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





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.<br> Methods: The subjects were 15 patients diagnosed endoscopically with rectal cancer (<i>m</i> in 1 patient, <i>sm</i> in 0, <i>mp</i> in 3, <i>ss</i> in 7, <i>se</i> in 1, <i>a</i> 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/mm<sup>2</sup>). 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.<br> 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<sup>-3</sup> mm<sup>2</sup>/s (standard deviation [SD]: 0.157) and 1.194×10<sup>-3</sup> mm<sup>2</sup>/s (SD: 0.152), respectively (<i>P</i>=0.026).<br> Conclusion: DWI with low and high b-values may be used to screen for rectal cancer.<br>


  • Magnetic resonance in medical sciences : MRMS

    Magnetic resonance in medical sciences : MRMS 5(4), 173-177, 2006-12-31

    Japanese Society for Magnetic Resonance in Medicine

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