Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Design of a double breast gradient coil with controlled anterior posterior gradient variation for diffusion weighted imaging

Feng Jia, Gerrit Cornelis Arends, Philipp Amrein, Edwin Versteeg, Dennis W. J. Klomp, Maxim Zaitsev, Chantal M. W. Tax, Sebastian Littin

Abstract

Introduction High performance gradients poses a promise for breast diffusion weighted imaging (DWI) but are restricted by physiological limits in whole body scanners. While local nonlinear coils offer higher amplitudes, they often suffer from severe gradient reduction near the chest wall. Methods We introduced an optimization framework incorporating a constraint to control anterior posterior gradient variation. A width based figure of merit was defined to evaluate performance regarding coil efficiency and minimum wire width. A prototype was constructed to validate the design methodology. Results The optimized coil achieved a 2.35 fold efficiency increase over standard linear coils. Compared to previous nonlinear designs, the new constraint reduced spatial variation by 35.7% and improved minimum efficiency near the chest wall by 2.6 fold. Experimental field maps matched simulations with errors under 8%. Discussion The proposed method effectively mitigates the trade-off between gradient strength and spatial uniformity along anterior posterior direction. By enhancing performance in the posterior breast region, the design addresses a critical limitation of previous local coils. Conclusion This framework enables the development of high performance, robust local gradient coils, facilitating the clinical implementation of advanced DWI protocols for breast cancer screening.

Design of a double breast gradient coil with controlled anterior posterior gradient variation for diffusion weighted imaging

Abstract

Introduction High performance gradients poses a promise for breast diffusion weighted imaging (DWI) but are restricted by physiological limits in whole body scanners. While local nonlinear coils offer higher amplitudes, they often suffer from severe gradient reduction near the chest wall. Methods We introduced an optimization framework incorporating a constraint to control anterior posterior gradient variation. A width based figure of merit was defined to evaluate performance regarding coil efficiency and minimum wire width. A prototype was constructed to validate the design methodology. Results The optimized coil achieved a 2.35 fold efficiency increase over standard linear coils. Compared to previous nonlinear designs, the new constraint reduced spatial variation by 35.7% and improved minimum efficiency near the chest wall by 2.6 fold. Experimental field maps matched simulations with errors under 8%. Discussion The proposed method effectively mitigates the trade-off between gradient strength and spatial uniformity along anterior posterior direction. By enhancing performance in the posterior breast region, the design addresses a critical limitation of previous local coils. Conclusion This framework enables the development of high performance, robust local gradient coils, facilitating the clinical implementation of advanced DWI protocols for breast cancer screening.

Paper Structure

This paper contains 16 sections, 3 equations, 10 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Methods
  3. A width-based performance measure
  4. Formulation of the optimizaiton problem
  5. Two other performance measures
  6. Numerical optimization procedure
  7. Coil geometry and physical parameters
  8. Prototype and field map measurement
  9. Results
  10. Comparison of Linear and Non-linear Coils
  11. Performance impact of different tuning parameters in non-linear coil designs
  12. Non-linear coil designs with the minimum width of 3.5 mm
  13. Prototype and field map measurement
  14. Discussion
  15. Conclusion
  16. ...and 1 more sections

Figures (10)

  • Figure 1: Geometries of the ROI and current-carrying surface $\Gamma$.
  • Figure 2: Figures of merit $\beta_J$, $\beta_P$ and $\beta_W$ for $C_s$ = 0.1589 (a, d, g), 0.06357 (b, e, h) and 0.03178 (c, f, i). Red markers (circles, crosses, triangles, and squares) denote 26, 28, 30, and 32 wire turns, respectively, where the number of turns in each case is determined by the minimum wire width constraint of 3.5 mm. Performance parameters corresponding to the points marked by gray circles are detailed in Tables \ref{['table:NBCD_Non-LinearCoils_CCD1']}, \ref{['table:NBCD_Non-LinearCoils_CCD2p5']}, and \ref{['table:NBCD_Non-LinearCoils_CCD5']}. Subfigures (a)–(c), (d)–(f), and (g)–(i) each share a common color bar.
  • Figure 3: Coefficients of variable per coronal slice. For $C_s$ = 0.1589, 0.06357 and 0.03178, the corresponding tuning and performance parameters for different cases (different $\alpha_J$ or $C_y$) are presented in Tables \ref{['table:NBCD_Non-LinearCoils_CCD1']}, \ref{['table:NBCD_Non-LinearCoils_CCD2p5']} and \ref{['table:NBCD_Non-LinearCoils_CCD5']}, respectively. $C_s$ = 0.1589 and $C_s$ = 0.06357 have four different cases and $C_s$ = 0.03178 has five cases.
  • Figure 4: Spatial distribution of coil efficiency $\eta$ [mT/m/A] (color map) for different values of $\alpha_J$ and $C_y$ at $C_s =$ 0.1589. The gradient vectors of the magnetic field $B_z$ per unit current are indicated by red arrows.
  • Figure 5: Spatial distribution of coil efficiency $\eta$ [mT/m/A] (color map) for different values of $\alpha_J$ and $C_y$ at $C_s =$ 0.06357. The gradient vectors of the magnetic field $B_z$ per unit current are indicated by red arrows.
  • ...and 5 more figures