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AJNR - American Journal of Neuroradiology

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American Journal of Neuroradiology 27:794-798, April 2006
© 2006 American Society of Neuroradiology

PEDIATRICS

Hypothalamic Hamartomas: Correlation of MR Imaging and Spectroscopic Findings with Tumor Glial Content

D.R. Amstutz^a, S.W. Coons^b, J.F. Kerrigan^c, H.L. Rekate^d and J.E. Heiserman^a

^a Division of Neuroradiology, Barrow Neurological Institute, Phoenix, Ariz
^b Division of Neuropathology, Barrow Neurological Institute, Phoenix, Ariz
^c Department of Child Neurology, Barrow Neurological Institute, Phoenix, Ariz
^d Division of Neurosurgery, Barrow Neurological Institute, Phoenix, Ariz

Address correspondence to Joseph Heiserman, PhD, MD, Division of Neuroradiology, Barrow Neurological Institute, 350 West Thomas Rd, Phoenix, AZ 85013

BACKGROUND AND PURPOSE: There is variability in the literature concerning the appearance and histology of hypothalamic hamartomas. This study correlates the MR imaging and proton MR spectroscopic properties of hypothalamic hamartomas with histopathologic findings.

METHODS: Studies were performed with 3T and 1.5T scanners. Single voxel hamartoma spectra were acquired by using short-echo-time point-resolved spectroscopy sequences (PRESS). 2D PRESS chemical shift imaging (CSI) spectroscopic sequences were also obtained for comparison of tumor-derived spectra with normal gray matter of the amygdala. Sequences were used to compare choline (Cho), N-acetylaspartate (NAA), and myoinositol (mI) resonances by using a creatine (Cr) reference. Spectral ratios and T2 signal intensity ratios of the hamartomas were then compared with histopathologic findings.

RESULTS: Data from single voxel spectroscopic sequences demonstrated a statistically significant decrease in NAA/Cr and an increase in mI/Cr ratios in tumor tissue when compared with values in normal gray matter of the amygdala. In addition, Cho/Cr ratios were also increased when compared with those in normal gray matter controls. Among the 14 hamartomas sampled, a spectrum of increased mI/Cr ratios was seen. Those tumors with markedly elevated mI/Cr demonstrated an increased glial component when compared with the remaining tumors. Increased glial component was also found to have a positive correlation with hyperintensity of lesions on T2-weighted images.

CONCLUSION: We have identified a correlation between the glial/neuronal fraction as determined by histopathology and MR spectral and T2 hyperintensity variations among hypothalamic hamartomas.