Robert G. Fraser

Myocardial calcification and cardiac dysfunction in chronic renal failure

PURPOSE Myocardial calcium content may have clinical importance in end-stage renal disease (ESRD), but it is difficult to detect during life. Our goal was to assess the effect of myocardial calcium content on left ventricular ejection fraction (LVEF) in uremic patients undergoing dialysis. PATIENTS AND METHODS Energy subtraction radiography of the chest was used to measure myocardial calcium content in 43 patients undergoing dialysis, in 32 control subjects, and in nine patients with advanced cardiomyopathy. LVEF and left ventricular end-diastolic dimension were measured by two-dimensional echocardiography. The concentration of parathyroid hormone was measured by radioimmunoassay; calcium-phosphorus product, alkaline phosphatase, and serum bicarbonate were also assessed. RESULTS Patients undergoing dialysis had a greater myocardial calcium content than control subjects [262 +/- 15.4 (mean +/- SE) versus 187 +/- 8 mg/cm2, p less than 0.05]. Ten patients with the highest myocardial calcium content (Group I) had the lowest LVEF values and highest left ventricular end-diastolic dimension. Significant inverse linear associations between LVEF and myocardial calcium content (r = -0.425, p = 0.013) and between parathyroid hormone concentration and LVEF (r = -0.352, p = 0.047) were noted. There was no association between parathyroid hormone concentration and myocardial calcium content. Stepwise regression analysis showed a strong positive correlation between myocardial calcium content and calcium-phosphorus product, vascular calcification, race (black), and parathyroidectomy. Similar analysis shows that LVEF was significantly associated with myocardial calcium content, lung calcium, calcium-phosphorus product, and race (black). CONCLUSION We suggest that increased myocardial calcium content results from poor calcium and phosphorus control and may be enhanced by parathyroid hormone hyperactivity. Increased myocardial calcium content is strongly associated with myocardial dysfunction in patients undergoing dialysis.

A comparison of dual-energy digital radiography and screen-film imaging in the detection of subtle interstitial pulmonary disease.

An ROC study is described which compares the performance of three types of images--conventional screen-film, single-energy digital and dual energy bone cancelled (soft tissue) digital--in detecting subtle interstitial pulmonary disease. Marginally detectable nodular and reticulonodular patterns (12 different patterns of each) were superimposed over the lungs of a frozen human chest phantom to simulate the clinical situation. The digital images were formatted on film at full size (ie, 35 cm X 43 cm). A total of 156 images (52 of each type, of which 28 were normal and 24 had simulated pathology) were used in the study and read by five experienced chest radiologists. Using a paired t-test, the areas under the individual ROC curves were compared for three combinations of images--single-energy digital and conventional, soft tissue digital and conventional, and soft tissue and single-energy digital. No statistically significant difference was observed between the conventional and single-energy digital images. The readers performed better with both conventional and single-energy digital images than with the soft tissue digital images at statistically significant levels (P = 0.05 for conventional vs. soft tissue digital and P = 0.02 for single-energy digital vs. soft tissue digital). The results suggest that there is no advantage in employing dual-energy soft tissue images to assist in diagnosing interstitial disease in the clinical setting. They also suggest that spatial resolution requirements are less demanding in digital chest systems that obtain scatter-free images than in digital systems utilizing conventional scatter control techniques.