Technology-enhanced visual desensitization home exercise program for post-concussive visually induced dizziness: a case series

Purpose: Post-concussive visually induced dizziness (VID), in which symptoms are provoked by exposure to complex visual motion, is associated with protracted recovery. Although vestibular rehabilitation therapy (VRT) is recommended to treat post-concussive dizziness, there is sparse literature reporting on specific VRT interventions treating VID. Methods: A consecutive series of 26 individuals referred for VRT post-concussion were retrospectively assessed for inclusion in this case series. Each participant underwent a combination of conventional VRT and a technology-enhanced visual desensitization home exercise program (HEP). Self-report and objective measures were recorded from initial and discharge therapy evaluations. Twenty-three individuals (mean age 23.1 ± 12.4) with post-concussive dizziness (mean 109 ± 56 days post-injury) and no evidence for peripheral vestibular dysfunction were included. Treatment duration averaged 6.9 ± 2.5 weeks. Results: There were significant improvements in post-intervention on subjective and objective measures of dizziness and gait (p < .05). The response to intervention was independent of pre-injury migraine history but pre-injury depression/anxiety increased self-report of post-treatment anxiety. Concurrent treatment with medications did not influence response to treatment. Conclusions: The combination therapy intervention improved outcome measures consistent with VRT treatment outcomes in both concussion and non-traumatic vestibular conditions. Individuals referred for VRT post-concussion warrant assessment for VID and may benefit from the addition of technology-enhanced visual desensitization.

Assessing Contribution of Higher Order Clinical Risk Factors to Prediction of Outcome in Aneurysmal Subarachnoid Hemorrhage Patients

The goal of this study was to investigate the application of machine learning models capable of capturing multiplica tive and temporal clinical risk factors for outcome prediction inpatients with aneurysmal subarachnoid hemorrhage (aSAH). We examined a cohort of 575 aSAH patients from Emory Healthcare, identified via digital subtraction angiog- raphy. The outcome measure was the modified Ranking Scale (mRS) after 90 days. Predictions were performed with longitudinal clinical and imaging risk factors as inputs into a regularized Logistic Regression, a feedforward Neural Network and a multivariate time-series prediction model known as the long short-term memory (LSTM) architecture. Through extraction of higher-order risk factors, the LSTM model achieved an AUC of 0.89 eight days into hospitaliza tion, outperforming other techniques. Our preliminary findings indicate the proposed model has the potential to aid treatment decisions and effective imaging resource utilization in high-risk patients by providing actionable predictions prior to the development of neurological deterioration.

Neuroimaging of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) accounts for 10% to 20% of strokes worldwide and is associated with high morbidity and mortality rates. Neuroimaging is indispensable for rapid diagnosis of ICH and identification of the underlying etiology, thus facilitating triage and appropriate treatment of patients. The most common neuroimaging modalities include noncontrast computed tomography (CT), CT angiography (CTA), digital subtraction angiography, and magnetic resonance imaging (MRI). The strengths and disadvantages of each modality will be reviewed. Novel technologies such as dual-energy CT/CTA, rapid MRI techniques, near-infrared spectroscopy, and automated ICH detection hold promise for faster pre- and in-hospital ICH diagnosis that may impact patient management.

The Surgical Intervention for Traumatic Injury Scale: A Clinical Tool for Traumatic Brain Injury

Introduction

There is no widely used method for communicating the possible need for surgical intervention in patients with traumatic brain injury (TBI). This study describes a scoring system designed to communicate the potential need for surgical decompression in TBI patients. The scoring system, named the Surgical Intervention for Traumatic Injury (SITI), was designed to be objective and easy to use.

Methods

The SITI scale uses radiographic and clinical findings, including the Glasgow Coma Scale Score, pupil examination, and findings noted on computed tomography. To examine the scale, we used the patient database for the Progesterone for the Treatment of Traumatic Brain Injury III (ProTECT III) trial, and retrospectively applied the SITI scale to these patients.

Results

Of the 871 patients reviewed, 164 (18.8%) underwent craniotomy or craniectomy, and 707 (81.2%) were treated nonoperatively. The mean SITI score was 5.1 for patients who underwent surgery and 2.5 for patients treated nonoperatively (P<0.001). The area under the receiver operating characteristic curve was 0.887.

Conclusion

The SITI scale was designed to be a simple, objective, clinical decision tool regarding the potential need for surgical decompression after TBI. Application of the SITI scale to the ProTECT III database demonstrated that a score of 3 or more was well associated with a perceived need for surgical decompression. These results further demonstrate the potential utility of the SITI scale in clinical practice.

Variability of Resting-State Functional MRI Graph Theory Metrics across 3T Platforms

BACKGROUND AND PURPOSE

Graph theory analysis of brain connectivity data is a promising tool for studying the function of the healthy and diseased brain. The consistency of resting-state functional MRI (rsfMRI) connectivity measures across multiple scanner types is an important factor in designing multi-institutional research studies and has important implications for the potential use of this technique in a heterogeneous clinical setting. We sought to quantitatively study the interscanner variability of rsfMRI graph theory metrics obtained from healthy volunteers scanned on three different scanner platforms.

METHODS

In this prospective Institutional Review Board approved study, 9 healthy volunteers were enrolled for brain MRI on three 3T scanners (Magnetom Prisma, Skyra, and Trio, Siemens, Erlangen, Germany) in three separate scan sessions within approximately 1 week. Standard preprocessing of rsfMRI was performed with SPM12. Subject scans were normalized to Montreal Neurologic Institute (MNI) space, and connectivity of 116 regions-of-interests based on the automated anatomic labeling (AAL) atlas was calculated using Conn toolbox. Whole-network graph theory metrics were calculated using Brain Connectivity Toolbox, and intraclass correlation (ICC) across three scan sessions was assessed.

RESULTS

A total of 25 rsfMRI exams were completed in 9 subjects with a median-intersession time of 3 days. Among all three sessions, there was good to excellent agreement in characteristic path length and global efficiency (ICC: .79, .79) and good agreement in the transitivity, local efficiency, and clustering coefficient (ICC = .72, .69, .62).

CONCLUSIONS

There was high consistency of graph theory metrics of rsfMRI connectivity networks among healthy volunteers scanned on three different generation 3T MRI scanners.

Divalent EuRh2Si2 as a reference for the Luttinger theorem and antiferromagnetism in trivalent heavy-fermion YbRh2Si2

Application of the Luttinger theorem to the Kondo lattice YbRh2Si2 suggests that its large 4f-derived Fermi surface (FS) in the paramagnetic (PM) regime should be similar in shape and volume to that of the divalent local-moment antiferromagnet (AFM) EuRh2Si2 in its PM regime. Here we show by angle-resolved photoemission spectroscopy that paramagnetic EuRh2Si2 has a large FS essentially similar to the one seen in YbRh2Si2 down to 1 K. In EuRh2Si2 the onset of AFM order below 24.5 K induces an extensive fragmentation of the FS due to Brillouin zone folding, intersection and resulting hybridization of the Fermi-surface sheets. Our results on EuRh2Si2 indicate that the formation of the AFM state in YbRh2Si2 is very likely also connected with similar changes in the FS, which have to be taken into account in the controversial analysis and discussion of anomalies observed at the quantum critical point in this system.

Patients with Mild Cognitive Impairment May be Stratified by Advanced Diffusion Metrics and Neurocognitive Testing

BACKGROUND AND PURPOSE

Mild cognitive impairment (MCI) is a prevalent disorder, with a subset of patients progressing to dementia each year. Although MCI may be subdivided into amnestic or vascular types as well as into single or multiple cognitive domain involvement, most prior studies using advanced diffusion imaging have not accounted for these categories. The purpose of the current study was to determine if the pattern of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) metrics in patients with amnestic MCI (aMCI) correlate to specific cognitive domain impairments.

METHODS

Nineteen consecutive patients with aMCI referred for brain magnetic resonance imaging (MRI) were included. All subjects underwent neurocognitive testing. A z-score was calculated for each domain and a composite of all four domains. Brain MRI included standard structural imaging and diffusion imaging. Volumetric, DTI, and DKI metrics were calculated and statistical analysis was performed with adjustments for multiple measures and comparisons.

RESULTS

Statistically significant correlations between diffusion metrics and cognitive z-scores were detected: visuospatial-visuoconstructional z-scores only correlated with alterations in the corpus callosum splenium, executive functioning z-scores with the corpus callosum genu, memory testing z-scores with the left hippocampus, and composite z-scores with the anterior centrum semiovale.

CONCLUSION

Neuroimaging studies of patients with aMCI to date have assumed a population with homogeneous cognitive impairment. Our results demonstrate selective patterns of regional diffusion metric alterations correlate to specific cognitive domain impairments. Future studies should account for this heterogeneity, and this may also be useful for prognostication.

Cerebral MR oximetry during acetazolamide augmentation: Beyond cerebrovascular reactivity in hemodynamic failure

BACKGROUND

Oxygen extraction fraction (OEF) elevation predicts increased ischemic stroke incidence among patients with carotid steno-occlusive disease, and can be estimated from quantitative susceptibility mapping (QSM) MRI.

PURPOSE

To explore QSM oximetry during acetazolamide (ACZ) challenge, hypothesizing that detectable OEF alterations will reflect hemodynamic compromise in unilateral cerebrovascular disease (CVD) patients.

STUDY TYPE

Retrospective.

SUBJECTS

Fourteen unilateral CVD patients, and 24 healthy controls (HC).

FIELD STRENGTH/SEQUENCE

Multiecho gradient echo (GRE) and T₁ -weighted images at 3T.

ASSESSMENT

We constructed QSM images and R2* maps from multiecho GRE images. QSM-OEF maps were generated from the susceptibility difference between venous blood and background brain tissue. Intrasubject diseased/contralateral hemisphere OEF ratios in the middle cerebral artery (MCA) territories were calculated. Intravascular susceptibility in the straight sinus (SS) and MCA was also measured.

STATISTICAL TESTS

The result significance was determined using t-tests and Pearson's correlation.

RESULTS

Mean and standard deviation for the patient diseased/contralateral OEF ratios were 1.15 ± 0.14 at baseline and 1.23 ± 0.17 post-ACZ. Disease group R2* ratios were 0.95 ± 0.05 at baseline and 1.03 ± 0.08 post-ACZ. Left/right OEF and R2* ratios for the HC group were 0.98 ± 0.06 and 0.99 ± 0.038, respectively. Susceptibility (ppb) in the SS and MCA in patients was 162.63 ± 35.4 and -22.33 ± 13.70, respectively, at baseline, 124.56 ± 37.43 and -19.27 ± 23.14 post-ACZ. The HC group SS and MCA susceptibility was 146.10 ± 24.79 and -19.59 ± 12.37, respectively. Patient group OEF ratios were greater than 1.0 before and after ACZ challenge (P < 0.01 and < 0.001, respectively, one-sample t-test), and were greater than HC ratios (P < 0.001 unpaired t-test). OEF and R2* ratios increased from baseline to post-ACZ (P = 0.024, 0.004, respectively, paired t-test). Detectable blood oxygenation change was confirmed by finding SS susceptibility decreased from baseline to post-ACZ (P < 0.001, paired t-test), while MCA susceptibility did not change significantly (P = 0.67, paired t-test).

DATA CONCLUSION

These results suggest QSM is sensitive to dynamic OEF modulation during hemodynamic augmentation.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:175-182.

Effects of Cranioplasty on Cerebral Blood Flow Following Decompressive Craniectomy: A Systematic Review of the Literature

BACKGROUND

Cranioplasty after decompressive craniectomy (DC) is routinely performed for reconstructive purposes and has been recently linked to improved cerebral blood flow (CBF) and neurological function.

OBJECTIVE

To systematically review all available literature to evaluate the effect of cranioplasty on CBF and neurocognitive recovery.

METHODS

A PubMed, Google Scholar, and MEDLINE search adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines included studies reporting patients who underwent DC and subsequent cranioplasty in whom cerebral hemodynamics were measured before and after cranioplasty.

RESULTS

The search yielded 21 articles with a total of 205 patients (range 3-76 years) who underwent DC and subsequent cranioplasty. Two studies enrolled 29 control subjects for a total of 234 subjects. Studies used different imaging modalities, including CT perfusion (n = 10), Xenon-CT (n = 3), single-photon emission CT (n = 2), transcranial Doppler (n = 6), MR perfusion (n = 1), and positron emission tomography (n = 2). Precranioplasty CBF evaluation ranged from 2 days to 6 months; postcranioplasty CBF evaluation ranged from 7 days to 6 months. All studies demonstrated an increase in CBF ipsilateral to the side of the cranioplasty. Nine of 21 studies also reported an increase in CBF on the contralateral side. Neurological function improved in an overwhelming majority of patients after cranioplasty.

CONCLUSION

This systematic review suggests that cranioplasty improves CBF following DC with a concurrent improvement in neurological function. The causative impact of CBF on neurological function, however, requires further study.

Abstract TP126: Carotid Webs in Cryptogenic Ischemic Strokes

Introduction: Carotid web is an intraluminal projection in the posterior aspect of the internal carotid bulb and represents an intimal variant of fibromuscular dysplasia. It may serve as a source of thrombus formation leading to embolic strokes and has been poorly described. We aim to study the prevalence of carotid webs among patients with cryptogenic ischemic strokes (CIS).

Methods: This was a retrospective analysis of patients aged 18-60 years who presented to two comprehensive stroke centers with CIS (TOAST criteria) and underwent neck CTA, from January 2016 to May 2017. Carotid web was defined as a shelf-like projection with linear/smooth filling on the posterior bulb without superimposed atherosclerosis (defined as adjacent calcifications or wall thickness >3mm). CTAs were reviewed by a neurointerventionist blinded to clinical and other radiological studies. CIS patients with carotid webs (with strokes within the vascular territory) were then compared to the remaining CIS patients.

Results: Of 162 CIS patients within the study period, 43 patients met the inclusion criteria. Thirteen patients had carotid webs (29.5%), 10 of whom had a stroke in the same vascular territory as the web (22.7%). Median length of the intraluminal web projection was 1.6[1.5-2.0]mm. Age, gender and comorbidities were similar between the patients with stroke within the carotid web territory (n=10) and the remainder of the CIS patients (n=33)( Table ). None of the patients with ischemic stroke in the carotid web territory were white, while 90% were black (compared to 18% and 74% of the 43 CIS patients, respectively). The NIHSS in the carotid web group was 14.2 [7.9-20.5] as compared to the other CIS arm 10.1 [3.3-16.9]; p=0.09.

Conclusion: Carotid webs are an under-recognized etiology in CIS affecting the young. Routine and careful vascular imaging analysis of the carotid bulb in young CIS patients is indicated. Further studies are needed.

Is there added value in obtaining cervical spine MRI in the assessment of nontraumatic angiographically negative subarachnoid hemorrhage? A retrospective study and meta-analysis of the literature

OBJECTIVE Diagnostic algorithms for nontraumatic angiographically negative subarachnoid hemorrhage (AN-SAH) vary, and the optimal method remains subject to debate. This study assessed the added value of cervical spine MRI in identifying a cause for nontraumatic AN-SAH. METHODS Consecutive patients 18 years of age or older who presented with nontraumatic SAH between February 1, 2009, and October 31, 2014, with negative cerebrovascular catheter angiography and subsequent cervical MRI were studied. Patients with intraparenchymal, subdural, or epidural hemorrhage; recent trauma; or known vascular malformations were excluded. All cervical MR images were reviewed by two blinded neuroradiologists. The diagnostic yield of cervical MRI was calculated. A literature review was conducted to identify studies reporting the diagnostic yield of cervical MRI in patients with AN-SAH. The weighted pooled estimate of diagnostic yield of cervical MRI was calculated. RESULTS For all 240 patients (mean age 53 years, 48% male), catheter angiography was performed within 4 days after admission (median 12 hours, interquartile range [IQR] 10 hours). Cervical MRI was performed within 19 days of admission (median 24 hours, IQR 10 hours). In a single patient, cervical MRI identified a source for SAH (cervical vascular malformation). Meta-analysis of 7 studies comprising 538 patients with AN-SAH produced a pooled estimate of 1.3% (95% confidence interval 0.5%-2.5%) for diagnostic yield of cervical MRI. No statistically significant between-study heterogeneity or publication bias was identified. CONCLUSIONS Cervical MRI following AN-SAH, in the absence of findings to suggest spinal etiology, has a very low diagnostic yield and is not routinely necessary.

Carotid Web (Intimal Fibromuscular Dysplasia) Has High Stroke Recurrence Risk and Is Amenable to Stenting

BACKGROUND AND PURPOSE

Carotid webs have been increasingly recognized as a cause of recurrent stroke, but evidence remains scarce. We aim to report the clinical outcomes and first series of carotid stenting in a cohort of patients with strokes from symptomatic carotid webs.

METHODS

Prospective and consecutive data of patients <65 years old with cryptogenic stroke admitted within September 2014 to May 2017. Carotid web was defined by a shelf-like/linear filling defect in the posterior internal carotid artery bulb by computed tomographic angiography.

RESULTS

Twenty-four patients were identified (91.6% strokes/8.4% transient ischemic attacks [TIAs]). Median age was 46 (41-59) years, 61% were female, and 75% were black. Median National Institutes of Health Stroke Scale score was 10.5 (3.0-16.0) and ASPECTS (Alberta Stroke Program Early CT Score) was 8 (7-8). There were no parenchymal hemorrhages, and 96% of patients were independent at 3 months. All webs caused <50% stenosis. In patients with bilateral webs (58%), median ipsilateral web length was larger than contralateral (3.1 [3.0-4.5] mm versus 2.6 [1.85-2.9] mm; P=0.01), respectively. Twenty-nine percent of patients had thrombus superimposed on the symptomatic carotid web. A recurrent stroke/TIA involving the territory of the previously symptomatic web occurred in 7 (32%; 6 strokes/1 TIA) patients: 3 <1 week, 2 <first year, and 3 >1 year of follow-up. Two recurrences occurred on dual antiplatelet therapy, 3 on antiplatelet monotherapy, 1 within 24 hours of thrombolysis, and 1 off antithrombotics. Median follow-up was 12.2 (8.0-18.0) months. Sixteen (66%) patients were stented at a median 12.2 (7.0-18.7) days after stroke with no periprocedural complications. No recurrent strokes/TIAs occurred in stented individuals (median follow-up of 4 [2.4-12.0] months).

CONCLUSIONS

Carotid web is associated with high recurrent stroke/TIA risk, despite antithrombotic use, and is amenable to carotid stenting.

Diagnostic Quality of 3D T2-SPACE Compared with T2-FSE in the Evaluation of Cervical Spine MRI Anatomy

BACKGROUND AND PURPOSE

Spinal anatomy has been variably investigated using 3D MRI. We aimed to compare the diagnostic quality of T2 sampling perfection with application-optimized contrasts by using flip angle evolution (SPACE) with T2-FSE sequences for visualization of cervical spine anatomy. We predicted that T2-SPACE will be equivalent or superior to T2-FSE for visibility of anatomic structures.

MATERIALS AND METHODS

Adult patients undergoing cervical spine MR imaging with both T2-SPACE and T2-FSE sequences for radiculopathy or myelopathy between September 2014 and February 2015 were included. Two blinded subspecialty-trained radiologists independently assessed the visibility of 12 anatomic structures by using a 5-point scale and assessed CSF pulsation artifact by using a 4-point scale. Sagittal images and 6 axial levels from C2-T1 on T2-FSE were reviewed; 2 weeks later and after randomization, T2-SPACE was evaluated. Diagnostic quality for each structure and CSF pulsation artifact visibility on both sequences were compared by using a paired t test. Interobserver agreement was calculated (κ).

RESULTS

Forty-five patients were included (mean age, 57 years; 40% male). The average visibility scores for intervertebral disc signal, neural foramina, ligamentum flavum, ventral rootlets, and dorsal rootlets were higher for T2-SPACE compared with T2-FSE for both reviewers (P < .001). Average scores for remaining structures were either not statistically different or the superiority of one sequence was discordant between reviewers. T2-SPACE showed less degree of CSF flow artifact (P < .001). Interobserver variability ranged between -0.02-0.20 for T2-SPACE and -0.02-0.30 for T2-FSE (slight to fair agreement).

CONCLUSIONS

T2-SPACE may be equivalent or superior to T2-FSE for the evaluation of cervical spine anatomic structures, and T2-SPACE shows a lower degree of CSF pulsation artifact.

Yield of computed tomography of the cervical spine in cases of simple assault

BACKGROUND

Computed tomography (CT) of the cervical spine (C-spine) is routinely ordered for low-impact, non-penetrating or "simple" assault at our institution and others. Common clinical decision tools for C-spine imaging in the setting of trauma include the National Emergency X-Radiography Utilization Study (NEXUS) and the Canadian Cervical Spine Rule for Radiography (CCR). While NEXUS and CCR have served to decrease the amount of unnecessary imaging of the C-spine, overutilization of CT is still of concern.

METHODS

A retrospective, cross-sectional study was performed of the electronic medical record (EMR) database at an urban, Level I Trauma Center over a 6-month period for patients receiving a C-spine CT. The primary outcome of interest was prevalence of cervical spine fracture. Secondary outcomes of interest included appropriateness of C-spine imaging after retrospective application of NEXUS and CCR. The hypothesis was that fracture rates within this patient population would be extremely low.

RESULTS

No C-spine fractures were identified in the 460 patients who met inclusion criteria. Approximately 29% of patients did not warrant imaging by CCR, and 25% by NEXUS. Of note, approximately 44% of patients were indeterminate for whether imaging was warranted by CCR, with the most common reason being lack of assessment for active neck rotation.

CONCLUSIONS

Cervical spine CT is overutilized in the setting of simple assault, despite established clinical decision rules. With no fractures identified regardless of other factors, the likelihood that a CT of the cervical spine will identify clinically significant findings in the setting of "simple" assault is extremely low, approaching zero. At minimum, adherence to CCR and NEXUS within this patient population would serve to reduce both imaging costs and population radiation dose exposure.

Enhanced responsivity resonant RF photodetectors

The responsivity of room-temperature, semiconductor-based photodetectors consisting of resonant RF circuits coupled to microstrip buslines is investigated. The dependence of the photodetector response on the semiconductor material and RF circuit geometry is presented, as is the detector response as a function of the spatial position of the incident light. We demonstrate significant improvement in detector response by choice of photoconductive material, and for a given material, by positioning our optical signal to overlap with positions of RF field enhancement. Design of RF circuits with strong field enhancement are demonstrated to further improve detector response. The improved detector response demonstrated offers opportunities for applications in RF photonics, materials metrology, or single read-out multiplexed detector arrays.

Fermi Surface of Metallic V_{2}O_{3} from Angle-Resolved Photoemission: Mid-level Filling of e_{g}^{π} Bands

Using angle resolved photoemission spectroscopy, we report the first band dispersions and distinct features of the bulk Fermi surface (FS) in the paramagnetic metallic phase of the prototypical metal-insulator transition material V_{2}O_{3}. Along the c axis we observe both an electron pocket and a triangular holelike FS topology, showing that both V 3d a_{1g} and e_{g}^{π} states contribute to the FS. These results challenge the existing correlation-enhanced crystal field splitting theoretical explanation for the transition mechanism and pave the way for the solution of this mystery.

Electronic Structure of YbB_{6}: Is it a Topological Insulator or Not?

To finally resolve the controversial issue of whether or not the electronic structure of YbB_{6} is nontrivially topological, we have made a combined study using angle-resolved photoemission spectroscopy (ARPES) of the nonpolar (110) surface and density functional theory (DFT). The flat-band conditions of the (110) ARPES avoid the strong band bending effects of the polar (001) surface and definitively show that YbB_{6} has a topologically trivial B 2p-Yb 5d semiconductor band gap of ∼0.3  eV. Accurate determination of the low energy band topology in DFT requires the use of a modified Becke-Johnson exchange potential incorporating spin-orbit coupling and an on-site Yb 4f Coulomb interaction U as large as 7 eV. The DFT result, confirmed by a more precise GW band calculation, is similar to that of a small gap non-Kondo nontopological semiconductor. Additionally, the pressure-dependent electronic structure of YbB_{6} is investigated theoretically and found to transform into a p-d overlap semimetal with small Yb mixed valency.

Performance of CT ASPECTS and Collateral Score in Risk Stratification: Can Target Perfusion Profiles Be Predicted without Perfusion Imaging?

BACKGROUND AND PURPOSE

Endovascular trials suggest that revascularization benefits a subset of acute ischemic stroke patients with large-artery occlusion and small-core infarct volumes. The objective of our study was to identify thresholds of noncontrast CT-ASPECTS and collateral scores on CT angiography that best predict ischemic core volume thresholds quantified by CT perfusion among patients with acute ischemic stroke.

MATERIALS AND METHODS

Fifty-four patients with acute ischemic stroke (<12 hours) and MCA/intracranial ICA occlusion underwent NCCT/CTP during their initial evaluation. CTP analysis was performed on a user-independent platform (RApid processing of PerfusIon and Diffusion), computing core infarct (defined as CBF of <30% normal). A target mismatch profile consisting of infarction core of ≤50 mL was selected to define candidates with acute ischemic stroke likely to benefit from revascularization.

RESULTS

NCCT-ASPECTS of ≥9 with a CTA collateral score of 3 had 100% specificity for identifying patients with a CBF core volume of ≤50 mL. NCCT-ASPECTS of ≤6 had 100% specificity for identifying patients with a CBF core volume of >50 mL. In our cohort, 44 (81%) patients had an NCCT-ASPECTS of ≥9, a CTA collateral score of 3, or an NCCT-ASPECTS of ≤6.

CONCLUSIONS

Using an NCCT-ASPECTS of ≥9 or a CTA collateral score of 3 best predicts CBF core volume infarct of ≤50 mL, while an NCCT-ASPECTS of ≤6 best predicts a CBF core volume infarct of >50 mL. Together these thresholds suggest that a specific population of patients with acute ischemic stroke not meeting such profiles may benefit most from CTP imaging to determine candidacy for revascularization.

Performance and Predictive Value of a User-Independent Platform for CT Perfusion Analysis: Threshold-Derived Automated Systems Outperform Examiner-Driven Approaches in Outcome Prediction of Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Treatment strategies in acute ischemic stroke aim to curtail ischemic progression. Emerging paradigms propose patient subselection using imaging biomarkers derived from CT, CTA, and CT perfusion. We evaluated the performance of a fully-automated computational tool, hypothesizing enhancements compared with qualitative approaches. The correlation between imaging variables and clinical outcomes in a cohort of patients with acute ischemic stroke is reported.

MATERIALS AND METHODS

Sixty-two patients with acute ischemic stroke and MCA or ICA occlusion undergoing multidetector CT, CTA, and CTP were retrospectively evaluated. CTP was processed on a fully operator-independent platform (RApid processing of PerfusIon and Diffusion [RAPID]) computing automated core estimates based on relative cerebral blood flow and relative cerebral blood volume and hypoperfused tissue volumes at varying thresholds of time-to-maximum. Qualitative analysis was assigned by 2 independent reviewers for each variable, including CT-ASPECTS, CBV-ASPECTS, CBF-ASPECTS, CTA collateral score, and CTA clot burden score. Performance as predictors of favorable clinical outcome and final infarct volume was established for each variable.

RESULTS

Both RAPID core estimates, CT-ASPECTS, CBV-ASPECTS, and clot burden score correlated with favorable clinical outcome (P < .05); CBF-ASPECTS and collateral score were not significantly associated with favorable outcome, while hypoperfusion estimates were variably associated, depending on the selected time-to-maximum thresholds. Receiver operating characteristic analysis demonstrated disparities among tested variables, with RAPID core and hypoperfusion estimates outperforming all qualitative approaches (area under the curve, relative CBV = 0.86, relative CBF = 0.81; P < .001).

CONCLUSIONS

Qualitative approaches to acute ischemic stroke imaging are subject to limitations due to their subjective nature and lack of physiologic information. These findings support the benefits of high-speed automated analysis, outperforming conventional methodologies while limiting delays in clinical management.

Persistent non-metallic behavior in Sr2IrO4 and Sr3Ir2O7 at high pressures

Iridium-based 5d transition-metal oxides are attractive candidates for the study of correlated electronic states due to the interplay of enhanced crystal-field, Coulomb and spin-orbit interaction energies. At ambient pressure, these conditions promote a novel Jeff = 1/2 Mott-insulating state, characterized by a gap of the order of ~0.1 eV. We present high-pressure electrical resistivity measurements of single crystals of Sr2IrO4 and Sr3Ir2O7. While no indications of a pressure-induced metallic state up to 55 GPa were found in Sr2IrO4, a strong decrease of the gap energy and of the resistance of Sr3Ir2O7 between ambient pressure and 104 GPa confirm that this compound is in the proximity of a metal-insulator transition.

Superconductivity. Fermi arcs in a doped pseudospin-1/2 Heisenberg antiferromagnet

High-temperature superconductivity in cuprates arises from an electronic state that remains poorly understood. We report the observation of a related electronic state in a noncuprate material, strontium iridate (Sr2IrO4), in which the distinct cuprate fermiology is largely reproduced. Upon surface electron doping through in situ deposition of alkali-metal atoms, angle-resolved photoemission spectra of Sr2IrO4 display disconnected segments of zero-energy states, known as Fermi arcs, and a gap as large as 80 millielectron volts. Its evolution toward a normal metal phase with a closed Fermi surface as a function of doping and temperature parallels that in the cuprates. Our result suggests that Sr2IrO4 is a useful model system for comparison to the cuprates.

Guided-mode resonant coherent light absorbers

We present a new class of coherent perfect absorbers based on guided-mode resonance in thin semiconductor films. Using particle-swarm optimization methods, we design a thin-film amorphous silicon grating that maximizes coherent modulation of the absorbance. The optimized device exhibits a maximum scattering power of ∼94% and a power absorption limit approaching 100% at the 1550-nm wavelength.

Photoemission spectroscopy and the unusually robust one-dimensional physics of lithium purple bronze

Temperature-dependent photoemission spectroscopy in Li(0.9)Mo(6)O(17) contributes to evidence for one-dimensional (1D) physics that is unusually robust. Three generic characteristics of the Luttinger liquid are observed: power law behavior of the k-integrated spectral function down to temperatures just above the superconducting transition, k-resolved lineshapes that show holon and spinon features, and quantum critical (QC) scaling in the lineshapes. Departures of the lineshapes and the scaling from expectations in the Tomonaga-Luttinger model can be partially described by a phenomenological momentum broadening that is presented and discussed. The possibility that some form of 1D physics obtains even down to the superconducting transition temperature is assessed.

Abstract P3-13-07: Clinicopathologic and Biologic Recurrence Risk in African-American Versus Caucasian Women with Early-Stage Hormone Receptor Positive Breast Cancer, a Single Institution Experience

Background: African-American women with hormone receptor positive breast cancer have an inferior survival compared to Caucasians (Sparano, et al (SABCS, 2009, Abstract #37) and Albain, et al (ASCO, 2010, Abstract #511)). It is not clear whether this difference is a result of disparities in access to care and stage at presentation or biological factors. We sought to examine whether African-American women with early-stage hormonereceptor positive breast cancer had a higher risk of recurrence than similarly staged Caucasians using a standard clinicopathologic risk prediction algorithm (AdjuvantOnline!) and a biologic risk prediction algorithm (Oncotype DX).

Materials and Methods: Women with early stage, hormone receptor positive, Her2 normal, lymph node negative breast cancer seen at the University of Tennessee Cancer Institute between 2007-2009 were retrospectively reviewed. All patients had an AdjuvantOnline! recurrence risk calculated. For patients in whom an Oncotype DX was available, differences in risk of recurrence between clinicopathologic and biologic algorithms were evaluated with respect to race (African-American versus Caucasian).

Results: 96 women were identified, 38 of whom were African-American and 58 of whom were Caucasian. 50 women had an Oncotype DX available. Clinicopathologic factors were well-balanced between the groups (see Table 1). Using AdjuvantOnline!, there was no significant difference between African-American and Caucasian patients in their average risk of recurrence (25% versus 23%, P=0.15). Using Oncotype DX, there was similarly no significant difference in the average risk of recurrence by race (18.6% for African-American versus 18.9% for Caucasian, P=0.55).

Patient Characteristics

Grade was not available for 1 Caucasian patient.

Discussion: When matched for stage and general clinicopathologic factors (hormone receptor positivity, Her2 normal, lymph node negative), African-American and Caucasian patients have similar risk of recurrence using AdjuvantOnline! and Oncotype DX, though the expected risk was somewhat lower with Oncotype DX in both groups. This would suggest that there may be little biologic difference between African-American and Caucasian women with early stage hormone receptor positive breast cancer and that any difference in survival is likely related to non-biological factors.

Utilizing fungus myceliated grain for molt induction and performance in commercial laying hens

Molting in poultry is used to rejuvenate hens for a second or third laying cycle. Feed withdrawal was once the most effective method used for molt induction; however, it has being phased out due to food safety and animal welfare concerns. This study evaluated the utilization of fungus myceliated grain as a safe and effective alternative for inducing molt, enhancing immunity, reducing Salmonella growth, and returning to egg production. Laying hens were subjected to 1 of 5 treatments: 1) nonfed (NF), 2) full-fed (FF), 3) fungus myceliated meal (FM), 4) 90% fungus myceliated meal+10% standard layer ration (FM-90), and 5) 90% alfalfa meal+10% fungus myceliated meal (AF-90). Each treatment condition was replicated 9 times during a 9-d molt period. The results revealed that egg production for treatments 1 and 3 ceased completely by d 5, whereas hens in treatments 4 and 5 ceased egg production by d 6. The percentage of BW loss decreased significantly (P<0.05) in treatments 1 (57%), 2 (8%), 3 (35%), 4 (37%), and 5 (44%). Ovary weights of hens fed all molting diets decreased significantly from the full-fed control but did not differ significantly (P<0.05) from each other. Salmonella population in the crop, ovary, and ceca from hens differed significantly (P<0.05) among treatments. Return to egg production differed between treatments with higher production beginning in treatment 3 and ending in treatment 5. Antibody titers did differ (P<0.05) among treatments. From these results, fungus myceliated meal appears to be a viable alternative to conventional feed withdrawal and other methods for the successful induction of molt and retention of postmolt performance.

Quantum critical scaling in the single-particle spectrum of a novel anisotropic metal

We report an angle resolved photoemission spectroscopy study of quantum critical scaling in the single-particle spectral function of a novel anisotropic metal Li_{0.9}Mo_{6}O_{17}. We find a temperature (T) scaling exponent value and also low-T angle resolved photoemission spectroscopy line shapes that are very challenging for current one-dimensional theory frameworks. These results add a new spectroscopic component to a growing collection of puzzling low-T transport behaviors of this material.

Treatment of physicians with epilepsy

BACKGROUND

Physicians with epilepsy (physician-patients) are an understudied, unique patient population due to the potential adverse outcomes that seizures or medication side effects might have on patients under their care, as well as their ability to modify treatments without consulting treating physicians. We examine the effect epilepsy has upon physician-patients as well as surveying epileptologists on their views and experiences in treating physician-patients.

METHODS

We reviewed charts to assess the clinical course of all physician-patients treated and distributed a questionnaire to active physician-patients at our epilepsy center. We surveyed epileptologists throughout the United States on their experience and views on treating physician-patients.

RESULTS

Seventy-three percent of responding physician-patients experienced seizures while in a medical setting, 55% while interacting with patients, and 18% during invasive procedures. Eighteen percent of physician-patients felt seizures impacted their work and 9% were on disability secondary to epilepsy. Among epileptologists surveyed, 35% would counsel and manage physician-patients differently than other patients and 26% favored establishing guidelines or regulations governing physician-patients. The majority of physician--patients and one-third of epileptologists felt that physician-patients were most analogous to professions that are currently regulated by the federal government.

CONCLUSION

This study highlights the diverse ways that epilepsy can affect physician-patients and the challenges that arise in treating this unique patient population.

Orbitally driven spin-singlet dimerization in S=1 La4Ru2O10

Using x-ray absorption spectroscopy at the Ru-L2,3 edge we reveal that the Ru4+ ions remain in the S=1 spin state across the rare 4d-orbital ordering transition and spin-gap formation. We find using local spin density approximation + Hubbard U band structure calculations that the crystal fields in the low-temperature phase are not strong enough to stabilize the S=0 state. Instead, we identify a distinct orbital ordering with a significant anisotropy of the antiferromagnetic exchange couplings. We conclude that La4Ru2O10 appears to be a novel material in which the orbital physics drives the formation of spin-singlet dimers in a quasi-two-dimensional S=1 system.

New Luttinger-liquid physics from photoemission on Li0.9M06O17

Temperature dependent high resolution photoemission spectra of quasi-one-dimensional Li(0.9)Mo(6)O(17)evince a strong renormalization of its Luttinger-liquid density-of-states anomalous exponent. We trace this new effect to interacting charge neutral critical modes that emerge naturally from the two-band nature of the material. Li(0.9)Mo(6)O(17) is shown thereby to be a paradigm material that is capable of revealing new Luttinger physics.

Ambulatory photodynamic therapy: a new concept in delivering photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) has been shown to be effective in treating Bowen's disease, superficial basal cell carcinoma and actinic keratosis.

OBJECTIVES

To investigate the feasibility of delivering PDT using a portable light-emitting diode device.

METHODS

A prototype diode array, comprising 37 AlGaInP diodes cast in epoxy with a diffuser, and driven by a battery pack, was designed and constructed. A pilot study was carried out in five patients with histologically proven Bowen's disease who were referred for PDT with 5-aminolaevulinic acid. They were all treated in the hospital-based dermatology PDT suite such that each received the same level of supervision as patients receiving PDT with nonambulatory light sources. Patients recorded pain levels. In accordance with our usual practice, patients received two treatments at a 4-week interval.

RESULTS

Four of five patients were clear at follow-up (range 6-13 months, median 9). Pain was classified as none or mild in 80% of treatments and moderate in the remainder.

CONCLUSIONS

There are many potential benefits of ambulatory PDT, including the possibility of a much higher patient throughput, and allowing effective treatment at home. This pilot study provides early promising data of the safety and efficacy of this approach.

Proximal intracranial internal carotid artery branches: prevalence and importance for balloon occlusion test

Object. The aim of this study was to determine the prevalence of angiographically identifiable skull base arterial branches that potentially serve as collateral conduits during a balloon occlusion test (BOT) of the internal carotid artery (ICA). The authors posited that neurological deficits in patients who had previously tolerated the occlusion test may be attributable to an unrecognized collateral support through these channels (operant during proximal ICA BOT) when permanent ICA occlusion was performed more distally.

Methods. In 481 cases (962 ICAs), cerebral angiograms obtained during routine Wada testing were retrospectively reviewed. Two hundred sixty-one patients had at least one angiographically identifiable ICA branch; 109 patients had two or more branches. A meningohypophyseal branch of the cavernous ICA was identified on the right side in 108 patients and on the left in 122. A vidian artery originated from the petrous portion of the ICA on the right side in 58 patients and on the left in 85. The inferolateral trunk revealed itself as a branch of the cavernous ICA on the right side in 17 patients and on the left in 33. A caroticotympanic artery arose from a left cavernous ICA. A persistent trigeminal artery was situated on the right side in two patients and on the left in three. More than half of the patients had angiographically identifiable and perhaps hemodynamically significant skull base branches of the ICA, and approximately one quarter had more than one identifiable branch.

Conclusions. The authors recommend that patients be screened during angiography studies performed prior to BOT in branches of the proximal intracranial ICA and that the site of BOT be moved distally if such branches are identified.

Filling of the mott-hubbard gap in the high temperature photoemission spectrum of (V0.972Cr0.028)2O3

Photoemission spectra of the paramagnetic insulating phase of (V0.972Cr0.028)2O3, taken in ultrahigh vacuum up to the unusually high temperature (T) of 800 K, reveal a property unique to the Mott-Hubbard (MH) insulator that has not been observed previously. With increasing T the MH gap is filled by spectral weight transfer, in qualitative agreement with high-T theoretical calculations combining dynamical mean field theory and band theory in the local density approximation.

Favorable early results of gastric banding for morbid obesity: the American experience

BACKGROUND

In 2001 a new device for surgical weight loss was approved by the Food and Drug Administration (Lap-Band, Inamed Health). We describe initial results of laparoscopic gastric banding for morbid obesity in two American academic centers.

METHODS

Prospective data was collected on consecutive morbidly obese patients undergoing laparoscopic adjustable gastric banding, and evaluated retrospectively.

RESULTS

Four hundred forty-five consecutive patients underwent Lap-Band from May 2001 through December 2002. The 103 men and 341 women had an average age of 42.1 years (range 17-72 years) and an average body mass index (BMI) of 49.6 kg/m2 (range 35.2-92.2 kg/m2). One operation required conversion to laparotomy due to bleeding; the rest were completed laparoscopically. Mean length of stay was 1.1 days (range 1-10 days). There was one death. Additional complications included band slippage in 14 patients (3.1%), gastric obstruction without slip in 12 (2.7%), port migration in 2 (0.4%), tubing disconnections in 3 (0.7%), and port infection in 5 (1.1%). Two bands (0.4%) were removed due to intraabdominal abscess 2 months after placement. There was one band erosion (0.2%) and no clinically significant esophageal dilation. Ninety-nine patients have 1-year follow-up and have lost an average of 44.3% excess body weight.

CONCLUSION

Laparoscopic gastric banding has much to offer the morbidly obese. We present data showing weight loss rivaling gastric bypass and acceptably low complications. These results parallel success with this device outside America.

Acute presentation of infected urachal cysts: case report and review of diagnosis and therapeutic interventions

Urachal remnants, although relatively rare, masquerade as a large number of diverse disorders leading to a high rate of misdiagnosis. A typical case is reported in which a 10-year-old boy presented to the Emergency Department twice before being incorrectly diagnosed with a pelvic or lower abdominal periappendiceal abscess. Definitive diagnosis and treatment of an infected urachal cyst were made intraoperatively. A review and discussion of urachal remnants is presented, and a diagnostic algorithm and treatment plan is offered for this entity.

Prominent quasiparticle peak in the photoemission spectrum of the metallic phase of V2O3

We present the first observation of a prominent quasiparticle peak in the photoemission spectrum of the metallic phase of V2O3 and report new spectral calculations that combine the local-density approximation with the dynamical mean-field theory (using quantum Monte Carlo simulations) to show the development of such a distinct peak with decreasing temperature. The experimental peak width and weight are significantly larger than in the theory.

Laparoscopic management of Meckel's diverticulum in adults

BACKGROUND

Meckel's diverticulum is an uncommon entity. A high index of suspicion is necessary for opportune diagnosis and prompt treatment. Technetium (TC) 99m pertechnetate scintigraphy is a sensitive and specific test for Meckel's diverticulum. In adults, the scan contributes little to clinical decision making and often will not change the need for surgical intervention. We describe our experience with four patients.

METHODS

Between August 2000 and August 2001, four patients were seen with Meckel's diverticula. Three were male and one was female. The mean age was 39 years (range, 18-64). Three patients presented with anemia and one with an acute abdomen. A 99mTc pertechnetate scan was performed at a cost of 900 dollars in the three anemic patients after other endoscopic and radiographic tests were nondiagnostic. Only one patient had a positive scan. All four patients underwent exploratory laparoscopy and small bowel resection. In one patient, a minilaparatomy had to be performed.

RESULTS

All patients had a satisfactory outcome without complications. Three patients were discharged within 3 days of surgery. The remaining patient had a prolonged hospital stay because of ongoing chemotherapy for small cell lung cancer. In the three anemic patients who underwent enterectomy, ulcerated small bowel outside the diverticulum was found by the pathologist.

CONCLUSION

Laparoscopy is safe, cost-effective, and efficient for the diagnosis and definitive management of Meckel's diverticulum. Technetium 99m pertechnetate scintigraphy scanning adds considerable time and expense to the care of the patient without significant benefits in adults. The practice of exploratory laparoscopy rather than scintigraphy is recommended.

Totally laparoscopic management of gallstone ileus

Gallstone ileus is an uncommon disease of elderly patients who present with bowel obstruction. Mortality and severe complications are common, even in modern series, due to the comorbidities in the affected patient population. A number of less invasive ways to treat this disease are described. We report on a case where enterolithotomy was performed laparoscopically. The patient is a 60-year-old diabetic woman who presented with a bowel obstruction and pneumobilia on abdominal radiographs. She underwent exploratory laparoscopy using three reusable ports, an enterolithotomy, and her remaining bowel was examined. The benefits to a minimal access approach to this rare disorder are discussed. The ability to suture laparoscopically is emphasized.

Laparoscopic choledochojejunostomy and gastrojejunostomy in a porcine model

BACKGROUND

Surgical extirpation remains the only known curative treatment for cancer of the pancreas. Because of locally advanced or metastatic tumor, up to 80% of patients are unresectable at the time of initial diagnosis [13]. Other investigators previously have suggested that laparoscopy before laparotomy aids in the diagnosis of unresectable pancreatic cancer in a fair number of patients even after negative computed tomography scans [3, 17]. Many surgeons are reluctant to incorporate laparoscopy into the workup of patients with cancer of the pancreas because of the frequent need for surgical bypass in the management of either biliary tract obstruction or gastric outlet obstruction [9, 13]. Previous studies have demonstrated the feasibility of laparoscopic cholecystojejunostomy combined with gastrojejunostomy in a porcine model, as well as the individual accomplishment of laparoscopic choledochojejunostomy. The purpose of this study was to document the feasibility of performing laparoscopic choledochojejunostomy with gastrojejunostomy.

METHODS

Under general anesthesia, seven pigs underwent laparoscopic choledochojejunostomy and gastrojejunostomy using an intracorporeal hand-sutured technique.

RESULTS

The mean operating time ranged from 150 to 450 min. All the animals recovered completely from the operation and had patent anastomoses at the time of necropsy. One pig died of gastric bleeding on postoperative day 13, and two animals had intraabdominal fluid collections discovered at the time of necropsy.

CONCLUSIONS

These results suggest that synchronous laparoscopic bypass of biliary and gastric outlet obstruction is feasible, and can be performed in a manner similar to that used in open operations. We believe this lends support to the argument promoting laparoscopy in the evaluation of pancreatic cancer.