Musculoskeletal Imaging Guidelines

Musculoskeletal Clinical Imaging Guidelines

• Guidelines are from the Egyptian society of radiology and nuclear medicine
• Created by Maj Gen Prof. Hany Hafez Lofty, head of radiology departments at Maadi Armed Forces compound
• Includes Armed Forces Collage of Medicine

Imaging Modalities

• X-ray (conventional, CR, DR)
• Ultrasound (US)
• Computed Tomography (CT)
• Magnetic Resonance Imaging (MRI)
• Nuclear Medicine (planar, SPECT, PET)
• Hybrid Imaging (SPECT-CT, PET-CT, PET-MRI)
• Imaging-guided intervention (diagnostic/therapeutic)

Imaging Selection

• Soft tissue superficial lesions: Ultrasound (US)
• Soft tissue lesions underlying bone: MRI
• Bony lesions: CT
• Bone marrow: MRI

X-ray (Conventional, CR, DR)

• At least two views are required.

CT

• Coronal and sagittal reformatting plus 3D reconstruction are often needed
• Contraindications for contrast media should be considered if no alternative exists
• Detailed clinical data should be provided to the interpreting radiologist

MRI

• Detailed clinical data should be provided to the radiologist.
• Protocol choices (e.g., discs or blocks) should be left to the radiologist
• Multiple sequence names may vary among companies

Ultrasound (US)

• Real-time, interactive, high-resolution imaging.
• Does not use radiation
• Useful for superficial structures, including ligament, tendon, and nerve pathologies.
• Examination of the contralateral side is beneficial for comparison

Ultrasound (US): Advantages

• High resolution for superficial structures and Doppler scanning
• Real-time interactive imaging
• No radiation to patient or provider
• Exam of the contralateral side for comparison
• Portable
• Relatively inexpensive
• Educational facility (anatomy, technique, interpretation)

Ultrasound (US): Disadvantages

• Limited field of view
• Limited penetration
• Operator dependent (requires expert)
• Cannot penetrate mature adult bone and air

Computed Tomography (CT): Advantages

• Relatively quick imaging
• Minimal patient cooperation is required
• Excellent anatomical detail
• High sensitivity to detect different densities (e.g., air, fat, water, soft tissue, blood, contrast medium, bone).

Computed Tomography (CT): Disadvantages

• Exposure to ionizing radiation
• Risk of contrast-induced nephropathy and allergic reactions

CT: Evolution

• Different generations of CT scanners, including conventional, 3rd generation, 4th generation, spiral, and multi-slice CT.

Conventional CT: Limitations

• Slow scan time, prone to movement artifacts
• Difficulty with reformatting images in different planes
• Limited accuracy in dynamic contrast studies
• Potential for missing small lesions due to slice thickness and respiratory variations

Spiral (Volumetric) Multi-Slice CT: Benefits

• Altered slice thickness without rescanning and reduced exam time (single breath-hold)
• Good control of delay between contrast injection and scan
• Multi-phasic studies with efficient contrast usage

MRI: Advantages

• No radiation exposure
• Variable image sequences
• Direct multiple planes without reformatting
• Excellent imaging for chest wall soft tissue and bone marrow; useful for characterizing mediastinal lesions
• Angiography possible without contrast injection

MRI: Disadvantages

• Longer scan times
• Less readily available
• May not be suitable for certain patient populations (e.g., uncontrolled, pediatric, claustrophobic)
• General anesthesia may be necessary in some cases
• High cost

MRI: High Field vs. Low Field

• High-field MRI scanners use strong magnets (1.5T to 3.0T) and produce high-quality images, but are often closed and may be unsuitable for claustrophobic patients. High-field scanners are often used for research
• Low-field MRI scanners utilize weaker magnets (0.23T to 0.3T) and are commonly open, and useful for patients who are claustrophobic, have weight issues or of concern relative to large sizes. Low-field MRI often requires longer scan times.

Standing/Sitting MRI Scans

• Allow patients to stand or sit, improving patient comfort, making them useful for certain situations

MRI, Disadvantages

• One exam per body part.
• Average Exam time: 15-30 minutes.
• Not patient friendly; Claustrophobia
• High cost
• Multiple sequences (T1, T2, PD, STIR, Gradient)
• Non-standardized imaging techniques
• Metallic or electronic objects

Nuclear Medicine Imaging (SPECT/PET)

• Functional imaging modality, detecting metabolic activity
• SPECT: Creates 3D reformatting of cross-sectional slices

PET (Positron Emission Tomography):

• Tracer emits positrons which results in the production of gamma rays, scanned by detectors, and the data is compiled for 3D reconstruction.
• FDG, naf (bone formation), H20 (blood flow) are markers frequently utilized.

PET: Advantages

• Differentiates necrotic tissue, scar tissue, and inflammatory changes from malignancy; often undifferentiable with anatomical imaging alone
• Detects lymph nodes harboring malignant cells, even if not enlarged
• High negative predictive value, often helpful for ruling-out malignancy

PET: Disadvantages

• Less spatial resolution and high percentage of false positives.
• High costs and significant radiation exposure. May be contraindicated for some special groups (e.g., pediatrics or pregnant)

Nuclear Imaging (Functional)

• PET images the entire body distribution of FDG, which highlights the increased metabolic activity of tumor cells.

Hybrid Imaging (SPECT-CT/PET-CT/PET-MRI)

• These combine the advantages of different modalities
• These systems are used when different views are needed

Imaging-Guided Intervention:

• Diagnostic intervention includes biopsy, fluid aspiration, nerve block, arthrograms, discorams, etc.
• Therapeutic intervention includes intra-articular steroid injection, dry-needling tendons, autologous blood injection, vertebroplasty, osteoid osteoma ablation.