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T. J. Holmes, A. Invernizzi, S. Larkin, G. Staurenghi; Measurement Maps of Dynamic ICG for Neovascular Conditions. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1026.
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Work was carried out to develop and test software algorithms that derive quantitative measures from dynamic indocynanine green (d-ICG) movie sequences and produce image maps of these measures. The main application is in the assessment of response to therapies for neovascular conditions, such as laser photocoagulation of feeder vessels to neovascular lesions and anti-VEGF injection therapy.
Six movie pairs were processed, that were obtained from Heidelberg Retinal Angiograph (HRA) and Spectralis models of scanning laser ophthalmoscopes. Each pair contained a baseline and follow-up movie, taken before and after treatment, respectively. Some of the movie pairs were of feeder-vessel laser photocoagulation therapy and some were of anti-VEGF treatment. The cases were categorized as responders and nonresponders, by standard clinical methods, where the term responder means that the neovascular lesion responded positively to the treatment and nonresponder means that the neovascular lesion progressed to a worse condition after treatment. Quantitative measures were produced for each pixel in the image that reflected (1) the time-delay for dye filling, (2) the overall fluorescence magnitude that is affected by blood volume and flow associated with the pixel, (3) dispersion of the temporal fill pattern that reflects diffusion of the dye, and (4), pulsation magnitude that is affected by cardiac activity.
The resulting images were examined for information that may serve as adjunct information to assist the physician in evaluating the response to therapy or in identifying pathological anatomy such as the feeder vessel, drain vessel and capillary network of the lesion in planning and deciding treatment options.
The measures that showed the most promise for augmented clinical information to the physician were the time-delay (1) and magnitude (2) image maps. The time-delay is an aid to identifying the feeder, drain and capillary network because the earliest fill occurs in the feeder, while the middle and late fills occur in the capillary network and drain, respectively. The magnitude showed decreasing activitiy in the feeder and drain, and sometimes in the capillary network with responders.
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