Variation in the MRI signal intensity of naturally occurring equine superficial digital flexor tendinopathies over a 12-month period

BackgroundSignal intensity (SI) of equine tendinopathies in MRI differs between the superficial digital flexor tendon (SDFT) and the deep digital flexor tendon (DDFT). In DDFT lesions, short tau inversion recovery (STIR) SI decreases earlier than T2-weighted (T2w) SI, while the latter decreases earlier in SDFT lesions, but long-term results using STIR sequences are lacking.MethodsStanding MRI of eight horses with naturally occurring SDFT lesions was performed at the day of treatment as well as 2, 6 and 12 months after treatment.ResultsAfter 12 months, six horses were sound and showed complete resolution of increased SI in T2w fast spin echo (FSE) images, but increased SI was found in STIR images in three horses and persisted in T1w and T2*w gradient recall echo images of all horses. In contrast, hyperintense areas were still visible in the SDFT in T2w FSE images in two horses presenting with re-injury. In the six horses without re-injury, percentage of cross-sectional areas affected and SI decreased over time in all sequences.ConclusionsThis study suggests that SI in naturally occurring SDFT lesions decreases earlier in T2w FSE than in STIR images, in contrast to the DDFT.

White matter hyperintensities: relationship to amyloid and tau burden

Although white matter hyperintensities have traditionally been viewed as a marker of vascular disease, recent pathology studies have found an association between white matter hyperintensities and Alzheimer’s disease pathologies. The objectives of this study were to investigate the topographic patterns of white matter hyperintensities associated with Alzheimer’s disease biomarkers measured using PET. From the population-based Mayo Clinic Study of Aging, 434 participants without dementia (55% male) with FLAIR and gradient recall echo MRI, tau-PET (AV-1451) and amyloid-PET scans were identified. A subset had cerebral microbleeds detected on T2* gradient recall echo scans. White matter hyperintensities were semi-automatically segmented using FLAIR MRI in participant space and normalized to a custom template. We used statistical parametric mapping 12-based, voxel-wise, multiple-regression analyses to detect white matter hyperintense regions associated with Alzheimer’s biomarkers (global amyloid from amyloid-PET and meta-regions of interest tau uptake from tau-PET) after adjusting for age, sex and hypertension. For amyloid associations, we additionally adjusted for tau and vice versa. Topographic patterns of amyloid-associated white matter hyperintensities included periventricular white matter hyperintensities (frontal and parietal lobes). White matter hyperintense volumes in the detected topographic pattern correlated strongly with lobar cerebral microbleeds (P < 0.001, age and sex adjusted Cohen’s d = 0.703). In contrast, there were no white matter hyperintense regions significantly associated with increased tau burden using voxel-based analysis or region-specific analysis. Among non-demented elderly, amyloid load correlated with a topographic pattern of white matter hyperintensities. Further, the amyloid-associated, white matter hyperintense regions strongly correlated with lobar cerebral microbleeds suggesting that cerebral amyloid angiopathy contributes to the relationship between amyloid and white matter hyperintensities. The study did not support an association between increased tau burden and white matter hyperintense burden.

Role of Magnetic Resonance Imaging in Unconscious Patients due to Diffuse Axonal Injury and Its Prognostic Value

Aim To study the long-term prognostic value of early magnetic resonance imaging (MRI) in unconscious patients with traumatic brain injury with findings of NCCT of the brain suggestive of diffuse axonal injury (DAI). Background Studies addressing the correlation of MRI with the pattern and duration of loss of consciousness due to DAI are few. The utility of MRI in predicting the functional outcome has not been reported in the Indian population. Materials and Methods In patients with DAI, MRI sequences including T1, T2*GRE (gradient recall echo), fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), and susceptibility-weighted imaging (SWI) were obtained. Glasgow coma scale (GCS) and Glasgow outcome scale (GOS) scores were documented at admission, on discharge, and at 3 months. Results A total of 54 patients (53 males, 1 female) were included in the study. The mean age was 27 ± 11.7 years. The mean GCS score on admission and at follow-up were 9.14 ± 2.3 and 11.7 ± 2.3, respectively. The mean GOS score on discharge and at 3 months were 2.6 ± 0.8 and 3.18 ± 1.02, respectively. SWI sequence detected maximum number of lesions followed by GRE and DWI. Patients with lesions in brainstem and basal ganglia were found to have a less favorable outcome as assessed by GCS and GOS at 3 months. There was no correlation between the total lesion load and outcome at 3 months. Conclusion In patients with DAI, SWI was found to be the most sensitive MRI sequence detecting maximum number of lesions. Patients with lesions in the brainstem and basal ganglia appear to have longer duration of unconsciousness and poorer outcome at 3 months.

Thrombus Characteristics Are Related to Collaterals and Angioarchitecture in Acute Stroke

BackgroundWe have theorized that clots with stasis are longer. We therefore explored the relationship between thrombus imaging characteristics on noncontrast computed tomography (NCCT) and magnetic resonance imaging (MRI) with clot length and pial collaterals on baseline computed tomography angiography (CTA).MethodsProspective study of acute ischemic stroke patients (2005-2009) from Keimyung University. Patients with known stroke symptom onset time, baseline CTA, MRI, and with M1-Middle Cerebral Artery (MCA)±intracranial internal carotid artery (ICA) occlusions were included. Clot length and pial collaterals were measured on baseline CTA.ResultsA total of 104 patients (mean age 65.1±12.28 years, 56.7% male, median baseline National Institutes of Health Stroke Scale 13) with intracranial ICA + MCA (n=50) or isolated M1-MCA (n=54) occlusions were included. Hyperdense sign on NCCT had a median clot length of 42.3 mm versus 29.5 mm when hyperdense negative (p=0.02). Clots showing blooming artifact on gradient recall echo MRI had a median length of 39.1 mm versus 24.5 mm without blooming (p=0.005). Patients with poor baseline collaterals on CTA had longer clots than those with intermediate/good collaterals (median clot length 49.4 mm vs 34.9 mm vs 20.5 mm respectively, p<0.001). In censored logistic regression modeling, clot length was an independent predictor of hyperdense sign (p=0.05) and of the presence of blooming artifact (p=0.006).ConclusionsClot length and baseline collateral status are independent predictors of clot hyperdensity on NCCT and blooming artifact on gradient recall echo. Longer clots are more likely to be hyperdense and to bloom more, probably because portions of these clots are freshly formed locally due to of stasis of blood around the original clot. This stasis could be because of poor collaterals and inefficient angio-architecture within the cerebral arterial tree.

Mechanical thrombectomy for acute ischemic stroke with cerebral microbleeds

BackgroundThe influence of cerebral microbleeds (CMBs) on post-thrombolytic hemorrhagic transformation (HT) in patients with acute ischemic stroke remains controversial.ObjectiveTo investigate the association of CMBs with HT and clinical outcomes among patients with large-vessel occlusion strokes treated with mechanical thrombectomy.MethodsWe analyzed patients with acute stroke treated with Merci Retriever, Penumbra system or stent-retriever devices. CMBs were identified on pretreatment T2-weighted, gradient-recall echo MRI. We analyzed the association of the presence, burden, and distribution of CMBs with HT, procedural complications, in-hospital mortality, and clinical outcome.ResultsCMBs were detected in 37 (18.0%) of 206 patients. Seventy-three foci of microbleeds were identified. Fourteen patients (6.8%) had ≥2 CMBs, only 1 patient had ≥5 CMBs. Strictly lobar CMBs were found in 12 patients, strictly deep CMBs in 12 patients, strictly infratentorial CMBs in 2 patients, and mixed CMBs in 11 patients. There were no significant differences between patients with CMBs and those without CMBs in the rates of overall HT (37.8% vs 45.6%), parenchymal hematoma (16.2% vs 19.5%), procedure-related vessel perforation (5.4% vs 7.1%), in-hospital mortality (16.2% vs 18.3%), and modified Rankin Scale score 0–3 at discharge. CMBs were not independently associated with HT or in-hospital mortality in patients treated with either thrombectomy or intravenous thrombolysis followed by thrombectomy.ConclusionsPatients with CMBs are not at increased risk for HT and mortality following mechanical thrombectomy for acute stroke. Excluding such patients from mechanical thrombectomy is unwarranted. The risk of HT in patients with ≥5 CMBs requires further study.

Abstract T P56: The Safety of Clopidogrel Loading Therapy in Acute Ischemic Stroke Patients with Chronic Hemorrhage on Gradient Echo MRI

Objective: To determine if an acute loading dose of clopidogrel is safe in acute ischemic stroke (AIS) patients with chronic intracerebral hemorrhage (ICH). Background: Clopidogrel loading is a promising therapy for AIS patients not eligible for tissue plasminogen activator (tPA) who are at risk for progressive stroke. Previous ICH is a risk factor for developing a new ICH. However, the acute risk of these events in this population after loading with clopidogrel has not been studied. Methods: We examined 1,011 AIS patients presenting to our center from 06/07/07-07/31/13. Only those loaded with at least 300mg of clopidogrel (with or without aspirin) within 6 hours of admission were analyzed. We compared new onset hemorrhagic complications in patients with and without chronic ICH, defined as areas of parenchymal hypodensity on gradient recall echo (GRE) sequencing on MRI. Repeat CT or MRI during admission was evaluated by a vascular neurologist for evidence of new ICH, hemorrhagic infarct using ECASS II criteria, or new ischemic infarct. Results: Of 365 AIS patients loaded with clopidogrel, 67 had chronic ICH on GRE. Patients with chronic ICH were more likely to be African American (80.0% vs. 65.9%, p=0.028) and male (69.2% vs. 50.9%, p=0.008). These patients were more likely to have existing comorbidities: history of stroke (67.7% vs 37.5%, p<0.001), hypertension (90.8% vs 78.2%, p=0.021), and hyperlipidemia (56.9% vs 42.5%, p=0.036). After logistic regression analysis adjusting for significant covariates, chronic ICH patients did not have significant differences in any new hemorrhagic changes (p=0.709), new infarct (p=0.429), neuroworsening (defined as an increase in NIHSS score by 2 points within 24 hours, p=0.297), poor functional outcome (defined as modifed Rankin Scale > 2 on discharge, p=0.889), or unfavorable discharge disposition (defined as disposition other than home or inpatient rehabilitation, p=0.166). Conclusion: The presence of chronic ICH on GRE did not increase the risk of new ICH, hemorrhagic infarct, ischemic event, or neurologic deterioration after administration of an acute loading dose of clopidogrel for AIS.