Abstract WMP28: Follow-up of Large Intracranial Aneurysms Indicates Growth Frequency Varies According to Location and Size

Background: Although treatment is recommended for unruptured large aneurysms (≥7mm), which have higher rupture risk, in practice some aneurysms remain under observation due to a patient’s medical history or age. Detailed data about aneurysm growth during follow-up is limited. In this study, we aim to investigate growth in large aneurysms by reviewing the unruptured aneurysms cases which were followed in our center.

Hypothesis: The growth of large unruptured aneurysms varies according to aneurysm characteristics and patient medical history.

Method: A retrospective review of patient records based on unruptured aneurysms diagnosed in our center from 2005 to 2011 was performed. Large unruptured aneurysms which had more than one CTA examination separated by at least 3 months were included. Aneurysm characteristics, patient information, and medical history were recorded. Univariate and multivariate logistic regression were used to analyze aneurysm growth.

Results: From a total of 410 unruptured aneurysms followed in our center, 50 large aneurysms (41 females, 9 males; age 67.3±12.6 years) were included: 42 aneurysms with initial size 7-12.9 mm, 7 aneurysms 13-23.9 mm, and 1 aneurysm ≥24 mm. During the average 25.6 month follow-up, 15 (30%) aneurysms enlarged and 35 (70%) were unchanged. The growth frequency of aneurysms located in ICA, MCA, ACA, BA was 40%, 22%, 20% and 17%, respectively. The growth frequency of aneurysms of sizes 7-12.9 mm, 13-23.9 mm and ≥24 mm was 23.8%, 71.4% and 0, respectively. Using univariate logistic regression analysis, duration of follow-up (P=0.023), and history of ischemic stroke (P=0.027) were associated with growth. Multivariate logistic regression showed only duration of follow-up as a risk factor for growth (OR, 1.056 per month; 95% CI 1010 to 1.104; P=0.016). Only one aneurysm (ICA) ruptured in the follow-up (70 months), resulting in a rupture rate of 6.7% (1/15) enlarged aneurysms (0/35 unchanged aneurysms).

Conclusion: A large percentage of aneurysms selected for observation grew, and growth frequency varied according to aneurysm location and size. A larger, future study may identify additional factors associated with growth, including ones specific to aneurysm characteristics like location and initial size.

Abstract WP41: Peri-Procedural Arterial Spin Labeling and Dynamic Susceptibility contrast Perfusion in Detection of Cerebral Blood Flow in Patients with Acute Ischemic Syndrome

Purpose: To investigate the potential clinical value and diagnostic performance of arterial spin-labeled (ASL) and dynamic susceptibility contrast (DSC) perfusion in detection of cerebral blood flow (CBF) changes before and after endovascular recanalization in patients with acute ischemic syndrome (AIS).

Methods: This retrospective study was performed using MR examinations between 2010-2012. Inclusion criteria were: patients with AIS who underwent endovascular recanalization and acquisition of both ASL and DSC before and after revascularization. ASL CBF and multiparametric DSC perfusion maps were qualitatively evaluated for image quality, presence of hypo or hyperperfusion and location of perfusion abnormality. Lesion segmentation for infarct core (ADCb >550) and hypoperfused area (TMax > 4 sec) was performed on DSC. rCBF was calculated using a regions-of-interest (ROI) method in the infarction core and hypoperfused areas using coregistered ASL and DSC images. Core and hypoperfused rCBF ROI’s were used for paired pre- and post-treatment intermodality comparisons. Interobserver and intermodality agreement was evaluated by Kappa test. T-test and Spearman correlation coefficients were calculated for ASL and DSC rCBF values.

Results: Twenty-five patients were met our inclusion criteria. Five studies were rated non-diagnostic, resulting in a total of 45 pair of DSC-ASL for comparison. ASL and DSC agreed on type of perfusion abnormality in 32 of 45 cases (71%) and location of the perfusion abnormality in 36 of 45 cases (80%). The image quality of ASL was lower than DSC, resulting in interobserver variability for the type (k =0.45) and location (k=0.56) of perfusion abnormality. ASL was unable to show any type of perfusion abnormality in 11% of patients. In patients with successful recanalization, hyperperfusion (rCBF> 1) was detected in 100% on DSC and 47% on ASL. ASL showed prolonged arterial transit effects in 58% of successfully recanalized patients.

Conclusion: ASL is moderately consistent with DSC for detection of cerebral blood flow changes in patients with AIS. Qualitative and quantitative differences exist between two modalities, in particular in respect to detection of hyperperfusion in successfully recanalized patients.

Abstract TP35: Reperfusion? Angiography and Serial Perfusion MRI Reveal Distinct Features of Endovascular Therapy for Middle Cerebral Artery Stroke

Background: TICI scores are routinely used to measure reperfusion on angiography after endovascular therapies for acute stroke. Reperfusion may also be quantified by Tmax parameter changes on serial perfusion MRI before and after treatment. Such definitions of reperfusion used in trials may vary and we therefore investigated the correlation between TICI and quantification of Tmax changes on serial MRI in proximal middle cerebral artery (MCA) stroke cases treated with endovascular therapy.

Methods: Consecutive acute ischemic stroke patients treated with endovascular therapy for proximal or M1 MCA occlusions with serial perfusion MRI at baseline and 3-6 hours after treatment were analyzed. TICI scores were noted for reperfusion on angiography. Reperfusion on serial MRI was separately defined as interval volume of Tmax>6s lesion size, dichotomous change by > 70% reduction in Tmax>6s, and voxel-wise changes across all Tmax values.

Results: 57 stroke patients (mean age 64±20 years, 68% female) with M1 MCA occlusions imaged with perfusion MRI both before and after treatment with endovascular therapy were studied. TICI angiographic outcomes included 8 TICI 0, 4 TICI 1, 22 TICI 2a, 22 TICI 2b and 1 TICI 3. Both the interval volume of Tmax>6s lesion size and voxel-wise changes across all Tmax values varied extensively. Dichotomous reduction in Tmax>6s lesion volume by 70% was noted in only 12.9% of cases, with reduction by 60% in 19.4%, and by 50% in 30.6%. TICI reperfusion did not correlate with either: interval volume of Tmax>6s lesion size, dichotomous change by > 70% reduction in Tmax>6s, or voxel-wise changes across all Tmax values. Even when only TICI 2a/2b/3 or TICI 2b/3 cases were analyzed, no correlation could be established between the TICI angiographic measure of reperfusion at post-procedure with the change in Tmax lesion from baseline to 3-6 hours after revascularization.

Conclusions: Reperfusion measured by TICI at angiography and changes in Tmax on serial perfusion MRI provide distinct information, likely reflecting heterogeneity and different vascular phases (arterial vs. microcirculation). Determining the clinical impact of such reperfusion measures on recovery after stroke remains paramount.

Abstract TP41: Arterial Spin-Labeled Perfusion MRI with Multi-Delay: Expanding Beyond CBF in Acute Ischemic Stroke

Background: Arterial spin-labeled (ASL) perfusion MRI can measure cerebral blood flow (CBF), yet the prolonged delays of collateral perfusion in acute ischemic stroke may impose limitations. Multiparametric maps of perfusion, including transit times and cerebral blood volume (CBV), may reveal important hemodynamic features before CBF collapse. We implemented a novel multi-delay ASL sequence to investigate multiparametric perfusion changes in acute stroke.

Methods: Consecutive acute ischemic stroke patients admitted during an 8-month period were evaluated with pseudo-continuous ASL on Siemens 1.5 T and 3 T scanners within 12 hours of symptom onset. ASL was acquired using a 4-delay pCASL protocol with background suppressed 3D GRASE (postlabeling delay (PLD)=1.5/2/2.5/3s, FOV=22cm, matrix=64x64, 16x8mm slices, rate-2 GRAPPA, TE=22ms, 8 pairs of tag and control for each delay, total scan time 4min). After motion correction, arterial transit time (ATT), CBF, and arterial CBV (aCBV) maps were generated from the 4 PLDs.

Results: A total of 161 ASL multi-delay perfusion MRI studies were performed in 130 acute ischemic stroke patients (mean age was 71±18 years and 56% were female). Repeated multi-delay ASL or serial studies were acquired in 19 cases, including 11 cases with 2 MRIs, 7 with 3, and 1 with 6 MRIs, depicting multiparametric blood flow changes after treatment. Correlation of multi-delay ASL (4 PLDs) and DSC MRI CBF asymmetry measures in MCA stroke patients (when available) was r=0.785 (p<0.001) and r=0.683 (p=0.003) for CBV measures with limited correlation for ATT.

Conclusions: Multidelay ASL with 4 PLDs is feasible in the setting of acute stroke, providing multiparametric perfusion measures (CBF, CBV, ATT) of blood flow changes with treatment.

Abstract TP33: Early DWI Changes in the Thrombolysis Time Window: From DWI-Negative to Malignant Stroke in More than 300 Cases

Background: Thrombolysis for acute stroke is routinely based on time from last known well (TLKW) as the extent of ischemic injury during early epochs is assumed to be minimal. DWI is extremely sensitive, yet rarely acquired prior to thrombolysis and the nature of DWI lesions is largely unknown during this time window. Large or malignant strokes on DWI, however, result in poor outcome after thrombolysis. We retrospectively analyzed a large cohort of DWI acquired as part of a standard MRI protocol for triage of patients at a single center over 8 years.

Methods: Consecutive patients with discharge diagnosis of ischemic stroke and documented time last known well to DWI MRI acquisition < 4.5 hours were identified. An imaging expert outlined DWI lesions on every axial slice for all MRIs to calculate corresponding lesion volumes as often-subtle changes may evade automated detection. Total DWI volumes were analyzed with respect to age, gender, TLKW and time of day.

Results: 307 stroke patients (mean age 69±17 years, 51% female) from 2004-2012 had DWI with TLKW < 4.5 hours (mean 147±62 min). DWI lesion volume (median 3.67cc) in each case varied extensively (TLKW-DWI < 1 hour (n=8) 0.40cc (0-93cc), 1-2 hours (n=126) 3.02 (0-265), 2-3 hours (n=78) 2.18 (0-103), 3-4.5 hours (n=95) 6.96 (0-227)). Only slight or negligible correlation (r=0.175, p=0.002) was noted between DWI lesion volume and TLKW-DWI time duration. DWI-negative findings < 4.5 hours occurred in 8.5% of stroke cases. Malignant strokes (>70cc) were noted in 7.5%. Older age was associated with DWI-negative strokes (mean 77 vs. 68 years, p=0.013). TLKW-DWI time duration was unrelated to DWI-negative strokes, yet malignant stroke was more common later (p=0.009). Interestingly, the majority of malignant strokes on DWI had TLKW during the daytime.

Conclusions: DWI changes are extremely variable within 4.5 hours. Most lesions are small, yet malignant strokes are not uncommon. Further work should delineate the clinical determinants of these early malignant strokes to optimize outcomes in acute ischemic stroke.

Abstract TP56: Insight Into Human Ischemia Reperfusion Injury in Acute Stroke: A Voxel-Based MRI Analysis of Tissue Fate

Background: Reperfusion is characterized by initial restriction of blood supply followed by subsequent vascular restoration and concomitant reoxygenation of downstream tissue. In spite of mitigating initial tissue hypoxia, exacerbation of tissue injury may occur. Animal models have delineated reperfusion injury on the cellular and molecular levels, yet, no study has quantified voxel-based analyses of tissue fate due to reperfusion injury in human stroke.

Methods: Evaluation included 58 stroke patients with an age range of 65±18 years, 65% of whom were woman and 35% men. All patients presented with M1 MCA occlusion and a subset received mechanical thrombectomy (38) while another received intravenous tPA followed by mechanical thrombectomy (20). Serial perfusion MRI images were obtained on presentation as well as 3-6 hours following reperfusion and processed to extract Tmax parameters. These images were co-registered serially at the voxel level with tissue fate outcomes on FLAIR and GRE 4-5 days following presentation. Reperfusion was defined by serial changes observed in Tmax voxels. The volume of reperfusion, injury, as well as tissue fate relative to initial perfusion were calculated.

Results: Hemorrhage was noted on GRE in 28.9% of the patients who received thrombectomy alone and in 20% of those who received IV tPA followed by thrombectomy. In pure thrombectomy cases without later hemorrhage, average voxel-based reperfusion was 72.3% with 18% demonstrating reperfusion injury and tissue death as assessed by FLAIR imaging 4-5 days following presentation, averaging 86.2%. In patients who received IV tPA followed by mechanical thrombectomy without any subsequent hemorrhage, average voxel-based reperfusion was 66.0% with 6.2% demonstrating reperfusion injury in reperfused voxels and tissue death as assessed by FLAIR imaging 4-5 following presentation, averaging 90.3%.

Conclusions: Non-hemorrhagic forms of reperfusion injury are common in acute stroke patients treated with standard therapies. Despite reperfusion and irrespective of treatment modality, substantial amounts of tissue are destined to infarct. Voxel-based analyses of serial imaging studies may provide a framework to develop therapies for reperfusion injury.

Abstract TP82: The Growth of Small, Asymptomatic, Unruptured Intracranial Aneurysms with no History of SAH -Different Risk Factors Associated with Single and Multiple Aneurysms

Introduction: The International Study on Unruptured Intracranial Aneurysms suggests that small (<7mm), asymptomatic, unruptured intracranial aneurysms (UIA) in patients with no history of subarachnoid hemorrhage (SAH) should be managed conservatively. Recent research has independently shown considerable variation in the rupture risk of small UIA. As enlargement may indicate increased risk of rupture, the factors related to UIA growth may also influence rupture risk. Information about small UIA growth is limited and heterogeneous due to limited follow-up data.

Hypothesis: Growth factors for small UIA vary between subset groups.

Methods: A retrospective study was performed based on a total of 508 patients diagnosed with UIA from 2005-2010 in our center. 235 patients with asymptomatic, small UIA and no history of SAH were monitored with high resolution 3D CTA. Patient medical history and aneurysm characteristics (size, growth, location and multiplicity) were analyzed. Multiple logistic regression analysis and the Hosmer-Lemeshow statistic were used to identify the factors associated with growth. The Student’s t-test was applied to compare the aneurysm growth rate between subset groups.

Results: A total of 319 UIA were included with follow-up durations of 29.2 20.0 months. 42 UIA increased in size during the follow-up. 5 UIA grew to become ≥ 7 mm (within 38.2±18.3 months). A trend of higher growth rates was found in single aneurysms than in multiple aneurysms (P=0.07). History of stroke was the only factor associated with single aneurysm growth (P=0.03). The number of aneurysms (P=0.014), aneurysms located within the posterior circulation (P=0.023), and patient history of transient ischemic attack (P=0.032) were related to multiple aneurysm growth.

Conclusion: We found that multiple small aneurysms were more likely to grow, especially those at posterior circulation. Although single aneurysms have a lower risk of growth, a trend of higher growth rates was found.

Imaging techniques in spinal cord injury

BACKGROUND

Spinal imaging plays a critical role in the diagnosis, treatment, and rehabilitation of patients with spinal cord injury (SCI). In recent years there has been increasing interest in the development of advanced imaging techniques to provide pertinent microstructural and metabolic information that is not provided by conventional modalities.

METHODS

This review details the pathophysiological structural changes that accompany SCI, as well as their imaging correlates. The potential clinical applications of novel spinal cord imaging techniques to SCI are presented.

RESULTS

There are a variety of novel advanced imaging techniques that are principally focused on the microstructural and/or biochemical function of the spinal cord, and can potentially be applied to traumatic SCI, including diffusion tensor imaging, magnetic resonance spectroscopy, positron emission tomography, single-photon emission computed tomography, and functional magnetic resonance imaging. These techniques are presently in various stages of development, including some whose applications are primarily limited to laboratory investigation, whereas others are being actively used in clinical practice.

CONCLUSION

Advanced imaging of the spinal cord has tremendous potential to provide patient-specific physiological information about the status of cord integrity and health. Advanced spinal cord imaging is still at early stages of development and clinical implementation but is likely to play an increasingly important role in the management of spinal cord health in the foreseeable future.

Acromegaly due to an ectopic pituitary adenoma in the clivus: case report and review of literature

Pituitary adenomas rarely originate outside the sella turcica. Ectopic locations include the suprasellar region, sphenoid sinus, cavernous sinus and clivus. We describe a 50-year-old female who presented with clinical signs and biochemical evidence of acromegaly. Pituitary MRI demonstrated a 2 mm hypointense lesion on the right side of the pituitary gland. However upon drilling of the upper clival bone to expose the sella during endoscopic transsphenoidal surgery, soft tumor-like tissue was encountered within the clivus. Exploration of the sella, including the area of hypointensity noted on preoperative imaging, did not identify any other abnormality. Immunohistochemical examination of the fully resected tumor demonstrated growth hormone immunoreactivity. Failed preoperative diagnosis of this rare ectopic GH-producing tumor was compounded by the presence of a misleading pituitary abnormality consistent with a microadenoma. The epidemiology and pertinent literature of this uncommon condition is discussed.

Neuroimaging in the definition and organization of the epilepsies: we're not there yet

Neuroimaging significantly affects the diagnosis and treatment of patients with patients. Despite its importance, magnetic resonance imaging (MRI) has been marginally incorporated into concepts used to define epilepsy etiologies by the International League Against Epilepsy (ILAE) Classification Commission. We propose that Structural etiology be defined as positive neuroimaging abnormalities likely causing the seizures. This would contrast with Genetic and Unknown etiologies, where imaging shows no overt structural abnormality that explains the seizures. It is further recommended that Structural and Metabolic be separated into individual categories, as the outcomes and therapies are different. It is advocated that Structural etiology be subdivided into subgroups based on MRI and surgical syndromes. With this approach, the ILAE should acknowledge that both MRI and electroencephalography (EEG) are necessary diagnostic tools in the classification of epilepsy syndromes and etiologies in the modern era. Promoting the use of neuroimaging into concepts that determine terminology will promote the notion that epilepsy classification should consider structural etiology of the seizures, along with the frequency of the most common epilepsy syndromes, and prognosis for spontaneous and treated remission and cure.

Anterior choroidal artery ischaemic patterns predict outcome of carotid occlusion

OBJECTIVE

To investigate whether anterior choroidal artery (AChA) territory sparing or AChA infarction restricted to the medial temporal lobe (MT), implying good collateral status, predicts good outcome, defined as modified Rankin Scale 0-2, at discharge in acute internal carotid artery (ICA) occlusion.

METHODS

The authors studied consecutive patients with acute ICA occlusion admitted to an academic medical centre between January 2002 and August 2010, who underwent MRI followed by conventional angiography. The pattern of AChA involvement on initial diffusion-weighted imaging was dichotomised as spared or MT only versus other partial or full. The association of AChA infarct patterns and good outcome at discharge was calculated by multivariate logistic regression with adjustment.

RESULTS

For the 60 patients meeting entry criteria, mean age was 68.3 years and median admission NIH Stroke Scale score was 19. AChA territory was spared or restricted to the MT in 27 patients and other partially involved or fully involved in 33 patients. AChA territory spared or ischaemia restricted to MT only, compared with other partial infarct patterns or full infarct, was independently associated with good discharge outcome (44.4% vs 12.1%, OR 7.24, 95% CI 1.32 to 39.89, p=0.023).

CONCLUSION

In acute ICA occlusion, the absence of AChA infarction or restriction to the MT is an independent predictor of good discharge outcome. Analysis of AChA infarct patterns may improve early prognostication and decision-making.

Leukoaraiosis predicts parenchymal hematoma after mechanical thrombectomy in acute ischemic stroke

BACKGROUND AND PURPOSE

The purpose of this study was to determine whether leukoaraiosis (LA) predicts hemorrhagic transformation and poor outcome in patients with acute ischemic stroke treated by mechanical thrombectomy.

METHODS

We retrospectively analyzed patients with anterior circulation stroke treated with Merci devices and identified LA in the deep white matter (DWM) and periventricular white matter on the preintervention MR images. We dichotomized patients into those with moderate or severe LA in the DWM versus those without. Hemorrhage rates and outcomes were evaluated between 2 groups. We analyzed the association of moderate or severe LA with hemorrhagic transformation and poor outcome.

RESULTS

Twenty-six of 105 patients had moderate or severe LA in the DWM. Patients with moderate or severe LA in the DWM were older, had more severe neurological deficits and worse outcome, had higher rates of hemorrhagic transformation and parenchymal hematoma, but had equivalent rates of hemorrhagic infarct and subarachnoid hemorrhage when compared with those without. Patients with only periventricular LA did not have a higher rate of parenchymal hematoma. Moderate or severe LA in the DWM was an independent predictor of hemorrhagic transformation (OR, 3.4; P=0.019) and parenchymal hematoma (OR, 6.3; P=0.005). Patients with parenchymal hematoma were less often independent (modified Rankin Scale≤2, 3.8% versus 32.5%; P=0.003) and had greater in-hospital mortality (50% versus 10.4%; P<0.001).

CONCLUSIONS

Moderate or severe LA in the DWM increases the risk of parenchymal hematoma after Merci thrombectomy for patients with acute stroke. These findings require validation in a larger prospective study.

The value of arterial spin-labeled perfusion imaging in acute ischemic stroke: comparison with dynamic susceptibility contrast-enhanced MRI

BACKGROUND AND PURPOSE

The purpose of this study was to evaluate the potential clinical value of arterial spin-labeled (ASL) perfusion MRI in acute ischemic stroke (AIS) through comparison with dynamic susceptibility contrast (DSC) enhanced perfusion MRI.

METHODS

Pseudocontinuous ASL with 3-dimensional background-suppressed gradient and spin echo readout was applied with DSC perfusion MRI on 26 patients with AIS. ASL cerebral blood flow and multiparametric DSC perfusion maps were rated for image quality and lesion severity/conspicuity. Mean ASL cerebral blood flow and DSC perfusion values were obtained in main vascular territories. Kendall coefficient of concordance was calculated to evaluate the reliability of ratings. Spearman correlation coefficients were calculated to compare ratings and quantitative perfusion values between ASL and DSC perfusion maps.

RESULTS

ASL cerebral blood flow and DSC perfusion maps provided largely consistent results in delineating hypoperfused brain regions in AIS. Hyperemic lesions, which also appeared frequently in the AIS cases studied, were more conspicuous on ASL cerebral blood flow than on DSC cerebral blood flow, mean transit time and time to the maximum of the tissue residual function maps.

CONCLUSIONS

As a rapid, noninvasive, and quantitative technique, ASL has clinical use in detecting blood flow abnormalities in patients with AIS.

Abstract 1905: Arterial Spin-Labeled MRI of Leptomeningeal Collateral Perfusion in Acute Ischemic Stroke

Background: Leptomeningeal collaterals and associated cortical perfusion downstream from a proximal arterial occlusion or stenosis are potent predictors of outcome in acute stroke. Arterial spin-labeled (ASL) MRI may depict delayed arterial transit effects (DATE) of these collaterals and cerebral blood flow (CBF), utilizing noninvasive techniques without the use of contrast. We conducted a prospective validation study of ASL DATE and CBF as biomarkers of leptomeningeal collateral perfusion compared to digital subtraction angiography (DSA) and dynamic susceptibility contrast (DSC) perfusion MRI in acute ischemic stroke.

Methods: Consecutive anterior circulation acute ischemic stroke patients admitted during a 1-year period were evaluated with pseudo-continuous ASL, DSA and DSC perfusion MRI within 12 hours of symptom onset. ASL DATE extent was scored using a 3-point scale and angiographic collaterals on the DSA graded using the ASITN/SIR collateral score. ASL CBF and DSC CBF maps were co-registered to derive comparative ROI statistics on perfusion in the symptomatic territory. ASL CBF lesions < 15 mL/100 g/min were used to measure DSC CBF values within coregistered ROIs.

Results: Among 39 patients meeting entry criteria, mean age was 66±19 years and 51% were male. All 39 patients were imaged with ASL and DSA, with DSC perfusion MRI in a subset of 27. Sites of vascular occlusion or stenosis were: terminal ICA - 10, M1 MCA - 20, M2 MCA - 5 and more distal MCA - 4. ASL DATE scores ranged from 0-2, with a median of 1. DSA collateral grade ranged from 0-4, with a median of 2. Overall, there was strong correlation (r=0.702, p<0.001) between the ASL and DSA measures of leptomeningeal collateral supply. In the downstream territory from these leptomeningeal collaterals, ASL CBF and DSC CBF maps both revealed hypoperfusion in regions that closely matched. Only limited correlation, however, was noted between exact ASL CBF and DSC CBF values within the co-registered ROIs.

Conclusions: ASL MRI provides an accurate, noninvasive measure of leptomeningeal collateral perfusion in acute ischemic stroke due to anterior circulation stenosis or occlusion. ASL CBF measures of collateral perfusion likely are arterially weighted, like DSA collateral grades, and unlike conventional DSC perfusion MRI CBF values.

Abstract 3094: Diffusion-Positive Cerebral Ischemia with Transient Symptoms - Is it Transient Ischemic Attack or Minor Ischemic Stroke? A Formal Analysis of Demographics, Risk Factors, and Prognosis

Background: The classification of patients with minor cerebral ischemic events is evolving. Under the classical time-based definition of TIA, cerebral infarcts with transient symptoms (CITS) were classified as TIA, while it is classified as minor ischemic stroke (MIS) under the modern tissue-based definition. However, arguments for this reclassification have been largely based on pathologic principles rather than formal analysis of whether CITS patients clinically more resemble DWI-negative TIA patients or MIS patients in demographics, clinical features, and prognosis.

Methods: We analyzed consecutive patients recorded in a prospectively maintained database with symptoms of presumed focal ischemic origin either lasting less than 24 hours or with minor neurologic deficits (NIHSS≤5) lasting more than 24 hours. Patients had to present within 48 hours of symptom onset and have undergone acute DWI. Patients were excluded if ischemia occurred immediate after carotid endarterectomy or stenting. Clinical variables, ABCD 2 score, presence of DWI abnormality, relevant large artery disease (≥ 50% stenosis or occlusion of ipsilateral intracranial or extracranial vessels), and stroke recurrence within 90 days were recorded for analysis.

Results: Among 416 patients meeting inclusion criteria (mean age 67 years, female 47.1%), 108 (26.0%) were CITS, 149 (35.8%) were DWI-negative TIA, and 159 (38.2%) were MIS. Compared with DWI-negative TIA patients, CITS patients were younger (65 vs. 70 years, p=0.017), had more coronary artery disease (25.9% vs. 14.1%, p=0.024) and relevant large artery disease (45.2% vs. 20.8%, p<0.001). In contrast, only diabetes differed between CITS and MIS patients (16.7% vs. 29.7%, p=0.027). The frequency of recurrent stroke was not different between MIS and CITS patients (16.0% vs. 12.3%, p>0.05), however, both were substantially higher than in DWI-negative TIA patients (2.5%). In multivariate logistic regression analysis performed across the entire cohort, the independent predictors of recurrent stroke were presence of DWI lesion (OR 4.95, 95% CI 1.11-22.09) and relevant large artery disease (OR 3.58, 95% CI 1.47-8.73).

Conclusion: DWI-positive cerebral ischemia with transient symptoms more resembles MIS than DWI-negative TIA in risk factor profile and prognosis of patients. DWI abnormality and large artery disease, rather than clinical variables, are the predominant determinants of early stroke recurrence. These results emphasize the utility of urgent MR imaging in patients with minor cerebral ischemic episodes and support the rationale of tissue-based definition of TIA over time-based definition.

Abstract 1910: Hyperperfusion in Acute Ischemic Stroke: Serial Arterial Spin-Labeled MRI of Reperfusion and Hemorrhagic Transformation

Background: Arterial spin-labeled (ASL) MRI facilitates repeated noninvasive evaluation of cerebral blood flow without the use of contrast. Hyperperfusion may be readily detected with ASL and serial imaging may therefore chronicle the dynamics of territorial perfusion from acute to chronic phases after stroke. We characterized hyperperfusion on ASL in a prospective series of acute ischemic stroke patients, describing the clinical correlates, time course and association with reperfusion hemorrhage.

Methods: A consecutive series of acute ischemic stroke patients admitted during a 1-year period were evaluated with pseudo-continuous ASL with background suppressed 3D GRASE (delay=2s, matrix=64x64; 26 slices, resolution 3.4x3.4x5mm, scan time 4min). Post-processed ASL CBF maps were visually inspected for detection of hyperperfusion. DSA measures of collaterals and reperfusion were scored when available and hemorrhagic transformation (HT) was graded on GRE in all 198 cases. Univariate and multivariate statistical analyses delineated clinical correlates, timing and other imaging features of hyperperfusion.

Results: Among 198 patients, mean age was 69.4±15.7 years and 48.5% were women. Among 77 with serial ASL MRI, interval from initial to follow-up MRI was median 25.0 (IQR 10.3-53.9) hours. Hyperperfusion was detected in 15/198 (7.6%) patients at baseline and 30/77 (39.0%) at follow-up. Trajectories included 7/77 (9.1%) with hyperperfusion at both baseline and follow-up and 38/77 (49.4%) showing hyperperfusion at any timepoint during admission. Hyperperfusion correlated with achievement of reperfusion among patients undergoing endovascular therapy (OR 6.5, 95% CI 1.82-23.25, p=0.018) and history of atrial fibrillation (OR 4.4, 95% CI 1.9-10.6, p<0.001). Analysis of the 42 cases with DSA revealed that hyperperfusion was most common in patients with poor collateral grade followed by more complete TICI reperfusion scores. Overall, HT affected 57/198 (28.8%), including 35/198 (17.7%) HI1, 11/198 (5.6%) HI2, 8/198 (4.1%) PH1 and 3/198 (1.5%) PH2. Multivariate analyses revealed that hyperperfusion at any timepoint was a potent predictor of HT (OR 52.6, 95%CI 12.4-222.6, p<0.001).

Conclusions: Hyperperfusion in acute ischemic stroke is frequently demonstrated by ASL MRI, providing novel insight on the dynamics of reperfusion and HT. Hyperperfusion increases the risk of HT 50-fold, likely due to autoregulatory loss. Poor collaterals and sudden reperfusion in vulnerable cases such as those with atrial fibrillation may herald hyperperfusion and HT.

Abstract 3198: Procedural Outcomes in Mechanical Thrombectomy for Acute Stroke: Atrial Fibrillation Predicts Single Device Therapy

Background Timely and efficient reperfusion is associated with better outcome from acute cerebral ischemia. The predictors of procedural success in patients treated with multimodal mechanical device strategies (Merci ± Penumbra ± angioplasty and stenting) have not been well delineated.

Methods In a prospectively maintained database, we analyzed consecutive patients with acute ICA and M1 occlusions treated with endovascular recanalization following multimodal MRI. We investigated the pretreatment clinical and imaging factors affecting three procedural outcomes: number of passes, single device-type therapy, and presence of SAH after the procedure. We also sought to determine the relationship between these procedural variables with substantial recanalization (TICI≥2b) and clinical outcome.

Results Among 105 patients meeting study entry criteria, mean age was 66.6 (±17.8), 65% were female and 34% had history of atrial fibrillation. The median pretreatment NIHSS was 18 (range 2-31), mean baseline DWI volume was 30.6cc (SD±35.1), and mean time to groin puncture was 412min (SD±207.6). The median number of mechanical device passes was 2 (range 0-8). 73 (70%) patients were treated with a single device. IV tPA was used in 43 patients (41%). Substantial recanalization occurred in 43 patients (41%). In the final binary logistic regression multivariate analysis, among all baseline clinical and imaging variables, history of atrial fibrillation was the most significant factor associated with a single device therapy (OR 0.249; p=0.024). Age, gender, baseline DWI volumes, arterial occlusion site and time to recanalization did not correlate with the number of attempts, single or multiple device usage, or presence of SAH after the procedure. None of the procedural or baseline variables correlated with recanalization rates. The strongest predictors of poor outcome (mRS≥3 at discharge) were high baseline NIHSS (OR 0.87; p<0.001) and presence of SAH after the procedure (OR 0.05; p=0.001). However, the presence of SAH did not correlate with the number of attempts or devices used.

Conclusions: A history of atrial fibrillation predicts single device usage in mechanical thrombectomy for acute ischemic stroke treatment. This is likely due to the fibrin-rich histological composition of the clot. In contrast to prior studies involving a single type of device, increased number of passes with multiple different mechanical devices was not associated with lower recanalization rates and did not worsen clinical outcome.

Thrombus branching and vessel curvature are important determinants of middle cerebral artery trunk recanalization with Merci thrombectomy devices

BACKGROUND AND PURPOSE

Determinants of successful recanalization likely differ for Merci thrombectomy and intra-arterial pharmacological fibrinolysis interventions. Although the amount of thrombotic material to be digested is an important consideration for chemical lysis, mechanical debulking may be more greatly influenced by other target lesion characteristics.

METHODS

In consecutive patients with acute ischemic stroke treated with Merci thrombectomy for middle cerebral artery M1 occlusions, we analyzed the influence on recanalization success and clinical outcome of target thrombus size (length) and shape (curvature and branching) on pretreatment T2* gradient echo MRI.

RESULTS

Among 65 patients, pretreatment MRI showed susceptibility vessel signs in 45 (69%). Thrombus length averaged 13.03 mm (range, 5.56-34.91) and irregular shape (curvature or branching) was present in 17 of 45 (38%). Presence and length of susceptibility vessel signs did not predict recanalization or good clinical outcome. Substantial recanalization (Thrombolysis In Cerebral Infarction 2b or 3) and good clinical outcome (modified Rankin Scale score ≤2) were more frequent with regular than irregular susceptibility vessel signs shape (57% versus 18%, P=0.013; 39% versus 6%, P=0.017). On multiple regression analysis, the only independent predictor of substantial recanalization was irregular susceptibility vessel signs (OR, 0.16; 95% CI, 0.04-0.69; P=0.014); and leading predictors of good clinical outcome were baseline National Institutes of Health Stroke Scale (OR, 1.20; 95% CI, 1.03-1.40; P= 0.019) and irregular susceptibility vessel signs (OR, 9.36; 95% CI, 0.98-89.4; P=0.052).

CONCLUSIONS

Extension of thrombus into middle cerebral artery division branches and curving shape of the middle cerebral artery stem, but not thrombus length, decrease technical and clinical success of Merci thrombectomy in M1 occlusions.

MRSI correlates of cognitive-behavioral therapy in pediatric obsessive-compulsive disorder

BACKGROUND

The brain mechanisms of cognitive-behavioral therapy (CBT), a highly effective treatment for pediatric obsessive-compulsive disorder (OCD), are unknown. Neuroimaging in adult OCD indicates that CBT is associated with metabolic changes in striatum, thalamus, and anterior cingulate cortex. We therefore probed putative metabolic effects of CBT on these brain structures in pediatric OCD using proton magnetic resonance spectroscopic imaging (1H MRSI).

METHOD

Five unmedicated OCD patients (4 ♀, 13.5±2.8) and 9 healthy controls (7 ♀, 13.0±2.5) underwent MRSI (1.5 T, repetition-time/echo-time=1500/30 ms) of bilateral putamen, thalamus and pregenual anterior cingulate cortex (pACC). Patients were rescanned after 12 weeks of exposure-based CBT. The Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS) of OCD symptoms was administered before and after CBT.

RESULTS

Four of 5 patients responded to CBT (mean 32.8% CY-BOCS reduction). Multiple metabolite effects emerged. Pre-CBT, N-acetyl-aspartate+N-acetyl-aspartyl-glutamate (tNAA) in left pregenual anterior cingulate cortex (pACC) was 55.5% higher in patients than controls. Post-CBT, tNAA (15.0%) and Cr (23.9%) in left pACC decreased and choline compounds (Cho) in right thalamus increased (10.6%) in all 5 patients. In left thalamus, lower pre-CBT tNAA, glutamate+glutamine (Glx), and myo-inositol (mI) predicted greater post-CBT drop in CY-BOCS (r=0.98) and CY-BOCS decrease correlated with increased Cho.

CONCLUSIONS

Interpretations are offered in terms of the Glutamatergic Hypothesis of Pediatric OCD. Similar to 18FDG-PET in adults, objectively measurable regional MRSI metabolites may indicate pediatric OCD and predict its response to CBT.

Association of laterality and size of perfusion lesions on neurological deficit in acute supratentorial stroke

BACKGROUND

The influence of lesion size and laterality on each component of the National Institutes of Health Stroke Scale has not been delineated. The objective of this study was to use perfusion-weighted imaging to characterize the association of ischaemic volume and laterality on each component item and the total score of the <National Institutes of Health Stroke Scale.

METHODS

We analysed consecutive right-handed patients with first-ever supratentorial acute ischaemic strokes who underwent acute perfusion-weighted imaging at a single centre. Perfusion deficits were defined as mean transit time > 10 s. Ordinal regression was used to clarify the relationship between ischaemic volume, laterality, and <National Institutes of Health Stroke Scale scores.

RESULTS

Among 111 patients, 58 were left-hemisphere stroke, and 53 right-hemisphere stroke. Median ischaemic volume was 53 ml in left-hand stroke and 65 ml in right-hand stroke and median total National Institutes of Health Stroke Scale was 10 in left-hand stroke and eight in right-hand stroke. For individual National Institutes of Health Stroke Scale items, ischaemic volume correlated most closely with commands and visual field and most weakly with ataxia and neglect. Left-hand stroke predicted higher scores of total National Institutes of Health Stroke Scale and National Institutes of Health Stroke Scale items of questions, commands, right limb weakness, and language. Right-hand stroke predicted higher scores of left limb weakness and extinction.

CONCLUSIONS

Larger perfusion defects contribute to higher scores on the total and most individual items of the National Institutes of Health Stroke Scale. However, lesion laterality contributes substantially to half the item scores, with greater association of left than right-brain side. These findings indicate that imaging-deficit correlations will be improved by designating lesions into an atlas, taking into account side in addition to size.

Non-invasive detection of 2-hydroxyglutarate and other metabolites in IDH1 mutant glioma patients using magnetic resonance spectroscopy

Mutations of the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) are commonly found in primary brain cancers. We previously reported that a novel enzymatic activity of these mutations results in the production of the putative oncometabolite, R(-)-2-hydroxyglutarate (2-HG). Here we investigated the ability of magnetic resonance spectroscopy (MRS) to detect 2-HG production in order to non-invasively identify patients with IDH1 mutant brain tumors. Patients with intrinsic glial brain tumors (n = 27) underwent structural and spectroscopic magnetic resonance imaging prior to surgery. 2-HG levels from MRS data were quantified using LC-Model software, based upon a simulated spectrum obtained from a GAMMA library added to the existing prior knowledge database. The resected tumors were then analyzed for IDH1 mutational status by genomic DNA sequencing, Ki-67 proliferation index by immunohistochemistry, and concentrations of 2-HG and other metabolites by liquid chromatography-mass spectrometry (LC-MS). MRS detected elevated 2-HG levels in gliomas with IDH1 mutations compared to those with wild-type IDH1 (P = 0.003). The 2-HG levels measured in vivo with MRS were significantly correlated with those measured ex vivo from the corresponding tumor samples using LC-MS (r (2) = 0.56; P = 0.0001). Compared with wild-type tumors, those with IDH1 mutations had elevated choline (P = 0.01) and decreased glutathione (P = 0.03) on MRS. Among the IDH1 mutated gliomas, quantitative 2-HG values were correlated with the Ki-67 proliferation index of the tumors (r ( 2 ) = 0.59; P = 0.026). In conclusion, water-suppressed proton ((1)H) MRS provides a non-invasive measure of 2-HG in gliomas, and may serve as a potential biomarker for patients with IDH1 mutant brain tumors. In addition to 2-HG, alterations in several other metabolites measured by MRS correlate with IDH1 mutation status.

Pontocerebellar hypoplasia in association with de novo 19p13.11p13.12 microdeletion

The pontocerebellar hypoplasias (PCHs) are a group of clinically variable disorders characterized by abnormally small cerebellum and brainstem, generally inherited in an autosomal recessive pattern. While PCHs have been grouped into six subtypes, clinical diagnosis is equivocal until a genetic diagnosis is established. We report a patient with PCH, intrauterine growth restriction, ventricular septal defect, rib anomalies, midgut malrotation, and facial dysmorphic features. Using SNP analysis, we identified three de novo deletions of: 1.055 Mb at 6q24.3q25.1 (148174730-149229583); 169 kb at 16p13.2 (6565411-6733934); and 2.530 Mb at 19p13.11p13.12 (13857587-16387798), which were confirmed by FISH. 19p13 deletions are rare aberrations. Of patients previously described with overlapping 19p13.12 deletions and multiple anomalies, only one presented with PCH. Deleted in both that patient and the patient reported here, is DDX39, a DEAD-box RNA helicase. DDX39 is part of the homeostatic machinery that regulates the switch of cellular proliferation and differentiation. It is highly expressed in the developing central nervous system and optic cup of Xenopus laevis. The brain abnormalities in the patient reported here were more severe than the previously reported patient, which may be due to additional deletions or undetected point mutations in the nondeleted allele. Notably, the patient reported here also has a partial deletion of RBFOX1 (A2BP1), which lies within the autism susceptibility locus on 16p13.2. Our findings suggest chromosomal microarray analysis may be useful in determining etiology of syndromic PCH.