If you’re considering GAE for knee osteoarthritis, imaging plays a central role at every stage — from determining whether you’re a candidate, to guiding the procedure itself, to tracking your response afterward. Understanding what each imaging modality tells your physician helps you navigate the process with confidence.
Pre-Procedure Imaging: Establishing Candidacy
Standing knee X-rays are the foundational imaging study. They establish the diagnosis of osteoarthritis, assess the degree of cartilage loss and joint space narrowing, and assign a Kellgren-Lawrence (KL) grade — the standardized scale used in every GAE clinical trial to define disease severity.
The KL grading system classifies knee OA from grade 0 (no radiographic disease) through grade 4 (severe). GAE has demonstrated its strongest results in patients with KL grade 2–3 — moderate disease with cartilage loss and osteophytes, but preserved (though narrowed) joint space. Grade 1 patients may not have enough inflammatory neovascularity to target effectively. Grade 4 patients — with complete joint space loss and bone-on-bone contact — typically need joint replacement.
Standing (weight-bearing) films are essential. Non-weight-bearing X-rays can underestimate joint space narrowing. Always ask for standing AP and lateral views when your imaging is ordered.
MRI adds important information in selected cases. While not universally required before GAE, MRI can detect synovitis (joint lining inflammation) — a positive predictor of GAE response, bone marrow edema (stress reaction in the subchondral bone), meniscal tears or other structural pathology that may be contributing to pain, and ligament integrity.
MRI findings of active synovitis or bone marrow edema suggest a significant inflammatory component to the patient’s pain — exactly the pathology that GAE targets. Some practitioners use MRI findings to select patients most likely to respond.
During the Procedure: Real-Time Angiographic Guidance
The GAE procedure itself is performed entirely under fluoroscopic guidance (real-time X-ray). Once the microcatheter is positioned in the genicular arteries, contrast dye is injected to create a detailed angiographic map of the knee’s blood supply.
This angiogram reveals the areas of abnormal neovascularity — the dense, pathological network of tiny blood vessels that develops in inflamed synovial tissue. On angiography, this appears as a characteristic pattern called ‘synovial blush’ — a cloud-like enhancement in the tissue surrounding the joint.
The physician uses this real-time map to selectively deliver microspheres to the abnormal vessels while preserving normal blood supply. This is the precision advantage of GAE: the treatment is targeted specifically to the diseased vasculature, guided by live imaging.
Frequently Asked Questions
After the Procedure: Tracking Response
Follow-up imaging is typically not routine after GAE — clinical response (pain improvement, functional capacity) is the primary outcome measure. However, if clinical response is incomplete or if there’s a question about disease progression, follow-up X-rays or MRI can be obtained to assess joint space status and evaluate for residual synovitis.
At SACMD, Dr. Chun reviews all imaging at the consultation and recommends any additional studies needed before proceeding. Bring your most recent imaging or the facility name so we can request it.
Schedule a consultation: Call (240) 427-1630 or visit www.sacmd.com
Disclaimer: This article is for informational purposes only and does not constitute medical advice.
References: -e 1. Kellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis. 1957. 2. Taslakian B, et al. Prospective GAE Trial. JVIR. 2025. 3. Cusumano LR, et al. GAE 2-Year IDE Trial. JVIR. 2024. 4. Cleveland Clinic. Knee X-Ray — What to Expect. 5. Mayo Clinic. MRI — Knee Imaging.
Dr. Rahbar is an esteemed vascular surgeon at Surgical Associates, known for their exceptional contributions to the field of vascular surgery. As a board-certified vascular surgeon with over 20 years of invaluable experience, Dr. Rahbar is a respected authority in the medical community serving Camp Spring, Maryland and the whole community of Maryland. Their unwavering dedication to providing advanced care for patients with diseases of the arteries and veins has earned them a reputation for excellence. Dr. Rahbar’s work embodies a passion for precision and compassion, improving the lives of those they serve, one procedure at a time.