Dr Hussein Farghaly PSMMC Radionuclide Brain Imaging Master Watermark Image: Lecture 4

Syllabus Contents Cerebral Anatomy Cerebral Perfusion Imaging Radiopharmaceuticals Methodology Dosimetry Clinical Applications Cisternography Radiopharmaceuticals Methods Pharmacokinetics Dosimetry Clinical Applications

Clinical Indications of Brain Perfusion Imaging Cerebral ischemia Dementia Seizures Alzheimer diseases psychiatric diseases Brain death Parkinson's Disease

Transient Ischemic Attacks It occurs in 10 to 20% of stroke patients. One third of these patients suffer a stroke within 5 years without treatment.

Transient Ischemic Attacks(Cont.) Single or multiple cerebral blood perfusion defect or abscent Early detecting ischemia region with SPECT compared to CT or MRI. Sensitivity is about 55-60% with SPECT, the sensitivity declines with time. SPECT CBF stress test with Diamox has been shown to increase the likelihood of detection of residual blood flow changes after TIA.

Transient Ischemic Attacks

(Diamox) SPECT IN TIA Semiquantitative analysis of ischemia with acetazolamide (Diamox) SPECT. A, Tc-99m HMPAO SPECT before acetazolamide (left) shows mild left parietal hypoperfusion. After acetazolamide (right), the brain shows increased activity in response to vasodilation, with the exception of the left parietal defect and the decreased activity from ischemia is even more apparent. B, Cortical region of interest (ROI) boxes are drawn like a clock numbered from 1 o’clock to 12 o’clock to generate regional cerebral blood flow (rCBF curves). In this patient, the curves after acetazolamide administration are increased relative to rest perfusion with the exception of a dip from 2 o’clock to 4 o’clock. This signifies an area at high risk for infarction because it is unable to respond to the vasodilation.

Carotid Artery Balloon Occlusion Test Left, HMPAO SPECT performed after a carotid balloon occlusion injection shows severe left middle cerebral artery territory hypoperfusion identifying a high risk for stroke. The patient underwent permanent left carotid occlusion using gradual occlusion with a Selverstone clamp rather than bypass. Right, This gradual occlusion was not sufficient to protect the patient, and the patient had a stroke, seen on CT in the same distribution as the SPECT.

Brain Death

Brain Death Scintigraphy: Summary Protocol

Brain death. This Tc-99m DTPA brain blood flow study shows radiotracer transiting the internal carotids; however, there is no intracerebral blood flow. Only external carotid blood flow to the scalp is seen.

Brain death evaluation Head trauma victim 3 days later Tc-99m HMPAO examination 1- No visualization of the brain is seen with Tc-99m HMPAO, making it the easiest test to interpret. 2- A secondary finding, the “hot nose” sign is often seen Diagnosis of BD in SPECT