AVN in the absence of fracture = Preiser's disease
MR feature:
Low on T1
Localized fluid around the scaphoid
Marrow edema of the proximal pole only
Reactive marrow hyperplasia of distal pole
Hyperemia is best shown on STIR (T2 and T1 are not sensitive)
Fluid seperating the fracture fragments
CT is better in assessing the bridging bone
Grading:
Non-contrast MRI:
Normal to slight ischemia - isointense proximal fragment similar to normal carpal bone on both T1 and T2
Moderate ischemia - proximal fragment slightly low signal on T1 and homogenous high signal on T2
Severe ischemia - proximal fragment variable low signal on T1 and heterogeneous signal intensity on T2
Avascular necrosis or nonviable proximal fragment - proximal fragment low signal on T1 and T2
Post Gd MRI:
Normal to slight ischemia - marked and homogenous enhancement in more than 80% proximal fragment
Moderate ischemia - patchy enhancement involving 50-80% of the proximal fragment
Severe ischemia - patchy enhancement involving 20-50% of the proximal fragment
Avascular necrosis to nonviable bone - absence of or less than 20% enhancement
Surgical grading: (Green)
group 1 (normal or good)
group 2 (fair)
group 3 (poor)
group 4 (none)
Other features (complications):
Fracture displacement
DISI
Volar displacement of proximal scaphoid, lunate and triquetrum (perilunar instability)
SLAC
SNAC (Scaphoid non-union advanced collapse)
Reference:
Munk PL et al. Gadolinium-Enhanced MR Imaging of Scaphoid Nonunions. AJR 2000; 175:1184-1185
