Sports Medicine: Just the Facts

CHAPTER 43 • MAGNETIC RESONANCE IMAGING: TECHNICAL CONSIDERATIONS AND UPPER EXTREMITY 261

for imaging the elbow vary, but most authors agree on

a volumetric gradient echo coronal sequence to evalu-

ate the major ligamentous stabilizers and tendons

about the elbow (Decker and Potter, 1998; Steinbach

et al, 1997; Fritz et al, 1997).

• Medial elbow pain, typically encountered in throwing
  athletes from repetitive valgus stress, is often as a result
  of injury to the medial collateral ligament, which can be
  seen to best advantage on high resolution three dimen-
  sional volumetrically acquired gradient echo sequences
  (Gaary, Potter, and Altchek, 1997) (Fig. 43-4).


• Posteromedial impingement, with osteophyte forma-
  tion about the humeral-ulnar joint, also often encoun-
  tered with chronic repetitive valgus stress and overuse
  throwing injuries, can be imaged with MR (Gaary,
  Potter, and Altchek, 1997), often demonstrating subtle
  proliferative change and cartilage wear before any
  findings are apparent on conventional radiographs.


• Posterolateral rotatory instability, resulting from laxity
  of the ulnar band of the lateral collateral ligament, with
  an intact annular ligament (O’Driscoll, Bell, and
  Morrey, 1991) can be diagnosed prospectively with
  high resolution MR images (Potter et al, 1997).


• MR is especially useful in diagnosing osteochondral
  injuries of the elbow (osteochondritis dissecans) and
  localizing potential intraarticular cartilage fragments.
  MR provides more information as to the behavior of
  the osteochondral lesion than conventional radi-
  ographs or computed tomography(CT). In addition to
  identifying the abnormality as well as possible intra-
  articular fragments, identification of high signal
  (fluid) tracking about an osteochondral lesion sug-
  gests an unstable fragment.

WRIST AND HAND

• Common indications for MR imaging of the hand and
  wrist are for evaluating triangular fibrocartilage com-
  plex (TFCC) lesions, intercarpal ligamentous injuries,
  and possible ganglion cysts.


• Both the extrinsic as well as the intrinsic ligaments of
  the wrist can be evaluated with high resolution MR
  imaging (Rominger et al, 1993).


• The TFCC is composed of multiple structures, includ-
  ing the articular disk, the ulnar collateral ligament, the
  volar and dorsal radioulnar ligaments, the extensor
  carpi ulnaris tendon sheath, and the ulnolunate and
  ulnotriquetral ligaments (Palmer and Werner, 1981).


• High resolution MR imaging can be used not only to
  identify TFCC tears but can further classify abnormal-
  ities as radial or ulnar sided avulsions, central tears,
  degenerative tears as well as degenerative changes,
  thus appropriately directing treatment, possibly to

include arthroscopy (Potter et al, 1997). The articular

disk and supporting ligamentous structures are low

signal intensity on all pulse sequences.

• The interosseous scapholunate ligament has a variable
  appearance at MR imaging depending on the level of the
  wrist one is imaging. It has been demonstrated that the
  more volar portion of the scapholunate ligament is
  somewhat more patulous and hyperintense than the
  dorsal aspect, suspected to be due to the higher concen-
  tration of loose connective tissue in the palmar aspect of
  the ligament; the higher concentration of collagen in the
  more dorsal fibers result in a more uniform low signal
  intensity appearance (Totterman and Miller, 1996).


• Carpal bone fractures, often nonvisualized on conven-
  tional radiographs, can be clearly seen with a water-
  sensitive pulse sequence, such as inversion recovery
  MR imaging.
  •Cartilage-sensitive pulse sequences can evaluate the
  articular cartilage in the radiocarpal, intercarpal, and
  carpometacarpal joint spaces, identifying abnormali-
  ties before secondary changes of joint space narrow-
  ing and subchondral sclerosis appear on conventional
  radiographs.


• The carpal tunnel can be evaluated with dedicated MR
  of the wrist. The median nerve is seen as a tubular
  intermediate signal intensity structure with fine inter-
  nal linear fascicles amidst the hypointense flexor ten-
  dons. Mass lesion such as a ganglion cyst in the carpal
  tunnel causing compression of the median nerve can
  be visualized.


• The contents of the carpal tunnel, clearly seen on axial
  images through the wrist, include the eight superficial
  and deep flexor tendons, the median nerve and the
  flexor pollicus longus tendon.
  •Repetitive overuse injuries in the adolescent can result
  in abnormalities of the physes about the wrist (espe-
  cially in gymnasts) such as early closure (Shih et al,
  1995; Liebling et al, 1995). A dedicated MR physeal
  pulse sequence can provide exquisite anatomic infor-
  mation about the status of the physis compared with
  conventional radiographs or CT.


• Ulnar impaction syndrome is a clinical entity with
  positive ulnar variance and degenerative changes
  along the ulnar side of the wrist, primarily involving
  the lunate, triquetrum and distal ulna (Escobedo,
  Bergman, and Hunter, 1995; Cerezal et al, 2002).
  Edema, subchondral cystic change and sclerosis can
  be seen, resulting from altered load-bearing across the
  ulnar side of the wrist. MR imaging can demonstrate
  findings in the early stages, observing signs of lunate
  chondromalacia, and thus can direct treatment (poten-
  tial ulnar shortening).


• In the finger, high resolution, small dedicated surface
  coils are needed to achieve adequate resolution.