Magnetic resonance imaging features and stroke etiology of ischemic stroke in essential thrombocythemia

Various essential thrombocythemia (ET)-related stroke mechanisms have been proposed, including microcirculatory disturbance due to coagulopathy, vasculitis, and embolism due to thrombus formation in large vessels. However, the stroke mechanism in ET remains largely unexplored. The purpose of this study was to evaluate magnetic resonance image (MRI) features of ischemic stroke in ET and determine the potential stroke mechanism.

We retrospectively collected data from 21 acute ischemic stroke patients with ET who were admitted to two stroke centers between 2010 and 2023. ET was diagnosed according to the World Health Organization criteria. We evaluated MRI features including the diffusion-weighted image (DWI) lesion pattern, and the presence of hemorrhagic transformation and intracranial artery steno-occlusive lesion, as well as other etiological workup results.

Of 21 patients, 20 exhibited multiple ischemic lesions on DWI, mainly within a single vascular territory. Cortical infarcts were observed in 19 patients. Hemorrhagic transformation occurred in 15 patients. Additionally, 15 patients had intracranial steno-occlusive arteries, which regressed to normal in 11 patients during follow-up. Out of all patients, only 2 had potential causes of stroke other than ET (1 with atrial fibrillation and 1 with intracranial atherosclerotic stenosis). The remaining 19 patients had ET as the only identified potential cause.

MRI features, including DWI lesion pattern in ischemic stroke patients with ET, suggested embolic etiology despite the absence of major embolic sources. Intra-arterial thrombus appears to be part of the stroke mechanism related to ET and may contribute to ischemic stroke in ET.