Wrist protocol (MRI)

The MRI wrist protocol encompasses a set of MRI sequences for the routine assessment of the wrist joint.

Note: This article aims to frame a general concept of an MRI protocol for the assessment of the wrist. Protocol specifics will vary depending on MRI scanner type, specific hardware and software, radiologist and perhaps referrer preference, patient factors e.g. implants, specific indications and time constraints

Indications

Typical indications include radial- or ulnar sided wrist pain decreased range of motion a lump or nerve-related pathologies including:

• scaphoid fracture, scaphoid non-union

• scapholunate dissociation

• carpal instability

• triangular fibrocartilage complex (TFCC) injury

• ulnar-sided wrist impaction and impingement syndromes

• De Quervain tenosynovitis 

• intersection syndrome, distal intersection syndrome

• carpal tunnel syndrome

• Guyon’s canal syndrome

1.5 vs 3 tesla

Musculoskeletal examinations are generally done on both 1.5 and 3 tesla. In particular, the examination of the wrist profits from the improved spatial and contrast resolution of 3 tesla. Postoperative examinations in patients with metallic implants, however, should be done on 1.5 tesla with a metal artifact reduction sequence.

Patient positioning

There are several options:

• the patient in a prone position with the arm in an overhead and elevated position and the elbow joint in pronation (superman position)

• the patient is supine with the arm adducted close to the hip in mild supination

A disadvantage of the superman position is that it is uncomfortable for the patient and possible advantages in fat saturation due to the wrist being in the center of the magnet might be mitigated by movement artefacts.

The hand of the patient should be positioned with the middle finger being in axis with the forearm.

Technical parameters

Coil

Multi-phased array coils are recommended.

• flexible small extremity coil

Scan geometry

• in-plane spatial resolution: ≤0.3 x 0.3 mm

• field of view (FOV): 80-120 mm

• slice thickness: ≤3 mm to ≤2 mm depending on the plane

Planning

• axial images:

  • angulation: perpendicular to the forearm-3rd metacarpal axis and fairly parallel to the radiocarpal joint

  • volume: depends on the specific question

  • slice thickness: ≤3 mm with a gap of 10%

• coronal images:             

  • angulation:  parallel to the forearm and metacarpal bones

  • volume: entire wrist from the skin to skin

  • slice thickness: ≤2,5 mm without a gap

• sagittal images:

  • angulation: in the axis of the forearm and the 3rd metacarpal bone, perpendicular to the coronal images and the radiocarpal joint

  • volume: includes the radiocarpal joint and the carpal bones

  • slice thickness: ≤2,5 mm with a gap of 10%

• 3D images (optional)

  • angulation: coronal

  • spatial resolution: isotropic ≤0.7 mm

• axial oblique images*: to depict the lunotriquetral ligament anatomy

• double oblique coronal-sagittal images*: for better depiction of the scaphoid bone

Sequences

The mainstay in musculoskeletal imaging is the use of water-sensitive sequences, this can be achieved with conventional STIR or fat-saturated images or with intermediate-weighted images.

At least one T1-weighted sequence should be included to ease the assessment and interpretation of bone marrow and/or soft tissue lesions.

Standard sequences

• intermediate-weighted (fat-saturated)​

  • purpose: bone and/or soft-tissue characterization and detailed anatomy of radiocarpal and intercarpal ligaments as well as the triangular fibrocartilage complex

  • technique: IM fast spin echo

  • planes: coronal, axial, sagittal* (option e.g. scaphoid fracture/non-union or tendinopathy)

• T1 weighted

  • purpose: bone and/or soft-tissue characterization

  • technique:  T1 fast spin echo

  • planes: coronal, axial* (option in nerve-related disorders or tumors)

Optional sequences

• T2 weighted

  • purpose: bone and/or soft-tissue characterization, in particular in tumors or nerve disorders

  • technique: T2 FS fast spin echo

  • planes: sagittal* (optional)

• 3D images

  • purpose: suspected scapholunate or lunotriquetral dissociation, triangular fibrocartilage complex injury, chondropathy

  • technique:  3D GRE

  • acquisition plane: coronal – sagittal and oblique multiplanar reconstructions

• T1 weighted C+ (fat-saturated)

  • purpose: for better characterization of ligament and TFCC injury, in case of a suspected tumor, inflammatory conditions or nerve-related disorders

  • technique:  T1 fast spin echo

  • planes: coronal, sagittal, axial depending on the pathology

(*) indicates optional planes

Practical points

• the protocol can and should be tailored to the specific indication or clinical question

• there are however few indications like an acute trauma or the depiction of a wrist ganglion, where contrast media is not necessary

• in the case of suspected De Quervain tenosynovitis, or  intersection syndrome the coronal and sagittal images might require an increased field of view towards the forearm, and the axial stack might need to be increased in that direction to picture the location of the first and second extensor compartment intersection

• the examination will benefit if every plane is imaged

• a typical noncontrast protocol will contain 4-5 sequences