Teaching and learning normal gynecological ultrasonography using simple virtual reality objects: a proposal for a standardized approach

Teaching basic gynecological and obstetric ultrasonography remains a challenge1; it typically consists of limited personal instruction by an expert while a patient, having agreed to a ‘training exam’, is being scanned. Virtual reality object movies displaying both normal and abnormal anatomy in a simple interactive format have recently been proposed for obstetric ultrasound teaching2, 3. We here extend virtual reality object movies to imaging of the normal female anatomy as it is seen in abdominal and vaginal ultrasound images and combine the resulting interactive material with an anatomical teaching approach demonstrating how to obtain diagnostic images in gynecological patients. Sonographic volume datasets from different insonation routes and angles were digitally sectioned in optimized orientations so that the sections obtained correspond to typical diagnostic planes in realtime scanning (Movies S1–S24). Table 1 lists the insonation routes, probe positioning and orientation landmarks for the provided object movies. Figure 1 shows key frames from a normal female pelvis with annotation of the most important anatomical landmarks, while Figure S1 shows the principal positions of the transvaginal probe, used to acquire the datasets, which may serve as reference positions when examining a patient. Figure 2 shows correlation of the principal vaginal probe orientations with the corresponding ultrasound images. Figures S2 and S3 show characteristic still images taken from the virtual reality object movies for transabdominal and transvaginal imaging, respectively, with annotations. Sample image sequence used for construction of a virtual reality object movie. The parallel sagittal sections, obtained using transabdominal ultrasound, show representative images from one virtual reality object (virtual reality object Movie S1) with annotations of the most prominent anatomical landmarks of a normal female pelvis. Vaginal probe orientation and resulting ultrasound images. Shown are the starting ultrasound images of the virtual reality object Movies S10, S16 and S20, respectively. (a,b) Neutral positioning of the probe, resulting in a median longitudinal section of the uterus; (c,d) pointing the transducer to the right of the patient and rotating it counterclockwise gives a display of the right external iliac vessels and often the right ovary; (e,f) further rotation from the orientation shown in (c) and (d) typically gives an oblique section of the uterus, the Fallopian tube and the ovary. Ultrasonography is considered by many practicing gynecologists to be their major diagnostic tool. This applies in particular to a transvaginal probe, which can be brought much closer to the object of interest (uterus, ovaries, Fallopian tubes) and usually has excellent resolution owing to its higher frequencies. But teaching transvaginal scanning poses unique challenges. Firstly, most women consider a vaginal ultrasound exam as at least uncomfortable. This applies even more to a teaching situation in which an experienced examiner guides a trainee. Secondly, in contrast to abdominal ultrasound scanning, the maneuvers available to position the probe relative to the object to be studied are limited: insertion of the probe into the vagina in the axial direction, lowering and raising of the probe handle to direct the beam anteriorly or posteriorly, tilting towards the pelvic walls and rotating the probe around its long axis. These obstacles prevent many interested trainees from acquiring the diagnostic confidence found in expert centers. Virtual reality movies simulate an ‘ideal’ ultrasound scan in that they allow the operator to move through the female pelvis in standard orientations, identify the correct plane and demonstrate the relevant findings. They are intuitive to use, easy to operate, extremely economic in terms of the digital storage space they occupy and can easily be shared. These advantages and their interactivity make them also the perfect tools for online teaching. More complex simulators, addressing in addition handling and positioning of ultrasound probes (transabdominal or transvaginal), have also been developed and used for gynecological ultrasonography4-10. Yet, the required hardware and cost seem to have precluded widespread use of such systems. The virtual reality objects presented here do not allow correlation of probe movement with the sections displayed on the screen; this movement is emulated using a standard computer pointing device. Another limitation of our approach is that orientation of the stack of planes accessible in the virtual reality object is fixed. The orientation of the current virtual reality objects (vaginal probe on the bottom of the monitor, bladder to the left) can easily be changed by electronically inverting the virtual reality objects (see object Movie S24). For those responsible for training in gynecological ultrasound, our material may form the basis for a practical component of a basic program. Of course, this approach can be extended to produce a digital library of typical gynecological anomalies (for example uterine tumors, adnexal tumors or uterine anomalies) that can be diagnosed by ultrasound. SUPPORTING INFORMATION ON THE INTERNET The following supporting information may be found in the online version of this article: Figures S1–S3 Still images showing probe handling, insonation directions and characteristic images obtained using transabdominal and transvaginal ultrasound Movies S1–S24 Quick Time virtual reality object movies exemplifying the standardized approach to gynecological ultrasound examination outlined in Table 1, with normal findings and some common abnormal findings demonstrated. Note, QuickTime version 7, which can be downloaded from apple.com/quicktime/download, is required to view these movies. ovary, tube and uterus (tilted view).zip This compressed file, as an example, contains the volume data set of Movie S20 in an alternative viewing format, Adobe Flash® To display this object movie, unzip the three files contained in the .zip file then open the extracted HTML file in a browser. PDF Slide with Videos.zip This compressed file contains a PDF illustrating examination technique for transvaginal ultrasound with hyperlinks to relevant movie objects. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. B. Tutschek* , S. Tercanli*, F. Chantraine , * Center for Fetal Medicine and Women's Ultrasound, Freie Strasse 38, 4001 Basel, Switzerland, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany, Obstetrics and Gynecology, University Hospital Liege, Belgium