Quantitative differentiation of minimal-fat angiomyolipomas from renal cell carcinomas using grating-based x-ray phase-contrast computed tomography: An ex vivo study.

BACKGROUND: The differentiation of minimal-fat-or low-fat-angiomyolipomas from other renal lesions is clinically challenging in conventional computed tomography. In this work, we have assessed the potential of grating-based x-ray phase-contrast computed tomography (GBPC-CT) for visualization and quantitative differentiation of minimal-fat angiomyolipomas (mfAMLs) and oncocytomas from renal cell carcinomas (RCCs) on ex vivo renal samples. MATERIALS AND METHODS: Laboratory GBPC-CT was performed at 40 kVp on 28 ex vivo kidney specimens including five angiomyolipomas with three minimal-fat (mfAMLs) and two high-fat (hfAMLs) subtypes as well as three oncocytomas and 20 RCCs with eight clear cell (ccRCCs), seven papillary (pRCCs) and five chromophobe RCC (chrRCC) subtypes. Quantitative values of conventional Hounsfield units (HU) and phase-contrast Hounsfield units (HUp) were determined and histogram analysis was performed on GBPC-CT and grating-based attenuation-contrast computed tomography (GBAC-CT) slices for each specimen. For comparison, the same specimens were imaged at a 3T magnetic resonance imaging (MRI) scanner. RESULTS: We have successfully matched GBPC-CT images with clinical MRI and histology, as GBPC-CT presented with increased soft tissue contrast compared to absorption-based images. GBPC-CT images revealed a qualitative and quantitative difference between mfAML samples (58±4 HUp) and oncocytomas (44±10 HUp, p = 0.057) and RCCs (ccRCCs: 40±12 HUp, p = 0.012; pRCCs: 43±9 HUp, p = 0.017; chrRCCs: 40±7 HUp, p = 0.057) in contrast to corresponding laboratory attenuation-contrast CT and clinical MRI, although not all differences were statistically significant. Due to the heterogeneity and lower signal of oncocytomas, quantitative differentiation of the samples based on HUp or in combination with HUs was not possible. CONCLUSIONS: GBPC-CT allows quantitative differentiation of minimal-fat angiomyolipomas from pRCCs and ccRCCs in contrast to absorption-based imaging and clinical MRI.

T2 mapping for the characterization of prostate lesions.

PURPOSE: Purpose of this study is to evaluate the diagnostic accuracy of quantitative T2/ADC values in differentiating between PCa and lesions showing non-specific inflammatory infiltrates and atrophy, features of chronic prostatitis, as the most common histologically proven differential diagnosis. METHODS: In this retrospective, single-center cohort study, we analyzed 55 patients suspected of PCa, who underwent mpMRI (3T) including quantitative T2 maps before robot-assisted mpMRI-TRUS fusion prostate biopsy. All prostate lesions were scored according to PI-RADS v2.1. Regions of interest (ROIs) were annotated in focal lesions and normal prostate tissue. Quantitative mpMRI values from T2 mapping and ADC were compared using two-tailed t tests. Receiver operating characteristic curves (ROCs) and cutoff were calculated to differentiate between PCa and chronic prostatitis. RESULTS: Focal lesions showed significantly lower ADC and T2 mapping values than normal prostate tissue (p < 0.001). PCa showed significantly lower ADC and T2 values than chronic prostatitis (p < 0.001). ROC analysis revealed areas under the receiver operating characteristic curves (AUCs) of 0.85 (95% CI 0.74-0.97) for quantitative ADC values and 0.84 (95% CI 0.73-0.96) for T2 mapping. A significant correlation between ADC and T2 values was observed (r = 0.70; p < 0.001). CONCLUSION: T2 mapping showed high diagnostic accuracy for differentiating between PCa and chronic prostatitis, comparable to the performance of ADC values.

Association between cardiovascular risk factors and degenerative disc disease of the thoracolumbar spine in the general population: results from the KORA MRI Study.

BACKGROUND: Little is known about the associations between cardiovascular risk factors (CRF) and disc degeneration (DD). PURPOSE: To evaluate the potential association between CRFs and intervertebral DD in a population-based sample. METHODS: A total of 400 participants from the community-based KORA-study were assessed in terms of CRFs, specifically obesity, hypertension, diabetes, elevated LDL-c, low HDL-c, elevated triglycerides, smoking status, and alcohol consumption. The patients additionally underwent whole-body magnetic resonance imaging (MRI) using T2-weighted single-shot fast-spin-echo and T1 dual-echo gradient-echo Dixon pulse sequences. Thoracic and lumbar DD were assessed using the Pfirrmann score and for the presence of disc bulging/protrusion. Cross-sectional associations between CRFs and MR-based Pfirrmann score were then analyzed. RESULTS: A total of 385 individuals (58.2% men; mean age 56.3 ± 9.2 years) were included. Prevalence of DD was 76.4%. Older age (ß = 0.18; 95% CI 0.12-0.25; P < 0.001) and higher body mass index (BMI) (ß = 0.19; 95% CI 0.06-0.30; P = 0.003) were significantly associated with DD of the thoracolumbar spine. Diabetes was significantly associated with DD at T7/8 (P = 0.029) and L3/4 (P = 0.017). Hypertension correlated significantly with DD in univariate analysis, but the association did not persist using multivariate analysis (ß = 0.53; 95% CI -0.74 to 1.81; P = 0.41). None of the other CRFs (P ≥ 0.11) were associated with advanced DD. Disc bulging was independently associated with hypertension (ß = 0.47; 95% CI 0.27-0.81; P = 0.01). CONCLUSION: A significant independent association exists between age, BMI, and intervertebral DD. In contrast, there is no significant association between cardiovascular risk factors and DD. Providing strong evidence that the pathologic process undergirding DD is mechanical, rather than microvascular, in nature.

Radiological Monitoring of Modern Immunotherapy: A Novel Challenge for Interdisciplinary Patient Care. / Radiologisches Monitoring von modernen Immuntherapien: Neue Herausforderung für die interdisziplinäre Zusammenarbeit.

BACKGROUND: Immunotherapy represents an effective therapeutic approach for many malignant diseases that were previously difficult to treat. However, since immunotherapy can lead to atypical therapy response patterns in the form of pseudo-progression or mixed responses and comprise an altered spectrum of adverse reactions, they present a new challenge for oncologic imaging. Detailed knowledge in this area is essential for oncologic clinical radiologists, since the radiological report is a cornerstone of response assessment, and increasingly influences therapy regimens and coverage by health insurances. METHOD: This white paper is based on an expert meeting in Frankfurt am Main and subsequent discussions between the authors. Based on the iRECIST criteria, it is intended to provide orientation for a response assessment of oncologic patients undergoing immunotherapy that can be applied in the clinical routine. RESULTS: Radiological therapy monitoring outside clinical studies is subject to inherent limitations, but should be performed based on iRECIST criteria, according to the opinion of the expert panel. It should be taken into account that immunotherapies can in principle lead to pseudo-progression and autoimmunological side effects. Since radiological follow-up is currently the only method to accurately distinguish real progressive disease from pseudo-progression, clinically stable patients with disease progression under immunotherapy should undergo additional short-term follow-up imaging according to the suspected diagnosis. Biopsy should be used cautiously and predominately in curative settings. CONCLUSION: For response assessment of immunotherapy in clinical studies, the new iRECIST criteria were published in 2017. Outside studies, the application of iRECIST criteria in the clinical routine is subject to several limitations. The recommendations implied in these criteria can, however, be used in conjunction with the current literature as a guideline in clinical practice and outside studies. KEY POINTS: · Novel immunotherapies can cause atypical response patterns like pseudo-progression. · Compared to real progressive disease, pseudo-progression occurs rather rarely, yet can influence therapy. · Short-term follow-up according to iRECIST can help to distinguish pseudo-progression from real progression. · Hence, radiological follow-up outside clinical studies should be oriented towards iRECIST criteria. CITATION FORMAT: · Lennartz S, Diederich S, Doehn C et al. Radiological Monitoring of Modern Immunotherapy: A Novel Challenge for Interdisciplinary Patient Care. Fortschr Röntgenstr 2020; 192: 235 - 244.

Platelet GPIbα is a mediator and potential interventional target for NASH and subsequent liver cancer.

Non-alcoholic fatty liver disease ranges from steatosis to non-alcoholic steatohepatitis (NASH), potentially progressing to cirrhosis and hepatocellular carcinoma (HCC). Here, we show that platelet number, platelet activation and platelet aggregation are increased in NASH but not in steatosis or insulin resistance. Antiplatelet therapy (APT; aspirin/clopidogrel, ticagrelor) but not nonsteroidal anti-inflammatory drug (NSAID) treatment with sulindac prevented NASH and subsequent HCC development. Intravital microscopy showed that liver colonization by platelets depended primarily on Kupffer cells at early and late stages of NASH, involving hyaluronan-CD44 binding. APT reduced intrahepatic platelet accumulation and the frequency of platelet-immune cell interaction, thereby limiting hepatic immune cell trafficking. Consequently, intrahepatic cytokine and chemokine release, macrovesicular steatosis and liver damage were attenuated. Platelet cargo, platelet adhesion and platelet activation but not platelet aggregation were identified as pivotal for NASH and subsequent hepatocarcinogenesis. In particular, platelet-derived GPIbα proved critical for development of NASH and subsequent HCC, independent of its reported cognate ligands vWF, P-selectin or Mac-1, offering a potential target against NASH.

Reduced scan range abdominopelvic CT in patients with suspected acute appendicitis - impact on diagnostic accuracy and effective radiation dose.

BACKGROUND: To evaluate a reduced range CT protocol in patients with suspected acute appendicitis as compared to standard abdominal CT regarding diagnostic performance, effective radiation dose and organ doses. METHODS: In this study, we retrospectively included 90 patients (43 female, mean age 56.7 ± 17 years) with suspected acute appendicitis who underwent CT of abdomen and pelvis. From those CTs, we reconstructed images with a reduced scan range from L1 to the the pubic symphysis. Full range and reduced range datasets were assessed by two radiologists for i) coverage of the Appendix, ii) presence/absence of appendicitis and iii) presence of differential diagnoses. Furthermore, effective radiation doses as well as organ doses were calculated using a commercially available dose management platform (Radimetrics, Bayer HealthCare). RESULTS: The Appendix was covered by the reduced range CT in all cases. In 66 patients CT confirmed the presence of appendicitis. In 14 patients, other relevant differential diagnoses were identified by CT, whereas in 10 patients no relevant findings were detected. Both readers identified all patients with appendicitis on both full and reduced range CT. For reduced range CT, total effective dose was 39% lower than for full range CT (reduced range: 4.5 [1.9-11.2] vs. full range: 7.4 [3.3-18.8] mSv; p ≤ 0.001). Notably, a remarkable reduction of organ dose in the female breasts by 97% (0.1 [0.1-0.6] vs. 3.8 [0.5-18.8] mSv; p ≤ 0.001) and in the testicles in males by 81% (3.4 [0.7-32.7] vs. 17.6 [5.4-52.9] mSv; p ≤ 0.001) was observed for reduced range CT compared to full range CT. CONCLUSIONS: In patients with suspected acute appendicitis, reduced range abdominopelvic CT results in a comparable diagnostic performance with a remarkable reduction of total effective radiation dose and organ doses (especially breast dose in female and testicle dose in male patients) as compared to full range CT.

Diffusion-weighted magnetic resonance imaging to assess diffuse renal pathology: a systematic review and statement paper.

Diffusion-weighted magnetic resonance imaging (DWI) is a non-invasive method sensitive to local water motion in the tissue. As a tool to probe the microstructure, including the presence and potentially the degree of renal fibrosis, DWI has the potential to become an effective imaging biomarker. The aim of this review is to discuss the current status of renal DWI in diffuse renal diseases. DWI biomarkers can be classified in the following three main categories: (i) the apparent diffusion coefficient-an overall measure of water diffusion and microcirculation in the tissue; (ii) true diffusion, pseudodiffusion and flowing fraction-providing separate information on diffusion and perfusion or tubular flow; and (iii) fractional anisotropy-measuring the microstructural orientation. An overview of human studies applying renal DWI in diffuse pathologies is given, demonstrating not only the feasibility and intra-study reproducibility of DWI but also highlighting the need for standardization of methods, additional validation and qualification. The current and future role of renal DWI in clinical practice is reviewed, emphasizing its potential as a surrogate and monitoring biomarker for interstitial fibrosis in chronic kidney disease, as well as a surrogate biomarker for the inflammation in acute kidney diseases that may impact patient selection for renal biopsy in acute graft rejection. As part of the international COST (European Cooperation in Science and Technology) action PARENCHIMA (Magnetic Resonance Imaging Biomarkers for Chronic Kidney Disease), aimed at eliminating the barriers to the clinical use of functional renal magnetic resonance imaging, this article provides practical recommendations for future design of clinical studies and the use of renal DWI in clinical practice.

Fast Abdominal Contrast-Enhanced Imaging With High Parallel-Imaging Factors Using a 60-Channel Receiver Coil Setup: Comparison With The Standard Coil Setup.

PURPOSE: The aim of this study was to assess a novel 60-channel receiver body coil (B60) setup for accelerated contrast-enhanced abdominal magnetic resonance imaging (MR) imaging with respect to signal-to-noise ratio (SNR) and image quality using high parallel-imaging technique (PAT) factors in comparison to a standard 30-channel coil setup. METHODS: All imaging data were acquired on a 3 T MR scanner using a novel B60 receiver coil setup in comparison to a standard 30-channel setup serving as reference standard. Phantom measurements were performed to systematically evaluate SNR and geometry factor performance in an ex vivo setting. To assess the in vivo application, additional measurements in 5 healthy volunteers and 17 patients were performed using a 3-dimensional T1w gradient-echo sequences with different acceleration factors. At first, the volunteers were examined. In a second step, standard contrast-enhanced abdominal images were acquired in the 17 patients, who were randomly assigned into 2 groups (group A: 60-channel, n = 8; group B: 30-channel, n = 9). Image quality, noise, lesion conspicuity, and artifacts were assessed by 2 radiologists independently on a 5-point Likert scale (5 = excellent). RESULTS: The phantom study revealed substantial advantages (SNR and geometry factor) of the B60 coil for measurements in the head-to-feet phase encoding direction, whereas only minor differences were found in other directions. Comparison of image quality in volunteers revealed significantly higher ratings of the B60 setup for all acquisitions (P ≤ 0.032), except for PAT = none. In patients, similar results were observed with comparable image quality at lower PAT factors and significantly superior image quality of the B60 setup for higher PAT factors (2 × 2 and 3 × 2; P = 0.008). CONCLUSIONS: The 60-channel coil setup facilitates improved SNR and image quality at high PAT factors with diagnostic image quality, which allows for accelerated contrast-enhanced MR imaging of the abdomen.

Cognitive versus Software-Assisted Registration: Development of a New Nomogram Predicting Prostate Cancer at MRI-Targeted Biopsies.

INTRODUCTION: Multiparametric magnetic resonance imaging (mpMRI) is gaining acceptance to guide targeted biopsy (TB) in prostate cancer (PC) diagnosis. We aimed to compare the detection rate of software-assisted fusion TB (SA-TB) versus cognitive fusion TB (COG-TB) for PC and to evaluate potential clinical features in detecting PC and clinically significant PC (csPC) at TB. PATIENTS AND METHODS: This was a retrospective cohort study of patients with rising and/or persistently elevated prostate-specific antigen (PSA) undergoing mpMRI followed by either transperineal SA-TB or transrectal COG-TB. The analysis showed a matched-paired analysis between SA-TB versus COG-TB without differences in clinical or radiological characteristics. Differences among detection of PC/csPC among groups were analyzed. A multivariable logistic regression model predicting PC at TB was fitted. The model was evaluated using the receiver operating characteristic-derived area under the curve, goodness of fit test, and decision-curve analyses. RESULTS: One hundred ninety-one and 87 patients underwent SA-TB or COG-TB, respectively. The multivariate logistic analysis showed that SA-TB was associated with overall PC (odds ratio [OR], 5.70; P < .01) and PC at TB (OR, 3.00; P < .01) but not with overall csPC (P = .40) and csPC at TB (P = .40). A nomogram predicting PC at TB was constructed using the Prostate Imaging Reporting and Data System version 2.0, age, PSA density and biopsy technique, showing improved clinical risk prediction against a threshold probability of 10% with a c-index of 0.83. CONCLUSION: In patients with suspected PC, software-assisted biopsy detects most cancers and outperforms the cognitive approach in targeting magnetic resonance imaging-visible lesions. Furthermore, we introduced a prebiopsy nomogram for the probability of PC in TB.

Continuous Hepatic Arterial Multiphase Magnetic Resonance Imaging During Free-Breathing.

PURPOSE: The aim of this study was to evaluate the feasibility of a prototype volume-interpolated breath-hold examination (VIBE) sequence using compressed sensing (VIBECS) for rapid multiphase arterial magnetic resonance imaging (MRI) at different temporal resolution during free-breathing in comparison with a conventional breath-hold approach (VIBESTD). MATERIAL AND METHODS: A total of 40 patients with liver malignancies were prospectively included in this study and underwent contrast-enhanced liver MRI at 1.5 T to evaluate the performance of VIBECS for rapid arterial multiphase imaging. An additional 40 patients examined with a VIBESTD were included serving as standard of reference. The VIBECS study cohort was subdivided into 2 groups (each n = 20). In both groups, VIBECS was continuously acquired for 60 seconds starting with the contrast agent administration (group A, temporal resolution 4 seconds; group B, temporal resolution 8 seconds). Subsequently, the time point with the subjectively best image quality was selected and defined as hepatic arterial dominant (HAD) phase. Overall image quality, lesion conspicuity, vessel contrast, and artifacts of HAD phase were assessed by 2 radiologists independently on a 5-point Likert scale (5 = excellent) and compared with arterial phase images of VIBESTD. In addition, signal attenuation/time curves of VIBECS were plotted for each patient to quantify the hepatic arterial enhancement. RESULTS: No patients were excluded and all HAD phases were reliably recorded in the investigated VIBECS cohort. Most commonly, HAD was observed at the ninth time point (36 seconds after intravenous contrast injection) in group A and at the fifth time point (40 seconds after intravenous contrast injection) in group B. Timing with VIBESTD was only adequate in 65% (26/40). Image quality, lesion conspicuity, and vessel contrast were good to excellent without significant differences between both VIBECS groups (P ≥ 0.2) and with significantly higher reading scores as compared with VIBESTD with respect to lesion conspicuity (P ≤ 0.006) and image quality (group B; P < 0.001). VIBECS showed reconstruction artifacts, which were significantly higher in group A (P = 0.001). Mean peak arterial enhancement was observed at the ninth time point (36 seconds) in group A and at the sixth (48 seconds) in group B. CONCLUSION: VIBECS allows for robust multiphase arterial imaging during free-breathing at high spatial and temporal resolution (preferably 8 seconds) with improved image quality and lesion conspicuity as compared with VIBESTD.

Added value of diffusion-weighted imaging in hepatic tumors and its impact on patient management.

BACKGROUND: To investigate the added diagnostic value of diffusion-weighted imaging (DWI) of the liver and its impact on therapy decisions in patients with hepatic malignancy. METHODS: Interdisciplinary gastrointestinal tumorboard cases concerning patients with hepatic malignancies discussed between 11/2015 and 06/2016 were included in this retrospective, single-center study. Two radiologists independently reviewed the respective liver MR-examination first without, then with DWI. The readers were blinded regarding number, position and size of hepatic malignancies. Cases in which DWI revealed additional findings concerning the hepatic tumor status as compared to conventional sequences alone were presented to experienced members of the interdisciplinary tumor board. In this retrospective setting changes in treatment decisions based on these additional findings in the DWI sequences were recorded. RESULTS: A total of 87 patients were included. DWI revealed additional findings in 12 patients (13,8%). These new findings had a direct effect on the therapy in 8 patients (9,2%): In 6 patients (6,9%) the surgical/interventional treatment was adapted (n = 5: extended resection, n = 1: with transarterial chemoembolization of a single hepatocellular carcinoma only detectable in DWI); 2 patients (2,3%) received systemic therapy (n = 1: neo-adjuvant, n = 1: palliative) based on the additional findings in DWI. In 4 patients (4.6%) additional DWI findings did not affect the therapeutic decision. CONCLUSIONS: DWI is a relevant diagnostic tool in oncologic imaging of the liver. By providing further information regarding tumor load in hepatic malignancies it can lead to a significant change in treatment.

MR arthrography of the hip: diagnostic performance and image quality of 3D-steady state free precession versus 2D turbo spin echo sequences.

OBJECTIVE: To retrospectively compare the diagnostic performance of isotropic 3D steady-state free precession (3D-SSFP) sequences with 2D turbo spin-echo proton density-weighted fat-saturated (2D-TSE-PD fs) images in hip magnetic resonance arthrography; arthroscopy was a standard of reference. METHODS: Eighty-one patients with suspected labral tears who underwent hip MR arthrography (3-T scanner) were included. 2D-TSE-PD fs sequences were acquired in three planes and a singular sagittal 3D-SSFP. Labral tears, cartilage pathology and bone marrow were independently assessed by two blinded radiologists using a 5-point Likert scale. Accuracy was determined in 39 patients using invasive arthroscopy. RESULTS: Diagnostic confidence of labral and cartilaginous pathologies based on image quality was rated higher for 3D-SSFP (4.5 ± 0.8; 4.35 ± 0.7; p < 0.0001), but inferior for bone marrow pathology (3.9 ± 0.7; 4.0 ± 0.7; p < 0.0001). In the arthroscopy patients, similar sensitivity (85.9%) but higher specificity (74.4vs.42.9%) and higher positive and negative predictive values were found in 3D-SSFP of labral and cartilage pathologies. CONCLUSIONS: 3D-SSFP in hip magnetic resonance arthrography offers increased accuracy in detecting labral and cartilage pathologies compared with 2D-TSE-PD, while reducing the acquisition time. A drawback of 3D-SSFP was the inferior diagnostic confidence for bone marrow evaluation; thus, 3D-SSFP should be combined with conventional 2D-TSE sequences.

Selecting living donors for uterus transplantation: lessons learned from two transplantations resulting in menstrual functionality and another attempt, aborted after organ retrieval.

PURPOSE: To contribute to establishing donor selection criteria based on our experience with two successful living-donor human uterus transplantations (UTx) and an aborted attempt. METHODS: This interventional study included three patients with uterine agenesis, aged 23, 34, and 23 years, scheduled for UTx, and their uterus-donating mothers, aged 46, 61, and 46 years, respectively. Interventions included preoperative investigations, donor surgery, back-table preparation, and recipient surgery. Preoperative imaging, surgical data, histopathology, menstrual pattern, and uterine blood flow were the main outcome measures. RESULTS: In the first case (46-year-old mother/23-year-old daughter), donor/recipient surgery took 12.12/5.95 h. Regular spontaneous menstruations started 6-week post-transplantation, continuing at 24-28-day intervals throughout the 6-month observation period. Repeated follow-up cervical biopsies showed no signs of rejection. In the second case (61-year-old donor), surgery lasted 13.10 h; attempts to flush the retrieved uterus failed due to extreme resistance of the left uterine artery (UA) and inability to perfuse the right UA. Transplantation was aborted to avoid graft vessel thrombosis or insufficient blood flow during potential pregnancy. Histopathology revealed intimal fibrosis and initial sclerosis (right UA), extensive intimal fibrosis (parametric arterial segments), and subtotal arterial stenosis (myometrial vascular network). In the third case (46-year-old mother/23-year-old daughter), donor/recipient surgery took 9.05/4.52 h. Menstruations started 6-week post-transplantation. Repeated cervical biopsies showed no signs of rejection during the initial 12-week follow-up period. CONCLUSIONS: Meticulous preoperative evaluation of potential living uterus donors is essential. This may include selective contrast-enhanced UA angiograms and limitation of donor age, at least in donors with risk factors for atherosclerosis. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03048396.

Implementation of a 5-Minute Magnetic Resonance Imaging Screening Protocol for Prostate Cancer in Men With Elevated Prostate-Specific Antigen Before Biopsy.

PURPOSE: The aims of this study were to establish a 5-minute magnetic resonance (MR) screening protocol for prostate cancer in men before biopsy and to evaluate effects on Prostate Imaging Reporting and Data System (PI-RADS) V2 scoring in comparison to a conventional, fully diagnostic multiparametric MR imaging (mpMRI) approach. MATERIALS AND METHODS: Fifty-two patients with elevated prostate-specific antigen levels and without prior biopsy were prospectively included in this institutional review board-approved study. In all patients, an mpMRI protocol according to the PI-RADS recommendations was acquired on a 3 T MRI system. In addition, an accelerated diffusion-weighted imaging sequence was acquired using simultaneous multislice technique (DW-EPISMS). Two readers independently evaluated the images for the presence/absence of prostate cancer according to the PI-RADS criteria and for additional findings. In a first reading session, only the screening protocol consisting of axial T2-weighted and DW-EPISMS images was made available. In a subsequent reading session, the mpMRI protocol was assessed blinded to the results of the first reading, serving as reference standard. RESULTS: Both readers successfully established a final diagnosis according to the PI-RADS criteria in the screening and mpMRI protocol. Mean lesion size was 1.2 cm in the screening and 1.4 cm in the mpMRI protocol (P = 0.4) with 35% (18/52) of PI-RADS IV/V lesions. Diagnostic performance of the screening protocol was excellent with a sensitivity and specificity of 100% for both readers with no significant differences in comparison to the mpMRI standard (P = 1.0). In 3 patients, suspicious lymph nodes were reported as additional finding, which were equally detectable in the screening and mpMRI protocol. CONCLUSIONS: A 5-minute MR screening protocol for prostate cancer in men with elevated prostate-specific antigen levels before biopsy is applicable for clinical routine with similar diagnostic performance as the full diagnostic mpMRI approach.

Targeted vs systematic robot-assisted transperineal magnetic resonance imaging-transrectal ultrasonography fusion prostate biopsy.

OBJECTIVE: To evaluate the performance of transperineal robot-assisted (RA) targeted (TB) and systematic (SB) prostate biopsy in primary and repeat biopsy settings. PATIENTS AND METHODS: Patients underwent RA biopsy between 2014 and 2016. Before RA-TB, multiparametric magnetic resonance imaging (mpMRI) was performed. Prostate lesions were scored (Prostate Imaging, Reporting and Data System, version 2) and used for RA-TB planning. In addition, RA-SB was performed. Available, whole-gland pathology was analysed. RESULTS: In all, 130 patients were biopsy naive and 72 had had a previous negative transrectal ultrasonography-guided biopsy. In total, 202 patients had suspicious mpMRI lesions. Clinically significant prostate cancer was found in 85% of all prostate cancer cases (n = 123). Total and clinically significant prostate cancer detection rates for RA-TB vs RA-SB were not significantly different at 77% vs 84% and 80% vs 82%, respectively. RA-TB demonstrated a better sampling performance compared to RA-SB (26.4% vs 13.9%; P < 0.001). CONCLUSION: Transperineal RA-TB and -SB showed similar clinically significant prostate cancer detection rates in primary and repeat biopsy settings. However, RA-TB offered a 50% reduction in biopsy cores. Omitting RA-SB is associated with a significant risk of missing clinically significant prostate cancer.

Imaging response assessment of immunotherapy in patients with renal cell and urothelial carcinoma.

PURPOSE OF REVIEW: Recent advances in anticancer immunotherapy have revolutionized the treatment of metastatic renal cell (RCC) and urothelial carcinoma. In this review, we discuss the mechanisms of action of these new therapeutic approaches, explicate the common adverse events, and highlight different imaging-based response criteria. RECENT FINDINGS: The recent introduction of immune-checkpoint inhibitors led to substantial advances in therapy of metastatic RCC and urothelial carcinoma. Because of the distinct effector mechanisms of these new substances, atypical response patterns such as transient enlargements of tumor lesions, appearance of new lesions after therapy, no measurable decrease in tumor size, or delayed responses are observed in medical imaging studies. This indicates that the established imaging-based response assessment according to the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines has shortcomings to comprehensively evaluate treatment effects. SUMMARY: While monitoring response to immunotherapy still relies on RECIST criteria, immune-related response criteria have been established to better address the imaging changes occurring under immunotherapy. Further studies with long-term follow-up are needed to properly identify and predict response after treatment beyond progression. Because of the expanding clinical use of immune checkpoint inhibitors, radiologists, urologist, and oncologists should be familiar with common imaging findings under this respective therapy.

Self-gated 4D-MRI of the liver: Initial clinical results of continuous multiphase imaging of hepatic enhancement.

PURPOSE: To evaluate the feasibility of a self-gated free-breathing volume-interpolated breath-hold examination (VIBE) sequence using compressed sensing (CS) for contrast-enhanced multiphase liver MRI. MATERIALS AND METHODS: We identified 23 patients who underwent multiphase gadobutrol-enhanced liver magnetic resonance imaging (MRI) using 1) a prototype free-breathing VIBE sequence with respiratory self-gating and CS (VIBECS ), and 2) a standard breath-hold VIBE (VIBESTD ) on the same 1.5T scanner at two timepoints. VIBECS was continuously acquired for 128 seconds and a time-series of 16 timepoints was jointly reconstructed from the dataset. The unenhanced, arterial, portal-venous, and venous timepoints with the best image quality were selected and compared to the corresponding VIBESTD series serving as reference. Image quality was assessed qualitatively (image quality, sharpness, lesion conspicuity, vessel contrast, noise, motion/other artifacts; two readers independently; 5-point Likert scale; 5 = excellent) and quantitatively (vessel contrast [VC], coefficient-of-variation [CV]) Statistics were performed using Wilcoxon-sign-rank (ordinal) and paired t-test (continuous variables). RESULTS: Image quality and lesion conspicuity revealed no significant differences between the sequences (P ≥ 0.3). VIBESTD showed a tendency to higher motion artifacts (P ≥ 0.07). Image sharpness significantly increased in VIBECS as compared to VIBESTD (P ≤ 0.03). Arterial phase vessel contrast appeared significantly lower in VIBECS than in VIBESTD (P = 0.04). VIBECS showed reconstruction artifacts not present in VIBESTD (P = 0.001). Image noise was significantly lower in VIBECS than in VIBESTD (P ≤ 0.004). Arterial phase VC was significantly lower in VIBECS than in VIBESTD (P = 0.01). CV revealed no differences between sequences (P = 0.7). CONCLUSION: VIBECS is feasible for continuous free-breathing contrast-enhanced multiphase liver MRI, providing similar image quality and lesion conspicuity as VIBESTD . LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:459-467.

Effect of reduced z-axis scan coverage on diagnostic performance and radiation dose of neck computed tomography in patients with suspected cervical abscess.

PURPOSE: To evaluate the effect of reduced z-axis scan coverage on diagnostic performance and radiation dose of neck CT in patients with suspected cervical abscess. METHODS: Fifty-one patients with suspected cervical abscess were included and underwent contrast-enhanced neck CT on a 2nd or 3rd generation dual-source CT system. Image acquisition ranged from the aortic arch to the upper roof of the frontal sinuses (CTstd). Subsequently, series with reduced z-axis coverage (CTred) were reconstructed starting at the aortic arch up to the orbital floor. CTstd and CTred were independently assessed by two radiologists for the presence/absence of cervical abscesses and for incidental and alternative findings. In addition, diagnostic accuracy for the depiction of the cervical abscesses was calculated for both readers. Furthermore, DLP (dose-length-product), effective dose (ED) and organ doses were calculated and compared for CTred and CTstd, using a commercially available dose management platform. RESULTS: A total of 41 abscesses and 3 incidental/alternative findings were identified in CTstd. All abscesses and incidental/alternative findings could also be detected on CTred resulting in a sensitivity and specificity of 1.0 for both readers. DLP, ED and organ doses of the brain, the eye lenses, the red bone marrow and the salivary glands of CTred were significantly lower than for CTstd (p<0.001). CONCLUSIONS: Reducing z-axis coverage of neck CT allows for a significant reduction of effective dose and organ doses at similar diagnostic performance as compared to CTstd.

Diagnostic accuracy of different magnetic resonance imaging sequences for detecting local tumor progression after radiofrequency ablation of hepatic malignancies.

OBJECTIVE: To evaluate the diagnostic accuracy of the individual sequences of a clinical routine liver MRI protocol for the detection of local tumour progression after radiofrequency (RF) ablation of hepatic malignancies. MATERIAL AND METHODS: A cohort of 93 patients treated for 140 primary and secondary hepatic malignancies with RF ablation was assembled for this retrospective study. The cohort contained 31 cases of local tumour progression, which occurred 8.3±6.2months (range: 4.0-28.2 months) after treatment. All patients underwent clinical routine follow-up MRI at 1.5T including following sequences: unenhanced T1-weighted fast low angle shot (FLASH-2D), T2-weighted turbo-spin-echo sequence, contrast-enhanced (CE) T1-weighted volume-interpolated breath-hold examination (VIBE), diffusion-weighted imaging (DWI). Follow-up was 32.7±22.5months (range: 4.0-138.3 months). Two readers independently evaluated the individual sequences separately for signs of local tumour progression. Diagnostic confidence was rated on a 4-point scale. Inter-reader agreement was assessed with Cohens kappa. Long-term follow-up and histological specimen served as standard of reference. RESULTS: Both readers reached the highest sensitivity for detection of local tumour progression with unenhanced T1-FLASH 2D (88.2% and 94.1%, respectively) and the highest specificity with CE T1-VIBE (96.2% and 97.2%, respectively). Highest inter-reader agreement was reached with T1-FLASH-2D (kappa=0.83). Typical pitfalls for false-positive diagnoses were focal cholestasis and vasculature adjacent to the ablation zone. Diagnostic confidence was highest with CE T1-VIBE for reader 1 and DWI for reader 2. CONCLUSION: Unenhanced T1-FLASH-2D is an essential sequence for follow-up imaging after tumour ablation with a high sensitivity for detection of local progression and a high inter-reader agreement.