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Prepared By: S. Ehtesham Al Hanif (Hridoy) [0510035

BIO (BIO-MEDICAL) ENGINEERING SPECT NUCLEAR

ME 471- BIO-ENGINEERING / BIO-MEDICAL

TOPICS: SPECT NUCLEAR

Prepared By,

S. EHTESHAM AL HANIF (HRIDOY)

STUDENT ID: 0510035

E-MAIL: SEAHHRIDOY@GMAIL.COM

MOBILE: 88-01670839383

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Prepared By: S. Ehtesham Al Hanif (Hridoy) [0510035

BIO (BIO-MEDICAL) ENGINEERING SPECT NUCLEAR

Positron Emission Tomography (PET)

Relies on injection of a radioactive isotope to measure cerebral blood flow. Whereas fMRI images rely on the interaction of multiple factors (different tissue proton densities, relaxation

times, a combination of CBF, CBV, CRMO and CRMGl) PET relies only on only one factor for a given experiment

(e.g., usually CBF but can be CBV or CRMO)

PET Positron Emission Tomography (PET) uses a ligand tagged with a positron emitting isotope such as 11C or 13N. The compound then binds quickly to a certain area of the body. For example, glucose tagged with 11C will bind inside the brain. The isotope will then decay emitting a positron which annihilates a free electron usually no farther than 1 mm away

Diagram depicting how a PET scan works

Two co-linear gamma rays, which result from the annihilation, emerge 180 degrees from one another, and can be detected by an array of scintillators that surround the patient When the photons are recorded both simultaneously and 180 degrees apart, the sensors can

infer where the annihilation occurred. PET has an advantage over other types of imaging in that it is capable of high resolution. Thus, it can be used, for example, in imaging and studying receptor

proteins in the body.

Transcranial magnetic stimulation (TMS)

Typically an interruption of function creating temporary lesions in the healthy brain. Great for pinpointing regions involved in specific components of tasks or for mimicking neurological disorders. Single vs. rapid-pulse TMS inherent dangers in rapid-pulse TMS Poor spatial resolution vitamin E tablets and MRI help! (and magnetic dipole modeling as in VEPs)

Single Photon Emission Computed Tomography (SPECT)

Less spatial resolution than PET but far less expensive Often used for early detection of dementias evidenced by hypoperfusion in a given area 10 SPECT

o Single Photon Emission Computed Tomography is the goal of the experiment described in this paper.o SPECT uses one or more gamma cameras that can be rotated around a patient to gather 2-D images

from different angles.

o Whereas PET uses a positron emitting tracer, SPECT uses a photon emitting tracer that is detected bythe gamma cameras.

o The radioactive isotope used in the present experiment is 125I.o After injection of the tracer, the PSPMTs are used to detect the gamma-rays given off by the isotope.

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Prepared By: S. Ehtesham Al Hanif (Hridoy) [0510035

BIO (BIO-MEDICAL) ENGINEERING SPECT NUCLEAR

o A SPECT computer system can then recreate three dimensional images of the radio isotope

Electro-encephalogram (EEG)

Scalp potentials EEG used clinically but from this we can get visually evoked potentials (VEPs) and the like. Dipole modeling used to locate the source of the VEP Requires many trials poor spatial but great temporal resolution.

Combinations

fMRI and single cell in monkeys (Logothetis) Non-pherous EEG recordings with fMRI in humans TMS and PET (Paus, 1999; Desmurget et al. 1999)