Presurgical Setting of Secondary Hyperparathyroidism Using High-Resolution Sonography and Color Doppler.

Purpose: High-resolution sonography (US) with color Doppler imaging (CDI) is a simple, noninvasive, safe and repeatable technique able to highlight the presence of hyperplastic parathyroid glands and changes in their volume, structure, and vascularization during uremia. The primary aim of this study was to assess the diagnostic accuracy of US and the sensitivity for localizing parathyroid glands with a volume ≥ 500mm3. The secondary aim was to assess the parameters that define parathyroid glandular perfusion. Materials and Methods: The diagnostic use of US was assessed in 40 consecutive uremic patients with severe secondary hyperparathyroidism (sHPT) who were receiving maintenance hemodialysis or conservative therapy with a hypoproteic- hypophosphoric diet and had undergone parathyroidectomy. Prior to surgery 99mTC-sestamibi scintigraphy (SM) was performed in all patients. Results: The sensitivity, specificity, positive predictive value and accuracy of US were 74%, 75%, 98%, and 74%, respectively. The sensitivity for localizing glands with a volume ≥ 500mm3 was 90%. US and SM had a combined sensitivity of 83%. The vascularization of parathyroid glands became more evident with increasing glandular volume. With CDI, the signs of hypervascularization (i.e. an enlarged feeding artery at the hilum, a peripheral arc of vascularity and/or ray-like endonodular vessels) were present in 77% of glands with a volume ≥ 500mm3. Conclusion: The sensitivity of US is higher than that of SM, but it cannot be compared with that of parathyroidectomy (74 vs. 95%). However, US/ CDI is able to characterize glands with different volumes and vascular patterns. Since glandular volume and vascularization are indicative of the severity of sHPT, this study suggests that the main role of US/CDI in the setting of sHPT should be to complete the diagnosis and to evaluate the morphological changes of enlarged glands during uremia in order to define surgical timing, rather than to assess the presurgical location of glands.