ABNORMAL ULTRASONIC TISSUE CHARACTERIZATION OF THE MYOCARDIUM IN CHILDREN RECEIVING DOXORUBICIN FOR CANCER-THERAPY

Ultrasonic tissue characterization by integrated backscatter is a sens itive tool to detect myocardial changes related to specific diseases. Cardiotoxicity related to doxorubicin use is well known and remains a major concern. To determine if ultrasonic tissue characterization of t he myocardium is abnormal in patients receiving doxorubicin, we studie d the myocardium of pediatric patients receiving doxorubicin by a real -time integrated backscatter (IB) imaging system. Three values of IB p arameters were averaged from the left ventricular posterior wall at th e Level of the tip of the mitral valve. In addition to standard echo p arameters, we obtained the following IB parameters: peak, nadir, cycli c variation (CV), end-diastole, heart-rate corrected delay of nadir (D elay(c)), and the ratio of CV over end-diastole. IB parameters were no rmalized as Z scores from multiple linear regression equations includi ng echo wall thickness and functional indices from a normal control gr oup of 72 children. We evaluated 27 patients at a median. age of 11.6 years (1.6 years to 20.3 years) and median time of 1.7 m (2 days to 7. 2 years) after a mean cumulative dose of doxorubicin of 188 +/- 120 mg /m(2) for treatment of neoplasm. Mean (+/- SD) Z scores for IB variabl es were as follows: zPeak 0.15 +/- 1.07, P = 0.47; zNadir 0.41 +/- 1.1 6, P = 0.08; zCV -0.49 +/- 0.95, P = 0.01; zEnd-diastole 0.17 +/- 0.94 , P = 0.38; zDelay, 0.33 +/- 0.80, P = 0.06, and zCV/Peak -0.59 +/- 1. 06, P = 0.009. This study shows that ultrasonic IB of the myocardium o f children receiving doxorubicin is abnormal and is independent of the cumulative dosage of doxorubicin. or the amount of time since the las t dose.