Use of prior mammograms in the transition to digital mammography: a performance and cost analysis

Breast screening in Europe is gradually changing from film to digital imaging and reporting of cases. In the transition period prior mammograms (from the preceding screening round) are films thereby potentially causing difficulties in comparison to current digital mammograms. To examine this breast screening performance was measured at a digital mammography workstation with prior mammograms displayed in different formats, and the associated costs calculated. 160 selected difficult cases (41% malignant) were read by eight UK qualified mammography readers in three conditions: with film prior mammograms; with digitised prior mammograms; or without prior mammograms. Lesion location and probability of malignancy were recorded, alongside a decision of whether to recall each case for further tests. JAFROC analysis showed a difference between conditions (p=.006); performance with prior mammograms in either film or digitised formats was superior to that without prior mammograms (p<.05). There was no difference in the performance when the prior mammograms were presented in film or digitised form. The number of benign or normal cases recalled was 26% higher without prior mammograms than with digitised or film prior mammograms (p<.05). This would correspond to an increase in recall rate at the study hospital from 4.3% to 5.5% with no associated increase in cancer detection rate. The cost of this increase was estimated to be ￡11,581 (€13,666) per 10,000 women screened, which is higher than the cost of digitised (￡11,114/€13,115), or film display (￡6451/€7612) of the prior mammograms. It is recommended that, where available, prior mammograms are used in the transition to digital breast screening.     

Current practice regarding reading previous films in the NHS Breast Screening Programme

Purpose: To evaluate current practice regarding reading previous films in the NHS Breast Screening Programme (NHSBSP) and review the imaging literature.Method: All NHSBSP units were sent a postal questionnaire. Each was asked whether they always read with previous films on the viewer? Those that answered, ‘yes’ were asked which films they display medio-lateral oblique (MLO), cranio-caudal (CC), or both?Results: Ninety-five of 101 centres replied to our postal questionnaire. Ninety-three of the 95 that replied are currently reading previous mammograms as part of their routine practice. Two units said previous mammograms are viewed only selectively. Forty-seven of the 93 that read with previous films display MLO views only. Forty-six of the 93 read both MLO and CC views if these are available.Conclusion: Consistent with ‘best practice’, most breast screening units in the NHSBSP display previous films when reading screening mammograms.     

A preliminary report on the role of spatial frequency analysis in the perception of breast cancers missed at mammography screening

RATIONALE AND OBJECTIVES: Because several factors are involved in cancer detection, a malignant lesion that is visible on a mammogram will not necessarily be reported by the radiologist reading the case. Indeed, a significant fraction of screening-detected cancers are visible in retrospect, and were perceived by the radiologist when the case was read, but were either reported as benign findings or dismissed as variations of normal breast tissue. In this preliminary report the spatial frequency characteristics of clinically missed lesions are investigated by analyzing the mammogram acquired when the lesion was sent for biopsy and the most recent prior mammogram. For control purposes, the contralateral breast is also analyzed, when this breast is lesion free. MATERIALS AND METHODS: A database of 70 mammogram cases was assembled. Each case contained eight films: craniocaudal (CC) and mediolateral oblique (MLO) of the breast where a biopsy-proven lesion was found, CC and MLO of the contralateral breast, and CC and MLO of both breasts in the most recent prior mammogram. The dictated reports for all of these cases were obtained. Both benign and malignant lesions were used. The films were digitized and an region of interest surrounding each lesion was segmented from the image for processing using wavelet packets to extract spatial frequency information. The corresponding area was also segmented from the prior mammogram and from the contralateral breast, when this breast was lesion-free. Analysis of variance was used to determine if statistically significant differences existed between the derived features of cancer in the current and prior mammograms. RESULTS: The data suggests that malignant lesions reported in the prior mammogram as being benign differed from correctly reported malignant lesions and from correctly reported benign lesions. They also differed from nonreported malignant lesions. In addition, the spatial frequency representation of cancer significantly differed in the current and prior cases from the representation of normal breast tissue. CONCLUSION: Spatial frequency analysis may be useful to differentiate malignant lesions that are reported as benign and correctly reported benign lesions.     

Can computer-aided detection with double reading of screening mammograms help decrease the false-negative rate? Initial experience

PURPOSE: To retrospectively evaluate the role of computer-aided detection (CAD) in reducing the rate of false-negative (FN) findings on screening mammograms considered normal at initial double reading. MATERIALS AND METHODS: At the authors' institution, independent prospective double readings in which the second reader is not blinded to results of the first reading are performed routinely for all mammograms. When cancer is diagnosed, prior mammograms also are reviewed with double reading to determine cancer visibility. Findings are categorized as (a) no evidence of cancer on any prior screening mammogram and patient presents more than 1 year after prior screening, (b) no evidence of cancer on any prior screening mammogram and patient presents with symptoms within 1 year after prior screening (year-interval occult false-negative), or (c) cancer visible. The clinical director separately evaluates each case in the same way. In 2000, 519 histologically proved breast cancers were diagnosed, including 132 for which patients sought a second opinion and FN findings were not tracked. Prior screening mammograms were available in 318 of the other 387 cases. Five radiologists in two reading sessions independently reviewed current and prior mammograms to categorize visible cancers as either threshold or actionable FN findings. Visible cancers deemed actionable by at least three of five readers were analyzed with a commercially available CAD system. FN rates were calculated prior to and after CAD analysis. RESULTS: Twenty-seven occult and 71 visible cancers were found (total FN findings, 98). Three of five readers considered 52 (73%) of 71 visible cancers actionable. The CAD system correctly marked 37 (71%) of these 52 on prior screening mammograms (19 [65%] of 29 masses, seven [88%] of eight microcalcifications, seven [78%] of nine architectural distortions, and four [67%] of six masses with microcalcifications). The FN rate was 98 (31%) of 318 before CAD and 61 (19%) of 318 after CAD. CONCLUSION: In this retrospective review of this small subset of cancers, it appears that CAD has the potential to decrease the FN rate at double reading by more than one-third (from 31% to 19%). The CAD system correctly marked 37 (71%) of 52 actionable findings read as negative in previous screening years.     

Mammographic characteristics of 115 missed cancers later detected with screening mammography and the potential utility of computer-aided detection

PURPOSE: To retrospectively determine the mammographic characteristics of cancers missed at screening mammography and assess the ability of computer-aided detection (CAD) to mark the missed cancers. MATERIALS AND METHODS: A multicenter retrospective study accrued 1,083 consecutive cases of breast cancer detected at screening mammography. Prior mammograms were available in 427 cases. Of these, 286 had lesions visible in retrospect. The 286 cases underwent blinded review by panels of radiologists; a majority recommended recall for 112 cases. Two experienced radiologists compared prior mammograms in 110 of these cases with the subsequent screening mammograms (when cancer was detected), noting mammographic characteristics of breast density, lesion type, size, morphology, and subjective reasons for possible miss. The prior mammograms were then analyzed with a CAD program. RESULTS: There were 110 patients with 115 cancers. On the prior mammograms with missed cancers, 35 (30%) of the 115 lesions were calcifications, with 17 of 35 (49%) clustered or pleomorphic. Eighty of the 115 (70%) were mass lesions, with 32 of 80 (40%) spiculated or irregular. For calcifications and masses, the most frequently suggested reasons for possible miss were dense breasts (12 of 35; 34%) and distracting lesions (35 of 80; 44%), respectively. CAD marked 30 (86%) of 35 missed calcifications and 58 (73%) of 80 missed masses. CONCLUSION: Detection errors affected cases with calcifications and masses. CAD marked most (77%; 88 of 115) cancers missed at screening mammography that radiologists retrospectively judged to merit recall.     

Effects of lesion conspicuity on visual search in mammogram reading

RATIONALE AND OBJECTIVES: The goal of mammography screening is to detect breast cancer at early stages, but because of the complexity of the breast parenchyma and the variability of signs of the disease, many cancers go unreported when initially visible on the mammogram. We compared the visual search strategy used by experienced mammographers in a case set where they examined both the mammogram in which a malignant mass was discovered at screening mammography and the most recent prior mammogram. MATERIALS AND METHODS: Four experienced mammographers participated in this experiment. They read a case set of 20 two-view mammograms, of which 15 contained a malignant mass and 5 were lesion-free, in two trials. For each of the cancer cases, two versions were shown to the observers: the one in which the cancer was reported in the clinical practice, called the "current" mammograms, and the most recent prior. Each trial had a balanced mix of current and prior mammograms. In addition, the same set of lesion-free cases was shown to the observers in both trials. The eye movements of the observers were tracked, and visual search parameters such as time to hit the location of the malignant mass, dwell, and mean pupil size in the location of the cancer were collected. Statistical analyses were used to determine whether there were differences between the current and prior mammograms. RESULTS: A total of 66% of the malignant masses in the current mammograms and 57% in the priors attracted some amount of visual attention. From these, 71% yielded a report on the current mammograms, but only 40% on the priors. In the cases where the observer saw the malignant mass, they did so within 2 seconds of image display, regardless of whether the mammogram was current or prior. CONCLUSION: Most unreported malignant masses attracted some amount of visual attention, but it was in the processing of the information extracted in the location of the lesion that most errors occurred. In our experiment, approximately 70% of the total time used by the observers for visual scan of the cases was spent gathering information to corroborate the hypothesis already formed by the radiologist.     

Is radiologists' volume of mammography reading related to accuracy? A critical review of the literature

The current UK quality assurance guidelines for radiologists in the NHS breast screening programme require those reporting screening mammograms to read a minimum of 5000 cases per year. We aimed to review the evidence for this and to assess whether there was justification for lowering the required level. A literature search was conducted to identify relevant studies where accuracy of reporting mammograms was related to reading volume. Three of the five studies reviewed suggested a positive association between reading volume and sensitivity, but there were few data on volumes above 5000 cases per year. The available evidence did not provide any basis for reducing the threshold volume. Further work is needed, in a UK or European setting, to study the relationship between reading volume and accuracy at higher volume levels and also the separate effects of reading volume and reading experience.     

Computer-aided detection versus independent double reading of masses on mammograms

PURPOSE: To evaluate the use of a computer-aided detection (CAD) system (designed for mammographic mass detection) to help improve mass interpretation and to compare CAD results with independent double-reading results. MATERIALS AND METHODS: Screening mammograms from 500 cases were collected; 125 of these cases were screening-detected cancers, and 125 were interval cancers. Previously obtained screening mammograms (ie, prior mammograms) were available in all cases. All mammograms were analyzed by a CAD system, which detected mass regions and assigned a level of (cancer) suspicion to each mass. Ten experienced screening radiologists read the prior mammograms. For independent interpretation with CAD, the suspicion rating assigned to each finding by the radiologist was weighted with the CAD output at the area of the finding. CAD markers on areas that were not reported by the radiologist were not used. Independent double reading was implemented by using a rule to combine the levels of suspicion assigned to findings by two radiologists. Results were evaluated by using localized-response receiver operating characteristic analysis. RESULTS: In a total of 141 cases, there was a visible abnormality at the location of the cancer on the prior mammogram, and 115 of these were classified as mass cases. For prior mammograms that depicted masses, the mean sensitivity of the radiologists, as averaged among the false-positive rates lower than 10%, was 39.4%; this increased by 7.0% with CAD and by 10.5% with double reading. Differences among single, double, and CAD readings were statistically significant (P <.001). CONCLUSION: Although independent double reading yields the best detection performance, the presence and probability of CAD mass markers can improve mammogram interpretation.     

Ductal carcinoma in situ: computer-aided detection in screening mammography

PURPOSE: To retrospectively evaluate the sensitivity of computer-aided detection (CAD) in depicting ductal carcinoma in situ (DCIS) on screening mammograms by using biopsy proved lesion location as the reference standard. MATERIALS AND METHODS: Institutional review board approval was obtained, with a waiver of patient informed consent for this HIPAA-compliant study. Findings of all image-guided biopsies with a pathologic diagnosis of DCIS during a 1-year period were reviewed. Fifty-eight lesions in 55 women (average age, 61.41 years +/- 12.89 [standard deviation]) were available for review. The screening mammogram of the affected breast and, if available, the prior screening mammogram were digitized by the CAD system. An assessment was then made as to whether the CAD system marked the area of DCIS on the current and prior mammograms. Patient age, location and mammographic size of the lesion, type of lesion, and breast density were recorded and were analyzed by using chi2, Fisher exact, or Cochran-Mantel-Haenzel tests, where applicable. RESULTS: CAD identified DCIS in 53 (91%) of 58 lesions on craniocaudal (CC) and mediolateral oblique (MLO) views of screening mammograms obtained in the year of the diagnosis. On screening mammograms obtained prior to the year of the diagnosis (34 patients), no radiologically or CAD-detected lesion was present on 11 (32%) of 34 mammograms. CAD identified DCIS in 16 (70%) of 23 lesions on one of the two views. Seven (30%) of 23 lesions had mammographic findings at retrospective review that were not identified with CAD. CONCLUSION: CAD had a high sensitivity in the depiction of DCIS.     

Effect of soft-copy display supported by CAD on mammography screening performance

Diagnostic performance and reading speed for conventional mammography film reading is compared to reading digitized mammograms on a dedicated workstation. A series of mammograms judged negative at screening and corresponding priors were collected. Half were diagnosed as cancer at the next screening, or earlier for interval cancers. The others were normal. Original films were read by fifteen experienced screening radiologists. The readers annotated potential abnormalities and estimated their likelihood of malignancy. More than 1 year later, five radiologists reread a subset of 271 cases (88 cancer cases having visible signs in retrospect and 183 normals) on a mammography workstation after film digitization. Markers from a computer-aided detection (CAD) system for microcalcifications were available to the readers. Performance was evaluated by comparison of A_z-scores based on ROC and multiple-Reader multiple-case (MRMC) analysis, and localized receiver operating characteristic (LROC) analysis for the 271 cases. Reading speed was also determined. No significant difference in diagnostic performance was observed between conventional and soft-copy reading. Average A_z-scores were 0.83 and 0.84 respectively. Soft-copy reading was only slightly slower than conventional reading. Using a mammography workstation including CAD for detection of microcalcifications, soft-copy reading is possible without loss of quality or efficiency.     

Radiologists' preferences for digital mammographic display. The International Digital Mammography Development Group

PURPOSE: To determine the preferences of radiologists among eight different image processing algorithms applied to digital mammograms obtained for screening and diagnostic imaging tasks. MATERIALS AND METHODS: Twenty-eight images representing histologically proved masses or calcifications were obtained by using three clinically available digital mammographic units. Images were processed and printed on film by using manual intensity windowing, histogram-based intensity windowing, mixture model intensity windowing, peripheral equalization, multiscale image contrast amplification (MUSICA), contrast-limited adaptive histogram equalization, Trex processing, and unsharp masking. Twelve radiologists compared the processed digital images with screen-film mammograms obtained in the same patient for breast cancer screening and breast lesion diagnosis. RESULTS: For the screening task, screen-film mammograms were preferred to all digital presentations, but the acceptability of images processed with Trex and MUSICA algorithms were not significantly different. All printed digital images were preferred to screen-film radiographs in the diagnosis of masses; mammograms processed with unsharp masking were significantly preferred. For the diagnosis of calcifications, no processed digital mammogram was preferred to screen-film mammograms. CONCLUSION: When digital mammograms were preferred to screen-film mammograms, radiologists selected different digital processing algorithms for each of three mammographic reading tasks and for different lesion types. Soft-copy display will eventually allow radiologists to select among these options more easily.     

Can radiographers read screening mammograms?

AIM: To evaluate the ability of radiographers to read screening mammograms in the National Health Service Breast Screening Programme (NHSBSP). MATERIALS AND METHODS: Two radiographers read a test set of 1000 screening mammograms previously reported by a consultant radiologist. Three radiographers then acted as a second reader for 54,000 screening mammograms, their recall results are presented. Four consultant radiologists and three film reading radiographers were timed while reading 2500 mammograms each. RESULTS: When reading the test mammograms the two radiographers recalled all the cancers previously detected by the radiologist at the original screen read. They also recalled 32/90 women who subsequently presented with interval cancers. As a second reader the radiographers had similar recall and cancer detection rates to the radiologists (P>0.05). Double reading detected 9% more cancers. The radiographers take the same length of time to film read as radiologists (P>0.05). CONCLUSION: Radiographers are able to read screening mammograms at least as well as radiologists and do not take longer to do so.     

Computer-aided detection (CAD) in screening mammography: sensitivity of commercial CAD systems for detecting architectural distortion

OBJECTIVE: Computer-aided detection (CAD) algorithms have successfully revealed breast masses and microcalcifications on screening mammography. The purpose of our study was to evaluate the sensitivity of commercially available CAD systems for revealing architectural distortion, the third most common appearance of breast cancer. MATERIALS AND METHODS: Two commercially available CAD systems were used to evaluate screening mammograms obtained in 43 patients with 45 mammographically detected regions of architectural distortion. For each CAD system, we determined the sensitivity for revealing architectural distortion on at least one image of the two-view mammographic examination (case sensitivity) and for each individual mammogram (image sensitivity). Surgical biopsy results were available for each case of architectural distortion. RESULTS: Architectural distortion was deemed present and actionable by a panel of expert breast imagers in 80 views of the 45 cases. One CAD system detected distortion in 22 of 45 cases of distortion (case sensitivity, 49%) and in 30 of 80 mammograms (image sensitivity, 38%); it displayed 0.7 false-positive marks per image. Another CAD system identified distortion in 15 of 45 cases (case sensitivity, 33%) and 17 of 80 mammograms (image sensitivity, 21%); it displayed 1.27 false-positive marks per image. Sensitivity for malignancy-caused distortion was similar to or lower than sensitivity for all causes of distortion. CONCLUSION: Fewer than one half of the cases of architectural distortion were detected by the two most widely available CAD systems used for interpretations of screening mammograms. Considerable improvement in the sensitivity of CAD systems is needed for detecting this type of lesion. Practicing breast imagers who use CAD systems should remain vigilant for architectural distortion.     

The use of batch reading to improve the performance of screening mammography

OBJECTIVE: The objective of our study was to prove that batch reading of screening mammograms can reduce recall rates without sacrificing cancer detection. MATERIALS AND METHODS: We analyzed recall rate, cancer detection, minimal cancer detection, detection of low-stage cancer, and tumor size from consecutive screening mammography examinations from October 2001 to July 2003. The initial 7,984 mammograms were interpreted in the midst of a busy breast imaging practice. Although these studies were not read online, the interpretations were often interrupted for telephone calls, procedures, and diagnostic mammograms. The remaining 1,538 studies were interpreted after the institution of dedicated uninterrupted batch reading. RESULTS: Recall rates were 20.1% before and 16.2% after the introduction of batch reading (p < 0.001). Cancer detection rates were not significantly different: 5.6 cancers were detected per 1,000 examinations without and 7.2 were detected per 1,000 with batch reading. Prognostic factors for breast cancers diagnosed between these groups also were not significantly different. Of the screening-detected cancers diagnosed before batch reading, minimal cancers comprised 67% and low-stage cancers accounted for 76%. Of the cancers diagnosed using batch reading, 73% were minimal and 91% were low stage. The mean size of cancers, 11.7 mm without batch reading and 9.1 mm with batch reading, also showed no statistically significant difference. CONCLUSION: Our experience shows that batch reading can significantly reduce screening mammography recall rates without affecting the cancer detection rate or the proportion of cancers diagnosed with favorable prognostic indicators.     

The visibility of cancer on previous mammograms in retrospective review

AIM: To study how many tumours were visible in restrospect on mammograms originally reported as normal or benign in patients coming to surgery with proven breast cancer. The effect of making the pre--operative mammogram available was also assessed. MATERIALS AND METHODS: Three hundred and twenty initial mammograms of consecutive new breast cancer cases were analysed by a group of radiologists in the knowledge that all patients were later diagnosed with breast cancer. The films were read twice, first without and then with the later (pre-operative) mammograms available. The parenchymal density in the location of the tumour was classified as fatty, mixed or dense, and the tumours were classified as visible or not visible. The reasons for the invisibility of the tumour in the earlier examination were analysed. RESULTS: Fourteen per cent (45) of cancers were retrospectively visible in earlier mammograms without the pre-operative mammograms having been shown, and 29% (95) when pre-operative mammograms were shown. Breast parenchymal density decreased with age and the visibility of tumours increased with age. When considered simultaneously, the effect of age (over 55 vs under 55) was greater (OR = 2.9) than the effect of density (fatty vs others) (OR = 1.5). The most common reasons for non-detection were that the lesion was overlooked (55%), diagnosed as benign (33%) or was visible only in one projection (26%). Growing density was the most common (37%) feature of those lesions originally overlooked or regarded as benign. CONCLUSIONS: Tumours are commonly visible in retrospect, but few of them exhibit specific signs of cancer, and are recognized only if they grow or otherwise change. It is not possible to differentiate most of them from normal parenchymal densities. Saarenmaa, I. (2001). Clinical Radiology56, 40-43.     

Optimal reference mammography: a comparison of mammograms obtained 1 and 2 years before the present examination

OBJECTIVE: We assessed and compared the benefit of using images acquired 1 year or 2 years previously during mammography interpretations. MATERIALS AND METHODS: Eleven radiologists and one resident reviewed 128 cases three times: once without prior mammograms for comparison, once with mammograms from the most recent (1 year) examination, and once with mammograms acquired 2 years previously. They were asked to determine whether the patient should be recalled for additional procedures. Performances under the three conditions were compared. RESULTS: Radiologists were significantly more accurate (p < 0.001) when comparison mammograms (obtained 1 or 2 years previously) were available. Although sensitivity was not significantly affected between the availability of mammograms from 1 or 2 years earlier (p > 0.10), the specificity was. Specificity using mammograms from the latest examination (obtained 1 year previously) as a reference was significantly better (p = 0.03) than specificity using mammograms obtained 2 years previously. CONCLUSION: Comparison mammograms are important for accurate diagnosis-in particular, for increasing specificity. The latest prior examination seems to be the optimal one for this purpose.     

Potential contribution of computer-aided detection to the sensitivity of screening mammography

PURPOSE: To determine the false-negative rate in screening mammography, the capability of computer-aided detection (CAD) to identify these missed lesions, and whether or not CAD increases the radiologists' recall rate. MATERIALS AND METHODS: All available screening mammograms that led to the detection of biopsy-proved cancer (n = 1,083) and the most recent corresponding prior mammograms (n = 427) were collected from 13 facilities. Panels of radiologists evaluated the retrospectively visible prior mammograms by means of blinded review. All mammograms were analyzed by a CAD system that marks features associated with cancer. The recall rates of 14 radiologists were prospectively measured before and after installation of the CAD system. RESULTS: At retrospective review, 67% (286 of 427) of screening mammography-detected breast cancers were visible on the prior mammograms. At independent, blinded review by panels of radiologists, 27% (115 of 427) were interpreted as warranting recall on the basis of a statistical evaluation index; and the CAD system correctly marked 77% (89 of 115) of these cases. The original attending radiologists' sensitivity was 79% (427 of [427 + 115]). There was no statistically significant increase in the radiologists' recall rate when comparing the values before (8.3%) with those after (7.6%) installation of the CAD system. CONCLUSION: The original attending radiologists had a false-negative rate of 21% (115 of [427 + 115]). CAD prompting could have potentially helped reduce this false-negative rate by 77% (89 of 115) without an increase in the recall rate.     

Use of prior mammograms in the classification of benign and malignant masses

The purpose of this study was to determine the importance of using prior mammograms for classification of benign and malignant masses. Five radiologists and one resident classified mass lesions in 198 mammograms obtained from a population-based screening program. Cases were interpreted twice, once without and once with comparison of previous mammograms, in a sequential reading order using soft copy image display. The radiologists' performances in classifying benign and malignant masses without and with previous mammograms were evaluated with receiver operating characteristic (ROC) analysis. The statistical significance of the difference in performances was calculated using analysis of variance. The use of prior mammograms improved the classification performance of all participants in the study. The mean area under the ROC curve of the readers increased from 0.763 to 0.796. This difference in performance was statistically significant (P = 0.008).     

Medical radiologic technologist review: effects on a population-based breast cancer screening program

PURPOSE: To evaluate the effects of medical radiologic technologist review of mammograms in a population-based breast cancer screening program. MATERIALS AND METHODS: A technologist review pilot project was incorporated into the Regina, Saskatchewan, Canada, reading center. Technologists received special training in mammographic interpretation. They reviewed all 27,863 mammograms obtained at the center from July 1995 to September 1996 that were reviewed by a radiologist and selected cases for second blind reading by another radiologist. When the two radiologists' readings were in agreement, the report was sent. When the readings differed, a third opinion was obtained from the program's consulting radiologist. Changes in the number of mammograms interpreted as abnormal and the number of cancers detected were assessed. RESULTS: The technologist review was responsible for the detection of nine cancers missed at the first radiologist's interpretation. Technologists were very discriminating; only 391 cases (1.4%) were sent for double reading. The positive predictive value of screening did not change significantly (7.5% without review, 8.1% with review; P > .20). CONCLUSION: A substantial number of cancers were found with the technologist review. The number of mammograms interpreted as abnormal was reduced slightly. The technologist review proved to be a cost-effective alternative to double reading by two radiologists.