Dr. Lorenzo Leonardi Profile

Dr. Lorenzo Leonardi

Research Officer at National Research Council Canada

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Publications (9)

SPIE Journal Paper | 1 September 2006 Open Access

Classification of burn injuries using near-infrared spectroscopy

Michael Sowa, Lorenzo Leonardi, Jeri Payette, K. M. Cross, Manuel Gomez, Joel Fish

JBO, Vol. 11, Issue 05, 054002, (September 2006) https://doi.org/10.1117/12.10.1117/1.2362722

KEYWORDS: Injuries, Near infrared spectroscopy, Animal model studies, Data modeling, Reflectivity, Tissue optics, Tissues, Surgery, Hemodynamics, Blood

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Early surgical management of those burn injuries that will not heal spontaneously is critical. The decision to excise and graft is based on a visual assessment that is often inaccurate but yet continues to be the primary means of grading the injury. Superficial and intermediate partial-thickness injuries generally heal with appropriate wound care while deep partial- and full-thickness injuries generally require surgery. This study explores the possibility of using near-infrared spectroscopy to provide an objective and accurate means of distinguishing shallow injuries from deeper burns that require surgery. Twenty burn injuries are studied in five animals, with burns covering <1% of the total body surface area. Carefully controlled superficial, intermediate, and deep partial-thickness injuries as well as full-thickness injuries could be studied with this model. Near-infrared reflectance spectroscopy was used to evaluate these injuries 1 to 3 hours after the insult. A probabilistic model employing partial least-squares logistic regression was used to determine the degree of injury, shallow (superficial or intermediate partial) from deep (deep partial and full thickness), based on the reflectance spectrum of the wound. A leave-animal-out cross-validation strategy was used to test the predictive ability of a 2–latent variable, partial least-squares logistic regression model to distinguish deep burn injuries from shallow injuries. The model displayed reasonable ranking quality as summarized by the area under the receiver operator characteristics curve, AUC=0.879. Fixing the threshold for the class boundaries at 0.5 probability, the model sensitivity (true positive fraction) to separate deep from shallow burns was 0.90, while model specificity (true negative fraction) was 0.83. Using an acute porcine model of thermal burn injuries, the potential of near-infrared spectroscopy to distinguish between shallow healing burns and deeper burn injuries was demonstrated.

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Proceedings Article | 22 February 2006 Paper

Atherosclerosis diagnostic imaging by optical spectroscopy and optical coherence tomography

M. D. Hewko, L. P. Choo-Smith, A. C. T. Ko, M. S. D. Smith, E. M. Kohlenberg, E. R. Bock, L. Leonardi, M. G. Sowa

Proceedings Volume 6078, 60782E (2006) https://doi.org/10.1117/12.641438

KEYWORDS: Raman spectroscopy, Collagen, Arteries, Optical coherence tomography, Tissues, Near infrared, Diagnostics, Luminescence, Imaging spectroscopy, Optical imaging

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Atherosclerosis is traditionally viewed as a disease of uncontrolled plaque growth leading to arterial occlusion. More recently, however, occlusion of the arterial lumen is being viewed as an acute event triggered by plaque rupture and thrombosis. An atheromatous plaque becomes vulnerable to sudden activation and/or rupture when a constellation of processes are activated by various trigger mechanisms. There is growing evidence that the vulnerability (i.e. susceptibility to rupture) and thrombogenic nature of the plaque need to be taken into account in the planning and treatment of the disease. X-ray fluoroscopy and intravascular ultrasound, the current clinical diagnostic tools are not capable of the providing a complete histological picture of the plaque region. Intravascular diagnostic imaging of coronary atherosclerotic plaques by optical means to assess plaque, patient risk and assist in planning treatment strategies represents the future in angioplasty treatment by interventional cardiologists. The techniques which will enable a clinically acceptable and reliable intravascular diagnostic platform are currently being investigated and compared to the clinical standard of histology. Currently, we are investigating the use of a number of optical and imaging techniques for biochemical analysis of arterial tissue including Raman, near infrared and fluorescence spectroscopies. Biochemical imaging will provide compositional information on collagen, elastin, lipid and thrombogenic by-products as well as gauging inflammation and tissue remodeling activity levels. To complement the functional biochemical imaging, optical coherence tomography will be provide structural morphological imaging. The synergistic combination of functional and structural imagery will provide the interventional cardiologist with a complete clinical picture of the atherosclerotic plaque region. The clinician can use this diagnostic information to plan a personalized treatment procedure based on the entire clinical presentation.

Proceedings Article | 13 October 2005 Paper

Near-infrared hyperspectral imaging: the road traveled to a clinical burn application

Michelle Levasseur, Lorenzo Leonardi, Jeri Payette, Elicia Kohlenberg, Michael Sowa, Joel Fish, Karen Cross, Manuel Gomez

Proceedings Volume 5969, 59691O (2005) https://doi.org/10.1117/12.628233

KEYWORDS: Near infrared, Injuries, Hyperspectral imaging, Imaging systems, Tissues, Control systems, Cameras, Blood, Oxygen, Hemodynamics

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SPIE Journal Paper | 1 May 2005 Open Access

Ex vivo detection and characterization of early dental caries by optical coherence tomography and Raman spectroscopy

Alex Ko, Lin-P'ing Choo-Smith, Mark Hewko, Lorenzo Leonardi, Michael Sowa, Cecilia Dong, Peter Williams, Blaine Cleghorn

JBO, Vol. 10, Issue 03, 031118, (May 2005) https://doi.org/10.1117/12.10.1117/1.1915488

KEYWORDS: Raman spectroscopy, Teeth, Dental caries, Optical coherence tomography, Fiber optics, Crystals, Luminescence, Imaging spectroscopy, Polarization, Spectroscopy

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Proceedings Article | 23 March 2005 Paper

OCT of early dental caries: a comparative study with histology and Raman spectroscopy

Mark Hewko, Lin-P'ing Choo-Smith, Alex Ko, Lorenzo Leonardi, Cecilia Dong, Blaine Cleghorn, Michael Sowa

Proceedings Volume 5687, (2005) https://doi.org/10.1117/12.590955

KEYWORDS: Optical coherence tomography, Teeth, Dental caries, Raman spectroscopy, Minerals, Imaging systems, Visualization, Imaging spectroscopy, Visible radiation, Bacteria

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Proceedings Article | 9 December 2004 Paper

Optical spectroscopic assessment of free flap circulatory impairment

Michael Sowa, Jeri Payette, Elicia Kohlenberg, Lorenzo Leonardi, Arone Pabbies, Paul Kerr

Proceedings Volume 5578, (2004) https://doi.org/10.1117/12.567434

KEYWORDS: Blood, Optical spectroscopy, Reflectivity, Tissues, Spectroscopy, Skin, Surgery, Tissue optics, Visible radiation, Animal model studies

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Proceedings Article | 2 July 2003 Paper

Evaluating the health of compromised tissues using a near-infrared spectroscopic imaging system in clinical settings: lessons learned

Lorenzo Leonardi, Michael Sowa, Mark Hewko, Bernhard Schattka, Jeri Payette, Michelle Hastings, Trevor Posthumus, Henry Mantsch

Proceedings Volume 4959, (2003) https://doi.org/10.1117/12.479483

KEYWORDS: Tissues, Injuries, Near infrared, Near infrared spectroscopy, Spectroscopy, Imaging spectroscopy, Oxygen, Principal component analysis, Hemodynamics, Blood

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Proceedings Article | 2 July 2001 Paper

Near-infrared spectroscopic approach to assess tissue viability following a thermal injury

Lorenzo Leonardi, Michael Sowa, Jeri Payette, Mark Hewko, Bernhard Schattka, Anna Matas, Henry Mantsch

Proceedings Volume 4259, (2001) https://doi.org/10.1117/12.432478

KEYWORDS: Injuries, Spectroscopy, Imaging spectroscopy, Near infrared, Tissues, Near infrared spectroscopy, Principal component analysis, Factor analysis, Tissue optics, Skin

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Proceedings Article | 8 May 2000 Paper

Applications of visible near-infrared spectroscopy and imaging in burn injury assessment

Lorenzo Leonardi, Michael Sowa, Jeri Payette, Mark Hewko, Bernhard Schattka, Anna Matas, Henry Mantsch

Proceedings Volume 3918, (2000) https://doi.org/10.1117/12.384955

KEYWORDS: Injuries, Tissues, Spectroscopy, Near infrared spectroscopy, Factor analysis, Skin, Tissue optics, Data modeling, Infrared spectroscopy, Oxygen

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Showing 5 of 9 publications

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