Brain hemorrhage Vs infarction in CT and MRI

Thamir Diab Alotaify4th year – medical student

NBU – medical college

Objectives

• Types of cerebral strokes and etiology• CT and MRI in cerebral hemorrhage • CT and MRI in cerebral infarction • 4-min Vedio for learning purpose• Conclusion

Intracrainial hemorrhage

Def / active bleeding inside the cranial cavity Types :- Epideural - Subdeural - Subarachnoid - Intracerebral (intraparnchymal)- Intraventricular

Etiology

• Generally most common cause of ICHs are traumatic causes

• And the most common cause of such traumas are RTAs

• Always it is nessery to evaluate the head and neck after RTAs

Clinically +++ radiologically Even if the patient is Asymptomaic(lucid interval )

CT and MRI in ICH • CT scan is the modality of choice in traumatic head

injuries ( in ER)• Why ? - Rapid - It can shows the bone status - It can detect the early onset of hemorrhge • So the CT good for 3 Bs -Blood -Brain -Bone

Stages of brain hemorrhage in CT

• Acute : hyperdense • Sub acute : isodense • Chronic : hypodense

CT appearance of hemorrhage. Serial CT scansof right thalamic hematoma. (A) Acute ICH in theright thalamus with mean attenuation 65 HU. (B) CTperformed 8 days later than (A); the periphery ofthe hematoma is now isodense to the brain whilethe center of the hematoma has mean attenuation45 HU. (C) CT performed 13 days later than (A) showscontinued evolution of the hematoma with decreasingattenuation. (D) CT performed 5 months laterthan (A) shows a small area of encephalomalacia in

ICH in MRI

• MRI is not a best choice for urgent diagnosis , it takes time and may be not available , and not good for bone status (not usefull in acute head injury )

• But it is the best modality for brain paranchymal assessment ( infarcts, demyelinatind dis , Tumors )

Brain infarction • Def/ necrosis of brain tissue due to many causes• types : (global , focal)• Most common cause : ischemia• Other causes : - Metabolic : hypoglycemia - Toxic : drugs • Cerebral infarction it can be detected in both CT & MRI • CT may appear normal in hyperacute state ( <3h)• MRI can detect small infarction at the moment

Cerebral infarction on CT• Hyperacute : before 3houres of onset ..normal• Early acute (4-6) :- Dense MCA sign - Obscuration of the lenticular nucleus - insular ribbon Sign• Late acute : - Low density basalganglia- sulcal effacement• Subacute :- Increasing mass effect- Wedge-shaped low density area involving gray and white matter- Possible hemorrhagic transformation

Chronic : (>3days)

-Well demarcated hypodensity Simillar density to CSF--ve mass effect (pulled midline)-Dilataion of ventricles (Encephalomalacia )

Early acute (3-6 )

MCA sign

Subacute cerebral infarction

Marked ill defined hypodense area involving most of the RT cerebral hemisphere and shifting the midline

Chronic cerebral infarction

Massive Hypodense area in LT cerebral hemispherSimillar density of CSF + ipsilateral widening of lateral ventricle

Cerebral infarction in MRI +ve DWI

Imaging Findings of Stroke:

• MR imaging of the brain is far more sensitive than CT imaging to recognize acute infarction.

• Diffusion wtd. pulse sequence (DW imaging) is the most sensitive MR sequence to demonstrate stroke. This sequence is sensitive to restricted diffusion within the cell from stroke-induced cytotoxic edema and the region of acute stroke is seen as an area of bright signal on DWI Cytotoxic edema can occur immediately after the initial insult thus DWI images can reveal, the area of acute infarct immediately after the insult.

• Intravascular contrast enhancement, another sign of early stroke (Figure 1f).

• Sulcal effacement, gyral edema (Fig. 5b), loss of gray-white matter interface can occur within 12 hours of stroke.

• Parenchymal contrast enhancement (Fig. 6d), mass effect (Fig. 4b) and hemorrhage can occur within 1-7 days of insult.

Subacute infarct: (1 week to 8 weeks)

•Focal area of encephalomalacia•Porencephalic dilatation of adjacent ventricle.• Residual old blood products may be present.

Old Infarct:

• Contrast enhancement slowly decreases in time but can persist for 8 weeks, with decreasing mass effect and abnormal signal intensity:

Acute Stroke (up to 7 days)

conclusion

• There are sequence of events in cerebral strokes :

- Hyperacute- Acute - Subacute - Chronic • CT is best for hemorrhagic • MRI is best to detect the ischemic at the onset