Evaluating the Performance of Augmented Reality in Displaying Magnetic Resonance Imaging-Derived Three-Dimensional Holographic Models.

INTRODUCTION/BACKGROUND: Establishing accuracy and precision of magnetic resonance (MR)-derived augmented reality (AR) models is critical before clinical utilization, particularly in preoperative planning. We investigate the performance of an AR application in representing and displaying MR-derived three-dimensional holographic models. METHODS: Thirty gold standard (GS) measurements were obtained on a magnetic resonance imaging (MRI) phantom (six interfiducial distances and five configurations). Four MRI pulse sequences were obtained for each of the five configurations, and distances measured in Picture Archiving and Communication System (PACS). Digital imaging and communications in medicine files were translated into three-dimensional models and then loaded onto a novel AR platform. Measurements were also obtained with the software's AR caliper tool. Significant differences among the three groups (GS, PACS, and AR) were assessed with the Kruskal-Wallis test and nonsample median test. Accuracy analysis of GS vs. AR was performed. Precision (percent deviation) of the AR-based caliper tool was also assessed. RESULTS: No statistically significant difference existed between AR and GS measurements (P = .6208). PACS demonstrated mean squared error (MSE) of 0.29%. AR digital caliper demonstrated an MSE of 0.3%. Three-dimensional T2 CUBE AR measurements using the platform's AR caliper tool demonstrated an MSE of 8.6%. Percent deviation of AR software caliper tool ranged between 1.9% and 3.9%. DISCUSSION: AR demonstrated a high degree of accuracy in comparison to GS, comparable to PACS-based measurements. AR caliper tool demonstrated overall lower accuracy than with physical calipers, although with MSE <10% and greatest measured difference from GS measuring <5 mm. AR-based caliper demonstrated a high degree of precision. CONCLUSION: There was no statistically significant difference between GS measurements and three-dimensional AR measurements in MRI phantom models.

Assessment of quiet T2 weighted PROPELLER sequence in pediatric abdominal imaging.

INTRODUCTION: Elevated acoustic noise during Magnetic Resonance Imaging (MRI) has been associated with patient anxiety and altered cochlear function. Acoustic Reduction Technique (ART) T2 weighted (T2w) periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) has been studied in brain MR but not abdominopelvic imaging. The purpose of our study was to evaluate the image quality and acoustic noise level of ART T2w PROPELLER sequence in comparison with the conventional T2w PROPELLER sequence in pediatric abdomino-pelvic imaging. METHODS: Eleven consecutive pediatric patients undergoing abdomino-pelvic MRI were scanned on a 3 Tesla magnet using standard and ART T2w PROPELLER sequences. After scanning completion, objective sound level measurements were performed with a sound level meter and microphone. Mann-Whitney U test was used for a non-parametric two-tailed statistical analysis of acoustics, image rating and scan time with significance level set to 0.05. Overall inter-rater agreement was calculated using Cohen's kappa coefficient. RESULTS: Eleven pediatric patients (4 females and 7 males) between 26 days and 18 years of age (mean = 10.0, SD = 5.8) were included. ART T2w produced lower levels of acoustic noise than standard technique in a comparison of mean decibel readings from eleven trials of standard and ART T2w (p value = 0.00008). Streak artifacts were rated greater in ART T2w by both raters (p-value = 0.00278 and 0.00252). There was no significant difference in bile duct blurring, respiratory ghosting, pulsation, fat suppression or hepatic parenchymal depiction. CONCLUSION: Presence of additional streaking artifacts should be considered along with the benefit of reduced acoustic noise from ART T2w.