Improved reproducibility of simple quantitative indices from ⁹⁹mTc-GSA liver functional imaging

Liver function and image evaluation after radiotherapy for liver metastases after resection of sigmoid colon cancer a case report

INTRODUCTION

Radiotherapy is a treatment option in the management of patients with metastatic liver disease. The aim in this case was to evaluate radiation-induced dysfunctional liver lesions using 99mTc-GSA-SPECT, Gd-EOB-DTPA-enhanced MRI, and radiation dose distribution in a patient after radiation therapy.

PRESENTATION OF CASE

After sigmoid colon resection, three liver metastases were treated with radiotherapy at the same time. Liver function after radiotherapy was determined to be A according to the Child-Turcott-Pugh classification. 99mTc-GSA-SPECT showed a wider reduction in uptake than Gd-EOB-DTPA MRI at all three sites. HH15 showed decreased liver function.

DISCUSSION

In the 99mTc-GSA-SPECT and Gd-EOB-DTPA MRI hepatocyte phases, residual signals of normal hepatocytes were observed despite irradiation at three sites. Additional treatment could be considered for the two recurrent lesions because there was no deterioration of liver function in post-irradiation imaging findings and blood sampling.

CONCLUSION

99mTc-GSA-SPECT and EOB-MRI showed characteristic findings for evaluation of liver function after radiotherapy for multiple liver metastases, suggesting the need for both imaging evaluations. It is now possible to choose whether to perform local additional treatment (additional radiation, RFA) or other chemotherapy for liver metastases after recurrence.

Deep learning-based attenuation correction method in 99mTc-GSA SPECT/CT hepatic imaging: a phantom study

This study aimed to evaluate a deep learning-based attenuation correction (AC) method to generate pseudo-computed tomography (CT) images from non-AC single-photon emission computed tomography images (SPECTNC) for AC in 99mTc-galactosyl human albumin diethylenetriamine pentaacetic acid (GSA) scintigraphy and to reduce patient dosage. A cycle-consistent generative network (CycleGAN) model was used to generate pseudo-CT images. The training datasets comprised approximately 850 liver phantom images obtained from SPECTNC and real CT images. The training datasets were then input to CycleGAN, and pseudo-CT images were output. SPECT images with real-time CT attenuation correction (SPECTCTAC) and pseudo-CT attenuation correction (SPECTGAN) were acquired. The difference in liver volume between real CT and pseudo-CT images was evaluated. Total counts and uniformity were then used to evaluate the effects of AC. Additionally, the similarity coefficients of SPECTCTAC and SPECTGAN were assessed using a structural similarity (SSIM) index. The pseudo-CT images produced a lower liver volume than the real CT images. SPECTCTAC exhibited a higher total count than SPECTNC and SPECTGAN, which were approximately 60% and 7% lower, respectively. The uniformities of SPECTCTAC and SPECTGAN were better than those of SPECTNC. The mean SSIM value for SPECTCTAC and SPECTGAN was 0.97. We proposed a deep learning-based AC approach to generate pseudo-CT images from SPECTNC images in 99mTc-GSA scintigraphy. SPECTGAN with AC using pseudo-CT images was similar to SPECTCTAC, demonstrating the possibility of SPECT/CT examination with reduced exposure to radiation.

Prognostic value of future liver remnant LU15 index of 99mTc-galactosyl serum albumin scintigraphy for predicting posthepatectomy liver failure

There is no gold standard indicator that is currently used to predict posthepatectomy liver failure (PHLF). A novel indicator of liver function, the LU15 index of ^99mTc-galactosyl serum albumin (GSA) scintigraphy, refers to the liver uptake ratio over a 15-min interval. We aimed to evaluate the usefulness of the future liver remnant (FLR)-LU15 in predicting PHLF. The clinical data of 102 patients (70 males and 32 females; median age, 70 years) who underwent liver resection between January 2011 and August 2019 were analyzed. The FLR-LU15 was calculated by a fusion of simulated 3-dimensional images and ^99mTc-GSA scintigraphy. PHLF was determined according to the definition of the International Study Group of Liver Surgery. The FLR-LU15 was an independent risk factor for PHLF ≥ Grade B according to multivariate analysis, and its value correlated with the PHLF grade. The area under the receiver operating characteristic curve of the FLR-LU15 for PHLF ≥ Grade B was 0.816 (95% confidence interval, 0.704–0.929), which was better than that of other indicators. When the cut-off value of FLR-LU15 was set at 16.7, the sensitivity was 86.7%, specificity was 74.7%, and odds ratio was 19.2 (95% confidence interval, 4.0–90.9), all of which were superior to other indicators. If the cut-off value was 13, the positive predictive value was 57.1%. The FLR-LU15 is a useful predictor of PHLF and may be more reliable than other predictors.

[Novel Index (Hepatic Receptor: IHR) to Evaluate Hepatic Functional Reserve Using (99m)Tc-GSA Scintigraphy]

PURPOSE

This study aimed to evaluate the novel index of hepatic receptor (IHR) on the regression analysis derived from time activity curve of the liver for hepatic functional reserve.

METHODS

Sixty patients had undergone (99m)Tc-galactosyl serum albumin ((99m)Tc-GSA) scintigraphy in the retrospective clinical study. Time activity curves for liver were obtained by region of interest (ROI) on the whole liver. A novel hepatic functional predictor was calculated with multiple regression analysis of time activity curves. In the multiple regression function, the objective variables were the indocyanine green (ICG) retention rate at 15 min, and the explanatory variables were the liver counts in 3-min intervals until end from beginning. Then, this result was defined by IHR, and we analyzed the correlation between IHR and ICG, uptake ratio of the heart at 15 minutes to that at 3 minutes (HH15), uptake ratio of the liver to the liver plus heart at 15 minutes (LHL15), and index of convexity (IOC).

RESULTS

Regression function of IHR was derived as follows: IHR=0.025×L(6)-0.052×L(12)+0.027×L(27). The multiple regression analysis indicated that liver counts at 6 min, 12 min, and 27 min were significantly related to objective variables. The correlation coefficient between IHR and ICG was 0.774, and the correlation coefficient between ICG and conventional indices (HH15, LHL15, and IOC) were 0.837, 0.773, and 0.793, respectively. IHR had good correlation with HH15, LHL15, and IOC.

CONCLUSIONS

The finding results suggested that IHR would provide clinical benefit for hepatic functional assessment in the (99m)Tc-GSA scintigraphy.

Clinical implication of the preoperative GSA index in ⁹⁹mTc-GSA scintigraphy in hepatitis C virus-related hepatocellular carcinoma

We aimed to examine the relationship between the preoperative GSA index [uptake ratio of the liver to the liver plus heart at 15 min (LHL15) to uptake ratio of the heart at 15 min to that at 3 min (HH15) ratio] calculated from 99mTc‑labeled diethylene triamine pentaacetate-galactosyl human serum albumin (99mTc-GSA) scintigraphy and background liver fibrosis and to investigate whether the GSA index can be a useful predictor in hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC) patients treated with surgical resection (SR). A total of 213 HCV-related HCC patients were analyzed. Receiver operating characteristic (ROC) curve analysis was performed for calculating the area under the ROC (AUROC) for nine noninvasive parameters including GSA index, indocyanine green retention at 15 min, aspartate aminotransferase (AST) to platelet ratio index, FIB-4 index, AST to alanine aminotransferase ratio, serum albumin, total bilirubin, platelet count and prothrombin time for cirrhosis. We also examined predictive factors associated with overall survival (OS) and recurrence-free survival (RFS) after SR in univariate and multivariate analyses. There were 153 males and 60 females with the mean age of 69.9 years. The median observation periods were 2.8 years. The mean maximum tumor size was 4.1 cm. HH15 ranged from 0.452 to 0.897. LHL15 ranged from 0.669 to 0.982. The mean value of the GSA index was 1.41. Among the nine parameters, the GSA index yielded the highest AUROC for cirrhosis with a level of 0.786 at an optimal cut-off value of 1.37 (sensitivity, 65.9%; specificity, 79.0%). In multivariate analyses, the GSA index was an independent predictor (P<0.001) linked to RFS and it had a marginal significance in terms of OS (P=0.074). In conclusion, the preoperative GSA index can be a useful predictor in HCV-related HCC patients treated with SR.

[Study of heart region of interest setting method in the hepatic functional reserve index of (99m)tc-diethylenetriamine pentaacetic Acid-galactosyl human serum albumin]

In this study we analyzed the influence of region of interest (ROI) selection on the uptake ratio of the liver to the liver plus heart at 15 min (LHL15) during (99m)Tc-galactosyl human serum albumin (GSA) scintigraphy and determined the optimal ROI by evaluating the individual effects of different ROIs in the heart on LHL15. Twenty patients were randomly selected from those who had undergone (99m)Tc-GSA scintigraphy GSA between April 2008 and June 2009. The liver body (L/B) ratio, liver uptake 15 min (LU15), and LHL15 were analyzed and compared among the following ROIs: entire heart, both ventricles, right ventricle, and left ventricle. There were significant differences in the L/B ratio and LU15 values among the different ROIs. However, LHL15 showed a tendency to shift toward a normal value when the size of the ROI was small (only the right or left ventricle), resulting in a lack of distinction between normal and abnormal LHL15 values. Furthermore, setting the entire heart as the ROI was difficult and reproducibility was low. Our results suggest that the use of both ventricles as the ROI provides optimal LHL15 values during (99m)Tc-GSA scintigraphy.