Accuracy of mammography in an Australian community setting.
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RATIONALE AND OBJECTIVES: The purpose of this project was to develop and evaluate an educational program targeted at mammography facilities in rural areas of North Carolina that were having difficulty complying with the 1992 Mammography Quality Standards Act (MQSA). MATERIALS AND METHODS: Fourteen facilities deemed at risk for closure under MQSA were identified by state inspection personnel. Problems at the facilities were evaluated by a radiologist, a physicist-educator, and a radiation physicist through a written survey, review of phantom and clinical images, and a site visit. Individual advice and instruction were provided on-site by the physicist-educator, with written materials provided in follow-up. A repeat site visit was made 4-6 months after the initial visit. RESULTS: Of 51 problems identified at the 12 institutions that completed the program, 35 (69%) were corrected. All facilities that had failing phantom scores at the inspection prior to the intervention had passing scores at the inspection after the intervention. There was a statistically significant increase in the sum of the phantom scores for the facilities offered this intervention compared with those not offered it (P = .03). CONCLUSION: This educational program improved mammography quality at participating facilities.
PURPOSE: To evaluate the conspicuity of microcalcifications in magnified mammographic views of preparations obtained with full field digital mammography (FFDM), film-screen mammography (FSM), and the DIMA technique. MATERIAL AND METHODS: Twelve preparations were examined by FFDM and FSM using 1.8 x magnification and DIMA using 7 x magnification. Parameter settings were identical for all three techniques. The number of visible microcalcifications was then determined for each modality by three radiologists. As far as possible, all preparations were X-rayed at 22 kV and 10 mAS. RESULTS: Altogether 9705 calcifications were counted (DIMA: 1609/1542/1534; FFDM: 1020/753/881; FSM: 901/643/822). The total number of microcalcifications identified with the DIMA technique was 4685 as compared to 2654 with FFDM and 2366 with FSM. The calcifications counted with FFDM and FSM thus corresponded to 56.6 % and 50.5 %, respectively, of those identified with DIMA. The differences between the groups were statistically significant (F-Test, p < 0.05). CONCLUSION: Significantly more calcifications are identified when magnified mammographic views of preparations containing microcalcifications are obtained with the DIMA technique compared to FFDM or FSM. FFDM depicts markedly more calcifications than FSM. This means one should increase spatial resolution. Digital mammography offers the potential for improved visualization of microcalcifications with advanced applications.
PURPOSE: Determination of image quality of a new digital mammography system with an a-Se-detector. MATERIAL AND METHOD: Radiograms of the Wisconsin Mammographic Random Phantom, Modell 152 A (Radiation Measurements Inc., Wisconsin) were acquired using a conventional film screen and a digital system. RESULTS: With the conventional film screen system there were detected 191/a 38.2 and with the digital mammography 219/a 43.8 of 225 possible details. CONCLUSION: Based on these results there is the possibility to replace the conventional film screen system by the digital mammography with a-Se-detector--this has to be confirmed in further clinical trials.
PURPOSE: To determine effects of lesion type (calcification vs mass) and image processing on radiologist's performance for area under the receiver operating characteristic curve (AUC), sensitivity, and specificity for detection of masses and calcifications with digital mammography in women with mammographically dense breasts. MATERIALS AND METHODS: This study included 201 women who underwent digital mammography at seven U.S. and Canadian medical centers. Three image-processing algorithms were applied to the digital images, which were acquired with Fischer, General Electric, and Lorad digital mammography units. Eighteen readers participated in the reader study (six readers per algorithm). Baseline values for reader performance with screen-film mammograms were obtained through the additional interpretation of 179 screen-film mammograms. A repeated-measures analysis of covariance allowing unequal slopes was used in each of the nine analyses (AUC, sensitivity, and specificity for each of three machines). Bonferroni correction was used. RESULTS: Although lesion type did not affect the AUC or sensitivity for Fischer digital images, it did affect specificity (P =.0004). For the General Electric digital images, AUC, sensitivity, and specificity were not affected by lesion type. For Lorad digital images, the results strongly suggested that lesion type affected AUC and sensitivity (P <.0001). None of the three image-processing methods tested affected the AUC, sensitivity, or specificity for the Fischer, General Electric, or Lorad digital images. CONCLUSION: Findings in this study indicate that radiologist's interpretation accuracy in interpreting digital mammograms depends on lesion type. Interpretation accuracy was not influenced by the image-processing method.
PURPOSE: To prospectively compare cancer detection rates, recall rates, and positive predictive values at screen-film mammography (SFM) with those at full-field digital mammography (FFDM) with soft-copy reading in a population-based screening program in Norway. MATERIALS AND METHODS: Of 43,429 women invited, 25,263 women aged 45-69 years attended the screening program and were randomized, with adjustments for age and area of residence, to undergo SFM or FFDM. Two standard views of each breast were acquired. Independent double reading was performed with use of a five-point rating scale for probability of cancer. Recall rates, positive predictive values, and cancer detection rates were compared for two age groups (45-49 and 50-69 years) by using the chi(2) test. RESULTS: Overall, 73 cancers in 17,911 women were detected at SFM (detection rate, 0.41%), compared with 41 cancers in 6,997 women at FFDM (detection rate, 0.59%; P =.06). In the group aged 50-69 years, 56 cancers in 10,304 women were detected at SFM (detection rate, 0.54%), compared with 33 cancers in 3,985 at FFDM (detection rate, 0.83%); the difference in cancer detection rates approached significance (P =.053). In the group aged 45-49 years, 17 cancers in 7,607 women were detected at SFM (detection rate, 0.22%), compared with eight cancers in 3,012 at FFDM (detection rate, 0.27%). Recall rates in both age groups were significantly higher at FFDM than at SFM (P <.05), but positive predictive value was not significantly different. CONCLUSION: FFDM allowed a higher cancer detection rate than did SFM in the group aged 50-69, although the difference did not reach statistical significance. The detection rate was nearly equal for the two modalities in the group aged 45-49. SFM and FFDM with soft-copy reading are comparable techniques for population-based screening mammography programs.
Radiologists with very limited practical experience in mammography initially achieved a low PVpos (0.50) and a high PVneg (0.95) in blind mammography of 80 patients with 85 excised and histologically examined breast tumours. After having read films from approximately 2500 patients the initial films were blindly reevaluated. PVneg was unchanged, whereas PVpos was elevated significantly (0.80). The intraobserver variation was 11.5 per cent. The actual interobserver variation was 3.2 per cent. These findings indicate that the reliability of blind mammography in patients with palpable tumours of the breast is considerable, also in case of only limited mammographic experience.
OBJECTIVE: We wanted to compare the ability of screen-film mammography (SFM) and soft-copy full-field digital mammography (s-FFDM) on two different monitors to detect and characterize microcalcifications. MATERIALS AND METHODS: The images of 40 patients with microcalcifications(three patients had malignant lesion and 37 patients had benign lesion), who underwent both SFM and FFDM at an interval of less than six months, were independently evaluated by three readers. Three reading sessions were undertaken for SFM and for FFDM on a mammography-dedicated review workstation (RWS, 2K x 2.5K), and for FFDM on a high-resolution PACS monitor (1.7K x 2.3K). The image quality, breast composition and the number and conspicuity of the microcalcifications were evaluated using a three-point rating method, and the mammographic assessment was classified into 4 categories (normal, benign, low concern and moderate to great concern). RESULTS: The image quality, the number and conspicuity of the microcalcifications by s-FFDM (on the RWS, PACS and both) were superior to those by SFM in 85.0%, 80.0% and 52.5% of the cases, respectively (p < 0.01), and those by the s-FFDM on the two different monitors were similar in 15.0%, 12.5% and 35.0% of the cases, respectively (p > 0.01). The mammographic assessment category for the microcalcifications in the three reading sessions was similar. CONCLUSION: s-FFDM gives a superior image quality to SFM and it is better at evaluating microcalcifications. In addition, s-FFDM with the PACS monitor is comparable to s-FFDM with the RWS for evaluating microcalcifications.
From 6/90-2/91 the daylight system EC (Fuji Ltd.), developed only for mammography, was used in the Department of Gynaecological Radiology of the Radiological Centre of the University of Freiburg for the first time in Germany. We examined 4000 patients (respectively 14,000 mammographies). We controlled the quality of the x-ray photographs every day (n = 175) and compared the results with the controls of quality, which had been carried out from 9/89-5/90 with the conventional technique (n = 175). During the entire period of research (9/89-2/91) at both systems the results of Dmin were inferior to the standard. Using the daylight system the measurements of the index of sensitivity were in 91% of the cases (n = 160), and the index of contrast in 88% (n = 154) within the range--much better than with the conventional system with 74% (130 measurements), respectively 70% (123 measurements). We also found an evident advantage of time and in future it is to be expected that the conventional system will be replaced by the daylight system in mammography.
This paper informs about the diagnostical accuracy of clinical examination and mammography at the women's Hospital of the Städtische Klinikum Zwickau from 1989 to 1992 when pathological changes of breasts are diagnosed. A total of 508 diagnostical biopsies was performed during this study period. The histological examination resulted in 276 benign breast lesions and in 232 breast cancers. In 432 cases there was a lump palpable in the breast that was noticed at first by more than 60% of women themselves. 288 (56.7%) correct and 220 (43.3%) false diagnoses were established following the clinical examination. This resulted in a sensitivity of 100% with a specificity of 20.3% and an overall accuracy of 56.7%. However, with the help of mammography 386 (76.6%) pathological changes of breasts were found to be correct. 118 mammograms proved to be false. Out of these 90 (17.8%) had a false-positive diagnosis and 28 (5.6%) a false-negative one. The overall accuracy of mammography was 76.6% (sensitivity 87.9%, specificity 67%).
Clinical studies of flow cytometric DNA analysis of breast carcinoma are often limited by the lack of fresh tissue samples from smaller, nonpalpable carcinomas. In addition, most studies measuring DNA in the current literature focus on larger palpable masses that may have less relevance to the smaller, nonpalpable lesions. A prospective study of flow cytometric DNA analysis of in vitro specimen mammography-guided fine-needle aspirates (FNAs) of 103 consecutive nonpalpable invasive carcinomas detected by screening mammography was performed to determine efficacy and explore associations with mammographic and pathological features. For 62 (60%) lesions for which DNA analysis on both FNA and standard tissue incision samples was performed, there was excellent (89%) agreement for ploidy determinations (kappa=0.77) and poor agreement for S-phase percentage determinations (kappa=0.23). Specimen mammography-guided FNA analysis detected aneuploidy in 36% of lesions overall, including 34% of 41 lesions for which standard tissue procurement was not possible. Mammographic microcalcifications had a higher aneuploid rate (14 of 28 lesions, 50%) as compared with soft tissue masses (22 of 75 lesions, 29%), P < 0.01. Lobulated masses with indistinct margins had a higher aneuploid rate (5 of 6 lesions, 83%) as compared with more irregular, spiculated masses (7 of 27 lesions, 26%), P < 0.01. The aneuploidy rate was independent of specific histological diagnosis, lesion size, nuclear grade, or nodal or estrogen receptor status. Flow cytometric DNA analysis of mammographic lesion-specific, fresh, cellular FNA samples obtained under specimen mammographic guidance can assess early invasive carcinomas when gross fresh tissue procurement is not possible. This technique could be incorporated into larger clinical follow-up studies to determine the prognostic significance of flow cytometric DNA analysis for these very early breast carcinomas.
In order to optimally integrate radiotracer breast imaging within the breast clinic, anatomy and pathology should be easily correlated with functional nuclear medicine breast images. As a first step in the development of a hybrid functional/anatomic breast imaging platform with biopsy capability, a conventional X-ray mammography gantry was modified to image the compressed breast with positron emitters. Phantom studies with the positron emission mammography (PEM) device showed that a 1-cc hot spot could be detected within 5 min. A preliminary clinical trial demonstrated in vivo visualization of primary breast cancer within 4 min. For sites where positron-emitting radionuclides are available, PEM promises to achieve low-cost directed functional examination of breast abnormalities, with the potential for achieving X-ray correlation and image-guided biopsy.
The goal of this prospective study was to compare a full-field digital mammography system (FFDM) to a conventional screen-film mammography system (SFM) for the detection and characterization of microcalcifications. Fifty-five patients with 57 isolated microcalcification clusters were examined using a FFDM system (Senographe 2000D, GE Medical Systems, Milwaukee, Wis.) and a SFM system (Senographe DMR, GE Medical Systems, Milwaukee, Wis.). A conventional screen-film mammogram and a digital contact mammogram were obtained of each cluster. The image quality and the number of calcification particles were evaluated, and a characterization (BI-RADS 1-5) of microcalcifications was given by four experienced readers. Histopathology revealed 16 benign lesions (sclerosing adenosis, dysplasia, hamartoma, radial scar) in 15 patients and 21 malignant tumors (in situ carcinoma, invasive carcinoma) in 20 patients. Twenty patients had benign changes verified by long-term follow-up. Image quality of FFDM was assessed as superior to SFM in more than 50% of the cases. The FFDM showed more calcifications in 41% of all cases. Sensitivity and specificity for FFDM vs SFM were 95.2 vs 91.9% and 41.4 vs 39.3%, respectively. Moreover, FFDM demonstrated a higher diagnostic accuracy (deviation: 0.86 BI-RADS steps) compared with FSM (deviation 0.93 BI-RADS steps). The FFDM system with a 100- micro m pixel size provides better image quality than SFM in patients with mammographic microcalcifications. The FFDM has a higher sensitivity and a higher reliability in characterizing microcalcifications.
New stationary ultra high resolution grids have been proposed as an alternative to the conventional moving grid techniques for mammography. The physical performance of the new grids resembles those of conventional grids with 1:5 grid ratio. They fail during mammography because of their inability to render fine detail and, in particular, the important shapes of micro-calcification.
PURPOSE: To compare cancer detection rates of screen-film (SFM) and full-field digital mammography (FFDM) with soft-copy reading in a screening program including the initial positive scores for interval cancers and cancers in the subsequent screening round, and to analyze the false-negative FFDM interpretations. MATERIAL AND METHODS: Using a paired study design, 3683 women underwent SFM and FFDM in a population-based screening program. Two standard views of each breast were acquired. The images were interpreted without previous films for comparison. Independent double reading using a 5-point rating scale for probability of cancer was used for each modality. An examination was defined as positive if at least one of the two independent readers scored 2 or higher on the 5-point rating scale. SFM-positive cases were discussed in a SFM consensus meeting and FFDM-positive cases in a separate FFDM consensus meeting before recall. The study population was followed for more than 2 years so that interval cancers and screen-detected cancers in the subsequent screening round could be included. Cancer detection rates were compared using the McNemar test for paired proportions. The kappa statistic and Wilcoxon signed-rank test for matched pairs were used for comparing rating scores. The reading time was recorded for all FFDM interpretations. RESULTS: A total of 31 cancers (detection rate 0.84%) were diagnosed initially, of which SFM detected 28 and FFDM 23 (McNemar test P=0.23, discordant pair 8 and 3). Two cancers with a positive score at initial SFM reading and three with a positive score at initial FFDM reading were dismissed at SFM and FFDM consensus meetings, respectively. The difference in cancer detection after recall (discordant pair 11 and 5) was not significant (McNemar test, P=0.21). Of the 10 interval cancers and 16 screen-detected cancers in the subsequent round, 3 had true-positive SFM scores while 4 had true-positive FFDM scores in the initial reading session. A total of 38 cancers therefore had a positive result at double reading at one or both modalities, 31 at SFM and 27 at FFDM (McNemar test, P=0.48). Comparison of SFM and FFDM interpretations using the mean score for each case revealed no statistically significant difference between the two modalities (Wilcoxon signed-rank test for matched pairs; P-value=0.228). Two initial round cancers (one tumor found incidentally at work-up for a mass proved to be a simple cyst with a positive score at FFDM but a negative score at SFM, and one tumor with positive score at SFM but negative score at FFDM due to positioning failure) were excluded from the further analysis. Excluding these two cancers from comparison, there were 31% (22 of 72) false-negative SFM and 47% (34 of 72) false-negative FFDM individual interpretations. The overall mean interpretation time for normal FFDM examinations was 45 s. For most false-negative FFDM results, the reading time was shorter or longer than for normal examinations. The recorded FFDM interpretation time was noticeably short for several overlooked cancers manifesting as microcalcifications (ductal carcinoma in situ). CONCLUSION: There is no statistically significant difference in cancer detection rate between SFM and FFDM with soft-copy reading in a mammography screening program. Analysis of cancers missed at FFDM with soft-copy reading indicates that close attention has to be paid to systematic use of image display protocols.
Contrast-detail experiments were performed to optimize technique factors for the detection of low-contrast lesions using a silicon diode array full-field digital mammography (FFDM) system under the conditions of a matched average glandular dose (AGD) for different techniques. Optimization was performed for compressed breast thickness from 2 to 8 cm. FFDM results were compared to screen-film mammography (SFM) at each breast thickness. Four contrast-detail (CD) images were acquired on a SFM unit with optimal techniques at 2, 4, 6, and 8 cm breast thicknesses. The AGD for each breast thickness was calculated based on half-value layer (HVL) and entrance exposure measurements on the SFM unit. A computer algorithm was developed and used to determine FFDM beam current (mAs) that matched AGD between FFDM and SFM at each thickness, while varying target, filter, and peak kilovoltage (kVp) across the full range available for the FFDM unit. CD images were then acquired on FFDM for kVp values from 23-35 for a molybdenum-molybdenum (Mo-Mo), 23-40 for a molybdenum-rhodium (Mo-Rh), and 25-49 for a rhodium-rhodium (Rh-Rh) target-filter under the constraint of matching the AGD from screen-film for each breast thickness (2, 4, 6, and 8 cm). CD images were scored independently for SFM and each FFDM technique by six readers. CD scores were analyzed to assess trends as a function of target-filter and kVp and were compared to SFM at each breast thickness. For 2 cm thick breasts, optimal FFDM CD scores occurred at the lowest possible kVp setting for each target-filter, with significant decreases in FFDM CD scores as kVp was increased under the constraint of matched AGD. For 2 cm breasts, optimal FFDM CD scores were not significantly different from SFM CD scores. For 4-8 cm breasts, optimum FFDM CD scores were superior to SFM CD scores. For 4 cm breasts, FFDM CD scores decreased as kVp increased for each target-filter combination. For 6 cm breasts, CD scores decreased slightly as kVp increased for Mo-Mo, but did not change significantly as a function of kVp for either Mo-Rh or Rh-Rh. For 8 cm breasts, Rh/Rh FFDM CD scores were superior to other target-filter combinations and increased significantly as kVp increased. These results indicate that low-contrast lesion detection was optimized for FFDM by using a softer x-ray beam for thin breasts and a harder x-ray beam for thick breasts, when AGD was kept constant for a given breast thickness. Under this constraint, optimum low-contrast lesion detection with FFDM was superior to that for SFM for all but the thinnest breasts.
A population-based, randomized breast cancer screening project was undertaken using mammography alone. Of 17,447 invited women aged 50-69, 12,765 (73%) attended the screening. On the basis of the screening films, malignancy was suspected in 405 women (3.2%) who were recalled for complete mammography. Additional films showed that the suspicion of malignancy was false in 194 women. The remaining 211 women (1.7%) were referred for clinical and cytological examination. Of these, 159 had surgery. Breast cancer was proved in 97 women, corresponding to a prevalence rate of 7.6/1000. Fifty-three (55%) of the carcinomas were either in situ or invasive with a diameter of less than or equal to 1 cm. Axillary metastases were found in 19 patients (19.6%). Cancers detected at screening were significantly less advanced than those in the control group. There was a remarkably high frequency of tubular carcinoma among cancers detected at screening.
The American College of Radiology has published a report that describes desirable features for new mammography x-ray units that will contribute to high-quality imaging. It encompasses all aspects of x-ray equipment performance including mechanical considerations, the x-ray tube focal spot and spectrum, generator performance, collimation, scatter rejection, and the automatic exposure control. The report is intended to provide guidance to equipment manufacturers and to purchasers of mammography systems with regard to basic performance levels that should be expected.