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

Abstract

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.

Figure 1

Drawings of four MR scanners which will be used in the custom-made questionnaire to assess which specific MR scanner design is evaluated to be the most attractive. Patients will be asked to rank the four MR scanner types according to their preferences. First, this assessment will be done assuming equal diagnostic utility of the MR scanners, and second, assuming for scanner A good, for scanner B very good, for scanner C moderate and for scanner D adequate diagnostic utility. Panel A shows the open MR scanner with a vertical magnetic field design and 1-T field strength (Panorama, Philips). Panel B shows the closed MR scanner with a short- and wide-bore design and 1.5-T field strength (Magnetom Avanto, Siemens). Panel C shows an open MR scanner with a one column design and a 0.4-T vertical magnetic field. Panel D shows a MR scanner with a 0.6-T horizontal magnetic field and a top/front-open design which allows upright positioning of the patient, while patients have to be examined in supine position on the scanners A-C. This information will allow defining which further improvements by the vendors might be necessary to reduce claustrophobic reactions during MR imaging.

Figure 2

Drawings of the two MR scanners to which patients will be randomized in the study. Panel A shows the open MR scanner with a vertical magnetic field with 1.0-T field strength (Panorama, Philips), up to 26 mT/m gradient strength, acoustic scanner noise of maximum 150 dB(A), and a 0.45 m high and 1.6 m wide patient aperture (0.7 m wide patient table). Panel B shows the closed MR scanner with 1.5-T field strength, up to 45 mT/m gradient strength, 97% noise reduction to below 99 dB(A), and a conical shaped wide (0.6 m) and short (1.5 m) bore resembling the gantry of a computed tomography scanner, which has been shown to reduce claustrophobia by a factor of 3 (Magnetom Avanto, Siemens).

Figure 3

Chart of CLAUSTRO study design. The diagram depicts the randomization procedure, patient flow, and data analysis. Abbreviations: AKV = Fragebogen zu körperbezogenen Ängsten, Kognitionen und Vermeidung [19]. BDI-II = Beck Depression Inventory II [24]. CF = Consent Form. CLQ = Claustrophobia Questionnaire [21]. FSS-III = Fear Survey Schedule III [20]. RWCCL = Revised Ways of Coping Checklist [29]. STAI = State-Trait Anxiety Inventory [18].