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

Abstract

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.

Figure 1. Screening, randomization, and claustrophobic events in the study.

^* Of the 29 patients who had a clinical indication for MR imaging of an anatomical region other than head, shoulder, or spine, 10 needed MR imaging of the knee, 6 of the hip, 3 of the petrous bone, 2 of the iliosacral joints, 2 of the breasts, one each of the whole body, the lower leg, the sternum, the neck, the spleen, and the eye. ^† Of the 33 patients who were eligible but declined to participate, 14 considered study participation too time-consuming, 6 had an appointment for open MR imaging elsewhere, 6 decided not to undergo MR imaging despite clinical indications, and 7 gave no reason. ^‡ Patients were cross-referred for a second MR examination on the other scanner if they could not bear imaging on the first scanner in order to avoid the risks of conscious sedation. Patients were offered cross-referral within one week. If patients could not bear MR imaging on the second scanner either, conscious sedation was performed according to the guideline of the American Society of Anesthesiology to reduce risks . ^§ Of the 30 patients who did attend the MR appointment and had claustrophobic events before or during the second MR imaging, 26 underwent MR imaging with conscious sedation using a mean of 2.6 mg (SD = 1) midazolam IV (sedation success rate 100%, no adverse events). Four patients rejected conscious sedation and could not undergo MR imaging.

Figure 2. Design of the open and short-bore MR scanners to which patients were randomized in the study.

A. Open panoramic MR system . B. Short-bore MR system. . Figure from .