LUCAS RAMOS DE PRETTO

LUCAS RAMOS DE PRETTO

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Osteoporosis evaluation through full developed speckle imaging
2020 - AMARAL, MARCELLO M.; DEL-VALLE, MATHEUS; RAELE, MARCUS P.; DE PRETTO, LUCAS R.; ANA, PATRICIA A.
Osteoporosis is a disease characterized by bone mineral density reduction, weakening the bone structure. Its diagnosis is performed using ionizing radiation, increasing health risk. Optical techniques are safer, due to non-ionizing radiation use, but limited to the analyses of bone tissue. This limitation may be circumvented in the oral cavity. In this work we explored the use of laser speckle imaging (LSI) to differentiate the sound and osteoporotic maxilla andmandible bones in an in vitro model. Osteoporosis lesions were simulated with acid attack. The samples were evaluated by optical profilometry and LSI, using a custom software. Two image parameters were evaluated, speckle contrast ration and patches ratio. With the speckle contrast ratio, it was possible to differentiate sound from osteoporotic tissue. From speckle patches ratio it was observed a negative correlation with the roughness parameter. LSI is a promissory technique for assessment of osteoporosis lesions on alveolar bone.
Controlling for artifacts in widefield optical coherence tomography angiography measurements of non-perfusion area
2019 - PRETTO, LUCAS R. de; MOULT, ERIC M.; ALIBHAI, A.Y.; CARRASCO-ZEVALLOS, OSCAR M.; CHEN, SIYU; LEE, BYUNGKUN; WITKIN, ANDRE J.; BAUMAL, CAROLINE R.; REICHEL, ELIAS; FREITAS, ANDERSON Z. de; DUKER, JAY S.; WAHEED, NADIA K.; FUJIMOTO, JAMES G.
The recent clinical adoption of optical coherence tomography (OCT) angiography (OCTA) has enabled non-invasive, volumetric visualization of ocular vasculature at micron-scale resolutions. Initially limited to 3 mm × 3 mm and 6 mm × 6 mm fields-of-view (FOV), commercial OCTA systems now offer 12 mm × 12 mm, or larger, imaging fields. While larger FOVs promise a more complete visualization of retinal disease, they also introduce new challenges to the accurate and reliable interpretation of OCTA data. In particular, because of vignetting, wide-field imaging increases occurrence of low-OCT-signal artifacts, which leads to thresholding and/or segmentation artifacts, complicating OCTA analysis. This study presents theoretical and case-based descriptions of the causes and effects of low-OCTsignal artifacts. Through these descriptions, we demonstrate that OCTA data interpretation can be ambiguous if performed without consulting corresponding OCT data. Furthermore, using wide-field non-perfusion analysis in diabetic retinopathy as a model widefield OCTA usage-case, we show how qualitative and quantitative analysis can be confounded by low-OCT-signal artifacts. Based on these results, we suggest methods and best-practices for preventing and managing low-OCT-signal artifacts, thereby reducing errors in OCTA quantitative analysis of non-perfusion and improving reproducibility. These methods promise to be especially important for longitudinal studies detecting progression and response to therapy.
New speckle analysis algorithm for flow visualization in optical coherence tomography images
2015 - PRETTO, LUCAS R. de; NOGUEIRA, GESSE E.C.; FREITAS, ANDERSON Z.
Novo algoritmo para visualização de fluxo através do speckle presente em imagens de tomografia por coerência óptica
2014 - PRETTO, L.R. de; NOGUEIRA, G.E.C.; FREITAS, A.Z.
Enhance resolution on OCT profilometry measurements using harmonic artifacts
2015 - RAELE, MARCUS P.; PRETTO, LUCAS R. de; FREITAS, ANDERSON Z. de