OCT-A Simplified

100%

A step-by-step guide to image acquisition, analysis, and interpretation

Section One

Introduction to OCT-A and the need for a standard operating procedure

Optical coherence tomography angiography is a noninvasive imaging technique that provides three-dimensional visualization of the chorioretinal microvasculature without requiring dye injection, marking a significant advancement in ophthalmic diagnostics. By capturing red blood cell movement through dynamic imaging, OCT-A integrates functional vascular data with the structural details obtained from conventional optical coherence tomography. This capability makes OCT-A a powerful tool for assessing ocular conditions characterized by vascular abnormalities, including age-related macular degeneration and diabetic retinopathy.

Beyond its ability to visualize vascular changes at a microstructural level, OCT-A also offers a distinct advantage over traditional imaging modalities. Unlike fluorescein angiography, which relies on dye injection, OCT-A employs sequential imaging, allowing clinicians to distinguish between superficial and deep retinal vascular layers, an essential differentiation that conventional techniques often fail to achieve. As a result, OCT-A has gained prominence in clinical practice due to its key benefits, including rapid image acquisition, reduced patient discomfort, and the elimination of allergic reactions associated with dye-based techniques. Figure One shows a comparison between fluorescein angiography and an OCT-A image.

However, despite these advantages, the adoption of OCT-A has not been without challenges. Early technological limitations, such as motion artifacts, a narrower field of view compared to conventional methods, and depth-related signal loss, initially hindered image quality and clinical applicability. Nevertheless, continuous advancements in image acquisition and processing have addressed many of these concerns. These refinements have led to broader and more sensitive scanning areas, significantly improving the accuracy and reliability of OCT-A assessments. Even with these advancements, some challenges remain, particularly those related to image misinterpretation due to incomplete or inadequate acquisition and analysis.

To maximize the clinical utility of OCT-A, the implementation of best practices is essential. Optimizing image quality and ensuring accurate interpretation require careful patient preparation, including the use of dilating drops and effective management of common artifacts, both of which are critical for obtaining reliable results. Additionally, patient comfort and stability must be prioritized during the imaging process, as even minor movements can compromise scan quality.

While OCT-A continues to evolve, its role in retinal evaluation remains primarily complementary rather than standalone. Ongoing research aims to refine OCT-A by addressing its current limitations

Comparative benefits and limitations of OCT-A imaging

Five

Two point Two Analysis Two point Three Application

Basic concepts

Two point One Retinal and choroidal circulation

Two point One Circulation Two point Two Analysis Two point Three Application

Two point Two OCT-A imaging and layer-specific analysis

Two point Three Application

Section Two Basic concepts

Three point three Optimizing acquisition

OCT-A acquisition

Factors affecting OCT-A quality

Three point one. Characteristics of the scanning method

Three point two Factors and artifacts Three point three Optimizing acquisition

Section three: OCT-A acquisition

Three point two Factors and artifacts

Section three: OCT-A acquisition

Three point two. Patient-related factors and artifacts

CIRRUS six thousand features for minimizing artifacts

Three point three. Optimizing acquisition with CIRRUS OCT

Section three: OCT-A acquisition

Section Four

Four point one VRI

Section Four: Segmentation and display modes

Four point two. Superficial Retinal Layer

What it shows

Clinical utility

Four point five RPE-RPE fit

Four point three. Deep Retinal Layer

Boundaries

Clinical utility

Four point four. Avascular layer

What it shows

Clinical utility

Section Four: Segmentation and display modes

Boundaries

What it shows

Clinical utility

Four point six. Sub-RPE

What it shows

Clinical utility

Section Four: Segmentation and display modes

Boundaries

What it shows

Clinical utility

Four point eight Choriocapillaris

Boundaries

What it shows

Clinical utility

Section Four: Segmentation and display modes

Boundaries

What it shows

Clinical utility

Four point ten. Retina

What it shows

Clinical utility

Section Four: Segmentation and display modes

Boundaries

Four point twelve. Depth-encoded map

What it shows

Clinical utility

What it shows

Clinical utility

Section Four: Segmentation and display modes

Clinical applicability/indication

Section Five

Verification steps for ensuring the reliability and accuracy of optical coherence tomography angiography scans

Section Five: Optical coherence tomography angiography analysis

Angiographic and structural en face evaluation process.

Section five: OCT-A analysis

Five point two point one. En face angiographic maps

Five point one Angiographic and structural images

Five point two point two Flow overlay on B-scan Section five: OCT-A analysis

Section 5: OCT-A analysis

Section five: OCT-A analysis

Five point two point two Flow overlay on B-scan |

Section five: OCT-A analysis

Five point three point one. Vessel density analysis

Section five: OCT-A analysis

Five point three point three Foveal avascular zone analysis

Section Five: OCT-A analysis

Five point three point five. Clinical applications and challenges

Five point three. Quantitative

Section Six

Six point two. Mid retina etina

Six point three. IS/OS-Ellipsoid zone segmentation

Section Six: Structural en face OCT: Beyond OCT-A quality assessment

Six point three. IS/OS-Ellipsoid zone segmentation

Section Six: Structural en face OCT: Beyond OCT-A quality assessment

Section six: Structural en face OCT: Beyond OCT-A quality assessment

Six point four Choroid

Section Seven

Section Eight

Eight point one. Image processing

Section Eight: Enhancing sensitivity to OCT-A findings

Section Nine

Nine point one. Preparation

| Nine point three Analysis: Quality assessment |

Nine point four Analysis: Interpretation and report

| Nine point three Analysis: Quality assessment | Nine point four Analysis: Interpretation and report

Nine point three. Analysis: Quality assessment

Nine point three Analysis: Quality assessment |

Nine point four Analysis: Interpretation and report |

Section ten

OCT-A quick interpretation flowchart

Section eleven. Training checklists

Capture: OCT-A image acquisition

Post-capture: Image review and optimization

Section twelve. Case studies and practical examples Twelve point one. Diabetic Macular Edema

12.2. Diabetic Retinopathy - FAZ Abnormality

Section twelve: Case studies and practical examples

Twelve point four. Refractory Proliferative Diabetic Retinopathy

Section twelve: Case studies and practical examples

Twelve point six. Non-ischemic Branch Retinal Vein Occlusion

Section twelve: Case studies and practical examples

Twelve point eight. Non-ischemic Central Retinal Vein Occlusion

Section twelve: Case studies and practical examples

Twelve point ten. AMD - GA

Section twelve: Case studies and practical examples

Twelve point twelve. AMD - Type one MNV + Fluid

Section twelve: Case studies and practical examples

Twelve point fourteen. AMD - Type three MNV

Section twelve: Case studies and practical examples

Twelve point sixteen. MacTel Type one

Section twelve: Case studies and practical examples

Twelve point eighteen. Central Serous Chorioretinopathy

Section twelve: Case studies and practical examples

Twelve point twenty. Foveal Hypoplasia

Section twelve: Case studies and practical examples

Overview

The guide outlines the process of acquiring and analyzing OCT-A images, emphasizing its importance in assessing ocular conditions and offering insights for optimizing diagnostic accuracy. By integrating clinical practices, it aims to enhance the understanding and usage of OCT-A among healthcare professionals.

Key Points

1OCT-A allows 3D visualization of chorioretinal microvasculature without dye injection
2The technique offers advantages over fluorescein angiography, including patient safety and comfort
3Best practices for optimal image acquisition are critical for accurate analysis
4OCT-A has applications across various ocular diseases, including diabetic retinopathy and age-related macular degeneration
5Continuous advancements are addressing earlier technological limitations of OCT-A.

Details

Authors: Ricardo Luz Leitão Guerra
Category: Health and Medicine

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