Magnetization transfer ratio and volumetric analysis of the brain in macrocephalic patients with neurofibromatosis type 1

Abstract

The purpose of the study was to evaluate brain myelination by measuring the magnetization transfer ratio (MTR) and to measure grey (GMV) and white matter volume (WMV) in macrocephalic children with neurofibromatosis type 1 (NF1). Seven NF1 patients (aged 0.65-16.67 years) and seven age- and gender-matched controls were studied. A three-dimensional (3D) gradient echo sequence with and without magnetization transfer (MT) prepulse was used for MTR assessment. Volume measurements of GM and WM were performed by applying segmentation techniques on T2-weighted turbo spin echo images (T2WI). MTR of unidentified bright objects (UBOs) on T2WI in cerebellar white matter (52.8+/-3.3), cerebral peduncles (48.5+/-1.5), hippocampus (52.6+/-1.1), internal capsule (55.7+/-0.3), globus pallidus (52.7+/-3.9), and periventricular white matter (52.6+/-1.2) was lower than in the corresponding areas of controls (64.6+/-2.5, 60.8+/-1.3, 56.4+/-0.9, 64.7+/-1.9, 59.2+/-2.3, 63.6+/-1.7, respectively; p<0.05). MTR of normal-appearing brain tissue in patients was not significantly different than in controls. Surface area (mm(2)) of the corpus callosum (809.1+/-62.8), GMV (cm(3)) (850.7+/-42.9), and white matter volume (WMV) (cm(3)) (785.1+/-85.2) were greater in patients than in controls (652.5+/-52.6 mm(2), 611.2+/-92.1 cm(3), 622.5+/-108.7 cm(3), respectively; p<0.05). To conclude, macrocephaly in NF1 patients is related to increased GMV and WMV and corpus callosum enlargement. MTR of UBOs is lower than that of normal brain tissue.

Characterizing the microstructural basis of “unidentified bright objects” in neurofibromatosis type 1: A combined in vivo multicomponent T2 relaxation and multi-shell diffusion MRI analysis

“…This is in line with previous histological findings (DiPaolo et al, 1995), although differences in myelin water content in living and post-mortem tissue mean that findings from our respective studies cannot be compared equivalently. Margariti et al (2007) hypothesized that decreased magnetization transfer ratio (MTR) in UBOs represented hypomyelination in their study of NF1 patients and healthy controls. However, decreased MTR may also relate to an increase in edema or inflammation, without demyelination (Stanisz et al, 2004; Laule et al, 2007a; Vavasour et al, 2011).…”

Bilateral Posterior Periventricular Nodular Heterotopia: A Recognizable Cortical Malformation with a Spectrum of Associated Brain Abnormalities

“…32 Four patients had callosal hypertrophy with dysplastic splenia, hippocampal dysplasia, and abnormal Sylvian fissures. A hyperplastic corpus callosum is rare and has been reported in neurofibromatosis type 1 33 and Cohen syndrome 34,35 and likely reflects a failure of normal pruning of the commissural fibers. 36,37 We commonly saw posterior ventricular dilation (50%), which we suspect has sometimes been interpreted as hydrocephalus.…”

Clinical and genetic aspects of neurofibromatosis 1

“…People with NF1 have larger brains, on an average, than people without NF1, but gray matter volume is not correlated with intelligence quotient in NF1. 78,79 Most individuals with NF1 have normal intelligence, but learning disabilities occur in 50% to 75%. 80 -85 Visual-spatial performance deficits and attention deficits are most often seen, although a variety of learning problems has been described.…”