Nicholas S BurrisUniversity of Michigan | U-M · Department of Radiology
Nicholas S Burris
MD
About
83
Publications
8,327
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,172
Citations
Introduction
Additional affiliations
July 2016 - present
July 2015 - June 2016
July 2011 - June 2015
Education
July 2011 - June 2015
August 2006 - May 2010
Publications
Publications (83)
Purpose:
To investigate the utility of a free-breathing ultrashort echo time (UTE) sequence for the evaluation of small pulmonary nodules in oncology patients by using a hybrid positron emission tomography (PET)/magnetic resonance (MR) imaging system and to compare the nodule detection rate between UTE and a conventional three-dimensional gradient...
Abnormal blood flow with bicuspid aortic valve (BAV) has been characterized with four-dimensional flow magnetic resonance imaging (MRI), but this approach is time consuming and requires technical expertise. We assess the relationship between different leaflets fusion patterns with BAV, eccentric systolic flow, and dilation patterns of the ascending...
Aortic disease is routinely monitored with anatomic imaging, but until the recent advent of 3-directional phase contrast MRI (4D) flow, blood flow abnormalities have gone undetected. 4D flow measures aortic hemodynamic markers quickly. Qualitative flow visualization has spurred the investigation of new quantitative markers. Flow displacement and wa...
Altered systolic blood flow in the ascending aorta has been correlated with increased aortic growth in patients with bicuspid aortic valves (BAVs). We used conventional, 2-dimensional (2D) phase contrast magnetic resonance imaging (PC-MRI) to assess the relationship between altered flow and future growth in patients with BAV.
Aortic MRI data were r...
Background and aim of the study: Bicuspid aorticvalve (BAV)-related aortopathy is characterized by histological abnormalities that result in aortic wall stiffening and aortic dilation. The study aim was to determine the range of ascending aortic stiffness seen in a clinical cohort of patients with BAV, and to identify the association of aortic stif...
4D Flow Magnetic Resonance Imaging (4D Flow MRI) is a non-invasive measurement technique capable of quantifying blood flow across the cardiovascular system. While practical use is limited by spatial resolution and image noise, incorporation of trained super-resolution (SR) networks has potential to enhance image quality post-scan. However, these ef...
Background: The ascending aorta exhibits a complex, 3D motion related to cyclic pressure changes and downward traction forces related to left ventricular contraction. However, most metrics of disease severity are static (i.e., diameter) and among prior studies that have investigated ascending aortic motion, 2D imaging is typically employed. Vascula...
Introduction: Patients with ascending thoracic aortic aneurysm (aTAA) are recommended to undergo routine imaging surveillance. While maximal diameter is the primary metric of disease severity, recent AHA/ACC guidelines emphasize the importance of aortic growth in determining surgical candidacy and risk of complications. Increasing diameter is often...
Introduction: Marfan syndrome (MFS) is associated with high aortic growth rate (GR) and incidence of aortic dissection (AD), including delayed type B AD (TBAD) after prophylactic root repair. Elevated aortic stiffness has been investigated as a biomarker in MFS, but it remains uncertain how stiffness relates to GR and risk of AD. Vascular deformati...
Purpose:
Diagnosis and surveillance of thoracic aortic aneurysm (TAA) involves measuring the aortic diameter at various locations along the length of the aorta, often using computed tomography angiography (CTA). Currently, measurements are performed by human raters using specialized software for three-dimensional analysis, a time-consuming process...
Hemodynamic assessment is an integral part of the diagnosis and management of cardiovascular disease. Four-dimensional cardiovascular magnetic resonance flow imaging (4D Flow CMR) allows comprehensive and accurate assessment of flow in a single acquisition. This consensus paper is an update from the 2015 '4D Flow CMR Consensus Statement'. We elabor...
The aorta is in constant motion due to the combination of cyclic loading and unloading with its mechanical coupling to the contractile left ventricle (LV) myocardium. This aortic root motion has been proposed as a marker for aortic disease progression. Aortic root motion extraction techniques have been mostly based on 2D image analysis and have thu...
Landmark detection is a critical component of the image processing pipeline for automated aortic size measurements. Given that the thoracic aorta has a relatively conserved topology across the population and that a human annotator with minimal training can estimate the location of unseen landmarks from limited examples, we proposed an auxiliary lea...
Objective:
This study combines a deep image prior with low-rank subspace modeling to enable real-time (free-breathing and ungated) functional cardiac imaging on a commercial 0.55 T scanner.
Materials and methods:
The proposed low-rank deep image prior (LR-DIP) uses two u-nets to generate spatial and temporal basis functions that are combined to...
Purpose:
To describe the design and methodological approach of a multicenter, retrospective study to externally validate a clinical and imaging-based model for predicting the risk of late adverse events in patients with initially uncomplicated type B aortic dissection (uTBAD).
Materials and methods:
The Registry of Aortic Diseases to Model Adver...
Introduction: Patients with genetically-mediated thoracic aortic aneurysm (TAA) are at high risk of progressive aortic growth, although growth is highly variable and often difficult to accurately define using conventional diameter measurements. An emerging image analysis technique, vascular deformation mapping (VDM), provides accurate, three-dimens...
A serious complication in aortic dissection is dynamic obstruction of the true lumen (TL). Dynamic obstruction results in malperfusion, a blockage of blood flow to vital organs. Clinical data reveal that increases in central blood pressure promote dynamic obstruction. However, the mechanisms by which high pressures result in TL collapse are underex...
Institution of extracorporeal membrane oxygenation (ECMO) results in unique blood flow characteristics to the end-organ vascular beds. We studied the interplay between cardiac-driven and extracorporeal membrane oxygenation (ECMO)-driven flow to vascular beds in different ECMO configurations using a patient-specific computational fluid dynamics (CFD...
Objective
Adverse left ventricular remodeling due to a mismatch between stiffness of native aortic tissue and current polyester grafts may be under-recognized. This study was conducted to evaluate the impact of proximal aortic replacement on adverse remodeling of the left ventricle.Materials and methodsAll aortic root and ascending aortic aneurysm...
Objective:
Focal intimal flaps (FIF) are a variety of defects of the aorta that result in a short, flap-like projection into the lumen, and are often encountered in asymptomatic patients undergoing computed tomography angiography (CTA) surveillance for aortic aneurysm, but the natural history and clinical significance of such lesions has not yet b...
Objectives
Establishing the reproducibility of expert-derived measurements on CTA exams of aortic dissection is clinically important and paramount for ground-truth determination for machine learning.Methods
Four independent observers retrospectively evaluated CTA exams of 72 patients with uncomplicated Stanford type B aortic dissection and assessed...
Purpose:
Accurate assessment of thoracic aortic aneurysm (TAA) growth is important for appropriate clinical management. Maximal aortic diameter is the primary metric that is used to assess growth, but it suffers from substantial measurement variability. A recently proposed technique, termed Vascular Deformation Mapping (VDM), is able to quantify t...
Objectives:
Malperfusion syndrome accompanying aortic dissection is an independent predictor of death with in-hospital mortality rates >60%. Asymmetrically decreased renal enhancement on computed tomography angiography is often considered evidence of renal malperfusion. We investigated the associations between renal enhancement, baseline laborator...
Ventricular-vascular interaction is central in the adaptation to cardiovascular disease. However, cardiomyopathy patients are predominantly monitored using cardiac biomarkers. The aim of this study is therefore to explore aortic function in dilated cardiomyopathy (DCM). Fourteen idiopathic DCM patients and 16 controls underwent cardiac magnetic res...
Abstract Background Chronic type B aortic dissection (TBAD) is associated with poor long-term outcome, and accurate risk stratification tools remain lacking. Pressurization of the false lumen (FL) has been recognized as central in promoting aortic growth. Several surrogate imaging-based metrics have been proposed to assess FL hemodynamics; however,...
Patients with aortic dissection and other acute aortic diseases are subject to long-term imaging surveillance to monitor aortic growth and detect complications. This chapter will focus on practical aspects of long-term aortic imaging, including the selection of imaging surveillance intervals, choice of imaging modality (echocardiography vs. CT vs....
Background
Aortic diameter measurements in patients with a thoracic aortic aneurysm (TAA) show wide variation. There is no technique to quantify aortic growth in a three-dimensional (3D) manner.
Purpose
To validate a CT-based technique for quantification of 3D growth based on deformable registration in patients with TAA.
Materials and Methods
Pat...
Introduction: Aging has many effects on the cardiovascular system, including changes in structure (aortic composition, and thus stiffening) and function (increased proximal blood pressure, and thus cardiac afterload). Mouse models are often used to gain insight into vascular aging and mechanisms of disease as they allow invasive assessments that ar...
Stanford type B aortic dissection (TBAD) is associated with relatively high rates of morbidity and mortality, and appropriate treatment selection is important for optimizing patient outcomes. Depending on individualized risk factors, clinical presentation, and imaging findings, patients are generally stratified to optimal medical therapy anchored b...
Abdominal aortic aneurysm (AAA) is a complex disease that requires regular imaging surveillance to monitor for aneurysm stability. Current imaging surveillance techniques use maximum diameter, often assessed by computed tomography angiography (CTA), to assess risk of rupture and determine candidacy for operative repair. However, maximum diameter me...
OBJECTIVES
Differential luminal enhancement [between true lumen (TL) and false lumen (FL)] results from differential flow patterns, most likely due to outflow restriction in the FL. We aimed to assess the impact of differential luminal enhancement at baseline computed tomography angiography on the risk of adverse events in patients with acute type...
IMPACT: Through conducting this systematic review and meta-analysis, we will elucidate which factors influence thoracic aortic aneurysm growth, which will further help clinicians to properly stratify and manage their patients with TAAs. OBJECTIVES/GOALS: Thoracic aortic aneurysms (TAA) are an indolent but fatal disease, and the patient characterist...
OBJECTIVES
Confident growth assessment during imaging follow-up is often limited by substantial variability of diameter measurements and the fact that growth does not always occur at standard measurement locations. There is a need for imaging-based techniques to more accurately assess growth. In this study, we investigated the feasibility of a thre...
Intracardiac blood flow is driven by differences in relative pressure, and assessing these is critical in understanding cardiac disease. Non-invasive image-based methods exist to assess relative pressure, however, the complex flow and dynamically moving fluid domain of the intracardiac space limits assessment. Recently, we proposed a method, νWERP,...
Purpose
Up to 10% of acute type A aortic dissection (TAAD) patients are deemed unfit for open surgical repair, exposing these patients to high mortality rates. In recent years, thoracic endovascular aortic repair has proven to be a promising alternative treatment modality in specific cases. This study presents a comprehensive overview of the curren...
Background:
Management of type A aortic dissection with cerebral malperfusion poses a significant challenge. Although involvement of craniocervical vessels is undoubtedly critical, it is not well-investigated in the surgical literature.
Methods:
Between 1997-2019, 775 patients presented with acute type A aortic dissection and 80 (10%) presented...
High-quality aortic imaging plays a central role in the management of patients with thoracic aortic aneurysm. Computed tomography angiography and magnetic resonance angiography are the most commonly used techniques for thoracic aortic aneurysm diagnosis and imaging surveillance, with each having unique strengths and limitations that should be weigh...
Introduction:
To identify patients with aneurysmal degeneration of the native aorta following type A aortic dissection (TAAD), reproducible serial measurements of aortic dimensions are critical. We used a systematic workflow for measuring aortic geometry following TAAD, using computed tomography angiography data, and test its reproducibility.
Met...
Objectives:
Maximal aortic diameter is commonly used to assess aortic risk but poorly predicts the timing and location of dissection events in patients with connective tissue disease who undergo regular imaging surveillance. Hence, we aimed to use available surveillance computed tomography angiography (CTA) scans to investigate the correlation bet...
Objectives:
Current risk assessment strategies in type B aortic dissection are focused on anatomic parameters, although haemodynamic abnormalities that result in false lumen (FL) pressurization are thought to play a significant role in aortic growth. The objective of this study was to evaluate blood flow of the FL using 4D flow magnetic resonance...
Purpose:
The purpose of this study was to compare dissection flap fenestration visualization between 4D flow MRI, clinical MRI/MRA, and clinical CTA studies and describe the presence of hemodynamically active fenestration flow using 4D flow.
Materials and methods:
Nineteen patients with type B dissection (age: 57±5 years) who had undergone stand...
A 74-year-old woman expired from ascending aortic rupture 3 months following branched zone 2 endovascular aortic repair. Multiparametric image-based computational evaluation of this case suggested that the stiffness mismatch between the endograft and the native aorta increased haemodynamic loads and likely led to the rupture of the ascending aorta....
CARDIOVASCULAR IMAGES
Patients with thoracic aortic aneurysm undergo regular imaging surveillance, commonly with computed tomography angiography (CTA). Aortic diameter measurements are the standard metric for assessing aortic growth and risk for adverse events, but are subject to significant measurement variability, on the order of 1 to 5 mm, a pro...
Subclinical systolic and diastolic left ventricular (LV) dysfunction has been reported in previous echocardio-graphic studies on congenital bicuspid aortic valve (BAV). Patients with BAV commonly undergo evaluation with magnetic resonance imaging, and feature-tracking cardiovascular magnetic resonance (CMR-FT) is an emerging technique that assesses...
To evaluate the effect of MRI blood pool contrast agent on 4D flow image quality and ventricular volume measurements. Adult patients referred for clinical cardiac MRI (n = 22) were imaged with 4D flow. Patients with renal failure (n = 10) received ferumoxytol, and the remainder (n = 12) received gadofosveset trisodium. Image quality was assessed wi...
Thoracic aortic aneurysm is a common and lethal disease that requires regular imaging surveillance to determine timing of surgical repair and prevent major complications such as rupture. Current cross-sectional imaging surveillance techniques, largely based on computed tomography angiography, are focused on measurement of maximal aortic diameter, a...
PURPOSE
Bicuspid aortic valve (BAV) is a common anomaly, which is associated with dilation of the ascending aorta (AsAo), causing significant morbidity and mortality. Prior retrospective cardiac MR (CMR) studies utilizing 4D flow techniques have shown that eccentric flow patterns caused by bicuspid valve anatomy are correlated with AsAo enlargement...
Vasospasm is the primary obstacle to widespread adoption of the radial artery as a conduit in coronary artery bypass grafting. We used optical coherence tomography, a catheter-based intravascular imaging modality, to measure the degree of radial artery spasm induced by means of harvest with electrocautery or a harmonic scalpel in patients undergoin...
The radial artery's (RA) tendency to spasm when used as a bypass graft may relate to features of the RA itself. We imaged RA conduits before and after CABG in order to characterize intimal abnormalities that might relate to the risk of spasm.
RA conduits from thirty-two CABG patients were imaged intraoperatively using catheter-based optical coheren...
Multiple randomized trials have established a favorable safety profile for aprotinin use during cardiac surgery, but recent database analyses suggest an increased risk of adverse thrombotic events. Our group previously demonstrated that off-pump coronary artery bypass (OPCAB) is linked to a postoperative hypercoagulable state. In this study, we tes...
Concerns about intimal disruption and spasm have limited enthusiasm for endoscopic radial artery harvest (ERAH), although the risk of these problems after this procedure remains uncertain. Radial artery conduits were screened intraoperatively before and after ERAH vs open harvest using catheter-based high-resolution optical coherence tomography (OC...
Less-invasive options are available for surgical treatment of multivessel coronary artery disease. We hypothesized that stenting combined with grafting of the left anterior descending artery with the left internal thoracic artery through a minithoracotomy (hybrid procedure) would provide the best outcome.
Patients with equivalent numbers of coronar...
Accumulating evidence suggests that a hypercoagulable state influences early graft failure after off-pump coronary artery bypass (OPCAB). We hypothesized that regional myocardial ischemia caused by obligatory periods of coronary occlusion during OPCAB is an important trigger for this prothrombotic state.
Using a series of biomarkers, 60 consecutive...
Residual clot strands within the excised saphenous vein are an increasingly recognized sequela of endoscopic vein harvest. We hypothesized that endoscopic visualization facilitated by sealed carbon dioxide insufflation causes stagnation of blood within the saphenous vein. In the absence of prior heparin administration, this stasis provokes clot for...
Saphenous vein grafts (SVG) used for coronary artery bypass surgery (CABG) often develop a gradual luminal narrowing over the first year due to neointimal hyperplasia (NH). Although the basic science of NH is well studied, our clinical understanding of this issue is limited. The purpose of this cohort study was to investigate clinical risk factors...
Recent advances in catheter-based optical coherence tomography (OCT) have provided the necessary resolution and acquisition speed for high-quality intravascular imaging. Complications associated with clearing blood from the vessel of a living patient have prevented its wider acceptance. We identify a surgical application that takes advantage of the...
Endothelial disruption within saphenous vein and radial artery grafts increases thrombosis risk. However, no clinically applicable method for imaging the intima currently exists. We used a novel infrared imaging technology, optical coherence tomography (OCT; LightLab Imaging, Inc, Westford, Mass), to visualize the intima within harvested conduits....
: Strands of clot are frequently flushed out of saphenous vein grafts (SVG) during preparation for grafting, particularly those that are endoscopically harvested. However, saline distention at uncontrolled pressures increases graft thrombogenicity and the risk of early failure after coronary artery bypass grafting. The purpose of this prospective i...
Questions
Question (1)
I’m working on a CT image analysis project and am running into some issues with non-regular slice intervals in some of our CT data, and I’m stuck trying to find a solution.
In brief, some of the Full body (CAP) CT studies at our institution are sent to PACS reconstructed as 1.25/0.625mm slice thickness/interval in the Chest, and then 2.5/2.5 mm slice thickness/interval for the Abdomen/Pelvis, and all images are stacked in a combined CAP series. When we look at a coronal MPR of the data in a standard DICOM viewer (Osirix) we get a distorted image (screenshot attached), presumably because the slice interval is 4 times less for the Chest (0.625) compared to the Abdomen/Pelvis (2.5). Our project involves only the Chest and so we are hoping to remove the Abdomen/Pelvis image from the series altogether and return the Chest images to their normal geometry. However, when we create a new series in Osirix only including the Chest images (exported from the original CAP series with non-regular slice intervals), the chest images still appear “stretched” in the z-axis. We are stuck with the images from PACS and cannot reconstruct the raw data from the scanner (screenshot attached). There is likely a simple answer to correcting the image geometry, but we have not been successful thus far. I would greatly appreciate any guidance that others may have! Some limited metadata pasted below:
Combined Chest/Abdomen/Pelvis Series
SliceThickness (0018,0050) 1.250000
SpacingBetweenSlices (0018,0088) 0.625000
SamplesperPixel (0028,0002) 1
Rows (0028,0010) 512
Columns (0028,0011) 512
PixelSpacing (0028,0030) 0.703125\0.703125
Chest Only Series:
SliceThickness (0018,0050) 1.25
SpacingBetweenSlices (0018,0088) 0.625000
SamplesperPixel (0028,0002) 1
Rows (0028,0010) 512
Columns (0028,0011) 512
PixelSpacing (0028,0030) 0.703125\0.703125
