Value of Dual Energy Computed Tomography for detection of myocardial iron deposition in Thalassaemia patients: initial experience.
ABSTRACT The aim of our study was to compare the value of cardiac DECT (cDECT) for detection of myocardial iron deposition to T2*w cardiac MRI (cMRI).
Nineteen patients with clinical history of Thalassaemia underwent T2*-weighted cardiac MRI (cMRI) with a 1.5 T MR scanner (MAGNETOM Symphony, Siemens Medical Solutions, Erlangen, Germany) and cardiac dual energy CT (cDECT) with a DSCT scanner (SOMATOM Definition, Siemens Medical Solutions, Erlangen, Germany) on the same day. HU values obtained from cDECT scans and T2*-values from cMRI were statistically correlated to calculate significance levels. Table times were measured for both cDECT and cMRI and compared. Patients were asked to grade their subjective comfort during the examination.
In all patients cDECT scans were successfully acquired. HU values of septal muscle correlated strongly with T2*-values, whereas no correlation was found for paraspinal muscle. Table time was significantly shorter for cDECT compared to cMRI (mean: 3.7 min vs. 11.2 min) and subjective patient comfort was rated comfortable for cDECT and average to poor for cMRI. Mean radiation dose was 0.71 mSv.
cDECT scans seem to be possible for evaluation of myocardial iron load in pediatric Thalassaemia patients.
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ABSTRACT: beta-Thalassaemia major is a hereditary haemolytic anaemia that is treated with multiple blood transfusions. A major complication of this treatment is iron overload, which leads to cell death and organ dysfunction. Chelation therapy, used for iron elimination, requires effective monitoring of the body burden of iron, for which serum ferritin levels and liver iron content measured in liver biopsies are used as markers, but are not reliable. MRI based on iron-induced T2 relaxation enhancement can be used for the evaluation of tissue siderosis. Various MR protocols using signal intensity ratio and mainstream relaxometry methods have been used, sometimes with discrepant results. Relaxometry methods using multiple echoes achieve better sampling of the time domain in which relaxation mechanisms take place and lead to more precise results. In several studies the MRI parameters of liver siderosis have failed to correlate with those of other affected organs, underlining the necessity for MRI iron evaluation in individual organs. Most studies have included children in the evaluated population, but MRI data on very young children are lacking. Wider application of relaxometry methods is indicated, with the establishment of universally accepted MRI protocols, and further studies, including young children, are needed.Pediatric Radiology 01/2008; 37(12):1191-200; quiz 1308-9. · 1.57 Impact Factor
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ABSTRACT: Cardiac hemochromatosis remains the most frequent cause of death in beta-thalassemia major. Previous studies suggest an important right ventricular (RV) contribution to cardiac morbidity and mortality. Studies with Doppler echocardiography have shown contradictory results regarding left ventricular (LV) filling, whereas the RV filling characteristics have not been studied yet. We prospectively studied the pattern of RV filling and investigated echocardiographic and clinical correlates during baseline and follow-up examinations in patients with beta-thalassemia major. The study included 79 patients, aged 24.2 +/- 8.0 years, with homozygous beta-thalassemia major without symptoms of heart failure with normal LV function and 51 healthy control subjects, matched for age, sex, and body surface area. Doppler echocardiographic indexes of systolic and diastolic ventricular function were assessed. Hemodynamic measurements were obtained in 8 patients by right heart catheterization. An abnormal RV relaxation pattern was evident in the patient group. The LV filling characteristics indicated increased preload without abnormal alteration, whereas catheterization findings were consistent with a high cardiac output state. Short tricuspid deceleration time (DT) had the best predictive value for subsequent cardiac events. Repeat echocardiographic study in 35 asymptomatic patients at 19 +/- 7 months demonstrated deterioration of LV systolic function, chamber enlargement, and shortening of DT of tricuspid and mitral inflow. In patients with homozygous beta-thalassemia major without cardiac disease, the pattern of RV filling is abnormally altered, indicating impaired relaxation. In contrast, the LV filling is compatible with increased preload, as in chronic anemia. Short DT of early tricuspid inflow carries important prognostic value. LV remodeling occurs over time along with transition toward a restrictive ventricular filling pattern.American Heart Journal 04/2001; 141(3):428-34. · 4.50 Impact Factor
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ABSTRACT: To develop and validate a non-invasive method for measuring myocardial iron in order to allow diagnosis and treatment before overt cardiomyopathy and failure develops. We have developed a new magnetic resonance T2-star (T2*) technique for the measurement of tissue iron, with validation to chemical estimation of iron in patients undergoing liver biopsy. To assess the clinical value of this technique, we subsequently correlated myocardial iron measured by this T2* technique with ventricular function in 106 patients with thalassaemia major. There was a significant, curvilinear, inverse correlation between iron concentration by biopsy and liver T2* (r=0.93, P<0.0001). Inter-study cardiac reproducibility was 5.0%. As myocardial iron increased, there was a progressive decline in ejection fraction (r=0.61, P<0.001). All patients with ventricular dysfunction had a myocardial T2* of <20 ms. There was no significant correlation between myocardial T2* and the conventional parameters of iron status, serum ferritin and liver iron. Multivariate analysis of clinical parameters to predict the requirement for cardiac medication identified myocardial T2* as the most significant variable (odds ratio 0.79, P<0.002). Myocardial iron deposition can be reproducibly quantified using myocardial T2* and this is the most significant variable for predicting the need for ventricular dysfunction treatment. Myocardial iron content cannot be predicted from serum ferritin or liver iron, and conventional assessments of cardiac function can only detect those with advanced disease. Early intensification of iron chelation therapy, guided by this technique, should reduce mortality from this reversible cardiomyopathy.European Heart Journal 01/2002; 22(23):2171-9. · 14.10 Impact Factor