To explore the diagnostic value of ⁶⁸Ga-fibroblast activation protein inhibitor (FAPI) PET for the restaging of patients with colorectal cancer and its impact on treatment strategy.

Patients with colorectal cancer who underwent ⁶⁸Ga-FAPI PET imaging in the PET Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from June 2020 to June 2021 were retrospectively analyzed. PET images were evaluated by 3 experienced imaging physicians. Biopsy or postoperative pathology, clinical and imaging follow-up results were as the gold standard. The diagnostic value of PET was compared with conventional imaging (CT/MR), and the impact of ⁶⁸Ga-FAPI PET on guiding treatment was evaluated. χ² test and Fisher exact test were used to compare the differences between groups.

A total of 33 patients were included (17 males, 16 females, age (52.8±12.3) years), of which 24 were finally diagnosed as recurrence/metastases/progression. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of ⁶⁸Ga-FAPI PET in detecting recurrence/metastases/progression of colorectal cancer were 93.9%(31/33), 100%(24/24), 7/9, 92.3%(24/26) and 7/7, respectively. Its accuracy, sensitivity and negative predictive value were significantly higher than those of conventional imaging (64.5%(20/31), 56.5%(13/23) and 7/17; χ² values: 8.549 and 10.786, all P<0.05). Compared with the clinical or pathological stage before examination,⁶⁸Ga-FAPI PET led upstaging to stage Ⅳ in 12 patients (50.0%, 12/24). Of the 31 patients who were correctly diagnosed by ⁶⁸Ga-FAPI PET, the treatment regimen of 22 patients (71.0%) was changed because of ⁶⁸Ga-FAPI PET imaging.

⁶⁸Ga-FAPI PET has good diagnostic performance in the restaging of colorectal cancer, which is helpful to further guide clinical treatment strategy.

Colorectal neoplasms; Positron-emission tomography; Tomography, X-ray computed; Magnetic resonance imaging; ⁶⁸Ga-FAPI