Abstract
ObjectiveMagnetic resonance-guided focused ultrasound (MRgFUS) is a minimum-invasive surgical approach to non-incisionally cause the thermos-coagulation inside the human brain. The skull score (SS) has already been approved as one of the most dominant factors related to a successful MRgFUS treatment. In this study, we first reveal the SS distribution of the tremor patients, and correlate the SS with the image feature from customized skull density ratio (cSDR). This correlation might give a direction to future clinical studies for improving the SS.MethodsTwo hundred and forty-six patients received a computed tomography (CT) scan of the brain, and a bone-enhanced filter was applied and reconstructed to a high spatial resolution CT images. The SS of all patients would be estimated by the MRgFUS system after importing the reconstructed CT images into the MRgFUS system. The histogram and the cumulative distribution of the SS from all the patients were calculated to show the percentage of the patients whose SS lower than 0.3 and 0.4. The same CT images of all patients were utilized to calculated the cSDR by first segmented the trabecular bone and the cortical bone from the CT images and divided the average trabecular bone intensity (aTBI) by the average cortical bone intensity (aCBI). The Pearson’s correlations between the SS and the cSDR, aTBI, and the aCBI were calculated, respectively.ResultsThere were 19.19 and 50% of the patient who had the SS lower than the empirical threshold 0.3 and 0.4, respectively. The Pearson’s correlation between the SS and the cSDR, aCBI, and the aTBI were R = 0.8145, 0.5723, and 0.8842.ConclusionHalf of the patients were eligible for the MRgFUS thalamotomy based on the SS, and nearly 20% of patients were empirically difficult to achieve a therapeutic temperature during MRgFUS. The SS and our cSDR are highly correlated, and the SS had a higher correlation with aTBI than with aCBI. This is the first report to explicitly reveal the SS population and indicate a potential way to increase the chance to achieve a therapeutic temperature for those who originally have low SS.
Highlights
High intensity focused ultrasound (HIFU) is an incisionless surgical device that has been widely used in medical research and clinical trials including the treatment of tumors (Kennedy, 2005) such as the liver (Kennedy et al, 2004; Illing et al, 2005), and kidney for over 50 years (Kennedy et al, 2003)
One of the important keys to these successes was the phase aberration correction (Fry and Barger, 1978; Sun and Hynynen, 1998; Hynynen et al, 2004) across thousands of the ultrasound beams when passing through the skull (Chang et al, 2016; Jung et al, 2019) that produce a constructive focusing at the target area which maximize the energy-heat efficiency without causing any thermal coagulation outside the target
The skull score (SS), which is offered by the InSightec, directly correlated with the temperature efficiency in the magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy (Chang et al, 2016), and the empirical criterion of the SS for the MRgFUS thalamotomy is 0.40 (Wang et al, 2018)
Summary
MATERIALS AND METHODSHigh intensity focused ultrasound (HIFU) is an incisionless surgical device that has been widely used in medical research and clinical trials including the treatment of tumors (Kennedy, 2005) such as the liver (Kennedy et al, 2004; Illing et al, 2005), and kidney for over 50 years (Kennedy et al, 2003). Sharing similar principles of the HIFU, recently the transcranial magnetic resonance-guided focused ultrasound (MRgFUS) has been widely used in different clinical trials to treat various neurological disorders in the human brain (Elias et al, 2016; Leinenga et al, 2016). One of the important keys to these successes was the phase aberration correction (Fry and Barger, 1978; Sun and Hynynen, 1998; Hynynen et al, 2004) across thousands of the ultrasound beams when passing through the skull (Chang et al, 2016; Jung et al, 2019) that produce a constructive focusing at the target area which maximize the energy-heat efficiency without causing any thermal coagulation outside the target. No literature was reported regarding the percentage of patients who can feasibly receive MRgFUS thalamotomy under this empirical criterion
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