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PubMed2002

Radiographic techniques in screen-film mammography.

The objectives of this study were to document imaging physics parameters associated with mammography physics surveys, and investigate how the choice of tube potential affects average glandular dose (AGD) and x-ray exposure time. Data from 60 mammography units were obtained pertaining to representative values of mAs, exposure time, half value layer, AGD and film density when acquiring phantom images. The survey of clinical systems showed that for a normal sized breast as represented by the mammography accreditation phantom, 60% of these units were operated at 25 kVp, and 33% at 26 kVp. Median exposure times were 1.14 s at 25 kVp and 0.73 s at 26 kVp. The median AGD was 1.62 mGy at 25 kVp and 1.51 mGy at 26 kVp. As expected, the choice of x-ray tube potential did not significantly affect the median film density value of 1.5. Five clinical systems, all from different vendors, had measurements performed of the AGD and x-ray exposure time as a function of x-ray tube potential at a constant film density. For a typical clinical x-ray unit, increasing the x-ray tube potential from 25 to 28 kVp reduced the exposure time by 50%, and reduced the AGD by 26%.

Humans↗
PubMed1992

Need for open access non-screening mammography in a hospital with a specialist breast clinic service.

OBJECTIVE: Assessment of open access non-screening mammography in a hospital with a breast clinic. DESIGN: Retrospective analysis of patients sent for first mammogram to our open access service by general practitioners and breast clinic in the year April 1989 to March 1990. SETTING: District general hospital serving 200,000 people before the introduction of breast screening. SUBJECTS: 361 symptomatic women referred directly by general practitioners and 226 women referred by the breast clinic for first, non-screening mammograms. MAIN OUTCOME MEASURES: Radiographic reports on all patients. Final diagnosis in patients reported as having possible or probable neoplasm. RESULTS: Of the women referred directly by general practitioners one (0.2%) was reported as showing probable malignancy (later histologically confirmed) and 15 (4%) as showing possible malignancy (on follow up none had proved malignancy). Of the women referred by the breast clinic 38 (17%) were reported as showing probable malignancy (all had confirmed carcinomas) and 35 (15%) as showing possible malignancy (19 (54%) had proved malignancy). 18 of the proved malignancies were in women under 50 years old, 26 were in women over 64 years, and 14 were in women of screening age. 54 (93%) of the 58 patients with proved breast cancer and an abnormal mammogram had a discrete breast lump. CONCLUSIONS: General practitioners accurately divided women into low and high risk groups, resulting in few abnormalities being detected in patients referred directly for mammography. This suggests that an open access non-screening mammography service for general practitioners is unnecessary in an area with a specialist breast clinic. The large proportion of cancers in women outside of screening age emphasises the need for such clinics.

Adult↗
PubMed2005

Breast cancer mortality in Copenhagen after introduction of mammography screening: cohort study.

OBJECTIVES: To evaluate the effect on breast cancer mortality during the first 10 years of the mammography service screening programme that was introduced in Copenhagen in 1991. DESIGN: Cohort study. SETTING: The mammography service screening programme in Copenhagen, Denmark. PARTICIPANTS: All women ever invited to mammography screening in the first 10 years of the programme. Historical, national, and historical national control groups were used. MAIN OUTCOME MEASURES: The main outcome measure was breast cancer mortality. We compared breast cancer mortality in the study group with rates in the control groups, adjusting for age, time period, and region. RESULTS: Breast cancer mortality in the screening period was reduced by 25% (relative risk 0.75, 95% confidence interval 0.63 to 0.89) compared with what we would expect in the absence of screening. For women actually participating in screening, breast cancer mortality was reduced by 37%. CONCLUSIONS: In the Copenhagen programme, breast cancer mortality was reduced without severe negative side effects for the participants.

Aged↗
PubMed1969

Mammography in management of breast lesions.

Comparison of the clinical and mammography findings in 101 histologically proved breast lesions showed that the accuracy of each method in diagnosing carcinoma was about 90%, but when taken together an accuracy of 98% was reached. Though mammography was less accurate in the diagnosis of benign lesions, it was found to be a valuable complement in the management of a lesion in the large atrophic breast and for showing an impalpable carcinoma. In mammography of the young dense breast a negative result must be interpreted with caution.

Adult↗
PubMed1997

Enthusiasm or uncertainty: small area variations in the use of mammography services in Ontario, Canada.

STUDY OBJECTIVE: To examine the variation in mammography utilisation in relation to age group and indication across health planning regions in Ontario, Canada. DESIGN: This study includes all women aged 30 and over in Ontario who received a mammogram between July 1, 1990 and December 31, 1991. Data from a sample of 10,000 women aged 50-69 were used to assign mammogram indication as "screening", "possible diagnostic", or "probable diagnostic" based on previous health care utilisation patterns. Age specific rates and age adjusted rates in relation to age group (30-39, 40-49, 50-69, and 70 + years) and region were derived. MAIN RESULTS: Overall, 572,762 women received one or more mammograms. Rates increased from 30-54 years and decreased thereafter. Similar variations were seen in the 40-49 and 50-69 age groups. The ranking in the area specific rates remained consistent for all ages except the 30-39 year range. In relation to indication, the largest variation across regions occurred in the screening group. CONCLUSIONS: Mammography utilisation varies across age groups. The greatest variability is for screening, probably because of physician referral patterns, patient uptake, and perhaps access to mammography. The extent of variation was similar when compared between groups where recommendations were consistent (ages 50-59) and where they were inconsistent (ages 40-49) suggesting that perhaps enthusiasm rather than uncertainty is related to regional variation for this procedure.

Adult↗
PubMed1998

Efficiency of cancer detection during routine repeat (incident) mammographic screening: two versus one view mammography.

OBJECTIVE: To examine the influence of one view versus two view mammography on cancer detection and recall for further investigation of women attending incident (subsequent) screening. SETTING: All cancers (invasive and in situ) detected as incident cases during the second screening round (January 1994 to January 1997) at the South West London Breast Screening Service were used. This service uses two view mammography and double reading, with arbitration by a third or further readers for all screens. METHODS: Mammograms of cases were mixed with those of controls in a 1:2 ratio in nine test sets; each set was read independently by three film readers. Fourteen readers, each reading from one to four test sets, took part in the study. Initially, the oblique view only was read, then the craniocaudal view was read in addition. Previous films were available to the readers. Data on abnormalities noted on the films and probability of recall were recorded and analysed. RESULTS: 10 of the 14 readers obtained increased sensitivity using two views (p = 0.04), for two readers there was no difference, and for two readers sensitivity decreased. The mean sensitivity increase was 6.1% (p = 0.01). The overall increase in sensitivity from all readings of invasive cancers was 8.9%, with no increase seen for in situ cancers. 11 of the 14 readers obtained an increase in specificity (p = 0.006), two readers showed no increase, and the specificity for one reader was decreased. The mean increase in specificity using two views was 5.7% (p = 0.006). CONCLUSION: This study showed an increase of 8.9% in sensitivity for the detection of invasive cancers when two views are used at incident screening, with a ratio of two control mammograms for every case. This is equivalent to a sample from population screening with a cancer detection rate of 333 per 1000. Such a study is considered to be likely to underestimate the benefit of two views in screening under non-test conditions where the cancer detection rate is of the order of five per 1000. The use of two view mammography for the detection of in situ cancers showed no increased benefit. A randomised controlled trial is needed to obtain a reliable estimate of the increase in cancer detection rate for incident screening in normal populations.

Female↗
PubMed1999

Proficiency test for screening mammography: results for 117 volunteer Italian radiologists.

OBJECTIVE: To analyse the performance of a large sample of Italian radiologists undergoing a proficiency test for screening mammography. DESIGN: Evaluation of performance indicators according to reference standards determined by a panel of experts (sensitivity (reference standard > or = 80%), recall rate (reference standard < or = 15%)). SETTING: 117 Italian radiologists of varying experience (years of practice 0.5-18, average 5.9; mammograms read 500-51,000, average 13,000), all currently reporting clinical mammography and planning to take part in screening in the near future. RESULTS: Eighty four of 117 (72%) radiologists reached the standard for sensitivity, 88 (75%) reached the standard for recall rate, and only 59 (50%) reached both standards and passed the proficiency test. The probability of passing the test was significantly correlated with mammographic practice (p = 0.015), mammograms read (p = 0.024), and mammograms read/year (p = 0.043). DISCUSSION: The performance of a large sample of Italian radiologists currently reporting clinical mammography was disappointing, indicating the need for proper training of at least 50% of the tested subjects. When implementing organised screening the health authority should set up a proper process for training and accrediting radiologists, and a proficiency test should be part of such a process.

Chi-Square Distribution↗
PubMed1999

Observer variability in cancer detection during routine repeat (incident) mammographic screening in a study of two versus one view mammography.

OBJECTIVE: To examine the reasons for observer variability of cancer detection using one and two view mammography at incident (subsequent) screening and determine whether false negative results (non-recall of a cancer) are due to failure to detect the associated features(s) of the cancer on the mammogram, or misinterpretation of the observed feature(s) as not indicative of malignancy. SETTING: A random selection of cancers (invasive and in situ) seen as incident cases during the second screening round (January 1994-January 1997) in the South West London Breast Screening Service were used. This service uses two view mammography and double reading with arbitration by a third or further readers for all screens. METHODS: Mammograms of cases were mixed with those of controls in a 1:2 ratio in two test sets. Eleven experienced film readers, each reading both test sets, took part in the study. Initially the oblique view only was read, then, additionally, the craniocaudal view. Previous films were available to the readers. Data on abnormalities noted on the films and probability of recall were recorded and analysed. RESULTS: 387 valid readings of 36 cancers (30 invasive and six ductal carcinoma in situ) were made by 11 readers. The overall sensitivity increased from 79% with one view to 85% with two views. For invasive cancers < 10 mm the sensitivity was 71% with one view, but increased to 85% with two views. Recall of individual cancers by the readers varied substantially. With one view 15 (50%) of the 30 invasive cancers were recalled by all 11 readers, increasing to 18 (60%) with two views. Of the invasive cancers not recalled by all 11 readers, there was considerable disagreement, particularly for the smaller cancers. With one view 69% of invasive cancers < 10 mm were correctly marked on the proforma compared with 87% with two views. Invasive cancers > 10 mm were almost all marked on the proforma with one or two views. For invasive cancers, the misinterpreted feature that did not lead to recall was most commonly an asymmetry (42%), whereas for in situ cancers it was calcifications (67%). The finding of an irregular mass was the least misinterpreted feature. CONCLUSION: The study showed that of those invasive cancers detected at routine repeat screening by a programme using two view mammography and double reading with arbitration, at least 50% could be described as "difficult" (for example, "minimal" signs) to recall using the single reading of one view, even under "favourable" study conditions with two normal subjects per case. The finding that at least 87% of invasive cancers < 10 mm are detected (marked on the proforma) with two views, but only 69% with the one view, suggests that for single reading of mammograms with one view the detection of small invasive cancers is a major problem. This problem is helped by the second view. For invasive cancers > or = 10 mm, interpretation (benign or malignant) rather than detection (under these study conditions) was the major cause of recall failure. The most common signs to be misinterpreted were calcifications and asymmetries; once visualised an irregular mass was least likely to be misinterpreted. This study provides evidence that detection and interpretation of most invasive cancers is improved by increasing the number of views, and by increasing the number of readers.

Breast Neoplasms↗
PubMed2000

The sensitivity, specificity, and positive predictive value of screening mammography and symptomatic status.

OBJECTIVE: To examine whether the accuracy of screening mammography varies according to symptomatic status reported at the time of screening. SETTING: Victoria, Australia, where free biennial screening is provided to women aged 40 and older. METHODS: We examined the sensitivity, specificity, and the positive predictive value of screening mammography by symptom status in 106,826 women from Victoria, who attended for first round mammography in 1994 and who did not have a personal history of breast cancer. Symptomatic status was divided into the following categories: asymptomatic; significant symptoms, if the woman reported a breast lump and/or blood stained or watery nipple discharge; and other symptoms, if reported. Unconditional logistic regression modelling was used to adjust for age, use of hormone replacement therapy (HRT), and family history. RESULTS: Sensitivity was lower for women with other symptoms (60.0%) than asymptomatic women (75.6%), or women with significant symptoms (80.8%). Specificity was lower for women with significant symptoms (73.7%) than asymptomatic women (94.9%), or women with other symptoms (95.4%). Among women who had invasive cancer detected during screening interval, women with other symptoms were more likely to get a false negative result (odds ratio 1.79, 95% confidence interval 1.03 to 3.04) than asymptomatic women, after adjusting for age, use of HRT, and family history. CONCLUSION: The lower sensitivity in women with other symptoms requires further investigation. Possible explanations include increased breast density and poor image quality. The high sensitivity in women with significant symptoms is probably due to more cautious radiological practice, which has also resulted in low specificity in this group.

Adult↗
PubMed2001

Service screening with mammography of women aged 50-69 years in Sweden: effects on mortality from breast cancer.

OBJECTIVES: To estimate the effect of the population based service screening programme in Sweden on mortality from breast cancer among women aged 50-69. SETTING; In 1986, population based service screening with mammography started in Sweden, and by 1997 screening had been introduced in all counties. Half of the counties invite women from 40 years of age whereas women 50 and older are invited in the other counties. The upper age limit was either 69 or 74. Women in the age group 50-69 years are thus invited to screening in all counties. METHODS: The counties which started with mammographic screening in 1986-87 constituted the study group and were compared with the counties which started in 1993 or later. In 1987 the mean number of women aged 50-69 was 161,986 and 98,608 in the study and control groups, respectively. Refined excess mortality (smoothed with the Lowess method) from breast cancer and refined cause specific mortality from breast cancer were used as effect measures. To adjust for geographical differences in mortality from breast cancer a reference period was used. Allowance was made for two potential biases: (a) inclusion bias implying the inclusion of cases diagnosed before invitation to screening in the first screening round, and (b) lead time bias. RESULTS: After a mean follow up time of 10.6 years since the start of screening and a mean individual follow up time of 8.4 years, a non-significant reduction in refined excess mortality for breast cancer was estimated as relative risk (RR) 0.84 (95% confidence interval (95% CI) 0.67 to 1.05). After adjustment for inclusion and lead time biases the RR was 0.80 (20% reduction). Only 27% of the deaths from breast cancer in the total mortality for women aged 50-79 at death consisted of women aged 50-69 at diagnosis who were diagnosed after the start of screening. This figure has important implications for judgement of the impact of screening on age specific national breast cancer mortalities. CONCLUSIONS: A non-significant reduction in mortality from breast cancer was found in counties performing service screening with mammography in Sweden. Adjustment for possible biases changed the result towards a larger effect of screening. The results do not contradict the effects found in the Swedish randomised mammography trials.

Aged↗
PubMed1977

Ultrasound mammography.

Ultrasound mammography was performed with unique, high resolution equipment which displays changes in acoustic properties of tissues through a calibrated gray scale. Color-coded isodensitometry was used to assist in the differential diagnosis. The rate of agreement between the ultrasound and pathological diagnoses was 86.7%. The false negative and false positive rates were 7.6% and 18.5%, respectively. Three problems must be solved before ultrasound mammography can be used as a screening device: First, additional clinical data must be accumulated. Second, the number of ultrasonograms needed for diagnosis must be reduced. Third, special equipment designed for ultrasound mammography must be developed.

Adenocarcinoma, Scirrhous↗
PubMed1978

Optimization of electrostatic imaging systems for minimum patient dose or minimum exposure in mammography.

The x-ray photon energies that give the highest signal-to-noise ratios per unit of exposure or average dose in mammography are significantly greater than those used in current film/screen systems. Optimum photon energies for detection of calcifications in a range of thicknesses of water and fat were calculated. Soft-tissue targets were also considered. Comparison of the theoretical results and those obtained experimentally with the Stanton mammography phantom indicate that operation at less than optimum photon energies is a major cause of inefficiency in film/screen mammography. On the other hand, electrostatic imaging systems, because of their processing flexibility, can operate at the optimum photon energy levels, thus minimizing either dose or exposure.

Elementary Particles↗
PubMed1990

AAPM tutorial. Physics of mammography: image recording process.

The many physical factors that influence image processing and image quality in mammography are reviewed in this tutorial. The physics principles that are at work in the function of screen-film mammographic image receptors are discussed in detail. The author reviews methods of quality control for screen-film mammography and the principles for xeromammography and magnification mammography.

Female↗
PubMedDate not supplied

Quality assurance in mammography: artifact analysis.

Evaluation of mammograms for artifacts is essential for mammographic quality assurance. A variety of mammographic artifacts (i.e., variations in mammographic density not caused by true attenuation differences) can occur and can create pseudolesions or mask true abnormalities. Many artifacts are readily identified, whereas others present a true diagnostic challenge. Factors that create artifacts may be related to the processor (eg, static, dirt or excessive developer buildup on the rollers, excessive roller pressure, damp film, scrapes and scratches, incomplete fixing, power failure, contaminated developer), the technologist (eg, improper film handling and loading, improper use of the mammography unit and related equipment, positioning and darkroom errors), the mammography unit (eg, failure of the collimation mirror to rotate, grid inhomogeneity, failure of the reciprocating grid to move, material in the tube housing, compression failure, improper alignment of the compression paddle with the Bucky tray, defective compression paddle), or the patient (e.g., motion, superimposed objects or substances [jewelry, body parts, clothing, hair, implanted medical devices, foreign bodies, substances on the skin]). Familiarity with the broad range of artifacts and the measures required to eliminate them is vital. Careful attention to darkroom cleanliness, care in film handling, regularly scheduled processor maintenance and chemical replenishment, daily quality assurance activities, and careful attention to detail during patient positioning and mammography can reduce or eliminate most mammographic artifacts.

Artifacts↗
PubMed2002

Palpable breast thickening: role of mammography and US in cancer detection.

PURPOSE: To determine the frequency of breast carcinoma and ascertain the diagnostic yield of mammography and breast ultrasonography (US) in the detection of breast carcinoma in women with palpable breast thickening. MATERIALS AND METHODS: One hundred twenty-three consecutive cases of breast thickening (103 patients) during a 1-year period were reviewed. Experienced breast examiners prospectively identified patients with breast thickening. Results of diagnostic mammographic work-up, breast US, breast biopsy, and clinical follow-up were retrospectively reviewed. RESULTS: Six (5%) of 123 cases had a diagnosis of breast carcinoma; five (83%) of the six had invasive carcinoma. Mammography was performed in all cases, US in 77 (63%) cases. Mammographic sensitivity for invasive cancer detection was 60% (three of five cases), specificity was 94% (102 of 108 cases), and negative predictive value was 97% (102 of 105 cases). Sensitivity of US alone was 100% (two of two cases), specificity was 96% (65 of 68 cases), and negative predictive value was 100% (65 of 65 cases). The combined negative predictive value of mammography and US was 100%. Patients with prior biopsies at the site of palpable thickening accounted for most false-negative mammograms. Median time to initiate follow-up of patients in whom biopsy was not performed was 14 months. CONCLUSION: Breast cancer was discovered in 5% of women with palpable breast thickening. Women with negative mammograms and US scans are at low risk for cancer but should, in our opinion, be followed up at short-term intervals with clinical examination and imaging if biopsy is not elected by their surgeon or clinician.

Adult↗
PubMed2005

Digital mammography.

In digital mammography, the processes of image acquisition, display, and storage are separated, which allows optimization of each. Radiation transmitted through the breast is absorbed by an electronic detector, the response of which is faithful over a wide range of intensities. Once this information is recorded, it can be displayed by using computer image-processing techniques to allow arbitrary settings of image brightness and contrast, without the need for further exposure to the patient. In this article, the current state of the art in technology for digital mammography and data from clinical trials that support the use of the technology will be reviewed. In addition, several potentially useful applications that are being developed with digital mammography will be described.

Adult↗
PubMed2005

Does litigation influence medical practice? The influence of community radiologists' medical malpractice perceptions and experience on screening mammography.

PURPOSE: To assess the relationship between radiologists' perception of and experience with medical malpractice and their patient-recall rates in actual community-based clinical settings. MATERIALS AND METHODS: All study activities were approved by the institutional review boards of the involved institutions, and patient and radiologist informed consent was obtained where necessary. This study was performed in three regions of the United States (Washington, Colorado, and New Hampshire). Radiologists who routinely interpret mammograms completed a mailed survey that included questions on demographic data, practice environment, and medical malpractice. Survey responses were linked to interpretive performance for all screening mammography examinations performed between January 1, 1996, and December 31, 2001. The odds of recall were modeled by using logistic regression analysis based on generalized estimating equations that adjust for study region. RESULTS: Of 181 eligible radiologists, 139 (76.8%) returned the survey with full consent. The analysis included 124 radiologists who had interpreted a total of 557 143 screening mammograms. Approximately half (64 of 122 [52.4%]) of the radiologists reported a prior malpractice claim, with 18 (14.8%) reporting mammography-related claims. The majority (n = 51 [81.0%]) of the 63 radiologists who responded to a question regarding the degree of stress caused by a medical malpractice claim described the experience as very or extremely stressful. More than three of every four radiologists (ie, 94 [76.4%] of 123) expressed concern about the impact medical malpractice has on mammography practice, with over half (72 [58.5%] of 123) indicating that their concern moderately to greatly increased the number of their recommendations for breast biopsies. Radiologists' estimates of their future malpractice risk were substantially higher than the actual historical risk. Almost one of every three radiologists (43 of 122 [35.3%]) had considered withdrawing from mammogram interpretation because of malpractice concerns. No significant association was found between recall rates and radiologists' experiences or perceptions of medical malpractice. CONCLUSION: U.S. radiologists are extremely concerned about medical malpractice and report that this concern affects their recall rates and biopsy recommendations. However, medical malpractice experience and concerns were not associated with recall or false-positive rates. Heightened concern of almost all radiologists may be a key reason that recall rates are higher in the United States than in other countries, but this hypothesis requires further study.

Adult↗
PubMed2006

Performance benchmarks for screening mammography.

PURPOSE: To retrospectively evaluate the range of performance outcomes of the radiologist in an audit of screening mammography by using a representative sample of U.S. radiologists to allow development of performance benchmarks for screening mammography. MATERIALS AND METHODS: Institutional review board approval was obtained, and study was HIPAA compliant. Informed consent was or was not obtained according to institutional review board guidelines. Data from 188 mammographic facilities and 807 radiologists obtained between 1996 and 2002 were analyzed from six registries from the Breast Cancer Surveillance Consortium (BCSC). Contributed data included demographic information, clinical findings, mammographic interpretation, and biopsy results. Measurements calculated were positive predictive values (PPVs) from screening mammography (PPV(1)), biopsy recommendation (PPV(2)), biopsy performed (PPV(3)), recall rate, cancer detection rate, mean cancer size, and cancer stage. Radiologist performance data are presented as 50th (median), 10th, 25th, 75th, and 90th percentiles and as graphic presentations by using smoothed curves. RESULTS: There were 2 580 151 screening mammographic studies from 1 117 390 women (age range, <30 to >/=80 years). The respective means and ranges of performance outcomes for the middle 50% of radiologists were as follows: recall rate, 9.8% and 6.4%-13.3%; PPV(1), 4.8% and 3.4%-6.2%; and PPV(2), 24.6% and 18.8%-32.0%. Mean cancer detection rate was 4.7 per 1000, and the median [corrected] mean size of invasive cancers was 13 mm. The range of performance outcomes for the middle 80% of radiologists also was presented. CONCLUSION: Community screening mammographic performance measurements of cancer outcomes for the majority of radiologists in the BCSC surpass performance recommendations. Recall rate for almost half of radiologists, however, is higher than the recommended rate.

Adult↗