Interscanner reproducibility of cardiovascular magnetic resonance T2* measurements of tissue iron in thalassemia

Westwood, Mark; Anderson, Lisa; Firmin, David N.; Gatehouse, Peter; Lorenz, Christine H.; Wonke, B; Pennell, Dudley J.

doi:10.1002/jmri.10396

Cited by 148 publications

(120 citation statements)

References 13 publications

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“…They concluded that the T2* technique is transferable between MR scanners with good reproducibility. Inter-study reproducibility has also been evaluated by Westwood et al, but only for T2* sequences for the heart -high transferability between scanners from different manufactures and between different sites could be demonstrated [26]. Our present data seem to support this finding.…”

supporting

confidence: 84%

“…Another explanation may be found in the different scanner types that were used. Westwood et al found slightly higher T2* relaxation times of the heart in normal subjects with a scanner from the same manufacturer as the one used in the An- derson study compared to a scanner from the manufacturer that was used in our study [26]. Virtanen et al compared R2* measurements with iron estimates based on the SIR method and obtained a highly linear correlation (r = 0.981) [15].…”

mentioning

confidence: 59%

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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

101

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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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supporting

confidence: 84%

mentioning

confidence: 59%

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

101

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“…Data were acquired on a Siemens Symphony Quantum 1.5T scanner using a multiple echo spoiled GRE sequence capable of sampling on the forward and reverse gradients (19). Up to 16 TEs were acquired in a single TR with minimum TE 2.3 ms and interecho spacing 2.3 ms.…”

Section: Mr Examinationmentioning

confidence: 99%

Relaxation effects in the quantification of fat using gradient echo imaging

Bydder

Yokoo

Hamilton

et al. 2008

Magnetic Resonance Imaging

360

577

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Quantification of fat has been investigated using images acquired from multiple gradient echos. The evolution of the signal with echo time and flip angle was measured in phantoms of known fat and water composition and in 21 research subjects with fatty liver. Data were compared to different models of the signal equation, in which each model makes different assumptions about the T1 and/ or T2* relaxation effects. A range of T1, T2*, fat fraction and number of echos was investigated to cover situations of relevance to clinical imaging. Results indicate that quantification is most accurate at low flip angles (to minimize T1 effects) with a small number of echos (to minimize spectral broadening effects). At short echo times the spectral broadening effects manifest as a short apparent T2 for the fat component.

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“…The second, liver R2* analysis, relies on more loosely standardized image acquisitions, but nonetheless demonstrate superb reproducibility [6][7][8][9]. Original validation studies were smaller [6,10], 21 and 43 patients respectively, but had better limits of agreement [246% to 44%] and [239 to 45%].…”

Section: Introductionmentioning

confidence: 99%

R2 and R2* are equally effective in evaluating chronic response to iron chelation

et al. 2014

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MRI relaxometry (R2, R2*) has generally replaced liver biopsy for estimation of liver iron stores in response to iron chelation, but there have been no longitudinal studies comparing R2 and R2* techniques. We use R2 and R2* liver iron concentration (LIC) estimates, transfusional iron burdens, and drug compliance data to calculate iron chelation efficiency (ICE) in patients undergoing a Phase II trial of SPD602. Fifty-one patients underwent a baseline examination, 39 patients completed 1 year, and 26 patients completed 2 years. Baseline LIC R2 and LIC R2* estimates were unbiased, but had limits of agreement exceeding 50%, suggesting that these techniques cannot be interchanged with one another in the same patient. However, ICE estimates across the two techniques compared more favorably, with r 2 values reaching 0.89 at 2 years. 95 confidence intervals for efficiency estimates were 0.0 6 4.1%. These data indicate that clinical trial and clinical effectiveness data calculated using LIC R2 and LIC R2* estimates can be compared to one another, even though LIC estimates may be disparate on cross-sectional analysis. While the choice of MRI assessment technique for clinical trials and for clinical management depends on many logistical considerations, one can have confidence comparing conclusions on clinical effectiveness.

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Interscanner reproducibility of cardiovascular magnetic resonance T2* measurements of tissue iron in thalassemia

Cited by 148 publications

References 13 publications

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

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

Relaxation effects in the quantification of fat using gradient echo imaging

R2 and R2* are equally effective in evaluating chronic response to iron chelation

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