68Ga-FAPI-04 PET/CT in Assessment of Fibroblast Activation in Keloids: A Prospective Pilot Study

Purpose Keloids are benign fibroproliferative disorders characterized by the massive proliferation of fibroblasts. Fibroblast activation plays a key role in the invasive growth of keloids. Therefore, a prospective pilot study was conducted to explore the value of Ga-68-FAPI-04 PET/CT in the assessment of keloids activity.Patients and Methods Twenty-five patients with keloid were enrolled to conduct Ga-68-FAPI-04 PET/CT. All patients accepted surgery to remove part of the lesions within 1 week. SUVmean and SUVmax were measured for semiquantitative analysis and compared with the Vancouver Scar Scale, Laser Speckle Contrast Imaging, pathology, and immunohistochemical stains.Results A total of 123 lesions were detected in 25 patients, most of which were distributed in the anterior chest wall. The Ga-68-FAPI-04 uptake was significantly different at different sites (P < 0.0001). There was uptake heterogeneity within the keloid lesions, and a significant difference was found between the edge and center of some large lesions. The SUVmax of Ga-68-FAPI-04 showed significantly correlation with the Vancouver Scar Scale (r = 0.565, P < 0.0001) moderately and the Laser Speckle Contrast Imaging parameters mildly. The SUVmax of Ga-68-FAPI-04 had a moderate correlation with FAPI expression (r = 0.520, P = 0.022). Moreover, collagen, fibroblast activator protein, and Ki-67 expression were found higher at the edges of keloid tissue than in the center.Conclusions Ga-68-FAPI-04 PET/CT can reflect the distribution characteristics of activated fibroblasts in keloid tissue and may provide a novel method for keloid evaluation for further fibroblast-related therapies.