Role of 68Ga-FAPI PET/CT in Assessing Hepatobiliary Malignancies

Abstract

Introduction and AimPreliminary studies showed good expression of fibroblast activating protein inhibitor (FAPI) in hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). Our aims were to study the diagnostic performance of 68Ga-FAPI PET/CT in diagnosing the primary hepatobiliary malignancies and to compare its performance with 18F-FDG PET/CT.Patients and MethodsPatients suspected to have HCC and CC were recruited prospectively. FDG and FAPI PET/CT studies were completed within 1 week. Final diagnosis of malignancy was achieved by tissue diagnosis (either histopathological examination or fine-needle aspiration cytology) and radiological correlation from conventional modalities. Results were compared with final diagnosis and expressed as sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy.ResultsForty-one patients were included. Thirty-one were positive for malignancy and 10 were negative. Fifteen were metastatic. Of 31, 18 were CC and 6 were HCC. For overall diagnosis of the primary disease, FAPI PET/CT performed exceptionally compared with FDG PET/CT with sensitivity, specificity, and accuracy of 96.77%, 90%, and 95.12%, respectively, versus 51.61%, 100%, and 63.41% for FDG PET/CT. FAPI PET/CT clearly outperformed FDG PET/CT for the evaluation of CC with sensitivity, specificity, and accuracy of 94.4%, 100%, and 95.24%, respectively, whereas for FDG PET/CT sensitivity, specificity, and accuracy were 50%, 100%, and 57.14%, respectively. Diagnostic accuracy of FAPI PET/CT was 61.54% for metastatic HCC compared with 84.62% for FDG PET/CT.ConclusionsOur study highlights the potential role of FAPI-PET/CT in evaluating CC. It also ascertains its usefulness in the cases of mucinous adenocarcinoma. Although it showed a higher lesion detection rate than FDG in primary HCC, its diagnostic performance in the metastatic setting is questionable.

FAPI Uptake in Gallbladder Is It Normal Biodistribution?

“…Here we are presenting 3 patients with GB uptake. FAPI uptakes in GB and hepatobiliary system have been reported in literature review 9–12 . Subsequent hepatobiliary ultrasound and liver function enzymes demonstrated that none of these patients had liver metastasis or other liver or GB diseases.…”

“…FAPI uptakes in GB and hepatobiliary system have been reported in literature review. [9][10][11][12] Subsequent hepatobiliary ultrasound and liver function enzymes demonstrated that none of these patients had liver metastasis or other liver or GB diseases. Case 1 presented a 60-year-old man with stage IV (according to TNM staging) lung adenocarcinoma (GB SUV max of 5.9 and SUV mean of 3.47, on the delayed phase with SUV max of 2.1 and SUV mean of 1.2 on the early ones).…”

Head-to-Head Comparison of FDG and Radiolabeled FAPI PET: A Systematic Review of the Literature

“… Schematic representation of the studies and their advantage in terms of detection rate and/or accuracy. pts: patients; ADV: advantage of FAPI-based tracers over FDG (green: strong advantage; yellow: only moderate advantage or comparable results); STS: soft tissue sarcoma; MM: multiple myeloma; IgG4-RD: IgG4-related [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ]. …”

“…A recent study by Rajaraman et al [30] evaluated the performance of [ 68 Ga]Ga-FAPI-04 PET/CT in a prospective cohort of 41 patients suspected to have HCC or cholangiocarcinoma (CC), subsequently found positive for malignancy (n = 31, of which 15 metastatic) or negative (n = 10) and compared with that of [ 18 F]FDG PET/CT studies. For overall diagnosis of primary disease, [ 68 Ga]Ga-FAPI-04 PET/CT resulted superior to [ 18 F]FDG PET/CT with a sensitivity, specificity, and accuracy of 96.8% vs. 51.6%, 90% vs. 100%, and 95.1% vs. 63.4%, respectively.…”

Superiority of 18F-FAPI-42 PET/CT in the detection of primary tumor and management of appendiceal neoplasm to 18F-FDG PET/CT and CE-CT

“…Radionuclide labelled, fibroblast-activated, protein inhibitors (FAPI), such as 68 Ga-FAPI, have been developed as PET tracers and show superiority to 18 F-FDG in imaging various cancers [ 13 – 15 ], especially in gastric cancer, pancreaticobiliary neoplasms and some rare tumors [ 16 – 18 ], although FAPI uptake can occur in non-oncologic conditions [ 19 , 20 ]. It was found that gastrointestinal tumors, even those containing mucus or signet ring cell carcinoma, had high FAPI uptake and these lesions could be depicted clearly [ 14 , 21 ].…”