Amir Sajjadi - Academia.edu (original) (raw)
Papers by Amir Sajjadi
Over 250 million scrap tires are generated annually in the U.S. Historically, a significant porti... more Over 250 million scrap tires are generated annually in the U.S. Historically, a significant portion of these tires have been processed into finely ground tire rubber (GTR), or crumb rubber, for use as an additive in hot mix asphalt (HMA) pavements to improve pavement performance. Recently, improved synthetic polymer additives have been developed that more economically provide the same performance improvements as GTR. This development has decreased the demand for GTR in HMA, potentially freeing supplies of GTR for other applications. Over the past two decades, the Florida Department of Transportation (FDOT) has conducted a significant amount of research on ways to re-use waste materials such as energy generation ash, tires, glass, reclaimed asphalt pavement, and reclaimed concrete in roadway construction. FDOT initiated this study to investigate whether blending GTR with subgrade soils would be a beneficial practice. The objective of this research was to determine the effect of GTR o...
Journal of Cerebral Blood Flow & Metabolism, 2017
Optical coherence tomography (OCT) allows label-free imaging of red blood cell (RBC) flux within ... more Optical coherence tomography (OCT) allows label-free imaging of red blood cell (RBC) flux within capillaries with high spatio-temporal resolution. In this study, we utilized time-series OCT-angiography to demonstrate interruptions in capillary RBC flux in mouse brain in vivo. We noticed ∼7.5% of ∼200 capillaries had at least one stall in awake mice with chronic windows during a 9-min recording. At any instant, ∼0.45% of capillaries were stalled. Average stall duration was ∼15 s but could last over 1 min. Stalls were more frequent and longer lasting in acute window preparations. Further, isoflurane anesthesia in chronic preparations caused an increase in the number of stalls. In repeated imaging, the same segments had a tendency to stall again over a period of one month. In awake animals, functional stimulation decreased the observance of stalling events. Stalling segments were located distally, away from the first couple of arteriolar-side capillary branches and their average RBC an...
Cancer Research, 2016
Background: Dynamic Diffuse optical imaging using near-infrared light was shown to be promising m... more Background: Dynamic Diffuse optical imaging using near-infrared light was shown to be promising method for neoadjuvant therapy monitoring as an alternative functional imaging that is low-cost, non-invasive, portable, safe and simple to operate. While optical breast imaging methods rely on "static" assessments of tissue oxy- and deoxy- hemoglobin concentration without contrast agents, they are insufficient for clinical applications. Dynamic tomographic optical imaging induces tumor-sensitive hemodynamic variations, as a contrast mechanism, driven by fractional mammographic compression. These tumor contrast measurements are governed by interlay of tissue biomechanics and oxygen metabolism. In this study we seek to evaluate the predictive value of these biomarkers with respect to treatment outcome. Methods: A group of 22 patients with locally advanced breast cancer were scanned using our dynamic TOBI system before and during neoadjuvant chemotherapy. In this analysis we focus...
Biomedical Optics Express, 2017
We characterize novel breast cancer imaging biomarkers for monitoring neoadjuvant chemotherapy (N... more We characterize novel breast cancer imaging biomarkers for monitoring neoadjuvant chemotherapy (NACT) and predicting outcome. Specifically, we recruited 30 patients for a pilot study in which NACT patients were imaged using dynamic tomographic optical breast imaging (DTOBI) to quantify the hemodynamic changes due to partial mammographic compression. DTOBI scans were obtained pre-treatment (referred to as day 0), as well as 7 and 30 days into therapy on female patients undergoing NACT. We present data for the 13 patients who participated in both day 0 and 7 measurements and had evaluable data, of which 7 also returned for day 30 measurements. We acquired optical images over 2 minutes following 4-8 lbs (18-36 N) of compression. The timecourses of tissue-volume averaged total hemoglobin (HbT), as well as hemoglobin oxygen saturation (SO 2) in the tumor vs. surrounding tissues were compared. Outcome prediction metrics based on the differential behavior in tumor vs. normal areas for responders (>50% reduction in maximum diameter) vs. non-responders were analyzed for statistical significance. At baseline, all patients exhibit an initial decrease followed by delayed recovery in HbT, and SO 2 in the tumor area, in contrast to almost immediate recovery in surrounding tissue. At day 7 and 30, this contrast is maintained in non-responders; however, in responders, the contrast in hemodynamic time-courses between tumor and normal tissue starts decreasing at day 7 and substantially disappears at day 30. At day 30 into NACT, responding tumors demonstrate "normalization" of compression induced hemodynamics vs. surrounding normal tissue whereas non-responding tumors did not. This data suggests that DTOBI imaging biomarkers, which are governed by the interplay between tissue biomechanics and oxygen metabolism, may be suitable for guiding NACT by offering early predictions of treatment outcome.
Photonics in Dermatology and Plastic Surgery, 2017
Monitoring phase transition in adipose tissue and formation of lipid crystals is important in Cry... more Monitoring phase transition in adipose tissue and formation of lipid crystals is important in Cryo-procedures such as cryosurgery or Selective Cryolipolysis (SC). In this work, we exploited a Near-Infrared Spectroscopy (NIRS) method to monitor the onset of fat freezing/melting. Concurrent measurements using frequency domain NIRS and MR Spectroscopy during cooling/heating were performed on an in vitro porcine skin sample with a thick subcutaneous fat layer in a human MR scanner. The NIRS probe was placed on the skin measuring the average optical scattering of the fatty layer. Two fiber optic temperature probes were inserted in the area of the MRS and NIRS measurements. To further investigate the microscopic features of the phase-transition, an identical cooling/heating procedure was replicated on the same fat tissue while being imaged by Optical Coherence Tomography. The temperature relationships of optical scattering, MRS peak characteristics and OCT reflection intensity were analyzed to find signatures related to the onset of phase transition. The optical scattering in the fatty tissues decreases during the heating and increases by cooling. However, there is an inflexion in the rate of change of the scattering while the phase transition happens in the fatty layer. The methylene fat peaks on the MR Spectrum are also shown to be broadened during the cooling. OCT intensity displays a sharp increase at the transition temperature. The results from multiple samples show two transition points around 5-10 ˚C (cooling) and 15-20 ˚C (heating) through all three methods, demonstrating that adipose tissue phase change can be monitored non-invasively.
Journal of biomedical optics, Apr 1, 2017
Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breas... more Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breast cancer diagnosis and neoadjuvant chemotherapy monitoring. In particular, the multimodal approach of combining DOT with x-ray digital breast tomosynthesis (DBT) is especially synergistic as DBT prior information can be used to enhance the DOT reconstruction. DOT, in turn, provides a functional information overlay onto the mammographic images, increasing sensitivity and specificity to cancer pathology. We describe a dynamic DOT apparatus designed for tight integration with commercial DBT scanners and providing a fast (up to 1 Hz) image acquisition rate to enable tracking hemodynamic changes induced by the mammographic breast compression. The system integrates 96 continuous-wave and 24 frequency-domain source locations as well as 32 continuous wave and 20 frequency-domain detection locations into low-profile plastic plates that can easily mate to the DBT compression paddle and x-ray detec...
Lasers in Surgery and Medicine, 2015
Background: Ablative fractional laser procedures have been shown to facilitate topical drug deliv... more Background: Ablative fractional laser procedures have been shown to facilitate topical drug delivery into the skin. Past studies have mainly used ex vivo models to demonstrate enhanced drug delivery and in vivo studies have investigated laser created channels over a time course of days and weeks rather than within the first few minutes and hours after exposures. We have noticed rapid in vivo fibrin plug formation within ablative fractional laser lesions impairing passage through the laser created channels. Material and Methods: In vivo laser exposures were performed in a porcine model. A fractional CO 2 laser (AcuPulse TM system, AcuScan 120 TM handpiece, Lumenis, Inc., Yokneam, Israel) was programmed in quasi-continuous wave (QCW) mode, at 40W, 50 mJ per pulse, 5% coverage, nominal 120 mm spot size, 8 Â 8 mm square pattern, 169 MTZs per scan. Six millimeters punch biopsies were procured at 0, 2, 5, 10, 15, 30, 60, 90 minutes after completion of each scan, then fixed in 10% formalin. 12 repeats were performed of each time point. Skin samples were processed for serial vertically cut paraffin sections (5 mm collected every 25 mm) then H&E and special immunohistochemistry staining for fibrin and platelet. Dimensions of Microscopic Treatment Zones (MTZs) and extent of fibrin plug were assessed and quantified histologically. Ex vivo laser exposures of the identical laser parameter were performed on porcine and human skin at different storage conditions. Results: Histology procured at various predetermined time intervals after in vivo fractional CO 2 laser exposures revealed a rapidly forming fibrin plug initiating at the bottom of the MTZ lesions. At longer time intervals, the fibrin plug was extending towards the superficial sections. Within the first 5 minutes, more than 25% length of the entire laser-ablated channel was filled with a fibrin plug. With increased time intervals, the cavity was progressively filled with a fibrin plug. At 90 minutes, more than 90% length of the entire laser-ablated channel was occluded. Ex vivo exposures failed to produce any significant fibrin plug formation. Conclusions: The current study has demonstrated rapid fibrin plug formation after ablative fractional laser procedures. It was shown that the passage through laser created pathways is critically time dependent for in vivo exposures. In contrast, ex vivo exposures do not exhibit such time dependent passage capacity. In particular, drug, substance, and cell delivery studies for ablative fractional laser treatments should take early fibrin plug formation into consideration and further investigate the impact on transdermal delivery.
Cancer Research, 2013
Background: Diffuse optical imaging using near-infrared light is emerging as a promising non-inva... more Background: Diffuse optical imaging using near-infrared light is emerging as a promising non-invasive method for breast neoadjuvant chemotherapy (NAC) monitoring and outcome prediction. While the majority of published studies rely on “static” assessments of tissue oxy- and deoxy- hemoglobin concentration, we have focused on extending diffuse optical tomography to capture hemodynamic changes driven by fractional mammographic compression. These hemodynamic changes are governed by the interplay of tissue biomechanics and oxygen metabolism, and thus form a novel class of optical dynamic biomarkers of breast pathology. In this study we seek to evaluate the predictive value of these biomarkers with respect to treatment outcome. Methods: We are conducting a pilot feasibility study in female patients with unilateral locally advanced breast cancer undergoing standard of care NAC. In this analysis we focused on pre-treatment and day 30 post-treatment dynamic TOBI scans. Both breasts are compr...
Biomedical Optics 2014, 2014
ABSTRACT We constructed a novel tomographic optical breast imager with simultaneous x-ray tomosyn... more ABSTRACT We constructed a novel tomographic optical breast imager with simultaneous x-ray tomosynthesis coregistration. It consists of a continuous wave and a frequency encoded frequency domain imaging unit connected to an x-ray translucent fiber optic probe.
Biomedical Optics 2014, 2014
ABSTRACT We use mesh based Monte Carlo simulations to generate realistic transmission breast diff... more ABSTRACT We use mesh based Monte Carlo simulations to generate realistic transmission breast diffuse optical tomography data. We use these controlled conditions to test the impact of data degradation on finite element diffusion based image reconstructions.
Biomedical Optics 2014, 2014
ABSTRACT We use a layered Monte Carlo model of diffuse correlation spectroscopy together with mul... more ABSTRACT We use a layered Monte Carlo model of diffuse correlation spectroscopy together with multi-distance measurements to more accurately recover cerebral blood flow changes. We also suggest a method to estimate skull/scalp thickness from the data.
Optical Tomography and Spectroscopy of Tissue X, 2013
ABSTRACT Near-infrared optical measurements have been shown to offer a promising non-invasive way... more ABSTRACT Near-infrared optical measurements have been shown to offer a promising non-invasive way for monitoring breast neoadjuvant chemotherapy (NAC) and predicting outcome. In this study, we extend optical measurements to capture additional hemodynamic and metabolic biomarkers revealed by dynamically imaging breast tissue during fractional mammographic compression. We are obtaining pre-treatment, day 7 and optional monthly scans in breast cancer patients undergoing NAC. The difference in hemodynamic response to compression between healthy and tumor-bearing breast decreases over the course of neoadjuvant therapy in responders compared to nearly no change in patients not responding to the chemotherapy.
Biomedical Optics Express, 2013
Near infrared dynamic diffuse optical tomography measurements of breast hemodynamics during fract... more Near infrared dynamic diffuse optical tomography measurements of breast hemodynamics during fractional mammographic compression offer a novel contrast mechanism for detecting breast cancer and monitoring chemotherapy. Tissue viscoelastic relaxation during the compression period leads to a slow reduction in the compression force and reveals biomechanical and metabolic differences between healthy and lesion tissue. We measured both the absolute values and the temporal evolution of hemoglobin concentration during 25-35 N of compression for 22 stage II and III breast cancer patients scheduled to undergo neoadjuvant chemotherapy. 17 patients were included in the group analysis (average tumor size 3.2 cm, range: 1.3-5.7 cm). We observed a statistically significant differential decrease in total and oxy-hemoglobin, as well as in hemoglobin oxygen saturation in tumor areas vs. healthy tissue, as early as 30 seconds into the compression period. The hemodynamic contrast is likely driven by the higher tumor stiffness and different viscoelastic relaxation rate, as well as the higher tumor oxygen metabolism rate.
Transportation Research Record: Journal of the Transportation Research Board, 2013
Reclaimed asphalt pavement (RAP) is a byproduct of roadway resurfacing. A limited amount of RAP c... more Reclaimed asphalt pavement (RAP) is a byproduct of roadway resurfacing. A limited amount of RAP can be recycled into new hot-mix asphalt; the rest is stockpiled. Some states allow the use of RAP–aggregate blends as base course material. Because of RAP's low strength and susceptibility to creep deformation, the Florida Department of Transportation (DOT) excludes RAP from being used as pavement base course for high-traffic areas. The research objective was to determine whether the strength characteristics of RAP could be improved through compaction and thereby make its base suitable in high-traffic areas. Modified Proctor, vibratory, and gyratory compaction data were compared. Four RAP sources were used. Specimens compacted by the three methods were tested with the limerock bearing ratio (LBR), unconfined compressive strength, and indirect split tensile strength. LBR is Florida's variation of the California bearing ratio. Specimens were compacted to either a density or a compa...
Transportation Research Record: Journal of the Transportation Research Board, 2013
Finding innovative ways to incorporate reclaimed asphalt pavement (RAP) into highway base course ... more Finding innovative ways to incorporate reclaimed asphalt pavement (RAP) into highway base course applications will provide both environmental and economic benefits by allowing in situ recycling of material for projects such as widening or shoulder addition. RAP is a well-drained granular material; however, 100% RAP has low bearing strength and creeps under load. The objective of this research is to develop methods to improve RAP's strength while reducing creep to an acceptable level through blending with high-quality crushed-limestone aggregate, by chemical stabilization with asphalt emulsion or portland cement, or both. RAP–aggregate blends with and without chemical stabilization were compacted by the modified Proctor method, cured, and tested for strength and creep. Strength was tested by the limerock bearing ratio (LBR), a variant of the California bearing ratio test. Specimens were tested dry and soaked to evaluate retained strength. One-dimensional creep testing was perform...
Over 250 million scrap tires are generated annually in the U.S. Historically, a significant porti... more Over 250 million scrap tires are generated annually in the U.S. Historically, a significant portion of these tires have been processed into finely ground tire rubber (GTR), or crumb rubber, for use as an additive in hot mix asphalt (HMA) pavements to improve pavement performance. Recently, improved synthetic polymer additives have been developed that more economically provide the same performance improvements as GTR. This development has decreased the demand for GTR in HMA, potentially freeing supplies of GTR for other applications. Over the past two decades, the Florida Department of Transportation (FDOT) has conducted a significant amount of research on ways to re-use waste materials such as energy generation ash, tires, glass, reclaimed asphalt pavement, and reclaimed concrete in roadway construction. FDOT initiated this study to investigate whether blending GTR with subgrade soils would be a beneficial practice. The objective of this research was to determine the effect of GTR o...
Journal of Cerebral Blood Flow & Metabolism, 2017
Optical coherence tomography (OCT) allows label-free imaging of red blood cell (RBC) flux within ... more Optical coherence tomography (OCT) allows label-free imaging of red blood cell (RBC) flux within capillaries with high spatio-temporal resolution. In this study, we utilized time-series OCT-angiography to demonstrate interruptions in capillary RBC flux in mouse brain in vivo. We noticed ∼7.5% of ∼200 capillaries had at least one stall in awake mice with chronic windows during a 9-min recording. At any instant, ∼0.45% of capillaries were stalled. Average stall duration was ∼15 s but could last over 1 min. Stalls were more frequent and longer lasting in acute window preparations. Further, isoflurane anesthesia in chronic preparations caused an increase in the number of stalls. In repeated imaging, the same segments had a tendency to stall again over a period of one month. In awake animals, functional stimulation decreased the observance of stalling events. Stalling segments were located distally, away from the first couple of arteriolar-side capillary branches and their average RBC an...
Cancer Research, 2016
Background: Dynamic Diffuse optical imaging using near-infrared light was shown to be promising m... more Background: Dynamic Diffuse optical imaging using near-infrared light was shown to be promising method for neoadjuvant therapy monitoring as an alternative functional imaging that is low-cost, non-invasive, portable, safe and simple to operate. While optical breast imaging methods rely on "static" assessments of tissue oxy- and deoxy- hemoglobin concentration without contrast agents, they are insufficient for clinical applications. Dynamic tomographic optical imaging induces tumor-sensitive hemodynamic variations, as a contrast mechanism, driven by fractional mammographic compression. These tumor contrast measurements are governed by interlay of tissue biomechanics and oxygen metabolism. In this study we seek to evaluate the predictive value of these biomarkers with respect to treatment outcome. Methods: A group of 22 patients with locally advanced breast cancer were scanned using our dynamic TOBI system before and during neoadjuvant chemotherapy. In this analysis we focus...
Biomedical Optics Express, 2017
We characterize novel breast cancer imaging biomarkers for monitoring neoadjuvant chemotherapy (N... more We characterize novel breast cancer imaging biomarkers for monitoring neoadjuvant chemotherapy (NACT) and predicting outcome. Specifically, we recruited 30 patients for a pilot study in which NACT patients were imaged using dynamic tomographic optical breast imaging (DTOBI) to quantify the hemodynamic changes due to partial mammographic compression. DTOBI scans were obtained pre-treatment (referred to as day 0), as well as 7 and 30 days into therapy on female patients undergoing NACT. We present data for the 13 patients who participated in both day 0 and 7 measurements and had evaluable data, of which 7 also returned for day 30 measurements. We acquired optical images over 2 minutes following 4-8 lbs (18-36 N) of compression. The timecourses of tissue-volume averaged total hemoglobin (HbT), as well as hemoglobin oxygen saturation (SO 2) in the tumor vs. surrounding tissues were compared. Outcome prediction metrics based on the differential behavior in tumor vs. normal areas for responders (>50% reduction in maximum diameter) vs. non-responders were analyzed for statistical significance. At baseline, all patients exhibit an initial decrease followed by delayed recovery in HbT, and SO 2 in the tumor area, in contrast to almost immediate recovery in surrounding tissue. At day 7 and 30, this contrast is maintained in non-responders; however, in responders, the contrast in hemodynamic time-courses between tumor and normal tissue starts decreasing at day 7 and substantially disappears at day 30. At day 30 into NACT, responding tumors demonstrate "normalization" of compression induced hemodynamics vs. surrounding normal tissue whereas non-responding tumors did not. This data suggests that DTOBI imaging biomarkers, which are governed by the interplay between tissue biomechanics and oxygen metabolism, may be suitable for guiding NACT by offering early predictions of treatment outcome.
Photonics in Dermatology and Plastic Surgery, 2017
Monitoring phase transition in adipose tissue and formation of lipid crystals is important in Cry... more Monitoring phase transition in adipose tissue and formation of lipid crystals is important in Cryo-procedures such as cryosurgery or Selective Cryolipolysis (SC). In this work, we exploited a Near-Infrared Spectroscopy (NIRS) method to monitor the onset of fat freezing/melting. Concurrent measurements using frequency domain NIRS and MR Spectroscopy during cooling/heating were performed on an in vitro porcine skin sample with a thick subcutaneous fat layer in a human MR scanner. The NIRS probe was placed on the skin measuring the average optical scattering of the fatty layer. Two fiber optic temperature probes were inserted in the area of the MRS and NIRS measurements. To further investigate the microscopic features of the phase-transition, an identical cooling/heating procedure was replicated on the same fat tissue while being imaged by Optical Coherence Tomography. The temperature relationships of optical scattering, MRS peak characteristics and OCT reflection intensity were analyzed to find signatures related to the onset of phase transition. The optical scattering in the fatty tissues decreases during the heating and increases by cooling. However, there is an inflexion in the rate of change of the scattering while the phase transition happens in the fatty layer. The methylene fat peaks on the MR Spectrum are also shown to be broadened during the cooling. OCT intensity displays a sharp increase at the transition temperature. The results from multiple samples show two transition points around 5-10 ˚C (cooling) and 15-20 ˚C (heating) through all three methods, demonstrating that adipose tissue phase change can be monitored non-invasively.
Journal of biomedical optics, Apr 1, 2017
Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breas... more Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breast cancer diagnosis and neoadjuvant chemotherapy monitoring. In particular, the multimodal approach of combining DOT with x-ray digital breast tomosynthesis (DBT) is especially synergistic as DBT prior information can be used to enhance the DOT reconstruction. DOT, in turn, provides a functional information overlay onto the mammographic images, increasing sensitivity and specificity to cancer pathology. We describe a dynamic DOT apparatus designed for tight integration with commercial DBT scanners and providing a fast (up to 1 Hz) image acquisition rate to enable tracking hemodynamic changes induced by the mammographic breast compression. The system integrates 96 continuous-wave and 24 frequency-domain source locations as well as 32 continuous wave and 20 frequency-domain detection locations into low-profile plastic plates that can easily mate to the DBT compression paddle and x-ray detec...
Lasers in Surgery and Medicine, 2015
Background: Ablative fractional laser procedures have been shown to facilitate topical drug deliv... more Background: Ablative fractional laser procedures have been shown to facilitate topical drug delivery into the skin. Past studies have mainly used ex vivo models to demonstrate enhanced drug delivery and in vivo studies have investigated laser created channels over a time course of days and weeks rather than within the first few minutes and hours after exposures. We have noticed rapid in vivo fibrin plug formation within ablative fractional laser lesions impairing passage through the laser created channels. Material and Methods: In vivo laser exposures were performed in a porcine model. A fractional CO 2 laser (AcuPulse TM system, AcuScan 120 TM handpiece, Lumenis, Inc., Yokneam, Israel) was programmed in quasi-continuous wave (QCW) mode, at 40W, 50 mJ per pulse, 5% coverage, nominal 120 mm spot size, 8 Â 8 mm square pattern, 169 MTZs per scan. Six millimeters punch biopsies were procured at 0, 2, 5, 10, 15, 30, 60, 90 minutes after completion of each scan, then fixed in 10% formalin. 12 repeats were performed of each time point. Skin samples were processed for serial vertically cut paraffin sections (5 mm collected every 25 mm) then H&E and special immunohistochemistry staining for fibrin and platelet. Dimensions of Microscopic Treatment Zones (MTZs) and extent of fibrin plug were assessed and quantified histologically. Ex vivo laser exposures of the identical laser parameter were performed on porcine and human skin at different storage conditions. Results: Histology procured at various predetermined time intervals after in vivo fractional CO 2 laser exposures revealed a rapidly forming fibrin plug initiating at the bottom of the MTZ lesions. At longer time intervals, the fibrin plug was extending towards the superficial sections. Within the first 5 minutes, more than 25% length of the entire laser-ablated channel was filled with a fibrin plug. With increased time intervals, the cavity was progressively filled with a fibrin plug. At 90 minutes, more than 90% length of the entire laser-ablated channel was occluded. Ex vivo exposures failed to produce any significant fibrin plug formation. Conclusions: The current study has demonstrated rapid fibrin plug formation after ablative fractional laser procedures. It was shown that the passage through laser created pathways is critically time dependent for in vivo exposures. In contrast, ex vivo exposures do not exhibit such time dependent passage capacity. In particular, drug, substance, and cell delivery studies for ablative fractional laser treatments should take early fibrin plug formation into consideration and further investigate the impact on transdermal delivery.
Cancer Research, 2013
Background: Diffuse optical imaging using near-infrared light is emerging as a promising non-inva... more Background: Diffuse optical imaging using near-infrared light is emerging as a promising non-invasive method for breast neoadjuvant chemotherapy (NAC) monitoring and outcome prediction. While the majority of published studies rely on “static” assessments of tissue oxy- and deoxy- hemoglobin concentration, we have focused on extending diffuse optical tomography to capture hemodynamic changes driven by fractional mammographic compression. These hemodynamic changes are governed by the interplay of tissue biomechanics and oxygen metabolism, and thus form a novel class of optical dynamic biomarkers of breast pathology. In this study we seek to evaluate the predictive value of these biomarkers with respect to treatment outcome. Methods: We are conducting a pilot feasibility study in female patients with unilateral locally advanced breast cancer undergoing standard of care NAC. In this analysis we focused on pre-treatment and day 30 post-treatment dynamic TOBI scans. Both breasts are compr...
Biomedical Optics 2014, 2014
ABSTRACT We constructed a novel tomographic optical breast imager with simultaneous x-ray tomosyn... more ABSTRACT We constructed a novel tomographic optical breast imager with simultaneous x-ray tomosynthesis coregistration. It consists of a continuous wave and a frequency encoded frequency domain imaging unit connected to an x-ray translucent fiber optic probe.
Biomedical Optics 2014, 2014
ABSTRACT We use mesh based Monte Carlo simulations to generate realistic transmission breast diff... more ABSTRACT We use mesh based Monte Carlo simulations to generate realistic transmission breast diffuse optical tomography data. We use these controlled conditions to test the impact of data degradation on finite element diffusion based image reconstructions.
Biomedical Optics 2014, 2014
ABSTRACT We use a layered Monte Carlo model of diffuse correlation spectroscopy together with mul... more ABSTRACT We use a layered Monte Carlo model of diffuse correlation spectroscopy together with multi-distance measurements to more accurately recover cerebral blood flow changes. We also suggest a method to estimate skull/scalp thickness from the data.
Optical Tomography and Spectroscopy of Tissue X, 2013
ABSTRACT Near-infrared optical measurements have been shown to offer a promising non-invasive way... more ABSTRACT Near-infrared optical measurements have been shown to offer a promising non-invasive way for monitoring breast neoadjuvant chemotherapy (NAC) and predicting outcome. In this study, we extend optical measurements to capture additional hemodynamic and metabolic biomarkers revealed by dynamically imaging breast tissue during fractional mammographic compression. We are obtaining pre-treatment, day 7 and optional monthly scans in breast cancer patients undergoing NAC. The difference in hemodynamic response to compression between healthy and tumor-bearing breast decreases over the course of neoadjuvant therapy in responders compared to nearly no change in patients not responding to the chemotherapy.
Biomedical Optics Express, 2013
Near infrared dynamic diffuse optical tomography measurements of breast hemodynamics during fract... more Near infrared dynamic diffuse optical tomography measurements of breast hemodynamics during fractional mammographic compression offer a novel contrast mechanism for detecting breast cancer and monitoring chemotherapy. Tissue viscoelastic relaxation during the compression period leads to a slow reduction in the compression force and reveals biomechanical and metabolic differences between healthy and lesion tissue. We measured both the absolute values and the temporal evolution of hemoglobin concentration during 25-35 N of compression for 22 stage II and III breast cancer patients scheduled to undergo neoadjuvant chemotherapy. 17 patients were included in the group analysis (average tumor size 3.2 cm, range: 1.3-5.7 cm). We observed a statistically significant differential decrease in total and oxy-hemoglobin, as well as in hemoglobin oxygen saturation in tumor areas vs. healthy tissue, as early as 30 seconds into the compression period. The hemodynamic contrast is likely driven by the higher tumor stiffness and different viscoelastic relaxation rate, as well as the higher tumor oxygen metabolism rate.
Transportation Research Record: Journal of the Transportation Research Board, 2013
Reclaimed asphalt pavement (RAP) is a byproduct of roadway resurfacing. A limited amount of RAP c... more Reclaimed asphalt pavement (RAP) is a byproduct of roadway resurfacing. A limited amount of RAP can be recycled into new hot-mix asphalt; the rest is stockpiled. Some states allow the use of RAP–aggregate blends as base course material. Because of RAP's low strength and susceptibility to creep deformation, the Florida Department of Transportation (DOT) excludes RAP from being used as pavement base course for high-traffic areas. The research objective was to determine whether the strength characteristics of RAP could be improved through compaction and thereby make its base suitable in high-traffic areas. Modified Proctor, vibratory, and gyratory compaction data were compared. Four RAP sources were used. Specimens compacted by the three methods were tested with the limerock bearing ratio (LBR), unconfined compressive strength, and indirect split tensile strength. LBR is Florida's variation of the California bearing ratio. Specimens were compacted to either a density or a compa...
Transportation Research Record: Journal of the Transportation Research Board, 2013
Finding innovative ways to incorporate reclaimed asphalt pavement (RAP) into highway base course ... more Finding innovative ways to incorporate reclaimed asphalt pavement (RAP) into highway base course applications will provide both environmental and economic benefits by allowing in situ recycling of material for projects such as widening or shoulder addition. RAP is a well-drained granular material; however, 100% RAP has low bearing strength and creeps under load. The objective of this research is to develop methods to improve RAP's strength while reducing creep to an acceptable level through blending with high-quality crushed-limestone aggregate, by chemical stabilization with asphalt emulsion or portland cement, or both. RAP–aggregate blends with and without chemical stabilization were compacted by the modified Proctor method, cured, and tested for strength and creep. Strength was tested by the limerock bearing ratio (LBR), a variant of the California bearing ratio test. Specimens were tested dry and soaked to evaluate retained strength. One-dimensional creep testing was perform...