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OBJECTIVES The aim of this study was to compare the diagnostic accuracy of apparent diffusion coefficient (ADC) ratios as a monoparametric magnetic resonance imaging (MRI) protocol for the detection of prostate cancer (PCa) with the established multiparametric (mp) MRI at 3.0 T. MATERIALS AND METHODS According to power analysis, 52 male patients were included in this monocenter study with prospective data collection and retrospective, blinded multireader image analysis. The study was approved by the local ethics committee. Patients were recruited from January to December 2020. Based on mpMRI findings, patients underwent in-bore MR biopsy or prostatectomy for histopathologic correlation of suspicious lesions. Three readers, blinded to the histopathologic results and images of mpMRI, independently evaluated ADC maps for the detection of PCa. The ADC ratio was defined as the lowest signal intensity (SI) of lesions divided by the SI of normal tissue in the zone of origin. Predictive accuracy of multiparametric and monoparametric MRI were compared using logistic regression analysis. Moreover, both protocols were compared applying goodness-of-fit analysis with the Hosmer-Lemeshow test for continuous ADC ratios and Pearson χ2 test for binary decision calls, correlation analysis with Spearman ρ and intraclass correlation coefficients, as well as noninferiority assessment with a TOST ("two one-sided test"). RESULTS Eighty-one histopathologically proven, unique PCa lesions (Gleason score [GS] ≥ 3 + 3) in 52 patients could be unequivocally correlated, with 57 clinically significant (cs) PCa lesions (GS ≥ 3 + 4). Multiparametric MRI detected 95%, and monoparametric ADC detected ratios 91% to 93% of csPCa. Noninferiority of monoparametric MRI was confirmed by TOST (P < 0.05 for all comparisons). Logistic regression analysis revealed comparable predictive diagnostic accuracy of ADC ratios (73.7%-87.8%) versus mpMRI (72.2%-84.7%). Spearman rank correlation coefficient for PCa aggressiveness revealed satisfactory correlation of ADC ratios (P < 0.013 for all correlations). The Hosmer-Lemeshow test for the logistic regression analysis for continuous ADC ratios indicated adequate predictive accuracy (P = 0.55-0.87), and the Pearson χ2 test showed satisfactory goodness of fit (P = 0.35-0.69, χ2 = 0.16-0.87). CONCLUSIONS Normalized ADC ratios based on advanced DWI are noninferior to mpMRI at 3.0 T for the detection of csPCa in a preselected patient cohort and proved a fast and accurate assessment tool, thus showing a potential prospect of easing the development of future screening methods for PCa.

We present an endovascular approach for anatomic reconstruction of the iliac bifurcation in life-threatening arterioureteral fistula without sacrificing the pelvic arterial vascular supply. Five consecutive patients suffering from acute onset of significant gross hematuria caused by iliac-ureteral fistula resulting from previous oncologic surgery and radiation therapy were treated by transfemoral stent graft implantation in a double-barrel technique. Iliac-ureteral pseudoaneurysm coverage succeeded in an iliac neobifurcation with preservation of pelvic perfusion. Follow-up ranging from 9 to 37 months confirmed cessation of hematuria. One patient experienced stent graft thrombosis of the external iliac artery as a result of large cervical cancer invasion treated by crossover bypass. In all other patients, stent grafts were patent.

Background For peripheral artery disease (PAD), MR angiography (MRA) is a well-established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this. Purpose To evaluate the diagnostic accuracy of time-resolved 4D MR-angiography with interleaved stochastic trajectories (TWIST-MRA) by using maximum intensity projections (MIPs) of dynamic images acquired with reduced doses of contrast agent. Study type Retrospective. Population Forty adult PAD patients yielding 1088 artery segments. Field strength/sequence A 3.0 T, time-resolved 4D MR-angiography with TWIST-MRA and MIP of dynamic images. Assessment DSA was available in 14 patients (256 artery segments) and used as reference standard. Three-segmental MIP reconstructions of TWIST-images after administration of 3 mL of gadolinium-based contrast agent (Gadoteridol/Prohance®, 0.5 M) per anatomical level (pelvis, thighs, and lower legs) yielded 256 artery segments for correlation between MRA and DSA. Three independent observers rated image quality (scale: 1 [nondiagnostic] to 4 [excellent]) and the degree of venous overlay (scale: 0 [none] to 2 [significant]) for all segments. Diagnostic accuracy for the detection of >50% stenosis and artery occlusion was calculated for all observers. Statistical tests Binary classification test (sensitivity, specificity, positive/negative predictive values, diagnostic accuracy). Intraclass correlation coefficients (ICCs), logistic regression analysis with comparison of areas under the receiver-operating-characteristics (ROC) curves (AUCs) with the DeLong method. Bland-Altman-comparison. Results High diagnostic performance was achieved for the detection of >50% stenosis (sensitivity 92.9% [84.3-99.9% (95%-CI)] and specificity 98.5% [95.7-99.8% (95%-CI)]) and artery occlusion (sensitivity 93.1% [77.2-99.2% (95%-CI)] and specificity 99.1% [96.9-99.9% (95%-CI)]). Inter-reader agreement was excellent with ICC values ranging from 0.95 to 1.0 for >50% artery stenosis and occlusion. Image quality was good to excellent for both readers (3.41 ± 0.72, 3.33 ± 0.65, and 3.38 ± 0.61 [mean ± SD]) with good correlation between observer ratings (ICC 0.71-0.81). No significant venous overlay was observed (0.06 ± 0.24, 0.23 ± 0.43 and 0.11 ± 0.45 [mean ± SD]). Data conclusion MIPs of dynamic TWIST-MRA offer a promising diagnostic alternative necessitating only reduced amounts (50%) of gadolinium-based contrast agents for the entire runoff vasculature. Evidence level 3 TECHNICAL EFFICACY: Stage 2.

The study described here systematically analyzed how specific artifacts in contrast-enhanced ultrasound (CEUS) can affect the detection of endoleaks during follow-up after endovascular aortic repair (EVAR). Patients undergoing EVAR of atherosclerotic or mycotic abdominal aortic aneurysms using various standard and branched stent-graft material for visceral and iliac preservation were enrolled over 5 y and followed up with computed tomography angiography (CTA) and CEUS simultaneously. CEUS artifacts were frequently identified after EVAR procedures (59% of examinations) and were caused mainly by contrast agent, different prosthesis or embolization material and postinterventional changes in the aneurysm sac. This article describes how to identify important artifacts and how to avoid false-negative or false-positive interpretations of endoleaks. Despite artifacts, CEUS had higher sensitivity for endoleak detection after EVAR than CTA. CEUS was superior to CTA in the identification of late endoleaks type II and in follow-up examinations after embolization procedures, where beam-hardening artifacts limited CTA.

Purpose: Unintended false-lumen thoracic endovascular aortic repair (TEVAR) is under-reported and often fatal. We present percutaneous endovascular rescue techniques for true-lumen reperfusion with strategies to address the peripheral artery perfusion needs unique to each case. Case Report: Two patients deteriorated 24 hours after uncomplicated and complicated acute aortic type-B dissection TEVAR treatment at a tertiary community hospital. Reevaluation of index and repeated imaging studies revealed inadvertent false-lumen TEVAR with severe visceral and peripheral ischemia. Stepwise subtraction angiography was used to confirm continuous true-lumen catheterization from femoral puncture into the thoracic aorta. Retrograde fenestration distal to the misplaced TEVAR from the true- into the false-lumen allowed for snorkeling by distal stent-extension across the dissection membrane. In one case, TEVAR stent graft extension resulted in true-lumen re-expansion and in the other case, bare-metal stent-extension for stabilization of the dissection membrane resulted in true-lumen re-expansion in addition to preservation of visceral and peripheral perfusion via the false-lumen. Despite excellent acute hemodynamic results and initial signs of recovery, both patients eventually died (multiorgan failure; cerebral hemorrhagic infarction). Conclusion: Correct indication and prompt recognition of potential inadvertent false-lumen stenting is critical to avoid disastrous sequelae, for example, malperfusion. Endovascular salvage is feasible for restoration of correct perfusion and must be performed in a timely manner. Clinical Impact Clinically apparent, complicated type-B dissection necessitates instantaneous treatment. Prerequisite for an endovascular approach is a true-lumen guidewire continuously from access to the ascending aorta. DSA after TEVAR and prompt clinical re-evaluation are to verify effective visceral and peripheral restoration of blood flow. Despite these measures, inadvertent false-lumen TEVAR may occur rarely. Immediate recognition may allow for timely true-lumen re-expansion using percutaneous endovascular salvage techniques e.g. retrograde fenestration from the true- into the false-lumen for distal snorkeling of the misplaced TEVAR across the dissection membrane. However, morbidity and mortality are very high, if erroneous stent graft placement is not identified early.

For students, early hands-on experience is very limited and often non-existent during study time. Thus, we aimed to evaluate the progress of inexperienced medical students in successfully establishing an ultrasound-guided vessel access. One brief, condensed single teaching lesson in a prior to post-teaching scenario was performed using an inexpensive, self-made phantom model. In this prospective study, medical students (n = 11) with no experience in ultrasound imaging performed an ultrasound-guided vessel access simulated by a gelatin-based phantom model. Success rates and time of procedures were measured. Afterwards, participants underwent dedicated supervised teaching in a single lesson (duration 30 min) with both theoretical information given and practical training skills shown. Then, every student performed the very same procedure again and results were compared with paired t test. Success rate of guide wire placement rose from 36.4 (4/11) to 100%. Mean number of attempts significantly decreased with 2.5 SD1.3 before and 1.2 SD0.4 after teaching (p < 0.05). Overall time to successful guide wire placement improved from 291 SD8 to 151 SD37 s (p < 0.05). With already limited training time and opportunities available during medical education, short and simple, but highly effective training tools are invaluable. With the help of an inexpensive, self-made gelatin-based phantom model for ultrasound-guided vascular access, medical students demonstrate significantly improved practical puncture skills after only one brief, condensed teaching lesson and thus an important progress with regard to their future clinical routine. The performance of ultrasound-guided vascular access can be highly improved for inexperienced medical students by applying one short teaching session using an inexpensive, self-made phantom model.

PURPOSE The aim of this study was to evaluate in vitro and in vivo the enhancement properties of experimental gadolinium (Gd)-based contrast agents (GBCAs) with different molecular weights and hydration numbers (P846 and gadopiclenol) compared with clinically approved low-molecular, extracellular agents (gadopentetate and gadoterate) at 9.4 T and to discuss influencing factors on r1 relaxivities. METHODS AND MATERIALS All experiments were performed with a 9.4 T animal scanner (Bruker, Germany). We performed relaxometry measurements for all contrast agents in human plasma at 37°C using an IR-RARE sequence. In addition, we compared P846 with gadopentetate and gadopiclenol with gadoterate intraindividually in rats with hepatic colorectal cancer metastases (n = 10 each) acquiring T1-weighted FLASH sequences before and at 10 consecutive time points during 20 minutes. After intravenous contrast agent application, signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), and lesion enhancement (LE) for liver parenchyma and tumors were calculated based on region of interest measurements. RESULTS Longitudinal relaxivities (r1) of the low-molecular agents were lower as compared with the experimental compounds. However, r1 of gadopentetate and gadoterate demonstrated only a moderate decrease of r1 at 9.4 T as compared with known data at lower field strengths (gadopentetate: r1 [at 9.4 T], 3.4 mM s/r1 [at 1.5 T], 4.1 mM s/gadoterate: r1 [at 9.4 T], 3.1 mM s/r1 [at 1.5 T], 3.6 mM s). In contrast, r1 of P846 showed a marked reduction at 9.4 T compared with 1.5 T (P846: r1 [at 9.4 T], 6.4 mM s/r1 [at 1.5 T], 32 mM s). Gadopiclenol provided the highest r1 in this study at 9.4 T and the drop of r1 as compared with lower field strength is less apparent (gadopiclenol: r1 [at 9.4 T], 8.7 mM s/r1 [at 1.5 T], 12.7 mM s).In vivo, P846 and gadopiclenol showed significantly higher SNR, CNR, and LE as compared with the low-molecular control agents (mean ± SD; SNRliver [gadopentetate, 18.1 ± 1.2; P846, 27.2 ± 1.5; P < 0.001]; SNRtumor [gadopentetate, 22.6 ± 1.9; P846, 40.1 ± 1.9; P < 0.001]; CNR [gadopentetate, 4.6 ± 1.0; P846, 12.9 ± 0.9; P < 0.001]; LE [gadopentetate, 7.2 ± 1.9; P846, 14.9 ± 1.9; P < 0.001]/SNRliver [gadoterate, 8.8 ± 0.5; gadopiclenol, 12.6 ± 1.3; P < 0.001]; SNRtumor [gadoterate, 11.3 ± 1.2; gadopiclenol, 20.9 ± 2.9; P < 0.001]; CNR [gadoterate, 2.5 ± 0.7; gadopiclenol, 8.3 ± 1.7; P < 0.001]; LE [gadoterate, 4.4 ± 1.2; gadopiclenol, 13.0 ± 2.9; P < 0.001]). Thus, for equal Gd doses, gadopiclenol and P846 increase the CNR of liver metastases by a factor of 2.5 to 3 at 9.4 T compared with gadoterate and gadopentetate. CONCLUSIONS P846 and gadopiclenol provide superior enhancement at 9.4 T as compared with gadopentetate and gadoterate. However, the macromolecular agent P846 shows a marked decrease of r1 from 1.5 T to 9.4 T. This effect is less apparent for the low-molecular agents gadopiclenol, gadopentetate, and gadoterate. Yet, based on the higher hydration number, r1 of P846 and gadopiclenol are markedly higher as compared with the reference contrast agents. Thus, building compounds with moderately increased molecular size and hydration number, as implemented in gadopiclenol, seems to be a promising way to develop highly effective GBCAs.Advantages for gadopiclenol include a strong enhancement regardless of the external magnetic field strength, pharmacokinetics comparable to those of clinically approved extracellular GBCAs, and the potential to either improve sensitivity in diagnostic magnetic resonance imaging by improving lesion conspicuity or to perform studies with significantly reduced Gd-dose while at the same time providing comparable diagnostic accuracy. However, all this needs to be proven in clinical studies.

Introduction Acute pulmonary embolism (PE) is a leading cardiovascular cause of death, resembling a common indication for emergency computed tomography (CT). Nonetheless, in clinical routine most CTs performed for suspicion of PE excluded the suspected diagnosis. As patients with low to intermediate risk for PE are triaged according to the d-dimer, its relatively low specifity and widespread elevation among elderly might be an underlying issue. Aim of this study was to find potential predictors based on initial emergency blood tests in patients with elevated d-dimers and suspected PE to further increase pre-test probability. Methods In this retrospective study all patients at the local university hospital's emergency room from 2009 to 2019 with suspected PE, emergency blood testing and CT were included. Cluster analysis was performed to separate groups with distinct laboratory parameter profiles and PE frequencies were compared. Machine learning algorithms were trained on the groups to predict individual PE probability based on emergency laboratory parameters. Results Overall, PE frequency among the 2045 analyzed patients was 41%. Three clusters with significant differences (p ≤ 0.05) in PE frequency were identified: C1 showed a PE frequency of 43%, C2 40% and C3 33%. Laboratory parameter profiles (e.g. creatinine) differed significantly between clusters (p ≤ 0.0001). Both logistic regression and support-vector machines were able to predict clusters with an accuracy of over 90%. Discussion Initial blood parameters seem to enable further differentiation of patients with suspected PE and elevated d-dimers to raise pre-test probability of PE. Machine-learning-based prediction models might help to further narrow down CT indications in the future.

For peripheral artery disease (PAD), MR angiography (MRA) is a well-established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this.To evaluate the diagnostic accuracy of time-resolved 4D MR-angiography with interleaved stochastic trajectories (TWIST-MRA) by using maximum intensity projections (MIPs) of dynamic images acquired with reduced doses of contrast agent.Retrospective.Forty adult PAD patients yielding 1088 artery segments.A 3.0 T, time-resolved 4D MR-angiography with TWIST-MRA and MIP of dynamic images.DSA was available in 14 patients (256 artery segments) and used as reference standard. Three-segmental MIP reconstructions of TWIST-images after administration of 3 mL of gadolinium-based contrast agent (Gadoteridol/Prohance®, 0.5 M) per anatomical level (pelvis, thighs, and lower legs) yielded 256 artery segments for correlation between MRA and DSA. Three independent observers rated image quality (scale: 1 [nondiagnostic] to 4 [excellent]) and the degree of venous overlay (scale: 0 [none] to 2 [significant]) for all segments. Diagnostic accuracy for the detection of50% stenosis and artery occlusion was calculated for all observers.Binary classification test (sensitivity, specificity, positive/negative predictive values, diagnostic accuracy). Intraclass correlation coefficients (ICCs), logistic regression analysis with comparison of areas under the receiver-operating-characteristics (ROC) curves (AUCs) with the DeLong method. Bland-Altman-comparison.High diagnostic performance was achieved for the detection of50% stenosis (sensitivity 92.9% [84.3-99.9% (95%-CI)] and specificity 98.5% [95.7-99.8% (95%-CI)]) and artery occlusion (sensitivity 93.1% [77.2-99.2% (95%-CI)] and specificity 99.1% [96.9-99.9% (95%-CI)]). Inter-reader agreement was excellent with ICC values ranging from 0.95 to 1.0 for50% artery stenosis and occlusion. Image quality was good to excellent for both readers (3.41 ± 0.72, 3.33 ± 0.65, and 3.38 ± 0.61 [mean ± SD]) with good correlation between observer ratings (ICC 0.71-0.81). No significant venous overlay was observed (0.06 ± 0.24, 0.23 ± 0.43 and 0.11 ± 0.45 [mean ± SD]).MIPs of dynamic TWIST-MRA offer a promising diagnostic alternative necessitating only reduced amounts (50%) of gadolinium-based contrast agents for the entire runoff vasculature.3 TECHNICAL EFFICACY: Stage 2.

Background. This paper aimed to prospectively evaluate the safety of embolization therapy of pulmonary arteriovenous malformations (PAVMs) for the detection of cerebral infarctions by pre- and post-interventional MRI. Method One hundred and five patients (male/female = 44/61, mean age 48.6+/−15.8, range 5–86) with pre-diagnosed PAVMs on contrast-enhanced MRA underwent embolization therapy. The number of PAVMs treated in each patient ranged from 1–8 PAVMs. Depending on the size and localization of the feeding arteries, either Nester-Coils or Amplatzer vascular plugs were used for embolization therapy. cMRI was performed immediately before, and at the 4 h and 3-month post-embolization therapy. Detection of peri-interventional cerebral emboli was performed via T2w and DWI sequences using three different b-values, with calculation of ADC maps. Results Embolization did not show any post-/peri-interventional, newly developed ischemic lesions in the brain. Only one patient who underwent re-embolization and was previously treated with tungsten coils that corroded over time showed newly developed, small, diffuse emboli in the post-interventional DWI sequence. This patient already had several episodes of brain emboli before re-treatment due to the corroded coils, and during treatment, when passing the corroded coils, experienced additional small, clinically inconspicuous brain emboli. However, this complication was anticipated but accepted, since the vessel had to be occluded distally. Conclusion Catheter-based embolization of PAVMs is a safe method for treatment and does not result in clinically inconspicuous cerebral ischemia, which was not demonstrated previously.

OBJECTIVE. The purpose of this study was to evaluate radiation dose, effective dose, and image quality of different low-dose abdominal CT protocols in a swine model and an anthropomorphic phantom u...

Background Transarterial chemoembolization (TACE) is an important therapy for hepatocellular carcinoma (HCC) in cirrhosis. In particular in advanced cirrhosis, post-TACE hepatic failure liver (PTHF) failure may develop. Currently, there is no standardization for the periinterventional risk assessment. The liver maximum capacity (LiMAx) test assesses the functional liver capacity, but has not been investigated in this setting. Aims The aim of this study was to prospectively evaluate periinterventional LiMAx and CT volumetry measurements in patients with cirrhosis and HCC undergoing repetitive TACE. Methods From 06/2016 to 11/2017, eleven patients with HCC and cirrhosis undergoing TACE were included. LiMAx measurements (n = 42) were conducted before and after each TACE. Laboratory parameters were correlated with the volume–function data. Results The median LiMAx levels before (276 ± 166 µg/kg/h) were slightly reduced after TACE (251 ± 122 µg/kg/h; p = 0.08). This corresponded to a median drop of 7.1%. Notably, there was a significant correlation between LiMAx levels before TACE and bilirubin (but not albumin nor albumin–bilirubin [ALBI] score) increase after TACE (p = 0.02, k = 0.56). Furthermore, a significantly higher increase in bilirubin in patients with LiMAx ≤ 150 µg/kg/h was observed (p = 0.011). LiMAx levels at different time points in single patients were similar (p = 0.2). Conclusion In our prospective pilot study in patients with HCC and cirrhosis undergoing multiple TACE, robust and reliable LiMAx measurements were demonstrated. Lower LiMAx levels before TACE were associated with surrogate markers (bilirubin) of liver failure after TACE. Specific subgroups at high risk of PTHF should be investigated. This might facilitate the future development of strategies to prevent occurrence of PTHF.

Background Computed tomography (CT) is the standard procedure for follow-up of non-small-cell lung cancer (NSCLC) after radiochemotherapy. CT has difficulties differentiating between tumor, atelectasis and radiation induced lung toxicity (RILT). Diffusion-weighted imaging (DWI) may enable a more accurate detection of vital tumor tissue. The aim of this study was to determine the diagnostic value of MRI versus CT in the follow-up of NSCLC. Methods Twelve patients with NSCLC stages I-III scheduled for radiochemotherapy were enrolled in this prospective study. CT with i.v. contrast agent and non enhanced MRI were performed before and 3, 6 and 12 months after treatment. Standardized ROIs were used to determine the apparent diffusion weighted coefficient (ADC) within the tumor. Tumor size was assessed by the longest longitudinal diameter (LD) and tumor volume on DWI and CT. RILT was assessed on a 4-point-score in breath-triggered T2-TSE and CT. Results There was no significant difference regarding LD and tumor volume between MRI and CT (p≥ 0.6221, respectively p≥ 0.25). Evaluation of RILT showed a very high correlation between MRI and CT at 3 (r = 0.8750) and 12 months (r = 0.903). Assessment of the ADC values suggested that patients with a good tumor response have higher ADC values than non-responders. Conclusions DWI is equivalent to CT for tumor volume determination in patients with NSCLC during follow up. The extent of RILT can be reliably determined by MRI. DWI could become a beneficial method to assess tumor response more accurately. ADC values may be useful as a prognostic marker.

Background: This prospective study evaluated the learning curve of inexperienced medical students in successfully establishing an ultrasound guided vessel access. Methods: Medical students (n=11) with no experience in ultrasound imaging were asked to perform an ultrasound- guided vessel access simulated by a gelatin based phantom model. Success rates and time of procedures were measured. Afterwards, every student underwent peer-teaching with both theoretical information given and practical training skills applied. Then, every student had to perform the very same procedure again and results were compared in a prior- to post-teaching scenario with paired t-test. Results: After theoretical and practical teaching lessons all students were able to successfully establish an ultrasound-guided vascular access. Prior to teaching sessions, only 4 out of 11 students managed to successfully perform the procedure. Success rate rose from 36.4% to 100%. Mean number of attempts were 2.5 +- 1.3 before, and 1.2 +- 0.4 after teaching (p < 0.05). Overall time to successful guide wire placement improved from 291+-8 seconds to 151+-37 seconds (p

To prospectively evaluate the relationship of established inflammatory markers and presepsin on nonocclusive mesenteric ischemia and to correlate presepsin levels to the occurrence and severity of nonocclusive mesenteric ischemia.Patients were prospectively enrolled and blood samples taken, followed by a retrospective evaluation of laboratory values and angiographic findings. The study was ethics committee approved.Patients with clinical suspicion of nonocclusive mesenteric ischemia underwent catheter angiography of the superior mesenteric artery. Images were assessed by two experienced radiologists on consensus basis using a previously published standardized reporting system (Homburg-Nonocclusive Mesenteric Ischemia-Score). Two groups were formed according to the severity of nonocclusive mesenteric ischemia, mild and severe, patients without clinical signs of nonocclusive mesenteric ischemia formed the reference group. These data were correlated to inflammatory blood markers assessed pre- and postoperatively: C-reactive protein, leucocytes, procalcitonin, and presepsin as well as outcome data.Between January 2010 and March 2011, a total of 839 patients undergoing cardiovascular surgery participated in this study.Mild nonocclusive mesenteric ischemia was diagnosed in 4.5%, and severe nonocclusive mesenteric ischemia in 3.2%. Median postoperative presepsin concentrations were significantly greater in mild and severe nonocclusive mesenteric ischemia than in non-nonocclusive mesenteric ischemia. Statistics showed that postoperative presepsin better discriminated mild and severe nonocclusive mesenteric ischemia than any other tested biomarker.Elevated postoperative plasma presepsin concentrations are an independent predictor of mild and severe nonocclusive mesenteric ischemia. The established inflammatory blood markers significantly correlate with the development and severity of nonocclusive mesenteric ischemia.

Objectives Magnetic resonance lymphography (MRL) in small animals is a promising but challenging tool in preclinical lymphatic research. In this study, we compared the gadolinium (Gd)-based nanoparticle AGuIX with Gd-DOTA for interstitial MRL in healthy rats and in a chronic rat hindlimb lymphedema model. Materials and Methods A comparative study with AGuIX and Gd-DOTA for interstitial MRL was performed in healthy Lewis rats (n = 6). For this purpose, 75 μL of 3 mM AGuIX (containing 30 mM Gd-DOTA side residues) and 75 μL 30 mM Gd-DOTA were injected simultaneously in the right and left hindlimbs. Repetitive high-resolution, 3-dimensional time-of-flight gradient recalled echo MRL sequences were acquired over a period of 90 minutes using a 9.4 T animal scanner. Gadofosveset-enhanced MR angiography and surgical dissection after methylene blue injection served as supportive imaging techniques. In a subsequent proof-of-principle study, AGuIX-based MRL was investigated in a hindlimb model of chronic lymphedema (n = 4). Lymphedema of the right hindlimbs was induced by means of popliteal and inguinal lymphadenectomy and irradiation with 20 Gy. The nonoperated left hindlimbs served as intraindividual controls. Six, 10, and 14 weeks after lymphadenectomy, MRL investigations were performed to objectify lymphatic reorganization. Finally, skin samples of the lymphedematous and the contralateral control hindlimbs were analyzed by means of histology and immunohistochemistry. Results AGuIX-based MRL resulted in high-resolution anatomical depiction of the rodent hindlimb lymphatic system. Signal-to-noise ratio and contrast-to-noise ratio of the popliteal lymph node were increased directly after injection and remained significantly elevated for up to 90 minutes after application. AGuIX provided significantly higher and prolonged signal intensity enhancement as compared with Gd-DOTA. Furthermore, AGuIX-based MRL demonstrated lymphatic regeneration in the histopathologically verified chronic lymphedema model. Collateral lymphatic vessels were detectable 6 weeks after lymphadenectomy. Conclusions This study demonstrates that AGuIX is a suitable contrast agent for preclinical interstitial MRL in rodents. AGuIX yields anatomical imaging of lymphatic vessels with diameters greater than 200 μm. Moreover, it resides in the lymphatic system for a prolonged time. AGuIX may therefore facilitate high-resolution MRL-based analyses of the lymphatic system in rodents.

BACKGROUND AND PURPOSE: Signal intensity increases possibly suggestive of gadolinium retention have recently been reported on unenhanced T1-weighted images of the pediatric brain following multiple exposures to gadolinium-based MR contrast agents. Our aim was to determine whether T1 signal changes suggestive of gadolinium deposition occur in the brains of pediatric nonneurologic patients after multiple exposures to gadobenate dimeglumine. MATERIALS AND METHODS: Thirty-four nonneurologic patients (group 1; 17 males/17 females; mean age, 7.18 years) who received between 5 and 15 injections (mean, 7.8 injections) of 0.05 mmol/kg of gadobenate during a mean of 2.24 years were compared with 24 control patients (group 2; 16 males/8 females; mean age, 8.78 years) who had never received gadolinium-based contrast agents. Exposure to gadobenate was for diagnosis and therapy monitoring. Five blinded readers independently determined the signal intensity at ROIs in the dentate nucleus, globus pallidus, pons, and thalamus on unenhanced T1-weighted spin-echo images from both groups. Unpaired t tests were used to compare signal-intensity values and dentate nucleus–pons and globus pallidus–thalamus signal-intensity ratios between groups 1 and 2. RESULTS: Mean signal-intensity values in the dentate nucleus, globus pallidus, pons, and thalamus of gadobenate-exposed patients ranged from 366.4 to 389.2, 360.5 to 392.9, 370.5 to 374.9, and 356.9 to 371.0, respectively. Corresponding values in gadolinium-based contrast agent–naive subjects were not significantly different ( P > .05). Similarly, no significant differences were noted by any reader for comparisons of the dentate nucleus–pons signal-intensity ratios. One reader noted a difference in the mean globus pallidus–thalamus signal-intensity ratios (1.06 ± 0.006 versus 1.02 ± 0.009, P = .002), but this reflected nonsignificantly higher T1 signal in the thalamus of control subjects. The number of exposures and the interval between the first and last exposures did not influence signal-intensity values. CONCLUSIONS: Signal-intensity increases potentially indicative of gadolinium deposition are not seen in pediatric nonneurologic patients after multiple exposures to low-dose gadobenate.

Purpose To investigate the potential of 3D ultrashort echo time MRI and short T2 images generated by subtraction for determination of total tumor burden in lung cancer. Methods As an animal model of spontaneously developing non–small cell lung cancer, the K-rasLA1 transgenic mouse was used. Three-dimensional MR imaging was performed with radial k-space acquisition and echo times of 20 µs and 1 ms. For investigation of the short T2 component in the recorded signal, subtraction images were generated from these data sets and used for consensus identification of tumors. Next, manual segmentation was performed on all MR images by two independent investigators. MRI data were compared with the results from histologic investigations and among the investigators. Results Tumor number and total tumor burden from imaging experiments correlated strongly with the results of histologic investigations. Intra- and interuser comparison showed highest correlations between the individual measurements for ultra-short TE MRI. Conclusions Three-dimensional MRI protocols facilitate accurate tumor identification in mice harboring lung tumors. Ultrashort TE MRI is the superior imaging strategy when investigating lung tumors of miscellaneous size with 3D MR imaging strategies. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

Background This was a retrospective single-center evaluation for off-label use of a single Angio-Seal-VIP 8F vascular closure device (VCD) (Terumo Interventional Systems, Somerset, NJ, USA) for retrograde transfemoral arterial access exceeding 8F. Methods Between 2010 and 2018, in 32 consecutive patients (3 females; mean age 67 ± 9; range 46–86 years) retrograde femoral access was performed in 48 groins for aortoiliac stent or stent graft implantations using 9-14F sheaths. For vascular closure, one single Angio-Seal™-VIP 8F was used. Procedural success, closure-related complications, and risk factors were retrospectively evaluated using patient characteristics, duplex-ultrasound, and contrast-enhanced computed tomography angiography (CTA). Receiver-operating-characteristics were used for statistical analysis. Results Technical success for deployment of VCD was 100%. Visual inspection and duplex-ultrasound confirmed immediate hemostasis in 100%. Postinterventional CTA depicted major vascular access site complications in 6.3% (3/48 groins) requiring surgical treatment. A subgroup of 13 patients underwent surgical cut-down one day after VCD deployment as part of a two-staged complex endovascular aortic aneurysm repair procedure, allowing for visual assessment of prior used undersized Angio-SealTM. Patient's height (p = 0.028) and severe access site calcifications (p = 0.028) proved as predictors for one vessel occlusion and two pseudoaneurysms. Low body-mass-index (BMI) showed a non-significant trend. Sheath-size, common femoral artery depth, or body weight were not indicative for occurrence of complications. Conclusions In selected cases, without availability of appropriate VCDs, a single Angio-SealTM-VIP 8F served as a feasible option to achieve sufficient hemostasis of transfemoral access exceeding 8F without relevant bleeding complications. Very low BMI, tall body-height, and severe atherosclerosis were identified to predispose to access site complications.

Background: Transjugular intrahepatic shunt (TIPSS) is placed in patients with variceal bleeding, refractory ascites, and for other indications. Postprocedural liver function-associated complications (LFAC), including hepatic encephalopathy (HE) and liver failure, represent a major setback. Current methods to predict complications are insufficient. Objectives: We investigated in a pilot study of patients prior TIPSS placement whether the risk of LFAC correlates with the functional reserve of the liver, as assessed by liver maximum function capacity (LiMAx) test. Methods: Prospectively we included patients prior TIPSS placement between June 2016 and November 2017 at Saarland University Medical Center. LiMAx was conducted before and after TIPSS placement. Patients with HE prior TIPSS, as well as other factors predisposing to HE, including concomitant sedative drugs, current bacterial infections and sepsis, were excluded. Overt HE (OHE), LiMAx, and laboratory values were assessed before and after TIPSS placement. Data were analyzed in multivariate regression and AUROC models. Results: Mean age was 60 ± 8 years. Patients (n = 20) were mainly men (65%), and presented predominantly with Child-Pugh class B (90%). Indications for TIPSS were most commonly refractory ascites or recurrent variceal bleeding. In total, 40% of the patients developed LFAC after TIPSS placement. Expectedly, LiMAx decreased and serum bilirubin increased after TIPSS. LiMAx drop ≥20% was the only parameter predicting the development of LFAC after TIPSS in multivariate regression and AUROC analysis. Conclusions: In multivariate regression models and AUROC analysis, a drop in LiMAx predicted the development of LFAC after TIPSS placement. Additional larger studies assessing OHE and early liver failure separately are warranted.

Objective Evaluation of diagnostic accuracy of an oscillometry-based device (VascAssist) combining fully automated ankle-brachial index (ABI) and pulse-wave velocity (PWV) assessment for detection of peripheral arterial disease (PAD). Subjects and methods 110 consecutive subjects including symptomatic PAD patients (n = 41) and healthy PAD-free participants (n = 69) were recruited. All subjects underwent standard manual Doppler-based ABI (sABI) and oscillometry-based automated ABI (aABI) measurements (VascAssist). Oscillometry by the VascAssist included central and peripheral PWV assessment. Additionally, arterial stiffness (AS) was evaluated by flow-mediated vasodilation (FMD) of the brachial artery in all patients. All symptomatic PAD patients underwent catheter angiography for endovascular intervention and post-interventional acquisition of sABI, aABI, PWV and FMD. Results Sensitivity, specificity, PPV and NPV of aABI for detecting PAD was 73%, 100%, 100%, and 86% as compared to 80%, 96%, 92%, and 89% for sABI. Pearson-correlation for diabetics was r = 0.81; (P

Objective Endovascular anatomic reconstruction of iliac artery bifurcation in aorto-iliac aneurysms using commercial stentgrafts in sandwich-technique by bilateral transfemoral approach. Methods 24 patients (mean 73.8±standard deviation 6.8years) with complex aorto-iliac aneurysms (AAA): n=17; diameter 64±15 [48–100]mm; common-iliac-artery (CIA): n=27; 43±15 [30–87]mm; internal-iliac-artery (IIA): n=14; 28±8 [15–43]mm) were prospectively enrolled for EVAR with preservation of the IIA (n=31; bi-lateral n=7). Maintenance of antegrade flow to IIA by iliac reconstruction was performed in sandwich-technique prior to EVAR. Follow-up of 15.0±10.8 [1–40]months included contrast-enhanced ultrasound and computed-tomography after 1week, 3, 6 and every 12months. Results Initial technical success for anatomic reconstruction of the iliac arteries in 31 instances was 100%. Primary patency of iliac neo-bifurcations was 90.9% (20/22) at 6months and 84.2% (16/19) at 1year. Postprocedural gutter-endoleaks type 1b were obvious in 6.5% (2/31) of cases, which disappeared 3months later. Aortic/iliac aneurysm-size after 1year decreased (>5mm) in 61.5% of patients. No aneurysm-size increase or late rupture occurred. Conclusions Endovascular reconstruction of the iliac bifurcation with commercial standard stentgrafts is safe and effective. Transfemoral approach allows extension of distal landing zone for EVAR while preserving the internal iliac artery blood-flow, even in unfavorable iliac anatomy.

Computed tomography (CT) is the standard procedure for follow-up of non-small-cell lung cancer (NSCLC) after radiochemotherapy. CT has difficulties differentiating between tumor, atelectasis and radiation induced lung toxicity (RILT). Diffusion-weighted imaging (DWI) may enable a more accurate detection of vital tumor tissue. The aim of this study was to determine the diagnostic value of MRI versus CT in the follow-up of NSCLC.Twelve patients with NSCLC stages I-III scheduled for radiochemotherapy were enrolled in this prospective study. CT with i.v. contrast agent and non enhanced MRI were performed before and 3, 6 and 12 months after treatment. Standardized ROIs were used to determine the apparent diffusion weighted coefficient (ADC) within the tumor. Tumor size was assessed by the longest longitudinal diameter (LD) and tumor volume on DWI and CT. RILT was assessed on a 4-point-score in breath-triggered T2-TSE and CT.There was no significant difference regarding LD and tumor volume between MRI and CT (p ≥ 0.6221, respectively p ≥ 0.25). Evaluation of RILT showed a very high correlation between MRI and CT at 3 (r = 0.8750) and 12 months (r = 0.903). Assessment of the ADC values suggested that patients with a good tumor response have higher ADC values than non-responders.DWI is equivalent to CT for tumor volume determination in patients with NSCLC during follow up. The extent of RILT can be reliably determined by MRI. DWI could become a beneficial method to assess tumor response more accurately. ADC values may be useful as a prognostic marker.

AIM To evaluate prospectively the safety of contrast medium injection through standard peripheral intravenous cannulas at standard injection sites during clinical routine using iomeprol 400, a contrast agent with high viscosity. MATERIALS AND METHODS Three thousand, five hundred and fourteen clinical CT examinations undertaken at Saarland University Medical Center were included in this prospective observational trial. The size and site of the cannula as well as the contrast medium injection rate and volume were assessed for each patient. In addition, the ability to aspirate blood though the cannula and the occurrence of complications, such as extravasation or abortion of injection by the automated injector, were recorded. RESULTS The overall complication rate was 30/3,514 (0.85%). With 22 G cannulas, the complication rate was 8/541 (1.48%) applying flow rates of 1–3.5 ml/s (mean 2.1 ml/s). With 20 G cannulas, complications occurred in 21/2,601 cases (0.81%) with flow rates of 1.5–5 ml/s (mean 3 ml/s). The complication rate using 18 G cannulas was 1/377 (0.26%) for flow rates of 2–6 ml/s (mean 3.5 ml/s). No relationship between the site and size of the cannula to the occurrence of complications was found. The inability to aspirate blood correlated with the development of extravasation. CONCLUSIONS The injection of contrast agent using standard peripheral venous cannulas is a safe and reliable procedure yielding diagnostic image contrast, even when using highly viscous contrast agents such as iomeprol 400; an aspiration test should be performed before each injection.

To evaluate technical feasibility and safety of endovascular tumor specimen sampling using an escalating endovascular biopsy strategy using a directional atherectomy device compared with forceps biopsy and catheter aspiration. Between 2013 and 2017, a cohort of ten consecutive patients (6 male; median age 56, range 39–73 years) was referred for sampling of endovascular masses. Localizations included the abdominal aorta (n = 4), left brachiocephalic vein (n = 2), inferior vena cava (n = 1), and left pulmonary artery (n = 3). For each individual mass, all three endovascular tissue sampling approaches were applied including catheter-based aspiration, straight two-jaw biopsy forceps, and directional atherectomy during a single session. Aspiration and forceps biopsy did not provide sufficient material for histological analyses. In contrast, technical success for endovascular tumor sampling using directional atherectomy was 100%. After two atherectomy passages, sufficient material was available for each vessel region allowing histologic diagnosis, which revealed sarcoma and chronic inflammation for masses in the aorta, angiosarcoma for brachiocephalic vein, hepatocellular carcinoma for inferior vena cava, and angiosarcoma for pulmonary artery. In case of a histologically benign diagnosis, no malignant tumor proliferation was obvious on follow-up imaging studies after 3 months and 1 year. Thus, the rate of false-negative results was considered 0%. No procedure-associated complications, e.g., vessel perforation, were recorded. Preliminary results in a limited number of patients proved directional atherectomy beneficial as a safe and feasible technique for endoluminal tissue sampling of vascular masses. Additional large-scale studies are necessary and worthy for further evaluation in clinical practice. • Endovascular masses pose a challenge to appropriate clinical management. • Off-label directional atherectomy proved to be a safe and feasible technique for endoluminal tissue sampling of vascular masses. Furthermore, directional atherectomy was superior to aspiration or forceps biopsy in our small study cohort. • Directional atherectomy may represent the last or only option for tissue probing as a prerequisite for further treatment decisions.

Background Chronic thromboembolic pulmonary hypertension (CTEPH) can potentially be cured by pulmonary thrombendarterectomy (PEA), the criteria for differentiation between operable and non-operable patients are not standardized. Purpose To retrospectively evaluate the value of rigidly registered computed tomography pulmonary angiography (CTPA) and single photon emission CT (SPECT) in differentiating for PEA. Material and Methods Forty-nine patients with CTEPH (21 men; age, 58 ± 13 years) were evaluated by an interdisciplinary expert board using all available diagnostic information and their consensus statement as gold standard. For SPECT a lobe based perfusion score was visually assessed using the score of 0 (lack of perfusion) to 1 (normal perfusion) calculating percentage of vascular obstruction (PVO). By CTPA, vascular obstruction index (OI) of central, peripheral, and global PA-bed were determined. The accuracy of the alignment between CTPA and SPECT was determined by fusion score (FS) ranging from 1 (no alignment) to 5 (exact alignment). Angiography provided PA pressure (PAP), pulmonary vascular resistance (PVR), and PA wedge pressure (PAWP). Receiver operating characteristics (ROC) analysis was performed. Results Twenty-nine patients were considered surgically amenable, and 20 patients were inoperable. Mean PAP, PVR, and PAWP were 48 ± 11 mmHg, 868 ± 461 dynes*sec*cm−5, and 11 ± 5 mmHg, without differences between surgical and non-surgical patients ( P > 0.5). In all patients accurate registration was reached (FS = 4.1 ± 0.7; range, 2–5). PVO and central OI separated PEA-amenable patients ( P ≤ 0.001) resulting in the area under the curve of 0.828 (cutoff for PVO: 37.8% with a sensitivity of 82% and specificity of 79%) and 0.755 (cutoff for central OI: 29% with a sensitivity and specificity of 86.2% and 79%) for operability. Conclusion An accurate interpretation of rigidly registered CTPA and perfusion SPECT may contribute to stratification of operability in patients with CTEPH.

Purpose To compare abdominal imaging dose from 3D imaging in radiology (standard/low-dose/dual-energy CT) and radiotherapy (planning CT, kV cone-beam CT (CBCT)). Methods Dose was measured by thermoluminescent dosimeters (TLD’s) placed at 86 positions in an anthropomorphic phantom. Point, organ and effective dose were assessed, and secondary cancer risk from imaging was estimated. Results Overall dose and mean organ dose comparisons yield significantly lower dose for the optimized radiology protocols (dual-source and care kV), with an average dose of 0.34±0.01 mGy and 0.54±0.01 mGy (average ± standard deviation), respectively. Standard abdominal CT and planning CT involve considerably higher dose (13.58 ± 0.18 mGy and 18.78±0.27 mGy, respectively). The CBCT dose show a dose fall-off near the field edges. On average, dose is reduced as compared with the planning or standard CT (3.79 ± 0.21 mGy for 220° rotation and 7.76 ± 0.37 mGy for 360°), unless the high-quality setting is chosen (20.30 ± 0.96 mGy). The mean organ doses show a similar behavior, which translates to the estimated secondary cancer risk. The modelled risk is in the range between 0.4 cases per million patient years (PY) for the radiological scans dual-energy and care kV, and 300 cases per million PY for the high-quality CBCT setting. Conclusions Modern radiotherapy imaging techniques (while much lower in dose than radiotherapy), involve considerably more dose to the patient than modern radiology techniques. Given the frequency of radiotherapy imaging, a further reduction in radiotherapy imaging dose appears to be both desirable and technically feasible.

Purpose To evaluate glass-fiber-based guidewires that are safe for magnetic resonance (MR) imaging-guided endovascular interventions by using a phantom and an in vivo swine model. Materials and Methods MR imaging-safe guidewires were made from micropultruded glass and/or aramid fibers and epoxy resin with diameters of 0.89 mm (0.035 inch) for standard and stiff guidewires and 0.36 mm (0.014 inch) for micro guidewires. MR imaging visibility and mechanical properties were assessed in a pulsatile flow model. After approval was obtained from the institutional animal care and use committee, MR imaging guidewires were evaluated for standard endovascular procedures in nine pigs. Real-time steady-state free-precession sequences were used for MR imaging-guided catheterization, balloon dilation, and stent implantation into aorto-iliac/visceral arteries and the vena cava (temporal resolution, five images per second; and spatial resolution, 150-mm field of view, and 128 × 128 matrix) with a 1.5-T clinical imager. Visualization with the guidewires was rated on a four-point scale, handling was rated on a three-point scale, and catheterization times for different vessel regions were determined by two interventional radiologists. Afterward, handling ratings and catheterization times were obtained for standard nitinol guidewires during x-ray-based fluoroscopy. Cannulation times, signal intensity in each vessel region, and visualization and handling ratings were measured for the MR imaging guidewires. Bland-Altman analysis was performed for inter- and intraobserver variability of cannulation time. Spearman rank correlation was used to compare handling of MR imaging guidewires and standard nitinol guidewires. Results MR imaging guidewires were characterized by good to excellent visibility, with a continuous artifact of 2 mm in diameter and 4 × 8-mm ball-shaped tip marker. Stiffness, flexibility, and guidance reflected comparable times for all in vitro and in vivo procedures with both the MR imaging and standard nitinol guidewires. Standard and micro MR imaging guidewires were most suitable for the iliac crossover maneuver. Phantom visceral artery cannulation was easier with standard and micro MR imaging guidewires. The stiff MR imaging guidewire provided the best support for cannulation of the swine aorta and vena cava. All interventional procedures were performed successfully without complications. Conclusion Preliminary results showed that the use of glass-fiber-based guidewires for evaluation of MR imaging-guided endovascular interventions is technically feasible and safe in a swine model, and potentially, in humans. © RSNA, 2017 Online supplemental material is available for this article.

Objective To retrospectively evaluate the technical feasibility and midterm results of uncovered thoracoabdominal stent placement in complicated acute aortic dissection Stanford type B (cAADB). Patients and Methods Fourteen consecutive patients (3 females; range, 44-71 years) with cAADB who had symptomatic gastrointestinal malperfusion and claudication underwent immediate uncovered stent implantation (diameter, 7-28 mm; length, 40-100 mm) into the true lumen of the thoracoabdominal aorta (n = 23) and visceral arteries (n = 5). Results Stenting resulted in elimination of gastrointestinal ischemia and symptoms in 13 of 14 patients; persisting symptoms led to secondary surgical revascularization in only 1 patient. More than 1 stent (≤4) was placed in 7 patients (2 celiac, 1 mesenteric, 2 renal, 8 aorto-iliac). Follow-up computed tomographic angiography (CTA) revealed collapse of 4 aortic stents (diameter, 9-25 mm; length, 100 mm) at 1 week in the absence of symptoms. Balloon reexpansion was possible in all 4 stents, but recollapse occurred within 1 month. Despite stent collapse, the patients remained asymptomatic; ultrasonography and CTA documented sufficient perfusion of the visceral arteries in all patients. Follow-up ranged from 6 months to 5 years (average, 2.5 years). Except for the patient who underwent iliacomesenteric bypass for unspecific abdominal pain, no other patient required additional interventional or surgical therapy. Conclusions Acute aortic dissection with suspicion of visceral ischemia should prompt for immediate intervention. Thoracoabdominal uncovered stent implantation is a technically feasible and effective minimally invasive approach that provided successful relief of acute visceral ischemia and claudication in cAADB. Stent size should be less than the normal aortic diameter to avoid possible stent collapse.

Magnetic resonance imaging (MRI) performed at ultra-high field strengths beyond 3 Tesla (T) has become increasingly prevalent in research and preclinical applications. As such, the inevitable clinical implementation of such systems lies on the horizon. The major benefit of ultra-high field MRI is the markedly increased signal-to-noise ratios achievable, enabling acquisition of MR images with simultaneously greater spatial and temporal resolution. However, at field strengths higher than 3 T, the efficacy of Gd(III)-based contrast agents is diminished due to decreased r1 relaxivity, somewhat limiting imaging of the vasculature and contrast-enhanced imaging of tumors. There have been extensive efforts to design new contrast agents with high r1 relaxivities based on macromolecular compounds or nanoparticles; however, the efficacy of these agents at ultra-high field strengths has not yet been proven. The aim of this review article is to provide an overview of the basic principles of MR contrast enhancement processes and to highlight the main factors influencing relaxivity. In addition, challenges and opportunities for contrast-enhanced MRI at ultra-high field strengths will be explored. Various approaches for the development of effective contrast agent molecules that are suitable for a broad spectrum of applied field strengths will be discussed in the context of the current literature.

Purpose A minimal-invasive interventional technique for recanalization of complex chronic central venous total occlusions is described to overcome difficulties in case of failure of common approaches. Method We present a patient with a central venous occlusion that caused severe venous congestion of her upper extremity and significant impairment of her forearm hemodialysis shunt. Since the usual transbrachial and transfemoral attempts for recanalization of occluded right subclavian, brachiocephalic, superior vena cava, and proximal internal jugular veins (IJV) failed, the approach was changed to a transjugular access. Only the IJV and subclavian vein occlusions were passed from transjugular. Results The key procedure was the switch of a jugular-brachial wire to a femoral-brachial setting. The wire transposition was achieved by snaring the looped stiff end of the jugular-brachial wire outside the jugular sheath from the opposite femoral access. Conclusion Different approaches should be considered for the recanalization of challenging central venous occlusions. After failed attempts via common access sites, a guidewire transposition maneuver using a combined approach may be particularly helpful for safe and effective endovascular treatment of complex situations.

To investigate the 3-year outcome of patients with peripheral arterial disease (PAD) and heavily calcified stenotic lesions of the superficial femoral artery after directional atherectomy. Fifty-three patients (mean age 67 ± 10 years; 18 females, 35 males, TASC B and C, mean lesion length 7.9 ± 3.5 cm) with PAD (Rutherford 2–6) were enrolled into this prospective monocentric study. In total, 59 calcified lesions of the superficial femoral artery were treated with the Silverhawk atherectomy device (Covidien, Plymouth, MN, USA). Patients were followed-up for 36 months with a 6-month interval to perform clinical re-evaluation, including measurement of maximum walking distance and ankle–brachial index (ABI) as well as duplex-sonography. The primary success rate of the procedure was 92 %. In five cases (8 %), additional balloon-PTA and/or stent-PTA was necessary. Procedure-related embolization occurred in seven cases (12 %), which were all successfully treated by aspiration. The primary patency rate after 3 years was 55 %. Median Rutherford score decreased significantly from 5 to 0 after 36 months (p

The β-blocker propranolol has become a valuable and effective drug for the treatment of infantile hemangiomas. Its therapeutic action probably results from vasoconstriction, blocking of angiogenesis through effects on vascular endothelial growth factor and induction of apoptosis. It is reasonable to suggest that propranolol can also be used effectively in the treatment of other vascular abnormalities. This case report describes propranolol treatment of vascular malformations such as Klippel-Trénaunay syndrome or Parkes-Weber syndrome in adults.

Purpose To report the first experience using the chimney technique in combination with the latest-generation low-profile stent-graft to seal abdominal aortic aneurysms having a very short neck (proximal sealing zone) and difficult access due to very small iliac vessels.

Recently, clinical studies demonstrated that magnetic resonance relaxometry with determination of relaxation times T1 andT2⁎may aid in staging and management of liver fibrosis in patients suffering from viral hepatitis and steatohepatitis. In the present study we investigated T1 andT2⁎in different models of liver fibrosis to compare alternate pathophysiologies in their effects on relaxation times and to further develop noninvasive quantification methods of liver fibrosis. MRI was performed with a fast spin echo sequence for measurement of T1 and a multigradient echo sequence for determination ofT2⁎. Toxic liver fibrosis was induced by injections of carbon tetrachloride (1.4 mL CCl4per kg bodyweight and week, for 3 or 6 weeks) in BALB/cJ mice. Chronic sclerosing cholangitis was mimicked using the ATP-binding cassette transporter B4 knockout(Abcb4 -/-)mouse model. Untreated BALB/cJ mice served as controls. To assess hepatic fibrosis, we ascertained collagen contents and fibrosis scores after Sirius red staining. T1 andT2⁎correlate differently to disease severity and etiology of liver fibrosis.T2⁎shows significant decrease correlating with fibrosis in CCl4treated animals, while demonstrating significant increase with disease severity inAbcb4 -/-mice. Measurements of T1 andT2⁎may therefore facilitate discrimination between different stages and causes of liver fibrosis.

This study presents a framework for workflow optimisation of multimodal image-guided procedures (MIGP) based on discrete event simulation (DES). A case of a combined X-Ray and magnetic resonance image-guided transarterial chemoembolisation (TACE) is presented to illustrate the application of this method. We used a ranking and selection optimisation algorithm to measure the performance of a number of proposed alternatives to improve a current scenario. A DES model was implemented with detail data collected from 59 TACE procedures and durations of magnetic resonance imaging (MRI) diagnostic procedures usually performed in a common MRI suite. Fourteen alternatives were proposed and assessed to minimise the waiting times and improve workflow. Data analysis observed an average of 20.68 (7.68) min of waiting between angiography and MRI for TACE patients in 71.19% of the cases. Following the optimisation analysis, an alternative was identified to reduce waiting times in angiography suite up to 48.74%. The model helped to understand and detect 'bottlenecks' during multimodal TACE procedures, identifying a better alternative to the current workflow and reducing waiting times. Simulation-based workflow analysis provides a cost-effective way to face some of the challenges of introducing MIGP in clinical radiology, highligthed in this study.

OBJECTIVE: A critical problem in cardiovascular MRI in small rodents is adjusting the sequence acquisition to the high heart and respiratory rates. The aim of this study was to compare a retrospectively self-gated fast low angle shot navigator (RSG-FLASH) sequence with a conventional prospectively triggered (PT-FLASH) sequence for cine imaging of the ascending aorta in mice at 9.4 T. MATERIAL AND METHODS: Ten C57/BL6 mice were examined with a horizontal bore 9.4 Tesla MRI animal scanner using a dedicated 2 × 2 phased-array surface coil. We acquired a RSG-FLASH sequence (RSG-FLASH sequences (repetition time (TR) / echo time (TE) = 6.5/2.5 ms, flip angle (FA) = 10 degrees, field of view (FOV) = 2 × 2 cm, matrix = 384 × 384, slice thickness = 1 mm, 25 movie frames) perpendicular to the ascending aorta using the IntraGate technique. At the same position, we performed a PT-FLASH sequence (TR/TE = 6.5/2.1 ms, FA = 10 degrees, FOV = 2 × 2 cm, matrix = 384 × 384, slice thickness = 1 mm) in which the maximum number of movie frames had to be adjusted to the interval between two R-peaks (RR interval) of the electrocardiogram (ECG) with: number of frames = RR interval / TR." Cross-sectional vessel areas at end-systole (AES) and end-diastole (AED) were measured to determine the aortic strain (ΔA = (AES-AED)/AED). Two blinded readers rated the sequences for presence of flow and trigger artifacts and their influence on the depiction of the blood/vessel-wall interface. Irregularities in displaying the cardiac cycle and the overall suitability of the sequence for aortic strain evaluation were assessed using a 5-level ordinal scale. Statistical differences were analyzed using Student t test and Wilcoxon signed rank test (P < 0.05). Intra- and interobserver variability was evaluated using Bland-Altman analyses. RESULTS: No significant differences were noted between techniques regarding the measured vessel areas (AED: P = 0.07, AES: P = 0.34), ΔA: P = 0.1). Similarly, there were no significant differences in heart (P = 0.06) and respiratory (P = 0.24) rates. The acquisition time for RSG-FLASH sequence was significantly shorter (P = 0.04). Significantly fewer flow and trigger artifacts were noted by both readers with the RSG-FLASH sequence. Likewise, both readers considered the RSG-FLASH sequence to be superior for depiction of the blood/vessel-wall interface. The RSG-FLASH sequence was also rated superior regarding irregularities in displaying the cardiac cycle and in terms of overall suitability for evaluation of AED, AES, and aortic strain (P < 0.05 each). CONCLUSION: RSG-FLASH is preferable for cine imaging of the aorta. It provides the same quantitative data as PT-FLASH cine imaging but is less prone to flow and trigger artifacts. RSG-FLASH permits more homogeneous depiction of the cardiac cycle and is faster than the PT-FLASH sequence. PT-FLASH is more prone to misregistration of the respiratory cycle or the ECG by the external monitoring device used for acquisition. This effect may be even more pronounced in animals with disease models that are less stable in terms of heart and respiration rate during anesthesia.

To retrospectively examine the technical feasibility and safety of directional atherectomy for treatment of subacute infrainguinal arterial vessel occlusions. Five patients (one woman, four men, age range 51–81 years) with peripheral arterial disease who experienced sudden worsening of their peripheral arterial disease–related symptoms during the last 2–6 weeks underwent digital subtraction angiography, which revealed vessel occlusion in native popliteal artery (n = 4) and in-stent occlusion of the superficial femoral artery (n = 1). Subsequently, all patients were treated by atherectomy with the SilverHawk (ev3 Endovascular, USA) device. The mean diameter of treated vessels was 5.1 ± 1.0 mm. The length of the occlusion ranged 2–14 cm. The primary technical success rate was 100%. One patient experienced a reocclusion during hospitalization due to heparin-induced thrombocytopenia. There were no further periprocedural complications, in particular no peripheral embolizations, until hospital discharge or during the follow-up period of 1 year. The recanalization of infrainguinal arterial vessel occlusions by atherectomy with the SilverHawk device is technically feasible and safe. In our limited retrospective study, it was associated with a high technical success rate and a low procedure-related complication rate.

To compare 3 different flow targeted magnetization preparation strategies for coronary MR angiography (cMRA), which allow selective visualization of the vessel lumen.The right coronary artery of 10 healthy subjects was investigated on a 1.5 Tesla MR system (Gyroscan ACS-NT, Philips Healthcare, Best, NL). A navigator-gated and ECG-triggered 3D radial steady-state free-precession (SSFP) cMRA sequence with 3 different magnetization preparation schemes was performed referred to as projection SSFP (selective labeling of the aorta, subtraction of 2 data sets), LoReIn SSFP (double-inversion preparation, selective labeling of the aorta, 1 data set), and inflow SSFP (inversion preparation, selective labeling of the coronary artery, 1 data set). Signal-to-noise ratio (SNR) of the coronary artery and aorta, contrast-to-noise ratio (CNR) between the coronary artery and epicardial fat, vessel length and vessel sharpness were analyzed.All cMRA sequences were successfully obtained in all subjects. Both projection SSFP and LoReIn SSFP allowed for selective visualization of the coronary arteries with excellent background suppression. Scan time was doubled in projection SSFP because of the need for subtraction of 2 data sets. In inflow SSFP, background suppression was limited to the tissue included in the inversion volume. Projection SSFP (SNR(coro): 25.6 +/- 12.1; SNR(ao): 26.1 +/- 16.8; CNR(coro-fat): 22.0 +/- 11.7) and inflow SSFP (SNR(coro): 27.9 +/- 5.4; SNR(ao): 37.4 +/- 9.2; CNR(coro-fat): 24.9 +/- 4.8) yielded significantly increased SNR and CNR compared with LoReIn SSFP (SNR(coro): 12.3 +/- 5.4; SNR(ao): 11.8 +/- 5.8; CNR(coro-fat): 9.8 +/- 5.5; P0.05 for both). Longest visible vessel length was found with projection SSFP (79.5 mm +/- 18.9; P0.05 vs. LoReIn) whereas vessel sharpness was best in inflow SSFP (68.2% +/- 4.5%; P0.05 vs. LoReIn). Consistently good image quality was achieved using inflow SSFP likely because of the simple planning procedure and short scanning time.Three flow targeted cMRA approaches are presented, which provide selective visualization of the coronary vessel lumen and in addition blood flow information without the need of contrast agent administration. Inflow SSFP yielded highest SNR, CNR and vessel sharpness and may prove useful as a fast and efficient approach for assessing proximal and mid vessel coronary blood flow, whereas requiring less planning skills than projection SSFP or LoReIn SSFP.

A novel fiber-reinforced material for the realization of MR guidewires, made using a newly-developed production process, is presented. The MR-safe artificial material provides a high stiffness and torque and allows the production, in a large range of sizes, of nonmetallic MR guidewires with similar mechanical properties as conventional metallic guidewires. Based on this material, a passively visualized MR guidewire has been developed, and was found to conform to existing standards on mechanical stability. Handling and steerability were evaluated in animal studies and were found to be comparable with conventional metallic guidewires. X-ray visibility is provided by a BaSO(4)- and tungsten-doped jacket. A hydrophilic coating improves sliding properties and hemocompatibility.

Magnetic resonance imaging (MRI) has developed dramatically in the 25 years since its clinical introduction. Advances in hardware design have included the development of high field magnets and more sophisticated and sensitive coils. Improvements in sequences, data sampling, and postprocessing software have benefited the attainable spatial and temporal resolution to the point at which the fine depiction of anatomical structure and pathological processes is now routine. As in other radiological areas, the most recent advances in MRI have proven highly valuable in the field of musculoskeletal radiology where the lack of radiation, high soft tissue contrast, and capacity for multiplanar or three-dimensional imaging have made MRI the imaging modality of choice. Particular benefits are seen in diagnostic imaging of the spine where MRI is clearly superior to both conventional radiography and computed tomography. In this article, we discuss the impact of the most recent technological advance in MRI, namely the advent of 3 Tesla (3-T) imaging, on diagnostic imaging of the spine. Comparisons are drawn with imaging at 1.5 T, and emphasis is placed on MR physics and on the benefits and principal difficulties associated with spine imaging at high field strength.