Cross-Sectional Imaging Characteristics of Pancreatic Intraductal Oncocytic Papillary Neoplasms.

PURPOSE: Pancreatic intraductal oncocytic papillary neoplasms (IOPN) are rare precursors to pancreatic ductal adenocarcinoma. We report cross-sectional computed tomography and magnetic resonance imaging (where available) findings of pancreatic IOPNs. MATERIALS AND METHODS: Consecutive cases of pancreatic IOPNs identified on pathology between 2008 and 2020 at University of Pittsburgh and Johns Hopkins University were included in the study. Cross-sectional imaging of all patients was reviewed by two subspecialty trained abdominal radiologists. Patient demographics, cross-sectional imaging appearances and growth characteristics were evaluated. RESULTS: In this dual-center study, 14 patients with IOPNs were included. Median age was 64 years, and 64% were male. The median size of the lesions was 5.4 cm (range, 1.4-12.3 cm). All patients had either an enhancing mural nodule (93% of patients) and/or thick internal septations (29%). Thin/imperceptible outer wall was seen in 93%. Main duct was involved in 64% of the cases. Only 14% of the cases did not demonstrate abutment of the main duct. Histologic evaluation of surgical specimen showed high-grade dysplasia without invasive carcinoma in 57% and invasive carcinoma in 43% of cases. Lesions with invasive carcinoma were larger (7.1 cm vs 4.3 cm, P = 0.05) and tended to have larger mural nodule (3.7 cm vs 1.8 cm) compared with those without invasive carcinoma. CONCLUSION: Pancreatic IOPNs are rare cystic premalignant lesions, which among resected cases, are predominantly seen in middle aged men, are often large, have enhancing mural nodules and frequently harbor invasive carcinoma.

Intestinal and Multivisceral Transplantation: Indications and Surgical Techniques.

Intestinal transplantation and multivisceral transplantation are technically challenging and complex procedures mainly performed on patients with irreversible and non-medically manageable end-stage intestinal failure. Increasingly, other organs besides small intestines are included in the allograft for which the terms "composite intestinal transplantation" and "multivisceral transplantation" are used. Commonly, complex vascular reconstructions are used for these procedures. Knowledge of surgical anatomy hence is essential for accurate interpretation of postoperative imaging in these patients. This article reviews the indications and most common surgical techniques for intestinal and multivisceral transplantations.

Intestinal and Multivisceral Transplantation: Complications.

Advancements in immunosuppression protocols, surgical techniques, and postoperative care in the last few decades have improved outcomes of intestinal transplant patients. Normal immediate postoperative imaging appearance can simulate pathology. Intestinal transplant recipients are prone for several postoperative complications due to the complex surgical technique, which involves multiple anastomoses, and immunogenic nature of the allograft intestine. Imaging plays a crucial role in detection of several major complications including infectious, immunologic, vascular, gastrointestinal, pancreaticobiliary, genitourinary, and neoplastic complications. The awareness of the posttransplant anatomy and normal imaging appearances helps radiologists anticipate and accurately detect posttransplant complications.

Unconventional Strategies for Solid Organ Transplantation and Special Transplantation Scenarios.

Solid organ transplantation is the only long-term therapeutic option for patients with end-organ failure but cadaveric and living donor transplant pools are unable to meet the demand for organ transplantation. Newer techniques, innovative strategies and altruistic donors can help bridge this wide gap between the number of organ donors and recipients. Domino liver transplantation, paired organ donation, and ABO incompatible transplants are some of the ways to ensure increased transplant organ availability. Split liver transplantation and ex vivo liver resection and auto transplantation are considered surgically challenging but are being done at tertiary transplant centers.

Diagnosis of chronic pancreatitis using semi-quantitative MRI features of the pancreatic parenchyma: results from the multi-institutional MINIMAP study.

PURPOSE: To determine the diagnostic performance of parenchymal MRI features differentiating CP from controls. METHODS: This prospective study performed abdominal MRI scans at seven institutions, using 1.5 T Siemens and GE scanners, in 50 control and 51 definite CP participants, from February 2019 to May 2021. MRI parameters included the T1-weighted signal intensity ratio of the pancreas (T1 score), arterial-to-venous enhancement ratio (AVR) during venous and delayed phases, pancreas volume, and diameter. We evaluated the diagnostic performance of these parameters individually and two semi-quantitative MRI scores derived using logistic regression: SQ-MRI Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume). RESULTS: When compared to controls, CP participants showed a significantly lower mean T1 score (1.11 vs. 1.29), AVR venous (0.86 vs. 1.45), AVR delayed (1.07 vs. 1.57), volume (54.97 vs. 80.00 ml), and diameter of the head (2.05 vs. 2.39 cm), body (2.25 vs. 2.58 cm), and tail (1.98 vs. 2.51 cm) (p < 0.05 for all). AUCs for these individual MR parameters ranged from 0.66 to 0.79, while AUCs for the SQ-MRI scores were 0.82 and 0.81 for Model A (T1 score, AVR venous, and tail diameter) and Model B (T1 score, AVR venous, and volume), respectively. After propensity-matching adjustments for covariates, AUCs for Models A and B of the SQ-MRI scores increased to 0.92 and 0.93, respectively. CONCLUSION: Semi-quantitative parameters of the pancreatic parenchyma, including T1 score, enhancement ratio, pancreas volume, diameter and multi-parametric models combining these parameters are helpful in diagnosis of CP. Longitudinal analyses including more extensive population are warranted to develop new diagnostic criteria for CP.

Mesotheliomas and Benign Mesothelial Tumors: Update on Pathologic and Imaging Findings.

A diverse spectrum of benign entities and malignant neoplasms originate from the monotonous mesothelium that lines the serosal membranes of the pleural, pericardial, and peritoneal cavities. The mesothelium of myriad sites shows a common origin from the lateral plate mesoderm; primary mesothelial tumors thus demonstrate similar pathogenesis, imaging findings, and treatment options. Significant changes have been made in the 2021 World Health Organization (WHO) classification schemata of the pleural and pericardial tumors on the basis of recent advances in pathology and genetics. While malignant mesotheliomas are biologically aggressive malignancies that occur primarily in patients exposed to asbestos with attendant poor survival rates, well-differentiated papillary mesothelial tumors and adenomatoid tumors charter a benign clinical course with an excellent prognosis. Mesothelioma in situ is a newly characterized entity represented by recurrent unexplained pleural effusions without any identifiable mass at imaging or thoracoscopy. Immunohistochemical markers based on BAP1, MTAP, CDKN2A, and TRAF7 gene mutations help differentiate diffuse mesotheliomas from benign mesothelial proliferations and localized mesotheliomas. Cross-sectional imaging modalities, including US, CT, MRI, and fluorine 18-fluorodeoxyglucose (FDG) PET/CT, permit diagnosis and play a major role in staging and assessing surgical resectability. Imaging studies are invaluable in providing noninvasive and quantitative assessment of tumor response in patients with unresectable disease. Owing to significant overlap in patient characteristics and pathomorphology, accurate diagnosis based on advanced histopathology techniques and genetic abnormalities is imperative for optimal management and prognostication. While patients with nonepithelioid pleural mesotheliomas benefit from immunotherapy, novel targeted therapies for CDKN2A-, NF2-, and BAP1-altered mesotheliomas are under consideration. © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Design and Rationale for the Use of Magnetic Resonance Imaging Biomarkers to Predict Diabetes After Acute Pancreatitis in the Diabetes RElated to Acute Pancreatitis and Its Mechanisms Study: From the Type 1 Diabetes in Acute Pancreatitis Consortium.

ABSTRACT: This core component of the Diabetes RElated to Acute pancreatitis and its Mechanisms (DREAM) study will examine the hypothesis that advanced magnetic resonance imaging (MRI) techniques can reflect underlying pathophysiologic changes and provide imaging biomarkers that predict diabetes mellitus (DM) after acute pancreatitis (AP). A subset of participants in the DREAM study will enroll and undergo serial MRI examinations using a specific research protocol. The aim of the study is to differentiate at-risk individuals from those who remain euglycemic by identifying parenchymal features after AP. Performing longitudinal MRI will enable us to observe and understand the natural history of post-AP DM. We will compare MRI parameters obtained by interrogating tissue properties in euglycemic, prediabetic, and incident diabetes subjects and correlate them with metabolic, genetic, and immunological phenotypes. Differentiating imaging parameters will be combined to develop a quantitative composite risk score. This composite risk score will potentially have the ability to monitor the risk of DM in clinical practice or trials. We will use artificial intelligence, specifically deep learning, algorithms to optimize the predictive ability of MRI. In addition to the research MRI, the DREAM study will also correlate clinical computed tomography and MRI scans with DM development.

Quantitative MRI of chronic pancreatitis: results from a multi-institutional prospective study, magnetic resonance imaging as a non-invasive method for assessment of pancreatic fibrosis (MINIMAP).

PURPOSE: To determine if quantitative MRI techniques can be helpful to evaluate chronic pancreatitis (CP) in a setting of multi-institutional study. METHODS: This study included a subgroup of participants (n = 101) enrolled in the Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) study (NCT03099850) from February 2019 to May 2021. MRI was performed on 1.5 T using Siemens and GE scanners at seven clinical centers across the USA. Quantitative MRI parameters of the pancreas included T1 relaxation time, extracellular volume (ECV) fraction, apparent diffusion coefficient (ADC), and fat signal fraction. We report the diagnostic performance and mean values within the control (n = 50) and CP (n = 51) groups. The T1, ECV and fat signal fraction were combined to generate the quantitative MRI score (Q-MRI). RESULTS: There was significantly higher T1 relaxation time; mean 669 ms (± 171) vs. 593 ms (± 82) (p = 0.006), ECV fraction; 40.2% (± 14.7) vs. 30.3% (± 11.9) (p < 0.001), and pancreatic fat signal fraction; 12.2% (± 5.5) vs. 8.2% (± 4.4) (p < 0.001) in the CP group compared to controls. The ADC was similar between groups (p = 0.45). The AUCs for the T1, ECV, and pancreatic fat signal fraction were 0.62, 0.72, and 0.73, respectively. The composite Q-MRI score improved the diagnostic performance (cross-validated AUC: 0.76). CONCLUSION: Quantitative MR parameters evaluating the pancreatic parenchyma (T1, ECV fraction, and fat signal fraction) are helpful in the diagnosis of CP. A Q-MRI score that combines these three MR parameters improves diagnostic performance. Further studies are warranted with larger study populations including patients with acute and recurrent acute pancreatitis and longitudinal follow-ups.

Morphomolecular Classification Update on Hepatocellular Adenoma, Hepatocellular Carcinoma, and Intrahepatic Cholangiocarcinoma.

Hepatocellular adenomas (HCAs), hepatocellular carcinomas (HCCs), and intrahepatic cholangiocarcinomas (iCCAs) are a highly heterogeneous group of liver tumors with diverse pathomolecular features and prognoses. High-throughput gene sequencing techniques have allowed discovery of distinct genetic and molecular underpinnings of these tumors and identified distinct subtypes that demonstrate varied clinicobiologic behaviors, imaging findings, and complications. The combination of histopathologic findings and molecular profiling form the basis for the morphomolecular classification of liver tumors. Distinct HCA subtypes with characteristic imaging findings and complications include HNF1A-inactivated, inflammatory, ß-catenin-activated, ß-catenin-activated inflammatory, and sonic hedgehog HCAs. HCCs can be grouped into proliferative and nonproliferative subtypes. Proliferative HCCs include macrotrabecular-massive, TP53-mutated, scirrhous, clear cell, fibrolamellar, and sarcomatoid HCCs and combined HCC-cholangiocarcinoma. Steatohepatitic and ß-catenin-mutated HCCs constitute the nonproliferative subtypes. iCCAs are classified as small-duct and large-duct types on the basis of the level of bile duct involvement, with significant differences in pathogenesis, molecular signatures, imaging findings, and biologic behaviors. Cross-sectional imaging modalities, including multiphase CT and multiparametric MRI, play an essential role in diagnosis, staging, treatment response assessment, and surveillance. Select imaging phenotypes can be correlated with genetic abnormalities, and identification of surrogate imaging markers may help avoid genetic testing. Improved understanding of morphomolecular features of liver tumors has opened new areas of research in the targeted therapeutics and management guidelines. The purpose of this article is to review imaging findings of select morphomolecular subtypes of HCAs, HCCs, and iCCAs and discuss therapeutic and prognostic implications. Online supplemental material is available for this article. ©RSNA, 2022.

Standardization of MRI Screening and Reporting in Individuals With Elevated Risk of Pancreatic Ductal Adenocarcinoma: Consensus Statement of the PRECEDE Consortium.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with a dismal survival rate. Screening the general population for early detection of PDAC is not recommended, but because early detection improves survival, high-risk individuals, defined as those meeting criteria based on a family history of PDAC and/or the presence of known pathogenic germline variant genes with PDAC risk, are recommended to undergo screening with MRI and/or endoscopic ultrasound at regular intervals. The Pancreatic Cancer Early Detection (PRECEDE) Consortium was formed in 2018 and is composed of gastroenterologists, geneticists, pancreatic surgeons, radiologists, statisticians, and researchers from 40 sites in North America, Europe, and Asia. The overarching goal of the PRECEDE Consortium is to facilitate earlier diagnosis of PDAC for high-risk individuals to increase survival of the disease. A standardized MRI protocol and reporting template are needed to enhance the quality of screening examinations, improve consistency of clinical management, and facilitate multiinstitutional research. We present a consensus statement to standardize MRI screening and reporting for individuals with elevated risk of pancreatic cancer.

T1 signal intensity ratio of the pancreas as an imaging biomarker for the staging of chronic pancreatitis.

PURPOSE: Our purpose was to validate the T1 SIR (T1 score) as an imaging biomarker for the staging of CP in a large, multi-institutional, prospective study. METHODS: The prospective study population included 820 participants enrolled in the PROCEED study from nine clinical centers between June 2017 and December 2021. A radiologist at each institution used a standardized method to measure the T1 signal intensity of the pancreas and the reference organs (spleen, paraspinal muscle, liver), which was used to derive respective T1 scores. Participants were stratified according to the seven mechanistic stages of chronic pancreatitis (MSCP 0-6) based on their clinical history, MRCP, and CT findings. RESULTS: The mean pancreas-to-spleen T1 score was 1.30 in participants with chronic abdominal pain, 1.22 in those with acute or recurrent acute pancreatitis, and 1.03 in definite CP. After adjusting for covariates, we observed a linear, progressive decline in the pancreas-to-spleen T1 score with increasing MSCP from 0 to 6. The mean pancreas-to-spleen T1 scores were 1.34 (MSCP 0), 1.27 (MSCP 1), 1.21 (MSCP 2), 1.16 (MSCP 3), 1.18 (MSCP 4), 1.12 (MSCP 5), and 1.05 (MSCP 6) (p < 0.0001). The pancreas-to-liver and pancreas-to-muscle T1 scores showed less linear trends and wider confidence intervals. CONCLUSION: The T1 score calculated by SIR of the pancreas-to-spleen shows a negative linear correlation with the progression of chronic pancreatitis. It holds promise as a practical imaging biomarker in evaluating disease severity in clinical research and practice.

Gastrointestinal Manifestations of Immunodeficiency: Imaging Spectrum.

There is a wide spectrum of hereditary and acquired immunodeficiency disorders that are characterized by specific abnormalities involving a plethora of humoral, cellular, and phagocytic immunologic pathways. These include distinctive primary immunodeficiency syndromes due to characteristic genetic defects and secondary immunodeficiency syndromes, such as AIDS from HIV infection and therapy-related immunosuppression in patients with cancers or a solid organ or stem cell transplant. The gut mucosa and gut-associated lymphoid tissue (the largest lymphoid organ in the body), along with diverse commensal microbiota, play complex and critical roles in development and modulation of the immune system. Thus, myriad gastrointestinal (GI) symptoms are common in immunocompromised patients and may be due to inflammatory conditions (graft versus host disease, neutropenic enterocolitis, or HIV-related proctocolitis), opportunistic infections (viral, bacterial, fungal, or protozoal), or malignancies (Kaposi sarcoma, lymphoma, posttransplant lymphoproliferative disorder, or anal cancer). GI tract involvement in immunodeficient patients contributes to significant morbidity and mortality. Along with endoscopy and histopathologic evaluation, imaging plays an integral role in detection, localization, characterization, and distinction of GI tract manifestations of various immunodeficiency syndromes and their complications. Select disorders demonstrate characteristic findings at fluoroscopy, CT, US, and MRI that permit timely and accurate diagnosis. While neutropenic enterocolitis affects the terminal ileum and right colon and occurs in patients receiving chemotherapy for hematologic malignancies, Kaposi sarcoma commonly manifests as bull's-eye lesions in the stomach and duodenum. Imaging is invaluable in treatment follow-up and long-term surveillance as well. Online supplemental material is available for this article. ©RSNA, 2022.

Tumor Size Differences Between Preoperative Endoscopic Ultrasound and Postoperative Pathology for Neoadjuvant-Treated Pancreatic Ductal Adenocarcinoma Predict Patient Outcome.

BACKGROUND & AIMS: The assessment of therapeutic response after neoadjuvant treatment and pancreatectomy for pancreatic ductal adenocarcinoma (PDAC) has been an ongoing challenge. Several limitations have been encountered when employing current grading systems for residual tumor. Considering endoscopic ultrasound (EUS) represents a sensitive imaging technique for PDAC, differences in tumor size between preoperative EUS and postoperative pathology after neoadjuvant therapy were hypothesized to represent an improved marker of treatment response. METHODS: For 340 treatment-naïve and 365 neoadjuvant-treated PDACs, EUS and pathologic findings were analyzed and correlated with patient overall survival (OS). A separate group of 200 neoadjuvant-treated PDACs served as a validation cohort for further analysis. RESULTS: Among treatment-naïve PDACs, there was a moderate concordance between EUS imaging and postoperative pathology for tumor size (r = 0.726, P < .001) and AJCC 8th edition T-stage (r = 0.586, P < .001). In the setting of neoadjuvant therapy, a decrease in T-stage correlated with improved 3-year OS rates (50% vs 31%, P < .001). Through recursive partitioning, a cutoff of ≥47% tumor size reduction was also found to be associated with improved OS (67% vs 32%, P < .001). Improved OS using a ≥47% threshold was validated using a separate cohort of neoadjuvant-treated PDACs (72% vs 36%, P < .001). By multivariate analysis, a reduction in tumor size by ≥47% was an independent prognostic factor for improved OS (P = .007). CONCLUSIONS: The difference in tumor size between preoperative EUS imaging and postoperative pathology among neoadjuvant-treated PDAC patients is an important prognostic indicator and may guide subsequent chemotherapeutic management.

Noninvasive Imaging Prior to Biliary Interventions.

Noninvasive imaging is a crucial and initial step in the diagnostic algorithm of patients with suspected biliary pathology and directs the subsequent diagnostic and therapeutic workup, including the endoluminal and percutaneous biliary interventions. This article reviews the current noninvasive imaging methods for the evaluation of biliary system and further discusses their roles in the diagnostic workup of different biliary disease.

Pancreatic-Portal Vein Fistula: a Rare Diagnosis with Wide-Ranging Complications-13-Year Experience of a Pancreas Center of Excellence.

PURPOSE: To determine factors affecting mortality, and long-term patency of portal vein, in patients with pancreatic-portal vein fistula (PPVF). METHODS: Consecutive cases of PPVF at the University of Pittsburgh Medical Center from 2008 to 2020 were retrospectively identified. Clinical history, imaging studies, management strategies, complications, and long-term outcomes were analyzed. RESULTS: Fourteen patients, representing the largest PPVF cohort reported to date (mean age 58.6 years, 64.3% women, median follow-up 10 months [1-98 months]) were identified. Underlying chronic pancreatitis was seen in 9 (64.3%) patients, while 5 (35.7%) developed PPVF with first attack of acute pancreatitis. PPVF involved proximal main portal vein (MPV) in 10 (78.6%) patients. Of the 5 patients (35.7%) who died, all had occlusive (n=4) or near-occlusive (n=1) PPVF-associated filling defect (FD) in the MPV. Conversely, 7 of 9 survivors (87.5%) had subocclusive FD and patent MPV. In patients with sepsis (n=5), 1 underwent surgical necrosectomy and survived, while 3 of 4 (75%) patients without debridement died. CONCLUSION: Occlusive/near-occlusive PPVF-associated MPV FD, and sepsis, are associated with high mortality rates, while subocclusive MPV FD is associated with survival and long-term MPV patency. PPVF is a potentially life-threatening, and possibly under-diagnosed, entity that warrants early clinical suspicion for timely diagnosis, to facilitate optimal management.

Role of standardized reporting and novel imaging markers in chronic pancreatitis.

PURPOSE OF REVIEW: This article reviews recent efforts about standardized imaging features and reporting of chronic pancreatitis and recently published or ongoing imaging studies, which aim to establish novel imaging biomarkers for detection of parenchymal changes seen in chronic pancreatitis. RECENT FINDINGS: New novel MRI techniques are being developed to increase the diagnostic yield of chronic pancreatitis specifically in the early stage. T1 relaxation time, T1 signal intensity ratio and extracellular volume fraction offer potential advantages over conventional cross-sectional imaging, including simplicity of analysis and more objective interpretation of observations allowing population-based comparisons. In addition, standardized definitions and reporting guidelines for chronic pancreatitis based on available evidence and expert consensus have been proposed. These new imaging biomarkers and reporting guidelines are being validated for prognostic/therapeutic assessment of adult patients participating in longitudinal studies of The Consortium for the Study of Chronic Pancreatitis, Diabetes and Pancreatic Cancer. SUMMARY: New imaging biomarkers derived from novel MRI sequences promise a new chapter for diagnosis and severity assessment of chronic pancreatitis; a cross-sectional imaging-based diagnostic criteria for chronic pancreatitis combining ductal and parenchymal findings. Standardized imaging findings and reporting guidelines of chronic pancreatitis would enhance longitudinal assessment of disease severity in clinical trials and improve communication between radiologists and pancreatologists in clinical practice.

Post-operative imaging anatomy in liver transplantation.

The article describes and illustrates the surgical techniques and the post-operative imaging anatomy in liver transplantation. Special attention is paid to the variant vascular and biliary anatomy that are important for surgical planning. Considering the ever-growing number of liver transplants performed and the key role that imaging plays in the pre-operative planning and post-operative assessment, it is important for the radiologist to be familiar with the surgical techniques and the normal post-operative appearance in these patients.

Groove pancreatitis has a spectrum of severity and can be managed conservatively.

BACKGROUND & AIMS: The natural history of groove pancreatitis is incompletely characterized. Published literature suggests a high rate of surgery. We describe the short- and long-term outcomes in a cohort of patients with groove pancreatitis treated at our institution. METHODS: Medical records of patients hospitalized in the University of Pittsburgh Medical Center system from 2000 to 2014 and diagnosed with groove pancreatitis based on imaging were retrospectively reviewed. Clinical presentation and outcomes during index admission and follow-up were recorded. RESULTS: Forty-eight patients with groove pancreatitis were identified (mean age 53.2 years, 79% male). Seventy-one percent were alcohol abusers and an equal number were cigarette smokers. Prior histories of acute and chronic pancreatitis were noted in 30 (62.5%) and 21 (43.8%), respectively. Forty-four (91.7%) met criteria for acute pancreatitis during their index admission. Alcohol was the most common etiology (68.8%). No patient experienced organ failure. The most frequent imaging findings were fat stranding in the groove (83.3%), duodenal wall thickening (52.1%), and soft tissue mass/thickening in the groove (50%). Over a mean follow-up of 5.0 years, seven (14.6%) required a pancreas-related surgery. Patients had a high burden of pancreatitis-related readmissions (68.8%, 69.4/100 patient-years). Incident diabetes and chronic pancreatitis were diagnosed in 5 (13.9% of patients at risk) and 8 (29.6% of patients at risk) respectively. CONCLUSIONS: Groove pancreatitis has a wide spectrum of severity; most patients have mild disease. These patients have a high burden of readmissions and progression to chronic pancreatitis. A small minority requires surgical intervention.