Standard 1.5 T MRIs in pre-treatment staging of localized prostate cancer

According to a report from a major British teaching hospital, simple, standard, 1.5 T MRI scanning (without use of an endorectal coil) does not improve preoperative staging of localized prostate cancer and should not be used in this scenario.

Johnston et al. conducted a retrospective review of data from all patients who received a radical prostatectomy at Addenbrooke’s Hospital, Cambridge, between 2005 and 2010, including all patients who were given a standard 1.5 T MRI scan prior to surgery. All MRI data and post-surgical prostate specimen histology slides were re-reviewed by genitourinary radiologists and pathologists at a centralized, multi-discipinary team meeting.

Here are the study findings:

  • MRI data and histology specimens from 568 patients were identified as eligible.
    • 198/568 patients (34.9 percent) were classified as low risk.
    • 303/568 patients (53.3 percent) were classified as intermediate risk.
    • 67/568 patients (11.8 percent) were classified as high risk.
  • The average (median) age of the patients was 62 years (range, 35 to 74 years).
  • Correlation of MRI findings and final histology showed that
    • MRI findings had a sensitivity of 20.0 percent.
    • MRI findings had a specificity of 80.2 percent.
    • The positive likelihood ratio of MRI findings was 1.25.
  • There was a trend toward improved sensitivity of the MRI findings as the clinical stage increased,  but trend did not reach statistical significance (P = 0.68).

Johnston et al. recommend that “standard MRI has no role in the local staging of prostate cancer.” They do note, however, that a variety of more sophisticated MRI techniques, such as higher field strength systems (e.g., 3.0 T MRI), endorectal coil-based systems, dynamic contrast-enhanced MRI, diffusion-weighted MRI, and MR spectroscopic imaging, do have significant potential in routine clinical practice.

As we have mentioned in earlier posts, the ability of more sophisticated forms of MRI technology does seem, gradually, to be offering us better diagnostic and prognostic evaluation of patients which may be valuable in a range of possible settings over time (from the decision to carry out a biopsy at all in undiagnosed men to the decision about how to treat a man with localized prostate cancer at risk for some degree of local disease progression). Such imaging techniques may also be able to eliminate the need for an excessive number of repeat biopsies in the management of men on active surveillance protocols.

7 Responses

  1. Has MRI S been found to be as effective in identifying prostate cancer location as biopsies?

  2. I think one needs to distinguish carefully between “identifying” an area that is potentially worth biopsying and actually “identifying and confirming” that a lesion is actually cancerous. MRI-S is pretty good at doing the former if the lesion is not too small, but it cannot do the latter.

  3. It’s not only the technology. It’s the skill of the radiologist at reading MRI results of PROSTATES that matters tremendously.

    Just as it’s necessary for a patient to understand how skilled, practiced and successful a surgeon or radiation oncologist is in using the technique they want to use on that patient, it is equally necessary to understand how skilled a diagnostician is in using the diagnosis tools a patient is depending on to make an informed decision that will forever radically alter the course and quality of his life. Whether biopsy slides or MRI results, interpretation is very, very, very much about experience and assumptions the diagnostician is consciously or subconsciously making about a patient based on his medical records and history as well as the actual slides or images.

    It took us months of extreme anxiety to figure out that an ambiguous, non-standard (as in totally made-up out of whole cloth) MRI “diagnosis” was most likely the result of a radiology resident and radiology attending with relatively little experience in imaging prostates making assumptions about levels of risk based on an inaccurate description of trends in lab results. The file read that my husband’s PSA and PCA3 were “increasing”, when, in fact, they both jump up and down wildly like a little red rubber ball and respond to antibiotics and extended periods of “rest”. It took us many, many, many months of persistence to access all the records, all the opinions, all the experience, and all the assumptions — both well- and ill-founded. It was a nightmare and clinicians and medical institutions will definitely try to withhold info for CYA purposes.

    I’m probably oversharing here, but my more general point is that there is a serious downside as well as upside to being an early “adopter” of a commercial, not research, use of diagnostic technology. The research is quite speculative, terms are not well-defined. It’s hard to even understand and contextualize what “expertise” means. And clinicians/diagnosticians tend to manage the increased risk of what they don’t know by being super-conservative and/or reticent and marginally disingenuous about their relative experience. Be ready to seek second and third opinions on anything ambiguous.

  4. Tracy is correct. … There are probably a very, very small number of truly expert urologic radiologists worldwide who can make reasonably accurate interpretations if 1.5 T MRI data … and not that many more who can do it well with more sophisticated MRI data.

    As with second pathological opinions on prostate biopsies, second radiological opinions on MRI data are often a very good idea!

  5. … and finding someone who will provide a second opinion on MRI data is like trying to find a chocolate drop in a coal mine — virtually impossible and if you do find it you’re no less conflicted as to how to proceed.

  6. I think Tracy’s point of ambiguity discovery in prostate cancer patients journey is exactly right. And what I found compelling, in a negative way, was the fact that urologists cannot even agree with one another and yet their diverse prognoses for 240,000 newly diagnosed patients changes the lives of so many men.

    To the point: one urologist told me I should do RALP, one said radiation, and one prescribed Lupron until I figured it out.

    How does a prostate cancer patient meander through the minefield of cryotherapy, radiation, RALP, proton therapy, HIFU, active surveillance?

  7. I agree with all of the above comments.

    Fortunately, multiparametric 3-T MRI is improving and will soon (after adequate studies are completed) at least reduce the numbers of repeat biopsies. For example, a patient with a low-risk (3 + 3 Gleason) prostate cancer on active surveillance might have an MRI and begin Avodart and have a repeat MRI a year later (assuming that PSA is not increasing). A reduction in the areas of loss of T2 signal on the repeat MRI might permit some patients to defer another biopsy for a year or so.

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