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898 results on '"Noël, Peter"'

1. Convolutional neural network-based single-shot speckle tracking for x-ray phase-contrast imaging

Author

Shi, Serena Qinyun Z., Shapira, Nadav, Noël, Peter B., and Meyer, Sebastian

Subjects
Physics - Medical Physics, Electrical Engineering and Systems Science - Image and Video Processing
Abstract

X-ray phase-contrast imaging offers enhanced sensitivity for weakly-attenuating materials, such as breast and brain tissue, but has yet to be widely implemented clinically due to high coherence requirements and expensive x-ray optics. Speckle-based phase contrast imaging has been proposed as an affordable and simple alternative; however, obtaining high-quality phase-contrast images requires accurate tracking of sample-induced speckle pattern modulations. This study introduced a convolutional neural network to accurately retrieve sub-pixel displacement fields from pairs of reference (i.e., without sample) and sample images for speckle tracking. Speckle patterns were generated utilizing an in-house wave-optical simulation tool. These images were then randomly deformed and attenuated to generate training and testing datasets. The performance of the model was evaluated and compared against conventional speckle tracking algorithms: zero-normalized cross-correlation and unified modulated pattern analysis. We demonstrate improved accuracy (1.7 times better than conventional speckle tracking), bias (2.6 times), and spatial resolution (2.3 times), as well as noise robustness, window size independence, and computational efficiency. In addition, the model was validated with a simulated geometric phantom. Thus, in this study, we propose a novel convolutional-neural-network-based speckle-tracking method with enhanced performance and robustness that offers improved alternative tracking while further expanding the potential applications of speckle-based phase contrast imaging.

Published
2023

7. High-Sensitivity Iodine Imaging by Combining Spectral CT Technologies

Author

Tivnan, Matthew, Gang, Grace, Cao, Wenchao, Shapira, Nadav, Noel, Peter B., and Stayman, J. Webster

Subjects
Physics - Medical Physics, Electrical Engineering and Systems Science - Image and Video Processing
Abstract

Spectral CT offers enhanced material discrimination over single-energy systems and enables quantitative estimation of basis material density images. Water/iodine decomposition in contrast-enhanced CT is one of the most widespread applications of this technology in the clinic. However, low concentrations of iodine can be difficult to estimate accurately, limiting potential clinical applications and/or raising injected contrast agent requirements. We seek high-sensitivity spectral CT system designs which minimize noise in water/iodine density estimates. In this work, we present a model-driven framework for spectral CT system design optimization to maximize material separability. We apply this tool to optimize the sensitivity spectra on a spectral CT test bench using a hybrid design which combines source kVp control and k-edge filtration. Following design optimization, we scanned a water/iodine phantom with the hybrid spectral CT system and performed dose-normalized comparisons to two single-technique designs which use only kVp control or only kedge filtration. The material decomposition results show that the hybrid system reduces both standard deviation and crossmaterial noise correlations compared to the designs where the constituent technologies are used individually.

Published
2021

8. Combining Spectral CT Acquisition Methods for High-Sensitivity Material Decomposition

Author

Tivnan, Matthew, Wang, Wenying, Gang, Grace, Liapi, Eleni, Noel, Peter, and Stayman, J. Webster

Subjects
Physics - Medical Physics, Electrical Engineering and Systems Science - Image and Video Processing
Abstract

Quantitative estimation of contrast agent concentration is made possible by spectral CT and material decomposition. There are several approaches to modulate the sensitivity of the imaging system to obtain the different spectral channels required for decomposition. Spectral CT technologies that enable this varied sensitivity include source kV-switching, dual-layer detectors, and source-side filtering (e.g., tiled spatial-spectral filters). In this work, we use an advanced physical model to simulate these three spectral CT strategies as well as hybrid acquisitions using all combinations of two or three strategies. We apply model-based material decomposition to a water-iodine phantom with iodine concentrations from 0.1 to 5.0 mg/mL. We present bias-noise plots for the different combinations of spectral techniques and show that combined approaches permit diversity in spectral sensitivity and improve low concentration imaging performance relative to the those strategies applied individually. Better ability to estimate low concentrations of contrast agent has the potential to reduce risks associated with contrast administration (by lowering dosage) or to extend imaging applications into targets with much lower uptake.

Published
2020
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16. Development of a robust radiomic biomarker of progression-free survival in advanced non-small cell lung cancer patients treated with first-line immunotherapy

Author

Singh, Apurva, Horng, Hannah, Roshkovan, Leonid, Weeks, Joanna K., Hershman, Michelle, Noël, Peter, Luna, José Marcio, Cohen, Eric A., Pantalone, Lauren, Shinohara, Russell T., Bauml, Joshua M., Thompson, Jeffrey C., Aggarwal, Charu, Carpenter, Erica L., Katz, Sharyn I., and Kontos, Despina

Published
2022
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22. Hybrid spectral CT system with clinical rapid kVp-switching x-ray tube and dual-layer detector for improved iodine quantification

Author

Sandvold, Olivia F., primary, Proksa, Roland, additional, Daerr, Heiner, additional, Perkins, Amy E., additional, Brown, Kevin M., additional, Shapira, Nadav, additional, Köhler, Thomas, additional, Stayman, Joseph W., additional, Gang, Grace J., additional, Manjeshwar, Ravindra M., additional, and Noël, Peter B., additional

Published
2024
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39. Combined inhibition of BET family proteins and histone deacetylases as a potential epigenetics-based therapy for pancreatic ductal adenocarcinoma

Author

Mazur, Pawel K, Herner, Alexander, Mello, Stephano S, Wirth, Matthias, Hausmann, Simone, Sánchez-Rivera, Francisco J, Lofgren, Shane M, Kuschma, Timo, Hahn, Stephan A, Vangala, Deepak, Trajkovic-Arsic, Marija, Gupta, Aayush, Heid, Irina, Noël, Peter B, Braren, Rickmer, Erkan, Mert, Kleeff, Jörg, Sipos, Bence, Sayles, Leanne C, Heikenwalder, Mathias, Heßmann, Elisabeth, Ellenrieder, Volker, Esposito, Irene, Jacks, Tyler, Bradner, James E, Khatri, Purvesh, Sweet-Cordero, E Alejandro, Attardi, Laura D, Schmid, Roland M, Schneider, Guenter, Sage, Julien, and Siveke, Jens T

Subjects
Biomedical and Clinical Sciences, Oncology and Carcinogenesis, Genetics, Rare Diseases, Pancreatic Cancer, Digestive Diseases, Cancer, Adenocarcinoma, Animals, Carcinoma, Pancreatic Ductal, Clustered Regularly Interspaced Short Palindromic Repeats, Epigenesis, Genetic, Histone Deacetylase Inhibitors, Humans, Mice, Proteins, Medical and Health Sciences, Immunology, Biomedical and clinical sciences, Health sciences
Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human cancers and shows resistance to any therapeutic strategy used. Here we tested small-molecule inhibitors targeting chromatin regulators as possible therapeutic agents in PDAC. We show that JQ1, an inhibitor of the bromodomain and extraterminal (BET) family of proteins, suppresses PDAC development in mice by inhibiting both MYC activity and inflammatory signals. The histone deacetylase (HDAC) inhibitor SAHA synergizes with JQ1 to augment cell death and more potently suppress advanced PDAC. Finally, using a CRISPR-Cas9-based method for gene editing directly in the mouse adult pancreas, we show that de-repression of p57 (also known as KIP2 or CDKN1C) upon combined BET and HDAC inhibition is required for the induction of combination therapy-induced cell death in PDAC. SAHA is approved for human use, and molecules similar to JQ1 are being tested in clinical trials. Thus, these studies identify a promising epigenetic-based therapeutic strategy that may be rapidly implemented in fatal human tumors.

Published
2015

40. 3D printed phantom with 12 000 submillimeter lesions to improve efficiency in CT detectability assessment.

Author

Shunhavanich, Picha, Mei, Kai, Shapira, Nadav, Stayman, Joseph Webster, McCollough, Cynthia H., Gang, Grace, Leng, Shuai, Geagan, Michael, Yu, Lifeng, Noël, Peter B., and Hsieh, Scott S.

Subjects
RECEIVER operating characteristic curves, PRINTMAKING, THREE-dimensional printing, STANDARD deviations
Abstract

Background: The detectability performance of a CT scanner is difficult to precisely quantify when nonlinearities are present in reconstruction. An efficient detectability assessment method that is sensitive to small effects of dose and scanner settings is desirable. We previously proposed a method using a search challenge instrument: a phantom is embedded with hundreds of lesions at random locations, and a model observer is used to detect lesions. Preliminary tests in simulation and a prototype showed promising results. Purpose: In this work, we fabricated a full‐size search challenge phantom with design updates, including changes to lesion size, contrast, and number, and studied our implementation by comparing the lesion detectability from a nonprewhitening (NPW) model observer between different reconstructions at different exposure levels, and by estimating the instrument sensitivity to detect changes in dose. Methods: Designed to fit into QRM anthropomorphic phantoms, our search challenge phantom is a cylindrical insert 10 cm wide and 4 cm thick, embedded with 12 000 lesions (nominal width of 0.6 mm, height of 0.8 mm, and contrast of −350 HU), and was fabricated using PixelPrint, a 3D printing technique. The insert was scanned alone at a high dose to assess printing accuracy. To evaluate lesion detectability, the insert was placed in a QRM thorax phantom and scanned from 50 to 625 mAs with increments of 25 mAs, once per exposure level, and the average of all exposure levels was used as high‐dose reference. Scans were reconstructed with three different settings: filtered‐backprojection (FBP) with Br40 and Br59, and Sinogram Affirmed Iterative Reconstruction (SAFIRE) with strength level 5 and Br59 kernel. An NPW model observer was used to search for lesions, and detection performance of different settings were compared using area under the exponential transform of free response ROC curve (AUC). Using propagation of uncertainty, the sensitivity to changes in dose was estimated by the percent change in exposure due to one standard deviation of AUC, measured from 5 repeat scans at 100, 200, 300, and 400 mAs. Results: The printed insert lesions had an average position error of 0.20 mm compared to printing reference. As the exposure level increases from 50 mAs to 625 mAs, the lesion detectability AUCs increase from 0.38 to 0.92, 0.42 to 0.98, and 0.41 to 0.97 for FBP Br40, FBP Br59, and SAFIRE Br59, respectively, with a lower rate of increase at higher exposure level. FBP Br59 performed best with AUC 0.01 higher than SAFIRE Br59 on average and 0.07 higher than FBP Br40 (all P < 0.001). The standard deviation of AUC was less than 0.006, and the sensitivity to detect changes in mAs was within 2% for FBP Br59. Conclusions: Our 3D‐printed search challenge phantom with 12 000 submillimeter lesions, together with an NPW model observer, provide an efficient CT detectability assessment method that is sensitive to subtle effects in reconstruction and is sensitive to small changes in dose. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Spectral performance evaluation of a second‐generation spectral detector CT.

Author

Liu, Leening P., Shapira, Nadav, Halliburton, Sandra S., Meyer, Sebastian, Perkins, Amy, Litt, Harold I., Kauczor, Hans Ulrich, Leiner, Tim, Stiller, Wolfram, and Noël, Peter B.

Subjects
MULTIDETECTOR computed tomography, DUAL energy CT (Tomography), STANDARD deviations, ADIPOSE tissues, DETECTORS
Abstract

Purpose: The aim of this study was to characterize a second‐generation wide‐detector dual‐layer spectral computed tomography (CT) system for material quantification accuracy, acquisition parameter and patient size dependencies, and tissue characterization capabilities. Methods: A phantom with multiple tissue‐mimicking and material‐specific inserts was scanned with a dual‐layer spectral detector CT using different tube voltages, collimation widths, radiation dose levels, and size configurations. Accuracy of iodine density maps and virtual monoenergetic images (MonoE) were investigated. Additionally, differences between conventional and MonoE 70 keV images were calculated to evaluate acquisition parameter and patient size dependencies. To demonstrate material quantification and differentiation, liver‐mimicking inserts with adipose and iron were analyzed with a two‐base decomposition utilizing MonoE 50 and 150 keV, and root mean square error (RMSE) for adipose and iron content was reported. Results: Measured inserts exhibited quantitative accuracy across a wide range of MonoE levels. MonoE 70 keV images demonstrated reduced dependence compared to conventional images for phantom size (1 vs. 27 HU) and acquisition parameters, particularly tube voltage (4 vs. 37 HU). Iodine density quantification was successful with errors ranging from ‐0.58 to 0.44 mg/mL. Similarly, inserts with different amounts of adipose and iron were differentiated, and the small deviation in values within inserts corresponded to a RMSE of 3.49 ± 1.76% and 1.67 ± 0.84 mg/mL for adipose and iron content, respectively. Conclusion: The second‐generation dual‐layer CT enables acquisition of quantitatively accurate spectral data without compromises from differences in patient size and acquisition parameters. [ABSTRACT FROM AUTHOR]

Published
2024
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