| 1. |
- Fieselmann, Andreas, et al.
(författare)
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Volumetric breast density measurement for personalized screening : Accuracy, reproducibility, and agreement with visual assessment
- 2018
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Ingår i: 14th International Workshop on Breast Imaging (IWBI 2018). - : SPIE. - 9781510620070 ; 10718
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Konferensbidrag (refereegranskat)abstract
- Assessment of breast density at the point of mammographic examination could lead to optimized breast cancer screening pathways. The onsite breast density information may offer guidance when to recommend supplemental imaging for women in a screening program. In this work, performance evaluation of a new software (Insight BD, Siemens Healthcare GmbH) for fast onsite quantification of volumetric breast density is presented. Accuracy of volumetric measurement is evaluated using breast tissue equivalent phantom experiments. Reproducibility of measurement results is analyzed using 8150 4-view mammography exams. Furthermore, agreement between breast density categories computed by the software with those determined visually by radiologists is examined. The results of the performance evaluation demonstrate that the software delivers accurate and reproducible measurements that agree well with the visual assessment of breast density by radiologists.
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| 2. |
- Fieselmann, Andreas, et al.
(författare)
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Volumetric breast density measurement for personalized screening : Accuracy, reproducibility, consistency, and agreement with visual assessment
- 2019
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Ingår i: Journal of Medical Imaging. - 2329-4302. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- Assessment of breast density at the point of mammographic examination could lead to optimized breast cancer screening pathways. The onsite breast density information may offer guidance of when to recommend supplemental imaging for women in a screening program. A software application (Insight BD, Siemens Healthcare GmbH) for fast onsite quantification of volumetric breast density is evaluated. The accuracy of the method is assessed using breast tissue equivalent phantom experiments resulting in a mean absolute error of 3.84%. Reproducibility of measurement results is analyzed using 8427 exams in total, comparing for each exam (if available) the densities determined from left and right views, from cranio-caudal and medio-lateral oblique views, from full-field digital mammograms (FFDM) and digital breast tomosynthesis (DBT) data and from two subsequent exams of the same breast. Pearson correlation coefficients of 0.937, 0.926, 0.950, and 0.995 are obtained. Consistency of the results is demonstrated by evaluating the dependency of the breast density on women's age. Furthermore, the agreement between breast density categories computed by the software with those determined visually by 32 radiologists is shown by an overall percentage agreement of 69.5% for FFDM and by 64.6% for DBT data. These results demonstrate that the software delivers accurate, reproducible, and consistent measurements that agree well with the visual assessment of breast density by radiologists.
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| 3. |
- Förnvik, Daniel, et al.
(författare)
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Comparison between software volumetric breast density estimates in breast tomosynthesis and digital mammography images in a large public screening cohort
- 2019
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 29:1, s. 330-336
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To compare software estimates of volumetric breast density (VBD) based on breast tomosynthesis (BT) projections to those based on digital mammography (DM) images in a large screening cohort, the Malmö Breast Tomosynthesis Screening Trial (MBTST). Methods: DM and BT images of 9909 women (enrolled 2010–2015) were retrospectively analysed with prototype software to estimate VBD. Software calculation is based on a physics model of the image acquisition process and incorporates the effect of masking in DM based on accumulated dense tissue areas. VBD (continuously and categorically) was compared between BT [central projection (mediolateral oblique view (MLO)] and two-view DM, and with radiologists’ BI-RADS density 4th ed. scores. Agreement and correlation were investigated with weighted kappa (κ), Spearman’s correlation coefficient (r), and Bland–Altman analysis. Results: There was a high correlation (r = 0.83) between VBD in DM and BT and substantial agreement between the software breast density categories [observed agreement, 61.3% and 84.8%; κ = 0.61 and ĸ = 0.69 for four (a/b/c/d) and two (fat involuted vs. dense) density categories, respectively]. There was moderate agreement between radiologists’ BI-RADS scores and software density categories in DM (ĸ = 0.55) and BT (ĸ = 0.47). Conclusions: In a large public screening setting, we report a substantial agreement between VBD in DM and BT using software with special focus on masking effect. This automated and objective mode of measuring VBD may be of value to radiologists and women when BT is used as the primary breast cancer screening modality. Key Points: • There was a high correlation between continuous volumetric breast density in DM and BT.• There was substantial agreement between software breast density categories (four groups) in DM and BT; with clinically warranted binary software breast density categories, the agreement increased markedly.• There was moderate agreement between radiologists’ BI-RADS scores and software breast density categories in DM and BT.
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| 4. |
- Förnvik, Hannie, et al.
(författare)
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Towards determination of individual glandular dose
- 2018
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Ingår i: Medical Imaging 2018 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 9781510616356 ; 10573
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Konferensbidrag (refereegranskat)abstract
- Due to variations in amount and distribution of glandular breast tissue among women, the mean glandular dose (MGD) can be a poor measure of the individual glandular dose. Therefore, to improve the basis for risk assessment related to radiation dose from breast X-ray examinations, the distribution should be considered. Breast tomosynthesis (BT) is an imaging technique that may be used as an alternative or complement to standard mammography in breast cancer screening, and it could provide the required 3D-localisation of glandular tissue for estimation of the individual glandular dose. In this study, we investigated the possibility to localize glandular tissue from BT data and use a Monte Carlo simulation routine to estimate the glandular dose for software breast phantoms with different amount and distribution of glandular breast tissue. As an initial evaluation of the method, the local energy absorption in glandular tissue was estimated for seven breast phantoms and the corresponding phantoms recreated from reconstructed BT data. As expected, the normalized glandular dose was found to differ substantially with glandular distribution. This emphasizes the importance of glandular tissue localization for estimation of the individual glandular dose. The results showed good accuracy for estimation of normalized glandular dose using breast phantoms recreated from reconstructed BT image volumes (relative differences between -7.3% and +9.5%). Following this initial study, the method will be evaluated for more phantoms and potentially developed for patient cases. In the future it could become a useful tool in breast dosimetry as a step towards the individual glandular dose.
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| 5. |
- Sartor, Hanna, et al.
(författare)
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Changes in breast density over serial mammograms : A case-control study
- 2020
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Ingår i: European Journal of Radiology. - : Elsevier BV. - 0720-048X. ; 127
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: In addition to a breast density category, temporal changes in breast density have gained attention as a dynamic breast cancer risk marker. This case-control study aimed to investigate a potential change in breast density preceding tumor development and the relationship of this potential change to prognostic pathological tumor variables. Method: A total of 51 consecutive, eligible-for-analyses, biopsy-proven breast cancers were diagnosed between 1 st of August and 31 st of December 2014 at Skåne University Hospital, Sweden. Mammogram data and patient- and tumor characteristics were retrieved retrospectively from medical charts. Breast density was quantitatively estimated using LIBRA (a free open source software package). The cases were matched for year of birth, number of screening rounds, and date for first and last mammograms with controls from the Malmö Breast Tomosynthesis Screening Trial in a 1:2 ratio, resulting in median time between mammograms of 4.5 (1.3–11.9) years for cases and 4.7 (1.4–11.1) years for controls, averaging approximately three screening rounds (1–6 rounds). Results: We detected a statistically significant difference in breast density change over time, with cases showing an increase in breast density (1.7 %) as compared to controls (-0.3 %) (p = 0.045). We found that in women with breast cancer, older women (≥ 55 years) experienced a higher breast density increase compared to younger women (5.1 % vs. 0.3 %, p = 0.002). Conclusions: There was a statistically significant difference in density change, where women with breast cancer showed an increased density over time, which was particularly evident in women > 55 years of age.
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| 6. |
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| 7. |
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| 8. |
- Ba, Alexandre, et al.
(författare)
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Inter-laboratory comparison of channelized hotelling observer computation
- 2018
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Ingår i: Medical Physics. - : Wiley. - 0094-2405 .- 2473-4209. ; 45:7, s. 3019-3030
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The task-based assessment of image quality using model observers is increasingly used for the assessment of different imaging modalities. However, the performance computation of model observers needs standardization as well as a well-established trust in its implementation methodology and uncertainty estimation. The purpose of this work was to determine the degree of equivalence of the channelized Hotelling observer performance and uncertainty estimation using an intercomparison exercise. Materials and Methods: Image samples to estimate model observer performance for detection tasks were generated from two-dimensional CT image slices of a uniform water phantom. A common set of images was sent to participating laboratories to perform and document the following tasks: (a) estimate the detectability index of a well-defined CHO and its uncertainty in three conditions involving different sized targets all at the same dose, and (b) apply this CHO to an image set where ground truth was unknown to participants (lower image dose). In addition, and on an optional basis, we asked the participating laboratories to (c) estimate the performance of real human observers from a psychophysical experiment of their choice. Each of the 13 participating laboratories was confidentially assigned a participant number and image sets could be downloaded through a secure server. Results were distributed with each participant recognizable by its number and then each laboratory was able to modify their results with justification as model observer calculation are not yet a routine and potentially error prone. Results: Detectability index increased with signal size for all participants and was very consistent for 6 mm sized target while showing higher variability for 8 and 10 mm sized target. There was one order of magnitude between the lowest and the largest uncertainty estimation. Conclusions: This intercomparison helped define the state of the art of model observer performance computation and with thirteen participants, reflects openness and trust within the medical imaging community. The performance of a CHO with explicitly defined channels and a relatively large number of test images was consistently estimated by all participants. In contrast, the paper demonstrates that there is no agreement on estimating the variance of detectability in the training and testing setting.
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| 9. |
- Dustler, Magnus, et al.
(författare)
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Binary implementation of fractal Perlin noise to simulate fibroglandular breast tissue
- 2018
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Ingår i: Proceedings of SPIE : Medical Imaging 2018: Physics of Medical Imaging - Medical Imaging 2018: Physics of Medical Imaging. - : SPIE. ; 10573, s. 1-8
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Konferensbidrag (refereegranskat)abstract
- Software breast phantoms are important in many applications within the field of breast imaging and mammography. This paper describes an improved method of using a previously employed in-house fractal Perlin noise algorithm to create binary software breast phantoms. The Perlin Noise algorithm creates smoothly varying structures of a frequency with a set band limit. By combining a range of frequencies (octaves) of noise, more complex structures are generated. Previously, visually realistic appearances were achieved with continuous noise values, but these do not adequately represent the breast as radiologically consisting of two types of tissue - fibroglandular and adipose. A binary implementation with a similarly realistic appearance would therefore be preferable. A library of noise volumes with continuous values between 0 and 1 were generated. A range of threshold values, also between 0 and 1, were applied to these noise volumes, creating binary volumes of different appearance, with high values resulting in a fine network of strands, and low values in nebulous clusters of tissue. These building blocks were then combined into composite volumes and a new threshold applied to make them binary. This created visually complex binary volumes with a visually more realistic appearance than earlier implementations of the algorithm. By using different combinations of threshold values, a library of pre-generated building blocks can be used to create an arbitrary number of software breast tissue volumes with desired appearance and density.
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| 10. |
- Dustler, Magnus, et al.
(författare)
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Can mechanical imaging increase the specificity of mammography screening?
- 2017
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 27:8, s. 3217-3225
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This study aimed to investigate the effects of adding adjunct mechanical imaging to mammography breast screening. We hypothesized that mechanical imaging could detect increased local pressure caused by both malignant and benign breast lesions and that a pressure threshold for malignancy could be established. The impact of this on breast screening was investigated with regard to reductions in recall and biopsy rates. Methods: 155 women recalled from breast screening were included in the study, which was approved by the regional ethical review board (dnr 2013/620). Mechanical imaging readings were acquired of the symptomatic breast. The relative mean pressure on the suspicious area (RMPA) was defined and a threshold for malignancy was established. Results: Biopsy-proven invasive cancers had a median RMPA of 3.0 (interquartile range (IQR) = 3.7), significantly different from biopsy-proven benign at 1.3 (IQR = 1.0) and non-biopsied cases at 1.0 (IQR = 1.3) (P < 0.001). The lowest RMPA for invasive cancer was 1.4, with 23 biopsy-proven benign and 33 non-biopsied cases being below this limit. Had these women not been recalled, recall rates would have been reduced by 36% and biopsy rates by 32%. Conclusions: If implemented in a screening situation, this may substantially lower the number of false positives. Key Points: • Mechanical imaging is used as an adjunct to mammography in breast screening.• A threshold pressure can be established for malignant breast cancer.• Recalls and biopsies can be substantially reduced.
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| 11. |
- Dustler, Magnus, et al.
(författare)
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High-attenuation artifact reduction in breast tomosynthesis using a novel reconstruction algorithm
- 2019
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Ingår i: European Journal of Radiology. - : Elsevier BV. - 0720-048X. ; 116, s. 21-26
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To assess the effect on reducing the out-of-plane artifacts from metal objects in breast tomosynthesis (BT)using a novel artifact-reducing reconstruction algorithm in specimen radiography. Methods and Materials: The study was approved by the Regional Ethical Review Board. BT images of 18 partial- and whole mastectomy specimens from women with breast cancer were acquired before and after a needle was inserted close to the lesion. The images were reconstructed using both a standard reconstruction algorithm, and a novel algorithm; the latter uses pre-segmentation to remove highly attenuating artifact-inducing objects from projection images before reconstruction. Images were separately reconstructed with and without segmentation, and combined into an artifact-reduced reconstruction. Standard and artifact-reduced BT-algorithms were compared visually and quantitatively using clinical images of mastectomy specimens and a physical anthropomorphic phantom. Six readers independently assessed the visibility of the lesion with and without artifact-reduction in a side-by-side comparison. A quantitative analysis was performed, comparing the signal-difference to background ratio (SDBR)and artifact spread function (ASF)between the two reconstruction methods. Results: The magnitude of out-of-plane artifacts was clearly reduced with the novel reconstruction compared to BT-images without artifact reduction. Lesion masking by artifacts was largely averted; tumour visibility was comparable to standard BT images without a needle. In 76 ± 8% (standard deviation)of cases overall, readers could confidently state needle location. The same figure was 94 ± 6% for whole mastectomy cases, compared to 62 ± 17% for partial mastectomies. With metal artifact reduction, SDBR increased by 97% in the phantom, and by 69% in the mastectomies. The artifact spread function was substantially narrower. Conclusion: Artifact reduction in BT using a novel reconstruction method enables qualitatively and quantitatively improved clinical use of BT when metal artifacts can be a limiting factor such as in tomosynthesis-guided biopsy.
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| 12. |
- Dustler, Magnus, et al.
(författare)
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The characteristics of malignant breast tumors imaged using a prototype mechanical imaging system as an adjunct to mammography
- 2016
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Ingår i: Breast Imaging : 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings - 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783319415451 - 9783319415468 ; 9699, s. 282-288
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Konferensbidrag (refereegranskat)abstract
- Breast cancer is diagnosed by a combination of modalities. Measuring the elasto-mechanical properties of suspicious lesions, by e.g. ultrasound elastography, can help differentiate malignant from benign findings. Using a prototype Mechanical Imaging (MI) system as an adjunct to mammography, the aim of this study was to characterize tumors using MI and compare the readings to those from the contralateral breast. Thirteen bilateral MI sets from women with malignant breast lesions were included in this study, drawn from a larger set of 155 women recalled from screening. The results showed that mean lesion pressure was significantly greater than the mean pressure of the corresponding breast, 7.5 ± 7.0 kPa compared to 2.5 ± 1.6 kPa (P = 0.01). There was no evidence for a difference in mean pressure or standard deviation of the MI image between symptomatic and contralateral asymptomatic breasts (P = 0.24 and 0.68). The results support that it is possible to use MI to distinguish malignant cancers from normal breast tissue. Still, further investigations of the characteristics of benign lesions are necessary to ascertain the usefulness of the system.
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| 13. |
- Förnvik, Hannie
(författare)
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Optimization of breast tomosynthesis: Computer simulations of image acquisition and glandular dose
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Breast tomosynthesis (BT) is an X-ray imaging technique recently introduced as an alternative or complement to standard digital mammography (DM) in breast imaging and breast cancer screening. In BT, a set of projection images is acquired over a limited angular range and reconstructed into a volume of slice images. The method includes many possible combinations of acquisition parameters that have to be optimized for best possible clinical performance and outcome. The visibility of breast cancer lesions is important in this context. Compared to DM images, the reconstructed BT volume provides additional information on depth, reducing the superposition of breast tissue, which may hide true lesions or appear as false positive findings. Thus, the BT volume also contains information about the distribution of dense tissue within the breast, which is of interest when estimating the radiation dose from DM and BT exposure.In this thesis, a simulation procedure was developed for the optimization of image acquisition and estimation of individual glandular dose in BT. The procedure was shown to be useful in generating BT images with realistic sharpness, though with higher image noise and contrast than experimentally acquired images (Paper I). The procedure was used to investigate the influence of angular range, distribution of projection images, and dose distribution on simulated microcalcifications in reconstructed BT volumes. Image acquisitions with very high central dose yielded significantly lower visibility than acquisitions with more uniform dose distributions, and the depth resolution increased with wider angular range (Paper II).A method for localizing dense tissue from reconstructed BT volumes was verified using the simulation procedure (Paper III). A prototype software program was used for automatic and objective estimation of breast density in BT, with similar performance as DM (Paper IV). Using software breast phantoms recreated from reconstructed BT volumes, the glandular dose could be estimated with good overall accuracy for breast phantoms with different amounts and distributions of dense tissue (Paper V).The developed simulation procedure has been a useful tool for optimizing acquisition parameters and estimating glandular dose in BT. The procedure could potentially be developed for further evaluation of the imaging chain and estimation of individual glandular dose in human cases.
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| 14. |
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| 15. |
- Timberg, Pontus, et al.
(författare)
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Breast density assessment using breast tomosynthesis images
- 2016
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Ingår i: Breast Imaging : 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings - 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783319415451 - 9783319415468 ; 9699, s. 197-202
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Konferensbidrag (refereegranskat)abstract
- In this work we evaluate an approach for breast density assessment of digital breast tomosynthesis (DBT) data using the central projection image. A total of 348 random cases (both FFDM CC and MLO views and DBT MLO views) were collected using a Siemens Mammomat Inspiration tomosynthesis unit at Unilabs, Malmö. The cases underwent both BI-RADS 5th Edition labeling by radiologists and automated volumetric breast density analysis (VBDA) by an algorithm. Preliminary results showed an observed agreement of 70% (weighted Kappa, κ = 0.73) between radiologists and VBDA using FFDM images and 63% (κ = 0.62) for radiologists and VBDA using DBT images. Comparison between densities for FFDM and DBT resulted in high correlation (r = 0.94) and an observed agreement of 72% (κ = 0.76). The automated analysis is a promising approach using low dose central projection DBT images in order to get radiologist- like density ratings similar to results obtained from FFDM.
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