Congenital diaphragmatic hernia: automatic lung and liver MRI segmentation with nnU-Net, reproducibility of pyradiomics features, and a machine learning application for the classification of liver herniation.

Prenatal assessment of lung size and liver position is essential to stratify congenital diaphragmatic hernia (CDH) fetuses in risk categories, guiding counseling, and patient management. Manual segmentation on fetal MRI provides a quantitative estimation of total lung volume and liver herniation. However, it is time-consuming and operator-dependent. In this study, we utilized a publicly available deep learning (DL) segmentation system (nnU-Net) to automatically contour CDH-affected fetal lungs and liver on MRI sections. Concordance between automatic and manual segmentation was assessed by calculating the Jaccard coefficient. Pyradiomics standard features were then extracted from both manually and automatically segmented regions. The reproducibility of features between the two groups was evaluated through the Wilcoxon rank-sum test and intraclass correlation coefficients (ICCs). We finally tested the reliability of the automatic-segmentation approach by building a ML classifier system for the prediction of liver herniation based on support vector machines (SVM) and trained on shape features computed both in the manual and nnU-Net-segmented organs. We compared the area under the classifier receiver operating characteristic curve (AUC) in the two cases. Pyradiomics features calculated in the manual ROIs were partly reproducible by the same features calculated in nnU-Net segmented ROIs and, when used in the ML procedure, to predict liver herniation (both AUC around 0.85).          Conclusion: Our results suggest that automatic MRI segmentation is feasible, with good reproducibility of pyradiomics features, and that a ML system for liver herniation prediction offers good reliability.          Trial registration: https://clinicaltrials.gov/ct2/show/NCT04609163?term=NCT04609163&draw=2&rank=1 ; Clinical Trial Identification no. NCT04609163. What is Known: • Magnetic resonance imaging (MRI) is crucial for prenatal congenital diaphragmatic hernia (CDH) assessment. It enables the quantification of the total lung volume and the extent of liver herniation, which are essential for stratifying the severity of CDH, guiding counseling, and patient management. • The manual segmentation of MRI scans is a time-consuming process that is heavily reliant upon the skill set of the operator. What is New: • MRI lung and liver automatic segmentation using the deep learning nnU-Net system is feasible, with good Jaccard coefficient values and satisfactory reproducibility of pyradiomics features compared to manual results. • A feasible ML system for predicting liver herniation could improve prenatal assessments and CDH patient management.

Accuracy of abbreviated multiparametric MRI-derived protocols in predicting local staging of prostate cancer in men undergoing radical prostatectomy.

BACKGROUND: Abbreviated magnetic resonance imaging (aMRI) protocols have emerged as an alternative to multiparametric MRI (mpMRI) to reduce examination time and costs. PURPOSE: To compare multiple aMRI protocols for predicting pathological stage ≥T3 (≥pT3) prostate cancer (PCa). MATERIAL AND METHODS: One hundred and eight men undergoing staging mpMRI before radical prostatectomy (RP) were retrospectively evaluated. 3.0-T imaging was performed with a 32-channel surface coil and a protocol including diffusion-weighted imaging (DWI), transverse T2-weighted (tT2W) imaging, coronal T2W (cT2W) imaging, sagittal T2W (sT2) imaging, and dynamic contrast-enhanced (DCE) imaging. Two readers independently assessed whether any MRI observation showed stage ≥T3 on each sequence (reading order: DWI, cT2W, tT2W, sT2W, DCE). Final stage was assessed by matching readers' assignments to pathology, and combining them into eight protocols: DWI + tT2W, DWI + cT2W + tT2W, DWI + tT2W + sT2W, DWI + cT2W + tT2W + sT2W, DWI + tT2W + DCE, DWI + cT2W + tT2W + DCE, DWI + tT2W + sT2W + DCE, and mpMRI. Diagnostic accuracy and inter-reader agreement for aMRI protocols were calculated. RESULTS: Prevalence of ≥pT3 PCa was 31.5%. Sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of aMRI protocols were comparable to mpMRI for R1. Sensitivity was 74.3% (95% confidence interval [CI] 64.8-72.0) to 77.1% (95% CI 67.9-84.4), and NPV 86.8% (95% CI 78.6-92.3) to 88.1% (95% CI 80.1-93.3). All accuracy measures of the various aMRI protocols were similar to mpMRI also for R2, albeit all slightly lower compared to R1. On a per-protocol basis, there was substantial inter-reader agreement in predicting stage ≥pT3 (k 0.63-0.67). CONCLUSION: When comparing the diagnostic accuracy of multiple aMRI protocols against mpMRI for predicting stage ≥pT3 PCa, the protocol with the fewest sequences (DWI + tT2W) is apparently equivalent to standard mpMRI.

Inter-reader agreement of high-resolution computed tomography findings in patients with COVID-19 pneumonia: A multi-reader study.

PURPOSE: To investigate the inter-reader agreement in assessing high-resolution computed tomography (HRCT) features of coronavirus disease 2019 (COVID-19) pneumonia. METHOD: Seventy-seven consecutive patients (mean age, 64 ± 15 years) with mild COVID-19 pneumonia that underwent HRCT were retrospectively included. Three radiologists [two devoted to thoracic imaging (R1, R2), and one generalist (R3)] on a per-examination basis independently assessed ground-glass opacity (GGO), consolidation, and crazy-paving pattern. The extent of each feature (total feature score, TFS) was semi-quantitatively assessed, and each TFS summed up to obtain total lung score (TLS). Presence of organizing pneumonia (OP) pattern was also recorded. The inter-reader agreement was calculated with Cohen's Kappa (k) and Free-Marginal Multirater k. Multivariable analysis was run to determine whether imaging features were predictive of short-term evolution to severe disease (need for ventilation). RESULTS: Most features showed substantial inter-reader agreement, including TLS > 6 (k = 0.69), which was an independent predictor of short-term occurrence of severe disease, regardless of the reader (OR 9-53.19). Consolidation TFS > 2 and OP pattern showed substantial and moderate agreement, respectively, only when comparing R1 and R2. Consolidation TFS > 2 and OP pattern were independent predictors of severe disease for R2 (OR 4.87) and R1 (OR 6), respectively. CONCLUSIONS: The inter-reader agreement for most HRCT features of COVID-19 pneumonia ranges moderate-to-substantial, though it depends on readers' experience in the case of consolidation and OP pattern.

Head-to-head comparison between multiparametric MRI, the partin tables, memorial sloan kettering cancer center nomogram, and CAPRA score in predicting extraprostatic cancer in patients undergoing radical prostatectomy.

BACKGROUND: It is unclear whether clinical models including the Partin tables (PT), the Memorial Sloan Kettering Cancer Center nomogram (MSKCCn), and the cancer of the prostate risk assessment (CAPRA) can benefit from incorporating multiparametric magnetic resonance imaging (mpMRI) when staging prostate cancer (PCa). PURPOSE: To compare the accuracy of clinical models, mpMRI, and mpMRI plus clinical models in predicting stage ≥pT3 of PCa. STUDY TYPE: Prospective monocentric cohort study. POPULATION: Seventy-three patients who underwent radical prostatectomy between 2016-2018. FIELD STRENGTH/SEQUENCE: 3.0T using turbo spin echo (TSE) imaging, single-shot echoplanar diffusion-weighted imaging, and T1 -weighted high-resolution-isotropic-volume-examination (THRIVE) contrast-enhanced imaging. ASSESSMENT: We calculated the probability of extraprostatic extension (EPE) using the PT and MSKCC, as well as the CAPRA score. Three readers with 2-8 years of experience in mpMRI independently staged PCa on imaging. STATISTICAL TESTS: Receiver operating characteristics analysis and logistic regression analysis to investigate the per-patient accuracy of mpMRI vs. clinical models vs. mpMRI plus clinical models in predicting stage ≥pT3. The alpha level was 0.05. RESULTS: Median probability for EPE and MSKCCn was 27.3% and 47.0%, respectively. Median CAPRA score was 3. Stage ≥pT3 occurred in 32.9% of patients. Areas under the curve (AUCs) were 0.62 for PT, 0.62 for MSKCCn, 0.64 for CAPRA, and 0.73-0.75 for mpMRI (readers 1-3) (P > 0.05 for all comparisons). Compared with mpMRI, the combination of mpMRI with PT or MSKCCn provided lower AUCs (P > 0.05 for all the readers), while the combination with CAPRA provided significantly higher (P < 0.05) AUCs in the case of readers 1 and 3. On multivariable analysis, mpMRI by reader 1 was the only independent predictor of stage ≥pT3 (odds ratio 7.40). DATA CONCLUSION: mpMRI was more accurate than clinical models and mpMRI plus clinical models in predicting stage ≥pT3, except for the combination of mpMRI and CAPRA in two out of three readers. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1604-1613.

Interreader agreement of PI-RADS v. 2 in assessing prostate cancer with multiparametric MRI: A study using whole-mount histology as the standard of reference.

BACKGROUND: Most studies assessing interreader agreement of Prostate Imaging Reporting and Data System v. 2 (PI-RADS v2) have used biopsy as the standard of reference, thus carrying the risk of not definitively noting all existent cancers. PURPOSE: To evaluate the interreader agreement in assessing prostate cancer (PCa) of PI-RADS v2, using whole-mount histology as the standard of reference. STUDY TYPE: Monocentric prospective cohort study. POPULATION: In all, 48 patients with biopsy-proven PCa referred for radical prostatectomy, undergoing staging multiparametric magnetic resonance imaging (mpMRI) between May 2016 to February 2017. FIELD STRENGTH/SEQUENCE: 3.0T system using high-resolution T2 -weighted imaging, diffusion-weighted imaging (echo-planar imaging with maximum b-value 2000 sec/mm2 ), and dynamic contrast-enhanced imaging (T1 -weighted high resolution isotropic volume examination; THRIVE) ASSESSMENT: Three radiologists blinded to final histology (2-8 years of experience) analyzed mpMRI images independently, scoring imaging findings in accordance with PI-RADS v2. On a per-lesion basis, we calculated overall and pairwise interreader agreement in assigning PI-RADS categories, as well as assessing malignancy with categories ≥3 or ≥4, and stage ≥pT3. STATISTICAL TESTS: Cohen's kappa analysis of agreement. RESULTS: On 71 lesions found on histology, there was moderate agreement in assigning PI-RADS categories to all cancers (k = 0.53) and clinically significant cancers (csPCa) (k = 0.47). Assessing csPCa with PI-RADS ≥4 cutoff provided higher agreement than PI-RADS ≥3 cutoff (k = 0.63 vs. 0.57). Interreader agreement was higher between more experienced readers, with the most experienced one achieving the highest cancer detection rate (0.73 for csPCa using category ≥4). There was substantial agreement in assessing stage ≥pT3 (k = 0.72). DATA CONCLUSION: We found moderate to substantial agreement in assigning the PI-RADS v2 categories and assessing the spectrum of cancers found on whole-mount histology, with category 4 as the most reproducible cutoff for csPCa. Readers' experience influenced interreader agreement and cancer detection rate. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:546-555.

Comparison between different imaging techniques in the evaluation of malignant breast lesions: can 3D ultrasound be useful?

PURPOSE: This study was done to assess the feasibility of three-dimensional ultrasonography (3D-US) for volume calculation of solid breast lesions. MATERIALS AND METHODS: The volumes of 36 malignant lesions were measured using conventional 2D-US, 3D-US and magnetic resonance imaging (MRI) and compared with that obtained with histology (standard of reference). With 2D Ultrasouns, volume was estimated by measuring three diameters and calculating volume with the mathematical formula for spheres. With 3D-US, stored images were retrieved and boundaries of masses were manually outlined; volume calculation was performed with VOCAL software. For MRI, volume measurements were obtained with special software for 3D reconstructions, after each lesion had been manually outlined. Histology measured the three main diameters and the volume was estimated using the mathematical formula for spheres. Interclass correlation coefficient (ICC) and Bland-Altman plots were used to assess agreement between the volumes measured. RESULTS: ICC indicated that a good level of concordance was identified between 3D-US and histology (0.79). According to the Bland-Altman analysis, limits of agreement of mean differences of the volumes measured with the three imaging modalities were comparable with histology: -2 ÷ 1.5 cm(3) for 3D-US; -2.3 ÷ 1.3 cm(3) for 2D-US and -2.2 ÷ 1.6 cm(3) for MRI. CONCLUSIONS: 3D-US is a reliable method for the volumetric assessment of breast lesions. 3D-US is able to provide valuable information for the preoperative evaluation of lesions.

Negative predictive value for cancer in patients with "gray-zone" PSA level and prior negative biopsy: preliminary results with multiparametric 3.0 Tesla MR.

PURPOSE: To investigate the negative predictive value (NPV) for malignancy of 3.0 Tesla (T) MRI in patients with "gray zone" PSA level and prior negative biopsies. MATERIALS AND METHODS: We enrolled 26 patients with PSA level between 2.5 and 10 ng/mL and no cancer at previous biopsies. Examinations were performed on a 3.0T system using T2-weighted imaging, diffusion-weighted imaging, spectroscopy, and postcontrast dynamic study. A regional scheme was used to record MRI findings and to perform subsequent transrectal-ultrasonography-guided biopsy. Based on the matching between imaging and biopsy findings we estimated MRI predictive values, sensitivity, specificity and accuracy on a per-patient and per-region basis. RESULTS: On a per patient basis, MRI had five true-positive (5/26; 19.2%), eight true-negative (8/26; 30.8%) and no false-negative cases, corresponding to a NPV and sensitivity of 100% each. Thirteen patients were assessed as false-positive cases (13/26; 50.0%) (specificity of 38.1%). Five of them (5/26; 19.2%) showed high-grade prostatic intraepithelial neoplasia (HGPIN) and atypical small-acinar proliferation (ASAP) at biopsy. T2-weighted imaging alone showed per-region NPV (96.8%). CONCLUSION: Because of the high NPV, MRI had the potential to avoid unnecessary biopsy in approximately one-third of "gray-zone" patients with a negative examination. Additionally, MRI was useful to address to biopsy more than one-third of patients with cancer or high-risk lesions as HGPIN and ASAP.

Comparison of multiple abbreviated multiparametric MRI-derived protocols for the detection of clinically significant prostate cancer.

BACKGROUND: The aim of this paper was to compare the accuracy of multiple abbreviated multiparametric magnetic resonance imaging (mpMRI)-derived protocols in detecting clinically significant prostate cancer (csPCa). METHODS: One hundred and eight men undergoing staging 3.0T mpMRI with a Prostate Imaging - Reporting and Data System version 2 (PI-RADSv2)-compliant protocol before radical prostatectomy (RP) were retrospectively evaluated. Two readers (R1, R2) independently analyzed mpMRI, assigning a PI-RADSv2 category to each observation as appearing on each examination sequence. A study coordinator assessed final PI-RADSv2 category by combining readers' assignments according to four protocols: short MRI (sMRI) (diffusion-weighted imaging + axial T2-weighted imaging), contrast-enhanced short MRI (cesMRI) (sMRI + dynamic contrast-enhanced [DCE] imaging), biparametric MRI (diffusion-weighted imaging + multiplanar T2-weigthed imaging), and mpMRI. Using RP pathology as the reference standard for csPCa, we calculated the per-lesion cancer detection rate (CDR) and false discovery rate (FDR) for each MRI protocol (cut-off PI-RADSv2 category ≥3), and the per-PI-RADSv2 category prevalence of csPCa and false positives. RESULTS: Pathology after RP found 142 csPCas with median International Society of Urogenital Pathology grade group 2, and stage ≤pT2c in 68.6% of cases. CDR was comparable across the four MRI protocols (74.6% to 75.3% for R1, and 68.3% for R2). FDR was comparable as well (14.4%-14.5% for R1 and 11.1% for R2). sMRI was the minimum protocol equaling mpMRI in terms of CDR, although cesMRI, similarly to mpMRI, was associated with fewer PI-RADSv2 category 3 assignments and higher prevalence of csPCa within PI-RADSv2 category 3 observations (66.7% versus 76.9% for R1, and 100% versus 91.7% for R2, respectively). CONCLUSIONS: Among multiple abbreviated mpMRI-derived protocols, cesMRI was the one equaling mpMRI in terms of csPCa detection and minimizing PI-RADSv2 category 3 assignments.

Incidental pancreatic cysts on 3D turbo spin echo magnetic resonance cholangiopancreatography: prevalence and relation with clinical and imaging features.

PURPOSE: To estimate the prevalence of incidental pancreatic cysts (IPCs) in asymptomatic patients addressed to magnetic resonance cholangiopancreatography (MRCP), and to correlate it with clinical and imaging features. MATERIALS AND METHODS: Magnetic resonance cholangiopancreatography performed over 26-months on 152 patients with unsuspected/unknown pancreatic disease were reviewed to assess IPCs' features of presentation. Multivariate analysis was performed to evaluate the correlation of IPCs with clinical information and type of pancreaticobiliary findings at MRCP. RESULTS: Prevalence of IPCs was 44.7%. Cysts sized 3-24 mm (mean, 6.08 mm), and were ≤4 in number in 83.8% of patients. Based on number, dimensions and relation with the main pancreatic duct, IPCs presented with intraductal-papillary-mucinous neoplasm (IPMN)-like or indeterminate patterns in 31.7% and 13.1% of patients, respectively. At follow-up on 24 patients, no evolution was found, except in one patient with proven IPMN showing increase in cysts number and dimensions (evolution rate of 4.1%). Features correlating with IPCs were age ≥60 years old, and history of autoimmune hepatobiliary disease, showing odds ratios of 5.95 (95% CI 2.77-12.79) and 0.13 (95% CI 0.04-0.44), respectively. CONCLUSIONS: Incidental pancreatic cysts represent a frequent finding at MRCP, correlating positively with increasing age, and negatively with biliary autoimmune disease. Cysts more frequently present with IPMN-like pattern.

Contrast-enhanced ultrasound applications in liver transplant imaging.

Contrast-enhanced ultrasound (CEUS) is gaining ever-increasing acceptance in the preoperative and postoperative evaluation of liver-transplanted patients. While indications are still a matter of research, CEUS is used in tertiary centers to supplement ultrasound (US) and Color Doppler US examination, with the potential of providing a comprehensive first-line ultrasound-based diagnosis. Alternatively, CEUS is used as a problem-solving tool when previous cross-sectional or US imaging was inconclusive, especially in assessing hepatocellular carcinoma, parenchymal perfusion abnormalities, the vascular status, and even the biliary tree. This review describes the potential use for CEUS in the setting of orthotopic liver transplantation (OLT).

Role of contrast-enhanced ultrasound in assessing indeterminate renal lesions and Bosniak ≥2F complex renal cysts found incidentally on CT or MRI.

OBJECTIVE: To investigate the impact of contrast-enhanced ultrasound (CEUS) in reclassifying incidental renal findings categorized as indeterminate lesions (IL) or Bosniak ≥ 2F complex renal cysts (CRC) on CT or MRI. METHODS: We retrospectively included 44 subjects who underwent CEUS between 2016 and 2019 to assess 48 IL (n = 12) and CRC (n = 36) incidentally found on CT or MRI. CEUS was performed by one radiologist with 10 year of experience with a sulfur hexafluoride-filled microbubble contrast agent. The same radiologist, blinded to clinical information and previous CT/MRIs, retrospectively reviewed CEUS images/videos, categorizing renal findings with Bosniak-derived imaging categories ranging from 0 (indeterminate) to 5 (solid lesion). CEUS-related reclassification rate was calculated (proportion of IL reclassified with an imaging category >0, or CRC reclassified below or above imaging category >2F). Using histological examination or a ≥ 24 months follow-up as the standard of reference, we also estimated per-lesion sensitivity/specificity for malignancy. RESULTS: CEUS reclassified 24/48 findings (50.0%; 95% C.I. 35.2-64.7), including 12/12 IL (100%; 95% CI 73.5-100) and 12/36 CRC (33.3%; 95% C.I. 18.5-50.9), mostly above category >2F (66.7%). CEUS and CT/MRI showed 96.0% (95%CI 79.7-99.9) vs 44.0% (95%CI 24.4-65.1) sensitivity, and 82.6% (95%CI 61.2-95.1) vs 60.9% (95%CI 38.5-80.3%) specificity. CONCLUSION: CEUS provided substantial and accurate reclassification of CT/MRI incidental findings. ADVANCES IN KNOWLEDGE: Previous studies included Bosniak 2 incidental findings, thus possibly underestimating CEUS-induced reclassification rates. Using a more meaningful cut-off (Bosniak ≥2F), problem-solving CEUS was effective as well, with higher reclassification rates for CRC than in literature.

A maChine and deep Learning Approach to predict pulmoNary hyperteNsIon in newbornS with congenital diaphragmatic Hernia (CLANNISH): Protocol for a retrospective study.

INTRODUCTION: Outcome predictions of patients with congenital diaphragmatic hernia (CDH) still have some limitations in the prenatal estimate of postnatal pulmonary hypertension (PH). We propose applying Machine Learning (ML), and Deep Learning (DL) approaches to fetuses and newborns with CDH to develop forecasting models in prenatal epoch, based on the integrated analysis of clinical data, to provide neonatal PH as the first outcome and, possibly: favorable response to fetal endoscopic tracheal occlusion (FETO), need for Extracorporeal Membrane Oxygenation (ECMO), survival to ECMO, and death. Moreover, we plan to produce a (semi)automatic fetus lung segmentation system in Magnetic Resonance Imaging (MRI), which will be useful during project implementation but will also be an important tool itself to standardize lung volume measures for CDH fetuses. METHODS AND ANALYTICS: Patients with isolated CDH from singleton pregnancies will be enrolled, whose prenatal checks were performed at the Fetal Surgery Unit of the Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (Milan, Italy) from the 30th week of gestation. A retrospective data collection of clinical and radiological variables from newborns' and mothers' clinical records will be performed for eligible patients born between 01/01/2012 and 31/12/2020. The native sequences from fetal magnetic resonance imaging (MRI) will be collected. Data from different sources will be integrated and analyzed using ML and DL, and forecasting algorithms will be developed for each outcome. Methods of data augmentation and dimensionality reduction (feature selection and extraction) will be employed to increase sample size and avoid overfitting. A software system for automatic fetal lung volume segmentation in MRI based on the DL 3D U-NET approach will also be developed. ETHICS AND DISSEMINATION: This retrospective study received approval from the local ethics committee (Milan Area 2, Italy). The development of predictive models in CDH outcomes will provide a key contribution in disease prediction, early targeted interventions, and personalized management, with an overall improvement in care quality, resource allocation, healthcare, and family savings. Our findings will be validated in a future prospective multicenter cohort study. REGISTRATION: The study was registered at ClinicalTrials.gov with the identifier NCT04609163.

Comparison of portal venous and delayed phases of gadolinium-enhanced magnetic resonance imaging study of cirrhotic liver for the detection of contrast washout of hypervascular hepatocellular carcinoma.

OBJECTIVE: To retrospectively compare portal venous phase (PVP) and delayed phase (DP) for the detection of tumor washout at gadobenate dimeglumine-enhanced liver magnetic resonance imaging (MRI) in cirrhotic patients with hypervascular hepatocellular carcinoma (HCC). METHODS: Thirty-three patients with 55 HCCs underwent 1.5-T MRI by means of fat-suppressed T1-weighted sequence obtained before and after gadobenate dimeglumine administration, during early and late arterial phases, PVP (70 seconds), and DP (180 seconds). Detection rates of contrast washout of hypervascular HCCs and tumor-to-liver contrast on PVP and DP were measured and compared. RESULTS: Among 54 hypervascular HCCs, washout was present in 24 (44%) of 54 tumors on PVP and in 44 (82%) of 54 on DP (P < 0.001). In 20 (37%) of 54 tumors, washout was deemed present only on DP. Delayed phase images yielded significantly higher mean tumor-to-liver contrast absolute values compared with PVP images (-24.5 [56.1] vs -9.3 [52.6], P = 0.001). CONCLUSIONS: Delayed phase is superior to PVP for the washout detection of hypervascular HCC at gadobenate dimeglumine-enhanced MRI of cirrhotic liver.

Role for contrast-enhanced ultrasound in assessing complications after kidney transplant.

Kidney transplantation (KT) is an effective treatment for end-stage renal disease. Despite their rate has reduced over time, post-transplant complications still represent a major clinical problem because of the associated risk of graft failure and loss. Thus, post-KT complications should be diagnosed and treated promptly. Imaging plays a pivotal role in this setting. Grayscale ultrasound (US) with color Doppler analysis is the first-line imaging modality for assessing complications, although many findings lack specificity. When performed by experienced operators, contrast-enhanced US (CEUS) has been advocated as a safe and fast tool to improve the accuracy of US. Also, when performing CEUS there is potentially no need for further imaging, such as contrast-enhanced computed tomography or magnetic resonance imaging, which are often contraindicated in recipients with impaired renal function. This technique is also portable to patients' bedside, thus having the potential of maximizing the cost-effectiveness of the whole diagnostic process. Finally, the use of blood-pool contrast agents allows translating information on graft microvasculature into time-intensity curves, and in turn quantitative perfusion indexes. Quantitative analysis is under evaluation as a tool to diagnose rejection or other causes of graft dysfunction. In this paper, we review and illustrate the indications to CEUS in the post-KT setting, as well as the main CEUS findings that can help establishing the diagnosis and planning the most adequate treatment.

Incidental pancreatic cysts: a frequent finding in liver-transplanted patients as assessed by 3D T2-weighted turbo spin echo magnetic resonance cholangiopancreatography.

CONTEXT: The increasing frequency of incidental pancreatic cysts at imaging is a challenging topic due to the uncertainty of the aggressiveness of these lesions, especially small ones. To date, no data exist about their prevalence in a population of liver-transplanted patients. OBJECTIVE: To determine the prevalence of incidental pancreatic cysts in liver-transplanted patients using magnetic resonance cholangiopancreatography. DESIGN: A retrospective, single center case series. SETTING: A tertiary referral centre. Interventions and patients Seventy-two examinations were performed over a two-year period in 47 liver-transplanted patients suspected for biliary complications. MAIN OUTCOME MEASURES: Prevalence of incidental pancreatic cysts; proportion of cyst evolution over time; association of cysts with clinical and imaging features. RESULTS: The prevalence of pancreatic cysts was 59.6%. Analysis showed a mean diameter of 5.4 mm and the presence of 1-3 cysts in 78.6% of patients (22/28). Communication with the main pancreatic duct was identified for 28 relatively larger cysts (up to 14 mm) in 14 subjects. An "intraductal papillary mucinous neoplasia-like pattern" was observed in 12 patients with cysts, based on the number of cysts, dimensions, and distribution. Out of the 15 patients who underwent additional MRCPs to monitor biliary findings, only one patient with proven intraductal papillary mucinous neoplasia showed modification of the cysts at follow-up. Among the evaluated pre- or post-transplantation factors (sex, age, etiology of cirrhosis, pre-transplant hepatocarcinoma, pancreatic abnormalities other than cysts, type of pancreaticobiliary channel/biliary anastomosis, presence of biliary complications, lithiasic biliary complications, transplant-examination interval), only the alcoholic etiology of cirrhosis was associated with the prevalence of pancreatic cysts (P=0.006). CONCLUSIONS: Incidental pancreatic cysts are frequent in liver-transplanted patients. Clinical significance, relation to transplant, impact on patient management before and after transplant are still under debate and a matter for further investigation.

Biliary complications after orthotopic liver transplantation: MRCP findings.

Orthotopic liver transplantation is a widely accepted treatment for end-stage liver disease and selected cases of hepatocellular carcinoma. Despite surgical progresses, biliary complications after transplantation remain a serious cause of morbidity, mortality, and graft dysfunction or failure in recipients. Early complications occur within a few weeks after transplantation and are mainly represented by bile leakage. Late complications, which become evident from 3 months to years, include strictures, stones, intraductal debris or sludge formation, kinking and ampullary dysfunction. Donor-to-recipient common bile duct disproportion has been reported as a borderline condition. Diagnosis is challenging because of the low specificity of clinical and biologic findings. Sonography does not provide projectional images of the biliary tract or direct evaluation of the anastomoses. Moreover, direct cholangiographic procedures have an unacceptable rate of complications to be used in patients with low clinical suspicion. Magnetic resonance cholangiography is a safe and accurate tool, playing an increasing role in the diagnosis and management of biliary complications. Heavily T2-weighted images provide panoramic, detailed evaluation of the biliary tract, showing biliary complications as a variable combination of bile duct dilatation, strictures, filling defects, fluid collections and peculiar morphologic changes, as described in this paper.

Detection of transplant renal artery stenosis with contrast-enhanced ultrasound.

Transplant renal artery stenosis (TRAS) is a vascular complication occurring during the first 2 years after kidney transplantation, with an incidence and a prevalence ranging from 1% to 23%, and from 1.5% to 4%, respectively. Detection of TRAS is the key, since most stenoses may progress to renal graft loss, however it may be difficult to detect due to its nonspecific clinical manifestations. Although Doppler ultrasound has become a primary imaging technique, digital subtraction angiography (DSA) remains the gold standard for diagnosing TRAS. We present a case of delayed graft function following kidney transplantation complicated by a lateral by-pass with prosthesis upstream and downstream of renal anastomosis, TRAS criteria were unclear using Doppler ultrasound, contrast-enhanced computed tomography-scan, and DSA. Only contrast-enhanced ultrasound (CE-US), observing a delayed and pulsating contest impregnation of renal parenchyma, supported the hypothesis of TRAS that was confirmed by the measurement of trans-anastomosis pressure gradient during DSA.

Imaging of liver transplantation.

Liver transplantation (LT) is the treatment of choice for end-stage chronic liver disease, fulminant liver failure and early stage hepatocellular carcinoma. As discussed in this review, state-of-the-art imaging modalities including ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) play a pivotal role in the selection of patients and donors, as well as in early detection of those complications at risk of impairing graft function and/or survival. We also illustrate main imaging findings related to the wide spectrum of clinical problems raised by LT.

Post-operative imaging in liver transplantation: state-of-the-art and future perspectives.

Orthotopic liver transplantation (OLT) represents a major treatment for end-stage chronic liver disease, as well as selected cases of hepatocellular carcinoma and acute liver failure. The ever-increasing development of imaging modalities significantly contributed, over the last decades, to the management of recipients both in the pre-operative and post-operative period, thus impacting on graft and patients survival. When properly used, imaging modalities such as ultrasound, multidetector computed tomography, magnetic resonance imaging (MRI) and procedures of direct cholangiography are capable to provide rapid and reliable recognition and treatment of vascular and biliary complications occurring after OLT. Less defined is the role for imaging in assessing primary graft dysfunction (including rejection) or chronic allograft disease after OLT, e.g., hepatitis C virus (HCV) recurrence. This paper: (1) describes specific characteristic of the above imaging modalities and the rationale for their use in clinical practice; (2) illustrates main imaging findings related to post-OLT complications in adult patients; and (3) reviews future perspectives emerging in the surveillance of recipients with HCV recurrence, with special emphasis on MRI.

Will Multi-Parametric Magnetic Resonance Imaging be the Future Tool to Detect Clinically Significant Prostate Cancer?

Multi-parametric magnetic resonance imaging is an emerging imaging modality for diagnosis, staging, characterization, and treatment planning of prostate cancer. In this report, we reviewed the literature for studies assessing the accuracy of multi-parametric magnetic resonance imaging in detecting clinically significant prostate cancer, and we critically examined the future role of this imaging tool in various clinical diagnostic settings. There is accumulating evidence suggesting a high accuracy of multi-parametric magnetic resonance imaging in ruling out clinically significant disease. Although definition for clinically significant disease widely varies, the negative predictive value is very high at up to 98%. Multi-parametric magnetic resonance imaging should, thus, be further evaluated for application in different clinical scenarios in which it is desirable to reduce the proportion of unnecessary prostate biopsies and to limit the detection of indolent disease, such as opportunistic screening, persistent prostate cancer suspicion in men with previous negative prostate biopsies, and eligibility for active surveillance. Continued improvement in standardization of technical parameters, functional sequences, and image reporting systems is a pre-requisite for a rapid and successful dissemination of this imaging modality.