Oncology Prostate Cancer TargetScan® 3D Transrectal Ultrasound System – Technical Review Gregory B Boustead Consultant Urological Surgeon, Department of Urological Surgery, South Bedfordshire and Hertfordshire Urological Cancer Centre, Lister Hospital


Abstract


Transrectal ultrasound guided biopsy has become the cornerstone of prostate cancer diagnosis. Improvements in ultrasound technology, guidance systems and biopsy needle technology have all resulted in improvements in cancer detection rates. The Targetscan 3D system allows computer aided saturation biopsy with accurate mapping and tumour volume assessment. This novel system also allows either transrectal or transperineal saturation biopsy, while also allowing integration into standard brachytherapy delivery devices and other new technologies.


Keywords Transrectal ultrasound scan, prostate cancer, diagnosis, sampling, prostate biopsy, brachytherapy


Disclosure: The author has no conflicts of interest to declare. Received: 25 June 2010 Accepted: 30 August 2010 Citation: European Urological Review, 2010;5(1):19–22 Correspondence: Gregory B Boustead, Lister Hospital, Coreys Mill Lane, Stevenage, SG1 4AB, UK. E: gboustead@tiscali.co.uk


Support: The publication of this article was funded by Pergentium Ltd. The views and opinions expressed are those of the author and not necessarily those of Pergentium Ltd.


Transrectal ultrasound imaging of the prostate was first reported in 1956,1


but equipment was crude and difficult to use. With technical improvements in ultrasound in the 1970s, the techniques became more popular as a diagnostic tool, although transrectal ultrasound guided biopsies were still awkward.2,3


The large-calibre Vim-Silverman


needles remained the most popular biopsy technique until the development of the spring-loaded biopsy needle in the late 1980s. Improved ultrasound technology allowed the technique to flourish and become the standard diagnostic procedure for detecting prostate cancer. In 1989, Hodge proposed the sextant biopsy approach, which was widely adopted and remained the standard sampling technique for nearly a decade.4


It soon became evident from whole-mount radical prostatectomy specimens that frequent mismatches between the biopsy information and whole-mount specimens. Cancers were also frequently missed on initial biopsy in up to 30% of cases.5


Attempts to increase cancer


detection rates included increasing the number of biopsies, more laterally placed cores, particularly of the lateral horns of the prostate, and, more recently, saturation and mapping biopsy techniques.6,7


Developments in Biopsy Techniques In 2001, Borboroglu and colleagues reported their experience with extensive transrectal ultrasound-guided prostate biopsy in men in whom a previous sextant biopsy was negative. They took an average of 22.5 biopsy cores (range 15–31) depending on prostate size with a 30% overall cancer detection rate.7


In the same year, Stewart et al. described saturation ultrasound-guided transrectal prostate needle biopsy in 224 men under anaesthesia


© TOUCH BRIEFINGS 2010


in an outpatient surgical setting, all of whom had previous negative biopsies. The mean number of previous sextant biopsy sessions before saturation biopsy was 1.8 (range 1–7). A mean of 23 saturation biopsy cores (range 14–45) were taken throughout the prostate, including the peripheral, medial and anterior regions, showing a 34% cancer detection rate.8


Five years later, Moran et al. described their stereotactic transperineal prostate biopsy technique, identifying cancer in 68 of 180 patients (38%).9


Despite the impressive cancer detection rate,


acute urinary retention developed in 10% of men. In a similar study with a transperineal template technique, Bott et al. showed an identical cancer detection rate, with 60% of cancers in the anterior gland only, but with a more acceptable urine retention rate of 3.3%.10


The Role of Saturation Biopsy Techniques Saturation biopsies have been described in a number of patient groups, including:


• •


as an initial biopsy technique;


in patients with repeated/prior negative biopsies or high-grade prostatic intraepithelial neoplasia (PIN); and


• in patients prior to/being followed on active surveillance protocols.11


The use of saturation protocols at the initial biopsy have not yielded significantly higher cancer detection rates compared with 10- or 12-core strategies. The group of patients who benefit most from an initial saturation approach are those with larger prostate volumes (particularly >50–60cm3).12,13


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