“The best” type of biopsy using mpMRI guidance to target the lesions

There have been suggestions that guided biopsies on the basis of multiparametric MRI (mpMRI) data are most accurate when done using so-called “in-bore” or “in-gantry” biopsies as opposed to mpMRI/TRUS fusion-guided biopsies. However, “in-bore”/”in-gantry” biopsies are time-consuming and therefore expensive to do.

Now we have data from a clinical research group in Australia stating that they found no meaningful difference between three different types of mpMRI-guided biopsy with respect to detection of prostate cancer or detection of clinically significant prostate cancer.

Yaxley et al.’s recent article in BJU International reports on a retrospective analysis of data from a cohort of 482 patients, all of whom had evidence of PIRADs 3, 4, or 5 lesions after a 3-T mpMRI. So here is what they found:

  • The 482 patients had a total of 595 suspicious and targetable lesions based on the mpMRI data.
  • The three types of biopsy carried out in the 482 patients were:
    • “In-bore” MRI-guided biopsies (biopsy type A) of 298 lesions
    • “Cognitively-directed” transperineal biopsies (biopsy type B) of 248 lesions
    • “Cognitively-directed” and TRUS-guided transrectal biopsies (biopsy tpce C) of 49 lesions
  • The authors report no significant difference in overall prostate cancer detection rates between the biopsy methods.
    • For patients with  PIRADs 3 lesions, the detection rates were
      • 48.9 percent for biopsy type A
      • 40.0 percent for biopsy type B
      • 44.4 percent for biopsy type C
    • For patients with PIRADs 4 lesions, the detection rates were
      • 73.2 percent for biopsy type A
      • 81.0 percent for biopsy type B
      • 85.0 percent for biopsy type C
    • For patients with PIRADs 5 lesions, the detection rates were
      • 95.2 percent for biopsy type A
      • 92.0 percent for biopsy type B
      • 95.0 percent for biopsy type C
  • The authors also report no significant difference in detection rates of clinically significant prostate cancer between the biopsy method.
    • For patients with  PIRADs 3 lesions, the detection rates were
      • 42.2 percent for biopsy type A
      • 30.0 percent for biopsy type B
      • 33.3 percent for biopsy type C
    • For patients with PIRADs 4 lesions, the detection rates were
      • 66.8 percent for biopsy type A
      • 66.0 percent for biopsy type B
      • 80.0 percent for biopsy type C
    • For patients with PIRADs 5 lesions, the detection rates were
      • 90.52 percent for biopsy type A
      • 89.8 percent for biopsy type B
      • 90.0 percent for biopsy type C

Based on these data, the authors conclude that

Identification of an abnormal area on mpMRI appears more important in increasing the detection of prostate cancer than the technique used to biopsy an MRI abnormality.

Now what this study does not imply is that that there aren’t any patients who would benefit from an “in-bore” MRI. What the authors are saying is that in general most men will have their cancer accurately identified regardless of the type of MRI-guided biopsy that is carried out. But there are always exceptional patients for whom special types of biopsy might be more appropriate. This is where the clinical judgement factor needs to be taken into account

6 Responses

  1. Very interesting. I have been hoping that we can better understand performance of guided biopsies.

    It should be noted that this study is based on a retrospective single centre study in Australia. Moreover, the doctor performing the MR Guided biopsy was a urologist. In the US, the MR-guided biopsy is typically performed by an experienced radiologist, so I am very skeptical as to the relevance of these findings as they apply to the US. It would be extremely interesting to see a well-designed randomized US trial that measures performance of MR-guided in-bore (radiologist) vs. fusion vs. cognitive.

  2. Dear John:

    In the CureTalk discussion on imaging with Dr. Westphalen (an experienced uroradiologist at UCSF) last Friday, I specifically asked about the role of MR-guided, “in-bore” biopsies, and while he said he enjoyed doing them, they were time-consuming and (in his experience) rarely provided data that was sufficiently better to justify regular use.

  3. Still Kind of Amazed at the Rapid Emergence of mpMRI in Aiding Biopsies

    It seems like just a few years ago the vast majority of biopsies were done without mpMRI. Now we are seeing this examination of the best way (“in bore” versus not “in bore) to take advantage of the mpMRI in doing the follow-up biopsy.

    We are hearing from a number of newly diagnosed men in our support group saying they had mpMRIs done before their biopsies. I’m curious how common this is.

    At last year’s 2016 Conference on Prostate Cancer (September) in Los Angeles, Dr. Mark Emberton, a noted focal therapy expert from London, was asked by Michigan’s Dr. Mark Moyad whether he would get [meaning “do”] a biopsy today without an MRI; Dr. Emberton replied “No.” Dr. Moyad asked whether there were exceptions. Dr. Emberton again replied “No.” Dr. Emberton added that he had stopped doing TRUS biopsies “seven years ago”: “everybody gets an MRI.” (By “MRI”, he meant a mpMRI.) (Conference DVD Disc 1: 1:47:07 – 1:47:37) (I found his talk, his Q&A with Dr. Moyad, and his Meet the Speaker Q&A with patients all highly informative about mpMRI for prostate cancer.)

  4. Dear Jim:

    The cost of MRIs and mpMRIs varies enormously around the world. In the UK and Japan they are relatively low cost. Here in America they vary a lot from area to area but they are much more expensive and payers are still unwilling to pay for an mpMRI prior to a standard TRUS-guided biopsy a lot of the time.

  5. Sitemaster:

    Thank you for that insight. This is another instance where the kind of care needed is constrained in the US by cost that is substantially higher than in other countries.

    Regarding cost, Dr. Emberton had an interesting commentary on efforts to reduce mpMRI cost. He explained that the high cost parameter of the mpMRI is the dynamic contrast enhanced part of the imaging, because of the contrast agent, which is gadolinium. It’s not just the cost of the gadolinium itself, but also the need to take images every 15 seconds — therefore taking a long time, the need for a doctor to be present in case of an allergic reaction to the contrast agent, and therefore the need for a medical facility of some sort.

    He said that the PROMIS trial (with results published in February 2017) described at ASCO last year, was powered to address the extent of value added by the dynamic contrast enhanced data versus the sum of data from just the T1 images and the water diffusion images. Interpretation of each mpMRI sequence in the study was blinded to interpretation of the other sequences to avoid confounding. However, per a search today, it does not appear that this aspect of the trial has been published.

    The impact would be great if the contrast sequence were not needed. Dr. Emberton noted that no doctor or medical setting would be needed, and of course the time required would be much shorter. He said the scan could then be done in a supermarket, for instance, possibly making it feasible to use mpMRI as a screening tool for prostate cancer. (2016 Conference on Prostate Cancer DVD set, Disc 1, 1:52:40 – 1:54:25)

    He also mentioned that, despite the fact that mpMRI appears to be far more effective at detecting significant cancer than systemic biopsies, there are quite a lot of groups that would like mpMRI to fail. Here and elsewhere he is indicating a turf battle between radiologists, whose work would grow with widespread adoption of mpMRI, and urologists, whose work would decline as such widespread adoption would reduce their biopsy business. (Of course, a more positive way of looking at it is that this development would free them for more of the work that only they can do.) (e.g., Dr. Emberton’s statement on Disc 1, about 1:46:05 through 1:47:07)

  6. Dear Jim:

    The potential for mpRI to be used as a “screening” test for prostate cancer is really very low indeed. It isn’t accurate enough even with the contrast agent; it would still need to be confirmed by biopsy; and the initial cost would be far too high.

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