Whole-body diffusion-weighted MR imaging with fat suppression by using STIR: clinical utility for detection of primary malignancies in patients initially presented with metastasis.

PURPOSE The purpose of this study was to prospectively evaluate the usefulness of DW MR imaging with fat suppression by using short time inversion recovery (STIR) to detect primary malignancies for patients initially presented with metastasis by direct visual assessment. MATERIALS AND METHODS Twenty-nine consecutive patients presented with metastatic lesions were included in this study and underwent whole-body DW MR imaging for detection of the primary malignancies. Twenty-five healthy volunteers were included in this study as control subjects. Whole-body DW MR imaging was conducted with a multi-stack pulse sequence and two b values of 0 and 600s/mm² and a coverage from head to knees. Three radiologists reviewed the whole-body DW MR images independently to detect the primary malignancies. Receiver operating characteristic (ROC) analysis was used to assess the overall accuracy of this imaging technique in direct visual detection of primary malignancies. Inter-observer agreement was assessed by using kappa analysis. RESULTS For 82.8% (24/29) of the patients, primary malignancies were correctly identified with this whole-body DW MR imaging, and subsequently confirmed by biopsy and/or pathology. While for 17.2% (5/29) of patients, no definite primary malignancy was identified. ROC analysis yielded Az values of 0.907, 0.914, and 0.910 for the three reviewers, respectively. The sensitivity and specificity was 82.8% (24/29) and 100% (25/25) for the three viewers. The inter-observer agreement between each pair of reviewer was 0.935, 0.804, and 0.873, respectively. CONCLUSION For patients originally presented with metastases, whole-body DW MR imaging might have potential utility in detecting primary malignancies.