Quantitative Differentiation Between Healthy and Disordered Brain Matter in Patients with Neurofibromatosis Type I Using Diffusion Tensor Imaging

• Published in: American journal of neuroradiology : AJNR Vol. 29; no. 4; pp. 816 - 822
• Main Authors: van Engelen, S.J.P.M, Krab, L.C, Moll, H.A, de Goede-Bolder, A, Pluijm, S.M.F, Catsman-Berrevoets, C.E, Elgersma, Y, Lequin, M.H
• Format: Journal Article
• Language: English
• Published: Oak Brook, IL Am Soc Neuroradiology 01-04-2008; American Society of Neuroradiology
• Subjects: Adolescent; Biological and medical sciences; Brain - pathology; Child; Diffusion Magnetic Resonance Imaging; Female; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Nervous system; Nervous system (semeiology, syndromes); Neurofibromatosis 1 - pathology; Neurology; Observer Variation; Pediatrics; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Human; Skin disease; Nervous system diseases; Diffusion tensor; Phacomatosis; Radiodiagnosis; Central nervous system; Diffusion imaging; Benign neoplasm; Neurofibromatosis Recklinghausen; Genetic disease; Encephalon
• ISSN: 0195-6108; 1936-959X
• DOI: 10.3174/ajnr.A0921

Hyperintensities on T2-weighted images are seen in the brains of most patients with neurofibromatosis type I (NF-1), but the origin of these unidentified bright objects (UBOs) remains obscure. In the current study, we examined the diffusion characteristics of brain tissue in children with NF-1 to test the hypothesis that a microstructural abnormality is present in NF-1.
Diffusion tensor imaging (DTI) was performed in 50 children with NF-1 and 8 controls. Circular regions of interest were manually placed in 7 standardized locations in both hemispheres, including UBO sites. Apparent diffusion coefficients (ADC), fractional anisotropy (FA), and axial anisotropy (A(m)) were used to differentiate quantitatively between healthy and disordered brain matter. Differences in eigenvalues (lambda(1), lambda(2), lambda(3)) were determined to examine parenchymal integrity.
We found higher ADC values for UBOs than for normal-appearing sites (P < .01) and higher ADC values for normal-appearing sites than for controls (P < .04 in 5 of 7 regions). In most regions, we found no differences in FA or A(m). Eigenvalues lambda(2) and lambda(3) were higher at UBO sites than in normal-appearing sites (P < .04).
With ADC, it was possible to differentiate quantitatively between normal- and abnormal-appearing brain matter in NF-1 and also between normal-appearing brain matter in NF-1 and healthy brain matter in controls, indicating subtle pathologic damage disrupting the tissue microstructure in the NF-1 brain. Higher diffusivity for lambda(1), lambda(2), and lambda(3) indicates that this disturbance of microstructure is caused by accumulation of fluid or vacuolation.