Assessment of MR Imaging and CT in Differentiating Hereditary and Nonhereditary Paragangliomas.

BACKGROUND AND PURPOSE: Head and neck paragangliomas have been reported to be associated with mutations of the succinate dehydrogenase enzyme family. The aim of this study was to assess whether radiologic features could differentiate between paragangliomas in the head and neck positive and negative for the succinate dehydrogenase mutation. MATERIALS AND METHODS: This single-center retrospective review from January 2015 to January 2020 included 40 patients with 48 paragangliomas (30 tumors positive for succinate dehydrogenase mutation in 23 patients and 18 tumors negative for the succinate dehydrogenase mutation in 17 patients). ADC values and tumor characteristics on CT and MR imaging were evaluated by 2 radiologists. Differences between the 2 cohorts in the diagnostic performance of ADC and normalized ADC (ratio to ADC in the medulla oblongata) values were evaluated using the independent samples t test. P < .05 was considered significant. RESULTS: ADCmean (1.07 [SD, 0.25]/1.04 [SD, 0.12] versus 1.31 [SD, 0.16]/1.30 [SD, 0.20]× 10-3 mm2/s by radiologists 1 and 2; P < .001), ADCmaximum (1.49 [SD, 0.27]/1.49 [SD, 0.20] versus 2.01 [SD, 0.16]/1.87 [SD, 0.20] × 10-3 mm2/s; P < .001), normalized ADCmean (1.40 [SD, 0.33]/1.37 [SD, 0.16] versus 1.73 [SD, 0.22]/1.74 [SD, 0.27]; P < .001), and normalized ADCmaximum (1.95 [SD, 0.37]/1.97 [SD, 0.27] versus 2.64 [SD, 0.22]/2.48 [SD, 0.28]; P < .001) were significantly lower in succinate dehydrogenase mutation-positive than mutation-negative tumors. ADCminimum, normalized ADCminimum, and tumor characteristics were not statistically significant. CONCLUSIONS: ADC is a promising imaging biomarker that can help differentiate succinate dehydrogenase mutation-positive from mutation-negative paragangliomas in the head and neck.

CT findings of intraductal papillary neoplasm of the bile duct: assessment with multiphase contrast-enhanced examination using multi-detector CT.

AIM: To evaluate multi-detector computed tomography (MDCT) findings of intraductal papillary neoplasm of the bile duct (IPNB), a neoplasm that is considered to be the biliary counterpart of pancreatic intraductal papillary mucinous neoplasm. MATERIALS AND METHODS: Two radiologists retrospectively evaluated multiphase contrast-enhanced CT images with 0.5 or 1mm collimation in 37 consecutive patients with resected IPNB diagnosed by a single pathologist. The CT findings were correlated with the pathological findings concerning invasion of the surrounding organs and vessels. RESULTS: All patients showed bile duct dilatation. An intraductal mass was detected in 36 patients and the following findings were observed: extensive infiltration along the bile duct more than 20mm (n=32), compared with normal hepatic parenchyma, isodense or hyperdense during the late arterial phase (n=31), not hyperdense during the portal-venous and delayed phases (n=36), and intense enhancement rim at the base of the mass during the portal-venous or delayed phase (n=27). Parenchymal invasion of the surrounding organs was seen in eight of 16 tumours showing irregular or bulging margins. Vascular invasion was false positive in four of eight tumours. CONCLUSIONS: IPNB exhibits relatively characteristic findings with multiphase contrast-enhanced examination using MDCT. A tendency to overestimate invasion of the surrounding organs and vessels was seen.

Scattered radiation from dental metallic crowns in head and neck radiotherapy.

We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS.

CT findings in autoimmune pancreatitis: assessment using multiphase contrast-enhanced multisection CT.

AIM: To assess the spectrum of findings using multiphase contrast-enhanced computed tomography (CT) in patients with autoimmune pancreatitis (AIP). MATERIALS AND METHODS: Fifty patients (four female and 46 male, mean age 65 years) were retrospectively identified from consecutive patients with abnormal CT findings of the pancreas and negative work-up for known causes. These patients had at least one finding supporting the diagnosis of AIP: serological abnormality, histopathological abnormality, or response to steroid. Two radiologists evaluated multiphase contrast-enhanced CT images in consensus. RESULTS: The pancreas showed diffuse enlargement (n=16; 32%), focal enlargement (n=18; 36%), or no enlargement (n=16; 32%). Forty-nine (98%) patients showed abnormal contrast enhancement in the affected pancreatic parenchyma, including hypoattenuation during the pancreatic phase (n=45; 90%) and hyperattenuation during the delayed phase (n=39; 87%). The following findings were also seen in the pancreas: a capsule-like rim (n=24; 48%); no visualization of the main pancreatic duct lumen (n=48; 96%); ductal enhancement (n=26; 52%); upstream dilatation of the main pancreatic duct (n=27; 54%); upstream atrophy of the pancreatic parenchyma (n=27; 54%); calcification (n=7; 14%); and cysts (n=5; 10%). Forty-two (84%) patients showed one or more of the following extrapancreatic findings: biliary duct or gallbladder abnormality (n=40; 80%); peripancreatic (n=8; 16%) or para-aortic (n=10; 20%) soft-tissue proliferation; and renal involvement (n=15; 30%). CONCLUSION: Patients with AIP presented with a variety of CT findings in the pancreas and the extrapancreatic organs. The present study highlights pancreatic ductal enhancement in a subset of patients with AIP.

Lymphoplasmacytic sclerosing cholangitis: assessment of clinical, CT, and pathological findings.

AIM: To assess the clinical, computed tomography (CT), and pathological findings in patients with lymphoplasmacytic sclerosing cholangitis. MATERIALS AND METHODS: Fifteen consecutive patients (four women and 11 men, mean age 71 years) with lymphoplasmacytic sclerosing cholangitis and without the characteristic features of underlying disorders causing benign biliary strictures were retrospectively recruited. Two radiologists evaluated multiphase contrast-enhanced CT images acquired with 0.5 or 1-mm collimation. One pathologist performed all histological examinations, including IgG4 immunostaining. RESULTS: The intrahepatic biliary ducts showed dilatation in all 15 patients, but only seven presented with jaundice. Although laboratory data were not available in all patients, serum gammaglobulin and IgG levels were elevated in five of six patients and six of eight patients, respectively. Anti-nuclear antibody was detected in three of six patients. The involved biliary ducts showed the following CT findings: involvement of the hilar biliary duct (14/15), a mean wall thickness of 4.9 mm, a smooth margin (10/15), a narrow but visible lumen (6/15), hyper-attenuation during the late arterial phase (9/15), homogeneous hyper-attenuation during the delayed phase (11/11), and no vascular invasion (14/15). Abnormal findings in the pancreas and urinary tract were detected in eight of 15 patients. In 13 patients with adequate specimens, moderate to severe lymphoplasmacytic infiltration associated with dense fibrosis was observed. Infiltration of IgG4-positive plasma cells was moderate or severe in nine patients and minimal or absent in four patients. CONCLUSION: Lymphoplasmacytic sclerosing cholangitis exhibits relatively characteristic clinical and CT findings, although they are not sufficiently specific for differentiation from other biliary diseases.

Focal inflammation in the embryological ventral pancreas: assessment using CT and MRI.

AIM: To identify the characteristic computed tomography (CT) and magnetic resonance imaging (MRI) findings of nonuniform inflammation between the posterior aspect of the head and the remainder of the pancreas. MATERIALS AND METHODS: Two radiologists retrospectively evaluated images of 19 patients in whom the degree of attenuation in the CT images and/or the signal intensity in the MRI images differed between the posterior aspect of the head (ventral primordium) and the remainder of the pancreas (dorsal primordium) due to benign disorders other than uneven fatty replacement. Multiphase, contrast-enhanced CT examinations were performed in 17 patients. In five, T1- and T2-weighted images with and without fat suppression were obtained using a 1.5 T superconducting MRI system. RESULTS: The lesions were localized in the posterior aspect of the head in 17 patients. In two patients, the lesions occupied the posterior aspect of the head and extended to the neck. The lesions exhibited the following findings: inhomogeneous hypoattenuation (with spotty areas of relatively well-maintained contrast enhancement) during the pancreatic phase (17/17) and no intense peripheral enhancement or central necrotic areas (17/17) in CT images, hypointensity in T1-weighed images (5/5), hyperintensity in T2-weighed images (4/5), no vascular invasion (19/19), failure to depict the entire course of Wirsung's duct (17/19), and calcification (13/19). Santorini's ducts were depicted in all but three patients. CONCLUSION: Focal inflammation in the embryological ventral pancreas exhibits a unique anatomical distribution and characteristic findings.