原发性肝癌碘油栓塞后磁共振成像表现与病理的对照研究

目的分析原发陆肝癌（HCC）碘油栓塞（TACE）后的磁共振成像（MRI）表现及其病理学基础。方法23例TACE后于术切除的HCC患者，共31个病灶。手术前1周内行MRI检查，包括SE序列T1W1、FSET2W1和FMPSPGR多回合动态增强扫描。术后沿MRI扫描平面作5～10mm层厚肿瘤连续切面和HE染色病理大切片。行MRI影像病理对照研究。结果（1）MRI表现：SE序列上病灶信号多样，且多为不均匀的混杂信号。FMPSPGR平面扫描：3个为不均匀高信号，28个为等低信号。增强早期22个强化，9个无强化。增强晚期6个部分强化。（2）病理结果：2个病灶无明显坏死，6个100％凝固性坏死，其余23个有不同程度坏死。其它病理改变包括肿瘤内坏死伴出血（10个）．纤维间隔形成（5个）、纤维包膜（12个）、炎性细胞浸润（28个）、局限性粘液样变（2个）、玻璃样变（2个）．碘油沉积（6个）。（3）MRI表现与病理对照：T1W1高信号为凝固性坏死伴（或小伴）出血、肿瘤残存；等、低信号为凝固性坏死或肿瘤残存。T2W1高信号为肿瘤残存、凝固性坏死伴出血；等信号为凝固性坏死、少量肿瘤残存、纤维间隔；低信号为凝固性坏死、纤维间隔。增强早期强化为肿瘤残存，无强化为凝固性坏死．出血、纤维间隔或少量肿瘤残仔；增强晚期强化为肿瘤残存、纤维间隔，无强化为肿瘤残存、凝固性坏死、出血。MRI各种信号区均可见炎性细胞浸润。结论（1）由于碘油栓塞后肝癌病灶的不同病理改变导致SE序列上病灶信号多种多样。T2W1低信号有特异性，代表凝固性坏死。（2）多回合动态增强扫描判断肿瘤坏死和残存较SE序列更有优势，增强早期有强化区为肿瘤残存，包膜早期明显强化可提示包膜下残存。（3）MRI能较准确的显示TACE后HCC的肿瘤坏死和残存及评价肝TACE疗效。

A comparative study of MRI manifestations and pathological changes in hepatocellular carcinoma treated by transcatheter arterial chemoembolization with lipiodol

Objective To analyze the MRI manifestations and pathological changes of hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) with lipiodol. Methods 23 patients with 31 HCC lesions treated by TACE underwent MRI examination within 1 week before their surgical resections. MRI was performed with SE sequence (T1WI and FSE T2WI) and FMPSPGR sequence dynamic multi-phase contrast scans. All resected specimens were cut into 5~10mm thick slices, corresponding to the same plane as that of MRI scans. The specimens were wholly embedded in paraffin, serial sections made and stained with hematoxylin and eosin. The MRI findings were thus compared with the pathology of the specimen sections. Results (1) MRI findings: In all 31 lesions, the signal intensity of lesions varied and was mostly heterogeneous on SE T1WI and T2WI images. Three lesions were inhomogeneous hyper-intensity and the other 28 lesions were iso- or hypo-intensity on FMPSPGR plain scannings. Twenty-two lesions were enhanced on early-phase dynamic scanning, and no enhancement was found in the other 9 lesions. Partial enhancement was also seen in 6 lesions on delay-phase dynamic scanning. (2) Pathologically, no coagulation necrosis was found in 2 specimens, but 6 lesions showed complete coagulation necrosis and 23 showed various degrees of it. The other pathological changes found included intra-tumoral hemorrhage (n=10), intra-lesional fibrotic septa formation (n=5), capsule-like fibrotic tissue proliferation around the lesions(n=12), inflammatory infiltration (n=28), focal mucoid degeneration (n=2), focal hyaline degeneration (n=2), and lipiodol retention (n=6). (3) Radiological-pathological correlation study: hyper-intense areas on T1W1 corresponded to areas of coagulation necrosis with or without hemorrhage and of residual viable tumor; iso- and hypo-intense corresponded to areas of coagulation necrosis or residual viable tumor. Hyper-intense areas on T2WI corresponded to those of residual viable tumor or coagulation necrosis with hemorrhage, and iso-intense areas corresponded to those of coagulation necrosis, small residual viable tumor or intra-lesional fibrotic septa formation, and hypo-intense areas corresponded to those of coagulation necrosis or intra-lesional fibrotic septa formation. Areas of enhancement within the lesions on the early-phase dynamic-contrast images corresponded to areas of residual viable tumors, while areas of no enhancement were those of coagulation necrosis, hemorrhage, intra-lesional fibrotic septa formation or small residual viable tumors. Areas of enhancement on the delay-phase dynamic scanning were those of residual viable tumors or intra-lesional fibrotic septa formation, while no enhancement corresponded to the areas of residual viable tumors, coagulation necrosis, and hemorrhage. Areas of enhancement on the delay-phase dynamic scanning corresponded to those areas of fibrosis tissue or residual viable tumors. Inflammatory infiltration was found in areas of different signal intensity on MRI images. Conclusions (1) Different pathological changes in HCCs after TACE are represented by various signal intensities on SE sequence images. The only area of hypo-intensity on T2WI has a specificity in representing coagulation necrosis. (2) FMPSPGR sequence dynamic MRI is superior to SE sequence in demonstrating and determining the necrosis and residual viable tumor. Enhanced areas within the lesions on the early-phase dynamic-contrast images represent residual viable tumors and the enhancement of capsule on early-phase dynamic-contrast images also represent subcapsular residual viable tumors. (3) MRI can demonstrate accurately the areas of necrosis and residual viable HCC tissues after TACE and evaluate the effect of TACE.