MRI of the Wrist

Marcos Loreto Sampaio, MD; Nicholas M. Kolanko, MD

Disclosures

Appl Radiol. 2014;43(10) 

In This Article

Bones and Cartilage

Occult fractures are detected as linear, low signal intensity on the T1-weighted sequence with surrounding bone marrow edema (Figure 1). Areas of bone contusion are differentiated mainly by the absence of a clear fracture line (Figure 2).[9] Typical areas include the scaphoid, the tubercle of trapezium (radial-sided pain), the hook of the hamate (ulnar/volar-sided pain) and the distal radius.

Figure 1.

Occult fracture. Coronal T1-weighted image demonstrates a band of low signal intensity along the scaphoid waist compatible with an undisplaced fracture line (negative initial x-rays).

Figure 2.

Bone contusion. Axial T2-weighted image with fat suppression. There is bone marrow edema within the tubercle of trapezium (post-fall) and associated edema of the surrounding soft tissues.

Avascular necrosis (AVN) of the lunate (Kienbock's disease) is characterized initially by high signal intensity on fluid sensitive sequences, with low signal intensity on all sequences later in disease progression. A typical coronal plane fracture and bone fragmentation may follow, with further progression of OA changes of the carpus (Figure 3).[10] AVN of the proximal pole of the scaphoid may happen in 30% of scaphoid waist fractures and up to 100% of proximal pole fractures. It may also present initially as nonspecific increased signal intensity on the fluid sensitive sequences. Enhancement with IV contrast is associated with viability of the fragment,[11] while low signal on all sequences (corresponding to sclerosis on radiographs and CT) is compatible with established necrosis (Figure 4).

Figure 3.

Kienbock's disease. (A) Coronal T1-weighted image. The lunate (arrow) is necrotic, with partial collapse and low signal intensity with cystic changes. (B) Associated negative ulnar variance (double arrow).

Figure 4.

Avascular necrosis of the scaphoid. (A) Coronal T1-weighted image. (B) Coronal T2-weighted image with fat suppression. Old scaphoid waist non-united fracture. There is marked low signal intensity of the proximal pole (arrow) compatible with necrosis. Note associated cystic changes of the capitate (*) with severe chondropathy of its proximal margin and joint effusion.

After initial radiographic assessment, ulnar-sided pain with suspected impaction syndromes may be assessed further by MRI, with clear demonstration of the bone anatomy, signal and, eventually, associated internal derangements. Typical findings include:

  1. ulnocarpal abutment syndrome: subchondral bone marrow edema and cystic changes of the ulnar margin of the lunate, triangular fibrocartilage degeneration or tear, frequently with positive ulnar variance (Figure 5);

  2. ulnar styloid impaction syndrome: a prominent ulnar styloid, previous styloid non-union or accessory ossicle, as well as edema and cystic changes in the styloid and triquetrum;

  3. hamatolunate impaction syndrome: a type 2 lunate (anatomical variant lunate defined by a clear articular facet with the hamate), chondropathy and associated subchondral marrow signal alteration (Figure 5); and,

  4. ulnar impingement syndrome: a shortened and radially convergent distal ulna, with signal changes and remodeling at the radio-ulnar interface (Figure 5).[12]

Figure 5.

(A) Ulnocarpal abutment. Coronal PD-weighted image with fat suppression reveals a deep chondral erosion of the ulnar margin of the lunate with subchondral marrow edema, cystic changes and an associated tear of the triangular fibrocartilage (arrow). (B) Hamatolunate impaction. Coronal PD-weighted image with fat suppression. Lunate type II. Mild hamate subchondral bone marrow signal changes related to chondropathy. Note also a tear of the triangular fibrocartilage (*). (C) Ulnar impingement. Coronal PD-weighted image with fat suppression reveals short ulnar converging into the radius. Mild radial subcortical signal changes at the area of bone contact (arrow).

Figure 6.

Symptomatic carpal boss. Sagittal T2-weighted image with fat suppression. The patient presented with a painful dorsal lump, corresponding to a small carpal boss (arrow). There is bone marrow edema of the boss and subcortical marrow edema of the base of the third metacarpal. Note an incidental volar ganglion cyst (*).

MRI often reveals carpal bone cysts, commonly called bone ganglia, and demonstrates their relation to cortical defects, ligament injuries and associated soft tissue ganglia.[13] Found most often in the scaphoid and lunate, bone ganglia may be differentiated from subchondral cysts due to associated deep chondropathy.

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