ADC measurements in various patterns of multiple sclerosis lesions.

OBJECTIVE: To determine the difference of mean apparent diffusion coefficients (ADC) among different patterns of focal multiple sclerosis (MS) lesions, to compare mean lesion ADC between 2 clinical subgroups and to correlate mean lesion ADC with disability. MATERIAL AND METHOD: Thirty seven patients (26 with relapsing-remitting multiple sclerosis (MS) and 11 with secondary-progressive MS) underwent both conventional and diffusion-weighted MR imaging of the brain. After creating ADC maps, region identification was done by using b = 0 images and T2-weighted images. ADC values were measured for MS lesions and (NAWM). RESULTS: A total of 288 lesions were identified on the images. The mean ADC for the lesions was significantly higher than that of NAWM Hypointense T1 lesions (n = 221) had a significantly higher mean ADC than isointense T1 lesions (n = 67) in both nonenhancing lesions (n = 250) and enhancing lesions (n = 38). The enhanced rim of ring-enhancing lesions (n = 18) had lower ADC than the central nonenhanced portions. Confluent lesions (n = 62) had a substantially higher mean ADC than discrete lesion (n = 226). Mean lesion ADC of secondary progressive MS was significantly higher than relapsing remitting MS. No correlation between mean lesion ADC and (EDSS) score was found CONCLUSION: Quantitative diffusion-weighted imaging is useful to elucidate the heterogeneous pathological substrate of MS in different patterns of MS lesions, to differentiate 2 major clinical subgroups.

Magnetic resonance urography (MRU) versus intravenous urography (IVU) in obstructive uropathy: a prospective study of 30 cases.

AIM: Intravenous Urography (IVU) as a diagnostic modality has limitations in patients of obstructive uropathy with impaired renal function. Our aim was to study the technique and diagnostic accuracy of Magnetic Resonance Urography (MRU) in obstructive uropathy and to correlate the findings with IVU. METHODOLOGY: Forty-eight patients, selected over a six-month period, based on mild to severe pelvicalyceal dilatation on screening ultrasonography, underwent an IVU; those having non-obstructive dilatation were excluded (18 patients). Thirty patients (age range 10 to 75 years) with definite obstructive dilatation underwent MRU. These were obtained using an open MRI unit (Siemens Magnetom Open Viva) with low-dose gadolinium-DTPA (0.01 mmol/kg body weight) using various MRI sequences. MRU studies were classified as 'excellent' or 'diagnostic' and data generated was compared with that of IVU. RESULTS: MRU studies were 'excellent' in twelve and 'diagnostic' in eighteen patients. Of the sixty pelvicalyceal systems (PCS) evaluated in thirty patients, there were thirty-seven calculi, nine pelvi-ureteric junction (PUJ) obstructions, six with impaired renal function, four malrotated kidneys and one each of horseshoe kidney, pancake kidney, pelvic mass (endometriomas), duplex moieties, ureterocele and vesico-ureteric reflux. MRU better depicted moderate-severe PCS dilatation, staghorn and urethral calculi, impaired renal function, extrinsic ureteric and PUJ obstruction. IVU better depicted small calculi and mild PCS dilatation. CONCLUSIONS: In these thirty patients of obstructive uropathy, low magnetic field, open MRI units and low-dose Gd-DTPA provided cost-effective MRU studies with excellent diagnostic utility. MRU scored over IVU in patients with moderate-severe dilatation, staghorn and urethral calculi, impaired renal function, extrinsic ureteric and PUJ obstruction.