High Yield Overview
Arthrography Techniques
Joint Contrast Imaging for Orthopaedics
DirectIntra-articular Injection
Gd-DTPAMRA Contrast
IodineCTA Contrast
15-20mLShoulder Volume
Arthrography Methods
Direct MRA
PatternIntra-articular dilute Gd + MRI
TreatmentBest for labrum, soft tissue detail
Direct CTA
PatternIntra-articular iodine + CT
TreatmentPost-surgery, bone detail, loose bodies
Indirect MRA
PatternIV Gd + delayed MRI
TreatmentLess invasive, cartilage assessment
Fluoroscopic arthrography
PatternContrast + real-time fluoro
TreatmentJoint assessment during injection
Critical Must-Knows
- Direct MR arthrography: Dilute gadolinium injected into joint → T1-weighted MRI. Best for labral tears.
- Direct CT arthrography: Iodinated contrast injected → CT scan. Best post-surgery, for loose bodies, bone detail.
- Indirect arthrography: IV gadolinium → diffuses into joint. Less invasive but inconsistent distension.
- Joint distension: Contrast separates structures for visualization (labrum from capsule, cartilage surfaces).
- Post-surgical joints: CT arthrography often superior (less metal artifact than MRI).
Examiner's Pearls
- "MRA is superior for labral tears (sensitivity 90%+ vs 70% non-contrast MRI).
- "CTA is preferred post-shoulder surgery (less artifact from anchors).
- "Paralabral cysts indicate underlying labral tear.
- "Exercise after indirect MRA improves contrast diffusion into joint.
- "Shoulder MRA: ABER position (abduction external rotation) opens anteroinferior capsule.
Clinical Imaging
Imaging Gallery
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Arthrography Contrast Considerations
For MR arthrography, gadolinium is diluted (approximately 1:200) to avoid T2 shortening artifact. For CT arthrography, use iodinated contrast (not gadolinium). Always confirm no contrast allergy. Infection is a contraindication to elective arthrography.
Arthrography Principles
Why Arthrography
Joint distension with contrast provides:
- Separation of intra-articular structures (labrum from capsule)
- Outline of cartilage surfaces
- Detection of communication with bursae/cysts
- Visualization of loose bodies
- Detection of capsular/ligament tears (contrast extravasation)
Non-contrast vs Arthrography
Non-contrast MRI vs MR Arthrography
| Feature | Non-contrast MRI | MR Arthrography |
|---|---|---|
| Labral tears | Sensitivity 70-80% | Sensitivity 90%+ |
| SLAP lesions | Often missed | Much better detection |
| Capsular structures | Collapsed, difficult to assess | Distended, well visualized |
| Cartilage detail | Good for surface lesions | Better for delamination/flaps |
| Loose bodies | May miss small bodies | Outlined by contrast |
| Invasiveness | Non-invasive | Requires injection |
Direct Arthrography
MR Arthrography (Direct)
Technique
Contrast preparation:
- Gadolinium diluted approximately 1:200 with saline
- Final concentration approximately 2 mmol/L
- Additional local anesthetic and/or steroid often added
Injection volumes:
- Shoulder: 12-15 mL
- Hip: 10-15 mL
- Wrist: 3-4 mL
- Ankle: 5-8 mL
Imaging:
- Scan within 30-45 minutes of injection
- T1-weighted sequences primary (Gd shortens T1 → bright)
- Fat-suppressed T1 (T1 FS) highlights contrast
- T2/PD sequences also obtained
MRA Sequences
MR Arthrography Sequences
| Sequence | Appearance of Contrast | Best For |
|---|---|---|
| T1-weighted | Bright (high signal) | Anatomy, labral outline |
| T1 Fat-Sat | Bright on dark background | Labral tears, cartilage defects |
| T2-weighted | Intermediate-dark | Bone marrow edema, soft tissue |
| PD Fat-Sat | Variable | Cartilage, complementary assessment |
CT Arthrography (Direct)
Technique
Contrast:
- Iodinated contrast (same as IV CT contrast)
- May be diluted 1:1 with saline or used full strength
- Do NOT use gadolinium for CTA
Advantages over MRA:
- Superior spatial resolution for bone detail
- Less affected by metal artifact (post-surgery)
- Faster scan time
- Better for claustrophobic patients
Disadvantages:
- Radiation exposure
- Less soft tissue contrast than MRI
- Cannot assess bone marrow
When to Choose CTA over MRA
Prefer CT Arthrography
- Post-surgical assessment (less artifact)
- Suture anchors, screws present
- Suspected loose bodies
- Osseous Bankart assessment
- MRI contraindicated
- Claustrophobia
Prefer MR Arthrography
- Primary labral tear assessment
- Soft tissue detail required
- Cartilage assessment
- No prior surgery
- Avoid radiation (young patients)
- Bone marrow assessment needed
Indirect Arthrography
Indirect MR Arthrography
Technique
Method:
- IV gadolinium injection (standard MRI dose)
- Wait 10-20 minutes
- Exercise the joint during wait period
- MRI scan
Mechanism:
- Gadolinium diffuses from blood into synovial fluid
- Enhanced synovium produces contrast-enhanced effusion
Advantages:
- Non-invasive (no joint puncture)
- Can image multiple joints
Disadvantages:
- Less reliable joint distension
- Variable contrast concentration
- Less sensitive than direct MRA
Comparison of Methods
Direct vs Indirect Arthrography
| Feature | Direct | Indirect |
|---|---|---|
| Joint distension | Controlled, reliable | Variable, often minimal |
| Contrast concentration | Consistent, optimized | Variable |
| Sensitivity for labral tears | Higher (90%+) | Lower (70-80%) |
| Invasiveness | Requires injection | IV only |
| Time to imaging | 30-45 min | 15-30 min post-IV |
| Cartilage assessment | Excellent | Good (delayed imaging) |
Regional Applications
Shoulder Arthrography
Primary indications:
- Suspected labral tear (Bankart, SLAP)
- Recurrent instability assessment
- Partial rotator cuff tears (articular surface)
- Suspected loose bodies
- Adhesive capsulitis (reduced joint volume)
- Post-surgical assessment (re-tear, anchor position)
Hip Arthrography
Hip MR Arthrography
Indications:
- Labral tears (femoroacetabular impingement)
- Cartilage assessment
- Loose bodies
- Ligamentum teres pathology
Technique:
- Fluoroscopy or ultrasound guided injection
- Anterolateral approach to femoral neck
- Volume: 10-15 mL
Key findings:
- Labral tear: Contrast undercutting or within labrum
- Cartilage delamination: Contrast beneath cartilage
- Paralabral cyst: Indicates labral tear
Wrist Arthrography
Wrist Arthrography
Indications:
- TFCC tears
- Intercarpal ligament tears (SL, LT)
- Loose bodies
- Capsular injury
Technique:
- Radiocarpal joint injection (most common)
- May add midcarpal and DRUJ injection for complete assessment
- Volume: 3-4 mL per compartment
Key findings:
- TFCC tear: Contrast from radiocarpal to DRUJ
- SL ligament tear: Contrast from radiocarpal to midcarpal
- LT ligament tear: Contrast into midcarpal compartment
Note: Some communication exists normally; correlate with symptoms
Ankle Arthrography
Ankle MR Arthrography
Indications:
- Osteochondral lesions of talus (cartilage detail)
- Loose bodies
- Ligament assessment (less common indication)
- Synovitis evaluation
Technique:
- Anteromedial or anterolateral approach
- Volume: 5-8 mL
Findings:
- OCD: Fluid undermining cartilage = unstable
- Loose bodies outlined by contrast
Interpretation Principles
Signs of Labral Tears
Mnemonic
CUTSLabral Tear MRA Signs
C
Contrast Extension
Contrast extending into or under labrum
U
Undercutting
Contrast between labrum and glenoid/acetabulum
T
Tear/Irregularity
Disrupted labral contour, fraying
S
Signal Change
Abnormal signal within labrum (also on non-contrast)
Memory Hook:Contrast CUTS through torn labrum
Associated Findings
Paralabral Cyst
- Cystic collection adjacent to labrum
- Indicates labral tear with one-way valve
- Can cause nerve compression (suprascapular, obturator)
- Treat labral tear, not just cyst
Contrast Extravasation
- Contrast outside expected joint capsule
- Indicates capsular/ligament tear
- Subscapularis bursa communication (normal)
- Distinguish normal recesses from pathology
Cartilage Assessment
Cartilage Lesion Grading (Modified Outerbridge)
| Grade | Arthrography Appearance | Significance |
|---|---|---|
| Grade I | Softening (not visible on imaging) | Mild |
| Grade II | Fissures not reaching bone, less than 50% depth | Moderate |
| Grade III | Fissures more than 50% depth, flaps, contrast undermining | Significant |
| Grade IV | Full-thickness defect, bone exposed | Severe |
Complications & Safety
Complications
Arthrography Complications
| Complication | Incidence | Prevention/Management |
|---|---|---|
| Infection (septic arthritis) | Rare (0.01-0.1%) | Sterile technique, avoid if skin infection |
| Allergic reaction | Rare | Gadolinium safer than iodinated; check history |
| Vasovagal reaction | 1-2% | Position supine, reassurance, atropine if severe |
| Post-procedure pain | Common | Resolves 24-48 hours, analgesia |
| Failed injection | Occasional | Confirm with contrast spread, reposition if needed |
Contraindications
Absolute Contraindications
- Active joint infection
- Known severe contrast allergy (consider alternative)
- Overlying skin infection at injection site
- Uncorrected coagulopathy
Relative Contraindications
- Anticoagulation (may need to hold/bridge)
- Prior contrast reaction (premedicate)
- Pregnancy (MRA may be acceptable, avoid CTA)
- Joint prosthesis (technically challenging)
Gadolinium Dilution for MRA
For MR arthrography, gadolinium MUST be diluted (approximately 1:200). Concentrated gadolinium causes T2 shortening artifact appearing as signal void. Standard dilution: 0.1 mL gadolinium in 20 mL saline ± local anesthetic.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
Shoulder MRA vs CTA
EXAMINER
"A 28-year-old has recurrent shoulder instability after previous arthroscopic Bankart repair with suture anchors. What imaging would you request?"
EXCEPTIONAL ANSWER
For this post-surgical patient with metallic suture anchors, I would request CT arthrography rather than MR arthrography. The metal anchors will cause significant susceptibility artifact on MRI, degrading visualization of the repaired labrum and capsule. CT has much less metal artifact and provides excellent bone detail to assess anchor position, bony Bankart lesion healing, and glenoid bone loss. CTA with iodinated contrast will distend the joint, allowing assessment of the labral repair integrity - contrast tracking under the labrum suggests re-tear. I would also request 3D CT reconstruction to quantify any glenoid bone loss using the best-fit circle method, which is important for surgical planning if revision is considered. If there were no metallic implants, MR arthrography would be preferred for its superior soft tissue contrast, but in the post-surgical shoulder with anchors, CTA is the modality of choice.
KEY POINTS TO SCORE
Metal artifact worse on MRI than CT
CTA preferred post-surgery with anchors
CTA shows anchor position, bone healing
3D CT for glenoid bone loss quantification
COMMON TRAPS
✗Ordering MRI despite metal implants
✗Forgetting to request 3D reconstruction
✗Not mentioning contrast injection technique
LIKELY FOLLOW-UPS
"What percentage glenoid bone loss is significant?"
"How do you calculate the glenoid bone loss on CT?"
"What is the best-fit circle method?"
VIVA SCENARIOStandard
Labral Tear Assessment
EXAMINER
"What are the MR arthrography findings of a labral tear, and what additional position helps visualize anteroinferior labral tears?"
EXCEPTIONAL ANSWER
On MR arthrography, labral tear findings include: contrast extending into or undermining the labrum (the key finding), labral irregularity or fraying, detachment of the labrum from the glenoid with contrast interposed, and linear high signal within the labral substance. A paralabral cyst is an indirect sign indicating a labral tear with communication. For better visualization of anteroinferior labral tears (Bankart lesions), we use the ABER position - Abduction and External Rotation. In this position, the arm is placed behind the head, which tensions the anterior band of the inferior glenohumeral ligament and opens up the anteroinferior joint capsule. This stretches the anteroinferior labrum away from the glenoid, making small tears more conspicuous by allowing contrast to track into them. ABER images are typically acquired in the axial oblique plane and are particularly valuable for detecting subtle peel-back SLAP lesions and Bankart variants.
KEY POINTS TO SCORE
Contrast undercutting or within labrum = tear
Paralabral cyst indicates underlying labral tear
ABER = Abduction External Rotation position
ABER opens anteroinferior capsule, improves tear detection
COMMON TRAPS
✗Forgetting to mention ABER position
✗Not describing contrast behavior at tear site
✗Missing indirect signs like paralabral cyst
LIKELY FOLLOW-UPS
"What is a Perthes lesion?"
"How do you differentiate a sublabral recess from a SLAP tear?"
"What is the sensitivity of non-contrast MRI vs MRA for labral tears?"
VIVA SCENARIOAdvanced
Arthrography Technique
EXAMINER
"Describe the technique for performing a direct MR arthrogram of the shoulder."
EXCEPTIONAL ANSWER
I perform shoulder MR arthrography using an anterior approach to the glenohumeral joint under fluoroscopic guidance. The patient is positioned supine with the arm in slight external rotation. I identify the target - the inferior aspect of the humeral head at the junction with the glenoid, in the rotator interval. After sterile preparation and local anesthetic infiltration, I advance a 22-gauge spinal needle under fluoroscopy into the joint, confirming position with a small amount of iodinated contrast showing articular spread. I then inject 12-15 mL of dilute gadolinium solution - typically 0.1 mL gadolinium diluted in 20 mL saline, giving a final concentration around 2 mmol/L. Local anesthetic can be added. I feel for increasing resistance indicating capsular distension. After injection, the patient is transferred to MRI within 30-45 minutes to prevent contrast resorption. Primary sequences include T1-weighted and T1 fat-saturated images where the contrast appears bright. ABER positioning is added for anteroinferior labral assessment.
KEY POINTS TO SCORE
Anterior approach, rotator interval target
Confirm position with iodinated contrast first
Gadolinium diluted approximately 1:200
Image within 30-45 minutes of injection
COMMON TRAPS
✗Forgetting to confirm needle position before Gd injection
✗Using undiluted gadolinium (causes artifact)
✗Delaying imaging too long (contrast resorption)
LIKELY FOLLOW-UPS
"What volume do you inject in the hip?"
"What are the contraindications to arthrography?"
"When would you use ultrasound guidance instead?"
Arthrography Exam Day Cheat Sheet
High-Yield Exam Summary
Arthrography Types
- •Direct MRA: Intra-articular dilute Gd → MRI
- •Direct CTA: Intra-articular iodine → CT
- •Indirect MRA: IV Gd → diffuses into joint
- •Direct methods give better joint distension
MRA vs CTA Selection
- •MRA: Primary labral assessment, soft tissue
- •CTA: Post-surgery (less metal artifact), bone detail
- •CTA: Suture anchors, screws present
- •MRA: No radiation, bone marrow assessment
Technique Points
- •Gadolinium dilution: approximately 1:200 (2 mmol/L)
- •Shoulder volume: 12-15 mL
- •Image within 30-45 minutes
- •ABER position for anteroinferior labrum
Labral Tear Signs
- •Contrast undercutting labrum
- •Contrast within labral substance
- •Labral detachment/irregularity
- •Paralabral cyst = indirect sign of tear