MRI Knee
Common Indications for MRI of the Knee
- Meniscal disorders: nondisplaced and displaced tears, discoid menisci, meniscal cysts
- Marrow abnormalities: avascular necrosis, marrow oedema syndromes, and stress fractures
- Congenital and developmental conditions: blount disease, dysplasia, normal variants
- Synovial based disorders: symptomatic plicae, synovitis ,bursitis, and popliteal cysts
- Muscle and tendon disorders: strains, partial and complete tears, tendonitis, tendonopathy.
- Mechanical knee symptoms: catching, locking, snapping, crepitus
- Vascular conditions: entrapment, aneurysm, stenosis, occlusion
- Neoplasms of bone, joint or soft tissue
- Infections of bone, joint or soft tissue
- Ligament tears: cruciate, collateral, retinacular
- Osteochondral and articular cartilage infractions
- Osteochondral fractures
- Osteochondritis
- Degenerative chondrosis
- Chondromalacia
- Acute trauma
- Fractures
Please check our new video tutorial for protocols and planning
Contraindications
- Any electrically, magnetically or mechanically activated implant (e.g. cardiac pacemaker, insulin pump biostimulator, neurostimulator, cochlear implant, and hearing aids)
- Intracranial aneurysm clips (unless made of titanium)
- Pregnancy (risk vs benefit ratio to be assessed)
- Ferromagnetic surgical clips or staples
- Metallic foreign body in the eye
- Metal shrapnel or bullet
Patient preparation for MRI Knee
- A satisfactory written consent form must be taken from the patient before entering the scanner room
- Ask the patient to remove all metal object including keys, coins, wallet, any cards with magnetic strips, jewellery, hearing aid and hairpins
- If possible provide a chaperone for claustrophobic patients (e.g. relative or staff)
- Offer earplugs or headphones, possibly with music for extra comfort
- Explain the procedure to the patient
- Instruct the patient to keep still
- Note the weight of the patient
Positioning for MRI Knee
- Feet first supine
- Position the knee in the knee coil and immobilise with cushions
- Give cushions under the ankle for extra comfort
- Centre the laser beam localiser over the lower border of patella
Recommended MRI Knee Protocols, Parameters, and Planning
Knee localiser
A three-plane localizer must be taken at the beginning to localize and plan the sequences. Localizers are usually T1-weighted low-resolution scans that last less than 25 seconds.
PD fat sat axial 3mm
Plan the axial slices on the coronal plane, angling the Planning block parallel to the medial and lateral condyle of the femur. Verify the Planning block in the other two planes. Provide an appropriate angle in the sagittal plane, perpendicular to the line of the femur and tibia. Ensure that the slices adequately cover the knee joint from the tibial tuberosity up to the superior border of the patella. The phase direction in the axial scans should be from right to left to minimize artifacts caused by popliteal artery pulsation. To further reduce arterial pulsation artifacts, consider using saturation bands above and below the axial block.
Protocol Parameters
TR 3000-4000 | TE 15-20 | SLICE 3 MM | FLIP 130-150 | PHASE R>L | MATRIX 320X320 | FOV 150-160 | GAP 10% | NEX(AVRAGE) 2 |
PD fat sat coronal 2mm
Plan the coronal slices on the axial plane, angling the Planning block parallel to the medial and lateral condyle of the femur. Check the Planning block in the other two planes. An appropriate angle must be given in the sagittal plane, parallel to the midline of the femur and tibia. Slices should sufficiently cover the entire knee joint from anterior to posterior. The phase direction in the axial scans should be head to feet to minimize artifacts from popliteal artery pulsation. Utilizing saturation bands above and below the coronal block will further reduce arterial pulsation artifacts.
Parameters
TR 4000-5000 | TE 15-20 | SLICE 2 MM | FLIP 130-150 | PHASE R>L | MATRIX 304X288 | FOV 160-170 | GAP 10% | NEX(AVERAGE) 2 |
T1 tse sagittal 2mm
Plan the sagittal slices on the axial plane; angle the Planning block parallel to the lateral condyle of the femur (parallel to the anterior cruciate ligament). Check the Planning block in the other two planes. An appropriate angle must be given in the coronal plane (parallel to the midline of the femur and tibia). Slices must be sufficient to cover the knee joint from right to left. The phase direction in the axial scans must be head to feet to avoid artifacts from popliteal artery pulsation. Using saturation bands above and below the sagittal block will further reduce arterial pulsation artifacts.
Parameters
TR 400-600 | TE 15-25 | SLICE 2 MM | FLIP 130 | PHASE H>F | MATRIX 320X320 | FOV 160-170 | GAP 10% | NEX(AVERAGE) 2 |
T2 STIR sagittal 2mm
Plan the sagittal slices on the axial plane; angle the Planning block parallel to the lateral condyle of the femur (parallel to the anterior cruciate ligament). Check the Planning block in the other two planes. An appropriate angle must be given in the coronal plane (parallel to the midline of the femur and tibia). Slices must be sufficient to cover the knee joint from right to left. The phase direction in the axial scans must be head to feet to avoid artifacts from popliteal artery pulsation. Using saturation bands above and below the sagittal block will further reduce arterial pulsation artifacts.
Parameters
TR 4000-5000 | TE 110 | FLIP 130 | NEX 2 | SLICE 2MM | MATRIX 256X256 | FOV 160-170 | PHASE H>F | GAP 10% | TI 130 |
T2*(MEDIC) sagittal 2mm
Plan the sagittal slices on the axial plane; angle the Planning block parallel to the lateral condyle of the femur (parallel to the anterior cruciate ligament). Check the Planning block in the other two planes. An appropriate angle must be given in the coronal plane (parallel to the midline of the femur and tibia). Slices must be sufficient to cover the knee joint from right to left. The phase direction in the axial scans must be head to feet to avoid artifacts from popliteal artery pulsation. Using saturation bands above and below the sagittal block will further reduce arterial pulsation artifacts.
Parameters
TR 800-1200 | TE 15-25 | FLIP 30 | NEX 2 | SLICE 3 MM | MATRIX 256X256 | FOV 160-170 | PHASE H>F | GAP 10% | oversample 50% |
PD fat sat coronal oblique 1.5mm for Anterior cruciate ligament
Plan the coronal oblique slices on the sagittal plane and angle the Planning block parallel to the anterior cruciate ligament (ACL). Check the Planning block in the other two planes. An appropriate angle must be given in the coronal plane, parallel to the medial and lateral condyle of the femur. The slices should be sufficient to cover the ACL. The phase direction for these coronal oblique scans should be right to left to avoid pulsation artifacts from the popliteal artery. Applying saturation bands above and below the coronal block will further reduce arterial pulsation artifacts.
Parameters
TR 3000-4000 | TE 15-20 | SLICE 1.5 MM | FLIP 130-150 | PHASE R>L | MATRIX 256X256 | FOV 140-150 | GAP 10% | NEX(AVERAGE) 4 |
PD fat sat sagittal oblique 1.5mm for ACL
Plan the sagittal oblique slices on the axial plane, angling the Planning block parallel to the ACL. Check the Planning block in the other two planes to ensure accuracy. In the coronal plane, an appropriate angle parallel to the ACL must be determined. The slices should sufficiently cover the ACL. For the sagittal oblique scans, the phase direction should be head to feet to minimize pulsation artifacts from the popliteal artery. Applying saturation bands above and below the coronal block will further reduce arterial pulsation artifacts.
Parameters
TR 3000-4000 | TE 15-20 | SLICE 1.5 MM | FLIP 130-150 | PHASE H>F | MATRIX 256X256 | FOV 140-150 | GAP 10% | NEX(AVERAGE) 4 |