The failure of T2 in foot imaging

This 14-year-old with prior fibular fracture now complains of ankle pain, swelling and locking symptoms 4-5 months after original injury. You are shown two sagittal sequences of the hind and midfoot. Image 1 is a proton density fat suppression using the technique known as STIR. Image 2 is a T2 fast-spin echo.

  1. What is the diagnosis?
  2. What should tip you off to the diagnosis?
  3. Why does the T2-weighted spin-echo image fail to demonstrate the abnormality?
  4. What is the treatment for this disorder?

Sagittal STIR

Sagittal T2

  1. The diagnosis is complex regional pain syndrome type 1, formerly known as reflex sympathetic dystrophy.
  2. The three tip-offs to the diagnosis are the history; generalized swelling; and a pattern of mostly peripheral marrow edema (most important) throughout every bone of the mid and hindfoot. This “window-framing” pattern is typical of the diagnosis.
  3. T2 spin-echo imaging, especially fast spin-echo imaging, is not a high-contrast resolution sequence for water inside bone. In other words, the relaxivity characteristics do not provide sufficient sensitivity. Only the most profound and grave disorders will show up within the bone or bone marrow on T2 spin-echo imaging especially without fat suppression. One example would be acute active osteomyelitis by Staphylococcus aureus, which shows up on every pulsing sequence.
  4. Movement therapy is the first treatment, especially if the disorder is caught early. However, often these children are in so much pain that movement therapy is not possible, especially if there is a delay in diagnosis. Often, multiple anesthetic blocks of the lumbar plexus on the side of the affected extremity are necessary. This is a serious disorder that can result in loss of a limb. Unusual therapies are also available to “quiet the nervous system” and one of these is ketamine therapy with the patient placed in twilight anesthesia for several days. Obviously this a more radical treatment but is sometimes needed. For more case review, check out MRI Online.
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