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Scale Adjustments to Facilitate Two-Dimensional Measurements in OCT Images.

Garcia Garrido M, Mühlfriedel RL, Beck SC, Wallrapp C, Seeliger MW - PLoS ONE (2015)

Bottom Line: The problems encountered with two-dimensional measurements in cases of unequal scales are demonstrated and an estimation of the resulting errors is provided.In this work, we highlight the distortion-related problems in OCT image analysis induced by unequal X and Y scales.Our results demonstrate the need for a proper two-dimensional calibration of OCT data, and we believe that equal scaling will certainly improve the efficiency of OCT image analysis.

View Article: PubMed Central - PubMed

Affiliation: Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, Tuebingen, Germany.

ABSTRACT

Purpose: To address the problem of unequal scales for the measurement of two-dimensional structures in OCT images, and demonstrate the use of intra¬ocular objects of known dimensions in the murine eye for the equal calibration of axes.

Methods: The first part of this work describes the mathematical foundation of major distortion effects introduced by X-Y scaling differences. Illustrations were generated with CorelGraph X3 software. The second part bases on image data obtained with a HRA2 Spectralis (Heidelberg Engineering) in SV129 wild-type mice. Subretinally and intravitreally implanted microbeads, alginate capsules with a diameter of 154±5 μm containing GFP-marked mesenchymal stem cells (CellBeads), were used as intraocular objects for calibration.

Results: The problems encountered with two-dimensional measurements in cases of unequal scales are demonstrated and an estimation of the resulting errors is provided. Commonly, the Y axis is reliably calibrated using outside standards like histology or manufacturer data. We show here that intraocular objects like dimensionally stable spherical alginate capsules allow for a two-dimensional calibration of the acquired OCT raw images by establishing a relation between X and Y axis data. For our setup, a correction factor of about 3.3 was determined using both epiretinally and subretinally positioned beads (3.350 ± 0.104 and 3.324 ± 0.083, respectively).

Conclusions: In this work, we highlight the distortion-related problems in OCT image analysis induced by unequal X and Y scales. As an exemplary case, we provide data for a two-dimensional in vivo OCT image calibration in mice using intraocular alginate capsules. Our results demonstrate the need for a proper two-dimensional calibration of OCT data, and we believe that equal scaling will certainly improve the efficiency of OCT image analysis.

No MeSH data available.


Related in: MedlinePlus

Use of intraocular MicroBeads to determine a correction factor to establish equal X-Y scaling.(A) Schematic drawing of a MicroBead. Encapsulated cells are genetically modified immortalized mesenchymal stem cells which in this case express GFP as a reporter. Scale bar: 100 μm (B). OCT raw images of (C) subretinally and (D) epiretinally placed beads. Scale bar: 200 μm. (E, F) Correction factors to establish X-Y equality for subretinal (E) and epiretinal (F) beads. Corrected OCT images of (G) subretinally and (H) epiretinally placed beads. Scale bar: 200 μm. There was no significant difference between E and F (p = 0,57).
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pone.0131154.g003: Use of intraocular MicroBeads to determine a correction factor to establish equal X-Y scaling.(A) Schematic drawing of a MicroBead. Encapsulated cells are genetically modified immortalized mesenchymal stem cells which in this case express GFP as a reporter. Scale bar: 100 μm (B). OCT raw images of (C) subretinally and (D) epiretinally placed beads. Scale bar: 200 μm. (E, F) Correction factors to establish X-Y equality for subretinal (E) and epiretinal (F) beads. Corrected OCT images of (G) subretinally and (H) epiretinally placed beads. Scale bar: 200 μm. There was no significant difference between E and F (p = 0,57).

Mentions: As a conclusion from the above results, an equal scaling of X and Y axes appears desirable. Therefore, we assessed the use of well-defined intraocular objects to achieve a two-dimensional calibration of the acquired OCT raw images via an explicit relation between X and Y axis data. We show here that dimensionally stable spherical alginate capsules (CellBeads, Fig 3) are suitable in this regard due to their robust nature and their known size of 154 ± 5 μm with low production tolerances.


Scale Adjustments to Facilitate Two-Dimensional Measurements in OCT Images.

Garcia Garrido M, Mühlfriedel RL, Beck SC, Wallrapp C, Seeliger MW - PLoS ONE (2015)

Use of intraocular MicroBeads to determine a correction factor to establish equal X-Y scaling.(A) Schematic drawing of a MicroBead. Encapsulated cells are genetically modified immortalized mesenchymal stem cells which in this case express GFP as a reporter. Scale bar: 100 μm (B). OCT raw images of (C) subretinally and (D) epiretinally placed beads. Scale bar: 200 μm. (E, F) Correction factors to establish X-Y equality for subretinal (E) and epiretinal (F) beads. Corrected OCT images of (G) subretinally and (H) epiretinally placed beads. Scale bar: 200 μm. There was no significant difference between E and F (p = 0,57).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482384&req=5

pone.0131154.g003: Use of intraocular MicroBeads to determine a correction factor to establish equal X-Y scaling.(A) Schematic drawing of a MicroBead. Encapsulated cells are genetically modified immortalized mesenchymal stem cells which in this case express GFP as a reporter. Scale bar: 100 μm (B). OCT raw images of (C) subretinally and (D) epiretinally placed beads. Scale bar: 200 μm. (E, F) Correction factors to establish X-Y equality for subretinal (E) and epiretinal (F) beads. Corrected OCT images of (G) subretinally and (H) epiretinally placed beads. Scale bar: 200 μm. There was no significant difference between E and F (p = 0,57).
Mentions: As a conclusion from the above results, an equal scaling of X and Y axes appears desirable. Therefore, we assessed the use of well-defined intraocular objects to achieve a two-dimensional calibration of the acquired OCT raw images via an explicit relation between X and Y axis data. We show here that dimensionally stable spherical alginate capsules (CellBeads, Fig 3) are suitable in this regard due to their robust nature and their known size of 154 ± 5 μm with low production tolerances.

Bottom Line: The problems encountered with two-dimensional measurements in cases of unequal scales are demonstrated and an estimation of the resulting errors is provided.In this work, we highlight the distortion-related problems in OCT image analysis induced by unequal X and Y scales.Our results demonstrate the need for a proper two-dimensional calibration of OCT data, and we believe that equal scaling will certainly improve the efficiency of OCT image analysis.

View Article: PubMed Central - PubMed

Affiliation: Division of Ocular Neurodegeneration, Institute for Ophthalmic Research, Centre for Ophthalmology, Tuebingen, Germany.

ABSTRACT

Purpose: To address the problem of unequal scales for the measurement of two-dimensional structures in OCT images, and demonstrate the use of intra¬ocular objects of known dimensions in the murine eye for the equal calibration of axes.

Methods: The first part of this work describes the mathematical foundation of major distortion effects introduced by X-Y scaling differences. Illustrations were generated with CorelGraph X3 software. The second part bases on image data obtained with a HRA2 Spectralis (Heidelberg Engineering) in SV129 wild-type mice. Subretinally and intravitreally implanted microbeads, alginate capsules with a diameter of 154±5 μm containing GFP-marked mesenchymal stem cells (CellBeads), were used as intraocular objects for calibration.

Results: The problems encountered with two-dimensional measurements in cases of unequal scales are demonstrated and an estimation of the resulting errors is provided. Commonly, the Y axis is reliably calibrated using outside standards like histology or manufacturer data. We show here that intraocular objects like dimensionally stable spherical alginate capsules allow for a two-dimensional calibration of the acquired OCT raw images by establishing a relation between X and Y axis data. For our setup, a correction factor of about 3.3 was determined using both epiretinally and subretinally positioned beads (3.350 ± 0.104 and 3.324 ± 0.083, respectively).

Conclusions: In this work, we highlight the distortion-related problems in OCT image analysis induced by unequal X and Y scales. As an exemplary case, we provide data for a two-dimensional in vivo OCT image calibration in mice using intraocular alginate capsules. Our results demonstrate the need for a proper two-dimensional calibration of OCT data, and we believe that equal scaling will certainly improve the efficiency of OCT image analysis.

No MeSH data available.


Related in: MedlinePlus