CT ankle scan

Surface rendered image (3D) of the ankle. Image is create using the data of a CT ankle joint scan.

Similar expressions

CT ankle joint/ NCCT ankle

Introduction

CT ankle protocol is used to assess bony structure of the foot, including fractures, neoplasms, congenital abnormalities and implants. This can provide 3D reconstruction images that helps in surgical planning.  

Patient preparation

  • Assess patients suitability to expose radiation.
  • Remove removable metallic objects in the interested region.
  • Ask not to move the ankle and foot during the scan.

Patient positioning

  • Position in feet-first supine.
  • Extend the affected leg and bent the unaffected leg at knee joint.
  • Place the affected ankle in the iso-center of scanner.

Explanation: this reduces radiation dose to the patient and improves image quality.

  • Position the planter aspect of the foot perpendicular to the table, form pad can be used to support the leg.
  • Place a sand bag on the mid part of the lower leg to immobilize the affected limb.
Demonstrates patient positioning for CT ankle joint scan. Limb with the effected ankle joint is extended.

Scan planning

  • Plan the scan slab to cover from tibiofibular joint to the bottom of the calcaneus.
  • Reduce the field of view (FOV) adequately to include the ankle joint.

Explanation: small FOV increases geometric resolution of the image.

Demonstrates scan slab positioning for CT ankle joint scan.

Post-processing

  • Axial, sagittal and coronal images in both bone (WW: 3500, WL: 350) and soft tissue window (WW:500, WL:50) with ≤ 2mm slice thickness.
Multiplanar reformation (MPR) for axial, sagittal and coronal for CT ankle joint scan are shown here. All these images are in bone window.
  • 3D images to demonstrate pathologies clearly.
Demonstrates surface shaded display (3D) of ankle joints. Raw data of CT ankle joint scan is used here.

Reference

  1. Kalantar, S. H., Bagheri, N., Milan, N., Mehni, S. M., Oskouie, I. M., Alinia, T., & Rahimdoost, N. (2024). Evaluation of treatment planning discrepancies: CT versus plain radiographic findings in patients with foot and ankle trauma. BMC research notes, 17(1), 238. https://doi.org/10.1186/s13104-024-06902-9
  2. Yoo I. R. (2020). Bone SPECT/CT of the Foot and Ankle: Potential Clinical Application for Chronic Foot Pain. Nuclear medicine and molecular imaging, 54(1), 1–8. https://doi.org/10.1007/s13139-019-00627-5
  3. Allen, G. M., Wilson, D. J., Bullock, S. A., & Watson, M. (2020). Extremity CT and ultrasound in the assessment of ankle injuries: occult fractures and ligament injuries. The British journal of radiology, 93(1105), 20180989. https://doi.org/10.1259/bjr.20180989