Seyed Ali Nabavizadeh MD, Presenter: Nothing to Disclose

Sanjeev Chawla PhD, Abstract Co-Author: Nothing to Disclose

Arastoo Vossough MD, PhD, Abstract Co-Author: Nothing to Disclose

Harish Poptani PhD, Abstract Co-Author: Nothing to Disclose

Elias Rafic Melhem MD, PhD, Abstract Co-Author: Nothing to Disclose

Proton MR spectroscopy is often used to discriminate low-grade brain tumors and non-tumoral masses based on the elevation of choline. In this study, we sought to determine the frequency of absence of choline elevation in a heterogeneous population of low grade brain tumors.

In this single center study, 41 patients with histopathologically confirmed low grade brain tumors who underwent multi-voxel proton magnetic resonance spectroscopic imaging (1H-MRSI) were retrospectively investigated. All MR imaging and 1H-MRSI was performed on a 3 Tesla MR system. 1H-MRSI data were analyzed from voxels that exhibited FLAIR hyperintensity. Voxels encompassing the contralateral normal appearing white matter were also analyzed for comparison. 1H-MRS indices [N-acetyl aspartate (NAA); creatine (Cr); choline (Cho); myo-inositol (mI) and lipid +lactate (Lip+Lac)] were computed from these regions. The area under the curve of choline peak was normalized with respect to that of Cr and unsuppressed water from the same voxel. Cho/Cr and Cho/water ratios from all the voxels from the ipsilateral side were compared from voxels from contralateral side in all the cases.

Six (14%) of low grade brain tumors, including two oligodendrogliomas, two dysembryoplastic neuroepithelial tumors (DNETs), one ganglioglioma, and finally one case of gliomatosis cerebri showed lack of elevation of choline levels with respect to the contralateral normal white matter. The patient with gliomatosis cerebri showed significant elevation of Myo-inositol (mI) along with decreased levels of choline.

Choline may not be elevated in a relatively high proportion of patients with low grade brain tumors. Knowledge of possible absence of elevation of choline in low grade tumors is important in defining the role of 1H-MRS as an adjunct to conventional imaging findings.

Awareness of the fact that a significant proportion of low grade tumors may not have increased choline on MRS is important in the clinical imaging interpretation of brain masses and mass-like lesions.

Nabavizadeh, S, Chawla, S, Vossough, A, Poptani, H, Melhem, E, Absence of Choline Elevation in Low Grade Brain Tumors: How Often Does It Occur?.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8008414.html