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 non-cyanoptic, yellow colored posterior chamber intraocular lens (UVCY-IOL, HOYA, Japan) was specially designed to reduce the penetration of ultraviolet (UV) and short wave length visible light(400-500 nm) by adding yellow coloring dye(monomethin) for the pervention of aphakic or pseudophakic cyanopsia, and the obtaining closer color sensitivity and contrast sensitivity to the normal phakic eyes. In this study, we implanted both yellow colored IOLs in 16 eyes and conventional clear UV absorbing IOLs in 12 eyes. They were prospectively followed up for 6 months with questionairs asking subjective symptoms and with contrast s~nsitivity test in order to evaluate the color sensitivity and contrast sensitivity. The subjective symptoms of cyanopsia, photophobia, and glare were signi ficantly reduced in the UVCY-IOL group comparing to the conventional UVAB-IOL group. But in few cases of UVCY-IOL implantation(18.8%) were in episode transiently on xanthopsia with some dim state in early postop periods. The contrast sensitivity pattern of UVCY-IOL group was very similar to that of normal phakic group. The decrement of contrast sensitivity was less in UVCY-IOL group than in conventional UVAB-PCL group. The amount of decreased contrast sensitivity of UVCY-IOL group in scotopic condition was similar to that of conventional UVAB-IOL group. The result of this study suggests that yellow colored IOL is effective in decre asing cyanopsia and photophobia and in improving contrast sensitivity after cataract surgery especially in the early postoperative period. And also we recommend patients would receive UVCY-IOL implantations in both eyes if you have cataract on both eyes.
Cataract ; Contrast Sensitivity ; Glare ; Humans ; Lenses, Intraocular ; Photophobia ; Postoperative Period ; Prospective Studies ; Radio Waves

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*

OBJECTIVETo investigate the feasibility and effectiveness of radiofrequency catheter ablation (RFCA) to treat per-manent atrial fibrillation (AF) under the guidance of Carto-Merge technique.

METHODSFifteen male patients with permanent AF underwent RFCA under the guidance of Carto-Merge technique. The mean age was 54.00 +/- 10.44 years, and duration of AF was 23.66 +/- 14.93 months. Cardiac magnetic resonance angiography (MRA) was performed to obtain pre-procedural three-dimensional (3D) images on the anatomy of left atrium (LA) and pulmonary veins (PVs) before RFCA procedure. Then the electroanatomical map was integrated with 3D images of MRA to form Carto-Merge map that guided step-by-step ablation strategy of permanent AF. Circumferential PV ablation was performed first until complete PVs electric isolation confirmed by Lasso catheter. If AF was not terminated, lesion lines on roof of LA, mitral isthmus, and tricuspid isthmus were produced.

RESULTSThe episodes of AF were terminated during RFCA in 2 patients, by direct current cardioversion in the remaining 13 patients. Transient AF occurred in 2 patients after ablation on 1st day and 1st week respectively, AF terminated spontaneously not long after taking metoprolol. One patient developed persistent atrial flutter (AFL) in 2 months after procedure and AFL was eliminated by the second ablation. Persistent AF recurred on 1st day, 1st and 5th week respectively in 3 patients, and did not terminate after 3 months even though amiodarone was given. The remaining 12 patients were all free of AF during 2-11 months of follow-up. The recent success rate for RFCA of permanent AF was 80%.

CONCLUSIONSCarto-Merge technique can effectively guide RFCA of permanent AF. When combined with single Lasso mapping, it can simplify the mapping, lower expenses, and enhance the success rate of RFCA of permanent AF.

In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.
Animals ; Magnetic Fields ; Magnetic Resonance Imaging ; instrumentation ; Magnets ; Mice ; Mice, Nude ; Phantoms, Imaging ; Radio Waves ; Rats