This paper reviews the basic principles and calculation methods of MR specific absorption rate, discusses the clinical application of MR specific absorption rate.
Humans ; Magnetic Resonance Imaging ; Radio Waves

In this article, an introduction is given on the structure of RF subsystem, its main parameters and impact on the performance of MRI and RF techniques and its development. Furthermore, pivotal parameters provided by different suppliers are quoted and compared in functionality aspect.
Magnetic Resonance Imaging ; instrumentation ; methods ; Radio Waves

Persistent light reaction, actinic reticuloid, photosensitive eczema are three chronic photodermatoses with a feature of clinical, histological, and photobiologieal characteristics in common. These conditions were given the name of chronic persistent photosensitivity. Chronic persistent photosensitivity with the feature of photosensitive eczema developed in a 68-year-old male patient who had experienced persisited dermatitis. On phototesting the patient showed extremely severe photosensitivity to the short wave UVB. A skin biopsy showed microscopic finding of eczematous dermatitis.
Actins ; Aged ; Biopsy ; Dermatitis ; Eczema ; Humans ; Male ; Radio Waves ; Skin

In this paper, an overview is given on the optimization methods of designing RF coil array. Advantages and disadvantages are also discussed.
Equipment Design ; Magnetic Resonance Imaging ; instrumentation ; methods ; Radio Waves

Aiming at the increasing application of RFID technology in the medical environment, this study introduces the foreign requirements for RFID immunity test of medical devices, compares them with the current immunity test requirements of medical devices in China, and puts forward the necessity of establishing relevant test specifications in China.
Radio Frequency Identification Device ; Electromagnetic Fields ; Radio Waves ; Equipment Safety ; Technology

Radio frequency identification sensor network, which is a product of integrating radio frequency identification (RFID) with wireless sensor network (WSN), is introduced in this paper. The principle of radio frequency identification sensor is analyzed, and the importance of the antenna is emphasized. Then three kinds of common antennae, namely coil antenna, dipole antenna and microstrip antenna, are discussed. Subsequently, according to requirement, we have designed a microstrip antenna in a wireless temperature-monitoring and controlling system. The measurement of factual effect showed the requirement was fulfilled.
Body Temperature ; Computer Communication Networks ; Humans ; Monitoring, Physiologic ; instrumentation ; Radio Frequency Identification Device ; methods ; Radio Waves ; Telemetry ; instrumentation ; methods ; Transducers

The technique of anterolateral cordotomy for relief of pain was first performed by Spiller and Martin (1912). It was accepted as the best available method for long-term relief despite its disadvantages. It has been well documented that the procedure often caused weakness of an extremity or the loss of sphincter control and respietory impairment associated with high surgical cervical cordotomy. In 1963, Mullan et al. devised an approach to the cervical spinal cord by inserting a needle through the neck under roentgenologic control. They introduced a radioactive needle (Strontium90) to produce a lesion interrupting the lateral spinothalamic tract. Mullan and Rosomoff et al. (1965) later simplified the produce by using an electrical current to produce the lesion. The percutaneous method has considerable advantages. The mortality and morbidity are very small and the technique can be used on any patient including even the terminal state. If the required level is not attained on the first attempt, or if the level subsequently drops, the procedure is easily repeated. Most patients can be discharged early after this type of cordotomy. Authors have reviewed 46 cordotomies on 35 patients with intractable pain carried out by the percutaneous radiofrequency procedure at the Neurosurgery Department of Yonsei University from 1972 to 1975:36 cases were treated by a modification of the Rosomoffs technique, 10 cases by Lin's technique. Intractable pain has been a continuing problem in neurosurgery and many methods have been employed in its treatment. The function of lateral spinothalamic tract was described by Spiller and Martin in 1912. and they described the posterior approach to the spinal cord which has been widely used for cordotomy in the 50 years since. However, in elderly or debilitated patients, this method has proved to have many complications and is poorly tolerated and has a morbidity and mortality rate. In 1963, Sean Mullan, using a Strontium90 electrode accomplished a lateral spinothalamic cordotomy by stereotaxic surgery under local anesthesia (Mullan, et al., 1963; 1965; 1965). Later, in 1965, Rosomoff (Rosomoff,et al., 1965; Rosomoff, et al., 1966) developed an improved technique using UHF radio waves, which achieved wide popularity. Using radiological equipment and measuring the impedance of various portions of the spinal cord with electrodes, the exact area of the lateral spinothalamic tract to be destroyed could be located. Utilizing localizing electrodes and the above method, complications from destruction of the tracts near the lateral spinothalamic tract which formerly resulted in hemiparesis, respiratory difficulty, urinary difficulties and other surgical difficulties could be minimized much more effectively than with open surgical approaches (Mullan and Hosobuchi, 1968). In bilateral, high cervical cordotomy the complication of sleep induced apnea may be a cause of death. Belmusto (Belmusto, et al., 1963; Belmusto; et al., 1965) indicated that the respiratory fibers are very near the lateral spinothalamic tract in the C-1 to C-3 spinal region. The respiratory fibers are located in the anterior one fourth of the spinal cord, extending from the median fissure 3~3.5 mm lateral wards towards the region of the median part of the lateral spinothalamic tract. (Mullan and Mosobuchi, 1968; Nathan, 1963; Hitchcock and Lee ce, 1967; Crosby, et al., 1962). In 1966, Lin (Lin, et al., 1966), developed a low cervical anterior approach, in order to avoid damage to the respiratory tract, and found that respiratory tract damage was actually decreased, and also found that regional analgesia was easily accomplished. Over the last three years, the authors, applying a percutaneous cervical cordotomy technique, have studied 46 patients, recording the present illness, method of surgery, postoperative analgesic area and its change with time, and complications. This material was analyzed and conclusions drawn.
Adult ; Aged ; Cordotomy/methods* ; Female ; Human ; Male ; Middle Age ; Pain, Intractable/surgery* ; Radio Waves*

In the design of RF receiver of the digital MRI spectrometer console, a digital demodulation and filtering algorithm is presented in this thesis. The MR signals are firstly converted to digital signals by the A/D converter, and then quadrature-demodulated from high frequency carrier wave. The CIC filter, half-band filter and linear phase FIR filter are designed to process the cascaded filtering and decimation of the demodulated signals. This method achieves a satisfying processing speed and filtering effect, and also reduces the data size obviously. The experiment based on the permanent magnetism resonance imaging system proves its effectiveness and practicability.
Algorithms ; Magnetic Resonance Imaging ; instrumentation ; methods ; Radio Waves ; Signal Processing, Computer-Assisted ; instrumentation ; Software

The objective of this article is to research magnetic resonance compatibility for coronary mental stents, and to evaluate the magnetic resonance compatibility based on laboratory testing results. Coronary stents magnetic resonance compatibility test includes magnetically induced displacement force test, magnetically induced torque test, radio frequency induced heating and evaluation of MR image. By magnetic displacement force and torque values, temperature, and image distortion values to determine metal coronary stent demagnetization effect. The methods can be applied to test magnetic resonance compatibility for coronary mental stents and evaluate its demagnetization effect.
Equipment Design ; Magnetic Resonance Imaging ; Magnetics ; Metals ; Radio Waves ; Stents ; standards ; Temperature ; Torque

OBJECTIVETo compare the safety, feasibility, and efficacy of a completely nonfluoroscopic approach to radiofrequency catheter ablation (RFCA) using CARTO3 and ablation with conventional fluoroscopic guidance for treatment of idiopathic premature ventricular contractions from the aortic sinus cusp (ASC-PVCs).

METHODSFrom April 2013 to October 2015, we prospectively enrolled 52 consecutive patients with ASC-PVCs scheduled for either CARTO3 mapping-guided zero-fluoroscopy ablation (group A, n=23) or conventional fluoroscopic ablation (group B, n=29). The success rates, rates of complications, rates of recurrences, number of radiofrequency applications, procedure time, mapping time and fluoroscopy time were compared between the 2 groups.

RESULTSs No significant differences were found in the success rates between the 2 groups [22/23 (96%) vs 24/29 (83%), P=0.21]. No major complications occurred during the procedures in either group. There was no significant difference with regard to the procedure time between the two groups (79.6∓8.8 vs 77.4∓7.2 min, P=0.332). The procedure was completed without any fluoroscopy use in group A, while the mean fluoroscopy time in group B was 23.1∓6.0 min. Group A showed a shorter mapping time than group B (4.3∓1.7 vs 7.8∓2.6 min, P<0.01) with significantly fewer radiofrequency applications (4.8∓1.1 vs 7.9∓3.2, P<0.01). The recurrence rates were comparable between the two groups over a follow-up period of 5 to 20 months.

CONCLUSIONCompared with the conventional fluoroscopic technique, the zero-fluoroscopy approach can shorten the total procedure time and the ablation time with significantly reduced RF applications to eliminate ionizing radiation exposure in RFCA. RFCA guided by CARTO3 system without fluoroscopy is feasible, safe, and effective for treatment of ASC-PVCs.

Catheter Ablation ; Fluoroscopy ; Humans ; Radio Waves ; Recurrence ; Sinus of Valsalva ; physiopathology ; Treatment Outcome ; Ventricular Premature Complexes ; surgery