Discussion
HMD
MINOR, INFILTRATION
Use of AR technology is increasing in several fields, including medicine. Early adaptations include image-guided infiltrations [We failed to confirm that our initial hypothesis, which was that inexperienced operators would perform biopsies of soft tissue lesions faster when using AR US than when using sUS, as demonstrated in a previously reported study [Second, in this study, the HMD application displayed two US images, one below the US probe at the exact anatomical location (in situ image), and a second image being the same but magnified and visible only when the head was lifted. The in situ image appeared rather small, as its actual dimensions were being viewed. The magnified US image, which was displayed when the head was lifted, was approximately the same size as on a sUS monitor and this magnified image followed the operator’s eyes. Many of the participants were probably initially overwhelmed by the two images, as indicated by the fact that they tended to look up and down repeatedly, presumably deciding which image they preferred for performing the biopsy. With the benefit of hindsight, we should have trained the participants in the AR US technique for better comparability. We tried to compensate for this issue by performing stratified analysis.Third, in the study cited above [Other limitations of the present study were that the supervisors did not change the modality and may have influenced the operators. Additionally, the turkey breast phantoms were not identical in that the olives were inserted randomly. Thus, the ease of obtaining a biopsy may have varied between the prepared phantoms. Further, some air artifacts might have influenced the operators as for 44 operators only four turkey breast were prepared. However, as more than 15 olives were inserted in each turkey breast we think, that the artifacts were of minor relevance. However, given that we used four different breast phantoms, the differences were hopefully distributed approximately equally. Of note, not all four breast phantoms were punctured with both modalities: they were punctured by all operators, but each with only one modality. Retrospectively, it would have been preferable to exchange both the supervisors and breast phantoms between the two modalities. Also, the fact that we had two different US apparatus could have influenced our results. However, we believe that this is negligible, considering that the lesions were easily visible with both US apparatus, and similar US probes were used.Even with all these limitations having deleterious effects on the AR US data, the participants did not generally perform the US-guided biopsies significantly more slowly and the learning curve was better for AR US than for sUS.Detailed analysis of gender distribution showed a tendency for women to perform the biopsies more slowly than their male colleagues when using the AR US technique; however, this difference was not statistically significant. This trend may have been related to the fact that male operators were more comfortable with the AR US technique and some of them had previously worn HMDs, probably associated with gaming histories. Although former studies have found a possible association between experience with gaming and superior performance of laparoscopic surgery [Interestingly, although puncturing with AR US was performed more slowly, most participants preferred the AR US technique and reported that it provided a better learning experience. The latter observation is concordant with several reports describing the advantages of 3D teaching and learning by AR use and is of utmost importance [The present data indicate that operators who have completed a basic sUS course perform US-guided biopsies similarly whether using AR US or sUS. However, most students preferred the AR US technique and the learning curve was steeper when using AR US. Further development of AR-based techniques may shift the equilibrium towards broader use of AR US. This evolution should be accompanied by innovation and research.