Visibility of microcalcifications in computed and screen-film mammography

Due to the clinically and technically demanding nature of breast x-ray imaging, mammography still remains one of the few essentially film-based radiological imaging techniques in modern medical imaging. There are a range of possible benefits available if a practical and economical direct digital imaging technique can be introduced to routine clinical practice. There has been much debate regarding the minimum specification required for direct digital acquisition. One such direct digital system available is computed radiography (CR), which has a modest specification when compared with modern screen-film mammography (SFM) systems. This paper details two psychophysical studies in which the detection of simulated microcalcifications with CR has been directly compared to that with SFM. The first study found that under scatter-free conditions the minimum detectable size of microcalcification was approximately 130 microns for both SFM and CR. The second study found that SFM had a 4.6% higher probability of observers being able to correctly identify the shape of 350 microns diameter test details; there was no significant difference for-either larger or smaller test details. From the results of these studies it has been demonstrated that the modest specification of CR, in terms of limiting resolution, does not translate into a dramatic difference in the perception of details at the limit of detectability. When judging the imaging performance of a system it is more important to compare the signal-to-noise ratio transfer spectrum characteristics, rather than simply the modulation transfer function.     

Improvement of detectability of microcalcifications by magnification digital mammography

Our aim in this study was to evaluate the potential utility of magnification mammography with a CR system by investigating the basic imaging parameters and detectability of microcalcifications in comparison with those of conventional screen-film systems. The basic imaging parameters were evaluated by measuring scatter fraction, modulation transfer function (MTF), Wiener spectrum, and incident dose for the various magnification factors. The detection of simulated microcalcifications in radiographs of a mammographic phantom and breast specimens were evaluated subjectively and quantitatively for screen-film and CR techniques with various magnification factors. The scatter fraction of digital magnification mammography decreased with increasing magnification factor. MTF of magnification digital mammography improved with increasing magnification factor. The detectability of microcalcifications with the CR system was significantly improved by magnification technique. From the above results, it is expected that the use of magnification mammography with a CR system will improve the detectability of microcalcification.     

Axillary lymph node microcalcifications disclosing breast cancer]

It is well known that vertebral schisis is frequent in enuretic children but the true incidence in the normal population is not clear, because all series published are referred to children with associated urinary anomalies, who were submitted to voiding cystography and or intravenous pyelography. This determine a statistical bias. The aim of our study was to compare the prevalence of vertebral schisis in enuretic children and in the general pediatric population. Therefore, we chose 142 enuretic children without associated urological or neurological anomalies and a control group of 152 children, assumed as general population, who were submitted to spinal X-rays during screening for scoliosis or congenital dysplasia of the hip. Vertebral schisis was found in 65% (93/142) of enuretics and in 18% (28/152) of control group children. Maximum association between enuresis and vertebral schisis was found in primary monosymptomatic nocturnal enuresis (82%), while minimum association was found in children with secondary enuresis (57%). The difference in percentage of association enuresis-schisis was statistically significant between enuretics and control group and between primary monosymptomatic and secondary enuresis (p < 0.001). The results of this paper are simply add knowledges on the prevalence of the sacral schisis in enuretic children. But, to speculate the different prevalence in different types of enuresis, the results should confirm that the phenomenon of enuresis is multifactorial and the primary monosymptomatic and secondary enuresis have different etiological factor.     

Computerized analysis of mammographic microcalcifications in morphological and texture feature spaces

We are developing computerized feature extraction and classification methods to analyze malignant and benign microcalcifications on digitized mammograms. Morphological features that described the size, contrast, and shape of microcalcifications and their variations within a cluster were designed to characterize microcalcifications segmented from the mammographic background. Texture features were derived from the spatial gray-level dependence (SGLD) matrices constructed at multiple distances and directions from tissue regions containing microcalcifications. A genetic algorithm (GA) based feature selection technique was used to select the best feature subset from the multi-dimensional feature spaces. The GA-based method was compared to the commonly used feature selection method based on the stepwise linear discriminant analysis (LDA) procedure. Linear discriminant classifiers using the selected features as input predictor variables were formulated for the classification task. The discriminant scores output from the classifiers were analyzed by receiver operating characteristic (ROC) methodology and the classification accuracy was quantified by the area, Az, under the ROC curve. We analyzed a data set of 145 mammographic microcalcification clusters in this study. It was found that the feature subsets selected by the GA-based method are comparable to or slightly better than those selected by the stepwise LDA method. The texture features (Az = 0.84) were more effective than morphological features (Az = 0.79) in distinguishing malignant and benign microcalcifications. The highest classification accuracy (Az = 0.89) was obtained in the combined texture and morphological feature space. The improvement was statistically significant in comparison to classification in either the morphological (p = 0.002) or the texture (p = 0.04) feature space alone. The classifier using the best feature subset from the combined feature space and an appropriate decision threshold could correctly identify 35% of the benign clusters without missing a malignant cluster. When the average discriminant score from all views of the same cluster was used for classification, the Az value increased to 0.93 and the classifier could identify 50% of the benign clusters at 100% sensitivity for malignancy. Alternatively, if the minimum discriminant score from all views of the same cluster was used, the Az value would be 0.90 and a specificity of 32% would be obtained at 100% sensitivity. The results of this study indicate the potential of using combined morphological and texture features for computer-aided classification of microcalcifications.     

Evidence that breast cancer associated microcalcifications are mineralized malignant cells

Antioxidant activity of carotenoids in multilamellar liposomes assayed by inhibition of formation of thiobarbituric acid-reactive substances was in the ranking: lycopene> alpha-tocopherol > alpha-carotene > beta-cryptoxanthin > zeaxanthin = beta-carotene > lutein. Mixtures of carotenoids were more effective than the single compounds. This synergistic effect was most pronounced when lycopene or lutein was present. The superior protection of mixtures may be related to specific positioning of different carotenoids in membranes.     

Stereotactic core biopsy of breast microcalcifications. Aid to diagnosis?]

We assessed the accuracy with which stereotactic core biopsy of breast microcalcifications helps to justify follow-up or indicate required surgical planning. Eighty-nine patients underwent stereotactic breast biopsy performed with large core needles. Histopathologic findings of microbiopsies were correlated with radiological findings, with follow up and with surgical findings. Agreement between radiological and histopathologic findings on biopsies was obtained in 86% for benign results. Even in the case of benign radiological findings, the histological results of microbiopsies required a surgical biopsy justified in 10% of cases. Radiologically suspicious or malignant microcalcifications were correlated with 35% benign and 65% malignant histologies on biopsies. The positive predictive value, negative predictive value and accuracy were respectively 93%, 86% and 95%. Invasive lesions were found on microbiopsies in 39% of excised malignant lesions. Multifocal lesions were proved on microbiopsies in 50% of all excised carcinomas. Microbiopsies help to disclose malignant lesions undetected on radiological analysis, and may obviate diagnostic surgical biopsy in many cases.     

Malignant and benign clustered microcalcifications: automated feature analysis and classification

Brassinosteroids are widely distributed plant compounds that modulate cell elongation and division, but little is known about the mechanism of action of these plant growth regulators. To investigate brassinosteroids as signals influencing plant growth and development, we identified a brassinosteroid-insensitive mutant in Arabidopsis thaliana (L.) Henyh. ecotype Columbia. The mutant, termed bri1, did not respond to brassinosteroids in hypocotyl elongation and primary root inhibition assays, but it did retain sensitivity to auxins, cytokinins, ethylene, abscisic acid, and gibberellins. The bri1 mutant showed multiple deficiencies in developmental pathways that could not be rescued by brassinosteroid treatment including a severely dwarfed stature; dark green, thickened leaves; males sterility; reduced apical dominance; and de-etiolation of dark-grown seedlings. Genetic analysis suggests that the Bri1 phenotype is caused by a recessive mutation in a single gene with pleiotropic effects that maps 1.6 centimorgans from the cleaved, amplified, polymorphic sequence marker DHS1 on the bottom of chromosome IV. The multiple and dramatic effects of mutation of the BRI1 locus on development suggests that the BRI1 gene may play a critical role in brassinosteroid perception or signal transduction.     

Fractal modeling and segmentation for the enhancement of microcalcifications in digital mammograms

The objective of this research is to model the mammographic parenchymal, ductal patterns and enhance the microcalcifications using deterministic fractal approach. According to the theory of deterministic fractal geometry, images can be modeled by deterministic fractal objects which are attractors of sets of two-dimensional (2-D) affine transformations. The iterated functions systems and the collage theorem are the mathematical foundations of fractal image modeling. In this paper, a methodology based on fractal image modeling is developed to analyze and model breast background structures. We show that general mammographic parenchymal and ductal patterns can be well modeled by a set of parameters of affine transformations. Therefore, microcalcifications can be enhanced by taking the difference between the original image and the modeled image. Our results are compared with those of the partial wavelet reconstruction and morphological operation approaches. The results demonstrate that the fractal modeling method is an effective way to enhance microcalcifications. It may also be able to improve the detection and classification of microcalcifications in a computer-aided diagnosis system.     

Mucinous breast carcinoma showing as a cluster of suspicious microcalcifications on mammography

We report a case of mucinous breast carcinoma whose mammographic features consisted of a suspicious cluster of microcalcifications as the unique sign of malignancy. The lesion was non-palpable and measured approximately 2 cm at the greatest diameter. The microcalcifications showed several morphologies: round, pleomorphic, and fine shapes were identified. The total number of microcalcifications was > 30 and the number per square centimeter varied from 10 to 20. The histological calcifications showed good correlation with the mammographic ones and were localized predominantly at the periphery of the tumor inside ducts with ductal carcinoma in situ or in the acellular mucin. Two types were observed: psammomatous and gross-irregular calcifications. To our knowledge, only one case with similar findings has been reported previously.     

Image compression in digital mammography: effects on computerized detection of subtle microcalcifications

Our previous receiver operating characteristic (ROC) study indicated that the detection accuracy of microcalcifications by radiologists is significantly reduced if mammograms are digitized at 0.1 mm x 0.1 mm. Our recent study also showed that detection accuracy by computer decreases as the pixel size increases from 0.035 mm x 0.035 mm. It is evident that very large matrix sizes have to be used for digitizing mammograms in order to preserve the information in the image. Efficient compression techniques will be needed to facilitate communication and archiving of digital mammograms. In this study, we evaluated two compression techniques: full frame discrete cosine transform (DCT) with entropy coding and Laplacian pyramid hierarchical coding (LPHC). The dependence of their efficiency on the compression parameters was investigated. The techniques were compared in terms of the trade-off between the bit rate and the detection accuracy of subtle microcalcifications by an automated detection algorithm. The mean-square errors in the reconstructed images were determined and the visual quality of the error images was examined. It was found that with the LPHC method, the highest compression ratio achieved without a significant degradation in the detectability was 3.6:1. The full frame DCT method with entropy coding provided a higher compression efficiency of 9.6:1 at comparable detection accuracy. The mean-square errors did not correlate with the detection accuracy of the microcalcifications. This study demonstrated the importance of determining the quality of the decompressed images by the specific requirements of the task for which the decompressed images are to be used. Further investigation is needed for selection of optimal compression technique for digital mammograms.     

Pheochromocytoma mimicking septic shock

A tumour arising from chromaffin cells, the pheochromocytoma may be associated or present with hypotension and result in a lethal shock. The authors report a rare case of pheochromocytoma simulating septic shock. They review the mechanisms by which hypersecretion of catecholamines may cause shock. The detection of pheochromocytoma in its atypical presentation is essential for early diagnosis and the reduction of mortality related to this condition.     

Urinary non-precipitable lead in lead workers

Sixty-six workers engaged in lead-glazing pottery with a presumed moderate exposure to lead were studied. The group comprised 20 men with long-term exposure to lead and positive laboratory signs of increased lead absorption (Group A); 22 with long-term exposure and negative laboratory signs (Group B); 11 with short-term exposure and positive laboratory signs (Group C); and 13 with short-term exposure and negative laboratory signs (Group D). In addition, 14 workers employed in casting the kelmet alloys with presumed heavy exposure to lead (Group E) and seven healthy individuals (Group F) were included. Urine samples from all the subjects were analysed to determine, first, the total lead using the ashing technique, and then the precipitable lead using the coprecipitation technique of Cholak, Hubbard, and Burkey (1948), but modified slightly by us. Thus, the non-precipitable lead fraction in urine was the difference between the two measurements and this was also expressed as a percentage of the total lead. The mean total lead and the mean proportion of non-precipitable lead were 0.62 mumol/l and 48.7%, 0.35 mumol/l and 44.9%, 0.40 mumol/l and 48.9%, 0.17 mumol/l and 24.6%, 1.43 mumol/l and 44.3%, 0.14 mumol/l and 18.8% for Groups A, B, C, D, E, and F respectively, showing that a large part of urinary lead was eliminated as precipitable lead in Groups D and F who had normal lead excretion, while about half was eliminated as non-precipitable lead in the other four groups who had excessive lead excretion. No essential difference in the proportion of non-precipitable lead among Groups A, B and C excluded the possibility that the proportion might be directly related to the period of exposure to lead and to the laboratory findings of excessive lead absorption. The mean proportion of non-precipitable lead for the physiological (up to 0.240 mumol/l), intermediate (0.241 to 0.721 mumol/l), and excessive (above 0.722 mumol/l) total lead levels was 26.7, 41.3, and 52.3% respectively, in the lead workers comprising Groups A, B, C, and E each showing increased lead excretion when grouped together. these data suggested that, when urinary lead is within the normal range, it is excreted largely as precipitable lead even in individuals exposed to lead, and that the principal conditions determining the excretion of non-precipitable lead would be the current or recent degree of lead absorption. The excretory mechanisms and the biological significance of the non-precipitable lead are also discussed.     

Electroextraction of lead from a lead trilonate solution

Laboratory studies of the cathode process of the electroextraction of zinc from the trilonate electrolyte obtained after the purification of solutions after leaching lead cakes of zinc production are performed. The potential scan rate is determined by recording potentiodynamic curves; the optimal electrolyte acidity, the composition, and the temperature are established. Values of activation energy confirming the concentration nature of process polarization are found.     

Automated detection of clustered microcalcifications on mammograms: CAD system application to MIAS database

To investigate the detection performance of our automated detection scheme for clustered microcalcifications on mammograms, we applied our computer-aided diagnosis (CAD) system to the database of the Mammographic Image Analysis Society (MIAS) in the UK. Forty-three mammograms from this database were used in this study. In our scheme, the breast regions were firstly extracted by determining the skinline. Histograms of the original images were used to extract the high-density area within the breast region as the segmentation from the fatty area around the skinline. Then the contrast correction technique was employed. Gradient vectors of the image density were calculated on the contrast corrected images. To extract the specific features of the pattern of the microcalcifications, triple-ring filter analysis was employed. A variable-ring filter was used for more accurate detection after the triple-ring filter. The features of the detected candidate areas were then characterized by feature analysis. The areas which satisfied the characteristics and specific terms were classified and displayed as clusters. As a result, the sensitivity was 95.8% with the false-positive rate at 1.8 clusters per image. This demonstrates that the automated detection of clustered microcalcifications in our CAD system is reliable as an aid to radiologists.     

论铅业的废铅资源

采用废铅指数(S)作为衡量废铅资源状况的指标,简明地分析了铅产量变化、废铅回收状况与S值之间的关系。结果表明,铅产量增长,会造成废铅资源短缺;反之,产量下降,废铅资源将比较充足;产量不变,废铅资源状况介于以上二者之间。废铅实得率愈高,废铅资源愈充足。根据统计数据,估算了1990～2000年间中国、瑞典、美国的S值,讨论了这三个国家S值不同的原因及其今后可能发生的变化。     

Tinea mammae mimicking atopic eczema

Tinea mammae is a dermatophyte infection of the breast. Although rarely reported in this anatomical location, it can mimic other dermatoses. In this paper we describe an 85-year-old man with an erythema at the left breast which had enlarged over the previous 3 weeks. Trichophyton rubrum was isolated. Digital 20-MHz sonography revealed a reduction in echogenicity of the corium and a widened corium. Treatment with fluconazole over 5 weeks led to clearing of the lesion at the glabrous skin. At the end of therapy no difference between the involved and uninvolved skin areas was found sonographically.     

Splenic mesothelial cysts mimicking lymphagiomas

The purpose of this prospective multicenter study of 350 consecutive patients who were accepted for mitral valve surgery because of severe regurgitation, was to assess the value of preoperative transthoracic and transesophageal echocardiography in predicting the surgical strategy in severe mitral regurgitation: repair or replacement. The cardiologist predicted the surgical strategy on the basis of the echocardiographic examination, according to predefined guidelines for repair and replacement. The predicted strategy and motivation thereof were compared with the surgical findings and procedure that was performed. Agreement on the basis of transthoracic echocardiography was reached in 86% of the repair patients and on the basis of transesophageal echocardiography in 89%. Agreement on the basis of transthoracic echocardiography was reached in 74% of the replacement patients and on the basis of transesophageal echocardiography in 75%. This study underlines the potential role of echocardiography in predicting the surgical procedure to be applied, provided that both surgeon and cardiologist use the same nomenclature and that the guidelines for replacement/repair are adhered to. Both transthoracic and transesophageal echocardiography appear to be equally accurate in predicting the optimal surgical procedure in this respect.