Perspectives on technology: Prostate Imaging-Reporting and Data System (PI-RADS) interobserver variability.

OBJECTIVES: To explore the topic of Prostate Imaging-Reporting and Data System (PI-RADS) interobserver variability, including a discussion of major sources, mitigation approaches, and future directions. METHODS: A narrative review of PI-RADS interobserver variability. RESULTS: PI-RADS was developed in 2012 to set technical standards for prostate magnetic resonance imaging (MRI), reduce interobserver variability at interpretation, and improve diagnostic accuracy in the MRI-directed diagnostic pathway for detection of clinically significant prostate cancer. While PI-RADS has been validated in selected research cohorts with prostate cancer imaging experts, subsequent prospective studies in routine clinical practice demonstrate wide variability in diagnostic performance. Radiologist and biopsy operator experience are the most important contributing drivers of high-quality care among multiple interrelated factors including variability in MRI hardware and technique, image quality, and population and patient-specific factors such as prostate cancer disease prevalence. Iterative improvements in PI-RADS have helped flatten the curve for novice readers and reduce variability. Innovations in image quality reporting, administrative and organisational workflows, and artificial intelligence hold promise in improving variability even further. CONCLUSION: Continued research into PI-RADS is needed to facilitate benchmark creation, reader certification, and independent accreditation, which are systems-level interventions needed to uphold and maintain high-quality prostate MRI across entire populations.

Clinical characteristics and outcomes in patients with metastatic breast cancer and pseudocirrhosis: a single center retrospective cohort study.

PURPOSE: Pseudocirrhosis is a term used to describe changes in hepatic contour that mimic cirrhosis radiographically, but lack the classic pathologic features of cirrhosis. This radiographic finding is frequently found in patients with metastatic breast cancer (MBC), but the risk factors and clinical consequences are poorly understood. METHODS: In this retrospective study, we identified patients with MBC and pseudocirrhosis who were treated at a single center from 2002 to 2021. We used chart extraction and radiology review to determine demographic characteristics, treatment history, imaging features, and complications of pseudocirrhosis. RESULTS: 120 patients with MBC and pseudocirrhosis were identified with the following BC subtypes: hormone receptor (HR) positive, HER2 negative (n = 99, 82.5%), HR+/HER2+ (n = 14, 11.7%), HR- /HER2+ (n = 3, 2.5%), and triple negative (TNBC; n = 4, 3.3%). All patients had liver metastases and 82.5% (n = 99) had > 15 liver lesions. Thirty-six patients (30%) presented with de novo metastatic disease. Median time from MBC diagnosis to pseudocirrhosis was 29.2 months. 50% of patients had stable or responding disease at the time of pseudocirrhosis diagnosis. Sequelae of pseudocirrhosis included radiographic ascites (n = 97, 80.8%), gastric/esophageal varices (n = 68, 56.7%), splenomegaly (n = 26, 21.7%), GI bleeding (n = 12, 10.0%), and hepatic encephalopathy (n = 11, 9.2%). Median survival was 7.9 months after pseudocirrhosis diagnosis. Radiographic ascites was associated with shorter survival compared to no radiographic ascites (42.8 vs. 76.2 months, p = < 0.001). CONCLUSIONS: This is the largest case series of patients with MBC and pseudocirrhosis. Nearly all patients had HR+ MBC and extensive liver metastases. Survival was short after pseudocirrhosis and prognosis worse with radiographic ascites.

Per-patient Negative Predictive Value of the CT and MRI Liver Imaging Reporting and Data System Version 2018 Treatment Response Algorithm for Hepatocellular Carcinoma.

Background The Liver Imaging Reporting and Data System version 2018 (LI-RADS) treatment response algorithm (TRA) is a high-specificity, lower-sensitivity grading system to diagnose hepatocellular carcinoma (HCC) and recurrence after local-regional therapy. However, the emphasis on specificity can result in disease understaging, potentially leading to poorer posttransplant outcomes. Purpose To determine the negative predictive value (NPV) of pretransplant CT and MRI assessment for viable HCC on a per-patient basis using the LI-RADS TRA, considering explant pathology as the reference standard. Materials and Methods Patient records from 218 consecutive adult patients from a single institution with HCC who underwent liver transplant from January 2011 to November 2017 were retrospectively reviewed. Two readers blinded to the original report reviewed immediate (within 90 days) pretransplant imaging and characterized observations according to the LI-RADS TRA. Based on this, patients with LR-4, LR-5, or LR-TR (treatment response) viable tumors were designated as viable tumor; patients with solely LR-3 or LR-TR equivocal tumors were designated as equivocal; and patients with only LR-TR nonviable lesions were designated as no viable disease. Patients were designated as within or outside the Milan criteria. These per-patient designations were compared with the presence of viable disease at explant pathology. Fisher exact test was used to compare the differences between CT and MRI. Weighted κ values were used to calculate interreader reliability. Results Final study sample consisted of 206 patients (median age, 61 years [IQR, 57-65 years]; 157 male patients and 49 female patients). Per-patient LI-RADS TRA assessment of pretransplant imaging had an NPV of 32% (95% CI: 27, 38) and 26% (95% CI: 20, 33) (readers 1 and 2, respectively) for predicting viable disease. Seventy-five percent (reader 1) and 77% (reader 2) of patients deemed equivocal had residual tumors at explant pathology. Weighted interreader reliability was substantial (κ = 0.62). Conclusion Patient-based stratification of viable, equivocal, and nonviable disease at pretransplant CT or MRI, based on LI-RADS TRA, demonstrated low negative predictive value in excluding HCC at explant pathology. © RSNA, 2023 See also the editorial by Tamir and Tau in this issue.

Positive Versus Neutral Oral Contrast Material for Detection of Malignant Deposits in Intraabdominal Nonsolid Organs on CT.

BACKGROUND. Data are limited regarding utility of positive oral contrast material for peritoneal tumor detection on CT. OBJECTIVE. The purpose of this article is to compare positive versus neutral oral contrast material for detection of malignant deposits in nonsolid intraabdominal organs on CT. METHODS. This retrospective study included 265 patients (133 men, 132 women; median age, 61 years) who underwent an abdominopelvic CT examination in which the report did not suggest presence of malignant deposits and a subsequent CT examination within 6 months in which the report indicated at least one unequivocal malignant deposit. Examinations used positive (iohexol; n = 100) or neutral (water; n = 165) oral agents. A radiologist reviewed images to assess whether the deposits were visible (despite clinical reports indicating no deposits) on unblinded comparison with the follow-up examinations; identified deposits were assigned to one of seven intraabdominal compartments. The radiologist also assessed adequacy of bowel filling with oral contrast material. Two additional radiologists independently reviewed examinations in blinded fashion for malignant deposits. NPV was assessed of clinical CT reports and blinded retrospective readings for detection of malignant deposits visible on unblinded comparison with follow-up examinations. RESULTS. Unblinded review identified malignant deposits in 58.1% (154/265) of examinations. In per-patient analysis of clinical reports, NPV for malignant deposits was higher for examinations with adequate bowel filling with positive oral contrast material (65.8% [25/38]) than for examinations with inadequate bowel filling with positive oral contrast material (45.2% [28/62], p = .07) or with neutral oral contrast material regardless of bowel filling adequacy (35.2% [58/165], p = .002). In per-compartment analysis of blinded interpretations, NPV was higher for examinations with adequate and inadequate bowel filling with positive oral contrast material than for examinations with neutral oral contrast regardless of bowel filling adequacy (reader 1: 94.7% [234/247] and 92.5% [382/413] vs 88.3% [947/1072], both p = .045; reader 2: 93.1% [228/245] and 91.6% [361/394] vs 85.9% [939/1093], both p = .01). CONCLUSION. CT has suboptimal NPV for malignant deposits in intraabdominal nonsolid organs. Compared with neutral material, positive oral contrast material improves detection, particularly with adequate bowel filling. CLINICAL IMPACT. Optimization of bowel preparation for oncologic CT may help avoid potentially severe clinical consequences of missed malignant deposits.

Prostate-specific Membrane Antigen PET in Prostate Cancer.

Prostate-specific membrane antigen (PSMA)-targeted radiopharmaceuticals are playing a large role at the time of initial staging and biochemical recurrence for localizing prostate cancer, as well as in other emerging clinical settings. PSMA PET has demonstrated increased detection rate compared with conventional imaging and has been shown to change management plans in a substantial percentage of cases. The aims of this narrative review are to highlight the development and clinical impact of PSMA PET radiopharmaceuticals, to compare PSMA to other agents such as fluorine 18 fluciclovine and carbon 11 choline, and to highlight some of the individual PSMA PET agents that have contributed to the advancement of prostate cancer imaging.

Müllerian Duct Anomalies: Role in Fertility and Pregnancy.

Müllerian duct anomalies (MDAs) have important implications for the reproductive health of female patients. In patients with both infertility and recurrent pregnancy loss, the incidence of MDAs is as high as 25%. Congenital uterine anomalies are often only part of a complex set of congenital anomalies involving the cervix, vagina, and urinary tract. Multiple classification systems for MDAs exist, each with different criteria that vary most for the diagnosis of septate uterus. Recognizing the features that guide clinical management is essential for interpretation. Identification of an MDA should prompt evaluation for associated urinary tract anomalies. In patients with infertility who seek to use assisted reproductive technologies such as intrauterine insemination, recognition of MDAs may have an affect on reproductive success, particularly in patients who have an incomplete and clinically occult septum that divides the cervix. Two-dimensional US is the first-line modality for evaluating the uterus and adnexa. Three-dimensional (3D) US or MRI may help to visualize the external uterine fundal contour and internal indentation of the endometrial cavity, which are two morphologic characteristics that are keys to the diagnosis of congenital uterine anomalies. Hysterosalpingo contrast-enhanced US may be performed in conjunction with 3D US to evaluate uterine morphologic characteristics, the endometrial cavity, and tubal patency in a single examination. MRI helps to characterize rudimentary uteri in patients with müllerian hypoplasia and allows assessment for ectopic ureters, abnormally positioned ovaries, or associated deep infiltrative endometriosis. Online supplemental material is available for this article. ©RSNA, 2021.

Mask-Guided Convolutional Neural Network for Breast Tumor Prognostic Outcome Prediction on 3D DCE-MR Images.

In this proof-of-concept work, we have developed a 3D-CNN architecture that is guided by the tumor mask for classifying several patient-outcomes in breast cancer from the respective 3D dynamic contrast-enhanced MRI (DCE-MRI) images. The tumor masks on DCE-MRI images were generated using pre- and post-contrast images and validated by experienced radiologists. We show that our proposed mask-guided classification has a higher accuracy than that from either the full image without tumor masks (including background) or the masked voxels only. We have used two patient outcomes for this study: (1) recurrence of cancer after 5 years of imaging and (2) HER2 status, for comparing accuracies of different models. By looking at the activation maps, we conclude that an image-based prediction model using 3D-CNN could be improved by even a conservatively generated mask, rather than overly trusting an unguided, blind 3D-CNN. A blind CNN may classify accurately enough, while its attention may really be focused on a remote region within 3D images. On the other hand, only using a conservatively segmented region may not be as good for classification as using full images but forcing the model's attention toward the known regions of interest.

Molecular Insights in Transmission of Cancer From an Organ Donor to Four Transplant Recipients.

Organ donors are systematically screened for infection, whereas screening for malignancy is less rigorous. The true incidence of donor-transmitted malignancies is unknown due to a lack of universal tumor testing in the posttransplant setting. Donor-transmitted malignancy may occur even when not suspected based on donor or recipient factors, including age and time to cancer diagnosis. We describe the detection of a gastrointestinal adenocarcinoma transmitted from a young donor to 4 transplant recipients. Multidimensional histopathologic and genomic profiling showed a CDH1 mutation and MET amplification, consistent with gastric origin. At the time of writing, one patient in this series remains alive and without evidence of cancer after prompt organ explant after cancer was reported in other recipients. Because identification of a donor-derived malignancy changes management, our recommendation is to routinely perform short tandem repeat testing (or a comparable assay) immediately upon diagnosis of cancer in any organ transplant recipient. Routine testing for a donor-origin cancer and centralized reporting of outcomes are necessary to establish a robust evidence base for the future development of clinical practice guidelines.

Nivolumab in patients with advanced hepatocellular carcinoma and Child-Pugh class B cirrhosis: Safety and clinical outcomes in a retrospective case series.

BACKGROUND: Nivolumab demonstrated durable responses and safety in patients with hepatocellular carcinoma (HCC) with Child-Pugh class A cirrhosis in the CheckMate 040 trial, with rates of hepatotoxicity that were similar to those of non-HCC populations. To the authors' knowledge, the safety and efficacy of nivolumab has not been established in patients with Child-Pugh class B (CPB) cirrhosis, a population with limited therapeutic options and a poor prognosis. METHODS: The authors conducted a retrospective case series of patients with advanced HCC and CPB cirrhosis who were treated with nivolumab and enrolled in the University of California at San Francisco Hepatobiliary Tissue Bank and Registry. Safety endpoints included rates of grade ≥3 adverse events (AEs) (graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.03]) and serious AEs, immune-related AEs (irAE), steroid requirement, and discontinuation. Efficacy endpoints included time on treatment, the objective response rate according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, overall survival, and progression-free survival. RESULTS: A total of 18 patients were included, with 72% of them (13 of 18 patients) previously treated with sorafenib. The majority of patients (94%; 17 of 18 patients) experienced a grade ≥3 AE, with treatment-related grade ≥3 AEs reported in 28% of patients (5 of 18 patients). irAEs were reported to occur in approximately 50% of patients (9 of 18 patients), and 28% (5 of 18 patients) required steroids. Treatment-related AEs required discontinuation in 4 patients (22%). The median time on treatment was 2.3 months (95% CI, 1.9 months to upper bound not estimable). The objective response rate was 17% (3 of 18 patients), including 2 partial responses and 1 complete response. The median overall survival from the time of nivolumab initiation was 5.9 months (95% CI, 3 months to upper bound not estimable), with a median progression-free survival of 1.6 months (95% CI, 1.4-3.5 months). CONCLUSIONS: Patients with CPB HCC experienced high rates of AEs, although the frequency of irAEs was similar to that of patients with Child-Pugh class A HCC in the CheckMate 040 trial. A subset of patients experienced prolonged tumor responses. Nivolumab warrants further study in patients with CPB HCC.

A Deep Learning Model to Predict a Diagnosis of Alzheimer Disease by Using 18F-FDG PET of the Brain.

Purpose To develop and validate a deep learning algorithm that predicts the final diagnosis of Alzheimer disease (AD), mild cognitive impairment, or neither at fluorine 18 (18F) fluorodeoxyglucose (FDG) PET of the brain and compare its performance to that of radiologic readers. Materials and Methods Prospective 18F-FDG PET brain images from the Alzheimer's Disease Neuroimaging Initiative (ADNI) (2109 imaging studies from 2005 to 2017, 1002 patients) and retrospective independent test set (40 imaging studies from 2006 to 2016, 40 patients) were collected. Final clinical diagnosis at follow-up was recorded. Convolutional neural network of InceptionV3 architecture was trained on 90% of ADNI data set and tested on the remaining 10%, as well as the independent test set, with performance compared to radiologic readers. Model was analyzed with sensitivity, specificity, receiver operating characteristic (ROC), saliency map, and t-distributed stochastic neighbor embedding. Results The algorithm achieved area under the ROC curve of 0.98 (95% confidence interval: 0.94, 1.00) when evaluated on predicting the final clinical diagnosis of AD in the independent test set (82% specificity at 100% sensitivity), an average of 75.8 months prior to the final diagnosis, which in ROC space outperformed reader performance (57% [four of seven] sensitivity, 91% [30 of 33] specificity; P < .05). Saliency map demonstrated attention to known areas of interest but with focus on the entire brain. Conclusion By using fluorine 18 fluorodeoxyglucose PET of the brain, a deep learning algorithm developed for early prediction of Alzheimer disease achieved 82% specificity at 100% sensitivity, an average of 75.8 months prior to the final diagnosis. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Larvie in this issue.

Distinguishing Tumor From Bland Portal Vein Thrombus in Liver Transplant Candidates With Hepatocellular Carcinoma: the A-VENA Criteria.

Differentiating tumor versus bland portal vein thrombosis (PVT) is essential in determining liver transplantation (LT) candidacy for patients with hepatocellular carcinoma (HCC). We aimed to evaluate radiographic and clinical features that could noninvasively distinguish tumor PVT from bland PVT in HCC patients. Of 467 patients with HCC listed for LT from 2004 to 2011, 59 (12.6%) had PVT and 12 of 59 (20.3%) were deemed malignant. When comparing tumor versus bland PVT, thrombus enhancement was seen in 100% versus 8.5%; venous expansion was seen in 91.7% versus 10.6%; neovascularity was seen in 58.3% versus 2.1%; and being adjacent to HCC or prior treatment site was seen in 100% versus 21.3% (all P < 0.001). Combining these 4 imaging characteristics with alpha-fetoprotein (AFP) >1000 ng/dL, the presence of ≥3 criteria best characterized tumor PVT with 100% sensitivity, 93.6% specificity, 80% positive predictive value, and 100% negative predictive value. No LT recipients with presumed bland PVT had macrovascular invasion on explant. There were no differences in post-LT survival or HCC recurrence with bland PVT versus no PVT. In conclusion, we proposed noninvasive criteria that could accurately differentiate tumor PVT from bland PVT called A-VENA, which is based on the presence of ≥3 of the following: AFP >1000 ng/dL; venous expansion; thrombus enhancement; neovascularity; and adjacent to HCC. Use of the A-VENA criteria can assist in standardizing the evaluation of PVT in patients with HCC being considered for LT.

Comparison of Positive Oral Contrast Agents for Abdominopelvic CT.

OBJECTIVE. The objective of our study was to compare the quality of bowel opacification from three different positive oral contrast agents-barium sulfate, diatrizoate, and iohexol-at abdominopelvic CT. MATERIALS AND METHODS. Abdominopelvic CT examinations with three different oral contrast agents (each contrast agent: n = 300 patients) of 900 patients were retrospectively evaluated by two independent readers. For four segments of the gastrointestinal tract (i.e., the stomach, jejunum, ileum, and colon), readers recorded qualitative data (grade of nonuniform lumen opacification, types of inhomogeneous opacifications, presence of artifacts, and distribution of contrast agent) and quantitative data (CT attenuation of lumen [in Hounsfield units]). The results were compared among the three contrast agents using the Mann-Whitney U test and repeated-measures ANOVA with a post hoc Bonferroni correction. RESULTS. Fewer artifacts were detected with iohexol (4.3%) as the oral contrast agent than with diatrizoate (13.0%) and barium sulfate (14.3%) (each, p < 0.05). Barium showed a greater frequency of bowel lumen heterogeneity (388/831 segments, 47%) than iohexol (155/679, 23%) and diatrizoate (185/763, 24% segments) (p < 0.001). Barium showed higher CT attenuation than iohexol and diatrizoate in the stomach but lower CT attenuation in the ileum (each, p < 0.05). CONCLUSION. The frequency of inhomogeneous bowel opacification was lower for iohexol than for diatrizoate or barium sulfate. Barium showed the highest frequency of bowel lumen heterogeneity. The iodinated agents showed greater increases in mean CT attenuation from the proximal bowel segments to the distal bowel segments than barium sulfate.

Single-Center Prospective Evaluation of 68Ga-PSMA-11 PET in Biochemical Recurrence of Prostate Cancer.

OBJECTIVE. The purpose of this study was to determine the diagnostic accuracy of 68Ga-labeled prostate-specific membrane antigen 11 (PSMA-11) PET for disease detection in patients with prostate cancer who have biochemically recurrent disease after radiation therapy or prostatectomy. SUBJECTS AND METHODS. One hundred fifty patients underwent 68Ga-PSMA-11 PET/CT or PET/MRI, and the images were interpreted by two blinded board-certified radiologists. Each reader evaluated for the presence or absence of PSMA-positive disease within the prostate bed, pelvic lymph nodes, bones, and soft tissues (extrapelvic lymph nodes and visceral structures). The presence or absence of disease was confirmed by histopathologic analysis if available. For patients who did not have pathologic analysis, a composite of imaging and clinical follow-up was used as the reference standard. RESULTS. The median prostate-specific antigen level was 2.1 ng/mL. Forty-three patients had pathologic correlation, and for 29 patients a composite of imaging and follow-up was used to determine the presence or absence of disease. With substantial to almost perfect interreader reliability by region (κ = 0.78-0.87), 68Ga-PSMA-11 PET had high sensitivity per region (up to 100%) and per patient (up to 89.8%). It also had high positive predictive value per region (up to 100%) and per patient (up to 91.5%). Sensitivity was highest for bone metastases and lowest for soft-tissue metastases. Positive predictive value was highest for bone metastases and lowest for prostate bed recurrence. CONCLUSION. Gallium-68-labeled PSMA-11 PET is sensitive for prostate cancer metastases in patients with biochemically recurrent prostate cancer. It has high positive predictive value and substantial to almost perfect interrater reliability.

Hybrid Capture-Based Tumor Sequencing and Copy Number Analysis to Confirm Origin of Metachronous Metastases in BRCA1-Mutant Cholangiocarcinoma Harboring a Novel YWHAZ-BRAF Fusion.

Biliary tract cancers such as cholangiocarcinoma represent a heterogeneous group of cancers that can be difficult to diagnose. Recent comprehensive genomic analyses in large cholangiocarcinoma cohorts have defined important molecular subgroups within cholangiocarcinoma that may relate to anatomic location and etiology [1], [2], [3], [4] and may predict responsiveness to targeted therapies in development [5], [6], [7]. These emerging data highlight the potential for tumor genomics to inform diagnosis and treatment options in this challenging tumor type. We report the case of a patient with a germline BRCA1 mutation who presented with a cholangiocarcinoma driven by the novel YWHAZ-BRAF fusion. Hybrid capture-based DNA sequencing and copy number analysis performed as part of clinical care demonstrated that two later-occurring tumors were clonally derived from the primary cholangiocarcinoma rather than distinct new primaries, revealing an unusual pattern of late metachronous metastasis. We discuss the clinical significance of these genetic alterations and their relevance to therapeutic strategies. KEY POINTS: Hybrid capture-based next-generation DNA sequencing assays can provide diagnostic clarity in patients with unusual patterns of metastasis and recurrence in which the pathologic diagnosis is ambiguous.To our knowledge, this is the first reported case of a YWHAZ-BRAF fusion in pancreaticobiliary cancer, and a very rare case of cholangiocarcinoma in the setting of a germline BRCA1 mutation.The patient's BRCA1 mutation and YWHAZ-BRAF fusion constitute potential targets for future therapy.

Impact of Lesion Visibility on Transrectal Ultrasound on the Prediction of Clinically Significant Prostate Cancer (Gleason Score 3 + 4 or Greater) with Transrectal Ultrasound-Magnetic Resonance Imaging Fusion Biopsy.

PURPOSE: The purpose of this study was to estimate the impact of lesion visibility with transrectal ultrasound on the prediction of clinically significant prostate cancer with transrectal ultrasound-magnetic resonance imaging fusion biopsy. MATERIALS AND METHODS: This HIPAA (Health Insurance Portability and Accountability Act) compliant, institutional review board approved, retrospective study was performed in 178 men who were 64.7 years old with prostate specific antigen 8.9 ng/ml. They underwent transrectal ultrasound-magnetic resonance imaging fusion biopsy from January 2013 to September 2016. Visible lesions on magnetic resonance imaging were assigned a PI-RADS™ (Prostate Imaging Reporting and Data System), version 2 score of 3 or greater. Transrectal ultrasound was positive when a hypoechoic lesion was identified. We used a 3-level, mixed effects logistic regression model to determine how transrectal ultrasound-magnetic resonance imaging concordance predicted the presence of clinically significant prostate cancer. The diagnostic performance of the 2 methods was estimated using ROC curves. RESULTS: A total of 1,331 sextants were targeted by transrectal ultrasound-magnetic resonance imaging fusion or systematic biopsies, of which 1,037 were negative, 183 were Gleason score 3 + 3 and 111 were Gleason score 3 + 4 or greater. Clinically significant prostate cancer was diagnosed by transrectal ultrasound and magnetic resonance imaging alone at 20.5% and 19.7% of these locations, respectively. Men with positive imaging had higher odds of clinically significant prostate cancer than men without visible lesions regardless of modality (transrectal ultrasound OR 14.75, 95% CI 5.22-41.69, magnetic resonance imaging OR 12.27, 95% CI 6.39-23.58 and the 2 modalities OR 28.68, 95% CI 14.45-56.89, all p <0.001). The ROC AUC to detect clinically significant prostate cancer using the 2 methods (0.85, 95% CI 0.81-0.89) was statistically greater than that of transrectal ultrasound alone (0.80, 95% CI 0.76-0.85, p = 0.001) and magnetic resonance imaging alone (0.83, 95% CI 0.79-0.87, p = 0.04). The sensitivity and specificity of transrectal ultrasound were 42.3% and 91.6%, and the sensitivity and specificity of magnetic resonance imaging were 62.2% and 84.1%, respectively. CONCLUSIONS: Lesion visibility on magnetic resonance imaging or transrectal ultrasound denotes a similar probability of clinically significant prostate cancer. This probability is greater when each examination is positive.

Early Response Assessment in Pancreatic Ductal Adenocarcinoma Through Integrated PET/MRI.

OBJECTIVE: The purpose of this study is to investigate early changes in 18F-FDG PET/MRI metrics after treatment in patients with advanced pancreatic ductal adenocarcinoma (PDAC) and to correlate those changes with eventual tumor response at standard-of-care CT. SUBJECTS AND METHODS: Thirteen patients with advanced PDAC underwent integrated FDG PET/MRI before and 4 weeks after treatment initiation. Patients were classified as responders or nonresponders according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 at subsequent CT performed 8-12 weeks after treatment initiation. Changes in the primary tumor's maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) determined at PET and apparent diffusion coefficient (ADC) determined at DWI at 4 weeks were compared between responders and nonresponders. RESULTS: Seven patients had a partial response according to RECIST, and six did not. Responders displayed significantly greater decreases in MTV (p = 0.003) and TLG (p = 0.006) in the primary pancreatic tumor at 4 weeks. Responders also displayed a greater increase in the mean (p = 0.004) and minimum (p = 0.024) ADC of the primary tumors. Tumor size change at 4 weeks was not significantly different between responders and nonresponders (p = 0.11). PET responders enjoyed longer progression-free survival (PFS) (p = 0.0004) and overall survival (OS) (p = 0.013) than did nonresponders, using either a 60% reduction in MTV or 65% reduction in TLG as a threshold. MRI responders had significantly longer PFS (p = 0.0002) and OS (p = 0.027) than did nonresponders, using a 20% increase in either mean or minimum ADC as a threshold. CONCLUSION: Integrated PET/MRI can provide early response assessment in patients with advanced PDAC, thus potentially allowing early treatment adaptation in nonresponders.

Imaging findings of concealed intra-amniotic hemorrhage in the setting of placenta previa and placenta accreta spectrum disorder.

Placental abruption is an important cause of feto-maternal hemorrhage, with significant impact on both fetal and maternal mortality. In most cases, it presents with abdominal pain and vaginal bleeding. However, vaginal bleeding may be absent with concealed intra-amniotic hemorrhage, as in cases with placenta previa, hence confounding this diagnosis. In such cases, imaging studies may be obtained to evaluate for abdominal pain in pregnancy; hence, radiologists should be aware of the ultrasound and magnetic resonance (MR) imaging appearance of intra-amniotic hemorrhage. This includes presence of markedly echogenic amniotic fluid on US. Hemorrhage signal intensity on MR imaging varies with the duration of bleeding. In acute to subacute cases, it will present as T1 isointense and T2 hypointense amniotic fluid. This case is the first report of MR imaging findings of acute concealed intra-amniotic hemorrhage.

Effect of Time-of-Flight and Regularized Reconstructions on Quantitative Measurements and Qualitative Assessments in Newly Diagnosed Prostate Cancer With 18F-Fluorocholine Dual Time Point PET/MRI.

Recent technical advances in positron emission tomography/magnetic resonance imaging (PET/MRI) technology allow much improved time-of-flight (TOF) and regularized iterative PET reconstruction regularized iterative reconstruction (RIR) algorithms. We evaluated the effect of TOF and RIR on standardized uptake values (maximum and peak SUV [SUVmax and SUVpeak]) and their metabolic tumor volume dependencies and visual image quality for 18F-fluorocholine PET/MRI in patients with newly diagnosed prostate cancer. Fourteen patients were administered with 3 MBq/kg of 18F-fluorocholine and scanned dynamically for 30 minutes. Positron emission tomography images were divided to early and late time points (1-6 minutes summed and 7-30 minutes summed). The values of the different SUVs were documented for dominant PET-avid lesions, and metabolic tumor volume was estimated using a 50% isocontour and SUV threshold of 2.5. Image quality was assessed via visual acuity scoring (VAS). We found that incorporation of TOF or RIR increased lesion SUVs. The lesion to background ratio was not improved by TOF reconstruction, while RIR improved the lesion to background ratio significantly ( P < .05). The values of the different VAS were all significantly higher ( P < .05) for RIR images over TOF, RIR over non-TOF, and TOF over non-TOF. In conclusion, our data indicate that TOF or RIR should be incorporated into current protocols when available.

Imaging Hepatocellular Carcinoma With 68Ga-Citrate PET: First Clinical Experience.

While cross-sectional imaging with computed tomography (CT) and magnetic resonance imaging is the primary method for diagnosing hepatocellular carcinoma (HCC), they provide little biological insight into this molecularly heterogeneous disease. Nuclear imaging tools that can detect molecular subsets of tumors could greatly improve diagnosis and management of HCC. To this end, we conducted a patient study to determine whether HCC can be resolved using 68Ga-citrate positron emission tomography (PET). One patient with recurrent HCC was injected with 300 MBq of 68Ga-citrate and imaged with PET/CT 249 minutes post injection. Four (28%) of 14 hepatic lesions were avid for 68Ga-citrate. One extrahepatic lesion was not PET avid. The average maximum standardized uptake value (SUVmax) for the lesions was 7.2 (range: 6.2-8.4), while the SUVmax of the normal liver parenchyma was 4.7 and blood pool was 5.7. The avid lesions were not significantly larger than the quiescent lesions, and a prior contrast CT showed uniform enhancement among the lesions, suggesting that tumor signals are due to specific binding of the radiotracer to the transferrin receptor, rather than enhanced vascularity in the tumor microenvironment. Further studies are required in a larger patient cohort to verify the molecular basis of radiotracer uptake and the clinical utility of this tool.

Quantitative Evaluation of Atlas-based Attenuation Correction for Brain PET in an Integrated Time-of-Flight PET/MR Imaging System.

Purpose To assess the patient-dependent accuracy of atlas-based attenuation correction (ATAC) for brain positron emission tomography (PET) in an integrated time-of-flight (TOF) PET/magnetic resonance (MR) imaging system. Materials and Methods Thirty recruited patients provided informed consent in this institutional review board-approved study. All patients underwent whole-body fluorodeoxyglucose PET/computed tomography (CT) followed by TOF PET/MR imaging. With use of TOF PET data, PET images were reconstructed with four different attenuation correction (AC) methods: PET with patient CT-based AC (CTAC), PET with ATAC (air and bone from an atlas), PET with ATACpatientBone (air and tissue from the atlas with patient bone), and PET with ATACboneless (air and tissue from the atlas without bone). For quantitative evaluation, PET mean activity concentration values were measured in 14 1-mL volumes of interest (VOIs) distributed throughout the brain and statistical significance was tested with a paired t test. Results The mean overall difference (±standard deviation) of PET with ATAC compared with PET with CTAC was -0.69 kBq/mL ± 0.60 (-4.0% ± 3.2) (P < .001). The results were patient dependent (range, -9.3% to 0.57%) and VOI dependent (range, -5.9 to -2.2). In addition, when bone was not included for AC, the overall difference of PET with ATACboneless (-9.4% ± 3.7) was significantly worse than that of PET with ATAC (-4.0% ± 3.2) (P < .001). Finally, when patient bone was used for AC instead of atlas bone, the overall difference of PET with ATACpatientBone (-1.5% ± 1.5) improved over that of PET with ATAC (-4.0% ± 3.2) (P < .001). Conclusion ATAC in PET/MR imaging achieves similar quantification accuracy to that from CTAC by means of atlas-based bone compensation. However, patient-specific anatomic differences from the atlas causes bone attenuation differences and misclassified sinuses, which result in patient-dependent performance variation of ATAC. © RSNA, 2017 Online supplemental material is available for this article.