In-vitro verification of the electron beam tomography method for measurement of heart valve calcification.

BACKGROUND AND AIM OF THE STUDY: Electron beam tomography (EBT) has been used previously to study aortic root wall and leaflet calcification. However, the sensitivity of this method must be validated by comparing EBT findings with calcification in the cusps as determined using other techniques. An in-vitro study was designed to examine the correlation between EBT scores of calcification, visual observations, traditional X-radiography, dual-energy X-ray analysis (DEXA) and atomic absorption spectroscopy (AAS).

METHODS

Seven commercial and experimental pericardial valves were implanted in the mitral position in juvenile sheep for up to 20 weeks. Valves were examined thoroughly upon explantation and traditional x-radiographs were taken using standard techniques and ranked in increasing order of calcification. A calcification score in Hounsfield Units (HU) and a calcified volume score in mm3 were calculated for each valve by EBT. Calcium content was then calculated by means of DEXA and AAS.

RESULTS

Calcification scores ranged from 1.03 to 538.93 HU, and calcified volume scores from 6.18 to 1804.6 mm3. Correlation analysis showed a good agreement between the physical observations, in-vitro traditional X-radiography and both the calcification score and calcified volume score. EBT measurements were highly correlated with the DEXA examinations (r = 0.98, p = 0.0001 versus calcification score; and r = 0.97, p = 0.0003 versus calcified volume score) and AAS analyses (r = 0.98, p = 0.0001 versus calcification score; and r = 0.99, p = 0.0000 versus calcified volume score).

CONCLUSION

These preliminary results indicate a good correlation between the physical observations of calcification, X-radiographic observations, DEXA, AAS analyses and EBT measures of calcification.