Usefulness of hybrid SPECT/CT for the 99mTc-HMPAO-labeled leukocyte scintigraphy in a case of cranial osteomyelitis

Cranial osteomyelitis is a potentially fatal lesion. White blood cell scanning (WBC) with 99mTc-hexamethylpropylene amine oxime (HMPAO) has proven highly sensitive and specific in the diagnosis and follow-up of patients with suspected osteomyelitis. In this report we show the usefulness of SPECT and transmission CT performed simultaneously using a hybrid imaging device for the functional anatomic mapping of soft tissue and cranial bone infections. 99mTc-HMPAO-labeled leukocytes scintigraphy was performed on an elderly diabetic man with an intracranial mass lesion and with suspected temporal bone infection. Planar scans were acquired 30 min, 4 h, and 24 h after injection. SPECT/CT was obtained 6 h after tracer injection, using a dual-head camera coupled with a low-power X-ray tube. The scintigraphic results were matched with the results of surgery and of clinical follow-up. The planar images alone were true-positives for abscess in this patient. SPECT/CT improves the accuracy of99mTc-HMPAO scintigraphy especially in discriminating between soft-tissue and bone involvement. In fact, SPECT/CT also showed temporal bone osteomyelitis. This result indicates that SPECT/CT performed using a hybrid device can improve imaging with 99mTc-HMPAO-labeled leukocytes in patients with suspected osteomyelitis by providing accurate anatomic localization and precise definition of the extent of infection.

A Case of Ocular Hydroxyapatite Infection Diagnosed by Technetium 99m-labeled Leukocyte Scintigraphy

PURPOSE: To describe a low-grade infection of hydroxyapatite orbital implant diagnosed by 99mTc-labeled leukocyte scintigraphy. METHODS: A 34-year-old man diagnosed as phthisis bulbi due to corneoscleral laceration on left eye had been treated with evisceration and hydroxyapatite orbital implant insertion. After drilling for ocular prosthesis, the patient did not have any symptom for 3 years and 5 months. He presented with socket pain, erythematous lid swelling, severe conjunctival discharge. There was no improvement of symptom despite conservative treatment for 3 weeks. MRI revealed no abnormalities so 99mTc-labeled leukocyte scintigraphy was performed. RESULTS: Scintigraphy showed a dense accumulation of labeled leukocyte at the implant site. After diagnosed as hydroxyapatite orbital implant infection, orbital implant was removed and silicon sphere implantation was done. After operation, the inflammation signs disappeared. CONCLUSIONS: 99mTc-labeled leukocyte scintigraphy is a useful technique in diagnosing low-grade infection of hydroxyapatite orbital implant undetected using conventional imaging method such as MRI.