The early findings from a case report have highlighted the potential held by 3D black blood vessel wall post-contrast imaging to predict the outcomes of reperfusion therapy for distal vessel occlusion (DVO)—although the report’s authors also state that a larger study will now be required to verify these early findings.
The report was published in the Journal of Cardiovascular, Neurovascular and Stroke (CVNS) by radiologist Mohd Fandi Al Khafiz Kamis (University Putra Malaysia [UPM] Teaching Hospital, Selangor, Malaysia) and other researchers from the UPM Department of Radiology.
In discussing these early findings, Kamis et al write: “Detection of intra-arterial thrombus in DVO is becoming increasingly important in acute stroke imaging. The evolution of medical devices for mechanical thrombectomy has allowed the smaller distal vessels to be treated via an endovascular approach. It is also useful to reassess vascular patency after the administration of thrombolysis agents. Large vessel occlusion [LVO] is undisputedly a known cause for disability in acute stroke, but DVO in an eloquent area of a specific branch can potentially lead to a significant neurological deficit.
“Advances in magnetic resonance imaging [MRI] allow detection of intra-arterial thrombus via 3D black blood vessel wall imaging. Our case demonstrates reperfusion of the affected vessel at five days after thrombolysis—evidenced by resolution of the previously-noted peri-thrombus vascular hyperintensity sign [PVHS] and intraluminal enhancement. Restoration of arterial flow suppression on 3D black blood imaging supports these findings.”
According to the report, direct visualisation of intra-arterial thrombus in acute ischaemic stroke is widely assessed, in LVO, through a hyperdense middle cerebral artery (MCA) sign on a computed tomography (CT) scan, or via a blooming artifact on a gradient echo MRI sequence. And, while the sensitivity of these signs is not as reliable in smaller DVO, the emergence of 3D black blood contrast-enhanced MRI enables clinicians to visualise the distal vessel wall and intraluminal features, and subsequently narrow down the differential cause of ischaemia and possible biomarkers to monitor reperfusion therapy responses.
The case reported by Kamis et al involved a 37-year-old male chronic smoker who had fallen in the bathroom and subsequently developed dysarthria and receptive aphasia. The patient’s premorbid Modified Rankin Score (MRS) was zero, with no known underlying diseases. Their National Institutes of Health Stroke Scale (NIHSS) score was found to be six, and language and speech were the most-affected components, with no limb weakness or other neurological deficits being found. The case report also notes that an electrocardiogram (ECG) revealed atrial fibrillation (AF) as well.
An MRI scan was performed within two hours of symptom onset in the patient, and showed restricted diffusion at the left parietal lobe and diffusion-weighted imaging with mismatch on fluid attenuation inversion recovery (FLAIR). Cortical enhancement was also noted at the MCA-PCA (posterior cerebral artery) watershed region, which the report states was suggestive of subacute infarct—explaining the cardioembolic origin of the stroke, secondary to undiagnosed AF. A time-of-flight magnetic resonance angiography (MRA) also revealed an absent flow signal in the affected cortical artery. The report details how a 3D black blood post-contrast MRI showed interface between PVHS and intraluminal enhancement of the affected cortical branch of the left MCA.
Thrombolysis with 0.9mg of alteplase per kilogram total of bolus, and one-hour infusion, was then conducted in the patient. The report details that their immediate, post-thrombolysis NIHSS score was static, but that an improvement in this score, from six to two, was noted eight hours after the procedure. Dual antiplatelet therapy was started on day five from the patient’s symptom onset and, prior to discharge, their NIHSS score further improved to one—leaving “only mild sensory components affected”. Repeated 3D black blood MRI five days after the acute event also showed a luminal patency in the affected cortical vessel that was “indicative of a good response towards reperfusion therapy”.
In concluding the case report, Kamis et al state that the vessel wall imaging features observed here, followed by a “vast clinical improvement” after thrombolysis, highlights the potential of 3D black blood post-contrast imaging to predict the outcome of reperfusion therapy for DVO, but that a larger study “is needed to verify these early findings”.