Search

Background Limited knowledge of stem cell therapies` mechanisms of action hampers their sustainable implementation into the clinic. Specifically, the interactions of transplanted stem cells with the host vasculature and its implications for their therapeutic efficacy are not elucidated. We tested whether adhesion receptors and chemokine receptors on stem cells can be functionally modulated, and consequently if such modulation may substantially affect therapeutically relevant stem cell interactions with the host endothelium. Methods We investigated the effects of cationic molecule polyethylenimine (PEI) treatment with or without nanoparticles on the functions of adhesion receptors and chemokine receptors of human bone marrow-derived Mesenchymal Stem Cells (MSC). Analyses included MSC functions in vitro, as well as homing and therapeutic efficacy in rodent models of central nervous system´s pathologies in vivo. Findings PEI treatment did not affect viability, immunomodulation or differentiation potential of MSC, but increased the CCR4 expression and functionally blocked their adhesion receptors, thus decreasing their adhesion capacity in vitro. Intravenously applied in a rat model of brain injury, the homing rate of PEI-MSC in the brain was highly increased with decreased numbers of adherent PEI-MSC in the lung vasculature. Moreover, in comparison to untreated MSC, PEI-MSC featured increased tumour directed migration in a mouse glioblastoma model, and superior therapeutic efficacy in a murine model of stroke. Interpretation Balanced stem cell adhesion and migration in different parts of the vasculature and tissues together with the local microenvironment impacts their therapeutic efficacy. Funding Robert Bosch Stiftung, IZEPHA grant, EU grant 7 FP Health

The aim of the study was to evaluate the diagnostic accuracy of carotid ultrasound (CU) to predict coronary atherosclerosis in asymptomatic male marathon runners. A total of 49 male marathon runners older than 45 years (mean age 53.3 ± 7.2 years, range 45-74 years) received CU and cardiac CT angiography (CTA) including calcium scoring (CS). Results of CU and CTA were classified binary: 1. Absence of atherosclerosis and 2. Presence of atherosclerosis. The extent of atherosclerosis was not primary end point of the study. Mean PROCAM score was 2.3% (SD 2.2, range 0.44%-12.34%). One person had to be excluded from analysis (one missing CT-scan). From the remaining 48 marathon runners, 17 (35.4%) had carotid atherosclerosis and 22 (45.8%) coronary atherosclerosis. Atherosclerosis in either exam was diagnosed in 27/48 (56.3%) marathon runners. Diagnostic accuracy of CU to predict coronary atherosclerosis was: sensitivity 54.55% (95% CI 32.2-75.6), specificity 80.8% (CI 60.6-93.4), positive predictive value 70.6 (CI 44.1-89.9), negative predictive value 67.7 (CI 48.6-83.3) with a positive likelihood ratio of 2.84 (CI 1.18-6.82) and a negative likelihood ratio of 0.56 (CI 0.34-0.92). Coronary and/or carotid atherosclerosis can be detected in more than 50% of male marathon runners aged older than 45 years. The diagnostic value of carotid ultrasound to predict coronary atherosclerosis is low but higher than the accuracy of rest- or stress-ECG. As outcome studies in sportsmen are still missing, the routine evaluation of the carotid arteries by ultrasound or even cardiac CT cannot be recommended at present. Furthermore, the incidence of atherosclerosis by our method in normal population is not known.

Objective: The aim of this pilot study was to test and demonstrate the feasibility of simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) of the head and upper neck area using a new hybrid PET/MRI system. Methods: Eight patients with malignant head and neck tumours were included in the pilot study. Directly after routine PET/CT imaging with a whole-body system using the glucose derivative 2-[18F]fluoro-2deoxy-D-glucose (FDG) as a radiotracer additional measurements were performed with a prototype PET/MRI system for simultaneous PET and MR imaging. Physiological radiotracer uptake within regular anatomical structures as well as tumour uptake were evaluated visually and semiquantitatively (metabolic ratios) in relation to cerebellar uptake on the PET/MRI and PET/CT systems. Results: The MR datasets showed excellent image quality without any recognisable artefacts caused by the inserted PET system. PET images obtained with the PET/MRI system exhibited better detailed resolution and greater image contrast in comparison to those from the PET/CT system. An excellent agreement between metabolic ratios obtained with both PET systems was found: R = 0.99 for structures with physiological tracer uptake, R = 0.96 for tumours. Conclusion: Simultaneous PET/MRI of the head and upper neck area is feasible with the new hybrid PET/MRI prototype

Die MR/PET ermoglicht als Hybridverfahren die Akquisition einer Vielzahl von Parametern wahrend einer einzelnen Untersuchung. Dazu gehoren die Darstellung der Anatomie, aber auch funktioneller und metabolischer Informationen, etwa zu Perfusion, Diffusion und Stoffwechsel. Die vorliegende Arbeit gibt einen Uberblick uber die verschiedenen Methoden und deren Anwendungsmoglichkeiten in multiparametrischer Bildgebung mittels MR/PET. Es konnte gezeigt werden, dass die Zusammenfuhrung der Informationen, die bei den Hybridverfahren gewonnen werden, bei onkologischen, neurologischen und inflammatorischen Erkrankungen zu einer Verbesserung der diagnostischen Genauigkeit fuhren kann. Aufgrund der Fulle und Komplexitat der hierbei anfallenden Daten ist die Anwendung von Klassifikationsverfahren und Methoden der Parameterselektion sinnvoll. Derzeit sind der klinischen Anwendung der dargestellten Verfahren noch Grenzen gesetzt, da einerseits eine Software fur eine schnelle und standardisierte Auswertung der gewonnenen Bilddaten noch fehlt. Andererseits gibt es Mangel bei der Vergleichbarkeit der Ergebnisse aufgrund von fehlenden Standardisierungen des Untersuchungs- und Befundungsablaufs.

Background Published national and international guidelines and consensus meetings on the use of vacuum-assisted biopsy (VAB) give different recommendations regarding the required numbers of tissue specimens depending on needle size and imaging method. Purpose To evaluate the weights of specimens obtained with different VAB needles to facilitate the translation of the required number of specimens between different breast biopsy systems and needle sizes, respectively. Material and Methods Five different VAB systems and seven different needle sizes were used: Mammotome® (11-gauge (G), 8-G), Vacora® (10-G), ATEC Sapphire™ (9-G), 8-G Mammotome® Revolve™, and EnCor Enspire® (10-G, 7-G). We took 24 (11-G) or 20 (7–10-G) tissue cores from a turkey breast phantom. The mean weight of a single tissue core was calculated for each needle size. A matrix, which allows the translation of the required number of tissue cores for different needle sizes, was generated. Results were compared to the true cumulative tissue weights of consecutively harvested tissue cores. Results The mean tissue weights obtained with the 11-G / 10-G Vacora® / 10-G Enspire® / 9-G / 8-G Original / 8-G Revolve™ / 7-G needles were 0.084 g / 0.142 g / 0.221 g / 0.121 g / 0.192 g / 0.334 g / 0.363 g, respectively. The calculated required numbers of VAB tissue cores for each needle size build the matrix. For example, the minimum calculated number of required cores according to the current German S3 guideline is 20 / 12 / 8 / 14 / 9 / 5 / 5 for needles of 11-G / 10-G Vacora® / 10-G Enspire® / 9-G / 8-G Original / 8-G Revolve™ / 7-G size. These numbers agree with the true cumulative tissue weights. Conclusion The presented matrix facilitates the translation of the required number of VAB specimens between different needle sizes and thereby eases the implementation of current guidelines and consensus recommendations into clinical practice.

Direct stem cell therapies for functionally impaired tissue require a sufficient number of cells in the target region and a method for verifying the fate of the cells in the subsequent time course. In vivo MRI of iron labeled mesenchymal stem cells has been suggested to comply with these requirements. The study was conducted to evaluate proliferation, migration, differentiation and adhesion effects as well as the obtained iron load of an iron labeling strategy for mesenchymal stem cells. After injection into the porcine urethral sphincter, the labeled cells were monitored for up to six months using MRI. Mesenchymal stem cells were labeled with ferucarbotran (60/100/200 µg/mL) and ferumoxide (200 µg/mL) for the analysis of migration and viability. Phantom MR measurements were made to evaluate effects of iron labeling. For short and long term studies, the iron labeled cells were injected into the porcine urethral sphincter and monitored by MRI. High resolution anatomical images of the porcine urethral sphincter were applied for detection of the iron particles with a turbo-spin-echo sequence and a gradient-echo sequence with multiple TE values. The MR images were then compared with histological staining. The analysis of cell function after iron labeling showed no effects on proliferation or differentiation of the cells. Although the adherence increases with higher iron dose, the ability to migrate decreases as a presumed effect of iron labeling. The iron labeled mesenchymal stem cells were detectable in vivo in MRI and histological staining even six months after injection. Labeling with iron particles and subsequent evaluation with highly resolved three dimensional data acquisition allows sensitive tracking of cells injected into the porcine urethral sphincter for several months without substantial biological effects on mesenchymal stem cells.

Rationale and Objectives Automatic bone and plaque subtraction (BPS) in computed tomographic angiographic (CTA) examinations using dual-energy CT (DECT) remains challenging because of beam-hardening artifacts in the shoulder region and close proximity of the internal carotid artery to the base of the skull. The selection of the tube voltage combination in dual-source CT influences the spectral separation and the susceptibility for artifacts. The purpose of this study was to assess which tube voltage combination leads to an optimal image quality of head and neck DECT angiograms after bone subtraction. Materials and Methods Fifty-one patients received tin-filter–enhanced DECT angiograms of the supra-aortic arteries using two voltage protocols: 24 patients were studied using 80/Sn140 kV and 27 using a 100/Sn140 kV protocol, both protocols with an additional tin filter. A commercially available DE-CTA BPS algorithm was used. Artificial vessel erosions in BPS maximum intensity projections (four-level Likert scale with CTA source data as reference) and vessel signal-to-noise ratio (SNR) were assessed in the level of the shoulders and the base of the skull in each patient and compared. Results At the level of the shoulder, 100/Sn140 kV achieved higher SNR (23.4 ± 6.4 at 80/Sn140 kV vs. 35.1 ± 11.8 at 100/Sn140 kV; P

Purpose To survey integrative teaching in radiology at German universities. Materials and methods A questionnaire about radiological education was sent electronically to all 37 chairpersons of university radiology departments in Germany. The questions included the course type, teaching methods, concept, perception, and advantages and disadvantages of integrative teaching. Statistical analysis was performed with nonparametric statistics and chi-square test. Results The survey was considered representative with a return rate of 68 %. Integrative teaching is established at 4/5 of all departments. Integrative teaching is well accepted with an acceptance rate that is significantly higher in so-called "Modellstudiengangen" [model courses of study] (100 %) compared to conventional courses of study (72 %). The advantages of integrative teaching include linking of content (92 %) and preparation for interdisciplinary work (76 %). The disadvantages include high effort (75 %) and time (67 %) for organization. Furthermore, there is a risk that basic radiological facts and knowledge cannot be conveyed and that the visibility of radiology as an independent discipline is lost. Conventional radiological teaching has a similarly high acceptance (84 %) compared to integrative courses (76 %). Conclusion Integrative teaching has a high acceptance among chairpersons in radiology in Germany despite the greater effort. A good interdisciplinary collaboration is essential for integrative teaching and at the same time this can be conveyed to the students. However, the visibility of radiology as a discipline and the possibility to cover basic radiological content must be ensured. Therefore, both conventional courses and integrative teaching seems reasonable, especially in cross-disciplinary subjects such as radiology. Key points Both integrative teaching and conventional radiological teaching are highly accepted. The advantages include the linking of multidisciplinary content and the preparation for interdisciplinary cooperation. The disadvantages include more time and effort for organization and reduced visibility of cross-disciplinary subjects.

OBJECTIVE. Dual-energy CT (DECT) enables subtraction of calcium, facilitating the visualization of bone marrow (BM) in the axial skeleton. The purpose of this study was to assess whether DECT BM images have the potential to improve the detection of multifocal and diffuse BM infiltration in multiple myeloma (MM) in comparison with regular CT with MRI as the reference standard. SUBJECTS AND METHODS. This study included 32 consecutive patients who had known MM or presented with monoclonal gammopathy of unknown significance and underwent DECT and MRI of the axial skeleton. The degrees (none, n = 14; moderate, n = 10; and high, n = 8) and patterns (diffuse, n = 10 or multifocal, n = 8) of infiltration were assessed on MR images. Attenuation in BM and CT images in known uninvolved and involved areas was measured. Cutoff values of attenuation in BM images for infiltration in lytic and nonlytic lesions were established by ROC analysis. At least 120 days later, sensitivity and specificity for reading CT images alone and when using additional BM images were evaluated. RESULTS. ROC analysis revealed larger AUC in BM images than in CT images; cutoff values for marrow invasion in BM images were 4 and -3 HU in lytic and nonlytic lesions, respectively. In the blinded reading session, BM images improved the sensitivity for the detection of diffuse infiltration from 0 to as much as 75% for cases with high-grade infiltration. In multifocal patterns, BM images did not significantly change the detection rate. CONCLUSION. BM images have the potential to improve the sensitivity for detection of diffuse BM involvement in comparison with regular CT.

Background Three-vessel coronary artery disease (CAD) comes along with globally reduced myocardial perfusion potentially restricting the demarcation of regional hypoperfusion in stress perfusion cardiac magnetic resonance imaging (MRI). Purpose To evaluate whether stress perfusion cardiac MRI is capable of detecting myocardial hypoperfusion in patients with 3-vessel CAD reliably. Material and Methods Two hundred and five patients with symptoms of CAD were included. The examination protocol comprised imaging of myocardial perfusion at stress (0.14 mg/kg/min adenosine for 4 min) using a 2D saturation recovery gradient echo sequence after administration of gadobutrol (0.1 mmol/kg body weight). Perfusion sequences were assessed qualitatively by two experienced observers. Coronary angiography served as standard of reference. Results Sensitivity and specificity for hemodynamically relevant stenoses in patients with 0-, 1-, 2-, 3-vessel coronary artery disease were 100%/91%, 91%/73%, 90%/71%, 92%/64%; positive/negative predictive value, 67%/100%, 91%/73%, 83%/81%, 93%/58%; diagnostic accuracy, 93%/87%/83%/87%, respectively. The negative predictive value in patients with 3-vessel CAD was lower than in patients with 0- and 2-vessel CAD and the specificity lower than in patients with no CAD whereas the positive predictive value was higher than in patients with no CAD. The other proportions did not differ significantly between the groups. Conclusion The diagnostic value of stress perfusion cardiac MRI in patients with 3-vessel CAD is comparable to results in patients with 1- or 2-vessel CAD. In the rare event that stress perfusion images do not depict regional hypoperfusion in patients with severe 3-vessel CAD, myocardial ischemia could be identified by reduced semi-quantitative perfusion parameters.

Objectives The purpose of this study was to evaluate the 5-year follow-up (FU) data of the THUNDER (Local Taxan With Short Time Contact for Reduction of Restenosis in Distal Arteries). Background The THUNDER trial was the first study to investigate the treatment of femoropopliteal arteries with a paclitaxel-coated balloon (PCB). Methods In 154 patients, femoropopliteal arteries were treated with PCB, with angioplasty with paclitaxel in contrast medium, or no paclitaxel (control). The primary endpoint was 6-month late lumen loss (LLL). Secondary endpoints included freedom from target lesion revascularization (TLR), binary restenosis rate, and amputation. The 5-year FU compares outcomes in patients treated with PCB and control subjects. Additionally, LLL at 6 months and TLR up to 5-year FU were analyzed in terms of sex and lesion length. Results Over the 5-year period, the cumulative number of patients with TLR remained significantly lower in the PCB group (21%) than in the control group (56%, p = 0.0005). In the small group of patients with angiographic and duplex sonographic follow-up, PCB was associated with a lower rate of binary restenosis (17% vs. 54%; p = 0.04). No signs of aneurysm formation or constrictive fibrosis were detected. Whereas LLL at 6-month FU did not differ between men and women in the PCB group, the TLR rate was lower in men than in women at 5-year FU. A benefit of PCB treatment in terms of LLL and TLR was seen independent of lesion length. Conclusions The reduced TLR rate following PCB treatment was maintained over the 5-year FU period. No signs of drug-related local vessel abnormalities were detected. (Thunder Trial—Local Taxan With Short Time Contact for Reduction of Restenosis in Distal Arteries [THUNDER]; NCT00156624 )

Purpose The impact of preoperative MRI on re-excisions and mastectomy rate is discussed controversially in the literature. Aim of this study was to evaluate the effect of preoperative breast MRI on the surgical procedure and rate of repeated surgeries. Material and methods A total of 991 consecutive patients in the years 2009 and 2010 with 1036 primary breast cancers were retrospectively analyzed. Sixty percent (599 patients with 626 cancers) received preoperative breast MRI. Planned surgical procedures before and after MRI and numbers of repeated surgeries in patients with (MR+ ) and without preoperative MRI (MR−) were compared. Results The result of preoperative MRI changed the surgical procedure in 25% (157/626) of the cases. In 81% (127/157), MRI was beneficial for the patients, as otherwise occult carcinomas were removed (n = 122) or further biopsy could be prevented (n = 5). Mastectomy rates did not differ between MR+ and MR- group (39% vs. 39%). On multiple regression analysis, the MR+ group had a lower chance for repeated surgery (p Conclusion Preoperative MRI could lower the chance for repeated surgery in patients with primary breast cancer. The rate of mastectomy did not differ between patients undergoing preoperative MRI and those who did not.

Deep venous thrombosis (DVT) can be difficult to detect using CT due to poor and heterogeneous contrast. Dual-energy CT (DECT) allows iodine contrast optimization using noise-optimized monoenergetic extrapolations (MEIs) and iodine maps (IMs). Our aim was to assess whether MEI and IM could improve the delineation of thrombotic material within iodine-enhanced blood compared to single-energy CT (SECT). Six vessel phantoms, including human thrombus and contrast media-enhanced blood and one phantom without contrast, were placed in an attenuation phantom and scanned with DECT 100/140 kV and SECT 120 kV. IM, virtual non-contrast images (VNC), mixed images, and MEI were calculated. Attenuation of thrombi and blood were measured. Contrast and contrast-to-noise-ratios (CNRs) were calculated and compared among IM, VNC, mixed images, MEI, and SECT using paired t tests. MEI40keV and IM showed significantly higher contrast and CNR than SE120kV from high to intermediate iodine concentrations (contrast:pMEI40keV

Rationale and Objectives A new computed tomography (CT) detector with integrated electric components and shorter conducting pathways has recently been introduced to decrease system inherent electronic noise. The purpose of this study was to assess the potential benefit of such integrated circuit detector (ICD) in head CT by comparing objective and subjective image quality in low-dose examinations with a conventional detector design. Materials and Methods Using a conventional detector, reduced-dose noncontrast head CT (255 mAs; effective dose, 1.7 mSv) was performed in 25 consecutive patients. Following transition to ICD, 25 consecutive patients were scanned using identical imaging parameters. Images in both groups were reconstructed with iterative reconstruction (IR) and filtered back projection (FBP) and assessed in terms of quantitative and qualitative image quality. Results Acquisition of head CT using ICD increased signal-to-noise ratio of gray and white matter by 14% (10.0 ± 1.6 vs. 11.4 ± 2.5; P = .02) and 17% (8.2 ± 0.8 vs. 9.6 ± 1.5; P = .000). The associated improvement in contrast-to-noise ratio was 12% (2.0 ± 0.5 vs. 2.2 ± 0.6; P = .121). In addition, there was a 51% increase in objective image sharpness (582 ± 85 vs. 884.5 ± 191; change in HU/Pixel; P Conclusions At the same radiation level, acquisition of head CT with ICD achieves superior objective and subjective image quality and provides potential for significant dose reduction.

To compare positron emission tomography (PET)/magnetic resonance (MR) imaging and PET/computed tomography (CT) for lesion detection and interpretation, quantification of fluorine 18 ((18)F) fluorodeoxyglucose (FDG) uptake, and accuracy of MR-based PET attenuation correction in pediatric patients with solid tumors. Materials and Methods This prospective study had local ethics committee and German Federal Institute for Drugs and Medical Devices approval. Written informed consent was obtained from all patients and legal guardians. Twenty whole-body (18)F-FDG PET/CT and (18)F-FDG PET/MR examinations were performed in 18 pediatric patients (median age, 14 years; range, 11-17 years). (18)F-FDG PET/CT and (18)F-FDG PET/MR data were acquired sequentially on the same day for all patients. PET standardized uptake values (SUVs) were quantified with volume of interest measurements in lesions and healthy tissues. MR-based PET attenuation correction was compared with CT-derived attenuation maps (µ-maps). Lesion detection was assessed with separate reading of PET/CT and PET/MR data. Estimates of radiation dose were derived from the applied doses of (18)F-FDG and CT protocol parameters. Descriptive statistical analyses were performed to report correlation coefficients and relative deviations for comparison of SUVs, rates of lesion detection, and percentage reductions in radiation dose.PET SUVs showed strong correlations between PET of PET/CT (PETCT) and PET of PET/MR (PETMR) (r0.85 for most tissues). Apart from drawbacks of MR-based PET attenuation correction in osseous structures and lungs, similar SUVs were found on PET images corrected with CT-based µ-maps (13.1% deviation of SUVs for bone marrow and5% deviation for other tissues). Lesion detection rate with PET/MR imaging was equivalent to that with PET/CT (61 areas of focal uptake on PETMR images vs 62 areas on PETCT images). Advantages of PET/MR were observed especially in soft-tissue regions. Furthermore, PET/MR offered significant dose reduction (73%) compared with PET/CT.Pediatric oncologic PET/MR is technically feasible, showing satisfactory performance for PET quantification with SUVs similar to those of PET/CT. Compared with PET/CT, PET/MR demonstrates equivalent lesion detection rates while offering markedly reduced radiation exposure. Thus, PET/MR is a promising modality for the clinical work-up of pediatric malignancies. Online supplemental material is available for this article.

Die MRT stellt fur die meisten malignen Tumoren im Kindesalter die entscheidende Bildgebung fur das lokoregionare Staging dar. Die Erfassung der lokalen Tumorausbreitung sowie die Gewebecharakterisierung mussen umfassend erfolgen. Daher sind an die kindliche Anatomie adaptierte Untersuchungsprotokolle, die sich an Leitlinien der onkologischen Gesellschaften orientieren, essentiell. Da einige Tumorentitaten wie z. B. das Nephroblastom in bestimmten Altersgruppen initial ohne bioptische Sicherung mit Chemotherapie behandelt werden, sind die Kenntnisse der vielfaltigen Differenzialdiagnosen notwendig. Die hochaufgeloste GK-MRT erfasst in einer Untersuchung sowohl die lokale als auch die systemische Ausbreitung, sodass multiple Teilkorperuntersuchungen eingespart werden konnen. Die technischen Voraussetzungen, einige Untersuchungsstrategien sowie die klinische Bedeutung typischer Befunde der lokalen und der systemischen MRT-Bildgebung im Kontext zu nuklearmedizinischen Methoden werden in dieser Ubersicht besprochen.

Aim To evaluate whether another contrast-enhanced (CE) magnetic resonance imaging (MRI) examination 24–48 h after MRI-guided vacuum-assisted breast biopsy (MRI-VAB) can reduce the rate of false-negative cases. Materials and methods The study included 252 patients who underwent MRI-VAB for the clarification of 299 lesions. The success of MRI-VAB was assessed at interventional MRI and another CE MRI 24–48 h after the intervention. In cases of successful MRI-VAB (complete or partial lesion removal) and benign histological results, follow-up breast MRI was performed. In cases of unsuccessful biopsy (unchanged lesion), tissue sampling was repeated. False-negative cases were calculated to assess the diagnostic value of MRI follow-up within 2 days after intervention. Results Ninety-eight malignant (32.8%) and 201 (67.2%) benign lesions were diagnosed using MRI-VAB. At immediate unenhanced control MRI, all lesions were assessed as successfully biopsied. In 18 benign cases (6%), CE MRI after 24–48 h showed an unsuccessful intervention. Further tissue sampling revealed another 13 cancers in these patients. This results in a false-negative rate of 11.7%. Follow-up MRI of the benign lesions presented no further malignancy. Conclusions MRI-VAB with immediate unenhanced control offers a success rate of 94%. The rate of false-negative biopsies (11.7%) could be reduced to zero by using short-term follow-up MRI. Therefore, a further CE breast MRI 24–48 h after benign MRI-VAB to eliminate missed cancers is recommended.

The aim of this study was to investigate frequencies of typical artifacts in low-dose pediatric lung examinations using high-pitch computed tomography (HPCT) compared to MDCT, and to estimate the effective radiation dose (Eeff).Institutional review board approval for this retrospective study was obtained. 35 patients (17 boys, 18 girls; mean age 112 ± 69 months) were included and underwent MDCT and follow-up scan by HPCT or vice versa (mean follow-up time 87 days), using the same tube voltage and current. The total artifact score (0 - 8) was defined as the sum of artifacts arising from movement, breathing or pulsation of the heart or pulmonary vessels (0 - no; 1 - moderate; 2 - severe artifacts). Eeff was estimated according to the European Guidelines on Quality Criteria for Multislice Computed Tomography. The Mann-Whitney U test was used to analyze differences between the patient groups. The Spearman's rank correlation coefficient was used for correlation of ordinal variables.The scan time was significantly lower for HPCT compared to MDCT (0.72 ± 0.13 s vs. 3.65 ± 0.81s; p 0.0001). In 28 of 35 (80 %) HPCT examinations no artifacts were visible, whereas in MDCT artifacts occurred in all examinations. The frequency of pulsation artifacts and breathing artifacts was higher in MDCT compared to HPCT (100 % vs. 17 % and 31 % vs. 6 %). The total artifact score significantly correlated with the patient's age in MDCT (r = - 0.42; p = 0.01), but not in HPCT (r = - 0.32; p = 0.07). The estimated Eeff was significantly lower in HPCT than in MDCT (1.29 ± 0.31 vs. 1.47 ± 0.37 mSv; p 0.0001).Our study indicates that the use of HPCT has advantages for pediatric lung imaging with a reduction of breathing and pulsation artifacts. Moreover, the estimated Eeff was lower. In addition, examinations can be performed without sedation or breath-hold without losing image quality.• Fewer artifacts in pediatric lung imaging with HPCT• Reduced Eeff in HPCT• HPCT without sedation or breath-hold without loss of image quality.

Purpose: Energy transfer from radiofrequency (RF) applicator to tissue is both precondition and limiting factor. The purpose of this ex vivo study was to examine the influence of form of energy delivery on ablation result during RF ablation with cryo-cooled applicators. Materials and Methods: One hundred eight ablations were performed in ex vivo bovine liver under continuous energy delivery (A), pulsed energy delivery with reduced current during ablation pause (B) and impedance-dependent energy delivery. Maximum ablation time was 20 min. Early termination of ablation in case of loss of conductivity. Optimal ablation parameters were assessed. Short axis diameter of the ablation zone and ablation duration were determined. Ablation results under mode A, B and C were compared with analysis of variance and Tukey-Kramer HSD test. Influence of ablation duration on short axis diameter was evaluated with regression analysis. Results: Significantly largest short axis diameter (51.1 mm ± SD 2.3; p = 0.01) was reached with impedance-dependent energy delivery (pulsed: 46.1 mm ± SD 5.6; continuous: 44.4 mm ± SD 4.1). Significantly longest ablation duration (1061.6 s ± SD 42.4; p = 0.01) was reached with impedance-dependent energy delivery (pulsed: 815.7 s ± 41.3; continuous: 715.3 s ± SD 82.2). Linear correlation between ablation duration and short axis diameter was calculated (R = 0.7). Conclusion: Modification of energy delivery during RF ablation with cryo-cooled applicators improves energy transfer to tissue and enables larger ablation zones. Key Points: • Impedance-dependent energy delivery prevents early termination in kryo-based RF-ablation, • Impedance-dependent energy delivery enables larger ablation zones than continuous energy delivery, • Reduced current during ablation pause does not improve ablation results. Citation Format: • Hoffmann R, Bustamante J, Pitsaer C et al. Forms of Energy Delivery during Cryo-cooled Radiofrequency Ablation for Optimization of the Ablation Result. Fortschr Rontgenstr 2014; 186: 945 – 950

Background Magnetic resonance imaging (MRI) BI-RADS® 3 lesions should have a very high probability of being benign. To prove benignity most institutions do follow-up MRI. Purpose To evaluate the necessity of initial short-interval follow-up after 6 months as it is suggested for mammographic BI-RADS®3 lesions. Material and Methods We analyzed 163 consecutive MRI-BI-RADS® 3 lesions on follow-up MRI: 75 masses (46%), 67 foci (41.1%), and 21 (12.9%) non-mass-like enhancing lesions (NMLE). Results During MRI follow-up (mean time, 563 days) 20% of the lesions disappeared, 23% decreased, 52% did not change, and 4.9% showed increase. All increasing lesions were biopsied (5 benign, 2 ductal carcinoma in situ, 1 invasive carcinoma). The rate of malignancy was 1.8%. All malignant lesions (1 mass, 1 focus, 1 NMLE) showed increase at initial follow-up after a mean interval of 190 days. Conclusion In this study the malignancy rate of MRI-BI-RADS® 3 lesions corresponded to mammographic BI-RADS® 3 lesions. Initial short-interval MRI should be suggested to identify malignant MRI-BI-RADS® 3 lesions.

OBJECTIVE The aim of this study was to search for chemotherapy-induced perfusion changes of diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma at midtreatment versus baseline volume perfusion computed tomography (VPCT). METHODS Forty-five consecutive patients with untreated diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma received VPCT examinations of the tumor bulk at baseline and during chemotherapy (midtreatment). Blood flow (BF), blood volume (BV), and transit constant (K-trans) were determined. Treatment response was categorized according to the Cheson criteria into complete or partial remission and stable or relapsed/progressive disease. RESULTS Midtreatment follow-up showed a reduction in BF, BV, and K-trans in all lymphoma subtypes compared with baseline. The reduction in BV was less pronounced in larger tumors. Notably, BF, BV, and K-trans decreased in the responders (complete remission/partial remission) when compared with the nonresponders (stable or relapsed/progressive disease). Less than 10% reduction in BF was shown to be the best VPCT criterion for the identification of nonresponse. CONCLUSIONS Chemotherapy-induced perfusion changes in responders are recognizable at midtreatment VPCT.

Das Lungenkarzinom stellt weiterhin eine der haufigsten krebsbedingten Todesursachen in Westeuropa dar. Prognose und Therapieansatz werden wesentlich bestimmt durch die initiale Ausbreitungsdiagnostik. Die Computertomografie wird hierbei oft als Standardmodalitat genutzt, ist allerdings hinsichtlich ihrer Sensitivitat und Spezifitat insbesondere beim N- und M-Staging limitiert, weshalb die S3-Leitlinie die kombinierte PET/CT zum Staging empfiehlt. Aufgrund der deutlichen Stadienabhangigkeit der Prognose des Lungenkarzinoms ist die moglichst fruhe Diagnose der Erkrankung von groser Bedeutung. Allerdings ist die Beurteilung der ­Dignitat zufallig diagnostizierter pulmonaler Rund­herde, die mit steigenden CT-Untersuchungszahlen immer haufiger vorkommen, schwierig, auserdem ist das Karzinomrisiko zufallig entdeckter solider pulmonaler Rundherde oft gering. Ein Algorithmus der Fleischner-Society gibt Empfehlungen zur Beurteilung und Kon­trolle derartiger Befunde. Fur die Zukunft ist mit einem verstarkten Einsatz von funktionellen Verfahren wie der PET/CT und der CT-Perfusion zur Prognoseabschatzung und zum Therapiemonitoring beim Lungenkarzinom zu rechnen.

To determine the diagnostic benefit of volume perfusion computed tomography (VPCT) at end of treatment for response assessment in lymphoma patients.Seventy-five patients with different lymphoma subtypes were included: 50/75 patients had residual masses at end of treatment, 26/50 patients underwent VPCT at baseline and at end of treatment, and 24/50 patients only had end-of-treatment VPCTs. We evaluated the size of the main lymphoma mass, its blood flow (BF), blood volume (BV) and k-trans, calculated ratios (baseline and end of treatment) as well as sensitivity/specificity/negative (NPV)/positive predictive values (PPV). For VPCT at end of treatment, a cutoff threshold between responders and non-responders was calculated.For patients undergoing VPCT at baseline and end of treatment, reduction in size, BF, BV and k-trans was significant (P 0.001). Identification of non-response was reached at:53% reduction in size (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/62.5%/80.77%/84.21%/71.43%),15% reduction of BF (sensitivity/specificity/accuracy/PPV/NPV of 100%/37.5%/80.77%/0.26%/100%), or45% reduction of k-trans (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/75%/84.62%/88.89%/75%). In the subgroup undergoing VPCT at end of treatment, BF18.51 ml/100 ml indicated non-responsiveness (sensitivity 92.86%, specificity 72.73%, accuracy 84%, PPV 81.25%, NPV 88.89%).VPCT seems adequate for assessment of lymphoma response at end of treatment. The degree of residual lymphoma perfusion at end of treatment helps to identify patients likely to remain in remission 1 year after completion of therapy.• Volume perfusion computed tomography (VPCT) offers measurements for assessing tumour response. • Perfusion parameter changes measured by VPCT correlate with antitumour therapy response. • In lymphoma, baseline and end-of-treatment perfusion parameter ratios can predict response. • Perfusion measurements after treatment identify patients likely to remain in remission.

To investigate the impact of using paclitaxel-coated balloons (PCB) on outcome after post-angioplasty dissection in femoropopliteal arteries.The angiograms obtained in the THUNDER study (ClinicalTrials.gov identifier NCT00156624) were analyzed to compare degrees of dissection and angiographic parameters between the control (uncoated balloons, n=43) and treatment (PCBs, n=43) groups before and after the intervention and at 6-month follow-up. Furthermore, target lesion revascularizations (TLR) were documented up to 2 years.In each group, 24 (56%) patients had a dissection after the intervention. At the 6-month follow-up, patients with dissection of any grade after treatment with PCBs had significantly less late lumen loss (0.4 mm) than patients with dissection after treatment with uncoated balloons (1.9 mm, p=0.001) and a lower degree of stenosis (20% vs. 51%, respectively; p=0.003). Patients with severe dissection (grades C, D, or E) especially seemed to benefit from the PCBs, with late lumen loss of 0.4 mm vs. 2.4 mm for controls (p=0.05). The binary restenosis rate was also markedly lower in the PCB group (20%) than in the uncoated group (55%, p=0.02). In the 2-year follow-up, TLR was performed in 56% of patients in the control group compared to 10% of patients in the PCB group (p=0.002).The results of this subgroup analysis suggest that patients with dissection following treatment with a paclitaxel-coated balloon have a very acceptable outcome and stent implantation is not necessary as long as the dissection does not result in acute flow limitation.

Objective: To evaluate the accuracy of high-spatial resolution T2-weighted endorectal magnetic resonance imaging (eMRI) for detection and pattern depiction of seminal vesicle invasion (SVI) in patients with prostate cancer (PCa). Methods: 376 patients were included who underwent eMRI for staging before radical open prostatectomy at 1.5 T with an endorectal coil. Statistical accuracy for detection of SVI was calculated. MR images of patients with SVI were further evaluated by two radiologists according to the classification by Wheeler and Ohori. Results: In the cohort, 35 patients had SVI after histopathological evaluation of the prostatectomy specimen (stage pT3b). Sensitivity and specificity for detection of SVI were 48.6 and 97.7%, respectively. Negative and positive predictive values and overall accuracy were 94.9, 68.0, and 93.1%, respectively. Infiltration pattern analysis showed that type I invasion was most common with 48.6 followed by type IIa (31.4%) and IIb (20%). Type III was not present. There was no statistical significant difference between the three groups regarding Gleason score, age, and prostate-specific antigen level. Conclusions: eMRI with high-spatial resolution T2-weighted imaging is accurate for assessment of SVI. Depiction of different infiltration types of SVI is feasible. By adding information about the extent of SVI, diagnostic reporting and risk stratification could be improved.

Purpose Off-resonant RF saturation influences signal intensity dependent on free and bound water fractions as well as the macromolecular content. The extent of interaction between these compartments can be evaluated by using the off-resonance saturation ratio (OSR). Combined with UTE sequences quantification of OSR even in tendinous tissues with extremely fast signal decay is possible. The aim of this prospective study was to investigate short-term exercise-induced effects of hydration state of the Achilles tendon by means of OSR and tendon volume. Materials and Methods Measurements of OSR and tendon volume before and after ankle-straining activity were performed in seven healthy male volunteers (median age 29 years) using a 3D UTE sequence with implemented off-resonance saturation pulse at 3T (off-resonance frequency 2/3 kHz) and by an automated contour detection in isotropic T2-weighted MR images with sub-millimeter resolution, respectively. Different tendon regions were evaluated. Reproducibility of OSR was measured in subsequent imaging sets. Root-mean-square-deviation (RMSD) and coefficient of variations (CV) were determined. Results RMSD of OSR in resting position were between 0.006 and 0.01 for different tendon regions and off-resonance frequencies (CV 2 to 3%). A significant increase (P < 0.05) of OSR after exercise was seen in all tendon regions except at the insertion (off-resonance frequency 3 kHz). Tendon volume was decreased significantly after ankle-straining activity (P = 0.003). Conclusion The observed decreased tendon volume and increased OSR directly after exercise indicates a short-term change in tendinous proton compartments, most likely a loss of free water molecules within the tendon.J. Magn. Reson. Imaging 2014;40:1400–1407. © 2013 Wiley Periodicals, Inc.

PURPOSE To characterize peritoneal carcinomatosis (PC) of different histologically proven primary tumors based on diffusion-weighted imaging (DWI) and (18) F-FDG positron emission tomography (PET). MATERIALS AND METHODS Forty-one patients underwent simultaneous MR/PET after clinically indicated (18) F-FDG-PET/CT. For all patients, histology of the primary tumor was obtained. MR protocol comprised anatomical imaging and axial DWI. Apparent diffusion coefficient (ADC) maps and FDG-PET were co-registered for evaluation of ADC and standard uptake value (SUV) of peritoneal lesions. Both lesion- and patient-based analysis was performed. Up to four peritoneal lesions were evaluated per patient. Mean and maximum standard uptake value (SUVmean , SUVmax ), mean and minimum ADC (ADCmean , ADCmin ) of each lesion were assessed. Spearman rank correlation (rs ) of ADC and SUV were calculated. SUV and ADC of ovarian and colorectal cancer lesions were compared using Wilcoxon test. RESULTS Measurable lesions (n = 52) were found in 20 of 41 PC patients. Moderate, but significant correlation existed between ADC and SUV in the lesion-based as well as the patient-based analysis (lesion-based: SUVmean versus ADCmean rs = -0.58; SUVmax versus ADCmin rs = -0.56, all P < 0.0001; patient-based: SUVmean versus ADCmean rs = -0.64, P = 0.002; SUVmax versus ADCmin rs = -0.60, P = 0.005). ADC and SUV differed significantly between ovarian and colorectal cancer lesions (ADCmin : P < 0.0001; ADCmean : P < 0.0001; SUVmax : P = 0.002; SUVmean : P = 0.005). Overall, mucinous tumor entities showed a tendency to higher ADC and lower SUV. CONCLUSION PC lesions showed significant differences in glucose uptake and diffusion characteristics depending on primary tumor histology. These differences should be considered when interpreting FDG-PET and DWI in PC patients.

Purpose To retrospectively evaluate the conspicuity of liver lesions in a fluoroscopic spoiled gradient echo (GRE) and a balanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) sequence. Materials and Methods In all, 103 patients with hepatocellular carcinomas (HCC) (41) or liver metastases (67) were treated using MR-guided radiofrequency ablation in a wide-bore 1.5 T scanner. A multislice real-time spoiled GRE sequence allowing for a T1 weighting (T1W) and a balanced SSFP sequence allowing for a T2/T1W contrast were used for MR guidance. The contrast-to-noise-ratio (CNR) of the lesions was calculated and lesion conspicuity was assessed retrospectively (easily detectable / difficult to detect / not detectable). Results HCC was easily detectable in 33/52% (GRE/SSFP), difficult to detect in 30/18%, and not detectable in 37/30% of the cases. Mean CNR varied widely (9.1 for GRE vs. 16.4 for SSFP). Liver metastases were easily detectable in 58/41% (GRE/SSFP), difficult to detect in 14/21%, and not detectable in 28/38% of the cases. Mean CNR for liver metastases was 11.5 (GRE) vs. 12.7 (SSFP). Twenty percent of all lesions could not be detected with either of the MR fluoroscopy sequences. Conclusion MR fluoroscopy using GRE and SSFP contrast enabled real-time detectability of 80% of the liver lesions. J. Magn. Reson. Imaging 2014;40:432–439. © 2013 Wiley Periodicals, Inc.

To measure blood perfusion in extramedullary myeloma by contrast-enhanced sonography, correlate it with specific hematologic parameters, and determine their utility for local and systemic response monitoring.Twenty-five consecutive patients (14 male and 11 female; median age, 68 years) with extramedullary myeloma were included. After intravenous administration of 2.4 mL of sulfur hexafluoride, extramedullary myeloma masses were examined for 60 seconds. All patients underwent contrast-enhanced sonography at baseline, and 15 were monitored additionally (3 weeks during therapy). Average peak perfusion, regional blood flow (RBF), and regional blood volume (RBV) were calculated. Baseline perfusion parameters were compared with short-term follow-up sonographic data and serologic biomarkers (M gradient). For validation of extramedullary myeloma and systemic myeloma, patients underwent midterm (3 months) imaging and serologic diagnosis.Patients with baseline β2-microglobulin (B2M) greater than 3.5 mg/L (n = 17) showed higher perfusion parameters compared with baseline B2M less than 3.5 mg/L (n = 8). At short-term follow-up, patients were classified by serologic criteria as responders (n = 9) and nonresponders (n = 6) and by sonographic criteria as responders (n = 10) and nonresponders (n = 5). In sonographic responders, mean peak, RBV, and RBF dropped from 59.13, 1446.09, and 71.52 (artificial units) at baseline to 29.30, 364.19, and 34.64 at follow-up (P.05), whereas in nonresponders, perfusion parameters increased from 33.18, 789.82, and 36.92 at baseline to 51.14, 1491.06, and 65.34 at follow-up (P.05). Prediction of a midterm course of systemic myeloma using serologic data yielded sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 0.66, 0.77, 0.66, and 0.77, whereas sonographic results (judged by RBV) yielded values of 0.66, 0.55, 0.5, and 0.71. Separate prediction of a local (extramedullary myeloma) response by sonography yielded sensitivity, specificity, PPV, and NPV of 0.8, 1.0, 1.0, and 0.71.Contrast-enhanced sonography is a valuable tool for short-term monitoring of the treatment response in extramedullary myeloma.

To present the 12-month results of a trial investigating the effects of dual antiplatelet therapy on target lesion revascularization (TLR) after balloon angioplasty ± stenting in the femoropopliteal segment.A prospective, randomized, single-center, double-blinded and placebo-controlled clinical trial randomly assigned 40 patients to receive pre- and postinterventional therapy with aspirin and clopidogrel. Another 40 patients received the same doses of aspirin and placebo instead of clopidogrel. Clopidogrel and placebo were stopped after 6 months, and patients remained on aspirin only. At 12 months after the intervention, 36 clopidogrel patients and 37 placebo patients were reevaluated.At 6 months, clopidogrel patients had significantly lower rates of TLR compared to placebo patients [2 (5%) vs. 8 (20%), p=0.04]. After stopping clopidogrel/placebo after 6 months, there was no significant difference in TLR at 12 months after treatment [9 (25%) clopidogrel vs. 12 (32.4%) placebo, p=0.35]. Mortality was 0 vs. 1 in the placebo group at 6 months (p=0.32) and 0 vs. 3 at 12 months (p=0.08).In contrast to the first report of a reduction in the TLR at 6 months, this advantage of dual antiplatelet therapy does not persist after stopping clopidogrel. Prolonged dual therapy (6 months) should be considered in patients who are at high risk for restenosis.

Solely size-based response criteria may be unreliable in patients with gastrointestinal stromal tumors (GIST) treated with tyrosine kinase inhibitors, because they typically underestimate responses to treatment. As GISTs are generally hypervascularized and novel targeted drugs knowingly affect angiogenic signaling pathways, perfusion measurements are expected to deliver important information about their efficacy. This pictorial essay illustrates the benefit of using complementary CT-perfusion-based measurements for more accurate evaluation of response to therapy in GIST.

Purpose: Sudden cardiac death [SCD] in competitive athletes is caused by a diverse set of cardiovascular diseases such as hypertrophic and dilated cardiomyopathy [HCM/DCM], myocarditis, coronary anomalies or even coronary artery disease. In order to identify potential risk factors responsible for SCD, elite athletes underwent cardiac magnetic resonance [CMR] imaging. Materials and Methods: 73 male [M] and 22 female [F] athletes (mean age 35.2 ± 11.4 years) underwent CMR imaging. ECG-gated breath-hold cine SSFP sequences were used for the evaluation of wall motion abnormalities and myocardial hypertrophy as well as for quantitative analysis (left and right ventricular [LV, RV] end-diastolic and end-systolic volume [EDV, ESV], stroke volume [SV], ejection fraction [EF] and myocardial mass [MM]). Furthermore, left and right atrial sizes were assessed by planimetry and delayed enhancement imaging was performed 10 minutes after the application of contrast agent. Coronary arteries were depicted using free-breathing Flash-3 D MR angiography. Results: The quantitative analyses showed eccentric hypertrophy of the left ventricle (remodeling index [MM/LV-EDV]: M 0.75, F 0.665), enlargement of the RV volumes (RV-EDV: M 122.6 ± 19.0 ml/m², F 99.9 ± 7.2 ml/m²) and an increased SV (LV-SV: M 64.7 ± 10.0 ml/m², F 56.5 ± 5.7 ml/m²; RV-SV; M 66.7 ± 10.4 ml/m², F 54.2 ± 7.1 ml/m²). Abnormal findings were detected in 6 athletes (6.3 %) including one benign variant of coronary anomaly and abnormal late gadolinium enhancement in 2 cases. None of the athletes showed wall motion abnormalities or signs of myocardial ischemia. Conclusion: CMR imaging of endurance athletes revealed abnormal findings in more than 5 % of the athletes. However, the prognostic significance remains unclear. Thus, cardiac MRI cannot be recommended as a routine examination in the care of athletes. Key points: Citation Format

To compare volume, sphericity, and short-axis diameter of the coagulation zone of four commercially available microwave ablation systems with three technical concepts in an ex vivo setting and to formulate mathematical models to predict these quantities.Two high-power systems (systems A and B), a system that enables simultaneous use of three antennas (system C), and a non-perfusion-cooled system that automatically adapts power and frequency (system D) were tested in ex vivo bovine livers (108 ablations). Coagulation volume, sphericity, and mean short-axis diameter were assessed, and mathematical functions were fitted for each system and assessed with the coefficient of determination (R(2)). Analysis of variance and Tukey post hoc tests were used for interdevice comparison after 5 and 10 minutes and after maximum recommended ablation time.Volume and short-axis diameter were determined by using a mathematical model for every system, with coefficients of determination of 0.75-0.98 and 0.70-0.97, respectively. Correlation for determination of sphericity was lower (R(2) = 0.01-0.68). Mean results with ablation performed according to manufacturer recommendations were as follows: Volume, sphericity, and short-axis diameter were 57.5 cm(3), 0.75, and 43.4 mm, respectively, for system A; 72.3 cm(3), 0.68, and 45.5 mm, respectively, for system B; 17.1 cm(3), 0.58, and 26.8 mm, respectively, for system C (one antenna); 76.5 cm(3), 0.89, and 50.6 mm, respectively, for system C (three antennas); and 56.0 cm(3), 0.64, and 40.9 mm, respectively, for system D. Systems A (mean volume, 52.4 cm(3) ± 4.5 [standard deviation]) and B (39.4 cm(3) ± 1.7) reach large ablation zones with 5-minute ablation.The largest ablation zone is obtained with systems B and C (three antennas) under maximum recommended ablation duration and with system A under short ablation time. The most spherical zone is obtained with system C (three antennas).

The aim of this study was to compare the size and shape of the indicated ablation zone using magnetic resonance (MR) imaging with different contrast weightings after MR-guided radiofrequency ablation (RFA) at 1.5 T.Magnetic resonance images of 50 patients treated for hepatic malignancies using MR-guided RFA were retrospectively evaluated. Areas indicating ablation zones in contrast-enhanced images were compared with nonenhanced T1- and T2-weighted images acquired after the intervention and 1 and 7 months after therapy. Corresponding slices were selected and registered to each other. Regions indicating ablation zones were segmented and compared. Areas in cm, positive predictive value, and sensitivity of native T1- and T2-weighted images were calculated with regard to their accordance with the contrast-enhanced images.Directly after the intervention, the ratios between the areas of the ablation zone in the contrast-enhanced and the tested sequences were 1.02 ± 0.12 in the T1-weighted images and 2.03 ± 0.78 in the T2-weighted images. Sensitivity (portion of the coagulation zone that was correctly detected based on the tested sequences) was 0.88 ± 0.08 using the T1-weighted and 0.54 ± 0.20 using the T2-weighted images. The positive predictive values were 0.89 ± 0.06 (T1 weighted) and 0.93 ± 0.06 (T2 weighted). One month after therapy, the ratios between the areas in the contrast-enhanced and the tested sequences were 1.02 ± 0.12 in the T1-weighted images and 1.04 ± 0.25 in the T2-weighted images. Seven months after therapy, the ratios were 1.04 ± 0.16 in the T1-weighted and 1.18 ± 0.22 in the T2-weighted images.In examinations performed directly after the intervention, the T2-weighted images tend to underestimate the ablation zone, whereas T1-weighted images clearly better reflect the ablation zone. T1-weighted images therefore seem more adequate for repetitive monitoring of MR-guided RFA at 1.5 T.

Objectives To measure and compare the objective image quality of true noncontrast (TNC) images with virtual noncontrast (VNC) images acquired by tin-filter–enhanced, dual-source, dual-energy computed tomography (DECT) of upper abdomen. Materials and Methods Sixty-three patients received unenhanced abdominal CT and enhanced abdominal DECT (100/140 kV with tin filter) in portal-venous phase. VNC images were calculated from the DECT datasets using commercially available software. The mean attenuation of relevant tissues and image quality were compared between the TNC and VNC images. Image quality was rated objectively by measuring image noise and the sharpness of object edges using custom-designed software. Measurements were compared using Student two-tailed t -test. Correlation coefficients for tissue attenuation measurements between TNC and VNC were calculated and the relative deviations were illustrated using Bland-Altman plots. Results Mean attenuation differences between TNC and VNC (HU TNC − HU VNC ) image sets were as follows: right liver lobe −4.94 Hounsfield units (HU), left liver lobe −3.29 HU, vena cava −2.19 HU, spleen −7.46 HU, pancreas 1.29 HU, fat −11.14 HU, aorta 1.29 HU, bone marrow 36.83 HU (all P P P = .19). Conclusion The Hounsfield units in VNC images closely resemble TNC images in the majority of the organs of the upper abdomen (kidneys, liver, pancreas). In spleen and fat, Hounsfield numbers in VNC images are tend to be higher than in TNC images. VNC images show a low image noise and satisfactory edge sharpness. Other criteria of image quality and the depiction of certain lesions need to be evaluated additionally.

Hybrid whole-body magnetic resonance/positron emission tomography (MR/PET) systems are a new diagnostic tool enabling the simultaneous acquisition of morphologic and multiple functional data and thus allowing for a diversified characterization of oncological diseases.The aim of this study was to investigate the image and alignment quality of MR/PET in patients with pulmonary lesions and to compare the congruency of the 2 functional measurements of diffusion-weighted imaging (DWI) in MR imaging and 2-deoxy-[18F] fluoro-2-D-glucose (FDG) uptake in PET.A total of 15 patients were examined with a routine positron emission tomography/computer tomography (PET/CT) protocol and, subsequently, in a whole-body MR/PET scanner allowing for simultaneous PET and MR data acquisition. The PET and MR image quality was assessed visually using a 4-point score (1, insufficient; 4, excellent). The alignment quality of the rigidly registered PET/CT and MR/PET data sets was investigated on the basis of multiple anatomic landmarks of the lung using a scoring system from 1 (no alignment) to 4 (very good alignment). In addition, the alignment quality of the tumor lesions in PET/CT and MR/PET as well as for retrospective fusion of PET from PET/CT and MR images was assessed quantitatively and was compared between lesions strongly or less influenced by respiratory motion. The correlation of the simultaneously acquired DWI and FDG uptake in the pulmonary masses was analyzed using the minimum and mean apparent diffusion coefficient (ADC min and ADC mean) as well as the maximum and mean standardized uptake value (SUV max and SUV mean), respectively. In addition, the correlation of SUV max from PET/CT data was investigated as well. On lesions 3 cm or greater, a voxelwise analysis of ADC and SUV was performed.The visual evaluation revealed excellent image quality of the PET images (mean [SD] score, 3.6 [0.5]) and overall good image quality of DWI (mean [SD] score of 2.5 [0.5] for ADC maps and 2.7 [0.5] for diffusion-weighted images, respectively). The alignment quality of the data sets was very good in both MR/PET and PET/CT without significant differences (overall mean [SD] score of MR/PET, 3.8 [0.4]; PET/CT 3.6 [0.5]). Also, the alignment quality of the tumor lesions showed no significant differences between PET/CT and MR/PET (mean cumulative misalignment of MR/PET, 7.7 mm; PET/CT, 7.0 mm; P = 0.705) but between both modalities and a retrospective fusion (mean cumulative misalignment, 17.1 mm; P = 0.002 and P = 0.008 for PET/CT and MR/PET, respectively). Also, the comparison of the lesions strongly or less influenced by respiratory motion showed significant differences only for the retrospective fusion (21.3 mm vs 11.5 mm, respectively; P = 0.043). The ADC min and SUV max as measures of the cell density and glucose metabolism showed a significant reverse correlation (r = -0.80; P = 0.0006). No significant correlation was found between ADC mean and SUV mean (r = -0.42; P = 0.1392). Also, SUV max from the PET/CT data showed significant reverse correlation to ADC min (r = -0.62; P = 0.019). The voxelwise analysis of 5 pulmonary lesions each showed weak but significant negative correlation between ADC and SUV.Examinations of pulmonary lesions in a simultaneous whole-body MR/PET system provide diagnostic image quality in both modalities. Although DWI and FDG-PET reflect different tissue properties, there may very well be an association between the measures of both methods most probably because of increased cellularity and glucose metabolism of FDG-avid pulmonary lesions. A voxelwise DWI and FDG-PET correlation might provide a more sophisticated spatial characterization of pulmonary lesions.

Purpose: In patients with a neuroendocrine tumour (NET), the extent of disease strongly influences the outcome and multidisciplinary therapeutic management. Thus, systematic analysis of the diagnostic performance of the existing staging modalities is necessary. The aim of this study was to compare the diagnostic performance of 2 whole-body imaging modalities, [68Ga]DOTATOC positron emission tomography (PET)/computed tomography (CT) and magnetic resonance imaging (MRI) in patients with NET with regard to possible impact on treatment decisions. Materials and methods: [68Ga]DOTATOC-PET/CT and whole-body magnetic resonance imaging (wbMRI) were performed on 51 patients (25 females, 26 males, mean age 57 years) with histologically proven NET and suspicion of metastatic spread within a mean interval of 2.4 days (range 0–28 days). PET/CT was performed after intravenous administration of 150 MBq [68Ga]DOTATOC. The CT protocol comprised multiphase contrast-enhanced imaging. The MRI protocol consisted of standard sequences before and after intravenous contrast administration at 1.5 T. Each modality (PET, CT, PET/CT, wbMRI) was evaluated independently by 2 experienced readers. Consensus decision based on correlation of all imaging data, histologic and surgical findings and clinical follow-up was established as the standard of reference. Lesion-based and patient-based analysis was performed. Detection rates and accuracy were compared using the McNemar test. P values

Purpose The aim of this study was to implement a time effective 1-1 double pulse water-selective excitation (WE) into a three-dimensional ultrashort echo time (UTE) sequence (WE-UTE) for visualization of short-T2 tissues with positive contrast and sufficient suppression of surrounding fat. Methods First, an analytical description of magnetization components in the steady state applying WE-UTE was derived and results were compared with numerical simulations based on Bloch's equations. Parameters were optimized for best positive contrast between short-T2 tissues and fat under consideration of variable relaxation properties over a broad range. Maximal signal yield and signal efficiency of on-resonant protons were compared with UTE sequences with and without off-resonance fat saturation (FatSat). WE-UTE was exemplarily applied for in-vivo musculoskeletal imaging on a 3T whole-body MR unit. Results Steady state magnetization of WE-UTE could be described analytically and showed excellent accordance with numerical simulations. Even for tissues with T2 = 1 ms WE-UTE resulted in 79% of maximal signal yield of UTE without FatSat and was more efficient regarding signal yield if compared with UTE with FatSat. Using WE-UTE in-vivo tendons and ligaments could be well delineated with positive contrast to surrounding fat. Conclusion WE-UTE provides a quick method for visualizing short-T2 tissues with positive contrast. Magn Reson Med 71:534–543, 2014. © 2013 Wiley Periodicals, Inc.

The efficacy of drug-eluting balloons has been demonstrated in clinical trials. The drug predominantly used is paclitaxel because of its lipophilic properties and the rapid onset of action. The aim of the investigation was to evaluate the feasibility and efficacy of an alternative balloon coating with rapamycin that can be applied on site.The balloon coating (3.0/18 and 3.0/12 mm, Cathy No. 4, Translumina GmbH) with rapamycin was conducted with a coating machine (Translumina GmbH). Concentrations were 2, 2 × 2, 3, and 4 %. Measurements regarding the amount of substance released to the vessel wall were carried out on explanted porcine coronaries by means of ultraviolet and visible-light spectroscopy. Inflation time varied between 30 and 120 s. The biological effect of the coating was evaluated in a porcine peripheral overstretch and stent implantation model.The amount of rapamycin on the balloon surface ranged from 558 ± 108 μg for the 2 % solution to 1,441 ± 228 μg in the 4 % solution. An amount of 95 ± 63-193 ± 113 μg was released into the vessel wall. The quantitative measurements of the angiographic examinations 4 weeks after treatment revealed a reduction of diameter stenosis from 20.6 ± 17.4 % in the control group to 11.6 ± 5.5 % in the drug-eluting balloon group.A balloon coating with rapamycin omitting an excipient is possible with a dose-adjustable coating machine. However, the biological effects are moderate, which make further optimization of the coating process and evaluation of appropriate excipients necessary.

Computed tomographic angiography is the standard in routine follow-up after endovascular aneurysm repair, causing radiation exposure; thus, dose-saving strategies should be applied. The aim of this study was to evaluate the novel sinogram-affirmed iterative reconstruction (SAFIRE) algorithm in terms of clinical usability and potential reduction of radiation exposure.Forty-six patients underwent computed tomographic angiographic follow-up after endovascular aneurysm repair. Data were acquired using a dual-source computed tomographic scanner running both x-ray tubes at the same voltage (120 kV). Raw data were reconstructed using projections of both tubes with filtered back projection (FBP) and of only one tube with FBP and SAFIRE, corresponding to synthetic acquisition with half the radiation dose of the clinical routine radiation dose. Image sets were objectively compared regarding signal-to-noise ratio and edge sharpness. Two radiologists independently assessed a set of subjective criteria, including diagnostic usability, depiction of contrasted vessels, and image noise.Half-dose (HD) SAFIRE images showed significantly higher signal-to-noise ratios compared to full-dose FBP images (P.001), while having equal edge sharpness (P = .56). Most of the subjectively assessed parameters, such as diagnostic usability and depiction of contrasted vessels, were rated similar for HD SAFIRE and full-dose FBP images. Full-dose FBP images depicted fine anatomic structures more clearly (P.05), while HD SAFIRE data sets showed less noise (P.01). HD FBP images performed worse on all criteria (P.001). Interrater agreement was good (κ = 0.74-0.80).Using the SAFIRE algorithm, the radiation dose of high-contrast abdominal computed tomographic angiography is reducible from routine clinical levels by up to 50% while maintaining good image quality and diagnostic accuracy.

Arterial spin labeling (ASL) is a non-invasive magnetic resonance technique for tissue perfusion quantification working without contrast media application. The method uses magnetically labeled blood protons as intrinsic tracer. Perfusion-weighted images are obtained by the signal difference between an image with proximal labeling of the arterial water protons and a control image. Initially designed for cerebral perfusion measurement, the ASL technique is increasingly being used for the evaluation of extracranial organs which might be attributed to the improvements in scanner, coil and sequence technology but also to the elaboration of postprocessing tools. In this review, the basic principles of ASL are explained. Technical difficulties in ASL sequence design are discussed. To illustrate the potential role of ASL in clinical research and diagnostics, comparison of ASL with other methods currently applied for perfusion assessment is performed. Finally, a variety of clinical applications of ASL is presented with respect to the current literature.

The aim of this study was to investigate correlations between glucose metabolism as determined by [18F]FDG PET/CT and tumour perfusion as quantified by volume perfusion CT in primary tumours and mediastinal lymph nodes (MLN) of patients with non-small-cell lung cancer (NSCLC). Enrolled in the study were 17 patients with NSCLC. [18F]FDG uptake was quantified in terms of SUVmax and SUVavg. Blood flow (BF), blood volume (BV) and flow extraction product (Ktrans) were determined as perfusion parameters. The correlations between the perfusion parameters and [18F]FDG uptake values were subsequently evaluated. For the primary tumours, no correlations were found between perfusion parameters and [18F]FDG uptake. In MLN, there were negative correlations between BF and SUVavg (r = −0.383), BV and SUVavg (r = −0.406), and BV and SUVmax (r = −0.377), but not between BF and SUVmax, Ktrans and SUVavg, or Ktrans and SUVmax. Additionally, in MLN with SUVmax >2.5 there were negative correlations between BF and SUVavg (r = −0.510), BV and SUVavg (r = −0.390), BF and SUVmax (r = −0.536), as well as BV and SUVmax (r = −0.346). Perfusion and glucose metabolism seemed to be uncoupled in large primary tumours, but an inverse correlation was observed in MLN. This information may help improve therapy planning and response evaluation.