Yin-Hui Siow MD, FRCPC Director of Nuclear Medicine Southlake Regional Health Centre

Yin-Hui Siow MD, FRCPC Director of Nuclear Medicine Southlake Regional Health Centre

Today Introduction to CT Introduction to MRI Introduction to nuclear medicine Imaging the dementias

The Brain ~ 1.5 kg (3lbs) Fatty organ (60%) Consistency of soft tofu It takes 5 parts of the brain to laugh at a joke

Brain Priorities The jockstrap was invented in 1874 NHL made helmets mandatory in 1979

Introduction to CT Computerized Tomography Computerized Axial Tomography

Advantages Very common Very fast

Disadvantages Ionizing radiation involved (lots) Primarily anatomic structures Very limited functional imaging Limited differentation between body structures

Introduction to MRI Magnetic Resonance Imaging Images from magnetic fields and radiowaves No ionizing radiation

Advantages High resolution Good contrast Great flexibility and potential No ionizing radiation

Disadvantages Long imaging time No movement Claustrophobia Expensive to buy and maintain Large, powerful magnets

Nuclear medicine Imaging modality Radioactive tracers Physiology vs anatomy

Brain SPECT Brain perfusion Activity proportional to blood flow Blood flow proportional to use SPECT (Single Photon Emission Computarized Tomography) allows different planes or slices

Disadvantages Lack of surrounding structures Moderately long imaging time Similar appearance to different pathologies

Right MCA Stroke

Large sulci causing perfusion defects

Best of Both Worlds Combine functional imaging with anatomic imaging Studies interpreted together (We need new software and equipment!)

Why do want to recognize dementia on imaging?

Leading Causes of Death 2014 United States Number of deaths for leading causes of death Heart disease: 596,577 Cancer: 576,691 Chronic lower respiratory diseases: 142,943 Stroke (cerebrovascular diseases): 128,932 Accidents (unintentional injuries): 126,438 Alzheimer's disease: 84,974 Diabetes: 73,831

Alzheimer s? Depression? Change in mood or personality Withdrawal from work or social Completing familiar tasks Memory loss disrupting daily life Changes in planning or solving problems Change in mood or personality Withdrawal from work or social Completing familiar tasks Memory loss disrupting daily life Changes in planning or solving problems

The Dementias Alzheimer s Disease 70% Vascular Dementia 20% Dementia with Lewy bodies Fronto Temporal Dementia Creutzfeldt-Jakob Disease Dementia from movement disorders

Where are we today when looking at dementia? CT & MRI for anatomic imaging SPECT for functional imaging

Alzheimer s Dementia CT & MRI Imaging Atrophy in: Parietal lobe Posterior cingulate gyrus Inferior frontal lobe entorhinal and hippocampal cortex

Normal vs atrophy

Parietal and Posterior Cingulate Atrophy

Atrophy of hippocampus

However 50% of normal controls also had atrophy in same distribution The British Journal of Radiology, 1993, 66, 23-27, Wyper,D. et al,

Alzheimer s Dementia CT & MRI Imaging Hippocampal atrophy most accurate for Alzheimer s Rate of hippocampal atrophy more accurate than cortical measurement alone

Alzheimer s Dementia SPECT Imaging Decreased perfusion posterior parietal temporal lobes, posterior cingulate cortex and inferior frontal lobes Posterior distribution

Typical Alzheimer s Pattern

Alzheimer s Normal

Alzheimer s Microscopic Pathology plaques & tangles Intracellular Tau protein (neurofibrillary tangles) deposits Extracellular beta amyloid plaques

Future Alzheimer s Imaging Now, imaging of function Direct imaging of beta amyloid

New Alzheimer s Imaging PET compounds 11 C PIB 18 F - florbetapir (Amyvid)

11 C PIB Imaging

Uses of Amyloid Imaging Confirmation of diagnosis Identify patients at risk Use in drug trials

Controversies with Amyloid imaging Lack of available treatment Insurance eligibility Social stigma Psychological impact

Multi Infarct Dementia CT & MRI Imaging Old and new infarcts Burden of small vessel ischemic disease with FLAIR Presence of hemosiderin deposits relating vascular risk factors, lacune infarcts and small vessel ischemia

Multi Infarct Dementia brain SPECT Variable distribution of perfusion defects Sensitivity much less than CT or MRI

Large Infarcts on CT

Multiple Infarcts on MRI

Multi infarct Dementia

Same patient

Same patient

Large burden of small vessel disease

MRI and Small Vessel Ischemic Disease

Microhemorrhages on MRI

Frontotemporal Dementias (FTD) Atrophy and decreased perfusion in frontal and anterior temporal lobes frontal distribution

Frontotemporal Dementias

Frontotemporal dementia Normal

Dementia with Lewy Bodies (DLB) Looks like Parkinson s clinically and pathologically Atrophy striatum, midbrain, hypothalamus Preservation of hippocampus Looks like Alzheimer s on functional imaging Also involvement of occipital lobes

DLB AD normal

Summary Dementia distribution imaging Alzheimer s Posterior MRI & SPECT Multi infarct Variable MRI FTD Frontal MRI & SPECT DLB Posterior MRI & SPECT

Conclusions CT very accessible but limited utility Combined brain SPECT and MRI better PET amyloid imaging best Support the Southlake Foundation!

siowyinhui@gmail.com