Image Analysis Methodology for Evaluating Coating Uniformity of Drug-coated Angioplasty Balloons
Semester of Graduation
Master of Science in Biological and Agricultural Engineering (MSBAE)
Biological and Agricultural Engineering
Percutaneous transluminal balloon angioplasty (PTA) is a surgical procedure to treat peripheral artery disease, but restenosis causes suboptimal outcomes in many patients. Drug-coated angioplasty balloons (DCBs) were developed to reduce the risk of restenosis by delivering anti-proliferative drugs to the lesion. The efficacy of DCBs depends on factors like drug loading and drug release rate, both of which are directly impacted by the coating uniformity. This thesis evaluates the uniformity of DBCs using fluorescence microscopy, scanning electron microscopy (SEM), qualitative analysis, and an image processing algorithm. Uniformity was quantified by three measurements: histogram standard deviation, histogram percentage of coverage, and horizontal line profile percent deviation. We compared the uniformity of the balloons before and after stressing them to investigate if this altered the coating’s uniformity. The balloons were stressed by thawing and freezing the samples and then storing them for six months in a freezer, where they were exposed to ambient humidity and atmospheric oxygen. SEM images were acquired of the balloons to visualize the surface characteristics of the coating. We created an algorithm to adjust the intensity values of the fluorescent images along the edges of the balloon, which have elevated values due to the curvature of the balloon. The quantification procedure detected significant differences in the balloons’ uniformity, but the results of all three methods were not consistent with one another. Altering the approach to remove ROIs of non-coated sections of the balloon may be beneficial. Many of the samples had a sinusoidal coating pattern in the longitudinal direction, indicating non-uniformity. Adjusting the coating parameters to improve the spray-ability of the coating solution may improve the coating uniformity in the longitudinal direction. The samples appeared to be affected by the stress conditions, and many of them showed a pattern characteristic of freezing and thawing the samples. The algorithm was able to normalize the images and reduce the intensity at the edges, but further improvements can be made to create smoother corrected images with fewer artifacts.
Zieschang, Allison Dobson, "Image Analysis Methodology for Evaluating Coating Uniformity of Drug-coated Angioplasty Balloons" (2023). LSU Master's Theses. 5753.
Available for download on Saturday, March 28, 2026
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