Single region of interest versus multislice T2* MRI approach for the quantification of hepatic iron overload.

PURPOSE: To evaluate the effectiveness of the single ROI approach for the detection of hepatic iron burden in thalassemia major (TM) patients in respect to a whole liver measurement. MATERIALS AND METHODS: Five transverse hepatic slices were acquired by a T2* gradient-echo sequence in 101 TM patients and 20 healthy subjects. The T2* value was calculated in a single region of interest (ROI) defined in the medium-hepatic slice. Moreover, the T2* value was extracted on each of the eight ROIs defined in the functionally independent segments. The mean hepatic T2* value was calculated. RESULTS: For patients, the mean T2* values over segments VII and VIII were significantly lower. This pattern was substantially preserved in the two groups identified considering the T2* normal cutoff. All segmental T2* values were correlated with the single ROI T2* value. After the application of a correction map based on T2* fluctuations in the healthy subjects, no significant differences were found in the segmental T2* values. CONCLUSION: Hepatic T2* variations are low and due to artifacts and measurement variability. The single ROI approach can be adopted in the clinical arena, taking care to avoid the susceptibility artifacts, occurring mainly in segments VII and VIII.

Cardiac iron and cardiac disease in males and females with transfusion-dependent thalassemia major: a T2* magnetic resonance imaging study.

BACKGROUND: It has been repeatedly reported that female patients with thalassemia major survive longer than males and that the difference is due to a lower rate of cardiac disease in females. DESIGN AND METHODS: We compared the cardiac iron load as measured by T2* magnetic resonance imaging in 776 patients (370 males) examined at the National Research Council as part of an Italian cooperative study. We also established normal left ventricular ejection fraction values for our population. RESULTS: The prevalence of cardiac disease was higher in males than in females (105 males versus 69 females; P < 0.0001). Cardiac T2* was significantly lower in patients with heart dysfunction (P < 0.0001), but no difference was observed according to sex. Twenty males and five females had a history of cardiac arrhythmias. Their cardiac T2* was not significantly lower than that of patients without arrhythmias (24 ms versus 26 ms; P = 0.381), nor was there a difference between sexes. Liver T2* was significantly lower in males and females with heart dysfunction compared to those without. Ferritin levels were higher in patients of both sexes with heart dysfunction without significant differences between males and females. Conclusions Males and females are at the same risk of accumulating iron in their hearts, but females tolerate iron toxicity better, possibly as an effect of reduced sensitivity to chronic oxidative stress.

Multislice multiecho T2* cardiac magnetic resonance for the detection of heterogeneous myocardial iron distribution in thalassaemia patients.

The present study investigated myocardial T2* heterogeneity in thalassaemia major (TM) patients by cardiac magnetic resonance (CMR), to determine whether is related to inhomogeneous iron overload distribution. A total of 230 TM patients consecutively referred to our laboratory were studied retrospectively. Three short-axis views (basal, medium and apical) of the left ventricle (LV) were obtained by multislice multiecho T2* CMR. T2* segmental distribution was mapped on a 16-segment LV model. The level of heterogeneity of the T2* segmental distribution, evaluated by the coefficient of variation (CoV), was compared with that of a surrogate data set, to determine whether the inhomogeneous segmental distribution of T2* could be generated by susceptibility artefacts. Susceptibility artefacts offer an explanation for the T2* heterogeneity observed in patients without iron overload. In subjects with global T2* below the lower limit of the normal, T2* heterogeneity increased abruptly which could not be explained by artefactual effects. Some segmental T2* values were below and others above the limit of normal threshold (20 ms) in 104 (45%) TM patients. Among these patients, 74% showed a normal T2* global value. In conclusion, a true heterogeneity in the iron overload distribution may be present in TM patients. Heterogeneity seemingly appears in the borderline myocardial iron and stabilizes at moderate to severe iron burden.

Cardiovascular magnetic resonance characterization of a hamartoma in an asymptomatic child.

BACKGROUND: The prevalence of primary cardiac neoplasms is approximately 0.3% and these masses should be distinguished from many of other primary and secondary processes that can occur in the heart. Further assessment of the left ventricular mass presents important clinical implications. Cardiovascular magnetic resonance was used. CLINICAL CASE: An asymptomatic 12-year-old child was referred for cardiovascular magnetic resonance imaging to further assess a left ventricular mass found after an echocardiography, executed for assessment for sport activity. His past medical history was absolutely negative. The patient was in optimal state of health. The EKG showed an aspecific ST elevation. A hamartoma was diagnosed. A surgical approach was performed. After 7 days the patient is in good condition.

Left ventricular non-compaction cardiomyopathy in children: Is segmental fibrosis the cause of tissue Doppler alterations and of EF reduction?

Noncompaction of the ventricular myocardium (LVNC) is a rare congenital cardiomyopathy resulting from an arrest in normal endomyocardial embryogenesis. In 2002 Jenni et al. [Jenni R, Wyss CA, Oechslin EN, Kaufmann PA. Isolated ventricular noncompaction is associated with coronary microcirculatory dysfunction. J Am Coll Cardiol 2002; 39:450-454.] reported a microvascular dysfunction in 12 patients affected by non compaction: areas of restricted myocardial perfusion have been documented by scintigraphy, suggesting a reduction of Coronary flow reserve. McMahon et al reported in a recent article a reduction of TD velocities in children with noncompaction of the left ventricle, compared with normal controls. The authors concluded their work saying that the reduction of lateral mitral Ea velocity helps to predict children with LVNC who are at risk of adverse clinical outcomes including death and need for cardiac transplantation. In a precedent report our group reported a strong correlation between pathological tissue Doppler and reduction of ejection fraction. Recently we scanned with a Signa HD 1.5 T (GE, Milwaukee, USA) 8 patients affected by non compaction. Transmural Gd-enhancement was detected in 5/8 patients (62%). In all patients with late enhancement a reduction of EF has demonstrated. In our opinion the late enhancement can depend on a CFR, and is the determinant of the tissue Doppler alterations. So the TD alteration is associated with EF, and is an indirect index of poor clinical outcome, like EF.

Improved T2* assessment in liver iron overload by magnetic resonance imaging.

In the clinical MRI practice, it is common to assess liver iron overload by T2* multi-echo gradient-echo images. However, there is no full consensus about the best image analysis approach for the T2* measurements. The currently used methods involve manual drawing of a region of interest (ROI) within MR images of the liver. Evaluation of a representative liver T2* value is done by fitting an appropriate model to the signal decay within the ROIs vs. the echo time. The resulting T2* value may depend on both ROI placement and choice of the signal decay model. The aim of this study was to understand how the choice of the analysis methodology may affect the accuracy of T2* measurements. A software model of the iron overloaded liver was inferred from MR images acquired from 40 thalassemia major patients. Different image analysis methods were compared exploiting the developed software model. Moreover, a method for global semiautomatic T2* measurement involving the whole liver was developed. The global method included automatic segmentation of parenchyma by an adaptive fuzzy-clustering algorithm able to compensate for signal inhomogeneities. Global liver T2* value was evaluated using a pixel-wise technique and an optimized signal decay model. The global approach was compared with the ROI-based approach used in the clinical practice. For the ROI-based approach, the intra-observer and inter-observer coefficients of variation (CoVs) were 3.7% and 5.6%, respectively. For the global analysis, the CoVs for intra-observers and inter-observers reproducibility were 0.85% and 2.87%, respectively. The variability shown by the ROI-based approach was acceptable for use in the clinical practice; however, the developed global method increased the accuracy in T2* assessment and significantly reduced the operator dependence and sampling errors. This global approach could be useful in the clinical arena for patients with borderline liver iron overload and/or requiring follow-up studies.

A critical review of non invasive procedures for the evaluation of body iron burden in thalassemia major patients.

It is evident that different non invasive methodologies have been implemented for the detection of organ specific iron burden in patients with thalassemia major. Among these MR relaxometry has the potential to become the method of choice for non-invasive, safe and accurate assessment of organ-specific iron load, although further theoretical research, along with studies monitoring wider age groups of patients, is needed. Moreover, the possibility of detecting organ-specific iron burden is relevant for tailoring specific chelation treatment in different patients or in the same patient during different periods of life. In fact, while heart organ-specific effect has been suggested by MR relaxometry for some chelation treatments, it is possible to suppose that another single chelator or association of other chelators may show different organ-specific effects. For these reasons, the future of our clinical research will be to understand, mainly by MR relaxometry, whether it would be possible to set up a tailored organ-specific chelation treatment, according to this supposed difference in organ efficacy of the current chelation therapies.

Multislice multiecho T2* cardiovascular magnetic resonance for detection of the heterogeneous distribution of myocardial iron overload.

PURPOSE: To assess the tissue iron concentration of the left ventricle (LV) using a multislice, multiecho T2* MR technique and a segmental analysis. MATERIALS AND METHODS: T2* multiecho MRI was performed in 53 thalassemia major patients. Three short-axis views of the LV were obtained and analyzed with custom-written software. The myocardium was automatically segmented into 12 segments. The T2* value on each segment as well as the global T2* value were calculated. Cine dynamic images were also obtained to evaluate biventricular function parameters by quantitative analysis. RESULTS: For the T2* global value, the coefficient of variation (CoV) for intra-/interobserver and interstudy reproducibility was 3.9% (r = 0.98), 5.5% (r = 0.98), and 4.7% (r = 0.99) respectively. Three groups were identified based on analysis of myocardial T2*: homogeneous (21%), heterogeneous (38%), and no myocardial iron overload (41%). The mean serum ferritin, liver iron concentration, and urinary iron excretion were significantly different among the groups. We did not find significant differences among groups in biventricular function. There was a correlation between the global T2* value and the T2* value in the mid-ventricular septum (r = 0.95, P < 0.0001). CONCLUSION: Multislice multiecho T2* MRI provides a noninvasive, fast, reproducible means of assessing myocardial iron distribution. The single measurement of mid-septal T2* correlated well with the global T2* value.

Evaluation of the efficacy of oral deferiprone in beta-thalassemia major by multislice multiecho T2*.

OBJECTIVES: Oral deferiprone (L1) appears to be promising in the treatment of beta-thalassemia major (TM) patients. T2* magnetic resonance imaging (MRI) with a single measurement in the mid-ventricular septum was validated as a quantitative evaluation of myocardial iron overload. Previous studies suggested a marked heterogeneity of iron distribution in the myocardium. We set up a multislice multiecho T2* MRI for the detection of this heterogeneity. The aim of our study was to investigate differences between the L1 vs. the subcutaneous desferrioxamine (DF)-treated patients using this new approach. METHODS: Thirty-six beta-TM patients (age 29 +/- 8 yr) underwent MRI. Eighteen patients received long-term L1, and 18 other patients matched for age and sex received DF. T2* multiecho sequences on three short axis views of the left ventricle were obtained and analyzed by custom-made software. In each slice, the myocardium was automatically segmented into four segments. Cine-dynamic images were also obtained to evaluate biventricular function. RESULTS: For multislice T2* technique, the coefficient of variation for intra- and inter-observer, and inter-study reproducibility was 3.9%, 4.7%, and 5.5%, respectively. The global heart T2* value was significantly higher in the L1 vs. DF group (35 +/- 7 vs. 27 +/- 2 ms; P = 0.02). The number of segments with normal T2* value (>20 ms) was significantly higher in the L1 vs. the DF group (11 +/- 1 vs. 8 +/- 5 segments; P = 0.03). We did not detect significant differences in biventricular function parameters. CONCLUSIONS: This new approach confirms that L1 could be more effective than DF in removal of myocardial iron.