Effect of Radiofrequency Transmit Field Correction on Quantitative Dynamic Contrast-enhanced MR Imaging of the Breast at 3.0 T

Bedair, Reem; Graves, Martin J.; Patterson, Andrew J.; Manavaki, Roido; Wallace, Tess E.; Reid, Scott A.; Mendichovszky, Iosif; Griffiths, John R.; Gilbert, Fiona J.

doi:10.1148/radiol.2015150920

Cited by 17 publications

(32 citation statements)

References 35 publications

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“…Any bias in the prescribed flip angle will lead to inaccuracies in the measured T 1 . The observed T 1 values in the AT and FGT in this study are not unreasonable and are similar to a recent study by Bedair et al that investigated the effect of a Bloch–Siegert B 1 correction technique on VFA-derived measurements of T 1 in the breast at 3 T (36). In addition, our study incorporated a comparison with the gold standard IR data and a reproducibility analysis, allowing for an evaluation of accuracy and precision of the combination of the Bloch–Siegert B 1 and the VFA T 1 mapping techniques.…”

Section: Discussionsupporting

confidence: 91%

“…However, the accuracy of the technique is severely affected by inhomogeneities in the B 1 transmit field, which are known to be significant in the breast at 3 T (14). The difference in the prescribed flip angle due to B 1 inhomogeneities leads to inaccuracies in VFA-derived estimates of T 1 , which can compound to large errors in, for example, the DCE-MRI parameter K trans (11, 36). Large errors in DCE-MRI analyses could lower the sensitivity and specificity of the imaging technique, thereby limiting clinical adoption.…”

Section: Resultsmentioning

confidence: 99%

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Bloch–Siegert B1-Mapping Improves Accuracy and Precision of Longitudinal Relaxation Measurements in the Breast at 3 T

et al. 2016

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Variable flip angle (VFA) sequences are a popular method of calculating T1 values, which are required in a quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). B1 inhomogeneities are substantial in the breast at 3 T, and these errors negatively impact the accuracy of the VFA approach, thus leading to large errors in the DCE-MRI parameters that could limit clinical adoption of the technique. This study evaluated the ability of Bloch–Siegert B1 mapping to improve the accuracy and precision of VFA-derived T1 measurements in the breast. Test–retest MRI sessions were performed on 16 women with no history of breast disease. T1 was calculated using the VFA sequence, and B1 field variations were measured using the Bloch–Siegert methodology. As a gold standard, inversion recovery (IR) measurements of T1 were performed. Fibroglandular tissue and adipose tissue from each breast were segmented using the IR images, and the mean T1 was calculated for each tissue. Accuracy was evaluated by percent error (%err). Reproducibility was assessed via the 95% confidence interval (CI) of the mean difference and repeatability coefficient (r). After B1 correction, %err significantly (P < .001) decreased from 17% to 8.6%, and the 95% CI and r decreased from ±94 to ±38 milliseconds and from 276 to 111 milliseconds, respectively. Similar accuracy and reproducibility results were observed in the adipose tissue of the right breast and in both tissues of the left breast. Our data show that Bloch–Siegert B1 mapping improves accuracy and precision of VFA-derived T1 measurements in the breast.

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Section: Discussionsupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Bloch–Siegert B1-Mapping Improves Accuracy and Precision of Longitudinal Relaxation Measurements in the Breast at 3 T

et al. 2016

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“…As is commonly done in quantitative DCE‐MRI, we used B 1 + maps to correct for the effects of B 1 + inhomogeneities using a variable flip‐angle T 1 mapping method . This method uses several T 1 ‐weighted gradient echo scans at different flip angles to estimate the T 1 value at every recorded voxel by performing a fit of the signal equation, which is a function of the applied flip angle.…”

Section: Methodsmentioning

confidence: 99%

“…As is commonly done in quantitative DCE-MRI, we used B 1 + maps to correct for the effects of B 1 + inhomogeneities using a variable flip-angle T 1 mapping method. 10,11,22,28,29 This method uses several T 1 -weighted gradient echo scans at different flip angles to estimate the T 1 value at every recorded voxel by performing a fit of the signal equation, which is a function of the applied flip angle. Since this is a voxel-wise method, B 1 + correction can be easily applied by fitting the function while using the actual flip angle as the independent variable, i.e.…”

Section: T 1 Mappingmentioning

confidence: 99%

“…9 It has been shown that applying B 1 + correction at 3 T has a significant effect on the results of quantitative analysis and serves to reduce differences in quantitative parameter estimations between the right and left breasts. 10 Recent work shows that, even at 1.5 T, refraining from B 1 + field corrections leads to a 50% estimation error in tumor T 1 and consequently a 41% estimation error in pharmacokinetic parameters. 11 At 7 T, the B 1 + field variations manifest themselves on a smaller spatial scale, such that variations within a single breast become significant.…”

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confidence: 99%

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Estimating B₁⁺ in the breast at 7 T using a generic template

et al. 2018

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Dynamic contrast‐enhanced MRI is the workhorse of breast MRI, where the diagnosis of lesions is largely based on the enhancement curve shape. However, this curve shape is biased by RF transmit (B 1 +) field inhomogeneities. B 1 + field information is required in order to correct these. The use of a generic, coil‐specific B 1 + template is proposed and tested.Finite‐difference time‐domain simulations for B 1 + were performed for healthy female volunteers with a wide range of breast anatomies. A generic B 1 + template was constructed by averaging simulations based on four volunteers. Three‐dimensional B 1 + maps were acquired in 15 other volunteers. Root mean square error (RMSE) metrics were calculated between individual simulations and the template, and between individual measurements and the template. The agreement between the proposed template approach and a B 1 + mapping method was compared against the agreement between acquisition and reacquisition using the same mapping protocol.RMSE values (% of nominal flip angle) comparing individual simulations with the template were in the range 2.00‐4.01%, with mean 2.68%. RMSE values comparing individual measurements with the template were in the range8.1‐16%, with mean 11.7%. The agreement between the proposed template approach and a B 1 + mapping method was only slightly worse than the agreement between two consecutive acquisitions using the same mapping protocol in one volunteer: the range of agreement increased from ±16% of the nominal angle for repeated measurement to ±22% for the B 1 + template.With local RF transmit coils, intersubject differences in B 1 + fields of the breast are comparable to the accuracy of B 1 + mapping methods, even at 7 T. Consequently, a single generic B 1 + template suits subjects over a wide range of breast anatomies, eliminating the need for a time‐consuming B 1 + mapping protocol.

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Diffusion‐weighted double‐echo steady‐state with a three‐dimensional cones trajectory for non‐contrast‐enhanced breast MRI

Moran

Cheng

Sandino

et al. 2020

Magnetic Resonance Imaging

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The image quality limitations of echo‐planar diffusion‐weighted imaging (DWI) are an obstacle to its widespread adoption in the breast. Steady‐state DWI is an alternative DWI method with more robust image quality but its contrast for imaging breast cancer is not well‐understood. The aim of this study was to develop and evaluate diffusion‐weighted double‐echo steady‐state imaging with a three‐dimensional cones trajectory (DW‐DESS‐Cones) as an alternative to conventional DWI for non‐contrast‐enhanced MRI in the breast. This prospective study included 28 women undergoing clinically indicated breast MRI and six asymptomatic volunteers. In vivo studies were performed at 3 T and included DW‐DESS‐Cones, DW‐DESS‐Cartesian, DWI, and CE‐MRI acquisitions. Phantom experiments (diffusion phantom, High Precision Devices) and simulations were performed to establish framework for contrast of DW‐DESS‐Cones in comparison to DWI in the breast. Motion artifacts of DW‐DESS‐Cones were measured with artifact‐to‐noise ratio in volunteers and patients. Lesion‐to‐fibroglandular tissue signal ratios were measured, lesions were categorized as hyperintense or hypointense, and an image quality observer study was performed in DW‐DESS‐Cones and DWI in patients. Effect of DW‐DESS‐Cones method on motion artifacts was tested by mixed‐effects generalized linear model. Effect of DW‐DESS‐Cones on signal in phantom was tested by quadratic regression. Correlation was calculated between DW‐DESS‐Cones and DWI lesion‐to‐fibroglandular tissue signal ratios. Inter‐observer agreement was assessed with Gwet's AC. Simulations predicted hyperintensity of lesions with DW‐DESS‐Cones but at a 3% to 67% lower degree than with DWI. Motion artifacts were reduced with DW‐DESS‐Cones versus DW‐DESS‐Cartesian (p < 0.05). Lesion‐to‐fibroglandular tissue signal ratios were not correlated between DW‐DESS‐Cones and DWI (r = 0.25, p = 0.38). Concordant hyperintensity/hypointensity was observed between DW‐DESS‐Cones and DWI in 11/14 lesions. DW‐DESS‐Cones improved sharpness, distortion, and overall image quality versus DWI. DW‐DESS‐Cones may be able to eliminate motion artifacts in the breast allowing for investigation of higher degrees of steady‐state diffusion weighting. Malignant breast lesions in DW‐DESS‐Cones demonstrated hyperintensity with respect to surrounding tissue without an injection of contrast. Level of Evidence 2. Technical Efficacy Stage 1.

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Effect of Radiofrequency Transmit Field Correction on Quantitative Dynamic Contrast-enhanced MR Imaging of the Breast at 3.0 T

Abstract: B1(+) correction demonstrates a substantial effect on the results of quantitative dynamic contrast-enhanced analysis of breast tissue at 3 T, which propagates into the pharmacokinetic analysis of tumors that is dependent on whether the tumor is located in the right or left breast.

Cited by 17 publications

References 35 publications

Bloch–Siegert B1-Mapping Improves Accuracy and Precision of Longitudinal Relaxation Measurements in the Breast at 3 T

Bloch–Siegert B1-Mapping Improves Accuracy and Precision of Longitudinal Relaxation Measurements in the Breast at 3 T

Estimating B₁⁺ in the breast at 7 T using a generic template

Diffusion‐weighted double‐echo steady‐state with a three‐dimensional cones trajectory for non‐contrast‐enhanced breast MRI

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Effect of Radiofrequency Transmit Field Correction on Quantitative Dynamic Contrast-enhanced MR Imaging of the Breast at 3.0 T

Abstract: B1(+) correction demonstrates a substantial effect on the results of quantitative dynamic contrast-enhanced analysis of breast tissue at 3 T, which propagates into the pharmacokinetic analysis of tumors that is dependent on whether the tumor is located in the right or left breast.

Cited by 17 publications

References 35 publications

Bloch–Siegert B1-Mapping Improves Accuracy and Precision of Longitudinal Relaxation Measurements in the Breast at 3 T

Bloch–Siegert B1-Mapping Improves Accuracy and Precision of Longitudinal Relaxation Measurements in the Breast at 3 T

Estimating B1+ in the breast at 7 T using a generic template

Diffusion‐weighted double‐echo steady‐state with a three‐dimensional cones trajectory for non‐contrast‐enhanced breast MRI

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Estimating B₁⁺ in the breast at 7 T using a generic template