Prospective data on the use of MRI-guided vs. TRUS-guided biopsy


Two newly published papers in the November issue of the Journal of Urology address prospective studies of the use of differing forms of MRI-guided biopsy in the diagnosis of prostate cancer.

Quentin et al. report data from a prospective study involving 132 biopsy-naive men with a PSA level > 4 ng/ml who underwent an initial 3-T MRI scan followed by an “in-bore” MRI-guided biopsy of up to three suspicious lesions as well as a standard, systematic, TRUS-guided 12-core biopsy, followed by radical prostatectomy. The authors defined “clinically significant” prostate cancer as any core containing cancer of > 5 mm total cancer length or any Gleason pattern > 3.

They found that:

  • 128/132 patients were eligible for evaluation.
  • The average (mean) age of the patients was 66.1 ± 8.1 years.
  • The patient’s average (median) PSA level was 6.7 ng/ml.
  • The TRUS-guided biopsy had
    • An overall detection prostate cancer detection rate of 53.1 percent
    • A 79.4 percent detection rate for clinically significant prostate cancer
    • A 9.4 percent rate of failure to detect clinically significant prostate cancer
  • The “in-bore” MRI-guided biopsy had
    • An overall prostate cancer detection rate of 53.1 percent
    • An 85.3 percent detection rate for clinically significant prostate cancer
    • A 7.8 percent rate of failure to detect clinically significant prostate cancer
  • The combination of both types of biopsy had
    • An overall detection prostate cancer detection rate of 60.9 percent
    • An 82.1 percent detection rate for clinically significant prostate cancer
  • Compared to TRUS-guided biopsy, “in-bore” MRI-guided biopsy
    • Required significantly fewer cores
    • Revealed a higher percent of cancer involvement per biopsy core

What is mildly surprising is that there was relatively little difference between the abilities of the TRUS-guided and the “in bore” MRI-guided biopsy techniques in the detection of prostate cancer when evaluated alone.

By comparison, Le et al. conducted a prospective evaluation of MRI/TRUS fusion-guided biopsy and systematic, mapping biopsy.

They found that:

  • The average (mean) age of their patients was 62 years.
  • The patient’s average (median) PSA level was 6.2 ng/ml.
  • The patient’s final Gleason scores at prostatectomy were
    • 6 in 13 percent of the men
    • 7 in 70 percent of the men
    • 8 or 9 in 17 percent of the men
  • 17/54 men had a tertiary Gleason pattern (of either Gleason 4 or Gleason 5)
  • Of 45 highly suspicious targets identified on MRI, 32 (71 percent) contained prostate cancer.
  • The per core prostate cancer detection rates were
    • 42 percent by MRI/TRUS fusion-targeted biopsy
    • 20 percent by systematic, mapping biopsy
  • The highest Gleason pattern found at subsequent prostatectomy was detected
    • In 54 percent of cases by systematic mapping biopsy
    • In 54 percent of cases by targeted biopsy
    • In 81 percent of cases by the two forms of biopsy in combination.
  • 17 percent of cases were still upgraded from fusion biopsy to final pathology; 1 case (2 percent) was downgraded.

As in the prior study, there was again relatively little difference between the abilities of the TRUS-guided mapping biopsy and the targeted MRI-guided biopsy techniques in the detection of prostate cancer when evaluated alone.

It is clear that the combination of a systematic biopsy together with some form of MRI targeting is a good deal more accurate than a simpler TRUS-guided biopsy alone. However, it also appears to be clear from these two papers that MRI-targeted biopsies alone will miss a significant percentage of prostate cancer lesions, and that even the combination of MRI-guided and systematic biopsy techniques is still associated with a significant risk for later upgrading at surgery.

Based on these data, it seems unlikely that we are ready to abandon the use of systematic biopsy techniques as part of the initial biopsy for prostate cancer, although the addition of some form of targeted, MRI-guided biopsy process to a systematic biopsy process does appear to be justifiable. Whether we can afford all the additional MRIs and the associated technology is a rather different question.

5 Responses

  1. I have been part of a clinical study of the use of 3-T mpMRI at the National Institute of Health for 2 years. The quality and precision of the new scanning technology has moved forward at an unprecedented rate. Changes in equipment, software, contrast agents and all facets of MRI use, show no resemblance to early 3-T MRI abilities. There are currently over 60 clinical studies involved in 3-T MRI at NIH. I am unable to ascertain what generation MRI technology was used in the study above; perhaps it does not reflect current state of the art imaging here in the USA. Affordability of MRI use compared to the cost of blind biopsies and the vast cost of over-treatment by the prostate treatment industry of surgery and radiation, not to include the cost of physical, emotional side effects and salvage treatments, may be the best investment health care ever made.

    God Bless

    Wayne

  2. This post seems to imply that TRUS (blind) biopsies and mapping (saturation) biopsies are excellent tools, deserving to be continued as the standard of care in the urologic profession. Yet numerous other papers pronounce the 3-T mpMRI to be a breakthrough in the diagnosis and treatment of prostate cancer. For example, a recent Urology Times article is close to stamping the gold standard label on the new MRI imaging:

    So, what really is the safety and efficacy of all of these tools?

    It seems we generally benefit from imaging before doing even minimally invasive procedures on other body parts from the feet up to the head. So, why do we use from roughly 12 to over 50 needles before an MRI when a patient has a positive DRE or a disturbing PSA velocity? The advantages of the MRI appear to be compelling: identifying all of the suspicious areas, seeing if there has been spread outside the capsule, understanding the size of the lesions, etc. In addition, the MRI is non invasive with no antibiotics, infection risk, inflammation, etc.

    Be well :-)

    John

  3. The articles commented on above seem to show clearly that — in prospective studies — the combination of MRI-guidance together with a set of standard, systematic biopsies are better than either MRI-guided or standard, systematic biopsies alone in the diagnosis of prostate cancer.

    As far as I am aware, the technologies being used at the relevant centers are quite certainly “state of the art”. In particular the UCLA group (the Le et al. paper) have been at the forefront of research into the use of MRI/TRUS fusion biopsies for several years now.

    It is important to understand that this is an evolving field of research and clinical practice. Most centers don’t have either the equipment or the clinical skills to use either of these techniques on a day to day basis as yet, and it is well understood that there is a major learning curve for uroradologists to become sufficiently skilled at reading 3-T MRI scans to determine with accuracy what is a lesion that clearly indicates risk for prostate cancer on such scans.

    Much as one might wish for every patient at risk to get a 3-T MRI prior to biopsy and for every patient to need only targeted, MRI-guided biopsies to maximize the quality of their biopsies and their diagnosis, this simply isn’t practicable at the present time, and the data from some centers does not appear to be reproducible at others.

    I would strongly dispute the statement that “This post seems to imply that TRUS (blind) biopsies are excellent tools, deserving to be continued” on their own as tools for the diagnosis of prostate cancer. The problem is a great deal more complex.

    The issue is about (a) who really needs to be biopsied at all (because there are now tests that can help to tell a patient and his physician that the benefit of a biopsy in individual cases is very low indeed) and (b) whether MRI-guided, targeted biopsies alone are any more effective that 12-core or other forms of systematic biopsy alone. The data from these two independently conducted studies both suggest that this is not necessarily the case (however much we might like it to be).

    Finally, the Urology Times is not the arbiter of standards of care for urologic disorders. It is a trade magazine, and what you read in it is the opinion of an individual writer or commentator about a particular piece of research at a point in time. When we have data very clearly showing that targeted, MRI-guided biopsies can be carried out with an accuracy that is equal to the accuracy that can be achieved with the combination of MRI-guided and systematic 12-corer biopsies, then we will be in a position to say that we no longer need the systematic biopsy component. We don’t appear to be there yet.

  4. I would argue that these data argue against MRI as a first-line method of doing a biopsy. Perhaps it may be a better choice for a second biopsy but we need more data to support that idea.

  5. Sitemaster,

    Thank you for this excellent review and statement of the current state of the art, as regards prostate biopsy and mpMRI.

    Like you said, when a prostate biopsy is indicated, the best results come from combined mpMRI-guided and systematic TRUS-guided biopsies, not one alone. And still, even with the best we have (combined biopsy), there could be false negative biopsies (5-20%).

    What might plug this loophole is the ConfirmMDx genetic test on the negative biopsy specimens.

    There is no question that that both the urologist and patient need to be up to date on how to best work-up a patient with a high suspicion of prostate cancer. The best answers are out there in the medical literature, even though they may not have made it to “guidelines” status.

    Your site is doing such an excellent job of keeping us informed on the latest in prostate cancer diagnosis and treatment. Thank you again.

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