Auxiliary liver transplantation in patients with fulminant hepatic failure: hepatobiliary scintigraphic follow-up

Interstage Assessment of Remnant Liver Function in ALPPS Using Hepatobiliary Scintigraphy: Prediction of Posthepatectomy Liver Failure and Introduction of the HIBA Index

OBJECTIVE

The aim of this study was to evaluate interstage liver function in associating liver partition and portal vein occlusion for staged hepatectomy (ALPPS) using hepatobiliary scintigraphy (HBS) and whether this may help to predict posthepatectomy liver failure (PHLF).

BACKGROUND

ALPPS remains controversial given the high rate of liver-related mortality after stage 2. HBS combined with single photon emission computed tomography (SPECT) accurately estimates future liver remnant function and may be useful to predict PHLF.

METHODS

Between 2011 and 2016, 20 of 39 patients (51.3%) underwent SPECT-HBS before ALPPS stage 2 for primary (n = 3) or secondary liver tumors (n = 17) at the Hospital Italiano de Buenos Aires (HIBA). PHLF was defined by the International Study Group of Liver Surgery criteria, 50-50 criteria, or peak bilirubin >7 mg/dL. Grade A PHLF was excluded, as it requires no change in clinical management. Receiver-operating characteristic curves were used to determine cutoff for HBS parameters.

RESULTS

Interstagely, 3 HBS parameters differed significantly between patients with (n = 4) and without PHLF (n = 16) after stage 2. Among these, the HIBA-index best predicted PHLF, with a cutoff value of 15%. The risk of PHLF in patients with cutoff <15% was 80%, whereas no patient with cutoff ≥15% developed PHLF.

CONCLUSIONS

Interstage HBS could help to predict clinically significant PHLF after ALPPS stage 2. An HIBA-index cutoff of 15% seemed to give the best diagnostic performance. Although further studies are needed to confirm our findings, the routine application of this noninvasive low-cost examination could facilitate decision-making in institutions performing ALPPS.

Blood-Brain Barrier Permeability Is Exacerbated in Experimental Model of Hepatic Encephalopathy via MMP-9 Activation and Downregulation of Tight Junction Proteins

The present study was designed to investigate the mechanisms involved in blood-brain barrier (BBB) permeability in bile duct ligation (BDL) model of chronic hepatic encephalopathy (HE). Four weeks after BDL surgery, a significant increase was observed in serum bilirubin levels. Masson trichrome staining revealed severe hepatic fibrosis in the BDL rats. ^99mTc-mebrofenin retention was increased in the liver of BDL rats suggesting impaired hepatobiliary transport. An increase in permeability to sodium fluorescein, Evans blue, and fluorescein isothiocyanate (FITC)-dextran along with increase in water and electrolyte content was observed in brain regions of BDL rats suggesting disrupted BBB. Increased brain water content can be attributed to increase in aquaporin-4 mRNA and protein expression in BDL rats. Matrix metalloproteinase-9 (MMP-9) mRNA and protein expression was increased in brain regions of BDL rats. Additionally, mRNA and protein expression of tissue inhibitor of matrix metalloproteinases (TIMPs) was also increased in different regions of brain. A significant decrease in mRNA expression and protein levels of tight junction proteins, viz., occludin, claudin-5, and zona occluden-1 (ZO-1) was observed in different brain regions of BDL rats. VCAM-1 mRNA and protein expression was also found to be significantly upregulated in different brain regions of BDL animals. The findings from the study suggest that increased BBB permeability in HE involves activation of MMP-9 and loss of tight junction proteins.

Liver function testing with nuclear medicine techniques is coming of age

Liver function is a broad term, as the organ participates in a multitude of different physiological and biochemical processes, including metabolic, synthetic, and detoxifying functions. However, it is the function of the hepatocyte that is central to sustaining normal life and dealing with disease states. When the liver begins to fail in severely ill patients, it forecasts a terminal outcome. However, unlike the glomerular filtration rate which clearly quantifies the key renal function, at most practice sites, there is no clinically available quantitative test for liver function. Although it is commonplace to assess indirect evidence of that function (by measuring blood levels of its end products and by-products) and to detect an acute injury (by following rising transaminases), a widely available test that would directly measure hepatocellular function is lacking. This article reviews current knowledge on liver function studies and focuses on those nuclear medicine tests available to study the whole liver and regional liver function. The clinical application driving these tests, prediction of remnant liver function after partial hepatectomy for primary liver malignancy or metastatic disease, is addressed here in detail. The test was recently validated for this specific application and was shown to be better than the current standard of practice (computed tomography volumetry), particularly in patients with hepatic comorbidities like cirrhosis, steatosis, or cholestasis. Furthermore, early assessment of regional liver function increase after preoperative portal vein embolization becomes possible with this technology. The limiting factor to a wider acceptance of this test is based on the lack of clinical software that would allow calculation of liver function parameters. This article provides information that enables a clinical nuclear medicine facility to provide this test using readily available equipment. Furthermore, it addresses emerging clinical applications that are under investigation.

Nuclear imaging techniques for the assessment of hepatic function in liver surgery and transplantation

This review describes the application of 2 nuclear imaging techniques for assessment of hepatic function in the setting of liver surgery and transplantation. The biochemical and technical background, as well as the clinical applications, of (99m)Tc-labeled diethylenetriaminepentaacetic acid galactosyl human serum albumin (GSA) scintigraphy and hepatobiliary scintigraphy (HBS) with (99m)Tc-labeled iminodiacetic acid derivates is discussed. (99m)Tc-mebrofenin is considered the most suitable iminodiacetic acid agent for (99m)Tc-HBS. (99m)Tc-GSA scintigraphy and (99m)Tc-mebrofenin HBS are based on 2 different principles. (99m)Tc-GSA scintigraphy is a receptor-mediated technique whereas HBS represents hepatic uptake and excretion function. Both techniques are noninvasive and provide visual and quantitative information on both total and regional liver function. They can be used for preoperative assessment of future remnant liver function, follow-up after preoperative portal vein embolization, and evaluation of postoperative liver regeneration. In liver transplantation, these methods are used to assess graft function and biliary complications.

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.

Auxiliary partial orthotopic versus standard orthotopic whole liver transplantation for acute liver failure: a reappraisal from a single center by a case-control study

OBJECTIVE

To reappraise the results of auxiliary partial orthotopic liver transplantation (APOLT) compared with those of standard whole-liver transplantation (OLT) in terms of postoperative death and complications, including neurologic sequelae.

SUMMARY BACKGROUND DATA

Compared with OLT, APOLT preserves the possibility for the native liver to recover, and to stop immunosuppression.

METHODS

In a consecutive series of 49 patients transplanted for fulminant or subfulminant hepatitis, 37 received OLT and 12 received APOLT. APOLT was done when logistics allowed simultaneous performance of graft preparation and the native liver partial hepatectomy to revascularize the graft as soon as possible. Each patient undergoing APOLT (12 patients) was matched to two patients undergoing OLT (24 patients) according to age, grade of coma, etiology, and fulminant or subfulminant type of hepatitis. All grafts in the study population were retrieved from optimal donors.

RESULTS

Before surgery, both groups were comparable in all aspects. In-hospital death occurred in 4 of 12 patients undergoing APOLT compared with 6 of 24 patients undergoing OLT. Patients receiving APOLT had 1 +/- 1.3 technical complications compared with 0.3 +/- 0.5 for OLT patients. Bacteriemia was significantly more frequent after APOLT than after OLT. The need for retransplantation was significantly higher in the APOLT patients (3/12 vs. 0/24). Brain death from brain edema or neurologic sequelae was significantly more frequent after APOLT (4/12 vs. 2/24). One-year patient survival was comparable in both groups (66% vs. 66%), and there was a trend toward lower 1-year retransplantation-free survival rates in the APOLT group (39% vs. 66%). Only 2 of 12 (17%) patients had full success with APOLT (i.e., patient survival, liver regeneration, withdrawal of immunosuppression, and graft removal). One of these two patients had neurologic sequelae.

CONCLUSIONS

Using optimal grafts, APOLT and OLT have similar patient survival rates. However, the complication rate is higher with APOLT. On an intent-to-treat basis, the efficacy of the APOLT procedure is low. This analysis suggests that the indications for an APOLT procedure should be reconsidered in the light of the risks of technical complications and neurologic sequelae.

T1 relaxation times for viability evaluation of the engrafted and the native liver in a rat model of heterotopic auxiliary liver transplantation: a pilot study

Following a heterotopic auxiliary liver transplantation, commonly used measurements are either invasive or non-indicative of individual viability of the coexisting engrafted and native livers. Magnetic resonance imaging (MRI) was therefore tested for its potential to monitor the post-transplant hepatic viability in a rat model. Thirteen Wistar rats were systematically evaluated with MRI and serum biochemical liver parameters. Post-transplant complications and the causes of animal death were identified by autopsy and histo-pathological examinations. The data of the healthy survivors were compared with those of the rats that developed complications. On MRI, the hepatic complications could be depicted in the individual livers. A specific pattern of signal evolution was found in the livers of the healthy survivors: the mean T1 relaxation times of the engrafted livers increased immediately after transplantation (476 +/- 64 ms, mean +/- standard deviation, pre-operative; 730 +/- 48 ms, week 1) and then declined steadily to a 3 month value of 489 +/- 246 ms, while, following a transient first rise (476 +/- 64 ms, pre-operative; 589 +/- 28 ms, week 1), the mean T1 value of the native livers increased again 4 weeks after surgery and reached a 3 month value of 859 +/- 43 ms. However, in the rats with various complications, the mean T1 relaxation times of the engrafted livers continued to increase throughout the first post-operative month (760 +/- 48 ms, week 1; 922 +/- 76 ms, week 4), while that of the native liver only varied mildly (546 +/- 25 ms, week 1; 473 +/- 25 ms, week 4). After the first post-transplant week, the healthy engrafted livers could already be distinguished from those with complications by a significant decrease in T1 relaxation times. These data suggest that, besides demonstrating major complications, MRI may allow one to monitor the viability of each liver by analysing the relative signal intensity and T1 relaxation times after a heterotopic auxiliary liver transplantation.

New approaches to supporting the failing liver

With the continued, growing disparity between the numbers of organ donations and patients waiting for liver transplantation, various efforts have been made to optimize the allocation of organs, as well as to devise means to support the failing liver. Over the years, the development of bioartificial liver-assist devices has aimed at replacing the three main functions of hepatocytes, which are synthetic, metabolic, and excretory. The application of porcine hepatocytes in humans to carry out biotransformation, as well as other metabolic functions and refinement of the membrane separator, have yielded some promising results in supporting patients with acute liver failure. Further advances will need to be made before these bioartificial devices can be considered for routine application in clinical settings.