Synthetic CT skull generation for transcranial MR imaging–guided focused ultrasound interventions with conditional adversarial networks

Liu, Han; Sigona, Michelle K.; Manuel, Thomas J.; Chen, Li Min; Caskey, Charles F.; Dawant, Benoît M.

doi:10.1117/12.2612946

Cited by 9 publications

(8 citation statements)

References 22 publications

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“…Vol 46 . In our future studies, we plan to incorporate skull CT along with Kranion to inform ourselves of focal shifts and account for aberration corrections in both in transmit and receive end.…”

Section: Discussionmentioning

confidence: 99%

Guiding and monitoring focused ultrasound mediated blood–brain barrier opening in rats using power Doppler imaging and passive acoustic mapping

Singh

Kusunose

Phipps

et al. 2022

Sci Rep

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The blood–brain barrier (BBB) prevents harmful toxins from entering brain but can also inhibit therapeutic molecules designed to treat neurodegenerative diseases. Focused ultrasound (FUS) combined with microbubbles can enhance permeability of BBB and is often performed under MRI guidance. We present an all-ultrasound system capable of targeting desired regions to open BBB with millimeter-scale accuracy in two dimensions based on Doppler images. We registered imaging coordinates to FUS coordinates with target registration error of 0.6 ± 0.3 mm and used the system to target microbubbles flowing in cellulose tube in two in vitro scenarios (agarose-embedded and through a rat skull), while receiving echoes on imaging transducer. We created passive acoustic maps from received echoes and found error between intended location in imaging plane and location of pixel with maximum intensity after passive acoustic maps reconstruction to be within 2 mm in 5/6 cases. We validated ultrasound-guided procedure in three in vivo rat brains by delivering MRI contrast agent to cortical regions of rat brains after BBB opening. Landmark-based registration of vascular maps created with MRI and Doppler ultrasound revealed BBB opening inside the intended focus with targeting accuracy within 1.5 mm. Combined use of power Doppler imaging with passive acoustic mapping demonstrates an ultrasound-based solution to guide focused ultrasound with high precision in rodents.

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Section: Discussionmentioning

confidence: 99%

Guiding and monitoring focused ultrasound mediated blood–brain barrier opening in rats using power Doppler imaging and passive acoustic mapping

Singh

Kusunose

Phipps

et al. 2022

Sci Rep

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“…As an extension of our previous work, 31 we adopted a 3D patch-based cGAN to generate a sCT skull image given a T1-weighted MRI. Our 3D cGAN consisted of a generator G and a discriminator D, where G was trained to generate realistic CT skulls to fool the discriminator and D was trained to classify the rCT and sCT skulls.…”

Section: Methodsmentioning

confidence: 99%

“…Built upon our previous work, 31 we perform more extensive experiments in this study to validate our developed technique from aspects of image similarity and acoustic simulations. For image similarity, we compare our cGAN-based method against another mainstream synthesis approach to demonstrate the superiority of our method for our application.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of synthetically generated computed tomography for use in transcranial focused ultrasound procedures

Liu,

Sigona,

Manuel

et al. 2023

J. Med. Imag.

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.PurposeTranscranial focused ultrasound (tFUS) is a therapeutic ultrasound method that focuses sound through the skull to a small region noninvasively and often under magnetic resonance imaging (MRI) guidance. CT imaging is used to estimate the acoustic properties that vary between individual skulls to enable effective focusing during tFUS procedures, exposing patients to potentially harmful radiation. A method to estimate acoustic parameters in the skull without the need for CT is desirable.ApproachWe synthesized CT images from routinely acquired T1-weighted MRI using a 3D patch-based conditional generative adversarial network and evaluated the performance of synthesized CT (sCT) images for treatment planning with tFUS. We compared the performance of sCT with real CT (rCT) images for tFUS planning using Kranion and simulations using the acoustic toolbox, k-Wave. Simulations were performed for 3 tFUS scenarios: (1) no aberration correction, (2) correction with phases calculated from Kranion, and (3) phase shifts calculated from time reversal.ResultsFrom Kranion, the skull density ratio, skull thickness, and number of active elements between rCT and sCT had Pearson’s correlation coefficients of 0.94, 0.92, and 0.98, respectively. Among 20 targets, differences in simulated peak pressure between rCT and sCT were largest without phase correction (12.4 % ± 8.1 % ) and smallest with Kranion phases (7.3 % ± 6.0 % ). The distance between peak focal locations between rCT and sCT was <1.3 mm for all simulation cases.ConclusionsReal and synthetically generated skulls had comparable image similarity, skull measurements, and acoustic simulation metrics. Our work demonstrated similar results for 10 testing cases comparing MR-sCTs and rCTs for tFUS planning. Source code and a docker image with the trained model are available at https://github.com/han-liu/SynCT_TcMRgFUS.

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“…The clinical method for targeting FUS is using MRI thermometry 26,32,46 . To target accurately and calculate FUS attenuation for transcranial applications, CT images of the skull are utilized 18,27 . Such targeting methods have been used towards blood brain barrier opening and neuromodulation procedures.…”

Section: In-vivo Harmonic Cranial B-mode Imagingmentioning

confidence: 99%

An all-ultrasound cranial imaging method to establish the relationship between cranial FUS incidence angle and transcranial attenuation in non-human primates in 3D

Singh

Jiménez-Gambín

Konofagou

2023

Preprint

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Focused ultrasound (FUS) is a non-invasive and non-ionizing technique which deploys ultrasound waves to induce bio-effects. When paired with acoustically active particles such as microbubbles (MBs), it can open the blood brain barrier (BBB) to facilitate drug delivery inhibited due to the presence of BBB. One of the parameters that affects the FUS beam propagation is the beam incidence angle on the skull. Prior work by our group has shown that, as incidence angles deviate from 900, FUS focal pressures attenuate and result to a smaller BBB opening volume. The incidence angles calculated in our prior studies were in 2D and used skull information from CT. The study presented herein develops methods to calculate incidence angle in 3D in non-human primate (NHP) skull fragments using harmonic ultrasound imaging without using ionizing radiation. Our results show that ultrasound harmonic imaging is capable of accurately depicting features such as sutures and eye-sockets of the skull. Furthermore, we were able to reproduce previously reported relationships between the incidence angle and FUS beam attenuation. We also show feasibility of performing ultrasound harmonic imaging in in-vivo non-human primates. The all-ultrasound method presented herein combined with our neuronavigation system stands to increase more widespread adoption of FUS and render it accessible by eliminating the need for CT cranial mapping.

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Synthetic CT skull generation for transcranial MR imaging–guided focused ultrasound interventions with conditional adversarial networks

Cited by 9 publications

References 22 publications

Guiding and monitoring focused ultrasound mediated blood–brain barrier opening in rats using power Doppler imaging and passive acoustic mapping

Guiding and monitoring focused ultrasound mediated blood–brain barrier opening in rats using power Doppler imaging and passive acoustic mapping

Evaluation of synthetically generated computed tomography for use in transcranial focused ultrasound procedures

An all-ultrasound cranial imaging method to establish the relationship between cranial FUS incidence angle and transcranial attenuation in non-human primates in 3D

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