Todd D Reil

University of Southern California, Los Angeles, California, United States

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Publications (30)35.92 Total impact

  • Journal of Vascular Surgery - J VASC SURG. 01/2009; 49(5).
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    ABSTRACT: Plaque with dense inflammatory cells, including macrophages, thin fibrous cap and superficial necrotic/lipid core is thought to be prone-to-rupture. We report a time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) technique for detection of such markers of plaque vulnerability in human plaques. The autofluorescence of carotid plaques (65 endarterectomy patients) induced by a pulsed laser (337 nm, 0.7 ns) was measured from 831 distinct areas. The emission was resolved spectrally (360-550 nm range) and temporally (0.3 ns resolution) using a prototype fiber-optic TR-LIFS apparatus. Lesions were evaluated microscopically and quantified as to the % of different components (fibrous cap, necrotic core, inflammatory cells, foam cells, mature and degraded collagen, elastic fibers, calcification, and smooth muscle cell of the vessel wall). We determined that the spectral intensities and time-dependent parameters at discrete emission wavelengths (1) allow for discrimination (sensitivity >81%, specificity >94%) of various compositional and pathological features associated with plaque vulnerability including infiltration of macrophages into intima and necrotic/lipid core under a thin fibrous cap, and (2) show a linear correlation with plaque biochemical content: elastin (P<0.008), collagen (P<0.02), inflammatory cells (P<0.003), necrosis (P<0.004). Our results demonstrate the feasibility of TR-LIFS as a method for the identification of markers of plaque vulnerability. Current findings enable future development of TR-LIFS-based clinical devices for rapid investigation of atherosclerotic plaques and detection of those at high-risk.
    Atherosclerosis 09/2008; 204(1):156-64. · 3.71 Impact Factor
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    ABSTRACT: Carotid interposition grafts (CIP) for carotid artery revascularization can be a viable alternative to carotid endarterectomy (CEA) or carotid artery stenting (CAS) for complex carotid disease. This is a retrospective review of the UCLA 17-year experience with CIP for carotid reconstruction. Carotid operations performed between 1988 and 2005 revealed 41 CIP procedures in 39 patients using polytetrafluoroethylene (PTFE, n = 31) or reversed greater saphenous vein (Vein) (n = 10). Perioperative data and long-term follow-up for each conduit were statistically compared. There were no significant differences in demographics, risk factors, operative indications, complications, or 30-day perioperative deaths. There was one postoperative stroke in each group, for an overall stroke rate of 4.9% (PTFE 3.2%, Vein 10%). There was one asymptomatic occlusion and there were two high-grade restenoses in the PTFE group compared with one asymptomatic occlusion and one high-grade restenosis in the Vein group. Overall primary patency was 90% and the assisted primary patency was 97% for the PTFE group (mean follow-up 50 months), whereas primary patency was 80% (mean follow-up 30 months) in the Vein group. CIP is a safe and effective technique with excellent long-term follow-up for complex carotid reconstruction when CEA or CAS may be contraindicated.
    Annals of Vascular Surgery 02/2008; 22(1):63-9. · 0.99 Impact Factor
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    ABSTRACT: Superior mesenteric artery (SMA) aneurysms are rare. However, patients are frequently symptomatic on presentation and require urgent repair. SMA aneurysms have the potential for severe complications, including thrombosis or rupture, resulting in acute mesenteric ischemia and death. In patients with adhesions secondary to prior abdominal surgery, traditional open exposure of the aneurysm neck via dissection at the base of the transverse colon mesentery may be technically difficult. Endovascular exclusion of visceral artery aneurysms using covered stent grafts presents a reasonable alternative to the morbidity associated with laparotomy. We report an interesting case of a patient with a large SMA aneurysm and multiple prior laparotomies treated percutaneously with a combined expanded polytetrafluoroethylene/nitinol self-expanding stent-graft allowing maintenance of end-organ perfusion and bowel viability.
    Vascular and Endovascular Surgery 01/2008; 42(2):184-6. · 0.88 Impact Factor
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    ABSTRACT: Les pontages carotidiens (PC) peuvent être une alternative viable à l'endartériectomie (EC) ou au stenting (SC) carotidiens pour les revascularisations carotidiennes complexes. Ce travail rétrospectif est une revue de l'expérience des PC à l'UCLA sur 17 ans pour les reconstructions carotidiennes. Les interventions carotidiennes effectuées entre 1988 et 2005 ont comporté 41 PC chez 39 patients employant le polytétrafluoroéthylène (PTFE, n = 31) ou une veine grande saphène inversée (Veine, n = 10). Les données périopératoires et le suivi à long terme de chaque substitut ont été statistiquement comparés. Il n'y avait aucune différence significative dans la démographie, les facteurs de risque, les indications opératoires, les complications, ou les décès à 30 jours. Il y a eu un AVC postopératoire dans chaque groupe, soit un taux global d'AVC de 4,9% (PTFE 3,2%, Veine 10%). Il y a eu une occlusion asymptomatique et il y avait deux resténoses serrées dans le groupe PTFE contre une occlusion asymptomatique et une resténose serrée dans le groupe Veine. La perméabilité primaire globale était de 90% et la perméabilité primaire assistée de 97% pour le groupe PTFE (suivi moyen 50 mois), tandis que la perméabilité primaire était de 80% (suivi moyen 30 mois) dans le groupe Veine. Le PC est une technique sûre et efficace avec d'excellents résultats à long terme pour les reconstructions carotidiennes complexes quand l'EC ou le SC peuvent être contre-indiqués.
    Annales De Chirurgie Vasculaire. 01/2008; 22(1):69-75.
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    ABSTRACT: La revascularización carotídea mediante la interposición de injertos carotídeos(IPC) puede ser una alternativa viable a la endarterectomía carotídea (EAC) o al stenting carotídeo (SC) en la patología carotídea compleja. Este artículo describe una revisión retrospectiva de la experiencia de 17 años de la University of California Los Ángeles (UCLA) con IPC para reparación de la carótida. Entre las intervenciones carotídeas realizadas entre 1988 y 2005 se practicaron 41 IPC en 39 pacientes con politetrafluoroetileno (PTFE, n = 31) o vena safena interna invertida (vena, n = 10). Se compararon estadísticamente los datos perioperatorios y el seguimiento a largo plazo para cada conducto. No se identificaron diferencias significativas en las características demográficas de los pacientes,, factores de riesgo, indicaciones operatorias, complicaciones ni en la mortalidad perioperatoria a los 30 días. En cada grupo se produjo un accidente vascular cerebral (AVC) postoperatorio, con una tasa global de AVC del 4,9% (PTFE 3,2%, vena 10%). En el grupo de IPC con PTFE se produjo una oclusión asintomática y dos reestenosis de alto grado comparado con una oclusión asintomática y una reestenosis de alto grado en el grupo de IPC realizados con vena. La permeabilidad primaria global del grupo con PTFE fue del 90% y la permeabilidad primaria asistida fue del 97% (seguimiento medio 50 meses), mientras que en el grupo de injerto venoso la permeabilidad primaria fue del 80% (seguimiento medio 30 meses). La IPC es una técnica segura y eficaz con un excelente seguimiento a largo plazo para la reparación compleja de la carótida cuando la EAC o el SC pueden estar contraindicados.
    Anales de Cirugía Vascular. 01/2008; 22(1).
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    ABSTRACT: A new deconvolution method for the analysis of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) data is introduced and applied for tissue diagnosis. The intrinsic TR-LIFS decays are expanded on a Laguerre basis, and the computed Laguerre expansion coefficients (LEC) are used to characterize the sample fluorescence emission. The method was applied for the diagnosis of atherosclerotic vulnerable plaques. At a first stage, using a rabbit atherosclerotic model, 73 TR-LIFS in-vivo measurements from the normal and atherosclerotic aorta segments of eight rabbits were taken. The Laguerre deconvolution technique was able to accurately deconvolve the TR-LIFS measurements. More interesting, the LEC reflected the changes in the arterial biochemical composition and provided discrimination of lesions rich in macrophages/foam-cells with high sensitivity (> 85%) and specificity (> 95%). At a second stage, 348 TR-LIFS measurements were obtained from the explanted carotid arteries of 30 patients. Lesions with significant inflammatory cells (macrophages/foam-cells and lymphocytes) were detected with high sensitivity (> 80%) and specificity (> 90%), using LEC-based classifiers. This study has demonstrated the potential of using TR-LIFS information by means of LEC for in vivo tissue diagnosis, and specifically for detecting inflammation in atherosclerotic lesions, a key marker of plaque vulnerability.
    Methods of Information in Medicine 01/2007; 46(2):206-11. · 1.08 Impact Factor
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    ABSTRACT: Our objective was to evaluate the impact of the ipsilateral superficial femoral artery (SFA) on percutaneous transluminal angioplasty (PTA) of the iliac arteries. From 1993 to 2005, 183 iliac lesions (179 stenoses, 4 occlusions; 37 common, 35 external, and 111 both iliac arteries) in 127 patients with disabling claudication [94 (52%)], rest pain [43 (23%)], and ulcer/gangrene [46 (25%)] were treated by PTA. TransAtlantic Inter-Society Consensus (TASC) iliac lesion types were A in 48 limbs (26%), B in 92 (50%), C in 38 (21%), and D in 5 (3%). Stents were placed selectively for primary angioplasty failure [residual stenosis (>30%) or pressure gradient (>5 mm Hg)]. Seventy-seven limbs (42%) had patent SFAs (66 intact/<50% stenosis and 11 previously bypassed, pSFA group), 28 (15%) had stenotic SFAs (50-99%, sSFA group), 51 (28%) had occluded SFAs (oSFA group), and 27 (15%) had concomitant SFA angioplasty (aSFA group). The Society for Vascular Surgery and the International Society for Cardiovascular Surgery reporting standards were followed to define outcomes. There were no perioperative deaths. Total complication rate was 1.1% (2/183, groin hematomas). The mean follow-up was 20 months (range 1-115). One hundred twenty-five limbs (68%) had PTA alone for iliac lesions, and 58 (32%) had iliac stenting (a total of 91 stents). TASC iliac lesion types and the status of the ipsilateral profunda femoris artery were not significantly different among the four groups. Seventeen limbs (9%) had subsequent infrainguinal bypass: three in the pSFA, seven in the oSFA, four in the sSFA, and three in the aSFA groups (p = 0.19). The primary patency rate was significantly decreased in the sSFA group (29% at 3 years, Kaplan-Meier log-rank, p < 0.0001) compared with the other three groups; however, there were no significant differences among the pSFA, oSFA, and aSFA groups (67%, 67%, and 86% at 3 years, respectively; p = 0.92). The continued clinical improvement rates were significantly decreased in the sSFA group (36% at 3 years, p = 0.0043) compared with the other three groups; however, there was no significant difference between the pSFA, oSFA, and aSFA groups (81%, 84%, and 75% at 3 years, respectively; p = 0.088). The assisted primary and secondary patency and limb salvage rates were not significantly different among the four groups (p > 0.40). Stratified analysis in patients with TASC type B/type C, critical limb ischemia, or claudicants revealed similar results. The primary patency and continued clinical improvement were significantly decreased in patients with stenotic SFAs, suggesting that concomitant SFA angioplasty might improve iliac patency after iliac PTA for patients with stenotic SFAs. The presence of an occluded SFA did not adversely affect the outcomes of iliac PTA. During iliac PTA, a stenotic SFA should be considered for revascularization via endovascular means but an occluded SFA can be observed.
    Annals of Vascular Surgery 07/2006; 20(4):502-11. · 0.99 Impact Factor
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    ABSTRACT: This study introduces new methods of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) data analysis for tissue characterization. These analytical methods were applied for the detection of atherosclerotic vulnerable plaques. Upon pulsed nitrogen laser (337 nm, 1 ns) excitation, TR-LIFS measurements were obtained from carotid atherosclerotic plaque specimens (57 endarteroctomy patients) at 492 distinct areas. The emission was both spectrally- (360-600 nm range at 5 nm interval) and temporally- (0.3 ns resolution) resolved using a prototype clinically compatible fiber-optic catheter TR-LIFS apparatus. The TR-LIFS measurements were subsequently analyzed using a standard multiexponential deconvolution and a recently introduced Laguerre deconvolution technique. Based on their histopathology, the lesions were classified as early (thin intima), fibrotic (collagen-rich intima), and high-risk (thin cap over necrotic core and/or inflamed intima). Stepwise linear discriminant analysis (SLDA) was applied for lesion classification. Normalized spectral intensity values and Laguerre expansion coefficients (LEC) at discrete emission wavelengths (390, 450, 500 and 550 nm) were used as features for classification. The Laguerre based SLDA classifier provided discrimination of high-risk lesions with high sensitivity (SE>81%) and specificity (SP>95%). Based on these findings, we believe that TR-LIFS information derived from the Laguerre expansion coefficients can provide a valuable additional dimension for the diagnosis of high-risk vulnerable atherosclerotic plaques.
    Proc SPIE 03/2006;
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    ABSTRACT: We report the application of the Laguerre deconvolution technique (LDT) to the analysis of in-vivo time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) data and the diagnosis of atherosclerotic plaques. TR-LIFS measurements were obtained in vivo from normal and atherosclerotic aortas (eight rabbits, 73 areas), and subsequently analyzed using LDT. Spectral and time-resolved features were used to develop four classification algorithms: linear discriminant analysis (LDA), stepwise LDA (SLDA), principal component analysis (PCA), and artificial neural network (ANN). Accurate deconvolution of TR-LIFS in-vivo measurements from normal and atherosclerotic arteries was provided by LDT. The derived Laguerre expansion coefficients reflected changes in the arterial biochemical composition, and provided a means to discriminate lesions rich in macrophages with high sensitivity (>85%) and specificity (>95%). Classification algorithms (SLDA and PCA) using a selected number of features with maximum discriminating power provided the best performance. This study demonstrates the potential of the LDT for in-vivo tissue diagnosis, and specifically for the detection of macrophages infiltration in atherosclerotic lesions, a key marker of plaque vulnerability.
    Journal of Biomedical Optics 01/2006; 11(2):021004. · 2.88 Impact Factor
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    ABSTRACT: In this study, time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) and ultrasonography were applied to detect vulnerable (high-risk) atherosclerotic plaque. A total of 813 TR-LIFS measurements were taken from carotid plaques of 65 patients, and subsequently analyzed using the Laguerre deconvolution technique. The investigated spots were classified by histopathology as thin, fibrotic, calcified, low-inflamed, inflamed and necrotic lesions. Spectral and time-resolved parameters (normalized intensity values and Laguerre expansion coefficients) were extracted from the TR-LIFS data. Feature selection for classification was performed by either analysis of variance (ANOVA) or principal component analysis (PCA). A stepwise linear discriminant analysis algorithm was developed for detecting inflamed and necrotic lesion, representing the most vulnerable plaques. These vulnerable plaques were detected with high sensitivity (>80%) and specificity (>90%). Ultrasound (US) imaging was obtained in 4 carotid plaques in addition to TR-LIFS examination. Preliminary results indicate that US provides important structural information of the plaques that could be combined with the compositional information obtained by TR-LIFS, to obtain a more accurate diagnosis of vulnerable atherosclerotic plaque.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2006; 1:2663-6.
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    ABSTRACT: Heparin use, both prophylactically and therapeutically, is prevalent among hospitalized patients. Patients on heparin may develop a thrombocytopenia that is self-limited. Fewer patients develop a heparin-induced thrombocytopenia that can cause severe bleeding and thrombosis owing to intravascular platelet aggregation. The authors present a case report of heparin-induced thrombocytopenia in a patient who underwent aortic arch and aortic valve replacement that resulted in bilateral above-knee amputations. The patient developed limb ischemia related to heparin-associated thrombosis, but had a delay in antibody seroconversion. Early and accurate diagnosis of heparin-induced thrombocytopenia requires a high clinical suspicion and may be present despite the absence of serum antibodies.
    Vascular and Endovascular Surgery 01/2006; 40(2):161-4. · 0.88 Impact Factor
  • The Journal of trauma 11/2005; 59(4):1012-7. · 2.35 Impact Factor
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    ABSTRACT: Accumulation of numerous macrophages in the fibrous cap is a key identifying feature of plaque inflammation and vulnerability. This study investigates the use of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) as a potential tool for detection of macrophage foam cells in the intima of atherosclerotic plaques. Experiments were conducted in vivo on 14 New Zealand rabbits (6 control, 8 hypercholesterolemic) following aortotomy to expose the intimal luminal surface of the aorta. Tissue autofluorescence was induced with a nitrogen pulse laser (337 nm, 1 ns). Lesions were histologically classified by the percent of collagen or macrophage foam cells as well as thickness of the intima. Using parameters derived from the time-resolved fluorescence emission of plaques, we determined that intima rich in macrophage foam cells can be distinguished from intima rich in collagen with high sensitivity (>85%) and specificity (>95%). This study demonstrates, for the first time, that a time-resolved fluorescence-based technique can differentiate and demark macrophage content versus collagen content in vivo. Our results suggest that TR-LIFS technique can be used in clinical applications for identification of inflammatory cells important in plaque formation and rupture.
    Atherosclerosis 08/2005; 181(2):295-303. · 3.71 Impact Factor
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    ABSTRACT: To evaluate the feasibility, safety, and histological response of laparoscopic external aortic wrap implantation in conjunction with an endovascular stent/stent-graft placement in the infrarenal aorta in a porcine model. Seven swine underwent laparoscopic retroperitoneal placement of a custom-made Dacron fabric wrap placed around the infrarenal aorta to create a landing zone for an endovascularly placed aortic stent/stent-graft. Technical success was achieved in all animals without any major complications. Follow-up ranged from 1 to 4 weeks. At necropsy, the external wraps were well incorporated into the adventitia, and the stents/stent-grafts were well incorporated into the intima. Small patches of medial necrosis of the aortic wall were observed in one animal in the stent model and in two animals in the stent-graft model. There was no transmural necrosis observed. CONCLUSIONS This adjunct technique, an external wrap around the infrarenal aorta combined with endovascular grafting, is feasible and deserves further studies into how it may be used to facilitate endovascular repair of aortic aneurysms. We hypothesize that our new device could provide capability of altering the proximal neck morphology of abdominal aortic aneurysm and reinforcement to the aortic wall. This, in turn, could improve eligibility for endovascular aneurysm repair and prevent or treat type I endoleak and graft migration. Future investigations will involve evaluation of the long-term effect of the external aortic wrap on the integrity of the aortic wall in an animal model and testing the clinical usefulness of this new technique.
    Journal of Vascular Surgery 07/2005; 41(6):1031-5. · 2.88 Impact Factor
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    ABSTRACT: This study investigates the ability of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) to detect inflammation in atherosclerotic lesion, a key feature of plaque vulnerability. A total of 348 TR-LIFS measurements were taken from carotid plaques of 30 patients, and subsequently analyzed using the Laguerre deconvolution technique. The investigated spots were classified as Early, Fibrotic/Calcified or Inflamed lesions. A stepwise linear discriminant analysis algorithm was developed using spectral and TR features (normalized intensity values and Laguerre expansion coefficients at discrete emission wavelengths, respectively). Features from only three emission wavelengths (390, 450 and 500 nm) were used in the classifier. The Inflamed lesions were discriminated with sensitivity > 80% and specificity > 90 %, when the Laguerre expansion coefficients were included in the feature space. These results indicate that TR-LIFS information derived from the Laguerre expansion coefficients at few selected emission wavelengths can discriminate inflammation in atherosclerotic plaques. We believe that TR-LIFS derived Laguerre expansion coefficients can provide a valuable additional dimension for the detection of vulnerable plaques.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2005; 6:6559-62.
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    ABSTRACT: Carotid endarterectomy (CEA) has been demonstrated to be safe and effective in elderly patients. Our aim was to analyze and compare outcome and cost of CEA in both elderly and younger patient groups. A total of 125 consecutive patients who underwent CEA were examined retrospectively and grouped according to age (<80 years old, n = 95; and >or=80 years old, n = 30). The actual total costs and itemized costs were analyzed, and diagnosis-related group (DRG) code payor mix were identified. Patient demographics and risk factors were similar except for a greater incidence of coronary artery disease (CAD) in the >or=80 group than in these <80 (43.3% vs. 21.1%, p < 0.05). Patients had similar minor complication rates; however, the >or=80 group had higher perioperative major complications (16.7% vs. 1.1%, p < 0.01). There were no deaths and there was one perioperative stroke, which occurred in the <80 group. Mean length of stay (LOS), intensive care unit (ICU) LOS, and ICU admissions were greater in the >or=80 group. Cost figures were normalized to a base value of 10 US dollars to maintain proprietary data. Actual total costs of CEA were 131.50 US dollars for the >or=80 group and $100 for the <80 group (p < 0.001). Significant cost differences were found in ICU room costs, and costs for clinical laboratory, radiology imaging, other specialty consults, operating room, and ancillary services in the >or=80 group compared with the <80 group. These results show that the cost of CEA in the elderly is significantly greater than that for younger patients. This difference can be attributed to a greater number of major complications in the more elderly group, who require increased ICU stay, and thus require more clinical laboratory, radiology imaging, and specialty consult service resources. Consideration should be given for a DRG modifier code to increase hospital reimbursement for increased associated costs in elderly patients undergoing CEA.
    Annals of Vascular Surgery 11/2004; 18(6):729-35. · 0.99 Impact Factor
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    ABSTRACT: Purpose. The purpose of this study is to evaluate the feasibility of using an external aortic wrap in conjunction with an endovascular graft and to examine the histological response. Methods. Six female pigs, 56–84 kg, underwent laparoscopic retroperitoneal placement of homemade aortic wraps made of Dacron fabric and specially designed straps just below the renal arteries. One week later, stents (one 12 mm × 4 cm Wallstent, two 308 Palmaz stents) were inserted into the infrarenal aorta for preliminary experiments in three pigs, and stent-grafts (13 mm × 5 cm Viabahn) were placed in three pigs. The stents and stent-grafts were aligned with the proximal edge of the aortic wrap, and the balloon was expanded. One animal was prematurely sacrificed. The pigs were followed for 1 to 3 weeks in stent models and for 4 weeks in stent-graft models. The animals were then sacrificed, and abdominal aortas were harvested for histological examination. Results. Technical success was achieved in all animals without complications. One animal was prematurely sacrificed due to cerebral edema secondary to anesthesia. Laparoscopic operative time was 2:42 ± 0:47, and 0:43 ± 0:15 for stent placement. Gross examination of the samples revealed fibrosis external to the device at 1- and 3-week time-points; by 3 weeks the wrap was partially incorporated into the adventitia. Stents and stent-grafts were well incorporated into the intima and no migration was observed. Histological examination of all samples revealed a foreign-body response. Sections taken from beneath the device edges revealed necrosis localized to the muscularis and adventitial aortic junction; however, sections taken from beneath the device body showed no signs of necrosis and the vasa vasorum of the aortic wall was intact. Conclusions. Coordinate laparoscopic external aortic wrapping and stent-grafting is feasible in a porcine model. Aortic wall necrosis was limited. This adjunct to endovascular graft repair of abdominal aortic aneurysms may enhance eligibility for patients with large aortic neck and prevent proximal type 1 endoleak.
    Journal of Surgical Research - J SURG RES. 01/2004; 121(2):324-325.
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    ABSTRACT: Time-resolved laser-induced fluorescence spectroscopy (tr-LIFS) has been studied as a potential tool for in vivo diagnosis of atherosclerotic lesions. This study is to evaluate the potential of a compact fiber-optics based tr-LIFS instrument developed in our laboratory for in vivo analysis of atherosclerotic plaque composition. Time-resolved fluorescence spectroscopy studies were performed in vivo on fifteen New Zealand White rabbits (atherosclerotic: N=8, control: N=7). Time-resolved fluorescence spectra were acquired (range: 360-600 nm, increment: 5 nm, total acquisition time: 65 s) from normal aorta wall and lesions in the abdominal aorta. Data were analyzed in terms of fluorescence emission spectra and wavelength specific lifetimes. Following trichrome staining, tissue specimens were analyzed histopathologically in terms of intima/media thickness and biochemical composition (collagen, elastin, foam cells, and etc). Based on intimal thickness, the lesions were divided into thin and thick lesions. Each group was further separated into two categories: collagen rich lesions and foam cell rich lesions based on their biochemical composition. The obtained spectral and time domain fluorescence signatures were subsequently correlated to the histopathological findings. The results have shown that time-domain fluorescence spectral features can be used in vivo to separate atherosclerotic lesions from normal aorta wall as well discrimination within certain types of lesions.
    Proc SPIE 01/2004;
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    ABSTRACT: This study investigates the ability of new analytical methods of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) data to characterize tissue in-vivo, such as the composition of atherosclerotic vulnerable plaques. A total of 73 TR-LIFS measurements were taken in-vivo from the aorta of 8 rabbits, and subsequently analyzed using the Laguerre deconvolution technique. The investigated spots were classified as normal aorta, thin or thick lesions, and lesions rich in either collagen or macrophages/foam-cells. Different linear and nonlinear classification algorithms (linear discriminant analysis, stepwise linear discriminant analysis, principal component analysis, and feedforward neural networks) were developed using spectral and TR features (ratios of intensity values and Laguerre expansion coefficients, respectively). Normal intima and thin lesions were discriminated from thick lesions (sensitivity >90%, specificity 100%) using only spectral features. However, both spectral and time-resolved features were necessary to discriminate thick lesions rich in collagen from thick lesions rich in foam cells (sensitivity >85%, specificity >93%), and thin lesions rich in foam cells from normal aorta and thin lesions rich in collagen (sensitivity >85%, specificity >94%). Based on these findings, we believe that TR-LIFS information derived from the Laguerre expansion coefficients can provide a valuable additional dimension for in-vivo tissue characterization.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2004; 2:1372-5.

Publication Stats

230 Citations
35.92 Total Impact Points

Institutions

  • 2008
    • University of Southern California
      Los Angeles, California, United States
  • 1999–2008
    • University of California, Los Angeles
      • • Division of Vascular Surgery
      • • Department of Surgery
      Los Angeles, CA, United States
  • 2006
    • University of California, Davis
      • Department of Biomedical Engineering
      Davis, CA, United States
  • 2004
    • Cedars-Sinai Medical Center
      Los Angeles, California, United States
  • 2002
    • Wilford Hall Ambulatory Surgery Center
      Lackland Air Force Base, Texas, United States