Utility of quantitative analysis of 99mTc-GSA SPECT/CT in the evaluation of liver fibrosis: comparison with conventional assessment on planar images and its complementary diagnostic value with other liver function indices

Abstract

Abstract Objective To evaluate the potential value of quantitative Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl human serum albumin (99mTc-GSA) SPECT in the assessment of liver fibrosis compared to a conventional index based on planar images (LHL15), and to assess its complementary value to other liver function indices such as fibrosis-4 (FIB-4) index and indocyanine green (ICG) clearance test (ICG-R15, ICG-K). Methods Seventy-eight consecutive patients with suspected chronic liver disease and hepatocellular carcinoma who underwent 99mTc-GSA scintigraphy and other liver function tests including ICG test and FIB-4 index as the workup prior to hepatectomy were studied. 99mTc-GSA image data were acquired with a SPECT/CT scanner (Discovery NM/CT 670) equipped with low-energy high-resolution collimator. Immediately after intravenous injection of median dose of 185 MBq of 99mTc-GSA, dynamic imaging was performed for 20 min, followed by SPECT data acquisition for 6 min. LHL15, a conventional index, was measured from the planar images, and the liver uptake ration (LUR) was measured from the 99mTc-GSA SPECT images. From the liver resection specimens, the degree of liver fibrosis was graded according to the Ludwig scale (F0-4). Results Significant differences in LUR, LHL15, ICG-R15, ICG-K, platelet count and FIB-4 index were found between the F0-3 and F4 liver fibrosis patient groups (P < 0.05). Multivariate logistic regression analysis revealed that LUR and ICG-K were independent factors for identifying severe liver fibrosis (F4). Area under the curve of receiver operating curve analysis for the logistic regression model using LUR and ICG-K was 0.83. In the patient group with higher FIB-4 (≥ 3.16), the diagnostic performance of LUR for detecting severe liver fibrosis was significantly better than LHL15 (AUC: 0.83 vs. 0.75, P = 0.048). In the high FIB-4 index group, the sensitivity, specificity, positive predictive value, and negative predictive value for the identification of severe liver fibrosis were 88%, 85%, 88%, and 85%, respectively, when using the cutoff value of 41.2% for LUR. Conclusions LUR measured by quantitative analysis of 99mTc-GSA SPECT reflects the severity of liver fibrosis more accurately than the conventional index from planar imaging. In patients with high FIB-4 index, LUR is a useful indicator to identify severe liver fibrosis with high diagnostic accuracy.