| 194431. |
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| 194432. |
- Tímár, József, et al.
(författare)
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Newly identified form of phenotypic plasticity of cancer : immunogenic mimicry
- 2023
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Ingår i: Cancer and Metastasis Reviews. - : Springer Science and Business Media LLC. - 0167-7659 .- 1573-7233. ; 42:1, s. 323-334
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Forskningsöversikt (refereegranskat)abstract
- Cancer plasticity is now a recognized new hallmark of cancer which is due to disturbances of cell differentiation programs. It is manifested not only in various forms like the best-known epithelial-mesenchymal transition (EMT) but also in vasculogenic and megakaryocytic mimicries regulated by EMT-specific or less-specific transcription factors such as HIF1a or STAT1/2. Studies in the past decades provided ample data that cancer plasticity can be manifested also in the expression of a vast array of immune cell genes; best-known examples are PDL1/CD274, CD47, or IDO, and we termed it immunogenic mimicry (IGM). However, unlike other types of plasticities which are epigenetically regulated, expression of IGM genes are frequently due to gene amplifications. It is important that the majority of the IGM genes are regulated by interferons (IFNs) suggesting that their protein expressions are regulated by the immune microenvironment. Most of the IGM genes have been shown to be involved in immune escape of cancers broadening the repertoire of these mechanisms and offering novel targets for immunotherapeutics.
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| 194433. |
- Timár, J., et al.
(författare)
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Terminating bands in 98,99,100Ru nuclei : New information on the neutron 2d5/2 and 1g7/2 energy spacing
- 2000
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Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states of 98,99,100Ru have been populated using the reaction 70Zn(36S, αxn) at 130 MeV. The γ rays have been detected with the EUROGAM-2 array. New high-spin bands have been established in these nuclei and interpreted as terminating configurations using the Nilsson-Strutinsky cranking formalism. These bands were observed up to the predicted terminating states which are built from g9/2 protons and N=3 proton holes combined with d5/2, 87/2, and h11/2 neutrons relative to a 90Zr core. Core-excited configurations with N=3 proton holes have been found to play an important role. The observed high-spin states assigned as terminating show systematic behavior and provide new information on the energy spacing between the 2d5/2 and 1 g7/2 neutron subshells.
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| 194434. |
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| 194435. |
- 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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| 194436. |
- Timberg, Pontus
(författare)
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Breast Tomosynthesis: Aspects on detection and perception of simulated lesions
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to investigate aspects on detectability of simulated lesions (microcalcifications and masses) in digital mammography (DM) and breast tomosynthesis (BT). Perception in BT image volumes were also investigated by evaluating certain reading conditions. The first study concerned the effect of system noise on the detection of masses and microcalcification clusters in DM images using a free-response task. System noise has an impact on image quality and is related to the dose level. It was found to have a substantial impact on the detection of microcalcification clusters, whereas masses were relatively unaffected. The effect of superimposed tissue in DM is the major limitation hampering the detection of masses. BT is a three-dimensional technique that reduces the effect of superimposed tissue. In the following two studies visibility was quantified for both imaging modalities in terms of the required contrast at a fixed detection performance (92% correct decisions). Contrast detail plots for lesions with sizes 0.2, 1, 3, 8 and 25 mm were generated. The first study involved only an in-plane BT slice, where the lesion centre appeared. The second study repeated the same procedure in BT image volumes for 3D distributed microcalcification clusters and 8 mm masses at two dose levels. Both studies showed that BT needs substantially less contrast than DM for lesions above 1 mm. Furthermore, the contrast threshold increased as the lesion size increased for both modalities. This is in accordance with the reduced effect of superimposed tissue in BT. For 0.2 mm lesions, substantially more contrast was needed. At equal dose, DM was better than BT for 0.2 mm lesions and microcalcification clusters. Doubling the dose substantially improved the detection in BT. Thus, system noise has a substantial impact on detection. The final study evaluated reading conditions for BT image volumes. Four viewing procedures were assessed: free scroll browsing only or combined with initial cine loops at frame rates of 9, 14 and 25 fps. They were viewed on a wide screen monitor placed in vertical or horizontal positions. A free-response task and eye tracking were utilized to record the detection performance, analysis time, visual attention and search strategies. Improved reading conditions were found for horizontally aligned BT image volumes when using free scroll browsing only or combined with a cine loop at the fastest frame rate.
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| 194437. |
- Timberg, Pontus, et al.
(författare)
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Detection of calcification clusters in digital breast tomosynthesis slices at different dose levels utilizing a SRSAR reconstruction and JAFROC
- 2015
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Ingår i: Medical Imaging 2015: Image Perception, Observer Performance, and Technology Assessment. - : SPIE. - 1996-756X .- 0277-786X. ; 9416, s. 941604-941604
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Konferensbidrag (refereegranskat)abstract
- Purpose: To investigate detection performance for calcification clusters in reconstructed digital breast tomosynthesis (DBT) slices at different dose levels using a Super Resolution and Statistical Artifact Reduction (SRSAR) reconstruction method. Method: Simulated calcifications with irregular profile (0.2 mm diameter) where combined to form clusters that were added to projection images (1-3 clusters per abnormal image) acquired on a DBT system (Mammomat Inspiration, Siemens). The projection images were dose reduced by software to form 35 abnormal cases and 25 normal cases as if acquired at 100%, 75% and 50% dose level (AGD of approximately 1.6 mGy for a 53 mm standard breast, measured according to EUREF v0.15). An FBP algorithm adapted to DBT (called standard FBP) and a SRSAR reconstruction method utilizing iterative reconstruction filtering, and outlier detection using Maximum-Intensity Projections and Average-Intensity Projections) were used to reconstruct single central slices to be used in a free-response task (60 images per observer and dose level). Six observers participated and their task was to detect clusters and assign confidence rating in randomly presented images from the whole image set (balanced by dose level). Each trial was separated by one week to reduce possible memory bias. The outcome was analyzed for statistical differences using Jackknife Alternative Free-response Receiver Operating Characteristics. Results: The results indicate that it is possible to reduce the dose by 50% with SRSAR without jeopardizing cluster detection. Conclusions: The detection performance for clusters can be maintained at a lower dose level by using SRSAR reconstruction.
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| 194438. |
- Timberg, Pontus, et al.
(författare)
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Impact of dose on observer performance in breast tomosynthesis using breast specimens
- 2008
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 6913, s. 9134-9134
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this study was to investigate the effect of dose on lesion detection† and characterization in breast tomosynthesis (BT), using human breast specimens. Images of 27 lesions in breast specimens were acquired on a BT prototype‡ based on a Mammomat Novation (Siemens) full-field digital mammography (FFDM) system. Two detector modes - binned (2×1 in the scan direction) and full resolution - and four BT exposure levels - approximately 2×, 1.5×, 1×, and 0.5× the total mAs at the same beam quality as used in a single FFDM view with a Mammomat Novation unit under automatic exposure control (AEC) conditions - were examined. The exposure for all BT scans was equally divided among 25 projections. An enhanced filtered back projection reconstruction method was applied with a constant filter setting. A human observer performance study was conducted in which the observers were forced to select the minimum (threshold) exposure level at which each lesion could be both detected and characterized for assessment of recall or not in a screening situation. The median threshold exposure level for all observers and all lesions corresponded to approximately 1×, which is half the exposure of what we currently use for BT. A substantial variation in exposure thresholds was noticed for different lesion types. For low contrast lesions with diffuse borders, an exposure threshold of approximately 2× was required, whereas for spiculated high contrast lesions and lesions with well defined borders, the exposure threshold was lower than 0.5×. The use of binned mode had no statistically significant impact on observer performance compared to full resolution mode. There was no substantial difference between the modes for the detection and characterization of the lesion types.
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| 194439. |
- Timberg, Pontus, et al.
(författare)
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In-plane visibility of lesions using breast tomosynthesis and digital mammography
- 2010
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Ingår i: Medical Physics. - : Wiley. - 0094-2405. ; 37:11, s. 5618-5626
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this work was to evaluate the visibility of simulated lesions in 2D digital mammography (DM) and breast tomosynthesis (BT) images of patients. Methods: Images of the same women were acquired on both a DM system (Mammomat Novation, Siemens Healthcare, Erlangen, Germany) and a BT prototype system adapted from the same type of DM system. Using the geometrical properties of the two systems, simulated lesions were projected and added to each DM image as well as to each BT projection image prior to 3D reconstruction. The same beam quality and approximately the same total absorbed dose to the glandular tissue were used for each breast image acquisition on the two systems. A series of four-alternative forced choice human observer experiments was conducted for each of five simulated lesion diameters: 0.2, 1, 3, 8, and 25 mm. An additional experiment was conducted for the 0.2 mm lesion in BT only at twice the dose level (BT2x). Threshold signal was defined as the lesion signal intensity required for a detectability index (d') of 2.5. Four medical physicists participated in all experiments. One experiment, consisting of 60 cases, was conducted per test condition (i.e., lesion size and signal combination). Results: For the smallest lesions (0.2 mm), the threshold signal for DM was 21% lower than for BT at equivalent dose levels, and BT2x was 26% lower than DM. For the lesions larger than 1 mm, the threshold signal increased linearly (in log space) with the lesion diameter for both DM and BT, with DM requiring around twice the signal as BT. The difference in the threshold signal between BT and DM at each lesion size was statistically significant, except for the 0.2 mm lesion between BT2x and DM. Conclusions: The results of this study indicate that low-signal lesions larger than 1.0 mm may be more visible in BT compared to DM, whereas 0.2 mm lesions may be better visualized with DM compared to BT, when compared at equal dose. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3488899]
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| 194440. |
- Timberg, Pontus, et al.
(författare)
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Investigation of viewing procedures for interpretation of breast tomosynthesis image volumes: a detection-task study with eye tracking.
- 2013
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 23:4, s. 997-1005
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To evaluate the efficiency of different methods of reading breast tomosynthesis (BT) image volumes. METHODS: All viewing procedures consisted of free scroll volume browsing and three were combined with initial cine loops at three different frame rates (9, 14 and 25 fps). The presentation modes consisted of vertically and horizontally orientated BT image volumes. Fifty-five normal BT image volumes in mediolateral oblique view were collected. In these, simulated lesions were inserted, creating four unique image sets, one for each viewing procedure. Four observers interpreted the cases in a free-response task. Time efficiency, visual attention and search were investigated using eye tracking. RESULTS: Horizontally orientated BT image volumes were read faster than vertically when using free scroll browsing only and when combined with fast cine loop. Cine loops at slow frame rates were ruled out as inefficient. CONCLUSIONS: In general, horizontally oriented BT image volumes were read more efficiently. All viewing procedures except for slow frame rates were promising when assuming equivalent detection performance. KEY POINTS : • Breast tomosynthesis is increasingly used for breast cancer detection • There is a benefit in reading breast tomosynthesis image volumes presented horizontally • Align image content to visual field, especially for dynamic 3D images • Reading at slow frame rates was considered inefficient.
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