Imaging language pathways predicts postoperative naming deficits

Naming difficulties are a well recognised, but difficult to predict, complication of anterior temporal lobe resection (ATLR) for refractory epilepsy. We used MR tractography preoperatively to demonstrate the structural connectivity of language areas in patients undergoing dominant hemisphere ATLR. Greater lateralisation of tracts to the dominant hemisphere was associated with greater decline in naming function. We suggest that this method has the potential to predict language deficits in patients undergoing ATLR

MRI for the evaluation of gastric physiology

Radiolog

Quantification of gastrointestinal liquid volumes and distribution following a 240 mL dose of water in the fasted state

Previous imaging studies offered a snapshot of water distribution in fasted humans and showed that water in the small intestine is distributed in small pockets. This study aimed to quantify the volume and number of water pockets in the upper gut of fasted healthy humans following ingestion of a glass of water (240 mL, as recommended for bioavailability/bioequivalence (BA/BE) studies), using recently validated noninvasive magnetic resonance imaging (MRI) methods. Twelve healthy volunteers underwent upper and lower abdominal MRI scans before drinking 240 mL (8 fluid ounces) of water. After ingesting the water, they were scanned at intervals for 2 h. The drink volume, inclusion criteria, and fasting conditions matched the international standards for BA/BE testing in healthy volunteers. The images were processed for gastric and intestinal total water volumes and for the number and volume of separate intestinal water pockets larger than 0.5 mL. The fasted stomach contained 35 ± 7 mL (mean ± SEM) of resting water. Upon drinking, the gastric fluid rose to 242 ± 9 mL. The gastric water volume declined rapidly after that with a half emptying time (T50%) of 13 ± 1 min. The mean gastric volume returned back to baseline 45 min after the drink. The fasted small bowel contained a total volume of 43 ± 14 mL of resting water. Twelve minutes after ingestion of water, small bowel water content rose to a maximum value of 94 ± 24 mL contained within 15 ± 2 pockets of 6 ± 2 mL each. At 45 min, when the glass of water had emptied completely from the stomach, total intestinal water volume was 77 ± 15 mL distributed into 16 ± 3 pockets of 5 ± 1 mL each. MRI provided unprecedented insights into the time course, number, volume, and location of water pockets in the stomach and small intestine under conditions that represent standard BA/BE studies using validated techniques. These data add to our current understanding of gastrointestinal physiology and will help improve physiological relevance of in vitro testing methods and in silico transport analyses for prediction of bioperformance of oral solid dosage forms, particularly for low solubility Biopharmaceutics Classification System (BCS) Class 2 and Class 4 compounds

Optimized interleaved whole-brain 3D double inversion recovery (DIR) sequence for imaging the neocortex

For a substantial number of individuals with neurological disorders, a conventional MRI scan does not reveal any obvious etiology; however, it is believed that abnormalities in the neocortical gray matter (GM) underlie many of these disorders. Attempts to image the neocortex are hindered by its thin, convoluted structure, and the partial volume (PV) effect. Therefore, we developed a 3D version of the double inversion recovery (DIR) sequence that incorporates an optimized interleaved (OIL) strategy to improve efficiency and allow high-quality, high-resolution imaging of GM. (C) 2004 Wiley-Liss, Inc

Postictal diffusion weighted imaging

Purpose: Our aim was to determine whether diffusion weighted imaging can detect abnormalities of diffusivity after single seizures, and investigate the localisation and time course of any changes.Methods: Twenty-one patients with intractable focal epilepsy were imaged interictally and after 23 seizures. Voxel-based statistical parametric mapping was used to detect postictal changes in mean diffusivity (MD), compared to the changes noted in 20 controls scanned twice. The time course and magnitude of the changes were evaluated by measuring MD in the areas of change identified by the voxel-based analysis.Results: Thirty-four focal changes in MD (24 decreases, 10 increases) were detected after 12 of 23 seizures in 11 patients, after a median interval of 53 min from the time of seizure onset. Five patients had areas of both increased and decreased diffusion after seizures. In four patients, postictal changes in diffusion corresponded with the presumed seizure focus. Repeated postictal scanning, after a further interval of a median of 46 min in eight patients, showed that postictal changes in MD, both increases and decreases, were returning towards interictal values.Conclusions: Diffusion weighted imaging identified focal changes in MD after 52% of single complex partial and secondarily generalised seizures. Changes in MD corresponded to the putative seizure focus in a minority of cases suggesting that the technique is not promising as a method for localising seizure foci, but may indicate the networks involved in seizures. (c) 2006 Elsevier B.V All rights reserved