J Korean Ophthalmol Soc.  2014 Sep;55(9):1320-1326. 10.3341/jkos.2014.55.9.1320.

Influence of Image Compression on the Interpretation of Optical Coherence Tomography in Diabetic Macular Edema

• Kang S
• Chang YS
• Kim JW
• Kim CG
• Lee TG
• Kim JH

• KMID: 2217115
• DOI: http://doi.org/10.3341/jkos.2014.55.9.1320

Abstract

PURPOSE
To evaluate the influence of image compression on optical coherence tomography (OCT) images in eyes with diabetic macular edema (DME).
METHODS
Twenty eyes of 30 patients diagnosed with DME were included in this retrospective observational case series. Horizontal OCT scans centered at the center of the fovea were conducted using spectral-domain OCT (Spectral OCT/SLO(R)). The images were exported to Tag Image File Format (TIFF) and then transformed to 10, 5, and 1 quality of Joint Photographic Experts Group (JPEG) format using Photoshop. OCT images were taken before and after intravitreal bevacizumab injection. The presence of intraretinal fluid, foveolar detachment, and photoreceptor inner segment/outer segment (IS/OS) disruption were evaluated in each image.
RESULTS
The mean (+/- standard deviation) size of TIFF images and 10, 5 and 1 quality JPEG images were 1712.0, 183.3 +/- 6.8, 90.9 +/- 4.3, 42.8 +/- 1.4 kilobytes (KB), respectively, before the injection and 1712.0, 189.5 +/- 9.1, 94.9 +/- 5.6, 43.4 +/- 1.8 KB, respectively, after the injection. The presence of intraretinal fluid, foveolar detachment, and photoreceptor IS/OS disruption identified in TIFF images was also identified in the compressed JPEG images.
CONCLUSIONS
Quality of retinal OCT image did not influence the estimation of DME despite the JPEG image being compressed to approximately 1/40 of the original TIFF image size.

Keyword

Diabetic macular edema; Image compression; Optical coherence tomography

MeSH Terms

Data Compression*
Humans
Joints
Macular Edema*
Retinaldehyde
Retrospective Studies
Tomography, Optical Coherence*
Bevacizumab
Retinaldehyde

Figure

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  Figure 1. Comparison of image quality between an image of Tag Image File Format (TIFF) format (A, A-1, A-2) and images of 1 quality of Joint Photographic Experts Group (JPEG) compression format (B, B-1, B-2) in an eye with diabetic macular edema before treatment. A-1, B-1: ×600% magnified view of areas enclosed by white square (A, B), A-2, B-1: ×3,200% magnified view of areas enclosed by white square (A-1, B-1). Magnified views show the distorted image. The image was composed of small squares (dotted square, A-2) in the TIFF image, whereas the basic unit composing the JPEG image was relative large square (dotted square, B-1, B-2) which composed of 8×8 small squares. However, the presence of subfoveal serous detachment and small intraretinal cysts were clearly identified even in compressed image.

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  Figure 2. Comparison of image quality between an image of Tag Image File Format (TIFF) format (A, A-1, A-2) and images of 1 quality of Joint Photographic Experts Group (JPEG) compression format (B, B-1, B-2) in an eye with diabetic macular edema after treatment. A-1, B-1: ×600% magnified view of areas enclosed by white square (A, B), A-2, B-2: ×3,200% magnified view of areas indicated by white arrows (A-1, B-1). Magnified view shows the distorted pixels in compressed JPEG image (B-1, B-2). The presence of very small intraretinal cysts white arrows was clearly identified even in compressed image (B-1).

Reference

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