Potential Pitfalls of Steatopygia on Bone Scintigraphy and the Added Value of Single Photon Emission Computed Tomography and Single Photon Emission Computed Tomography/Computed Tomography

Abstract

Objectives: The aims of the study were to assess the prevalence of steatopygia on bone scintigraphy of obese patients and to evaluate its effect on the appearance of the lumbar spine, and the added benefit of single photon emission computed tomography (SPECT) and SPECT/computed tomography (SPECT/CT) in overcoming possible artifacts. Methods: Patients with BMI ≥30 who underwent bone scintigraphy between 2016 and 2019 were included. Three nuclear medicine consultants reviewed the studies to determine whether significant steatopygia was present, and whether it resulted in attenuation of underlying lumber spine and crease edge artifact. SPECT or SPECT/CT images were reviewed to evaluate their impact on diagnosis. Results: 56 out of the 100 patients were noted to have steatopygia on planar images. Among the group of 80 obese patients, 50% showed steatopygia, while in the group of 20 morbidly obese patients, 80% showed steatopygia. 32 of the 56 patients with steatopygia had significant attenuation at the lower lumber vertebrae. Nine of these patients showed crease edge artifact. SPECT and SPECT/CT clarified the scintigraphic abnormalities noted in all patients including those with edge artifact alleviating diagnostic difficulty. Among the 9 patients with edge artifact, 6 patients showed normal appearance on SPECT/CT images while three showed true abnormalities. Conclusions: Steatopygia is common on bone scintigraphy of obese patients, higher in females and morbidly obese patients. Obesity-related artifacts in bone scintigraphy, including attenuation effect and edge artifact, are common in this patient group. SPECT or SPECT/CT improves the diagnostic accuracy by overcoming the effects of steatopygia seen on planar images.