A pilot study by researchers in China suggests that PET/CT imaging with gallium-68 (Ga-68) fibroblast activation protein inhibitor (FAPI)-04 may be an effective method for assessing liver fibrosis.
In an analysis of 14 patients, the technique performed better than standard ultrasound and blood-based diagnostic methods, noted corresponding author Yue Chen, MD, of the Affiliated Hospital of Southwest Medical University in Luzhou, and colleagues.
“The results of this preliminary study suggest that Ga-68 FAPI-04 PET/CT may be an effective noninvasive method for assessing liver fibrosis and could potentially outperform FIB-4 and Fibroscan,” the group wrote. The study was published January 11 in Scientific Reports.
Liver fibrosis is a common pathological consequence of chronic liver diseases and represents a major global health burden due to its potential to progress to cirrhosis, liver failure, and hepatocellular carcinoma, the authors explained. Current standard methods for diagnosing the condition include serum-based laboratory tests such as the Fibrosis-4 (FIB-4) index and transient elastography (FibroScan, Echosens), yet both methods can be suboptimal in patients with comorbidities such as diabetes or inflammation, the authors noted.
Given that Ga-68 FAPI-PET/CT can visualize the primary activated cells in fibrosis development (hepatic stellate cells), the group hypothesized that the molecular imaging technique may be more accurate. To test the hypothesis, the researchers recruited 14 patients with chronic liver diseases between October 2022 and September 2023. Nine participants had hepatitis B virus, three had primary biliary cholangitis, and two had PBC/autoimmune hepatitis (AIH) overlap syndrome.
All participants underwent blood tests, FibroScans, liver biopsies, and PET/CT scans. Two experienced nuclear medicine physicians then compared the diagnostic performance of the three methods using sensitivity, specificity, and positive predictive value (PPV).
Images of a 55-year-old man with a 10-year history of hepatitis B virus infection. He presented with abdominal distension and yellowing of the skin and sclera for six months. The maximum intensity projection (MIP) image of Ga-68 FAPI-PET/CT showed diffuse tracer uptake in the liver region. Axial images showed significant liver uptake with abdominal effusion (SUVmean = 3.13; TBRliver-to-blood = 2.84; TLfap = 41.3). F4 level of liver fibrosis was confirmed by liver biopsy.Scientific ReportsAccording to the results, Ga-68 FAPI-04 PET/CT yielded a sensitivity of 87.5%, specificity of 83.3%, and PPV of 87.5%. Both FIB-4 and Fibroscan correctly classified 10 out of 14 (71.4%) participants, while Ga-68 FAPI-04 PET/CT successfully differentiated 12 of 14 (85.7%) participants (weighted kappa = 0.841).
“Our study provides initial clinical evidence that Ga-68 FAPI-04 PET/CT may offer better diagnostic performance,” the investigators wrote.
They explained that the findings are consistent with those in two previous clinical studies: One larger retrospective study demonstrated that Ga-68 FAPI-04 uptake correlated with clinical indicators of liver fibrosis, and another prospective study showed that Ga-68 FAPI-04 PET uptake values differ across grades of liver fibrosis. However, their study is among the first to compare diagnostic efficacy between Ga-68 FAPI-04 PET and existing noninvasive methods, they noted.
Further research is warranted, according to the group.
“Larger clinical trials are necessary to confirm these findings and further evaluate its clinical utility,” Chen and colleagues concluded.
The full study is available here.