CT Arthrogram (Shoulder / Hip / Wrist / Knee / Elbow / Ankle)

Indications

• Internal derangement when MRI is contraindicated or degraded by hardware: labral tears (shoulder/hip), TFCC and intrinsic ligament tears (wrist), osteochondral lesions
• Intra-articular loose bodies
• Painful arthroplasty (combined with aspiration/anesthetic injection)
• Post-repair assessment (e.g. recurrent labral tear)

Patient prep

• Fluoroscopy- or ultrasound-guided intra-articular injection of dilute iodinated contrast performed first (sterile technique)
• Typical injectate volumes: shoulder 10-15 mL, hip 10-14 mL, knee 20-40 mL, wrist 3-5 mL, elbow 6-10 mL, ankle 6-12 mL of ~50% diluted 300 mgI/mL contrast
• Move the joint through range of motion after injection to distribute contrast
• Scan PROMPTLY (within ~30 min) before contrast absorbs and delineation fades

Contrast

Technique

• If a partial or total joint replacement is present: acquire a PRE-injection CT first as the baseline, then the arthrogram CT
• Thin isotropic acquisition (0.5-1 mm), bone AND soft-tissue algorithms, multiplanar reformats aligned to the joint
• Tight DFOV on the injected joint (wrist ~7-10 cm, shoulder ~14-16 cm) — the intra-articular contrast is the region of interest
• MAR recon when hardware present
• Note: arthroplasty 3D-planning CTs are a different exam — most vendors reject studies containing intra-articular contrast

Series / Sequences

Key points

• Contrast outlines what MRI shows intrinsically: a defect filling with dense contrast (labral detachment, TFCC perforation, cartilage fissure) is the positive finding
• Timing matters — image within ~30 minutes of injection
• The pre-injection baseline scan is mandatory around arthroplasty (distinguishes injected contrast from pre-existing density; documents component position)
• For the injection itself see the fluoroscopic Arthrogram protocol

References