Magnetic resonance imaging has been rated by leading general internists to be, together with computed tomography , the most important medical innovation of the last 25 years. However, MR imaging can be severely hampered by CT99021 GSK-3 inhibitor claustrophobia induced by confinement in the long narrow bore of conventional scanners and further unpleasant aspects of the examination such as scanner noise and vibration. Anxious patients suffer from claustrophobia during MR imaging in up to 35% of all cases , and claustrophobic events can lead to abortion of imaging or require sedation for its completion. This situation decreases diagnostic yield, limits patient acceptance, and reduces workflow. Moreover, conscious sedation to alleviate claustrophobia involves significant risks. Thus, claustrophobia is a common challenge for performing MR imaging and has been investigated in CPI-613 supply several large nonrandomized studies. 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 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. An event for the primary hypothesis was defined as the inability of a patient to complete an examination on the assigned MR scanner due to claustrophobia. Events were assessed by two research staff members who had to be present during MR imaging and thus could not be blinded to the study group. Secondary objectives were to analyze the duration of MR imaging, the time at which events occur during the MR examination, the predictive value of validated questionnaires and patient characteristics for claustrophobic events , and follow-up results. 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.