Cystoid Macular Edema and Netra Restoration Therapy

Cystoid Macular Edema and Netra Restoration Therapy

Cystoid macular edema, often abbreviated CME, is a retinal condition in which fluid accumulates in cyst-like spaces within the macula. The macula is the central part of the retina responsible for sharp central vision, reading, facial recognition, contrast sensitivity, and detailed visual tasks. When fluid collects in the macular layers, vision may become blurred, distorted, dim, wavy, or reduced in contrast. Some patients notice a central haze or difficulty reading even when peripheral vision remains relatively preserved.

CME is not a single disease with one cause. It is better understood as a common final pathway of retinal stress. It can occur in association with inflammatory eye disease, retinal vascular disorders, diabetic retinal disease, inherited retinal degeneration, post-procedural retinal irritation, tractional stress, and other conditions that disturb normal retinal fluid control. For this reason, meaningful support for CME should not focus only on the visible swelling. It should also ask why the retina is leaking fluid, why the blood-retinal barrier is unstable, why fluid clearance is impaired, and why the macular tissue is unable to restore normal balance.

Netra Restoration Therapy, or NRT, is a full-spectrum integrative ophthalmology platform designed to support ocular health through multiple biological pathways at the same time. For CME, the emphasis is on supporting the biological terrain that influences retinal vascular permeability, blood-retinal barrier integrity, inflammatory balance, Muller cell function, retinal metabolism, oxidative stress, mitochondrial energy production, microvascular circulation, and whole-body factors that may affect the eye. NRT is not presented as a cure for CME, and it does not replace appropriate ophthalmic monitoring. It is positioned as an adjunctive, systems-based approach for patients seeking broader biological support for chronic or recurrent macular edema.

A Comprehensive Therapy Designed to Address the Key Underlying Drivers of Cystoid Macular Edema

CME is often described structurally: there is swelling, thickening, and cystic fluid within the macula. Optical coherence tomography can show the pattern, location, and severity of the fluid. That structural information is extremely valuable. Yet structure is only one layer of the story. The deeper question is biological: what created the conditions for fluid to enter and remain inside the macular retina?

Modern retinal literature describes CME as involving disruption of the blood-retinal barrier, vascular hyperpermeability, inflammation, leukostasis, cytokine signaling, and glial dysfunction. A 2019 review in Korean Journal of Ophthalmology emphasized that CME can be approached through both vasogenic mechanisms, such as inflammation and vascular hyperpermeability, and cytotoxic mechanisms, particularly retinal Muller cell dysfunction. Earlier reviews also describe CME as excess fluid accumulation after breakdown of the blood-retinal barrier. This makes CME a biologically complex condition, not merely an imaging finding.

NRT is designed around this complexity. It seeks to support the key underlying drivers of CME from multiple angles rather than treating the macula as an isolated compartment. The macula depends on healthy blood vessels, intact endothelial tight junctions, retinal pigment epithelium pumping, glial cell water transport, mitochondrial energy, inflammatory restraint, oxygen delivery, and systemic metabolic stability. If any of these systems become stressed, retinal fluid balance may be disturbed.

For CME, NRT may focus on the following support goals:

• Support retinal microcirculation and oxygen delivery.
• Support blood-retinal barrier stability and vascular integrity.
• Promote healthier inflammatory signaling and cytokine balance.
• Support Muller cell and retinal glial fluid regulation.
• Reduce oxidative stress burden in the retinal environment.
• Support mitochondrial energy production in retinal tissue.
• Support retinal pigment epithelium function and fluid handling.
• Evaluate systemic contributors such as metabolic inflammation, vascular health, gut health, sleep, stress physiology, and immune balance.
• Promote retinal neuroprotection and cellular resilience.

This systems-based model is not meant to criticize conventional ophthalmology. Conventional retinal imaging and diagnosis are essential. However, NRT adds a different question: how can we support the biology that allows the macula to regulate fluid, maintain barrier integrity, calm chronic inflammatory stress, and preserve visual function?

Why Treatment Support for Cystoid Macular Edema Should Be Multi-Factorial

CME should be approached as a multifactorial condition because macular fluid accumulation usually reflects the convergence of several biological failures. The blood-retinal barrier may become leaky. Retinal vessels may become inflamed. Muller cells may lose efficient water and potassium handling. The retinal pigment epithelium may struggle to transport fluid outward. Oxidative stress may injure endothelial cells and glia. Mitochondrial energy decline may weaken active transport mechanisms. Systemic inflammation and metabolic dysfunction may add further pressure.

A single-mechanism explanation can be too narrow. The macula is not only a vascular structure and not only neural tissue. It is part of a neurovascular-glial unit in which neurons, capillaries, pericytes, Muller cells, microglia, astrocytes, the retinal pigment epithelium, and immune signals interact. CME occurs when this unit loses homeostatic control.

Blood-Retinal Barrier Dysfunction

The blood-retinal barrier helps keep plasma proteins, inflammatory molecules, and excess fluid out of retinal tissue. When this barrier is disrupted, proteins and solutes enter the retina and draw water with them. This creates a fluid imbalance in the macula. Reviews of macular edema describe blood-retinal barrier breakdown as a central requirement for retinal fluid accumulation. The barrier can be affected by inflammation, vascular endothelial stress, ischemia, oxidative damage, cytokines, and mechanical disruption.

NRT places barrier integrity at the center of CME support. In practical terms, this means supporting vascular health, endothelial function, inflammatory balance, retinal metabolism, and systemic factors that influence microvascular stability.

Inflammation and Cytokine Signaling

Inflammation is one of the most important drivers of CME. Inflammatory mediators can loosen endothelial tight junctions, increase vascular permeability, activate microglia, stimulate vascular leakage, and impair retinal fluid clearance. Cytokines such as IL-6, IL-1 beta, TNF-alpha, IL-8, and other inflammatory mediators are frequently discussed in macular edema literature. IL-6, in particular, has been reviewed as an important molecular contributor to macular edema because of its relationship to vascular permeability and inflammatory amplification.

NRT seeks to support inflammatory balance rather than simply suppressing normal immune activity. The goal is to help the retinal environment move away from chronic inflammatory signaling and toward more stable tissue regulation. This may include support for gut health, metabolic health, nutrition, stress physiology, sleep, and botanical strategies that are studied for anti-inflammatory and antioxidant properties.

Vascular Hyperpermeability and Microvascular Stress

CME is often associated with leakage from retinal vessels. Vascular hyperpermeability can arise when endothelial cells are stressed by hypoxia, inflammatory cytokines, oxidative injury, metabolic dysfunction, or impaired autoregulation. The result is abnormal movement of fluid from the vascular compartment into retinal tissue.

NRT considers retinal microvascular health essential. This includes ocular blood flow, endothelial resilience, nitric oxide balance, autonomic regulation, systemic vascular markers, and inflammatory load. The goal is not to make a narrow claim that all CME is a circulation disorder. Rather, vascular stability is one of the key biological foundations of macular fluid balance.

Muller Cell Dysfunction and Retinal Fluid Regulation

Muller cells are the main glial cells of the retina. They extend across the retinal layers and help regulate potassium, water movement, neurotransmitter balance, metabolic support, structural stability, and communication between neurons and vessels. Research has described Muller cell swelling, impaired water transport, and disturbed potassium regulation as important components of retinal edema. A 2023 review on diabetic macular edema noted that Muller cells contribute to macular drainage and blood-retinal barrier integrity.

This matters because CME is not only leakage into the retina. It can also involve impaired fluid clearance from the retina. If the drainage and homeostatic functions of Muller cells are compromised, cystoid spaces may persist even when leakage is not the only factor. NRT therefore includes glial health and retinal neurovascular support as part of a broader CME strategy.

Oxidative Stress

Oxidative stress can damage retinal endothelial cells, Muller cells, photoreceptors, the retinal pigment epithelium, and mitochondria. It can also amplify inflammation and weaken vascular barrier function. Retinal tissue is especially vulnerable because it has high oxygen demand and is exposed to light, metabolic activity, and lipid-rich membranes.

NRT addresses oxidative stress as a major terrain factor. This may include dietary and botanical support, mitochondrial support, sleep and stress regulation, metabolic optimization, and reduction of inflammatory burden. The purpose is to support the retina's endogenous capacity to resist injury and restore homeostasis.

Mitochondrial Energy Strain

Fluid regulation is energy-dependent. Retinal cells require ATP to maintain ion gradients, active transport, neurotransmitter clearance, antioxidant recycling, and barrier maintenance. When mitochondria are stressed, cells become less able to regulate fluid, resist oxidative injury, or repair damage. Mitochondrial dysfunction also increases reactive oxygen species, which can further injure retinal vessels and glial cells.

NRT includes mitochondrial support because the macula is metabolically demanding. Supporting mitochondrial function may involve nutrition, oxygen delivery, vascular support, inflammation reduction, circadian rhythm support, and lifestyle factors that influence cellular energy.

Systemic Terrain: Metabolic, Immune, Vascular, and Gut-Eye Factors

CME often appears in the eye, but the forces that influence it may extend beyond the eye. Systemic inflammation, metabolic dysregulation, glycemic stress, vascular dysfunction, autoimmune activity, sleep disruption, stress physiology, and gut barrier dysfunction may all influence retinal inflammatory and vascular tone. The gut-retina axis is an emerging field suggesting that intestinal microbiome balance and immune signaling may affect retinal disease biology through inflammatory metabolites, immune activation, and vascular changes.

NRT evaluates the whole person because the retina is part of the body. This does not mean that every case of CME is caused by gut dysfunction or systemic inflammation. It means that systemic terrain can influence how stable or unstable the retinal environment becomes.

Key Biological Mechanisms in Cystoid Macular Edema

Retinal Fluid Imbalance

Macular edema occurs when fluid entry exceeds fluid exit. Fluid can enter through leaky retinal vessels or a compromised outer retinal barrier. Fluid exit depends on Muller cell transport, retinal pigment epithelium pumping, intact tissue architecture, and healthy vascular drainage. CME forms when this balance is lost and cyst-like spaces appear within the macular retina, often in the inner nuclear and outer plexiform layers.

The macula is especially vulnerable because it has dense photoreceptors, high metabolic demand, specialized Muller cell architecture, and limited extracellular fluid handling in the central avascular zone. This makes small disturbances in fluid regulation visually significant.

Inner Blood-Retinal Barrier Breakdown

The inner blood-retinal barrier is formed by retinal vascular endothelial cells and their tight junctions, supported by pericytes, Muller cells, astrocytes, and basement membrane structures. When inflammatory cytokines, oxidative stress, hypoxia, or metabolic injury damage this barrier, vascular leakage may occur. In CME, this leakage can lead to fluid accumulation in the macular retina.

Supporting the inner barrier requires attention to endothelial function, inflammation, oxidative stress, and retinal neurovascular communication. This is one of the reasons NRT uses a systems-based model rather than focusing only on the fluid seen on imaging.

Outer Blood-Retinal Barrier and RPE Fluid Pumping

The retinal pigment epithelium, or RPE, helps regulate the outer blood-retinal barrier and transports fluid from the retina toward the choroid. When RPE function is impaired, fluid clearance may decline. Although CME is often discussed in relation to retinal vascular leakage, the RPE can also influence how fluid is handled, especially when there is subretinal fluid or broader macular dysfunction.

NRT includes RPE support through oxidative stress reduction, mitochondrial support, vascular support, and nutrition-focused strategies. The RPE is metabolically active and vulnerable to inflammation and oxidative injury.

Leukostasis and Microvascular Inflammation

Leukostasis refers to the adhesion of white blood cells to retinal vascular endothelium. This process can contribute to capillary obstruction, endothelial injury, vascular leakage, and local inflammatory amplification. CME literature describes leukostasis and related cytokines as part of the inflammatory pathogenesis of cystoid fluid accumulation.

From an integrative perspective, leukostasis reflects a broader inflammatory and vascular terrain. NRT therefore pays attention to systemic inflammatory load, vascular health, oxidative stress, metabolic stability, and immune balance.

Cytokine Dysregulation

Cytokines act as signaling molecules within the immune system and retinal tissue. In CME, elevated inflammatory cytokines may weaken endothelial tight junctions, increase vascular permeability, activate glial cells, and prolong edema. IL-6, IL-1 beta, TNF-alpha, IL-8, MCP-1, and related mediators are frequently investigated in macular edema associated with retinal vascular and inflammatory disease.

NRT does not claim to block a single cytokine. Instead, it seeks to support the upstream terrain that influences cytokine expression: oxidative stress, gut and systemic inflammation, metabolic health, autonomic stress, and tissue resilience.

Muller Cell Swelling and Glial Stress

Muller cells are central to retinal water and ion homeostasis. They help move water out of retinal tissue and regulate potassium channels, aquaporins, neurotransmitters, and metabolic exchange. When Muller cell function is disturbed, they may swell and contribute to intracellular edema. Chronic stress may also reduce their ability to clear extracellular fluid, allowing cystoid spaces to persist.

This mechanism is important because it reframes CME as more than a vessel leakage problem. It is also a glial-fluid regulation problem. A comprehensive approach should support the retinal glial environment, not just the vascular compartment.

Neurovascular Unit Dysfunction

The retina functions as a neurovascular unit. Neurons, capillaries, pericytes, Muller cells, microglia, and endothelial cells communicate continuously. When this communication is disrupted, vascular leakage, inflammation, neuronal stress, and glial dysfunction can reinforce one another. CME reflects failure of this coordinated system.

NRT's neurovascular focus is especially relevant here. Supporting retinal health means supporting the interactions among circulation, inflammation, glial function, metabolism, and neural tissue survival.

Oxidative Stress and Mitochondrial Dysfunction

Oxidative stress and mitochondrial dysfunction are closely linked. Damaged mitochondria produce more reactive oxygen species, and oxidative stress further damages mitochondria. This cycle can weaken endothelial cells, Muller cells, photoreceptors, and RPE cells. It can also activate inflammatory signaling and impair barrier integrity.

For CME, mitochondrial support is not a cosmetic add-on. It is relevant because retinal fluid transport, ion gradients, and barrier maintenance require cellular energy. The macula is energy intensive, and energy failure can reduce retinal resilience.

Hypoxia and Metabolic Stress

Retinal hypoxia can increase vascular permeability and inflammatory signaling. Hypoxia-related pathways may interact with vascular growth factors, cytokines, leukostasis, oxidative stress, and glial dysfunction. In CME associated with retinal vascular disease, oxygen delivery and microvascular integrity are especially important.

NRT considers oxygen delivery and vascular regulation part of the larger retinal terrain. This may include evaluating circulation, cardiometabolic risk, autonomic regulation, systemic inflammation, and lifestyle factors that influence oxygenation.

Neuroinflammation and Microglial Activation

Microglia are immune cells of the retina. When activated chronically, they may release inflammatory mediators and amplify retinal stress. Neuroinflammation can influence vascular permeability, neuronal injury, glial function, and tissue repair. In chronic CME, this type of low-grade inflammatory activation may contribute to persistent retinal vulnerability.

NRT seeks to support a calmer retinal inflammatory environment through whole-person strategies that address immune balance, oxidative stress, metabolic health, and stress physiology.

What Is Netra Restoration Therapy for Cystoid Macular Edema?

Netra Restoration Therapy is a comprehensive, synergistic, multi-target integrative ophthalmology approach designed to support ocular health through several biological pathways simultaneously. For CME, NRT focuses on supporting the macula's ability to regulate fluid, maintain barrier stability, reduce inflammatory stress, preserve neurovascular communication, and support visual function.

NRT may include individualized combinations of acupuncture-based ocular support, Traditional Chinese Medicine principles, Ayurvedic principles, nutritional support, botanical and herbal medicine, functional medicine evaluation, vascular and metabolic support, stress physiology support, sleep and lifestyle guidance, and whole-person care. The exact approach should be individualized based on the underlying cause of CME, retinal imaging, medical history, systemic health, visual symptoms, and patient goals.

In modern scientific language, NRT is best understood as a systems-based biological support platform. It is not a single procedure, single supplement, or single mechanism. CME is multi-pathway; therefore, NRT is designed to work across multiple support domains:

• Barrier support: helping stabilize the biological environment around the blood-retinal barrier.
• Vascular support: promoting healthier microcirculation and endothelial resilience.
• Inflammation support: reducing chronic inflammatory burden and supporting cytokine balance.
• Glial support: supporting Muller cell function, retinal fluid handling, and neurovascular communication.
• Mitochondrial support: supporting cellular energy production needed for fluid transport and repair.
• Oxidative stress support: supporting antioxidant defense and reducing redox burden.
• Systemic terrain support: addressing metabolic, gut, immune, stress, sleep, and circulatory factors that may influence retinal health.

NRT should be viewed as adjunctive care. Patients with CME should continue appropriate eye examinations and retinal imaging. Sudden changes in vision, distortion, new central blur, or rapid worsening should be evaluated promptly by an eye-care professional.

How NRT Supports the Biological Terrain in Cystoid Macular Edema

Supporting Ocular Blood Flow and Microvascular Health

Healthy retinal circulation is necessary for oxygen delivery, nutrient exchange, endothelial stability, and waste clearance. In CME, microvascular inflammation, hypoxia, and vascular leakage may contribute to fluid accumulation. NRT supports ocular blood flow by considering both local and systemic vascular factors, including endothelial function, autonomic balance, metabolic health, inflammation, and circulation.

From a systems biology perspective, vascular health is not separate from inflammation or metabolism. Endothelial cells respond to cytokines, oxidative stress, blood pressure patterns, glucose stress, and immune signals. Supporting the vascular terrain may help create a more stable environment for the macula.

Supporting Blood-Retinal Barrier Integrity

The blood-retinal barrier is one of the central biological structures involved in CME. NRT seeks to support barrier stability by addressing the factors that weaken it: oxidative injury, inflammatory cytokines, vascular stress, metabolic dysfunction, and glial dysregulation. This approach does not claim to physically seal the barrier. Rather, it supports the biological conditions that allow barrier cells to function more effectively.

Supporting Inflammatory Balance

Chronic inflammation can keep the retina in a state of vulnerability. NRT may support inflammatory balance through nutritional strategies, botanical compounds, acupuncture-based regulation, gut health support, metabolic evaluation, stress reduction, and lifestyle measures. The goal is to reduce the inflammatory terrain that can contribute to vascular permeability and glial stress.

Traditional Chinese Medicine may describe certain CME patterns using terms such as Dampness, Phlegm, Blood Stasis, Qi Deficiency, Spleen Qi Deficiency, Liver Blood Deficiency, or Kidney deficiency. In biomedical interpretation, these may loosely parallel fluid dysregulation, impaired microcirculation, metabolic weakness, inflammatory burden, tissue undernourishment, or chronic degenerative stress. These are conceptual parallels, not exact scientific equivalents.

Supporting Muller Cell and Retinal Glial Function

Because Muller cells are central to retinal water and ion regulation, NRT includes glial health as a key concept. Supporting Muller cell function may involve reducing oxidative stress, improving energy production, supporting microcirculation, calming inflammation, and improving systemic metabolic conditions that affect retinal tissue. The goal is to support the retina's own fluid-regulating architecture.

Supporting Oxidative Stress Reduction

Oxidative stress can intensify inflammation, barrier breakdown, mitochondrial dysfunction, and cellular injury. NRT addresses oxidative stress through whole-person strategies that may include nutrition, botanical medicine, sleep support, metabolic optimization, and lifestyle changes. Herbal medicine is increasingly studied through network pharmacology, where multiple compounds may influence antioxidant, inflammatory, vascular, and mitochondrial pathways at the same time.

Supporting Mitochondrial Function

Mitochondria provide the energy required for active transport, ion homeostasis, antioxidant defense, and tissue repair. In CME, mitochondrial strain may make retinal cells less able to handle fluid and inflammation. NRT supports mitochondrial function through oxygen delivery, nutrition, circulatory support, stress regulation, sleep optimization, and anti-inflammatory terrain work.

Supporting Retinal Pigment Epithelium Fluid Transport

The RPE helps move fluid out of the retina and maintain outer retinal homeostasis. NRT supports RPE function by addressing oxidative stress, mitochondrial energy, inflammation, vascular supply, and nutritional status. This may be especially relevant when CME occurs alongside broader macular or outer retinal stress.

Supporting the Gut-Retina and Immune-Metabolic Axis

The gut-retina axis is an emerging research field connecting intestinal barrier function, microbiome balance, microbial metabolites, systemic inflammation, and retinal disease. While this field is still developing, it supports the integrative idea that the retina is influenced by whole-body immune and metabolic signals. NRT may evaluate digestive health, inflammatory triggers, nutrient absorption, and systemic markers when clinically relevant.

Translating Traditional Medicine into Modern Biomedical Language

NRT uses traditional systems such as TCM and Ayurveda while interpreting them through modern physiology whenever possible. In Ayurveda, concepts such as Vata, Pitta, Kapha, Rakta Dhatu, Majja Dhatu, and Ojas may be discussed as traditional frameworks related to nervous system regulation, inflammation, circulation, tissue nourishment, neuro-resilience, and vitality. These are not direct biomedical definitions, but they can help organize a whole-person view of retinal disease.

When herbal medicine is used, it should not be described as a single-target remedy. A single herb may contain dozens or hundreds of bioactive compounds. A traditional formula may contain hundreds or thousands of phytochemicals. Modern network pharmacology, metabolomics, transcriptomics, and systems biology are increasingly used to study how botanical compounds may influence multiple pathways at once, including oxidative stress, inflammation, endothelial function, mitochondrial health, and tissue resilience.

Supporting Visual Function and Quality of Life

CME can interfere with reading, driving, computer use, facial recognition, depth perception, contrast, and daily independence. NRT supports visual function by addressing the broader biological environment of the macula. The aim is not to promise a cure, but to support the retinal terrain in which visual function depends.

Patients with chronic CME often want more than monitoring of retinal thickness. They want to understand what can be done to support the tissue itself, reduce systemic inflammatory burden, strengthen metabolic resilience, and protect the macula over time. NRT is designed to answer that need through a comprehensive, individualized, adjunctive approach.

Frequently Asked Questions on Cystoid Macular Edema

Selected References for Scientific Support

• Rotsos TG, Moschos MM. Cystoid macular edema. Clinical Ophthalmology. 2008. This review describes CME as excess macular fluid accumulation associated with disruption of the blood-retinal barrier and multiple underlying ocular conditions.
• Chung YR, et al. Insights into the pathogenesis of cystoid macular edema: leukostasis and related cytokines. Korean Journal of Ophthalmology. 2019. This review discusses CME through vasogenic mechanisms such as vascular hyperpermeability and inflammation, as well as cytotoxic mechanisms related to Muller cell dysfunction.
• Bringmann A, Reichenbach A, Wiedemann P. Pathomechanisms of cystoid macular edema. Ophthalmic Research. 2004. This review describes vascular leakage after blood-retinal barrier breakdown and the role of retinal fluid dynamics in CME.
• Daruich A, Matet A, Moulin A, et al. Mechanisms of macular edema: beyond the surface. Progress in Retinal and Eye Research. 2018. This paper reviews major mechanisms involved in macular edema, including vascular leakage, inflammation, and retinal homeostatic failure.
• Bringmann A, Wiedemann P. Muller cells in retinal disease and edema. Graefe's Archive for Clinical and Experimental Ophthalmology. 2012. This work discusses Muller cell physiology and its relevance to retinal edema and degeneration.
• Reichenbach A, Wurm A, Pannicke T, Iandiev I, Wiedemann P, Bringmann A. Muller cells as players in retinal degeneration and edema. Graefe's Archive for Clinical and Experimental Ophthalmology. 2007. This article highlights disturbed fluid transport through Muller cells as a pathogenic factor in retinal edema.
• Lai D, et al. The Role of Muller Cells in Diabetic Macular Edema. Investigative Ophthalmology & Visual Science. 2023. This review emphasizes Muller cells in macular drainage, blood-retinal barrier integrity, and neurovascular unit dysfunction.
• Ascaso FJ, et al. The Role of Inflammation in the Pathogenesis of Macular Edema. Mediators of Inflammation. 2014. This review discusses inflammatory mediators in macular edema associated with retinal vascular disease.
• Yang JY, et al. Interleukin-6 and Macular Edema: A Review. Journal of Clinical Medicine. 2023. This review focuses on IL-6 as a pro-inflammatory cytokine involved in macular edema biology.
• Ferreira LB, et al. Inflammatory cytokines as mediators of retinal endothelial barrier dysfunction in non-infectious uveitis. Clinical & Experimental Immunology. 2023. This review discusses cytokine effects on retinal endothelial barrier integrity.
• Jadeja RN, et al. Oxidative Stress and Inflammation in Retinal Degeneration. Antioxidants. 2021. This review summarizes the interaction between oxidative stress and inflammation in retinal disease.
• Kohli P, et al. Macular Edema. StatPearls. Updated 2024. This clinical reference describes macular edema as fluid accumulation from mismatch between retinal fluid entry and exit mechanisms and highlights symptoms and diagnostic imaging.