Detecting radiation esophagitis using ¹⁸F-FAPI-04 PET/CT in patients with LA-ESCC treated with concurrent...

This prospective study examined whether ¹⁸F-AlF-NOTA-fibroblast activation protein inhibitor (FAPI)-04 (denoted as ¹⁸F-FAPI-04) positron emission tomography/computed tomography (PET/CT) can detect the development and severity of radiation esophagitis (RE) in patients with locally advanced esophageal squamous cell carcinoma (LA-ESCC) treated with concurrent chemoradiotherapy.

From June 2021 to March 2022, images were collected from LA-ESCC patients who underwent ¹⁸F-FAPI-04 PET/CT examinations before and during radiotherapy. The development of RE was evaluated weekly according to Radiation Therapy Oncology Group criterion. The target-to-background ratio in blood (TBR_blood) was analyzed at each time point and correlated with the onset and severity of RE. Factors that predicted RE were identified by multivariate logistic analyses.

Thirty patients were evaluated. Significantly higher TBR_blood (during radiotherapy, P = 0.003) and change in TBR_blood compared with pre-RT (ΔTBR_blood, P = 0.002) were observed in patients with RE than patients without RE. Those with grade 3 RE had a significantly higher TBR_blood (during radiotherapy, P = 0.003) and ΔTBR_blood (P = 0.003) compared with those with RE < grade 3. On multivariate analysis, ΔTBR_blood was identified as a significant detection of any grade RE (P = 0.021) and grade 3 RE (P = 0.038).

The ΔTBR_blood on ¹⁸F-FAPI-04 PET/CT may be effective at identifying patients with RE, especially grade 3 RE.