Abstract Background Accurate delineation of brain metastases is essential for the successful of stereotactic radiosurgery (SRS). This study aimed to compare the morphological and volumetric characteristics of brain metastases using post-contrast 3D T1 gradient-recalled echo (GRE) and 3D T1 black blood turbo-spin-echo (TSE) sequences. The hypothesis was that gross tumour volumes (GTV) and planning target volumes (PTV) would be larger on black blood sequences. Methods A retrospective review was conducted on 74 adult patients with untreated brain metastases who underwent MRI during a 12-month period. Post-contrast 3D T1 GRE and black blood TSE sequences were acquired using a 1.5 T MRI. A total of 167 brain metastases were delineated separately by a neuroradiologist and a radiation oncologist, who then determined the consensus GTV and PTV (2 mm). The volumes were then statistically compared using Wilcoxon matched-pairs tests. Results The inter-observer agreement (DICE index) was higher for black blood sequences (0.84) than for GRE sequences (0.76). The mean GTV increased significantly from 1.84 cc on GRE sequences to 2.16 cc on black blood sequences (a 29.8% increase, p 0.001). Similarly, the mean PTV increased from 3.30 cc to 3.77 cc (a 32.5% increase; p 0.001). Black blood sequences depicted larger volumes in 80% of metastases, showing superior visualisation of lesion margins and reduced artifacts (p 0.001). Conclusion Post-contrast black blood sequences produce a significantly larger GTV and PTV than GRE, thereby improving target delineation for SRS. These findings suggest that black blood MRI should be incorporated into routine planning to optimise treatment accuracy.
Zhou et al. (Mon,) studied this question.
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