Article

Microwave imaging for neoadjuvant chemotherapy monitoring: Initial clinical experience

Breast cancer research: BCR (Impact Factor: 5.49). 04/2013; 15(2):R35. DOI: 10.1186/bcr3418
Source: PubMed

ABSTRACT

Introduction
Microwave tomography recovers images of tissue dielectric properties, which appear to be specific for breast cancer, with low-cost technology that does not present an exposure risk, suggesting the modality may be a good candidate for monitoring neoadjuvant chemotherapy.

Methods
Eight patients undergoing neoadjuvant chemotherapy for locally advanced breast cancer were imaged longitudinally five to eight times during the course of treatment. At the start of therapy, regions of interest (ROIs) were identified from contrast-enhanced magnetic resonance imaging studies. During subsequent microwave examinations, subjects were positioned with their breasts pendant in a coupling fluid and surrounded by an immersed antenna array. Microwave property values were extracted from the ROIs through an automated procedure and statistical analyses were performed to assess short term (30 days) and longer term (four to six months) dielectric property changes.

Results
Two patient cases (one complete and one partial response) are presented in detail and demonstrate changes in microwave properties commensurate with the degree of treatment response observed pathologically. Normalized mean conductivity in ROIs from patients with complete pathological responses was significantly different from that of partial responders (P value = 0.004). In addition, the normalized conductivity measure also correlated well with complete pathological response at 30 days (P value = 0.002).

Conclusions
These preliminary findings suggest that both early and late conductivity property changes correlate well with overall treatment response to neoadjuvant therapy in locally advanced breast cancer. This result is consistent with earlier clinical outcomes that lesion conductivity is specific to differentiating breast cancer from benign lesions and normal tissue.

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    • "The applications of the microwave radiometry in biophysical and clinical medical researches had a special development during the recent years, due to its advantages: non-invasiveness of the method, measurement of living structure internal temperature with a satisfactory precision, its simplicity in manipulation and rapidity in measurements, its possibility to perform the population " screening " , and to repeat the investigations after short time intervals without consequences. Among the method's applications, one can remark the following: • pre-clinical investigation of tumour structures in breast cancer, as compared to the X-rays mammography which is nowadays predominant and functional only in the clinical phase; • evaluation of the hypodermic energy level (temperature) in laser, ultrasound, penetrant radiation or hyperthermy therapy using the electromagnetic field [1], [2]; • thermal dosimetry; • non-invasive temperature measurement at the level of brain internal structures in the hypothermia treatment of the new-born babies, which is now the only potentially applicable method [3], [5], [6]; • non-invasive diagnosis and assistance during the therapeutic treatments; • applications in tumour detection, including brain, breast, thyroid cancers, spinal column miss-functions, as a substitute of the computerized tomography (CT) or MRI [4]; • it can be a substitute to diminish the " false negative " or " false positive " rate in case of mammography and ultra-echography. "
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    ABSTRACT: During the recent years, the microwave radiometry has developed many devices in the medical area. The applications of the microwave radiometry in the biomedical area permit the detection of the hot structures which appear due to a specific pathology. The paper describes the measurements of electromagnetic noise temperature, inside a MSR (Magnetic Shielded Room) destined for bioelectromagnetic measurements, namely its applications in microwave radiometry, the verification and calibration of the radiometer, and a very simple simulation experiment on a tumoral structure in a breast phantom.
    Full-text · Article · Dec 2014
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    • "Microwave tomography (MT) is a nonionizing imaging modality capable of noninvasively recovering a wide range of dielectric property (DP) values [1] [2] [3]. An observable contrast exists between the dielectric properties (e.g., permittivity and conductivity) of healthy and abnormal breast tissue [4– 8], and MT has shown great promise as a clinical imaging technique for applications initially related to breast-cancer detection [9], diagnosis [8], and chemotherapy monitoring [10]. Current breast-imaging investigations at Dartmouth College (Hanover, NH, USA) now focus on multimodal MR- MT techniques [11] [12] [13] [14], with the advent of MT providing specificity information to the high-resolution noncontrast enhanced MR images. "
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    ABSTRACT: We have developed a simple mechanism incorporating feedline bends and rotary joints to enable motion of a monopole antenna within a liquid-based illumination chamber for tomographic imaging. The monopole is particularly well suited for this scenario because of its small size and simplicity. For the application presented here a full set of measurement data is collected from most illumination and receive directions utilizing only a pair of antennas configured with the rotating fixture underneath the imaging tank. Alternatively, the concept can be adapted for feed structures entering the tank from the sides to allow for measurements with vertically and horizontally polarized antennas. This opens the door for more advanced imaging applications where anisotropy could play an important role such as in bone imaging.
    Full-text · Article · Jun 2014 · International Journal of Antennas and Propagation
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    • "Even more unfortunate are the implications of these results on interpretations being made and conclusions being drawn from the data reported in [10,11]. These widely cited studies are often considered to be the definitive data on the electromagnetic properties of breast tissue/tumor, and while they do represent the largest and most systematic effort completed to date to probe the dielectric properties of breast surgical specimens, the results presented here suggest that those measurements are surface-property biased, and likely do not represent the effective dielectric properties of the volume averaged tissue that could, for example, be recovered on a cm-scale through non-invasive microwave imaging methods [14,15,17]. "
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    ABSTRACT: Background Tissue dielectric properties are specific to physiological changes and consequently have been pursued as imaging biomarkers of cancer and other pathological disorders. However, a recent study (Phys Med Biol 52:2637–2656, 2007; Phys Med Biol 52:6093–6115, 2007), which utilized open-ended dielectric probing techniques and a previously established sensing volume, reported that the dielectric property contrast may only be 10% or less between breast cancer and normal fibroglandular tissue whereas earlier data suggested ratios of 4:1 and higher may exist. Questions about the sensing volume of this probe relative to the amount of tissue interrogated raise the distinct possibility that the conclusions drawn from that study may have been over interpreted. Methods We performed open-ended dielectric probe measurements in two-layer compositions consisting of a background liquid and a planar piece of Teflon that was translated to predetermined distances away from the probe tip to assess the degree to which the probe produced property estimates representative of the compositional averages of the dielectric properties of the two materials resident within a small sensing volume around the tip of the probe. Results When Teflon was in contact with the probe, the measured properties were essentially those of pure Teflon whereas the properties were nearly identical to those of the intervening liquid when the Teflon was located more than 2 mm from the probe tip. However, when the Teflon was moved closer to the probe tip, the dielectric property measurements were not linearly related to the compositional fraction of the two materials, but reflected nearly 50% of those of the intervening liquid at separation distances as small as 0.2 mm, and approximately 90% of the liquid when the Teflon was located 0.5 mm from the probe tip. Conclusion These results suggest that the measurement methods reported in the most recent breast tissue dielectric property study are not likely to return the compositional averages of the breast tissue specimens evaluated, and thus, the conclusions reached about the expected dielectric property contrast in breast cancer from this specimen study may not be correct.
    Full-text · Article · Jun 2014 · BMC Medical Physics
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