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 ≥ 500 mm(3). 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 (99m)TC-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 ≥ 500 mm(3) 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 ≥ 500 mm(3). 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.

Color Doppler sonography in the study of chronic ischemic nephropathy.

In western countries, the risk of cardiovascular disease has increased considerably in recent decades. This trend has been paralleled by an increase in cases of atherosclerotic renal disease, which is related to the improved prognosis of cardiovascular diseases, aging, and the increasing mean age of the general population. It is reasonable to expect that in the near future, there will be a sharp increase in the number of elderly patients with atherosclerotic vascular disease in chronic dialysis programs. The result will be a dramatic rise in the social and economic costs of dialysis that could constitute a true clinical emergency. In this epidemiologic scenario, one of the most important targets of 21st century nephrology will be the early diagnosis of chronic ischemic nephropathy and the development of new and more effective strategies for its treatment.Color Doppler (CD) ultrasonography has displayed high sensitivity, specificity, and positive and negative predictive values in the diagnosis of this disease in selected population, making it an ideal tool for use in screening programs. Eligibility for screening should be based on clinical criteria. For the most part, it will be aimed at adults (especially those who are elderly) with atherosclerotic vascular disease involving multiple districts and chronic kidney disease (CKD), stage 2-3, in the absence of a documented history of renal disease. In these patients, hypertension may be a secondary manifestation or a symptom of the ischemic nephropathy itself. The objectives of sonographic screening should be (1) to identify subjects in the population at risk who are affected by stenosis of the main renal artery (RAS); (2) to identify and characterize patients without RAS who have chronic ischemic nephropathy caused by nephroangiosclerosis and/or atheroembolic disease. The former group will require second-level diagnostic studies or angioplasty with stenting; the latter can be managed conservatively. The most important CD parameters in the workup of suspected RAS are those that are direct signs, i.e., increases in peak systolic velocity (PSV) and diastolic velocity (DV), spectral broadening, and an altered renal:aortic ratio (RAR). Their assessment requires full-length sampling of the renal artery and is associated with greater practical/technical difficulties. Measurement in triplicate of the PSV in the ostial, medial, and hilar segments of both arteries and bilateral measurement of parenchymal resistance indices are usually sufficient to detect the presence of stenosis and refer the patient for second-level studies. Important parameters for estimating the severity of a stenosis include the renal:aortic ratio (>3.5), disappearance of the early systolic peak in segmental vessels, lateralization of the resistance index (ΔRI > 0.05), and the evaluation of the acceleration index (AI) and acceleration time (AT). Second-level imaging studies (CT angiography, MR angiography) are still indispensable for precise definition of the location and extension of the stenosis and the therapeutic approach during digital subtraction angiography (DSA). In the absence of direct or indirect signs of RAS, increases in the intraparenchymal resistance indices (RI > 0.75-0.80; PI > 1.50) associated with systemic atherosclerotic disease are indicative of microcirculatory damage related to nephroangiosclerosis or atheroembolic disease.