Forearm MRI : Protocol and Planning
Indications for forearm MRI scan
- Marrow abnormalities (e.g. bone contusions, osteonecrosis, marrow oedema syndromes, and stress fractures)
- Synovial based disorders ( e.g. synovitis, tenosynovitis, bursitis, and ganglion cysts)
- Infections of bone, joint, or soft tissue (eg. osteomyelitis, osteo arthritis )
- Neoplasms of bone, joint or soft tissue
- Avascular necrosis
- Nerve Impingement
- Fractures in children
- Soft-tissue masses
- Occult fracture
- Ganglion cyst
- Ligament tear
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 forearm MRI scan
- A satisfactory written consent form must be taken from the patient before entering the scanner room
- Ask the patient to remove all metal objects including keys, coins, wallet, 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 forearm MRI scan
- Position the patient in supine position with head pointing towards the magnet (head first supine)
- Position the patient off-center over the spine coil (in the anatomical position) as demonstrated, and place the body coil or a large flexible coil over the forearm (from elbow to wrist).
- Securely tighten the coil using straps to prevent respiratory artefacts
- Give a pillow under the head and cushions under the legs for extra comfort
- Centre the laser beam localiser over the mid forearm
- Register the patient on the scanner as 'head first supine'
Recommended Forearm MRI Protocols and Planning
forearm MRI localiser
A three-plane localizer must be taken at the beginning to localize and plan the sequences. Localizers are usually less than 25 seconds. T1-weighted low-resolution scans can be used for this purpose. Continue taking additional localizers until a true coronal, axial, and sagittal view of the forearm is obtained.
T2 stir axial 4 mm SFOV
Plan the axial slices on the coronal plane and angle the positioning block perpendicular to the radius and ulna. Check the positioning block in the other two planes. An appropriate angle must be used in the sagittal plane (perpendicular to the radius and ulna). Slices must be sufficient to cover the whole forearm from the wrist joint to the elbow joint.
Parameters
TR 4000-5000 | TE 110 | FLIP 150 | NEX 2 | SLICE 4 MM | MATRIX 256X256 | FOV 150-200 | PHASE A>P | GAP 10% | TI 150 |
T1 tse axial 4 mm SFOV
Plan the axial slices on the coronal plane and angle the positioning block perpendicular to the radius and ulna. Check the positioning block in the other two planes. An appropriate angle must be used in the sagittal plane (perpendicular to the radius and ulna). Slices must be sufficient to cover the whole forearm from the wrist joint to the elbow joint.
Parameters
TR 400-600 | TE 15-25 | SLICE 4 MM | FLIP 150 | PHASE A>P | MATRIX 320X320 | FOV 150-200 | GAP 10% | NEX(AVRAGE) 2 |
T2 stir coronal 3mm
Plan the coronal slices on the axial plane and angle the positioning block parallel to the radius and ulna. Check the positioning block in the other two planes. An appropriate angle must be given in the sagittal plane (parallel to the radius and ulna). Slices must be sufficient to cover the whole forearm from anterior to posterior. Adding a saturation band over the chest and abdominal area will reduce wrap-around and breathing artifacts.
Parameters
TR 4000-5000 | TE 110 | FLIP 150 | NEX 2 | SLICE 3 MM | MATRIX 384X320 | FOV 350-400 | PHASE R>L | GAP 10% | TI 150 |
T1 tse coronal 3mm
Plan the coronal slices on the axial plane and angle the positioning block parallel to the radius and ulna. Check the positioning block in the other two planes. An appropriate angle must be given in the sagittal plane (parallel to the radius and ulna). Slices must be sufficient to cover the whole forearm from anterior to posterior. Adding a saturation band over the chest and abdominal area will reduce wrap-around and breathing artifacts.
Parameters
TR 400-600 | TE 15-25 | SLICE 3 MM | FLIP 150 | PHASE H>F | MATRIX 384X384 | FOV 350-400 | GAP 10% | NXA(AVRAGE) 2 |
T2 tse sagittal 3mm
Plan the sagittal slices on the axial plane; angle the positioning block perpendicular to the medial and lateral epicondyles of the humerus. Check the positioning block in the other two planes. An appropriate angle must be used in the coronal plane (parallel to the ulna). Slices must be sufficient to cover the whole forearm from medial to lateral.
Parameters
TR 3000-4000 | TE 100-120 | SLICE 3 MM | FLIP 130-150 | PHASE A>P | MATRIX 384X384 | FOV 350-400 | GAP 10% | NEX(AVRAGE) 2 |