Download High lac Clinical applications of MRS

Magnetic Resonance Spectroscopy
By A. Ghazavi, M.D.
MR spectroscopy consensus group:
MR spectroscopy adds diagnostic and prognostic benefits to MR
imaging and adds in treatment planning and monitoring of brain
cancer.
MRI: Signal versus time
(anatomic changes)
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MRS: signal versus frequency
(biochemical and metabolic changes)
Long TE
Short TE
Clinical applications of MRS
1. Evaluation of normal brain development and regional brain
differences:
Newborn up to 3 months: increased MI and Cho
decreased NAA
No lac
Pre-term newborn up to 40 days: High lac
Clinical applications of MRS
2. Brain tumors:
Glioma: High Cho, Low NAA and Cr
differentiation between tumor and peri-tumoral edema
grading of tumor
Differentiation of neoplastic from pseudotumoral lesions
Metastasis
Near normal peri-tumoral MRS
Lactate level
Schwannoma: absence of Cr and increased lipid
Meningioma: high Cho and Ala
2. Epilepsy
Temporal lobe epilepsy: Mesial temporal sclerosis
If MRI negative
To evaluate the other apparent normal hippocampal head
To predict outcome of surgery
Low NAA/Cr and NAA/Cho
High Lac in post-ictal phase for 6 hours
3. Alzheimer’s disease:
Increased MI/Cr and decreased NAA/Cr in temporoparietal lobes and
hippocampi
Pick’s disease: the same but in only frontal lobe
Other causes of increased MI/Cr: DM, CRF, Hypernatremia and
chronic hypoxic encephalopathy
4. Metabolic disorders and leukoencephalopathy:
Phenylketonuria: increased phenylalanine
Canavan’s disease: increased NAA
5. Cerebral abscess v.s. necrotic tumor:
Low Cho, Cr and NAA
New resonance of aminoacids
Lac may increase
6. Acquired immunodeficiency syndrome:
Infants of HIV-infected mothers: decrease in NAA after 10 days
NAA
Toxoplasmosis
Lymphoma
Cryptococosis
PML
Cr
Cho
MI
Lac
Lipid
7. Multiple sclerosis:
Mobile lipid signal