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Papers by Kyle Verdecchia

Biomedical optics express, 2012

The authors provide corrections to tabular data and a figure, which do not alter the conclusions ... more The authors provide corrections to tabular data and a figure, which do not alter the conclusions of the original paper [Biomed. Opt. Express 2, 2068 (2011)].

ABSTRACT The purpose of this study was to develop a dynamic contrast-enhanced (DCE) near-infrared... more ABSTRACT The purpose of this study was to develop a dynamic contrast-enhanced (DCE) near-infrared spectroscopy (NIRS) technique to characterize tumor physiology. Dynamic data were acquired using two contrast agents of different molecular weights, indocyanine green (ICG) and IRDye 800CW carboxylate (IRDcxb). The DCE curves were analyzed using a kinetic model capable of extracting estimates of tumor blood flow (F), capillary transit time (tc) and the amount of dye that leaked into the extravascular space (EVS) – characterized by the extraction fraction (E). Data were acquired from five nude rats with tumor xenografts (>10mm) implanted in the neck. Four DCE-NIR datasets (two from each contrast agent) were acquired for each rat. The dye concentration curve in arterial blood, which is required to quantify the model parameters, was measured non-invasively by dye densitometry. A modification to the kinetic model to characterize tc as a distribution of possible values, rather than finite, improved the fit of acquired tumor concentration curves, resulting in more reliable estimates. This modified kinetic model identified a difference between the extracted fraction of IRDcxb, 15 ± 6 %, and ICG, 1.6 ± 0.6 %, in the tumor, which can be explained by the difference in molecular weight: 67 kDa for ICG since it binds to albumin and 1.17 kDa for IRD. This study demonstrates the ability of DCENIRS to quantify tumor physiology. The next step is to adapt this approach with a dual-receptor approach.

The authors provide corrections to tabular data and a figure, which do not alter the conclusions ... more The authors provide corrections to tabular data and a figure, which do not alter the conclusions of the original paper [Biomed. Opt. Express 2, 2068 (2011)].

Biomedical Optics 2014, 2014

ABSTRACT A DCS method that quantifies changes in cerebral blood flow by simultaneously acquiring ... more ABSTRACT A DCS method that quantifies changes in cerebral blood flow by simultaneously acquiring data at multiple source-detector distances (7, 20, and 30 mm) directly on the scalp, skull and brain of adolescent pigs is presented.

Physics in Medicine and Biology, 2013

Dynamic contrast-enhanced (DCE) methods are widely used with magnetic resonance imaging and compu... more Dynamic contrast-enhanced (DCE) methods are widely used with magnetic resonance imaging and computed tomography to assess the vascular characteristics of tumours since these properties can affect the response to radiotherapy and chemotherapy. In contrast, there have been far fewer studies using optical-based applications despite the advantages of low cost and safety. This study investigated an appropriate kinetic model for optical applications to characterize tumour haemodynamics (blood flow, F, blood volume, V b , and vascular heterogeneity) and vascular leakage (permeability surface-area product, PS). DCE data were acquired with two dyes, indocyanine green (ICG) and 800 CW carboxylate (IRD cbx ), from a human colon tumour xenograph model in rats. Due to the smaller molecular weight of IRD cbx (1166 Da) compared to albumin-bound ICG (67 kDa), PS of IRD cbx was significantly larger; however, no significant differences in F and V b were found between the dyes as expected. Error analysis demonstrated that all parameters could be estimated with an uncertainty less than 5% due to the high temporal resolution and signal-to-noise ratio of the optical measurements. The next step is to adapt this approach to optical imaging to generate haemodynamics and permeability maps, which should enhance the clinical interest in optics for treatment monitoring.

Journal of Biomedical Optics, 2013

Preterm infants are highly susceptible to ischemic brain injury; consequently, continuous bedside... more Preterm infants are highly susceptible to ischemic brain injury; consequently, continuous bedside monitoring to detect ischemia before irreversible damage occurs would improve patient outcome. In addition to monitoring cerebral blood flow (CBF), assessing the cerebral metabolic rate of oxygen (CMRO 2 ) would be beneficial considering that metabolic thresholds can be used to evaluate tissue viability. The purpose of this study was to demonstrate that changes in absolute CMRO 2 could be measured by combining diffuse correlation spectroscopy (DCS) with time-resolved near-infrared spectroscopy (TR-NIRS). Absolute CBF was determined using bolus-tracking TR-NIRS to calibrate the DCS measurements. Cerebral venous blood oxygenation (SvO 2 ) was determined by multiwavelength TR-NIRS measurements, the accuracy of which was assessed by directly measuring the oxygenation of sagittal sinus blood. In eight newborn piglets, CMRO 2 was manipulated by varying the anesthetics and by injecting sodium cyanide. No significant differences were found between the two sets of SvO 2 measurements obtained by TR-NIRS or sagittal sinus blood samples and the corresponding CMRO 2 measurements. Bland-Altman analysis showed a mean CMRO 2 difference of 0.0268 AE 0.8340 mL O 2 ∕100 g∕ min between the two techniques over a range from 0.3 to 4 mL O 2 ∕100 g∕ min.

ABSTRACT A time-resolved near-infrared and diffuse correlation spectroscopy hybrid method to meas... more ABSTRACT A time-resolved near-infrared and diffuse correlation spectroscopy hybrid method to measure absolute cerebral blood flow and oxygen metabolism measurements dynamically. Arterial and venous blood samples are drawn for validation in newborn piglets.

Biomedical optics express, 2012

The authors provide corrections to tabular data and a figure, which do not alter the conclusions ... more The authors provide corrections to tabular data and a figure, which do not alter the conclusions of the original paper [Biomed. Opt. Express 2, 2068 (2011)].

ABSTRACT The purpose of this study was to develop a dynamic contrast-enhanced (DCE) near-infrared... more ABSTRACT The purpose of this study was to develop a dynamic contrast-enhanced (DCE) near-infrared spectroscopy (NIRS) technique to characterize tumor physiology. Dynamic data were acquired using two contrast agents of different molecular weights, indocyanine green (ICG) and IRDye 800CW carboxylate (IRDcxb). The DCE curves were analyzed using a kinetic model capable of extracting estimates of tumor blood flow (F), capillary transit time (tc) and the amount of dye that leaked into the extravascular space (EVS) – characterized by the extraction fraction (E). Data were acquired from five nude rats with tumor xenografts (>10mm) implanted in the neck. Four DCE-NIR datasets (two from each contrast agent) were acquired for each rat. The dye concentration curve in arterial blood, which is required to quantify the model parameters, was measured non-invasively by dye densitometry. A modification to the kinetic model to characterize tc as a distribution of possible values, rather than finite, improved the fit of acquired tumor concentration curves, resulting in more reliable estimates. This modified kinetic model identified a difference between the extracted fraction of IRDcxb, 15 ± 6 %, and ICG, 1.6 ± 0.6 %, in the tumor, which can be explained by the difference in molecular weight: 67 kDa for ICG since it binds to albumin and 1.17 kDa for IRD. This study demonstrates the ability of DCENIRS to quantify tumor physiology. The next step is to adapt this approach with a dual-receptor approach.

The authors provide corrections to tabular data and a figure, which do not alter the conclusions ... more The authors provide corrections to tabular data and a figure, which do not alter the conclusions of the original paper [Biomed. Opt. Express 2, 2068 (2011)].

Biomedical Optics 2014, 2014

ABSTRACT A DCS method that quantifies changes in cerebral blood flow by simultaneously acquiring ... more ABSTRACT A DCS method that quantifies changes in cerebral blood flow by simultaneously acquiring data at multiple source-detector distances (7, 20, and 30 mm) directly on the scalp, skull and brain of adolescent pigs is presented.

Physics in Medicine and Biology, 2013

Dynamic contrast-enhanced (DCE) methods are widely used with magnetic resonance imaging and compu... more Dynamic contrast-enhanced (DCE) methods are widely used with magnetic resonance imaging and computed tomography to assess the vascular characteristics of tumours since these properties can affect the response to radiotherapy and chemotherapy. In contrast, there have been far fewer studies using optical-based applications despite the advantages of low cost and safety. This study investigated an appropriate kinetic model for optical applications to characterize tumour haemodynamics (blood flow, F, blood volume, V b , and vascular heterogeneity) and vascular leakage (permeability surface-area product, PS). DCE data were acquired with two dyes, indocyanine green (ICG) and 800 CW carboxylate (IRD cbx ), from a human colon tumour xenograph model in rats. Due to the smaller molecular weight of IRD cbx (1166 Da) compared to albumin-bound ICG (67 kDa), PS of IRD cbx was significantly larger; however, no significant differences in F and V b were found between the dyes as expected. Error analysis demonstrated that all parameters could be estimated with an uncertainty less than 5% due to the high temporal resolution and signal-to-noise ratio of the optical measurements. The next step is to adapt this approach to optical imaging to generate haemodynamics and permeability maps, which should enhance the clinical interest in optics for treatment monitoring.

Journal of Biomedical Optics, 2013

Preterm infants are highly susceptible to ischemic brain injury; consequently, continuous bedside... more Preterm infants are highly susceptible to ischemic brain injury; consequently, continuous bedside monitoring to detect ischemia before irreversible damage occurs would improve patient outcome. In addition to monitoring cerebral blood flow (CBF), assessing the cerebral metabolic rate of oxygen (CMRO 2 ) would be beneficial considering that metabolic thresholds can be used to evaluate tissue viability. The purpose of this study was to demonstrate that changes in absolute CMRO 2 could be measured by combining diffuse correlation spectroscopy (DCS) with time-resolved near-infrared spectroscopy (TR-NIRS). Absolute CBF was determined using bolus-tracking TR-NIRS to calibrate the DCS measurements. Cerebral venous blood oxygenation (SvO 2 ) was determined by multiwavelength TR-NIRS measurements, the accuracy of which was assessed by directly measuring the oxygenation of sagittal sinus blood. In eight newborn piglets, CMRO 2 was manipulated by varying the anesthetics and by injecting sodium cyanide. No significant differences were found between the two sets of SvO 2 measurements obtained by TR-NIRS or sagittal sinus blood samples and the corresponding CMRO 2 measurements. Bland-Altman analysis showed a mean CMRO 2 difference of 0.0268 AE 0.8340 mL O 2 ∕100 g∕ min between the two techniques over a range from 0.3 to 4 mL O 2 ∕100 g∕ min.

ABSTRACT A time-resolved near-infrared and diffuse correlation spectroscopy hybrid method to meas... more ABSTRACT A time-resolved near-infrared and diffuse correlation spectroscopy hybrid method to measure absolute cerebral blood flow and oxygen metabolism measurements dynamically. Arterial and venous blood samples are drawn for validation in newborn piglets.