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

Abstract

Purpose: The purpose of this study was to assess the potential role of diŠusion-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 W echo time 1200 W 66,ˆeld 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 W mm 2 ). 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 diŠusion coe‹cient (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 classiˆed as negative and 7 cases as positive for rectal cancer. Sensitivity for detection of rectal cancer was 100z (15 W 15), and speciˆcity was 65z (13 W 20). The mean ADC values in 7 patients with false-positive lesions and in 15 patients with rectal cancer were 1.374×10 -3 mm 2 W s (standard deviation [SD]: 0.157) and 1.194×10 -3 mm 2 W s (SD: 0.152), respectively (P＝0.026).Conclusion: DWI with low and high b-values may be used to screen for rectal cancer.

Acute pancreatitis successfully diagnosed by diffusion-weighted imaging: A case report

“…DWI has been applied in the diagnosis of brain ischemia and brain tumors [7][8][9][10][11] . Recent technical development in MRI has expanded the utility of DWI in examinations of the liver, kidney, breast, etc [12][13][14][15][16] . The apparent diffusion coefficient (ADC) is a quantitative parameter, which reflects the microenvironment of diffusing water molecules.…”

“…Diffusion-weighted imaging (DWI) is an established diagnostic tool of acute stroke and brain tumors [7][8][9][10][11] . Due to the latest technical advances in magnetic resonance imaging (MRI), DWI has also been applied in detecting various disorders of abdominal organs [12][13][14][15][16] . This report describes the efficacy of DWI in evaluation of acute pancreatitis.…”

Can diffusion-weighted MRI determine complete responders after neoadjuvant chemoradiation for locally advanced rectal cancer?

“…Therefore, it was impossible to identify detailed rectal wall layers on highb-value DW-MR images alone, as the background signal intensity was suppressed, especially in the normal rectal wall. Moreover, we used a high b-value of 800 s/mm 2 compared to 1000 s/mm 2 , and therefore it is possible that the sensitivity of this technique was decreased by the presence of patients with false-positive results (33,34).…”

Diffusion-Weighted Imaging in the Detection of Lymph Node Metastasis in Colorectal Cancer

“…Despite advances in the magnetic resonance imaging (MRI) technique, only a few reports have evaluated the use of DWI in diagnosing colorectal cancer Hosonuma et al 2006). Furthermore, no reports have eval-uated the use of DWI in detecting lymph node metastases from colorectal cancer.…”