Análise e otimização dos algoritmos para angiografia por tomografia por coerência óptica e desenvolvimento de Phantom por impressão 3D
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Data
2021
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Universidade Brasil
Resumo
Skin grafts are surgically applied to repair skin lesions such as burns and extensive
necrosis. The success of this surgical procedure is associated with good blood supply
in the grafted region. Thus, the assessment of angiogenesis during the tissue repair
process is essential for its prognosis. The development of non-invasive evaluation
techniques is extremely important for the success of this procedure. One of the
promising techniques is Optical Coherence Tomography Angiography (OCT-A), a noninvasive technique that can be used to obtain images of the vascularization of
biological tissues. The adoption of this technique as a clinical practice in dermatology
involves reducing its cost, and the use of equipment with a low acquisition rate (low
cost) is a possible path. Thus, this work aimed to implement and optimize algorithms
for obtaining angiography images by optical coherence tomography (OCT-A) for
applications in images acquired with low acquisition rate and cost equipment. To test
those methods, it is requiring the use of phantom that simulate the behavior of the
microvascular system. Thus, this work also aimed at the development of a phantom to
simulate a microvascular system using 3D printing technology. Phantoms containing
microchannels were designed and printed on polylactic acid (PLA) using a 3D printer
by fused filament deposition. These PLA phantoms were imaged with the OCT system
(OQLabScope - Lumedica, USA). Seven different OCT-A methods were implemented
(HFM, STS, CM, SV, OSV, ISC and UHS-OMAG) and compared against their
processing time, signal-to-noise ratio, contrast, and contrast-to-noise ratio. The OSV
and CM methods showed better overall performance based on these parameters, but
CM shown higher processing time. An optimization of the CM method was proposed
in this work, reducing the processing time by 99.2%, a significant gain for the algorithm
that presented better performances in contrast
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Palavras-chave
Tomografia por Coerência Óptica - OCT, Angiografia OCT - OCT-A, Phantom de microcanais, Mapa de correlação otimizado