Variations in feeding arteries of hepatocellular carcinoma located in the left hepatic lobe

The left hepatic lobe is divided into three subsegments according to anatomical landmarks; however, there are several variations in the vascular territories of the left hepatic arterial branches. Hepatocellular carcinoma (HCC) located near the umbilical fissure or at the left side of the umbilical portion of the left portal vein has frequent crossover blood supply. HCC located in the caudal aspect of the lateral segment has a variety of feeding arteries, and is infrequently supplied by the caudate artery or the medial subsegmental artery (A4), and by the lateral left hepatic arteries. HCC located in the posterior aspect of segment 4 is frequently supplied by the caudate artery or a small A4 branch arising from the caudate artery. In addition, the left inferior phrenic, right and left internal mammary, right and left gastric, cystic, and omental arteries are well known extrahepatic collateral pathways supplying HCC in the left hepatic lobe, especially when the hepatic artery is attenuated by previous transcatheter arterial chemoembolization (TACE). Interventional radiologists should have sufficient knowledge of vascular territories in the left hepatic arterial branches and extrahepatic collaterals to perform effective TACE for HCC located in the left hepatic lobe.     

Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography

Seo TS, Oh JH, Lee DH, et al. Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography. Invest Radiol 2001;36:186-192.RATIONALE AND OBJECTIVES: The radiologic anatomy of rabbit liver has received little study but is important in many experimental investigations. METHODS: Twenty-four rabbits were studied by using hepatic venograms, aortograms, hepatic arteriograms, cholangiograms, and portograms. RESULTS: In all cases, the right, middle, and left hepatic veins drained into the inferior vena cava just below the diaphragm, and the caudate lobe hepatic vein drained more inferiorly. The proper hepatic artery was a branch of the common hepatic artery in 96%. The first branch of the proper hepatic artery was the caudate lobe artery. The remaining main hepatic artery was divided into the right and left hepatic arteries. The left hepatic artery was further divided into the medial and lateral segmental branches in 95%. The anatomy of the portal vein or bile duct was the same as the hepatic artery in 100% of cases. CONCLUSIONS: Knowledge of the normal patterns and variations of the vessels and bile duct will be helpful for experiments of the rabbit liver in future studies.     

Arterial blood supply to the posterior aspect of segment IV of the liver from the caudate branch: demonstration at CT after iodized oil injection

PURPOSE: To retrospectively evaluate the arterial blood supply to the posterior aspect of segment IV of the liver with computed tomography (CT) after transcatheter arterial chemoembolization (TACE) with iodized oil through the caudate arterial branch of the liver for treatment of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Institutional review board approval and patient informed consent were not required for this retrospective study. Twenty-four patients (11 men and 13 women; mean age, 68 years) with HCC originating in the caudate lobe (n = 23) or posterior aspect of segment IV (n = 1) were selected. TACE of the caudate arterial branch was performed in all patients, including one patient with HCC in the posterior aspect of segment IV who underwent TACE of the caudate arterial branch after CT helped confirm that iodized oil was not distributed in the tumor after TACE of the medial segmental artery. The distribution of iodized oil in the posterior aspect of segment IV was analyzed with CT 1 week after TACE. The number and origin of all arteries supplying the caudate lobe and the number of arteries embolized were determined. RESULTS: Thirty-three caudate arterial branches were embolized. Twenty-nine branches were derived from the right hepatic artery and four were derived from the left hepatic artery. A single branch was seen in 17 patients, two branches were seen in five, and three branches were seen in two. Eight patients simultaneously underwent additional TACE of branches of the right hepatic artery (n = 6) or right inferior phrenic artery (n = 2). At CT, iodized oil was seen to be distributed entirely (n = 19) or partially (n = 5) in the caudate lobe. Distribution of iodized oil at the posterior aspect of segment IV was observed in 16 patients (67%), including 13 (54%) whose caudate arterial branches were derived entirely from the right hepatic artery. CONCLUSION: The results of this study suggest that the caudate arterial branch, which is mainly derived from the right hepatic artery, frequently supplies the posterior aspect of segment IV. This knowledge is important for managing HCC in the posterior aspect of segment IV by means of TACE.     

单通道双支架植入技术治疗肝门部胆管癌

目的 探讨单通道双支架植入技术治疗肝门部胆管癌的可行性和临床应用价值。方法 18例肝门部胆管癌患者，左、右肝管起始部狭窄或闭塞。采用右腋中线入路穿刺右肝管，用导丝寻找右肝管与左肝管和胆总管之间的潜在腔隙，于左右肝管间以及右肝管-胆总管间分别植入支架。结果 18例患者均从右腋中线穿刺通道成功植入右肝管-左肝管间及右肝管-胆总管间的支架，实现了胆汁经左肝管-右肝管-胆总管的完全内引流，解除梗阻疗效显著。结论 单通道双支架植入技术简化了高位胆管梗阻介入件引流的操作，减少了操作创伤，缩短了操作时间，具有较高的临床实用价值。     

Predicting biliary complications in right lobe liver transplant recipients according to distance between donor's bile duct and corresponding hepatic artery

PURPOSE: To retrospectively determine whether biliary complications in recipients of living-donor right lobe liver grafts can be predicted at pretransplantation donor computed tomography (CT). MATERIALS AND METHODS: The human research committee approved this study. The requirement for informed consent was waived. Multi-detector row CT cholangiography and CT angiography were performed in 44 consecutive right lobe liver donors (25 men, 19 women; mean age, 37 years). When CT cholangiography in the donor demonstrated the right biliary anatomy (conventional or variant), the shortest distance between the right main (or second-order) hepatic artery and the corresponding right main (or second-order) bile duct was measured and compared with posttransplantation biliary complications in the transplant recipient by using generalized estimating equations. RESULTS: In 22 transplant recipients with one right main duct-to-common duct anastomosis (ie, conventional donor anatomy), the distance between the donor's right main bile duct and hepatic artery generally was small (mean distance, 3.8 mm; range, 1-14 mm) and unrelated (P=.46) to biliary complications (n=6). In 22 recipients who required two second-order right duct anastomoses (ie, with variant donor anatomy), the distance between the donor's second-order duct and corresponding hepatic artery was more variable (mean distance, 6.6 mm; range, 1-32.5 mm), and biliary complications were significantly more common when this distance was 10 mm or greater (in eight of 13 ducts with conventional anatomy and four of 31 ducts with variant anatomy, P<.05). CONCLUSION: Right lobe liver graft recipients who have variant right biliary anatomy and a second-order bile duct 10 mm or farther from the corresponding hepatic artery are at high risk for biliary complications, possibly because of a predisposition to ischemic injury.     

Value of MRI in three patients with major vascular injuries after laparoscopic cholecystectomy

The aim of this study was to describe three cases of major vascular injuries after laparoscopic cholecystectomy depicted on magnetic resonance (MR) examination. Three female patients (mean age, 32 years; range, 22–39 years) were studied with clinical suspicion of bilio-vascular injuries after laparoscopic cholecystectomy. All MR examinations were performed within 24 h after the laparoscopic procedure. MR imaging was evaluated for major vascular injuries involving the arterial and portal venous system, for bile duct discontinuity, presence or absence of biliary dilation, stricture, excision injury, free fluid and collections. In the first patient, a type-IV Bismuth injury with associated intrahepatic bile ducts dilation was observed. Contrast-enhanced MR revealed lack of enhancement in the right hepatic lobe due to occlusion of the right hepatic artery and the right portal branch. This patient underwent right hepatectomy with hepatico-jejunostomy. In the other two cases, no visualization of the right hepatic artery and the right portal branch was observed on MR angiography. In the first case, the patient underwent right hepatectomy; in the second case, because of stable liver condition, the patient was managed conservatively. MR imaging combined with MR angiography and MR cholangiography can be performed emergently in patients with suspicion of bilio-vascular injury after laparoscopic cholecystectomy allowing the simultaneous evaluation of the biliary tree and the hepatic vascular supply that is essential for adequate treatment planning.     

Altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein: evaluation with Doppler US in 14 patients

PURPOSE: To evaluate with Doppler ultrasonography (US) the altered hepatic hemodynamics caused by temporary occlusion of the right hepatic vein. MATERIALS AND METHODS: The study group consisted of 14 patients being considered for hepatic arterial infusion or transarterial embolization. In all patients, maximum peak velocity of the blood flow in the right portal vein was measured with Doppler US before and during the occlusion of the right hepatic vein. In 13 patients, color Doppler US was performed to evaluate Doppler signal in the portal venous branch in the occluded area before and during occlusion. Average peak velocity in the right hepatic artery in eight patients was measured by using a transducer-tipped guide wire before and during occlusion. RESULTS: Maximum peak velocity of the right portal vein significantly decreased with occlusion (P <.01). Hepatic venous occlusion changed the Doppler signal in the portal venous branch in the occluded area from hepatopetal to no signal in 10 patients; to weakened hepatopetal in two; and to hepatofugal in one. Average peak velocity of the right hepatic artery showed a decrease or plateau for 15-30 seconds after the start of occlusion and then a rapid increase to reach a plateau at around 75-90 seconds, with 1.5-2 times as much velocity as that before occlusion. CONCLUSION: Increase in hepatic arterial velocity is accompanied by a decrease in the portal velocity with temporary occlusion of the right hepatic vein; the expected increased drainage through the portal vein was almost undetectable.     

Main Bile Duct Stricture Occurring After Transcatheter Arterial Chemoembolization for Hepatocellular Carcinoma

The purpose of this study was to evaluate the clinical course of main bile duct stricture at the hepatic hilum after transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). Among 446 consecutive patients with HCC treated by TACE, main bile duct stricture developed in 18 (4.0%). All imaging and laboratory data, treatment course, and outcomes were retrospectively analyzed. All patients had 1 to 2 tumors measuring 10 to 100 mm in diameter (mean ± SD 24.5 ± 5.4 mm) near the hepatic hilum fed by the caudate arterial branch (A1) and/or medial segmental artery (A4) of the liver. During the TACE procedure that caused bile duct injury, A1 was embolized in 8, A4 was embolized in 5, and both were embolized in 5 patients. Nine patients (50.0%) had a history of TACE in either A1 or A4. Iodized oil accumulation in the bile duct wall was seen in all patients on computed tomography obtained 1 week later. Bile duct dilatation caused by main bile duct stricture developed in both lobes (n = 9), in the right lobe (n = 3), in the left lobe (n = 4), in segment (S) 2 (n = 1), and in S3 (n = 1). Serum levels of alkaline phosphatase and γ-glutamyltranspeptidase increased in 13 patients. Biloma requiring drainage developed in 2 patients; jaundice developed in 4 patients; and metallic stents were placed in 3 patients. Complications after additional TACE sessions, including biloma (n = 3) and/or jaundice (n = 5), occurred in 7 patients and were treated by additional intervention, including metallic stent placement in 2 patients. After initial TACE of A1 and/or A4, 8 patients (44.4%), including 5 with uncontrollable jaundice or cholangitis, died at 37.9 ± 34.9 months after TACE, and 10 (55.6%) have survived for 38.4 ± 37.9 months. Selective TACE of A1 and/or A4 carries a risk of main bile duct stricture at the hepatic hilum. Biloma and jaundice are serious complications associated with bile duct strictures.     

Biliary anatomy in potential right hepatic lobe living donor liver transplantation (LDLT): the utility of CT cholangiography in the setting of inconclusive MRCP

Objective

To determine the utility of CT cholangiography (CT-Ch) in preoperative evaluation of the biliary anatomy of living-donor liver transplantation (LDLT) donors when magnetic resonance cholangiopancreatography (MRCP) is inconclusive.

Materials and methods

Over a 2-year period, 22 potential living liver donors underwent contrast-enhanced CT-Ch for preoperative evaluating biliary anatomy due to inconclusive results on MRCP and subsequently donated their right hepatic lobe. Nineteen of them underwent intraoperative cholangiography and were included in this study. Two radiologists retrospectively reviewed both MRCP and CT-Ch with 1-month interval and documented the types of bile duct branching patterns and visualization score of intrahepatic bile ducts (4-point scale).

Results

There were no complications associated with CT-Ch examinations. CT-Ch was concordant with the reference standard in 18/19 (95%) including 7/8 typical branching type and 11/11 anomalous branching types. MRCP was concordant with the reference standard in 14/19 (74%) including 4/8 typical branching types and 10/11 anomalous branching types. The discordant case by CT-Ch was the identification of a tiny accessory right intrahepatic duct joining the common bile duct which was not visualized on intraoperative cholangiography. CT-Ch showed higher visualization score (mean, 3.9) than MRCP (mean, 2.6) (P < .001).

Conclusion

CT-Ch can be effectively used for the depiction of the branching pattern of the bile duct at the hepatic hilum when MRCP is inconclusive.     

Pseudo-obstruction of the extrahepatic bile duct due to artifact from arterial pulsatile compression: a diagnostic pitfall of MR cholangiopancreatography

PURPOSE: To evaluate the frequency of artifact from arterial pulsatile compression as the cause of pseudo-obstruction of the extrahepatic bile duct at magnetic resonance (MR) cholangiopancreatography (MRCP) and specify the causative vessels. MATERIALS AND METHODS: In 234 patients (102 men, 132 women; age range, 25-80 years), MRCP images obtained by using a single-shot turbo spin-echo sequence were reviewed to assess pseudo-obstruction of the extrahepatic bile duct caused by vascular compression. Dual-phase spiral computed tomography, contrast material-enhanced three-dimensional MR angiography, and/or digital subtraction angiography also were performed to determine the vessel that caused the pseudo-obstruction. RESULTS: Thirty-six pseudo-obstructions due to vascular compression were found in 33 (14%) patients. The common hepatic duct (27 [75%] sites) was the most common pseudo-obstruction site, followed by the left hepatic duct (four [11%] sites), proximal common bile duct (three [8%] sites), and right hepatic duct (two [6%] sites). The causative vessels were identified as the right hepatic artery at 24 (67%) sites; gastroduodenal artery, two (6%) sites; cystic artery, two (6%) sites; proper hepatic artery, one (3%) site; and an unspecified branch of the common hepatic artery, seven (19%) sites. CONCLUSION: At MRCP, pseudo-obstruction of the extrahepatic bile duct can be caused by pulsatile vascular compression of the hepatic and gastroduodenal arteries, and it should not be misdiagnosed as a bile duct tumor or biliary stone.     

Hepatocellular carcinoma in the caudate lobe of the liver: variations of its feeding branches on arteriography

There are usually multiple caudate arteries arising from the right, left, and middle hepatic arteries, and they are frequently connected to each other. Therefore, hepatocellular carcinoma (HCC) in the caudate lobe is frequently fed by multiple branches arising from different origins. HCC located in the Spiegel lobe is usually fed by the caudate arteries derived from the right and/or left hepatic artery. HCC in the paracaval portion is mainly fed by the caudate artery derived from the right hepatic artery; with low frequency, it is fed by the caudate artery derived from the left hepatic artery. HCC in the caudate process is usually fed by the caudate artery derived from the right hepatic artery. Because of the complexity and overlap of vascular territories, the tumor-feeding branch of a recurrent HCC lesion in the caudate lobe frequently changes on follow-up arteriograms. In addition, several extrahepatic collateral vessels supply the recurrent tumor. To perform effective transcatheter arterial chemoembolization (TACE) for HCC in the caudate lobe, radiologists should have sufficient knowledge of vascular anatomy supplying HCC in the caudate lobe.     

磁共振3D-VIBE序列联合MRCP在肝门部胆管癌T1期中的诊断价值

目的 探讨磁共振三维容积式内插法屏气检查序列(3D-VIBE)联合磁共振胆胰管成像(MRCP)在肝门部胆管癌T1期中的诊断价值. 资料与方法 回顾性分析经手术病理证实的T1期肝门胆管癌16例,术前均经MR 3D-VIBE三期增强扫描和MRCP检查,复习MR肝门部胆管癌T1期3D-VIBE三期增强扫描和MRCP的影像学表现并与手术病理作对照. 结果 16例T1期肝门部胆管癌中,单纯发生于肝管汇合部7例;同时侵及左肝管4例,侵及右肝管2例;肝管汇合部未见病灶,仅发生于左肝管2例,右肝管1例.肿瘤呈结节状3例,结节合并浸润状2例,单纯浸润状11例;局部淋巴结增大5例,胆囊萎缩2例.MRI T1WI平扫呈等信号4例,稍低信号12例,T2WI呈等信号2例,稍高信号14例;MRCP表现为肝门部胆管截断3例,其上肝内外胆管呈"软藤样"扩张;肝门部胆管狭窄、变细4例,狭窄呈"鼠尾状"或"矛尖状",肝左右叶扩张的胆管在肝门部不能汇合;肝外二级胆管狭窄9例,狭窄段以上胆管不同程度扩张.3D-VIBE三期增强扫描动脉早期肿瘤轻度强化,动脉晚期和门静脉期中到明显强化. 结论 MR 3D-VIBE联合MRCP检查能够提高T1期肝门部胆管癌的检出率.有助于指导临床术前制定合理的手术方案.     

肝癌介入治疗中肝动脉狭窄闭塞及肝外侧支血管对肝癌供血的分析

目的 探讨在肝癌介入治疗中肝动脉狭窄闭塞后肝外侧支血管的形成对肝癌介入治疗的意义。材料与方法 观察和统计787例肝癌血管造影中见到的37例肝动脉狭窄闭塞者肝外侧支血管的部位及其发生率。结果 右膈下动脉和胃左动脉是形成肝外侧支的主要血管,分别占40．5％、29．7％,而胰十二指肠下动脉、胃十二指肠动脉、肠系膜上动脉分别占8％、5．4％8％。肝右叶7、8段肿瘤侧支血供主要来自右隔下动脉,5、6段肿瘤主要来自胆总管周围动脉,肝左叶肿瘤侧支血供主要来自胃动脉。经 肝动脉狭窄闭塞的主要原因为重复导管化疗和操作不当。结论 肝左叶肿瘤侧支血供主要来自胃左动脉。引起肝动脉狭窄闭塞的主要原因为重复导管化疗和操作不当。结论 肝动脉狭窄闭塞后肝外侧支血管成为肝肿瘤的主要供血动脉。了解侧支血管发生的部位及其发生率对肝癌患者的进一步治疗有重要意义。     

Experimental hepatic artery embolization with a collagen embolic agent in rabbits. A microcirculatory study

The authors used new fibrous collagen embolic material (5 by 75 microns in size) for flow-directed hepatic artery embolization in four rabbits; the purpose of the study was to examine the acute effects of the material on hepatic microcirculation. Extent of hepatic dearterialization, level of arterial occlusion, collateral formation and status of portal sinusoidal perfusion were evaluated under a dissection microscope after embolization. The collagen material produced proximal and peripheral hepatic arterial occlusion with complete hepatic dearterialization, including the bile duct. Portal sinusoidal perfusion appeared to be intact. No intrahepatic microcollaterals were observed.     

Embolization of the right gastric artery before hepatic arterial infusion chemotherapy to prevent gastric mucosal lesions: approach through the hepatic artery versus the left gastric artery

OBJECTIVE: The purpose of our study was to evaluate whether the hepatic artery or the left gastric artery is the better route of approach for selective embolization of the right gastric artery before hepatic arterial infusion chemotherapy using a port-catheter system. SUBJECTS AND METHODS: Eighty-six patients (56 men, 30 women; mean age, 62.1 years) with unresectable advanced liver cancer underwent percutaneous implantation of a port-catheter system. In the 75 patients who had not undergone gastrectomy, right gastric artery embolization was performed before port-catheter system placement to prevent gastric mucosal lesions. In 43 patients, the approach for embolization was through a microcatheter inserted from the hepatic artery site, and in the remaining 32 patients, the approach was from the left gastric artery. The success rates of these two groups were compared. RESULTS: Embolization was successfully accomplished at the first attempt in 72.1% of the 43 patients in whom the microcatheter was inserted from the hepatic artery site. In contrast, in 93.8% of 32 patients, embolization was successfully performed through the left gastric artery. The success rate of embolization was significantly higher in the latter group (p = 0.0173, chi-square test). A second attempt in which the catheter was redirected to another approach, performed on the same day in a majority of patients, resulted in successful embolization in an additional eight patients, with a final success rate of 92.0%. CONCLUSION: Embolization of the right gastric artery using microcoils through a microcatheter advanced through the left gastric artery may be the preferred method for the preparation of repeated hepatic artery infusion.     

Hilar biliary strictures after liver transplantation: cholangiography and percutaneous treatment

Nonanastomotic hilar bile duct strictures developed in 16 of 152 patients who underwent liver transplantation. The type of pretransplantation liver disease did not significantly affect the likelihood of hilar stricture formation. Possible causes of hilar biliary strictures include hepatic artery occlusion, ductopenic arteriopathic rejection, and cytomegalovirus infection; however, five of the 16 patients had hilar strictures without these complications. Hilar strictures developed within 3 months after transplantation in 11 of the 16 patients. Strictures began as a slight common hepatic duct irregularity and progressed to mucosal cast formation and later to firm strictures. Fifteen of the 16 patients underwent percutaneous stricture dilation. Of 12 patients who no longer have stents, four have had no stricture recurrence for 12-30 months. Eight patients have had to undergo retransplantation or have died. Percutaneous dilations were most likely to result in patient bile ducts if strictures developed within 3 months after transplantation and in the absence of pretransplantation primary sclerosing cholangitis, ductopenic arteriopathic rejection, cytomegalovirus infection, or hepatic artery thrombosis.     

去胆管肝叶肝组织形态及功能变化的实验研究

目的观察大鼠肝叶胆管栓塞结扎后肝细胞形态及功能的变化,探讨去胆管肝叶的保留价值。方法应用氰基丙烯酸酯对仅保留肝右叶和方叶的大鼠行右叶胆道栓塞并结扎,制备去胆管肝叶,肝方叶不处理或行门静脉结扎作去门脉肝叶自身对照。通过分肝静脉血化验检查、组织学观察探讨肝细胞形态及功能的变化。结果与假手术对照组及自身未处理肝叶相比,去胆管肝叶萎缩不明显,超微结构变化不大。透射电镜观察发现去胆管肝叶肝细胞富含线粒体、核糖体及粗面内质网。PAS染色显示肝糖原代谢也无明显差别。分肝静脉血白蛋白及纤维蛋白原含量无明显减低。结论去胆管肝叶在观察期内无明显纤维化,仍保留有肝细胞蛋白质合成、分泌及营养物质代谢功能,提示去胆管肝叶具有保留价值。本实验为临床特殊情况下结扎或切除胆管而保留相应的肝脏组织提供了理论基础。     

Development of extrahepatic arterial blood supply to the liver during hepatic arterial infusion chemotherapy

The aim of this study was to evaluate the correlation of development of the collateral circulation to the liver during hepatic arterial infusion chemotherapy (HAIC) with the presence of hepatic tumours adjacent to the hepatic surface, and with pretreatment occlusion of aberrant hepatic arteries. In 102 patients with unresectable malignant hepatic tumours treated with HAIC using an implantable port system, development of collaterals to the liver was assessed with CT arteriography using the implantable port and pre- and postoperative angiography. Aberrant hepatic arteries, if present, were occluded prior to treatment for hepatic arterial redistribution. Collaterals to the liver were seen in 29 patients, who had 35 areas with collateral perfusion: 22 areas were in the right posterosuperior area, 6 in the left peripheral area and 7 in the right or left lobar area. Collaterals were revealed more frequently in patients with hepatic tumours adjacent to the hepatic surface than in those without hepatic tumours in peripheral areas in the liver (p < 0.0001). In addition, collaterals developed more frequently in patients with an aberrant hepatic arterial anatomy compared with those with conventional anatomy (p = 0.0007). Our results indicated that patients with hepatic tumours adjacent to the hepatic surface and with pretreatment occlusion of aberrant hepatic arteries had the potential to develop collaterals to the liver during HAIC. Received 4 November 1997; Revision received 24 February 1998; Accepted 2 June 1998     

Evaluation of "M-point" in hepatic artery to identify left medial segment of liver. Angiographic study

The hepatic arteries of 122 patients were analysed on angiography to identify the left medial segment of the liver. Left medial arterial branches were classified into three types: type I arising from the left hepatic artery on the umbilical portion of the portal vein; type II arising from proximal portion of left hepatic artery before reaching the umbilical portion of the portal vein; type III arising from right hepatic artery. Incidence of each type is 37.2%, 35.8% and 27.0%, respectively. The artery frequently kinks at the right side of the umbilical portion of the portal vein and a total of incidence is 68% and that of each type is 23.5%, 89.8% and 100%, respectively. We call this characteristic kinking point of the left medial arterial branches, the "M-point".     

Potential pitfall of MR cholangiopancreatography: right hepatic arterial impression of the common hepatic duct

PURPOSE: The purpose of this study was to evaluate the frequency and imaging characteristics of nonpathologic narrowing that is seen in the common hepatic duct on MR cholangiopancreatography (MRCP), which can be caused by impression of the right hepatic artery. METHOD: MRCP images obtained in 52 patients were reviewed by two radiologists who attained consensus for evaluation of the frequency, degree, and length of narrowing of the common hepatic duct. Subsequent endoscopic retrograde cholangiopancreatography, CT, ultrasonography, and follow-up imagings performed in 3-6 months were reviewed for evaluation of the narrowing in the common hepatic duct seen with MRCP images. RESULTS: Smooth narrowing of the common hepatic duct that was presumably due to right hepatic arterial impression was seen in 11 (21%) of 52 patients. The extrinsic impression was severe in none, moderate in five, and subtle in six patients, ranging in length from 4 to 11 mm (mean 7.9 mm). CONCLUSION: Radiologists should avoid misinterpreting a smooth and short narrowing in the common hepatic duct on MRCP images by recognizing the possible presence of the right hepatic artery that makes an impression on the common hepatic duct.