Brain tumors and MRS

1-In brain tumors, the following changes will occur putting in your consideration that as the malignancy increased these changes will be more apparant:

-NAA: Decreases as the tumor will destroy the neurones.

-Creatine: Decreases as tumors with high metabolism will reduce the energy store.

-Choline: Increases as hyper cellular tumors with rapid growth will increase it.

-Lactate: Increases when tumor exceeds the capability of its blood supply and try to increase anerobic glycolysis.

-Lipids: Increased  in necrotic portion of the tumor.

2-In case of tumor recurrance, choline will be increased.

3-You should evaluate the presence of high choline outside the enhanced margins of the mass to see the true extension of the tumor.

4-Following radiation, there are decreased NAA, creatine and choline.

5- In case of radiation necrosis, Increased lipid and lactate.

6-In case of meningioma, there is increased alanine at 1.48 ppm with no NAA, very low creatine and increased glutamates.

The normal MR spectra obtained from gray matter and white matter are shown below. Predominant metabolites, displayed from right to left, are NAA, creatine, choline, and myo-inositol. The primary difference between the two spectra is that gray matter has more creatine.� Hunter's angle is the line formed by the metabolites on the white matter spectrum. The common way to analyze clinical spectra is to look at metabolite ratios, namely NAA/Cr, NAA/Cho, and Cho/Cr. Normal and abnormal values are shown in the chart above. By including a known reference solution when acquiring the MR spectral data, absolute concentrations of metabolites can be calculated.