Department of Urology, Mansoura University, Mansoura, Egypt.
BJU Int. 2012 Dec;110(11 Pt B):E622-7. doi: 10.1111/j.1464-410X.2012.11345.x. Epub 2012 Jul 3.
What's known on the subject? and What does the study add? Diffusion-weighted (DW) MRI is a non-invasive technique measuring the microscopic mobility of water molecules in the tissues without contrast administration. It provides information on perfusion and diffusion simultaneously in any organ, so it can be used to differentiate normal and abnormal tissue structure, and it might help in the characterization of various abnormalities. In recent years, DW-MRI has been applied in the evaluation of urinary tract lesions, such as malignant renal, prostatic and bladder tumours; however, it has not previously been tested on its ability to distinguish residual cancer from fibrotic and inflammatory changes secondary to transurethral resection (TUR) and intravesical chemotherapy, both of which manifest as bladder-wall thickening on T2-weighted MRI. This is the first study to show the feasibility of DW-MRI in follow-up of patients with superficial bladder tumours after TUR. DW-MRI was highly reliable in differentiating post-TUR inflammatory changes from bladder tumours, with results similar to those of conventional cystoscopy. This non-invasive method could be used efficiently in future for follow-up of this patient group and may obviate the need for routine cystoscopy.
• To study the feasibility of using diffusion-weighted (DW) magnetic resonance imaging (MRI) in bladder cancer follow-up after transurethral resection (TUR).
• Included in the study were 47 patients with a history of TUR of superficial bladder carcinoma, who were admitted to our centre between January and December 2011 for follow-up cystoscopy. • Before cystoscopy, DW-MRI was performed and the apparent diffusion coefficient (ADC) value was measured in a circular region of interest within the carcinoma and normal bladder wall. • Two radiologists, blinded to the results of cystoscopy, independently interpreted the DW images. • A comparison of imaging findings with those of cystoscopy was performed using the McNemar test.
• In our 47 patients, cystoscopy identified 34 bladder lesions in 24 patients and in the remaining 23 the bladder looked normal. • In the 24 patients with malignant bladders, DW-MRI detected 32/34 tumours with two false-negative findings of lesions in two patients. • In 23 patients with non-malignant bladders, the DW-MRI data were accurate for 21 patients, as two patients were misdiagnosed as malignant. • The sensitivity, specificity, accuracy, positive and negative predictive values of DW-MRI for identifying bladder tumours were 91.6% (22/24), 91.3% (21/23), 91.5% (43/47), 91.6 (22/24) and 91.3 (21/23), respectively. • Using the McNemar test there was no significant difference between DW-MRI and cystoscopy.
• DW-MRI has a high reliability in differentiating post-TUR inflammatory changes from bladder tumours, which is similar to that of cystoscopy. • DW-MRI could be a first-line diagnostic test in follow-up of patients after TUR.
• 研究弥散加权（DW）磁共振成像（MRI）在经尿道切除（TUR）后膀胱癌随访中的应用可行性。
• 纳入 2011 年 1 月至 12 月在本中心接受 TUR 治疗的浅表膀胱癌患者 47 例，进行随访性膀胱镜检查。• 在膀胱镜检查前，对患者进行 DW-MRI 检查，并在癌灶和正常膀胱壁的圆形感兴趣区内测量表观弥散系数（ADC）值。• 两位放射科医生在不了解膀胱镜检查结果的情况下，分别对 DW 图像进行独立解读。• 采用 McNemar 检验比较影像学结果与膀胱镜检查结果。
• 在 47 例患者中，膀胱镜检查在 24 例患者中发现 34 个膀胱病变，在其余 23 例患者中膀胱镜检查正常。• 在 24 例有恶性膀胱病变的患者中，DW-MRI 检测到 34 个肿瘤中的 32 个，有 2 个患者的 2 个病变漏诊。• 在 23 例无恶性膀胱病变的患者中，DW-MRI 数据在 21 例患者中准确，有 2 例患者被误诊为恶性。• DW-MRI 对膀胱癌的识别具有较高的敏感性（91.6%，22/24）、特异性（91.3%，21/23）、准确性（91.5%，43/47）、阳性预测值（91.6%，22/24）和阴性预测值（91.3%，21/23）。• 采用 McNemar 检验，DW-MRI 与膀胱镜检查之间无统计学差异。
• DW-MRI 在区分 TUR 后炎症性改变与膀胱癌方面具有较高的可靠性，与膀胱镜检查相似。• DW-MRI 可能成为 TUR 后患者随访的一线诊断性检查方法。
