Intraprocedural Ablation Margin Assessment by Using Ammonia Perfusion PET during FDG PET/CT-guided Liver Tumor Ablation: A Pilot Study.

Purpose To prospectively determine whether nitrogen 13 (13N) ammonia perfusion positron emission tomography (PET) during fluorine 18 fluorodeoxyglucose (FDG) PET/computed tomography (CT)-guided liver tumor ablation can be used to intraprocedurally assess ablation margins. Materials and Methods Eight patients (five women and three men; age range, 36-74 years; mean age, 57 years) were enrolled in this pilot study and underwent FDG PET/CT-guided microwave ablation of 11 FDG-avid liver metastases (mean diameter, 22 mm; range, 11-34 mm). All procedures were performed between March 2014 and December 2016. Complete ablation margin visibility and minimum ablation margin thickness were assessed by using intraprocedural 13N-ammonia perfusion PET compared with 24-hour postprocedural MR imaging by two independent blinded radiologists. Local tumor progression for each ablated tumor was assessed at follow-up imaging for 3-38 months (median, 17.6 months). Descriptive analysis was performed. Results Eleven of 11 (100%) ablation margins were fully assessable by using intraprocedural perfusion PET by both readers; six of eleven (55%) margins were fully assessable by both readers at postprocedural 24-hour MR imaging. By using perfusion PET, one tumor that had been judged by both readers to have a minimum margin of 0 mm progressed locally. No tumors judged to have a minimum margin greater than 0 mm at perfusion PET progressed locally. Conclusion 13N-ammonia perfusion PET during FDG PET/CT-guided liver tumor ablations can potentially be used to intraprocedurally assess the entire ablation margin, including the minimum margin. © RSNA, 2018.

Interreader Agreement of Prostate Imaging Reporting and Data System Version 2 Using an In-Bore MRI-Guided Prostate Biopsy Cohort: A Single Institution's Initial Experience.

OBJECTIVE: The purpose of this study is to determine the interobserver agreement of the Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) for diagnosing prostate cancer using in-bore MRI-guided prostate biopsy as the reference standard. MATERIALS AND METHODS: Fifty-nine patients underwent in-bore MRI-guided prostate biopsy between January 21, 2010, and August 21, 2013, and underwent diagnostic multiparametric MRI 6 months or less before biopsy. A single index lesion per patient was selected after retrospective review of MR images. Three fellowship-trained abdominal radiologists (with 1-11 years' experience) blinded to clinical information interpreted all studies according to PI-RADSv2. Interobserver agreement was assessed using Cohen kappa statistics. RESULTS: Thirty-eight lesions were in the peripheral zone and 21 were in the transition zone. Cancer was diagnosed in 26 patients (44%). Overall PI-RADS scores were higher for all biopsy-positive lesions (mean ± SD, 3.9 ± 1.1) than for biopsy-negative lesions (3.1 ± 1.0; p < 0.0001) and for clinically significant lesions (4.2 ± 1.0) than for clinically insignificant lesions (3.1 ± 1.0; p < 0.0001). Overall suspicion score interobserver agreement was moderate (κ = 0.45). There was moderate interobserver agreement among overall PI-RADS scores in the peripheral zone (κ = 0.46) and fair agreement in the transition zone (κ = 0.36). CONCLUSION: PI-RADSv2 scores were higher in the biopsy-positive group. PI-RADSv2 showed moderate interobserver agreement among abdominal radiologists with no prior experience using the scoring system.

Impact of a Structured Report Template on the Quality of MRI Reports for Rectal Cancer Staging.

OBJECTIVE: The purpose of this study is to assess the impact of implementing a structured report template on the quality of MRI reports for rectal cancer staging. MATERIALS AND METHODS: After excluding examinations performed after surgery or neoadjuvant therapy, we analyzed all rectal cancer staging MRI reports finalized at an academic medical center 12 months before and after an intervention consisting of implementing a structured report template integrated into the institution's speech recognition system. The primary outcome measure was the quality of rectal cancer staging MRI reports classified as optimal, satisfactory, or unsatisfactory, on the basis of the documentation of 14 quality measures predefined by a consensus of the institution's abdominal radiology subspecialists. Chi-square and t tests were used to assess differences in report quality and documentation of each discrete quality measure before and after the intervention. RESULTS: The study cohort included 106 MRI reports from 104 patients (mean age, 60 years; 58.5% male); 52 (49.1%) of the reports were completed before implementation of the structured report template. After implementation, the proportion of total reports classified as optimal or satisfactory increased from 38.5% (20/52) to 70.4% (38/54) (p = 0.0010). No reports generated before the intervention were classified as optimal, whereas 40.7% (22/54) of reports were classified as optimal after the intervention. CONCLUSION: Implementation and voluntary use of a structured report template improved the quality of MRI reports for rectal cancer staging compared with free-text format.

Radiogenomics of clear cell renal cell carcinoma: preliminary findings of The Cancer Genome Atlas-Renal Cell Carcinoma (TCGA-RCC) Imaging Research Group.

PURPOSE: To investigate associations between imaging features and mutational status of clear cell renal cell carcinoma (ccRCC). MATERIALS AND METHODS: This multi-institutional, multi-reader study included 103 patients (77 men; median age 59 years, range 34-79) with ccRCC examined with CT in 81 patients, MRI in 19, and both CT and MRI in three; images were downloaded from The Cancer Imaging Archive, an NCI-funded project for genome-mapping and analyses. Imaging features [size (mm), margin (well-defined or ill-defined), composition (solid or cystic), necrosis (for solid tumors: 0%, 1%-33%, 34%-66% or >66%), growth pattern (endophytic, <50% exophytic, or ≥50% exophytic), and calcification (present, absent, or indeterminate)] were reviewed independently by three readers blinded to mutational data. The association of imaging features with mutational status (VHL, BAP1, PBRM1, SETD2, KDM5C, and MUC4) was assessed. RESULTS: Median tumor size was 49 mm (range 14-162 mm), 73 (71%) tumors had well-defined margins, 98 (95%) tumors were solid, 95 (92%) showed presence of necrosis, 46 (45%) had ≥50% exophytic component, and 18 (19.8%) had calcification. VHL (n = 52) and PBRM1 (n = 24) were the most common mutations. BAP1 mutation was associated with ill-defined margin and presence of calcification (p = 0.02 and 0.002, respectively, Pearson's χ (2) test); MUC4 mutation was associated with an exophytic growth pattern (p = 0.002, Mann-Whitney U test). CONCLUSIONS: BAP1 mutation was associated with ill-defined tumor margins and presence of calcification; MUC4 mutation was associated with exophytic growth. Given the known prognostic implications of BAP1 and MUC4 mutations, these results support using radiogenomics to aid in prognostication and management.

Necrotizing pancreatitis: diagnosis, imaging, and intervention.

Acute necrotizing pancreatitis is a severe form of acute pancreatitis characterized by necrosis in and around the pancreas and is associated with high rates of morbidity and mortality. Although acute interstitial edematous pancreatitis is diagnosed primarily on the basis of signs, symptoms, and laboratory test findings, the diagnosis and severity assessment of acute necrotizing pancreatitis are based in large part on imaging findings. On the basis of the revised Atlanta classification system of 2012, necrotizing pancreatitis is subdivided anatomically into parenchymal, peripancreatic, and combined subtypes, and temporally into clinical early (within 1 week of onset) and late (>1 week after onset) phases. Associated collections are categorized as "acute necrotic" or "walled off" and can be sterile or infected. Imaging, primarily computed tomography and magnetic resonance imaging, plays an essential role in the diagnosis of necrotizing pancreatitis and the identification of complications, including infection, bowel and biliary obstruction, hemorrhage, pseudoaneurysm formation, and venous thrombosis. Imaging is also used to help triage patients and guide both temporizing and definitive management. A "step-up" method for the management of necrotizing pancreatitis that makes use of imaging-guided percutaneous catheter drainage of fluid collections prior to endoscopic or surgical necrosectomy has been shown to improve clinical outcomes. The authors present an algorithmic approach to the care of patients with necrotizing pancreatitis and review the use of imaging and interventional techniques in the diagnosis and management of this pathologic condition.

Computed tomography-guided percutaneous biopsy of isoattenuating focal liver lesions.

PURPOSE: The purpose of this study was to evaluate the efficacy of CT-guided percutaneous biopsy of isoattenuating liver lesions using anatomic landmarks (ALs) to guide needle placement and added value of intravenous (IV) contrast. METHODS: An interventional radiology database was reviewed to identify patients with CT-guided percutaneous biopsy of isoattenuating focal liver lesions using ALs to guide needle placement. The cohort was further divided into two groups: lesions biopsied using ALs only and lesions biopsied using ALs and intravenous contrast (AL+IV). Pathology results or follow-up imaging served as reference standard. Sensitivity and accuracy were calculated, Student's t test and Fisher's exact test were used for statistical comparison between the two groups. RESULTS: Between January 2000 and December 2011, CT-guided percutaneous biopsy of 133 isoattenuating focal liver lesions was performed in 133 patients. The AL group included 54 patients (M:F = 29:25) with 54 lesions (size range 7-90 mm, mean 32.1 ± 18.1) and AL+IV group included 79 patients (M:F = 44:35) with 79 lesions (size range 7-100 mm, mean 25.6 ± 15.0). AL group included 23 (43%) benign and 31 (57%) malignant lesions; AL+IV group included 31 (39%) benign and 48 (61%) malignant lesions. Sensitivity and accuracy for CT-guided biopsy of focal isoattenuating liver lesions were, overall 94% and 96%, AL group 97% and 98% and AL+IV group 92% and 94%, with no statistical significant difference between the AL and AL+IV groups (P = 0.88-1.00). CONCLUSION: Accurate planning and utilizing of internal reference ALs is successful in yielding a diagnostic sample for CT-guided percutaneous biopsy of isoattenuating focal liver lesion. The confidence of accurate targeting can be enhanced by administering IV contrast, however, since the visualization provided by IV contrast can be short-lived; use of IV contrast does not obviate the need for precise planning based on ALs.

Successful percutaneous radiologic management of renal cell carcinoma tumor seeding caused by percutaneous biopsy performed before ablation.

A case is reported of the successful image-based detection, diagnosis, and percutaneous ablation of tumor seeding in a 61-year-old man that was caused by percutaneous biopsy of a renal cell carcinoma performed before cryoablation and was not detected until 4 years after the biopsy procedure. Although tumor seeding is a rare complication after percutaneous biopsy or ablation, this case emphasizes the importance of imaging surveillance of the needle tract used during both biopsy and ablation procedures, provides guidance on measures that can be used to minimize the occurrence of tumor seeding, and demonstrates that entirely radiologic management can be successful.

Imaging after percutaneous radiofrequency ablation of hepatic tumors: Part 1, Normal findings.

OBJECTIVE: The purpose of this article is to review the spectrum of early and delayed normal cross-sectional imaging findings after percutaneous radiofrequency ablation of hepatic tumors. CONCLUSION: Knowledge of postablation imaging changes is vital not only for the interventionalist who performs the procedure but also for the diagnostician who interprets the postablation imaging. Recognition of normal postprocedural changes and differentiation from abnormal imaging findings prevent overcalling benign changes as abnormal and can thus avoid needless treatment.

Imaging after percutaneous radiofrequency ablation of hepatic tumors: Part 2, Abnormal findings.

OBJECTIVE: The purpose of this article is to review the spectrum of early and delayed abnormal cross-sectional imaging findings after radiofrequency ablation (RFA) of hepatic tumors. CONCLUSION: Recognition of abnormal post-RFA imaging findings and differentiation of abnormal findings from normal postprocedural changes are important for diagnostic and interventional radiologists. Early identification of residual or recurrent disease and complications can facilitate timely retreatment, management, and follow-up care.

The challenging image-guided abdominal mass biopsy: established and emerging techniques 'if you can see it, you can biopsy it'.

Image-guided percutaneous biopsy of abdominal masses is among the most commonly performed procedures in interventional radiology. While most abdominal masses are readily amenable to percutaneous biopsy, some may be technically challenging for a number of reasons. Low lesion conspicuity, small size, overlying or intervening structures, motion, such as that due to respiration, are some of the factors that can influence the ability and ultimately the success of an abdominal biopsy. Various techniques or technologies, such as choice of imaging modality, use of intravenous contrast and anatomic landmarks, patient positioning, organ displacement or trans-organ approach, angling CT gantry, triangulation method, real-time guidance with CT fluoroscopy or ultrasound, sedation or breath-hold, pre-procedural image fusion, electromagnetic tracking, and others, when used singularly or in combination, can overcome these challenges to facilitate needle placement in abdominal masses that otherwise would be considered not amenable to percutaneous biopsy. Familiarity and awareness of these techniques allows the interventional radiologist to expand the use of percutaneous biopsy in clinical practice, and help choose the most appropriate technique for a particular patient.

Cigarette smoking impairs pancreatic duct cell bicarbonate secretion.

OBJECTIVE: To compare pancreatic duct cell function in smokers (current and past) and never smokers by measurement of secretin-stimulated peak bicarbonate concentration ([HCO3-]) in endoscopic collected pancreatic fluid (PF). METHODS: This retrospective study was cross-sectional in design, recording demographic information (age, gender, etc.), smoking status (former, current, never), alcohol intake, clinical data (imaging, endoscopy), and laboratory results (peak PF [HCO3-]) from subjects evaluated for pancreatic disease at a tertiary pancreas center. Univariate and multivariate statistical analysis (SAS Version 9.2, Cary, NC, USA) was performed to assess the relationship between cigarette smoking and secretin-stimulated pancreatic fluid bicarbonate concentration. RESULTS: A total of 131 subjects underwent pancreatic fluid collection (endoscopic pancreatic function test, ePFT) for bicarbonate analysis: 25.2% (33 out of 131) past smokers, 31.3% (41 out of 131) current smokers, and 43.5% (57 out of 131) were never smokers. Measures of Association: The mean peak PF [HCO3-] in never smokers (81.3 ± 18.5 mEq/L) was statistically higher (indicating better duct cell function) when compared to past smokers (66.8 ± 24.7 mEq/L, P=0.005) and current smokers (70.0 ± 20.2 mEq/L, P=0.005). However, the mean peak [HCO3-] in past smokers was not statistically different from that in current smokers (P=0.575), and therefore, the two smoking groups were combined to form a single "smokers cohort". When compared to the never smokers, the smokers cohort was older (P=0.037) and had a greater proportion of subjects with definite chronic pancreatitis imaging (P=0.010), alcohol consumption ≥20 g/day (P=0.012), and abnormal peak PF [HCO3-] (P<0.001). Risk-Based Estimates: Cigarette smoking (risk ratio, RR: 2.2, 95% CI: 1.3-3.5; P<0.001), diagnosis of definite chronic pancreatitis imaging (RR: 2.2, 95% CI: 1.6-3.2; P<0.001) and alcohol consumption ≥20 g/day (RR: 1.6, 95% CI: 1.1-2.4; P=0.033) were all associated with low mean peak PF [HCO3-] (indicating duct cell secretory dysfunction). Multivariate Analysis: Smoking (odds ratio, OR: 3.8, 95% CI: 1.6-9.1; P=0.003) and definite chronic pancreatitis imaging (OR: 5.7, 95% CI: 2.2-14.8; P<0.001) were determined to be independent predictors of low peak PF [HCO3-], controlling for age, gender, and alcohol intake. Furthermore there was no interaction between smoking status and alcohol intake in predicting duct cell dysfunction (P=0.571). CONCLUSION: Measurement of pancreatic fluid bicarbonate in smokers reveals that cigarette smoking (past and current) is an independent risk factor for pancreatic duct cell secretory dysfunction (low PF [HCO3-]). Furthermore, the risk of duct cell dysfunction in subjects who smoked was approximately twice the risk (RR: 2.2) in never smokers. Further in depth, translational research approaches to pancreatic fluid analysis may help unravel mechanisms of cigarette smoking induced pancreatic duct cell injury.

PET/CT-guided radiofrequency and cryoablation: is tumor fluorine-18 fluorodeoxyglucose activity dissipated by thermal ablation?

PURPOSE: To determine if tumor fluorine-18 fluorodeoxyglucose ((18)F-FDG) activity is dissipated by radiofrequency (RF) ablation or cryoablation during tumor ablation guided by positron emission tomography/computed tomography (PET/CT). MATERIALS AND METHODS: This prospective study enrolled 12 patients (9 women and 3 men, 39-65 years old), each with at least one (18)F-FDG-avid liver, perihepatic, or lung tumor. Six patients (experimental group) underwent percutaneous PET/CT-guided RF ablation (n = 3) or cryoablation (n = 3). Six patients (control group) underwent diagnostic PET/CT-guided percutaneous biopsy. At a mean time of 103.5 minutes after a single intravenous (18)F-FDG dose, preprocedure and postprocedure PET/CT scans, separated by a mean time interval of 83.4 minutes, were obtained in all patients. Target tumor maximum standardized uptake value (TSUVmax) and ratio (SUVratio) of TSUVmax to normal liver average standardized uptake value (LSUVavg) were measured on all scans. Percentage changes in TSUVmax and SUVratio from preprocedure to postprocedure scans were compared for both groups and analyzed using the Student t test (P < .05 considered statistically significant). RESULTS: For all patients in both groups, TSUVmax and SUVratio increased from preprocedure to postprocedure PET/CT scans without statistically significant differences. The mean percentage increase in TSUVmax for the ablation group was 32.5% (range 8.2%-46.7%) and for the biopsy group was 24.6% (3.7%-42.4%; P = .45). The mean percentage increase in SUVratio for the ablation group was 47.9% (18.8%-69.6%) and for the biopsy group was 37.6% (9.4%-65%; P = .37). CONCLUSIONS: Tumor (18)F-FDG activity is not dissipated by percutaneous RF ablation or cryoablation. When performing (18)F-FDG PET/CT-guided RF ablation or cryoablation, changes in target tumor (18)F-FDG activity cannot be used to monitor treatment effects.

Minimizing image misregistration during PET/CT-guided percutaneous interventions with monitored breath-hold PET and CT acquisitions.

PURPOSE: To validate a monitored, breath-hold positron emission tomography (PET)/computed tomography (CT) acquisition technique for the minimization of respiratory PET/CT image misregistration and lesion distortion during PET/CT-guided percutaneous interventional procedures. MATERIALS AND METHODS: Eleven patients referred for percutaneous biopsy or thermal ablation of tumors near the diaphragm were prospectively enrolled. Initial PET/CT scanning was performed by using a bellows device and monitored, same-level breath-holds for PET and CT acquisitions. Breath-hold PET consisted of nine 20-second breath-hold frames, yielding a 3-minute equivalent PET dataset. A second PET/CT scan was obtained without monitoring by using end-expiration breath-hold CT and free-breathing PET. PET/CT tumor misregistration and craniocaudal tumor diameter were measured on monitored and unmonitored PET/CT datasets. Data were analyzed by using nonparametric, two-sided, signed-rank statistical tests. RESULTS: Mean PET/CT image misregistrations in the craniocaudal, anteroposterior, and transverse planes were 2.6 mm (range, 0-7 mm), 3.3 mm (range, 1-8 mm), and 2.7 mm (range, 0-8 mm) with monitoring and 14.7 mm (range, 0-49 mm), 7.6 mm (range, 1-24 mm), and 4.0 mm (range, 0-12 mm) without monitoring, respectively. Differences were significant for craniocaudal (P = .0087) and anteroposterior (P = .014) planes, but not for the transverse plane (P = .23). Mean craniocaudal target diameter was 2.5 mm (range, -2 to 9 mm) larger (ie, distorted) for unmonitored versus monitored PET (P = .061). CONCLUSIONS: Acquiring PET/CT datasets with respiratory bellows-assisted, monitored breath-holds improves PET/CT image registration versus unmonitored PET/CT and may facilitate accurate targeting during PET/CT-guided interventions in anatomic regions subject to respiratory motion.

Prospective evaluation of reader performance on MDCT in characterization of cystic pancreatic lesions and prediction of cyst biologic aggressiveness.

OBJECTIVE: Our objective was to evaluate the accuracy of MDCT features of pancreatic cystic lesions in cyst characterization and in predicting cyst biologic aggressiveness. SUBJECTS AND METHODS: In this prospective study, 114 patients (40 men and 74 women; age range, 23-89 years) with 130 cystic lesions (size range, 31-160 mm) in the pancreas underwent contrast-enhanced dual-phase (n = 92) and portal phase (n = 22) examinations with 16- or 64-MDCT scanners. Using defined morphologic features of cystic lesions on MDCT, two readers performed blinded evaluations for cystic characterization and predicting biologic aggressiveness (invasive lesions, carcinoma in situ, and moderate grade dysplasias) before pancreatic surgery. Receiver operating characteristic analysis was performed to assess the accuracy of MDCT using pathologic evaluation of the surgical specimen as a reference standard. RESULTS: On the basis of MDCT features, the radiologic accuracy (reader 1 and reader 2) for stratifying lesions into mucinous and nonmucinous subtypes was 85% and 82% and for recognizing cysts with aggressive biology was 86% and 85%, respectively. Predictive values of MDCT were superior for lesions > 30 mm and nonmucinous lesions. Features favoring aggressive biology were main pancreatic duct dilation > 10 mm (p < 0.0001), biliary obstruction (p=0.01), mural nodule (p < 0.0001), main-duct intraductal papillary mucinous neoplasm (p < 0.0001), and advanced age (p = 0.0001). Sensitivity of detecting morphologic features was higher with the dual-phase pancreatic protocol CT. CONCLUSION: Morphologic features of pancreatic cystic lesions on MDCT allow reliable characterization into mucinous and nonmucinous subtypes and enable prediction of biologic aggressiveness.

Secretin-enhanced MRCP: proceed with cautious optimism.

Magnetic resonance imaging (MRI) is a safe and universally available test that has much appeal to generalists and subspecialists evaluating patients with pancreatic disease. Testoni et al. report the clinical utility of magnetic resonance pancreaticocholangiography (MRCP) and secretin-enhanced MRCP in the evaluation of patients with asymptomatic abnormalities in pancreatic enzymes. The authors report that chronic pancreatitis changes will be seen in up to a third of patients with asymptomatic elevations in pancreas enzymes when compared with age-matched controls. The changes described on MRI and secretin-enhanced MRI are not in question, but the clinical significance of these changes is unknown. The authors rightly report that some of the changes seen may be age related, nonspecific, and of unknown clinical significance. Any new imaging and diagnostic test needs to be interpreted with caution until appropriate prospective clinical trials have been performed. It appears that secretin stimulation enhances the diagnostic accuracy of MRCP for the detection of minor changes in the pancreatic duct and parenchyma. Gastroenterologists are encouraged to proceed with cautious optimism when using MRI for the evaluation of early chronic pancreatitis.

Autoimmune pancreatitis: disease evolution, staging, response assessment, and CT features that predict response to corticosteroid therapy.

PURPOSE: To evaluate the evolution of morphologic features of autoimmune pancreatitis (AIP) at computed tomography (CT) and to identify imaging features that can predict AIP response to corticosteroid therapy (CST). MATERIALS AND METHODS: This HIPAA-compliant retrospective study had institutional review board approval. From among a cohort of 63 patients with AIP, 15 patients (12 men, three women; mean age, 64.7 years; age range, 30-84 years) who underwent sequential CT examinations before treatment were included to assess the evolution of disease by reviewing pancreatic, peripancreatic, and ductal changes. Of these patients, 13 received CST and underwent posttreatment CT; these CT studies were evaluated to determine if there were imaging features that could predict response to CST. RESULTS: The disease evolved from changes of diffuse (14 of 15 patients) or focal (one of 15 patients) parenchymal swelling, peripancreatic stranding (10 of 15 patients), "halo" (nine of 15 patients), pancreatic duct changes (15 of 15 patients), and distal common bile duct narrowing (12 of 15 patients) to either resolution or development of ductal strictures and/or focal masslike swelling. In 13 patients treated with CST, favorable response to treatment was seen in those with diffuse pancreatic and peripancreatic changes. Suboptimal response was seen in patients with ductal stricture formation (two of 13 patients) and in those in whom focal masslike swellings persisted after resolution of diffuse changes (seven of 13 patients). CONCLUSION: CT features like diffuse swelling and halo respond favorably to CST and likely reflect an early inflammatory phase, whereas features like ductal strictures and focal masslike swelling are predictive of a suboptimal response and symbolize a late stage with predominance of fibrosis.

IgG4-associated cholangitis: a comparative histological and immunophenotypic study with primary sclerosing cholangitis on liver biopsy material.

IgG4-associated cholangitis is a steroid-responsive hepatobiliary inflammatory condition associated with autoimmune pancreatitis that clinically and radiologically mimics primary sclerosing cholangitis. In this study, we conducted a morphological and immunohistochemical analysis of liver material obtained from individuals with IgG4-associated cholangitis, and compared these with well-characterized cases of primary sclerosing cholangitis. The study group consisted of 10 patients (9 biopsy and 1 hepatectomy case) with IgG4-associated cholangitis and 17 patients with primary sclerosing cholangitis (16 needle biopsy and 1 hepatectomy case). All patients with IgG4-associated cholangitis had pancreatic involvement as well, and six pancreatectomy samples revealed characteristic histopathological features of autoimmune pancreatitis. Primary sclerosing cholangitis cases were defined by the presence of a characteristic ERCP appearance. Clinical, pathological, radiological, and follow-up data were recorded for all cases. Portal and periportal inflammation was graded according to Ishak's guidelines. Immunohistochemical stains for IgG and IgG4 were performed. The cohort of patients with IgG4-associated cholangitis (mean age: 63 years) was older than individuals with primary sclerosing cholangitis (mean age: 44 years). Seven of these cases showed intrahepatic biliary strictures. IgG4-associated cholangitis liver samples showed higher portal (P=0.06) and lobular (P=0.009) inflammatory scores. Microscopic portal-based fibro-inflammatory nodules that were composed of fibroblasts, plasma cells, lymphocytes, and eosinophils were exclusively observed in five of the IgG4-associated cholangitis cases (50%). More than 10 IgG4-positive plasma cells per HPF (high power field) were observed in 6 of the IgG4-associated cholangitis cases (mean: 60, range: 0-140 per HPF), whereas all primary sclerosing cholangitis cases showed significantly lesser numbers (mean: 0.08, range: 0-1 per HPF). On a liver biopsy, the histological features of IgG4-associated cholangitis may be distinctive, and in conjunction with IgG4 immunohistochemical stain, may help distinguish this disease from primary sclerosing cholangitis.

Comparative performance of MDCT and MRI with MR cholangiopancreatography in characterizing small pancreatic cysts.

OBJECTIVE: The objective of our study was to compare MDCT with MRI-MR cholangiopancreatography (MRCP) in characterizing small pancreatic cysts (< or = 3 cm) and predicting aggressiveness. MATERIALS AND METHODS: In a retrospective analysis, contrast-enhanced MDCT and MRI examinations of 30 patients with 38 pathologically confirmed small pancreatic cysts were reviewed. MDCT and MRCP studies were independently evaluated by two readers for cyst morphology, cyst characterization, and prediction of lesion aggressiveness, which included lesions with moderate-grade dysplasia, high-grade dysplasia (carcinoma in situ), and invasive carcinomas. The sensitivity of MDCT and MRI for the detection of each morphologic feature, accuracy for cyst characterization, and predictive values for aggressiveness were calculated. RESULTS: Of 38 lesions, 14 were side-branch intraductal papillary mucinous neoplasms (IPMNs), 12 mixed IPMNs, six mucinous cystic neoplasms, and six nonneoplastic cysts. On histopathology, 26 lesions were nonaggressive (six nonneoplastic cysts, six benign mucinous cystic neoplasms, 14 low-grade dysplasias in IPMNs), whereas 12 lesions revealed aggressive biology (eight moderate-grade dysplasias, four high-grade dysplasias in IPMNs). The sensitivity of MRCP for the detection of morphologic features was better than that of MDCT, but the differences were not statistically significant (p = 0.25-1). Interreader agreement and MDCT-MRI agreement for morphologic features were good to perfect (kappa = 0.7-1). The accuracy of MDCT and MRI was higher in classifying cysts as mucinous or nonmucinous than in determining a specific diagnosis (71-84.2% vs 39.5-44.7%, respectively), whereas the accuracy of the two techniques in characterizing cysts into nonaggressive and aggressive categories was similar (MDCT vs MRI, 75-78% vs 78-86%, respectively; p > 0.05). CONCLUSION: MRI enables more confident assessment of the morphology of small cysts than MDCT, but the accuracy of the two imaging techniques for cyst characterization is comparable. MDCT and MRI have high accuracy in classifying cysts into mucinous and nonmucinous categories and perform similarly in estimating histologic aggressiveness.

Cholangiocarcinoma: current and novel imaging techniques.

The radiologic manifestations of cholangiocarcinomas are extremely diverse, since these tumors vary greatly in location, growth pattern, and histologic type. Familiarity with the imaging manifestations of cholangiocarcinomas is important for accurate detection and characterization of these tumors and assessment of resectability. Advances in imaging techniques have led to the availability of an array of modalities that, used independently or in combination, can aid in the accurate diagnosis and evaluation of cholangiocarcinomas in preparation for advanced surgical procedures and treatment planning. Response to novel targeted therapies can also be assessed with newer imaging tools. Hence, knowledge of current and emerging imaging applications is essential for correct diagnosis and appropriate management of these tumors.

Antenatal diagnosis of iniencephaly: sonographic and MR correlation: a case report.

Iniencephaly is an uncommon and fatal neural tube defect involving the occiput and inion, this occurs together with rachischisis of the cervical and thoracic spine, and retroflexion of the head. We report the ultrasound (US) and magnetic resonance (MR) imaging findings of a case of iniencephaly with clubfeet and arthrogryposis. The diagnosis of iniencephaly is easy to make on ultrasound due to the typical star-gazing fetus. However, the details of the fetal brain and spinal cord may not be adequately delineated on US. We found MR imaging to be superior for depicting central nervous system abnormalities. MR imaging has evolved as an imaging modality and it is complementary to fetal US, yet US remains the screening modality of choice.