The use of additional imaging increased specificity and decreased sensitivity in screening mammography

Comparison of malignant calcification identification between breast cone-beam computed tomography and digital mammography

BACKGROUND

Calcifications are important abnormal findings in breast imaging and help in the diagnosis of breast cancer.

PURPOSE

To compare breast cone-beam computed tomography (CBCT) with digital mammography (DM) in terms of the ability to identify malignant calcifications.

MATERIAL AND METHODS

In total, 115 paired examinations were performed utilizing breast CBCT and DM; 86 pathology-proven malignant lesions with calcifications detected on DM and 29 randomly selected breasts without calcifications were reviewed by three radiologists. The ability to detect calcifications was assessed on CBCT images. The characterization agreement of two imaging modalities was evaluated by the kappa coefficient. For breast CBCT images, the parameters for the display of calcifications were recorded. The Kruskal-Wallis test was used to compare the preferred slice thickness chosen by each of the three radiologists. The degree of calcification clarity was compared between two modalities using the Mann-Whitney U-test.

RESULTS

The combined sensitivity and specificity of three radiologists in 85 DM-detected calcifications detection on breast CBCT images were 98.43% (251/255) and 98.85% (86/87), respectively. CBCT images showed substantial agreement with mammograms in terms of the characterization of calcifications morphology (k = 0.703; P < 0.05) and distribution (k = 0.629; P < 0.05). CBCT images with a slice thickness of 0.273 mm and three-dimensional maximum-intensity projection (3D-MIP) were more beneficial for calcifications identification. No statistically significant difference was found between standard DM views and CBCT images for three radiologists on calcification display clarity.

CONCLUSION

CBCT images were comparable to mammograms in calcification identification and may be sufficient for malignant calcifications detection and characterization.

Digital zoom of the full-field digital mammogram versus magnification mammography: a systematic review

OBJECTIVES

To summarise and compare the performance of magnification mammography and digital zoom utilising a full-field digital mammography (FFDM) system in the detection and diagnosis of microcalcifications.

METHODS

We ran an extended search in MEDLINE, EMBASE, CINAHL, Engineering Village and Web of Science. Diagnostic test studies, experimental breast phantom studies and a Monte Carlo phantom study were included. A narrative approach was selected to summarise and compare findings regarding the detection of microcalcifications, while a hierarchical model with bivariate analysis was used for the meta-analysis of sensitivity and specificity for diagnosing microcalcifications.

RESULTS

Nine studies were included. Phantom studies suggested that the size of microcalcifications, magnification or zoom factor, exposure factors and detector technology determine whether digital zoom is equivalent to magnification mammography in the detection of microcalcifications. Pooled sensitivity for magnification and zoom calculated from the diagnostic test studies was 0.93 (95% CI 0.84-0.97) and 0.85 (95% CI 0.70-0.94), respectively. Pooled specificity was 0.55 (95% CI 0.51-0.58) and 0.56 (95% CI 0.50-0.62), respectively. The differences between the sensitivities and specificities were not statistically significant.

CONCLUSIONS

Digital zoom may be equivalent to magnification mammography. Diagnostic test studies and phantom studies using newer detector technology would contribute additional knowledge on this topic.

KEY POINTS

• The performance of digital zoom is comparable to magnification for detecting microcalcifications when newer detector technology and optimised imaging procedures are utilised. • The accuracy of digital zoom appears equivalent to geometric magnification in diagnosing microcalcifications.

A Micro CT Study in Patients with Breast Microcalcifications Using a Mathematical Algorithm to Assess 3D Structure

PURPOSE

The aim of this study was to evaluate the relevance of the three-dimensional (3D) structure of breast microcalcifications (MC) as a predictor of malignancy using highly resolved micro-computed tomography (micro-CT) datasets of biopsy samples.

MATERIAL AND METHODS

The study included 28 women with suspicious MC in their mammogram undergoing vacuum-assisted biopsy. Directly after the intervention, the specimens were scanned in a micro-CT with an isometric spatial resolution of 9 μm. Datasets were analysed regarding the number, volume and morphology of suspicious non-monomorphic MC (fl-fine linear, fp-fine pleomorphic, ch-coarse heterogeneous) and the structure model index (SMI). Histological evaluation was performed according to the B-classification: normal tissue or benign (group A: B1, B2), unclear malignant potential or suspicious of malignancy (group B: B3, B4) and malignant lesions (group C: B5).

RESULTS

In all groups, suspicious non-monomorphic MC were found: group A exhibited fp MC in 38.5% of samples, no fl/ch; group B: fl 14.3%, fp 28.6%, ch 14.3%; group C always had at least one type of suspicious non-monomorphic MC (fl (57.1%) or fp (57.1%)) in each sample. The different histologic groups showed a similar mean SMI (benign: 2.97 ± 0.31, malignant: 3.02 ± 0.10, unclear: 2.90 ± 0.28). Between the three groups, no significant differences were found regarding number, volume or SMI value of MC.

CONCLUSION

3D structure based on the SMI of MC analysed with highest spatial resolution is not significantly associated with the B-classification of breast lesions. Thus, magnification views of MC may be omitted in the analysis of MC detected in mammograms.

A comparison between the electronic magnification (EM) and true magnification (TM) of breast phantom images using a CDMAM phantom

PURPOSE

To provide a comparison between the image quality of electronically magnified (EM) and geometric, or true, magnification (TM) mammographic images.

MATERIALS AND METHODS

One Computed Radiography (CR), one Digital Radiography (DR) and two screen-film (S-F) imaging systems were investigated. A Contrast-Detail Mammography (CDMAM) phantom was used as a test object. Three contact images and three sets of TM images with a magnification factor of 1.8 were taken on all systems. Software was used to zoom the contact images by a factor of 1.8 to produce EM images. Two observers evaluated all of the images. An Image Quality Figure and contrast detail curve were used to analyze the observer data and Mann-Whitney U-tests were performed to determine the statistical significance of the results.

RESULTS

No significant differences were found between soft copy and hard copy for any imaging modality. No significant difference in contrast detail detectability (CDD) was seen between EM images from the two digital systems and TM images on S-F systems. The results for the DR EM images and S-F TM images also showed no differences. The CDD of DR TM images was significantly better than both EM and S-F TM images.

CONCLUSION

Digitally zoomed images offer the same level of CDD as S-F TM images, and so may be viably used in their place. DR systems offer greater CDD than conventional S-F images, when comparing the TM images. This implies that doses can be greatly reduced for TM views using DR systems, while maintaining acceptable image quality.

Effect of previous benign breast biopsy on the interpretive performance of subsequent screening mammography

BACKGROUND

Most breast biopsies will be negative for cancer. Benign breast biopsy can cause changes in the breast tissue, but whether such changes affect the interpretive performance of future screening mammography is not known.

METHODS

We prospectively evaluated whether self-reported benign breast biopsy was associated with reduced subsequent screening mammography performance using examination data from the mammography registries of the Breast Cancer Surveillance Consortium from January 2, 1996, through December 31, 2005. A positive interpretation was defined as a recommendation for any additional evaluation. Cancer was defined as any invasive breast cancer or ductal carcinoma in situ diagnosed within 1 year of mammography screening. Measures of mammography performance (sensitivity, specificity, and positive predictive value 1 [PPV1]) were compared both at woman level and breast level in the presence and absence of self-reported benign biopsy history. Referral to biopsy was considered a positive interpretation to calculate positive predictive value 2 (PPV2). Multivariable analysis of a correct interpretation on each performance measure was conducted after adjusting for registry, year of examination, patient characteristics, months since last mammogram, and availability of comparison film. Accuracy of the mammogram interpretation was measured using area under the receiver operating characteristic curve (AUC). All statistical tests were two-sided.

RESULTS

A total of 2,007,381 screening mammograms were identified among 799,613 women, of which 14.6% mammograms were associated with self-reported previous breast biopsy. Multivariable adjusted models for mammography performance showed reduced specificity (odds ratio [OR] = 0.74, 95% confidence interval [CI] = 0.73 to 0.75, P < .001), PPV2 (OR = 0.85, 95% CI = 0.79 to 0.92, P < .001), and AUC (AUC 0.892 vs 0.925, P < .001) among women with self-reported benign biopsy. There was no difference in sensitivity or PPV1 in the same adjusted models, although unadjusted differences in both were found. Specificity was lowest among women with documented fine needle aspiration-the least invasive biopsy technique (OR = 0.58, 95% CI = 0.55 to 0.61, P < .001). Repeating the analysis among women with documented biopsy history, unilateral biopsy history, or restricted to invasive cancers did not change the results.

CONCLUSIONS

Self-reported benign breast biopsy history was associated with statistically significantly reduced mammography performance. The difference in performance was likely because of tissue characteristics rather than the biopsy itself.

Early detection of breast cancer: benefits and risks of supplemental breast ultrasound in asymptomatic women with mammographically dense breast tissue. A systematic review

BACKGROUND

Mammographic screening alone will miss a certain fraction of malignancies, as evidenced by retrospective reviews of mammograms following a subsequent screening. Mammographic breast density is a marker for increased breast cancer risk and is associated with a higher risk of interval breast cancer, i.e. cancer detected between screening tests. The purpose of this review is to estimate risks and benefits of supplemental breast ultrasound in women with negative mammographic screening with dense breast tissue.

METHODS

A systematic search and review of studies involving mammography and breast ultrasound for screening of breast cancer was conducted. The search was performed for the period 1/2000-8/2008 within the data source of PubMed, DARE, and Cochrane databases. Inclusion and exclusion criteria were determined prospectively, and the Oxford evidence classification system for diagnostic studies was used for evidence level. The parameters biopsy rate, positive predictive value (PPV) for biopsy, cancer yield for breast ultrasound alone, and carcinoma detection rate by breast density were extracted or constructed.

RESULTS

The systematic search identified no randomized controlled trials or systematic reviews, six cohort studies of intermediate level of evidence (3b) were found. Only two of the studies included adequate follow-up of subjects with negative or benign findings. Supplemental breast ultrasound after negative mammographic screening permitted diagnosis of primarily invasive carcinomas in 0.32% of women in breast density type categories 2-4 of the American College of Radiology (ACR); mean tumor size for those identified was 9.9 mm, 90% with negative lymph node status. Most detected cancers occurred in mammographically dense breast ACR types 3 and 4. Biopsy rates were in the range 2.3%-4.7%, with PPV of 8.4-13.7% for those biopsied due to positive ultrasound, or about one third of the PPV of biopsies due to mammography.

LIMITATIONS

The study populations included wide age ranges, and the application to women age 50-69 years as proposed for mammographic screening could result in less striking benefit. Further validation studies should employ a uniform assessment system such as BI-RADS and report not only PPV, but also negative predictive value, sensitivity and specificity.

CONCLUSION

Supplemental breast ultrasound in the population of women with mammographically dense breast tissue (ACR 3 and 4) permits detection of small, otherwise occult, breast cancers. Potential adverse impacts for women in this intermediate risk group are associated with an increased biopsy rate.

Tissue Doppler and strain imaging for evaluating tissue elasticity of breast lesions

RATIONALE AND OBJECTIVES

Sonoelastography depicts the intrinsic elastic properties of a tissue which are characterized by the strain applied to achieve tissue deformation and the velocity at which tissue deformation occurs. The present study served to investigate whether the specificity of B-mode ultrasound (US) can be improved by combining B-mode imaging with tissue Doppler imaging (TDI) and offline analysis of tissue strain imaging (TSI).

MATERIALS AND METHODS

Fifty women, 25 with malignant and 25 with benign focal breast lesions, were examined by US with a linear transducer (9 MHz, Aplio, Toshiba, Otawara, Japan). B-mode US views of the lesions were overlaid with color-coded TDI information and area quotients (AQ = area B-mode view/area TDI) were calculated. TSI views were reconstructed offline from the source data. This was done by placing a region of interest (ROI) in the target lesion and color-encoded display of the information. In addition, tissue elasticity was evaluated using a scale of 1-5 corresponding to the BI-RADS categories. Maximum strain (strain factor, SF) was determined in the ROI. All patients also underwent mammography. Sensitivities and specificities were calculated and statistical analysis was performed using Wilcoxon's test.

RESULTS

Sensitivity/specificity was 96%/68% for B-mode US, 100%/40% for combined B-mode US and mammography, and 96%/80% for TSI. The AQ of benign and malignant lesions was significantly different (p = .00008) as was the difference in SF (p = .0004). The readers considered TSI a feasible technique.

CONCLUSION

Evaluation of elasticity based on the quantification of strain factors improves characterization of focal breast lesions, especially the differentiation of BI-RADS 3 and 4 lesions. Surprisingly, significant results in characterizing breast lesions were obtained with the simple technique of TDI, showing a lower tissue displacement in malignant cases.

Real-time sonoelastography performed in addition to B-mode ultrasound and mammography: improved differentiation of breast lesions?

RATIONALE AND OBJECTIVES

The goal of the present study was to compare the sensitivity and specificity of elastography with that of B-mode ultrasound (US) and mammography.

MATERIALS AND METHODS

A total of 300 patients with histologically confirmed breast lesions (168 benign, 132 malignant) were included. Evaluation was by means of the three-dimensional finite-element method. The data are color-coded and superimposed on the B-mode US scan. The images were evaluated by two independent readers. The results were compared with mammography, histology, and the data obtained by previous US investigations. Sensitivities and specificities were calculated.

RESULTS

Sensitivity and specificity in the differentiation of benign and malignant lesions were 87% and 85%, respectively, for mammography and 94% and 83% for B-mode US. The two examiners were in very good agreement in their evaluation of the elastograms (kappa: 0.86). Elastography had a sensitivity of 82% and a specificity of 87%. Elastography was superior to B-mode US in diagnosing Breast Imaging Reporting and Data System (BI-RADS) 3 lesions (92% vs. 82% specificity) and in lipomatous involution (80% vs. 69% specificity).

CONCLUSION

Elastography in breast lesions showed a higher specificity and a lower sensitivity in comparison with B-mode sonography. Elastography may be beneficial in BI-RADS 3 lesions and in lipomatous involution.