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

Randomized controlled trials of iron chelators for the treatment of cardiac siderosis in thalassaemia major

In conditions requiring repeated blood transfusion or where iron metabolism is abnormal, heart failure may result from accumulation of iron in the heart (cardiac siderosis). Death due to heart failure from cardiac iron overload has accounted for considerable early mortality in β-thalassemia major. The ability to detect iron loading in the heart by cardiovascular magnetic resonance using T2* sequences has created an opportunity to intervene in the natural history of such conditions. However, effective and well tolerated therapy is required to remove iron from the heart. There are currently three approved commercially available iron chelators: deferoxamine, deferiprone and deferasirox. We review the high quality randomized controlled trials in this area for iron chelation therapy in the management of cardiac siderosis.

A 1-year randomized controlled trial of deferasirox vs deferoxamine for myocardial iron removal in β-thalassemia major (CORDELIA)

Randomized comparison data on the efficacy and safety of deferasirox for myocardial iron removal in transfusion dependent patients are lacking. CORDELIA was a prospective, randomized comparison of deferasirox (target dose 40 mg/kg per day) vs subcutaneous deferoxamine (50-60 mg/kg per day for 5-7 days/week) for myocardial iron removal in 197 β-thalassemia major patients with myocardial siderosis (T2* 6-20 milliseconds) and no signs of cardiac dysfunction (mean age, 19.8 years). Primary objective was to demonstrate noninferiority of deferasirox for myocardial iron removal, assessed by changes in myocardial T2* after 1 year using a per-protocol analysis. Geometric mean (Gmean) myocardial T2* improved with deferasirox from 11.2 milliseconds at baseline to 12.6 milliseconds at 1 year (Gmeans ratio, 1.12) and with deferoxamine (11.6 milliseconds to 12.3 milliseconds; Gmeans ratio, 1.07). The between-arm Gmeans ratio was 1.056 (95% confidence interval [CI], 0.998, 1.133). The lower 95% CI boundary was greater than the prespecified margin of 0.9, establishing noninferiority of deferasirox vs deferoxamine (P = .057 for superiority of deferasirox). Left ventricular ejection fraction remained stable in both arms. Frequency of drug-related adverse events was comparable between deferasirox (35.4%) and deferoxamine (30.8%). CORDELIA demonstrated the noninferiority of deferasirox compared with deferoxamine for myocardial iron removal. This trial is registered at www.clinicaltrials.gov as #NCT00600938.

Oral deferiprone for iron chelation in people with thalassaemia

BACKGROUND

Thalassaemia major is a genetic disease characterised by a reduced ability to produce haemoglobin. Management of the resulting anaemia is through red blood cell transfusions.Repeated transfusions result in an excessive accumulation of iron in the body (iron overload), removal of which is achieved through iron chelation therapy. A commonly used iron chelator, deferiprone, has been found to be pharmacologically efficacious. However, important questions exist about the efficacy and safety of deferiprone compared to another iron chelator, desferrioxamine.

OBJECTIVES

To summarise data from trials on the clinical efficacy and safety of deferiprone and to compare the clinical efficacy and safety of deferiprone with desferrioxamine for thalassaemia.

SEARCH METHODS

We searched the Cochrane Cystic fibrosis and Genetic Disorders Group's Haemoglobinopathies trials Register and MEDLINE, EMBASE, CENTRAL (The Cochrane Library), LILACS and other international medical databases, plus registers of ongoing trials and the Transfusion Evidence Library (www.transfusionevidencelibrary.com). We also contacted the manufacturers of deferiprone and desferrioxamine.All searches were updated to 05 March 2013.

SELECTION CRITERIA

Randomised controlled trials comparing deferiprone with another iron chelator; or comparing two schedules or doses of deferiprone, in people with transfusion-dependent thalassaemia.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials for risk of bias and extracted data. Missing data were requested from the original investigators.

MAIN RESULTS

A total of 17 trials involving 1061 participants (range 13 to 213 participants per trial) were included. Of these, 16 trials compared either deferiprone alone with desferrioxamine alone, or a combined therapy of deferiprone and desferrioxamine with either deferiprone alone or desferrioxamine alone; one compared different schedules of deferiprone. There was little consistency between outcomes and limited information to fully assess the risk of bias of most of the included trials.Four trials reported mortality; each reported the death of one individual receiving deferiprone with or without desferrioxamine. One trial reported five further deaths in patients who withdrew from randomised treatment (deferiprone with or without desferrioxamine) and switched to desferrioxamine alone. Seven trials reported cardiac function or liver fibrosis as measures of end organ damage.Earlier trials measuring the cardiac iron load indirectly by magnetic resonance imaging (MRI) T2* signal had suggested deferiprone may reduce cardiac iron more quickly than desferrioxamine. However, a meta-analysis of two trials suggested that left ventricular ejection fraction was significantly reduced in patients who received desferrioxamine alone compared with combination therapy.  One trial, which planned five years of follow up, was stopped early due to the beneficial effects of combined treatment compared with deferiprone alone in terms of serum ferritin levels reduction.The results of this and three other trials suggest an advantage of combined therapy over monotherapy to reduce iron stores as measured by serum ferritin. There is, however, no conclusive or consistent evidence for the improved efficacy of combined deferiprone and desferrioxamine therapy over monotherapy from direct or indirect measures of liver iron. Both deferiprone and desferrioxamine produce a significant reduction in iron stores in transfusion-dependent, iron-overloaded people. There is no evidence from randomised controlled trials to suggest that either has a greater reduction of clinically significant end organ damage.Evidence of adverse events were observed in all treatment groups. Occurrence of any adverse event was significantly more likely with deferiprone than desferrioxamine in one trial, RR 2.24 (95% CI 1.19 to 4.23). Meta-analysis of a further two trials showed a significant increased risk of adverse events associated with combined deferiprone and desferrioxamine compared with desferrioxamine alone, RR 3.04 (95% CI 1.18 to 7.83). The most commonly reported adverse event was joint pain, which occurred significantly more frequently in patients receiving deferiprone than desferrioxamine, RR 2.64 (95% CI 1.21 to 5.77). Other common adverse events included gastrointestinal disturbances as well as neutropenia or leucopenia, or both.

AUTHORS' CONCLUSIONS

In the absence of data from randomised controlled trials, there is no evidence to suggest the need for a change in current treatment recommendations; namely that deferiprone is indicated for treating iron overload in people with thalassaemia major when desferrioxamine is contraindicated or inadequate. Intensified desferrioxamine treatment (by either subcutaneous or intravenous route) or use of other oral iron chelators, or both, remains the established treatment to reverse cardiac dysfunction due to iron overload. Indeed, the US Food and Drug Administration (FDA) recently only gave support for deferiprone to be used as a last resort for treating iron overload in thalassaemia, myelodysplasia and sickle cell disease. However, there is evidence that adverse events are increased in patients treated with deferiprone compared with desferrioxamine and in patients treated with combined deferiprone and desferrioxamine compared with desferrioxamine alone. There is an urgent need for adequately-powered, high-quality trials comparing the overall clinical efficacy and long-term outcome of deferiprone with desferrioxamine.

Desferrioxamine mesylate for managing transfusional iron overload in people with transfusion-dependent thalassaemia

BACKGROUND

Thalassaemia major is a genetic disease characterised by a reduced ability to produce haemoglobin. Management of the resulting anaemia is through red blood cell transfusions.Repeated transfusions result in an excessive accumulation of iron in the body (iron overload), removal of which is achieved through iron chelation therapy. Desferrioxamine mesylate (desferrioxamine) is one of the most widely used iron chelators. Substantial data have shown the beneficial effects of desferrioxamine, although adherence to desferrioxamine therapy is a challenge. Alternative oral iron chelators, deferiprone and deferasirox, are now commonly used. Important questions exist about whether desferrioxamine, as monotherapy or in combination with an oral iron chelator, is the best treatment for iron chelation therapy.

OBJECTIVES

To determine the effectiveness (dose and method of administration) of desferrioxamine in people with transfusion-dependent thalassaemia.To summarise data from trials on the clinical efficacy and safety of desferrioxamine for thalassaemia and to compare these with deferiprone and deferasirox.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. We also searched MEDLINE, EMBASE, CENTRAL (The Cochrane Library), LILACS and other international medical databases, plus ongoing trials registers and the Transfusion Evidence Library (www.transfusionevidencelibrary.com). All searches were updated to 5 March 2013.

SELECTION CRITERIA

Randomised controlled trials comparing desferrioxamine with placebo, with another iron chelator, or comparing two schedules or doses of desferrioxamine, in people with transfusion-dependent thalassaemia.

DATA COLLECTION AND ANALYSIS

Six authors working independently were involved in trial quality assessment and data extraction. For one trial, investigators supplied additional data upon request.

MAIN RESULTS

A total of 22 trials involving 2187 participants (range 11 to 586 people) were included. These trials included eight comparisons between desferrioxamine alone and deferiprone alone; five comparisons between desferrioxamine combined with deferiprone and deferiprone alone; eight comparisons between desferrioxamine alone and desferrioxamine combined with deferiprone; two comparisons of desferrioxamine with deferasirox; and two comparisons of different routes of desferrioxamine administration (bolus versus continuous infusion). Overall, few trials measured the same or long-term outcomes. Seven trials reported cardiac function or liver fibrosis as measures of end organ damage; none of these included a comparison with deferasirox.Five trials reported a total of seven deaths; three in patients who received desferrioxamine alone, two in patients who received desferrioxamine and deferiprone. A further death occurred in a patient who received deferiprone in another who received deferasirox alone. One trial reported five further deaths in patients who withdrew from randomised treatment (deferiprone with or without desferrioxamine) and switched to desferrioxamine alone.One trial planned five years of follow up but was stopped early due to the beneficial effects of a reduction in serum ferritin levels in those receiving combined desferrioxamine and deferiprone treatment compared with deferiprone alone. The results of this and three other trials suggest an advantage of combined therapy with desferrioxamine and deferiprone over monotherapy to reduce iron stores as measured by serum ferritin. There is, however, no evidence for the improved efficacy of combined desferrioxamine and deferiprone therapy against monotherapy from direct or indirect measures of liver iron.Earlier trials measuring the cardiac iron load indirectly by measurement of the magnetic resonance imaging T2* signal had suggested deferiprone may reduce cardiac iron more quickly than desferrioxamine. However, meta-analysis of two trials showed a significantly lower left ventricular ejection fraction in patients who received desferrioxamine alone compared with those who received combination therapy using desferrioxamine with deferiprone.Adverse events were recorded by 18 trials. These occurred with all treatments, but were significantly less likely with desferrioxamine than deferiprone in one trial, relative risk 0.45 (95% confidence interval 0.24 to 0.84) and significantly less likely with desferrioxamine alone than desferrioxamine combined with deferiprone in two other trials, relative risk 0.33 (95% confidence interval 0.13 to 0.84). In particular, four studies reported permanent treatment withdrawal due to adverse events from deferiprone; only one of these reported permanent withdrawals associated with desferrioxamine. Adverse events also occurred at a higher frequency in patients who received deferasirox than desferrioxamine in one trial. Eight trials reported local adverse reactions at the site of desferrioxamine infusion including pain and swelling. Adverse events associated with deferiprone included joint pain, gastrointestinal disturbance, increases in liver enzymes and neutropenia; adverse events associated with deferasirox comprised increases in liver enzymes and renal impairment. Regular monitoring of white cell counts has been recommended for deferiprone and monitoring of liver and renal function for deferasirox.In summary, desferrioxamine and the oral iron chelators deferiprone and deferasirox produce significant reductions in iron stores in transfusion-dependent, iron-overloaded people. There is no evidence from randomised clinical trials to suggest that any one of these has a greater reduction of clinically significant end organ damage, although in two trials, combination therapy with desferrioxamine and deferiprone showed a greater improvement in left ventricular ejection fraction than desferrioxamine used alone.

AUTHORS' CONCLUSIONS

Desferrioxamine is the recommended first-line therapy for iron overload in people with thalassaemia major and deferiprone or deferasirox are indicated for treating iron overload when desferrioxamine is contraindicated or inadequate. Oral deferasirox has been licensed for use in children aged over six years who receive frequent blood transfusions and in children aged two to five years who receive infrequent blood transfusions. In the absence of randomised controlled trials with long-term follow up, there is no compelling evidence to change this conclusion.Worsening iron deposition in the myocardium in patients receiving desferrioxamine alone would suggest a change of therapy by intensification of desferrioxamine treatment or the use of desferrioxamine and deferiprone combination therapy.Adverse events are increased in patients treated with deferiprone compared with desferrioxamine and in patients treated with combined deferiprone and desferrioxamine compared with desferrioxamine alone. People treated with all chelators must be kept under close medical supervision and treatment with deferiprone or deferasirox requires regular monitoring of neutrophil counts or renal function respectively. There is an urgent need for adequately-powered, high-quality trials comparing the overall clinical efficacy and long-term outcomes of deferiprone, deferasirox and desferrioxamine.

Cardiovascular function and treatment in β-thalassemia major: a consensus statement from the American Heart Association

This aim of this statement is to report an expert consensus on the diagnosis and treatment of cardiac dysfunction in β-thalassemia major (TM). This consensus statement does not cover other hemoglobinopathies, including thalassemia intermedia and sickle cell anemia, in which a different spectrum of cardiovascular complications is typical. There are considerable uncertainties in this field, with a few randomized controlled trials relating to treatment of chronic myocardial siderosis but none relating to treatment of acute heart failure. The principles of diagnosis and treatment of cardiac iron loading in TM are directly relevant to other iron-overload conditions, including in particular Diamond-Blackfan anemia, sideroblastic anemia, and hereditary hemochromatosis. Heart failure is the most common cause of death in TM and primarily results from cardiac iron accumulation. The diagnosis of ventricular dysfunction in TM patients differs from that in nonanemic patients because of the cardiovascular adaptation to chronic anemia in non-cardiac-loaded TM patients, which includes resting tachycardia, low blood pressure, enlarged end-diastolic volume, high ejection fraction, and high cardiac output. Chronic anemia also leads to background symptomatology such as dyspnea, which can mask the clinical diagnosis of cardiac dysfunction. Central to early identification of cardiac iron overload in TM is the estimation of cardiac iron by cardiac T2* magnetic resonance. Cardiac T2* <10 ms is the most important predictor of development of heart failure. Serum ferritin and liver iron concentration are not adequate surrogates for cardiac iron measurement. Assessment of cardiac function by noninvasive techniques can also be valuable clinically, but serial measurements to establish trends are usually required because interpretation of single absolute values is complicated by the abnormal cardiovascular hemodynamics in TM and measurement imprecision. Acute decompensated heart failure is a medical emergency and requires urgent consultation with a center with expertise in its management. The first principle of management of acute heart failure is control of cardiac toxicity related to free iron by urgent commencement of a continuous, uninterrupted infusion of high-dose intravenous deferoxamine, augmented by oral deferiprone. Considerable care is required to not exacerbate cardiovascular problems from overuse of diuretics or inotropes because of the unusual loading conditions in TM. The current knowledge on the efficacy of removal of cardiac iron by the 3 commercially available iron chelators is summarized for cardiac iron overload without overt cardiac dysfunction. Evidence from well-conducted randomized controlled trials shows superior efficacy of deferiprone versus deferoxamine, the superiority of combined deferiprone with deferoxamine versus deferoxamine alone, and the equivalence of deferasirox versus deferoxamine.

Fast approximation to pixelwise relaxivity maps: validation in iron overloaded subjects

PURPOSE

Liver iron quantification by MRI has become routine. Pixelwise (PW) fitting to the iron-mediated signal decay has some advantages but is slower and more vulnerable to noise than region-based techniques. We present a fast, pseudo-pixelwise mapping (PPWM) algorithm.

MATERIALS AND METHODS

The PPWM algorithm divides the entire liver into non-contiguous groups of pixels sorted by rapid relative relaxivity estimates. Pixels within each group of like-relaxivity were binned and fit using a Levenberg-Marquadt algorithm.

RESULTS

The developed algorithm worked about 30 times faster than the traditional PW approach and generated R2* maps qualitatively and quantitatively similar. No systematic difference was observed in median R2* values with a coefficient of variability (CoV) of 2.4%. Intra-observer and inter-observer errors were also under 2.5%. Small systematic differences were observed in the right tail of the R2* distribution resulting in slightly lower mean R2* values (CoV of 4.2%) and moderately lower SD of R2* values for the PPWM algorithm. Moreover, the PPWM provided the best accuracy, giving a lower error of R2* estimates.

CONCLUSION

The PPWM yielded comparable reproducibility and higher accuracy than the TPWM. The method is suitable for relaxivity maps in other organs and applications.

Long-term treatment with deferiprone enhances left ventricular ejection function when compared to deferoxamine in patients with thalassemia major

Transfusion and iron chelation treatment have significantly reduced morbidity and improved survival of patients with thalassemia major. However, cardiac disease continues to be the most common cause of death. We report the left-ventricular ejection fraction, determined by echocardiography, in one hundred sixty-eight patients with thalassemia major followed for at least 5years who received continuous monotherapy with deferoxamine (N=108) or deferiprone (N=60). The statistical analysis, using the generalized estimating equations model, indicated that the group treated with deferiprone had a significantly better left-ventricular ejection fraction than did those treated with deferoxamine (coefficient 0.97; 95% CI 0.37; 1.6, p=0.002). The heart may be particularly sensitive to iron-induced mitochondrial damage because of the large number of mitochondria and its low level of antioxidants. Deferiprone, because of its lower molecular weight, might cross into heart mitochondria more efficiently, improving their activity and, thereby, myocardial cell function. Our findings indicate that the long-term administration of deferiprone significantly enhances left-ventricular function over time in comparison with deferoxamine treatment. However, because of limitations related to the design of this study, these findings should be confirmed in a prospective, randomized clinical trial.

MRI of cardiac iron overload

Transfusion therapy has greatly improved the survival of transfusion dependent thalassemia major (TM) patients; however, the resultant iron load damages tissues including the heart, liver and endocrine organs. Among these, heart complication still remains the leading cause of mortality. Myocardial iron deposition can occur independently of other solid organ involvement; conversely, the heart may be spared despite heavy siderosis in other tissues. Iron chelation treatment diminishes the risk of hemosiderosis; however, the chelation treatment has its own toxicities and might not be available to all patients due to costs. Close monitoring of individual organ iron concentration and function is thus important for optimization of individual patient care. This review outlines the importance and clinical significance of recently available MRI techniques for monitoring cardiac iron load.

Cardiac and hepatic iron and ejection fraction in thalassemia major: multicentre prospective comparison of combined deferiprone and deferoxamine therapy against deferiprone or deferoxamine monotherapy

BACKGROUND

Due to the limited data available in literature, the aim of this multi-centre study was to prospectively compare in thalassemia major (TM) patients the efficacy of combined deferiprone (DFP) and deferoxamine (DFO) regimen versus either DFP and DFO in monotherapy by cardiovascular magnetic resonance (CMR) over a follow up of 18 months.

METHODS

Among the first 1135 TM patients in the MIOT (Myocardial Iron Overload in Thalassemia) network, we evaluated those who had received either combined regimen (DFO + DFP, N=51) or DFP (N=39) and DFO (N=74) monotherapies between the two CMR scans. Iron overload was measured by T2* multiecho technique. Biventricular function parameters were quantitatively evaluated by cine images.

RESULTS

The percentage of patients that maintained a normal global heart T2* value was comparable between DFP+DFO versus both monotherapy groups. Among the patients with myocardial iron overload at baseline, the changes in the global heart T2* and in biventricular function were not significantly different in DFP+DFO compared with the DFP group. The improvement in the global heart T2* was significantly higher in the DFP+DFO than the DFO group, without a difference in biventricular function. Among the patients with hepatic iron at baseline, the decrease in liver iron concentration values was significantly higher with combination therapy than with either monotherapy group.

CONCLUSIONS

In TM patients at the dosages used in the real world, the combined DFP+DFO regimen was more effective in removing cardiac iron than DFO, and was superior in clearing hepatic iron than either DFO or DFP monotherapy. Combined therapy did not show an additional effect on heart function over DFP.

Evaluation of MR imaging with T1 and T2* mapping for the determination of hepatic iron overload

OBJECTIVES

To evaluate MRI using T1 and T2* mapping sequences in patients with suspected hepatic iron overload (HIO).

METHODS

Twenty-five consecutive patients with clinically suspected HIO were retrospectively studied. All underwent MRI and liver biopsy. For the quantification of liver T2* values we used a fat-saturated multi-echo gradient echo sequence with 12 echoes (TR = 200 ms, TE = 0.99 ms +  n × 1.41 ms, flip angle 20°). T1 values were obtained using a fast T1 mapping sequence based on an inversion recovery snapshot FLASH sequence. Parameter maps were analysed using regions of interest.

RESULTS

ROC analysis calculated cut-off points at 10.07 ms and 15.47 ms for T2* in the determination of HIO with accuracy 88 %/88 %, sensitivity 84 %/89.5 % and specificity 100 %/83 %. MRI correctly classified 20 patients (80 %). All patients with HIO only had decreased T1 and T2* relaxation times. There was a significant difference in T1 between patients with HIO only and patients with HIO and steatohepatitis (P = 0.018).

CONCLUSIONS

MRI-based T2* relaxation diagnoses HIO very accurately, even at low iron concentrations. Important additional information may be obtained by the combination of T1 and T2* mapping. It is a rapid, non-invasive, accurate and reproducible technique for validating the evidence of even low hepatic iron concentrations.

KEY POINTS

• Hepatic iron overload causes fibrosis, cirrhosis and increases hepatocellular carcinoma risk. • MRI detects iron because of the field heterogeneity generated by haemosiderin. • T2* relaxation is very accurate in diagnosing hepatic iron overload. • Additional information may be obtained by T1 and T2* mapping.

Deferasirox for up to 3 years leads to continued improvement of myocardial T2* in patients with β-thalassemia major

BACKGROUND

Prospective data on cardiac iron removal are limited beyond one year and longer-term studies are, therefore, important.

DESIGN AND METHODS

Seventy-one patients in the EPIC cardiac substudy elected to continue into the 3(rd) year, allowing cardiac iron removal to be analyzed over three years.

RESULTS

Mean deferasirox dose during year 3 was 33.6 ± 9.8 mg/kg per day. Myocardial T2*, assessed by cardiovascular magnetic resonance, significantly increased from 12.0 ms ± 39.1% at baseline to 17.1 ms ± 62.0% at end of study (P<0.001), corresponding to a decrease in cardiac iron concentration (based on ad hoc analysis of T2*) from 2.43 ± 1.2 mg Fe/g dry weight (dw) at baseline to 1.80 ± 1.4 mg Fe/g dw at end of study (P<0.001). After three years, 68.1% of patients with baseline T2* 10 to <20 ms normalized (≥ 20 ms) and 50.0% of patients with baseline T2* >5 to <10 ms improved to 10 to <20 ms. There was no significant variation in left ventricular ejection fraction over the three years. No deaths occurred and the most common investigator-assessed drug-related adverse event in year 3 was increased serum creatinine (n = 9, 12.7%).

CONCLUSIONS

Three years of deferasirox treatment along with a clinically manageable safety profile significantly reduced cardiac iron overload versus baseline and normalized T2* in 68.1% (32 of 47) of patients with T2* 10 to <20 ms.

Assessment of iron overload with T2* magnetic resonance imaging

T2* is a magnetic relaxation property of any tissue and is inversely related to intracellular iron stores. Measurement is simple, quick, and robust and has high reproducibility. The ability to measure ventricular function plus T2* in the heart and liver during the same scan has revolutionized the understanding of iron storage disease and the management of the iron-loaded patient. The early findings using T2* challenged conventional teachings, and both the technique and the findings were initially viewed with scepticism. However, after a decade of work in validating, calibrating, and expanding access to this method, it is now accepted as the method of choice for tissue iron assessment. In the UK, where T2* measurement was first used in the clinical care of patients with thalassemia major, a large and significant fall in mortality has been seen in this patient group.

Feasibility, reproducibility, and reliability for the T*2 iron evaluation at 3 T in comparison with 1.5 T

This study aimed to determine the feasibility, reproducibility, and reliability of the multiecho T*(2) Magnetic resonance imaging technique at 3 T for myocardial and liver iron burden quantification and the relationship between T*(2) values at 3 and 1.5 T. Thirty-eight transfusion-dependent patients and 20 healthy subjects were studied. Cardiac segmental and global T*(2) values were calculated after developing a correction map to compensate the artifactual T*(2) variations. The hepatic T*(2) value was determined over a region of interest. The intraoperator and interoperator reproducibility for T*(2) measurements at 3 T was good. A linear relationship was found between patients' R *2 (1000/T*(2) ) values at 3 and 1.5 T. Segmental correction factors were significantly higher at 3 T. A conversion formula returning T*(2) values at 1.5 T from values at 3 T was proposed. A good diagnostic reliability for T*(2) assessment at 3 T was demonstrated. Lower limits of normal for 3 T T*(2) values were 23.3 ms, 21.1 ms, and 11.7 ms, for the global heart, mid-ventricular septum, and liver, respectively. In conclusion, T*(2) quantification of iron burden in the mid-ventricular septum, global heart, and no heavy-moderate livers resulted to be feasible, reproducible, and reliable at 3 T. Segmental heart T*(2) analysis at 3 T may be challenging due to significantly higher susceptibility artifacts.

Unenhanced fat fraction ratios obtained by MR and enhanced T2* values with liver-specific MR contrast agents for diagnosis of non-alcoholic steatohepatitis in rats

BACKGROUND

Non-invasive MR imaging is expected to be used for accurate diagnosis and quantification of non-alcoholic steatohepatitis (NASH), because NASH is a progressive fatty liver disease. New MR techniques, such as fat fraction ratio (FFR) and T2* value measurement, have attracted an increasing attention, because those techniques can measure quantitative parameters of fibrosis, fat and iron deposition in the liver.

PURPOSE

To investigate the potential of FFR and T2* value in NASH with pre-enhancement, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) or super-paramagnetic iron oxide (SPIO)-enhanced MRI.

MATERIAL AND METHODS

Twenty-eight rats were divided equally into four groups (one control group and three NASH groups). All rats underwent unenhanced, Gd-EOB-DTPA, and SPIO-enhanced MRI. The T2* value of the liver was measured for each image sequence, and then changes in T2* values before and after each injection were analyzed using Dunnett's test. The reduction rate of T2* value before and 13 min after injection of Gd-EOB-DTPA or SPIO was analyzed using Mann-Whitney's U test. Moreover, FFR of the liver was measured before enhancement, and the relationship between fat fraction and the calculated fat area percentage on a pathological specimen was examined using Spearman's correlation test.

RESULTS

On pre-enhancement, FFR and T2* value were 26.0% ± 12.0% and 21.5 ± 4.2 ms for all NASH groups, and 0.9% ± 0.5% and 30.8 ±-5.5 ms for control, respectively. Both FFR and T2* values were significantly different between the NASH and control groups. The reduction rate of T2* value was significantly lower in the NASH groups than in the control group on SPIO-enhanced MRI, though there was no significant difference on Gd-EOB-DTPA-enhanced MRI. FFR was correlated with the calculated fat area percentage for the pathological specimen.

CONCLUSION

Pre-enhancement FFR, T2* value measurement and reduction rate of T2* value on SPIO-enhanced MRI may help estimate the progress of liver fat deposition and fibrosis in NASH.

Ferritin as a reporter gene for in vivo tracking of stem cells by 1.5-T cardiac MRI in a rat model of myocardial infarction

The methods currently utilized to track stem cells by cardiac MRI are affected by important limitations, and new solutions are needed. We tested human ferritin heavy chain (hFTH) as a reporter gene for in vivo tracking of stem cells by cardiac MRI. Swine cardiac stem/progenitor cells were transduced with a lentiviral vector to overexpress hFTH and cultured to obtain cardiospheres (Cs). Myocardial infarction was induced in rats, and, after 45 min, the animals were subjected to intramyocardial injection of ∼200 hFTH-Cs or nontransduced Cs or saline solution in the border zone. By employing clinical standard 1.5-Tesla MRI scanner and a multiecho T2* gradient echo sequence, we localized iron-accumulating tissue only in hearts treated with hFTH-Cs. This signal was detectable at 1 wk after infarction, and its size did not change significantly after 4 wk (6.33 ± 3.05 vs. 4.41 ± 4.38 mm2). Cs transduction did not affect their cardioreparative potential, as indicated by the significantly better preserved left ventricular global and regional function and the 36% reduction in infarct size in both groups that received Cs compared with control infarcts. Prussian blue staining confirmed the presence of differentiated, iron-accumulating cells containing mitochondria of porcine origin. Cs-derived cells displayed CD31, α-smooth muscle, and α-sarcomeric actin antigens, indicating that the differentiation into endothelial, smooth muscle and cardiac muscle lineage was not affected by ferritin overexpression. In conclusion, hFTH can be used as a MRI reporter gene to track dividing/differentiating stem cells in the beating heart, while simultaneously monitoring cardiac morpho-functional changes.

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.

Observational study of iron overload as assessed by magnetic resonance imaging in an adult population of transfusion-dependent patients with beta thalassaemia: significant association between low cardiac T2* < 10 ms and cardiac events

BACKGROUND

Thalassaemia major patients usually die from cardiac haemosiderosis. Improved strategies are required to modify this risk.

AIMS

To assess the significance of cardiac iron overload in patients with beta thalassaemia.

METHOD

Observational study of cardiac iron overload as assessed by magnetic resonance imaging (MRI) cardiac T2* relaxometry in 30 adult patients with transfusion-dependent beta thalassaemia.

RESULTS

11/30 patients (37%) had cardiac T2* < 10 ms, 8/30 (27%) in range 10-20 ms and 11/30 (37%) > 20 ms. There was significant inverse correlation between T2* values and values for serum ferritin (SF) and liver iron concentration (LIC) and positive correlation with left ventricular ejection fraction (LVEF). Median LVEF values were 49% in patients with T2* < 10 ms and 58% in patients with T2* > 10 ms (P = 0.02). Very low T2* values <10 ms were strongly associated with the occurrence of cardiac events (congestive heart failure, arrhythmia, cardiac death): occurring in 5/11 patients with T2* < l0 ms and in 0/19 in patients with T2* > 10 ms (P = 0.003 Fisher's exact test; P = 0.002 log rank Kaplan-Meier time to event analysis). There was no significant association between T2* < 10 ms or cardiac events and traditional measures of iron overload, such as SF levels >2500 mg/L and LIC (evaluated at thresholds of >7 or >15 mg/g dry weight).

CONCLUSION

Very low cardiac T2* values <10 ms are common in adults with beta thalassaemia and are significantly associated with risk of cardiac events. This permits the use of individually targeted chelation strategies which are more effective in removing cardiac iron.

Regional and global pancreatic T*2 MRI for iron overload assessment in a large cohort of healthy subjects: normal values and correlation with age and gender

Multiecho gradient-echo T*2 magnetic resonance imaging is a well-established technique for iron overload assessment but there are few reports concerning the pancreas. The aim of this work was to assess the feasibility and reproducibility of the magnetic resonance imaging for measuring pancreatic regional and global T*2 values, to establish the lower limit of normal in a large cohort of healthy subjects and to correlate the measured values with age and gender. One hundred and twenty healthy subjects (61 males, 51±17 years) underwent magnetic resonance imaging (1.5T) using a multiecho gradient-echo T*2 sequence. T*2 measurements were performed in pancreatic head, body, and tail. The global value was calculated as the mean. Measurement of pancreatic T*2 values was feasible in all subjects. For the T*2 global value the coefficient of variation for intraoperator and interoperator reproducibility were 7.7% and 13%, respectively. The global T*2 values ranged from 24 to 52 ms with the lower limit of normal of 26 ms. There were no significant differences among the regional pancreatic T*2 values. No significant correlation was found between T*2 and patient age or gender. In conclusion, pancreatic T*2 measurements appear to be feasible, reproducible, nontime-consuming and reliable. Gender- and age-related differences concerning pancreatic T*2 were not found.

Preferential patterns of myocardial iron overload by multislice multiecho T*2 CMR in thalassemia major patients

T*(2) multislice multiecho cardiac MR allows quantification of the segmental distribution of myocardial iron overload. This study aimed to determine if there were preferential patterns of myocardial iron overload in thalassemia major. Five hundred twenty-three thalassemia major patients underwent cardiac MR. Three short-axis views of the left ventricle were acquired and analyzed using a 16-segment standardized model. The T*(2) value on each segment was calculated, as well as the global value. Four main circumferential regions (anterior, septal, inferior, and lateral) were defined. Significant segmental variability was found in the 229 patients with significant myocardial iron overload (global T*(2) <26 ms), subsequently divided into two groups: severe (global T*(2) <10 ms) and mild to moderate (global T*(2) between 10 and 26 ms) myocardial iron overload. A preferential pattern of iron store in anterior and inferior regions was detected in both groups. This pattern was preserved among the slices. The pattern could not be explained by additive susceptibility artifacts, negligible in heavily iron-loaded patients. A significantly higher T*(2) value in the basal slice was found in patients with severe iron overload. In conclusion, a segmental T*(2) cardiac MR approach could identify early iron deposit, useful for tailoring chelation therapy and preventing myocardial dysfunction in the clinical setting.

Deferasirox, deferiprone and desferrioxamine treatment in thalassemia major patients: cardiac iron and function comparison determined by quantitative magnetic resonance imaging

BACKGROUND

Oral deferiprone was suggested to be more effective than subcutaneous desferrioxamine for removing heart iron. Oral once-daily chelator deferasirox has recently been made commercially available but its long-term efficacy on cardiac iron and function has not yet been established. Our study aimed to compare the effectiveness of deferasirox, deferiprone and desferrioxamine on myocardial and liver iron concentrations and bi-ventricular function in thalassemia major patients by means of quantitative magnetic resonance imaging.

DESIGN AND METHODS

From the first 550 thalassemia subjects enrolled in the Myocardial Iron Overload in Thalassemia network, we retrospectively selected thalassemia major patients who had been receiving one chelator alone for longer than one year. We identified three groups of patients: 24 treated with deferasirox, 42 treated with deferiprone and 89 treated with desferrioxamine. Myocardial iron concentrations were measured by T2* multislice multiecho technique. Biventricular function parameters were quantitatively evaluated by cine images. Liver iron concentrations were measured by T2* multiecho technique.

RESULTS

The global heart T2* value was significantly higher in the deferiprone (34 ± 11 ms) than in the deferasirox (21 ± 12 ms) and the desferrioxamine groups (27 ± 11 ms) (P = 0.0001). We found higher left ventricular ejection fractions in the deferiprone and the desferrioxamine versus the deferasirox group (P = 0.010). Liver iron concentration, measured as T2* signal, was significantly lower in the desferrioxamine versus the deferiprone and the deferasirox group (P = 0.004).

CONCLUSIONS

The cohort of patients treated with oral deferiprone showed less myocardial iron burden and better global systolic ventricular function compared to the patients treated with oral deferasirox or subcutaneous desferrioxamine.

Beta-thalassemia cardiomyopathy: history, present considerations, and future perspectives

Beta-thalassemia is an inherited hemoglobin disorder resulting in chronic hemolytic anemia that typically requires life-long transfusion therapy. Although traditionally prevalent in the Mediterranean basin, Middle East, North India, and Southeast Asia, immigration of those populations to North America and Western Europe has rendered beta-thalassemia a global health problem. Cardiac complications represent the primary cause of mortality and one of the major causes of morbidity in those patients. Heart disease is mainly expressed by a particular cardiomyopathy that progressively leads to heart failure and death. The beta-thalassemia cardiomyopathy is mainly characterized by 2 distinct phenotypes, a dilated phenotype, with left ventricular dilatation and impaired contractility and a restrictive phenotype, with restrictive left ventricular filling, pulmonary hypertension, and right heart failure. The pathophysiology of the disorder is multifactorial, with a central role of myocardial iron overload and the significant contribution of immunoinflammatory mechanisms. Patients' management is demanding and requires a multidisciplinary approach, preferably in specialized centers.

Right ventricular volumes and function in thalassemia major patients in the absence of myocardial iron overload

AIM

We aimed to define reference ranges for right ventricular (RV) volumes, ejection fraction (EF) in thalassemia major patients (TM) without myocardial iron overload.

METHODS AND RESULTS

RV volumes, EF and mass were measured in 80 TM patients who had no myocardial iron overload (myocardial T2* > 20 ms by cardiovascular magnetic resonance). All patients were receiving deferoxamine chelation and none had evidence of pulmonary hypertension or other cardiovascular comorbidity. Forty age and sex matched healthy non-anemic volunteers acted as controls. The mean RV EF was higher in TM patients than controls (males 66.2 +/- 4.1% vs 61.6 +/- 6%, p = 0.0009; females 66.3 +/- 5.1% vs 62.6 +/- 6.4%, p = 0.017), which yielded a raised lower threshold of normality for RV EF in TM patients (males 58.0% vs 50.0% and females 56.4% vs 50.1%). RV end-diastolic volume index was higher in male TM patients (mean 98.1 +/- 17.3 mL vs 88.4 +/- 11.2 mL/m2, p = 0.027), with a higher upper limit (132 vs 110 mL/m2) but this difference was of borderline significance for females (mean 86.5 +/- 13.6 mL vs 80.3 +/- 12.8 mL/m2, p = 0.09, with upper limit of 113 vs 105 mL/m2). The cardiac index was raised in TM patients (males 4.8 +/- 1.0 L/min vs 3.4 +/- 0.7 L/min, p < 0.0001; females 4.5 +/- 0.8 L/min vs 3.2 +/- 0.8 L/min, p < 0.0001). No differences in RV mass index were identified.

CONCLUSION

The normal ranges for functional RV parameters in TM patients with no evidence of myocardial iron overload differ from healthy non-anemic controls. The new reference RV ranges are important for determining the functional effects of myocardial iron overload in TM patients.

Liver iron content determination by magnetic resonance imaging

Accurate evaluation of iron overload is necessary to establish the diagnosis of hemochromatosis and guide chelation treatment in transfusion-dependent anemia. The liver is the primary site for iron storage in patients with hemochromatosis or transfusion-dependent anemia, therefore, liver iron concentration (LIC) accurately reflects total body iron stores. In the past 20 years, magnetic resonance imaging (MRI) has emerged as a promising method for measuring LIC in a variety of diseases. We review the potential role of MRI in LIC determination in the most important disorders that are characterized by iron overload, that is, thalassemia major, other hemoglobinopathies, acquired anemia, and hemochromatosis. Most studies have been performed in thalassemia major and MRI is currently a widely accepted method for guiding chelation treatment in these patients. However, the lack of correlation between liver and cardiac iron stores suggests that both organs should be evaluated with MRI, since cardiac disease is the leading cause of death in this population. It is also unclear which MRI method is the most accurate since there are no large studies that have directly compared the different available techniques. The role of MRI in the era of genetic diagnosis of hemochromatosis is also debated, whereas data on the accuracy of the method in other hematological and liver diseases are rather limited. However, MRI is a fast, non-invasive and relatively accurate diagnostic tool for assessing LIC, and its use is expected to increase as the role of iron in the pathogenesis of liver disease becomes clearer.

Multicenter validation of the magnetic resonance T2* technique for segmental and global quantification of myocardial iron

PURPOSE

To assess the transferability of the magnetic resonance imaging (MRI) multislice multiecho T2(*) technique for global and segmental measurement of iron overload in thalassemia patients.

MATERIALS AND METHODS

Multiecho T2(*) sequences were installed on six MRI scanners. Five healthy subjects (n = 30) were scanned at each site; five thalassemia major (TM) patients were scanned at the reference site and were rescanned locally (n = 25) within 1 month. T2(*) images were analyzed using previously validated software.

RESULTS

T2(*) values of healthy subjects showed intersite homogeneity. On TM patients, for global heart T2(*) values the correlation coefficient was 0.97, coefficients of variation (CoV(s)) ranged from 0.04-0.12, and intraclass coefficients (ICC(s)) ranged from 0.94-0.99. The mean CoV and ICC for segmental T2(*) distribution were 0.198 and 88, respectively.

CONCLUSION

The multislice multiecho T2(*) technique is transferable among scanners with good reproducibility.

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.

On using T2 to assess extrinsic magnetic field inhomogeneity effects on T2* measurements in myocardial siderosis in thalassemia

Magnetic resonance T(2)* has been validated as a noninvasive means of assessing myocardial iron overload. However, the effect on myocardial T(2)* of factors such as shimming, variations in capillary geometry, and susceptibility in relation to the effects of iron has not been fully clarified. Since T(2) is not affected by extrinsic magnetic field inhomogeneity and has different sensitivity to capillary geometry, investigation into the in vivo relationship between myocardial T(2)* and T(2) measurements can shed light on this important issue. This study was performed in 136 thalassemia patients. The myocardial T(2) and T(2)* thresholds for normality created identical no-iron-overload and iron-overloaded patient groups. In the no-iron group, there was no correlation between myocardial T(2) and T(2)*. In the iron-overloaded patients, there was a linear correlation (R(2) = 0.89) between myocardial T(2)* and T(2) measurements, which indicates that the iron deposition is the dominant factor in determining these two relaxation values in this scenario.

Evaluation of a web-based network for reproducible T2* MRI assessment of iron overload in thalassemia

PURPOSE

To build and evaluate a national network able to improve the care of thalassemia, a genetic disorder in haemoglobin synthesis often associated with iron accumulation in a variety of organs, due to the continuous blood transfusions.

METHODS

The MIOT (Myocardial Iron Overload in Thalassemia) network is constituted by thalassemia and magnetic resonance imaging (MRI) centers. Thalassemia centers are responsible for patient recruitment and collection of anamnestic and clinical data. MRI centers have been equipped with a standardized acquisition technique and an affordable workstation for image analysis. They are able to perform feasible and reproducible heart and liver iron overload assessments for a consistent number of thalassemia patients in a robust manner. All centers are linked by a web-based network, configured to collect and share patient data.

RESULTS

On 30th March 2008, 695 thalassemia patients were involved in the network. The completion percentage of the patient records in the database was 85+/-6.5%. Six hundred and thirteen patients (88%) successfully underwent MRI examination. Each MRI center had a specific absorption capacity that remained constant over time, but the network was capable of sustaining an increasing number of patients due to continuous enrollment of new centers. The patient's comfort, assessed as the mean distance from the patient home locations to the MRI centers, significantly increased during the network's evolution.

CONCLUSION

The MIOT network seems to be a robust and scalable system in which T2* MRI-based cardiac and liver iron overload assessment is available, accessible and reachable for a significant and increasing number of thalassemia patients in Italy (about 420 per year), reducing the mean distance from the patient locations to the MRI sites from 951km to 387km. A solid, wide and homogeneous database will constitute an important scientific resource, shortening the time scale for diagnostic, prognostic and therapeutical evidence-based research on the management of thalassemia disease.

Myocardial T2* measurements in iron-overloaded thalassemia: An in vivo study to investigate optimal methods of quantification

Reproducible and accurate myocardial T2* measurements are required for the quantification of iron in heart tissue in transfused thalassemia. The aim of this study was to determine the best method to measure the myocardial T2* from multi-gradient-echo data acquired both with and without black-blood preparation. Sixteen thalassemia patients from six centers were scanned twice locally, within 1 week, using an optimized bright-blood T2* sequence and then subsequently scanned at the standardization center in London within 4 weeks, using a T2* sequence both with and without black-blood preparation. Different curve-fitting models (monoexponential, truncation, and offset) were applied to the data and the results were compared by means of reproducibility. T2* measurements obtained using the bright- and black-blood techniques. The black-blood data were well fitted by the monoexponential model, which suggests that a more accurate measure of T2* can be obtained by removing the main source of errors in the bright-blood data. For bright-blood data, the offset model appeared to underestimate T2* values substantially and was less reproducible. The truncation model gave rise to more reproducible T2* measurements, which were also closer to the values obtained from the black-blood data.

Magnetic Resonance T2* Technique for Segmental and Global Quantification of Myocardial Iron : Multi-Centre Validation in the MIOT (Myocardial Iron Overload in Thalassemia) Network

Iron induced cardiomiopathy is the main cause of mortality in thalassemic population. Thus, the improvement of chelation regimens, to reduce cardiac disease, has the highest priority. Efficient evaluation of cardiac iron status and careful epidemiologic assessment of thalassemic patients play an important role in this matter. T2* magnetic resonance imaging (MRI) is a unique technique to quantify myocardial iron overload and useful to tailor the chelation therapy. Effective and reproducible assessment of myocardial iron loading using the multislice multiecho T2* approach for segmental and global myocardial iron distribution, has been demonstrated at the MRI centre in Pisa [1,2]. Aim of this work is to build within the MIOT (Myocardial Iron Overload in Thalassemia) project a reliable network of haematological and paediatric centers specializing in thalassemia care and MRI centers able to perform feasible and reproducible heart and liver iron overload assessments for a consistent number of thalassemia patients in a standardized and robust manner.

First, the transferability of the multislice multiecho T2* technique was assessed. Heart multislice multiecho T2* and liver multiecho T2* sequences were installed on 1.5 T MRI scanners (GE Healthcare) at six different sites in Italy. Five healthy subjects at each site (n=30) were scanned to verify the homogeneity of normal ranges (T2* lover limit of normal 20ms). Then, five thalassemia major (TM) patients were scanned at the reference site and were rescanned locally (n=25) within one month. T2* images were analysed using a previously validated software (HIPPO MIOT®). T2* values of healthy subjects showed inter-sites homogeneity. On TM patients, for global heart T2* values the correlation coefficient was 0.97, Coefficients of Variation (CoVs) ranged from 0.04 to 0.12 and Intraclass Coefficients (ICCs) ranged from 0.94 to 0.99. The mean CoV and ICC for segmental T2* distribution were 0.198 and 88, respectively.

After the assessment of MRI technique reproducibility, patients enrolling started in September 2006. Since the project’s beginning, 695 thalassemia patients have been involved in the network. Six hundred and thirteen patients (88%) successfully underwent MRI examination. Each MRI center had a specific absorption capacity that seemed to remain constant over time, but the network was capable of sustaining an increasing number of patients due to continuous enrolment of new centers. The mean distance from the patients’ home locations to the MRI centers where the patients underwent the exams, which is considered an indicator of patient comfort, significantly decreased during the network’s evolution. In Figure, the average distances from the thalassemia centers which sent the patients for MRI examination are plotted versus time. With the activation of delocalized MRI centers, average distances tend to be comparable.

In conclusion, the multislice multiecho T2* technique is transferable among scanners with good reproducibility. The MIOT network seems to be a robust and scalable system in which T2* MRI-based cardiac and liver iron overload assessment is available, accessible and reachable for a significant and increasing number of thalassemia patients in Italy, reducing the mean distance from the patients’ locations to the MRI sites. A solid, wide and homogeneous database will constitute an important scientific resource, shortening the time scale for diagnostic, prognostic and therapeutical evidence-based research on the management of thalassemia disease.

Figure Figure

Myocardial T*2 measurement in iron-overloaded thalassemia: an ex vivo study to investigate optimal methods of quantification

Myocardial T*2 measurement has been increasingly used for iron quantification to assess the risk of cardiac complications in thalassemia patients. In this study the noise effects were evaluated along with different curve-fitting models on an iron overloaded ex vivo heart in order to determine the optimal method of T*2 measurement and to help understand issues affecting reproducibility and accuracy. Gradient multiecho short axis images were acquired with differing numbers of excitations to generate varying signal-to-noise ratio (SNR) images. A noise correction method was implemented; linear and nonlinear curve-fitting algorithms were compared and different curve-fitting models (monoexponential, truncation, baseline subtraction, and offset) were evaluated. This study suggests that the T*2 decay curve in an ex vivo heart can be fitted by a monoexponential model and accurate T*2 measurements can be obtained with proper noise correction. With MRI noise, T*2 is generally overestimated by including late low SNR data points, but underestimated by the offset or baseline subtraction models, which are in fact equivalent. In this situation the truncation model proves to be reproducible and more accurate than the other models. The study also shows that the nonlinear algorithm is preferred in T*2 curve fitting.

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.