Large percent of posterior circulation strokes missed by acute MRI; however tpa does not usually resolve diffusion deficits on MRI

Hotter B, Kufner A, Malzahn U. et al.  Validity of negative high resolution diffusion weighted imaging in transient cerebrovascular events.  Stroke 2013; 44:2598-2600

 

151 patients with suspected stroke and negative DWI in first twenty four hours , 63 underwent followup MRI showing stroke in seven (11%).  5/7 had at least one point on NIHSS. 

 

Oppenheim C, Stanescu R, Dormont D, et al.  False negative diffusion weighted MR findings in acute ischemic stroke.  AJNR 2000; 21: 1434-1440

 

older study showing miss rate of about 20 %

 

Schellinger PD, Bryan RN, Caplan LR et al.  Evidence -based guideline: the role of diffusion and perfusion MRI for the diagnosis of acute ischemic stroke: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology; 2010; 75:177-185.

 

guideline from AAN cautioning that sensitivity of MRI to diagnose stroke is imperfect.

 

Albach FN, Brunecker P, Usnich T, et al.  Complete early reversal of diffusion weighted imaging hyperintensities after ischemic stroke is mainly limited to small embolic lesions.  Stroke 2013; 44:1043-1048

Authors studied 153 patients with an average NIHSS of 4 who received tpa; and underwent MRI on admission and in subsequent week.  97/611 (16%) of MRI diffusion hyperintensities resolved, but only 2 % of patients had ALL of their diffusion abnormalities resolve after receiving tpa.