Ei Ueno

Real‑time Tissue Elasticity Imaging using the Combined Autocorrelation Method

The elastic properties of tissues are expected to provide novel information for use in diagnosing pathologic changes in tissues and discriminating between malignant and benign tumors. Because it is hard to directly estimate the elastic modulus distribution from echo signals, methods for imaging the distribution of tissue strain under static compression are being widely investigated. Imaging the distribution of strain has proven to be useful for detecting disease tissues on the basis of their differences in elastic properties, although it is more qualitative than elastic modulus distribution. Many approaches to obtaining strain images from echo signals have been proposed. Most of these approaches use the spatial correlation technique, a method of detecting tissue displacement that provides maximum correlation between the echo signal obtained before and the one obtained after compression. Those methods are not suited for real-time processing, however, because of the amount of computation time they require. An alternative approach is a phase-tracking method, which is analogous to Doppler blood flowmetry. Although it can realize the rapid detection of displacement, the aliasing effect prevents its application to the large displacements that are necessary to improve the S/N ratio of the strain image. We therefore developed a more useful technique for imaging tissue elasticity. This approach, which we call the combined autocorrelation (CA) method, has the advantages of producing strain images of high quality with real-time processing and being applicable to large displacements.Numeric simulation and phantom experimentation have demonstrated that this methods capability to reconstruct images of tissue strain distribution under practical conditions is superior to that of the conventional spatial correlation method. In simulation and phantom experimentation, moreover, the image of elastic modulus distribution was also obtained by estimating stress distribution using a three-dimensional tissue model. When the proposed CA method was used to measure breast tumor specimens, the obtained strain images clearly revealed harder tumor lesions that were only vaguely resolved in B-mode images. Moreover, the results indicated the possibility of extracting the pathological characteristics of a tumor, making it useful for determining tumor type. These advantages justify the clinical use of the CA method.

Detection of GST1 gene deletion by the polymerase chain reaction and its possible correlation with stomach cancer in Japanese

SummaryA homozygous gene deletion at the GST1 locus of genomic DNA isolated from peripheral blood was investigated for its relationship with several types of cancer using the polymerase chain reaction (PCR) technique. DNA samples were prepared from blood obtained from 128 healthy blood donors and 150 patients with cancer or chronic hepatitis. PCR primers were prepared based on the human cDNA sequence and the intron/exon sequences of the rat Yb2 gene. The amplified sequence between exons 5 and 6 including intron 5 showed very clearly the presence of absence of the GST1 gene, after electrophoresis in a 2% agarose gel. Segregation of the presence and absence of PCR product from samples of twins and their parents indicated that presence involves homozygous or heterozygous normal GST1 genotypes while absence invovles only homozygous gene deletion. The patients with stomach cancer had a significantly higher frequency of gene deletion than did the healthy controls (P< 0.005). Thus, GST1 deletion may be a possible genetic marker for early detection of a group at high risk of stomach cancer.

High-speed Freehand Tissue Elasticity Imaging for Breast Diagnosis

Tissue elasticity imaging technology is expected to be a new technique for breast disease diagnosis. In clinical measurement, high-speed and freehand manipulation of the probe is required for a practical system. Thus, we developed a tissue elasticity imaging system which performs a stable strain measurement with freehand tissue compression based on the extended combined autocorrelation method. The method enables us to obtain tissue strain distribution at high-speed and suppressing errors due to lateral slip of the probe caused by freehand compression. The developed method can estimate the strain images at about 5 frames/s and was applied to breast disease measurement in vivo. Consequently, it is shown that the system is effective not only for the diagnosis of tissue hardness but also to determine the disease expansion area. It is also confirmed that the method can stably estimate the strain during the breast measurement in vivo.

Ultrasound screening of breast cancer.

Ultrasound (US) screening of breast cancer was surveyed with the results of breast screening combined with mammography (MMG), US and clinical breast examination (CBE) at Ibaraki Health Service Association. Breast cancer is common among women in their late 40s in Japan, who tend to have small and dense breasts. Our results showed that US works as well as MMG in detecting breast cancers in women in their 40s, and both modalities are compensatory. There are many reports that the combination of MMG and US is a suitable method for breast screening in Japan. A large-scale randomized control trial is now ongoing to investigate whether breast screening by both MMG and US is useful to decrease breast cancer mortality.

Phase-contrast X-ray CT image of breast tumor

Phase-contrast X-ray CT images generated by differences in refractive indices can be used to visualize the internal structures of soft tissues without contrast enhancement. In this study, imaging of human breast tumor was performed on formalin-fixed samples. Experiments were carried out at the synchrotron source of the Photon Factory, Tsukuba, Japan. The X-ray energy was adjusted to 17.7 keV. Phase-contrast X-ray CT images revealed various structures of human breast tumor as clearly as optical images.

Current improvements in breast ultrasound, with a special focus on elastography

Current improvements in the area of breast ultrasound are described. Digital beam formers contributed to improving both contrast and special resolution of B-mode images and enabled other techniques. Four-dimensinal images and CAD are still in progress. Elastography may reduce false-positives and unnecessary interventional procedures, especially in nonsymptomatic patients.

Use of doppler color flow imaging for differential diagnosis of vascular malformations: A preliminary report

PURPOSE To ascertain whether Doppler color flow imaging can demonstrate the characteristics of blood flow within vascular lesions. MATERIALS AND METHODS Two cases with vascular malformation in the soft tissues of the maxillofacial region were examined. One was an arteriovenous, high-flow type malformation involving the tongue, the floor of the mouth, and the mandible. The other was a venous, low-flow type malformation of the whole tongue. The technique used was the same as that for the extraoral approach in conventional ultrasound imaging. RESULTS Doppler color flow imaging provided valuable information on the hemodynamic characteristics of the vascular malformations when comparing with other diagnostic forms of imaging, and clearly differentiated between high- and low-flow vascular lesions. CONCLUSION Doppler color flow imaging was suggested to be another method in our armamentarium for differential diagnosis of vascular malformations.

Ultrasonographic Criteria for Diagnosis of Cervical Lymph Node Metastasis of Squamous Cell Carcinoma in the Oral and Maxillofacial Region

PURPOSE This retrospective study was done to establish an objective criterion for sonographic diagnosis of cervical lymph node metastasis of squamous cell carcinoma in the oral and maxillofacial region. PATIENTS AND METHODS A quantitative criterion for differentiating metastatic from nonmetastatic nodes was statistically calculated using logistic regression analysis of 106 cervical lymph nodes in 41 patients. A prospective study was then conducted to ascertain the reliability of the criterion for 82 nodes in another 23 patients. RESULTS The following equation was obtained from the retrospective study: Y = 1/(1+e(-lambda) (lambda = -7.5709 + 4.2423 X1 + 1.9354 X2 + 0.5507 X3) Y represents the predicted value; lambda, also representing a predicted value, was defined as negative for nonmetastatic and positive for metastatic nodes; X1, signifying the existence of an echogenic hilus, was defined as 0 for presence and 1 for absence; X2, signifying the internal echo pattern, was defined as 0 for homogeneous and 1 for heterogeneous; X3, signifying the minimal diameter, was the actual measured value (mm). This equation showed a sensitivity of 82%, a specificity of 91%, and an accuracy of 88% in the prospective study. CONCLUSION The equation calculated by logistic regression analysis was a reliable criterion for diagnosing cervical lymph node metastasis.

The Breast Cancer Working Group Presentation was Divided into Three Sections: The Epidemiology, Pathology and Treatment of Breast Cancer

EPIDEMIOLOGY OF BREAST CANCER: The incidence and mortality of breast cancer are lower in Asia than in the West, particularly in post-menopausal women, but they are increasing. The age patterns of the incidence of breast cancer in Asia differ from in the West: in most Asian countries the peak incidence of breast cancer is at about age 45-50, whereas in western countries the incidence continues to increase even at older ages. Mortality is decreasing in western countries, whereas it is still increasing in Asian nations. There are many epidemiological factors involved in breast cancer, and important known risk factors include diet, obesity and diabetes. Asian studies found that high intake of isoflavones reduced the risk of breast cancer. PATHOLOGY OF BREAST CANCER: With regard to the pathology of breast cancer, for the molecular subtype, luminal A and luminal B are being used, while HER2 expression and rapid proliferation are also employed. Study results showed a somewhat higher prevalence of luminal A in Japanese compared with Americans. Ductal carcinoma in situ breast cancer is less frequent in Asian breast cancer patients than in Americans. The Working Group resolved to establish an international committee for pathological assessment of breast cancer in Asia. TREATMENT OF BREAST CANCER: Pharmacokinetics-pharmacodynamics studies are needed between ethnic backgrounds, investigating aromatase inhibitors and tamoxifen (endoxifen), as well as the effects of demographic factors such as diet, medical care, body mass index, etc. Correlations between adverse events and the clinical outcome also need to be studied.

Attempt at Visualizing Breast Cancer with X-ray Dark Field Imaging

X-ray dark-field imaging (DFI) can clearly visualize breast cancer phantoms and cancer cell nests, stroma, fat tissue, ductus lactiferi, muscle, collagen fibers at stroma and calcification in a 2.8-mm-thick breast cancer pathological specimen. The system comprises a Bragg asymmetric-cut monochro-collimator and a 2.124-mm-thick Si 440 Laue diffraction analyzer at 35 keV. Both optical elements are Floating Zone made silicon crystals. The view size of 33 mm (H) ×19.5 mm (V) and the spatial resolution of 10 µm or better are obtainable at the vertical wiggler beamline BL14B at the Photon Factory.