Utility of Quantitative Assessment of Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl Human Serum Albumin SPECT/CT in the Identification of Severe Liver Fibrosis: Its Complementary Diagnostic Value with Other Liver Function Indices.

Purpose: To evaluate the value of Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl human serum albumin (Tc-GSA) single photon emission computed tomography (SPECT) for assessing liver fibrosis, and to assess its complementary value to other liver function indices such as fibrosis-4 (FIB-4) index and indocyanine green (ICG) clearance test parameters (ICG-R15 and ICG-K).

Procedures: Seventy-eight patients with chronic liver disease and hepatocellular carcinoma who underwent Tc-GSA scintigraphy and other liver function tests including ICG test and FIB-4 index prior to hepatectomy were studied. Tc-GSA imaging was performed with SPECT/CT scanner (Discovery NM/CT 670). Immediately after injection of Tc-GSA, dynamic imaging was performed for 20 min, followed by SPECT data acquisition for 6 min. LHL15 which is a conventional index by Tc-GSA planar images, and liver uptake ration (LUR) was measured from Tc-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 and specificity for identifying F4 was 88% and 85%, respectively, with LUR cutoff value of 41.2%.

Conclusions: LUR, measured by Tc-GSA SPECT, is a useful indicator for identifying sever liver fibrosis. Particularly in patients with high FIB-4 index (≥ 3.16), LUR can be a valuable indicator to identify severe liver fibrosis with high diagnostic accuracy.