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Purpose: We aimed to investigate the potential of [68Ga]Ga-FAPI-04 PET/CT as an alternative diagnostic and theranostic tool in well-differentiated NETs refractory to [177Lu]Lu-DOTATATE therapy. Methods: Patients who received at least two cycles of [177Lu]Lu-DOTATATE therapy for metastatic NETs and progressed under treatment were included. All patients had performed [68Ga]Ga-DOTATATE and [68Ga]Ga-FAPI-04 PET/CT within 3 weeks. The number of PET-positive lesions related to NETs and tumor sites was documented. Mann-Whitney U and chi-square tests were used to compare SUVmax levels of tracers and the number of detected metastases. Results: Twelve patients (7 male, 5 female) who met the eligibility criteria were included in the study. Ten patients had grade 1–2 NET of various origins, and two had paraganglioma and pheochromocytoma. One hundred ninety-eight of 230 lesions (86%) were SSTR positive with a median SUVmax of 16.6 (2.2–76.5), and 88 of 230 lesions (38.2%) were [68Ga]Ga-FAPI-04 positive with a median SUVmax of 5.1 (2.3–21). Median SUVmax level and detected number of tumors were significantly higher in [68Ga]Ga-DOTATATE PET/CT (p=<0.001). [68Ga]Ga-FAPI-04 PET/CT was completely (n:2) or almost completely (n:3) negative in 5 (42%) patients. Two (17%) patients had flip-flop SSTR/FAPI uptake in tumors. In four patients (33%), tumor uptake or the number of PET-positive lesions was inferior in [68Ga]Ga-FAPI-04 PET/CT. In only one patient (8%), tumor uptakes were higher in [68Ga]Ga-FAPI-04 PET/CT. Low-dose [177Lu]Lu-FAPI-46 dosimetry was performed on the FAPI-dominant patient; absorbed radiation doses per GBq were 1.26 Gy, 0.36 Gy, 0.32 Gy, and 0.2 Gy for kidneys, liver, spleen, and total body, respectively. The mean absorbed dose per GBq was 0.33 Gy for liver mass and 0.41 Gy for metastatic lymph nodes. Conclusion: Our preliminary results demonstrated that [68Ga]Ga-FAPI-04 PET/CT mainly failed in well-differentiated NETs refractory to [177Lu]Lu-DOTATATE therapy and had a limited role as an alternative diagnostic or theranostic agent. Further investigations with a larger patient population are required to determine the impact of [68Ga]Ga-FAPI-04 PET/CT on NETs. [ABSTRACT FROM AUTHOR]

Purpose: Platelet-rich plasma (PRP) includes growth factors and proteins that accelerate and stimulate bone regeneration and tissue recovery. The aim of this study was to evaluate the effects of PRP on fracture healing in terms of biomechanics and histology. Methods: Seventy female rats were included in this experimental study. They were divided into three groups: Group I (no PRP, n = 30), Group II (PRP added, n = 30) and Group III (control, n = 10). The left femurs of the rats in Groups I and II were osteotomized and fixed by K-wires. Although no additional intervention was performed on Group I rats, PRP was applied to the fracture sites of Group II rats. The remaining ten rats were used as the control group of the biomechanical test (Group III). In the fourth week, nine femurs from Group I and ten femurs from Group II, and in the ninth week, nine femurs from each group were removed, and bone recovery was assessed histologically according to Modified Lane-Sandhu histological scoring criteria. Three-point bending test was applied to femurs for biomechanical evaluation in the ninth week. Results: Histological healing was found to be significantly higher in Group II than in Group I ( p < 0.05). Furthermore, biomechanical test results showed that healing quantity and bone strength were significantly better in Group II than in Group I ( p < 0.05). Conclusion: PRP is a widely studied material in the physiology of fracture healing. The results of this study demonstrated the ameliorative biomechanical effects of PRP on fracture healing, in addition to accelerating the histological union of fractures. In the light of these results, PRP could be a viable alternative to accelerate the healing of fractures, late unions or non-unions. Level of evidence: Prospective comparative study, Level II. [ABSTRACT FROM AUTHOR]