PT - JOURNAL ARTICLE AU - Guanyun Wang AU - Yachao Liu AU - Haodan Dang AU - Yue Wu AU - Mu Lin AU - Shulin Yao AU - Jiahe Tian AU - Baixuan Xu TI - Comparative Diagnostic Value Between <sup>18</sup>F-FDG and <sup>18</sup>F-DCFPyL PET/CT in Recurrent or Metastasis Clear Cell Renal Carcinoma after Nephrectomy DP - 2021 May 01 TA - Journal of Nuclear Medicine PG - 1355--1355 VI - 62 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/62/supplement_1/1355.short 4100 - http://jnm.snmjournals.org/content/62/supplement_1/1355.full SO - J Nucl Med2021 May 01; 62 AB - 1355Objectives: Although the role of 18F-fluoro-2-deoxy-2-d-glucose (18F-FDG) PET/CT (positron emission tomography/computed tomography) in diagnosing renal cell carcinoma (RCC) is conflicting[1]. However, some researches showed the effectiveness of FDG-PET in detecting postoperative recurrence and distant metastasis of renal cell carcinoma[2]. Nowadays, prostate-specific antigen (PSMA) PET/CT has emerged in clinical studies on RCC diagnosis and showed better performance than 18F-FDG PET/CT and conventional imaging[3, 4]. Our previous study found the results that 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine-3-car-bonyl)-amino]-pentyl}-ureido)-pentanedioic acid (18F-DCFPyL) PET/CT was better than 18F-FDG PET/CT in detecting bone metastasis and distinguishing benign and malignant in postoperative recurrence[5]. The purpose of this study was to compare the diagnosis value in 18F-FDG PET/CT and 18F-DCFPyL PET/CT for patients who were suspected with clear cell renal carcinoma (ccRCC) recurrence or metastasis after nephrectomy. Materials and Methods: 23 patients (19 males and 4 females, mean age 58.8±11.0 years old) who were suspected with recurrent or metastasis ccRCC after nephrectomy were enrolled and were performed with 18F-FDG PET/CT and 18F-DCFPyL PET/CT imaging study. The interval between the two inspections should not exceed 10 days. Lesion detectability of 18F-FDG PET/CT and 18F-DCFPyL PET/CT in the same patients were compared.SUV of lesions and metastasis-background ratio (TBR) were measured. Histopathological results and follow-up imaging findings were used as the reference standard. The study was approved by the regional ethics committee. Results: A total of 8 recurrent lesions and 87 metastatic lesions were found. Metastatic lesions were divided into: lymph node metastasis (n=35), bone metastasis (n=25), lung metastasis (n=13) and others (n=14). Among the 35 lymph node metastases, 33 were positive in 18F-DCFPyL PET/CT imaging. The SUVmax were 4.3 ± 2.7 (range 1.8-14.6) and the MBRSUVmax were 9.2 ± 4.6 (range 4.0-24.3); 34 lesions were positive in 18F-FDG PET/CT with SUVmax of 10.6 ± 4.6 (range 1.5-20.3) and MBRSUVmax of 12.6 ± 6.3 (range 1.3-25.4). MBRSUVmax between the two imaging agents showed significant difference (P=0.018, Fig 1). Among the 25 bone metastases, 21 were positively detected by 18F-DCFPyL PET/CT imaging with SUVmax of 6.3±4.2 (range 1.6-14.1) and MBRSUVmax of 9.4±5.6 (range 3.4-20.1); 13 were positive in 18F-FDG PET/CT. SUVmax were 3.0±2.4 (range 1.0-11.9) and MBRSUVmax were 3.0±2.3 (range 0.9-11.9), and MBRSUVmax also were found with significant difference between two imaging agents (P&lt;0.001, Fig 1). Among the 13 lung metastases, 9 were positive in 18F-DCFPyL PET/CT imaging with SUVmax of 2.8±1.7 (0.5-5.8) and MBRSUVmax of 4.8±2.8 (1.0-9.7); 12 were positive in 18F-FDG PET/CT with SUVmax of 3.3±2.7 (0.6-11.0) and MBRSUVmax of 3.3±2.4 (0.6-9.2). MBRSUVmax showed no significant difference between the two imaging agents (P=0.081, Fig 1). Among the 8 suspected recurrent lesions, 4 recurrences and 4 postoperative changes were found. All suspected recurrent lesions were positive in 18F-FDG PET/CT imaging, but 18F-DCFPyL PET/CT could distinguish the recurrent or postoperative lesions. Conclusions: Our findings indicated the potential value of 18F-DCFPyL PET/CT in the morphometabolic detection of RCC metastases, especially for bone metastasis and distinguishing benign and malignant in postoperative recurrence. 18F-FDG PET/CT has more advantages in detecting lymph node metastasis. These results remind us that 18F-FDG and 18F-DCFPyL PET/CT combining may have better performance in the diagnosis of recurrent or metastasis renal cell carcinoma after nephrectomy.