Comparison of hybrid (68)Ga-PSMA PET/MRI and (68)Ga-PSMA PET/CT in the evaluation of lymph node and bone metastases of prostate cancer.

To evaluate the reproducibility of the combination of hybrid PET/MRI and the (68)Ga-PSMA-11 tracer in depicting lymph node (LN) and bone metastases of prostate cancer (PC) in comparison with that of PET/CT.

A retrospective analysis of 26 patients who were subjected to (68)Ga-PSMA PET/CTlow-dose (1 h after injection) followed by PET/MRI (3 h after injection) was performed. MRI sequences included T1-w native, T1-w contrast-enhanced, T2-w fat-saturated and diffusion-weighted sequences (DWIb800). Discordant PET-positive and morphological findings were evaluated. Standardized uptake values (SUV) of PET-positive LNs and bone lesions were quantified and their morphological size and conspicuity determined.

Comparing the PET components, the proportion of discordant PSMA-positive suspicious findings was very low (98. 5 % of 64 LNs concordant, 100 % of 28 bone lesions concordant). Two PET-positive bone metastases could not be confirmed morphologically using CTlow-dose, but could be confirmed using MRI. In 12 of 20 patients, 47 PET-positive LNs (71. 9 %) were smaller than 1 cm in short axis diameter. There were significant linear correlations between PET/MRI SUVs and PET/CT SUVs in the 64 LN metastases (p < 0. 0001) and in the 28 osseous metastases (p < 0. 0001) for SUVmean and SUVmax, respectively. The LN SUVs were significantly higher on PET/MRI than on PET/CT (p SUVmax < 0. 0001; p SUVmean < 0. 0001) but there was no significant difference between the bone lesion SUVs (p SUVmax = 0. 495; p SUVmean = 0. 381). Visibility of LNs was significantly higher on MRI using the T1-w contrast-enhanced fat-saturated sequence (p = 0. 013), the T2-w fat-saturated sequence (p < 0. 0001) and the DWI sequence (p < 0. 0001) compared with CTlow-dose. For bone lesions, only the overall conspicuity was higher on MRI compared with CTlow-dose (p < 0. 006).

Nodal and osseous metastases of PC are accurately and reliably depicted by hybrid PET/MRI using (68)Ga-PSMA-11 with very low discordance compared with PET/CT including PET-positive LNs of normal size. The correlation between PET/MRI SUVs and PET/CT SUVs was linear in LN and bone metastases but was significantly lower in control (non-metastatic) tissue.

European journal of nuclear medicine and molecular imaging. 2015 Oct 28 [Epub ahead of print]

Martin T Freitag, Jan P Radtke, Boris A Hadaschik, A Kopp-Schneider, Matthias Eder, Klaus Kopka, Uwe Haberkorn, Matthias Roethke, Heinz-Peter Schlemmer, Ali Afshar-Oromieh

Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120, Heidelberg, Germany. Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120, Heidelberg, Germany. , Department of Urology, University Hospital Heidelberg, Heidelberg, Germany. , Department of Bioinformatics and Statistics, German Cancer Research Center, Heidelberg, Germany. , Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany. , Division of Radiopharmaceutical Chemistry, German Cancer Research Center, Heidelberg, Germany. , Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany. , Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120, Heidelberg, Germany. , Department of Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120, Heidelberg, Germany. , Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.

PubMed

E-Newsletters

Newsletter subscription

Free Daily and Weekly newsletters offered by content of interest

The fields of GU Oncology and Urology are rapidly advancing. Sign up today for articles, videos, conference highlights and abstracts from peer-review publications by disease and condition delivered to your inbox and read on the go.

Subscribe