Motion compensation

2018 ◽  
pp. 26-33 ◽  
Author(s):  
Sebastian Kozerke ◽  
Redha Boubertakh ◽  
Marc Miquel
Keyword(s):  
Respiratory Gating ◽  
Pulse Sequences ◽  
Breath Holding ◽  
Cine Imaging ◽  
Single Shot ◽  
Breathing Motion ◽  
Retrospective Gating ◽  
Image Artefacts ◽  
Electrocardiogram Ecg ◽  
Space Acquisition

This chapter introduces the different methods used to synchronize pulse sequences with both cardiac and respiratory motions, to suppress motion-related blurring and image artefacts. A single frame or a series of images (cine imaging) can be acquired at different time points (cardiac phases) throughout the cardiac cycle by detecting the patient’s heart rate, usually by using an electrocardiogram (ECG) or, in case of poor ECG signals, a pulse oximeter signal. Fast single-shot and segmented k-space acquisition techniques are introduced, and for segmented cine imaging, both prospective and retrospective gating techniques are described. To suppress breathing motion artefacts, acquisitions use respiratory motion techniques. For short acquisition durations, breath-holding is the easiest method to stop the patient’s breathing during data collection. However, for long scans, respiratory gating or respiratory navigated techniques can be used. The principles of these techniques and their applications are presented.

Ultrasound-based sensors for respiratory motion assessment in multimodality PET imaging

2021 ◽  
Author(s):  
Bruno Madore ◽  
Gabriela Belsley ◽  
Cheng-Chieh Cheng ◽  
Frank Preiswerk ◽  
Marie Foley Kijewski ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Respiratory Gating ◽  
Sensitive Information ◽  
Internal Organs ◽  
Respiration Monitoring ◽  
Breathing Motion ◽  
Pet Ct ◽  
Motion Phantom ◽  
Motion Assessment

Abstract Breathing motion can displace internal organs by up to several cm; as such, it is a primary factor limiting image quality in medical imaging. Motion can also complicate matters when trying to fuse images from different modalities, acquired at different locations and/or on different days. Currently available devices for monitoring breathing motion often do so indirectly, by detecting changes in the outline of the torso rather than the internal motion itself, and these devices are often fixed to floors, ceilings or walls, and thus cannot accompany patients from one location to another. We have developed small ultrasound-based sensors, referred to as ‘organ configuration motion’ (OCM) sensors, that attach to the skin and provide rich motion-sensitive information. In the present work we tested the ability of OCM sensors to enable respiratory gating during in vivo PET imaging. A motion phantom involving an FDG solution was assembled, and two cancer patients scheduled for a clinical PET/CT exam were recruited for this study. OCM signals were used to help reconstruct phantom and in vivo data into time series of motion-resolved images. As expected, the motion-resolved images captured the underlying motion. In Patient #1, a single large lesion proved to be mostly stationary through the breathing cycle. However, in Patient #2, several small lesions were mobile during breathing, and our proposed new approach captured their breathing-related displacements. In summary, a relatively inexpensive hardware solution was developed here for respiration monitoring. Because the proposed sensors attach to the skin, as opposed to walls or ceilings, they can accompany patients from one procedure to the next, potentially allowing data gathered in different places and at different times to be combined and compared in ways that account for breathing motion.

Abstract 15240: Evaluation of the Performance and Safety of Wideband Cardiac MRI in Patients With a Cardiac Implantable Electronic Device (CIED)

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Sarah M Schwartz ◽  
Ashitha Pathrose ◽  
Ali Serhal ◽  
Ryan Avery ◽  
Ann Ragin ◽  
...  
Keyword(s):  
Image Quality ◽  
Electronic Device ◽  
Pulse Sequences ◽  
Free Breathing ◽  
Whole Body ◽  
Breath Hold ◽  
Single Shot ◽  
Before And After ◽  
Order Of Magnitude ◽  
Chest X Ray

Introduction: Wideband late gadolinium enhancement (LGE) CMR is capable of suppressing image artifacts induced by cardiac implanted electronic devices (CIEDs). We implemented our own wideband segmented (seg) breath-hold and wideband single-shot (SS) free-breathing LGE pulse sequences and used them clinically since 2016. The purpose of this study was to evaluate image quality and CMR safety of wideband LGE compared to standard LGE. Methods: We retrospectively identified 54 consecutive patients (mean age: 61±15 years; 31% females) with CIED (33 t-ICD, 4 s-ICD, 15 pacemaker, 1 CRT-D, 1 CRT-P) who underwent CMR at 1.5T (Avanto, Siemens). Standard seg, wideband seg, and wideband SS LGE used standard imaging parameters. 16 myocardial segments were scored for scar/myocardial conspicuity and presence of any visual artifact on a 5-point Likert scale (1:worst; 3:acceptable; 5:best). Distance between center of the heart and CIED (CXR D) was measured on chest X-ray. Whole-body specific absorption rate (SAR) was read from DICOM metadata. Device changes were calculated from pre- and post- device interrogation measurements. Results: Both wideband seg and SS LGE consistently produced better image quality than standard LGE (Figure 1A). Median conspicuity and artifact scores were significantly better for wideband seg (F=20.6, p<0.001) and wideband SS (F=24.2, p<0.001) LGE compared to standard LGE. There was a trend in conspicuity and artifact scores with CIED distance for standard LGE (rho=0.476, p=0.02), but not wideband LGE scans (Figure 1B, 1C). Whole-body SAR averaged for both wideband scans (0.15±0.04 W/kg) was one order of magnitude below the 2.0 W/kg FDA limit. Device parameters (sensing, impedance, threshold, battery level) did not differ before and after CMR including wideband LGE. Conclusions: Both wideband seg and SS LGE scans produced improved image quality compared to standard LGE while maintaining CMR safety. *The first two authors (SS and AP) contributed equally

scholarly journals Isotopically enhanced triple-quantum-dot qubit

2015 ◽  
Vol 1 (4) ◽  
pp. e1500214 ◽  
Author(s):  
Kevin Eng ◽  
Thaddeus D. Ladd ◽  
Aaron Smith ◽  
Matthew G. Borselli ◽  
Andrey A. Kiselev ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Coherent Control ◽  
Spin Echo ◽  
Pulse Sequences ◽  
Low Noise ◽  
Single Shot ◽  
Spin Qubit ◽  
Echo Type ◽  
Silicon Based ◽  
Long Pulse

Like modern microprocessors today, future processors of quantum information may be implemented using all-electrical control of silicon-based devices. A semiconductor spin qubit may be controlled without the use of magnetic fields by using three electrons in three tunnel-coupled quantum dots. Triple dots have previously been implemented in GaAs, but this material suffers from intrinsic nuclear magnetic noise. Reduction of this noise is possible by fabricating devices using isotopically purified silicon. We demonstrate universal coherent control of a triple-quantum-dot qubit implemented in an isotopically enhanced Si/SiGe heterostructure. Composite pulses are used to implement spin-echo type sequences, and differential charge sensing enables single-shot state readout. These experiments demonstrate sufficient control with sufficiently low noise to enable the long pulse sequences required for exchange-only two-qubit logic and randomized benchmarking.

Rapid Lumbar Spine MR Myelography: Imaging Findings Using a Single-Shot Technique

1997 ◽  
Vol 10 (2) ◽  
pp. 181-187 ◽  
Author(s):  
P. Demaerel ◽  
P. Van Hover ◽  
A. Broeders ◽  
B. Kiefer ◽  
A.L. Baert
Keyword(s):  
Spin Echo ◽  
Pulse Sequences ◽  
Three Dimensional ◽  
Projection Algorithm ◽  
Fast Spin Echo ◽  
Single Shot ◽  
Rapid Acquisition ◽  
Spin Echo Sequence ◽  
Echo Pulse ◽  
Mr Myelography

MR myelography has been performed by several authors. Most authors have used techniques based on three-dimensional gradient-echo pulse sequences or fast spin-echo pulse sequences. The examination time varied between 5 and 13 minutes and postprocessing with a maximum-intensity projection algorithm was necessary for three-dimensional visualization. The rapid acquisition with relaxation enhancement (RARE) was initially described by Hennig et Al. In this technical note we present our experience with a single-shot turbo spin-echo sequence, derived from RARE, of approximately 2 seconds to obtain one view. MR myelography can replace conventional myelography in all different types of pathology. In addition MR myelography provides additional information compared to MR imaging in a minority of the cases. Taking into account the ultra-rapid acquisition and the absence of postprocessing procedures, we recommended this technique in the appropriate clinical setting. The MR myelogram increases the level of conficence of the neuroradiologist.

scholarly journals Improved Workflow for Quantification of Right Ventricular Volumes Using Free-Breathing Motion Corrected Cine Imaging

2018 ◽  
Vol 40 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Anthony Merlocco ◽  
Laura Olivieri ◽  
Peter Kellman ◽  
Hui Xue ◽  
Russell Cross
Keyword(s):  
Right Ventricular ◽  
Free Breathing ◽  
Cine Imaging ◽  
Ventricular Volumes ◽  
Breathing Motion

Scan acceleration

2018 ◽  
pp. 14-16
Author(s):  
Sebastian Kozerke ◽  
Redha Boubertakh ◽  
Marc Miquel
Keyword(s):  
Magnetic Resonance ◽  
Cardiovascular Magnetic Resonance Imaging ◽  
Breath Holding ◽  
Magnetic Resonance Imaging Scan ◽  
Sampling Techniques ◽  
Critical Importance ◽  
Scan Time ◽  
Under Sampling ◽  
Image Artefacts ◽  
Resonance Imaging Scan

In cardiovascular magnetic resonance imaging, scan time is of critical importance, as many applications require breath-holding to suppress respiratory-related image artefacts. In this chapter, approaches to reduce scan time, while maintaining resolution, are described. Besides partial sampling of k-space, non-Cartesian k-space trajectories are introduced, followed by an overview of data under-sampling techniques as they are implemented on clinical magnetic resonance systems. Advantages and limitations of each of these methods are briefly described.

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