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IMAGING OF INTRACRANIAL HAEMORRHAGES
Abdullah Albakri
Objectives
• Normal anatomy• Physical principles• Intraparenchymal haemorrhage (IPH)• Subarachnoid haemorrhage (SAH)• Subdural haematoma (SDH)• Epidural haematoma (EDH)• New imaging applications
Introduction
• IC haemorrhages constitute a heterogeneous group of disorders
• Occur spontaneously or a result of direct trauma to cranium
• Management is closely related diagnostic modalities
Classification
Intraparenchymal haemorrhage
• The most common risk factors
• Hypertension• Has predictable localisation, supplied
by perforators; putamen > subcortical WM, cerebellum > thalamus > pons
• Deep brain
• Cerebral amyloid angiopathy • Elderly • Lobal in nature (posterior)
• Tumors
Imaging modalities (CT)
• NCCT Still the gold standard in many enters
• Degree of x-ray attenuation is determined by• Hematocrit• Blood clot retraction • Hb content
• Heamorrhge avearaging 60 HU to 100 HU
• 3 phases• Acute• Subacute • Chronic
55 Y old man with BP 220/110 mmHg on admission
Acute haemorrhage• Hyperdense
Subacute haemorrhage• Small• Centripetally
Cerebral amyloid angiopathy
Posterior hemisphere acute hemorrhage, such as those observed in patients with amyloid angiopathy. A, The CT shows a small hemorrhage outside of the perforator territories. B, The hemorrhage is hardly visible in T1-weighted imaging, as would be expected in the acute phase. C, Gradient-refocused echo imaging clearly displays the hemorrhage.
Imaging modalities (CT with contrast)
• The routine utilisation of IV contrast is unwarranted(CONTINUUM: Lifelong Learning in Neurology. Neuroimaging. 14(4, Neuroimaging):37-56, August 2008)
• In general, contrast studies are indicated in patients without a clear underlying aetiology or in patients with haemorrhages in unusual locations(Guidelines for the Management of Spontaneous Intracerebral Hemorrhage in Adults: 2007 Update: A Guideline From the American Heart Association/American Stroke Association Stroke Council, High Blood Pressure Research Council, and the Quality of Care and Outcomes in Research Interdisciplinary Working Group: The American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists)
• To detect hematoma expansion “hot spot”• Tumor
History of hypertension with abrupt left hemiparesis
this patient with oat cell carcinoma of the lung prescnted with new onset seizure.
Imaging modalities (MRI)
• Conventional T1WI/T2WI are not sensitive to blood in hyper acute stage
• GRE MRI sequences are as accurate as CT for detection of IPH(Kidwell CS, Chalela JA, Saver JL, et al. Comparison of MRI and CT for detection of acute intracerebral hemorrhage. JAMA 2004;292: 1823–30.)
• Better than CT in detecting underlying structural abnormalities
• The MR signals are determined by• Paramagnetic effects• Pulse sequence • Hb content
• 5 phases• Hyperacute • Acute • Early subacute • Late subacute • Chronic
Oxy Hb —-> Deoxy Hb —-> Met Hb, hemosideren
Oxy Hb De Hb Met Hb Hemosidderen
DiamagneticHigh H2O
Paramagnetic
Paramagnetic
Paramagnetic
T1 Isointense Isointense Hyperintense Isointense
T2 Hyperintense
Hypointense
IC: Hypointens
eEC:
Hyperintense
Hypointense
Case courtesy of Dr Frank Gaillard, radiopaedia.org
Hyperacute hematoma: In this image , it can be observed on sagittal T1-weighted MR a isointense hematoma and axial T2-weighted MR the hematoma is hyperintense. It is located in the right cerebellar hemisphere.
HyperacuteBlood extravasate Intact RBCsIC oxy HbDimagneticHigh water content
Acute Hematoma: Sagittal T1-weighted MR shows a isointense hematoma (arrows) surrounded by a hyperintense halo. Axial T2-weighted MR shows a hypointensity. It corresponds to an acute hematoma (8 hours of evolution). There is also another hematoma of different time of evolution.
Acute
Intact hypoxic RBCsDeoxy HbParamagnetic
Early subacute Hematoma: The hematoma is hyperintense on T1-weighted MRI and hypointense on T2-weighted MRI, due to methemoglobin inside intact red blood cells.
Early subacute
Clot retractionMet HbParamagnetic
Late Subacute intracerebral Hematoma: 67 year-old-male. On sagittal T1- weighted and axial T2-weighted MRI a hyperintense intracerebral hematoma is seen, located in the right cerebral hemisphere. Hyperintensity is due to extracellular methemoglobin. (25 days of evolution).
Late subacute
Cell lysisMet HbParamagnetic
Chronic hematoma: Sagittal T1-weighted MRI and axial T2-weighted MRI in the same patient, show a hypointense hematoma in chronic phase (5 months of evolution). There is, also dilatation of the right lateral ventricle due to adjacent parenchymal atrophy
Chronic
MacrophagesHemosiderinSuperpaeamagnetic
Practical approach• Hyperintensity in T1WI automatically classifies
hematoma as subacute• If so, hyper intensity in T2WI places the
hematoma in late subacute• If the hematoma is isointense on T1WI, the nest
step is to identify the presence of conspicuous hypointense rim on T2WI to classify is as chronic
• If hypointense rim is absent and the hematoma is hyperintense, the lesion is clearly hyperacute
• CONTINUUM: Lifelong Learning in Neurology. Neuroimaging. 14(4, Neuroimaging):37-56, August 2008
Subarachnoid hemorrhage
• The subarachnoid space filled with RBCs suspended within CSF
• Could be traumatic or non-traumatic
• Symptoms develop either to bleeding of mass effect
Imaging modalities
• CT• CT is over 90% sensitive with hyper sense blood seen in
SAS and BCs• Difficult to detect if
• Hematocrit is low• Small haemorrhage • Delayed scanning
• ?
• MRI• Difficult to detect by conventional T1WI/T2WI• FLAIR
• CTA• To detect site of vascular malformation
21-YEAR-OLD MAN COLLAPSED IMMEDIATELY AFTER A LINE OF COCAINE
NCCT SHOWS BLOOD IN THE INTERRHEMISPHCRIC FISSURE AND IN THE DEPENDENT PORTIONS OF THE
LATERAL VENTRICLES.
Lateral view from a digitalsubtractionangiogramdemonstratesalargeanteriorcommunic
atingarte.ryaneurysm(arrow).Ovuhalfofdrugabusers with intracra.ni.al hemorrhage will be found to have an underlying
aneurysm or arteriovenous malformation
Subarachnoid hemorrhage, unenhanced CT scans. Subarachnoid hemorrhage is frequently the result of a ruptured aneurysm. Blood may be most easily visualized within the basal cisterns (solid white arrows in A), in the fissures (dotted white arrows in B), and interdigitated in the subarachnoid spaces of the sulci (dashed white arrow in C). The region of the falx may become hyperdense, widened, and irregularly marginated (solid black arrow in C).
SUBARACHNOID HEMORRHAGE
FLAIR IMAGE
Epidural Hematoma
• Results from trauma, associated with skull fracture (95%)
• Arterial in origin, MMA• Temporal or temporoparietal• The underlying brain may be spared• Almost always acute
EPIDURAL HEMATOMAS
• High density, extra axial Lenticular appearance
• Not cross sutures
Subdural hematoma• Occur in subdural space • Caused by traumatic tearing of bridging
veins (deceleration) • 3 stages• Associated with significant brain injury
due to mass effect• No consistence relationship to skull
fracture
Acute
Subacute
Chronic
SUBDURAL HEMATOMAS
• High attenuation semilunar appearance• Can cross sutures
Acute on chronic
Subdural hematomasSUBDURAL HEMATOMAS
Epidural H. Subdural H.• Convex inner margin• Can cross midline• Almost always acute (post traumatic)
• Concave inner margin• Can not cross midline• Almost always acute
Intraventricular Hemorrhage
• Commonly seen in patients with head injury
• Occur by several mechanisms• Risk of obstructive hydrocephalus • On CT, hyperdense material, layering
dependently
Direct extension Retrograde flow
New imaging applications
Conclusion
References • William E, B., Clyde H. (2012). Fundamentals of Diagnostic
Radiology. LWW
• IMAGING OF INTRACRANIAL HEMORRHAGE. Gomez, Camilo R. CONTINUUM: Lifelong Learning in Neurology. 14(4, Neuroimaging):37-56, August 2008
• Imaging of intracranial haemorrhage. Kidwell, Chelsea S et al.. The Lancet Neurology , Volume 7 , Issue 3 , 256 - 267
• Guidelines for the Management of Spontaneous Intracerebral Hemorrhage in Adults: 2007 Update: A Guideline From the American Heart Association/American Stroke Association Stroke Council, High Blood Pressure Research Council, and the Quality of Care and Outcomes in Research Interdisciplinary Working Group: The American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists