Prospective Study Comparing [ 99m Tc]Tc-DP-FAPI Quantitative SPECT/CT with [ 68 Ga]Ga-FAPI-04 PET/CT in Patients with Gastrointestinal Tumors.

Over the past decade, [ 68 Ga]Ga-FAPI-04 positron emission tomography (PET)/CT imaging has been widely used for the treatment of various tumors. However, the application of 99m TC-labeled fibroblast activation protein inhibitors in tumors has been less studied. Our team previously demonstrated the safe biological distribution of [ 99m Tc]Tc-DP-FAPI in the human body. Based on this, this study reports the accuracy of [ 99m Tc]Tc-DP-FAPI in the imaging diagnosis of gastrointestinal tumors and compares it with that of [ 68 Ga]Ga-FAPI-04 to evaluate the differences. A total of 24 patients with clinically diagnosed gastrointestinal tumors were prospectively included. All patients received [ 99m Tc]Tc-DP-FAPI quantitative SPECT/CT imaging on the first day and [ 68 Ga]Ga-FAPI-04 PET/CT imaging on the second day. And the effectiveness of the two imaging probes in detecting suspicious lesions was analyzed and compared. The primary tumors of all 24 patients were well detected by two imaging probes, and the sensitivity of [ 99m Tc]Tc-DP-FAPI and [ 68 Ga]Ga-FAPI-04 to the primary lesions was 100%. [ 99m Tc]Tc-DP-FAPI examined 21 lymph nodes with a sensitivity and specificity of 32.8% and 10.9%, and [ 68 Ga]Ga-FAPI-04 detected 57 lymph nodes with a sensitivity and specificity of 89.1% and 67.2%, respectively. Three distant metastases were detected by [ 99m Tc]Tc-DP-FAPI and nine metastases by [ 68 Ga]Ga-FAPI-04. The study showed that [ 99m Tc]Tc-DP-FAPI is highly sensitive to detecting primary lesions of gastrointestinal tumors. Compared with [ 68 Ga]Ga-FAPI-04, [ 99m Tc]Tc-DP-FAPI has the same sensitivity in detecting primary tumors but has certain limitations in detecting metastases. [ 99m Tc]Tc-DP-FAPI is of great value for preliminary screening of tumor lesions and early diagnosis of disease in patients who are suspected of having gastrointestinal tumors.