Case Author(s): Jerold Wallis, M.D. , 5/11/96 . Rating: #D2, #Q3

Diagnosis: Osteomyelitis of the calcaneous

Brief history:

Heel ulcerations, evaluate for bone infection

Images:

Anterior, posterior, and lateral delayed images of the feet.

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View second image(bs). Flow and immediate images of the feet. The flow images and upper right immediate image are posterior views.

View third image(bs). Anterior and posterior images of the whole body. Can you figure out the patient's underlying medical problem?

Full history/Diagnosis is available below

Diagnosis: Osteomyelitis of the calcaneous

Full history:

The patient is status post gunshot wound several years ago, and is a paraplegic. He has sacral ulcers and heel ulcerations, and the study is obtained to evaluate for osteomyelitis

Radiopharmaceutical:

20 mCi Tc-99m MDP, i.v.

Findings:

Increased activity is seen in the region of the right and left calcaneous on all three phases of the bone scintigraphy (flow, blood pool, and delayed imaging). This finding suggests osteomyelitis, although the diagnostic accuracy of the test has been reported to be decreased in the presence of overlying skin ulcers.

Imaging of the whole body demonstrate increased activity around the hip joints in a distribution not corresponding to normal bone; this finding is consistent with myositis ossificans in the paraplegic patient.

Increased activity can be seen in the mid sacrum as well, with probable increased activity at the ischial tuberosities.

Discussion:

Three phase bone scintigraphy can be used as an aid in the determination of osteomyelitis. Radiographs of suspicious areas should also be obtained, but may be normal at the time of bone scintigraphy.

Other possible causes of increased uptake on a three-phase bone scan include fracture, healing avascular necrosis, bone involvement with primary or metastatic tumor, and Paget's disease. Mild diffuse increased uptake on delayed imaging can also be seen in the setting of increased blood flow from overlying cellulitis.

Note that evaluation of the sacrum can be difficult, since the normal appearance can vary due to the variable angulation of the sacrum. In this patient, the increased uptake in the mid sacrum and absent uptake in the lower sacrum warrented careful inspection of plain radiographs of this region (see below).

Followup:

Radiographs confirmed sclerosis and cortical destruction in both calcanei. Plain films of the pelvis demonstrate destruction of the inferior half of the sacrum (new from comparison images one year prior), consistent with infection in this patient with a sacral decubitus and no known malignancy. Hypertrophic bone and evidence of myositis ossificans was also noted.

ACR Codes and Keywords:

References and General Discussion of Bone Scintigraphy (Anatomic field:Skeletal System, Category:Inflammation,Infection)

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Case number: bs058

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