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1.
J Neurointerv Surg ; 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38238009

RESUMO

BACKGROUND: Detecting and segmenting intracranial aneurysms (IAs) from angiographic images is a laborious task. OBJECTIVE: To evaluates a novel deep-learning algorithm, named vessel attention (VA)-Unet, for the efficient detection and segmentation of IAs. METHODS: This retrospective study was conducted using head CT angiography (CTA) examinations depicting IAs from two hospitals in China between 2010 and 2021. Training included cases with subarachnoid hemorrhage (SAH) and arterial stenosis, common accompanying vascular abnormalities. Testing was performed in cohorts with reference-standard digital subtraction angiography (cohort 1), with SAH (cohort 2), acquired outside the time interval of training data (cohort 3), and an external dataset (cohort 4). The algorithm's performance was evaluated using sensitivity, recall, false positives per case (FPs/case), and Dice coefficient, with manual segmentation as the reference standard. RESULTS: The study included 3190 CTA scans with 4124 IAs. Sensitivity, recall, and FPs/case for detection of IAs were, respectively, 98.58%, 96.17%, and 2.08 in cohort 1; 95.00%, 88.8%, and 3.62 in cohort 2; 96.00%, 93.77%, and 2.60 in cohort 3; and, 96.17%, 94.05%, and 3.60 in external cohort 4. The segmentation accuracy, as measured by the Dice coefficient, was 0.78, 0.71, 0.71, and 0.66 for cohorts 1-4, respectively. VA-Unet detection recall and FPs/case and segmentation accuracy were affected by several clinical factors, including aneurysm size, bifurcation aneurysms, and the presence of arterial stenosis and SAH. CONCLUSIONS: VA-Unet accurately detected and segmented IAs in head CTA comparably to expert interpretation. The proposed algorithm has significant potential to assist radiologists in efficiently detecting and segmenting IAs from CTA images.

2.
J Thorac Cardiovasc Surg ; 166(6): 1583-1593.e2, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37295642

RESUMO

BACKGROUND: In ascending thoracic aortic aneurysm risk stratification, aortic area/height ratio is a reasonable alternative to maximum diameter. Biomechanically, aortic dissection may be initiated by wall stress exceeding wall strength. Our objective was to evaluate the association between aortic area/height and peak aneurysm wall stresses in relation to valve morphology and 3-year all-cause mortality. METHODS: Finite element analysis was performed on 270 ascending thoracic aortic aneurysms (46 associated with bicuspid and 224 with tricuspid aortic valves) in veterans. Three-dimensional aneurysm geometries were reconstructed from computed tomography and models developed accounting for prestress geometries. Fiber-embedded hyperelastic material model was applied to obtain aneurysm wall stresses during systole. Correlations of aortic area/height ratio and peak wall stresses were compared across valve types. Area/height ratio was evaluated across peak wall stress thresholds obtained from proportional hazards models of 3-year all-cause mortality, with aortic repair treated as a competing risk. RESULTS: Aortic area/height 10 cm2/m or greater coincided with 23/34 (68%) 5.0 to 5.4 cm and 20/24 (83%) 5.5 cm or greater aneurysms. Area/height correlated weakly with peak aneurysm stresses: for tricuspid valves, r = 0.22 circumferentially and r = 0.24 longitudinally; and for bicuspid valves, r = 0.42 circumferentially and r = 0.14 longitudinally. Age and peak longitudinal stress, but not area/height, were independent predictors of all-cause mortality (age: hazard ratio, 2.20 per 9-year increase, P = .013; peak longitudinal stress: hazard ratio, 1.78 per 73-kPa increase, P = .035). CONCLUSIONS: Area/height was more predictive of high circumferential stresses in bicuspid than tricuspid valve aneurysms, but similarly less predictive of high longitudinal stresses in both valve types. Peak longitudinal stress, not area/height, independently predicted all-cause mortality. VIDEO ABSTRACT.


Assuntos
Aneurisma da Aorta Torácica , Doença da Válvula Aórtica Bicúspide , Doenças das Valvas Cardíacas , Veteranos , Humanos , Doenças das Valvas Cardíacas/complicações , Doenças das Valvas Cardíacas/diagnóstico por imagem , Aneurisma da Aorta Torácica/diagnóstico por imagem , Aneurisma da Aorta Torácica/etiologia , Aneurisma da Aorta Torácica/cirurgia , Aorta , Valva Aórtica/diagnóstico por imagem , Valva Aórtica/cirurgia
3.
Semin Thorac Cardiovasc Surg ; 35(3): 447-456, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35690227

RESUMO

Risk of aortic dissection in ascending thoracic aortic aneurysms is not sufficiently captured by size-based metrics. From a biomechanical perspective, dissection may be initiated when wall stress exceeds wall strength. Our objective was to assess the association between aneurysm peak wall stresses and 3-year all-cause mortality. Finite element analysis was performed in 273 veterans with chest computed tomography for surveillance of ascending thoracic aortic aneurysms. Three-dimensional geometries were reconstructed and models developed accounting for prestress geometries. A fiber-embedded hyperelastic material model was applied to obtain circumferential and longitudinal wall stresses under systolic pressure. Patients were followed up to 3 years following the scan to assess aneurysm repair and all-cause mortality. Fine-Gray subdistribution hazards were estimated for all-cause mortality based on age, aortic diameter, and peak wall stresses, treating aneurysm repair as a competing risk. When accounting for age, subdistribution hazard of mortality was not significantly increased by peak circumferential stresses (p = 0.30) but was significantly increased by peak longitudinal stresses (p = 0.008). Aortic diameter did not significantly increase subdistribution hazard of mortality in either model (circumferential model: p = 0.38; longitudinal model: p = 0.30). The effect of peak longitudinal stresses on subdistribution hazard of mortality was maximized at a binary threshold of 355kPa, which captured 34 of 212(16%) patients with diameter <5 cm, 11 of 36(31%) at 5.0-5.4 cm, and 11 of 25(44%) at ≥5.5 cm. Aneurysm peak longitudinal stresses stratified by age and diameter were associated with increased hazard of 3-year all-cause mortality in a veteran cohort. Risk prediction may be enhanced by considering peak longitudinal stresses.

4.
J Am Heart Assoc ; 11(7): e024571, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-35348001

RESUMO

Background Abdominal aortic aneurysm (AAA) screening programs have been active in the United States since 2005, but are not the only way AAAs are detected. AAA management and outcomes have not been investigated broadly in the context of "implicit AAA screening," whereby radiologic examinations not intended for focused screening can identify AAAs. Methods and Results We examined the association between imaging-based AAA screening, both explicit and implicit, and various outcomes for ≈1.6 million veterans in the Veterans Affairs health care system from 2005 to 2015. Screened-positive, screened-negative, and unscreened veterans were identified in the overall cohort and within a subgroup of veterans aged 65 years in 2005. The yearly composite screening rate increased over 10 years, from 11.7% to 18.3%, whereas the screened-positive rate decreased from 7.3% to 4.9%. Only 12.9% of screening examinations were explicit AAA screening ultrasounds. The subgroup's composite screening rate was 74% within its 10-year eligibility window, with implicit screening accounting for 91.8% of examinations. In the 2005 subgroup, all-cause mortality and Charlson comorbidity scores were higher for veterans who underwent screening compared with those unscreened (31.2% versus 23.1% and 0.47 versus 0.25, respectively; P<0.001). AAA rupture rates were similar between those unscreened and screened-negative individuals. Conclusions Accounting for both explicit and implicit screening, AAA screening in the Veterans Affairs population has moderate reach. Efforts to expand explicit AAA screening are not likely to impact either all-cause mortality or AAA rupture on the population scale as significantly as a careful accounting for and use of implicit screening data.


Assuntos
Aneurisma da Aorta Abdominal , Veteranos , Idoso , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/epidemiologia , Atenção à Saúde , Humanos , Programas de Rastreamento/métodos , Fatores de Risco , Ultrassonografia , Estados Unidos/epidemiologia
5.
Quant Imaging Med Surg ; 11(2): 823-830, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33532280

RESUMO

Accurate and reproducible measurement of abdominal aortic aneurysm (AAA) size is an essential component of patient management, and most reliably performed at CT using a multiplanar reformat (MPR) strategy. This approach is not universal, however. This study aims to characterize the measurement error present in routine clinical assessment of AAAs and the potential clinical ramifications. Patients were included if they had AAA assessed by CT and/or MRI at two time points at least 6 months apart. Clinical maximal AAA diameter, assessed by non-standardized methods, was abstracted from the radiology report at each time point and compared to the reference aneurysm diameter measured using a MPR strategy. Discrepancies between clinical and reference diameters, and associated aneurysm enlargement rates were analyzed. Two hundred thirty patients were included, with average follow-up 3.3±2.5 years. When compared to MPR-derived diameters, clinical aneurysm measurement inaccuracy was, on average, 3.3 mm. Broad limits of agreement were found for both clinical diameters [-6.7 to +6.5 mm] and aneurysm enlargement rates [-4.6 to +4.2 mm/year] when compared to MPR-based measures. Of 78 AAAs measuring 5-6 cm by the MPR method, 21 (26.9%) were misclassified by the clinical measurement with respect to a common repair threshold (5.5 cm), of which 5 were misclassified as below, and 16 were misclassified as above the threshold. The clinical use of non-standardized AAA measurement strategies can lead to incorrect classification of AAAs as larger or smaller than the commonly accepted repair threshold of 5.5 cm and can induce large errors in quantification of aneurysm enlargement rate.

6.
IEEE Open J Eng Med Biol ; 1: 116-122, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33294851

RESUMO

OBJECTIVE: Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are widely researched as contrast agents in clinical magnetic resonance imaging (MRI). SPIONs are frequently coated with anti-biofouling substances such as poly(ethylene glycol) (PEG) to prevent protein deposition and improve circulation time in vivo. However, few previous studies have comprehensively examined optimization of SPION MR properties with respect to physicochemical properties of the core SPION and the polymeric coating. The aim of this study is to determine effects of different methods of chemical attachment of a polymer, polymer chain length, and polymer coating density on the MR relaxivities of SPIONs, thereby contributing to a better understanding of the interaction of these parameters and the efficacy of the designed agent. RESULTS: These studies indicate that the chemical composition and, in particular, the hydrophobicity/hydrophilicity of the chemical group linking PEG chains to a SPION core may play a larger role in the resulting MR relaxivities than other variable properties such as SPION core size and PEG chain length. CONCLUSIONS: The method of SPION fabrication and chemical composition of the coating play a significant role in the MR relaxivities of the resulting particles. These results should be considered in the fabrication of particles for clinical purposes, particularly when optimization of the MR relaxivities is desired.

7.
Laryngoscope ; 129(9): 2045-2052, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-30698840

RESUMO

OBJECTIVES: Medical three-dimensional (3D) printing, the fabrication of handheld models from medical images, has the potential to become an integral part of otolaryngology-head and neck surgery (Oto-HNS) with broad impact across its subspecialties. We review the basic principles of this technology and provide a comprehensive summary of reported clinical applications in the field. METHODS: Standard bibliographic databases (MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, Web of Science, and The Cochrane Central Registry for Randomized Trials) were searched from their inception to May 2018 for the terms: "3D printing," "three-dimensional printing," "rapid prototyping," "additive manufacturing," "computer-aided design," "bioprinting," and "biofabrication" in various combinations with the terms: "ptolaryngology," "head and neck surgery," and "otology." Additional articles were identified from the references of retrieved articles. Only studies describing clinical applications of 3D printing were included. RESULTS: Of 5,532 records identified through database searching, 87 articles were included for qualitative synthesis. Widespread implementation of 3D printing in Oto-HNS is still at its infancy. Nonetheless, it is increasingly being utilized across all subspecialties from preoperative planning to design and fabrication of patient-specific implants and surgical guides. An emerging application considered highly valuable is its use as a teaching tool for medical education and surgical training. CONCLUSIONS: As technology and training standards evolve and as healthcare moves toward personalized medicine, 3D printing is emerging as a key technology in patient care in Oto-HNS. Treating physicians and surgeons who wish to stay abreast of these developments will benefit from a fundamental understanding of the principles and applications of this technology. Laryngoscope, 129:2045-2052, 2019.


Assuntos
Otolaringologia/instrumentação , Impressão Tridimensional , Cirurgia Assistida por Computador/instrumentação , Materiais Biocompatíveis , Bioimpressão , Desenho Assistido por Computador , Humanos , Modelos Anatômicos , Planejamento de Assistência ao Paciente , Próteses e Implantes
8.
J Surg Oncol ; 116(3): 407-415, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28753252

RESUMO

BACKGROUND AND OBJECTIVES: 3D-printed models are increasingly used for surgical planning. We assessed the utility, accuracy, and reproducibility of 3D printing to assist visualization of complex thoracic tumors for surgical planning. METHODS: Models were created from pre-operative images for three patients using a standard radiology 3D workstation. Operating surgeons assessed model utility using the Gillespie scale (1 = inferior to 4 = superior), and accuracy compared to intraoperative findings. Model variability was assessed for one patient for whom two models were created independently. The models were compared subjectively by surgeons and quantitatively based on overlap of depicted tissues, and differences in tumor volume and proximity to tissues. RESULTS: Models were superior to imaging and 3D visualization for surgical planning (mean score = 3.4), particularly for determining surgical approach (score = 4) and resectability (score = 3.7). Model accuracy was good to excellent. In the two models created for one patient, tissue volumes overlapped by >86.5%, and tumor volume and area of tissues ≤1 mm to the tumor differed by <15% and <1.8 cm2 , respectively. Surgeons considered these differences to have negligible effect on surgical planning. CONCLUSION: 3D printing assists surgical planning for complex thoracic tumors. Models can be created by radiologists using routine practice tools with sufficient accuracy and clinically negligible variability.


Assuntos
Adenocarcinoma/diagnóstico por imagem , Modelos Anatômicos , Impressão Tridimensional , Sarcoma/diagnóstico por imagem , Neoplasias Torácicas/diagnóstico por imagem , Adenocarcinoma/patologia , Adenocarcinoma/cirurgia , Adulto , Idoso , Feminino , Humanos , Imageamento Tridimensional , Imageamento por Ressonância Magnética , Masculino , Reprodutibilidade dos Testes , Sarcoma/patologia , Sarcoma/cirurgia , Neoplasias Torácicas/patologia , Neoplasias Torácicas/cirurgia
9.
Ann Thorac Surg ; 103(6): e509-e512, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28528053

RESUMO

We describe the use of percutaneously inserted, transcatheter endovascular graft prostheses to exclude large Mustard baffle leaks in a high-surgical-risk patient. We used 3-dimensional-printed models to determine feasibility and to plan the procedure. Telescoping thoracic and abdominal graft extensions were placed in the inferior and superior limbs of the systemic venous pathways. An atrial septal defect occluder device was also used to close a separate leak not covered by the endovascular graft prostheses. This approach may be useful in patients with complex, large intraatrial baffles that require repair of baffle leaks not amenable to device closure.


Assuntos
Implante de Prótese Vascular , Prótese Vascular , Procedimentos Endovasculares , Stents , Transposição dos Grandes Vasos/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Reoperação
10.
Eur Heart J Cardiovasc Imaging ; 18(1): 19-30, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27013245

RESUMO

AIMS: To evaluate the incremental value of low endothelial shear stress (ESS) combined with high-resolution magnetic resonance imaging (MRI)- and computed tomography angiography (CTA)-based imaging for the prediction of inflamed plaque. METHODS AND RESULTS: Twelve hereditary hyperlipidaemic rabbits underwent quantitative analysis of plaque in the thoracic aorta with 256-slice CTA and USPIO-enhanced (ultra-small superparamagnetic nanoparticles, P904) 1.5-T MRI at baseline and at 6-month follow-up. Computational fluid dynamics using CTA-based 3D reconstruction of thoracic aortas identified the ESS patterns in the convex and concave curvature subsegments of interest. Subsegments with low baseline ESS exhibited significant increase in wall thickness and plaque inflammation by MRI, in non-calcified plaque burden by CTA, and developed increased plaque size, lipid and inflammatory cell accumulation (high-risk plaque features) at follow-up by histopathology. Multiple regression analysis identified baseline ESS and inflammation by MRI to be independent predictors of plaque progression, while receiver operating curve analysis revealed baseline ESS alone or in combination with inflammation by MRI as the strongest predictor for augmented plaque burden and inflammation (low ESS at baseline: AUC = 0.84, P < 0.001; low ESS and inflammation by molecular MRI at baseline: AUC = 0.89, P < 0.001). CONCLUSION: Low ESS predicts progression of plaque burden and inflammation as assessed by non-invasive USPIO-enhanced MRI. Combined non-invasive assessment of ESS and imaging of inflammation may serve to predict plaque with high-risk features.


Assuntos
Angiografia por Tomografia Computadorizada/métodos , Endotélio Vascular/patologia , Hiperlipidemias/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Placa Aterosclerótica/diagnóstico por imagem , Resistência ao Cisalhamento , Animais , Aorta/diagnóstico por imagem , Aorta/patologia , Biópsia por Agulha , Intervalos de Confiança , Modelos Animais de Doenças , Progressão da Doença , Hiperlipidemias/patologia , Imuno-Histoquímica , Inflamação/diagnóstico por imagem , Inflamação/patologia , Modelos Lineares , Masculino , Imagem Molecular/métodos , Variações Dependentes do Observador , Placa Aterosclerótica/patologia , Valor Preditivo dos Testes , Curva ROC , Coelhos , Distribuição Aleatória , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Ultrassonografia de Intervenção
11.
3D Print Med ; 3(1): 14, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29782619

RESUMO

In this work, we provide specific clinical examples to demonstrate basic practical techniques involved in image segmentation, computer-aided design, and 3D printing. A step-by-step approach using United States Food and Drug Administration cleared software is provided to enhance surgical intervention in a patient with a complex superior sulcus tumor. Furthermore, patient-specific device creation is demonstrated using dedicated computer-aided design software. Relevant anatomy for these tasks is obtained from CT Digital Imaging and Communications in Medicine images, leading to the generation of 3D printable files and delivery of these files to a 3D printer.

12.
3D Print Med ; 2(1): 5, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-30050977

RESUMO

Medical 3D printing holds the potential of transforming personalized medicine by enabling the fabrication of patient-specific implants, reimagining prostheses, developing surgical guides to expedite and transform surgical interventions, and enabling a growing multitude of specialized applications. In order to realize this tremendous potential in frontline medicine, an understanding of the basic principles of 3D printing by the medical professionals is required. This primer underlines the basic approaches and tools in 3D printing, starting from patient anatomy acquired through cross-sectional imaging, in this case Computed Tomography (CT). We describe the basic principles using the relatively simple task of separation of the relevant anatomy to guide aneurysm repair. This is followed by exploration of more advanced techniques in the creation of patient-specific surgical guides and prostheses for a patient with extensive pleomorphic sarcoma using Computer Aided Design (CAD) software.

13.
PLoS One ; 8(4): e63079, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23638180

RESUMO

OBJECTIVE: To test the hypothesis that wide area detector face transplant surgical planning CT angiograms with simulated lower radiation dose and iterative reconstruction (AIDR3D) are comparable in image quality to those with standard tube current and filtered back projection (FBP) reconstruction. MATERIALS AND METHODS: The sinograms from 320-detector row CT angiography of four clinical candidates for face transplantation were processed utilizing standard FBP, FBP with simulated 75, 62, and 50% tube current, and AIDR3D with corresponding dose reduction. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured at muscle, fat, artery, and vein. Image quality for each reconstruction strategy was assessed by two independent readers using a 4-point scale. RESULTS: Compared to FBP, the median SNR and CNR for AIDR3D images were higher at all sites for all 4 different tube currents. The AIDR3D with simulated 50% tube current achieved comparable SNR and CNR to FBP with standard dose (median muscle SNR: 5.77 vs. 6.23; fat SNR: 6.40 vs. 5.75; artery SNR: 43.8 vs. 45.0; vein SNR: 54.9 vs. 55.7; artery CNR: 38.1 vs. 38.6; vein CNR: 49.0 vs. 48.7; all p-values >0.19). The interobserver agreement in the image quality score was good (weighted κ = 0.7). The overall score and the scores for smaller arteries were significantly lower when FBP with 50% dose reduction was used. The AIDR3D reconstruction images with 4 different simulated doses achieved a mean score ranging from 3.68 to 3.82 that were comparable to the scores from images reconstructed using FBP with original dose (3.68-3.77). CONCLUSIONS: Simulated radiation dose reduction applied to clinical CT angiography for face transplant planning suggests that AIDR3D allows for a 50% reduction in radiation dose, as compared to FBP, while preserving image quality.


Assuntos
Angiografia , Transplante de Face , Proteção Radiológica , Tomografia Computadorizada por Raios X , Adulto , Relação Dose-Resposta à Radiação , Humanos , Masculino , Interpretação de Imagem Radiográfica Assistida por Computador , Razão Sinal-Ruído
14.
Eplasty ; 12: e57, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23308304

RESUMO

OBJECTIVE: Screening for full face transplantation candidates includes computed tomographic vascular mapping of the external carotid distribution for potential arterial and venous anastomoses. The purpose of this study is to illustrate the benefits and drawbacks of cine computed tomographic imaging for preoperative vascular mapping compared with best arterial and venous phase static images. METHODS: Two image data sets were retrospectively created and compared for diagnostic findings. The first set of images was the clinical cine computed tomographic acquisition including all phases. The second set of images was composed of the best arterial and best venous phases extracted from the cine loop and determined by the quality of contrast enhancement. For each patient, the benefits and drawbacks of the cine loop were documented in consensus by a plastic surgeon and a radiologist. RESULTS: Cine loop analysis identified retrograde arterial filling not illustrated on the static images alone. Cine assessment identified most of the major vessels necessary for surgery, whereas the static images depicted small vessels more clearly, particularly in the crowded vessel takeoffs. CONCLUSIONS: Cine computed tomographic images provide data on direction of blood flow, which is important for preoperative planning. Combination of cine computed tomographic and the best static images will allow comprehensive vascular assessment necessary for future successful full face transplantation.

15.
Eplasty ; 11: e51, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22184509

RESUMO

OBJECTIVE: Face transplantation replaces substantial defects with anatomically identical donor tissues; preoperative vascular assessment relies on noninvasive imaging to separate and characterize the external carotid vessels and branches. The objective is to describe and illustrate vascular considerations for face transplantation candidates. METHODS: Novel noninvasive imaging using computed tomography and magnetic resonance imaging over 3 spatial dimensions plus time was developed and tested in 4 face transplant candidates. Precontrast images assessed bones and underlying metal. Contrast media was used to delineate and separate arteries from veins. For computed tomography, acquisition over multiple time points enabled the computation of tissue perfusion metrics. Time-resolved magnetic resonance angiography was performed to separate arterial and venous phases. RESULTS: The range of circulation times for the external carotid system was 6 to 14 seconds from arterial blush to loss of venous enhancement. Precontrast imaging provided a roadmap of bones and metal. Among the 4 patients, 3 had surgical clips, metal implants, or both within 1 cm of major vessels considered for surgery. Contrast-enhanced wide area detector computed tomographic data acquired in the axial mode separated these structures and provided arterial and venous images for planning the surgical anastomoses. Magnetic resonance imaging was able to distinguish between the large vessels from the external carotid systems. CONCLUSIONS: Vascular imaging maps are challenging in face transplantation because of the rapid circulation times and artifact from the initial injury, prior reconstructive attempts, or both. Nevertheless, face transplant candidates require high spatial and temporal resolution vascular imaging to determine those vessels appropriate for surgical anastomoses.

16.
Plast Reconstr Surg ; 128(4): 883-891, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21921764

RESUMO

BACKGROUND: Facial allotransplantation requires a detailed arterial and venous assessment for surgical planning. Target vessels are often depleted by multiple reconstructive attempts or the severe facial injury itself. The purpose of this study was to retrospectively compare the diagnostic performance of computed tomography and magnetic resonance angiography in the preoperative assessment. METHODS: Four-dimensional (three spatial planes plus time) computed tomographic and magnetic resonance images including 126 potential vessels (76 arteries and 50 veins) from five candidates were analyzed independently by two radiologists using a four-point image quality scale. Computed tomographic versus magnetic resonance image quality was compared directly, using a computed tomographic angiography consensus read as reference standard. Vessels with metal artifact on magnetic resonance imaging, computed tomography, or both underwent separate analyses to determine the impact of metal implants on image quality. RESULTS: Considering all 126 vessels, the mean computed tomographic image quality was superior to that of magnetic resonance angiography. When considering individual vessels, all except for major neck vessels were better visualized by computed tomography. Images of 26 vessels were degraded by metal artifact; magnetic resonance image quality was inferior for those vessels. Considering images of major vessels with no metal artifact, there was no significant mean image quality difference between computed tomography and magnetic resonance imaging. CONCLUSIONS: Computed tomographic angiography should be used as the first-choice modality for preoperative imaging of facial transplant patients because, when compared with magnetic resonance imaging, the visualization of small vessels is far superior and images have fewer artifacts. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, II.


Assuntos
Face/irrigação sanguínea , Tomografia Computadorizada Quadridimensional/métodos , Angiografia por Ressonância Magnética/métodos , Procedimentos de Cirurgia Plástica/métodos , Adulto , Face/cirurgia , Feminino , Humanos , Masculino , Variações Dependentes do Observador , Cuidados Pré-Operatórios/métodos , Estudos Retrospectivos , Estudos de Amostragem , Sensibilidade e Especificidade , Estatísticas não Paramétricas , Retalhos Cirúrgicos/irrigação sanguínea , Transplante Homólogo
17.
J Comput Assist Tomogr ; 34(5): 766-9, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20861783

RESUMO

We report initial surgical planning computed tomographic protocols for composite tissue allotransplantation of the face. This complex procedure replaces missing facial structures with anatomically identical tissues, restoring form and function. Achieved results are superior to those accomplished with conventional techniques. As a growing number of patients/recipients have undergone multiple reconstructions, vascular imaging plays an increasingly critical role in surgical planning and successful execution of the operation.


Assuntos
Traumatismos Faciais/cirurgia , Transplante de Face , Tomografia Computadorizada por Raios X/métodos , Ferimentos por Arma de Fogo/cirurgia , Adulto , Traumatismos Faciais/etiologia , Humanos , Imageamento Tridimensional , Masculino , Planejamento de Assistência ao Paciente , Doses de Radiação , Transplante Homólogo
18.
Bioconjug Chem ; 21(8): 1408-12, 2010 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-20608720

RESUMO

Emerging data supports a role for negative wall remodeling in the failure of vascular interventions such as vein grafts, yet clinicians/researchers currently lack the ability to temporally/efficiently investigate adventitial surface topography/total vascular wall anatomy in vivo. We established a strategy of immobilizing commercially available iron oxide magnetic nanoparticles (Fe-NPs) onto the surface of human vein conduits to facilitate high-throughput total vascular wall demarcation with magnetic resonance (MR). Binding of activated Fe-NPs to amine groups on the surface of the veins induced a thin layer of negative contrast that differentiated the adventitia from surrounding saline signal in all MR images, enabling delineation of total wall anatomy; this was not possible in simultaneously imaged unlabeled control veins. Under the conditions of this ex vivo experiment, stable covalent binding of Fe-NPs can be achieved (dose-dependent) on human vein surface for MR detection, suggesting a potential strategy for enhancing the ability of MRI to investigate total wall adaptation and remodeling in vein graft failure.


Assuntos
Vasos Sanguíneos/química , Compostos Férricos/química , Imageamento por Ressonância Magnética , Magnetismo , Nanopartículas/química , Sítios de Ligação , Humanos , Propriedades de Superfície
19.
Int J Cardiovasc Imaging ; 26(6): 683-91, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20333469

RESUMO

The purpose of this study is to primarily evaluate the lumen area and secondarily evaluate wall area measurements of in vivo lower extremity peripheral vein bypass grafts patients using high spatial resolution, limited field of view, cardiac gated, black blood inner volume three-dimensional fast spin echo MRI. Fifteen LE-PVBG patients prospectively underwent ultrasound followed by T1-weighted and T2-weighted magnetic resonance (MR) imaging. Lumen and vessel wall areas were measured by direct planimetry. For graft lumen areas, T1- and T2-weighted measurements were compared with ultrasound. For vessel wall areas, differences between T1- and T2-weighted measurements were evaluated. There was no significant difference between ultrasound and MR lumen measurements, reflecting minimal MR blood suppression artifact. Graft wall area measured from T1-weighted images was significantly larger than that measured from T2-weighted images (P < 0.001). The mean of the ratio of T1- versus T2-weighted vessel wall areas was 1.59 (95% CI: 1.48-1.69). The larger wall area measured on T1-weighted images was due to a significantly larger outer vessel wall boundary. Very high spatial resolution LE-PVBG vessel wall MR imaging can be performed in vivo, enabling accurate measurements of lumen and vessel wall areas and discerning differences in those measures between different tissue contrast weightings. Vessel wall area differences suggest that LE-PVBG vessel wall tissues produce distinct signal characteristics under T1 and T2 MR contrast weightings.


Assuntos
Meios de Contraste , Oclusão de Enxerto Vascular/diagnóstico , Imageamento Tridimensional , Extremidade Inferior/irrigação sanguínea , Angiografia por Ressonância Magnética , Doenças Vasculares Periféricas/cirurgia , Procedimentos Cirúrgicos Vasculares , Veias/transplante , Idoso , Artefatos , Boston , Feminino , Oclusão de Enxerto Vascular/etiologia , Oclusão de Enxerto Vascular/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Tempo , Resultado do Tratamento , Ultrassonografia de Intervenção , Grau de Desobstrução Vascular , Procedimentos Cirúrgicos Vasculares/efeitos adversos , Veias/diagnóstico por imagem , Veias/patologia
20.
J Vasc Surg ; 47(6): 1235-42, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18440187

RESUMO

BACKGROUND: The remodeling of vein bypass grafts after arterialization is incompletely understood. We have previously shown that significant outward lumen remodeling occurs during the first month of implantation, but the magnitude of this response is highly variable. We sought to examine the hypothesis that systemic inflammation influences this early remodeling response. METHODS: A prospective observational study was done of 75 patients undergoing lower extremity bypass using autogenous vein. Graft remodeling was assessed using a combination of ultrasound imaging and two-dimensional high-resolution magnetic resonance imaging. RESULTS: The vein graft lumen diameter change from 0 to 1 month (22.7% median increase) was positively correlated with initial shear stress (P = .016), but this shear-dependent response was disrupted in subjects with an elevated baseline high-sensitivity C-reactive protein (hsCRP) level of >5 mg/L. Despite similar vein diameter and shear stress at implantation, grafts in the elevated hsCRP group demonstrated less positive remodeling from 0 to 1 month (13.5% vs 40.9%, P = .0072). By regression analysis, the natural logarithm of hsCRP was inversely correlated with 0- to 1-month lumen diameter change (P = .018). Statin therapy (beta = 23.1, P = .037), hsCRP (beta = -29.7, P = .006), and initial shear stress (beta = .85, P = .003) were independently correlated with early vein graft remodeling. In contrast, wall thickness at 1 month was not different between hsCRP risk groups. Grafts in the high hsCRP group tended to be stiffer at 1 month, as reflected by a higher calculated elastic modulus (E = 50.4 vs 25.1 Mdynes/cm2, P = .07). CONCLUSIONS: Early positive remodeling of vein grafts is a shear-dependent response that is modulated by systemic inflammation. These data suggest that baseline inflammation influences vein graft healing, and therefore, inflammation may be a relevant therapeutic target to improve early vein graft adaptation.


Assuntos
Braço/irrigação sanguínea , Hemodinâmica , Inflamação/fisiopatologia , Claudicação Intermitente/cirurgia , Isquemia/cirurgia , Extremidade Inferior/irrigação sanguínea , Veia Safena/transplante , Cicatrização , Adaptação Fisiológica , Idoso , Anastomose Cirúrgica/efeitos adversos , Proteína C-Reativa/metabolismo , Feminino , Humanos , Inflamação/etiologia , Inflamação/metabolismo , Inflamação/patologia , Claudicação Intermitente/etiologia , Claudicação Intermitente/patologia , Claudicação Intermitente/fisiopatologia , Isquemia/complicações , Isquemia/patologia , Isquemia/fisiopatologia , Angiografia por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fluxo Sanguíneo Regional , Veia Safena/patologia , Veia Safena/fisiopatologia , Estresse Mecânico , Fatores de Tempo , Resultado do Tratamento , Ultrassonografia Doppler Dupla
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