Click on any image below to see an enlargement of that image.

Figure 1: Achilles Tendinosis. Sagittal STIR image shows thickening of the Achilles tendon with mild increased signal intensity in the anterior aspect and inflammation in the adjacent fat.
Figure 2: Partial Tear of the Achilles Tendon. Axial PD Image shows increased signal intensity in the right aspect of the Achilles tendon representing a 30% tear.
Figure 3: Rupture of the Achilles Tendon. Sagittal STIR image shows a complete tear of the Achilles tendon with fluid in the gap.
Figure 4: Fracture of the Medial Cuneiform. 53 year old with mid-foot pain but negative radiographs. Sagittal T1 (A) and STIR (B) images show an oblique fracture in the medial cuneiform bone.
A	B
Figure 5: Complex Calcaneal Fracture. Sagittal T1 weighted image shows an oblique fracture through the body of the calcaneus and a second fracture through the anterior calcaneal process. The subtalar ligaments in the sinus tarsi are intact.
Figure 6: Normal 3-D Volume Rendered reconstruction of the Foot and Ankle. 3-D Volume rendered reconstruction of a normal foot CT showing bones and tendons (A) and only bones (B).
A	B

Above images are all original MR scans performed at Parkside MR Center.

Most ankle and foot injuries are adequately evaluated with a history, physical examination and radiographs; the common ankle sprain is usually treated conservatively and most fractures are readily detected on x-rays. As such, MRI and CT are typically reserved for the evaluation of patients with chronic pain, discordant physical examination and x-rays, suspected tendon injuries, suspected stress fractures, or complex fractures.

Chronic ankle pain has many etiologies and MRI is the study of choice to detect and classify these causes. MRI can show osteochondritis desiccans, chronic ligament and tendon tears, sinus tarsi syndrome, tarsal coalition, and impingement syndromes.

MRI is the most sensitive test to evaluate tendon pathology. It can reliably differentiate amongst tendinosis (fig. 1), partial tears (fig. 2) and complete tears (fig. 3). By assessing the extent of tendon tear, MRI can guide the clinician in treatment planning. In addition, associated abnormalities such as sinus tarsi syndrome, ligamentous injury, tendon dislocation, and bone contusions can also be evaluated. The commonly injured ankle tendons are the Achilles, posterior tibial, peroneus longus and peroneus brevis.

Although most foot and ankle fractures are easily detected on x-rays, some are located in a region not easily assessed on radiographs (fig. 4) or are not evident on the x-rays. Bone contusions (microtrabelucar fractures) commonly accompany acute traumatic soft tissue injuries and are seldom seen on radiographs. Repetitive stress injuries (stress reactions) follow a typical pattern starting in the periosteum. MRI can grade these stress reactions and can assist in determining when patients may resume their usual activities. Grade 1 stress reaction is the mildest and is characterized by periosteal reaction. Grade 2 shows high signal intensity in the bone marrow on STIR images and grade 3 injuries show low marrow signal intensity on T1 images. A grade 4 injury shows a discrete fracture line. Although initially used to grade tibial stress reactions, this system has been used to grade stress reactions at other sites.

For very complex fractures detected on radiographs, both MRI (fig. 5) and CT can be used to assist the surgeon in treatment planning. Modern CT software and hardware produce isotropic images, so later 2D and 3D reconstructions (fig. 6) can be performed in any plane.

1. Cerezal L, Abascal A, Pereda T, et. al. MR Imaging of Ankle Impingement Syndromes. AJR 2003;181:551.

2. Fredericson M, Bergman G, Hoffman KL, et. al. Tibial Stress Reaction in Runners: Correlation of Clinical Symptoms and Scintigraphy with a New Magnetic Resonance Imaging Grading System. Am J Sports Med 1995;23:472.

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