在体和离体胰头癌的磁共振成像表现与病理对照

目的 分析在体和离体胰头癌磁共振成像(MRI)的信号特征,研究其与大体标本及组织病理特征的相关性.方法 16例胰头癌患者行MRI检查(包括2D FLASH T1WI平扫、动态增强和抑脂TSE T2WI序列扫描),行Whipple手术切除肿瘤.新鲜手术标本再行MRI检查,扫描结束后,即将肿瘤标本按MRI检查方向完整切开,制成连续切片,分析MRI表现与大体切片和组织病理的对应关系.结果 肿瘤大小1.5 cm×2.0 cm～4.8 cm×4.2 cm,平均3.6 cm×3.1 cm.在体MRI检查:T1WI序列上,14例肿瘤呈低信号,2例呈等信号;抑脂TSE T2WI序列上,3例肿瘤呈等信号,13例肿瘤呈混杂信号;胰腺实质期增强扫描,15例强化不明显呈低信号,其中11例肿瘤周围呈环形强化;肝脏期增强扫描,9例呈不规则中等强化;增强延迟期,4例延迟强化呈等或略高信号.离体MRI检查: T1WI序列上,16例肿瘤均为低信号;在抑脂TSE T2WI序列中,均为混杂信号.MRI表现和病理的相关性:各类肿瘤成分在T1WI序列上均可为低信号,等信号区以肿瘤组织及炎性细胞为主;T2WI序列上,等低信号以纤维成分为主,略高信号以肿瘤组织和慢性炎症为主,高信号为黏液变性和受压扩张的胰腺导管.增强胰腺期环形强化是多种病理成分共同作用的结果,无明显强化区为肿瘤组织及纤维组织.肝脏期和延迟期强化以纤维成分为主.结论 胰头癌肿瘤内由多种病理成分按不同比例混合而成,MRI可揭示胰头癌的病理特征.在可切除的胰头癌肿瘤内,未见明显出血坏死的病理改变.

Comparison of MRI manifestations and histopathologic findings in pancreatic head carcinoma in vivo and ex vivo

Objective To prospectively analyze the correlation of MRI image characteristics with histopathological findings in pancreatic head carcinoma in vivo and ex vivo. Methods Sixteen patients with pancreatic head carcinoma were examined by 1.5T MRI. MR sequences included pre- and post-contrast dynamic 2D FLASH T1WI, TSE T2WI + fat suppressed (FS). All fresh specimens were scanned again within an hour after resection during the Whipple procedure, and were then cut into slices along the direction of MRI scan. The MRI image characteristics were compared with gross and histopathologic findings of the specimens. Results The tumor size ranged from 1.5 cm×2.0 cm to 4.8 cm×4.2 cm with a mean value of 3.6 cm×3.1 cm. The MRI findings in vivo showed hypointensity in 14 lesions and isointensity in 2, and on 2D FLASH T1WI and TSE T2WI, all lesions displayed mixed intensity except 3 lesions with iso-intensity. During post-contrast dynamic pancreatic parenchymal phase, 15 lesions showed mild enhancement and 11 lesions had ring enhancement sign. Nine lesions displayed progressive irregular moderate enhancement during post-contrast dynamic hepatic phase. Four lesions showed enhancement with iso- and hyperintensity in post-contrast dynamic delayed phase. The MRI findings demonstrated that all lesions ex vivo had hypointensity on 2D FLASH T1WI and mixed intensity on TSE T2WI + FS. Tumor tissues mainly displayed hypointensity, and the area containing tumor and inflammatory tissue showed iso-intensity on 2D FLASH T1WI. On T2WI + FS, the fibrosis proportion displayed hypo or isointensity, while the tumor and chronic inflammatory tissue demonstrated slight hyperintensity, and the zones of mucous degeneration or pancreatic ductal dilatation displayed hyper-intensity. The ring enhancement of tumor was caused by multiple factors and no obvious enhancement within tumor and fibrosis area were observed during post-contrast dynamic pancreatic parenchymal phase. Progressive irregular enhancement originated from desmoplastic reaction within the tumor during post-contrast dynamic hepatic phase and delayed phase, respectively. Conclusion Pancreatic head carcinomas contain various kinds of tissues. MRI can reveal these pathologic characteristics. No obvious hemorrhage and necrosis within the tumor were observed in this series.