Acute interstitial edematous pancreatitis:Findings on non-enhanced MR imaging

AIM： To study the appearances of acute interstitial edematous pancreatitis （IEP） on non-enhanced MR imaging. METHODS： A total of 53 patients with IEP diagnosed by clinical features and laboratory findings were underwent MR imaging. MR imaging sequences included fast spoiled gradient echo （FSPGR） fat saturation axial T1-weighted imaging, gradient echo T1-weighted （in phase）, single shot fast spin echo （SSFSE） T2-weighted, respiratory triggered （R-T） T2-weighted with fat saturation, and MR cholangiopancreatography. Using the MR severity score index, pancreatitis was graded as mild （0-2 points）, moderate （3-6 points） and severe （7-10 points）. RESULTS： Among the 53 patients, IEP was graded as mild in 37 patients and as moderate in 16 patients. Forty-seven of 53 （89%） patients had at least one abnormality on MR images. Pancreas was hypointense relative to liver on FSPGR T1-weighted images in 18.9% of patients, and hyperintense in 25% and 30% on SSFSE T2-weighted and R-T T2-weighted images, respectively. The prevalences of the findings of IEP on R-T T2-weighted images were, respectively, 85% for pancreatic fascial plane, 77% for left renal fascial plane, 55% for peripancreatic fat stranding, 42% for right renal fascial plane, 45% for perivascular fluid, 40% for thickened pancreatic Iobular septum and 25% for peripancreatic fluid, which were markedly higher than those on in-phase or SSFSE T2-weighted images （P 〈 0.001）. CONCLUSION： IEP primarily manifests on non- enhanced MR images as thickened pancreatic fascial plane, left renal fascial plane, peripancreatic fat stranding, and peripancreatic fluid. R-T T2-weighted imaging is more sensitive than in-phase and SSFSE T2- weighted imaging for depicting IER

Hepatocellular carcinoma after Iocoregional therapy:Magnetic resonance imaging findings in falsely negative exams

AIM:To elucidate causes for false negative magnetic resonance imaging(MRI)exams by identifying imaging characteristics that predict viable hepatocellular carcinoma(HCC)in lesions previously treated with locoregional therapy when obvious findings of recurrence are absent.METHODS:This retrospective institutional review board-approved and Health Insurance Portability and Accountability Act-compliant study included patients who underwent liver transplantation at our center between 1/1/2000 and 12/31/2012 after being treated for HCC with locoregional therapy.All selected patients had a contrast-enhanced MRI after locoregional therapy within 90 d of transplant that was prospectively interpreted as without evidence of residual or recurrenttumor.Retrospectively,2 radiologists,blinded to clinica and pathological data,independently reviewed the pre transplant MRIs for 7 imaging features.Liver explan histopathology provided the reference standard,with clinically significant tumor defined as viable tumor≥1.0cm in maximum dimension.Fisher’s exact test was firs performed to identify significant imaging features.RESULTS:Inclusion criteria selected for 42 patients with 65 treated lesions.Fourteen of 42 patients(33%and 16 of 65 treated lesions(25%)had clinically significant viable tumor on explant histology.None o the 7 imaging findings examined could reliably and reproducibly determine which treated lesion had viable tumor when the exam had been prospectively read as without evidence of viable HCC.CONCLUSION:After locoregional therapy some treated lesions that do not demonstrate any MRI evidence o HCC will contain viable tumor.As such even patients with a negative MRI following treatment should receive regular short-term imaging surveillance because some have occult viable tumor.The possibility of occult tumo should be a consideration when contemplating any action which might delay liver transplant.