磁共振血管成像评价肝移植术后血管形态：11例分析

背景:多数学者认为超声发现血栓形成和血管狭窄的灵敏度比较高,但对血管吻合口的直接显示较困难,磁共振血管造影对血管解剖的显示及并发症的诊断优于多普勒超声。目的:观察磁共振血管造影对肝移植术后血管形态的显示及其对并发症的评估。设计:观察对比实验。单位:南方医科大学附属南方医院影像中心。对象:选择2004-01/2006-12于南方医科大学附属南方医院影像中心收治的11例男性原位肝移植术后患者。年龄40～58岁,平均49岁。术前临床诊断为原发性肝癌2例,重症肝硬化9例,均经病理组织学检测证实,其中9例行原位经典式肝移植,2例行背驮式原位肝移植术。所有患者均对检测项目知情同意。方法:对11例原位肝移植术后患者均用磁共振快速自选回波序列及快速小角度激发梯度回波序列常规扫描、钆喷替酸葡甲胺动态增强3D磁共振血管造影检查,在MRA成像后,迅速采用与平扫FLASH T1WI抑脂序列完全相同参数行轴面和冠状面扫描。根据ECST法计算血管直径狭窄率S(S=[(D-d)/D]×100%),d为最狭窄处内径,D为该处正常管径。判断狭窄的程度:直径狭窄率S在0～30%为正常范围;31%～50%为轻度狭窄;51%～85%为中度狭窄;86%～100%为重度狭窄。分析各序列图像特点。同时行多普勒超声检查。主要观察指标:①磁共振血管造影观察肝移植术后血管形态及对并发症的评估结果。②多普勒超声检查结果。结果:纳入患者11例全部进入结果分析。①磁共振血管造影:显示3例肝动脉、门静脉和下腔静脉吻合口通畅,其中1例供体门静脉管径略小于受体门静脉,1例肝移植术后早期MRT2WI图像见到门静脉周围高信号,持续3周后消失。其余8例中,2例肝动脉过长迂曲,2例肝动脉供体端瘤样轻度扩张,2例门静脉轻度狭窄,位于吻合口,且门静脉供体段与受体段的管径不相等,门静脉肝内分支均正常,2例肝静脉末梢分支杵状扩张,而其下腔静脉未见异常。1例下腔静脉血栓,磁共振血管造影表现为高信号血管腔内椭圆形低无信号区。2例肝静脉末梢分支杵状扩张患者半年后肝静脉末梢分支扩张程度降低,但仍有轻度扩张,下腔静脉血栓治疗1月后复查血栓消失。②多普勒超声检测:1例肝动脉过长迂曲合并肝动脉供体端瘤样轻度扩张诊断为肝动脉过长迂曲,例门静脉轻度狭窄1例诊断为正常,1例诊断为可疑狭窄。未发现肝静脉末梢分支杵状扩张。其余诊断与磁共振血管造影相符。结论:磁共振血管造影可清楚显示肝移植术后血管解剖并准确、快速诊断肝移植术后出现的血管并发症。

Evaluation of vascular system using MR angiography after liver transplantation: Analysis of 11 cases

BACKGROUND: Sonography is believed by many scholars to be sensitive for the detection of hepatic arterial thrombosis and stenosis, but it is difficult to show the anastomotic vascular stenosis. MR angiography is better than sonography in the display of vascular anatomy and the diagnosis of various vascular complications after liver transplantation.OBJECTIVE: To evaluate the role of MR angiography (MRA) in the display of vascular anatomy and the diagnosis of various vascular complications after liver transplantation.DESIGN: Contrast trial observation.SETTING: Medical Imaging Center of Nanfang Hospital, Southern Medical University.PARTICIPANTS: Eleven adult male patients had undergone liver transplantations at Nanfang Hospital of Southern Medical University between January 2004 and December 2006. They ranged in age from 40 to 58 years, average 49 yeas. Original causes of liver failure in the study group included cirrhosis (n =9) and primal hepatic carcinoma (n =2) diagnosed by pathohistological methods. And 9 cases had undergone orthotopic liver transplantations while 2 cases with piggy-back liver transplantation.METHODS: Eleven consecutive adult patients underwent MR imaging examinations after orthotopic liver transplantation using a breath-hold 2D True Fast Imaging with Stead-state Precession and Fast Low Angle Shot. MR triphasic contrast-enhanced 3D imaging was also performed. Enhancement scan: A final gadolinium-enhanced axial and coronal T1WI spin-echo sequence with spectral fat saturation was performed after completion of the MRA. The vascular diameter stenosis was calculated according to S (S=[(D-d)/D]×100%) by ECST method, d as the inner diameter of the most obvious stenosis while D as normal diameter. Degree of stenosis: normal as S 0-30%, mild stenosis as S 31%-50%, moderate stenosis as S 51%-85%, and severe stenosis as S 86%-100%. Then the imaging findings after liver transplantation were analyzed. Meanwhile the sonography was performed.MAIN OUTCOME MEASURES: ① MR Image analysis of vascular anatomy and vascular complications after liver transplantation.②Normal findings after liver transplantation by using sonography.RESULTS: All 11 patients were involved in the result analysis.①MRA: The anastomosis of hepatic artery, portal vein and inferior vena cava were smooth in 3 cases. The high signal intensity was seen around portal vein at T2WI in 1 case with a shorter interval after transplantation and persisted 3 weeks. In 1 case, the caliber of the donor portion was smaller than the recipient portion. Among other 8 cases, hepatic artery complication included hepatic artery winding in 2 cases and aneurysm formation of donor's hepatic artery in 2 cases, but the twig of the hepatic artery was normal. Mild Portal vein stenosis at the anastomosis was found in 2 cases, caused by the different calibers of the donor portion from the recipient portion, but the inter-hepatic branches of the portal vein were normal. Clubbed dilatation of hepatic veins end-brush was depicted in 2 cases whose inferior vena cava at the anastomosis was not stenosis. Inferior vena cava thrombosis was found in 1 case. The thrombus displayed the low signal intensity in the high signal intensity of inferior vena cava. By follow-up examination, the degree of clubbed dilatation of hepatic veins end-brush reduced after half a year and inferior vena cava thrombosis disappeared by treatment. ②Sonography: By ultrasound examination, 1 case who had hepatic artery winding combining to aneurysm formation of donor's hepatic artery was discovered just hepatic artery winding. In 2cases that had mild portal vein stenosis at the anastomosis, 1 case was diagnosed normal while the other was not affirmed. The clubbed dilatation of hepatic veins end-brush was not depicted. The others were same as MRI diagnosis.CONCLUSION: Dynamic enhanced 3D MRA imaging can provide a comprehensive assessment of vascular anatomy in most recipients of liver transplants, and is an accurate and quick method to diagnose the vascular complication after liver transplantation.