Brain single-photon emission CT with HMPAO and safety of thrombolytic therapy in acute ischemic stroke. Proceedings of the meeting of the SPECT Safe Thrombolysis Study Collaborators and the members of the Brain Imaging Council of the Society of Nuclear Medicine

Abstract

Background: To reliably identify patients at risk for symptomatic hemorrhagic transformation (SHT), future trials of thrombolysis for acute ischemic stroke might use a vascular imaging protocol applicable to a multicenter setting. The goal of this commentary is to address the safety of intravenous thrombolysis with the recombinant tissue plasminogen activator (rTPA) and potential solutions offered by single-photon emission CT (SPECT) as a noninvasive brain perfusion imaging modality.

Summary of review: Even if patients with severe stroke, extensive ischemic changes on CT scan, advanced age, and high blood pressure are excluded from thrombolytic therapy, this cannot completely guarantee the safety of using rTPA. Brain SPECT scanning with hexamethylpropyleneamine-oxime (HMPAO) may help to screen out patients at risk if performed in addition to clinical and CT tests. The knowledge of pretreatment severity, extent, and location of ischemia might identify good versus poor responders to rTPA therapy. HMPAO-SPECT is widely available and feasible to perform without delaying rTPA therapy. Rigorous quality control and use of reproducible visual and semiquantitative methods of interpreting SPECT are necessary for implementation of SPECT technology in multicenter clinical trials.

Conclusions: The major obstacle to general acceptance of thrombolytic therapies and rTPA in particular is the fear of symptomatic hemorrhagic transformation, and because HMPAO-SPECT might reliably identify patients at high risk of symptomatic hemorrhagic transformation, the clinical value of HMPAO-SPECT in patient selection for thrombolysis during the first hours of acute ischemic stroke should be determined through a prospective clinical trial.