Patient safety issues in magnetic resonance imaging: state of the art

Clinical outcome and safety of holmium laser prostate enucleation after transrectal prostate biopsies for benign prostatic hyperplasia

PURPOSE

This study aimed to assess the clinical outcome and safety of holmium laser enucleation of the prostate (HoLEP) following transrectal ultrasound-guided prostate biopsy (TR biopsy) in the treatment of benign prostate hyperplasia.

MATERIALS AND METHODS

We retrospectively analyzed data from 556 patients who underwent HoLEP between 2014 and 2021. The patients were categorized into six groups: Group 1-A (n=45) underwent HoLEP within four months post TR biopsy. Group 1-B (n=94) underwent HoLEP more than four months post TR biopsy. Group 1-C (n=120) underwent HoLEP after a single TR biopsy. Group 1-D (n=19) underwent HoLEP after two or more TR biopsies. Group 1-total (n=139, group 1-A+group 1-B or group 1-C+group 1-D) underwent HoLEP post TR biopsy. Group 2 (control group, n=417) underwent HoLEP without prior TR biopsy. We examined perioperative parameters, safety, and functional outcomes.

RESULTS

The age, body mass index, International Prostate Symptom Score (IPSS), uroflowmetry, and comorbid diseases between group 1-total and group 2 were comparable. However, group 1-total exhibited significantly elevated prostate-specific antigen levels and larger prostate volumes (p<0.01). Perioperative factors like enucleation time, enucleation weight, and catheterization duration were notably higher in group 1-total (p<0.01). All groups showed significant improvements in IPSS, postvoid residual urine, and maximum flow rate during the 1-year postoperative period (p<0.05). The rates of postoperative complications were similar between group 1-total and group 2.

CONCLUSIONS

Enucleation time and catheterization duration were significantly longer in the TR biopsy group. However, postoperative complications were not significantly different between TR biopsy and non-TR biopsy groups.

Comparison of multifidus muscle intramuscular fat by ultrasound echo intensity and fat-water based MR images in individuals with chronic low back pain

PURPOSE

The aim of this observational cross-sectional study was to examine correlations of intramuscular fat content in lumbar multifidus (LM) by comparing muscle echo intensity (EI) and percent fat signal fraction (%FSF) generated from ultrasound (US) and magnetic resonance (MR) images, respectively.

METHODS

MRI and US images from 25 participants (16 females, 9 males) selected from a cohort of patients with chronic low back pain (CLBP) were used. Images were acquired bilaterally, at the L4 and L5 levels (e.g., 4 sites). EI measurements were acquired by manually tracing the cross-sectional border of LM. Mean EI of three US images per site were analyzed (e.g., raw EI). A correction factor for subcutaneous fat thickness (SFT) was also calculated and applied (e.g., corrected EI). Corresponding fat and water MR images were used to acquire %FSF measurements. Intra-rater reliability was assessed by intraclass coefficients (ICC). Pearson correlations and simple linear regression were used to assess the relationship between %FSF, raw EI and corrected EI measurements.

RESULTS

The intra-rater ICCs for all measurements were moderate to excellent. Correlations between %FSF vs. raw EI and corrected EI were moderate to strong (0.40 < r < 0.52) and (0.40 < r < 0.51), respectively. Moderate correlations between SFT and EI were also identified.

CONCLUSION

US is a low-cost, non-invasive, accessible, and reliable method to examine muscle composition, and presents a promising solution for assessing and monitoring the effect of different treatment options for CLBP in clinical settings.

Low-Field Magnetic Resonance Imaging: Its History and Renaissance

ABSTRACT

Low-field magnetic resonance imaging (MRI) systems have seen a renaissance recently due to improvements in technology (both hardware and software). Originally, the performance of low-field MRI systems was rated lower than their actual clinical usefulness, and they were viewed as low-cost but poorly performing systems. However, various applications similar to high-field MRI systems (1.5 T and 3 T) have gradually become possible, culminating with high-performance low-field MRI systems and their adaptations now being proposed that have unique advantages over high-field MRI systems in various aspects. This review article describes the physical characteristics of low-field MRI systems and presents both their advantages and disadvantages for clinical use (past to present), along with their cutting-edge clinical applications.

Right ventricular shotgun pellet embolism: Case report and radiological aspect

Pellet embolism to the heart following gunshot injuries is an unusual event that requires a fast diagnosis. Imaging assessment is necessary to locate the projectiles and look for associated injuries. We present a case of a 41-year-old woman admitted after sustaining 2 gunshot wounds in the abdomen and left thigh, with the initial computed tomography (CT) scan showing a metallic object next to the right ventricle. Further radiological evaluation included transthoracic echocardiography and electrocardiogram-gated cardiac CT scan which confirmed the diagnosis of a migrating pellet to the right ventricle, entrapped within the trabeculations. Electrocardiogram-gated cardiac CT has a major role in detailed evaluation of bullet embolism to the heart cavities and guides the management.

Patients' perceptions and attitude towards MRI safety in Asir Region, Saudi Arabia

PURPOSE

To assess the knowledge and attitudes of Saudi patients toward the safety of magnetic resonance imaging (MRI).

METHODS

A cross-sectional study was conducted on 142 Saudi patients at King Khalid hospital, Asir, Saudi Arabia. Data were collected using a self-questionnaire based on MRI safety issues gained from the literature. The questionnaire was divided into two sections, one containing the respondents' sociodemographic information and the other assessing their knowledge and attitudes toward participating in MRI.

RESULTS

A total of 142 patients responded to the survey, and their average age was 31.5 ± 4 years. The majority were married and held a bachelor's degree. The mean knowledge score regarding MRI safety was 0.29 ± 0.25, which reflects poor knowledge, whereas the attitude score was 0.67 ± 0.20, reflecting a moderately positive attitude. Awareness and attitude among patients improved as education levels increased. Finally, only 53.5% of the respondents were aware of the noise produced by the MRI scanner.

CONCLUSION

This study demonstrated that the awareness of MRI safety among patients in the Asir Region is poor, although they showed positive attitudes toward the issue. Thus, education is necessary for patients to improve awareness of MRI safety to facilitate MRI examinations, which will help decrease scan time and image artefacts.

The application of in utero magnetic resonance imaging in the study of the metabolic and cardiovascular consequences of the developmental origins of health and disease

Observing fetal development in utero is vital to further the understanding of later-life diseases. Magnetic resonance imaging (MRI) offers a tool for obtaining a wealth of information about fetal growth, development, and programming not previously available using other methods. This review provides an overview of MRI techniques used to investigate the metabolic and cardiovascular consequences of the developmental origins of health and disease (DOHaD) hypothesis. These methods add to the understanding of the developing fetus by examining fetal growth and organ development, adipose tissue and body composition, fetal oximetry, placental microstructure, diffusion, perfusion, flow, and metabolism. MRI assessment of fetal growth, organ development, metabolism, and the amount of fetal adipose tissue could give early indicators of abnormal fetal development. Noninvasive fetal oximetry can accurately measure placental and fetal oxygenation, which improves current knowledge on placental function. Additionally, measuring deficiencies in the placenta’s transport of nutrients and oxygen is critical for optimizing treatment. Overall, the detailed structural and functional information provided by MRI is valuable in guiding future investigations of DOHaD.

MRI-related FDA adverse event reports: A 10-yr review

PURPOSE

To provide an overview of the types of adverse events reported to the US Food and Drug Administration (US FDA) for magnetic resonance (MR) systems over a 10-yr period.

METHODS

Two reviewers independently reviewed adverse events reported to FDA for MR systems from 1 January 2008 to 31 December 2017 and manually categorized events into eight event types. Thermal events were further subcategorized by probable cause. Objects that became projectiles were also categorized.

RESULTS

FDA received 1568 adverse event reports for MR systems between 1 January 2008 and 31 December 2017. This analysis included 1548 reports. Thermal events were the most commonly reported serious injury (59% of analyzed reports). Mechanical events - defined as slips, falls, crush injuries, broken bones, and cuts; musculoskeletal injuries from lifting or movement of the device - (11%), projectile events (9%), and acoustic events (6%) were also observed.

CONCLUSIONS

Adverse events related to MR systems consistent with the known hazards of the MR environment continue to be reported to FDA. Increased awareness of the types of adverse events occurring for MR imaging systems is important for prevention.

Clinical Practice Guideline: Hoarseness (Dysphonia) (Update)

Objective

This guideline provides evidence-based recommendations on treating patients who present with dysphonia, which is characterized by altered vocal quality, pitch, loudness, or vocal effort that impairs communication and/or quality of life. Dysphonia affects nearly one-third of the population at some point in its life. This guideline applies to all age groups evaluated in a setting where dysphonia would be identified or managed. It is intended for all clinicians who are likely to diagnose and treat patients with dysphonia.

Purpose

The primary purpose of this guideline is to improve the quality of care for patients with dysphonia, based on current best evidence. Expert consensus to fill evidence gaps, when used, is explicitly stated and supported with a detailed evidence profile for transparency. Specific objectives of the guideline are to reduce inappropriate variations in care, produce optimal health outcomes, and minimize harm. For this guideline update, the American Academy of Otolaryngology—Head and Neck Surgery Foundation selected a panel representing the fields of advanced practice nursing, bronchoesophagology, consumer advocacy, family medicine, geriatric medicine, internal medicine, laryngology, neurology, otolaryngology–head and neck surgery, pediatrics, professional voice, pulmonology, and speech-language pathology.

Action Statements

The guideline update group made strong recommendations for the following key action statements (KASs): (1) Clinicians should assess the patient with dysphonia by history and physical examination to identify factors where expedited laryngeal evaluation is indicated. These include, but are not limited to, recent surgical procedures involving the head, neck, or chest; recent endotracheal intubation; presence of concomitant neck mass; respiratory distress or stridor; history of tobacco abuse; and whether the patient is a professional voice user. (2) Clinicians should advocate voice therapy for patients with dysphonia from a cause amenable to voice therapy. The guideline update group made recommendations for the following KASs: (1) Clinicians should identify dysphonia in a patient with altered voice quality, pitch, loudness, or vocal effort that impairs communication or reduces quality of life (QOL). (2) Clinicians should assess the patient with dysphonia by history and physical examination for underlying causes of dysphonia and factors that modify management. (3) Clinicians should perform laryngoscopy, or refer to a clinician who can perform laryngoscopy, when dysphonia fails to resolve or improve within 4 weeks or irrespective of duration if a serious underlying cause is suspected. (4) Clinicians should perform diagnostic laryngoscopy, or refer to a clinician who can perform diagnostic laryngoscopy, before prescribing voice therapy and document/communicate the results to the speech-language pathologist (SLP). (5) Clinicians should advocate for surgery as a therapeutic option for patients with dysphonia with conditions amenable to surgical intervention, such as suspected malignancy, symptomatic benign vocal fold lesions that do not respond to conservative management, or glottic insufficiency. (6) Clinicians should offer, or refer to a clinician who can offer, botulinum toxin injections for the treatment of dysphonia caused by spasmodic dysphonia and other types of laryngeal dystonia. (7) Clinicians should inform patients with dysphonia about control/preventive measures. (8) Clinicians should document resolution, improvement or worsened symptoms of dysphonia, or change in QOL of patients with dysphonia after treatment or observation. The guideline update group made a strong recommendation against 1 action: (1) Clinicians should not routinely prescribe antibiotics to treat dysphonia. The guideline update group made recommendations against other actions: (1) Clinicians should not obtain computed tomography (CT) or magnetic resonance imaging (MRI) for patients with a primary voice complaint prior to visualization of the larynx. (2) Clinicians should not prescribe antireflux medications to treat isolated dysphonia, based on symptoms alone attributed to suspected gastroesophageal reflux disease (GERD) or laryngopharyngeal reflux (LPR), without visualization of the larynx. (3) Clinicians should not routinely prescribe corticosteroids for patients with dysphonia prior to visualization of the larynx. The policy level for the following recommendation about laryngoscopy at any time was an option: (1) Clinicians may perform diagnostic laryngoscopy at any time in a patient with dysphonia.

Disclaimer

This clinical practice guideline is not intended as an exhaustive source of guidance for managing dysphonia (hoarseness). Rather, it is designed to assist clinicians by providing an evidence-based framework for decision-making strategies. The guideline is not intended to replace clinical judgment or establish a protocol for all individuals with this condition, and it may not provide the only appropriate approach to diagnosing and managing this problem. Differences from Prior Guideline (1) Incorporation of new evidence profiles to include the role of patient preferences, confidence in the evidence, differences of opinion, quality improvement opportunities, and any exclusion to which the action statement does not apply (2) Inclusion of 3 new guidelines, 16 new systematic reviews, and 4 new randomized controlled trials (3) Inclusion of a consumer advocate on the guideline update group (4) Changes to 9 KASs from the original guideline (5) New KAS 3 (escalation of care) and KAS 13 (outcomes) (6) Addition of an algorithm outlining KASs for patients with dysphonia

Fetal magnetic resonance imaging and ultrasound

Magnetic resonance imaging (MRI) has been increasingly adopted in obstetrics practice in the past three decades. MRI aids prenatal ultrasound and improves diagnostic accuracy for selected maternal and fetal conditions. However, it should be considered only when high-quality ultrasound cannot provide certain information that affects the counseling, prenatal intervention, pregnancy course, and delivery plan. Major indications of fetal MRI include, but are not restricted to, morbidly adherent placenta, selected cases of fetal brain anomalies, thoracic lesions (especially in severe congenital diaphragmatic hernia), and soft tissue tumors at head and neck regions of the fetus. For fetal anatomy assessment, a 1.5-Tesla machine with a fast T2-weighted single-shot technique is recommended for image requisition of common fetal abnormalities. Individual judgment needs to be applied when considering usage of a 3-Tesla machine. Gadolinium MRI contrast is not recommended during pregnancy. MRI should be avoided in the first half of pregnancy due to small fetal structures and motion artifacts. Assessment of fetal cerebral cortex can be achieved with MRI in the third trimester. MRI is a viable research tool for noninvasive interrogation of the fetus and the placenta.

Computer-assisted surgical planning and intraoperative guidance in fetal surgery: a systematic review

Fetal surgery has become a clinical reality, with interventions for twin‐to‐twin transfusion syndrome (TTTS) and spina bifida demonstrated to improve outcome. Fetal imaging is evolving, with the use of 3D ultrasound and fetal MRI becoming more common in clinical practise. Medical imaging analysis is also changing, with technology being developed to assist surgeons by creating 3D virtual models that improve understanding of complex anatomy, and prove powerful tools in surgical planning and intraoperative guidance.

We introduce the concept of computer‐assisted surgical planning, and present the results of a systematic review of image reconstruction for fetal surgical planning that identified six articles using such technology.

Indications from other specialities suggest a benefit of surgical planning and guidance to improve outcomes. There is therefore an urgent need to develop fetal‐specific technology in order to improve fetal surgical outcome. © 2015 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.

What's already known about this topic?

Fetal surgery has now become a clinical reality, with interventions such as laser treatment for twin‐to‐twin transfusion syndrome (TTTS) and open fetal surgery for spina bifida demonstrated in randomised control trials to improve neonatal outcome

Other specialities are increasingly utilising computer‐assisted surgical planning software, with evidence that this can improve outcome

What does this study add?

We feel that there is an urgent need to develop fetal‐specific technology for surgical planning as it is likely to play an important role in improving outcomes from fetal surgery

Fetal MRI: An approach to practice: A review

MRI has been increasingly used for detailed visualization of the fetus in utero as well as pregnancy structures. Yet, the familiarity of radiologists and clinicians with fetal MRI is still limited. This article provides a practical approach to fetal MR imaging. Fetal MRI is an interactive scanning of the moving fetus owed to the use of fast sequences. Single-shot fast spin-echo (SSFSE) T2-weighted imaging is a standard sequence. T1-weighted sequences are primarily used to demonstrate fat, calcification and hemorrhage. Balanced steady-state free-precession (SSFP), are beneficial in demonstrating fetal structures as the heart and vessels. Diffusion weighted imaging (DWI), MR spectroscopy (MRS), and diffusion tensor imaging (DTI) have potential applications in fetal imaging. Knowing the developing fetal MR anatomy is essential to detect abnormalities. MR evaluation of the developing fetal brain should include recognition of the multilayered-appearance of the cerebral parenchyma, knowledge of the timing of sulci appearance, myelination and changes in ventricular size. With advanced gestation, fetal organs as lungs and kidneys show significant changes in volume and T2-signal. Through a systematic approach, the normal anatomy of the developing fetus is shown to contrast with a wide spectrum of fetal disorders. The abnormalities displayed are graded in severity from simple common lesions to more complex rare cases. Complete fetal MRI is fulfilled by careful evaluation of the placenta, umbilical cord and amniotic cavity. Accurate interpretation of fetal MRI can provide valuable information that helps prenatal counseling, facilitate management decisions, guide therapy, and support research studies.

Magnetic resonance imaging: fundamental safety issues

Medical practitioners have a variety of imaging modalities at their disposal. The exquisite soft tissue delineation available with magnetic resonance imaging (MRI) has resulted in the rising utilization of this particular modality. Increasingly, physical therapists around the world are actively involved in not only referring patients with musculoskeletal conditions for MRI but also in the acquisition of MRI data in both the clinical and research arenas. The MRI process involves the use of a very strong static magnetic field, time-varying (gradient) fields, and radiofrequency energy. To ensure the well-being of patients, staff, and visitors, an understanding of the primary hazards of this environment and the rigorous safety procedures that must be followed is imperative to the clinician. This paper describes the basic components of an MRI system, discusses various MRI safety issues, and presents the screening procedure necessary prior to using MRI. Primary hazards associated with the imaging process are also reviewed. J Orthop Sports Phys Ther 2011;41(11):820-828. doi:10.2519/jospt.2011.3906.

Computed tomography in patients with cardiac pacemakers: difficulties and solutions

The presence of cardiac pacemaker systems may significantly limit interpretation of multi-slice computed tomography (MSCT) images. In 80 patients (45 men; aged 69.5 ± 13.4) with previously implanted anti-arrhythmic devices, a 64-slice CT (Aquilion-64) was performed. In 61 patients (76.3%), ECG gating was used (coronaries visualization) and in 19 patients (23.7%) without ECG gating (not coronaries visualization). In all 19 patients without ECG gating MSCT images were diagnostic. In 37 (60.6%) patients of 61, there was no problem with gating process and image quality was diagnostic. In 24 (39.4%) with visible spikes in the ECG-gating group, there were difficulties in differentiating the R spike from an artificial spike (unipolar pacing) by MSCT software. In 15 patients (24.6%) after reprogramming, it was possible to obtain good quality images. In nine (14.7%) patients, it was not possible to reprogram devices due to old unipolar leads, but in two cases (3.3%), ECG gating was corrected manually and good image quality was obtained. In seven (11.5%) patients, it was not possible to perform ECG gating. The ECG gating process was identified as the main cause of the imaging problems. Bipolar leads working as bipolar pacing seem to be necessary to perform MSCT with ECG gating. A unipolar system lead may cause serious problems with reconstructions.

Predicting clinical outcome in comatose cardiac arrest patients using early noncontrast computed tomography

BACKGROUND AND PURPOSE

Early assessment of the likelihood of neurological recovery in comatose cardiac arrest survivors remains challenging. We hypothesize that quantitative noncontrast computed tomography (NCCT) combined with neurological assessments, are predictive of outcome.

METHODS

We analyzed data sets acquired from comatose cardiac arrest patients who underwent CT within 72 hours of arrest. Images were semiautomatically segmented into anatomic regions. Median Hounsfield units (HU) were measured regionally and in the whole brain (WB). Outcome was based on the 6-month modified Rankin Scale (mRS) score. Logistic regression was used to combine Glasgow Coma Scale (GCS) score measured on Day 3 post arrest (GCS_Day3) with imaging to predict poor outcome (mRS>4).

RESULTS

WB HU (P=0.02) and the ratio of HU in the putamen to the posterior limb of the internal capsule (PLIC) (P=0.004) from 175 datasets from 151 patients were univariate predictors of poor outcome. Thirty-three patients underwent hypothermia treatment. Multivariate analysis showed that combining median HU in the putamen (P=0.0006) and PLIC (P=0.007) was predictive of poor outcome. Combining WB HU and GCS_Day3 resulted in 72% [61% to 80%] sensitivity and 100% [73% to 100%] specificity for predicting poor outcome in 86 patients with measurable GCS_Day3. This was an improvement over prognostic performance based on GCS_Day3≤8 (98% sensitive but 71% specific).

DISCUSSION

Combining density changes on CT with GCS_Day3 may be useful for predicting poor outcome in comatose cardiac arrest patients who are neither rapidly improving nor deteriorating. Improved prognostication with CT compared with neurological assessments can be achieved in patients treated with hypothermia.

Toward cardiovascular MRI at 7 T: clinical needs, technical solutions and research promises

OBJECTIVE

To consider potential clinical needs, technical solutions and research promises of ultrahigh-field strength cardiovascular MR (CMR).

METHODS

A literature review is given, surveying advantages and disadvantages of CMR at ultrahigh fields (UHF). Key concepts, emerging technologies, practical considerations and applications of UHF CMR are provided. Examples of UHF CMR imaging strategies and their added value are demonstrated, including the numerous unsolved problems. A concluding section explores future directions in UHF CMR.

RESULTS

UHF CMR can be regarded as one of the most challenging MRI applications. Image quality achievable at UHF is not always exclusively defined by signal-to-noise considerations. Some of the inherent advantages of UHF MRI are offset by practical challenges. But UHF CMR can boast advantages over its kindred lower field counterparts by trading the traits of high magnetic fields for increased temporal and/or spatial resolution.

CONCLUSIONS

CMR at ultrahigh-field strengths is a powerful motivator, since speed and signal may be invested to overcome the fundamental constraints that continue to hamper traditional CMR. If practical challenges can be overcome, UHF CMR will help to open the door to new approaches for basic science and clinical research.

Comparison of left ventricular function assessment using phonocardiogram- and electrocardiogram-triggered 2D SSFP CINE MR imaging at 1.5 T and 3.0 T

OBJECTIVE

As high-field cardiac MRI (CMR) becomes more widespread the propensity of ECG to interference from electromagnetic fields (EMF) and to magneto-hydrodynamic (MHD) effects increases and with it the motivation for a CMR triggering alternative. This study explores the suitability of acoustic cardiac triggering (ACT) for left ventricular (LV) function assessment in healthy subjects (n = 14).

METHODS

Quantitative analysis of 2D CINE steady-state free precession (SSFP) images was conducted to compare ACT's performance with vector ECG (VCG). Endocardial border sharpness (EBS) was examined paralleled by quantitative LV function assessment.

RESULTS

Unlike VCG, ACT provided signal traces free of interference from EMF or MHD effects. In the case of correct R-wave recognition, VCG-triggered 2D CINE SSFP was immune to cardiac motion effects-even at 3.0 T. However, VCG-triggered 2D SSFP CINE imaging was prone to cardiac motion and EBS degradation if R-wave misregistration occurred. ACT-triggered acquisitions yielded LV parameters (end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and left ventricular mass (LVM)) comparable with those derived from VCG-triggered acquisitions (1.5 T: ESV(VCG) = (56 +/- 17) ml, EDV(VCG) = (151 +/- 32) ml, LVM(VCG) = (97 +/- 27) g, SV(VCG) = (94 +/- 19) ml, EF(VCG) = (63 +/- 5)% cf. ESV(ACT) = (56 +/- 18) ml, EDV(ACT) = (147 +/- 36) ml, LVM(ACT) = (102 +/- 29) g, SV(ACT) = (91 +/- 22) ml, EF(ACT) = (62 +/- 6)%; 3.0 T: ESV(VCG) = (55 +/- 21) ml, EDV(VCG) = (151 +/- 32) ml, LVM(VCG) = (101 +/- 27) g, SV(VCG) = (96 +/- 15) ml, EF(VCG) = (65 +/- 7)% cf. ESV(ACT) = (54 +/- 20) ml, EDV(ACT) = (146 +/- 35) ml, LVM(ACT) = (101 +/- 30) g, SV(ACT) = (92 +/- 17) ml, EF(ACT) = (64 +/- 6)%).

CONCLUSIONS

ACT's intrinsic insensitivity to interference from electromagnetic fields renders it suitable for clinical CMR.

Radiofrequency-induced heating near fixed orthodontic appliances in high field MRI systems at 3.0 Tesla

OBJECTIVE

To assess radiofrequency (RF)-induced heating of fixed orthodontic appliances during acquisition of three different sequences in magnetic resonance imaging (MRI) at 3 Tesla.

MATERIALS AND METHODS

Ten commonly used fixed orthodontic appliances were investigated utilizing a phantom head and simulating the in vivo intraoral situation. A 3 Tesla MRI system (Intera, Philips Medical Systems, Best, The Netherlands) was used to acquire T1w spin-echo (T1 SE), T1w turbo spin-echo (T1 TSE) and T1w gradient-echo (T1 GRE) sequences in axial orientation. Continuous temperature measurement was performed with a dedicated four channel fluoroptic thermometry system. For each orthodontic appliance temperature probes were placed at three predefined sites in order to perform temperature measurements during MR imaging. The fourth temperature probe was fixed to the neck of the phantom head and served as the reference. Mean temperature alterations were determined for all appliances.

RESULTS

Temperature elevations ranged from -0.3 degrees C to 0.2 degrees C and were negligible for all orthodontic appliances investigated. There was no difference in mean temperature alteration for any of the three imaging sequences.

CONCLUSION

Based on the data of our experimental study the radiofrequency-induced heating of orthodontic brackets during high field MRI at 3 Tesla can be categorized as negligibly low. Even the clinical routine examination of the head at 3 Tesla using high-energetic pulse sequences can be applied without hesitation in patients with fixed orthodontic appliances.

Feasibility of cardiac gating free of interference with electro-magnetic fields at 1.5 Tesla, 3.0 Tesla and 7.0 Tesla using an MR-stethoscope

OBJECTIVES

To circumvent the challenges of conventional electrocardiographic (ECG)-gating by examining the efficacy of an MR stethoscope, which offers (i) no risk of high voltage induction or patient burns, (ii) immunity to electromagnetic interference, (iii) suitability for all magnetic field strengths, and (iv) patient comfort together with ease of use for the pursuit of reliable and safe (ultra)high field cardiac gated magnetic resonance imaging (MRI).

MATERIALS AND METHODS

The acoustic gating device consists of 3 main components: an acoustic sensor, a signal processing unit, and a coupler unit to the MRI system. Signal conditioning and conversion are conducted outside the 0.5 mT line using dedicated electronic circuits. The final waveform is delivered to the internal physiological signal controller circuitry of a clinical MR scanner. Cardiovascular MRI was performed of normal volunteers (n = 17) on 1.5 T, 3.0 T and 7.0 T whole body MR systems. Black blood imaging, 2D CINE imaging, 3D phase contrast MR angiography, and myocardial T2* mapping were carried out.

RESULTS

The MR-stethoscope provided cardiograms at 1.5 T, 3.0 T and 7.0 T free of interference from electromagnetic fields and magneto-hydrodynamic effects. In comparison, ECG waveforms were susceptible to T-wave elevation and other distortions, which were more pronounced at higher fields. Acoustically gated black blood imaging at 1.5 T and 3.0 T provided image quality comparable with or even superior to that obtained from the ECG-gated approach. In the case of correct R-wave recognition, ECG-gated 2D CINE SSFP imaging was found to be immune to cardiac motion effects -even at 3.0 T. However, ECG-gated 2D SSFP CINE imaging was prone to cardiac motion artifacts if R-wave mis-registration occurred because of T-wave elevation. Acoustically gated 3D PCMRA at 1.5 T, 3.0 T and 7.0 T resulted in images free of blood pulsation artifacts because the acoustic gating approach provided cardiac signal traces free of interference with electromagnetic fields or magneto-hydrodynamic effects even at 7.0 Tesla. Severe ECG-trace distortions and T-wave elevations occurred at 3.0 T and 7.0 T. Acoustically cardiac gated T2* mapping at 3.0 T yielded a T2* value of 22.3 +/- 4.8 ms for the inferoseptal myocardium.

CONCLUSIONS

The proposed MR-stethoscope presents a promising alternative to currently available techniques for cardiac gating of (ultra)high field MRI. Its intrinsic insensitivity to interference from electromagnetic fields renders it suitable for clinical imaging because of its excellent trigger reliability, even at 7.0 Tesla.

Noninvasive in vivo small animal MRI and MRS: basic experimental procedures

Small animal Magnetic Resonance (MR) research has emerged as an important element of modern biomedical research due to its non-invasive nature and the richness of biological information it provides. MR does not require any ionizing radiation and can noninvasively provide higher resolution and better signal-to-noise ratio in comparison to other tomographic or spectroscopic modalities. In this protocol, we will focus on small animal MR imaging and MR spectroscopy (MRI/MRS) to noninvasively acquire relaxation weighted (1)H images of mouse and to obtain (31)P spectra of mouse muscle. This work does not attempt to cover every aspect of small animal MRI/MRS but rather introduces basic procedures of mouse MRI/MRS experiments. The main goal of this work is to inform researchers of the basic procedures for in vivo MR experiments on small animals. The goal is to provide a better understanding of basic experimental procedures to allow researchers new to the MR field to better plan for non-MR components of their studies so that both MR and non-MR procedures are seamlessly integrated.

Clinical Practice Guideline: Hoarseness (Dysphonia)

Objective:

This guideline provides evidence-based recommendations on managing hoarseness (dysphonia), defined as a disorder characterized by altered vocal quality, pitch, loudness, or vocal effort that impairs communication or reduces voice-related quality of life (QOL). Hoarseness affects nearly one-third of the population at some point in their lives. This guideline applies to all age groups evaluated in a setting where hoarseness would be identified or managed. It is intended for all clinicians who are likely to diagnose and manage patients with hoarseness.

Purpose:

The primary purpose of this guideline is to improve diagnostic accuracy for hoarseness (dysphonia), reduce inappropriate antibiotic use, reduce inappropriate steroid use, reduce inappropriate use of anti-reflux medications, reduce inappropriate use of radiographic imaging, and promote appropriate use of laryngoscopy, voice therapy, and surgery. In creating this guideline the American Academy of Otolaryngology—Head and Neck Surgery Foundation selected a panel representing the fields of neurology, speech-language pathology, professional voice teaching, family medicine, pulmonology, geriatric medicine, nursing, internal medicine, otolaryngology–head and neck surgery, pediatrics, and consumers.

Results

The panel made strong recommendations that 1) the clinician should not routinely prescribe antibiotics to treat hoarseness and 2) the clinician should advocate voice therapy for patients diagnosed with hoarseness that reduces voice-related QOL. The panel made recommendations that 1) the clinician should diagnose hoarseness (dysphonia) in a patient with altered voice quality, pitch, loudness, or vocal effort that impairs communication or reduces voice-related QOL; 2) the clinician should assess the patient with hoarseness by history and/or physical examination for factors that modify management, such as one or more of the following: recent surgical procedures involving the neck or affecting the recurrent laryngeal nerve, recent endotracheal intubation, radiation treatment to the neck, a history of tobacco abuse, and occupation as a singer or vocal performer; 3) the clinician should visualize the patient's larynx, or refer the patient to a clinician who can visualize the larynx, when hoarseness fails to resolve by a maximum of three months after onset, or irrespective of duration if a serious underlying cause is suspected; 4) the clinician should not obtain computed tomography or magnetic resonance imaging of the patient with a primary complaint of hoarseness prior to visualizing the larynx; 5) the clinician should not prescribe anti-reflux medications for patients with hoarseness without signs or symptoms of gastroesophageal reflux disease; 6) the clinician should not routinely prescribe oral corticosteroids to treat hoarseness; 7) the clinician should visualize the larynx before prescribing voice therapy and document/communicate the results to the speech-language pathologist; and 8) the clinician should prescribe, or refer the patient to a clinician who can prescribe, botulinum toxin injections for the treatment of hoarseness caused by adductor spasmodic dysphonia. The panel offered as options that 1) the clinician may perform laryngoscopy at any time in a patient with hoarseness, or may refer the patient to a clinician who can visualize the larynx; 2) the clinician may prescribe anti-reflux medication for patients with hoarseness and signs of chronic laryngitis; and 3) the clinician may educate/counsel patients with hoarseness about control/preventive measures.

Disclaimer:

This clinical practice guideline is not intended as a sole source of guidance in managing hoarseness (dysphonia). Rather, it is designed to assist clinicians by providing an evidence-based framework for decision-making strategies. The guideline is not intended to replace clinical judgment or establish a protocol for all individuals with this condition, and may not provide the only appropriate approach to diagnosing and managing this problem.