simple notes for start..

1. MR SPECTROSCOPY
BY
NILOFER NESHAT
B.SC 3RD YEAR

2. INTRODUCTION
• Magnetic Resonance (MR) spectroscopy is a non invasive diagnostic test
for measuring biochemical changes in the brain, especially the presence
of tumours .
• The magnetic resonance imaging (MRI) identifies the anatomical
location of a tumour , whereas MR spectroscopy compares the chemical
composition of normal brain tissue with abnormal tumour tissue.
• This test can also be used to detect tissue changes in stroke and
epilepsy.

3. Working of MR spectroscopy
• MR spectroscopy is conducted on the same machine as conventional
MRI.
• The MRI scan uses a powerful magnet, radio waves, and a computer to
create detailed images. Spectroscopy is a series of tests that are
added to the MRI scan of your brain or spine to measure the chemical
metabolism of a suspected tumor.
• The frequency of these metabolites is measured in units called parts
per million (ppm) and plotted on a graph as peaks of varying height.
• By measuring each metabolite’s ppm and comparing it to normal
brain tissue, the Neuro-radiologist can determine the type of tissue
present.

4. • MR spectroscopy can be used to determine tumour type and
aggressiveness, and distinguish between tumour recurrence and
radiation necrosis.
• They require interpretation and should always be correlated to the MR
images before making a final diagnosis.
• If all the signals were used for MRS, the fat and water peaks would be
huge and scaling would make the other metabolites peak invisible. Fat
and water are eliminated.
• Fat is avoided by placing the voxel for MRS within the brain , away
from the fat in bone marrow and scalp.

5. Typical metabolism present in human tissues
SPECTRUM ABBREVIATION EFFECT RESONANCE
N-acetyl aspartate NAA Neuronal marker 2.0 ppm
Lactate Lac Product of anaerobic
glycosis
1.3 ppm
Choline Cho Present in cell
membrane
3.2 ppm
Creatine Cr – PCr 3.0 ppm
Lipids Lip Result of cellular
decay
0.9 – 1.3 ppm
Myo-inositol Ins Glial cell marker 3.5 – 3.6 ppm
Glutamineglutamate Glx neurotransmitter 2.1 – 3.8 ppm

6. Ml – Myo-inositol
Cho – choline
Cr / Pcr – Creatine
Glu / Gln – glutamine / glutamate
NAA – N-acetyl aspartate
Lac / Lip – lactate / lipid

7. Techniques
Single voxel technique:
• It is the simplest technique to
acquire and interpret and hence,
the most widely used.
• They provide high signal-to-noise
in a relatively short scan time.
• The imaging time is fast { 3 – 5
minutes per voxel }.

8. Multi voxel technique:
• It has lower signal to noise but has a
larger total coverage area , since the
size of the entire multi-voxel slab is
greater.
• A wide coverage area is important for
large, heterogeneous lesions like the
brain tumor, where MVT provides
better information.
• The imaging time is slower and
depends on the resolution { 5 – 8
minutes for 2D and 7 – 15 minutes for
3D }

9. Preparation for the test
• Avoid caffeinated beverages.
• Wear comfortable clothes since you will be lying still for about 30
minutes.
• Avoid wearing jewelry and metal, and remove credit cards.

10. Uses of MRS
MRS is used in the following ways:
• To diagnose in conjunction with MRI
• Biopsy guidance
• Therapy monitoring.
• It is useful in stroke and tumor staging, especially in the brain, breast
and prostate.
• It may also have some use in the diagnosis and understanding of
depression, epilepsy .

11. Risk in the procedure
• MRI and MR spectroscopy are very safe.
• There are no known health risks associated with the magnetic
field or the radio waves used by the machine.
• Some people are sensitive to the contrast agent and may
develop an allergic reaction

12. THANK YOU