Benedikt Michael Schaarschmidt MD, Presenter: Nothing to Disclose

Felix Nensa MD, Abstract Co-Author: Nothing to Disclose

Christian Buchbender, Abstract Co-Author: Nothing to Disclose

Verena Ruhlmann, Abstract Co-Author: Nothing to Disclose

Gerald Antoch MD, Abstract Co-Author: Speaker, Siemens Medical AG Speaker, Bayer AG Speaker, BTG International Ltd

Philipp Heusch MD, Abstract Co-Author: Nothing to Disclose

Integrated PET/MRI promises increased diagnostic accuracy in oncological patients concerning staging of the primary tumor as well as nodal and distant metastasis (TNM) staging based on a combination of excellent soft tissue contrast with functional MRI and PET. The aim of this study was to compare a dedicated 18F-FDG-PET/MRI protocol to 18F-FDG-PET/CT for TNM-staging in oncological patients.

73 patients (mean age 59y) with histologically confirmed, solid malignancy were included (malignant melanoma: n=33, bronchial cancer: n=25, breast cancer: n=4, other n=11). All patients underwent PET/CT (Siemens mCT™) 60 min after injection of a mean dose of 295MBq and whole body PET/MRI (mean delay 81 min following PET/CT, Siemens Biograph mMR™). TNM-staging was performed for both examinations according to the 7th Edition of the AJCC cancer staging manual by two readers. Assessment of the primary tumor, of nodal and distant metastases with FDG-PET/CT and FDG-PET/MRI was based on qualitative and quantitative analysis. Histopathology as well as radiological and clinical follow-up served as reference standard (available for 27 patients in T-, for 67 in N- and for 42 in M-stage). McNemar's test was used to test for differences in diagnostic accuracy between both imaging procedures.

PET/CT and PET/MRI agreed in T-staging in 25/27 of patients (93%). Compared to the reference standard, the primary tumor was correctly staged by PET/CT in 22/27 patients (82%) and by PET/MRI in 20/27 patients (74%), respectively (p>0.05). Regional lymph node staging was performed correctly in 55 (82%) and 56 out of 67 (84%) patients with PET/CT and PET/MRI, respectively (p>0.05). PET/MRI accurately differentiated between M0 and M1 disease in 35 out of 42 (83%) patients. Compared with the reference standard, PET/MRI overstaged the M-stage in 3 patients and understaged it in 4 patients. With PET/CT, the M-stage was correctly classified in 32 out of 42 (76%) patients. Concerning diagnostic accuracy, there was no statistically significant difference between PET/MRI and PET/CT (p>0.05).

For TNM-staging, no significant differences were observed between PET/CT and PET/MRI regarding their diagnostic accuracy.

PET/CT and PET/MRI seems to have similar staging accuracies for solid malignant tumors. This is an important finding when considering the future diagnostic work up of oncological patients.

Schaarschmidt, B, Nensa, F, Buchbender, C, Ruhlmann, V, Antoch, G, Heusch, P, Diagnostic Accuracy of Whole Body PET/MRI and Whole Body PET/CT for TNM Staging in Oncology.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007116.html