Aurelie Drier MD, Presenter: Nothing to Disclose

Charlotte Rosso MD, Abstract Co-Author: Nothing to Disclose

Denis Lacroix MD, Abstract Co-Author: Nothing to Disclose

Gurkan Mutlu MD, Abstract Co-Author: Nothing to Disclose

Yves Samson MD, PhD, Abstract Co-Author: Nothing to Disclose

Didier Dormont MD, Abstract Co-Author: Nothing to Disclose

To compare sensitivity and specificity of 1.5- and 3.0-T Diffusion-weighted (DW) magnetic resonance (MR) imaging of hyper acute carotid ischemic stroke lesions

We retrospectively reviewed the DW MR imaging of 108 patients at 1.5-T and 61 at 3.0-T performed in the six first hours of a carotid ischemic stroke onset. Baseline characteristics were not statistically different for both magnetic field-strength for the delay to MRI acquisition (mean: 153 min, p>0,05) and the stroke scale injury (mean NIHSS: 15, p>0,05). Four readers (2 neuroradiologists and 2 stroke neurologists) blinded to clinical data and magnetic field-strength recorded the presence of ischemic lesions on DWI and ADC maps. Sensitivity, specificity and false negative rate were computed for each reader. The final diagnosis of stroke was based on clinical data and MRI obtained within 24 hours after stroke onset.

Sensitivity for DWI decreased from 99,4% at 1.5-T to 92,5% at 3.0-T (p=0,04) and specificity from 97,8% to 84% (p=0,002). False negative rate trends to be lower at 1.5-T: 0,4% at 1.5-T and 6% at 3.0-T (p=0,07). When DWI ADC map is employed, only specificity is significantly lower at 3.0-T (100% *vs. *90,6%, p=0,005).

3.0-T DW MR imaging appears to be less accurate than 1.5-T for acute carotid stroke diagnosis in the first six hours of stroke onset, especially for the lower rate of specificity. Greater susceptibility artifact at high magnetic-field-strength may create small bright hyperintense artifacts leading to false positive diagnosis. ADC map examination is crucial at 3.0-T.

Radiologists should be aware of the potential failure of DWI to reveal ischemic stroke and of the absolute necessity of ADC map examination at 3.0-T.

Drier, A, Rosso, C, Lacroix, D, Mutlu, G, Samson, Y, Dormont, D, Hyper Acute Carotid Ischemic Stroke 1.5 T Diffusion-weighted MR Imaging Superior to 3.0 T DWI.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6017344.html