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Magnetic Resonance Procedures: Summary of Bioeffects and Safety Research 1985 to 1996
Magnetic Resonance Procedures: Summary of Bioeffects and Safety Research 1997 to 1999

Magnetic Resonance Procedures: Summary of Bioeffects and Safety Research 1985 to 1996

Study description	Summary Results	Reference
1.5 T -simulated imaging conditions -human subjects -studied RF power levels equivalent to an SAR of 3 W/kg for 20 minutes	"Examinations on patients without thermoregulatory impairment can be carried out safely up to at least this SAR level (3 W/kg)".	Abart et al. (1)
-mathematic modeling of thermoregulatory responses	"Assuming a criterion elevation in deep body temperature of 0.6 degrees C, Ta = 20 degrees C and v = 0.8 m/sec, a 70 kg patient could undergo an NMR exposure of infinite duration at SAR < 5 W/kg".	Adair et al. (2)
-mathematic modeling of thermoregulatory responses with an emphasis on cardiovascular impairment	"Under conditions that are desirable in the clinic (Ta = 20 degrees C, 50% RH, still air), moderate restrictions (up to 67%) of SkBF yield tolerable increases in core temperature (TCO < 1 degree C) during NMR exposures (SAR < 4 W/kg of 40 minutes or less".	Adair et al. (3)
2.0 T -clinical imaging conditions -rats studied effect of MRI on blood-brain barrier permeability	"no MRI-induced difference was detected"	Adzamil et al. (4)
-mathematic modeling of thermoregulatory responses	"The model suggests that current practices in MR imaging will not cause a temperature rise in the center of small unperfused regions such as the eye of more than 1 degrees C".	Athey (5)
1.5 T -exposure to RF radiation in excess of clinical imaging conditions -sheep -studied RF radiation induced heating	"For exposure periods in excess of standard clinical imaging protocols the temperature increase was insufficient to cause adverse thermal effects."	Barber et al. (6)
0.5 and 1.5 T -clinical imaging conditions -human subjects -studied effect of MRI on the EEG and evaluated neuropsychological status	"no measurable influence of MRI on cognitive functions"	Bartels et al. (7)
0.04 T -clinical imaging conditions -human subjects -studied effects of MRI on cognition	"MRI did not cause any cognitive deterioration"	Besson et al. (8)
1.6 T -quenched magnet -pig -studied effect of quenching a magnet	"our findings, which in the circumstances of this experiment, suggested that the risks are small"	Bore et al. (9)
MRI gradient induced electric fields -dogs -studied bioeffects at high MRI gradientinduced fields	"as the strength of MRI gradient-induced fields increases, biological effects in order of increasing field and severity include stimulation of peripheral nerves, nerves of respiration and finally, the heart"	Bourland et al. (10)
1.5 T -clinical imaging conditions -human subjects -studied memory loss	"No gross or subtle memory changes could be attributed to MR imaging, because control groups showed similar patterns of memory loss."	Brockway and Beam (11)
0.38 T -static magnetic field only -deoxygenated erythrocytes -studied orientation of sickle erythrocytes	"further studies are needed to assess possible hazards of MRI of sickle cell disease"	Brody et al. (12)
0.35 and 1.5 T -clinical imaging conditions -human subjects with sickle cell disease -studied effects of MRI on patients with sickle cell disease	"no change in sickle cell blood flow during MR imaging in vivo"	Brody et al. (13)
0.35 T -clinical imaging conditions -human subjects -studied effects of noise during MRI on hearing	"noise generated by MR imaging may cause temporary hearing loss, and earplugs can prevent this"	Brummet et al. (14)
-varying gradient fields -humans -studied neural stimulation threshold with varying oscillations and gradient field strength	"the threshold decreases with the number of oscillations and increases with frequency. The repeatable threshold of 63 T/s (1270 Hz) remains constant from 32 oscillations (25.6 msec) to 128 oscillations (102.4 msec)"	Budinger et al. (15)
60 T/sec for 1.2-kHz sinusoids	"Assuming a 0.03-m radius current loop in the heart, 1,600 T/s corresponds to an induced electric field of 24 V/m. This field is approximately four times greater than that expected to cause perceptible sensation in the human torso".	Budinger et al. (16)
0.15 T -stimulated imaging conditions -HL60 promyelocytic cells -studied effect of MRI of Ca++	"results demonstrate that timevarying magnetic fields associated with MRI procedures increase Ca++"	Carson et al. (17)
-gradient magnetic fields up to 66 T/sec in dogs and 61 T/sec in humans -dogs -human subjects studied physiologic responses to large amplitude time-varying magnetic fields	dogs-"no motion, twitch, or ECG abnormalities" humans- "brief minimal muscular twitches observed on various parts of the body due to magnetic stimulation"	Cohen et al. (18)
0.5 and 1.0 T -simulated imaging conditions -cultured human blood cells -studied effect of static magnetic fields and line scan imaging on human blood cells	"neither treatment had any significant effect on any of the parameters measured"	Cooke and Morris (19)
4.7 T -exposures to static and RF electromagnetic fields only -isolated rabbit hearts -studied effects on cardiac excitability and vulnerability	no measurable effect on strength interval relationship or ventricular vulnerability	Doherty et al. (20)
-gradient magnetic fields only -sinusoidal gradients at a frequency of 1.25 kHz with amplitudes up to 40 mT/min for a z coil and 25 mT/min for an x coil -human subjects studied physiologic effects, physiologic responses	observed peripheral muscle stimulation, no extrasystoles or arrhythmias	Fischer (21)
0.3, 0.5, 1.5 T -stimulated imaging conditions and static/RF and gradient fields separately -rats -studied blood-brain barrier permeability	"increased brain mannitol associated with gradient fluid flux may reflect increase blood-brain barrier permeability or blood volume in brain"	Garber et al. (22)
2.2 to 2.7 T -simulated imaging conditions -mouse cells -studied oncogenic and genotoxic effects of MRI	"data clearly mitigate against an association between exposure to MR imaging modalities and both carcinogenic and genotoxic effects"	Geard et al. (23)
60 T/sec -gradient magnetic fields only -human subjects -studied effects of gradient magnetic fields on cardiac and respiratory function	"no changes were observed"	Gore et al. (24)
-mathematic modeling of rates of RF energy absorption	"fair to good agreement was found between SAR and those predicted by simple phenomenological models"	Grandolfo et al. (25)
0.1 to 1.5 T -static magnetic field only -human subjects -studied effects of static magnetic fields on temperature	temperatures increased or decreased depending on field strength of magnet	Gremmel et al. (26)
2.11 T -static magnetic field only -isolated rat hearts -studied effect of static magnetic field on cardiac muscle contraction	"static magnetic fields used in NMR imaging do not constitute any hazard in terms of cardiac contractility"	Gulch and Lutz (27)
2.0 T -RF at 90 MHz -simulated imaging conditions -phantom -Caphuchin monkey -studied temperature changes in phantom and monkey brain during high RF power exposures	"blood flowing through the brain used the body as a heat sink"	Hammer et al. (28)
0.35 T -simulated imaging conditions -mice -studied teratogenic effects of MRI	"prolonged midgestional exposure failed to reveal any overt embryotoxicity or teratogenicity" "slight but significant reduction in fetal crown-rump length after prolonged exposure justifies further study of higher MRI energy levels"	Heinrichs et al. (29)
1.5 T -static magnetic field only -human subjects -studied effect of static magnetic field on somatosensory evoked potentials	"short-term exposure to 1.5 T static magnetic field does not effect SEPs in human subjects"	Hong and Shellock (30)
0.15 T -simulated imaging conditions -rats -studied effects on cognitive processes	"MRI procedure has no significant effect on spatial memory processes in rats"	Innis et al. (31)
2.0 T -static magnetic field only -human subjects -studied effect of static magnetic field on cardiac rhythm	cardiac cycle length was significantly increased but this is probably harmless in normal subjects, safety in dysrrhythmic patients remains to be determined	Jehenson et al. (32)
-survey of thermal injuries/incidents related to MR procedures	"The increasing incidence of such clinical MR-related reports of patient burns in conjunction with the ever-increasing number of MR sites, examinations, and applications (e.g., MRA) strongly indicate the need for increased physician awareness and education concerning this rare, but real, MR-related potential hazard"	Kanal et al. (33)
1.5 T -simulated imaging conditions -frog embryo -studied effect of MRI on embryogenesis	"no adverse effects of MRI components on development of this vertebrate (Xenopus laevis)"	Kay et al. (34)
2.3, 4.7, & 10 T -static magnetic fields only -physiologic solutions (2.3 & 4.7 T) and mathematic modeling (10 T) -studied hydrostatic pressure and electrical potentials across vessels in presence of static magnetic fields	"A 10-T magnetic field changes vascular pressure in a model of the human vasculature by less than 0.2%"	Keltner et al. (35)
1.5 T -clinical imaging conditions -human subjects -studied physiologic changes during high field strength MRI	"temperature changes and other physiologic changes were small and of no clinical concern"	Kido et al. (36)
1.5 T -simulated imaging conditions -rats -studied effects of MRI on receptor-mediated activation of pineal gland indole biosynthesis	"strong magnetic fields and/or radiofrequency pulsing used in MRI inhibited beta-adrenergic activation of the gland"	LaPorte et al. (37)
1.0 and 1.5 T -clinical imaging conditions -human subjects -studied acoustic noise	"...many sequences produce noise levels above the safe levels defined by Department of Health and the Health and Safety Executive."	McJury (38)
1.5 T -clinical imaging conditions -human subjects -studied acoustic noise	"...for certain protocols, the exposure to acoustic noise falls outside safety guidelines unless ear protection is used."	McJury et al. (39)
3.5 to 12 kT/s -gradient magnetic fields only -mice -studied effect of gradient magnetic fields on pregnancy and post-natal development	"no significant difference between the litter numbers and growth rates of the exposed litters compared with controls"	McRobbie and Foster (40)
-various strong magnetic field -gradient magnetic fields only anesthetized rats -studied cardiac response to gradient magnetic fields	"the types of pulsed magnetic magnetic fields used in the present study did not affect the cardiac cycle of anesthetized rats"	McRobbie and Foster (41)
1.89 T -simulated imaging sequence -rats -studied taste aversion in rats to evaluate possible toxic effects of MRI	"rats exposed to MRI did not display any aversion to the saccharin solution"	Messmer et al. (42)
1.89 T -simulated imaging sequence -mouse spleen cells -studied possible interaction between ionizing radiation and MRI on damage to normal tissue	"for the normal tissues studied, MR imaging neither increases radiation damage nor inhibits repair"	Montour et al. (43)
0 to 2.0 T -clinical imaging conditions -human subjects -studied the extent of changes of the brainstem evoked potentials with MRI	"routine MRI examinations do not produce pathological changes in auditory evoked potentials"	Muller et al. (44)
1.5 T -simulated imaging condition -in vitro -studied the amalgamrelated mercury release for typical MRI conditions	"in vitro study demonstrated no evidence of an elevated mercury dissolution..."	Muller-Miny et al. (45)
0.75 T -static magnetic field only -hamster cells -studied effect of static magnetic field on DNA synthesis and survival of mammalian cells irradiated with fast neutrons	"presence of the magnetic field either during or subsequent to fast-neutron irradiation does not effect the neutron-induced radiation damage or its repair"	Ngo et al. (46)
1.5 T -simulated imaging conditions -human subjects -studied effect of MRI on somatosensory and brainstem auditory evoked potentials	"it may be assumed that MRI causes no lasting changes"	Niemann et al. (47)
1.89 T -static magnetic field only -mice -studied effects of long term exposure to a static magnetic field magnet groups compared to two control groups"	"no consistent differences found in gross and microscopic morphology, hematocrit and WBCs, plasma creatine phosphokinase, lactic dehydrogenase, cholesterol, trigliceride, or protein concentrations in	Osbakken et al. (48)
0.15 T -simulated imaging conditions -rats -studied effects of MRI on behavior of rats	"results fail to provide any evidence for short or long term behavioral changes in animals exposed to MRI"	Ossenkopp et al. (49)
0.15 T -simulated imaging conditions -rats -studied effect of MRI on murine opiate analgesia levels	"NMRI procedure alter both day and night time responses to morphine"	Ossenkopp et al. (50)
1.0 T -static magnetic field only -mice -studied effect of static magnetic field on in vivo bone growth	"results suggest that exposure to intense magnetic fields does not alter physiological mechanisms of bone mineralization"	Papatheo-fanis and Papathe-fanis (51)
2.35 T -static and gradient magnetic fields only -nematodes -studied toxic effects of static and gradient magnetic fields	"static magnetic fields have no effect on fitness of test animals" "time-varying magnetic fields cause inhibition of growth and maturation" "combination of pulsed magnetic field gradients in a static uniform magnetic field also has a detrimental effect on the fitness of the test animals"	Peeling et al. (52)
0.7 T -simulated imaging conditions -frog spermatazoa, fertilized eggs, and embryos, -studied effects of MRI on development	"NMR exposure, at the dose used does not cause detectable adverse effects in this amphibian"	Prasad et al. (53)
0.7 T -simulated imaging conditions -mouse bone marrow cells -studied the cytogenic effects of MRI	"NMR exposure causes no adverse cytogenic effects"	Prasad et al. (54)
2.35 T -simulated imaging conditions -mice -studied the effect of MRI on tumor development	"immune response may be enhanced following MRI exposure, as indicated by the longer latency and smaller sizes of tumors in animals receiving MRI exposure"	Prasad et al. (55)
4.5 T -simulated imaging conditions -mice -studied the effects of high field strength MR imaging on mouse testes epididymes	"little, if any, damage to male reproductive tissues from...high intensity MRI exposure"	Prasad et al (56)
2.35 T -simulated imaging conditions -human peripheral blood mononuclear cells (PBMC) -studied effect of MRI on natural killer cell toxicity of PBMC with and without interleukin-2	"in neither case was cytotoxicity affected by prior exposure to MR imaging"	Prasad et al. (57)
0.15 T -simulated imaging conditions -mice -studied effects of MRI on immune system	"MR exposure has no adverse effect on the immune system, as evidenced by natural killer cell activity"	Prasad et al. (58)
0.15 and 4.0 T -simulated imaging conditions -fertilized frog eggs studied effect of MRI on developing embryos	"no adverse effect early development"	Prasad et al. (59)
0.15 T -exposed separately to static, gradient and RF electromagnetic fields -mice -studied separate effects of static, gradient and RF electromagnetic fields on morphine induced analgesia in mice	"time-varying, and to a lesser extent the RF, fields associated with the MRI procedure inhibit morphine-induced analgesia in mice"	Prato et al. (60)
4.7 T -clinical imaging conditions -human subjects -studied bioeffects of 4.7 T scanner	"mild vertigo" "headaches, nausea" "magnetophosphenes" "metallic taste in mouth"	Redington et al. (61)
0.04 T -clinical imaging conditions -human subjects -follow-up study	"average follow-up time was 6 months...none of the 35 deaths recorded was unexpected" "using the magnetic field and radiofrequency levels currently in operation...we believe NMRI to be a safe, non-invasive method of whole-body imaging	Reid et al. (62)
1.5 T -simulated imaging conditions -fetal mice -studied combined effect of exposure to gadopentetate dimeglumine and MR imaging on the developing embryo	"...MR exposure with and without gadopentetate dimeglumine had no adverse effect on the end points analyzed."	Rofsky et al. (63)
4.0 T -RF at 8 MHz to 170 MHz -no gradient magnetic fields -human subjects -studied response of human auditory system to RF-pulses	"in accordance with the used RF modulation envelope three distinct chirps per sequence could be resolved" "RF induced auditory noise is usually completely masked by noise from simultaneously switched gradient fields"	Roschmann et al. (64)
2.7 T -simulated imaging conditions -rats -studied effects of MRI on ocular tissues	"there were no discernable effects on the rat eye"	Sacks et al. (65)
1.5 T -clinical imaging conditions -human subjects -studied effect of electromagnetic fields on melatonin levels	"MR imaging at high field strengths...did not suppress melatonin levels in human subjects."	Schiffman et al. (66)
0.35 T -simulated imaging conditions -hamster ovary cells -studied effects of MRI on observable mutations and cytotoxicity	"NMR imaging caused no detectable genetic damage and does not affect cell viability"	Schwartz and Crooks (67)
1.5 T -static magnetic field only -human subjects -studied effect of static magnetic field on body temperature	"no effect on body temperature of normal human subjects"	Shellock et al. (68)
1.5 T -clinical imaging conditions -human subjects -studied thermal effects of MRI of the spine	"no surface "hot spots" "temperature effects were well-below known thresholds for adverse effects"	Shellock et al. (69)
1.5 T -clinical imaging conditions -human subjects -studied possible hypothalamic heating produced by MRI of the head	"there was probably no direct hypothalamic heating produced by clinical MRI of the head"	Shellock et al. (70)
1.5 T -clinical imaging conditions -human subjects -studied effect of MRI on corneal temperatures	"MR imaging... causes relatively minor increases in corneal temperature that do not appear to pose any thermal hazard to ocular tissue"	Shellock and Crues (71)
1.5 T -clinical imaging conditions -human subjects -studied temperature, heart rate, and blood pressure changes associated with MRI	"MR imaging... not associated with any temperature or hemodynamic related deleterious effects"	Shellock and Crues (72)
1.5 T -clinical imaging conditions -human subjects -studied temperature changes associated with MRI of the brain	"no significant increases in average body temperature" "observed elevations in skin temperatures were physiologically inconsequential"	Shellock and Crues (73)
1.5 T -static magnetic field only -human subjects -studied effects of static magnetic field on body and skin temperatures	"there were no statistically significant changes in body or any of the skin temperatures recorded"	Shellock et al. (74)
1.5 T -clinical imaging conditions -human subjects -studied effect of MRI performed at high SAR levels	"recommended exposure to RF radiation during MR imaging of the body for patients with normal thermoregulatory function may be too conservative"	Shellock et al. (75)
1.5 T -clinical imaging conditions -human subjects -studied effect of MRI on scrotal skin temperature	"absolute temperature is below threshold known to affect testicular function"	Shellock et al. (76)
1.5 T -clinical imaging conditions -phantom -studied acoustic noise	"MR imaging performed with the worst-case pulse sequences did not produce noise levels that exceeded federal guidelines."	Shellock et al. (77)
0.15 T -simulated imaging conditions -anesthetized rats -studied effect of MRI on blood-brain barrier permeability	"these findings raise the possibility that exposure to clinical MRI procedures may also temporarily alter the central blood-brain permeability in human subjects"	Shivers et al. (78)
1.5 T -simulated imaging conditions -anesthetized dogs -studied effect of MRI performed at high SAR levels	"these findings argue for continued caution in the design and operation of imagers capable of high specific absorption rates"	Shuman et al. (79)
0.4 to 8.0 T -static magnetic field only -mice -studied effect of static magnetic field on temperature	"observed a field-induced increase in temperature"	Sperber et al. (80)
0.4 to 1.0 T -static magnetic field only -human subjects -studied the effects of static magnetic fields on tissue perfusion	"neither at the skin of the thumb nor at the forearm were the changes in local blood flow attributable to the magnetic fields applied"	Stick et al. (81)
0.4 T -static magnetic field only -human subjects -studied magnetic field induced changes in auditory evoked potentials	"strong steady magnetic fields induce changes in human auditory evoked potentials"	Stojan et al. (82)
0.15 T -clinical imaging conditions -human subjects -studied effect of MRI on cognitive functions	"no significant effect upon cognitive functions assessed"	Sweetland et al. (83)
0.6 T/sec -gradient magnetic field only -mice -studied effect of gradient magnetic fields on the analgesic properties of specific opiate antagonists	"results indicate that the time-varying fields associated with MRI have significant inhibitory effects on analgesic effects of specific my-opiatedirected ligands"	Teskey et al. (84)
0.15 T -simulated imaging conditions -rats -studied effects of MRI on survivability and longterm stress reactivity levels	"results fail to provide any evidence for changes in survivability and longterm reactivity levels in rats exposed to MRI"	Teskey et al. (85)
0.01 and 1.0 T -simulated imaging conditions and static magnetic field only -Echerichia coli -studied effect of MRI and static magnetic field on various properties of E. coli	"no mutations or lethal effects observed"	Thomas and Morris (86)
1.5 T -simulated imaging conditions -mice -studied the potential effects of MRI fields on eye development	"these data suggest a potential for MRI teratogenicity in a strain of mouse predisposed to eye malformations"	Tyndall (87)
1.5 T -simulated imaging conditions -C57BL/6J mouse -studied combined effects of MRI and X-irradiation on the developing eye of the mouse	"results...suggested that the MRI techniques employed for this investigation did not enhance teratogenicity of X- irradiation on eye malformations produced in the 657BL/6J mouse"	Tyndall and Sulik (88)
0.35 and 1.5 T -clinical imaging conditions -human subjects -studied effects of MRI on temperature	"no significant changes in central or peripheral temperatures resulting from the application of static or dynamic or radiofrequency"	Vogl et al. (89)
0.35 T -static magnetic field only -human subjects -studied effect of static magnetic field on auditory evoked potentials	"magnetically induced shift may be explained by changes in electric capacities of the magnetically exposed biological system"	Von Klitzing (90)
0.2 T -static magnetic field only -human subjects -studied effect of static magnetic field on power intensity of EEG	"the increased control values following on inverted magnetic flux vector point to a reversible alteration of brain function induced by a static magnetic field"	Von Klitzing (91)
0.2 T -static magnetic field only -human subjects studied -studied encephalomagnetic fields during exposure to static magnetic field	"exposure to static magnetic fields as used in NMR-equipment generates a new encephalomagnetic field in human brain"	Von Klitzing (92)
1.5 and 4.0 T -static magnetic fields only -rats -studied effect of magnetic field on behavior	"at 4 T... in 97% of the trials the rats would not enter the magnet"	Weiss et al. (93)
0.16 T -static and gradient magnetic fields only -anesthetized rats and guinea pigs -studied effects of static and gradient magnetic fields on cardiac function of rats and guinea pigs	"no change in blood pressure, heart rate, or ECG"	Willis and Brooks (94)
0.3 T -static magnetic field only -mouse sperm cell -studied effect of static magnetic field on spermatogenesis	"acute and subacute exposure to static magnetic fields associated with diagnostic MR imaging devices is unlikely to have any significant adverse effect on spermatogesis"	Withers et al. (95)
0.35 T -simulated imaging conditions -hamster ovary cells -studied effect of MRI on DNA and chromosomes	"the conditions used for NMR imaging do not cause genetic damage which is detectable by any of these methods"	Wolff et al. (96)
-varying gradient fields -human subjects -studied the effects of time-varying gradient fields on peripheral nerve stimulation using trapezoidal and sinusoidal pulse trains	"the thresholds of trapezoidal pulses were higher than those of sinusoidal pulses by 11% and 30% respectively, at equivalent power level"	Yamagata et al. (97)
1.5 T -simulated imaging conditions -chick embryos -studied teratogenicity of magnetic resonance field exposure	"...exposed embryos...showed a trend toward higher abnormality and mortality rates than their controls."	Yip et al. (98)
1.5 T -simulated imaging conditions -chick embryos -studied effect of of magnetic resonance exposure on proliferation and migration of motoneurons	"...birth rates, migration, and proliferation of lateral motoneurons were unaffected compared to their controls."	Yip et al. (99)
1.5 T -simulated imaging conditions -chick embryos -studied effects of of magnetic resonance exposure on the rate and specificity of sympathetic preganglionic axonal outgrowth	"...MR exposure conditions used in this study do not affect axonal growth in the sympathetic nervous system of the chick."	Yip et al. (100)
0.5 and 1.5 Tesla -static and gradient magnetic field -human subject -studied magnetic field effects on phantom limb pain	"The painful symptoms mimicked those experienced in the presence of the imagers".	Yuh et al. (101)

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Magnetic Resonance Procedures: Summary of Bioeffects and Safety Research 1997 to 1999

Study description	Summary Results	Reference
1.5 T and 2.0 T -simulated imaging conditions -studied typical acoustic noise and analyzed the characteristics	"Through the analysis of acoustic noise, we find that the acoustic noise profiles and their frequency distributions are not only dependent on the pulse sequence employed but also greatly dependent on the types of scanners, especially the coil structures and their supports."	Cho et al. (1)
-various MR systems –clinical conditions – the safety profile of ProHance in special populations was evaluated by analyzing data extracted from the database of phase I-III studies -pediatric, elderly, and patients with renal disease studied	ProHance was administered at doses ranging from 0.1 mmol/kg to 0.3 mmol/kg and was found to be safe in all patient populations irrespective of age and of pre-existing renal impairment. There appeared to be no correlation between incidence of adverse events and dose level in these special populations and the higher dose level of 0.3 mmol/kg could be safely administered also to patients with end stage renal disease requiring hemodialysis, from whom the contrast medium was rapidly and efficiently dialysed.	Yoshikawa and Davies (2)
1.0 T -simulated imaging conditions -studied active noise control techniques that introduce antiphase noise to destructively interfere with MRI noise to produce a zone of quite around the patient’s ears	The results obtained show a useful attenuation of low-frequency periodic acoustic noise components. This suggests that MR generated acoustic noise can be effectively attenuated at both low and high frequencies leading to improved patient comfort.	McJury et al. (3)
1.5 T -simulated imaging conditions -healthy volunteers -studied effects of high gradient amplitudes and switching rates	"…only for the imaging protocols characterized by the application of long bipolar repetitive gradient pulse trains, such as echo planar, peripheral nerve stimulation is reported at the threshold levels."	Ham et al. (4)
-various MR systems and conditions -2,481 adult and pediatric subjects were studied with gadoteridol at doses from 0.025 to 0.3 mmol/kg in phase I-IIIb clinical trials in Europe and the United States	This report confirms the excellent safety profile of gadoteridol in healthy subjects and patients with a variety of known or suspected pathologies.	Runge and Parker (5)
1.5 T -human subjects -clinical imaging conditions -studied the incidence, type, and location of stimulation in a whole-body scanner	"Maximum stimulation typically occurred 30 to 40 cm from isocenter in the region of maximum dB/dt. Generally, y gradients produced truncal stimulation and x gradients produced stimulation in the head. …Patients should be instructed to keep their hands apart."	Ehrhardt et al. (6)
-human subjects -clinical imaging conditions -study performed to assess the stimulation threshold for healthy adults using sinusoidally oscillating gradients	The greatest frequency of reported stimulations occurs when the y-gradient is used. This was confirmed by the results and support the hypothesis that orthogonal to the y-axis the body has the largest conductive loop, resulting in the strongest peripheral simulation.	Abart et al. (7)
1.5 T -clinical imaging conditions -human subjects, neonates -studied heart rate (HR) and oxygen saturation before and during MR examinations of newborns	"Fluctuations in HR (but not oxygen saturation) that are temporally linked to the MR image acquisition occur in most neonates during routine clinical MR examinations."	Taber et al. (8)
2.0 T -simulated imaging conditions –human volunteers -studied effects of acoustic, or sound noise arising in fMR imaging of the auditory, visual, and motor cortices	"…results show that the effects of acoustic noise on motor and visual responses are opposite…could have significant conequences in data observation and interpretation in future fMRI studies."	Cho et al. (9)
-various MR systems and conditions -this study assessed the safety, efficacy and cost-effectiveness of the use of triple dose gadolinium-DTPA (Gd) in serial monthly brain MRI of patients with multiple sclerosis	No side-effects were reported and no significant changes in blood test parameters were found throughout the study. This study shows that the serial use of triple dose Gd is safe, and that it increases the sensitivity of serial monthly enhanced MRI in detecting multiple sclerosis activity significantly.	Filippi M, et al. (10)
-various MR systems and conditions -this study evaluated the safety and pharmacokinetics of gadolinium contrast agents in patients with hemodialysis, in vitro and clinical studies were performed	The results showed that all contrast agents and both dialysis membranes were suitable. Neither change in laboratory parameters nor side effects were observed. ...consequently, there are no contraindications when using the ordinary dose of contrast agent even in patients with dialysis.	Katagiri K, et al. (11)
1.5 T -simulated imaging conditions -this study assessed gradient magnetic-field-induced acoustic noise levels associated with the use of echo planar imaging (EPI) and three-dimensional fast spin echo (3D-FSE) pulse sequences	"Gradient magnetic fields associated with the use of EPI and 3D-FSE techniques produced acoustic noise levels that were within the permissible levels recommended by federal guidelines."	Shellock et al. (12)
-1.5 T -simulated imaging conditions -human subjects	The dB/dt intensity to induce a sensation which the subject described as uncomfortable was about 50% above the sensation threshold. Experiments with dogs showed that cardiac stimulation by pulsed magnetic gradient fields is exceedingly unlikely.	Bourland et al. (13)
-0.5 T -static field only -Wistar albino mice -studied possible alterations in enzyme activity of catalase and isoenzyme MB-creatine kinase induced by prolonged exposure of laboratory rodents to a static magnetic field	Results exclude any alteration in the activity of catalase and isoenzyme MB-creatine kinase caused by long-term exposure to a 0.5 T Magnetic Resonance unit.	Salerno et al. (14)
1.5 T -simulated imaging conditions –human fetal lung fibroblast cells -studied the effects of repetitive exposures to static magnetic field on cell proliferation	"The data do not provide evidence that repetitive exposures to a static magnetic field (1.5 T) exert effects on HFL proliferation."	Wiskerchen et al. (15)

Magnetic Resonance Procedures: Summary of Bioeffects and Safety Research 1997 to 1999 References

1. Cho ZH, et al. Analysis of acoustic noise in MRI. Magnetic Resonance Imaging 1997;15:815-822.

2. Yoshikawa K, Davies A. Safety of ProHance in special populations. Eur Radiol 1997;7 Suppl 5:246-50.

3. McJury M, Stewart RW, Crawford D, Toma E. The use of active noise control (ANC) to reduce acoustic noise generated during MRI scanning: some initial results. Magn Reson Imaging 1997;15:319-322.

4. Ham CLG, Engels JML, van de Wiel GT, Machielsen A. Peripheral nerve stimulation during MRI: effects of high gradient amplitudes and switching rates. J Magn Reson Imag 1997;7:933-937.

5. Runge VM, Parker JR. Worldwide clinical safety assessment of gadoteridol injection: an update Eur Radiol 1997;7Suppl 5:243-5.

6. Ehrhardt JC, et al. Peripheral nerve stimulation in a whole-body echo-planar imaging system. J Magn Reson Imag 1997;7:405-409.

7. Abart J, et al. Peripheral nerve stimulation by time-varying magnetic fields. J Comput Assist Tomogr 1997;21:532-538.

8. Taber K, et al. Vital sign changes during infant magnetic resonance examinations. J Magn Reson Imag 1998;8:1252-1256.

9. Cho ZH, et al. Effects of acoustic noise of the gradient systems on fMRI: a study on auditory, motor, and visual cortices. Magn Reson in Med 1998;39:331-336.

10. Filippi M, et al. A multi-centre longitudinal study comparing the sensitivity of monthly MRI after standard and triple dose gadolinium-DTPA for monitoring disease activity in multiple sclerosis. Implications for phase II clinical trials. Brain 1998;121 (Pt 10):2011-2020.

11. Katagiri K, et al. Clearance of gadolinium contrast agent by hemodialysis: in vitro and clinical studies. [Article in Japanese] Nippon Igaku Hoshasen Gakkai Zasshi 1998;58:739-44.

12. Shellock FG, Ziarati M, Atkinson D, Chen DY. Determination of gradient magnetic field-induced acoustic noise associated with the use of echo planar and three-dimensional, fast spin echo techniques. J Magn Reson Imaging 1998;8:1154-1157.

13. Bourland JD, Nyenhuis JA, Schaefer DJ. Physiologic effects of intense MR imaging gradient fields. Neuroimaging Clin N Amer 1999;9:363-367.

14. Salerno S, et al. Biologic effects of the static magnetic field generated by a 0.5 T magnetic resonance tomograph on the enzyme activity of catalase and creatine kinase in the rat. Radiol Med (Torino) 1999;97:174-8.

15. Wiskirchen J, et al. Long-term effects of repetitive exposure to a static magnetic field (1.5 T) on proliferation of human fetal lung fibroblasts. Magn Reson Med 1999;41:464-468.

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