Head-to-Head Comparison Between [ 68 Ga]Ga-DOTA.SA.FAPi And [ 18 F]F-FDG PET/CT Imaging in Patients With Sarcoma.

Objective: This study aimed to compare the diagnostic efficacy of [ 68 Ga]Ga-DOTA.SA.FAPi and [ 18 F]F-FDG PET/CT for detecting primary and metastatic lesions in sarcoma patients.

Methods: The analysis included both patient-based and lesion-based comparisons of PET/CT scans in individuals with histologically confirmed sarcoma.

Results: A total of 23 sarcoma patients (mean age 43.0 ± 16.5 years; range: 21-76 years) underwent both [ 18 F]F-FDG and [ 68 Ga]Ga-DOTA.SA.FAPi PET/CT scans. Histological distribution included 30% synovial sarcoma, 13% liposarcoma, and 21.7% leiomyosarcoma, with 70% of patients presenting with distant metastases. Detection rates for primary tumors were similar between [ 68 Ga]Ga-DOTA.SA.FAPi and [ 18 F]F-FDG PET/CT (85.7% vs 100%, P  = 0.149). Lymph node detection rates were also comparable (80% vs 100%, P  = 0.146). Lesion-based analysis revealed that [ 68 Ga]Ga-DOTA.SA.FAPi detected 220 lesions (83% efficiency) compared with 249 lesions (94% efficiency) for [ 18 F]F-FDG ( P  < 0.0001). Notably, [ 68 Ga]Ga-DOTA.SA.FAPi demonstrated superior detection of liver (54 vs 38 lesions, P  < 0.0001) and bone metastases (125 vs 102 lesions, P  < 0.0001).

Conclusions: Our study shows that although [ 18 F]F-FDG PET/CT offers superior overall lesion detection efficiency, [ 68 Ga]Ga-DOTA.SA.FAPi PET/CT excels in identifying specific metastatic sites, particularly in bone and liver. These findings highlight the complementary roles of both imaging modalities in sarcoma evaluation.