Elbow protocol (MRI)

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

Note: This article aims to frame a general concept of an MRI protocol for the assessment of the elbow joint. 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 elbow pain, decreased range of motion or nerve-related pathologies as in:

1.5 vs 3 tesla

Musculoskeletal examinations are generally done on both 1.5 and 3 tesla. They profit 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 metal artifact reduction sequence.

Patient positioning

There are several options:

  • the patient is prone with the arm in elevation and pronation of the elbow joint (superman position)
  • the patient is supine with the arm close to the body and full supination
  • elbow in flexion, abduction and supination (FABS position)

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): 120-160 mm
  • slice thickness: ≤3 mm or ≤2.5 mm depending on the plane
Planning

A typical MRI of the elbow joint might look like as follows:

  • axial images:
    • angulation: parallel to the humero-radioulnar joint and perpendicular to the humeral-radio-ulnar axis
    • volume: includes distal humeral metaphysis above the epicondyles to the radial tuberosity
    • slice thickness: ≤3 mm with a gap of 10%
  • coronal images:             
    • angulation:  parallel to the intercondylar axis 
    • volume: entire elbow from skin to skin
    • slice thickness: ≤2.5 mm without a gap
  • sagittal images:
    • angulation: perpendicular to the intercondylar axis 
    • slice thickness: ≤2.5 mm with a gap of 10%
    • volume: including the lateral and medial epicondyle
  • coronal oblique images*:
    • angulation: parallel to the distal biceps tendon from the biceps belly to the radial tuberosity
    • volume: distal biceps tendon about in thickness of a biceps belly (10-12 slices)
    • slice thickness: ≤2.5 mm without a gap

Coronal oblique images might be performed for the evaluation of distal biceps tendon pathology with the arm in a non-FABS position.

Sequences

The mainstay in musculoskeletal imaging are 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 or for the delineation of nerve tracts.

Standard sequences

Most indications for an MRI of the elbow joint do not require any contrast media:

  • intermediate-weighted (fat-saturated)
  • T1-weighted
    • purpose: bone and/or soft-tissue characterization, for the delineation of ulnar, median and radial nerve tracts
    • technique:  T1 fast spin echo
    • planes: coronal, axial (optional for nerve tract delineation)
  • T2-weighted
    • purpose: bone and/or soft-tissue characterization, in particular in tumors or nerve disorders
    • technique: T2 fast spin echo
    • planes: axial
Optional sequences

Some indications might benefit from an application of contrast media as e.g. nerve-related issues, tumors or inflammatory disease

  • T1-weighted C+ (fat-saturated)
    • technique:  T1 fast spin echo
    • purpose: for inflammatory  conditions,  in case of suspected tumor or nerve-related disorders
    • planes: coronal, axial, sagittal

(*) indicates optional planes

Practical points

  • a disadvantage of the superman position is that it is uncomfortable for the patient and possible advantages in fat saturation due to the elbow being in the center of the magnet might be mitigated by movement artifacts
  • the FABS (flexion, abduction, and supination) position can be performed for assessment of the distal biceps tendon
  • an alternative to the FABS position for the distal biceps tendon assessment are additional coronal oblique images angulated onto the distal biceps tendon course
  • the protocol can and should be tailored to the specific indication or clinical question
  • the examination will benefit if every plane is imaged
  • a typical native protocol will contain 4-5 sequences