title: Can Initial (18)F-FDG PET-CT Imaging Give Information on Metastasis in Patients with Primary Renal Cell Carcinoma?
abstract: OBJECTIVE
  The aim of this study was to investigate the relationship between the maximum standardized uptake values (SUVmax) of primary renal cancers with and without metastatic lesions, if any. We also studied the relationship between the size of primary renal cancers and their SUVmax, and tried to find a clinical value of (18)F-FDG PET-CT for the initial evaluation of renal cell carcinoma (RCC).
  
  
  METHODS
  The cases of 23 patients, 16 men and 7 women, who underwent PET-CT examination before operation were retrospectively reviewed. We measured the SUVmax of the primary renal cancers and those of any existing metastatic lesions, and the size of the primary renal cancers. We compared the SUVmax of primary RCCs with metastases and those without metastases, SUVmax of primary RCC and those of metastases, and studied the correlation between the size and SUVmax of primary RCCs.
  
  
  RESULTS
  The SUVmax of primary RCC of the 16 patients without metastasis ranged from 1.1 to 5.6 with a median value of 2.6. Those of the patients with metastasis ranged from 2.9 to 7.6 with a median of 5.0. The size of the all 23 primary renal cancers ranged from 1.7 cm to 13.5 cm, with a median of 4.5 cm, and their SUVmax ranged from 1.1 to 7.6, with a median of 2.9. There was a statistically significant difference between the SUVmax of the primary RCC with metastasis (5.3 ± 1.7) and those without metastasis (2.9 ± 1.0). There was a moderate positive correlation between the sizes and SUVmax of all 23 primary RCCs. However, there was no statistically significant correlation between the sizes and SUVmax of primary RCCs with metastatic lesions and the same for RCCs without metastasis. The cutoff value of SUVmax for predicting extra-renal lesion was 4.4 and that for size was 5.8 cm according to the receiver operating characteristic curves.
  
  
  CONCLUSIONS
  Those who have primary RCC with high SUVmax are suggested to have a likelihood of metastasis. Also, there was a moderate trend of increasing value of SUVmax of primary RCC as their size increases. Physicians should beware of missing extra-renal lesions elsewhere.
authors.affiliation: Department of Nuclear Medicine, Gachon University Gil Hospital, Incheon, Republic of Korea.
authors.forename: Haejun
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Nuclear Medicine, Gachon University Gil Hospital, Incheon, Republic of Korea.
authors.forename: Kyung Hoon
authors.initials: KH
authors.lastname: Hwang
authors.affiliation: Department of Nuclear Medicine, Gachon University Gil Hospital, Incheon, Republic of Korea.
authors.forename: Seog Gyun
authors.initials: SG
authors.lastname: Kim
authors.affiliation: Department of Nuclear Medicine, Gachon University Gil Hospital, Incheon, Republic of Korea.
authors.forename: Geon
authors.initials: G
authors.lastname: Koh
authors.affiliation: Department of Nuclear Medicine, Gachon University Gil Hospital, Incheon, Republic of Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Kim
keywords: 18F-FDG; Initial staging; Metastasis; PET-CT; Renal cell carcinoma; SUV