How do mpMRI and MRI/TRUS fusion biopsies actually work?

As our regular readers will be well aware, the combination of multiparametric MRI (mpMRI) data with transrectal ultrasound (TRUS)-guided biopsy techniques are rapidly becoming more common in both the diagnosis of prostate cancer and in monitoring risk for prostate cancer in men on active surveillance protocols.

There is a recent slide presentation now available on line (put together by Borofsky et al. from the George Washington University School of Medicine and Health Sciences) that may be useful to many readers in understanding the details of this technique and the differing ways it can be carried out, including:

  • “In-bore” biopsies — when the biopsy is carried out with the patient actually in the MRI scanner
  • MRI/TRUS fusion using spatial registration
  • The UroNav system for MRI/TRUS fusion biopsy guidance
  • The Artemis system for MRI/TRUS fusion biopsy guidance

11 Responses

  1. I read on Inspire that doctors only get reimbursed for a standard biopsy even if they perform a combined MRI/TRUS biopsy. I am not sure this is correct, but if it is, it may discourage smaller practices from adopting the use of MRI/TRUS biopsies.

    (This is not unusual, as doctors who perform a laparoscopic hernia repair only get reimbursed for a surgical procedure even though more skill is required and more equipment, some of which has to be discarded.)

  2. Indeed, according to one of the slides in the slide set mentioned above, “MRI/TRUS fusion does not have an independent CPT code, and is currently only reimbursed to same extent as a standard biopsy.”

  3. From what I have read, “in-bore” real-time biopsy is more precise than “fusion” in hitting the biopsy target.

    IMO, urologists like “fusion” biopsy because it allows them to do the biopsy, whereas “in-bore” biopsies typically done by interventional radiologists (who have access to 3-T MRI machines).

  4. Dear Doug:

    (1) I am not aware of any data that has actually confirmed the idea that in-bore biopsies are necessarily more accurate than mpMRI/TRUS fusion biopsies. I suspect tnhat that depends on the skill and experience of the persons carrying out such a biopsy and “reading” the MRI scans.

    (2) The in-bore biopsies are (generally) much more complicated to carry out, much more expensive to do, and a good deal less comfortable for the patient.

    (3) The average interventional radiologist probably has very limited experience in the conduct of a prostate biopsy. If I was going to want such a biopsy done, I would still want the person who did the biopsy to be an experienced urologist or urologic oncologist … with an experienced interventional radiologist “looking over his or her shoulder” to offer guidance about exactly which areas of the prostate needed to be biopsied.

  5. My understanding is that there are problems aligning the MRI with ultrasound, and the MRI is typically done well in advance of the biopsy, and the prostate often changes in shape/size in the interim.

    I’ve had an “in-bore” biopsy………more comfortable and much quicker biopsying time, as compared to my TRUS biopsy, and about the same price.

    The interventional radiologists who do “in-bore” biopsies are experts at interpreting MRIs….most urologists are not.

  6. Dear Doug:

    When MRI/TRUS fusion is carried out today, it is usually done (here in America) using specialized software technology such as the UroNav and Artemis systems, and (as I understand this) there is actually very little difficulty aligning the MRI data with the TRUS data when using such systems.

    You are absolutely correct, however, when you say that ‘interventional radiologists who do “in-bore” biopsies are experts at interpreting MRIs’. On the other hand, very few interventional radiologists have done even 100+ prostate biopsies. Skilled urologists have usually done thousands. It’s not just a question of what you can see on the MRI. It is also important whether you can insert the biopsy needle accurately into the appropriate tissue. That is a surgically acquired skill. My current understanding is that there are very, very few centers at all in the US where the “in-bore” technique is routinely carried out as yet. One of the reason for that, as you also accurately note, is that reimbursement for an in-bore biopsy is “about the same” as for a standard systematic 12-core biopsy. A consequence is that the centers doing “in-bore” biopsies lose money on every such biopsy (unless the patient is willing and able to pay for this out of pocket or it is being done as part of a clinical research protocol being funded by the NIH or some other organization).

  7. I pretty much agree with you. However, most urologists have done very few MRI/fusion biopsies.

    Also, the “in bore” MRI and biopsy can be done in one visit. In my case, they did the MRI, saw 2 lesions, and added the biopsy “on the fly”, which only took a few more minutes (you are already in position on the MRI table).

    With the fusion biopsy, you have to go twice … once for the MRI and once for the biopsy. When you consider this point, “in bore” shouldn’t be much more expensive … most of the time is spent doing the MRI, which is the same for both procedures.

  8. Doug:

    Please understand that I an not arguing with you about any of this. My point is only that to get an in-bore biopsy you require a pre-arranged set up which actually allows for what happened for you, and that has to include: (a) an experienced radiologist on site who knows how to read the prostate MRI scans with a high degree of skill (these individuals are relatively rare in an “on-site setting” because so much reading of MRIs is now done remotely); (b) someone with skill and experience in the actual conduct of a prostate biopsy (whether that person is an interventional radiologist or a urologist may be moot if they have been appropriately trained and had enough practice … but such training and practice is essential); and (c) an MRI set-up which actually allows for in-bore biopsies to be carried out both physically and aseptically in-bore.

    Most MRI centers wouldn’t meet the criteria for a biopsy to be carried out because they are not required to meet standards for office-based biopsies at all. Also, most of the MRI centers in the country don’t even have the relatively recent MRI technology that allow for a biopsy to be carried out physically. It is all but impossible to carry out such a biopsy in one of the older “tube” MRI machines.

    By comparison, an awful lot of urologists are now acquiring the in-office equipment that allows them to conduct MRI/TRUS fusion biopsies. In contrast to the cost of acquiring the necessary type of MRI equipment and ensuring it is being used in an aseptic environment, this is relatively low cost — but it is still hard to get profitably reimbursed because under these circumstances the radiologist gets reimbursed for the MRI and the person doing the biopsy only gets reimbursed for a standard biopsy.

    Do you actually know how many centers in North America can and do now routinely carry out in-bore biopsies? I would really like to know that, but I am not aware of a concise source for that information. I get the impression that it may be as few as half a dozen or so. I would also like to know how many of those centers are doing such biopsies as a part of some form of research protocol as opposed as a purely clinical protocol. By comparison, I think there are probably several hundred urologists at ac academic and large community practice centers that can and do carry out MRI/TRUS fusion biopsies.

    The fact is that MRI/TRUS fusion biopsies are becoming reasonably accessible and are already available at almost every academic urology department around the country as well as many large community practices. By comparison, finding a center that can do an in-bore biopsy is much harder because there are far fewer of them and this is unlikely to ever become a mainstream opportunity for the vast majority of patients (unless they live close to somewhere like the NIH at Bethesda or UCSF in San Francisco or similar). And, as I said originally, I know of no objective data that confirms that an in-bore biopsy is necessarily “better” than a good MRI/TRUS fusion biopsy.

  9. I believe most of the “in-bore” biopsies are being done by just a handful of doctors. Mayo is getting into the MRI biopsy biz, but I don’t know if they are “in-bore” or not.

    I don’t want to belabor this, but IMO “in-bore” is more accurate, and better for the patient.

    In theory for “in-bore”, the MRI, biopsy, and some type of ablation could all be done at one time (if you had a pathologist on site to immediately read the biopsy).

    Thanks for you comments.

  10. Doug:

    And you are entirely entitled to your opinion … but I always prefer to have actual data because opinion is all too often incorrect in retrospect. :O)

  11. There is a guy on Inspire (MRYFLYGUY) who maintains a downloadable list of facilities that perform 3-T MRI biopsies. Click here for info.

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