Toward real‐time availability of 3D temperature maps created with temporally constrained reconstruction

Todd, Nick; Prakash, Jaya; Odéen, Henrik; Bever, Josh de; Payne, Allison; Yalavarthy, Phaneendra K.; Parker, Dennis L.

doi:10.1002/mrm.24783

Cited by 36 publications

(39 citation statements)

References 27 publications

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“…26,38,40,44,46,47 A real-time TCR algorithm has been described, 59 in which the computation burden is reduced by only applying the TCR algorithm on a limited FOV. The limited FOV is achieved by cropping the image for TCR reconstruction in the directions in which k-space is fully sampled.…”

Section: Discussionmentioning

confidence: 99%

Sampling strategies for subsampled segmented EPI PRF thermometry in MR guided high intensity focused ultrasound

et al. 2014

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Purpose: To investigate k-space subsampling strategies to achieve fast, large field-of-view (FOV) temperature monitoring using segmented echo planar imaging (EPI) proton resonance frequency shift thermometry for MR guided high intensity focused ultrasound (MRgHIFU) applications. Methods: Five different k-space sampling approaches were investigated, varying sample spacing (equally vs nonequally spaced within the echo train), sampling density (variable sampling density in zero, one, and two dimensions), and utilizing sequential or centric sampling. Three of the schemes utilized sequential sampling with the sampling density varied in zero, one, and two dimensions, to investigate sampling the k-space center more frequently. Two of the schemes utilized centric sampling to acquire the k-space center with a longer echo time for improved phase measurements, and vary the sampling density in zero and two dimensions, respectively. Phantom experiments and a theoretical point spread function analysis were performed to investigate their performance. Variable density sampling in zero and two dimensions was also implemented in a non-EPI GRE pulse sequence for comparison. All subsampled data were reconstructed with a previously described temporally constrained reconstruction (TCR) algorithm. Results: The accuracy of each sampling strategy in measuring the temperature rise in the HIFU focal spot was measured in terms of the root-mean-square-error (RMSE) compared to fully sampled "truth." For the schemes utilizing sequential sampling, the accuracy was found to improve with the dimensionality of the variable density sampling, giving values of 0.65• C, 0.49 • C, and 0.35• C for density variation in zero, one, and two dimensions, respectively. The schemes utilizing centric sampling were found to underestimate the temperature rise, with RMSE values of 1.05• C and 1.31• C, for variable density sampling in zero and two dimensions, respectively. Similar subsampling schemes with variable density sampling implemented in zero and two dimensions in a non-EPI GRE pulse sequence both resulted in accurate temperature measurements (RMSE of 0.70• C and 0.63 • C, respectively). With sequential sampling in the described EPI implementation, temperature monitoring over a 192 × 144 × 135 mm 3 FOV with a temporal resolution of 3.6 s was achieved, while keeping the RMSE compared to fully sampled "truth" below 0.35• C. Conclusions: When segmented EPI readouts are used in conjunction with k-space subsampling for MR thermometry applications, sampling schemes with sequential sampling, with or without variable density sampling, obtain accurate phase and temperature measurements when using a TCR reconstruction algorithm. Improved temperature measurement accuracy can be achieved with variable density sampling. Centric sampling leads to phase bias, resulting in temperature underestimations.

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Section: Discussionmentioning

confidence: 99%

Sampling strategies for subsampled segmented EPI PRF thermometry in MR guided high intensity focused ultrasound

et al. 2014

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“…61 Available and accurate methods for retrospective reconstruction of the temperature maps useful in research settings were investigated. 62,63 A recent study by Ramsay et al 64 proposes to monitor temperature changes in the cortical bone using a short echo-time gradient echo sequence. The feasibility of using T 2 mapping to monitor the temperature change in subcutaneous adipose tissue layers was studied by Baron et al 59,65 Temperature monitoring and hyperthermic injury detection in fatty tissue was also tested by using X-ray CT during HIFU thermal treatment.…”

Section: Focused Ultrasound Mri and Musculoskeletal Tissues: Pros Anmentioning

confidence: 99%

MRI-guided focused ultrasound surgery in musculoskeletal diseases: the hot topics

Bazzocchi¹,

Napoli²,

Sacconi³

et al. 2016

BJR

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MRI-guided focused ultrasound surgery (MRgFUS) is a minimally invasive treatment guided by the most sophisticated imaging tool available in today's clinical practice. Both the imaging and therapeutic sides of the equipment are based on non-ionizing energy. This technique is a very promising option as potential treatment for several pathologies, including musculoskeletal (MSK) disorders. Apart from clinical applications, MRgFUS technology is the result of long, heavy and cumulative efforts exploring the effects of ultrasound on biological tissues and function, the generation of focused ultrasound and treatment monitoring by MRI. The aim of this article is to give an updated overview on a "new" interventional technique and on its applications for MSK and allied sciences

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“…The EKF employed the bio-heat transfer equation (BHTE) as the model predictor and dynamically adapts the model covariance in order to achieve measurement accuracy even in regions where the parameters of the BHTE are not exactly known. Alternatively, sparse sampling approaches in k-space have been proposed, which also exploit the physical knowledge of the heating process [26] to achieve offline an artefact free reconstruction of 3-D MR-temperature maps from under-sampled k-space data using sparse sampling approaches [27], [28].…”

Section: Introductionmentioning

confidence: 99%

Extended Kalman Filtering for Continuous Volumetric MR-Temperature Imaging

Senneville

Roujol

Hey

et al. 2013

IEEE Trans. Med. Imaging

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Real time magnetic resonance (MR) thermometry has evolved into the method of choice for the guidance of high-intensity focused ultrasound (HIFU) interventions. For this role, MR-thermometry should preferably have a high temporal and spatial resolution and allow observing the temperature over the entire targeted area and its vicinity with a high accuracy. In addition, the precision of real time MR-thermometry for therapy guidance is generally limited by the available signal-to-noise ratio (SNR) and the influence of physiological noise. MR-guided HIFU would benefit of the large coverage volumetric temperature maps, including characterization of volumetric heating trajectories as well as near- and far-field heating. In this paper, continuous volumetric MR-temperature monitoring was obtained as follows. The targeted area was continuously scanned during the heating process by a multi-slice sequence. Measured data and a priori knowledge of 3-D data derived from a forecast based on a physical model were combined using an extended Kalman filter (EKF). The proposed reconstruction improved the temperature measurement resolution and precision while maintaining guaranteed output accuracy. The method was evaluated experimentally ex vivo on a phantom, and in vivo on a porcine kidney, using HIFU heating. On the in vivo experiment, it allowed the reconstruction from a spatio-temporally under-sampled data set (with an update rate for each voxel of 1.143 s) to a 3-D dataset covering a field of view of 142.5×285×54 mm(3) with a voxel size of 3×3×6 mm(3) and a temporal resolution of 0.127 s. The method also provided noise reduction, while having a minimal impact on accuracy and latency.

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Toward real‐time availability of 3D temperature maps created with temporally constrained reconstruction

Cited by 36 publications

References 27 publications

Sampling strategies for subsampled segmented EPI PRF thermometry in MR guided high intensity focused ultrasound

Sampling strategies for subsampled segmented EPI PRF thermometry in MR guided high intensity focused ultrasound

MRI-guided focused ultrasound surgery in musculoskeletal diseases: the hot topics

Extended Kalman Filtering for Continuous Volumetric MR-Temperature Imaging

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