Title:
The value of diffusion-weighted magnetic resonance imaging in the differential diagnosis in diffuse bowel wall thickening.

Abstract:
We aimed to investigate the value of diffusion-weighted magnetic resonance imaging in the differentiation of benign-malignant diffuse bowel wall thickening (scirrhous colon carcinoma) and to discuss the diagnostic importance and potential use of apparent diffusion coefficient measurements.
A total of 41 patients (32 males, 9 females; mean age, 57 years) with diffuse bowel wall thickening diagnosed on computed tomography were included in this study. The magnetic resonance imaging was performed on a 1.5 T scanner (Siemens-Espree). Changes in the signal intensity of the lesions were determined by their appearance in images at b800 s/mm 2 , and apparent diffusion coefficient values were also calculated. Lesions were classified in two groups according to the presence of hyperintensity on b800 images and results of endoscopic biopsies. The differences in mean apparent diffusion coefficient values between the two groups were compared with the Mann-Whitney U test, and threshold values were determined with receiver operating characteristic curve analysis.
The difference between the mean apparent diffusion coefficient values of benign and malignant groups was statistically significant, and the apparent diffusion coefficient values of benign lesions were significantly higher than of malignant lesions (p<0.05). By using a cut-off value of 1.21 x 10-3mm2 /s, apparent diffusion coefficient had a sensitivity of 100%, specificity of 87.3%, and accuracy of 89.3% in the discrimination of malignant colorectal pathologies. With the visual assessment of the diffusion weighted images and the measurement of apparent diffusion coefficient values, malignant and benign lesions could be differentiated, with 100% sensitivity, 89.2% specificity, and 90.4% accuracy. Although some benign lesions were interpreted as malignant,no malignant lesion was determined as benign in the visual assessment.
Diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient values together can successfully differentiate malignant from benign diffuse bowel wall thickening.