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Reducing Patient Anxiety in MRI using Acoustic Noise-Modulated Computer Animations: Experience in Pediatric Psychiatric Patients1Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, TX, United States
Synopsis
Acoustic noise is a major source of discomfort and anxiety for patients undergoing MRI examination, and psychiatric patients are especially vulnerable to this stressor. We implemented a simple and low-cost system for patient distraction using visual animations synchronized to the acoustic noise caused by MRI scanner gradients. This multisensory approach, linking sensory to visual inputs, was implemented on a 3 Tesla scanner and tested in 13 pediatric patients with bipolar disorder. Another group of 15 patients received only music as a control. After the scans were completed, all subjects responded to a questionnaire, with the help of their parents, about their scan experience. Analysis shows that the multisensory input was perceived less favorably by the patient despite the scan duration was perceived to be 15% shorter.
INTRODUCTION
Acoustic noise arising from strong rapid switching of the gradient coils is one of the major factor that promotes anxiety for the patient in the MRI scanner. The noise pressure levels are high and necessitate the use of earplugs and headphones to protect the patient’s hearing. Still, acoustic noise remains part of the normal MRI operation mode, which adversely affects the patient experience 1. However, the perception of the intense acoustic noise also depends on the presence of other stimuli in the environment and how the brain integrates sensory stimuli 2–5. Hence, patients are frequently provided with multimedia content as a distraction, such as listening to music and/or watching vedio clips. Nevertheless, the multimedia content is independent of the MRI scanner noise. We hypothesize that synchronizing external stimuli to the MRI acoustic noise may provide a favorable modulation of the noise that can reduce the anxiety/annoyance of the loud repetitive MRI noise, and may even turn it into an entertainment.
As vision dominates our sensory input 5, we investigated whether computer-animated graphics synchronized to the MRI acoustic noise can improve the patient experience. This hypothesis was tested in a group of children with psychiatric disorders, who may be more susceptible to anxiety in the MRI environment.
METHODS
The patient distraction/entertainment system was integrated into a 3.0 Tesla MRI system (Ingeina, Philips Healthcare). The system (Fig. 1) used a microphone to pick up the MRI scanner’s noise, and fed it as an input to a computer program (Winamp v5.666, Nullsoft Inc.) that modulated a visualization routine using the sound level and frequency content. The animated scene was displayed on a monitor in the scanner room, and projected to the patient’s line of vision through a mirror system. Four visualization routines were cycled through the study (1 min each). These routines were selected to be responsive to the audio signal, use eye-friendly color schemes, avoid rapid animation transitions, and employ engaging animations.
The study included 28 pediatric patient with bipolar disorder (15M, 13F, age=10.9±2.5 years), undergoing a standard neuroimaging protocol. The subjects were randomized to receive music-only (n=13), or music and MRI noise-synchronized animations (n=15). After the scan, the subjects answered a questionnaire about their overall MRI scan experience (1: very unsatisfied, 5: very satisfied), comfort inside the scanner (1: very uncomfortable, 5: very comfortable), loudness of the scanner (1: very quiet, 5: very loud), enjoying the audio and/or visual material (1: not at all, 5: very much), estimated duration the scan the scan, experience relative to previous scans, if applicable (1: much worse, 5: much better), and how likely the subject will recommend the audio/visual materials to others (1: very unlikely, 5: very likely). Parents were allowed to assist the children completing the questionnaire without any input from the investigative team. The Mann-Whitney test was used to compare the ratings.
RESULTS
The overall MRI scan experience was better without the animations (P<0.04), but the scan was perceived shorter with the animations (P<0.05). Patients enjoyed the music input more when presented alone (P < 0.04). Recommendation of MRI scanning was also higher for the music-only group (P < 0.01). No statistically significant differences were found in other aspects.DISCUSSION
Despite a perceived shorter scan with the acoustic noise-synchronized animations, the subjects generally preferred the music-only scan during MRI examination. This is in contrast to a previous study of healthy adult volunteers who rated the visualization scan as more favorable 6. This may be due to increased distraction of young psychiatric patients to additional input stimuli. In addition, a limitation of this study was the use of largely abstract animation routines, which may not appeal to a young patient population. More interesting animation routines, such as cartoon or animations incorporating familiar movie themes and characters may improve the overall experience of the patients. In addition, customizing the animations to the individual patient may improve engagement with the animation. Finally, incorporating acoustic-noise modulated audio effects, combined with the modulated visual animations, could be more entertaining. Larger studies including both adults and children with various disorders are currently planned.CONCLUSION
The proposed approach provides low-cost and practical patient distraction and entertainment system that can be readily implemented on current clinical MRI systems. However, pediatric patients with a psychiatric disorder do not appear to favor the additional stimulus of abstract animations.Acknowledgements
We thank Dr. Giovana Zunta-Soares and Dr. Jair Soares for providing access to the patients.References
1. McNulty, J. P. & McNulty, S. Acoustic noise in magnetic resonance imaging: An ongoing issue. Radiography 15, 320–326 (2009).
2. Stein, B. E., Stanford, T. R. & Rowland, B. A. The neural basis of multisensory integration in the midbrain: Its organization and maturation. Hear. Res. 258, 4–15 (2009).
3. Shimojo, S. & Shams, L. Sensory modalities are not separate modalities: Plasticity and interactions. Current Opinion in Neurobiology 11, 505–509 (2001).
4. Macaluso, E. & Driver, J. Multisensory spatial interactions: A window onto functional integration in the human brain. Trends in Neurosciences 28, 264–271 (2005).
5. Witten, I. B. & Knudsen, E. I. Why seeing is believing: Merging auditory and visual worlds. Neuron 48, 489–496 (2005).
6. Gabr, R. E. & Narayana, P. A. Patient Distraction and Entertainment System for Magnetic Resonance Imaging using Visual Effects Synchronized to the Scanner Acoustic Noise. in The 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (VISIGRAPP) 60 (2016).
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