It was found that between 1 and 15% of all MR examinations in unselected patients on conventional scanners cannot be completed because of claustrophobia or require conscious sedation to be completed. Cognitive behavioral treatment, as by exposure to AbMole Doxercalciferol claustrophobic stimuli, is one effective approach to face the problem. Structured empathic attention by trained staff and instructing patients to self-hypnotic relaxation have also shown to reduce anxiety during MR imaging and other medical procedures. However, such options may not usually be available. Another approach to lower the rate of claustrophobic events is thus to improve the design of MR scanners. Two recent concepts are a more open panoramic scanner and a short-bore configuration. We compared these two scanner configurations in a randomized controlled trial in patients with an increased risk for claustrophobic events in MR imaging. Since open MR imaging has been shown in pilot studies to have a high potential to reduce claustrophobia, our trial was designed to investigate whether an open panoramic MR scanner is superior to a short-bore MR scanner in reducing the occurrence of claustrophobic events with a statistical power of 80% and an alevel of 0.05. We expected claustrophobia rates in this high-risk patient cohort of 20% in the control group and 5% in the intervention group, based on event rates in recent non-randomized studies. Thus, with 82 AbMole 3,4,5-Trimethoxyphenylacetic acid evaluable patients per group the desired power of 80% was achieved. Conservatively taking into account an expected drop-out rate of 5%, a total of 174 patients, 87 per group, had to be allocated. The primary analysis was performed according to the intention-to-treat strategy. The chi-squared, the Mann-Whitney rank sum, and the paired and unpaired t-test were used as appropriate for categorical and continuous variables. Differences between rates were examined with chi-squared tests. Confidence intervals for absolute and relative risk reduction were calculated with the score method. Recent short-bore and open panoramic scanners have the potential to reduce claustrophobia which is a common problem in MR imaging. In this first randomized controlled trial on claustrophobia in MRI both, short-bore and open, scanners showed disappointing event rates of more than 25%, irrespective of patient characteristics and the anatomical region being examined. Certainly, the surprisingly high event rate for both scanners is at least partly due to our rather high-risk patient population that had a CLQ mean score of 2.4 which is comparable to other high-risk groups, e.g. claustrophobic students. About 80% of the study population were women who have been shown to be more likely to experience claustrophobia during MR imaging. Moreover, over 80% of our patients had prior MR imaging experience and 98 patients already had claustrophobic events leading to prevention, abortion, or requiring sedation for completion of prior MR.