Haemorrhagic infarct with T2 blackout

Case contributed by A.Prof Frank Gaillard

Presentation

Right hemiplegia and aphasia three days ago.

Patient Data

Age: 85 years
Gender: Male

Middle cerebral artery territory petechial haemorrhagic infarct. 

The patient had presented early with an ischaemic stroke, and underwent successful endovascular clot retrieval and recanalization 3 days prior to the CT shown above. 

Selected images demonstrating a large left MCA distribution infarct with a large area of low signal on DWI and ADC imaging in keeping with associated petechial cortical haemorrhage. Loss of signal on DWI is due to T2 blackout, best seen on B=0 (GE EPI) image, which is of course a T2* weighted image and thus suffers from significant signal loss due to blood products. 

Case Discussion

T2 blackout is essentially the opposite effect to T2 shine through, namely the extremely low signal on T2* images results in loss of signal on DWI and ADC. This clearly does not reflect actual diffusion characteristics of the tissue. 

With no signal in a voxel on B=0 images, the DWI value will also be 0 (black) and ADC will be undefined (manipulating the DWI equation with B=0 results in a natural logarithm of 0/0, which is undefined - twice in fact). 

 

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Case information

rID: 46059
Case created: 20th Jun 2016
Last edited: 22nd Jun 2016
Inclusion in quiz mode: Included

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