NeuroImaging Dr. Norman Pay
Jan 12, 2016
NeuroImaging
Dr. Norman Pay
CT
• Transmission
CT• Transmission• Density differences• Ionizing radiation• Iodinated contrast material• Spatial resolution• Fast scanning times and acquisition• Appropriate in emergent situations,
claustrophobic patients, body coverage
• Utilization for contraindications in MRI as aneurysm clips, cardiac pacemakers, etc.
• Biopsies• Workstation compatibility • CT angiography
RADIATION
• Sv (Sievert) – absorbed dose in biological tissue
• 2 mSv/ year – background radiation• 24 mSv/ year –background radiation for
airline cruising altitude• 6.8 mSv – chest CT scan• 10-30 mSv – single full body CT scan• 21 Sv – fatal dose
CT Angiography
CAROTID STENT CAROTID TRAUMATIC ANEURYSM
MRI• Proton Relaxation• Signal intensities• Contrast resolution• Gadolinium (Gd) contrast • Nephrogenic Systemic Fibrosis
(NSF) – Gd contraindicated in Low GFR states (<30) and renal failure
• Non-ionizing, non-invasive• Workstation compatibility• More complex, longer
acquisitions and set-up• Magnet bore - claustrophobia• MR angiography
MR Angiography
CAVERNOMA CAROTID DISSECTION CAROTID OCCLUSION
T1 T2 Flair
Diffusion GRE Contrast
MR sequences
• T1 – anatomy, CSF dark• T2 – screening, CSF bright• FLAIR (fluid attenuated inversion recovery)
– similar to T2• MR diffusion – bright signal for restriction• GRE (gradient echo) – susceptibility- dark
signal• Gadolinium, T1 – bright signal• MR angiography and perfusion –
Gadolinium utilization
• Anatomy of the Brain• Spatial Resolution
– CT Density
• Contrast Resolution– MR Signal Intensity
• Intravenous Contrast– Iodinated contrast– Gadolinium contrast
NEURONAL MIGRATION
CORTICAL DYSPLASIA
FLAIR T2
Stroke
• Acute ischemic stroke (AIS) – 3rd leading cause of death, leading cause of disability in adults
• 700,000 ischemic strokes annually in the U.S.
• Reperfusion therapy is the only proven treatment of AIS
CT and MR
• Time to infarct• Time to treatment• Extent of infarct• Hematoma• Recovery
PRE THROMBUS LYSIS POST THROMBUS LYSIS
PRE THROMBUS LYSIS POST THROMBUS LYSIS
CT
MOYA-MOYA
FLAIR
Pattern Recognition
Diagnostic Neuroradiology, pg 130-131.Osborn, Anne G., M.D. Mosby – Year Book, Inc., 1994.
Pattern Recognition
Diagnostic Neuroradiology, pg 130-131.Osborn, Anne G., M.D. Mosby – Year Book, Inc., 1994.
MR DIFFUSION
• Diffusion refers to the general transport of molecules, mixing through agitation and randomly
• The driving force is the motion of water within water, driven by thermal agitation called Brownian motion
• If restricted as in acute infarcts, decreased diffusion results
• Decreased diffusion displayed as bright MR signal
MR DIFFUSION
• Failure of Na+/K+ ATPase and other ionic pumps – net shift of water from the extracellular to the intracellular space
• Cell swelling with decrease in extracellular space
• Increased intracellular viscosity and cell membrane permeability
• Temperature decrease• Decreased diffusion in acute stroke
CT MR DIFFUSION
CEREBELLAR INFARCT
CT MR
MIDDLE CEREBRAL ARTERY INFARCT
DIFFUSION DIFFUSION DIFFUSION
BASILAR ARTERY OCCLUSION
MRA MRA
FLAIR DIFFUSION
ACUTE INFARCT
EMBOLIC DISEASE – ATRIAL FIBRILLATION
MR DIFFUSION
T1 T1 T2
CONTRAST
POSTERIOR CEREBRAL ARTERY
INFARCT
FLAIR FLAIR T2
VASCULITIS
FLAIRFLAIR DIFFUSION DIFFUSION
STATUS POST AORTIC VALVE SURGERYHYPOTENSION
Neuroimaging in acute ischaemic stroke: insights into unanswered questions of pathophysiology. Wardlaw, J. M. Journal of Internal Medicine 267; 172–190.
Blackwell Publishing Ltd. 2010.
MR DIFFUSION
Neuroimaging in acute ischaemic stroke: insights into unanswered questions of pathophysiology. Wardlaw, J. M. Journal of Internal Medicine 267; 172–190.
Blackwell Publishing Ltd. 2010.
CT MR
MIDDLE CEREBRAL ARTERY INFARCT
Hematoma
• Hemorrhagic transformation – dreaded complication
• Exclusion of hematoma -prerequisite for treatment
• Cue for emergent intervention
CT
INFARCT HEMORRHAGE INTO INFARCT
EPIDURAL EPIDURAL SUBDURAL
HEMATOMA
ISODENSE REBLEED
SUBDURAL HEMATOMA
Magnetic Resonance Imaging of the Brain and Spine, 3rd ed., Vol. 1, pg 788.Atlas, Scott W., M.D., editor. Lippincott Williams & Wilkins, 2002.
HEMATOMA
GREFLAIR
CT T1 T2
SUBDURAL HYGROMA AND HEMATOMA
SUBDURAL HEMATOMA
T1 CT T2
CHRONIC CHRONICCHRONIC
CT FLAIR FLAIR
SUBARACHNOID HEMORRHAGE
ANTERIOR COMMUNICATING ARTERY
(ACA) ANEURYSM
T1 T1 FLAIR
VENOUS THROMBOSIS AND VENOUS INFARCT
SIDEROSIS
GRE
GREFLAIR CT
BENIGN MALIGNANT MALIGNANT
HEMATOMA
MALIGNANT HEMATOMA
T1 T2 CONTRAST
T1GRECT
T2
CYST
SUMMARY
• CT and MR utilize different technologies, often complementary
• Advantages and disadvantages of CT and MR
• CT and MR advances pari-passu with computing capabilities
•Moore’s Law
REFERENCES• Diagnostic Neuroradiology, pg 130-131. Osborn,
Anne G., M.D. Mosby – Year Book, Inc., 1994.• Magnetic Resonance Imaging of the Brain and
Spine, 3rd ed., Vol. 1, pg 788. Atlas, Scott W., M.D., editor. Lippincott Williams & Wilkins, 2002.
• Neuroimaging in acute ischaemic stroke: insights into unanswered questions of pathophysiology. Wardlaw, J. M. Journal of Internal Medicine 267; 172–190. Blackwell Publishing Ltd. 2010.