Percutaneous MR imaging-guided transvascular access of mesenteric venous system: study in swine model

PURPOSE: To determine if, with use of magnetic resonance (MR) imaging guidance alone, transcaval puncture of the superior mesenteric vein (SMV) and/or portal vein is feasible with a percutaneous femoral vein approach. MATERIALS AND METHODS: The Institutional Animal Care and Use Committee approved the animal studies. Ten inferior vena cava (IVC)-SMV punctures were performed in six pigs. An active MR intravascular needle system was used for all transvascular punctures, and all procedures were performed with a 1.5-T MR unit. The needle was introduced via a 12-F femoral vein sheath and advanced into the IVC by using a real-time gradient-recalled-echo sequence (3.4/1.2 [repetition time msec/echo time msec], 45 degrees flip angle, and six to eight frames per second). Fast transverse spoiled gradient-recalled acquisition in the steady state (SPGR) (6.0/1.5, 60 degrees flip angle, one frame per second) was performed to confirm needle trajectory. The needle system was advanced under real-time MR imaging to puncture the SMV. The location of the needle tip was confirmed with a fast spin-echo sequence (1904/4.5, 36-cm field of view). A direct MR portogram was obtained after the administration of gadopentetate dimeglumine at a concentration of 25% with fast SPGR (6/1.3, 90 degrees flip angle, no section selection, three frames per second). Success was defined as entry into the mesenteric venous system without traversal of any retroperitoneal organs or adjacent vasculature. RESULTS: Successful MR imaging-guided IVC-SMV punctures were performed in all 10 procedures (100%). The needle was fully visualized as it traversed the retroperitoneum and entered the SMV. MR portograms were successfully obtained following all punctures through the needle. Conventional transverse MR imaging helped confirm that the needle did not traverse any retroperitoneal organs or vessels. CONCLUSION: With use of only MR imaging guidance and an active MR imaging intravascular needle system, the authors were able to successfully puncture the SMV from the IVC with direct visualization of the needle and all retroperitoneal structures.     

1999 Gary J. Becker Young Investigator Award. MR-guided transjugular portosystemic shunt placement in a swine model.

PURPOSE: To evaluate the performance of portal venous puncture with use of magnetic resonance (MR) guidance, and to place a transjugular intrahepatic portosystemic shunt (TIPS) in a swine model. MATERIALS AND METHODS: A study of 12 swine was performed to evaluate the ability of interventional MR imaging to guide portal vein puncture and TIPS placement. Six swine had catheters placed in the right hepatic vein under C-arm fluoroscopy. A nitinol guide wire was left in the vein and the animals were then moved into an open configuration MR imaging unit. A TIPS needle set was used to puncture the portal vein using MR fluoroscopy. The animals were transferred to the C-arm, and venography confirmed portal vein puncture. A follow-up study was performed in six additional swine to place a TIPS using only MR imaging guidance. MR tracking was used to advance a catheter from the right atrium into the inferior vena cava. Puncture of the portal vein was performed and a nitinol stent was placed, bridging the hepatic parenchyma. MR venogram confirmed placement. RESULTS: Successful portal vein puncture was achieved in all animals. The number of punctures required decreased from 12 in the first animal to a single puncture in the last eight swine. A stent was successfully placed across the hepatic tract in all six swine. CONCLUSIONS: Real-time MR imaging proved to be a feasible method to guide portal vein puncture and TIPS placement in pigs.     

Experimental Percutaneous Extrahepatic Portacaval Shunt Creation by Transjugular Approach in Swine

The purpose of the study was to evaluate the feasibility of the creation of a percutaneous extrahepatic portacaval shunt (PEPS) in swine by a transjugular approach and to find a suitable stent-graft to use in PEPS. In 12 swine, the extrahepatic portal vein (PV) was entered from the inferior vena cava (IVC) by a needle system introduced from the transjugular approach. A catheter introduced through the transhepatic approach served as a target. Five types of stent-graft consisting of homemade Z stents and a polytetrafluoethylene cover were explored for PEPS creation. Eight animals had follow-up venograms up to 6 weeks or until the shunt became severely stenotic. Gross and histologic examinations were performed after the final follow-up venography. The PV punctures and stent-graft placement were difficult, but the PEPS was established in all animals. In four animals, the stent-graft failed to adequately cover the tract, causing severe hemorrhage. Only two shunts remained patent up to 6 weeks. The other shunts exhibited severe stenosis or occlusion. At gross examination, all shunts traversed the liver parenchyma of the caudate lobe surrounding the IVC. The extravascular PEPS portion was 4 mm to 2 cm long. All shunts entered the PV close to the splenomesenteric junction and exhibited neointimal formation. Shunt stenoses were caused by neointimal hyperplasia and occlusions by a superimposed thrombus. PEPS can be created by the transjugular approach in swine, but only the PV shunt entrance is extrahepatic. None of the tested rigid stent-grafts were suitable for PEPS creation. A short flexible stent-graft with flanged ends is suggested for further exploration.     

Intravascular US-guided direct intrahepatic portacaval shunt with a PTFE-covered stent-graft: feasibility study in swine and initial clinical results

PURPOSE: To determine the feasibility of the creation of a direct intrahepatic inferior vena cava (IVC)-to-portal-vein shunt with puncture guided by a transfemorally placed intravascular ultrasound (IVUS) probe and use of a polytetrafluoroethylene (PTFE)-covered stent-graft. MATERIALS AND METHODS: In five swine, transjugular access was used to perform a direct puncture from the IVC to the portal vein with use of a modified Rosch-Uchida Portal Access set directed with real-time IVUS (9 MHz) introduced from a transfemoral venous approach. The direct intrahepatic portocaval shunt (DIPS) was then created with single or overlapping PTFE-covered Palmaz stents placed through a 10-F sheath and dilated to a diameter of 8 mm. Follow-up was performed with transhepatic portography at 2, 4, and 8 weeks. Animals were killed when shunts occluded or at the termination of the study at 8 weeks. Gross and microscopic histologic study was performed on sacrificed animals. A similar technique was used to create DIPS in five patients with intractable ascites, with follow-up by US and venography. RESULTS: All experimental DIPS created in swine were created without complications. Portal vein punctures were achieved in four of five swine on the first or second pass of the needle. Follow-up transhepatic portography at 2 weeks demonstrated occlusion of two shunts, both explained by technical reasons at sacrifice. At 4 and 8 weeks, the remaining three shunts were patent on portography. Histology showed a thin neointimal lining with no significant tissue ingrowth or hyperplasia. Clinically, in five patients, successful puncture of the portal vein from the IVC was achieved in one to three passes. Creation of DIPS led to a reduction of mean portosystemic gradient from 18-29 mm Hg (mean, 24 mm Hg) to 9-10 mm Hg (mean, 9 mm Hg). One patient died of liver failure 2 days after creation of DIPS. The other four patients were doing well 2-15 months (mean, 8 months) after the procedure, with patency confirmed by US and venography. CONCLUSION: Creation of DIPS is technically feasible, and the direct IVC-to-portal-vein puncture can be done accurately with real-time IVUS guidance. Further studies and longer follow-up are necessary to determine if the short length of the PTFE-covered stent-graft and avoidance of the hepatic vein will increase the long-term patency compared to standard transjugular intrahepatic portosystemic shunt creation.     

Magnetic resonance image-guided trans-septal puncture in a swine heart

PURPOSE: To test the feasibility of performing magnetic resonance (MR)-guided trans-septal punctures in the swine heart. MATERIALS AND METHODS: All procedures were performed in a 1.5-T MR scanner. A novel, active MR intravascular needle system was utilized for needle tracking and septal punctures. Trans-septal punctures were performed in five swine using electrocardiogram (ECG)-gated high resolution and non-ECG-gated, real-time MR imaging techniques. The intravascular needle was advanced over a guidewire from the femoral vein. Once the needle was in proper position, trans-septal punctures were made. RESULTS: Active tracking of the needle traversing the septum was possible. The location of the catheter tip was confirmed using real time gradient recalled echo (GRE). After a confirmatory ventriculogram with gadolinium-DTPA, a 0.014-inch guidewire was advanced into the left atrium and left ventricle. All punctures were made with no change in cardiac rhythm or rate; postmortem analysis was performed on all animals and demonstrated that 18/19 (95%) punctures were directly through the fossa ovalis. CONCLUSION: Using only MR guidance and a novel active intravascular needle system, we were able to repeatedly puncture the fossa ovalis in a swine heart from a transfemoral approach, with direct visualization of all components, including the needle, the atria, the fossa ovalis, and the surrounding vasculature.     

Percutaneous CT-guided superior mesenteric vein access for portal vein recanalization-transjugular intrahepatic portosystemic shunt

Portal vein recanalization-transjugular intrahepatic portosystemic shunt (PVR-TIPS) is a valuable technique in the treatment cirrhosis and portal vein (PV) thrombosis. Only a few studies have reported cases of utilizing the transmesenteric approach in the procedure''s initial portal access. Here, we report the successful utilization of a CT-guided percutaneous puncture of the superior mesenteric vein (SMV) for PVR-TIPS in a patient with splenic vein thrombosis. A 54-year-old male with a history of morbid obesity (BMI: 44.67), hepatitis C, NASH cirrhosis, esophageal varices, and complete PV thrombosis presented for PVR-TIPS. An initial percutaneous transplenic approach was attempted, but was aborted due to the discovery of a splenic vein thrombosis. Subsequently, the patient was brought back into the hybrid-angio CT suite, and the SMV was accessed percutaneously with a 21-gauge needle under 4D CT-guidance. A 5-Fr micropuncture sheath was then placed. Additional portal venogram confirmed PV thrombosis. Right internal jugular vein (IJV) access was then obtained, and the right hepatic vein was catheterized. A loop snare was advanced from the SMV access into the right PV. A Colapinto needle was later positioned in the right hepatic vein, and the right PV was accessed using the loop snare as a target. A wire was then advanced and captured by the snare, and brought down through the PV. The tract was dilated with a 10 mm balloon, and a Viatorr stent was deployed. Balloon embolectomy of the SMV, splenomesenteric vein, and TIPS were then performed with a CODA balloon with improvement in flow through the TIPS on final portal venogram. Portosystemic gradient was 11 mmHg initially and 10 mmHg post-TIPS. Follow-up TIPS venogram in 3 weeks showed a widely patent TIPS. CT-guided percutaneous SMV access may serve as valuable technique in PVR-TIPS when traditional modes of initial portal access for recanalization are unobtainable.     

Intravascular ultrasound-guided direct intrahepatic portacaval shunt: description of technique and technical refinements

PURPOSE: This is a prospective study designed to demonstrate the safety and feasibility of creating a direct inferior vena cava (IVC)-to-portal vein shunt with use of a new type of intravascular ultrasound (IVUS) to guide the puncture and completing the shunt with the use of a polytetrafluoroethylene (PTFE)-covered stent graft. MATERIALS AND METHODS: IVC-to-portal vein shunts were created in 31 sequential patients for ascites (n = 31) or bleeding (n = 8). Transfemorally placed IVUS transducers were positioned in the IVC to guide the puncture from the IVC to the portal vein, which was performed from a transjugular approach with a modified Rosch-Uchida liver access set. A 9-MHz axial imaging IVUS system was used for the first 11 patients, and a variable 5-10-MHz sagittal IVUS imaging system was used for the next 20 patients. The shunts were completed with the use of single (n = 11) or overlapping (n = 20) PTFE-covered Palmaz stent-grafts, deployed primarily at a diameter of 8 mm. Patients were followed clinically and with US, venography, and inspection at liver transplantation to establish 30-day patency rates. RESULTS: All direct intrahepatic portacaval shunts (DIPSs) were created successfully. Both IVUS systems were able to adequately guide the portal vein puncture. Resolution and operator confidence were subjectively superior with the sagittal IVUS imaging system compared to the axial IVUS system. Two extrahepatic portal vein punctures occurred during the procedures. Both were controlled by the placement of sheaths and subsequent placement of stent-grafts. Both patients remained asymptomatic, although one required transfusion of blood products. The mean portosystemic gradient was reduced from 24 mm Hg before DIPS creation to 10 mm after DIPS creation. Embolization of varices was also performed in eight patients with history of recent gastrointestinal bleeding. Two patients died in the first week of acute liver failure. Two patients with hepatocellular carcinoma refused further follow-up. Of the 27 remaining patients, patency was demonstrated in all DIPS at 30 days by US, venography, or direct inspection at liver transplantation. CONCLUSIONS: IVUS-guided direct IVC-to-portal vein shunts may be created successfully with minimal complications. The use of a stent-graft is recommended for this procedure. Modifications of current technique and IVUS systems are described.     

Balloon sizing and transcatheter closure of acute atrial septal defects guided by magnetic resonance fluoroscopy: assessment and validation in a large animal model

PURPOSE: To quantitatively assess atrial septal defects (ASDs) with small shunts using MRI followed by transcatheter closure monitored by MR fluoroscopy. MATERIALS AND METHODS: Acute ASDs were created in 14 pigs under x-ray fluoroscopy. Six animals were studied in order to select MR-compatible delivery systems and imaging strategies. ASDs in eight animals were examined with balloon sizing under MR fluoroscopy, flow measurements, and contrast media injections, after which transcatheter closure was performed under MR fluoroscopy. The delivery system was assembled from commercially available materials. RESULTS: The ratio of pulmonary to systemic flow (Qp/Qs) was reduced from 1.23 +/- 0.15 before ASD closure to 1.07 +/- 0.11 after ASD closure (P < 0.001). In two out of eight animals Qp/Qs was close to 1.0 before closure despite the presence of defects >15 mm. The ASDs were measurable with MR balloon sizing in all of the animals. Balloon sizing was identical with MR (16.9 +/- 2.3 mm) and x-ray fluoroscopy (17.1 +/- 1.3 mm). The in-house-assembled delivery system allowed successful placement of closure devices under MR guidance. CONCLUSION: Assessment and closure of small shunts with MR fluoroscopy is feasible. A barrier to the rapid implementation of transcatheter closure in patients is uncertainty about the MR safety of guidewires and device delivery systems.     

Successful portal-systemic shunt occlusion of a direct shunt between the inferior mesenteric vein and inferior vena cava with balloon-occluded retrograde transvenous obliteration following recanalization after placing a covered stent in the portal and superior mesenteric veins

Extrahepatic portal-systemic shunts cause portal-systemic encephalopathy. Direct communication between the inferior mesenteric vein (IMV) and the inferior vena cava (IVC) is a relatively rare pathway among the variety of portal-systemic shunts. This report describes a case of successful occlusion of an IMV-IVC shunt. Based on laboratory data and computed tomography findings, a 69-year-old woman with liver cirrhosis was diagnosed with portal-systemic encephalopathy due to a shunt between the IMV and the IVC. Her hepatic coma had not been adequately controlled by oral or intravenous pharmacotherapy. First, we placed a covered stent in the main trunk of the portal vein and the superior mesenteric vein (SMV) to block the SMV hepatofugal flow and splenic vein hepatopetal flow, but this therapy showed only a transient therapeutic effect due to recanalization. Next, we performed balloon-occluded retrograde transvenous obliteration (BRTO) of the portal-systemic shunt. After the BRTO, she has had no episodes of portal-systemic encephalopathy for 2 years.     

Needle biopsy of anatomically unfavorable liver lesions with an electromagnetic navigation assist device in a computed tomography environment

PURPOSE: Emerging interventional radiology assistance systems that incorporate electromagnetic navigation (EMN) can help the operator guide a needle or other instrument toward a target along preplanned oblique trajectories while avoiding critical structures. A proof-of-concept study was conducted to assess the use of EMN, and EMN was compared with the standard computed tomographic (CT) fluoroscopy guidance technique. MATERIALS AND METHODS: A total of 14 needle passes, seven each with EMN and CT fluoroscopy guidance, were performed into an artificially created liver lesion of a single swine. The accuracy of needle placement for each pass was verified with a confirmatory CT scan. The total radiation dose and time of procedure was compared between the EMN and conventional CT fluoroscopy methods. RESULTS: All needle passes were successful, and all passes conducted with EMN were completed with a single insertion, whereas multiple passes (mean, 2.9) with needle repositioning were required with CT fluoroscopic guidance. Statistically significant reduction in procedure time and overall radiation dose for EMN punctures was shown. Accuracy of needle placement was statistically equivalent for the two methods. CONCLUSIONS: This proof-of-concept study shows that EMN guidance has equivalent accuracy of needle placement to conventional CT fluoroscopy-guided methods in swine. EMN is also associated with favorable radiation-dose and time-of-procedure profiles for biopsy of liver lesions. Clinical studies are needed to evaluate the safety and efficacy of this technology in the biopsy of lesions in anatomically challenging locations that require steep angles of needle insertion.     

Transjugular Intrahepatic Portosystemic Shunt Creation Using Intravascular Ultrasound Guidance

PurposeTo describe the use of intravascular ultrasound (US) guidance for creation of transjugular intrahepatic portosystemic shunts (TIPSs) in humans.Materials and MethodsThe initial 25 cases of intravascular US–guided TIPS were retrospectively compared versus the last 75 conventional TIPS cases during the same time period at the same institution in terms of the number of needle passes required to establish portal vein (PV) access, fluoroscopy time, and needle pass–related complications.ResultsIntravascular US–guided TIPS creation was successful in all cases, and there was no statistically significant difference in number of needle passes, fluoroscopy time, or needle pass–related complications between TIPS techniques. Intravascular US–guided TIPS creation was successful in cases in which conventional TIPS creation had failed as a result of PV thrombosis or distorted anatomy. Intravascular US guidance for TIPS creation was additionally useful in a patient with Budd–Chiari syndrome and in a patient with intrahepatic tumors.ConclusionsIntravascular US is a safe and reproducible means of real-time image guidance for TIPS creation, equivalent in efficacy to conventional fluoroscopic guidance. Real-time sonographic guidance with intravascular US may prove advantageous for cases in which there is PV thrombus, distorted anatomy, Budd–Chiari syndrome, or hepatic tumors.     

Congenital absence of portal vein with nodular regenerative hyperplasia of the liver

Congenital absence of the portal vein is a very rare anomaly. The intestinal and splenic venous drainage bypasses the liver and drain into the inferior vena cava (IVC). Two cases of such anomaly are described. Both cases were investigated by US coupled with echo-colour Doppler examination, CT and MR imaging, followed by digital subtraction angiography (DSA) and liver biopsy. In the first case the splenic and superior mesenteric vein formed a venous trunk which emptied directly into the IVC; in the second case, the splanchnic blood flowed into a dilated hepatofugal inferior mesenteric vein which connected to the left internal iliac vein. In both cases nodular regenerative hyperplasia of the liver was present, presumably due to an abnormal hepatic cell response to the absent portal flow. The particular contribution of MR imaging to the diagnosis of both vascular abnormalities and liver parenchyma derangement and its advantages over the other diagnostic techniques is emphasized. The clinical and radiological features of 17 previously reported cases are reviewed. Received: 22 September 1998; Revised: 21 January 1999; Accepted: 22 April 1999     

Pre- and postprandial alterations of portal venous flow: evaluation with single breath-hold three-dimensional half-Fourier fast spin-echo MR imaging and a selective inversion recovery tagging pulse

PURPOSE: To evaluate the influence of food intake on portal flow using unenhanced magnetic resonance imaging (MRI). MATERIALS AND METHODS: The study population included 29 healthy subjects. A selective inversion recovery tagging pulse was used on the superior mesenteric vein (SMV) and splenic vein (SpV) to study the correlation of tagged blood in the portal vein (PV). MRI was performed before and 60-90 min after a meal. RESULTS: The flow signal from the SMV increased in 97% of the subjects after the meal. Before the meal the portal flow was dominated by flow from the SpV in 59% of the subjects, while it was dominated by flow from the SMV in 76% of the subjects after the meal. The most common distribution pattern of the flow signal from the SpV before the meal was in the central part of the main PV (55%), while it was in the left side (45%) after the meal. The most common distribution pattern of the flow signal from the SMV was in the bilateral sides of the main PV both before and after the meal (62%). CONCLUSION: This technique shows potential for evaluating pre- and postprandial alterations of flow from the SpV and SMV in the PV under physiological conditions.     

A comprehensive approach using MR imaging to diagnose acute segmental mesenteric ischemia in a porcine model.

OBJECTIVE: Acute mesenteric ischemia is a lethal disease that lacks a noninvasive diagnostic test. We evaluated the abilities of contrast-enhanced MR angiography, MR oximetry, and real-time interactive MR imaging to diagnose segmental mesenteric ischemia in a porcine model. MATERIALS AND METHODS: Segmental mesenteric ischemia was created by subselective Gelfoam embolization of the mesenteric circulation in eight pigs. Conventional digital subtraction angiography (DSA), MR oximetry, and real-time interactive MR imaging of the small bowel were performed before and after embolization. Changes in the perfusion pattern seen on DSA established the regions of true ischemia. Postembolization DSA and MR angiography were compared with this gold standard. RESULTS: Both MR angiography and DSA had high sensitivity (91% and 100%, respectively) for detecting ischemic regions. The difference was not statistically significant (p > .2). MR angiography yielded lower specificity than DSA (80% and 90%, respectively; p < .01). After embolization, the oxygen saturation in the superior mesenteric vein (SMV) dropped significantly (p < .005). After embolization, the SMV also showed oxygen saturation significantly lower than that in the inferior vena cava (p < .005). In two of the animals, segmental hypomotility of the small bowel was observed. CONCLUSION: MR oximetry is capable of detecting oxygen desaturation caused by segmental ischemia. A loss of oxygen saturation in the SMV relative to that in the inferior vena cava provides a convenient marker of mesenteric ischemia. Contrast-enhanced MR angiography has sensitivity and specificity approaching those of DSA. Both MR techniques hold promise for the detection of acute mesenteric ischemia.     

Transhepatic puncture of portal and hepatic veins for TIPS using a single-needle pass under sonographic guidance

OBJECTIVE: Creating transjugular intrahepatic portosystemic shunts (TIPS) requires accessing a portal vein branch from a metal cannula wedged in a hepatic vein. This initial step in shunt creation often requires multiple blind intrahepatic punctures and occasionally fails. We describe a method using sonographic guidance to serially puncture the portal vein and hepatic vein with a single transhepatic needle pass, after which the TIPS procedure is completed in the standard transjugular fashion. CONCLUSION: Sonographically guided transhepatic dual puncture of the portal and hepatic veins facilitates portosystemic shunt creation in a single needle pass and allows more controlled selection of the portal vein entry and hepatic vein landing sites in selected patients.     

Streamlined flow in the portal vein: demonstration with MR angiography

PURPOSE: To demonstrate whether streamlining of the portal vein flow exists by evaluating the relative distribution of blood flowing from the superior mesenteric vein (SMV) and splenic vein (SV) into the portal venous system. MATERIALS AND METHODS: Fifteen healthy adult volunteers underwent MR angiography of the main portal vein (PV) and portal vein branches after an overnight fast. Transverse two dimension time-of-flight gradient echo sequences were obtained three times, in suspended expiration and inspiration, respectively, as follows: 1) No presaturation slab, 2) presaturation slab across the SMV, 3) presaturation slab across the SV. Signal intensity (SI) measurements were obtained for all acquisitions. using regions of interest traced manually within the PV and portal branches. RESULTS: After presaturation of the SMV and SV during expiration, the overall SI average in the PV decreased by 47% +/- 8 (mean +/- SD) and 17% +/- 9, respectively. Right to left portal branch SI ratio and right-anterior to left-posterior SI ratio in the PV were 0.91 +/- 0.09 and 1.02 +/- 0.08 at baseline, respectively. They decreased significantly (P < 0.05) to 0.87 +/- 0.09 and to 0.95 +/- 0.09 after saturation of the SMV, and increased significantly to 0.95 +/- 0.08 and to 1.07 +/- 0.10 after saturation of the SV. CONCLUSION: MR angiography with selective saturation of the SMV and SV provided reproducible assessment of the respective contributions of the SMV and SV to portal flow, and allows demonstration that streamlining of splanchnic blood occurs in the portal vein of normal subjects.     

与TIPSS相关的影像学解剖关系的研究

目的应用多种医学影像学及解剖学方法，研究与经颈静脉肝内门腔静脉内支架分流术（ＴＩＰＳＳ）密切相关的解剖学改变，以提高操作的成功率、可靠性及安全性，并探索新的导向方式及分流途径。材料与方法采用ＭＲＩ、ＣＴ、血管造影、肝脏血管铸型等手段，研究肝动脉、胆管和门静脉的伴行情况及相互空间关系，估计各种穿刺途径对其损伤的可能性。分析肝段下腔静脉与门静脉的空间关系。结果胆管和肝动脉主要位于门静脉分叉及主干的前方、前上方；在右干分叉部及左干角部、矢状部分布不规则，可位于其后上或左右方。肝动脉，特别是肝右动脉和门静脉关系密切，可作为穿刺导向。肝段下腔静脉距门静脉分叉及左右干均较近，穿刺有较大的安全范围，可作为新的分流途径。结论熟悉肝脏血管解剖、应用有效导向、避免胆道和肝动脉损伤可提高ＴＩＰＳＳ疗效     

Real-time MR Imaging Guidance for Percutaneous Core Biopsy of US- and CT-negative Lesion

Biopsies traditionally are performed under ultrasound (US), computed tomography (CT), or fluoroscopic guidance. In situations in which lesions are difficult to visualize with US or CT guidance, magnetic resonance (MR) imaging often can provide better imaging results. The authors describe a case in which a recurrent calf mass not well visualized under fluoroscopy, CT, or US was identified on MR imaging. In the absence of real-time needle visualization, percutaneous interventions under MR guidance have been limited by prohibitively long imaging times. A novel guidance system providing real-time MR guidance of needle position was used to procure a core biopsy specimen of the lesion.     

Percutaneous MR-guided discography in a low-field system using optical instrument tracking: a feasibility study

PURPOSE: To evaluate the feasibility of MRI-guided discography with optical tracking. MATERIAL AND METHODS: 12 consecutive patients who had a clinical suspicion of lumbar discogenic pain and/or suggestive finding of disc degeneration in imaging studies (MRI, CT, plain radiography) underwent MRI-guided discography in order to determine possible pain provocation during puncture and contrast injection. An 0.23 T open configuration MRI device with interventional tools (Outlook Proview, Philips Medical Systems, MR Technologies, Finland) was used in procedural imaging and instrument guidance. An optical guidance tool was attached to the MRI compatible needle (Chiba-type MReye, Cook, Bloomington, IN). After initial disc puncture, 1-2 mL of gadolinium contrast (Magnevist, 469 mg/mL, Schering AG, Germany) saline mixture (1:8) was injected into the disc. Immediately after injection, sagittal FE T1 weighted images were obtained to verify the final position of the needle and formation of the MRI discogram. On nine patients, additional noncontrast sagittal fast spin echo (FSE) T1, FSE T2, and axial 3D T1 gradient echo imaging was performed before and after contrast media injection to obtain MRI discograms. RESULTS: Overall, 35 disc punctures were initialized and 34 MRI discograms were obtained. In all punctures, a positive or negative pain response was obtained. The average time for performing a procedure for three discs was 1 hour 25 minutes (minimum 45 minutes, maximum 2 hours, 15 minutes), and the average number of imaging sequences used for a puncturing one disc was 12. On one disc, the puncture failed and a discogram was not acquired. There was one complication (disc collapse) reported during follow-up. CONCLUSION: Our results show that MRI guidance in performing discography is accurate and relatively safe. It is a technically comparable method to CT-guidance or fluoroscopy.     

胰腺癌侵犯胰周主要血管的CT表现分析

目 的分析多层螺旋CT(MSCT)胰腺检查，胰腺癌侵及胰周主要动、静脉的不同CT表现特征。方法 MSCT诊断胰腺癌68例患者中，33例行手术治疗(其中12例行胰十二指肠切除术，21例剖腹探查发现不可切除)，病理结果均证实为胰腺导管细胞癌。术中由手术者仔细探查胰周主要血管[肠系膜上动脉(SMA)、腹腔干(CA)、肝动脉(HA)、肠系膜上静脉(SMV)及门静脉主干(PV)]。结果 165支受检血管中，手术探查发现103支血管未受侵犯，其余62支血管受侵，MSCT术前检查，8．1％(5／62)受侵血管误判为未受侵犯(假阴性)。其余受侵的胰周主要动、静脉(57支)具有不同的CT表现特征：胰周主要动脉受侵时，均被肿瘤包绕大于管周的1／2或完全包埋于肿瘤中。胰周主要静脉受侵时，部分静脉血管被肿瘤包绕小于管周的1／2：SMV为4支(4／17)，PV为2支(2／13)，但同时均出现管壁受浸润或管腔狭窄或管腔形态改变；胰周静脉受侵犯时出现管腔狭窄或闭塞的机会较胰周动脉大：SMV为11支(11／17)，PV为12支(12／13)，而CA为3支(3／8)，HA为4支(4／7)，SMA为4支(4／12)；胰周静脉受侵犯时管壁呈浸润性改变的比例较胰周动脉高：SMV为11支(11／17)，PV为7支(7／13)，而CA为3支(3／8)，HA为2支(2／7)，SMA为6支(6／12)。结论 胰周动、静脉受侵及时，其CT表现具有不同特征。