Ultrasound in Liver Trasplantation

Transcription

1 Ultrasound in Liver Trasplantation Poster No.: C-1892 Congress: ECR 2011 Type: Educational Exhibit Authors: B. Molinares, A. Marquez, M. Ochoa, S. Alvarez; CO Keywords: Ultrasound-Spectral Doppler, Ultrasound-Colour Doppler, Ultrasound, Liver, Interventional non-vascular, Abdomen DOI: /ecr2011/C-1892 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 25

2 Learning objectives - Recognize normal ultrasound findings in liver transplantation in adult patients - Identify abnormal findings that suggest complications - Describe normal and abnormal findings of vascular structures of the graft in Doppler evaluation Background Liver transplantation is an effective therapeutic method to treat multiple end-stage liver disease, irreversible acute and chronic. With the advances in immunosuppressive therapy, surgical technique and perioperative care as well as imaging methods the outcome of patients undergoing liver transplantation has improved. Ultrasound is the initial imaging modality for monitoring patients and detecting complications. Its advantages to be widely available, portable, does not produce side effects and is not associated with effects of ionizing radiation. What makes it an ideal method as the initial screening of suspected complications. The complications are diverse and include vascular complications, complications of biliary anastomosis, collections, cancer and graft rejection. In our institution liver transplant is performed of cadaveric donor, in adults is made whole - liver transplantation and Reduced and split liver transplantation is reserved for pediatric patients. Imaging findings OR Procedure details Considerations of the surgical technique The whole liver transplantation involves a biliary anastomosis and four vascular anastomoses. Page 2 of 25

3 The biliary anastomosis is end - to - end. Choledoco-Jejunostomy is performed only when there is common hepatic duct disease since with the anastomosis bilioenteric is greater risk of infection and bleeding. In our institution does not use the tube T. The portal vein anastomosis is also end to end unless graft is required by previous thrombosis. The hepatic artery anastomosis is performed is usually between bifurcation in hepatic and splenic artery or celiac trunk with a Carrel patch of donor and recipient hepatic artery. The venous anastomosis most used in our center is the ''piggy-back''. Early detection of postoperative complications is essential for patient and graft survival. Graft loss is a serious problem because of the complexity of the surgical procedure and the limited availability of livers for transplantation. The clinical signs of complications are usually not specific and diagnosis is often based on imaging methods. Ultrasound is the imaging method of choice for screening because it is cost effective, accessible, and easily performed in the patient's bedside. Routine screening: Routine postoperative ultrasound evaluation includes a grayscale of the liver parenchyma and bile duct plus a doppler evaluation of hepatic vasculature. The monitoring of liver transplant is performed with ultrasound. Thus it is early posttransplant follow-up usually includes an ultrasound on the first day. In our institution, ultrasound is performed within the first six hours after transplantation, 24 hours later and there according to the clinical and laboratory parameters. According to the findings of ultrasound screening, carried out other procedures or closer monitoring. And then an ultrasound is performed on the fifth day, before discharging the patient. Also performed routine ultrasound follow-up late when there is any indication, clinical or biochemical, that may indicate a late complication. Grayscale normal findings Normal transplanted liver has a homogeneous or slightly heterogeneous echogenicity. The bile duct should be normal in appearance and normal size. Fig. 1 Page 3 of 25

4 In the early postoperative period is common to find little or moderate amount of free fluid in the abdominal cavity, especially in the perihepatic space that usually resolves within 7 to 10 days after transplantation. It is also usual to find the presence of low to moderate amount of free fluid in the right pleural space. Fig. 2 Normal findings on Doppler - Hepatic artery:it looks like an artery with low resistance with a waveform that shows a rapid systolic peak with continuous diastolic flow. The acceleration time (representing the time between the beginning and end of diastole to first systolic peak) should be less than 80 ms and the resistance index (IR) must be between 05 and 07. Fig. 3. It is important to evaluate in the porta hepatis, on the right and left side, because a normal waveform obtained at the porta hepatis not completely rule out an obstruction. Since this is possible is important to evaluate also the site of the anastomosis. - Portal vein: The morphology of the wave of the portal vein must show a pattern of continuous flow to the liver with some slight variations of the velocity, induced by breathing. Fig.4 - Vena cava and hepatic veins: The normal appearance of the flow of the hepatic veins and inferior vena cava is a flow pattern multi phasic reflecting the physiological changes of blood during the cardiac cycle. Fig.5 Complications of liver transplantation Ultrasound also is preferred for the detection of complications, both early and late and can detect the majority. Vascular complications: Usually occur in the early postoperative period. These should be discarded in all transplant patients presenting liver failure, bile leakage, gastrointestinal bleeding or sepsis. Complications of hepatic artery Page 4 of 25

5 Should be diagnosed as soon as possible in the early postoperative period, for an urgent revascularization of the graft. If this is not done, this patient probably will require retransplantation. Bile ducts in the transplanted liver, unlike the native liver are dependent only on the irrigation of the hepatic artery, therefore the clinical presentation of hepatic artery thrombosis can be varied from fulminant hepatic failure until the bile duct leaks Hepatic artery thrombosis Corresponds to 60% of all vascular complications. Be considered early when it occurs within 15 days after transplant. Risk factors include an increased difference in size between the hepatic artery of the donor and recipient, prior stenosis in the celiac trunk, excessive duration of cold ischaemia, ABO incompatibility, cytomegalovirus infection and acute rejection. Early diagnosis is extremely important because early intervention as thrombectomy or reconstruction of the hepatic artery or both, can save the graft in some cases. However, most patients will require retransplantation. Even with retransplantation mortality increases up to 30%. The diagnosis of hepatic artery thrombosis is performed when no flow is detected in the proper hepatic artery or intrahepatic level with color Doppler and pulsed Doppler. Fig. 6 The color Doppler leads to a correct diagnosis in 92% of cases. A resistance index below 0.5, a higher systolic acceleration time of 0.08 seconds or a peak systolic velocity in the hepatic artery greater than 2 m / s are ominous signs that require close monitoring. In contrast, a high resistance index during the period immediately after transplantation is a very common finding and not associated with prognosis or impact on the development of further complications. Fig. 7 Hepatic artery stenosis Reported between 5% and 11% of transplanted livers. Usually occurs at the site of the anastomosis within three months after transplantation. Early detection is crucial for treatment, either surgical reconstruction or balloon angioplasty and avoid retransplantation. The findings suggest focal stenosis is any increase in peak systolic velocity (more than 2 to 3 times) and further identify poststenotic turbulent flow. Additionally, a finding that is very often is the presence of a tardus parvus intrahepatic flow, which is characterized by an increased systolic acceleration time is greater than 0.08 seconds and a resistive index of less than 0.5. Fig. 8, 9 Page 5 of 25

6 Complications of portal vein: The portal vein complications include thrombosis and stenosis. Occur between 1 and 2% of transplant patients. The causes contributing to these complications are related to the surgical technique, venous thrombosis or previous surgery of the portal vein. The clinical presentation includes portal hypertension, liver failure, edema and massive ascites. Thrombosis in grayscale displays an echogenic luminal thrombus without identifying flow with Doppler evaluation. Fig 10 Occasionally when the thrombosis is acute, the thrombus may be even anechoic. In these cases, the grayscale value of the vessels may appear normal, but when evaluated with color Doppler and spectrum is evidence of abnormality. In the portal vein stenosis is a decrease in the caliber of the vascular structure with turbulent flow and increased flow velocity 3 to 4 times on the site of stenosis compared with preestenótico segment. Fig. 11, 12, 13 But turbulent flow can be a normal finding in the early postoperative period. Other signs of stenosis in the gray scale include poststenotic dilatation and signs of portal hypertension demonstrated by an increase in the number or size of the collateral vessels. Complications of the vena cava: Include thrombosis and stenosis. Are relatively rare and is diagnosed in less than 1%. This is most commonly seen in retransplanted patients and in the pediatric population. Stenosis of the vena cava occurs acutely secondary to a discrepancy in the anastomosing vascular structures or in a suprahepatic kinking. The stenosis of the vena cava in the late postoperative period usually occur secondary to fibrosis, chronic thrombosis or neointimal hyperplasia. The normal wave morphology is a multi-wave. A continuous waveform morphology is a sensitive finding, but not specific for stenosis of the hepatic veins. Fig. 14, 15 In stenosis a reduction in the caliber of the inferior vena cava or hepatic veins flow results in preestenotic dilation of the hepatic veins as an indirect diagnostic finding. The direct signs of stenosis include focal stenosis in the gray scale and a turbulent flow on color Doppler velocity. In thrombosis of the hepatic veins or inferior vena cava is identified echogenic intraluminal thrombus, without identifying flow with Doppler assessment. Biliary complications Occur in up to 25% of patients. Page 6 of 25

7 Include stenosis, leaks, and stones.the most common is stenosis of the anastomosis. Fig. 16 Ultrasound is less sensitive in detecting obstruction that general population possibly because the regular monitoring of liver function after transplantation causes biochemical abnormality is detected before the dilatation develops. Careful evaluation is needed and if clinical suspicion persists proceeds to review with other methods such as MRCP or ERCP Collections Most patients develop pleural effusion in the period immediately pospoperatorio, usually without clinical significance and resolves within a few days. Fig. 2 If there is respiratory compromise ultrasound guided drainage is indicated. Abscesses may occur in up to 10% of patients and most are of bacterial origin. Most in the subphrenic or subhepatic space. Fig. 17 Imagiologic appearance of abscesses may not be specifcity. Ultrasound-guided aspiration is of choice because it is diagnostic and therapeutic. Images for this section: Page 7 of 25

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24 Conclusion Ultrasound is a method of choice in patients after liver transplantation as it provides anatomical and functional information. Another procedure could allow the realization of as biopsies and drainages. Is a diagnostic method cost effective, easily performed in the patient's bed or even intraoperatively. If done with dedication is possible an accurate assessment of hepatic parenchyma, vascular structures graft and the biliary tract. Personal Information Beatriz Molinares. Radiology Deparment. Pablo Tobon Uribe Hospital. Professor of Radiology. Chief of the postgrad in radiology. CES University. Medellin. Colombia Sergio Alvarez. Radiology Deparment. Pablo Tobón Uribe Hospital. Professor of Radiology. CES University. Medellín. Colombia. Martin Ochoa. Radiology Deparment. Pablo Tobón Uribe Hospital. Medellín. Colombia Adriana Marquez. Radiology Resident. CES University. Medellín. Colombia References 1. MotoyamaA, Blasbalg R, Zafred A, Da Cunha M, ChammasM, Da Costa C, Cerri G. Complications of Liver Transplantation: Multimodality Imaging Approach. RadioGraphics 2007; 27: Crossin J, Muradali D, Wilson S. US of LiverTransplants: Normal and Abnormal. RadioGraphics 2003; 23: Platt1 J, Yutzy1' G, Bude R, Ellis J, Rubin J. Use of Doppler Sonography for Revealing Hepatic Artery Stenosis in LiverTransplant Recipients. AJR 1997;168: Page 24 of 25

25 4. Shaw A, Ryan S, Beese R, Norris S, Bowles M, Rela M, Sidhu P. Liver transplantation. Imaging, 14 (2002), Uzochukwu L, Bluth E, Smetherman D, Troxclair L, Loss G, Cohen A, Eason J. Early Postoperative Hepatic Sonography as a Predictor of Vascular and Biliary Complications in Adult Orthotopic Liver Transplant Patients. AJR 2005; 185: García A, Gilabert R, Salmerón J, Nicolau C, Vilana R, Bianchi L. Significance of and Contributing Factors for a High Resistive Index on Doppler Sonography of the Hepatic Artery Immediately After Surgery: Prognostic Implications for Liver Transplant Recipients. AJR 2003;181: Chen W, Facciuto M, Rocca J, Marvin M, Sheiner P, Rachlin S, Rodriguez M. Doppler Ultrasonographic Findings on Hepatic Arterial Vasospasm Early After Liver Transplantation. J Ultrasound Med 2006; 25: García A, Gilabert R, Nicolau C, Real I, Arguis P, Bianchi L. Early Detection of Hepatic Artery Thrombosis After Liver Transplantation by Doppler Ultrasonography. J Ultrasound Med 20:51-58, 2001 Page 25 of 25