Peggy Nguyen, MD
Goyal MS, Hoff BG, Williams J, Khoury N, Wiesehan R, Heitsch L, et al. Streamlined Hyperacute Magnetic Resonance Imaging Protocol Identifies Tissue-Type Plasminogen Activator–Eligible Stroke Patients When Clinical Impression Is Stroke Mimic. Stroke. 2016
Despite advances in imaging, the radiologic component of the tPA decision-making is predicated on a non-contrast CT head, guided by the clinical history and exam. Sometimes, however, the clinical exam or history can be confusing and the CT scan does not provide much additional diagnostic data; stroke mimics make up anywhere between 1-16% of the patients presenting with stroke-like symptoms at large institutions. The use of a hyperacute MRI (hMRI) can help differentiate strokes from stroke mimics, and potentially minimize tPA given to mimics and, perhaps more importantly, ensure that tPA is not withheld from patients who are suspected to be mimics, but are actually strokes.
Here, the authors report an institution-specific streamlined hMRI protocol in the setting of acute stroke. The hMRI protocol described here provides DWI/ADC, FLAIR, and T2*GRE sequences in just under 6 minutes. In order to avoid overutilization, physicians were instructed to order the hMRI only when the initial diagnostic impression was likely stroke mimic, but ischemic stroke could not be entirely ruled out and, if MRI was not available at their institution, the physician would not give the patient tPA. 57 patients, identified as stroke mimics, underwent the hMRI protocol, with 11 having the final diagnosis of stroke, 4 with the final diagnosis of TIA, and the remaining diagnoses being conversion disorder, seizure, complicated migraine, and other. Seven of the 11 stroke patients received IV tPA. There were no differences in door-to-needle, onset-to-needle, or door-to-arrival times for all IV tPA treated patients pre- and post-hMRI; however, the door-to-needle time for tPA treated patients screened with CT alone were significantly shorter than the 7 tPA patients screened with hMRI (37 minutes vs 112 minutes).
Although the overall metrics (door to needle, onset to needle, etc) did not change much with the institution of hMRI protocol, likely due to the minority of patients who went on to receive tPA under the protocol, using the hMRI protocol did lead to substantially longer door-to-needle times for patients who received tPA. However, longer door-to-needle times are preferable than withholding tPA, and it is probable that these patients, having been initially identified as stroke mimics, would not have received tPA otherwise. The use of a hMRI does have its limitations, given it is not widely available and many institutions may not have the resources to staff it emergently, but in institutions where the resources are available, it could potentially increase tPA usage to patients with strokes and decrease tPA usage to patients without strokes.