Improved reproducibility in measuring the laminar thickness on enhanced depth imaging SD-OCT images using maximum intensity projection.
OBJECTIVE
To investigate whether the thin-slab maximum intensity projection (MIP) image improves the reproducibility of the measurement of spectral domain optical coherence tomography (SD-OCT) based lamina cribrosa thickness (LCT).


METHODS
Optic discs of 63 open angle glaucoma patients or glaucoma suspects were scanned with enhanced depth imaging spectral domain optical coherence tomography (SD-OCT). The B-scan images were constructed three-dimensionally using maximum intensity projection (MIP). The whole mip volume was then cut into thin slabs of two scan-line distance width (approximately 64 μm) at three 3 locations: mid-horizontal, and superior and inferior mid-peripheral regions of the optic nerve head. The LCT was measured in the thin-slab MIP images (LCT-MIP) and the three B-scans corresponding to each thin-slab MIP image (LCT-Bscan) at the three regions in each eye. The interobserver and intraobserver reproducibility of measuring the LCT-MIP and LCT-Bscan were evaluated by calculating the intraclass correlation coefficient (ICC), coefficient of variation (CV), and coefficient of repeatability (CR). The agreement between the LCT-MIP and the LCT-Bscan was assessed by Bland-Altman analysis.


RESULTS
The thin-slab MIP images provided better image contrast with more distinct borders of the lamina cribrosa compared to the B-scan images. Both intraobserver and interobserver ICCs were higher for LCT-MIP than for LCT-Bscan in all areas. The 95% limit of agreement of measurement differences between LCT-Bscan and LCT-MIP ranged from -29.43 to 32.55 μm.


CONCLUSIONS
The thin-slab MIP images provided a higher reproducibility in measuring the LCT using SD-OCT than the B-scan images. With thin-slab MIP images, the detection of the laminar borders was more straightforward. This technique should facilitate the evaluation of the lamina cribrosa.
Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
Eun Ji
EJ
Lee
Tae-Woo
TW
Kim
Robert N
RN
Weinreb
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007089:Image Enhancement; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000379:methods*; D014792:Visual Acuity; D055815:Young Adult