Fast and accurate localization of multiple RF markers for tracking in MRI-guided interventions

Galassi, Francesca; Brujić, Djordje; Rea, Marc; Lambert, Nicholas; deSouza, Nandita M.; Ristić, M.

doi:10.1007/s10334-014-0446-3

Cited by 13 publications

(18 citation statements)

References 25 publications

(31 reference statements)

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“…Previous work indicated that the typical accuracy of the localization method is better than 0.3 voxels. If the markers are arranged in a known pattern such that they are not equidistant from each other, then the correspondence between identified marker positions in different volume images can be established automatically . Registration is then performed as a rigid‐body transformation that minimizes the sum of the squared distances between the corresponding marker points .…”

Section: Methodsmentioning

confidence: 99%

Detection of maturity and ligament injury using magic angle directional imaging

Chappell

Brujić

Straeten

et al. 2019

Magnetic Resonance in Med

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Purpose:To investigate whether magnetic field-related anisotropies of collagen may be correlated with postmortem findings in animal models. Methods: Optimized scan planning and new MRI data-processing methods were proposed and analyzed using Monte Carlo simulations. Six caprine and 10 canine knees were scanned at various orientations to the main magnetic field. Image intensities in segmented voxels were used to compute the orientation vectors of the collagen fibers. Vector field and tractography plots were computed. The Alignment Index was defined as a measure of orientation distribution. The knees were subsequently assessed by a specialist orthopedic veterinarian, who gave a pathological diagnosis after having dissected and photographed the joints. Results: Using 50% less scans than reported previously can lead to robust calculation of fiber orientations in the presence of noise, with much higher accuracy. The 6 caprine knees were found to range from very immature (< 3 months) to very mature (> 3 years). Mature specimens exhibited significantly more aligned collagen fibers in their patella tendons compared with the immature ones. In 2 of the 10 canine knees scanned, partial cranial caudal ligament tears were identified from MRI and subsequently confirmed with encouragingly high consistency of tractography, Alignment Index, and dissection results. Conclusion: This method can be used to detect injury such as partial ligament tears, and to visualize maturity-related changes in the collagen structure of tendons. It can provide the basis for new, noninvasive diagnostic tools in combination with new scanner configurations that allow less-restricted field orientations. K E Y W O R D Scollagen, magic angle effect, musculoskeletal imaging

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Section: Methodsmentioning

confidence: 99%

Detection of maturity and ligament injury using magic angle directional imaging

Chappell

Brujić

Straeten

et al. 2019

Magnetic Resonance in Med

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“…The prototype presented here makes use of semi-active markers localised using a tracking algorithm that employs 1D projections (Galassi et al, 2014). The method involves acquiring a set of 1D projections through excitation of the whole imaging volume.…”

Section: Robot Localisationmentioning

confidence: 99%

“…This setup simulates a fully inserted needle and amplifies position errors of θ 2 and θ 3 by a factor 5, corresponding to the ratio between adapter length l and distance t (1). The coordinates of the micro-coil in the reference frame F0 of the MR scanner were calculated using the tracking algorithm described in (Galassi et al, 2014). Initially the reference frame F1 was automatically registered with respect to the scanner frame F0 computing the position of 3 points with (2) and measuring the corresponding position of the micro-coil fiducial with the tracking algorithm.…”

Section: Robot Accuracymentioning

confidence: 99%

See 1 more Smart Citation

Design and control of 3-DOF needle positioner for MRI-guided laser ablation of liver tumours

Franco

Aurisicchio

Ristić

2015

IJBBR

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This article presents the design and control of a pneumatic needle positioner for laser ablation of liver tumours under guidance by Magnetic Resonance Imaging (MRI). The prototype was developed to provide accurate point-to-point remote positioning of a needle guide inside an MR scanner with the aim of evaluating the potential advantages over the manual procedure. In order to minimize alterations to the MR environment the system employs plastic pneumatic actuators and 9 m long supply lines connecting with the control hardware located outside the magnet room. An improved Sliding Mode Control (SMC) scheme was designed for the position control of the device. Wireless micro-coil fiducials are used for automatic registration in the reference frame of the MR scanner. The MRI-compatibility and the accuracy of the prototype are demonstrated with experiments in the MR scanner. Keywords: Medical Robotics; Pneumatic Systems; MRI; Sliding Mode ControlReference to this paper should be made as follows: Franco, E., Aurisicchio, M., Ristic, M. (2016) 'Design and control of 3-DOF needle positioner for MRI-guided laser ablation of liver tumours', Int.

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“…43 Caliber Clear Paintballs 8000, Rap4 UK). While fast and accurate tracking of semi-active markers was demonstrated in [50], a closer integration with the scanner was required. The main advantage of the approach presented here is its portability, since it does not rely on special imaging sequences, which would have to be reprogrammed for different MRI scanners.…”

Section: Robot Registrationmentioning

confidence: 99%