FDG-Avid Keloid on PET/CT Imaging

68 Ga-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 68 Ga-FAPI-04 PET/CT in the assessment of keloids activity.

PATIENTS AND METHODS

Twenty-five patients with keloid were enrolled to conduct 68 Ga-FAPI-04 PET/CT. All patients accepted surgery to remove part of the lesions within 1 week. SUV mean and SUV max 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 68 Ga-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 SUV max of 68 Ga-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 SUV max of 68 Ga-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

68 Ga-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.

Chest Wall Keloids Depicted by 18 F-Piflufolastat PET/CT Imaging

ABSTRACT

Keloids are pathological scars from exuberant fibroproliferative collagen response and excessive extracellular matrix production usually extending beyond the original wound margins. Although keloids are mostly of dermatological concern, they could be incidentally depicted on scintigraphic planar and PET/CT imaging and could mimic other types of skin diseases. The authors present a case of chest wall keloids documented on 18 F-piflufolastat PET/CT during the evaluation of prostate cancer recurrence.

GLUT-1 Enhances Glycolysis, Oxidative Stress, and Fibroblast Proliferation in Keloid

A keloid is a fibroproliferative skin tumor. Proliferating keloid fibroblasts (KFs) demand active metabolic utilization. The contributing roles of glycolysis and glucose metabolism in keloid fibroproliferation remain unclear. This study aims to determine the regulation of glycolysis and glucose metabolism by glucose transporter-1 (GLUT-1), an essential protein to initiate cellular glucose uptake, in keloids and in KFs. Tissues of keloids and healthy skin were explanted for KFs and normal fibroblasts (NFs), respectively. GLUT-1 expression was measured by immunofluorescence, RT-PCR, and immunoblotting. The oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were measured with or without WZB117, a GLUT-1 inhibitor. Reactive oxygen species (ROS) were assayed by MitoSOX immunostaining. The result showed that glycolysis (ECAR) was enhanced in KFs, whereas OCR was not. GLUT-1 expression was selectively increased in KFs. Consistently, GLUT-1 expression was increased in keloid tissue. Treatment with WZB117 abolished the enhanced ECAR, including glycolysis and glycolytic capacity, in KFs. ROS levels were increased in KFs compared to those in NFs. GLUT-1 inhibition suppressed not only the ROS levels but also the cell proliferation in KFs. In summary, the GLUT-1-dependent glycolysis and ROS production mediated fibroblast proliferation in keloids. GLUT1 might be a potential target for metabolic reprogramming to treat keloids.