Magnetic Resonance Imaging Procedures Research Articles

Clinical safety of the ProMRI pacemaker system in patients subjected to thoracic spine and cardiac 1.5-T magnetic resonance imaging scanning conditions

Permanent cardiac pacemakers have historically been considered a contraindication to magnetic resonance imaging (MRI). The purpose of the ProMRI Phase B Study, a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI pacemaker system in patients undergoing thoracic spine and cardiac MRI. The ProMRI Phase B study enrolled 245 patients with stable baseline pacing indices implanted with an Entovis pacemaker (DR-T or SR-T) and Setrox 53-cm and/or 60-cm lead(s). Device interrogation was performed at enrollment, pre- and post-MRI scan, and 1 and 3 months post-MRI. End-points were (1) freedom from MRI- and pacing system-related serious adverse device effects through 1 month post-MRI; (2) freedom from atrial and ventricular MRI-induced pacing threshold increase (>0.5 V); and (3) freedom from P- and R-wave amplitude attenuation (<50%), or P wave <1.5 mV, or R wave <5.0 mV at 1 month post-MRI. In total, 216 patients completed the MRI and 1-month post-MRI follow-up. One adverse event possibly related to the implanted system and the MRI procedure occurred, resulting in a serious adverse device effect-free rate of 99.6% (220/221; P < .0001. Freedom from atrial and ventricular pacing threshold increase was 100% (194/194, P < .001) and 100% (206/206, P < .001) respectively. Freedom from P- and R-wave amplitude attenuation was 98.2% (167/170, P < .001) and 100% (188/188, P < .001) respectively. The results of the ProMRI Phase B study demonstrate the clinical safety and efficacy of the ProMRI pacemaker system in patients subjected to thoracic spine and cardiac MRI conditions.

MRI Heating Reduction for External Fixation Devices Using Absorption Material

This paper presents a novel approach to minimize the radio frequency (RF)-induced heating from external fixation devices under magnetic resonance imaging (MRI) procedure. With proper placement and selection of absorption material, one can alter the electromagnetic field and current distributions around and/or on medical devices so that the MRI RF field-induced heating can be reduced. The absorption-material-based RF heating reduction schemes are analyzed and validated. Numerical and experimental studies are conducted to illustrate the potentials of reducing the RF heating for external fixation devices. A design strategy based on response surface methodology is presented for material selection, and it is shown that absorption materials can significantly reduce the RF heating effects from 645 to 172 W/kg in terms of 1-g spatial-averaged SAR for the device under this investigation.

Abstract 260: Congruence of Speckle Tracking Echocardiography and Magnetic Resonance Imaging Assessment of Left Ventricular Ejection Fraction

Background: Assessment of left ventricular ejection fraction (LVEF) is an important aspect of diagnosing and treating patients with cardiovascular disease. While cardiac MRI is considered the gold standard for assessing LVEF, high cost and patient risk has precluded routine use of MRI in clinical practice. Echocardiography is a common non-invasive, safe, and economic method for assessing LVEF. Traditionally, these measures required making visual determinations, resulting in wide variations in LVEF estimates. Using calculations from global longitudinal peak strain (GLPS) in speckle tracking echocardiography (STE) might reduce variability in estimations of LVEF and enhance treatment decision-making. To examine whether STE GLPS compared to cardiac MRI provides clinically acceptable variation in LVEF estimations, the congruence between GLPS in STE and cardiac MRI was examined. Methods: At a single Midwestern regional referral center, medical records were abstracted for inpatients and outpatients with a first-listed cardiovascular disease diagnosis who were ≥18 years of age and who were evaluated using speckle tracking echocardiogram and magnetic resonance imaging procedures within a 30-day period between January, 2011 and May, 2014. Demographic and relevant clinical variables that might affect echocardiographic and MRI quality and interpretation were extracted from medical records. Overall agreement between LVEF estimates from cardiac MRI and from STE GLPS was assessed using the concordance correlation coefficient, Bland-Altman analysis, and weighted Kappa. The influence of demographic and co-morbidity factors on the agreement was also assessed using multivariable regression analysis. Results: A total of 93 patient medical records (48 males; age 59±18 years) underwent both STE and MRI within a maximum 30-day period. For quantification of LVEF, STE correlated well with MRI (r=0.73; CCC=0.67), but LVEF was significantly underestimated (bias=6.8%), with wide limits of agreement (-17% to 31%). Categorization of LVEF into four classes, ranging from severely impaired to normal, resulted in a weighted kappa of 0.65 (95% CI: 0.53, 0.77). The difference between MRI and STE increased with increasing BMI (b=0.48, P=.01), and this difference was greater for those with hypertension (mean=9.5) than those without hypertension (mean=3.8, P=.02). Discussion and Conclusions: While these two measures indicate moderate to substantial agreement, STE-derived LVEF was underestimated in most patients compared with MRI. The magnitude of STE underestimation was positively associated with both BMI and hypertension. Further research is needed on technological developments in echocardiography, as well as interventions focused on addressing inter-observer agreement variability and treatment decision-making to effectively achieve desired clinical outcomes.

Gadobutrol for contrast-enhanced magnetic resonance imaging in elderly patients: review of the safety profile from clinical trial, post-marketing surveillance, and pharmacovigilance data

To assess the safety of gadobutrol administration in elderly patients (≥65 years) by comparing the incidence of adverse drug reactions (ADRs) following gadobutrol-enhanced magnetic resonance imaging (MRI) procedures in elderly patients with that in adults aged 18-64 years. Safety data on gadobutrol administration from clinical trials, post-marketing surveillance (PMS) studies, and pharmacovigilance reports were collected in three databases. In each dataset, absolute and relative frequencies of ADRs between age groups were analysed, along with odds ratios and 95% confidence intervals. Logistic regression was used to identify significant influencing factors on ADRs in the PMS and pharmacovigilance data. Rates of reported ADRs were lower in elderly patients versus adults aged <65 years due to a reduced incidence of non-serious ADRs; this was statistically significant for the clinical trials and pharmacovigilance populations, with a trend in the PMS database. Serious ADRs occurred infrequently in the clinical trials and PMS populations (too low for statistical comparison), and pharmacovigilance data demonstrated a low incidence (<0.005%) in both age groups. This evaluation involving three large databases demonstrated no greater incidence of ADRs following gadobutrol-enhanced MRI in elderly patients (≥65 years) compared with younger adults, with gadobutrol having a favourable safety profile in both age groups.

Hippocampal Metabolites Correlate with Neuroimaging Outcomes in the Piglet

By combining magnetic resonance imaging (MRI) and metabolomic profiling techniques, the objective of this study was to elucidate relationships between brain structure and hippocampal metabolites in the piglet. Two-day-old, vaginally-delivered male piglets (n=24) were artificially reared using standardized procedures and feeding a custom milk replacer formulated to meet piglet nutrient requirements. At 30 d of age, piglets underwent MRI procedures, and brain tissue was collected 24 h post-imaging for metabolomic and lipodomic profiling of hippocampal tissue. Analysis of MRI data in 19 brain regions yielded volumetric estimates as well as microstructural details measured by diffusion tensor fractional anisotropy (FA), and radial (RD), axial (AD), and mean (MD) diffusivities, which provide directional characterization of water movement within axons. Comparison of fatty acids in n-3, n-6, and n-9 categories with MRI measures yielded correlations (P < 0.05) in 150 of 2726, 162 of 3596, and 129 of 2494 possible outcomes, respectively. Neuroimaging outcomes that were highly correlative across fatty acid categories included MD, RD, and AD in the internal capsule and right hippocampus, suggesting ongoing myelination in the piglet brain. Nervonic acid, a fatty acid known to be prevalent at peak myelination, was correlated with 26 of 58 total outcomes, further supporting the link between metabolism and neurodevelopment. In conclusion, significant correlations between metabolic and structural outcomes in the neonatal piglet brain emphasize targets whereby dietary manipulation may alter neurodevelopmental patterns. Supported by Mead Johnson Nutrition.

Neurodevelopment in Piglets is Influenced by Perinatal Choline Status as Evidenced by Magnetic Resonance Imaging

Adequate choline supply during the perinatal period is critical for proper brain formation when robust neurogenesis and neuronal maturation are occurring. To examine the impact of perinatal choline on neurodevelopment, sows (n = 8) were fed a choline deficient (CD) or sufficient (CS) diet during the last 65 d of the 114 d gestation period. At 2 d of age, piglets from sows within each prenatal treatment group were stratified into postnatal treatment groups and provided either a CD or CS milk replacer, resulting in a 2 x 2 factorial arrangement (N = 32, n = 6‐9 piglets treatment). At 30 d of age, piglets underwent magnetic resonance imaging procedures to examine brain morphology and metabolite concentrations. Fractional anisotropy (FA) values, obtained from diffusion tensor imaging, revealed an interaction (P = 0.02) between prenatal and postnatal treatments in the right hippocampus. Pigs of a continuous perinatal CD status exhibited lower FA values than CS/CD and CD/CS piglets, highlighting the importance of perinatal choline supplementation for white matter development. Voxel‐based morphometry illustrated differences (P 蠄 0.01) between prenatal choline status in grey and white matter volumes of cortical, cerebellar, and hippocampal regions. Volumes of whole brain, cortical, and subcortical regions were greater (P 蠄 0.05) in prenatal CS compared with prenatal CD piglets. Hippocampal metabolites, assessed using single‐voxel spectroscopy, indicated a decrease (P &lt; 0.01) in glycerophosphocholine + phosphocholine concentration in postnatal CD piglets and a decrease (P = 0.01) in glutamate + glutamine concentration in prenatal CD piglets. These results suggest that adequate dietary choline provided prenatally or postnatally, promotes neuronal growth and maturation.

Nephrogenic Systemic Fibrosis on Mammography

Nephrogenic systemic fibrosis, previously known as nephrogenic fibrosing dermopathy, is a multiorgan sclerotic disorder that is strongly linked to the administration of gadolinium-based chelates used for intravenous contrast in magnetic resonance imaging procedures. Although involvement of truncal skin is a relatively common, few reports of its appearance on mammography exist in the literature.

Clinical safety of the ProMRI pacemaker system in patients subjected to head and lower lumbar 1.5-T magnetic resonance imaging scanning conditions

Permanent cardiac pacemakers have historically been considered a contraindication to magnetic resonance imaging (MRI). The purpose of the ProMRI/ProMRI AFFIRM Study, which was a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI Pacemaker System under specific MRI conditions. The ProMRI Study (in the United States) and the ProMRI AFFIRM study (outside the United States) with identical design enrolled 272 patients with stable baseline pacing indices implanted with an Entovis or Evia pacemaker (DR-T or SR-T) and Setrox or Safio 53-cm or 60-cm lead. Device interrogation was performed at enrollment, pre-MRI and post-MRI scan, and 1 and 3 months post-MRI. End-points were (1) freedom from MRI- and pacing system-related serious adverse device effects (SADEs) through 1 month post-MRI, (2) freedom from atrial and ventricular MRI-induced pacing threshold increase (>0.5 V), and (3) freedom from P- and R-wave amplitude attenuation (<50%), or P wave <1.5 mV, or R wave <5.0 mV at 1 month post-MRI. Two hundred twenty-six patients completed the MRI and 1-month post-MRI follow-up. No adverse events related to the implanted system and the MRI procedure occurred, resulting in an SADE-free rate of 100.0% (229/229, P <.001). Freedom from atrial and ventricular pacing threshold increase was 99.0% (189/191, P = .003) and 100% (217/217, P <.001), respectively. Freedom from P- and R- wave amplitude attenuation was 99.4% (167/168, P <.001) and 99.5% (193/194, P <.001), respectively. The results of the ProMRI/ProMRI AFFIRM studies demonstrate the clinical safety and efficacy of the ProMRI pacemaker system in patients subjected to head and lower lumbar MRI conditions.

Use of Public Data to Target Variation in Providers' Use of CT and MR Imaging among Medicare Beneficiaries.

To examine geographic variation in providers' use of diagnostic imaging to identify potential targets for quality improvement initiatives after adjusting for imaging referral across hospital referral regions (HRRs). Using two Centers for Medicare and Medicaid Services datasets, the authors included all claims for beneficiaries enrolled in the Medicare fee-for-service program. Diagnostic imaging procedures were selected on the basis of common procedure coding system codes, excluding interventional procedures. The authors assessed providers' use of imaging for each HRR after creating an imaging referral index (IRI) to adjust for imaging referral rates across HRRs. Relative risk statistics were used to assess geographic variation. The authors calculated two imaging measures for computed tomography (CT) and magnetic resonance (MR) imaging: IRI-adjusted utilization intensity (number of examinations per 1000 beneficiaries) and total payments (in dollars, after deducting deductibles and coinsurances) in each HRR. High-impact regions were defined as those in the highest deciles for both imaging intensity and payment. For 34 million Medicare beneficiaries, 124 million unique diagnostic imaging services (totaling $5.6 billion) were performed in 2012. The average adjusted CT utilization intensity ranged from 330.4 studies per 1000 beneficiaries in the lowest decile to 684.0 in the highest decile (relative risk, 2.1); adjusted MR imaging utilization intensity varied from 105.7 studies per 1000 beneficiaries to 256.3 (relative risk, 2.4). The most common CT and MR imaging procedures were head CT and lumbar spine MR imaging. With use of public data, the authors identified a wide variation in imaging use across the United States. Potential targets for future imaging quality improvement initiatives include head CT and lumbar spine MR imaging.

A method of detecting heartbeat locations in the ballistocardiographic signal from the fiber-optic vital signs sensor.

We present a flexible, easy-to-expand digital signal processing method for detecting heart rate (HR) for cardiac vibration signals of fiber Bragg grating (FBG) sensor. The FBG-based method of measuring HR is possible to use during the magnetic resonance imaging procedure, which is its unique advantage. Our goal was to design a detection method with plurality of parameters and to subject these parameters to genetic algorithm optimization technique. In effect, we arrived at a method that is well able to deal with much distorted signals with low SNR. We proved that the method we developed allows automatic adjustment to the shape of the waves of signal carrying useful information about the moments of heartbeat. Thus, we can easily adapt our technique to the analysis of signals, which contains information on HR, from sensors employing different techniques of strain detection. The proposed method has the capabilities of analyzing signals in semi-real-time (online) with beat-to-beat resolution, significantly low delay, and negligible computational power requirements. We verified our method on recordings in a group of seven subjects. Verification included over 6000 heartbeats (82min 47s of recordings). The root-mean-square error of our method does not exceed 6.0bpm.

Time-Related Changes in Yield and Harms of Screening Breast Magnetic Resonance Imaging

PurposeBreast magnetic resonance imaging (MRI) is accepted as a useful adjunct to screening mammography for women at high risk for breast cancer. Nevertheless, concerns about false-positive findings remain, and data about MRI harms and yields are limited. The aim of this study was to quantify harms and yields of breast MRI over time in a large series of patients. MethodsA retrospective review was performed of patients at increased risk for breast cancer who underwent annual screening digital mammography and MRI from 2007 to 2013. Harms were defined as events not producing a breast cancer diagnosis (ultrasonography [US], imaging-guided core or surgical biopsy procedure, recommendation for short-term follow-up, or a combination). ResultsOf 350 high-risk patients offered MRI screening, 320 underwent 757 screening MRI procedures over time. The median age at the first MRI was 48 years. All patients met American Cancer Society criteria for annual screening breast MRI. Total harms were highest with the first MRI procedure and decreased with subsequent MRI screening. Of 75 biopsy procedures performed, including 58 US- or MRI-guided core biopsy procedures and 17 surgical biopsy procedures, 6 specimens were found to be malignant, including 2 resulting from biopsy procedures performed based on findings from the first MRI scan, 0 from the second MRI scan, 3 from the third MRI scan, and 1 from the fourth MRI scan. ConclusionAmong women followed with screening MRI, the number of harms was shown to decrease over time. Breast cancer continued to be detected in MRI studies performed over time. This study demonstrates the utility of MRI screening performed over time in high-risk women.

Fiber-optic sensors for monitoring patient physiological parameters: a review of applicable technologies and relevance to use during magnetic resonance imaging procedures.

The issues involved with recording vital functions in the magnetic resonance imaging (MRI) environment using fiber-optic sensors are considered in this paper. Basic physiological parameters, such as respiration and heart rate, are fundamental for predicting the risk of anxiety, panic, and claustrophobic episodes in patients undergoing MRI examinations. Electronic transducers are generally hazardous to the patient and are prone to erroneous operation in heavily electromagnetically penetrated MRI environments; however, nonmetallic fiber-optic sensors are inherently immune to electromagnetic effects and will be crucial for acquiring the above-mentioned physiological parameters. Forty-seven MRI-tested or potentially MRI-compatible sensors have appeared in the literature over the last 20 years. The author classifies these sensors into several categories and subcategories, depending on the sensing element placement, method of application, and measure and type. The author includes five in-house-designed fiber Bragg grating based sensors and shares experience in acquiring physiological measurements during MRI scans. This paper aims to systematize the knowledge of fiber-optic techniques for recording life functions and to indicate the current directions of development in this area.

A Technique to Evaluate MRI-Induced Electric Fields at the Ends of Practical Implanted Lead

This paper presents a novel technique for efficient evaluation of magnetic resonance imaging (MRI)-induced electric fields or induced voltages in the vicinity of implanted metallic leads. The technique is based on the reciprocity theorem in conjunction with the Huygens Principle. This approach allows one to decouple the micro-scale metallic lead simulation/measurement from the macro-level phantom human simulations within the MRI scanners. Consequently, the estimation of MRI-induced heating on an implanted lead, and the induced voltage on the pacemaker device can be greatly simplified. In addition, this method clearly explains the induced lead heating mechanism during MRI procedures. Several numerical examples, as well as measurement results are given to demonstrate the efficiency and accuracy of this method.

The Kora Pacemaker is Safe and Effective for Magnetic Resonance Imaging.

BACKGROUNDThe impact of magnetic resonance imaging (MRI) on pacemakers is potentially hazardous. We present clinical results from a novel MRI conditional pacing system with the capability to switch automatically to asynchronous mode in the presence of a strong magnetic field.AIMSThe IKONE (Assessment of the MRI solution: KORA 100™ and Beflex™ pacing leads system) study is an open-label, prospective, multicenter study aimed at confirming the safety and effectiveness of the system, when used in patients undergoing MRI of anatomical regions excluding the chest.METHODSPrimary eligibility criteria included patients implanted with the system, with or without a clinically indicated MRI. The primary endpoint was to confirm no significant change in pacing capture thresholds at 1 month after an MRI, with an absolute difference of ≤0.75 V between the pre- and 1-month post-MRI for both atrial and ventricular capture thresholds.RESULTSOut of 33 patients enrolled (mean age: 72.8 ± 11.4 years, 70% male, implant indication or device), 29 patients implanted with the MRI conditional system underwent an MRI 6–8 week postimplant. The study reached its primary endpoint: the mean absolute difference in pacing capture threshold at 1-month post-MRI versus pre-MRI was less than 0.75 V in the atrium (Δ = 0.18 ± 0.16 V, P-value < 0.001) and in the ventricle (Δ = 0.18 ± 0.22 V, P-value < 0.001). There were no adverse events related to the MRI procedure nor were there reports of patient symptoms or discomfort associated. MR image quality was of diagnostic quality in all patients.CONCLUSIONLead electrical performance as measured by difference in capture thresholds were not impacted by MRI. This first clinical evaluation of a novel MRI conditional system demonstrates it is safe and effective for use in out-of-chest, 1.5-T MR imaging.

Performance of ventilators compatible with magnetic resonance imaging: a bench study.

Magnetic resonance imaging (MRI) is indispensable for diagnosing brain and spinal cord abnormalities. Magnetic components cannot be used during MRI procedures; therefore, patient support equipment must use MRI-compatible materials. However, little is known of the performance of MRI-compatible ventilators. At commonly used settings, we tested the delivered tidal volume (V(T)), F(IO2), PEEP, and operation of the high-inspiratory-pressure-relief valves of 4 portable MRI-compatible ventilators (Pneupac VR1, ParaPAC 200DMRI, CAREvent MRI, iVent201) and one ICU ventilator (Servo-i). Each ventilator was set in volume control/continuous mandatory ventilation mode. Breathing frequency and V(T) were tested at 10 breaths/min and 300, 500, and 700 mL, respectively. The Pneupac VR1 has fixed V(T) and frequency combinations, so it was tested at V(T) = 300 mL and 20 breaths/min, V(T) = 500 mL and 12 breaths/min, and V(T) = 800 mL and 10 breaths/min. F(IO2) was 0.6 and 1.0. At the air-mix setting, F(IO2) was fixed at 0.5 with the Pneupac VR1, 0.45 with the ParaPAC 200DMRI, and 0.6 with the CAREvent MRI. PEEP was set at 5 and 10 cm H2O, and pressure relief was set at 30 and 40 cm H2O. V(T) error varied widely among ventilators (-28.1 to 25.5%). As V(T) increased, error decreased with the Pneupac VR1, ParaPAC 200DMRI, and CAREvent MRI (P < .05). F(IO2) error ranged from -13.3 to 25.3% at 0.6 (or air mix). PEEP error varied among ventilators (-29.2 to 42.5%). Only the Servo-i maintained V(T), F(IO2), and PEEP at set levels. The pressure-relief valves worked in all ventilators. None of the MRI-compatible ventilators maintained V(T), F(IO2), and PEEP at set levels. Vital signs of patients with unstable respiratory mechanics should be monitored during transport and MRI.

Measurements of the ripple effect and geometric distribution of switched gradient fields inside a magnetic resonance scanner.

Knowledge of patient exposure during magnetic resonance imaging (MRI) procedures is limited, and the need for such knowledge has been demonstrated in recent in vitro and in vivo studies of the genotoxic effects of MRI. This study focuses on the dB/dt of the switched gradient field (SGF) and its geometric distribution. These values were characterized by measuring the peak dB/dt generated by a programmed gradient current of alternating triangles inside a 1.5T MR scanner. The maximum dB/dt exposure to the gradient field was 6-14 T/s, and this occurred at the edges of the field of view (FOV) 20-25 cm from the isocenter in the longitudinal direction. The dB/dt exposure dropped off to roughly half the maximum (3-7 T/s) at the edge of the bore. It was found that the dB/dt of the SGF was distorted by a 200 kHz ripple arising from the amplifier. The ripple is small in terms of B-field, but the high frequency content contributes to a peak dB/dt up to 18 times larger than that predicted by the slew rate (4 T/s m) and the distance from the isocenter. Measurements on a 3 T MRI scanner, however, revealed a much smaller filtered ripple of 100 kHz in dB/dt. These findings suggest that the gradient current to each coil together with information on the geometrical distribution of the gradient field and ripple effects could be used to assess the SGF exposure within an MRI bore.

Pharmacologic MRI (phMRI) as a tool to differentiate Parkinson's disease–related from age-related changes in basal ganglia function

The prevalence of both parkinsonian signs and Parkinson's disease (PD) per se increases with age. Although the pathophysiology of PD has been studied extensively, less is known about the functional changes taking place in the basal ganglia circuitry with age. To specifically address this issue, 3 groups of rhesus macaques were studied: normal middle-aged animals (used as controls), middle-aged animals with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)–induced parkinsonism, and aged animals (>20 years old) with declines in motor function. All animals underwent the same behavioral and pharmacologic magnetic resonance imaging (phMRI) procedures to measure changes in basal ganglia function in response to dopaminergic drug challenges consisting of apomorphine administration followed by either a D1 (SCH23390) or a D2 (raclopride) receptor antagonist. Significant functional changes were predominantly seen in the external segment of the globus pallidus (GPe) in aged animals and in the striatum (caudate nucleus and putamen) in MPTP-lesioned animals. Despite significant differences seen in the putamen and GPe between MPTP-lesioned versus aged animals, a similar response profile to dopaminergic stimulations was found between these 2 groups in the internal segment of the GP. In contrast, the pharmacologic responses seen in the control animals were much milder compared with the other 2 groups in all the examined areas. Our phMRI findings in MPTP-lesioned parkinsonian and aged animals suggest that changes in basal ganglia function in the elderly may differ from those seen in parkinsonian patients and that phMRI could be used to distinguish PD from other age-associated functional alterations in the brain.

An optically coupled sensor for the measurement of currents induced by MRI gradient fields into endocardial leads.

The gradient fields generated during magnetic resonance imaging (MRI) procedures have the potential to induce electrical current on implanted endocardial leads. Whether this current can result in undesired cardiac stimulation is unknown. This paper provides a detailed description of how to construct an optically coupled sensor for the measurement of gradient-field-induced currents into endocardial leads. The system is based on a microcontroller that works as analog-to-digital converter and sends the current signal acquired from the lead to an optical high-speed, light-emitting diode transmitter. A plastic fiber guides the light outside the MRI chamber to a photodiode receiver and then to an acquisition board connected to a PC laptop. The performance of the system has been characterized in terms of power consumption (8 mA on average), sampling frequency (20.5 kHz), measurement range (-12.8 to 10.3 mA) and resolution (22.6 µA). Results inside a 3 T MRI scanner are also presented. The detailed description of the current sensor could permit more standardized study of MRI gradient current induction in pacemaker systems. Results show the potential of gradient currents to affect the pacemaker capability of triggering a heartbeat, by modifying the overall energy delivered by the stimulator.

Normal anatomy of the shoulder joint through the prism of magnetic resonance imaging

Magnetic resonance imaging (MRI) is a modern high-tech medical imaging technique which is characterized by the absence of radiation exposure, and is highly effective for the detection of pathology of soft tissue structures of the shoulder joint. Shoulder joint structures in different planes in different types of pulse sequences have differences in the display. Experience of carrying out of such studies in most radiological professionals is slight. In modern orthopedics they use a variety of techniques of arthroscopic treatment of pathology of the shoulder joint and during surgeries they often find its damaged soft tissue structures that are not diagnosed before surgery. Objective: To analyze the imaging features of normal anatomical structures of the shoulder joint in standard MRI procedure. Methods: Based on the analysis of the scientific and methodological literature there was considered the principle of MRI method, its physical properties and peculiarities of the study of the bone-joint system, and compared of anatomical structures of the shoulder joint with their display on the MRI slices in three standard planes in normal condition. Results: There was presented generalized description of the anatomical structures of the shoulder joint in normal condition. There were examined and detailed anatomical features of display on the MRI of certain structures of the shoulder joint in normal condition. Conclusions: The correct MRI conclusion is an important criterion for an accurate preoperative diagnosis, which will allow to apply the appropriate method of treatment, to plan the amount of surgery, and to determine the prognosis of the disease.

O-162 Clinical Implications Of Mri-procedure In Preterm Neonates

Background and aim Magnetic Resonance Imaging (MRI) of the brain at 30 weeks Postmenstrual age (PMA) is part of routine care for preterms born The aim was to evaluate fluctuations in vital parameters following the MRI procedure. Methods and patients We compared clinical parameters in 30 infants 4 h before and after the MRI: number of apneas and bradycardias, changes in oxygen requirement, respiratory support, and rectal temperature. Oral chloralhydrate sedation (30–50 mg/kg) was administered upon discretion of the attending neonatologist. Results Infants had the following clinical characteristics: mean GA 26 + 4 wks (24–28 wks), mean BW 1012 g (610–1520 g), PMA at scan was 30 + 6 wks (29 + 6–31 + 6 wks) with weight of 1397 g (980–1860 g). Infants None of the infants had >4 apneas or >3 bradycardias before the MRI. After the MRI 5 infants (all unsedated) had >4 apneas (5–7 apneas), 2 infants (1 sedated) had >3 bradycardias (5–6). After the MRI, FiO 2 was increased in 10/30 patients, max change 0.06, more respiratory support was needed in 5 infants (3 sedated): PEEP from +4 to PEEP +5 cmH 2 O, and temperature was lower in 20/30 patients, max decrease 1,3°C (before 37.1°C (36.3–37.9°C) vs. 36.6°C (35.9–37.4°C)). Conclusions Early MRI scanning using an MRI incubator is a relatively safe procedure in clinically stable infants. Use of sedation was not associated with clinically relevant changes, although these findings warrant further investigation.