Follow-up Diffusion-weighted MRI Research Articles

A Detailed Analysis of Infarct Patterns and Volumes at 24-hour Noncontrast CT and Diffusion-weighted MRI in Acute Ischemic Stroke Due to Large Vessel Occlusion: Results from the ESCAPE-NA1 Trial.

Background The effect of infarct pattern on functional outcome in acute ischemic stroke is incompletely understood. Purpose To investigate the association of qualitative and quantitative infarct variables at 24-hour follow-up noncontrast CT and diffusion-weighted MRI with 90-day clinical outcome. Materials and Methods The Safety and Efficacy of Nerinetide in Subjects Undergoing Endovascular Thrombectomy for Stroke, or ESCAPE-NA1, randomized controlled trial enrolled patients with large-vessel-occlusion stroke undergoing mechanical thrombectomy from March 1, 2017, to August 12, 2019. In this post hoc analysis of the trial, qualitative infarct variables (predominantly gray [vs gray and white] matter involvement, corticospinal tract involvement, infarct structure [scattered vs territorial]) and total infarct volume were assessed at 24-hour follow-up noncontrast CT or diffusion-weighted MRI. White and gray matter infarct volumes were assessed in patients by using follow-up diffusion-weighted MRI. Infarct variables were compared between patients with and those without good outcome, defined as a modified Rankin Scale score of 0-2 at 90 days. The association of infarct variables with good outcome was determined with use of multivariable logistic regression. Separate regression models were used to report effect size estimates with adjustment for total infarct volume. Results Qualitative infarct variables were assessed in 1026 patients (mean age ± standard deviation, 69 years ± 13; 522 men) and quantitative infarct variables were assessed in a subgroup of 358 of 1026 patients (mean age, 67 years ± 13; 190 women). Patients with gray and white matter involvement (odds ratio [OR] after multivariable adjustment, 0.19; 95% CI: 0.14, 0.25; P < .001), corticospinal tract involvement (OR after multivariable adjustment, 0.06; 95% CI: 0.04, 0.10; P < .001), and territorial infarcts (OR after multivariable adjustment, 0.22; 95% CI: 0.14, 0.32; P < .001) were less likely to achieve good outcome, independent of total infarct volume. Conclusion Infarct confinement to the gray matter, corticospinal tract sparing, and scattered infarct structure at 24-hour noncontrast CT and diffusion-weighted MRI were highly predictive of good 90-day clinical outcome, independent of total infarct volume. Clinical trial registration no. NCT02930018 © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Mossa-Basha in this issue.

Thalamic Hyperintensity on Diffusion-Weighted MRI in a Patient with Nonconvulsive Status Epilepticus

We present a 70-year-old woman with nonconvulsive status epilepticus (NCSE) with thalamic hyperintensity on diffusion-weighted MRI (DWI). She had no previous history of epilepsy. Her altered mentality was not normalized though we successfully controlled the ictal activity by standard treatment. Initial DWI showed diffuse hyperintensity in the right thalamus, which raised the possibility of seizure-related change. At the follow-up DWI, more localized high signal intensity lesion was present in the right pulvinar area. There was no apparent cause of her NCSE despite our extensive work-ups. The authors suggest that transient ischemia is a possible causative pathomechanism in this case.

Is Aortic Atherothrombotic Disease Detected Using Multidetector-Row CT Associated With an Increased Risk of Early Ischemic Lesion Recurrence After Acute Ischemic Stroke?

Multidetector-row CT (MDCT) is emerging as a new tool for diagnosing aortic atherothrombotic disease (AAD). We elucidated whether MDCT-detected AAD is associated with an increased risk of early ischemic lesion recurrence on diffusion-weighted MRI after ischemic stroke. A consecutive series of patients with acute ischemic stroke confirmed using diffusion-weighted MRI who were hospitalized within 48 hours after symptom onset and underwent MDCT were identified in a prospective stroke registry database. AAD on MDCT was defined as the presence of plaque formation that was noncalcified and ≥4 mm thick, ulcerative, or soft and thrombosed (vulnerable) in the proximal aortic arch. Ischemic lesion recurrence on diffusion-weighted MRI was defined as the occurrence of any new lesion separate from the index lesion on follow-up diffusion-weighted MRI performed within 14 days after symptom onset. A total of 138 patients was selected. MDCT detected AAD in 24 of 138 (17.4%); ≥4 mm thickness in 17 of 138 (12.3%); ulcerated plaque in 20 of 138 (14.5%); and vulnerable plaque in 16 of 138 (11.6%). With respect to diffusion-weighted MRI lesion recurrence, the crude ORs (95% CIs) were as follows: AAD, 3.56 (1.43-8.89); vulnerable plaque, 3.21 (1.11-9.30); ulcerated plaque, 3.37 (1.27-8.95); and ≥4 mm thickness of the noncalcified plaque, 4.23 (1.11-16.19). These results remained significant after adjustments for potential confounders were made. This study shows that AAD detected by MDCT increases the risk of early ischemic lesion recurrence after acute ischemic stroke, thus supporting the role of MDCT in diagnosing AAD and assessing its contribution to recurrence.

Post-Interventional Microembolism: Cortical Border Zone Is a Preferential Site for Ischemia

Background: Previous diffusion-weighted MRI (DWI) studies have indicated that 10–40% of patients have silent embolism during neurointerventional procedures. However, lesion patterns of the embolisms have not been adequately investigated. Methods: DWI was taken within 7 days before and 48 h after cerebral angioplasty and stent procedures. New lesions on the follow-up DWI were analyzed in the non-treated arterial territories. Based on the arterial territories, supratentorial lesions were classified into cortical lesions and subcortical lesions. Cortical lesions were subdivided into cortical border zone and cortical proper lesions. Subcortical lesions were divided into deep perforator and internal border zone lesions. Infratentorial lesions were divided into brainstem and cerebellar lesions. Results: 72 patients were included in this study. There were 223 new DWI lesions (1–23 lesions) in the non-treated arterial territories of 37 patients. There were 154 cortical lesions, 45 cerebellar lesions, 21 subcortical lesions and 3 brainstem lesions. Analysis of the distribution pattern of cortical lesions showed that 88 of 154 lesions were located at the cortical border zone. Of the subcortical lesions, 13 of 21 lesions were located at the internal border zone area, within the corona radiata and centrum ovale. Only 4 lesions were located at the deep perforator territory. Infratentorial lesions were mostly located at the cerebellar hemisphere (45/48). Most lesions were tiny infarcts (<5 mm diameter); 7 of 223 lesions were >10 mm in diameter. Conclusions: Interventional-angiography-related microembolisms mostly lodge in the cerebral cortical border zone area and cerebellar hemisphere. Microembolisms to the deep perforating artery territory are distinctly rare.

Crossed Cerebellar Diaschisis in Status Epilepticus

Crossed cerebellar diaschisis (CCD) has been reported on positron-emission tomography and single-photon emission computed tomography of stroke patients. Rarely it has been described with brain diffusion-weighted MRI (DWI) of status epilepticus (SE). Case report. A 53-year-old woman was found unresponsive after cocaine use. A diagnostic electroencephalogram was consistent with ictal SE. A brain DWI showed reduced diffusion in the left temporo-parietal and occipital cortexes, the left thalamus and the right cerebellum. The DWI changes did not correspond to a vascular territory and were attributed to seizure activity and secondary CCD. A 2-week follow-up DWI showed interval near-complete resolution of the diffusion changes. CCD in SE may represent injury caused by excessive neuronal transmission from prolonged excitatory synaptic activity via the cortico-pontine-cerebellar pathway. Alternatively, it may be a result of interruption of the cortico-pontine-cerebellar pathway with loss of cortical inhibitory input. This case documents CCD during SE, providing further evidence of contralateral cerebellar involvement with a supratentorial epileptiform focus.

Lesion volume increase is related to neurologic progression in patients with subcortical infarction

It remains unknown whether subacute lesion volume increase is related to neurologic progression (NP) and clinical outcome (CO) in patients with single subcortical infarct (SSI) in the middle cerebral artery (MCA) territory. We studied 77 patients who underwent diffusion-weighted MRI (DWI) within 48 h after stroke onset, which revealed unilateral SSI in the MCA territory, and follow-up DWI and MR angiography within 7 days of onset. Neurologic progression was defined as the increase of the National Institutes of Health Stroke Scale (NIHSS) score by ≥2 during the first week. Clinical outcome was dichotomized as good (≤2) and poor (≥3) according to the modified Rankin Scale at 1 month after the onset. Lesion volume increase was defined when the infarct volume in the follow-up MRI exceeds the initial one by either ≥30% or 50%. Fourteen patients (18.2%) had NP, and 17 (22.1%) had poor CO. Increase in lesion volume, found in 42 patients (54.5%) when defined by 50% increase and in 51 (66.2%) by 30%, was significantly associated with NP (50%, p=0.010; 30%, p=0.027) and poor CO (50%, p=0.040; 30%, 0.111). Multivariate logistic analyses revealed that lesion volume increase was independently related to NP (odd ratio, 8.48; 95% CI, 1.55–46.46) and that NP was the important predictor for poor CO (odd ratio, 39.69; 95% CI, 3.44–458.68). We conclude that subacute lesion volume growth is closely related to the NP and that the NP predicts subsequent poor CO.

Perfusion CT Improves Diagnostic Accuracy for Hyperacute Ischemic Stroke in the 3-Hour Window: Study of 100 Patients with Diffusion MRI Confirmation

Purpose: Conventional noncontrast CT (NCCT) is insensitive to hyperacute cerebral infarction in the first 3 h. Our aim was to determine if CT perfusion (CTP) can improve diagnostic accuracy over NCCT for patients presenting with stroke symptoms in the 3-hour window. Methods: Consecutive patients presenting to our emergency department with symptoms of ischemic stroke <3 h old and receiving NCCT and CTP as part of their triage evaluation were retrospectively reviewed. Patients with follow-up diffusion-weighted MRI (DWI) <7 days from ictus were included. Two readers rated the NCCT and CTP for evidence of acute infarct and its vascular territory. CTP selectively covered 24 mm of brain centered at the basal ganglia with low relative cerebral blood volume in a region of low cerebral blood flow or elevated time to peak as the operational definition for infarction. A third reader rated all follow-up DWI for acute infarct and its vascular territory as the reference standard. Sensitivity, specificity, and predictive values were calculated. An exact McNemar test and generalized estimating equations from a binary logistic regression model were used to assess the difference in detection rates between modalities. A two-sided p value <0.05 was considered significant. Results: 100 patients were included. Sixty-five (65%) patients had follow-up DWI confirmation of acute infarct. NCCT revealed 17 (26.2%) acute infarcts without false positives. CTP revealed 42 (64.6%) acute infarcts with one false positive. Of the 23 infarcts missed on CTP, 10 (43.5%) were outside the volume of coverage while the remaining 13 (56.5%) were small cortical or lacunar type infarcts (≤15 mm in size). CTP was significantly more sensitive (64.6 vs. 26.2%, p < 0.0001) and accurate (76.0 vs. 52%, p < 0.0001) and had a better negative predictive value (59.6 vs. 42.2%, p = 0.032) than NCCT. Conclusion: In a retrospective cohort of 100 patients with symptoms of hyperacute stroke in the 3-hour window, CTP provided improved sensitivity and accuracy over NCCT.

Carotid artery dissection and middle cerebral artery stroke following methamphetamine use

Methamphetamine use may be associated with increased risk of stroke in young adults. We describe two cases of carotid artery dissection and ispilateral middle cerebral artery (MCA) stroke following methamphetamine use. ### Patient 1. A 36-year-old right-handed woman had sudden onset of speech difficulty and right-sided weakness while eating lunch. She presented to the emergency department within 30 minutes. Her medical history was significant for migraine and oral contraceptive and methamphetamine use. She was smoking methamphetamine with some left neck pain over the preceding two nights. Her initial examination was remarkable for global aphasia, left gaze preference, and right hemiplegia without Horner syndrome. The NIH Stroke Scale (NIHSS) score was 21. The initial head CT was unremarkable. IV tissue plasminogen activator (tPA) was started within 80 minutes of symptom onset. She improved significantly with only moderate expressive aphasia and mild right hemiparesis 8 hours after tPA therapy. A follow-up diffusion-weighted MRI of the brain showed a small infarct in the …