Foot Pathology

The most common application for CT of the ankle is acute trauma. Other applications include evaluation of postoperative healing, (i.e. nonunion), arthritis, and tumors. This section presents a syllabus and a series of cases demonstrating trauma and pathology in the ankle and the corresponding scanning protocol.

CT has been used as a supplemental study for the evaluation of the foot and ankle for over two decades. Much of the discussion in the literature had focused on study protocol and design with emphasis on the need for positioning the foot or ankle in two positions at 90 degrees to each other to obtain the maximum information possible from a study. In this new era of volume acquisition and isotropic datasets evaluation of the foot or ankle can be performed in a single acquisition that is completed in less than 10 seconds. Using isotropic datasets we can then display the data interactively on a workstation in any plane or perspective without the loss of image detail or resolution. The use of 16 slice MDCT and subsequently 32 or 64 slice MDCT should prove critical in increasing the number of referrals for CT of the foot and ankle whether it be for trauma, infection, post operative evaluation or persistent pain. This exhibit is designed to first review the normal anatomy of the foot as seen from a volume visualization perspective. The second portion of the exhibit reviews the current clinical applications of MDCT in the foot and ankle with an emphasis on common applications like trauma and evaluation of persistent pain (i.e. arthritis, gout, tarsal coalition).

Technique and Tips
Scanner: Sensation 16 (Siemens Medical Systems)
Scanner rotation time 500 msec
Detectors used 16 x .75 mm
Slice thickness of reconstructed data .75 mm
Interscan spacing .5 mm
mAs 130-180
KVP 120
Foot routinely position at 90 degrees to table top (or as comfortable)
Single CT acquisition obtained and data then sent for post processing to a Leonardo workstation using InSpace software (Siemens Medical Solutions)
Data should be processed with both standard and high-resolution algorithm.