Magnetic Resonance Angiography Signal Intensity as a Marker of Hemodynamic Impairment in Intracranial Arterial Stenosis

BACKGROUND: Intracranial arterial stenosis (ICAS) is the predominant cause of ischemic stroke and transient ischemic attack in Asia. Change of signal intensities (SI) across an ICAS on magnetic resonance angiography (MRA) may reflect its hemodynamic severity. METHODS: In-patients with a symptomatic single ICAS detected on 3D time-of-flight MRA were recruited from 2 hospitals. Baseline and 1-year follow-up data were collected. Signal intensity ratio (SIR) [ =  (mean post-stenotic SI -mean background SI)/(mean pre-stenotic SI - mean background SI)] was evaluated on baseline MRA to represent change of SIs across an ICAS. Acute infarct volume was measured on baseline diffusion-weighted images (DWI). Relationships between SIR and baseline characteristics as well as 1y outcomes were evaluated. RESULTS: Thirty-six subjects (86.1% males, mean age 55.0) were recruited. Overall, mean SIR was 0.84±0.23. Mean SIRs were not significantly different between the 23 (63.9%) anatomically severe stenoses and the 13 (36.1%) anatomically moderate stenoses (0.80±0.23 versus 0.92±0.21, p = 0.126). SIR was significantly, linearly and negatively correlated to acute infarct volume on DWI (Spearman correlation coefficient −0.471, p = 0.011). Two patients (5.6%) had recurrent ischemic strokes at 1y, not related to SIR values. CONCLUSIONS: Change of signal intensities across an ICAS on MRA may reflect its hemodynamic and functional severity. Future studies are warranted to further verify the relationships between this index and prognosis of patients with symptomatic ICAS

Rare neoplasms

Although interest in pancreatic pathology is very high in the radiological and gastroenterological communities, it is still the case that less is known about pathology of the pancreas than about liver pathology, for example. Diagnosis depends on the structure of the pancreatic lesion, which can be directly visualized on US, CT or MR images. This atlas, which encompasses both the imaging and the pathology of pancreatic neoplasms, will therefore be invaluable in enabling radiologists and sonographers to understand the underlying pathology and in allowing pancreatic pathologists to understand the imaging translation. The emphasis in the atlas is very much on the pathological and imaging appearances, with most of the text concentrated at the beginning of the chapters. A comprehensive overview is provided of typical and atypical presentations and diverse aspects of common and uncommon pancreatic neoplasms, including ductal adenocarcinoma, neuroendocrine neoplasms, intraductal papillary mucinous neoplasms, cystic neoplasms, metastases and lymphoma