高分辨磁共振成像结合弥散加权成像对直肠癌术前诊断的价值

目的探讨高分辨磁共振成像（MRI）结合横轴位磁共振弥散加权成像（DWI）对直肠癌术前诊断的价值。方法对疑诊直肠癌的55例患者进行前瞻性研究，术前进行高分辨MRI检查，并采用b值分别为600、1000s／mm2对患者进行DWI检查，测量瘤体的表观弥散系数（ADC）值；将影像结果与术后病理作对照。选取15例非直肠病变患者，将正常直肠壁与直肠癌的ADC值进行对照。结果高分辨MRI诊断直肠癌的灵敏度、特异度及符合率分别为95．7％（45／47）、50．0％（4／8）、89．1％（49／55）。高分辨MRI结合DWI诊断直肠癌的灵敏度、特异度及符合率分别为100．0％（47／47）、75．0％（6／8）、96．4％（53／55）。高分辨MRI对直肠癌T分期诊断总准确度为88．9％（40／45），对T2和T3期诊断准确度分别为87．5％（14／16）和89．6％（26／29）。同一b值下正常直肠壁与直肠癌瘤体的ADC值差异有统计学意义（P〈0．05）；同一b值下不同分化级别直肠癌的ADC值差异无统计学意义（P〉0．05）。结论高分辨MRI结合DWI对直肠癌术前诊断及T分期具有较高的诊断价值，DWI可以作为诊断直肠癌的重要补充序列。

Value of high resolution MRI with DWI in the preoperative diagnosis of rectal cancer

Objective To evaluate the value of high resolution MR imaging (MRI) with diffusion weighted imaging (DWI) in the preoperative diagnosis of rectal cancer. Methods 55 patients with rectal cancer may underwent high resolution MRI examinations before surgical operation, and with DWI (b=600, 1000 s/mm2). The apparent diffusion coefficient (ADC) of the tumors were measured. The image findings were compared with pathology. Select 15 patients without rectal lesion, ADC value of the tumors and normal rectal wall were measured. Results High resolution MRI diagnosis rectal cancer sensitivity, specific degree and coincidence rate were 95.7% (45/47), 50.0% (4/8), 89.1% (49/55), high resolution MRI with DWI diagnosis colorectal cancer sensitivity, specific degree and coincidence rate were 100.0 % (47/47), 75.0 % (6/8), 96.4 % (53/55). The high resolution MRI tumor T-staging agreed with the histological stage that was 88.9% (40/45), the diagnosis of T2 stage was 87.5 % (14/16), the diagnosis of T3 stage was 89.6 % (26/29). The same b-valued under the ADC values of rectal cancer tumors and the normal rectal were different (P ＜0.05). No correlation can be pointed out between ADC and pathological classification of each tumor.Conclusion High resolution MRI with DWI for the rectal cancer preoperative diagnosis and T-staging has higher diagnostic accuracy, DWI can serve as an important supplement sequence of colorectal cancer diagnosis.