Initial experience of 68Ga-PSMA PET/CT imaging in evaluation of biochemical recurrence in prostate cancer patients. — ASN Events
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  3. Initial experience of 68Ga-PSMA PET/CT imaging in evaluation of biochemical recurrence in prostate cancer patients.

Initial experience of 68Ga-PSMA PET/CT imaging in evaluation of biochemical recurrence in prostate cancer patients. (#78)

Aravintho Natarajan 1 , Archi Agrawal 1 , Ganesh Bakshi 2 , Gagan Prakash 2 , Umesh Mahantshetty 3 , Vedang Murthy 3 , Amit Joshi 4 , Nilendu Purandare 1 , Santosh Menon 5 , Kumar Prabhash 4 , Sneha Shah 1 , Venkatesh Rangarajan 1
  1. Department of nuclear medicine and molecular imaging, Tata Memorial Hospital, Mumbai, Maharashtra, India
  2. Department of Surgical Oncology, Tata Memorial Hospital , Mumbai, Maharashtra , India
  3. Department of Radiotherapy, Tata Memorial Hospital , Mumbai , Maharashtra , India
  4. Deparment of Medical oncology, Tata Memorial Hospital , Mumbai , Maharashtra , India
  5. Department of Pathology, Tata Memorial Hospital , Mumbai , Maharashtra , India

Introduction:

68Ga-PSMA (Glu-NH-CO-NH-Lys-(Ahx)-[68Ga(HBED-CC]) is a novel PSMA-ligand used for prostate cancer imaging. The aim of the study was to investigate the performance of 68Ga-PSMA PET/CT in patients with biochemical recurrence following definitive treatment.

Materials and methods:

Scans of 64 consecutive patients were analysed. 28 patients received external beam radiotherapy, 14 underwent radical prostatectomy, 4 patients were treated with salvage radiotherapy and 18 patients were on hormonal treatment. All patients underwent contrast-enhanced PET/CT after injection of 2 mci 68Ga-PSMA-ligand.  Detection rates were correlated with serum PSA levels. Detection rate for nodal metastases was compared with CT scan. Diagnostic accuracy was calculated by using either biopsy or follow up imaging or clinical follow up with serum PSA. 

Results:

48 (72.8%) patients had abnormal finding on PSMA PET/CT. The median serum PSA level of the population was 6 ng/ml (range 0.21-123 ng/ml). Statistically significant difference was noted between the median PSA level of the abnormal scans (7.3ng/ml) and normal scans (2.4 ng/ml) (p value-0.001 by Mann-Whitney U test). PSMA PET/CT revealed nodal metastases in 29 (45.3%) patients while CT scan detected pathological nodes only in 14 (21.8%) patients. Overall PSMA PET/CT revealed more number of nodes than CT (65 versus 25). PSMA PET/CT showed relapse in prostatic bed in 20 (31.2%) patients, skeletal metastases in 15(23.4%) and other visceral metastases in 3(4.6%) patients. The sensitivity and specificity of 68Ga-PSMA PET/CT was 73.3 and 100% respectively. 

Conclusion:

PSMA PET/CT has high sensitivity and specificity for localising the site of recurrence in patients with biochemical failure and is superior to CT scan particularly in detection of nodal disease.