المؤلفون: Sauter, Andreas P., Kopp, Felix K., Bippus, Rolf, Dangelmaier, Julia, Deniffel, Dominik, Fingerle, Alexander A., Meurer, Felix, Pfeiffer, Daniela, Proksa, Roland, Rummeny, Ernst J., Noël, Peter B.

المصدر: European Radiology; Nov2019, Vol. 29 Issue 11, p5950-5960, 11p, 2 Color Photographs, 3 Charts, 3 Graphs

مصطلحات موضوعية: PULMONARY embolism, TOMOGRAPHY, FEASIBILITY studies, COMPUTED tomography, DIAGNOSTIC imaging, ANALYSIS of variance, LUNGS, PATIENT safety, RADIATION doses, RESEARCH funding, PILOT projects, MEDICAL artifacts

مستخلص: Objectives: Evaluation of sparse sampling computed tomography (SpSCT) regarding subjective and objective image criteria for the detection of pulmonary embolism (PE) at different simulated dose levels.Methods: Computed tomography pulmonary angiography (CTPA) scans of 20 clinical patients were used to obtain simulated low-dose scans with 100%-50%-25%-12.5%-6.3%-3.1% of the clinical dose, resulting in a total of six dose levels (DL). From these full sampling (FS) data, every second (2-SpSCT) or fourth (4-SpSCT) projection was used to obtain simulated sparse sampling scans. Each image set was evaluated by four blinded radiologists regarding subjective image criteria (artifacts, image quality) and diagnostic performance (confidence, sensitivity, specificity, accuracy, and area under the curve). Additionally, the contrast-to-noise ratio (CNR) was evaluated for objective image quality.Results: Sensitivity was 100% with 2-SpSCT and 4-SpSCT at the 25% DL and the 12.5% DL for all localizations of PE (one subgroup 98.5%). With FS, the sensitivity decreased to 90% at the 12.5% DL. 2-SpSCT and 4-SpSCT showed higher values for sensitivity, specificity, accuracy, and the area under the curve at all DL compared with FS. Subjective image quality was significantly higher for 4-SpSCT compared with FS at each dose level (p < 0.01, paired t test). Only with 4-SpSCT, all examinations were rated as showing diagnostic image quality at the 12.5% DL.Conclusions: Via SpSCT, a dose reduction down to a 12.5% dose level (corresponding to a mean effective dose of 0.38 mSv in the current study) for CTPA is possible while maintaining high image quality and full diagnostic confidence.Key Points: • With sparse sampling CT, radiation dose could be significantly reduced in clinical routine. • Sparse sampling CT is a novel hardware solution with which less projection images are acquired. • In the current study, a dose reduction of 87.5% (corresponding to a mean effective dose of 0.38 mSv) for CTPA could be achieved while maintaining excellent diagnostic performance. [ABSTRACT FROM AUTHOR]

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المؤلفون: Ando, Masami, Sunaguchi, Naoki, Wu, Yanlin, Do, Synho, Sung, Yongjin, Louissaint, Abner, Yuasa, Tetsuya, Ichihara, Shu, Gupta, Rajiv

المصدر: European Radiology; Feb2014, Vol. 24 Issue 2, p423-433, 11p, 6 Color Photographs

مصطلحات موضوعية: DIAGNOSTIC imaging research, MAMMOGRAMS, COMPUTED tomography, BREAST tumors, BREAST cancer research

مستخلص: Objectives: We demonstrate the soft tissue discrimination capability of X-ray dark-field imaging (XDFI) using a variety of human tissue specimens. Methods: The experimental setup for XDFI comprises an X-ray source, an asymmetrically cut Bragg-type monochromator-collimator (MC), a Laue-case angle analyser (LAA) and a CCD camera. The specimen is placed between the MC and the LAA. For the light source, we used the beamline BL14C on a 2.5-GeV storage ring in the KEK Photon Factory, Tsukuba, Japan. Results: In the eye specimen, phase contrast images from XDFI were able to discriminate soft-tissue structures, such as the iris, separated by aqueous humour on both sides, which have nearly equal absorption. Superiority of XDFI in imaging soft tissue was further demonstrated with a diseased iliac artery containing atherosclerotic plaque and breast samples with benign and malignant tumours. XDFI on breast tumours discriminated between the normal and diseased terminal duct lobular unit and between invasive and in-situ cancer. Conclusions: X-ray phase, as detected by XDFI, has superior contrast over absorption for soft tissue processes such as atherosclerotic plaque and breast cancer. Key points: • X-ray dark field imaging (XDFI) can dramatically increase sensitivity of phase detection. • XDFI can provide enhanced soft tissue discrimination. • With XDFI, abnormal anatomy can be visualised with high spatial/contrast resolution. [ABSTRACT FROM AUTHOR]

: Copyright of European Radiology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)