Augmented Reality for Therapy

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Prostate Biopsy

Many men with prostate cancer often do not have readily notable symptoms. By the time any symptom becomes apparent, the disease may have spread beyond the bounds of the prostate. It is therefore important to develop reliable ways of diagnosing prostate cancer. The most common steps of diagnosing prostate cancer include Digital Rectal Examination (DRE) and a blood test known as Prostate Specific Antigen (PSA). Based on these steps, a Transrectal Ultrasound (TRUS) guided prostate biopsy may be recommended to confirm the cancerous growth under microscopic observation of tissue samples taken from within prostate [1]. Despite the increasing acceptance of new improved real-time image ultrasound guiding techniques, many image-guided prostate biopsies are not yet considered as reliable although they have been in use for many years. This is because interpretation and 3D-visualisation (often done mentally) of 2D ultrasonographic prostate images are subjective and dependent on the experience of the investigator [2][3]. Furthermore, many image-guided prostate biopsies still need urologist to refer to 2D images viewed on an inconveniently located monitor. An interactive system providing assistance by allowing the urologist to see within the patient a 3D model of the prostate perineally will be desirable.

We are currently developing an AR visualizing system, called Augmented Reality for Therapy in UROlogy (URO-ART), that is able to provide an ideal platform for visualization of the prostate’s anatomical surface structure within a live patient [4]. Though not fully real-time, the 3D prostate model can be displayed pre-operatively within the patient to improve the planning of biopsy pathway. A urologist is able to do a fast planning of biopsy pathway using his/her natural view of action with decipherable depth perception between the 3D prostate model within the patient and the exterior view of patient's skin. Under the AR display guidance of a selected real-time 2D-ultrasound image, the urologist is able to observe the real-time insertion movement of the biopsy needle reaching the interior target tissue of the prostate. This greatly reduces the invasiveness of the biopsy procedure and improves for the targeting of cancerous tissue.

Picture of a preliminary demonstration display of using URO-ART on transrectal needle biopsy on Prostate.
a) Section view of patient and transrectal needle biopsy. b) Preoperative AR 3D prostate model.
c) Needle insertion with the AR guide of transparent 3D model and a selected real-time 2D-ultrasound image.

System Layout

References

[1] Scardino, P.T., Early detection of prostate cancer. Advances in Urologic Ultrasound, 1989; 16(4): 635-655.

[2] Desgrez, J.P., Julia, M., Verges, J., The limits of conventional imagery in urology: the prostate and the kidney, Annual Urology, Paris, 1990; 24(7): 593-597.

[3] Tan, H.H., Chang, W.Y., Foo, K.T., Transrectal Ultrasound of the Prostate: The Early Singapore Experience, Singapore Medical Journal, 1991; 32: 434-437.

[4] *Chan, C. F., Zhu, C. G., Kwoh, C. K., Teo, M. Y., Ng, W. S., Wong, Y. C., Cheng, W. S., Foo, K. T. Prostate Biopsy using Augmented Reality 3D-Visualisation. Accepted for 18th Southern Biomedical Engineering Conference and 2nd International Conference on Ethical Issues in Biomedical Engineering. Clemson, US, May 20-23 1999.

*Awarded 2^nd Best Graduate/Resident Student Paper

Nomenclature of terms

Biopsy : The removal and examination of a piece of tissue taken the body for diagnostic purposes.
Digital Rrectal Eexamination (DRE) : A common screening procedure for prostate cancer, whereby a physician inserts a gloved, lubricated finger into the rectum, in order to feel the size and shape of the prostate through the rectal wall.
Prostate Specific Antigen test (PSA) : A blood test which measures a patient's level of prostate specific antigen. If elevated, the antigens may be an indicator of prostate cancer.
Urethra : The canal that carries urine from the bladder and semen from the sex glands to the outside of the body.
Urologist : A physician and surgeon who is specially trained in the diagnosis and treatment of diseases of the male genital tract and urinary tract in patients of any age or sex.

Page written by Chan Chee Fatt, Frank