R2* magnetic resonance imaging of the liver in patients with iron overload

Hankins, Jane S.; McCarville, M. Beth; Loeffler, Ralf B.; Smeltzer, Matthew P.; Onciu, Mihaela; Hoffer, Fredric A.; Li, Chin Shang; Wang, Winfred C.; Ware, Russell E.; Hillenbrand, Claudia M.

doi:10.1182/blood-2008-12-191643

Cited by 320 publications

(412 citation statements)

References 13 publications

Supporting

Mentioning

390

Contrasting

Unclassified

Order By: Relevance

“…Uncertainty increased with estimated LIC, similar to prior studies comparing R2 and R2* against biopsy [4,6,10]. Log-transformation of both LIC indices normalized the uncertainty, producing a linear relationship with a slope of 0.996, an intercept of 0.114, and an Rsquared of 0.76, P < 0.0001; data are displayed on logarithmic axes for clarity.…”

Section: Methodssupporting

confidence: 76%

See 1 more Smart Citation

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

et al. 2014

View full text Add to dashboard Cite

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.

show abstract

Section: Methodssupporting

confidence: 76%

“…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%]. Numerous FDA-approved analysis software packages are available for R2* analysis, although known, correctable biases exist depending on the fitting model employed [11].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Without spectral fat saturation a complex fitting Fig. 3 Pooled data of 3 studies from the literature (13,14,21) and results of our study. model would have to be used taking multiple fat peaks into account which was beyond the scope of the present article.…”

mentioning

confidence: 87%

“…They also found a close relationship between R2* and HIC (r = 0.97) and concluded that R2* can accurately measure hepatic iron with values in the entire range of iron overload. Hankins et al investigated 44 patients with R2* and liver biopsy [14]. HIC and R2* MRI had a strong correlation with coefficients of 0.96 -0.98.…”

mentioning

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

View full text Add to dashboard Cite

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.

show abstract

“…Linear dependence on liver iron concentration (LIC) is expected for relaxation rate R 2 * liver of the liver, cf. e. g. [2,12]:…”

Section: Appendixmentioning

confidence: 99%

MRI-Based Liver Iron Content Determination at 3T in Regularly Transfused Patients by Signal Intensity Ratio Using an Alternative Analysis Approach Based on R2* Theory

Wunderlich

Cario

Bommer

et al. 2016

Fortschr Röntgenstr

View full text Add to dashboard Cite

▼Objectives: To evaluate the feasibility of addressing liver iron content (LIC) in regularly transfused patients by MR imaging at 3 T based on the signal intensity ratio (SIR). An innovative data analysis approach was developed for this purpose. Methods: 47 consecutive examinations of regularly transfused patients were included. In all cases, we expected high LIC levels. Patients were scanned with MRI at 3 T with multi-echo gradient echo sequences (GRE) at four different flip angles between 20°and 90°with echo times (TE) ranging from 0.9 to 9.8 ms. Spin-echo protocols were acquired to determine the LIC with a reference MRI method working at 1.5 T. 3 T GRE data were analyzed using the liver-to-muscle SIR. Since the method known for 1.5 T was not expected to be applicable for analyzing 3 T data, theoretic dependence of the SIR on the LIC was derived from the equation describing R 2 * signal decay. Obtained SIR values were correlated to reference LIC to get a relation for calculating LIC from SIR quantities. LIC values and their uncertainties were determined from GRE data and correlated to LIC reference values. For two LIC thresholds, the diagnostic accuracy was determined. Results: LIC was reliably determined from SIR in our patient cohort even for large LIC values. Median of LIC uncertainties was 10 %, and the diagnostic accuracy was 0.92 and 0.91, respectively. Conclusion: Determination of even high LIC, resulting in small SIR values, is feasible at 3 T using appropriate SIR analysis.

show abstract

R2* magnetic resonance imaging of the liver in patients with iron overload

Cited by 320 publications

References 13 publications

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

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

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

MRI-Based Liver Iron Content Determination at 3T in Regularly Transfused Patients by Signal Intensity Ratio Using an Alternative Analysis Approach Based on R2* Theory

Contact Info

Product

Resources

About