Purpose:
To study if Digital Imaging and Communications in Medicine (DICOM) compression and transmission of optic nerve digital simultaneous stereo images affect clinical interpretation.
Methods:
The DICOM platform is widely used in radiology and is a standard for telemedicine transmission of digital images to a reading center. Following standards set forward by the American Telemedicine Association and Working Group 9, images were obtained with a Nidek 3–Dx (Gamagori, Japan) simultaneous stereo disc camera equipped with a Nikon D1x (Tokyo, Japan) 6.1 megapixel camera attachment. Fifteen optic nerve simultaneous stereo images from glaucoma patients were analyzed independently twice, in random order, by 2 glaucoma specialists (30 evaluations per rater). Images were evaluated directly from a computer monitor (32 bytes with a resolution of 1024 x 768 pixels) using a Berezin stereo viewer in a dark room, held at a fixed angle to the monitor. Baseline assessment of vertical and horizontal cup–to–disc ratio (CDV and CDH), and quality of images (score 1=worse, 5=best) were determined. Images were then transmitted to a distant location and returned to our primary site using DICOM standards, and without any image manipulation. The decoded images were reassessed by the same 2 glaucoma specialists.
Results:
Image file size in KB was slightly increased for all received (mean 2545KB) vs transmitted (mean 2460KB) images. This change reflects the DICOM encryption upon transmission. Baseline means and SD for CDV, CDH, and quality score were 0.66+/–0.22, 0.59+/–0.23, and 3.9+/–0.93 respectively. Baseline replicate correlations were high for all parameters: CDV (0.952), CDH (0.965) and quality score (0.856). Received DICOM image analysis for means and SD for CDV, CDH, and quality score were 0.66+/–0.22, 0.62+/–0.23, and 3.73+/–0.94, respectively. Differences between transmitted and received stereo image analyses for CDV, CDH, and quality score were not statistically significant (Table).
Conclusions:
Clinical interpretation of digital stereo images of glaucomatous optic nerves appears unaffected by the compression, encryption, and transmission using the DICOM platform. Image quality was not degraded.
Keywords: image processing • imaging/image analysis: clinical • optic disc