Effect of artificial intelligence-based computer-aided diagnosis on the screening outcomes of digital mammography: a matched cohort study

OBJECTIVE

To investigate whether artificial intelligence-based computer-aided diagnosis (AI-CAD) can improve radiologists' performance when used to support radiologists' interpretation of digital mammography (DM) in breast cancer screening.

METHODS

A retrospective database search identified 3158 asymptomatic Korean women who consecutively underwent screening DM between January and December 2019 without AI-CAD support, and screening DM between February and July 2020 with image interpretation aided by AI-CAD in a tertiary referral hospital using single reading. Propensity score matching was used to match the DM with AI-CAD group in a 1:1 ratio with the DM without AI-CAD group according to age, breast density, experience level of the interpreting radiologist, and screening round. Performance measures were compared with the McNemar test and generalized estimating equations.

RESULTS

A total of 1579 women who underwent DM with AI-CAD were matched with 1579 women who underwent DM without AI-CAD. Radiologists showed higher specificity (96% [1500 of 1563] vs 91.6% [1430 of 1561]; p < 0.001) and lower abnormal interpretation rates (AIR) (4.9% [77 of 1579] vs 9.2% [145 of 1579]; p < 0.001) with AI-CAD than without. There was no significant difference in the cancer detection rate (CDR) (AI-CAD vs no AI-CAD, 8.9 vs 8.9 per 1000 examinations; p = 0.999), sensitivity (87.5% vs 77.8%; p = 0.999), and positive predictive value for biopsy (PPV3) (35.0% vs 35.0%; p = 0.999) according to AI-CAD support.

CONCLUSIONS

AI-CAD increases the specificity for radiologists without decreasing sensitivity as a supportive tool in the single reading of DM for breast cancer screening.

CLINICAL RELEVANCE STATEMENT

This study shows that AI-CAD could improve the specificity of radiologists' DM interpretation in the single reading system without decreasing sensitivity, suggesting that it can benefit patients by reducing false positive and recall rates.

KEY POINTS

• In this retrospective-matched cohort study (DM without AI-CAD vs DM with AI-CAD), radiologists showed higher specificity and lower AIR when AI-CAD was used to support decision-making in DM screening. • CDR, sensitivity, and PPV for biopsy did not differ with and without AI-CAD support.

Which Morphological Features of Facet Diastasis Predict Thoracolumbar Posterior Ligamentous Complex Injury as Defined by Magnetic Resonance Imaging?

BACKGROUND

The association of various morphological features of facet diastasis with posterior ligamentous complex (PLC) injury has not been previously described. This study aims to determine the diagnostic value of facet diastasis subtypes for diagnosing thoracolumbar PLC injury.

METHODS

We retrospectively reviewed 337 consecutive patients with acute thoracolumbar fractures who had computed tomography (CT) and magnetic resonance imaging (MRI) within 10 days of injury. Three and 5 reviewers evaluated MRI and CT images, respectively. Facet diastasis was subclassified as follows: Dislocated, no articular surface apposition; subluxed, incomplete articular surface apposition; and facet fracture articular process fractures which may be displaced ≥2 mm or otherwise undisplaced, facet joint widening (FJW) ≥ 3 mm. We examined the diagnostic accuracy and the multivariate associations of facet diastasis subtypes with PLC injury in MRI.

RESULTS

Facet dislocation, subluxation, and displaced facet fracture yielded a high positive predictive value (PPV) for PLC injury (96%, 88%, and 94%, respectively). In contrast, undisplaced facet fracture and FJW yielded a moderate PPV for PLC injury (78%, and 45%, respectively). Facet dislocation, subluxation, and displaced facet fracture showed independent associations with PLC injury (adjusted odds ratio [AOR] = 38.4, 17.1, 13.4, respectively; P < 0.05). Undisplaced facet fracture and FJW were not associated with PLC injury (AOR = 3.9 [95% confidence interval, 0.49-38.4], P = 0.20) and (AOR = 1.94 [95% confidence interval, 0.48-7.13]; P = 0.20; P = 0.33), respectively.

CONCLUSIONS

Facet dislocation, subluxation, and displaced facet fracture, but not undisplaced facet fracture or FJW, were independently associated with PLC injury. Therefore, we propose to define facet diastasis as a surrogate marker of PLC injury in MRI based on these morphologies.

Traumatic low lumbar fractures: How often MRI changes the fracture classification or clinical decision-making compared to CT alone?

PURPOSE

To determine the impact of magnetic resonance imaging (MRI) on fracture classification for low lumbar fractures (LLFs) compared to CT alone.

METHODS

This study was a retrospective review of 41 consecutive patients with LLFs who underwent CT and MRI within 10 days of injury. Three reviewers classified all fractures according to AOSpine Classification and the Thoracolumbar Injury Classification (TLISS). Posterior ligamentous complex (PLC) injury in MRI was defined by black stripe discontinuity and in CT by the presence of: vertebral body translation, facet joint malalignment, horizontal laminar or spinous process fracture, and interspinous widening. The proportion of patients with AO type A/B/C and with TLISS < 5 and ≥ 5 was compared between CT and MRI. We examined the overall accuracy and individual CT findings for PLC injury.

RESULTS

AO classification using CT was: AO type A in 26 patients (61%), type B in 7 patients (17%), and type C in 8 patients (22%). Seventeen patients (41%) had a TLISS ≥ 5 while 24 (59%) had TLISS < 5. The addition of MRI after CT changed the AO classification in only 2 patients (4.9%, 95% CI (0.6-16.5%) due to upgrade of type A to type B or vice versa, but did not change TLISS from < 5 to ≥ 5 [p< 0.0001; 95% CI (0.59, 0.77)].

CONCLUSIONS

CT was highly accurate (95%) for diagnosis of PLC injury in LLFs. Addition of MRI after CT did not change the AO classification or TLISS, compared to CT alone, thus suggesting limited additional value of MRI for PLC assessment or fracture classification.

Diagnostic Value of Various Morphological Features of Horizontal and Vertical Laminar Fractures for Posterior Ligamentous Complex Injury of the Thoracolumbar Spine as Defined by Magnetic Resonance Imaging

OBJECTIVE

To determine diagnostic value of morphological features of horizontal laminar fracture (HLF) and vertical laminar fracture (VLF) for diagnosis of posterior ligamentous complex (PLC) injury.

METHODS

This retrospective review comprised 271 consecutive patients with acute thoracolumbar fractures presenting to a Level 1 trauma center between January 2014 and January 2021. Two reviewers evaluated computed tomography and magnetic resonance imaging. VLFs were subclassified based on length and depth of lamina involved, as follows: type 1, full-length complete; type 2, full-length incomplete; type 3, partial-length complete or incomplete. HLFs were subclassified as follows: bilateral versus unilateral, displaced >2 mm versus nondisplaced, and lamina-only versus laminar and pedicle. We examined the diagnostic accuracy and the univariate and multivariate associations of laminar fracture subtypes with PLC injury as defined by black stripe discontinuity.

RESULTS

Bilateral HLFs, laminar and pedicle fractures, displaced HLFs, and type 1 VLFs yielded a high positive predictive value for PLC injury (95%, 91%, 100%, and 86%, respectively). Type 2 and 3 VLFs did not show significant univariate associations with PLC injury. Bilateral HLFs, laminar and pedicle fractures, and displaced HLFs showed independent associations with PLC injury (adjusted odds ratio = 13.6, 8.4, 6, and 10.3, respectively; P < 0.002). Type 1 VLFs did not show a significant association with PLC (adjusted odds ratio = 10.3; P = 0.06).

CONCLUSIONS

Bilateral HLFs, laminar and pedicle fractures, and displaced HLFs, but not any VLF subtypes, were independently associated with PLC injury. These findings may improve the reliability of PLC assessment by computed tomography.

Analysis of the Combined Computed Tomography Findings Improves the Accuracy of Computed Tomography for Detecting Posterior Ligamentous Complex Injury of the Thoracolumbar Spine as Defined by Magnetic Resonance Imaging

OBJECTIVE

To determine the diagnostic accuracy of combined computed tomography (CT) findings for detecting posterior ligamentous complex (PLC) injury in thoracolumbar fractures using magnetic resonance imaging as a reference.

METHODS

A retrospective review of 263 consecutive patients with thoracolumbar fractures who underwent CT and magnetic resonance imaging within 10 days of injury. Two reviewers evaluated CT for the following findings: facet joint malalignment, facet joint widening, horizontal laminar fracture, spinous process fracture, and interspinous widening. We examined the independent association of CT findings with PLC injury before combining the CT findings to calculate the diagnostic accuracy: sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), and positive and negative likelihood ratios. PLC injury was defined by black stripe discontinuity caused by supraspinous or ligamentum flavum rupture.

RESULTS

Facet joint malalignment, spinous process fracture, horizontal laminar fracture, and interspinous widening were independently associated with PLC injury (adjusted odds ratio range, 4.4e17.4). A single positive CT finding yielded a PPV of 31% and NPV of 66% for PLC injury. Two or more CT findings yielded a PPV of 91% for PLC injury. A negative CT for all the 4 CT sings had a 94% NPV for PLC injury.

CONCLUSIONS

Two or more CT findings provided the best combination to confirm PLC injury; thus, this combination could be used as a criterion for injured PLC. A single CT finding lacks sufficient predictive value to confirm or rule out PLC injury. A negative CT for the 4 CT findings provided the highest sensitivity for PLC injuries.

Consensus Review of Discordant Imaging Findings after the Introduction of Digital Screening Mammography: Irish National Breast Cancer Screening Program Experience

Background When there are discordant results between individual readers interpreting screening mammograms, consensus by independent readers may reduce unnecessary recalls for further work-up. Few studies have looked at consensus outcomes following the introduction of full-field digital mammography (FFDM). Purpose To determine outcomes of women discussed at consensus meetings during a 5-year period after introduction of FFDM, including recall rates, cancer detection, and interval cancers. Materials and Methods In this retrospective study from January 2010 to December 2014, the authors reviewed all screening mammograms from a single unit of a biennial Irish national breast screening program after the introduction of FFDM. Screening mammograms were double reported. Abnormalities detected at discordant screening mammography readings were discussed at biweekly consensus meetings. Outcomes of consensus meetings were reviewed in terms of referral for assessment, biopsy rates, cancer detection, and outcomes from later rounds of screening. Statistical analysis was performed by using a χ² test to compare recall rate and cancer detection rates between FFDM and screen-film mammography based on a previously published study from the authors' institution. Results A total of 2565 women (age range, 50-64 years) with discordant mammographic findings were discussed at consensus meetings. Of these 2565 women, 1037 (40%) were referred for further assessment; 108 cancers were detected in these women. Of the 1285 women who returned to biennial screening, malignancy was detected at the site of original concern in 12 women at a further round of screening. Three true interval cancers were identified. Sensitivity (88.5% [108 of 122]; 95% confidence interval [CI]: 81.5%, 93.6%) and negative predictive value (99.1% [1528 of 1542]; 95% CI: 98.5%, 99.4%) of consensus review remained stable after the introduction of FFDM. Specificity of consensus review increased from 57.6% (729 of 1264; 95% CI: 54.9%, 60.4%) to 62.2% (1528 of 2457; 95% CI: 60.2%, 64.1%) (P = .008). Conclusion Consensus review of discordant mammographic screening-detected abnormalities remains a valuable tool after introduction of full-field digital mammography as it reduces recall for assessment and demonstrates persistently high sensitivity and negative predictive values. © RSNA, 2020 See also the editorial by Hofvind and Lee in this issue.

Prevalence and clinical significance of discordant LI-RADS® observations on multiphase contrast-enhanced MRI in patients with cirrhosis

PURPOSE

To determine the prevalence and clinical significance of discordant LI-RADS^® (Liver Imaging Reporting and Data System) liver observations on multiphase contrast-enhanced (MCE) magnetic resonance imaging (MRI) in patients with cirrhosis.

METHODS

This cross-sectional study included 93 cirrhosis patients who underwent 1.5 or 3 T MCE MRI for evaluation of hepatocellular carcinoma (HCC). Two abdominal radiologists independently reviewed T1-, T2-, diffusion-weighted unenhanced images as well as MCE T1-weighted fat-suppressed images and reported liver observations using LI-RADS^®. Concordance were recorded for detection (co-detected by both radiologists or not), size category (< 10; 10-19; ≥ 20 mm), and LI-RADS^® category assignment as reportable (LR-3/4/5/M) and actionable (LR-4/5/M). The overall concordance (i.e., concordant in detection, size, and LR-category) was calculated with 95% confidence interval [CI], and separately for detection, size, and LR-category. Clinical significance of discordance was assessed as impact on follow-up imaging, referral for biopsy, liver transplant eligibility, or treatment modality.

RESULTS

Reportable and actionable observations were overall concordant between two radiologists only in 32.3% [24.6, 41.0] and 40.1% [29.5, 51.5] of cases, respectively. Poor overall concordance was related to detection concordance of 52.0% [44.3, 59.5] and 62.5% [52.3, 71.8], as well as LR-category concordance of 73.7% [61.6, 83.1] and 70.9% [57.3, 81.6], for reportable and actionable observations, respectively. Discordant LI-RADS^® observations would have impacted clinical management in 30 subjects (43.5%), most (66.7%) of whom were due to discordant detection.

CONCLUSION

Discordant MRI LI-RADS^® observations are common in patients with cirrhosis and may have potential implications for patient management.

Is the false-positive rate in mammography in North America too high?

The practice of investigating pathological abnormalities in the breasts of females who are asymptomatic is primarily employed using X-ray mammography. The importance of breast screening is reflected in the mortality-based benefits observed among females who are found to possess invasive breast carcinoma prior to the manifestation of clinical symptoms. It is estimated that population-based screening constitutes a 17% reduction in the breast cancer mortality rate among females affected by invasive breast carcinoma. In spite of the significant utility that screening confers in those affected by invasive cancer, limitations associated with screening manifest as potential harms affecting individuals who are free of invasive disease. Disease-free and benign tumour-bearing individuals who are subjected to diagnostic work-up following a screening examination constitute a population of cases referred to as false positives (FPs). This article discusses factors contributing to the FP rate in mammography and extends the discussion to an assessment of the consequences associated with FP reporting. We conclude that the mammography FP rate in North America is in excess based upon the observation of overtreatment of in situ lesions and the disproportionate distribution of detriment and benefit among the population of individuals recalled for diagnostic work-up subsequent to screening. To address the excessive incidence of FPs in mammography, we investigate solutions that may be employed to remediate the current status of the FP rate. Subsequently, it can be suggested that improvements in the breast-screening protocol, medical litigation risk, image interpretation software and the implementation of image acquisition modalities that overcome superimposition effects are promising solutions.

Double versus single reading of mammograms in a breast cancer screening programme: a cost-consequence analysis

OBJECTIVES

To assess the costs and health-related outcomes of double versus single reading of digital mammograms in a breast cancer screening programme.

METHODS

Based on data from 57,157 digital screening mammograms from women aged 50-69 years, we compared costs, false-positive results, positive predictive value and cancer detection rate using four reading strategies: double reading with and without consensus and arbitration, and single reading with first reader only and second reader only. Four highly trained radiologists read the mammograms.

RESULTS

Double reading with consensus and arbitration was 15 % (Euro 334,341) more expensive than single reading with first reader only. False-positive results were more frequent at double reading with consensus and arbitration than at single reading with first reader only (4.5 % and 4.2 %, respectively; p < 0.001). The positive predictive value (9.3 % and 9.1 %; p = 0.812) and cancer detection rate were similar for both reading strategies (4.6 and 4.2 per 1000 screens; p = 0.283).

CONCLUSIONS

Our results suggest that changing to single reading of mammograms could produce savings in breast cancer screening. Single reading could reduce the frequency of false-positive results without changing the cancer detection rate. These results are not conclusive and cannot be generalized to other contexts with less trained radiologists.

KEY POINTS

• Double reading of digital mammograms is more expensive than single reading. • Compared to single reading, double reading yields a higher proportion of false-positive results. • The cancer detection rate was similar for double and single readings. • Single reading may be a cost-effective strategy in breast cancer screening programmes.

Collective intelligence meets medical decision-making: the collective outperforms the best radiologist

While collective intelligence (CI) is a powerful approach to increase decision accuracy, few attempts have been made to unlock its potential in medical decision-making. Here we investigated the performance of three well-known collective intelligence rules (“majority”, “quorum”, and “weighted quorum”) when applied to mammography screening. For any particular mammogram, these rules aggregate the independent assessments of multiple radiologists into a single decision (recall the patient for additional workup or not). We found that, compared to single radiologists, any of these CI-rules both increases true positives (i.e., recalls of patients with cancer) and decreases false positives (i.e., recalls of patients without cancer), thereby overcoming one of the fundamental limitations to decision accuracy that individual radiologists face. Importantly, we find that all CI-rules systematically outperform even the best-performing individual radiologist in the respective group. Our findings demonstrate that CI can be employed to improve mammography screening; similarly, CI may have the potential to improve medical decision-making in a much wider range of contexts, including many areas of diagnostic imaging and, more generally, diagnostic decisions that are based on the subjective interpretation of evidence.

Impact of full field digital mammography on the classification and mammographic characteristics of interval breast cancers

OBJECTIVE

Full field digital mammography (FFDM) is increasingly replacing screen film mammography (SFM) in breast screening programs. Interval breast cancers are an issue in all screening programs and the purpose of our study is to assess the impact of FFDM on the classification of interval breast cancers at independent blind review and to compare the mammographic features of interval cancers at FFDM and SFM.

MATERIALS AND METHODS

This study included 138 cases of interval breast cancer, 76 following an FFDM screening examination and 62 following screening with SFM. The prior screening mammogram was assessed by each of five consultant breast radiologists who were blinded to the site of subsequent cancer. Subsequent review of the diagnostic mammogram was performed and cases were classified as missed, minimal signs, occult or true interval. Mammographic features of the interval cancer at diagnosis and any abnormality identified on the prior screening mammogram were recorded.

RESULTS

The percentages of cancers classified as missed at FFDM and SFM did not differ significantly, 10.5% (8 of 76) at FFDM and 8.1% (5 of 62) at SFM (p=.77). There were significantly less interval cancers presenting as microcalcifications (alone or in association with another abnormality) following screening with FFDM, 16% (12 of 76) than following a SFM examination, 32% (20 of 62) (p=.02).

CONCLUSION

Interval breast cancers continue to pose a problem at FFDM. The switch to FFDM has changed the mammographic presentation of interval breast cancer, with less interval cancers presenting in association with microcalcifications.

Establishing a gold standard for test sets: variation in interpretive agreement of expert mammographers

RATIONALE AND OBJECTIVES

Test sets for assessing and improving radiologic image interpretation have been used for decades and typically evaluate performance relative to gold standard interpretations by experts. To assess test sets for screening mammography, a gold standard for whether a woman should be recalled for additional workup is needed, given that interval cancers may be occult on mammography and some findings ultimately determined to be benign require additional imaging to determine if biopsy is warranted. Using experts to set a gold standard assumes little variation occurs in their interpretations, but this has not been explicitly studied in mammography.

MATERIALS AND METHODS

Using digitized films from 314 screening mammography exams (n = 143 cancer cases) performed in the Breast Cancer Surveillance Consortium, we evaluated interpretive agreement among three expert radiologists who independently assessed whether each examination should be recalled, and the lesion location, finding type (mass, calcification, asymmetric density, or architectural distortion), and interpretive difficulty in the recalled images.

RESULTS

Agreement among the three expert pairs for recall/no recall was higher for cancer cases (mean 74.3 ± 6.5) than for noncancers (mean 62.6 ± 7.1). Complete agreement on recall, lesion location, finding type and difficulty ranged from 36.4% to 42.0% for cancer cases and from 43.9% to 65.6% for noncancer cases. Two of three experts agreed on recall and lesion location for 95.1% of cancer cases and 91.8% of noncancer cases, but all three experts agreed on only 55.2% of cancer cases and 42.1% of noncancer cases.

CONCLUSION

Variability in expert interpretive is notable. A minimum of three independent experts combined with a consensus should be used for establishing any gold standard interpretation for test sets, especially for noncancer cases.

Magnetic resonance imaging frequently changes classification of acute traumatic thoracolumbar spine injuries

OBJECTIVE

To evaluate the influence of additional (MRI) compared with computed tomography (CT) alone for the classification of traumatic spinal injuries using the Arbeitsgemeinshaft für Osteosynthesefragen (AO) system and the Thoraco-Lumbar Injury Classification and Severity (TLICS) scale.

MATERIALS AND METHODS

Images from 100 consecutive patients with at least one fracture on CT were evaluated retrospectively by three radiologists with regard to the AO and TLICS classification systems in 2 steps. First, all images from the initial CT examination were analyzed. Second, 6 weeks later, CT and MR images were analyzed together. Descriptive statistics and Wilcoxon tests were performed to identify changes in the number of fractures and ligamentous lesions detected and their corresponding classification.

RESULTS

CT and MRI together revealed a total of 196 fractures (CT alone 162 fractures). The AO classification changed in 31 %, the TLICS classification changed in 33 % of the patients compared with CT alone. Based on CT and MRI together, the TLICS value changed from values <5 (indication for conservative therapy) to values ≥ 5 (indication for surgical therapy) in 24 %.

CONCLUSION

MRI of patients with thoracolumbar spinal trauma considerably improved the detection of fractures and soft tissue injuries compared with CT alone and significantly changed the overall trauma classification.

Prospective trial comparing full-field digital mammography (FFDM) versus combined FFDM and tomosynthesis in a population-based screening programme using independent double reading with arbitration

OBJECTIVES

To compare double readings when interpreting full field digital mammography (2D) and tomosynthesis (3D) during mammographic screening.

METHODS

A prospective, Ethical Committee approved screening study is underway. During the first year 12,621 consenting women underwent both 2D and 3D imaging. Each examination was independently interpreted by four radiologists under four reading modes: Arm A-2D; Arm B-2D + CAD; Arm C-2D + 3D; Arm D-synthesised 2D + 3D. Examinations with a positive score by at least one reader were discussed at an arbitration meeting before a final management decision. Paired double reading of 2D (Arm A + B) and 2D + 3D (Arm C + D) were analysed. Performance measures were compared using generalised linear mixed models, accounting for inter-reader performance heterogeneity (P < 0.05).

RESULTS

Pre-arbitration false-positive scores were 10.3 % (1,286/12,501) and 8.5 % (1,057/12,501) for 2D and 2D + 3D, respectively (P < 0.001). Recall rates were 2.9 % (365/12,621) and 3.7 % (463/12,621), respectively (P = 0.005). Cancer detection was 7.1 (90/12,621) and 9.4 (119/12,621) per 1,000 examinations, respectively (30 % increase, P < 0.001); positive predictive values (detected cancer patients per 100 recalls) were 24.7 % and 25.5 %, respectively (P = 0.97). Using 2D + 3D, double-reading radiologists detected 27 additional invasive cancers (P < 0.001).

CONCLUSION

Double reading of 2D + 3D significantly improves the cancer detection rate in mammography screening.

KEY POINTS

• Tomosynthesis-based screening was successfully implemented in a large prospective screening trial. • Double reading of tomosynthesis-based examinations significantly reduced false-positive interpretations. • Double reading of tomosynthesis significantly increased the detection of invasive cancers.

Cumulative risk of cancer detection in breast cancer screening by protocol strategy

BACKGROUND

There is little information on the individual risk of screen-detected cancer in women over successive participations. This study aimed to estimate the 10-year cumulative breast cancer detection risk (ductal carcinoma in situ and invasive carcinoma) in a population-based breast cancer screening program according to distinct protocol strategies. A further aim was to determine which strategies maximized the cancer detection risk and how this risk was affected by the radiologic protocol variables.

METHODS

Data were drawn from a retrospective cohort of women from nine population-based screening programs in Spain from 1990 to 2006. We used logistic regression with discrete intervals to estimate the cumulative detection risk at 10 years of follow-up according to radiologic variables and protocol strategies.

RESULTS

In women starting screening at the age of 45-59 years, the cumulative risk of screen-detected cancer at 10 years ranged from 11.11 to 16.71 per 1,000 participants according to the protocol strategy. The cumulative detection risk for overall cancer and invasive cancer was the highest with strategies using digital mammography, double reading, and two projections (16.71 and 12.07 ‰, respectively). For ductal carcinoma in situ, cumulative detection risk was the highest with strategies using screen-film, double reading, and two projections (2.32 ‰). The risk was the lowest with strategies using screen-film mammography, single reading, and two projections.

CONCLUSIONS

This study found that at least eleven cancers are detected per 1,000 women screened in the first 10 years of follow-up. Enhanced knowledge of the variability in cumulative risk of screen-detected cancer could improve protocol strategies.

Comparison of the clinical performance of three digital mammography systems in a breast cancer screening programme

This study compares the clinical performance of three digital mammography system types in a breast cancer screening programme. 28 digital mammography systems from three different vendors were included in the study. The retrospective analysis included 238 182 screening examinations of females aged between 50 and 64 years over a 3-year period. All images were double read and assigned a result according to a 5-point rating scale to indicate the probability of cancer. Females with a positive result were recalled for further assessment imaging and biopsy if necessary. Clinical performance in terms of cancer detection rate was analysed and the results presented. No statistically significant difference was found between the three different mammography systems in a population-based screening programme, in terms of the overall cancer detection rate or in the detection of invasive cancer and ductal carcinoma in situ. This was shown in both prevalent and subsequent screening examination categories. The results demonstrate comparable cancer detection performance for the three imaging system types operational in the screening programme.

Mammography screening using independent double reading with consensus: is there a potential benefit for computer-aided detection?

BACKGROUND

Double reading improves the cancer detection rate in mammography screening. Single reading with computer-aided detection (CAD) has been considered to be an alternative to double reading. Little is known about the potential benefit of CAD in breast cancer screening with double reading.

PURPOSE

To compare prospective independent double reading of screen-film (SFM) and full-field digital (FFDM) mammography in population-based screening with retrospective standalone CAD performance on the baseline mammograms of the screen-detected cancers and subsequent cancers diagnosed during the follow-up period.

MATERIAL AND METHODS

The study had ethics committee approval. A 5-point rating scale for probability of cancer was used for 23,923 (SFM = 16,983; FFDM = 6940) screening mammograms. Of 208 evaluable cancers, 104 were screen-detected and 104 were subsequent (44 interval and 60 next screening round) cancers. Baseline mammograms of subsequent cancers were retrospectively classified in consensus without information about cancer location, histology, or CAD prompting as normal, non-specific minimal signs, significant minimal signs, and false-negatives. The baseline mammograms of the screen-detected cancers and subsequent cancers were evaluated by CAD. Significant minimal signs and false-negatives were considered 'actionable' and potentially diagnosable if correctly prompted by CAD.

RESULTS

CAD correctly marked 94% (98/104) of the baseline mammograms of the screen-detected cancers (SFM = 95% [61/64]; FFDM = 93% [37/40]), including 96% (23/24) of those with discordant interpretations. Considering only those baseline examinations of subsequent cancers prospectively interpreted as normal and retrospectively categorized as 'actionable', CAD input at baseline screening had the potential to increase the cancer detection rate from 0.43% to 0.51% (P = 0.13); and to increase cancer detection by 16% ([104 + 17]/104) and decrease interval cancers by 20% (from 44 to 35).

CONCLUSION

CAD may have the potential to increase cancer detection by up to 16%, and to reduce the number of interval cancers by up to 20% in SFM and FFDM screening programs using independent double reading with consensus review. The influence of true- and false-positive CAD marks on decision-making can, however, only be evaluated in a prospective clinical study.

Effect of protocol-related variables and women's characteristics on the cumulative false-positive risk in breast cancer screening

BACKGROUND

Reducing the false-positive risk in breast cancer screening is important. We examined how the screening-protocol and women's characteristics affect the cumulative false-positive risk.

METHODS

This is a retrospective cohort study of 1,565,364 women aged 45-69 years who underwent 4,739,498 screening mammograms from 1990 to 2006. Multilevel discrete hazard models were used to estimate the cumulative false-positive risk over 10 sequential mammograms under different risk scenarios.

RESULTS

The factors affecting the false-positive risk for any procedure and for invasive procedures were double mammogram reading [odds ratio (OR)=2.06 and 4.44, respectively], two mammographic views (OR=0.77 and 1.56, respectively), digital mammography (OR=0.83 for invasive procedures), premenopausal status (OR=1.31 and 1.22, respectively), use of hormone replacement therapy (OR=1.03 and 0.84, respectively), previous invasive procedures (OR=1.52 and 2.00, respectively), and a familial history of breast cancer (OR=1.18 and 1.21, respectively). The cumulative false-positive risk for women who started screening at age 50-51 was 20.39% [95% confidence interval (CI) 20.02-20.76], ranging from 51.43% to 7.47% in the highest and lowest risk profiles, respectively. The cumulative risk for invasive procedures was 1.76% (95% CI 1.66-1.87), ranging from 12.02% to 1.58%.

CONCLUSIONS

The cumulative false-positive risk varied widely depending on the factors studied. These findings are relevant to provide women with accurate information and to improve the effectiveness of screening programs.

No benefit for consensus double reading at baseline screening for lung cancer with the use of semiautomated volumetry software

PURPOSE

To retrospectively evaluate the performance of consensus double reading compared with single reading at baseline screening of a lung cancer computed tomography (CT) screening trial.

MATERIALS AND METHODS

The study was approved by the Dutch Minister of Health and ethical committees. Written informed consent was obtained from all participants. The benefit of consensus double reading was expressed by the percentage change in cancer detection rate, recall rate, number of additional nodules detected, and change in sensitivity and specificity in 7557 participants. The reference standard was a retrospective analysis of the serial CT scans performed in participants diagnosed with lung cancer during a 2-year period after baseline. Semiautomated volumetric software was used for nodule evaluation. McNemar tests were performed to test statistical significance. In addition, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated and 95% confidence intervals (CIs) constructed.

RESULTS

Seventy-four cases of lung cancer were qualified as detectable at baseline. Compared with single reading, consensus double reading did not increase the cancer detection rate (2.7%; 95% CI: -1.0%, 6.4%; P = .50) or change the recall rate (20.6% vs 20.8%, P = .28), but led to the detection of 19.0% (1635 of 8623; 95% CI: 18.0%, 19.9%, P < .01) more nodules. The sensitivity, specificity, PPV, and NPV were 95.9% (71 of 74), 80.2% (6001 of 7483), 4.6% (71 of 1553) and 99.9% (6001 of 6004) for single reading and 98.6% (73 of 74), 80.0% (1497 of 7483), 4.6% (73 of 1570), and 99.9% (5986 of 5987) for consensus double reading, respectively.

CONCLUSION

There is no statistically significant benefit for consensus double reading at baseline screening for lung cancer with the use of a nodule management strategy based solely on semiautomated volumetry.

Improving the accuracy of CTC interpretation: computer-aided detection

Computer-aided polyp detection aims to improve the accuracy of the colonography interpretation. The computer searches the colonic wall to look for polyplike protrusions and presents a list of suspicious areas to a physician for further analysis. Computer-aided polyp detection has developed rapidly in the past decade in the laboratory setting and has sensitivities comparable with those of experts. Computer-aided polyp detection tends to help inexperienced readers more than experienced ones and may also lead to small reductions in specificity. In its currently proposed use as an adjunct to standard image interpretation, computer-aided polyp detection serves as a spellchecker rather than an efficiency enhancer.

Screening-detected breast cancers: discordant independent double reading in a population-based screening program

PURPOSE

To analyze discordant and concordant screening-detected breast cancers in a nationwide population-based screening program by using independent double reading with consensus.

MATERIALS AND METHODS

The study is a part of the evaluation of the Norwegian Breast Cancer Screening Program and is covered by the Cancer Registry regulation. Analyses were based on prospective initial interpretation scores of 1 033 870 screenings that included 5611 breast cancers. A five-point scale for probability of cancer was used in the initial interpretation. Screening mammograms with a score of 2 or higher by either radiologist were discussed at consensus meetings where the decision whether to recall was made. A score of 1 by one reader and 2 or higher by the other was defined as a discordant interpretation and discordant cancer, whereas a score of 2 or higher by both readers was defined as a concordant recall and cancer.

RESULTS

Discordant interpretation was present in 5.3% (54 447 of 1 033 870) of the screenings, whereas 2.1% (21 928 of 1 033 870) were concordant positive interpretations. Of the screening-detected cancers, 23.6% (1326 of 5611) were diagnosed in women who were recalled because of screenings with discordant interpretation. One hundred seventeen interval breast cancers were diagnosed among the 40 312 screenings that were dismissed at consensus; these were 6.5% of all interval cancers. A significantly higher proportion of microcalcifications alone was present in discordant cancers (24.9% [304 of 1219]) compared with concordant cancers (17.7% [704 of 3972]) (P < .001).

CONCLUSION

Independent double reading with consensus at mammography screening has the potential to increase the cancer detection rate compared with single reading. Mammograms with microcalcifications alone are significantly more common among discordant cancers.