Brain Imaging

Frank P. Dawry Physx.home.comcast.net Brain Imaging Common Indications Detection and evaluation of cerebrovascular disease (stroke) Diamox challenge – blood shunt Evaluation of patients with suspected dementia (Alzheimer’s) Pre-surgical localization of epileptic foci PET ECD Evaluation of suspected brain trauma altered Blood brain barrier Differentiate between tumors and necrosis Differentiate between tumors and infection Brain Death – no arterial blood flow DTPA blood flow HMPAO, ECD – brain specific tracers CSF Dynamics Cisternogram Shunts Leakage

Frank P. Dawry Physx.home.comcast.net Anatomy Cerebrum - Two hemispheres connected by nerve bundles (Corpus Callosum )  Frontal lobe located directly behind the forehead helps control voluntary movement aids higher intellectual functions  as solving a math problem  planning an event.  Temporal lobe Associated with speech, sound and complex visual perceptions.  Occipital lobe deals with vision.  Parietal lobe plays a role in sensory processes, attention and language.

Frank P. Dawry Physx.home.comcast.net Anatomy Midbrain  relays sensory information from sense organs to other brain areas  coordinates some reflex activity size of the eye’s pupil. Hindbrain  relays information from the spinal cord to other parts of the brain  helps control movement coordination, involuntary functions and equilibrium.  Cerebellum helps control movement aids cognitive processes that require precise timing, such as playing a musical instrument. Spinal cord  is protected by a fluid-filled bony canal and extends along the back  in an adult it is roughly 18 inches long and contains 31 pairs of nerves.  serves as a pathway for nerve signals to travel to and from the brain  as a center for coordinating many reflex actions independently of the brain

Frank P. Dawry Physx.home.comcast.net Ventricular system CSF Formed in the choroid plexus in each ventricle Provides a fluid cushion upon which the brain “floats” Removes waste Provides nutrients

Frank P. Dawry Physx.home.comcast.net Vascular system Arterial blood supplied by  Internal Carotid Arteries  Vertebral Arteries

Frank P. Dawry Physx.home.comcast.net Vascular system Anterior Cerebral Arteries supply the  Frontal lobes  Parietal lobes Posterior Cerebral Arteries supply the  Temporal lobes  Occipital lobes

Frank P. Dawry Physx.home.comcast.net Blood-Brain Barrier The tight seal of cells that lines the blood vessels in the brain  Allows Lipophillic diffusion Selective active transport  Excludes Large molecules Toxins Unless disrupted

Frank P. Dawry Physx.home.comcast.net SPECT Single Photon Emission Computerized Tomography

Frank P. Dawry Physx.home.comcast.net Tomographic planes

Frank P. Dawry Physx.home.comcast.net Image Orientation

Frank P. Dawry Physx.home.comcast.net

Frank P. Dawry Physx.home.comcast.net

Frank P. Dawry Physx.home.comcast.net Radiopharmaceuticals Cerebrovascular Disease, Epilepsy - Perfusion studies (vascular imaging) Crosses the intact Blood-Brain barrier (BBB) - Lipid-soluble Tc99m-HMPAO (Exametazime) – CERETEC (stabilized) millicuries (mCi) Tc99m-Bicisate (Ethyl cystine dimer [ECD]) – NEUROLITE millicuries (mCi) FDG Tumor altered BBB Tl-201 Thallium - does not normally cross the BBB 3-5 millicuries (mCi) Tc99m-Sestamibi - does not normally cross the BBB millicuries (mCi) FDG – increased glucose metabolism CSF - cisternogram In-111 DTPA – sterile (pyrogen free) 0.4 – 0.75 millicuries (mCi) Brain Death no arterial blood flow DTPA blood flow HMPAO, ECD – brain specific tracers

Frank P. Dawry Physx.home.comcast.net Neuroendocrine tumor imaging Neurotransmitters  chemical messengers released at nerve ending terminals  bind to receptors on the surface of the target neuron. Octreoscan Indium-111

Frank P. Dawry Physx.home.comcast.net Patient Procedure Vascular imaging Pre-Arrival Patients should be instructed to avoid caffeine, alcohol or other drugs known to affect cerebral blood flow (CBF). Pre-Injection Evaluate the patient for his/her ability to cooperate. Achieve a consistent environment at the time of injection and uptake: i. Place the patient in a quiet, dimly-lit room. ii. Instruct the patient to keep his/her eyes and ears open. iii. Ensure that the patient is seated or reclining comfortably. iv. Place intravenous access at least 10 min prior to injection to permit accommodation. v. Instruct the patient not to speak or read. vi. Have no interaction with the patient prior to, during or up to 5 min post-injection. Perform SPECT imaging 30 minutes post injection 128x128 matrix 3 degrees/step 20 seconds/stop

Frank P. Dawry Physx.home.comcast.net Patient Procedure Tumor - altered BBB No special preparation 3-4 millicuries (mCi) Perform SPECT imaging 10 minutes and 3 hours post injection – analyze ROIs 128x128 matrix 3 degrees/step 20 seconds/stop CSF - cisternogram Sterile injection! Performed by a RAM licensed physician, or under his/her supervision image at 6, 24 & 48 hours post injection Medium energy collimation 173 & 247 photopeak window 100,000 counts/image or 10 minutes/view 128x128 matrix Brain Death Tourniquet around the patient’s scalp, just above the eyebrows and ears – so long as there is no history of brain trauma Obtain flow in anterior or posterior projection 128x128 matrix 2 seconds/frame for 90 seconds Obtain Anterior, Left and Right Lateral, and if possible, Posterior static (planar) images at 5 minutes post flow 256x256 matrix 500,000 counts/image