Head-to-Head Comparison of [68Ga]Ga-NOTA-RM26 and [18F]FDG PET/CT in Patients with Gastrointestinal Stromal Tumors: A Prospective Study

Gastrointestinal stromal tumors (GISTs) are the most common stromal tumors in the gastrointestinal tract. This study was designed to evaluate a gastrin-releasing peptide receptor antagonist PET tracer, [⁶⁸Ga]Ga-NOTA-RM26, and compare it with [¹⁸F]FDG PET/CT in the assessment of patients with GISTs. Methods: With institutional review board approval and informed consent, 30 patients with suspected or proven GISTs based on abdominal CT or gastroscopy were recruited. All patients underwent [⁶⁸Ga]Ga-NOTA-RM26 and [¹⁸F]FDG PET/CT scans. Pathology and other patient information were collected. Results: No radiopharmaceutical-related adverse events were observed in the patients. In total, 18 lesions in 16 patients were diagnosed as GIST, 3 patients were diagnosed with schwannoma, and 4 patients were diagnosed with leiomyoma. In 18 GISTs, the mean SUV_max of [⁶⁸Ga]Ga-NOTA-RM26 PET was significantly higher than that of [¹⁸F]FDG PET (17.07 ± 19.57 vs. 2.28 ± 1.65; P < 0.01), and [⁶⁸Ga]Ga-NOTA-RM26 PET/CT had a higher tumor detection rate than did [¹⁸F]FDG PET/CT (88.9% vs. 50%; P < 0.01). The uptake of [⁶⁸Ga]Ga-NOTA-RM26 in GISTs was significantly higher than that in 2 other benign tumors (leiomyoma or schwannoma) (17.07 ± 19.57 vs. 4.23 ± 1.77; P = 0.014). With the SUV_max cutoff value of 6.0, the sensitivity of ⁶⁸Ga-NOTA-RM26 PET/CT in diagnosing GISTs is 72% and the specificity is 85.7%. Conclusion: Compared with [¹⁸F]FDG PET/CT, [⁶⁸Ga]Ga-NOTA-RM26 PET/CT is a promising and effective imaging modality for the detection of GISTs.