Elsevier

European Urology

Volume 50, Issue 4, October 2006, Pages 738-749
European Urology

Prostate Cancer
MRI-Guided Biopsy of the Prostate Increases Diagnostic Performance in Men with Elevated or Increasing PSA Levels after Previous Negative TRUS Biopsies

https://doi.org/10.1016/j.eururo.2006.03.007Get rights and content

Abstract

Objectives

Repeatedly negative prostate biopsies in individuals with elevated prostate specific antigen (PSA) levels can be frustrating for both the patient and the urologist. This study was performed to investigate if magnetic resonance imaging (MRI)-guided transrectal biopsy increases diagnostic performance in individuals with elevated or increasing PSA levels after previous negative conventional transrectal ultrasound (TRUS)-guided biopsies.

Methods

27 consecutive men with a PSA >4 ng/ml and/or suspicious finding on digital rectal examination, suspicious MRI findings, and at least one prior negative prostate biopsy were included. Median age was 66 years (mean, 64.5 ± 6.8); median PSA was 10.2 ng/ml (mean, 11.3 ± 5.5). MRI-guided biopsy was performed with a closed unit at 1.5 Tesla, an MRI-compatible biopsy device, a needle guide, and a titanium double-shoot biopsy gun.

Results

Median prostate volume was 37.4 cm3 (mean, 48.4 ± 31.5); median volume of tumor suspicious areas on T2w MR images was 0.83 cm3 (mean, 0.99 ± 0.78). The mean number of obtained cores per patient was 5.22 ± 1.45 (median, 5; range, 2–8). Prostate cancer was detected in 55.5% (15 of 27) of the men. MRI-guided biopsy could be performed without complications in all cases.

Conclusion

According to our knowledge, this is the largest cohort of consecutive men to be examined by MRI-guided transrectal biopsy of the prostate in this setting. The method is safe, can be useful to select suspicious areas in the prostate, and has the potential to improve cancer detection rate in men with previous negative TRUS-biopsies.

Introduction

With the widespread use of PSA testing, the characteristics of prostate cancer (PCa) patients have changed in favor of patients with organ-confined tumors at initial diagnosis. According to Ward et al, the percentage of patients with clinical T3 tumors before radical prostatectomy (RP) at their institution has declined dramatically from 25.3% in 1987 to 2.8% in 2001 [1]. As a consequence of early diagnosis, adopted treatment modalities have been developed, resulting in improvement of quality of life without compromising oncologic outcome [2], [3]. However, these advantages rely on early detection of the disease. Elevated PSA levels also can be present in benign conditions, often resulting in unnecessary biopsies, complications, and costs. Despite all efforts in increasing PSA performance using PSA-isoforms or the free (f) and total (t) PSA ratio, a clear cut between benign conditions and malignancy will not be possible [4].

Repeated negative prostate biopsies in individuals with persistently elevated or increasing PSA levels can be frustrating for both the patient and the urologist. Additional rounds of conventional transrectal ultrasound (TRUS) biopsies do not seem to improve cancer detection rates, which on first, second, third and fourth round have been reported to be 14–22%, 10–15%, 5–10%, and 4%, respectively [5], [6].

To further increase diagnostic performance, Beyersdorff et al. [7] evaluated the role of using magnetic resonance imaging (MRI) in 44 patients with elevated PSA levels and negative TRUS-guided quadrant or sextant biopsies, and found a higher sensitivity for MRI compared with TRUS examinations in detecting PCa. State-of-the-art endoMRI also plays an important role in preoperative assessment of tumor extent within the prostate, extracapsular extension, or seminal vesicle invasion [8]. The next step would be to perform prostate biopsies under direct control of the probe placement. These MRI-guided biopsies can be performed in either dedicated (“interventional”) low-field systems or clinically widely available MRI scanners (1.0–1.5 Tesla field strengths) [9]. The latter system provides a high T2-weighted (w) contrast within acceptable measurement times—a precondition for visualization of suspicious lesions during biopsy.

The purpose of this study was to investigate feasibility, safety, cancer detection rates and complications of MRI-guided transrectal biopsies in individuals with elevated or increasing PSA levels after at least one prior negative TRUS biopsy and suspicious endoMRI findings.

Section snippets

General patient considerations, data documentation and analysis

The use of the devices and procedures described here was approved by the institutional ethics committee. All patients were informed in detail before giving their written consent. Conduction and reporting were in accordance to GCP standards.

All patients were referred by external urologists and attendings of the Department of Urology of the University of Tübingen. In case of a former negative TRUS-guided biopsy, endoMRI is performed routinely at our institution. The indication for MRI-guided

Patients and procedure safety

Mean ± SD of the time interval between the last endoMRI and MRI-guided biopsy was 49 ± 49 days (median, 27; range, 2–168). On the basis of endoMRI findings and estimates of an ellipsoid shape, maximum volumes of the main suspicious T2w hypointense areas were calculated: mean ± SD was 0.99 ± 0.78 cm3 (median, 0.83; range, 0.17–3.75).

Because of a large variety of referring urologists, documentation regarding the time interval between TRUS- and MRI-guided biopsies as well as the exact number and location

Discussion

The most widely used and available tool to detect prostate cancer is the measurement of serum PSA. Although elevated PSA levels can be suggestive of malignancy, benign conditions such as benign prostatic hyperplasia, or acute and chronic prostatitis can also lead to PSA elevation [11]. A serum PSA of 4 ng/ml often is used as a threshold for prostate biopsy. However, the specificity of the test is poor when the value is <10 ng/ml [12]. Since it could be demonstrated that only 25–40% of men with a

Acknowledgments

The authors would like to thank Mr Jan Sabisch and Mr Axel Winkel from MRI Devices Daum GmbH, Schwerin, Germany, for their excellent technical assistance.

Source of funding: This work was funded by a grant of the AKF-Programme of the Medical School of the University of Tübingen (grant #159-1-0).

References (20)

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Drs Anastasiadis and Lichy contributed equally to the work.

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