Diffusion-weighted MRI in bladder carcinoma: the differentiation between tumor recurrence and benign changes after resection.
OBJECTIVE
To investigate the efficacy of diffusion-weighted MRI (DWI) in differentiating recurrent tumor from chronic inflammation and fibrosis after cystectomy or transurethral resection of bladder cancer.


METHODS
Eleven patients with suspected tumor recurrence underwent pelvic DWI and dynamic contrast-enhanced (DCE) MRI at 3 months to 7 years following bladder cancer resection. The diagnosis was histologically confirmed in all patients by transurethral or cystoscopic resection of 27 lesions within 2 weeks of MR examinations.


RESULTS
The accuracies, sensitivities, specificities, and positive predict values of DWI (92.6%, 100%, 81.8%, and 88.9%) were higher than those of DCE MRI (59.3%, 81.3%, 27.3%, and 54.2%) for detecting recurrent tumors. Using receiver operating characteristic analysis, the accuracy of DWI was significantly higher than that of DCE MRI (P < 0.05). There was no significant difference between DWI diagnosis and histopathology (P > 0.05), whereas the difference between diagnosis of DCE MRI and histopathology was significant (P < 0.05). The normalized apparent diffusion coefficients of recurrent tumors (0.697 ± 0.219) were significantly (P < 0.05) lower than those of postoperative inflammation or fibrosis (1.019 ± 0.143).


CONCLUSIONS
DWI is superior to DCE MRI for differentiating recurrent bladder tumors from postoperative inflammation or fibrosis. DWI can be included in the follow-up MRI protocol after bladder cancer surgery.
Department of Radiology, The First Affiliated Hospital of Sun Yat-sen University, 58 Zhongshan Road 2, Guangzhou, Guangdong, People's Republic of China.
Huan-jun
HJ
Wang
Margaret H
MH
Pui
Yan
Y
Guo
Dong
D
Yang
Bi-tao
BT
Pan
Xu-hui
XH
Zhou
D000368:Aged; D015653:Cystectomy; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005355:Fibrosis; D006801:Humans; D007089:Image Enhancement; D007249:Inflammation / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D001743:Urinary Bladder / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis* / Q000473:pathology