Purpose: To study solitary metastatic lesions of the brain with routine spin-echo (SE) and magnetization transfer (MT) magnetic resonance (MR) imaging.
Materials and methods: In 15 patients with such lesions, the MT ratio (MTR) was calculated in the center and at the periphery of the metastatic lesion, and distally in adjacent white matter, from the periphery of the lesion radially to the most distant cortex. It also was calculated for mirror-image locations in the opposite hemisphere to provide control values.
Results: MTRs were decreased in and immediately around the site of the metastatic focus. MTRs also were lower than control values far distal to the metastatic focus, even when no abnormality was seen on SE MR images obtained before and those obtained after administration of gadopentetate dimeglumine.
Conclusion: MT enables demonstration of white matter abnormalities in patients with metastatic lesions not seen on SE MR images. These changes can be found in white matter far distal to the lesion and surrounding areas of edema.