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Neurology India
Medknow Publications on behalf of the Neurological Society of India
ISSN: 0028-3886 EISSN: 1998-4022
Vol. 58, Num. 4, 2010, pp. 620-621

Neurology India, Vol. 58, No. 4, July-August, 2010, pp. 620-621

Topic of the Issue: Neuroimage

Middle cerebral artery susceptibility sign and venous prominence in acute ischemic stroke

Yen Ju-Chun, Lai Yen-Jun, Chan Lung

Section of Neurology, Department of Internal Medicine, Far-Eastern Memorial Hospital, Taipei

Correspondence Address:Section of Neurology, Department of Internal Medicine, Far-Eastern Memorial Hospital, Taipei County, cjustinmd@yahoo.com.tw

Date of Acceptance: 09-Oct-2010

Code Number: ni10163

PMID: 20739807

DOI: 10.4103/0028-3886.68672

A 44-year-old man visited neurology clinic for slurred speech and gait disturbance of 4 days duration. Brain magnetic resonance image (MRI) showed subacute infarction in the right middle cerebral artery (MCA) watershed territory [Figure - 1]a. MR-angiography (MRA) showed truncation of right MCA indicating right MCA occlusion [Figure - 1]b. MR perfusion study revealed prolongation of mean transit time in the right MCA territory with decreased relative cerebral blood flow and relative cerebral blood volume [Figure - 1]c and d. Susceptibility-weighted imaging (SWI) demonstrated focal hypointensity in the right M1 segment of the MCA representing a thrombus [Figure - 2]a. Accentuation of cortical venous hypointensities in the right cerebral hemisphere suggested a relative increase of deoxyhemoglobin in the draining veins within the acute ischemic region [Figure - 2]b.

Deoxygenated hemoglobin is paramagnetic in SWI with a hypointensity signal. The oxygenated hemoglobin is of lesser paramagnetic effect, and is iso- or hyperintense on SWI. [1] In acute thrombotic or thromboembolic stroke, decreased arterial blood flow will cause an increase in the amount of deoxyhemoglobin and deoxygenated blood pooling in tissue capillaries and draining veins. SWI will show a hypointensity signal of the cortical veins in the areas of impaired brain perfusion. [1] Furthermore, blood clots in the vessels contain high concentration of deoxyhemoglobin, which will present as a hypointensity on SWI. [2],[3] SWI is a very powerful tool in localization of the arterial occlusion and thromboembolus, even in the distal branches of cerebral arteries. [3]

References

1.Hermier M, Nighoghossian N. Contribution of susceptibility-weighted imaging to acute stroke assessment. Stroke 2004;35:1989-94.  Back to cited text no. 1  [PUBMED]  [FULLTEXT]
2.Mittal S, Wu Z, Neelavalli J, Haacke EM. Susceptibility-weighted Imaging: Technical aspects and clinical applications, Part 2. AJNR Am J Neuroradiol 2009;30:232-52.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Santhosh K, Kesavadas C. Susceptibility-weighted imaging: a new tool in magnetic resonance imaging of stroke. Clin Radiol 2009;64:74-83.  Back to cited text no. 3    

Copyright 2010 - Neurology India

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[ni10163f1.jpg] [ni10163f2.jpg]
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