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Detection of masses is much more difficult than that of microcalcifications (MCCs) because breast masses are part of tissues that may not be detected effectively by the techniques developed for detection of MCCs. In this chapter, we present a texture feature coding method (TFCM) to extract features that could characterize special properties of masses. It extracts gradient variations of gray level co-occurrence matrix as texture features. As a result, the TFCM is more sensitive to changes in texture. Three neural network architectures, backpropagation neural network, probabilistic neural network, and radial basis function neural network are used for mass detection with inputs provided by TFCM-extracted features. The experimental results show that our TFCM-based neural network approaches can achieve a detection rate of approximately 87% with a 10% false alarm rate.

Ultrasound-based evaluation of breast lesions is most often performed by recognizing characteristic ultrasonic properties of the findings, such as shape, orientation, border characteristics, and echogenicity. During traditional ultrasound examination of the breast, the patient lies supine, and the ultrasound probe is moved manually over the breast. Probe pressure must be applied to ensure good acoustic contact to the tissue. By applying pressure, however, the true shape characteristics of the suspected lesions are distorted and tissues or lesions may be displaced. Further, the examination technique is not systematic and the result is user dependent. Systematic 3D breast scanning minimizes the user dependency of the examination and makes the reporting of findings easier. One advantage of 3D ultrasound is the ability to view arbitrary 2D scan planes, to evaluate size and shape of findings. True evaluation of these parameters, however, requires a scanning performed on the uncompressed breast. A system for systematic 3D scanning of the uncompressed breast has been developed. During examination, the patient lies prone on an examination bed, with the breast immersed in a water-filled cup. A transducer is moved in a systematic rotational pattern, covering the full breast. Compound imaging techniques minimize shadow and enhancement artifacts before 3D reconstruction.

To make a standard diagnosis, it is important to have a standard lexicon. Although many kinds of expression are possible for the same feature of a breast tumor, a technical term must be a word that is seldom confused with another different concept. Especially, a halo or boundary high echo must be a word that is used to express a malignant sign.

Breast cancer screening was carried out in 3455 subjects living in Tochigi Prefecture during 1999. All subjects underwent palpation, ultrasonic examination and mammography. The detection rate of each method was examined and compared. Breast cancer was discovered in 11 (0.32%) cases, of which 72.7% was early cancer. Three cases were discovered by ultrasonic examination alone, while 4 cases were discovered by mammography alone. No case was discovered by palpation only. Those that were discovered by ultrasonic examination were detected as a mass (two schirrhous carcinoma, one papillotubular carcinoma). Three cases that were discovered by mammography showed microcalcification without forming a mass and all were noninvasive carcinoma. In conclusion, mammography and ultrasonic examination were considered complementary to each other for the detection of breast cancer in mass screenings.

In 89 breast cancer lesions found during clinical breast cancer screening with combined usage of mammography (MMG) and ultrasonography (US) between February 1995 and August 2002, we found 13 cases were negative for US detection. In this study, we reexamined those cases of breast cancer undetectable by breast US. In the 12 US-negative lesions, a secondary extended examination performed using US showed 7 lesions were positive for detection; the remaining 5 lesions were still negative for US examination. In summary, of the 89 breast cancer lesions, US failed to detect 10 (11.2%) during clinical breast cancer screening.

From 1994 until 2002, we performed 6956 ultrasonic screenings of the thyroid for all patients who received breast examination by ultrasonography. We discovered 14 thyroid cancers (0.32%) from 4327 cases with breast complaints. The incidence of thyroid cancer with breast cancer (0.25%) was three times higher than that of thyroid cancer without breast cancer (0.73%). It was concluded that ultrasonic screening of the thyroid was useful in patients with breast complaints.

A new technique named the ultrasound transmission technique has been proposed by the authors. The idea was developed from the clinical findings that sound velocity in breast cancer is higher than in normal tissue by 49-90 m/s. Phantom experiments were conducted. Plexiglas (PMMA) plates 3 mm, 2 mm, or 1 mm thick were put into a cubic container (86 × 86 × 86 mm) filled with degassed water. In the echogram, the apparent distance between the back wall of the container and transducer was shortened because of the higher velocity of sound waves in plexiglas (2700 m/s) than degassed water (1500 m/s). This result showed the validity of the method. A breast to be examined can be sandwiched between a planar ultrasound transducer and reflector plate. Similar experiments were performed using a slice of pork (42 mm thick) instead of degassed water. The shortening of the reflector was apparent. The forearm of a human volunteer was also examined with plexiglas 2mm or 1 mm thick with similar results, suggesting the validity of the method.

The goal of minimally invasive therapy for breast cancer is to eradicate cancer cells with minimal damage to the underlying normal breast parenchyma or skin. Tumor ablation is seen as a means of obtaining local control of breast cancer without surgery. Breast imaging is a critical component of therapy to (1) detect the primary tumor, (2) demonstrate the anatomical extent of the tumor, (3) Guide the tumor-ablative device, (4) monitor tissue effects during treatment, and (5) Monitor the long-term effects of treatment. Current protocols of minimally invasive ablation of primary breast cancer use physical means for tumor ablation. Preliminary data exist for the use of percutaneous excision and thermal energy (cryotherapy, interstitial laser photocoagulation, radiofrequency, and microwaves).

Ultrasound (US)-guided fine-needle aspiration biopsy cytology is useful for diagnosing hard-to-palpate tumors or small-sized tumors. However, it is sometimes difficult to establish diagnosis of masses with insufficient samples or to manage the diagnosis of questionable features. The purpose of this study was to evaluate US-guided Mammotome biopsy for the diagnosis of breast masses in comparison with US-guided fine-needle aspiration biopsy cytology. Fifty-eight histologically proven breast masses on US-guided fine-needle biopsy cytology and US-guided Mammotome biopsy were analyzed during January 1999-March 2003. US guidance was performed with a 7.5-MHz linear array ultrasonic transducer (Aloka SSD 5500); US-guided aspiration biopsy cytology was performed using a 21-gauge needle. Needle biopsy was performed using a Biopsis Mammotome with an 11-gauge needle with a freehand technique. Sensitivity, specificity and accuracy of aspiration biopsy cytology were 92.7%, 76.9%, and 88.9%, respectively. Duct cells were not obtained in 4 of 58 patients (6.9%). The sensitivity, specificity, and accuracy of Mammotome biopsy were 94.1%, 100%, and 97.1%, respectively. Mammotome biopsy is useful for the accurate diagnosis of masses with insufficient materials on aspiration biopsy cytology, sonographiccytologic discordance, and radiotherapy after breast-conserving surgery.

We assessed the ultrasonographic appearance and clinical implication of bilateral breast involvement in three cases of acute leukemia: L1, L3, and M1 of the FAB subtype. Breast involvement was observed in one case at the initial presentation and in two cases at relapse after bone marrow transplantation. Common findings of ultrasonograms of the cases were hypoechoic masses with diffusely mixed internal echogenicity, including a mottled appearance in the case with L3. The ultrasonographic appearance was nonspecific to leukemia. In each case, both sides of breast involvement were identical to each other in appearance at the diagnosis and during the course of treatment. When breasts were found to be involved by leukemia cells, all three cases had another extramedullary lesion: meninx in two cases at relapse and ovary in one case at the initial presentation. These findings suggested the bilateral breast involvement occurred as a part of the diffuse and generalized leukemia process and as extramedullary lesions at sanctuary areas of antileukemia agents.