Is MRI Useful in Guiding Prostate Biopsies?
Is MRI Useful in Guiding Prostate Biopsies?
Hello. I am Dr Gerald Chodak for Medscape. This week, I want to talk about the role of magnetic resonance imaging (MRI) in performing prostate biopsies.
Quentin and colleagues conducted a prospective study comparing MRI-targeted biopsies with a 12-core ultrasound-guided biopsy. The people performing each of the biopsies were not aware of the results obtained by the other method.
The study comprised 132 men, but four of the cases had to be excluded because the MRIs were unacceptable. Unfortunately, this slightly biases the results toward MRI because these four were not included in the results.
The investigators found a 53% detection rate overall, using both methods. In other words, there was no significant difference in the ability to diagnose prostate cancer between these modalities. Overall, the mean Gleason scores for the men diagnosed with cancer were similar. The only significant difference was in the men who had positive biopsies: A greater percentage of the cores showed cancer in biopsies that were done using MRI, which is to be expected, since they were going after targeted lesions.
These investigators also defined "significant cancer," a term that I have been critical of in the past. In this study, patients with "significant cancer" were those with greater than 5 mm of cancer. The ability to diagnose significant cancer was also statistically similar, whether by MRI or the ultrasound-guided biopsy technique.
Thus, the only real difference between the diagnostic methods was that of the men who had cancer, a greater percentage of the cores showed cancer: 65% in the men who had the MRI-detected biopsies compared with 50% of men whose biopsies were done by ultrasound. The question is whether that matters.
These authors concluded that the results were comparable. They are making an argument that MRI is valuable because it may allow fewer biopsy cores to be performed.
The problem, of course, is that this is a rather limited finding to warrant switching to MRI-guided biopsy. Someone else could have concluded, in the absence of finding a significantly better detection rate, why bother with the expense and inconvenience of MRI over the 12-core ultrasound-guided biopsy?
This was a well-done study, but the evidence is clear that MRI did not offer a significant advantage. It did not find more cancers, and even if you accept the finding of "significant cancers," it was no better in that regard, either.
The bottom line for now is that the standard 12-core ultrasound-guided biopsy is doing a good enough job, and MRI should be evaluated for a possible role in men who have had a previous negative biopsy. To use MRI at the outset does not seem to be warranted on the basis of the existing data, and this study provides additional support for not conducting MRI-guided biopsies.
I look forward to your comments. Thank you.
Hello. I am Dr Gerald Chodak for Medscape. This week, I want to talk about the role of magnetic resonance imaging (MRI) in performing prostate biopsies.
Quentin and colleagues conducted a prospective study comparing MRI-targeted biopsies with a 12-core ultrasound-guided biopsy. The people performing each of the biopsies were not aware of the results obtained by the other method.
The study comprised 132 men, but four of the cases had to be excluded because the MRIs were unacceptable. Unfortunately, this slightly biases the results toward MRI because these four were not included in the results.
The investigators found a 53% detection rate overall, using both methods. In other words, there was no significant difference in the ability to diagnose prostate cancer between these modalities. Overall, the mean Gleason scores for the men diagnosed with cancer were similar. The only significant difference was in the men who had positive biopsies: A greater percentage of the cores showed cancer in biopsies that were done using MRI, which is to be expected, since they were going after targeted lesions.
These investigators also defined "significant cancer," a term that I have been critical of in the past. In this study, patients with "significant cancer" were those with greater than 5 mm of cancer. The ability to diagnose significant cancer was also statistically similar, whether by MRI or the ultrasound-guided biopsy technique.
Thus, the only real difference between the diagnostic methods was that of the men who had cancer, a greater percentage of the cores showed cancer: 65% in the men who had the MRI-detected biopsies compared with 50% of men whose biopsies were done by ultrasound. The question is whether that matters.
These authors concluded that the results were comparable. They are making an argument that MRI is valuable because it may allow fewer biopsy cores to be performed.
Is This Finding Enough to Change Practice?
The problem, of course, is that this is a rather limited finding to warrant switching to MRI-guided biopsy. Someone else could have concluded, in the absence of finding a significantly better detection rate, why bother with the expense and inconvenience of MRI over the 12-core ultrasound-guided biopsy?
This was a well-done study, but the evidence is clear that MRI did not offer a significant advantage. It did not find more cancers, and even if you accept the finding of "significant cancers," it was no better in that regard, either.
The bottom line for now is that the standard 12-core ultrasound-guided biopsy is doing a good enough job, and MRI should be evaluated for a possible role in men who have had a previous negative biopsy. To use MRI at the outset does not seem to be warranted on the basis of the existing data, and this study provides additional support for not conducting MRI-guided biopsies.
I look forward to your comments. Thank you.