Diffusion And Perfusion MR Imaging Of The Prostate

Main Category: Prostate / Prostate Cancer
Also Included In: MRI / PET / Ultrasound;  Urology / Nephrology
Article Date: 29 Nov 2008 - 1:00 PST

email to a friend   printer friendly   view / write opinions   rate article

UroToday.com - The current gold standard for diagnosis of prostate cancer is the Transrectal Ultrasound (TRUS) guided prostate biopsy, initiated by elevated PSA-levels or a Digital Rectal Examination (DRE) suspicious for prostate cancer. However TRUS and TRUS-guided biopsies are known to have high false-negative rates, up to 30% with random sextant biopsies 1, 2. In the PSA era probably more low-volume prostate cancers are detected, leading to higher false-negative rates with random TRUS-guided biopsies, even when schemes with increasing numbers of random biopsy cores are used.

Anatomical T2-weighted MRI has been established to outperform DRE and TRUS in patients with an elevated PSA for localization of prostate carcinoma, with a sensitivity and specificity, respectively, of up to 81% and 61% 3. The spreading availability of 3 Tesla MR devices only increases the performance of T2-weighted sequences. At this point MRI is the most promising technique available for adequate localization of prostate carcinoma. Consequently, TRUS-guided biopsies of tumor suspicious regions on MRI can be obtained and more recently the technique of real-time MR-guided biopsies has been perfected to a level making it feasible in clinical practice4.

More recently the introduction of advanced functional MR modalities, such as MR Spectroscopy, Diffusion-Weighted MR Imaging (DWI) and Dynamic Contrast Enhanced (DCE) MRI, have only improved the performance of MRI as a detection, localization and staging tool for prostate cancer 5,6. More importantly, with DWI and DCE-MR, characterization of prostate carcinoma has become within reach. Not only does the addition of these techniques improve the performance of MRI as a localization and staging tool, more interestingly these modalities might be able to characterize prostate cancer. As the architectural combined Gleason score remains the foremost prognostic parameter in prostate cancer, the ability to predict Gleason score is of utmost importance. Hypothetically the characteristics imaged by DWI and DCE-MR, respectively cellular density and neo-angiogenesis, might correlate well with the Gleason score and consequently aggressiveness of the tumor 7. With an emerging spectrum of therapeutic options to be considered, ranging from active surveillance to radiotherapy and surgery, this information could be a cornerstone in clinical decision-making.

In the near future multimodality, MRI will be the measure of choice for localization of prostate cancer in patients with serial negative TRUS-guided prostate biopsy with a persistent high suspicion of prostate cancer. When the histological diagnosis has been made, multimodality MRI will enhance the accuracy of pre-treatment staging and grading of prostate cancer, aiding in decisions on treatment. The most potent combination of anatomical and functional MR sequences still needs to be established.

References

1. Norberg M, Egevad L, Holmberg L, Sparen P, Norlen BJ, Busch C. The sextant protocol for ultrasound-guided core biopsies of the prostate underestimates the presence of cancer. Urology 1997;50:562-6.

2. Rabbani F, Stroumbakis N, Kava BR, Cookson MS, Fair WR. Incidence and clinical significance of false-negative sextant prostate biopsies. J Urol 1998;159:1247-50.

3. Fütterer JJ, Heijmink SW, Spermon JR. Imaging the male reproductive tract: current trends and future directions. Radiol Clin North Am 2008;46:133-47.

4. Pondman KM, Fütterer JJ, ten Haken B, Schultze Kool LJ, Witjes JA, Hambrock T, Macura KJ, Barentsz JO. MR-guided biopsy of the prostate: an overview of techniques and a systematic review. Eur Urol 2008;54:517-27.

5. Haider MA, van der Kwast TH, Tanguay J, et al. Combined T2-weighted and diffusion-weighted MRI for localization of prostate cancer. AJR Am J Roentgenol 2007;189:323-8.

6. Fütterer JJ, Heijmink SW, Scheenen TW, et al. Prostate cancer localization with dynamic contrastenhanced MR imaging and proton MR spectroscopic imaging. Radiology 2006;241:449-58.

7. de Souza NM, Riches SF, Van As NJ, Morgan VA, Ashley SA, Fisher C, Payne GS, Parker C. Diffusion-weighted magnetic resonance imaging: a potential non-invasive marker of tumour aggressiveness in localized prostate cancer. Clin Radiol. 2008; 63:774-82.

Written by Diederik M. Somford, MD and Jurgen J. Fütterer, MD, PhD, as part of Beyond the Abstract on UroToday.com.

UroToday - the only urology website with original content written by global urology key opinion leaders actively engaged in clinical practice.

To access the latest urology news releases from UroToday, go to: www.urotoday.com

Copyright © 2008 - UroToday