DOI: 10.1007/s00259-018-3936-0Pages: 1-9

68Ga-PSMA PET/CT in the evaluation of bone metastases in prostate cancer

1. German Cancer Research Center (DKFZ), Clinical Cooperation Unit Nuclear Medicine

2. German Cancer Research Center (DKFZ), Department of Radiology

3. German Cancer Research Center (DKFZ), Division of Radiopharmaceutical Chemistry

4. German Cancer Consortium (DKTK)

5. University Hospital Heidelberg, Department of Urology

6. University Hospital Essen, Department of Urology

7. German Cancer Research Center, Department of Biostatistics

8. University of Heidelberg, Division of Nuclear Medicine

Correspondence to:
Christos Sachpekidis
Email: christos_saxpe@yahoo.gr

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Abstract

Purpose

The aims of this retrospective analysis were to compare 68Ga-PSMA PET findings and low-dose CT findings (120 kV, 30 mA), and to obtain semiquantitative and quantitative 68Ga-PSMA PET data in patients with prostate cancer (PC) bone metastases.

Methods

In total, 152 PET/CT scans from 140 patients were evaluated. Of these patients, 30 had previously untreated primary PC, and 110 had biochemical relapse after treatment of primary PC. All patients underwent dynamic PET/CT scanning of the pelvis and lower abdomen as well as whole-body PET/CT with 68Ga-PSMA-11. The PET/CT scans were analysed qualitatively (visually), semiquantitatively (SUV), and quantitatively based on a two-tissue compartment model and a noncompartmental approach leading to the extraction of the fractal dimension. Differences were considered significant for p values <0.05.

Results

In total, 168 68Ga-PSMA-positive and 113 CT-positive skeletal lesions were detected in 37 patients (8 with primary PC, 29 with biochemical recurrence). Of these 168 lesions, 103 were both 68Ga-PSMA PET-positive and CT-positive, 65 were only 68Ga-PSMA-positive, and 10 were only CT-positive. The Yang test showed that there were significantly more 68Ga-PSMA PET-positive lesions than CT-positive lesions. Association analysis showed that PSA plasma levels were significantly correlated with several 68Ga-PSMA-11-associated parameters in bone metastases, including the degree of tracer uptake (SUVaverage and SUVmax), its transport rate from plasma to the interstitial/intracellular compartment (K1), its rate of binding to the PSMA receptor and its internalization (k3), its influx rate (Ki), and its distribution heterogeneity.

Conclusion

68Ga-PSMA PET/CT is a useful diagnostic tool in the detection of bone metastases in PC. 68Ga-PSMA PET visualizes more bone metastases than low-dose CT. PSA plasma levels are significantly correlated with several 68Ga-PSMA PET parameters.

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  • Accepted: Jan 2, 2018
  • Online: Jan 23, 2018

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