Publications by authors named "Petrice M Cogswell"

18 Publications

  • Page 1 of 1

e-ASPECTS software improves interobserver agreement and accuracy of interpretation of aspects score.

Interv Neuroradiol 2021 Apr 14:15910199211011861. Epub 2021 Apr 14.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Introduction: There is increased interest in the use of artificial intelligence-based (AI) software packages in the evaluation of neuroimaging studies for acute ischemic stroke. We studied whether, compared to standard image interpretation without AI, Brainomix e-ASPECTS software improved interobserver agreement and accuracy in detecting ASPECTS regions affected in anterior circulation LVO.

Methods: We included 60 consecutive patients with anterior circulation LVO who had TICI 3 revascularization within 60 minutes of their baseline CT. A total of 16 readers, including senior neuroradiologists, junior neuroradiologists and vascular neurologists participated. Readers interpreted CT scans on independent workstations and assessed final ASPECTS and evaluated whether each individual ASPECTS region was affected. Two months later, readers again evaluated the CT scans, but with assistance of e-ASPECTS software. We assessed interclass correlation coefficient for total ASPECTS and interobserver agreement with Fleiss' Kappa for each ASPECTS region with and without assistance of the e-ASPECTS. We also assessed accuracy for the readers with and without e-ASPECTS assistance. In our assessment of accuracy, ground truth was the 24 hour CT in this cohort of patients who had prompt and complete revascularization.

Results: Interclass correlation coefficient for total ASPECTS without e-ASPECTS assistance was 0.395, indicating fair agreement compared, to 0.574 with e-ASPECTS assistance, indicating good agreement (P < 0.01). There was significant improvement in inter-rater agreement with e-ASPECTS assistance for each individual region with the exception of M6 and caudate. The e-ASPECTS software had higher accuracy than the overall cohort of readers (with and without e-ASPECTS assistance) for every region except the caudate.

Conclusions: Use of Brainomix e-ASPECTS software resulted in significant improvements in inter-rater agreement and accuracy of ASPECTS score evaluation in a large group of neuroradiologists and neurologists. e-ASPECTS software was more predictive of final infarct/ASPECTS than the overall group interpreting the CT scans with and without e-ASPECTS assistance.
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http://dx.doi.org/10.1177/15910199211011861DOI Listing
April 2021

CSF dynamics as a predictor of cognitive progression.

Neuroimage 2021 May 23;232:117899. Epub 2021 Feb 23.

Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.

Disproportionately enlarged subarachnoid-space hydrocephalus (DESH), characterized by tight high convexity CSF spaces, ventriculomegaly, and enlarged Sylvian fissures, is thought to be an indirect marker of a CSF dynamics disorder. The clinical significance of DESH with regard to cognitive decline in a community setting is not yet well defined. The goal of this work is to determine if DESH is associated with cognitive decline. Participants in the population-based Mayo Clinic Study of Aging (MCSA) who met the following criteria were included: age ≥ 65 years, 3T MRI, and diagnosis of cognitively unimpaired or mild cognitive impairment at enrollment as well as at least one follow-up visit with cognitive testing. A support vector machine based method to detect the DESH imaging features on T1-weighted MRI was used to calculate a "DESH score", with positive scores indicating a more DESH-like imaging pattern. For the participants who were cognitively unimpaired at enrollment, a Cox proportional hazards model was fit with time defined as years from enrollment to first diagnosis of mild cognitive impairment or dementia, or as years to last known cognitively unimpaired diagnosis for those who did not progress. Linear mixed effects models were fit among all participants to estimate annual change in cognitive z scores for each domain (memory, attention, language, and visuospatial) and a global z score. For all models, covariates included age, sex, education, APOE genotype, cortical thickness, white matter hyperintensity volume, and total intracranial volume. The hazard of progression to cognitive impairment was an estimated 12% greater for a DESH score of +1 versus -1 (HR 1.12, 95% CI 0.97-1.31, p = 0.11). Global and attention cognition declined 0.015 (95% CI 0.005-0.025) and 0.016 (95% CI 0.005-0.028) z/year more, respectively, for a DESH score of +1 vs -1 (p = 0.01 and p = 0.02), with similar, though not statistically significant DESH effects in the other cognitive domains. Imaging features of disordered CSF dynamics are an independent predictor of subsequent cognitive decline in the MCSA, among other well-known factors including age, cortical thickness, and APOE status. Therefore, since DESH contributes to cognitive decline and is present in the general population, identifying individuals with DESH features may be important clinically as well as for selection in clinical trials.
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http://dx.doi.org/10.1016/j.neuroimage.2021.117899DOI Listing
May 2021

CSF dynamics disorders: Association of brain MRI and nuclear medicine cisternogram findings.

Neuroimage Clin 2020 28;28:102481. Epub 2020 Oct 28.

Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55902, USA.

Disproportionately enlarged subarachnoid space hydrocephalus (DESH), characterized by ventriculomegaly, high convexity/midline tight sulci, and enlarged sylvian fissures on brain MRI has been increasingly recognized as a distinct diagnostic imaging entity that falls within the larger category of idiopathic normal pressure hydrocephalus. Normal pressure hydrocephalus has been previously characterized as a CSF dynamics disorder based on abnormalities on nuclear medicine cisternography: radiotracer in the lateral ventricles and absent or delayed ascent of radiotracer over the cerebral convexity. The purpose of this work was to evaluate for differences in nuclear medicine cisternography between patients with vs without DESH and thereby provide support for the concept that DESH is a structural imaging marker of a CSF dynamics disorder. The study included 102 patients (mean age 71 years, range 46-86, 38 females), 58 patients with cisternogram performed to evaluate suspected normal pressure hydrocephalus (mean age 73 years, range 46-86 years, 24 female) and 44 patients evaluated for headache (mean age 68 years, range 60-82 years, 14 female). All patients had an MRI of the brain performed within 13 months of the cisternogram. Cisternogram imaging, typically acquired at 0.5, 1, 2, 4, and 24 h post injection, was evaluated for the time at which radiotracer reached the basal cisterns, presence of persistent radiotracer in the lateral ventricles, time radiotracer first entered the lateral ventricles, presence of radiotracer over the cerebral convexity, and time at which radiotracer was first visualized over the cerebral convexity. MRI features of ventriculomegaly (defined as Evans' index ≥ 0.3) and high convexity tight sulci (HCTS) were recorded. Based on the MRI features, patients were grouped according to presence or absence of DESH (ventriculomegaly and HCTS). Those without DESH were separated into groups of ventriculomegaly alone, HCTS alone, and neither ventriculomegaly nor HCTS. Cisternogram metrics were compared between MR-defined groups. Patients with DESH showed a higher frequency of radiotracer in the lateral ventricles and delayed or absent ascent over the cerebral convexity compared to those without DESH, higher frequency of ventricular radioactivity vs those with HCTS alone, and shorter time to ventricular radioactivity compared to those with ventriculomegaly alone. Patients with ventriculomegaly or HCTS alone had a higher frequency of radiotracer in the lateral ventricles and delayed ascent of radiotracer over the cerebral convexity compared to those with neither ventriculomegaly nor HCTS. These findings support DESH and the individual components of ventriculomegaly and HCTS as markers of disordered CSF dynamics.
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http://dx.doi.org/10.1016/j.nicl.2020.102481DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7658703PMC
October 2020

A cross-sectional, case-control study of intracranial arterial wall thickness and complete blood count measures in sickle cell disease.

Br J Haematol 2021 Feb 16;192(4):769-777. Epub 2020 Dec 16.

Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.

In sickle cell disease (SCD), cerebral oxygen delivery is dependent on the cerebral vasculature's ability to increase blood flow and volume through relaxation of the smooth muscle that lines intracranial arteries. We hypothesised that anaemia extent and/or circulating markers of inflammation lead to concentric macrovascular arterial wall thickening, visible on intracranial vessel wall magnetic resonance imaging (VW-MRI). Adult and pediatric SCD (n = 69; age = 19.9 ± 8.6 years) participants and age- and sex-matched control participants (n = 38; age = 22.2 ± 8.9 years) underwent 3-Tesla VW-MRI; two raters measured basilar and bilateral supraclinoid internal carotid artery (ICA) wall thickness independently. Mean wall thickness was compared with demographic, cerebrovascular and haematological variables. Mean vessel wall thickness was elevated (P < 0·001) in SCD (1·07 ± 0·19 mm) compared to controls (0·97 ± 0·07 mm) after controlling for age and sex. Vessel wall thickness was higher in participants on chronic transfusions (P = 0·013). No significant relationship between vessel wall thickness and flow velocity, haematocrit, white blood cell count or platelet count was observed; however, trends (P < 0·10) for wall thickness increasing with decreasing haematocrit and increasing white blood cell count were noted. Findings are discussed in the context of how anaemia and circulating inflammatory markers may impact arterial wall morphology.
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http://dx.doi.org/10.1111/bjh.17262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7902452PMC
February 2021

Application of Adaptive Image Receive Coil Technology for Whole-Brain Imaging.

AJR Am J Roentgenol 2021 02 25;216(2):552-559. Epub 2020 Nov 25.

Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.

The Adaptive Image Receive (AIR) radiofrequency coil is an emergent technology that is lightweight and flexible and exhibits electrical characteristics that overcome many of the limitations of traditional rigid coil designs. The purpose of this study was to apply the AIR coil for whole-brain imaging and compare the performance of a prototype AIR coil array with the performance of conventional head coils. A phantom and 15 healthy adult participants were imaged. A prototype 16-channel head AIR coil was compared with conventional 8-and 32-channel head coils using clinically available MRI sequences. During consensus review, two board-certified neuroradiologists graded the AIR coil compared with an 8-channel coil and a 32-channel coil on a 5-point ordinal scale in multiple categories. One- and two-sided Wilcoxon signed rank tests were performed. Noise covariance matrices and geometry factor (g-factor) maps were calculated. The signal-to-noise ratio, structural sharpness, and overall image quality scores of the prototype 16-channel AIR coil were better than those of the 8-channel coil but were not as good as those of the 32-channel coil. Noise covariance matrices showed stable performance of the AIR coil across participants. The median g-factors for the 16-channel AIR coil were, overall, less than those of the 8-channel coil but were greater than those of the 32-channel coil. On average, the prototype 16-channel head AIR coil outperformed a conventional 8-channel head coil but did not perform as well as a conventional 32-channel head coil. This study shows the feasibility of the novel AIR coil technology for imaging the brain and provides insight for future coil design improvements.
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http://dx.doi.org/10.2214/AJR.20.22812DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7968701PMC
February 2021

Associations of quantitative susceptibility mapping with Alzheimer's disease clinical and imaging markers.

Neuroimage 2021 01 6;224:117433. Epub 2020 Oct 6.

Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.

Altered iron metabolism has been hypothesized to be associated with Alzheimer's disease pathology, and prior work has shown associations between iron load and beta amyloid plaques. Quantitative susceptibility mapping (QSM) is a recently popularized MR technique to infer local tissue susceptibility secondary to the presence of iron as well as other minerals. Greater QSM values imply greater iron concentration in tissue. QSM has been used to study relationships between cerebral iron load and established markers of Alzheimer's disease, however relationships remain unclear. In this work we study QSM signal characteristics and associations between susceptibility measured on QSM and established clinical and imaging markers of Alzheimer's disease. The study included 421 participants (234 male, median age 70 years, range 34-97 years) from the Mayo Clinic Study of Aging and Alzheimer's Disease Research Center; 296 (70%) had a diagnosis of cognitively unimpaired, 69 (16%) mild cognitive impairment, and 56 (13%) amnestic dementia. All participants had multi-echo gradient recalled echo imaging, PiB amyloid PET, and Tauvid tau PET. Variance components analysis showed that variation in cortical susceptibility across participants was low. Linear regression models were fit to assess associations with regional susceptibility. Expected increases in susceptibility were found with older age and cognitive impairment in the deep and inferior gray nuclei (pallidum, putamen, substantia nigra, subthalamic nucleus) (betas: 0.0017 to 0.0053 ppm for a 10 year increase in age, p = 0.03 to <0.001; betas: 0.0021 to 0.0058 ppm for a 5 point decrease in Short Test of Mental Status, p = 0.003 to p<0.001). Effect sizes in cortical regions were smaller, and the age associations were generally negative. Higher susceptibility was significantly associated with higher amyloid PET SUVR in the pallidum and putamen (betas: 0.0029 and 0.0012 ppm for a 20% increase in amyloid PET, p = 0.05 and 0.02, respectively), higher tau PET in the basal ganglia with the largest effect size in the pallidum (0.0082 ppm for a 20% increase in tau PET, p<0.001), and with lower cortical gray matter volume in the medial temporal lobe (0.0006 ppm for a 20% decrease in volume, p = 0.03). Overall, these findings suggest that susceptibility in the deep and inferior gray nuclei, particularly the pallidum and putamen, may be a marker of cognitive decline, amyloid deposition, and off-target binding of the tau ligand. Although iron has been demonstrated in amyloid plaques and in association with neurodegeneration, it is of insufficient quantity to be reliably detected in the cortex using this implementation of QSM.
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http://dx.doi.org/10.1016/j.neuroimage.2020.117433DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7860631PMC
January 2021

Prevalence and Trends in Management of Idiopathic Normal Pressure Hydrocephalus in the United States: Insights from the National Inpatient Sample.

World Neurosurg 2021 Jan 8;145:e38-e52. Epub 2020 Sep 8.

Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA. Electronic address:

Background: Over the past 2 decades, management of idiopathic normal pressure hydrocephalus (iNPH) has evolved significantly. In the current study, we sought to evaluate the national prevalence and management trends of iNPH in the United States using a national database.

Methods: The National Inpatient Sample was queried for patients with an International Classification of Diseases diagnosis code for iNPH from 2007 to 2017. Trends in prevalence and procedure type were evaluated per 100,000 discharges and as a percentage of discharges, using weighted discharges. Utilization of procedure type across U.S. regions and hospital types was also compared.

Results: From 2007 to 2017, 302,460 weighted discharges with any diagnosis code for iNPH, aged ≥60 years, were identified. Prevalence ranged from 0.04% to 0.20% (41/100,000 to 202/100,000) among admitted patients ≥60 years old, giving an average prevalence during the study duration of 0.18% (179/100,000). Of 66,759 weighted discharges with a primary diagnosis code of iNPH undergoing surgical management, ventriculoperitoneal shunt (72.0% of discharges, n = 48,977) was most commonly used; of these, 9.3% (n = 4567) were performed laparoscopically. This result was followed by lumbar peritoneal shunt (15.1% of discharges, n = 10,441). Up to 15.1% (n = 9990) of discharges reported only a lumbar puncture, assumed to be only diagnostic, for screening, or part of serial cerebrospinal fluid removal procedures. Significant discrepancies in procedure utilization were also identified among hospitals in the Western, Southern, Northeast and Midwest regions, as well as between urban and rural hospitals (P < 0.05).

Conclusions: We have summarized the national prevalence of iNPH, trends in its management over the previous decade and trends by region and hospital type.
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http://dx.doi.org/10.1016/j.wneu.2020.09.012DOI Listing
January 2021

Intracranial vasculature 3D printing: review of techniques and manufacturing processes to inform clinical practice.

3D Print Med 2020 Aug 6;6(1):18. Epub 2020 Aug 6.

Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, USA.

Background: In recent years, three-dimensional (3D) printing has been increasingly applied to the intracranial vasculature for patient-specific surgical planning, training, education, and research. Unfortunately, though, much of the prior literature regarding 3D printing has focused on the end-product and not the process. In addition, for 3D printing/manufacturing to occur on a large scale, challenges and bottlenecks specific to each modeled anatomy must be overcome.

Main Body: In this review article, limitations and considerations of each 3D printing processing step, as they relate to printing individual intracranial vasculature models and providing an active clinical service for a quaternary care center, are discussed. Relevant advantages and disadvantages of the available acquisition techniques (computed tomography, magnetic resonance, and digital subtraction angiography) are reviewed. Specific steps in segmentation, processing, and creation of a printable file may impede the workflow or degrade the fidelity of the printed model and are, therefore, given added attention. The various available printing techniques are compared with respect to printing the intracranial vasculature. Finally, applications are discussed, and a variety of example models are shown.

Conclusion: In this review we provide insight into the manufacturing of 3D models of the intracranial vasculature that may facilitate incorporation into or improve utility of 3D vascular models in clinical practice.
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http://dx.doi.org/10.1186/s41205-020-00071-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7409717PMC
August 2020

Identification of Normal Pressure Hydrocephalus by Disease-Specific Patterns of Brain Stiffness and Damping Ratio.

Invest Radiol 2020 04;55(4):200-208

From the Departments of Radiology.

Objectives: The aim of this study was to perform a whole-brain analysis of alterations in brain mechanical properties due to normal pressure hydrocephalus (NPH).

Materials And Methods: Magnetic resonance elastography (MRE) examinations were performed on 85 participants, including 44 cognitively unimpaired controls, 33 with NPH, and 8 who were amyloid-positive with Alzheimer clinical syndrome. A custom neural network inversion was used to estimate stiffness and damping ratio from patches of displacement data, accounting for edges by training the network to estimate the mechanical properties in the presence of missing data. This learned inversion was first compared with a standard analytical approach in simulation experiments and then applied to the in vivo MRE measurements. The effect of NPH on the mechanical properties was then assessed by voxel-wise modeling of the stiffness and damping ratio maps. Finally, a pattern analysis was performed on each individual's mechanical property maps by computing the correlation between each person's maps with the expected NPH effect. These features were used to fit a classifier and assess diagnostic accuracy.

Results: The voxel-wise analysis of the in vivo mechanical property maps revealed a unique pattern in participants with NPH, including a concentric pattern of stiffening near the dural surface and softening near the ventricles, as well as decreased damping ratio predominantly in superior regions of the white matter (family-wise error corrected P < 0.05 at cluster level). The pattern of viscoelastic changes in each participant predicted NPH status in this cohort, separating participants with NPH from the control and the amyloid-positive with Alzheimer clinical syndrome groups, with areas under the receiver operating characteristic curve of 0.999 and 1, respectively.

Conclusions: This study provides motivation for further development of the neural network inversion framework and demonstrates the potential of MRE as a novel tool to diagnose NPH and provide a window into its pathogenesis.
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http://dx.doi.org/10.1097/RLI.0000000000000630DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7681913PMC
April 2020

Contemporary and emerging magnetic resonance imaging methods for evaluation of moyamoya disease.

Neurosurg Focus 2019 12;47(6):E6

2Neurosurgery, and.

Numerous recent technological advances offer the potential to substantially enhance the MRI evaluation of moyamoya disease (MMD). These include high-resolution volumetric imaging, high-resolution vessel wall characterization, improved cerebral angiographic and perfusion techniques, high-field imaging, fast scanning methods, and artificial intelligence. This review discusses the current state-of-the-art MRI applications in these realms, emphasizing key imaging findings, clinical utility, and areas that will benefit from further investigation. Although these techniques may apply to imaging of a wide array of neurovascular or other neurological conditions, consideration of their application to MMD is useful given the comprehensive multidimensional MRI assessment used to evaluate MMD. These MRI techniques span from basic cross-sectional to advanced functional sequences, both qualitative and quantitative.The aim of this review was to provide a comprehensive summary and analysis of current key relevant literature of advanced MRI techniques for the evaluation of MMD with image-rich case examples. These imaging methods can aid clinical characterization, help direct treatment, assist in the evaluation of treatment response, and potentially improve the understanding of the pathophysiology of MMD.
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http://dx.doi.org/10.3171/2019.9.FOCUS19616DOI Listing
December 2019

Vessel Wall and Lumen Features in North American Moyamoya Patients.

Clin Neuroradiol 2020 Sep 6;30(3):545-552. Epub 2019 Aug 6.

Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.

Purpose: To apply intracranial vessel wall imaging (VWI) to determine changes in vessel wall characteristics between North American moyamoya patients and controls, as well as with standard clinical measures of moyamoya disease severity.

Methods: North American moyamoya patients and controls underwent intracranial 3.0 T VWI. Moyamoya patients also underwent digital subtraction angiography (DSA), from which modified Suzuki scores (mSS) were calculated. Lumen and outer vessel wall diameters of the supraclinoid internal carotid arteries (ICAs) and basilar artery on VWI were measured by two readers from which wall thickness was calculated. Controls and moyamoya patients were compared in logistic regression using disease category (moyamoya or none) as the dependent variable and wall thickness, age, gender, and side as the explanatory variables (significance: two-sided p < 0.05). In moyamoya patients, regression was performed with mSS as the dependent variable and wall thickness, age, gender, and side as the explanatory variables. Analyses were repeated for each lumen diameter and outer vessel wall diameter in place of wall thickness.

Results: Patients with moyamoya (n = 23, gender = 3/20 male/female; age = 43 ± 12 years) and controls (n = 23, gender = 3/20 male/female, age = 43 ± 13 years) were included. Moyamoya patients showed a significantly smaller ICA lumen and outer vessel wall diameter compared to controls (p < 0.05) but no significant change in vessel wall thickness. Similarly, ICA lumen and outer vessel wall diameters decreased with increasing mSS (p < 0.05).

Conclusion: Findings suggest decreased ICA lumen and outer vessel wall diameters, but no significant difference in wall thickness, between patients and controls. Lumen and outer vessel wall diameters also decreased with disease severity.
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http://dx.doi.org/10.1007/s00062-019-00819-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245731PMC
September 2020

Vessel wall and lumen characteristics with age in healthy participants using 3T intracranial vessel wall magnetic resonance imaging.

J Magn Reson Imaging 2019 11 17;50(5):1452-1460. Epub 2019 Apr 17.

Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.

Background: Intracranial vessel wall imaging (VWI) at a clinical field strength of 3T has become more widely available. However, how vessel measurements change with age and sex, over an age range spanning a typical lifespan, are needed.

Purpose/hypothesis: To assess for identifiable changes in arterial wall thickness, outer vessel wall diameter, and lumen diameter with age cross-sectionally in healthy controls without cerebrovascular disease risk factors at the spatial resolution afforded by currently recommended 3T VWI approaches.

Study Type: Prospective.

Population/subjects: Healthy subjects (n = 82; age = 8-79 years).

Field Strength/sequence: 3T intracranial VWI, angiography, and T -weighted anatomical imaging.

Assessment: Two readers measured lumen and outer wall diameters of the supraclinoid internal carotid artery (ICA) and distal basilar artery. Wall thickness and intraclass correlation coefficients (ICCs) were calculated.

Statistical Tests: Separate linear regressions were performed to understand the relationship between wall measurements (lumen diameter, outer vessel wall diameter, and wall thickness) and age, gender, side (left or right); significance: two-sided P < 0.05.

Results: Readers showed excellent agreement for lumen and outer wall diameters (ICC 0.83-094). Linear regression of supraclinoid ICA wall measurements showed a statistically significant increase in wall thickness (P = 0.00051) and outer vessel wall diameter (P = 0.030) with age. ICA lumen and outer vessel wall diameters were statistically greater in males vs. females (lumen diameter 3.69 ± 0.41 vs. 3.54 ± 0.35 mm, P = 0.026; outer wall diameter 5.78 ± 0.52 vs. 5.56 ± 0.44 mm, P = 0.0089) with a trend toward increase in wall thickness (1.05 ± 0.12 vs. 1.01 ± 0.10 mm, P = 0.055). No significant difference was found in basilar artery wall thickness (P = 0.45, P = 0.72), lumen diameter (P = 0.15, P = 0.42), or outer vessel wall diameter (P = 0.34, P = 0.41) with age or gender, respectively.

Data Conclusion: Intracranial vessel wall measurements were shown to be consistent between readers. At the available spatial resolution of 3T intracranial VWI sequences, supraclinoid ICA vessel wall thickness and outer vessel wall diameter appear to mildly increase with age. There was no detectable change in basilar artery vessel wall characteristics with age.

Level Of Evidence: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:1452-1460.
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http://dx.doi.org/10.1002/jmri.26750DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800748PMC
November 2019

Variable impact of CSF flow suppression on quantitative 3.0T intracranial vessel wall measurements.

J Magn Reson Imaging 2018 10 31;48(4):1120-1128. Epub 2018 Mar 31.

Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.

Background: Flow suppression techniques have been developed for intracranial (IC) vessel wall imaging (VWI) and optimized using simulations; however, simulation results may not translate in vivo.

Purpose: To evaluate experimentally how IC vessel wall and lumen measurements change in identical subjects when evaluated using the most commonly available blood and cerebrospinal fluid (CSF) flow suppression modules and VWI sequences.

Study Type: Prospective.

Population/subjects: Healthy adults (n = 13; age = 37 ± 15 years) were enrolled.

Field Strength/sequence: A 3.0T 3D T /proton density (PD)-weighted turbo-spin-echo (TSE) acquisition with post-readout anti-driven equilibrium module, with and without Delay-Alternating-with-Nutation-for-Tailored-Excitation (DANTE) was applied. DANTE flip angle (8-12°) and TSE refocusing angle (sweep = 40-120° or 50-120°) were varied.

Assessment: Basilar artery and internal carotid artery (ICA) wall thicknesses, CSF signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal ratio (SR) were assessed. Measurements were made by two readers (radiology resident and board-certified neuroradiologist).

Statistical Tests: A Wilcoxon signed-rank test was applied with corrected two-sided P < 0.05 required for significance (critical P = 0.008, 0.005, and 0.05 for SNR/CNR, SR, and wall thickness, respectively).

Results: A TSE pulse sweep = 40-120° and sweep = 50-120° provided similar (P = 0.55) CSF suppression. Addition of the DANTE preparation reduced CSF SNR from 17.4 to 6.7, thereby providing significant (P < 0.008) improvement in CSF suppression. The DANTE preparation also resulted in a significant (P < 0.008) reduction in vessel wall SNR, but variable vessel wall to CSF CNR improvement (P = 0.87). There was a trend for a difference in blood SNR with vs. without DANTE (P = 0.05). The outer vessel wall diameter and wall thickness values were lower (P < 0.05) with (basilar artery 4.45 mm, 0.81 mm, respectively) vs. without (basilar artery 4.88 mm, 0.97 mm, respectively) DANTE 8°.

Data Conclusion: IC VWI with TSE sweep = 40-120° and with DANTE flip angle = 8° provides the best CSF suppression and CNR of the approaches evaluated. However, improvements are heterogeneous, likely owing to intersubject vessel pulsatility and CSF flow variations, which can lead to variable flow suppression efficacy in these velocity-dependent modules.

Level Of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;48:1120-1128.
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http://dx.doi.org/10.1002/jmri.26028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6167215PMC
October 2018

Attitudes of Radiology Program Directors Toward MD-PhD Trainees, Resident Research Productivity, and Dedicated Research Time.

Acad Radiol 2018 06 9;25(6):733-738. Epub 2018 Mar 9.

Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Ave South, Medical Center North, Nashville, TN 37232; Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.

Rationale And Objectives: The percentage of clinical scientists in radiology has historically been low. Increasing the pipeline of trainees interested in research could occur by recruiting MD-PhD trainees and providing protected research time during residency. The purpose of this work is to assess the attitudes of radiology program directors toward MD-PhD trainees, resident research productivity, and dedicated research time.

Methods: An online survey was sent to residency program directors of all diagnostic radiology departments that received National Institutes of Health (NIH) awards in 2014 (n = 63). Survey questions included program size; perception of overall performance, clinical performance, and research productivity of MD-PhD residents compared to non-PhD residents; and presence of dedicated research time. Responses comparing MD-PhD residents to non-PhD residents were reported as a five-point Likert scale. Student t test was used to assess for significance (alpha = 0.05).

Results: Response rate was 37%. Clinical performance of MD-PhD residents was judged inferior (P < .05) to non-PhD residents, although that of all residents engaged in research trended toward superiority compared to those not involved in research. Dedicated research time is offered by 61% of programs in years R1-R3 and all programs in year R4. Research productivity during residency was judged to be similar (P = .5) between MD-PhD and non-PhD residents.

Conclusions: Survey results suggest that clinical performance during residency and research involvement is often individually based and difficult to generalize based on prior PhD training. All programs offered dedicated research time, and the vast majority of residents were reported to engage in research during residency, which may increase the pipeline of trainees interested in an academic career.
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http://dx.doi.org/10.1016/j.acra.2018.01.029DOI Listing
June 2018

Consensus statement on current and emerging methods for the diagnosis and evaluation of cerebrovascular disease.

J Cereb Blood Flow Metab 2018 09 17;38(9):1391-1417. Epub 2017 Aug 17.

10 Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.

Cerebrovascular disease (CVD) remains a leading cause of death and the leading cause of adult disability in most developed countries. This work summarizes state-of-the-art, and possible future, diagnostic and evaluation approaches in multiple stages of CVD, including (i) visualization of sub-clinical disease processes, (ii) acute stroke theranostics, and (iii) characterization of post-stroke recovery mechanisms. Underlying pathophysiology as it relates to large vessel steno-occlusive disease and the impact of this macrovascular disease on tissue-level viability, hemodynamics (cerebral blood flow, cerebral blood volume, and mean transit time), and metabolism (cerebral metabolic rate of oxygen consumption and pH) are also discussed in the context of emerging neuroimaging protocols with sensitivity to these factors. The overall purpose is to highlight advancements in stroke care and diagnostics and to provide a general overview of emerging research topics that have potential for reducing morbidity in multiple areas of CVD.
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http://dx.doi.org/10.1177/0271678X17721830DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6125970PMC
September 2018

Impact of vessel wall lesions and vascular stenoses on cerebrovascular reactivity in patients with intracranial stenotic disease.

J Magn Reson Imaging 2017 10 6;46(4):1167-1176. Epub 2017 Jan 6.

Department of Radiology, Vanderbilt University, Nashville, Tennessee, USA.

Purpose: To compare cerebrovascular reactivity (CVR) and CVR lagtimes in flow territories perfused by vessels with vs. without proximal arterial wall disease and/or stenosis, separately in patients with atherosclerotic and nonatherosclerotic (moyamoya) intracranial stenosis.

Materials And Methods: Atherosclerotic and moyamoya patients with >50% intracranial stenosis and <70% cervical stenosis underwent angiography, vessel wall imaging (VWI), and CVR-weighted imaging (n = 36; vessel segments evaluated = 396). Angiography and VWI were evaluated for stenosis locations and vessel wall lesions. Maximum CVR and CVR lagtime were contrasted between vascular territories with and without proximal intracranial vessel wall lesions and stenosis, and a Wilcoxon rank-sum was test used to determine differences (criteria: corrected two-sided P < 0.05).

Results: CVR lagtime was prolonged in territories with vs. without a proximal vessel wall lesion or stenosis for both patient groups: moyamoya (CVR lagtime = 45.5 sec ± 14.2 sec vs. 35.7 sec ± 9.7 sec, P < 0.001) and atherosclerosis (CVR lagtime = 38.2 sec ± 9.1 sec vs. 35.0 sec ± 7.2 sec, P = 0.001). For reactivity, a significant decrease in maximum CVR in the moyamoya group only (maximum CVR = 9.8 ± 2.2 vs. 12.0 ± 2.4, P < 0.001) was observed.

Conclusion: Arterial vessel wall lesions detected on noninvasive, noncontrast intracranial VWI in patients with intracranial stenosis correlate on average with tissue-level impairment on CVR-weighted imaging.

Level Of Evidence: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1167-1176.
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http://dx.doi.org/10.1002/jmri.25602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500451PMC
October 2017

Hemodynamic mechanisms underlying elevated oxygen extraction fraction (OEF) in moyamoya and sickle cell anemia patients.

J Cereb Blood Flow Metab 2018 09 28;38(9):1618-1630. Epub 2016 Dec 28.

1 Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, USA.

Moyamoya is a bilateral, complex cerebrovascular condition characterized by progressive non-atherosclerotic intracranial stenosis and collateral vessel formation. Moyamoya treatment focuses on restoring cerebral blood flow (CBF) through surgical revascularization, however stratifying patients for revascularization requires abilities to quantify how well parenchyma is compensating for arterial steno-occlusion. Globally elevated oxygen extraction fraction (OEF) secondary to CBF reduction may serve as a biomarker for tissue health in moyamoya patients, as suggested in patients with sickle cell anemia (SCA) and reduced oxygen carrying capacity. Here, OEF was measured (TRUST-MRI) to test the hypothesis that OEF is globally elevated in patients with moyamoya (n = 18) and SCA (n = 18) relative to age-matched controls (n = 43). Mechanisms underlying the hypothesized OEF increases were evaluated by performing sequential CBF-weighted, cerebrovascular reactivity (CVR)-weighted, and structural MRI. Patients were stratified by treatment and non-parametric tests applied to compare study variables (significance: two-sided P < 0.05). OEF was significantly elevated in moyamoya participants (interquartile range = 0.38-0.45) compared to controls (interquartile range = 0.29-0.38), similar to participants with SCA (interquartile range = 0.37-0.45). CBF was inversely correlated with OEF in moyamoya participants. Elevated OEF was only weakly related to reductions in CVR, consistent with basal CBF level, rather than vascular reserve capacity, being most closely associated with OEF.
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http://dx.doi.org/10.1177/0271678X16682509DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6125968PMC
September 2018

Pretreatment imaging of peripheral vascular malformations.

J Vasc Diagn 2014;2014(2):121-126

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Peripheral vascular malformations (VMs) are complex and diverse vascular lesions which require individualized pretreatment planning. Pretreatment imaging using various modalities, especially magnetic resonance imaging and time-resolved magnetic resonance angiography, is a valuable tool for classifying peripheral VMs to allow proper diagnosis, demonstrate complete extent, identify the nidus, and distinguish between low-flow and high-flow dynamics that determines the treatment approach. We discuss pretreatment imaging findings in four patients with peripheral VMs and how diagnostic imaging helped guide management.
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http://dx.doi.org/10.2147/JVD.S66467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4304669PMC
January 2014