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This paper studies the possibility of distinguishing between benign and malignant masses by exploiting the morphology-dependent temporal and spectral characteristics of their microwave backscatter response in ultra-wideband breast cancer detection. The spiculated border profiles of 2-D breast masses are generated by modifying the baseline elliptical rings based upon the irregularity of their peripheries. Furthermore, the single- and multilayer lesion models are used to characterize a distinct mass region followed by a sharp transition to background, and a blurred mass border exhibiting a gradual transition to background, respectively. Subsequently, the complex natural resonances (CNRs) of the backscatter microwave signature can be derived from the late-time target response and reveal diagnostically useful information. The fractional sequence CLEAN algorithm is proposed to estimate the lesions' delay intervals and identify the late-time responses. Finally, it is shown through numerical examples that the locations of dominant CNRs are dependent on the lesion morphologies, where 2-D computational breast phantoms with single and multiple lesions are investigated. The analysis is of potential use for discrimination between benign and malignant lesions, where the former usually possesses a better-defined, more compact shape as opposed to the latter.

Background: Sentinel node (SN) biopsy for breast cancer is becoming more common owing to its lower morbidity when compared with full axillary dissection. However, the optimal method of finding and the number of SN to be dissected are still subject to conjecture. The aim of this study was to determine the optimal number of SN required to accurately stage an axilla after the i.d. injection of isotope and blue dye., Method: Prospective data from all patients undergoing SN biopsy from April 2000 to September 2004 were analysed. For positive SN, the order in which they became positive was then tabulated., Results: During the 4 years, 113 patients who fulfilled the selection criteria had undergone SN biopsy with 216 SN harvested. Of these, 33 patients had positive SN results. If only the first SN was analysed, 87.9% of those positive biopsies would have been discovered. Two SN raised the predictive value to 97.0%., Conclusion: Two SN would seem to be the optimal number to harvest after i.d. injection of both isotope and blue dye.

This paper presents a generic framework for the modeling of ultra-wideband (UWB) signal propagation in human breast, which facilitates system-level simulations and provides performance prediction. The clutter associated with the breast tissue heterogeneity is modeled through several key parameters depending on the tissue compositions. Subsequently, important channel properties such as the backscatter energy and the probability density function of time-of-arrival are derived. The modified Hermite polynomials, which fit well into the real pulse shapes, are then used to model the UWB signals. Armed with the channel/signal model preliminaries, three metrics are proposed, namely, the mean clutter response, the clean tumor response, and the worst-case clutter response. The generalized model provides a parsimonious way to study the effects of tissue structures, pulse templates, and array setup on the performance of a specified UWB imaging system. Numerical examples are used to demonstrate the usefulness of the proposed approach.