Fig. 4. DDF tendonitis/tendonopathy. Transverse proton density image of the foot (A) showing insertional DDF tendonitis (arrows), transverse proton density image at the level of the navicular bursa (B) showing a core lesion of the DDFT (arrow), and sagittal proton density image showing extension of DDF tendonitis proximal into the sheath (arrow).
density/T1-weighted sequences and low signal in- tensity on T2 and fat-suppressed images are less severe or more chronic in nature.24 In addition, it has also been shown that very early tendinosis can be manifested as increased signal intensity seen only on T1 and gradient echo sequences.24 It has been shown that in chronic cases of tendonitis, high signal inten- sity on T1-weighted images were areas of fibrosis/ fibroplasias in contrast with lesions with high signal intensity on all sequences, which were more active/ severe lesions with necrotic changes.25,26
Supporting Ligaments of the Navicular Bone
MRI provides the best means of evaluation of the sup- porting ligaments of the navicular bone, the CSL, and DSIL (Fig. 5). These supporting ligaments are com- monly injured within the foot. A definitive diagnosis of CSL and DSIL desmitis is difficult with radio- graphic or ultrasonographic examinations alone due to the location deep within the hoof capsule. MRI ap-
pearance in desmitis of the CSL is manifested by en- largement and increased signal intensity in acute cases or low signal intensity due to fibrosis in more chronic cases. Many times this is accompanied by radiographic evidence of enthesopathy present on the medial and lateral proximal wings of the navicular bone. Impar ligament desmitis is also characterized by enlargement and increased signal intensity on the MRI. In addition to enlargement many cases have tissue of intermediate signal intensity between the impar ligament and the DDFT suggesting the pres- ence of adhesions between the ligament and the DDFT. Avulsion/marginal fragments at the origin of the impar ligament on the distal border of the navic- ular bone, and insertional bone edema/cysts of the coffin bone can also be present.
Collateral Ligament Desmitis
Injuries to the collateral ligament of the distal in- terphalangeal joint are best evaluated with MRI
