Role of nuclear medicine in liver transplantation

Hepatobiliary Scintigraphy to Evaluate Biliary Complications of Pediatric Liver Transplantation: An Account of an Experience

INTRODUCTION

 Hepatobiliary scintigraphy (HS) is a noninvasive imaging technique whose use in the follow-up of liver transplantation has not been duly documented. The main objective of this study is to describe the experience of using this technique to detect biliary complications in pediatric patients following liver transplantation.

MATERIALS AND METHODS

 A retrospective, observational, and descriptive study involving 86 pediatric patients who had undergone liver transplantation between 2013 and 2018. Of the 86, 31 had undergone at least one HS during their postoperative period.

RESULTS

 A total of 45 studies were performed on 31 patients (36% of the patients undergoing transplantation during that time period). Patient ages ranged from 5 to 204 months (mean = 50 months). A total of 22 transplants (71%) were from living donors and 9 (29%) were from cadaveric donors. Of the 45 studies, 22 were positive for biliary complications, and all of them had an impact on clinical decision-making. The remaining 23 studies were negative. Of these 23, 19 continued under medical treatment and the other four underwent an additional intervention with positive surgical outcomes in all cases. All scintigraphy studies revealed hepatocellular dysfunction and cholestasis.

CONCLUSION

 The HS is a useful, noninvasive, and diagnostic procedure for the early diagnosis of biliary complications that may impact the evolution of disease in liver transplant patients. It allows the treating physician to make a more informed decision regarding expectant management, surgical management, or a less invasive course of action for transplantation complications.

Renal clearable polyfluorophore nanosensors for early diagnosis of cancer and allograft rejection

Optical nanoparticles are promising diagnostic tools; however, their shallow optical imaging depth and slow clearance from the body have impeded their use for in vivo disease detection. To address these limitations, we develop activatable polyfluorophore nanosensors with biomarker-triggered nanoparticle-to-molecule pharmacokinetic conversion and near-infrared fluorogenic turn-on response. Activatable polyfluorophore nanosensors can accumulate at the disease site and react with disease-associated proteases to undergo in situ enzyme-catalysed depolymerization. This disease-specific interaction liberates renal-clearable fluorogenic fragments from activatable polyfluorophore nanosensors for non-invasive longitudinal urinalysis and outperforms the gold standard blood and urine assays, providing a level of sensitivity and specificity comparable to those of invasive biopsy and flow cytometry analysis. In rodent models, activatable polyfluorophore nanosensors enable ultrasensitive detection of tumours (1.6 mm diameter) and early diagnosis of acute liver allograft rejection. We anticipate that our modular nanosensor platform may be applied for early diagnosis of a range of diseases via a simple urine test.

Hepatobiliary scintigraphy in the study of complications in adult patients after liver transplant. Description of the experience

OBJECTIVE

To show the experience of the use of hepatobiliary scintigraphy in patients with suspected complications after liver transplantation in a high complexity centre.

MATERIAL AND METHOD

Retrospective, observational and descriptive study. All consecutive adult patients with liver transplantation between January 2013 and February 2018 were included, with one or more hepatobiliary scintigraphy during the early or late postoperative period. A total of 58 studies were analyzed in 38 patients (22 men and 16 women). Mean age: 48 years. In 34/38: cadaverous donor (89%), and in 4 (11%): a living donor. Demographic data and relevant information regarding the transplant were obtained, and the result was related to the surgical findings to determine the correlation between them. The influence of the test on the final clinical decisions was evaluated.

RESULTS

Findings: 9 scans (14%) were normal, 36 studies were negative, and 21 were positive for biliary complications. Of the total of 58 studies, 50 (86%) had impact on the clinical behaviour of observation or intervention. All the patients with findings of biliary complications (21/21; 100%) had clinical repercussion since 18/21 patients were taken to invasive studies or treatments, and 3/21 patients continued in medical management for findings of non-surgical biliary complications. In 14/18 patients taken to studies or procedures, correlation was found with the scintigraphic study. In 24/36 (66%) of patients with negative scintigraphy, an impact on clinical behaviour was found.

CONCLUSION

Hepatobiliary scintigraphy is a simple, non-invasive, reliable, current and available form for the early study of biliary complications in patients with liver transplantation. Important hepatocellular dysfunction should be taken into account as a frequent cause of false negative studies.

Nuclear imaging of the liver: is there a diagnostic role of HIDA in posttransplantation?

BACKGROUND AND AIMS

Biliary complications are common after liver transplantation. This study sought to assess the value of hepatic iminodiacetic acid (HIDA) scans (hepatobiliary iminodiacetic acid scan) to detect early posttransplantation biliary complications.

METHODS

From April 2003 to June 2006, 34 liver transplantations (recipients of mean +/- SD age of 43.0 +/- 15.7 years) were performed in 25 (73.5%) males from 20 (58.8%) cadaveric donors and 14 (41.2%) living-related donors. The subjects underwent HIDA scans using a single head gamma camera Meridian (Philips) after intravenous (IV) administration of 185 MBq Tc-99m Disofenin. The mean time +/- SD posttransplantation to HIDA scan was 14.6 +/- 18.2 days (range, 0-74). The results were compared with endoscopic retrograde cholangio pancreatography, magnetic resonant cholangiopancreatography, percutaneous cholangiograhy, and/or liver biopsy.

RESULTS

Twenty-four abnormalities were detected by HIDA scan in 16 patients (47.1%): 10 (29.4%) biliary leaks; 4 (11.4%) biliary obstruction or cholestasis; 1 (2.9%) delayed uptake; 5 (14.7%) delayed blood pool clearance; and 8 (23.5%) delayed transit to the bowel. The complications were more common among living-donor compared with deceased-donor graft recipients, albeit a not statistically significant difference (P = .066). Total and direct bilirubin levels were significantly higher in patients with abnormal than normal HIDA scans (P = .011 and P = .040, respectively). The sensitivity and specificity of HIDA scans to detect overall postoperative complications were 100% and 66.7%, respectively. Biliary leak results were false positives in 7/10 patients, and true in 3. Detection of obstruction was 75% sensitive by HIDA.

CONCLUSION

HIDA scans are a noninvasive, reliable modality for early exclusion of posttransplantation biliary complications. However, correlation with clinical status and imaging modalities is essential to confirm detected abnormalities.

Usefulness of hepatobiliary scintigraphy for the evaluation of living related liver transplant recipients in the early postoperative period

AIM

The aim of this study was to investigate the usefulness of hepatobiliary scintigraphy for the evaluation of liver grafts in the early postoperative period in patients receiving liver transplants from living related donors.

MATERIALS AND METHODS

Fifty-six liver transplant recipients who received grafts from living related donors were included in the study. We examined the hepatobiliary scintigraphies of all patients, which were performed 7 to 10 days after the transplantation. The scintigraphic images were evaluated visually in terms of hepatic parenchymal function and biliary and vascular complications.

RESULTS

In 44/56 recipients, hepatobiliary scintigraphy was completely normal in the early postoperative period. However, in 6/56 cases, scintigraphy was interpreted to show parenchymal dysfunction. In these patients, histopathologic confirmation by biopsies revealed four cases of hepatocellular damage/cholestasis, one acute rejection, and one cholangitis. In 3/56 patients, hepatobiliary scintigraphy demonstrated a hypoactive area in the liver graft; however, the other areas showed normal function. When the abdominal computed tomography (CT) and CT angiography were evaluated, these hypoactive areas were discovered to be related to minor vascular problems. In 3/56 liver graft recipients whose grafts showed normal parenchymal function scintigraphically, images were interpreted to indicate bile leak because accumulation of tracer was seen at an abnormal physiological site.

CONCLUSION

Hepatobiliary scintigraphy, which is a noninvasive and objective method, is useful to assess grafts in the early postoperative period among patients who received liver transplants from living related donors.

Hepatobilijarna scintigrafija u proceni funkcije transplantirane jetre

The aim of the study is evaluation of hepatocellular function, as well as morphology and patency of the biliary three of the liver transplants by dynamic hepatobiliary scintigraphy. The study was performed in 10 controls and 10 patients after orthotopic transplantation (up to two years). Sixty minutes dynamic acquisition (1 frame/min) was performed with scintillation camera after injection of 360 MBq 99mTc-diethyl-IDA. Hepatobiliary scintigrams were analysed for morphology, and parenchymal and hepatobiliary TA curves were generated and analysed as regard to the time to maximal acitivity (Tmax) and the time to half of maximum acitivity (T1/2). Uptake of the radiopharmaceutical was slightly but not significantly delayed (Tmax=18.5+2.9 min) in comparison to the controls (Tmax=14.2+ 3.4min), while excretion was significantly prolonged (T1/2=59.5+ 12.1 min) than physiological (Tmax=34.2+4.1min). Intrahepatic bile flow was nonsignificantly prolonged (Tmax=31.3+3.7 min) in comparison to the controls (Tmax=25.7+ 3.5 min) while extrahepatic one is high significantly prolonged (T1/2=89.0+14.3 min) than physiological (T1/2 =45.0+ 7.2 min). Biliary phase of hepatobiliary scintigraphy showed increased accumulation of radiopharmaceutical in the left (n=1) or right (n=2) hepatic duct. Radionuclide methods are noninvasive, and apear to be sensitive and valuable for the monitoring of liver transplants.

Molecular imaging in transplantation: basic concepts and strategies for potential application

BACKGROUND

The potential applications of molecular imaging in the clinical arena are diverse and expanding rapidly. One such area of application is transplantation. Currently, biopsy is the gold standard for monitoring allograft well-being after transplantation of organs or tissues. However, biopsies are invasive, associated with morbidity if performed on a routine basis and can potentially miss focal rejection.

AIM

It is notable that none of the existing studies in the literature have examined the possible role of molecular imaging in transplantation-related indications. In this direction, this paper aims to discuss imaging strategies that could be of pertinence in monitoring immune events and improving long-term outcomes after solid organ or tissue transplantation.

METHODS

This paper discusses the currently available direct/surrogate imaging techniques/agents that can be used to detect chemokine receptors/ligands, leucocyte endothelial events and ischaemia-reperfusion injury in transplantation.

CONCLUSION

Molecular imaging methods can non-invasively detect, quantify and monitor immune phenomena, such as rejection or graft-versus-host disease, after transplantation. Molecular imaging could help in targeted biopsy and could improve graft survival by allowing for early intervention with tailored immunosuppressive regimens. Given the unprecedented progress in the field, the potential benefits of molecular imaging to the speciality of organ and tissue transplantation cannot be underestimated.

Bile leakage after living donor liver transplantation demonstrated with hepatobiliary scan using 9mTc-PMT

Although it is recognized that hepatobiliary scan is of value in assessing postoperative complications of biliary surgery or cadaveric whole liver transplantation, there have been few reports regarding its usefulness following living donor liver transplantation. We performed living donor liver transplantation in a patient with biliary cirrhosis due to hepatolithiasis, using a right lobe graft from her sister. On the 15th postoperative day, bile discharge appeared from the operative wound. The leakage point could not be identified by computed tomography and cholangiography from the biliary drainage catheter. Hepatobiliary scan with Tc-99m Sn-N-pyridoxyl-5-methyltryptophan (99mTc-PMT) demonstrated biliary extravasation from the left side of the anastomosis of the hepatico-jejunostomy, indicating biliary leakage from the anastomosis. Conservative therapy was continued because the radioisotope flowed smoothly into the reconstructed jejunum and the biliary drainage catheter, and the leakage was stopped on the 63th postoperative day. Hepatobiliary scan is useful in determining the therapeutic plan as well as detection of bile leakage and identification of leakage points after living donor liver transplantation.

Hepatobiliary scintigraphy in liver transplant patients: the "blind end sign" and its differentiation from bile leak

PURPOSE

Hepatobiliary scintigraphy is commonly performed on liver transplant patients to exclude biliary complications such as obstruction or leak. Biliary reconstruction in these patients is performed using either a direct duct-to-duct anastomosis (choledochocholedochostomy) or a biliary-enteric anastomosis (Roux-en-Y hepaticojejunostomy). The authors have observed a finding in scans performed on the latter group of patients that often simulates a bile leak. They postulate this finding to represent retention of activity in the blind end of the Roux limb (the "blind end sign"). The purpose of this study was to determine characteristics of this blind end activity, which may help differentiate it from true bile leaks.

METHODS

Two nuclear medicine physicians reviewed 36 Tc-99m mebrofenin hepatobiliary scans (31 patients). Biliary reconstruction was performed in 25 patients with a Roux-en-Y hepaticojejunostomy, and in 6 patients with a choledochocholedochostomy. Each scan was evaluated regarding whether there was focal, persistent retention of activity in the anastomotic region, and, if so, various features of the activity were noted. Activity was concluded to represent a true bile leak based on subsequent surgical confirmation, and if there was no such confirmation, the activity was concluded to represent blind end retention in patients with Roux-en-Y hepaticojejunostomies.

RESULTS

There were 8 total examples of blind end activity and 3 examples of bile leak activity. Useful discriminators between the 2 types of activity included the following: fluctuation in size and/or intensity with time (8 of 8 blind end cases vs. 0 of 3 bile leak cases); size comparable with bowel (8 of 8 vs. 1 of 3); tubular (4 of 8 vs. 0 of 3), round (4 of 8 vs. 1 of 3), or irregular (0 of 8 vs. 2 of 3) shape; and movement into bowel (3 of 8 vs. 0 of 3). Delayed imaging was performed in 3 cases at 1.5 hours, but was only conclusive in 1 case in which diffuse extravasation was seen consistent with bile leak.

CONCLUSION

Retention of activity in the blind end of the Roux limb in patients with Roux-en-Y hepaticojejunostomies may simulate bile leak, but certain typical features, as well as delayed imaging, may aid in distinguishing the two.

Radiolabeled annexin V imaging: diagnosis of allograft rejection in an experimental rodent model of liver transplantation

PURPOSE

To assess the value of imaging rejection-induced apoptosis with technetium 99m and annexin V, a human protein-based radiopharmaceutical used in the diagnosis of acute rejection of a liver transplant, in a well-characterized rodent model of orthotopic liver transplantation.

MATERIALS AND METHODS

99mTc-radiolabeled annexin V was intravenously administered to six allografted (immunologically mismatched) and five isografted (immunologically matched) recipient rats on days 2, 4, and 7 after orthotopic liver transplantation. Animals were imaged 1 hour after injection of 0.2-2.0 mCi (8.0-74.0 MBq) of radiolabeled annexin V by use of clinical nuclear scintigraphic equipment.

RESULTS

All animals in the allografted group demonstrated marked increases of 55% and 97% above the activity in the isografted group in hepatic uptake of annexin V on days 4 and 7, respectively. Severe acute rejection was histologically detected in all allografted livers on day 7. There was no histologic evidence of acute rejection in isografted animals. Dynamic hepatobiliary imaging with 99mTc and mebrofenin, an iminodiacetic acid derivative, demonstrated no correlation with the presence or absence of acute rejection or with annexin V uptake.

CONCLUSION

Noninvasive imaging with radiolabeled annexin V is more sensitive and specific than imaging with 99mTc-mebrofenin in the diagnosis of acute rejection of a liver transplant.

Nuclear medicine and the surgeon

Nuclear medicine provides the surgeon with important diagnostic and functional information on specific organs and with therapy for a limited set of diseases. Clinical applications of nuclear medicine are beginning to guide surgeons to specific locations, notably to sentinel lymph nodes in patients with cancer. The role of radionuclide diagnosis in oncology has been covered earlier in this Lancet series, so here is a surgeon's perspective on sentinel node and other oncological applications and on the surgical value of nuclear medicine in non-malignant diseases.

The hepatopulmonary syndrome

The hepatopulmonary syndrome is a disease entity seen in association with liver failure and other disease entities. It is a devastating consequence of liver failure that results in a significant morbidity for affected patients. Currently, there are no identified medications that ameliorate the symptoms of hypoxemia in this disease state. Recent research, however, has begun to unravel the pathobiology of the vascular dilations that arise in the lungs of patients with liver failure. In this article, a compendium of current knowledge is presented, as well as the contemporary methods for identifying and treating patients.

Dual-phase spiral CT angiography with volumetric 3D rendering for preoperative liver transplant evaluation: preliminary observations

PURPOSE

The goal of our study was to determine whether dual-phase spiral CT angiography with 3D volume rendering could be used for preoperative evaluation and patient selection for orthotopic liver transplantation candidates.

METHOD

Fifty consecutive potential candidates for liver transplantation were evaluated with dual-phase spiral CT with 3D volume rendering. Intravenous contrast medium was administered as bolus peripheral injection at 3 ml/s. The protocol consisted of a contrast-enhanced dual-phase spiral CT (arterial phase acquisition at 30 s after initiation of contrast medium injection followed by portal venous phase beginning at 60 s) with scan parameters of 0.75 s gantry rotation speed, 3 mm collimation, 5 to 6 mm/s table speed, and reconstruction at 1 mm intervals for arterial-phase images and 3 mm collimation for portal venous-phase studies (Siemens Plus 4 scanner; Siemens Medical Systems, Iselin, NJ, U.S.A.). All scan information was sent to a free-standing workstation (Silicon Graphics Onyx or Infinite Reality, Mountain View, CA, U.S.A.) for interactive real-time 3D volume rendering using a customized version of the Volren volume renderer (Silicon Graphics; Advanced Imaging Laboratory, Johns Hopkins Medical Institutions, Baltimore, MD, U.S.A.). The arterial phase was used to create vascular maps of the celiac axis including the origin(s) of the hepatic artery and origin of the superior mesenteric artery. The portal phase was used to define portal venous patency as well as the hepatic venous anatomy. All images were analyzed for vascular patency, shunting, or collateralization as well as the status of the underlying liver (i.e., liver size, cirrhosis, tumor, etc.).

RESULTS

All 50 studies were successfully completed without complication. The 3D CT angiograms defined key arterial and venous structures including origin(s) of the hepatic artery, portal vein and/or superior mesenteric vein thrombosis, cavernous transformation of the portal vein, and/or other collateral vasculature. Ten patients (20%) demonstrated anomalous anatomy at the origin(s) of the hepatic artery. Portal vein thrombosis with cavernous transformation of the portal vein was shown in six patients, and there were three cases of partial venous thrombosis. Underlying liver tumors as well as parenchymal liver disease were well defined. Hepatic masses were found in five patients. Masses were pathologically proven as hepatocellular carcinoma (n = 1), giant cavernous hemangioma (n = 1), hepatic adenoma (n = 1), and focal nodular hyperplasia (n = 2).

CONCLUSION

Preliminary results suggest that dual-phase spiral CT with CT angiography can provide a comprehensive preoperative liver transplant evaluation, supplying the necessary information for patient selection and surgical planning. As a single, minimally invasive examination, this should significantly impact patient care by minimizing procedures and avoiding potential complications.

Hepatobiliary scintigraphy in children

Hepatobiliary scintigraphy using iminodiacetic (IDA) radiopharmaceuticals provides clinically useful information on the function of the biliary tract in a variety of pathological processes in children, including neonatal jaundice, gallbladder dysfunction, trauma, and liver transplantation. Phenobarbital premedication (5 mg/kg per day for a minimum of 5 days in divided doses) is used in infants who are being examined for neonatal jaundice to increase the accuracy of 99mTc-IDA scintigraphy in differentiating extrahepatic biliary atresia from neonatal hepatitis. Biliary atresia can be ruled out in an infant if a patent biliary tree is shown with passage of activity into the bowel. If no radiopharmaceutical is noted in the bowel on imaging up to 24 hours, distinction between severe hepatocellular disease and biliary atresia cannot be made. The literature reports 91% accuracy, 97% sensitivity, and 82% specificity for hepatobiliary imaging in the diagnosis of biliary atresia. The impairment of both intrahepatic and extrahepatic biliary drainage is an important cause of liver disease in cystic fibrosis. Hepatobiliary scintigraphy in cystic fibrosis has shown characteristic patterns of dilatation of mainly the left hepatic duct, narrowing of the distal common bile duct, gallbladder dysfunction, and delayed bowel transit. Cholecystitis in children may be acalculous. Sensitivity and specificity for the scintigraphic diagnosis of acute acalculous cholecystitis is reported to range from 68% to 93% and 38% to 93%, respectively. Cholescintigraphy in a suspected bile leak provides information generally not available with other techniques, except for direct cholangiography. If the amount of intraperitoneal accumulation of the tracer is greater than that entering the gastrointestinal tract, surgery is usually indicated. Hepatobiliary imaging in children who have undergone liver transplantation will assess graft vascularity, parenchymal function, biliary drainage, presence of a leak, and obstruction.