Abstract
Purpose: The hyperintense acute reperfusion marker (HARM) is characterized by the delayed enhancement of the subarachnoid or subpial space observed on postcontrast fluid-attenuated inversion recovery (FLAIR) images, and is considered a cerebral reperfusion marker for various brain disorders, including infarction. In this study, we evaluated the cerebral distribution patterns of HARM for discriminating between an enhancing subacute infarction and an enhancing mass located in the cortex and subcortical white matter. Materials and methods: We analyzed consecutive patients who experienced a subacute ischemic stroke, were hospitalized, and underwent conventional brain magnetic resonance imaging including postcontrast FLAIR within 14 days from symptom onset, as well as those who had lesions corresponding to a clinical sign detected by diffusion-weighted imaging and postcontrast T1-weighted imaging between May 2019 and May 2021. A total of 199 patients were included in the study. Of them, 94 were finally included in the subacute infarction group. During the same period, 76 enhancing masses located in the cortex or subcortical white matter, which were subcategorized as metastasis, malignant glioma, and lymphoma, were analyzed. We analyzed the overall incidence of HARM in subacute ischemic stroke cases, and compared the enhancement patterns between cortical infarctions and cortical masses. Results: Among 94 patients with subacute stroke, 78 patients (83%) presented HARM, and among 76 patients with subcortical masses, 48 patients (63%) presented peripheral rim enhancement. Of 170 subcortical enhancing lesions, 88 (51.8%) showed HARM, and 78 (88.6%) were determined to be subacute infarction. Among 94 patients with subacute stroke, 48 patients (51%) had diffusion restrictions, and HARM was found in 39 patients (81.2%). Of the 46 patients (49%) without diffusion restriction, 39 patients (84.8%) showed HARM. Conclusions: The presence of HARM was significantly associated with subacute infarctions. For the masses, a peripheral rim enhancement pattern was observed around the mass rather than the cerebral sulci on postcontrast FLAIR.
Highlights
The evaluation of patients visiting the hospital with neurologic symptoms during the subacute period is important in determining the direction of treatment
We demonstrated the clinical significance of hyperintense acute reperfusion marker (HARM) in differentiating subacute infarction from other subcortical enhancing masses
The presence of HARM was significantly associated with subacute infarction, and a peripheral rim enhancement pattern was observed around the mass on postcontrast fluid-attenuated inversion recovery (FLAIR)
Summary
The evaluation of patients visiting the hospital with neurologic symptoms during the subacute period is important in determining the direction of treatment. The hyperintense acute reperfusion marker (HARM) is characterized as the delayed contrast enhancement of the subarachnoid or subpial space on postcontrast FLAIR images in various intracranial pathologic conditions, and is believed to be associated with permeability changes in the BBB. Despite the success of MRI in evaluating acute ischemia, the differential diagnosis of nodular enhancing lesions in the cortical and subcortical areas often remains challenging. The discrimination between a true ischemic stroke and other conditions, including malignant primary CNS tumor or metastasis, is essential for planning adequate treatment, and estimating outcomes and future diagnosis. We evaluated the usefulness of HARM in differentiating mass-like enhancing subacute infarction from malignant lesions for cortical and subcortical enhancing nodular lesions on postcontrast T1WI. We hypothesized that a linear contrast enhancement pattern along the subpial and subarachnoid space adjacent to the enhancing nodular lesion on postcontrast FLAIR images suggests infarction rather than malignant lesions
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