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image postprocessing of aortic CTA and MRA

RADIOLOGE 2007年第11期47卷 1003-1011页

作者： von Tengg-Kobligk, H. Weber, T. F. Rengier, F. Boeckler, D. Schumacher, H. Kauczor, H. -U. Univ Heidelberg Klin Gefasschirurg Vasculaire & Endovasc Chirurg Heidelberg Germany Klinikum Stadt Hanau Klin Gefasschirurg Hanau Germany

Multiplanar reformation (MPR) is the most relevant tool for patient selection and precise procedural planning and also for analyzing postinterventional complications. Curved MPR is used primarily for semiautomated or completely automated calculation of the centerline of the vascular lumen and to estimate the orthogonal vessel diameter and longitudinal extent. Reproducible and accurate measurement of complex pathologies and courses of vessels extends the range of diagnostic radiology. Contemporary scanner consoles allow automated processing of maximum intensity projections (MIP) and standard MPR and their storage in PACS. To improve patient selection, procedural planning, root-cause analysis postoperatively for assessment of treatment effects and to make better communication of findings to nonradiologists possible, volume rendering techniques (VRT) are a beneficial adjunct to source images. With current algorithms semiautomated segmentation is satisfactory for vessels and bones, but not for low-contrast structures (soft tissues), which still need to be segmented manually. In general, isotropic CT source data are preferable to MR images, which are often anisotropic. In many European countries image postprocessing is still not adequately reimbursed although the doctors making referrals often specifically and emphatically demand 3D visualization and measurements in daily practice.

关键词： aorta image postprocessing magnetic resonance angiography (MRA) computed tomography (CT) angiography

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Deep learning-based noise reduction for coronary CT angiography: using four-dimensional noise-reduction images as the ground truth

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ACTA RADIOLOGICA 2023年第5期64卷 1831-1840页

作者： Kobayashi, Takuma Nishii, Tatsuya Umehara, Kensuke Ota, Junko Ohta, Yasutoshi Fukuda, Tetsuya Ishida, Takayuki Osaka Univ Grad Sch Med Dept Med Phys & Engn Suita Japan Natl Cerebral & Cardiovasc Ctr Dept Radiol Suita Japan Natl Inst Quantum Sci & Technol QST QST Hosp Dept Med Technol Med Informat Sect Chiba Japan Natl Inst Quantum Sci & Technol Inst Quantum Med Sci Dept Mol Imaging & Theranost Appl MRI Res Chiba Japan Osaka Univ Dept Med Phys & Engn Grad Sch Med 1-7 Yamadaoka Suita Osaka 5650871 Japan

Background To assess low-contrast areas such as plaque and coronary artery stenosis, coronary computed tomography angiography (CCTA) needs to provide images with lower noise without increasing radiation doses. Purpose To develop a deep learning-based noise-reduction method for CCTA using four-dimensional noise reduction (4DNR) as the ground truth for supervised learning. Material and Methods \We retrospectively collected 100 retrospective ECG-gated CCTAs. We created 4DNR images using non-rigid registration and weighted averaging three timeline CCTA volumetric data with intervals of 50 ms in the mid-diastolic phase. Our method set the original reconstructed image as the input and the 4DNR as the target image and obtained the noise-reduced image via residual learning. We evaluated the objective image quality of the original and deep learning-based noise-reduction (DLNR) images based on the image noise of the aorta and the contrast-to-noise ratio (CNR) of the coronary arteries. Further, a board-certified radiologist evaluated the blurring of several heart structures using a 5-point Likert scale subjectively and assigned a coronary artery disease reporting and data system (CAD-RADS) category independently. Results DLNR CCTAs showed 64.5% lower image noise (P < 0.001) and achieved a 2.9 times higher CNR of coronary arteries than that in original images, without significant blurring in subjective comparison (P > 0.1). The intra-observer agreement of CAD-RADS in the DLNR image was excellent (0.87, 95% confidence interval = 0.77-0.99) with original CCTAs. Conclusion Our DLNR method supervised by 4DNR significantly reduced the image noise of CCTAs without affecting the assessment of coronary stenosis.

关键词： Coronary computed tomography angiography noise reduction deep learning convolutional neural network image postprocessing

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Separation of arteries and veins in 3D MR angiography using correlation analysis

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MAGNETIC RESONANCE IN MEDICINE 2000年第3期43卷 481-487页

作者： Bock, M Schoenberg, SO Floemer, F Schad, LR Deutsch Krebsforschungszentrum FS Radiol Diagnost & Therapie D-69120 Heidelberg Germany

Multiphase contrast-enhanced 3D MR angiography (MRA) data sets allow the separate visualization of the arterial and venous pulmonary vasculature. However, due to short arterial-to-venous bolus transit times in the lung, the generation of pure venograms without arterial overlay is difficult. To suppress arterial signal in venograms, early arterial phase data are typically subtracted from peak venous phase images. In this study, a correlation algorithm is used to postprocess the multiphase 3D MRA data sets. The cross-correlation between a measured arterial or venous reference function and the local signal-time course is computed which highlights image locations with a similar signal-time curve as the reference function and suppresses constant signal, Conventional maximum intensity projections (MIP) are generated from the arterial and venous correlation maps. In a study with five volunteers, an increase in SNR by a factor of 2.1 (1.8) of arterial (venous) correlation MIP images over subtraction MIP images was observed. (C) 2000 Wiley-Liss, Inc.

关键词： multiphase contrast-enhanced 3D MR angiography lung imaging image postprocessing

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Spectral Detector Computed Tomography Pulmonary Angiography: Improved Diagnostic Assessment and Automated Estimation of Window Settings Angiography of Pulmonary Arteries From Novel Spectral Detector Computed Tomography Provides Improved image Quality if Settings are Adjusted

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JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY 2018年第6期42卷 850-857页

作者： Hokamp, Nils Grosse Kessner, Rivka Van Hedent, Steven Graner, Frank Philipp Gupta, Amit Gilkeson, Robert Univ Hosp Cleveland Med Ctr Dept Radiol 11000 Euclid Ave Cleveland OH 44106 USA Case Western Reserve Univ Dept Radiol Cleveland OH 44106 USA Univ Hosp Brussels Dept Radiol Brussels Belgium

Objective This study aimed to evaluate image quality (IQ) of virtual monoenergetic images (VMIs) from novel spectral detector computed tomography angiography of the pulmonary arteries and to identify appropriate window settings for each kiloelectron volt level. Materials Forty consecutive patients were included in this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant study. Signal- and contrast-to-noise ratios were calculated within the pulmonary trunk, and pulmonary/lobar/segmental arteries were calculated. The IQ and diagnostic certainty were rated by 2 radiologists on 5-point scales. In addition, they recorded appropriate window settings (center/width) that were linearly modeled against attenuation within the pulmonary trunk to generate generable results. Results Signal- and contrast-to-noise ratios, IQ, and diagnostic certainty are significantly increased in low-kiloelectron volt VMIs (60 keV). Interrater agreement was excellent (? = 0.89). We developed 2 linear models (R-2: 0.91-0.97 and R-2: 0.43-0.91, respectively, P 0.01), that suggest appropriate window settings. Conclusions The VMIs from spectral detector computed tomography improve objective and subjective IQ in angiography of the pulmonary arteries, if window settings are adjusted;they can be automatically estimated using reported linear models.

关键词： dual-energy computed tomography spectral detector computed tomography image quality image postprocessing window settings pulmonary emboli

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Blocking artifact reduction in compressed images based on edge-adaptive quadrangle meshes

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JOURNAL OF VISUAL COMMUNICATION AND image REPRESENTATION 2003年第4期14卷 492-507页

作者： Gan, XC Liew, AWC Yan, H City Univ Hong Kong Dept Comp Engn & Informat Technol Kowloon Hong Kong Peoples R China Univ Sydney Sch Elect & Informat Engn Sydney NSW 2006 Australia

During image deblocking, the preservation of visually significant edges in the image is important. Based on the observation that blocking artifact along edge direction is difficult for human perception, a number of existing techniques have proposed to filter the edge pixels with low weight or bypass them altogether to avoid blurring. However, the un-processed artifacts that are anti-parallel to the edge direction often fragment the edges and seriously degrade visual quality. In this paper, by considering the behavior of intensity evolution along and across edges, we propose a new POCS-based algorithm using a new smoothness constraint set. The new constraint set is realized indirectly by limiting the distance between the coded image and the image simulated using edge-adaptive quadrangle meshes. Experimental results indicated that our method compares favorably with several existing techniques. (C) 2003 Elsevier Inc. All rights reserved.

关键词： image postprocessing adaptive mesh projections onto convex sets blocking artifacts smoothness constraint set quantization constraint set

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Feasibility of thin-slice, low noise images created using multi-kernel synthesis to replace multiple image series in head CT

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ACTA RADIOLOGICA 2024年第11期65卷 1411-1421页

作者： Inoue, Akitoshi Diehn, Felix E. Nagelschneider, Alex A. Passe, Theodore J. DeLone, David R. Nelson, Brandon J. Cardona, Daniel G. Gomez Huber, Nathan R. Missert, Andrew D. Yu, Lifeng Johnson, Matthew P. Holmes, David R. Lee, Yong S. Thorne, Jamison E. McCollough, Cynthia H. Fletcher, Joel G. Mayo Clin Dept Radiol 200 First St SW Rochester MN 55905 USA Mayo Clin Dept Quantitat Hlth Sci Rochester MN USA Mayo Clin Dept Physiol Biomed Engn Rochester MN USA Shiga Univ Med Sci Dept Radiol Shiga Japan Gunderson Hlth Syst Dept Imaging La Crosse WI USA

Background SynthesiZed Improved Resolution and Concurrent nOise reductioN (ZIRCON) is a multi-kernel synthesis method that creates a single series of thin-slice computed tomography (CT) images displaying low noise and high spatial resolution, increasing reader efficiency and minimizing partial volume *** To compare the diagnostic performance of a single set of ZIRCON images to two routine clinical image series using conventional CT head and bone reconstruction kernels for diagnosing intracranial findings and fractures in patients with trauma or suspected acute neurologic *** and Methods In total, 50 patients underwent clinically indicated head CT in the ER (15 normal, 35 abnormal cases). A non-reader neuroradiologist established the reference standard. Three neuroradiologists reviewed two routine clinical series (head and bone kernels) and a single ZIRCON series, detecting intracranial findings or fractures and rating confidence (0-100). Sensitivity, specificity, and jackknife free-response receiver operating characteristic (JAFROC) figure of merit (FOM) were compared (limit of non-inferiority: -0.10).Results ZIRCON and conventional images demonstrated comparable performance for fractures (sensitivity: 51.5% vs. 54.5%;specificity: 40.2% vs. 34.2%) and intracranial findings (sensitivity: 88.2% vs. 91.4%;specificity: 77.2% vs. 73.7%).The estimated difference of JAFROC FOM demonstrated ZIRCON non-inferiority for acute pathologies overall (0.003 [95% CI=-0.051-0.057]) and fractures (0.048 [95% CI=-0.050-0.145]) but not for intracranial findings alone (-0.024 [95% CI=-0.100-0.052]).Conclusion Thin-slice, low noise, and high spatial resolution images can be created to display intracranial findings and fractures replacing multiple images series in head CT with similar performance. Future studies in more patients and further algorithmic development are warranted.

关键词： Computed tomography image postprocessing trauma hemorrhage

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INSTRUMENTATION FOR MAGNETIC-RESONANCE ANGIOGRAPHY

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CARDIOVASCULAR AND INTERVENTIONAL RADIOLOGY 1992年第1期15卷 14-22页

作者： SALONER, D ANDERSON, CM Departments of Radiology Service (114) VA Medical Center and University of California San Francisco San Francisco USA

Magnetic resonance angiography (MRA) places high demands on instrumentation capabilities. Magnetic gradient strength capabilities, main magnetic field strength and homogeneity, and eddy current compensation all play a role in determining the quality of the flow studies. In addition, radiofrequency coil design and use is governed by the specific vascular territories of interest. Once the instrumentational and pulse sequence considerations have been optimized, the postprocessing and display of the acquired three-dimensional data sets is of key importance. Great strides have been made in addressing instrumentation needs for MRA, but further improvements are anticipated.

关键词： MAGNETIC RESONANCE ANGIOGRAPHY GRADIENT ECHO SEQUENCES RADIOFREQUENCY COILS image postprocessing

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Evaluation of Gd-enhancement in brain MR of multiple sclerosis: image subtraction with and without magnetization transfer.

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EUROPEAN RADIOLOGY 2002年第8期12卷 2077-2082页

作者： Sardanelli, F Losacco, C Iozzelli, A Renzetti, P Rosso, E Parodi, RC Bonetti, M Murialdo, A Ist Policlin San Donato Dept Diagnost Imaging I-20097 San Donato Milanese MI Italy Univ Genoa Sch Med Dept Expt Med Sect Diagnost Imaging I-16132 Genoa Italy San Martino Hosp Dept Neuroradiol I-16132 Genoa Italy Univ Genoa Sch Med Dept Neurol Sci & Vis I-16132 Genoa Italy

The aim of our study was to test the possibility of using image subtraction in detecting enhancing lesions in brain MR scans with and without magnetization transfer (MT) in multiple sclerosis (MS). Ten MS patients underwent 1.5-T MR imaging of the brain with spin-echo T1-weighted sequences with and without MT, repeated after 0.1 mmol/kg of an usual two-compartment paramagnetic contrast agent (Gadoteridol, Gd-HP-DO3A). Precontrast images were subtracted from postcontrast. Enhancing lesions were counted on the postcontrast images only (post-Gd), comparing pre- and postcontrast images by direct visual control (pre/post-Gd), and on the subtracted images (SI) only. Without MT, 36 enhancing lesions were counted on post-Gd, 36 on pre/post-Gd, and 59 on SI;using MT, 69, 52, and 50, respectively. Significant differences were found for pre/post-Gd without MT vs SI without MT (p = 0.028) and vs pre/post-Gd with MT (p = 0.012) as well as for pre/post-Gd with MT vs post-Gd with MT (p = 0.028). With pre/post-Gd, MT allowed the detection of 1.6 enhancing lesions per patient more than without MT. Whereas the SI without MT allow the detection of an increased number of enhancing lesions, SI with MT do not. An off-site final assessment allowed calculation of sensitivity and positive predictive value as follows: without MT were 63 and 94% (post-Gd), 67 and 100% (pre/post-Gd), 96 and 88% (SI);and with MT were 93 and 73% (post-Gd), 96 and 100% (pre/post-Gd), 91 and 98% (SI), respectively. Thus, SI seem to increase the sensitivity without MT;moreover, they could be used to correct the pseudoenhancement that impair post-Gd images with MT.

关键词： brain MR Gd-enhancement brain white matter MR magnetization transfer multiple sclerosis image postprocessing subtraction

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MR Lymphangiography: How I Do It

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JOURNAL OF MAGNETIC RESONANCE IMAGING 2015年第6期42卷 1465-1477页

作者： Mitsumori, Lee M. McDonald, Elizabeth S. Wilson, Gregory J. Neligan, Peter C. Minoshima, Satoshi Maki, Jeffrey H. Straub Clin & Hosp Dept Radiol Honolulu HI 96813 USA Univ Penn Dept Radiol Philadelphia PA 19104 USA Univ Washington Dept Radiol Seattle WA 98195 USA Univ Washington Dept Plast Surg Seattle WA 98195 USA

Lymphedema is a chronic progressive edematous disease that in the United States is most commonly related to malignancy and its treatment. Lymphaticovenular anastomosis is a recently introduced microsurgical treatment option for lymphedema that requires the identification and mapping of individual lymphatic channels. While nuclear medicine lymphoscintigraphy has been the primary imaging modality performed to evaluate suspected lymphedema, lymphoscintigraphy does not provide the spatial information necessary for presurgical planning. High-resolution dynamic 3D magnetic resonance imaging (MRI) can noninvasively image abnormal lymphatic channels to both diagnose lymphedema and depict the location and number of individual lymphatic channels for surgical planning. MR lymphangiography can be performed at 1.5T or 3.0T using multichannel phased array surface coils. The main components of the exam are a heavily T2-weighted 3D sequence to define the severity and extent of edema, a high-resolution dynamic 3D gradient echo imaging after intracutaneous contrast injection to visualize lymphatic channels, and a delayed 3D gradient echo sequence after intravenous contrast to define veins. This article reviews the pathophysiology and microsurgical treatment of lymphedema, presents the imaging protocol used at our institution, and describes exam interpretation and the image postprocessing performed for surgical planning.

关键词： lymphedema MR lymphangiography lymphaticovenular anastomosis microsurgery image postprocessing breast cancer

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Diagnostic Imaging of Oral and Maxillofacial Anatomy and Pathology

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VETERINARY CLINICS OF NORTH AMERICA-SMALL ANIMAL PRACTICE 2022年第1期52卷 67-105页

作者： Villamizar-Martinez, Lenin A. Tsugawa, Anson J. North Carolina State Univ Dept Clin Sci Coll Vet Med 1060 William Moore Dr Raleigh NC 27607 USA Dog & Cat Dentist Inc 9599 Jefferson Blvd Culver City CA 90232 USA

This article describes the technical principles and indications for the most often encountered diagnostic imaging modalities in veterinary dentistry and oral surgery; with extensive coverage of intraoral (and extraoral) dental radiographic imaging and interpretation through detailed example figures of common dental and maxillofacial diseases in the dog and cat. Multidetector/multislice computed tomography (MDCT/MSCT) and emergent technologies such as cone-beam computed tomography (CBCT) are presented here in detail. Magnetic resonance imaging (MRI) and diagnostic ultrasound, which are used less frequently, are briefly discussed.

关键词： Intraoral radiography Dental digital imaging equipment image postprocessing Dental radiograph interpretation CT CBCT maxillofacial skeleton CBCT high spatial resolution Multiplanar reconstruction maxillofacial trauma 3D printing OMFS MRI TMJ articular disc Orbital ultrasound retrobulbar disease

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