Background
Before a hepatectomy, it is necessary to evaluate liver function and estimate the function of the future liver remnant. Assessment of hepatic functional reserve is one of the most important issues in hepatic resection [
1‐
4]. This is especially true for patients with both hepatocellular carcinoma (HCC) and liver cirrhosis, or both hilar cholangiocarcinoma and jaundice, that often need an extended hepatectomy. To avoid a resection that would likely lead to postoperative hepatic failure, various methods have been developed for the preoperative assessment of liver function. However, some of these are complex and require calculations involving multiple formulas. To estimate the hepatic functional reserve,
99mTc-labelled diethylene triamine pentaacetate–galactosyl-human serum albumin (
99mTc-GSA), a radiopharmaceutical that binds specifically to the hepatic asialoglycoprotein receptor (ASGP-R) has been developed and used clinically to estimate hepatic function [
5,
6]. Because ASGP-R is a natural superficial antigen of viable hepatocytes, the uptake of
99mTc-GSA is independent of biochemical processes and allows direct estimation of the functioning hepatocyte mass [
7]. In addition, the distribution of
99mTc-GSA in the liver is not dependent on liver blood flow [
8]. Koizumi et al. reported that several parameters for
99mTc-GSA liver scintigraphy were estimated and that LU3 and GSAR15 were interesting and promising parameters for assessing liver function [
9].
When a hepatic resection involves more than two sections, evaluation of future functional reserve by using 99mTc-GSA and computed tomography (CT) combined fusion images is currently supposed to be more accurate than a combined estimation using an indocyanine green (ICG) retention test and CT [
10]. In this study, remnant liver LU15, which was considered the remnant hepatic functional reserve, was estimated using
99mTc-GSA single-photon emission computed tomograpic (SPECT) scintigraphy and CT fusion images. In addition, the functional reserve of the future liver remnant was also estimated before surgery by using fusion images obtained from contrast-enhanced CT and
99mTc-GSA SPECT, and was used to predict liver failure after a hepatic resection. A retrospective study was performed to determine whether the remnant liver LU15 value could enable a final decision regarding a hepatectomy in order to avoid postoperative hepatic failure.
Results
The mean age of the patients was 70 years, with a range of 23 to 85 years. There were 87 (71%) male and 36 (29%) female patients, yielding a male:female ratio of 2:1; the patients’ Child-Pugh grades included A (94%) and B (6%). The surgical procedures consisted of a partial resections (15), segmentectomy (18), mono-sectionectomy (31), hemihepatectomy (53), and tri-sectionectomy (6) (Table
1). In 21 patients with portal vein occlusion, remnant liver volume increased from 490 g to 607 g.
Ninety six patients within Makuuchi criteria and 27 patients developed without Makuuchi criteria (Fig.
1). 13 patients of all 96 patients within Makuuchi criteria developed without criteria for remnant liver LU15. And 27 patients without Makuuchi criteria were within criteria for remnant liver LU15. Total seven patients developed potoperative hepatic failure over grade B. Table
2 shows the details of seven patients developed postoperative hepatic failure. Two patients developed hepatic failure grade C were performed sgmentectomy, S7/8 segmentactomy and S8 segmentectomy. All two patients died of a hepatic failure while still in the hospital.
Table 2
Patients with postoperative hepatic failure grade B/C
68 | F | CCC | A | (-) | 9.5 | 16.7 | 11.5 | Left Hemi. | HF grade B |
73 | F | HCC | A | (-) | 12.3 | 15.2 | 12.6 | Left Hemi. | HF grade B |
68 | M | HCC | A | (-) | 17.8 | 14.1 | 12.1 | Left Hemi. | HF grade B |
71 | M | HCC | A | (-) | 15.0 | 12.6 | 10.7 | S8 Seg. | HF grade B |
72 | M | HCC | A | (-) | 7.2 | 26.3 | 12.8 | S7/8 Seg. | HF grade C |
85 | M | HCC | A | (-) | 28.5 | 16.1 | 12.3 | S8 Seg. | HF grade C |
73 | M | HCC | A | (+) | 11.0 | 31.1 | 18.8 | Right Tri. | HF grade B |
Table
3 shows the hazard ratios (HR) for the candidate risk factors associated with postoperative hepatic failure as calculated by the univariate and multivariate analysis. Although serum albumin concentration, ICGR15, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and the other factors including the ICGR15 criteria by Makuuchi, et al. were not risk factors, operative time and the criteria for remnant liver LU15 were risk factors for postoperative hepatic failure by univariate analysis. And the criteria for remnant liver LU15 was an only risk factor for postoperative hepatic failure by multivariate analysis.
Table 3
Prognostic factor for postoperative hepatic failure
Univariate analysis | Odds ratio | 95% CI |
p-value |
Age | 1.175 | 0.950–1.351 | 0.1239 |
Sex |
Male | 1 | | |
Female | 1.024 | 0.189–5.538 | 0.9779 |
Child-Pugh grade |
A | 1 | | |
B | 2.944 | 0.304–6.540 | 0.3514 |
ICG R15 | 1.001 | 0.996–1.007 | 0.5973 |
Total billirubin | 0.004 | 0.001–7.003 | 0.1451 |
Albumin | 0.214 | 0.019–3.656 | 0.2870 |
AST | 0.983 | 0.921–1.049 | 0.6065 |
Prothoronbin test | 0.946 | 0.847–1.057 | 0.3270 |
Intraoperative blood loss | 1.000 | 0.998–1.001 | 0.6229 |
Operation time | 1.137 | 1.017–1.271 | 0.0242 |
LHL 15 | 0.041 | 0.007–15.070 | 0.3927 |
HH 15 | 0.074 | 0.009–72.115 | 0.6485 |
LU 15 | 0.965 | 0.884–1.054 | 0.9650 |
Remnant liver LU 15 | 0.915 | 0.789–1.062 | 0.2425 |
Makuuchi criteria |
Within | 1 | | |
Without | 1.400 | 0.257–7.640 | 0.6975 |
Criteria for remnant liver LU15 |
> 13.0 | 1 | | |
< 13.0 | 81.750 | 8.741–764.566 | 0.0001 |
Multivariate analysis |
Operation time | 1.073 | 0.938–1.226 | 0.3041 |
Criteria for remnant liver LU15 | 67.724 | 6.840–670.561 | 0.0009 |
Discussion
In this study, we attempted to develop a preoperative risk marker for predicting postoperative hepatic failure in patients with any diseases that were candidates for a hepatic resection using 99mTc-GSA scintigraphy. After a bolus intravenousinjection of a radiotracer, sequential anterior abdominal 128 X 128 matrix size images, including the liver and heart, were acquired every 20 s for 20 min. The parameters; HH15, LHL15 and LU15 were calculated from the time-activity curves. Two parameters, HH15 and LHL15, should be used together as complementary indications of liver function, because these parameters seem to reach a plateau value in cases of severe liver dysfunction in HH15 and in cases of liver function improvement in LHL15. In this study, HH15 and LHL15 had week correlation with ICGR15 (data not shown), and the criteria for LHL15 and HH15 were not risk factors for postoperative hepatic failure in univariate analysis. Therefore, HH15 and LHL15 might not be suitable surrogate marker for postoperative hepatic failure. Because LU15 has the advantages of a wider range and a higher value level, as well as better correlation with that of other parameters except ICGR15, LU15 is expected to be the best parameter for regional liver function and seem to be the good surrogate marker for postoperative hepatic failure.
Measurement of the remnant liver volume using planar images obtained by
99mTc-GSA scintigraphy is not accurate, but by creating a cut line in each section of the transaxial or frontal SPECT image, precise measurement of the remnant liver hepatic binding concentration is possible [
16]. The amount of remnant liver LU15 could be calculated more correctly before surgery by using fusion images of
99mTc-GSA SPECT and contrast-enhanced CT scans with the Vinsent software. By using these fusion images, any resection area (partial resection, sub-segmentectomy, and any sectionectomy) could be drawn manually on SPECT scans on the basis of the anatomy observed on CT, permitting calculation of the volume of the future liver remnant. Moreover, remnant liver LU15 could be evaluated in cases with obstructive jaundice (for example, hilar cholangiocarcinoma) or a post portal vein embolization, because the hepatic asialoglycoprotein receptor is not affected by jaundice or a portal vein embolization. Thus, radioactivity within the volume of the future liver remnant could be estimated and the remnant liver LU15 values could be calculated.
Many authors have reported methods for assessing liver volume and function using a standard CT,
99mTc-GSA SPECT, or both [
17,
18]. In HCC with liver cirrhosis, chronic hepatitis or fibrosis, hepatic dysfunction in the hepatic segment or lobe containing HCC was greater than that of the segments or lobe without HCC because the liver parenchyma around the tumor was damaged by mechanical compression, possibly the result of tumor compression of the vessels and bile ducts. If hepatic CT and SPECT images obtained using
99mTc-GSA were compared, the defect seen on the SPECT images was larger than that of the tumor seen on the CT image. On the other hand, for cases of hilar cholangiocarcinoma with high serum bilirubin levels, we clarified the usefulness of
99mTc-GSA volumetry because evaluation of the ICG test was unreliable, as bilirubin competes with hepatic ICG excretion. Further, a diseased liver without drainage of the obstructive bile duct showed poor functioning. Application of volumetry by
99mTc-GSA scintigraphy might address the limitations of the ICG test, as this test can evaluate separated liver functions in any situation or background liver function [
19]. In this study, remnant liver volume estimated by CT volumetry was greater than that of
99mTc-GSA scintigraphy in cases of hilar cholangiocarcinoma (data not shown).
Other studies have evaluated a variety of quantitative liver function tests to predict the risk of postoperative death and complications. Conventional biochemical liver tests, such as serum bilirubin, prothrombin time, and Child-Pugh classification, have only limited value with respect to estimating the hepatocellular reserve. Yamanaka et al. reported that an ICG test, in combination with a radiologic estimation of the liver volume, was of value for predicting liver failure after a hepatectomy [
20]. Kinetic analysis of hepatic ICG uptake has been a useful method to evaluate hepatic function, and has been reported to be a good preoperative predictor of death and complications in patients undergoing a liver resection for HCC [
21]. The occasional discrepancy between the ICG clearance values and histologic liver findings are thought to depend mainly on the hepatic blood supply and intra/extrahepatic shunt. First, ICG retention is expected to increase in patients with jaundice, because ICG is excreted into the biliary system. Second, a rare constitutional dye excretory disorder has been reported. Moreover, as a test agent, it is well-known that ICG has some adverse reactions such as shock, nausea, rashes and itching. The ability to make a final decision about the extent of liver resection with an underlying liver disease requires new methods to estimate the functional hepatic reserve in the predicted remnant liver, rather than the entire liver.