Metastatic calcification of the heart and lungs in end-stage renal disease: detection and quantification by dual-energy digital chest radiography

Abstract

Metastatic calcification of the lung and heart can cause severe cardiopulmonary compromise and death. Although it is found in most end-stage renal disease patients at autopsy, it is only rarely detected during life. Using a prototype dual-energy digital chest radiographic unit, we measured calcium content (mg/cm2) over the lung and heart in 32 hemodialysis patients. Pulmonary calcium content was significantly greater in these patients than in sex-matched control subjects (men, 230 +/- 43 [mean +/- standard error] vs 166 +/- 7, p less than .05; women, 168 +/- 19 vs 110 +/- 7.5, p less than .001). Abnormal values were detected by dual-energy radiography in 44% of patients (vs 9% of patients studied by conventional radiography). Cardiac calcium content was also significantly greater in the hemodialysis patients than in the control subjects (259 +/- 14 vs 184 +/- 8, p less than .05). Metastatic calcification was significantly correlated with elevated phosphate and calcium-phosphate product levels. Patients with significantly elevated pulmonary calcium content had evidence of restrictive lung disease by functional testing. There was an inverse correlation between elevated cardiac calcium content and ejection fraction. We conclude that dual-energy digital radiography allows premortem diagnosis of metastatic visceral calcification and is more sensitive than current techniques.