The clinical contribution of SPECT/CT with 99mTc-HMPAO-labeled leukocyte scintigraphy in hip and knee prosthetic infections. / Aportación clínica de la SPECT/TC en la gammagrafía con leucocitos marcados con 99mTc-HMPAO en infección de prótesis de cadera y rodilla.

ABSTRACT

OBJECTIVES: White blood cell scanning with 99mTc-hexamethylpropylene amine oxime (HMPAO) has proven a sensitive and specific imaging method in the diagnosis of suspected prosthesis infection. The aim of this retrospective study was to evaluate the usefulness of SPECT/CT performed simultaneously using a hybrid imaging device of prosthesis infections. MATERIALS AND METHODS: 99mTc-HMPAO scintigraphy was performed on 37 patients (11 men and 26 women; age range 38-84 years; mean age±SD, 65.7±5.6 years). Planar scans were acquired 2.4 and 24hour after injection. SPECT/CT was obtained 4 h after injection, using a dual-head hybrid gama camera coupled with a low-power x-ray tube. In all patients, scintigraphic results were matched with the results of surgery, cultures and clinical follow-up. RESULTS: Seventeen (45,9%) out of 37 patients had prosthesis infection and 20 (54,1%) out of 37 patients had non-infectious prosthesis pathologies with 99mTc-HMPAO scintigraphy and SPECT/CT. The 99mTc-HMPAO scintigraphy was true-positive for infection in 16 of 37 patients and true-negative in 20 of 37 patients. SPECT/CT provided an accurate anatomic localization of all positive foci. With regard to the final diagnosis, SPECT/CT added a significant clinical contribution in 22 of 37 patients (59,4%). Sensitivity, specificity, negative predictive value and positive predictive values were 100%,59.1%,100%,62.5% in planar images with 99mTc-HMPAO scintigraphy and 100%,90.1%,100%,88.2% in the planar+SPECT/CT imaging, respectively. DISCUSSION: Our results indicate that SPECT/CT performed using a hybrid device can improve imaging with 99mTc-HMPAO scintigraphy in patients with suspected osteomyelitis by providing accurate anatomic localization and precise definition of the extent of infection.