Rationale and objectives: Evaluate proton magnetic resonance spectroscopy ((1)H-MRS) for assessing and grading brain tumors.
Materials and methods: The research was done at Detroit Medical Center in a 1.5-T Siemens MR magnet using single-voxel or multivoxel MRS. This study consisted of 27 patients: 10 females and 17 males ages 22-83 years (average age 43.8). The data were recorded for three peaks-N-acetyl aspartate (NAA), choline (Cho), creatine (Cr)-which were used to calculate the ratios Cho/NAA and Cho/Cr.
Results: Abnormal spectra were seen in 25 patients and normal spectra in 2. In 16 patients with brain astrocytoma of various grades, the pathology grading was correlated with Cho/NAA and Cho/Cr. These values were 6.53 and 3.35 for nine patients with Grade 4 astrocytoma; 1.85 and 1.62 for three patients with Grade 3 astrocytoma; 2.21 and 1.50 for three patients with Grade 2 astrocytoma; and 1.45 and 1.49 for one patient with Grade 1 astrocytoma. The remaining nine patients with abnormal spectra were also correlated with pathology.
Conclusion: MRS ratios can be used to differentiate malignant and nonmalignant lesions from normal brain tissue. In general, high-grade astrocytoma have higher Cho/NAA and Cho/Cr ratios compared with low-grade astrocytoma.