On the orientation of mammographic structure

Area of Science:

• Medical imaging analysis
• Biophysics of tissue structure
• Mammography image texture analysis

Background:

• Mammographic breast tissue texture follows a power-law P(f) = c/f(β).
• Current models assume isotropic breast structure for power-law background simulation.
• Breast phantoms use power-law backgrounds to mimic complex breast anatomy.

Purpose of the Study:

• To demonstrate that breast anatomic structure is anisotropic, not isotropic.
• To develop a method for estimating power-law coefficients (β and c) considering tissue orientation.
• To analyze the impact of structure orientation on power-law parameters and simulated backgrounds.

Main Methods:

• Developed a formalism to quantify breast structure orientation in mammographic regions of interest (ROIs).
• Modeled the broken radial symmetry in power spectra using an ellipsoidal model.
• Incorporated ellipse tilt angle and axis ratio into the power-law fitting process.

Main Results:

• Breast structure predominantly orients towards the nipple.
• Average orientation angles were 22.5° for MLO and 5° for CC views.
• Statistically significant differences were observed in power-law exponent (β) and magnitude (c) when orientation was considered (<Δβ> = -0.096, <Δlog(c)> = -0.192).

Conclusions:

• A novel formalism for quantifying breast structure and its orientation is presented.
• Accounting for tissue orientation significantly impacts power-law coefficient estimation.
• Simulated backgrounds more accurately mimic breast structure when orientation is incorporated.