Baker's Cyst

Preliminary Diagnosis: Baker's cyst

I. What imaging technique is first-line for this diagnosis?

Ultrasound (gray scale and color Doppler imaging)

II. Describe the advantages and disadvantages of this technique for diagnosis of Baker's cyst.

Advantages

• Diagnostic for baker's cyst

• Safe, cost-effective, fast, and readily available method

• Can also evaluate for cyst complications (rupture, synovitis), as well as for other causes of the patient’s symptoms, such as other popliteal masses (popliteal artery aneurysm) and deep venous thrombosis of the leg

Disadvantages

• Less accurate for small cysts (often asymptomatic)

• Operator-dependent imaging technique

III. What are the contraindications for the first-line imaging technique?

There are no contraindications for ultrasound.

IV. What alternative imaging techniques are available?

• MRI

• CT

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of Baker's cyst.

MRI

Advantages

• Diagnostic for baker's cyst

• Can detect cyst complications (rupture, synovitis), as well as other possible causes of the patient’s symptoms, such as other popliteal masses (popliteal artery aneurysm), and the presence of other internal derangements of the knee joint (often associated with baker's cyst)

• Does not include exposure to ionizing radiation

• Increasingly available imaging method, covered by most insurance companies

Disadvantages

• Expensive

• Time consuming

• Requires patient cooperation and the images are susceptible to motion artifact. Uncooperative patients may need sedation.

• Closed bore magnets may be uncomfortable for claustrophobic and obese patients.

CT

Advantages

• Does not involve magnetic field, representing a suitable method for patients with formal contraindications to MRI and no access to ultrasound

Disadvantages

• Includes exposure to ionizing radiation

• CT provides suboptimal musculoskeletal soft tissue evaluation, with lower contrast and resolution compared with MRI.

• May require additional evaluation

VI. What are the contraindications for the alternative imaging techniques?

MRI

• Formal contraindications for MRI include (1) patients with non-MRI-compatible implanted electronic devices, such as pacemakers, defibrillators, and nerve stimulators, which may be damaged by the magnetic field; (b) patients with non-MR-compatible clips, implants, or foreign bodies, especially older aneurysm clips and cochlear implants, which may move when placed in the magnetic field.

• MRI is also relatively contraindicated in pregnant women within the first trimester, due to the lack of studies regarding the effect of the magnetic field on the embryo.

CT

• CT is contraindicated in pregnant women, especially within the first and second trimesters.