Objective: The purpose of this study was to evaluate the sensitivities and specificities of four single-slab 3D MRI sequences in the detection of cranial metastases: double inversion recovery (IR), T2 FLAIR, contrast-enhanced T2 FLAIR, and contrast-enhanced IR-prepared fast spoiled gradient-echo (FSPGR) sequences.
Subjects and methods: Eighty-four patients underwent double IR and T2 FLAIR imaging using 3-T MRI. Then, 49 of 84 patients were randomly selected to undergo contrast-enhanced IR-prepared FSPGR before contrast-enhanced T2 FLAIR, and the other 35 patients underwent contrast-enhanced T2 FLAIR before contrast-enhanced IR-prepared FSPGR. Two experienced neuroradiologists reviewed the images by consensus on a workstation. Metastases were scored a negative, equivocal, or positive. For each metastasis, we recorded the anatomic area and size, and checked whether edema was present.
Results: A total of 210 cranial metastases in 56 of 84 patients were revealed. The sensitivities of double IR, T2 FLAIR, contrast-enhanced IR-prepared FSPGR, and contrast-enhanced T2 FLAIR sequences were 66.2%, 56.7%, 80.5%, and 99%, respectively. The specificities were 68.3%, 73%, 75.7%, and 82.4%. The areas under the receiver operating characteristic curve were 0.763, 0.709, 0.865, and 0.993. Contrast-enhanced T2 FLAIR imaging was found to have the highest sensitivity especially for detecting lesions in meninges (98.2%; p<0.0001) and gray matter (GM) (100%; p<0.0001). The double IR sequence was superior to the T2 FLAIR sequence for imaging metastases located in ependyma (81.8% vs 36.4%) and GM (66.7% vs 48.1%). Delayed enhancement did not affect the sensitivities of the contrast-enhanced T2 FLAIR and contrast-enhanced IR-prepared FSPGR sequences.
Conclusion: Contrast-enhanced T2 FLAIR is the most sensitive sequence of the four MR sequences evaluated for the detection of cranial metastases despite its delay time after contrast enhancement.