A magnetic resonance imaging (MRI) study of patients with multiple sclerosis suggests that at ultrahigh-field strength, T1-weighted magnetization-prepared rapid acquisition and multiple gradient echoes (MPRAGE) is highly sensitive for detecting MS plaques within the white and gray brain parenchyma (matter), according to a report published Online First by Archives of Neurology, one of the JAMA/Archives journals.
In current clinical practice, T2-weighted MRI is commonly used to quantify the accumulated MS lesion load in the brain, whereas T1-weighted sequences are used to differentiate, among other things, irreversible brain tissue damage commonly called “black holes.” Black holes are associated with clinical worsening and cerebral atrophy. On spin-echo T1-weighted images, a proportion of T2 hyperintense lesions (black holes) appears hypointense to the surrounding normal-appearing white matter for a long time, the researchers note in study background.
Tim Sinnecker, of the NeuroCure Clinical Research Center , Charite University Medicine, Berlin , and colleagues enrolled 20 patients with relapsing-remitting MS and 14 healthy controls to undergo 7-T brain MRI. A subgroup of 18 patients with MS also underwent 1.5-T brain MRI.
“Against the background of the unresolved dispute over the clinical significance of black holes, and the increasing appreciation of gray matter pathology in MS, we investigated whether the visibility of T1 and T2 lesions in both gray and white matter would be influenced by the improved signal-to-noise ratio at 7 T,” the authors note. “In particular, we hypothesized that the application of MPRAGE would facilitate the detection of hypointense lesions in comparison with conventional MRI.”
The 7-T MPRAGE sequences detected a total number of 728 lesions, depicting more lesions than 7-T FLASH (fast low-angle shot) and almost twice as much as 1.5-T MPRAGE, study results indicate. Each of the 217 T1 hypointense lesions detected by the 7-T MPRAGE sequences in the longitudinal subgroup persisted without major change in formation or size for at least one year and could thus be classified as a black hole, they explain in their results.
“To our knowledge, the present study is the first to demonstrate that, at ultrahigh-field strength, every T2 hyperintense lesion detected on T2-weighted FLASH sequences directly corresponds to a T1 hypointense lesion on a MPRAGE sequence,” they conclude.
(Arch Neurol. Published online Feb. 20, 2012. doi:10.1001/archneurol.2011.2450.