Monday 4 April 2016

?DSA ---VENOUS INFARCT

Q.All are true regarding imaging of venous infarcts except
a. a venous sinus  appear expanded and hyperdense on NECT
b. more intense enhancement of the walls of the sinuses than of its contents on CECT
c. spin-echo images is usually acquired to diagnose
d. CT venography is a satisfactory alternative in case of  equivocal MRV
e. very little need to resort to DSA to confirm the diagnosis of venous thrombosis
ANS .----c

MRI shows lack of flow void in the affected sinuses but normal slow flowing blood may appear bright, simulating a thrombus and acute thrombus can appear hypointense on spin-echo images mimicking a flow void . Therefore structural MRI is not always reliable for the exclusion of venous occlusion, particularly if chronic, and a phase-contrast MR venogram (MRV) is usually acquired, which depicts only flow and not thrombus. A low-velocity encoding (VENC) is chosen to demonstrate venous flow. CT venography is a satisfactory alternative if MRV is unavailable or equivocal. Using a combination of structural images, MR and CT venography, there is very little need to resort to DSA to confirm the diagnosis of venous thrombosis.

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