3.
Findings and procedure details.
1. Cerebral microbleeds (CMB)
Cerebral microbleeds are observed in various conditions.
Cerebral amyloid angiopathy:
It consists of deposition of amyloid protein within the small and medium sized cerebral arteries which is likely responsible for increased vessel fragility with consequent micro and macro haemorrhages demonstrated on SWI with cortical and subcortical distribution.
Fig. 7
Chronic hyperintensive encephalopathy (HE):
Chronic hyperintensive encephalopathy HE is also characterized by multiple cerebral microbleeds (CMB) which normally are silent.
They are usually discovered both in deep basal ganglia and subcortical white matter.
Fig. 8
2.
Vascular malformations
Arteriovenous malformations are easily displayed with conventional MRI and MR angiography because of their characteristic high flow.
But venous malformations can’t be adequate visualized without contrast as they consist of slow flow and could be entirely missed by conventional imaging techniques.
On the contrary,
SWI are well suited for the visualization of small vessels.
Cavernomas:
They are composed of dilated disorganized vascular channels.
Individuals with cavernous malformations can present with epilepsy focal neurological deficits or acute intracranial haemorrhages.
Fig. 9
Developmental venous anomalies
Abnormal veins that drain normal brain parenchyma.
SWI demonstrates the slow flow and their characteristic stellate appearance.
Fig. 10
Telangiectasia.
Telangiectasia is typically a small lesion.
It is a low-flow vascular malformation with low signal intensity on SWI.
Telangiectasias are found primarily in the pons and may occur sporadically.
SWI is a useful adjunct to conventional MRI in diagnosing telangiectasia.
Fig. 11
3.
Acute stroke
SWI has been demonstrated to be very useful in the acute phase of stroke.
It is very sensitive in the detection of cerebral microbleeds whose early identification is believed to predict haemorragic transformation after thrombolytic treatment.
Fig. 12
SWI is also capable of identifying the acute intravascular clot in the main and distal branches of the cerebral arteries.
Fig. 13
SWI has been demonstrated to be useful in the assessment of tissue viability.
An improved visualization of draining veins,
which is related to increased oxygen extraction,
within areas of impaired perfusion allows the identification of penumbra brain tissue with SWI.
4.
Traumatic brain injuries
Diffuse axonal injury (DAI) is a form of traumatic brain injury,
caused by shearing stress primarily in the white matter.
The extension of axonal injury correlates with poor outcome.
However,
lesions are usually poorly visualized with conventional methods while MRI conventional appearance of hemorrhage is variable,
due to the multiple parameters of haemoglobin and blood cells.
SWI sequences are very sensitive in the detection of DAI lesions.
Fig. 14
5.
Intracranial tumors
Primary brain tumors
The growth of solid tumors such as gliomas,
is dependent on the angiogenesis of pathological vessels.
SWI can provide an assessment of the angioarchitecture of brain tumors,
together with the identification of haemorrhage and calcification. Fig. 15
Secondary brain tumors
SWI is able to demonstrate the presence of haemorrhage on metastases.
SWI also can differentiate the melanin that doesn’t have susceptibility effect from the haemorrhage.
Fig. 16
6.
Neurodegenerative disorder
Iron deposition increases in the brain as a function of age,
in the form of ferritine.
Typical sites include the globus pallidum,
substantia nigra and red and dentate nuclei.
Abnormally elevated iron levels are evident in many neurodegenerative disorders like: Parkinson's disease,
Alzheimer's disease,
Huntington's disease and amyotrophic lateral sclerosis.
Fig. 17
7.
Calcium related diseases
Calcium is commonly found in the brain and may be physiologic or present in a number of conditions like toxoplasmosis,
tuberous sclerosis and Sturge Weber syndrome.
Fig. 18 ,
Fig. 19 and Fig. 20 .
8.
Subarachnoid haemorrhage
Non traumatic subarachnoid haemorrhage is most commonly due to rupture of an aneurysm.
SWI can demonstrate the subarachnoid haemorrhage and the parenchymal and intraventricular extension.
Fig. 21 and Fig. 22 .
9.
Pneumoencephalus
Some studies suggest that SWI might be suitable for monitoring neurosurgical patients recovering from pneumoencephalus that can be easily detected with SWI.
Fig. 23 .
10.
Localization of the subthalamic nucleus
An accurate localization of the subthalamic nucleus can be achieved in the SWI maps at 3.0 Teslas,
allowing safe direct targeting for placement of electrodes in the treatment of Parkinson’s disease.
Fig. 24 .