Matthias Johannes Eiber MD, Abstract Co-Author: Nothing to Disclose

Bernd Krause, Abstract Co-Author: Nothing to Disclose

Tobias Maurer, Abstract Co-Author: Nothing to Disclose

Markus Schwaiger MD, Abstract Co-Author: Research grant, Siemens AG

Ambros Johannes Beer MD, Presenter: Research Funding, Pieris AG, Munich Germany

11C-Choline PET/CT is a commonly used diagnostic imaging tool in patients with prostate cancer. Diffusion weighted MR-imaging (DWI) is a promising new technique for tissue characterization. We compared both methods concerning characterization of lymph nodes metastases in prostate cancer patients.

14 patients with prostate cancer underwent DWI-MRI at 1.5T (b-values of 50, 300 and 600 s/mm2) and 11C-Choline PET/CT. All lymph nodes larger than 5mm were analyzed. ADC-values and standardized uptake values (SUVs) were compared by using linear-regression analysis. Diagnostic performance was assessed by receiver operator characteristic (ROC) analysis using histological and/or clinical follow-up as standard of reference.

ADC-value and SUV showed a moderate but highly significant inverse correlation (r=-0.5144, p<0.0001). Highly significant differences (p<0.0001) could be found between benign and malignant lymph nodes for both mean ADC-value (1.60±0.24 vs. 1.09±0.23 x 10-3 mm2/s) and SUV (1.82±0.57 vs. 4.68±03.12). ROC-analysis demonstrated that diagnostic accuracy at the optimum cutoff-value for both ADC-value (80.0%) and SUV (85.4%) was superior to size (67.3%). A combinatorial analysis of DWI and SUV further increased diagnostic accuracy (87.3%), which however did not reach statistical significance.

DWI is a suitable tool for detection and characterization of pelvic lymph nodes metastases in prostate cancer patients with a diagnostic accuracy comparable to 11C-Choline-PET/CT. The correlation between low ADCs and high SUVs reflects the fact that both tools are indicative of malignancy. Our data suggest that a combinatorial analysis of ADC and SUV increases diagnostic accuracy, thus making this approach especially attractive for potential use in combined PET-MRI scanners in the future.

Our data suggest that by combining 11C-Choline PET/CT and DWI and rating only positive lesions in both modalities as malignant, a higher diagnostic accuracy might be obtained.

Eiber, M, Krause, B, Maurer, T, Schwaiger, M, Beer, A, PET-MRI Correlation of Diffusion-weighted MR Imaging and 11C-Choline PET/CT for Characterization of Pelvic Lymph Node Metastases in Patients with Prostate Cancer.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8014092.html