The patient was a 45-year-old man with nothing remarkable in his medical records, who presented with a 6-month history of pain and swelling in the dorsum of right foot (Fig. 1D) with purulent exudate between 4th and 5th toes. Cultures had repeatedly been negative, and he did not improve with intensive antibiotic therapy. The radiological images were not conclusive, and he came to our department to undergo scintigraphy1 with 99mTc-hexamethylpropyleneamine oxime (HMPAO)-labeled leukocytes (Fig. 1A and B). There was an increased uptake of the tracer in the fourth metatarsal 3h after injection of the radiotracer.2 The study was completed with the acquisition of a single photon emission computed tomography/computed tomography and 3D reconstruction (3D SPECT/CT) which made it possible to locate the infectious process in soft tissue of the dorsum of the foot. It was related to a foreign body in the distal third of the fourth metatarsal (Fig. 1C), unknown until then. After its surgical removal, the patient's improvement was excellent in a few weeks.

Fig. 1.

Single photon emission computed tomography/computed tomography (SPECT/CT) after the intravenous administration of autologous leukocytes labeled with 20mCi of 99mTc-hexamethylpropyleneamine oxime (HMPAO). Hybrid SPECT/CT image (A) and SPECT image (B) showing the increased uptake in the fourth metatarsal of right foot. 3D reconstruction with bone window (C) that enables the correlation of the scintigraphic findings with the presence of a foreign body (arrow), that can be discerned by the impression it leaves on the surface of the skin (D).

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Informative Message

The hybrid SPECT/CT image with 99mTc-HMPAO-labeled autologous leukocytes and 3D reconstruction is a highly accurate tool for the noninvasive diagnosis of infectious processes associated with invisible foreign bodies using morphological imaging techniques.