Small hepatocellular carcinomas displayed as a ring enhancing mass on arterial phase MRI in the chronically diseased liver.

AIM: To assess the prevalence of arterial phase (AP) ring-enhancing small hepatocellular carcinomas (HCC) on magnetic resonance imaging (MRI); detail additional MRI features that enable HCC diagnosis; and examine arterial timing as one possible cause of this appearance. MATERIALS AND METHODS: Patients undergoing HCC screening with both computed tomography (CT) and MRI within 40 days were examined at a single institution over a 7- year time period ending in 2013. From this initial group, small (1-3 cm), (AP) ring-enhancing HCC on MRI were studied. RESULTS: From the initial group of 64 patients with 129 HCC, 20 patients with 78 HCCs had a small diameter with 32 (41%) having an AP ring at MRI. The mean age of this latter group was 63-years old, with the average tumour diameter of 1.9 cm. Histopathology and secondary imaging supported a diagnosis of HCC in 20 (100%) patients and 31 (97%) lesions. Most of the ringed lesions had early AP timing. CONCLUSION: This study revealed a high prevalence (41%) of small, AP ring HCC with MRI. The use of other MRI sequences adds support in making the proper diagnosis with this appearance. Early AP timing may help create this pattern.

Comparison of spin-echo T1- and T2-weighted and gradient-echo T1-weighted images at 3T in evaluating very preterm neonates at term-equivalent age.

Term-equivalent imaging can assess myelination status in very preterm infants (<30 weeks' gestational age at birth). However, myelination assessment has yet to be compared among GRE-T1WI, SE-T1WI, and SE-T2WI at 3T. We aimed to compare the rates of myelination among those 3 sequences in 11 very preterm neonates who underwent 3T MR imaging at term-equivalent age and subsequently had normal neurologic development. On each sequence, 2 neuroradiologists individually assessed 22 structures. SE-T2WI depicted a higher myelination rate (present in 58.2%-66.4% of all structures) than either GRE-T1WI (51.6%-63.9%) or SE-T1WI (20.5%-38.5%), while GRE-T1WI had the highest interobserver agreement (κ, 0.56; P < .0001). Myelination was present in 90%-100% of patients within the corpus callosum splenium, DSCP, ICP, lateral lemniscus, and spinal tract/nucleus of cranial nerve V on SE-T2WI, and in the DSCP, ICP, lateral lemniscus, medial lemniscus, pyramidal decussation, PLIC, and superior cerebellar peduncle on GRE-T1WI, occurring in similar structures as previously shown at 1.5T and 1T. However, it is not clear whether these findings represent true myelination versus precursors to myelination.