Clinical Usefulness of Diffusion-weighted Imaging Using Low and High b-values to Detect Rectal Cancer

• Published in: Magnetic Resonance in Medical Sciences 2006, Vol.5(4), pp.173-177
• Main Authors: HOSONUMA, Tomonori, TOZAKI, Mitsuhiro, ICHIBA, Noriatsu, SAKUMA, Tohru, HAYASHI, Daichi, YANAGA, Katsuhiko, FUKUDA, Kunihiko
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Algorithms; Diffusion Magnetic Resonance Imaging - methods; diffusion-weighted images; Female; Humans; Image Enhancement - methods; Image Interpretation, Computer-Assisted - methods; low and high b-value; Male; Middle Aged; rectal cancer; Rectal Neoplasms - diagnosis; Rectum - pathology; Reproducibility of Results; Sensitivity and Specificity
• ISSN: 1347-3182; 1880-2206
• DOI: 10.2463/mrms.5.173

Purpose: The purpose of this study was to assess the potential role of diffusion-weighted imaging (DWI) using low and high b-values to detect rectal cancer. Methods: The subjects were 15 patients diagnosed endoscopically with rectal cancer (m in 1 patient, sm in 0, mp in 3, ss in 7, se in 1, a in 3) and 20 patients diagnosed endoscopically with colon cancer and no other lesions (control group). Magnetic resonance imaging was performed using a 1.5T system. DWI was performed in the axial plane using echo planar imaging sequence (repetition time/echo time 1200/66, field of view 306×350 mm, reconstruction matrix 156×256, pixel size 2.0×1.4×8.0 mm) and acquired with 2 b-values (50 and 800 s/mm2). Low and high b-value DW images were analyzed visually. A lesion was positive by detection of a focal area of high signal in the rectum in high b-value images. The apparent diffusion coefficient (ADC) values of areas of high signal in high b-value images were calculated from the low and high b-value images. Results: High b-value images enabled visualization of all 15 rectal cancers. In the control group, 13 cases were classified as negative and 7 cases as positive for rectal cancer. Sensitivity for detection of rectal cancer was 100% (15/15), and specificity was 65% (13/20). The mean ADC values in 7 patients with false-positive lesions and in 15 patients with rectal cancer were 1.374×10-3 mm2/s (standard deviation [SD]: 0.157) and 1.194×10-3 mm2/s (SD: 0.152), respectively (P=0.026). Conclusion: DWI with low and high b-values may be used to screen for rectal cancer.