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

Meloni, Antonella; Luciani, A.; Positano, Vincenzo; Marchi, Daniele De; Valeri, Gianluca; Restaino, Gennaro; Cracolici, Eliana; Caruso, Vincenzo; Dell’Amico, Maria Chiara; Favilli, Brunella; Lombardi, Massimo; Pepe, Alessia

doi:10.1002/jmri.22417

Cited by 77 publications

(69 citation statements)

References 25 publications

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“…Meloni et al demonstrated that liver T2* variations were limited and when present they were secondary to artifact or measurement variability [14]. In an attempt to negate the presence of any sampling bias, we calculated average T2* values obtained from nine ROI, divided into seven wedges.…”

Section: Discussionmentioning

confidence: 99%

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

Clarke¹,

Kidson‐Gerber²,

Moses³

et al. 2016

Journal of Hematology and Blood Disorders

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Research ArticleOpen Access Regular transfusion in thalassaemia major results in progressive iron overload and its complications. Chelation therapy can prevent these complications and has been pivotal in the improved survival of these patients. With inadequate chelation, cardiac arrhythmias and cardiomyopathy are the predominant causes of death, while endocrinopathies and cirrhosis contribute to both morbidity and mortality [1][2][3]. Each chelating agent has potential risks and benefits. The accurate assessment of iron overload is therefore critical in guiding the appropriate choice of therapy and in managing adherence. AbstractRelaxometry based Magnetic Resonance Imaging (MRI) techniques have increasingly been adopted as a means of non invasive measurement of tissue iron concentration in patients with transfusion dependent thalassaemia. Currently, different MRI techniques are utilised to assess cardiac and hepatic iron concentrations, which correlate poorly. In an attempt to simplify the assessment of tissue iron concentration, we prospectively compared T2* MRI with R2 (FerriScan®) derived liver iron concentration. A strong correlation exists between these two modalities, particularly at lower iron burdens. These findings would enable the concurrent assessment of cardiac and liver iron concentration thus streamlining total body iron assessment. Method: 34 patients with β-thalassemia major underwent MRI assessment. R2 and T2* images were generated concurrently and R2 LIC calculated. Data was analysed with SAS/STAT 9. Conclusion:These results indicate there is a strong correlation between T2* MRI and R2 generated LIC. These findings have the potential to streamline iron assessment by facilitating the concurrent assessment of cardiac and liver iron concentration.

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Section: Discussionmentioning

confidence: 99%

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

Clarke¹,

Kidson‐Gerber²,

Moses³

et al. 2016

Journal of Hematology and Blood Disorders

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“…Another limitation of our method could be that it is an ROI-based method. Meloni et al evaluated the effectiveness of the single ROI approach and found that it slightly underestimates liver iron quantification due to susceptibility artifacts when the ROI was placed over segments VII and VIII [28]. They concluded that the single ROI approach can be safely used in the clinical area when taking care to avoid susceptibility artifact effect.…”

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confidence: 99%

R2* Relaxometry for the Quantification of Hepatic Iron Overload: Biopsy-Based Calibration and Comparison with the Literature

Henninger

Zoller

Rauch

et al. 2015

Fortschr Röntgenstr

107

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We compared the calibration of hepatic iron based on R2* relaxometry and liver biopsy with similar studies that have already been published to investigate the transferability of published calibration curves. Materials and Methods: 17 patients with clinically suspected hepatic iron overload (HIO) were enrolled. All patients underwent liver biopsy and MRI of the liver using a multi-echo gradient echo sequence (TR = 200 ms; TE-initial 0.99 ms; Delta-TE 1.41 ms; 12 echos; flip-angle: 20°). R2* parameter maps were analyzed using manually placed regions of interest and R2* values were correlated with liver iron concentration (LIC) obtained from liver biopsy. In addition, the results of our study were compared with 6 similar, already published studies. Results: A linear relationship between R2* and LIC was found. Regression analysis yielded a correlation coefficient of 0.926, a slope of 0.024 (s mg/g) [95 % CI 0.013 -0.024] and an intercept of 0.277 (mg/g) [95 % CI -0.328 -2.49]. We found a significant correlation between the calibration curves obtained from our study in comparison to 3/6 similar studies. The other 3 studies used a different reference standard or sequence parameters which lead to a significant difference for slope, intercept or both in comparison to our data. Conclusion: Calibration curves from published studies that are based on a correlation of liver biopsy and R2* can be used for the estimation of liver iron concentration, although different scanning parameters and post-processing protocols were used. Low initial TEs might be a prerequisite for pooling data for liver iron quantification.

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“…Alternatives are global analysis including the full extent of the liver within the slice, but excluding obvious major hilar vessels [5, 15], and ROI defined in an area of homogeneous liver tissue, avoiding blood vessels and other sources of artifacts [16–18]. …”

Section: Methodsmentioning

confidence: 99%

“…Alternatives are averaged-signal or region-based analysis, where pixels within the ROI are averaged together and fit is performed for this averaged decay curve [17, 18], and pixelwise analysis, where fitting is performed for each pixel within the ROI and the median of the distribution of R2* values is calculated [5, 15]. …”

Section: Methodsmentioning

confidence: 99%

“…One alternative to the curve-fitting model is a three-parameter model, which includes an exponential with a variable offset [5, 16, 18], calculated as follows:

S = S_{0} e^{- T E \cdot R 2 *} + C,

where S is signal intensity, S 0 is signal intensity at TE of 0, TE is TE, and C is constant offset that corrects for contributions for blood, bile, motion artifact, and noise bias. The other alternative to the curve-fitting model is a two-parameter model, with a single exponential model (Equation 1 without the constant C ) [17].…”

Section: Methodsmentioning

confidence: 99%

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Effect of Inversion Recovery Fat Suppression on Hepatic R2* Quantitation in Transfusional Siderosis

Meloni

Tyszka²,

Pepe³

et al. 2015

American Journal of Roentgenology

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OBJECTIVE The purpose of this study is to evaluate whether the application of spectral presaturation inversion recovery (SPIR) fat suppression in standard multiecho gradient-echo sequences has a significant effect on hepatic R2* quantitation in patients with iron overload syndromes. MATERIALS AND METHODS Eighty patients were scanned with a multiecho gradient-echo sequence without and with the application of SPIR. Six different postprocessing approaches were used to extract R2* values for maximum generality. RESULTS SPIR fat suppression lowered R2* values by 3.9–7.0% (p < 0.0001 in all pairwise comparisons), independently of the postprocessing algorithm. Coefficients of variation for R2* ranged from 4.5% to 10.0%. Regardless of the size of the ROI (area of homogeneous tissue or entire liver profile in the slice), pixelwise approaches combined with an exponential-plus-constant fitting model yielded the lowest coefficients of variation (4.5% and 5.1%), whereas truncated exponential fits of the averaged signals produced the highest coefficients of variation (7.8% and 10%). For R2* values exceeding 200 Hz, a Bland-Altman analysis showed a bias that grew linearly for all postprocessing methods. CONCLUSION SPIR fat suppression resulted in systematically lower hepatic R2* estimates. Because calibration curves were derived using images without fat suppression, these biases should be corrected when reporting liver iron concentrations estimated from fat-suppressed multiecho T2*-weighted images.

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

Cited by 77 publications

References 25 publications

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

T2* MRI Correlates with R2 Liver Iron Concentration in Transfusion Dependent Thalassaemia

R2* Relaxometry for the Quantification of Hepatic Iron Overload: Biopsy-Based Calibration and Comparison with the Literature

Effect of Inversion Recovery Fat Suppression on Hepatic R2* Quantitation in Transfusional Siderosis

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