Diagnostic Confidence of Contrast-Enhanced T1-Weighted MRI for the Detection of Brain Metastases: 3D FSE-vs. 3D GRE-Based Sequences

BACKGROUND AND PURPOSE: This retrospective study evaluated the utility of contrast-enhanced (CE) T1-weighted 3D fast spinecho-based SPACE sequences for brain metastasis detection on 3T MRI compared to gradient recalled-echo-based 3D fast low-angle shot (FLASH) sequence.

MATERIALS AND METHODS: We identified all patients at a single institution who underwent SPACE and 3D FLASH sequences as part of a practice quality improvement project. Their medical records were retrospectively reviewed. Five certified neuroradiologists reviewed the images, with at least 2 weeks separation between scoring sequences for the same patient. The following parameters were evaluated: number of metastatic lesions, number of indeterminate lesions, lesion margin, contrast-to-noise ratio (CNR), extent of image artifacts, and overall image quality. CNR was also quantified for solidly enhancing lesions > 1 cm.

RESULTS: We identified 220 patients who underwent SPACE and 3D FLASH sequences (the order of the sequences was equally distributed). Of these, 79 had brain metastases on imaging, and 7 were excluded; thus, 72 patients were included in the study. Twenty patients were scored by 2 radiologists. Out of the 92 evaluations, SPACE detected more lesions than did 3D FLASH in 35, while 3D FLASH detected more lesions in 10. More indeterminate lesions were seen on 3D FLASH (27) than on SPACE (9). For lesion margin, CNR, and overall image quality on a Likert scale, SPACE performed significantly better than did 3D FLASH, with less image artifacts (P < 0.00001). Higher quantitative CNRs were found on SPACE than on 3D FLASH images, although this result was not statistically significant (median = 22.9 vs. 15.5, respectively, P = 0.134). There was a high inter-reader lesion detection concordance with Krippendorf’s alpha ordinals at 0.962 for SPACE, 0.870 for 3D FLASH, and 0.918 for the two sequences combined.

CONCLUSIONS: Compared with 3D FLASH, the SPACE sequence detected more metastatic lesions and was rated higher for image quality, lesion margin, and CNR, with fewer artifacts. Importantly, the SPACE sequence resulted in increased reader confidence, with fewer indeterminate lesions detected.

ABBREVIATIONS: FLASH = fast low-angle shot; FSE = fast spin-echo; GRE = gradient-recalled echo; MP-RAGE = magnetization-prepared rapid gradient echo; SPACE = Sampling Perfection with Application-optimized Contrasts using different flip angle Evolution; VIBE = volumetric interpolated breath-hold examination.