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Objective: To evaluate the use of a novel battery-powered drill, enabling specimen requirement while drilling, in radiofrequency ablation of osteoid osteoma as an alternative to conventional orthopedic drills. Materials and methods: Between 2009 and 2013, altogether 33 patients underwent CT-guided radiofrequency ablation of an osteoid osteoma at our institution. To access the nidus of the clinically and radiologically suspected osteoid osteoma, a channel was drilled using the OnControl Bone Marrow Biopsy System (OBM, Arrow OnControl, Teleflex, Shavano Park, TX, USA) and a biopsy was taken. Procedure time (i.e., drilling including local anesthesia), amount of scans (i.e., single-shot fluoroscopy), radiation exposure, and the results of biopsy were investigated and compared retrospectively to a classical approach using either a manual bone biopsy system or a conventional orthopedic drill ( n = 10) after ethical review board approval. Results: Drilling the tract into the nidus was performed without problems in 22 of the 23 OBM cases. Median procedure time was 7 min compared to 13 min using the classical approach ( p < 0.001). Median amount CT scans, performed to control correct positioning of the drill was comparable with 26 compared to 24.5 ( p = NS) scans. Histologically, the diagnosis of osteoid osteomas could be determined in all 17 cases where a biopsy was taken. Radiofrequency ablation could be performed without problems in any case. Conclusions: The use of the battery-powered drill was feasible and facilitated the access to the osteoid osteoma's nidus offering the possibility to extract a specimen in the same step. [ABSTRACT FROM AUTHOR]

Objectives: To assess the feasibility, safety and efficacy of real-time MR guidance and thermometry of percutaneous laser disc decompression (PLDD). Methods: Twenty-four discs in 22 patients with chronic low-back and radicular pain were treated by PLDD using open 1.0-T magnetic-resonance imaging (MRI). A fluoroscopic proton-density-weighted turbo spin-echo (PDw TSE) sequence was used to position the laser fibre. Non-spoiled gradient-echo (GRE) sequences were employed for real-time thermal monitoring based on proton resonance frequency (PRF). Radicular pain was assessed over 6 months with a numerical rating scale (NRS). Results: PLDD was technically successful in all cases, with adequate image quality for laser positioning. The PRF-based real-time temperature monitoring was found to be feasible in practice. After 6 months, 21 % reported complete remission of radicular pain, 63 % at least great pain relief and 74 % at least mild relief. We found a significant decrease in the NRS score between the pre-intervention and the 6-month follow-up assessment ( P < 0.001). No major complications occurred; the single adverse event recorded, moderate motor impairment, resolved. Conclusions: Real-time MR guidance and PRF-based thermometry of PLDD in the lumbar spine under open 1.0-T MRI appears feasible, safe and effective and may pave the way to more precise operating procedures. Key Points: • Percutaneous laser disc decompression ( PLDD) is increasingly used instead of conventional surgery. • Open 1. 0- T MRI with temperature mapping seems technically successful in monitoring PLDD. • Pain relief was at least ' great' in 64 % of patients. • No major complications occurred. • Open 1. 0- T MRI appears a safe and effective option for patient- tailored PLDD. [ABSTRACT FROM AUTHOR]

Objectives: The aim of the present study was to intra-individually compare provocative discography and discoblock (disc analgesia) of idiopathic degenerated discs (IDD) results to each other, to clinical parameters, and to MRI findings. By this the value of both diagnostic features should be critically reevaluated. Methods: 31 intervertebral IDD (Pfirrmann III°–IV°) of 26 patients were analyzed for surgery decision making by combined discoblock/discography procedure in an open MRI at 1T. A correlation analysis was performed between the Dallas Discogram Scale, pain discrimination score (PDS: concordant/discordant/no pain), positive discoblock (Numerical Rating Scale [NRS] reduction by ≥3, 60min after intervention), presence of Modic changes or high intensity zones (HIZ), patient sex and age, intervention level, injection pressure and discography endpoint analysis (pain/pressure/anatomic/volume). Results: Concordant pain could be evoked in 35% of the IDDs whereas discoblock was positive in 64%. Patients’ age, sex, Dallas I, Dallas II, and Pfirrmann scores, as well as the presence of HIZ did not correlate to PDS or discoblock results. Discoblock correlated positively to concordant pain. Further positive correlation was found between PDS and intervention level/pressure, between discoblock and Modic changes/discography endpoint as well as between HIZ and discography endpoint. Conclusions: We suggest discoblock to be an additional tool for surgery decision making in patients with IDD because it correlates to concordant pain evoked by provocative discography as well as to presence of Modic changes. Additionally, assessment of a release instead of provocation of pain can be of advantage. [ABSTRACT FROM AUTHOR]

Thermal ablation has become a therapy of choice in the treatment of osteoid osteomas. To date, computed tomography has been the standard imaging modality for minimally invasive treatment regimes. We report a case of a 46-year-old man with a recurrent osteoid osteoma in the right tibial head after CT-guided drill excision and repeat treatment with laser ablation under open high-field MRI guidance. We describe the steps of the interventional MRI procedure and discuss related innovative guidance and monitoring features, and potential benefits of MRI compared with CT-guided techniques. In conclusion, MR-guided laser ablation was proved to be safe and effective. [ABSTRACT FROM AUTHOR]

Purpose: To assess the influence of different temporal sampling rates on the accuracy of the results from cerebral perfusion CTs in patients with an acute ischemic stroke. Material and Methods: Thirty consecutive patients with acute stroke symptoms received a dynamic perfusion CT (LightSpeed 16, GE). Forty millilitres of iomeprol (Imeron 400) were administered at an injection rate of 4 ml/s. After a scan delay of 7s, two adjacent 10mm slices at 80 kV and 190 mA were acquired in a cine mode technique with a cine duration of 49 s. Parametric maps for the blood flow (BF), blood volume (BV) and mean transit time (MTT) were calculated for temporal sampling intervals of 0.5, 1, 2, 3 and 4s using GE's Perfusion 3 software package. In addition to the quantitative ROI data analysis, a visual perfusion map analysis was performed. Results: The perfusion analysis proved to be technically feasible with all patients. The calculated perfusion values revealed significant differences with regard to the BF, BV and MTT, depending on the employed temporal resolution. The perfusion contrast between ischemic lesions and healthy brain tissue decreased continuously at the lower temporal resolutions. The visual analysis revealed that ischemic lesions were best depicted with sampling intervals of 0.5 and 1s. Conclusion: We recommend a temporal scan resolution of two images per second for the best detection and depiction of ischemic areas. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess the tolerance dose of gastric mucosa for single-fraction computed tomography (CT)-guided, high-dose-rate (HDR) brachytherapy of liver malignancies. Methods and Materials: A total of 33 patients treated by CT-guided HDR brachytherapy of liver malignancies in segments II and/or III were included. Dose planning was performed upon a three-dimensional CT data set acquired after percutaneous applicator positioning. All patients received gastric protection post-treatment. For further analysis, the contours of the gastric wall were defined in every CT slice using Brachyvision Software. Dose-volume histograms were calculated for each treatment and correlated with clinical data derived from questionnaires assessing Common Toxicity Criteria (CTC). All patients presenting symptoms of upper GI toxicity were examined endoscopically. Results: Summarizing all patients the minimum dose applied to 1 ml of the gastric wall (D(1 ml)) ranged from 6.3 to 34.2 Gy; median, 14.3 Gy. Toxicity was present in 18 patients (55%). We found nausea in 16 (69%), emesis in 9 (27%), cramping in 13 (39%), weight loss in 12 (36%), gastritis in 4 (12%), and ulceration in 5 patients (15%). We found a threshold dose D(1 ml) of 11 Gy for general gastric toxicity and 15.5 Gy for gastric ulceration verified by an univariate analysis (p = 0.01). Conclusions: For a single fraction, small volume irradiation we found in the upper abdomen a threshold dose D(1 ml) of 15.5 Gy for the clinical endpoint ulceration of the gastric mucosa. This in vivo assessment is in accordance with previously published tolerance data. [ABSTRACT FROM AUTHOR]

A 63-year-old female with a well-vascularized pulmonary metastasis of an endometrial stromal sarcoma (ESS) of 6x6 cm received selective embolization with 150-250 μm polyvinyl alcohol (Contour; Boston Scientific, Natick, MA, USA) via a bronchial artery. Postinterventional loss of perfusion was qualitatively estimated to be >80%. The lesion was located in direct proximity to the pulmonary hilar vessels. Owing to recurrent and sudden hemoptyses, an interdisciplinary tumor board assessed the risk of life-threatening blood loss to be greater than that of angiography with particle embolization and agreed on an endovascular approach. Hemoptysis did not recur in a follow-up period of six months. Initial clinical symptoms were noted 25 years ago. However, establishing a definite diagnosis has, for a long time, remained a histopathological challenge. [ABSTRACT FROM AUTHOR]

A 63-year-old female with a well-vascularized pulmonary metastasis of an endometrial stromal sarcoma (ESS) of 6×6 cm received selective embolization with 150-250 mm polyvinyl alcohol (Contour; Boston Scientific, Natick, MA, USA) via a bronchial artery. Postinterventional loss of perfusion was qualitatively estimated to be >80%. The lesion was located in direct proximity to the pulmonary hilar vessels. Owing to recurrent and sudden hemoptyses, an interdisciplinary tumor board assessed the risk of life-threatening blood loss to be greater than that of angiography with particle embolization and agreed on an endovascular approach. Hemoptysis did not recur in a follow-up period of six months. Initial clinical symptoms were noted 25 years ago. However, establishing a definite diagnosis has, for a long time, remained a histopathological challenge. [ABSTRACT FROM AUTHOR]

Hip joint loading is dominated by muscular activity. Thus, contact forces exceeding many times one's body weight are a consequence of imbalanced muscular activity. The objective was to analyze the influence of muscle atrophy after total hip arthroplasty on in vivo hip joint contact loading initially and long term. We hypothesized that an impaired periarticular muscle will lead to increase in vivo joint load, specifically in the long term. Using a group of nine patients with instrumented hip implants, contact forces and muscle status were analyzed one day prior to 3 and 50 months after joint arthroplasty. In vivo load measurements were performed for different activities of daily living (ADL). Pre- and postoperative pelvic CT scans were analyzed to assess the periarticular muscle status. Finally, the muscle morphologies and in vivo contact forces were compared. At 3 months after total hip arthroplasty we found a significant correlation of lower lean gluteus minimus muscle (GMin) volume with higher loads during all tested activities of daily living. 50 months postoperatively statistical analysis revealed lower lean volume of the gluteus maximus to be correlated with higher joint loads in walking. Our data generally show a good comparability between muscle status and joint contact forces and thus support our hypothesis that an impairment of periarticular musculature contributes to an increase of the in vivo joint loads after total hip arthroplasty. Effects were most pronounced during stair climbing and sit-down/stand-up from a chair at 3 months and during level walking at 50 months. • In vivo load measurements with instrumented hip implants were performed at 3 and 50 months postoperatively. • Individual CT analyses of the gluteal muscle status and fat ratio were performed at 3 and 50 months postoperatively. • The individual muscle status are influence the postoperative hip joint loading. • Our findings suggest that an impairment of periarticular musculature contributes to an increase of the in vivo joint loads. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Computed tomography in trauma patients using iterative reconstruction: reducing radiation exposure without loss of image quality," by Johannes Kahn and others in the April 6, 2015 issue.

Objectives: The aim of the present study was to histologically compare chondrotoxicity in surgically harvested intervertebral discs (IVDs) of patients following discoblock, discography, or no preoperative intervention.Methods: Thirty patients (IVD degeneration Modic ≥ 2°, Pfirrmann 3° or 4°) at L4/5 or L5/S1 who were planned for anterior lumbar interbody fusion were randomly assigned to three groups (open MRI: group DG - discography with gadobutrol; group DB - discoblock with bupivacaine at 4 weeks prior to surgery; group C - no intervention). The intervertebral discs were histologically evaluated and compared using ANOVA and Bonferroni tests for cell count, apoptosis, and proliferation.Results: A reduced cell count (groups DG vs. DB vs. C: 14.9 ± 7.1, 9.2 ± 3.8, and 16.6 ± 5.2 cells/mm2, respectively; p ANOVA = 0.016), increased apoptosis (groups DG vs. DB vs. C: 34.9 ± 10.2, 47.4 ± 16.3, 32.6 ± 12.2 %, respectively; p ANOVA = 0.039) and increased cell proliferation (post hoc pDB vs. DG or C p < 0.001; for 3-7 cell monoclonal cell nests: groups DG vs. DB vs. C: 2.4 ± 1, 3.9 ± 1, 2.2 ± 1.1, respectively; p interventionx nest size = 0.006) were found in the IVDs of patients in group DB.Conclusions: This in vivo study suggests that chondrotoxic effects occur in IVD cells after the intradiscal injection of bupivacaine but not after gadobutrol administration.Key Points: • Local bupivacaine administration to intervertebral discs leads to cell toxicity and proliferation. • Gadobutrol demonstrated no significant effect on cell count, apoptosis, or cell proliferation. • In vivo cytotoxicity was demonstrated histologically in humans for the first time. • Addition/administration of bupivacaine during discographies must be judged critically. [ABSTRACT FROM AUTHOR]

Background: TIPS is an established treatment for portal hypertension. The aim was to analyze how patient selection for TIPS implantation and procedural aspects have changed over 25 years. Routinely collected demographic, clinical, laboratory, and procedural data of 835 patients treated with TIPS in a single center were used. Time trends over the observational period from 1993 to 2018 were retrospectively analyzed. Descriptive statistical analysis was performed. Results: The most common indication for TIPS implantation has changed significantly from secondary prevention of variceal hemorrhage in the early years to treatment of recurrent ascites. During the observation period, increasingly more severely ill patients became TIPS candidates. There was little change in MELD scores over this period (in total median 13.00; IQR 10.00–18.00). The proportion of patients with Child–Pugh C cirrhosis increased. The most frequent underlying diseases in total were alcohol-related liver disease (66.5%) and viral hepatitis (11.9%). However, shares of cryptogenic liver cirrhosis, autoimmune hepatitis, and NASH increased over time. The proportion of patients post liver transplant also increased. While bare metal stents were standard in the past, use of covered stents increased. The success rate of TIPS (defined by successful implantation and a decrease in the portosystemic pressure gradient ≤ 12 mmHg) increased significantly over time. The total success rate according to this definition was 84.9%. Conclusion: The results of our analysis reflect technical developments in TIPS, especially in terms of stent material and gains in clinical experience, particularly regarding indications and patient selection for TIPS implantation. [ABSTRACT FROM AUTHOR]

The goal of this study was to compare magnetic resonance (MR) image quality at different field strengths for evaluating lesions in wrist and finger joints of patients with rheumatoid arthritis (RA) in order to determine whether the higher field strength provides diagnostic gain. The hand mainly affected in 17 RA patients was examined at 1.5 Tesla (T) and 3.0 T with comparable MR imaging (MRI) protocols. MR images were reviewed twice by two experienced radiologists using the Rheumatoid Arthritis MRI Scoring System (RAMRIS) of the OMERACT (Outcome Measures in Rheumatoid Arthritis Clinical Trials) group. Image quality was rated on a five-point scale using Friedmann's test and Kendall's W-test for statistical analysis. Image comparison revealed better image quality at higher field strength. Image quality of T1-weighted images was rated 14-22% better at 3.0 T compared with 1.5 T by both readers. Moreover, the rating for the T2-weighted-images acquired at 3.0 T was one point better in the five-point scale used. Inter-reader correlation for image quality, bone erosions/defects, edema and synovitis ranged between 0.6 and 0.9 at 3.0 T and between 0.6 and 0.8 at 1.5 T. Intra-reader correlation for these parameters was high at 0.8-1.0. MRI image quality of RA hands is superior at 3.0 T, while an acceptable image quality is achieved at 1.5 T, which improves the evaluation of extent of bone edema, synovitis and identification of small bone erosions. [ABSTRACT FROM AUTHOR]

Objectives: To compare the diagnostic value of ultrashort echo time (UTE) magnetic resonance imaging (MRI) for the lung versus the gold standard computed tomography (CT) and two T1-weighted MRI sequences in children. Methods: Twenty-three patients with proven oncologic disease (14 male, 9 female; mean age 9.0 + / − 5.4 years) received 35 low-dose CT and MRI examinations of the lung. The MRI protocol (1.5-T) included the following post-contrast sequences: two-dimensional (2D) incoherent gradient echo (GRE; acquisition with breath-hold), 3D volume interpolated GRE (breath-hold), and 3D high-resolution radial UTE sequences (performed during free-breathing). Images were evaluated by considering image quality as well as distinct diagnosis of pulmonary nodules and parenchymal areal opacities with consideration of sizes and characterisations. Results: The UTE technique showed significantly higher overall image quality, better sharpness, and fewer artefacts than both other sequences. On CT, 110 pulmonary nodules with a mean diameter of 4.9 + / − 2.9 mm were detected. UTE imaging resulted in a significantly higher detection rate compared to both other sequences (p < 0.01): 76.4% (84 of 110 nodules) for UTE versus 60.9% (67 of 110) for incoherent GRE and 62.7% (69 of 110) for volume interpolated GRE sequences. The detection of parenchymal areal opacities by the UTE technique was also significantly higher with a rate of 93.3% (42 of 45 opacities) versus 77.8% (35 of 45) for 2D GRE and 80.0% (36 of 45) for 3D GRE sequences (p < 0.05). Conclusion: The UTE technique for lung MRI is favourable in children with generally high diagnostic performance compared to standard T1-weighted sequences as well as CT. Key Points • Due to the possible acquisition during free-breathing of the patients, the UTE MRI sequence for the lung is favourable in children. • The UTE technique reaches higher overall image quality, better sharpness, and lower artefacts, but not higher contrast compared to standard post-contrast T1-weighted sequences. • In comparison to the gold standard chest CT, the detection rate of small pulmonary nodules small nodules ≤ 4 mm and subtle parenchymal areal opacities is higher with the UTE imaging than standard T1-weighted sequences. [ABSTRACT FROM AUTHOR]

Interfragmentary movements affect the quality and quantity of callus formation. The mounting plane of monolateral external fixators may give direction to those movements. Therefore, the aim of this study was to determine the influence of the fixator mounting plane on the process of fracture healing.Identically configured fixators were mounted either medially or anteromedially on the tibiae of sheep. Interfragmentary movements and ground reaction forces were evaluated in vivo during a nine week period. Histomorphological and biomechanical parameters described the bone healing processes.Changing only the mounting plane led to a modification of interfragmentary movements in the initial healing phase. The difference in interfragmentary movements between the groups was only significant during the first post-operative period. However, these initial differences in mechanical conditions influenced callus tissue formation significantly. The group with the anteromedially mounted fixator, initially showing significantly more interfragmentary movements, ended up with a significantly smaller callus diameter and a significantly higher callus stiffness as a result of advanced fracture healing. This demonstrates that the initial phase of healing is sensitive to mechanical conditions and influences the course of healing. Therefore, initial mechanical stability of an osteosynthesis should be considered an important factor in clinical fracture treatment. [Copyright &y& Elsevier]

To validate the collapsed cone (CC) algorithm against Monte Carlo (MC) simulations for model-based dose calculations in high-dose-rate (HDR) liver brachytherapy. Doses for liver brachytherapy treatment plans of 10 cases were retrospectively recalculated with a model-based approach using Monte Carlo n-Particle Code (MCNP) 6 (Dm,m-MC) and Oncentra Brachy ACE (Dm,m-ACE). Tissue segmentation consisted of assigning uniform compositions and mass densities to predefined Hounsfield Unit (HU) thresholds. Resulting doses were compared according to dose volume histogram parameters typical for clinical routine. These included the percentage liver volume receiving 5 Gy (V5Gy) or 10 Gy (V10Gy), the maximum dose to one cubic centimeter (D1cc) of organs at risk, the clinical target volume (CTV) fractions receiving 150% (V150), 100% (V100), 95% (V95) and 90% (V90) of the prescribed dose and the absolute doses to 95% (D95) and 90% (D90) of the CTV volumes. Doses from Oncentra Brachy ACE agreed well with MC simulations. Differences were seen far from the source, in low-density regions and bone structures. Median percentage deviations were 1.1% for the liver V5Gy and 0.4% for the liver V10Gy, with deviations of largest magnitude amounting to 2.2% and 1.0%, respectively. Organs at risk had median deviations ranging from 0.3% to 1.5% for D1cc, with outliers ranging up to 4.6%. CTV volume parameter deviations ranged between −1.5% and 0.5%, dose parameter deviations ranged mostly between −2% and 1%, with two outliers at −4.0% and −3.4% for a small CTV. [ABSTRACT FROM AUTHOR]

Background: In unresectable hepatocellular carcinoma several local ablative treatments are available. Among others, radiation based treatments such as stereotactic body radiotherapy (SBRT) and high-dose rate interstitial brachytherapy (HDR BT) have shown good local control rates.Methods: We conducted a dose comparison between actually performed HDR BT versus virtually planned SBRT to evaluate the respective clinically relevant radiation exposure to uninvolved liver tissue. Moreover, dose coverage and conformity indices were assessed.Results: Overall, 46 treatment sessions (71 lesions, 38 patients) were evaluated. HDR BT was applied in a single fraction with a dose prescription of 1 × 15 Gy. D98 was 17.9 ± 1.3 Gy, D50 was 41.8 ± 8.1 Gy. The SBRT was planned with a prescribed dose of 3 × 12.5 Gy (65%-Isodose), D98 was 50.7 ± 3.1 Gy, D2 was 57.0 ± 2.3 Gy, and D50 was 55.2 ± 2.3 Gy. Regarding liver exposure Vliver10GyBT was compared to Vliver15.9GySBRT, Vliver16.2GySBRT (EQD2 equivalent doses), and Vliver20GySBRT (clinically relevant dose), all results showed significant differences (p < .001). In a case by case analysis Vliver10GyBT was smaller than Vliver20GySBRT in 38/46 cases (83%). Dmean of the liver was significantly smaller in BT compared to SBRT (p < .001). GTV volume was correlated to the liver exposure and showed an advantage of HDR BT over SBRT in comparison of clinically relevant doses, and for EQD2 equivalent doses. The advantage was more pronounced for greater liver lesions The Conformity Index (CI) was significantly better for BT, while Healthy Tissue Conformity Index (HTCI) and Conformation Number (CN) showed an advantage for SBRT (p < .001).Conclusion: HDR BT can be advantageous in respect of sparing of normal liver tissue as compared to SBRT, while providing excellent target conformity. [ABSTRACT FROM AUTHOR]

Background: In computed tomography (CT) scans, artifacts caused by metallic orthopedic implants still hamper the visualization of important, periprosthetic tissues. Smart MAR metal artifact reduction tool is a promising three-stage, projection-based, post-processing algorithm.Purpose: To determine whether the Smart MAR tool improves subjective and objective image quality and diagnostic confidence in patients with orthopedic implants of the hip, spine, and shoulder.Material and Methods: Seventy-two patients with orthopedic screws, hip/shoulder replacement, or spine spondylodesis were included. CT scans were performed on a single-source multislice CT scanner, raw data were post-processed using Smart MAR. Image quality was evaluated both quantitatively (ROI-based) and qualitatively (rater-based) and compared to iterative reconstructions (ASIR V). As comparative standard for artificial prosthetic breaks or loosening, follow-up examinations were used.Results: Smart MAR reconstructions of the hip (n = 23), spine (n = 26), and shoulder (n = 23) showed a significantly reduced attenuation and noise of regions adjacent to metallic implants (P<0.002). Subjective image quality (P<0.005, shoulder P = 0.038/P = 0.046) and overall diagnostic confidence were higher in Smart MAR (all regions P<0.002). Signal-to-noise ratio (SNR; P = 0.72/P = 0.96) was not improved. Compared to standard ASIR V new, artificial metal extinctions (up to 50%) or periprosthetic hem lines (48%-73%) were introduced by Smart MAR.Conclusion: Smart MAR improved image quality of the hip, spine, and shoulder CT scans resulting in higher diagnostic confidence in evaluation of periprosthetic soft tissues. As shown for spine implants, it should be used with caution and as a complementary tool for evaluation of periprosthetic loosening or integrity of metal implant, as in many cases it introduced new artifacts. [ABSTRACT FROM AUTHOR]

Purpose: To compare treatment plans for interstitial high dose rate (HDR) liver brachytherapy with 192Ir calculated according to current-standard TG-43U1 protocol with model-based dose calculation following TG-186 protocol.Methods: We retrospectively evaluated dose volume histogram (DVH) parameters for liver, organs at risk (OARs) and clinical target volumes (CTVs) of 20 patient cases diagnosed with hepatocellular carcinoma (HCC) or metastatic colorectal cancer (mCRC). Dose calculations on a homogeneous water geometry (TG-43U1 surrogate) and on a computed tomography (CT) based geometry (TG-186) were performed using Monte Carlo (MC) simulations. The CTs were segmented based on a combination of assigning TG-186 recommended tissues to fixed Hounsfield Unit (HU) ranges and using organ contours delineated by physicians. For the liver, V5Gy and V10Gy were analysed, and for OARs the dose to 1 cubic centimeter (D1cc). Target coverage was assessed by calculating V150, V100, V95 and V90 as well as D95 and D90. For every DVH parameter, median, minimum and maximum values of the deviations of TG-186 from TG-43U1 were analysed.Results: TG-186-calculated dose was found to be on average lower than dose calculated with TG-43U1. The deviation of highest magnitude for liver parameters was -6.2% of the total liver volume. For OARs, the deviations were all smaller than or equal to -0.5 Gy. Target coverage deviations were as high as -1.5% of the total CTV volume and -3.5% of the prescribed dose.Conclusions: In this study we found that TG-43U1 overestimates dose to liver tissue compared to TG-186. This finding may be of clinical importance for cases where dose to the whole liver is the limiting factor. [ABSTRACT FROM AUTHOR]

Background: Measurement of iodine concentration from dual-energy or spectral computed tomography (CT) provides useful diagnostic information especially in patients suffering from malignant tumors of various origins. Purpose: The purpose of this study was to systematically investigate the accuracy of the measurement of iodine concentration, focusing on potential influencing factors and assessing its suitability for routine clinical use. Material and Methods: First, a 3D-printed cylindrical phantom was used to assess reliability of dual-energy CT-based iodine concentration measurement. Second, a semi-anthropomorphic phantom was used to evaluate the potential impact of positional variation of the target volume as typically seen in clinical scans. Finally, a reference vial was placed on the body surface of 38 patients undergoing abdominal dual-energy CT to analyze correlations between applied doses and patient diameters. Results: The position of the target volume within the cylindrical phantom and the applied dose level significantly influenced the magnitude of measured iodine concentrations (P < 0.001). We also found a significant difference in accuracy depending on target volume position in the semi-anthropomorphic phantom (P = 0.028). In patient scans, we observed an error of 19.6 ± 5.6% in iodine concentration measurements of a reference and significant, moderate to strong, negative correlations between measured iodine concentration, maximum patient diameter, and applied dose (maximum sagittal diameter: r = −0.455, P = 0.004; maximum coronal diameter: r=−0.517, P = 0.001; CTDIvol: r = −0.385, P = 0.017) Conclusion: Dual-energy CT-based iodine concentration measurement should be interpreted with caution. In clinical examinations, placement of a reference vial could be a potential solution to relativize errors. [ABSTRACT FROM AUTHOR]

Introduction: Tumour response in lung cancer treatment is monitored by measuring lesion size in computed tomography (CT). Spectral CT (SCT) offers additional information on tumour tissue besides morphology. We evaluated SCT iodine content (IC) and performed spectral slope analysis to assess the response of non-small-cell lung cancer (NSCLC) to chemoradiotherapy (CRT).Methods: Eighty-three patients with advanced NSCLC treated by CRT prospectively underwent single-phase, contrast-enhanced SCT. Evaluation of all patients included treatment response (RECIST 1.1), quantitative measurements as well as SCT IC determination and spectral slope analysis in NSCLC primaries. Measurements were performed at the maximum cross-diameter of tumours and in areas with high iodine values (hotspot analysis). Iodine difference (ΔIC) was calculated. Secondary outcome parameters were IC and spectral slopes in mediastinal lymph nodes (n = 61).Results: Twenty-four patients (29%) showed complete remission after CRT. Thirty-four patients (41%) had stable disease (SDSCT ) or partial regression (PRSCT ). Progressive disease (PDSCT ) was seen in 25 patients (30%). Hotspot analysis showed significantly higher iodine values in PDSCT than in SDSCT /PRSCT (P < 0.001). Ten patients (12%) with initially stable disease in SCT showed progressive disease during follow-up for up to 18 months (PDFU ). These patients also had significantly higher hotspot iodine values and ΔIC in the initial scan compared to patients with SD throughout the follow-up period (SDFU ) (29%) (P < 0.001). Enlarged lymph nodes showed significantly lower iodine content and a lower spectral slope pitch than normal-sized nodes (P = 0.003 to 0.029).Conclusion: Spectral CT-derived iodine content of NSCLC following CRT may help in predicting recurrence. Hotspot analysis and iodine heterogeneity allow the identification of residual vascularisation as an indicator of vital tumour tissue, indicating that IC might be a suitable imaging biomarker for predicting tumour progression. Iodine content and spectral slope analysis might also help in identifying metastatic lymph nodes. [ABSTRACT FROM AUTHOR]

Purpose: We determined whether the Smart MAR metal artifact reduction tool - a three-stage, projection-based, post processing algorithm - improves subjective and objective image quality and diagnostic confidence in patients with dental artifacts and suspected head and neck pathology compared to standard adaptive statistical iterative reconstructions (ASIR V) alone.Method: The study included 100 consecutive patients with nonremovable oral implants or dental fillings and suspected oropharyngeal cancer or abscess. CT raw data of a single-source multislice CT scanner were postprocessed using ASIR V alone and with additional Smart MAR reconstruction. Image quality of baseline ASIR V and Smart MAR-based reconstruction series was compared both quantitatively (5 regions of interest, ROIs) and qualitatively (two independent raters).Results: Additional Smart MAR reconstruction significantly seems to improve both attenuation and noise adjacent to implants and in more distant areas (all p < 0.001) compared to standard ASIR V reconstructions alone. Signal-to-noise ratio (SNR; p = 0.001) and contrast-to-noise ratio were improved significantly (CNR; p = 0.001). Smart MAR improved visualization of tumor/abscess (detected in 36 of 100 patients, 36%) and representative oropharyngeal tissue (p < 0.001). In 8 of 36 patients (22%), tumor was only detected in Smart MAR series. Mean total DLP was 506.8mGy*cm; average CTDIvol was 5.5 mGy.Conclusions: The supplementary use of the Smart MAR post-processing tool seems to significantly improve both subjective and objective image quality as well as diagnostic confidence and lesion detection in CT of the head and neck. In 22% of cases, the tumor was detected only in Smart MAR reconstructed images. [ABSTRACT FROM AUTHOR]

Background: Virtual monochromatic images (VMI) generated using spectral computed tomography (CT) are promising recently available tools to improve diagnostic performance in oncologic patients.Purpose: To investigate if virtual monochromatic datasets are suitable for clinical routine use in patients with hypervascularized abdominal tumors.Material and Methods: A total of 41 patients with hypervascularized hepatocellular carcinoma (HCC), renal cell carcinoma (RCC), or neuroendocrine tumors (NET) were enrolled in the study; 451 CT series were analyzed. In an intra-individual study design, virtual monochromatic datasets of the arterial phase of each scan were computed. Image quality was assessed objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR) and subjectively by using five-point Likert-scales. The volume CT dose index (CTDIvol) was taken from each radiation dose report. The increase in reading time was estimated from the increase in the number of images.Results: Intra-individual comparison of the spectral mode in the arterial phase with the portal venous phase revealed no significant increase in the applied dose. SNR, CNRtumor-to-liver , and CNRtumor-to-muscle were significantly increased by lowering virtual monochromatic energy. Subjective image quality scores revealed an increase of contrast in low energy datasets, resulting in significantly higher diagnostic confidence, but an increased image noise at low energies. While diagnostic confidence improved, taking all datasets into account resulted in a significantly longer estimated reading time.Conclusion: In clinical practice, the use of low energy VMI improved diagnostic confidence without a significant increase in dose. The main disadvantage is a decrease in efficiency due to longer reading times. [ABSTRACT FROM AUTHOR]

Background Endovascular aneurysm repair (EVAR) requires lifelong surveillance by computed tomography angiography (CTA). This is attended by a substantial accumulation of radiation exposure. Iterative reconstruction (IR) has been introduced to approach dose reduction. Purpose To evaluate adaptive statistical iterative reconstruction (ASIR) at different levels of tube voltage concerning image quality and dose reduction potential in follow-up post EVAR. Material and Methods One hundred CTAs in 67 patients with EVAR were examined using five protocols: protocol A (n = 40) as biphasic standard using filtered back projection (FBP) at 120 kV; protocols B (n = 40), C (n = 10), and D1 (n = 5) biphasic using ASIR at 120, 100, and 80 kV, respectively; and protocol D2 (n = 5) with a monophasic splitbolus ASIR protocol at 80 kV. Image quality was assessed quantitatively and qualitatively. Applied doses were determined. Results Applied doses in ASIR protocols were significantly lower than FBP standard (up to 75%). Compared to protocol A, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) (e.g. arterial CNR intra-/extra-stent lumen: A = 35.4 ± 13.5, B = 34.2 ± 10.0, C = 29.6 ± 6.8, D1 = 32.1 ± 6.3, D2 = 40.8 ± 23.1) in protocol B were equal and in protocols C and D equal to partially inferior, however not decisive for diagnostic quality. Subjective image quality ratings in all protocols were good to excellent without impairments of diagnostic confidence (A-D2: 5), with high inter-rater agreement (60-100%). Conclusion ASIR contributes to significant dose reduction without decisive impairments of image quality and diagnostic confidence. We recommend an adapted follow-up introducing ASIR and combined low-kV in the long-term surveillance after EVAR. [ABSTRACT FROM AUTHOR]

Background: Total hip arthroplasty (THA) is in most cases improving patients´ life quality immediately after surgery. However, a closer look at these patients, especially with modern gait analysis methods, reveals also negative consequences due to the surgical approach related injury to the pelvic muscles. We hypothesized that this damage will have a negative impact on hip joint contact forces during activities of daily living (ADL). Methods: 10 patients undergoing THA received an instrumented hip joint implant enabling real time in vivo measurements of hip joint loads using a direct lateral approach. Pre- and 3 months postoperative computed tomography (CT) scans were used for evaluation of the periarticular muscle status, using muscle volume, fat ratio and lean muscle volume as parameters. An analysis of in vivo hip contact forces was made 3 months after THA during ADL (walking, stair climbing, chair rising and sitting) and correlated with the morphology of the periarticular muscles. Results: We found a significant decrease of volume by 25% (-3 to -45, p = 0.005) and increase in fat ratio of the Gluteus Minimus (Gmin), resulting in a decrease in lean muscle volume of 28% (-48 to 0, p = 0.008). This was accompanied by an inverse development in the Tensor Fasciae Latae (TFL) resulting in a lean muscle volume increase of 34% (-2 to -102, p = 0.013). Changes in Gluteus Medius (Gmed) and Gluteus Maximus (Gmax) have not been observed in the short-term follow up. A decreased Gmin lean muscle volume was found to strongly correlate with high in vivo joint contact forces in all tested ADL. Conclusion: The decrease of Gmin volume can be seen as a direct effect of THA surgery, whereas the increase of TFL might compensate for loss of Gmin volume. Lean muscle volume and fat ratio were better predictors for joint contact forces than total muscle volume. These effects were most pronounced during sitting down and standing up due to the higher demand on the gluteal muscles during these activities. [ABSTRACT FROM AUTHOR]

Background Placement of central venous port catheters (CVPS) and peripherally inserted central catheters (PICC) is an integral component of state-of-the-art patient care. In the era of increasing cost awareness, it is desirable to have more information to comprehensively assess both procedures. Purpose To perform a retrospective analysis of interventional radiologic implantation of CVPS and PICC lines in a large patient population including a cost analysis of both methods as well as an investigation the learning curve in terms of the interventions' durations. Material and Methods All CVPS and PICC line related interventions performed in an interventional radiology department during a three-year period from January 2011 to December 2013 were examined. Documented patient data included sex, venous access site, and indication for CVPS or PICC placement. A cost analysis including intervention times was performed based on the prorated costs of equipment use, staff costs, and expenditures for disposables. The decrease in intervention duration in the course of time conformed to the learning curve. Results In total, 2987 interventions were performed by 16 radiologists: 1777 CVPS and 791 PICC lines. An average implantation took 22.5 ± 0.6 min (CVPS) and 10.1 ± 0.9 min (PICC lines). For CVPS, this average time was achieved by seven radiologists newly learning the procedures after performing 20 CVPS implantations. Total costs per implantation were €242 (CVPS) and €201 (PICC lines). Conclusion Interventional radiologic implantations of CVPS and PICC lines are well-established procedures, easy to learn by residents, and can be implanted at low costs. [ABSTRACT FROM AUTHOR]

Background Context: An overload of the paravertebral muscles after surgical intervention is suggested to be the major cause of postoperative pain. In cross-sectional area analyses, increased atrophy of the multifidus muscle (MF) after conventional open versus minimally invasive posterior lumbar interbody fusion (PLIF) has been described. The three-dimensional characteristics of the paravertebral muscles and separate evaluation of the longissimus muscle (LS) have not been addressed in analyses thus far.Purpose: The purpose of the present study was to compare the MF and LS volume atrophy and fatty degeneration between single-level minimally invasive transforaminal lumbar interbody fusion (miTLIF) and conventional midline approach-based PLIF (coPLIF) of L4/L5 or L5/S1 at the index and superior adjacent segments.Design: This was a prospective, randomized, controlled, non-blinded study.Patient Sample: Fifty patients with single-level segment degeneration (Pfirrmann ≥III and Modic ≥3) of L4/L5 or L5/S1 not requiring decompression were randomly assigned to two groups.Outcome Measures: Paraspinal lumbar residual muscle tissue volume, change in the relative fat content of MF and LS at the index and superior adjacent segments, and clinical parameters, including a visual analogue scale (VAS) for low back pain and the Oswestry Disability Questionnaire (ODI) were the outcome measures in this study.Methods: Twenty-five patients were treated with miTLIF, and the remaining patients were treated with coPLIF (both with transpedicular fixation). Clinical scoring was performed preoperatively and at 1 week and 12 months postoperatively, and computed tomography was performed at the latter two follow-ups.Results: The LS damage at the index segment was similar in both groups (3% greater fat content increase in the coPLIF vs. the miTLIF group, p=.032), whereas MF atrophy and degeneration were increased (p<.001) in the coPLIF group. At the adjacent segment, muscle atrophy and increased fatty infiltration (p<.05) were minimal in both muscles but were similar in both groups. Visual analogue scale and ODI scores improved (p<.001), without differences between the groups.Conclusions: The muscle damage after miTLIF was inferior to that after coPLIF; spatially, however, the muscle sparing was predominantly attributed to the MF and, surprisingly, not to the LS. [ABSTRACT FROM AUTHOR]

In the last few years, minimally invasive tumor ablation performed by interventional radiologists has gained increasing relevance in oncologic patient care. Limitations of thermal ablation techniques such as radiofrequency ablation (RFA), microwave ablation (MWA), and laser-induced thermotherapy (LITT), including large tumor size, cooling effects of adjacent vessels, and tumor location near thermosensitive structures, have led to the development of image-guided high-dose-rate (HDR) brachytherapy, especially for the treatment of liver malignancies. This article reviews technical properties of image-guided brachytherapy, indications and its current clinical role in multimodal cancer treatment. Furthermore, perspectives of this novel therapy option will be discussed. [ABSTRACT FROM AUTHOR]

Background: Rising numbers of computed tomography (CT) examinations worldwide have led to a focus on dose reduction in the latest developments in CT technology. Iterative reconstruction (IR) models bear the potential to effectively reduce dose while maintaining adequate image quality.Purpose: To assess the impact of adaptive statistical iterative reconstruction (ASIR) technique on dose reduction and image quality in a dedicated whole body CT (WBCT) protocol for trauma patients.Material and Methods: A total of 122 subjects with multiple trauma was prospectively included in our study. Subjects who had to undergo a WBCT following a severe trauma were randomly assigned to two different groups: Group A was examined with an ASIR protocol for the body series (n = 64), group B (n = 58) was examined using a standard filtered back projection (FBP) protocol. Image quality was assessed both quantitatively by calculating signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs) and qualitatively by two observers who evaluated image quality using a 5-point scale system. Applied dose was analyzed as CTDIvol (mGy), total DLP (mGyxcm), and effective dose (mSv).Results: Applied dose for the body series in group A was about 23% lower than in group B (P < 0.05). SNR and CNRs for different tissues were not significantly different. Subjective image quality ratings were excellent and showed no significant difference, with a high inter-reader agreement.Conclusion: ASIR contributes to a relevant dose reduction without any loss of image quality in a dedicated WBCT protocol for patients with multiple trauma. [ABSTRACT FROM AUTHOR]

The first objective of this study was to determine normative digital X-ray radiogrammetry (DXR) values, based on original digital images, in a pediatric population (aged 6-18 years). The second aim was to compare these reference data with patients suffering from distal radius fractures, whereas both cohorts originated from the same geographical region and were evaluated using the same technical parameters as well as inclusion and exclusion criteria. DXR-BMD and DXR-MCI of the metacarpal bones II-IV were assessed on standardized digital hand radiographs, without printing or scanning procedures. DXR parameters were estimated separately by gender and among six age groups; values in the fracture group were compared to age- and gender-matched normative data using Student's t tests and Z scores. In the reference cohort (150 boys, 138 girls), gender differences were found in bone mineral density (DXR-BMD), with higher values for girls from 11 to 14 years and for boys from 15 to 18 years (p < 0.05). Girls had higher normative metacarpal index (DXR-MCI) values than boys, with significant differences at 11-14 years (p < 0.05). In the case-control investigation, the fracture group (95 boys, 69 girls) presented lower DXR-BMD at 15-18 years in boys and 13-16 years in girls vs. the reference cohort (p < 0.05); DXR-MCI was lower at 11-18 years in boys and 11-16 years in girls (p < 0.05). Mean Z scores in the fracture group for DXR-BMD were -0.42 (boys) and -0.46 (girls), and for DXR-MCI were -0.51 (boys) and -0.53 (girls). These findings indicate that the fully digital DXR technique can be accurately applied in pediatric populations ≥ 6 years of age. The lower DXR-BMD and DXR-MCI values in the fracture group suggest promising early identification of individuals with increased fracture risk, without the need for additional radiation exposure, enabling the initiation of prevention strategies to possibly reduce the incidence of osteoporosis later in life. [ABSTRACT FROM AUTHOR]

Purpose: Computed tomography (CT) or magnetic resonance imaging (MRI) guided brachytherapy provides high tumor control rates in hepatocellular carcinoma (HCC) and colorectal liver metastases. In contrast to thermal ablation methods such as radiofrequency ablation (RFA), much less restrictions apply with respect to tumor location or size. In this study, we determined the efficacy and safety of CT- or MRI-guided brachytherapy in metastatic melanoma. Material and methods: Fifty-two metastases of malignant melanoma in 14 patients were included in this retrospective study. Local tumor control and safety were evaluated as primary and secondary endpoints. Furthermore, we evaluated overall survival and progression free survival. Tumor locations were liver (n = 31), lung (n = 15), adrenal (n = 3), lymph nodes (n = 2), and kidney (n = 1). Treatment planning was performed using three-dimensional CT or MRI data acquired after percutaneous applicator positioning under CT or open MRI guidance. Subsequently, single fraction high-dose-rate (HDR) brachytherapy was applied using a 192Iridium source. Clinical and cross-sectional follow- up were performed every 3 months post intervention. Results: The median diameter of treated lesions was 1.5 cm (range: 0.7-10 cm). Doses between 15 and 20 Gy were applied (median dose: 19.9 Gy). The mean irradiation time ranged between 7-45 minutes. After treatment, there was one patient with a cholangitis. After a median follow up of five months, the median local tumor control was 90%. The median overall survival of the patients was 8 months. The median progression free survival of the patients was 6 months. Conclusion: Image-guided HDR brachytherapy is a safe and effective treatment procedure in metastatic malignant melanoma. [ABSTRACT FROM AUTHOR]

Purpose: Computed tomography (CT) or magnetic resonance imaging (MRI) guided brachytherapy provides high tumor control rates in hepatocellular carcinoma (HCC) and colorectal liver metastases. In contrast to thermal ablation methods such as radiofrequency ablation (RFA), much less restrictions apply with respect to tumor location or size. In this study, we determined the efficacy and safety of CT- or MRI-guided brachytherapy in metastatic melanoma. Material and methods: Fifty-two metastases of malignant melanoma in 14 patients were included in this retrospective study. Local tumor control and safety were evaluated as primary and secondary endpoints. Furthermore, we evaluated overall survival and progression free survival. Tumor locations were liver (n = 31), lung (n = 15), adrenal (n = 3), lymph nodes (n = 2), and kidney (n = 1). Treatment planning was performed using three-dimensional CT or MRI data acquired after percutaneous applicator positioning under CT or open MRI guidance. Subsequently, single fraction high-dose-rate (HDR) brachytherapy was applied using a 192Iridium source. Clinical and cross-sectional follow- up were performed every 3 months post intervention. Results: The median diameter of treated lesions was 1.5 cm (range: 0.7-10 cm). Doses between 15 and 20 Gy were applied (median dose: 19.9 Gy). The mean irradiation time ranged between 7-45 minutes. After treatment, there was one patient with a cholangitis. After a median follow up of five months, the median local tumor control was 90%. The median overall survival of the patients was 8 months. The median progression free survival of the patients was 6 months. Conclusion: Image-guided HDR brachytherapy is a safe and effective treatment procedure in metastatic malignant melanoma. [ABSTRACT FROM AUTHOR]

Objectives: To assess the impact of ASIR (adaptive statistical iterative reconstruction) and lower tube potential on dose reduction and image quality in chest computed tomography angiographies (CTAs) of patients with pulmonary embolism. Materials and methods: CT data from 44 patients with pulmonary embolism were acquired using different protocols-Group A: 120 kV, filtered back projection, n = 12; Group B: 120 kV, 40 % ASIR, n = 12; Group C: 100 kV, 40 % ASIR, n = 12 and Group D: 80 kV, 40 % ASIR, n = 8. Normalised effective dose was calculated; image quality was assessed quantitatively and qualitatively. Results: Normalised effective dose in Group B was 33.8 % lower than in Group A ( p = 0.014) and 54.4 % lower in Group C than in Group A ( p < 0.001). Group A, B and C did not show significant differences in qualitative or quantitative analysis of image quality. Group D showed significantly higher noise levels in qualitative and quantitative analysis, significantly more artefacts and decreased overall diagnosability. Best results, considering dose reduction and image quality, were achieved in Group C. Conclusions: The combination of ASIR and lower tube potential is an option to reduce radiation without significant worsening of image quality in the diagnosis of pulmonary embolism. Key Points: • Iterative algorithms and lowering of tube potential reduce radiation without compromising interpretability • 40 % ASIR and 100 kV tube potential led to a 54.4 % dose reduction • 40 % ASIR and 80 kV tube potential led to significantly worse image quality [ABSTRACT FROM AUTHOR]

Purpose: To assess ASIR (adaptive statistical iterative reconstruction) technique regarding dose reduction and its impact on image quality in evaluation CTs of potential kidney donors. Materials and Methods: Between May and November 2013, a prospective study of 53 assumingly healthy potential kidney donors was conducted. The subjects underwent abdominal evaluation CT prior to the planned explantation of a kidney and were randomly divided into 2 groups: Group A was examined with an ASIR 40 protocol (n=26), group B (n=27) was examined using a standard FBP (filtered back projection) protocol. Image quality was assessed both quantitatively (by obtaining attenuation values in different organ regions and calculating SNR and CNRs) and qualitatively (by two observers who evaluated image quality using a 5-point scale system). Applied dose was analyzed as CTDIvol (mGy), total DLP (mGy×cm) and effective dose (mSv). Results: Applied dose in group A was about 26% lower than in group B (p<0.05). Between both groups, dose determining parameters such as scan length and patients' body diameter showed no significant difference. SNR (signal-to-noise ratio) was significantly higher in group A (p<0.05). CNRs (contrast-to-noise ratios) for different tissues were not significantly different. Observer rated image quality showed no significant difference. Conclusion: ASIR can contribute to a relevant dose reduction without any loss of image quality in CT scans for evaluating potential kidney donors. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To assess ASIR (adaptive statistical iterative reconstruction) technique regarding dose reduction and its impact on image quality in evaluation CTs of potential kidney donors. Materials and methods: Between May and November 2013, a prospective study of 53 assumingly healthy potential kidney donors was conducted. The subjects underwent abdominal evaluation CT prior to the planned explantation of a kidney and were randomly divided into 2 groups: Group A was examined with an ASIR 40 protocol (n =26), group B (n =27) was examined using a standard FBP (filtered back projection) protocol. Image quality was assessed both quantitatively (by obtaining attenuation values in different organ regions and calculating SNR and CNRs) and qualitatively (by two observers who evaluated image quality using a 5-point scale system). Applied dose was analyzed as CTDIvol (mGy), total DLP (mGy×cm) and effective dose (mSv). Results: Applied dose in group A was about 26% lower than in group B (p <0.05). Between both groups, dose determining parameters such as scan length and patients’ body diameter showed no significant difference. SNR (signal-to-noise ratio) was significantly higher in group A (p <0.05). CNRs (contrast-to-noise ratios) for different tissues were not significantly different. Observer rated image quality showed no significant difference. Conclusion: ASIR can contribute to a relevant dose reduction without any loss of image quality in CT scans for evaluating potential kidney donors. [Copyright &y& Elsevier]

Background. The aim of this study was to evaluate imaging-based response to standardized neoadjuvant chemotherapy (NACT) regimen by dynamic contrast-enhanced magnetic resonance mammography (DCE-MRM), whereas MR images were analyzed by an automatic computer-assisted diagnosis (CAD) system in comparison to visual evaluation. MRI findings were correlated with histopathologic response to NACT and also with the occurrence of metastases in a follow-up analysis. Patients and methods. Fifty-four patients with invasive ductal breast carcinomas received two identical MRI examinations (before and after NACT; 1.5T, contrast medium gadoteric acid). Pre-therapeutic images were compared with post-therapeutic examinations by CAD and two blinded human observers, considering morphologic and dynamic MRI parameters as well as tumor size measurements. Imaging-assessed response to NACT was compared with histopathologically verified response. All clinical, histopathologic, and DCE-MRM parameters were correlated with the occurrence of distant metastases. Results. Initial and post-initial dynamic parameters significantly changed between pre- and post-therapeutic DCE-MRM. Visually evaluated DCE-MRM revealed sensitivity of 85.7%, specificity of 91.7%, and diagnostic accuracy of 87.0% in evaluating the response to NACT compared to histopathology. CAD analysis led to more false-negative findings (37.0%) compared to visual evaluation (11.1%), resulting in sensitivity of 52.4%, specificity of 100.0%, and diagnostic accuracy of 63.0%. The following dynamic MRI parameters showed significant associations to occurring metastases: Post-initial curve type before NACT (entire lesions, calculated by CAD) and post-initial curve type of the most enhancing tumor parts after NACT (calculated by CAD and manually). Conclusions. In the accurate evaluation of response to neoadjuvant treatment, CAD systems can provide useful additional information due to the high specificity; however, they cannot replace visual imaging evaluation. Besides traditional prognostic factors, contrast medium-induced dynamic MRI parameters reveal significant associations to patient outcome, i.e. occurrence of distant metastases. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the accuracy, safety and efficacy of magnetic resonance imaging (MRI)-guided facet joint injection therapy using a 1.0-T open MRI.Methods: One hundred and sixty-six facet joint blocks in 45 patients with lower back pain were performed under MR fluoroscopic guidance using a proton-density-weighted turbo-spin-echo sequence. An in-room monitor, wireless MR-mouse for operator-controlled multiplanar navigation, a flexible surface coil and MR-compatible 20-G needle were used. Clinical outcome was evaluated by questionnaire before intervention and after 1 week, 3, 6 and 12 months using a numerical visual analogue scale (VAS).Results: All facet joint blocks were considered technically successful with distribution of the injectant within and/or around the targeted facet joint. No major complications occurred. The final outcome analysis included 38 patients. An immediate effect was reported by 63 % of the patients. A positive mid-/long-term effect was seen in 13 patients (34 %) after 6 months and in 9 patients (24 %) after 12 months. Mean VAS was reduced from 7.1 ± 1.7 (baseline) to 3.5 ± 2.2, 4.1 ± 3.0, 3.8 ± 2.9 and 4.6 ± 2.9 at 1 week, 3, 6 and 12 months (P < 0.01).Conclusions: MR-guided facet joint injection therapy of the lumbosacral spine is accurate, safe and efficient in the symptomatic treatment of lower back pain. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To compare the diagnostic efficacy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) vs. multidetector computed tomography (MDCT) for the detection and classification of focal liver lesions, differentiated also for lesion entity and size; a separate analysis of pre- and postcontrast images as well as T2-weighted MRI sequences of focal and exclusively solid lesions was integrated. Methods: Twenty-nine patients with 130 focal liver lesions underwent MDCT (64-detector-row; contrast medium iopromide; native, arterial, portalvenous, venous phase) and MRI (1.5-T; dynamic and tissue-specific phase 20min after application of Gd-EOB-DTPA). Hepatic lesions were verified against a standard of reference (SOR). CT and MR images were independently analysed by four blinded radiologists on an ordinal 6-point-scale, determining lesion classification and diagnostic confidence. Results: Among 130 lesions, 68 were classified as malignant and 62 as benign by SOR. The detection of malignant and benign lesions differed significantly between combined and postcontrast MRI vs. MDCT; overall detection rate was 91.5% for combined MRI and 80.4% for combined MDCT (p <0.05). Considering all four readers together, combined MDCT achieved sensitivity of 66.2%, specificity of 79.0%, and diagnostic accuracy of 72.3%; combined MRI reached superior diagnostic efficacy: sensitivity 86.8%, specificity 94.4%, accuracy 90.4% (p <0.05). Differentiated for lesion size, in particular lesions <20mm revealed diagnostic benefit by MRI. Postcontrast MRI also achieved higher overall sensitivity, specificity, and accuracy compared to postcontrast MDCT for focal and exclusively solid liver lesions (p <0.05). Conclusion: Combined and postcontrast Gd-EOB-DTPA-enhanced MRI provided significantly higher overall detection rate and diagnostic accuracy, including low inter-observer variability, compared to MDCT in a single centre study. [Copyright &y& Elsevier]

Objective: To evaluate the diagnostic potential of a multi-factor analysis of morphometric parameters and signal characteristics of brain tumours and peritumoural areas for distinguishing WHO-grade II and III gliomas at magnetic resonance imaging (MRI). Methods: MR examinations of 108 patients with histologically proven World Health Organization (WHO) grade II and III gliomas were included. Morphological criteria and MR signal characteristics were evaluated. The data were subjected to a multifactorial logistic regression analysis to differentiate between grade II and grade III gliomas. The discriminatory power was assessed by receiver operating characteristic (ROC). Results: Logistic regression analysis showed that WHO grade II and III can be distinguished based on contrast enhancement, cortical involvement, margin of the enhancing lesion and maximum diameter (width and length) of the peritumoural area (the so-called tumour infiltration zone). With the final model of logistic regression analysis and with the cut-off value ≥ 0.377, WHO grade III glioma is predicted with a sensitivity of 71.0 % and a specificity of 80.4 %. Conclusion: Measurement of maximum diameter of peritumoural area, contrast enhancement as well as cortical involvement and the margin of the contrast-enhancing lesion can be used easily in clinical routine to adequately distinguish WHO grade II from grade III gliomas. Key Points: • MRI offers new information concerning WHO-grade II and III gliomas. • The differentiation between such tumour grades is important for therapeutic decisions. • We assessed differences in enhancement, cortical involvement, margins and peritumoural appearances. • WHO grade III gliomas can be predicted with reasonable sensitivity and specificity. [ABSTRACT FROM AUTHOR]

Objective. This study aims to assess the impact of adaptive statistical iterative reconstruction (ASIR) on CT imaging quality, diagnostic interpretability, and radiation dose reduction for a proven CT acquisition protocol for total body trauma. Methods. 18 patients with multiple trauma (ISS ⩾ 16) were examined either with a routine protocol (n = 6), 30% (n = 6), or 40% (n = 6) of iterative reconstruction (IR) modification in the raw data domain of the routine protocol (140 kV, collimation: 40, noise index: 15). Study groups were matched by scan range and maximal abdominal diameter. Image noise was quantitatively measured. Image contrast, image noise, and overall interpretability were evaluated by two experienced and blinded readers. The amount of radiation dose reductions was evaluated. Results. No statistically significant differences between routine and IR protocols regarding image noise, contrast, and interpretability were present. Mean effective dose for the routine protocol was 25.3 ± 2.9 mSv, 19.7 ± 5.8 mSv for the IR 30, and 17.5 ± 4.2 mSv for the IR 40 protocol, that is, 22.1% effective dose reduction for IR 30 (P = 0.093) and 30.8% effective dose reduction for IR 40 (P = 0.0203). Conclusions. IR does not reduce study interpretability in total body trauma protocols while providing a significant reduction in effective radiation dose. [ABSTRACT FROM AUTHOR]

Osteoid osteoma (OO) is a common benign tumor of the bone and is typically treated by thermal ablation with computed tomography (CT) guidance. Only a few cases of multicentric OO have been described. We here report the case of an 11-yearold boy with multicentric OO of the right femur treated with laser ablation under open high-field MRI guidance. The steps of the interventional MRI procedure are described, discussing the benefits and disadvantages of MRI versus CT guidance especially with regard to younger patients. [ABSTRACT FROM AUTHOR]

Background: In amyotrophic lateral sclerosis (ALS) patients with respiratory impairment and/or advanced disease, performing even mild sedation - as is usually necessary for percutaneous endoscopic gastrostomy (PEG) placements - is fraught with risk. These patients are often referred to Interventional Radiology for alternative percutaneous gastrostomy tube placement options. Purpose: To report our experience with CT fluoroscopy-guided percutaneous gastrostomy with a novel loop gastropexy and peel-away sheath trocar technique in ALS patients as an alternative to endoscopic techniques. Material and Methods: A consecutive series of 31 amyotrophic lateral sclerosis patients in whom endoscopic gastrostomy was considered too dangerous or impossible to perform underwent CT-guided percutaneous gastropexy and gastrostomy and prospective follow-up. All procedures were performed with a 15 FR Freka® Pexact gastrostomy kit, a 16-row CT scanner (Aquilion 16) and single shot CT fluoroscopy mode. Results: The procedure was performed successfully in 30 of 31 patients (20 men, 11 women; median age 60 years, range 38-80 years). In the remaining case the stomach was punctured under CT fluoroscopy and CO2 insufflation was initiated thereafter, leading to successful gastrostomy without prior gastropexy and without further adverse events during follow-up. Two patients reported unproblematic exchange of a balloon tube due to skin irritations with no further adverse events. One patient reported accidental displacement of an exchanged new balloon tube in domestic environment due to balloon leakage: A new balloon tube was easily re-inserted in a hospital the same day. No serious adverse events such as peritonitis, persistent local bleeding, systemic blood loss, or any local infection requiring surgical intervention were observed. Until August 11, 2011 follow-up resulted in 7473 cumulative gastrostomy-days from the date of first placement. Conclusion: Initial results suggest that the described technique under CT guidance is feasible and safe and may especially be advantageous in cases where endoscopic gastrostomy and sedation are contraindicated. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: Verification of MR-guidance with image acquisitions slower than 1 image per second as it is inevitable for some interventions. Therefore, we quantified solely the effect of acquisition-time on the efficiency of MR-guided interventions in a static phantom study. Materials and methods: We measured the duration, accuracy and error rate of simulated interventions for different acquisition-times using a simplified interventional setup. All measurements were performed in a 1.0T open MRI scanner. Imaging was performed with a gradient-echo sequence (flipangle=20°; TR/TE=12/6ms; voxelsize=1mm×1mm; slicethickness=5mm; FOV=230mm×200mm; acquisition-time=1s). Variable acquisition times were simulated with intermediate pauses of 0, 1, 2, 3, 4 and 5s. The interventions were performed by a total of 20 volunteers including 7 experienced interventionalists. Results: The mean duration of the intervention was 2min. Significant differences between experienced and unexperienced volunteers were limited to the localization of the image plane and corrections made. The mean accuracy was 5.6mm. The time to localize the image plane increased with deceleration of imaging from 24s to 49s. A similar increase was observed for the intervention time (55–108s). A significant influence of the acquisition-time on durations and corrections was only found with acquisition-times greater than 4s per image. Conclusion: Even image rates of several seconds per image are sufficient enough for efficient interventions in static organs. Thus, the main attention has to be turned on the visibility of the needle when sequences are optimized for MR-guidance. The minimization of imaging speed is rather of secondary interest. [Copyright &y& Elsevier]

Laparoscopic radiofrequency ablation (LapRFA) is an established procedure for liver tumors in patients who are unsuitable for resection. A novel technique of magnetic resonance (MR) guided needle positioning during LapRFA was developed and compared to conventional ultrasound (US) guidance in a phantom model. MR-guided procedures were conducted in a 1.0 tesla high field open MR using an MR compatible endoscope and camera. The ultrasound-guided procedure was performed with a clinically established laparoscopy setup and a 2D laparoscopic US probe. During both techniques an identical monopolar non-ferromagnetic RFA needle and a silicon-based phantom model were applied. Finally needle positioning was performed by two surgeons and one interventionalist. Time to needle placement and number of trials were recorded and statistically analyzed. MR-guided needle positioning under laparoscopic control was technically feasible. Average time to correct needle placement was 2′′ 6″″ in the LapUS group and 1′′ 54″″ in the MR group. The number of trials was 3.2 in the LapUS group and 2.6 in the MR group. Image quality was assessed by all participants. MR images showed a better tissue to tumor contrast and allowed an improved orientation due to multiplanar visualization. MR-guided laparoscopic RFA is a promising technique offering multiplanar needle positioning with high soft tissue contrast with immediate therapy control. In a phantom model it showed comparable results regarding needle positioning to the established technique of laparoscopic US guidance. [ABSTRACT FROM AUTHOR]

Objective: To investigate the performance of an open MRI system at its conceptual limits by examining excessively obese patients who otherwise could not receive adequate imaging examinations.Methods: Twenty-six excessively obese patients (BMI ≥ 35, average age 46) where CT, standard MR or ultrasound examinations were not possible or not conclusive were referred to an open MRI system at 1.0 Tesla. Image quality was measured by SNR and CNR with the integrated body coil for obese patients and optimal body coils for a regular weight control group (average BMI 23, average age 30). MRI findings were evaluated by a diagnostic impact matrix.Results: SNR and CNR were generally lower in obese patients when the integrated body coil was used compared to the normal weight group with ideal body coils e.g.: For cerebral imaging T2W TSE (<5% for white matter, ca. 30% for grey matter) and T1W SE (ca. 15% for white matter, <5% for grey matter), for spinal imaging T2W TSE (ca. 35% for disc and vertebral body) and T1W SE (about 2% for disc, ca. 10% for vertebral body). Relevant new diagnoses impacting patient's therapy were identified in 30% (8/26), the particular medical question of the referring physician could be ruled out as possible reason for the medical condition in 53% (14/26).Conclusion: In excessively obese patients where CT, standard MR or ultrasound examination is not possible or not conclusive open MRI system have great potential in diagnostic evaluation, offering lower but sufficient image quality to impact therapy. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the feasibility of MR-guided discography using an open 1 Tesla MRI system.Methods: 48 disc segments of 41 patients scheduled for intradiscal thermal treatment, total disc replacement or spondylodesis were examined. A 1.0-T open MRI was used for instrument guidance and imaging. After primary disc puncture under guidance of interactive PDw TSE imaging, 1-2 ml of gadolinium contrast saline mixture was injected into the disc. The occurrence of memory pain during injection was recorded. Axial and sagittal T1w TSE images with and without fat saturation were obtained. All MRI discograms were analysed by two readers, who were blinded to the clinical findings.Results: Overall, the placement of the puncture needle in the targeted disc was accurate under real-time MR guidance. Injections were technically successful in all cases. No major complications occurred. The mean procedure time was 17 min (range 13-34 min). Image quality of contrast-enhanced MR discograms was excellent when using an optimized gadolinium contrast saline mixture of 1:600. Memory pain was detected in 16 out of 48 affected segments.Conclusion: MR-guided discography is accurate and safe. Multiplanar dynamic imaging facilitates the puncture of discs and provides high-quality MR discograms. [ABSTRACT FROM AUTHOR]

Background: preoperative assessment of pancreatic masses is still challenging as regards the characterization and assessment of irresectability. The opportunities of modern multidetector computed tomography (MDCT) with image postprocessing can be expected to enhance the diagnostic performance if accurate criteria are elaborated. Purpose: to estimate the accuracy of MDCT and multiplanar image reconstructions with the use of standardized imaging criteria for preoperative evaluation of pancreatic masses with respect to irresectability. Material and Methods: a total of 105 consecutive patients who underwent exploratory laparoscopy or pancreatic resection and had preoperative 3-phase MDCT (4-64 rows) were enrolled retrospectively. First, transverse sections and secondly additional 3Ds were reviewed by two independent blinded observers (O1/O2). Preoperative imaging findings were correlated with intraoperative and histopathologic results. Results: among all 105 patients, 70 malignant pancreatic tumors and 35 benign pancreatic diseases were found (accuracy of 93% for O1 and 91% for O2). For arterial tumor invasion, receiver operator characteristic (ROC) analysis (values averaged from the results of O1 and O2) revealed an area under the curve (AUC) of 0.931 for transverse sections and 0.986 for 3Ds. Regarding irresectability, positive predictive values were 97% (with 3Ds, 97%) for O1/O2; negative predictive values were 84% (with 3Ds, 89%) for O1 and 86% (with 3Ds, 91%) for O2. Conclusion: MDCT with 3Ds was highly accurate for evaluation and assessment of irresectability criteria in patients with pancreatic masses. However, due to the limited specificity regarding arterial tumor infiltration, the indication for surgical exploration should be made generously in case of inconclusive findings. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the feasibility and safety of a novel LITT applicator for thermal ablation of liver malignancies in 1.0-T high-field open MRI.Methods: A miniaturised 6-F double-tubed protective catheter with a closed cooling circuit was used with a flexible laser fibre, connected to a 1,064-nm Nd:YAG laser and evaluated in non-perfused porcine livers (18-30 W for 10-20 min, 2-W and 2-min increments; n = 210/applicator) in reference to an established 9-F system. As a proof of concept, MR-guided LITT was performed in two healthy domestic pigs in high-field open MRI.Results: Ex-vivo, the coagulation volumes induced by the 6-F system with maximum applicable power of 24 W for 20 min (33.0 ± 4.4 cm(3)) did not differ significantly from those set with the 9-F system at 30 W for 20 min (35.8 ± 4.9 cm(3)) (p = 0.73). A flow-rate of 15 ml/min of the cooling saline solution was sufficient. MR navigation and thermometry were feasible.Conclusion: The miniaturised 6-F applicator can create comparable coagulation sizes to those of the 9-F system. Applicator guidance and online-thermometry in high-field open MRI are feasible. [ABSTRACT FROM AUTHOR]

Background: The goal of this study was to evaluate high-field open magnetic resonance imaging (MRI) for intraoperative real-time imaging during hand-assisted laparoscopic liver resection. MR guidance has several advantages compared to ultrasound and may represent a future technique for abdominal surgery. Various MRI-safe and -compatible instruments were developed, tested, and applied to realize minimally invasive liver surgery under MR guidance. As proof of the concept, liver resection was performed in a porcine model. Methods: All procedures were conducted in a 1.0-T open MRI unit. Imaging quality and surgical results were documented during three cadaveric and two live animal procedures. A nonferromagnetic hand port was used for manual access and the liver tissue was dissected using a Nd:YAG laser. Results: The intervention time ranged from 126 to 145 min, with a dissection time from 11 to 15 min. Both live animals survived the intervention with a blood loss of 250 and 170 ml and a specimen weight of 138 and 177 g. A dynamic T2W fast spin-echo sequence allowed real-time imaging (1.5 s/image) with good delineation of major and small hepatic vessels. The newly developed MR-compatible instruments and camera system caused only minor interferences and artifacts of the MR image. Conclusion: MR-guided liver resection is feasible and provides additional image information to the surgeon. We conclude that MR-guided laparoscopic liver resection improves the anatomical orientation and may increase the safety of future minimally invasive liver surgery. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate different methods of magnetic resonance thermometry (MRTh) for the monitoring of intradiscal laser ablation therapy in an open 1.0 Tesla magnetic resonance (MR) scanner. Material and methods: MRTh methods based on the two endogenous MR temperature indicators of spin-lattice relaxation time T1 and water proton resonance frequency (PRF) shift were optimised and compared in vitro. For the latter, we measured the effective spin-spin relaxation times T2* in intervertebral discs of volunteers. Then we compared four gradient echo-based imaging techniques to monitor laser ablations in human disc specimens. Criteria of assessment were outline of anatomic detail, immunity against needle artefacts, signal-to-noise ratio (SNR) and accuracy of the calculated temperature. Results: T2* decreased in an inverse and almost linear manner with the patients’ age ( r = 0.9) from 70 to 30 ms (mean of 49 ms). The optimum image quality (anatomic details, needle artefacts, SNR) and temperature accuracy (±1.09°C for T1-based and ±1.11°C for PRF-based MRTh) was achieved with a non-spoiled gradient-echo sequence with an echo time of TE = 10 ms. Conclusion: Combination of anatomic and thermometric non-invasive monitoring of laser ablations in the lumbar spine is feasible. The temperature accuracy of the investigated T1- and PRF-based MRTh methods in vitro is high enough and promises to be reliable in vivo as well. [ABSTRACT FROM AUTHOR]