(577) MRI Tractography and Benzodiazepine SPECT Neuroimaging to Predict Outcome After Reperfusion Therapy

Introduction: Intravenous thrombolysis and mechanical thrombectomy are the first-line treatments for acute ischemic stroke. However, successful recanalization or reperfusion does not always lead to favorable functional outcomes. We describe the utility of the combined application of diffusion magnetic resonance imaging (MRI) fiber tractography and 123I-iomazenil benzodiazepine receptor single-photon emission computed tomography to predict long-term impairment associated with neural networks and cellular viability in the arcuate fasciculus in aphasia and related disabilities.

Description: 81-year-old man was admitted to the hospital approximately 3.5 hours after the onset of symptoms including decreased consciousness, right hemiparesis, and aphasia. Brain MRI revealed infarct lesions in the left middle cerebral artery territory due to M1 segment occlusion. Intravenous alteplase thrombolysis followed by endovascular thrombectomy resulted in complete recanalization and revascularization of the left middle cerebral artery territory. Subsequent MRI showed no new ischemic or hemorrhagic lesions. Although the patient’s motor hemiparesis gradually recovered over the following 3 weeks, motor aphasia and apraxia with cognitive deficits persisted. Diffusion MRI fiber tractography performed 3 weeks after admission revealed partial injury to the left arcuate fasciculus indicated by fractional anisotropy values lower than those of the contralateral side. This was accompanied by decreased benzodiazepine receptor density, which suggested matched hypoperfusion-hypometabolism in the left perisylvian and temporoparietal cortices. The patient showed no clear signs of further improvement in the chronic stage post-stroke and was discharged to a nursing home after 3 months.

Discussion: A combination of functional neuroimaging techniques to assess neuronal damage to the left arcuate fasciculus may allow for more accurate prognosis of long-term recovery or disability due to aphasia and apraxia following acute reperfusion therapy.