Diffusion-weighted MR Imaging In Diagnosis Research Articles

Role of diffusion-weighted MR imaging in diagnosis of acute pancreatitis

BackgroundThe role of diffusion-weighted magnetic resonance imaging (DW-MRI) in the diagnosis of acute pancreatitis is assessed in this study by measuring the apparent diffusion coefficient (ADC) values in acute pancreatitis and comparing them with a control group. The aim of this study is to compare those two groups thus supporting the diagnosis of this disease.Sixteen patients with acute pancreatitis and 16 control participants underwent diffusion-weighted imaging with b values of 0, 200, and 800. ADC maps were generated from the DW-MRI and ADC values, which were calculated for the pancreas, and the results of the two groups of patients were compared.ResultsThe mean pancreatic ADC value in the acute pancreatitis group (1.15 × 10(−3) mm(2)/s ± 0.28) was significantly lower than in the normal group (1.6 × 10−3 mm(2)/s ± 0.2). A threshold ADC value of 1.38 × 10−3 mm(2)/s yielded 81.25%, specificity of 93.75%, positive predictive value of 92.9%, negative predictive value of 83.3%, and accuracy of 91.8%. Pancreatic ADC values were significantly lower in patients with acute pancreatitis than in the control group.ConclusionDiffusion-weighted magnetic resonance imaging could be an important supportive tool in the diagnosis of acute pancreatitis.

Value of diffusion-weighted MR imaging in diagnosis of acute rejection after renal transplantation

To evaluate the feasibility of MR diffusion-weighted imaging (DWI) in diagnosis of acute rejection after renal transplantation. Sixty-nine patients who underwent renal transplantation were enrolled in the study. According to the clinical features and renal biopsy, 26 patients were designated in rejection group and 43 in non-rejection group. Patients in non-rejection group underwent MR DWI scan at 2 to 3 weeks after operation, and those in rejection group underwent scan at 5 d before or after renal biopsy. Then the apparent diffusion coefficient (ADC) values of transplanted kidneys were measured with high diffusion sensitivity gradient factors (b values). Patients with acute rejection had significantly lower ADC (P <0.04) than non-rejection patients with all the different b values (b=200, 400, 600, 800, 1,000 s/mm(2)). The ROC curves showed that sensitivity and specificity were best when b value was 800 s/mm(2). DWI is a potential and reliable non-invasive method for the diagnosis of the acute rejection after renal transplantation.

Diffusion-Weighted MR Imaging in Diagnosis of Superficial and Invasive Urinary Bladder Carcinoma: A Preliminary Prospective Study

We conducted a prospective study to demonstrate the feasibility of using diffusionweighted (DW) magnetic resonance imaging (MRI) for the detection of urinary bladder carcinomas. Between January to June 2007, 43 patients with single bladder tumor were included in our study. Before taking a biopsy, DW MRI was obtained in the axial plane under free breathing scanning with a multisection, spin-echo type, single-shot echo planar sequence with a body coil. Moreover, the apparent diffusion coefficient (ADC) value was measured in a circular region of interest within the carcinoma, urine, normal bladder wall, prostate, and seminal vesicle. All carcinomas in the 43 patients were clearly shown as high signal intensity relative to the surrounding structure. The sensitivity and positive predictive values of DW MRI were 100% in terms of correctly detecting the carcinomas. The ADC value in the carcinoma (1.40 ± 0.51) was significantly lower compared with that of urine (3.50 ± 0.43) (p < 0.001), normal bladder wall (2.29 ± 0.78) (p < 0.001), peripheral zone of prostate (1.77 ± 0.44) (p < 0.05), transition zone of prostate (1.88 ± 0.54) (p < 0.05), and the seminal vesicle (2.12 ± 0.43) (p < 0.001). There was no statistical difference in ADC values between different histological subtypes. There was no overlap between the ADC values of the tumors and the urine, but there was no clear cutoff between the tumor and bladder wall, prostate, or seminal vesicles. Bladder carcinomas have significantly lower ADC when compared to surroundings. Clinical experience with this method is still preliminary and further studies are required.