by: Prof.Dr. Hosna Moustafa Cairo University, Egypt Brain Imaging ( 1 ) by: Prof.Dr. Hosna Moustafa Cairo University, Egypt

Brain Imaging Radionuclide brain imaging is differnet from anatomic imaging as C.T., M.R.I. in being functional imaging. Radionuclides may be used to study: Cerebral blood flow: 123-I iodoamphetamine Tc99m- ECD Tc99m- HMPAO

Principle radiopharmaceuticals used to study C.B.F. Washout Brain Uptake Extraction Peak activity (min.) Redistribution 6.5 – 8 % > 90% 20 I123-IMP 85 % stable 5 – 7 % 80 % 2 Tc99m-HMPAO 6 % per Hr. 70 % Tc99m- ECD

Brain Imaging Dual or single head SPECT gamma camera, multi-head is better (better resolution 6 - 9 mm) Low-energy high-resolution collimator 20% window at 140 KeV of Tc Start imaging 30 minutes – 3 hours

Brain Imaging Ensure dim light with no noise Patient is supine and head is fixed in head holder Remind the patient NOT TO MOVE during the procedure Imaging should be done for 360 degree, each for 30 sec., using 128 X 128 matrix. Hamming or hanning filter is used in reconstruction to have images in transverse, sagittal and coronal cuts.

Normal brain perfusion study using Tc99m-HMPAO

Clinical Applications Cerebro-Vascular stroke Epilepsy Dementia Brain death Traumatic lesions

Large left frontal and temporal lobe perfusion defect Decreased perfusion to the right cerebellar hemisphere. Large left middle cerebral artery stroke with crossed cerebellar diaschisis.

Base line study with large righ ttempro pariatal lobe hypoperfusion defect with Decreased perfusion to the left cerebellar hemisphere. follow up study with partial improvement in cerebral perfusion

Focally increased perfusion involving the left fronto-temporal region (Luxury perfusion)

2-Epilepsy Epilepsy is a paroxysmal and transitory disturbance of the brain function. Radionuclide brain SPECT can diagnose and localize site of focus in 70-90% as compared to 17-34% in C.T. and M.R.I. If injected in ictal phase, a focal area of hyperperfusion is seen with 90% sensitivity. If injected in inter-ictal phase, a focal area of hypoperfusion is seen with 60 – 70% sensitivity.

A B Inter-ictal SPECT with hypoperfusion in the left temporal region (B) Ictal SPECT with hyperperfusion in the left temporal region

3- Dementia Alziehemer’s disease is a common cause of dementia with scan pattern of bilateral hypoperfusion in temporoparietal regions, while basal ganglia is normal Multi-infarcts dementia: multiple scattered areas of hypoperfusion in both cerebral cortices.

Early Alziehemer’s disease with bilateral hypo-perfusion in bilateral front-parietal regions, more evident in left side.

Advanced Alzeihemer’s disease with marked hypoperfusion all through the cortex with normal uptake in basal ganglia and minimal changes in C.T.

Perfusion defects involving lateral frontal, posterior parietal, and posterior temporal lobes on the left side.

4- Brain Death In patients with deep coma, it is important to be sure of brain death, especially if organ transplant is needed. Scan pattern show no blood flow to the brain which is sure sign of death compared to EEG.

Initial SPECT study (before brain death) showed massive perfusion deficit in the areas supplied by the anterior and middle cerebral arteries. A repeat SPECT study after 3 days showed NO cerebral perfusion, indicating brain death.

5- Traumatic lesions Common with increased motor car accidents Early functional damage can be detected with radionuclide imaging as areas of hypoperfusion. The prognostic aspects depend on site and size of involved lesions, if multiple sites are involved or one half of the brain is more affected, this indicates poor prognosis. Brain SPECT allow to evaluate degree of recovery in traumatic lesions.

CT shows small subarachnoid contusional hemorrhage in both frontal lobes SPECT shows absence of tracer uptake in anteromedial aspect of both frontal lobes. CT 1 month later shows hypodense haematoma in both frontal lobes SPECT image show improvement in cerebral perfusion, in both frontal lobes.

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