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Turkish Journal of Medical Sciences

DOI

10.3906/sag-1609-59

Abstract

Background/aim: This study aimed to differentiate rectal mucinous carcinoma (MC) from nonmucinous rectal adenocarcinoma (AC) using mean apparent diffusion coefficient (mADC) values obtained with diffusion-weighted imaging.Materials and methods: Sixty-two pathologically confirmed rectal AC (n = 44) and MC (n = 18) patients were included in this study. The two groups underwent pelvic MRI to determine the local staging baseline for rectal tumors. Once the region of interest (ROI) was determined, a border was drawn around each hyperintense tumor (b = 1000 s/mm2 images). Following a repeat of this procedure for each patient, the ROIs were recorded to apparent diffusion coefficient (ADC) maps, and mADC values were measured. The mADC was determined per slice, followed by a calculation of whole tumor volume ADC mean using the individual mADC values. The Mann?Whitney test was performed to compare mADCs for the two groups. A receiver operating characteristic (ROC) curve was generated to determine the differentiating capacity of ADCs from MC to AC. Results: The mADC was higher in MC (1.631 $\pm$ 0.375 x 10-3 mm2/s) (range: 0.95-2.36 x 10-3 mm2/s) than in AC (0.921 $\pm$ 0.157 x 10-3 mm2/s) (range: 0.6-1.48 x 10-3 mm2/s) (P < 0.001). mADCs were effective in distinguishing MC from AC (area under the ROC curve, 0.972 (95% CI : 0.928-1.00)). A threshold of 1.27 x 10-3 mm2/s was set that corresponded with high sensitivity (94.4%) and specificity (97.7%). Twelve MCs (67%) were predominantly hypointense, and 6 MCs (33%) were seen as mixed signal intensity lesions. Forty ACs (91%) were observed as hyperintense lesions, and 4 ACs (9%) had mixed signal intensity. There was a significant difference in the signal intensities between MC and AC (c2 = 54.7, P < 0.001).Conclusion: MCs and ACs show different diffusion characteristics, which can be distinguished with high sensitivity and specificity and can help to improve prognostic treatment options.

Keywords

Rectal cancer, adenocarcinoma, mucinous adenocarcinoma, diffusion-weighted imaging, apparent diffusion coefficient

First Page

1520

Last Page

1525

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