MR Imaging of the Pediatric Foot and Ankle

MRI of Pediatric Foot and Ankle Conditions

The increase in competitive sports practice among children and lack of ionizing radiation have resulted in a higher demand for MRI examinations. MRI of the children skeleton has some particularities that can lead orthopedists, pediatricians, and radiologists to diagnostic errors. The foot and ankle have several bones with abundant radiolucent and high signal intensity cartilage in several ossification centers, apophysis and physis, that can make this interpretation even harder. The present revision aims to show, how to differentiate between normal developmental findings and anatomic variants from pathologic conditions, whether mechanical, inflammatory, infectious, or neoplastic.

Benign incidental lesion of the calcaneus: the calcaneal vascular remnant

BACKGROUND

The calcaneal vascular remnant, first described by Fleming et al. in 2005, is a benign intramedullary lesion of the calcaneus with a vascular origin.

PURPOSE

To determine the prevalence and magnetic resonance imaging (MRI) characteristics of incidental calcaneal vascular remnant on routine ankle MRI.

MATERIAL AND METHODS

We retrospectively reviewed 457 ankle MRI scans for the presence of calcaneal vascular remnant. MRI was considered positive when a focal cyst-like area was seen on a T2-weighted sequence, and a low signal intensity was identified on a T1-weighted image beneath the calcaneal sulcus. Patients with calcaneal vascular remnants were further evaluated for age, gender, right or left foot location, size, and lesion characteristics.

RESULTS

The prevalence of incidental calcaneal vascular remnant was 21.7% on our consecutive ankle MR examinations. The average lesion size was 5.5 mm. No statistically significant difference was noted in the frequency of lesion detection between gender, age, and side of the lesions (P > 0.05). Multilobulated lesions were detected predominantly in women (P = 0.013) and classic type lesions were detected predominantly in men (P = 0.036).

CONCLUSION

This report is the first to determine the prevalence and MRI characteristics of calcaneal vascular remnants. Detecting and reporting this lesion on routine MRI is essential to avoid confusion with other pathologic entities.

Magnetic resonance imaging of severe idiopathic club foot treated with one-week accelerated Ponseti (OWAP) technique

PURPOSE

This study aims to evaluate changes in tarsal bones relationship after the use of one week accelerated Ponseti method in the treatment of severe idiopathic clubfoot using MRI. We hypothesize that one-week accelerated Ponseti is at least as effective as standard techniques in achieving the desirable MRI parameters.

METHODS

This is a prospective study of 8 children with severe idiopathic clubfeet (Pirani 6) (4 unilateral and 4 bilateral) treated before the age of three months with one-week accelerated Ponseti technique, as described in a former study with minimum 2-year follow-up. The 8 corrected feet were compared with the 4 unilateral normal feet at clinical and radiological levels using a Pirani scoring system and an MRI, respectively.

RESULTS

Clinical results showed that Pirani score was 1.1 in the last follow up in comparison to Pirani 6 pretreatment (p < 0.05). MRI results indicated that the malleocalcaneal angle, axial malleocalcaneal index, coronal tibiocalcaneal angle, sagittal talocalcaneal angle, and talar head neck calcaneal rotation showed statistical difference between the two groups (p < 0.05). Sagittal malleocalcaneal index, sagittal tibiocalcaneal angle, talar head neck rotation related to talar body, and posterior calcaneal rotation showed no statistical difference between normal feet and clubfeet after correction (p value >0.05).

CONCLUSION

One-week accelerated Ponseti technique showed to be as effective and safe as other treatment methods through clinical and MRI follow up data. MRI role was to confirm the efficiency of this innovative accelerated technique, but not used as a routine follow up.

Traumatic and non-traumatic bone marrow edema in ankle MRI: a pictorial essay

Bone marrow edema (BME) is one of the most common findings on magnetic resonance imaging (MRI) after an ankle injury but can be present even without a history of trauma. This article will provide a systematic overview of the most common disorders in the ankle and foot associated with BME.

The presence of BME is an unspecific but sensitive sign of primary pathology and may act as a guide to correct and systematic interpretation of the MR examination. The distribution of BME allows for a determination of the trauma mechanism and a correct assessment of soft tissue injury. The BME pattern following an inversion injury involves the lateral malleolus, the medial part of the talar body, and the medial part of the distal tibia. In other cases, a consideration of the distribution of BME may indicate the mechanism of injury or impingement. Bone in direct contact with a tendon may lead to alterations in the bone marrow signal where BME may indicate tendinopathy or dynamic tendon dysfunction. Changed mechanical forces between bones in coalition may lead to BME. Degenerative changes or minor cartilage damage may lead to subchondral BME. Early avascular necrosis, inflammation, or stress fracture may lead to more diffuse BME; therefore, a detailed medical history is crucial for correct diagnosis.

A systematic analysis of BME on MRI can help to determine the trauma mechanism and thus assess soft tissue injuries and help to differentiate between different etiologies of nontraumatic BME.