Abstract
1406
Objectives Conventional planar Tc99m-MDP skeletal scintigraphy (PBSS) is most common modality used to detect skeletal metastases in patients with prostate carcinoma. However recent studies have shown superiority of F-18 PET/CT over PBSS in detecting bone metastases. This prospective study was conducted to evaluate the utility of F-18 PET/CT in detecting skeletal metastases in patients with high PSA levels and negative PBSS.
Methods All patients with prostate carcinoma who underwent PBSS during the period of July 2010 - March 2011 were screened for inclusion into this study. All the PBSS scans were scored with a 5 point scale of 1-5 (score of 1,2- benign; 3- equivocal; 4, 5- as definitely malignant). Patients with scores of 1,2 and 3 on PBSS and with PSA levels greater than 20ng/ml subsequently underwent F-18 PET/CT. F-18 PET/CT findings were also scored in similar way blinded to PBSS findings. Final diagnosis was established by clinical or imaging follow up of 6 month and correlative imaging.
Results Out of 76 patients who underwent PBSS, 16 patients met with inclusion criteria and underwent F-18 PET/CT. On PBSS, 15 of these 16 patients fell in benign category and 1 in equivocal category according to above described scale. PSA levels ranged from 20-626 ng/ml with a mean of 134 ng/ml. F-18 PET/CT suggested bone metastases in 6/16 patients with scores of 3 in 2 patients and scores of 4 and above in 4 patients, all confirmed to have metastatic disease (1 on MRI and 5 on follow up). Over all F-18 PET/CT detected skeletal metastases in 6/16 (37.5%) patients with negative PBSS.
Conclusions Our results suggest that F-18 PET/CT is more sensitive than PBSS and increases diagnostic confidence in detecting skeletal metastases in patients with prostate carcinoma with high PSA levels. It detects skeletal metastases in more than one third patients with negative PBSS but high PSA levels