DWI Reversibility after Intra-Arterial Thrombolysis. A Case Report and Literature Review

[Diffusion-weighted imaging hyperintensity is reversible in large middle cerebral artery infarction following thrombectomy:a case report]

Diffusion-weighted imaging (DWI) is currently the most sensitive technique to diagnose early ischemic stroke. DWI signal hyperintensity is usually considered to suggest irreversible infarct core, but recent studies demonstrated that DWI hyperintensity signal could be reversible on small embolic lesions. Herein we present a case in a 63-year-old male patient, who was admitted to the emergency department with altered mental status and complaint of weakness in the left arm and leg 6.8 h prior to the admission. Emergency cranial magnetic resonance imaging (MRI) and angiography (MRA) revealed occlusion of his right middle cerebral artery (MCA) and large lesions on DWI. The patient underwent intra-artery thrombectomy after evaluation in spite of the large volume of the DWI lesions up to 91.5 mL at the baseline. His right MCA was recanalized at 8.5 h from symptom onset. One week after the procedure, the patient showed reduced DWI lesion volume to 11.58 mL. In this case we observed the reversibility of a large lesion of the anterior artery circulation presenting with hyperintensity on DWI, suggesting that the clinical implication of DWI hyperintensity should be interpreted with caution, and a large volume of baseline DWI hyperintensity may not be a contraindication to thrombectomy. This conclusion, however, awaits further validation by future large-scale randomized controlled trials.

Impact of infarct location on functional outcome following endovascular therapy for stroke

OBJECTIVES

The relationship between stroke topography (ie, the regions damaged by the infarct) and functional outcome can aid clinicians in their decision-making at the acute and later stages. However, the side (left or right) of the stroke may also influence the identification of clinically relevant regions. We sought to determine which brain regions are associated with good functional outcome at 3 months in patients with left-sided and right-sided stroke treated by endovascular treatment using the diffusion-weighted imaging-Alberta Stroke Program Early CT Score (DWI-ASPECTS).

METHODS

Patients with ischaemic stroke (n = 405) were included from the ASTER trial and Pitié-Salpêtrière registry. Blinded readers rated ASPECTS on day 1 DWI. Stepwise logistic regression analyses were performed to identify the regions related to 3-month outcome in left (n = 190) and right (n = 215) sided strokes with the modified Rankin scale (0-2) as a binary independent variable and with the 10 regions-of-interest of the DWI-ASPECTS as independent variables.

RESULTS

Median National Institute of Health Stroke Scale (NIHSS) at baseline was 17 (IQR: 12-20), median age was 70 years (IQR: 58-80) and median day-one NIHSS 9 (IQR: 4-18). Not all brain regions have the same weight in predicting good outcome at 3 months; moreover, these regions depend on the affected hemisphere. In left-sided strokes, the multivariate analysis revealed that preservation of the caudate nucleus, the internal capsule and the cortical M5 region were independent predictors of good outcome. In right-sided strokes, the cortical M3 and M6 regions were found to be clinically relevant.

CONCLUSION

Cortical non-motors areas related to outcome differed between left-sided and right-sided strokes. This difference might reflect the specialisation of the dominant and non-dominant hemispheres for language and attention, respectively. These results may influence decision-making at the acute and later stages.

TRIAL REGISTRATION NUMBER

NCT02523261.

Role of Diffusion-weighted Imaging in Acute Stroke Management using Low-field Magnetic Resonance Imaging in Resource-limited Settings

A variety of imaging modalities exist for the diagnosis of stroke. Several studies have been carried out to ascertain their contribution to the management of acute stroke and to compare the benefits and limitations of each modality. Diffusion-weighted imaging (DWI) has been described as the optimal imaging technique for diagnosing acute ischemic stroke, yet limited evidence is available on the value of DWI in the management of ischemic stroke with low-field magnetic resonance (MR) systems. Although high-field MR imaging (MRI) is desirable for DWI, low-field scanners provide an acceptable clinical compromise which is of importance to developing countries posed with the challenge of limited availability of high-field units. The purpose of this paper was to systematically review the literature on the usefulness of DWI in acute stroke management with low-field MRI scanners and present the experience in Nigeria.

ASFNR recommendations for clinical performance of MR dynamic susceptibility contrast perfusion imaging of the brain

MR perfusion imaging is becoming an increasingly common means of evaluating a variety of cerebral pathologies, including tumors and ischemia. In particular, there has been great interest in the use of MR perfusion imaging for both assessing brain tumor grade and for monitoring for tumor recurrence in previously treated patients. Of the various techniques devised for evaluating cerebral perfusion imaging, the dynamic susceptibility contrast method has been employed most widely among clinical MR imaging practitioners. However, when implementing DSC MR perfusion imaging in a contemporary radiology practice, a neuroradiologist is confronted with a large number of decisions. These include choices surrounding appropriate patient selection, scan-acquisition parameters, data-postprocessing methods, image interpretation, and reporting. Throughout the imaging literature, there is conflicting advice on these issues. In an effort to provide guidance to neuroradiologists struggling to implement DSC perfusion imaging in their MR imaging practice, the Clinical Practice Committee of the American Society of Functional Neuroradiology has provided the following recommendations. This guidance is based on review of the literature coupled with the practice experience of the authors. While the ASFNR acknowledges that alternate means of carrying out DSC perfusion imaging may yield clinically acceptable results, the following recommendations should provide a framework for achieving routine success in this complicated-but-rewarding aspect of neuroradiology MR imaging practice.