Sedation and analgesia in MR imaging

Patient preferences for development in MRI scanner design: a survey of claustrophobic patients in a randomized study

OBJECTIVE

To investigate which magnetic resonance imaging (MRI) scanner designs claustrophobic patients prefer.

MATERIAL/METHODS

We analyzed questionnaires completed by 160 patients at high risk for claustrophobia directly after a scan in either a short-bore or open panoramic scanner as part of a prospective randomized trial Enders et al (BMC Med Imaging 11:4, 2011). Scanner preferences were judged based on schematic drawings of four scanners. Information on the diagnostic performance of the depicted scanners was provided, too.

RESULTS

A majority of patients suggested upright open (59/160, 36.9%) and open panoramic (53/160, 33.1%) before short-bore designs (26/160, 16.3%, for all p < 0.001) for future development. When asked about patients' preferred scanner choice for an upcoming examination, information about a better diagnostic performance of a short-bore scanner significantly improved its preference rates (from 6/160 to 49/160 or 3.8 to 30.5%, p < 0.001). Patients with a claustrophobic event preferred open designs significantly more often than patients without a claustrophobic event (p = 0.047). Patients scanned in a short-bore scanner in our trial preferred this design significantly more often (p = 0.003). Noise reduction (51/160, 31.9%), more space over the head (44/160, 27.5%), and overall more space (33/160, 20.6%) were the commonest suggested areas of improvement.

CONCLUSION

Patients at high risk for claustrophobia visually prefer open- over short-bore MRI designs for further development. Education about a better diagnostic performance of a visually less-attractive scanner can increase its acceptance. Noise and space were of most concern for claustrophobic patients. This information can guide individual referral of claustrophobic patients to scanners and future scanner development.

KEY POINTS

• Patients at high risk for claustrophobia visually favor the further development of open scanners as opposed to short- and closed-bore scanner designs. • Educating claustrophobic patients about a higher diagnostic performance of a short-bore scanner can significantly increase their acceptance of this otherwise visually less-attractive design. • A medical history of earlier claustrophobic events in a given MRI scanner type and focusing on the features "more space" and "noise reduction" can help to guide referral of patients who are at high risk for claustrophobia.

Prevalence and Financial Impact of Claustrophobia, Anxiety, Patient Motion, and Other Patient Events in Magnetic Resonance Imaging

Claustrophobia, other anxiety reactions, excessive motion, and other unanticipated patient events in magnetic resonance imaging (MRI) not only delay or preclude diagnostic-quality imaging but can also negatively affect the patient experience. In addition, by impeding MRI workflow, they may affect the finances of an imaging practice. This review article offers an overview of the various types of patient-related unanticipated events that occur in MRI, along with estimates of their frequency of occurrence as documented in the available literature. In addition, the financial implications of these events are discussed from a microeconomic perspective, primarily from the point of view of a radiology practice or hospital, although associated limitations and other economic viewpoints are also included. Efforts to minimize these unanticipated patient events can potentially improve not only patient satisfaction and comfort but also an imaging practice's operational efficiency and diagnostic capabilities.

Modified technique for imaging the wrist and elbow in obese and claustrophobic patients using a non-open standard MRI scanner

OBJECTIVE

It is challenging to image extremely obese and claustrophobic patients using a standard, non-open, magnetic resonance imaging (MRI) scanner. On the other hand, installing an additional upright or open MRI scanner may not be cost-effective for most practices. Our technique with a patient in a sitting or standing position behind the standard MRI scanner may be helpful in the MR examination of the wrist/elbow in these patients using a standard wrist/elbow coil.

MATERIAL AND METHODS

We performed wrist and elbow MRI of extremely obese and claustrophobic patients by using our modified technique with the patient sitting or standing outside the standard non-open MRI scanner. A total number of 20 cases with the following diagnosis were examined: triquetral and scaphoid bone contusions and fractures, scapholunate ligament tears, triangular fibrocartilage complex tear, and biceps tear.

RESULTS

Comparison of image quality for diagnostic information between the standard technique and our technique showed no significant difference, which is necessary for making the diagnosis.

CONCLUSIONS

Our technique enables wrist and elbow imaging of extremely obese and claustrophobic patients who cannot otherwise be imaged using a standard MRI scanner without compromising the image quality that is essential for making a diagnosis.

Reduction of claustrophobia with short-bore versus open magnetic resonance imaging: a randomized controlled trial

BACKGROUND

Claustrophobia is a common problem precluding MR imaging. The purpose of the present study was to assess whether a short-bore or an open magnetic resonance (MR) scanner is superior in alleviating claustrophobia.

METHODS

Institutional review board approval and patient informed consent were obtained to compare short-bore versus open MR. From June 2008 to August 2009, 174 patients (139 women; mean age = 53.1 [SD 12.8]) with an overall mean score of 2.4 (SD 0.7, range 0 to 4) on the Claustrophobia Questionnaire (CLQ) and a clinical indication for imaging, were randomly assigned to receive evaluation by open or by short-bore MR. The primary outcomes were incomplete MR examinations due to a claustrophobic event. Follow-up was conducted 7 months after MR imaging. The primary analysis was performed according to the intention-to-treat strategy.

RESULTS

With 33 claustrophobic events in the short-bore group (39% [95% confidence interval [CI] 28% to 50%) versus 23 in the open scanner group (26% [95% CI 18% to 37%]; P = 0.08) the difference was not significant. Patients with an event were in the examination room for 3.8 min (SD 4.4) in the short-bore and for 8.5 min (SD 7) in the open group (P = 0.004). This was due to an earlier occurrence of events in the short-bore group. The CLQ suffocation subscale was significantly associated with the occurrence of claustrophobic events (P = 0.003). New findings that explained symptoms were found in 69% of MR examinations and led to changes in medical treatment in 47% and surgery in 10% of patients. After 7 months, perceived claustrophobia increased in 32% of patients with events versus in only 11% of patients without events (P = 0.004).

CONCLUSIONS

Even recent MR cannot prevent claustrophobia suggesting that further developments to create a more patient-centered MR scanner environment are needed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00715806.

Reduction of claustrophobia during magnetic resonance imaging: methods and design of the "CLAUSTRO" randomized controlled trial

Background

Magnetic resonance (MR) imaging has been described as the most important medical innovation in the last 25 years. Over 80 million MR procedures are now performed each year and on average 2.3% (95% confidence interval: 2.0 to 2.5%) of all patients scheduled for MR imaging suffer from claustrophobia. Thus, prevention of MR imaging by claustrophobia is a common problem and approximately 2,000,000 MR procedures worldwide cannot be completed due to this situation. Patients with claustrophobic anxiety are more likely to be frightened and experience a feeling of confinement or being closed in during MR imaging. In these patients, conscious sedation and additional sequences (after sedation) may be necessary to complete the examinations. Further improvements in MR design appear to be essential to alleviate this situation and broaden the applicability of MR imaging. A more open scanner configuration might help reduce claustrophobic reactions while maintaining image quality and diagnostic accuracy.

Methods/Design

We propose to analyze the rate of claustrophobic reactions, clinical utility, image quality, patient acceptance, and cost-effectiveness of an open MR scanner in a randomized comparison with a recently designed short-bore but closed scanner with 97% noise reduction. The primary aim of this study is thus to determine whether an open MR scanner can reduce claustrophobic reactions, thereby enabling more examinations of claustrophobic patients without incurring the safety issues associated with conscious sedation. In this manuscript we detail the methods and design of the prospective "CLAUSTRO" trial.

Discussion

This randomized controlled trial will be the first direct comparison of open vertical and closed short-bore MR systems in regards to claustrophobia and image quality as well as diagnostic utility.

Trial Registration

ClinicalTrials.gov: NCT00715806

Evaluation of adult outpatient magnetic resonance imaging sedation practices: are patients being sedated optimally?

PURPOSE

To evaluate the use of anxiolytics in adult outpatient magnetic resonance imaging (MRI) centres and to determine whether utilisation is optimal based on the pharmacology of the drugs used, who prescribes these drugs, and how patients are managed after administration.

MATERIALS AND METHODS

Identical paper and Web-based surveys were used to anonymously collect data about radiologists' use of anxiolytic agents for adult outpatient MRI examinations. The survey questions were about the type of facility, percentage of studies that require sedation, the drug used and route of administration, who orders the drug, timing of administration, patient monitoring during and observation after the study, use of a dedicated nurse for monitoring, and use of standard sedation and discharge protocols. The chi(2) analysis for statistical association among variables was used.

RESULTS

Eighty-five of 263 surveys were returned (32% response rate). The radiologist ordered the medication (53%) in slightly more facilities than the referring physician (44%) or the nurse. Forty percent of patients received medication 15-30 minutes before MRI, which is too early for peak effect of oral or sublingual drugs. Lorazepam was most commonly used (64% first choice). Facilities with standard sedation protocols (56%) were more likely to use midazolam than those without standard sedation protocols (17% vs 10%), to have a nurse for monitoring (P = .032), to have standard discharge criteria (P = .001), and to provide written information regarding adverse effects (P = .002).

CONCLUSIONS

Many outpatients in MRI centres may be scanned before the peak effect of anxiolytics prescribed. A standard sedation protocol in such centres is associated with a more appropriate drug choice, as well as optimized monitoring and postprocedure care.

The use of sedation in the radiology department

The use of intravenous sedation and analgesia in patients undergoing interventional diagnostic and therapeutic procedures is increasing. Sedation by non-anaesthetists is considered to be safe, provided that they have received adequate training and have the necessary equipment, facilities, and personnel. This article aims to increase awareness of the safe use of sedative drugs in radiology and provide a practical guideline for minimal and moderate sedation.

Conscious sedation for patients undergoing enteroclysis: comparing the safety and patient-reported effectiveness of two protocols

OBJECTIVE

To compare the safety and patient-reported effectiveness of two regimens for conscious sedation during enteroclysis.

MATERIALS AND METHODS

We surveyed two groups of outpatients and retrospectively reviewed procedure records for conscious sedation and complications. Patients were divided into Group One (received sedative/amnesic diazepam), and Group Two, (received amnesic/sedative, midazolam and analgesic fentanyl).

RESULTS

All enteroclyses were successfully completed; there were no hospital admissions due to complications. In Group One (n=106), mean dose of diazepam was 12.7 mg. 25% had oxygen desaturation (n=25), and post-procedure vomiting without aspiration (n=1). 56% of outpatients completed phone surveys, and 68% recalled procedural discomfort. In Group Two (n=45), mean doses were 3.9 mg midazolam and 108 mcg fentanyl. 31% had desaturation (n=13), and post-procedure vomiting without aspiration (n=1). 87% had only a vague recall of the procedure or of any discomfort.

CONCLUSION

A combination of amnesic and fentanyl prevented the recall of discomfort of nasoenteric intubation and infusion in most patients who had enteroclysis compared to diazepam. Most of the patients would undergo the procedure again, if needed.

Magnetic resonance imaging anesthesia: new challenges and techniques

PURPOSE OF REVIEW

The increasing use of magnetic resonance imaging as a diagnostic modality has led to increased demand for sedation and monitoring during the procedure. This review is to acquaint the reader with the most recent developments in magnetic resonance imaging diagnostics and to describe the evolving techniques and strategies for patient management.

RECENT FINDINGS

Many centers are meeting the challenges of increasing demand by streamlining their sedation/anesthetic protocols to achieve greater efficiency. Some have enlisted the help of nursing staff who are trained to provide sedation for certain patients. Continued experience in magnetic resonance imaging anesthesia has led to a better understanding of patient needs and decreased the number of failed procedures. The scope of magnetic resonance imaging diagnostics has expanded to include urology, otolaryngology, and neonatal evaluation. Although infants and children constitute the majority of patients, many adults also require anesthesia for magnetic resonance imaging and present their own challenges.

SUMMARY

Anesthesia and sedation during magnetic resonance imaging have a unique set of constraints. However, most of the standards of modern, safe anesthetic care can be met in this environment. The growing experience at many hospitals has demonstrated that a wide range of patients can receive safe care during magnetic resonance imaging.

Utilization of Low-Field MR Scanners

The evident advantage of high-field MR (magnetic resonance) scanners is their higher signal-to-noise ratio, which results in improved imaging. While no reliable efficacy studies exist that compare the diagnostic capabilities of low- versus high-field scanners, the adoption and acceptance of low-field MRI (magnetic resonance imaging) is subject to biases. On the other hand, the cost savings associated with low-field MRI hardware are obvious. The running costs of a non-superconductive low-field scanner show even greater differences in favor of low-field scanners. Patient anxiety and safety issues also reflect the advantages of low-field scanners. Recent technological developments in the realm of low-field MR scanners will lead to higher image quality, shorter scan times, and refined imaging protocols. Interventional and intraoperative use also supports the installation of low-field MR scanners. Utilization of low-field systems has the potential to enhance overall cost reductions with little or no loss of diagnostic performance.