Whole-body dual-modality PET/CT and whole-body MRI for tumor staging in oncology.

CONTEXT: Deciding on the appropriate therapy for patients with malignant diseases mandates accurate tumor staging with whole-body coverage. Magnetic resonance imaging (MRI) and a combined modality including positron emission tomography (PET) and computed tomography (CT) provide whole-body tumor staging in a single session.

OBJECTIVE: To determine the staging accuracies of both whole-body PET/CT and whole-body MRI for different malignant diseases.

DESIGN, SETTING, AND PATIENTS: Prospective, blinded, investigator-initiated study of 98 patients (mean age, 58 years; range, 27-94 years) with various oncological diseases who underwent back-to-back whole-body glucose analog [18F]-fluorodeoxyglucose-PET/CT and whole-body MRI for tumor staging. The study was conducted at a university hospital from December 2001 through October 2002 and had a mean follow-up of 273 days (range, 75-515 days). The images were evaluated by 2 different, blinded reader teams. The diagnostic accuracies of the 2 imaging procedures were compared.

MAIN OUTCOME MEASURES: Correct classification of the primary tumor, regional lymph nodes, and distant metastasis (overall TNM stage) using whole-body PET/CT and whole-body MRI. Secondary outcome measures were accurate assessment of T-stage, N-stage, and M-stage by the 2 imaging procedures.

RESULTS: Of 98 patients, the overall TNM stage was correctly determined in 75 with PET/CT (77%; 95% confidence interval [CI], 67%-85%) and in 53 with MRI (54%; 95% CI, 44%-64%) (P<.001). Compared with MRI, PET/CT had a direct impact on patient management in 12 patients. Results from MRI changed the therapy regimen in 2 patients compared with PET/CT. Separate assessment of T-stage (with pathological verification) in 46 patients revealed PET/CT to be accurate in 37 (80%; 95% CI, 66%-91%) and MRI to be accurate in 24 (52%; 95% CI, 37%-67%) (P<.001). Of 98 patients, N-stage was correctly determined in 91 patients with PET/CT (93%; 95% CI, 86%-97%) and in 77 patients with MRI (79%; 95% CI, 69%-86%) (P =.001). Both imaging procedures showed a similar performance in detecting distant metastases.

CONCLUSIONS: The feasibility and diagnostic accuracy of the whole-body staging strategies of PET/CT and MRI are established. Superior performance in overall TNM staging suggests the use of [18F]-fluorodeoxyglucose-PET/CT as a possible first-line modality for whole-body tumor staging.