Basic principles of magnetic resonance imaging for beginner oral and maxillofacial radiologists

Kagawa, Toyohiro; Yoshida, Shoko; Shiraishi, T; Hashimoto, Marie; Inadomi, Daisuke; Sato, Mamoru; Tsuzuki, Takashi; Miwa, Kunihiro; Yuasa, Kenji

doi:10.1007/s11282-017-0274-z

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…The patient can choose the position of the seated side and the position of the decubitus side, as well as the clinical anesthesia area or sitting position. The selection of ultrasonic detection mainly depends on the depth of puncture target and the body shape of the patient, and the weight of the patient has been shown in many studies to be an important factor affecting the depth of thoracic puncture [ 19 ]. An ultrasonic probe with the appropriate frequency must be selected by the scanning site.…”

Section: Discussionmentioning

confidence: 99%

Ultrasound Images Guided under Deep Learning in the Anesthesia Effect of the Regional Nerve Block on Scapular Fracture Surgery

Liu

Cheng

2021

Journal of Healthcare Engineering

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In order to discuss the clinical characteristics of patients with scapular fracture, deep learning model was adopted in ultrasound images of patients to locate the anesthesia point of patients during scapular fracture surgery treated with the regional nerve block. 100 patients with scapular fracture who were hospitalized for emergency treatment in the hospital were recruited. Patients in the algorithm group used ultrasound-guided regional nerve block puncture, and patients in the control group used traditional body surface anatomy for anesthesia positioning. The ultrasound images of the scapula of the contrast group were used for the identification of the deep learning model and analysis of anesthesia acupuncture sites. The ultrasound images of the scapula anatomy of the patients in the contrast group were extracted, and the convolutional neural network model was employed for training and test. Moreover, the model performance was evaluated. It was found that the adoption of deep learning greatly improved the accuracy of the image. It took an average of 7.5 ± 2.07 minutes from the time the puncture needle touched the skin to the completion of the injection in the algorithm group (treated with artificial intelligence ultrasound positioning). The operation time of the control group (anatomical positioning) averaged 10.2 ± 2.62 min. Moreover, there was a significant difference between the two groups ( p < 0.05 ). The method adopted in the contrast group had high positioning accuracy and good anesthesia effect, and the patients had reduced postoperative complications of patients (all P < 0.005 ). The deep learning model can effectively improve the accuracy of ultrasound images and measure and assist the treatment of future clinical cases of scapular fractures. While improving medical efficiency, it can also accurately identify patient fractures, which has great adoption potential in improving the effect of surgical anesthesia.

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Section: Discussionmentioning

confidence: 99%

Ultrasound Images Guided under Deep Learning in the Anesthesia Effect of the Regional Nerve Block on Scapular Fracture Surgery

Liu

Cheng

2021

Journal of Healthcare Engineering

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“…Application of RF pulses causes misalignment of the protons from their original position. When the radio-frequency (RF) signal is switched off, the protons return back to their original position while emitting RF signals which are used to create the MR images [1]. Higher resolution in MRI-scanned images is obtained with an increase in signal-to-noise ratio (SNR) [2].…”

Section: Introductionmentioning

confidence: 99%

A non-linear triangular split-ring based metaresonator for targeted scanning at 1.5T MRI

Das¹

2023

Phys. Scr.

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In magnetic resonance imaging (MRI), RF signals are initially transmitted to stimulate the body protons which eventually release the electromagnetic energy while returning back to their original states. The image resolution and scanning efficiency of MRI can be improved by enhancing the magnetic fields received from the patient’s body using metamaterials. The major limitation of linear metamaterials is that they amplify RF magnetic fields both during transmission and reception phases. This requires modification of the RF excitation pulses during the transmission phase. Further, local increase of transmitted power poses a potential threat of tissue-heating and high specific absorption rate (SAR) values in addition to perturbing the transmit field homogeneity. In order to circumvent these problems, we propose a self-adaptive metasurface which has the capability of self-detuning itself during transmission of RF pulses during MRI scans. A triangular split-ring based metasurface is designed for maximum thirty-fold SNR improvement in 1.5T MRI. Switching diodes have been employed for switching on and off the magnetic field enhancement by the metasurface. During transmission phase when the switching diodes get turned on, the metasurface is detuned. During reception phase when the switching diodes get turned off, the metasurface is tuned to 63.8 MHz which is the Larmor frequency of 1.5T MRI. The proposed metasurface is thin and compact which enables its easy placement in the multi-element arrays of clinical MRI.

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“…MRI provides higher contrast in the images of soft tissues such as fat, muscle, brain cells, ligaments, and tendons as compared with other diagnostic imaging technologies 4 – 6 . Moreover, MR images are acquired without any ionizing radiation, thus keeping patients safe from the harmful effects of radiation 7 – 9 .…”

Section: Introductionmentioning

confidence: 99%

Compact bunker shielding assessment for 1.5 T MR-Linac

Sung

Choi

Kim

et al. 2022

Sci Rep

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This study evaluated the effect of the 1.5 T magnetic field of the magnetic resonance-guided linear accelerator (MR-Linac) on the radiation leakage doses penetrating the bunker radiation shielding wall. The evaluated 1.5 T MR-Linac Unity system has a bunker of the minimum recommended size. Unlike a conventional Linac, both primary beam transmission and secondary beam leakage were considered independently in the design and defined at the machine boundary away from the isocenter. Moreover, additional shielding was designed considering the numerous ducts between the treatment room and other rooms. The Linac shielding was evaluated by measuring the leakage doses at several locations. The intrinsic vibration and magnetic field were inspected at the proposed isocenter of the system. For verification, leakage doses were measured before and after applying the magnetic field. The intrinsic vibration and magnetic field readings were below the permitted limit. The leakage dose (0.05–12.2 µSv/week) also complied with internationally stipulated limits. The special shielding achieved a five-fold reduction in leakage dose. Applying the magnetic field increased the leakage dose by 0.12 to 4.56 µSv/week in several measurement points, although these values fall within experimental uncertainty. Thus, the effect of the magnetic field on the leakage dose could not be ascertained.

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Basic principles of magnetic resonance imaging for beginner oral and maxillofacial radiologists

Cited by 6 publications

References 17 publications

Ultrasound Images Guided under Deep Learning in the Anesthesia Effect of the Regional Nerve Block on Scapular Fracture Surgery

Ultrasound Images Guided under Deep Learning in the Anesthesia Effect of the Regional Nerve Block on Scapular Fracture Surgery

A non-linear triangular split-ring based metaresonator for targeted scanning at 1.5T MRI

Compact bunker shielding assessment for 1.5 T MR-Linac

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