Novel imaging strategy for the detection of fat embolism after arthroplasty

Introduction: Respiratory complications are common after arthroplasty with fat emboli and thromboembolic disease (PTE) being the most serious. As fat embolism from bone marrow should contain reticuloendothelial cells, we hypothesized that these cells take up colloid in the lung. A prospective tomographic study of 99m Tc phytate and perfusion was performed within 24 h after arthroplasty. Methods: Tomographic lung studies were acquired after 99m Tc phytate and 99m Tc MAA injection. Pre- and postoperative arterial blood gases (ABG), radiography/computed tomography were obtained. ABG were analysed as the difference in alveolar-arterial oxygen gradients, pre- and postoperatively (D_A-a). Results: Forty patients were studied, 16 with hip and 24 with knee arthroplasties. Lung uptake of 99m Tc phytate was present in 35% of cases. PTE was detected in 25 of 38 (67%) patients evaluated. D_A-a was significantly different between patients with PTE/fat embolism and without either entity (P < 0.05). Conclusion: A simple test is available for the detection of fat embolism in the lungs. It can specifically differentiate this common cause of hypoxia from PTE.