Biomedical subjects

E K Fishell

Publications and source records attributed to E K Fishell.

5 recordsLinked to original sources

PubMed1996

Magnetic resonance imaging in potential postsurgical recurrence of breast cancer: pitfalls and limitations.

OBJECTIVE: To determine the sensitivity and specificity of magnetic resonance imaging (MRI) of the breast for detecting recurrent carcinoma. PATIENTS AND METHODS: Thirteen patients ranging in age from 47 to 77 years who had undergone lumpectomy 5 months to 8 years earlier and who had mammographic findings suggestive of recurrence underwent contrast-enhanced dynamic MRI. Histologic confirmation was obtained in all cases. RESULTS: Of the eight lesions (in seven patients) for which biopsy proved recurrence, MRI correctly identified six; there were two false negative results. Of the six benign lesions, four were correctly identified by MRI. The two false positive results involved fat necrosis and a foreign-body reaction respectively. CONCLUSION: These results confirm previous reports of the poor specificity of MRI of focal breast lesions. The authors therefore recommend caution in the use of breast MRI in the assessment and management of suspected recurrent carcinoma.

Aged↗

PubMed1995

Quantitative classification of mammographic densities and breast cancer risk: results from the Canadian National Breast Screening Study.

BACKGROUND: The radiographic appearance of the female breast varies from woman to woman depending on the relative amounts of fat and connective and epithelial tissues present. Variations in the mammographic density of breast tissue are referred to as the parenchymal pattern of the breast. Fat is radiologically translucent or clear (darker appearance), and both connective and epithelial tissues are radiologically dense (lighter appearance). Previous studies have generally supported an association between parenchymal patterns and breast cancer risk (greater risk with increasing densities), but there has been considerable heterogeneity in risk estimates reported. PURPOSE: Our objective was to determine the level of breast cancer risk associated with varying mammographic densities by quantitatively classifying breast density with conventional radiological methods and novel computer-assisted methods. METHODS: From the medical records of a cohort of 45,000 women assigned to mammography in the Canadian National Breast Cancer Screening Study (NBSS), a multicenter, randomized trial, mammograms from 354 case subjects and 354 control subjects were identified. Case subjects were selected from those women in whom histologically verified invasive breast cancer had developed 12 months or more after entering the trial. Control subjects were selected from those of similar age who, after a similar period of observation, had not developed breast cancer. The mammogram taken at the beginning of the NBSS was the image used for measurements. Mammograms were classified into six categories of density, either by radiologists or by computer-assisted measurements. All radiological classification and computer-assisted measurements were made using one craniocaudal view from the breast contralateral to the cancer site in case subjects and the corresponding breast of control subjects. All P values represent two-sided tests of statistical significance. RESULTS: For all subjects, there was a 43% increase in the relative risk (RR) between the lower and the next higher category of density, as determined by radiologists, and there was a 32% increase as determined by the computer-assisted method. For all subjects, the RR in the most extensive category relative to the least was 6.05 (95% confidence interval [CI] = 2.82-12.97) for radiologists and 4.04 (95% CI = 2.12-7.69) for computer-assisted methods. Statistically significant increases in breast cancer risk associated with increasing mammographic density were found by both radiologists and computer-assisted methods for women in the age category 40-49 years (P = .005 for radiologists and P = .003 for computer-assisted measurements) and the age category 50-59 years (P = .002 for radiologists and P = .001 for computer-assisted measurements). CONCLUSION: These results show that increases in the level of breast tissue density as assessed by mammography are associated with increases in risk for breast cancer.

Adult↗

PubMed1992

Evaluation of mammographic image quality: pilot study comparing five methods.

A radiograph is considered of high quality when it allows a radiologist to identify abnormalities with high sensitivity and specificity. Although many methods for assessing image quality have been devised, it is not clear which is most meaningful or how well these methods correlate with one another. A pilot study was undertaken to compare five methods of evaluating mammographic image quality. Each of the methods was used to form separate rankings of 11 mammographic system configurations. In two of the methods, observers (three radiologists and three physicists) subjectively ranked the "image quality" of radiographs of phantoms obtained with each configuration. The third method ranked the systems according to contrast as measured densitometrically with an aluminum step wedge, and the fourth, in terms of lowest to highest mean glandular radiation doses to the breast. In the final method, observers based their rankings on mammograms of patients. The intra- and interobserver variabilities of each ranking method were assessed, as well as the correlations between methods, by using standard nonparametric statistical tests. Intraobserver consistency was high with any of the image quality ranking methods; however, image quality rankings based on either of the two phantoms provided better agreement among observers than did rankings based on images of patients. Surprisingly, no significant degree of correlation was found between any two image quality evaluation methods. Our work may have two implications for the American College of Radiology Mammography Accreditation Program: (1) small variations in phantom scores do not necessarily correlate with subjective variation in image quality in radiographs of patients, and (2) when small numbers of radiographs are used, the assessment of the quality of mammograms of patients may vary considerably among radiologists.

Accreditation↗

PubMed1990

Clinical performance of a cone/annular array ultrasound breast scanner.

Ultrasound is a useful adjunctive imaging modality to x-ray mammography for the detection and management of breast disease. A high resolution (0.3 mm at -6 dB) transducer consisting of co-axially aligned cone and annular array transducers has been incorporated into a prototype breast imaging system. The prototype scanner had an operating frequency of 4 MHz and scanning was performed in the prone position. We hypothesized that the increased resolution of this system would lead to improved detection of smaller, nonpalpable lesions and would thus contribute to the early detection of breast cancer. Results of a four year clinical study of the prototype involving 1743 patients are reported. The overall true positive (TP) fraction for the detection of malignancy was 52.5% compared with 86.6% for x-ray mammography. Improved performance of ultrasound approaching that of mammography is demonstrated for the youngest age group (less than 34 years) and for women whose breasts are predominantly dysplastic. However, the detection of nonpalpable tumours is disappointing with a TP fraction of only 22%. Causes for the failure of the prototype breast scanner to detect early breast lesions are presented and general conclusions on the use of large aperture transducers for automated breast imaging are discussed.

Adolescent↗

PubMed1988

Ultrasonographically defined parenchymal patterns of the breast: relationship to mammographic patterns and other risk factors for breast cancer.

We have used ultrasound of the breast to define four parenchymal patterns in which increasing proportions of the breast are replaced by densely echogenic tissue. A series of 452 symptomatic women examined by both ultrasound and conventional X-ray mammography was reviewed to determine whether these ultrasonographic images could predict the breast parenchymal pattern defined mammographically. A very strong correlation was demonstrated between the breast pattern on ultrasound and the volume of the breast replaced by either dysplasia (Kendall's tau-b = 0.731 +/- 0.026, p less than 0.0001) or ductal prominence (Kendall's tau-b = 0.641 +/- 0.049, p less than 0.0001). This was seen both on initial reporting and on a blind re-reading of a random sample of 100 cases. The strength of correlation was similar for subgroups defined by family history of breast cancer, age, menopausal status, and history of benign breast disease, and the breast parenchymal pattern assessed by mammography or ultrasound showed similar associations with these variables. Ultrasonographic parenchymal patterns of the breast can predict the tissue patterns defined mammographically and may therefore be useful as a marker of breast cancer risk.

Adult↗