Respiratory triggered imaging with an optical displacement sensor

Wilson, Stephen J.; Brereton, Ian M.; Hockings, Paul D.; Roffmann, Wolfgang U.; Doddrell, David M.

doi:10.1016/0730-725x(93)90221-x

Cited by 28 publications

(17 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Data acquisition was synchronized with the respiratory cycle of the free breathing rats, which were anaesthetized with iso urane as an alternative to the more hepatotoxic halothane (1-1.5%, 0.6-1 L/min), using a ber optic respiratory monitor (22). A segmented 3D fat suppressed inversion recovery snapshot readout sequence was used to determine liver volumes.…”

Section: Mr Imagingmentioning

confidence: 99%

Longitudinal Magnetic Resonance Imaging Quantitation of Rat Liver Regeneration After Partial Hepatectomy

et al. 2002

View full text Add to dashboard Cite

This report demonstrates the advantage s of using a noninvasive soft tissue imaging technique-magnetic resonance imaging (MRI)-to monitor liver regeneration after 70% partial hepatectomy in the rat in a longitudinal manner. Six animals were scanned prior to and on 6 subsequen t occasions up to 9 days after surgical removal of the median and left lateral lobes. Within the observed time frame liver volumes were restored to approximately 88% of presurgery values. The rate of regeneration was maximal at 1.5 days, which coincided with the maximum increase of Mitotic Index-a measure of cell proliferation, determined in a subsequen t study. Pre-and postpartial hepatectomy measurements remove two potentially confoundin g unknowns -the presurgery liver volume, and the amount of liver actually excised. 3D reconstruction s of the liver effectively illustrate the morphologica l changes associated with the procedure, and the regrowth of liver tissue.

show abstract

Section: Mr Imagingmentioning

confidence: 99%

Longitudinal Magnetic Resonance Imaging Quantitation of Rat Liver Regeneration After Partial Hepatectomy

et al. 2002

View full text Add to dashboard Cite

show abstract

“…Various approaches for respiratory motion sensing have been reported using direct or indirect detection methods. Direct detection methods sense motion using the ECG signal (13), or by impedance pneumographic (14), pneumatic (15), hydraulic (2), infrared (16), fiberoptic (10,(17)(18)(19), piezoelectric (20), or inductive sensors (21), respectively. Indirect detection methods use information in an additional MR signal as a basis for accepting or acquiring MR data in real time or in postprocessing (navigator technique (22,23)).…”

mentioning

confidence: 99%

Assessment of motion gating strategies for mouse magnetic resonance at high magnetic fields

Cassidy

Schneider

Grieve

et al. 2004

Magnetic Resonance Imaging

113

101

View full text Add to dashboard Cite

Purpose:To assess the performance of motion gating strategies for mouse cardiac magnetic resonance (MR) at high magnetic fields by quantifying the levels of motion artifact observed in images and spectra in vivo. Materials and Methods:MR imaging (MRI) of the heart, diaphragm, and liver; MR angiography of the aortic arch; and slice-selective 1 H-spectroscopy of the heart were performed on anesthetized C57Bl/6 mice at 11.75 T. Gating signals were derived using a custom-built physiological motion gating device, and the gating strategies considered were no gating, cardiac gating, conventional gating (i.e., blanking during respiration), automatic gating, and userdefined gating. Both automatic and user-defined modes used cardiac and respiratory gating with steady-state maintenance during respiration. Gating performance was assessed by quantifying the levels of motion artifact observed in images and the degree of amplitude and phase stability in spectra.Results: User-defined gating with steady-state maintenance during respiration gave the best performance for mouse cardiac imaging, angiography, and spectroscopy, with a threefold increase in signal intensity and a sixfold reduction in noise intensity compared to cardiac gating only. Conclusion:Physiological gating with steady-state maintenance during respiration is essential for mouse cardiac MR at high magnetic fields.

show abstract

“…Detection without contact, based on the infrared reflectometry principle has previously been characterized by Lemieux [9]. Different authors have used a dedicated bed to facilitate the non-invasive placement of an optical probe coupled to optical fibers for mice liver examination at 4.7T [10] and 7T [11]. The ease of use and low cost of the fiber-optic detector was further demonstrated on mouse liver by enabling respiratory-synchronized 1H MR Spectroscopy acquisition [12].…”

Section: Introductionmentioning

confidence: 99%

An Optical Fiber-Based Gating Device for Prospective Mouse Cardiac MRI

Sablong

Rengle

Ramgolam

et al. 2014

IEEE Trans. Biomed. Eng.

View full text Add to dashboard Cite

Abstract-Prospective synchronization of MRI acquisitions on living organisms involves the monitoring of respiratory and heart motions. The electrocardiogram (ECG) signal is conventionally used to measure the cardiac cycle. However, in some circumstances, obtaining an uncorrupted ECG signal recorded on small animals with RF pulses and gradient switching is challenging. To monitor respiratory motion, an air cushion associated with a pressure sensor is commonly used but the system suffers from bulkiness. For many applications, the physiological gating information can also be derived from an MR navigated-signal. However, a compact device that can simultaneously provide respiratory and cardiac information, for both prospective gating and physiological monitoring, is desirable. This is particularly valid since small volume coils or dedicated cardiac RF coil arrays placed directly against the chest wall are required to maximize measurement sensitivity. An optic-based device designed to synchronize MRI acquisitions on small animal's respiratory and heart motion was developed using a transmit-receive pair of optical fibers. The suitability of the developed device was assessed on mice (n=10) and was based on two sets of experiments with dual cardiac and respiratory synchronization. Images acquired with prospective triggering using the opticalbased signal, ECG and the pressure sensor during the same experiment were compared between themselves in the first set. The second set compared prospective technique using optical-based device and ECG to a retrospective technique. The optical signal which was correlated to both respiratory and heart motion was totally unaffected by radiofrequency pulses or currents induced by the magnetic field gradients used for imaging. Mice heart MR images depict low visible motion artifacts with all sensors or techniques used. No significant SNR differences were found between each series of image. Full fiber optic based signal derived from heart and respiratory motion was suitable for prospective triggering of heart MR imaging. The fiber optic device performed similarly to the ECG and air pressure sensors, while providing an advantage for imaging with dedicated cardiac array coils by reducing bulk. It can be an attractive alternative for small animal MRI in difficult environments such as limited space and strong gradient switching.

show abstract

Respiratory triggered imaging with an optical displacement sensor

Cited by 28 publications

References 7 publications

Longitudinal Magnetic Resonance Imaging Quantitation of Rat Liver Regeneration After Partial Hepatectomy

Longitudinal Magnetic Resonance Imaging Quantitation of Rat Liver Regeneration After Partial Hepatectomy

Assessment of motion gating strategies for mouse magnetic resonance at high magnetic fields

An Optical Fiber-Based Gating Device for Prospective Mouse Cardiac MRI

Contact Info

Product

Resources

About