Originally published 8/11/2014
It’s been over 6 years since I posted the blog below. During the intervening years, my colleagues in prostate imaging continued an ongoing discussion on the pros and cons of an endorectal (in the rectum) imaging antenna during multiparametric MRI of the prostate. While I was one of the early voices in favor of alternative body antennas, my position never wavered. I want to share two recent studies that confirm the endorectal coil offers no advantage over external body coils. Both studies were conducted at well-respected centers.
The first study was done out of Brigham & Women’s Hospital (Boston). O’Donohoe, et al. (2019)[i] compared biparametric 3T MRI using a wearable pelvic coil followed by the same type of scan using an endorectal coil with 18 patients. Their findings included the following: The wearable pelvic coil (WPC) produced “comparable image quality to that of an ERC [endorectal coil]. WPC imaging provides comparable image quality to that of an ERC, potentially reducing the need for an ERC.” Each method had a slight advantage over the other in certain specific details, but overall they were equally beneficial.
The second study was done out of several institutions, including Harvard Medical School (Boston) and Case Western University (Cleveland). Tirumani, et al. (2020) conducted a review of published literature in order to develop what they call a head-to-head comparison of endorectal vs. non-endorectal coils in staging T3 prostate cancer. They analyzed 8 comparison studies, and concluded that there is “no significant difference” in diagnostic performance regardless of the type of antenna used.
It’s always reassuring to find that one’s imaging preference is validated.
If you had a chance to read my earlier article on the necessity (or not) of an endorectal coil for prostate imaging, you know that some centers prefer to do MRI scans of the prostate using an endorectal coil. At the Sperling Prostate Center, we do not use this device.
An endorectal coil is essentially an “antenna” placed into the rectum during the MRI scan. The antenna itself is slender, but it is covered with an inflatable balloon, or condom, made of latex or a different substance for patients who have a sensitivity to latex. Patients are usually instructed to eat light meals the day before and often asked to administer an enema so the lower bowel is empty. This is to make insertion easier.
Prior to insertion, the balloon is lubricated and then a nurse or technician inserts it through the anus into the rectum. The balloon is inflated using a liquid, and as the inflation occurs, the patient experiences pressure within the rectum. The inflation remains throughout the scan, and can be quite uncomfortable for the patient.
Our Center does not use the coil for the following reasons:
- Our 3T magnet is state-of-the-art powerful equipment that generates fantastic magnetic resonance image clarity.
- Our multiparametric software is equally advanced, and provides sophisticated visual data on the key parameters (T2 weighting, Diffusion Weighting, Dynamic Contrast Enhancement) that differentiate healthy tissue from cancer and from benign prostate conditions such as BPH (benign prostatic hyperplasia).
- I personally have top-tier experience in reading prostate MRI scans. In fact, I have been collaborating for several years with the Dutch team at Nijmegen University in The Netherlands, who are arguably among the top international experts in 3T multiparametric MRI of the prostate. Thanks to their leadership, I literally have trained with the world’s best.
- While the endorectal coil brings the antenna closer to the prostate, the size and shape of the inflated balloon actually distort the prostate/pelvic anatomy to a certain degree. I prefer to capture images of the prostate and pelvic region as nature created it.
- Last, but certainly not least, our patient-centered approach means that we want our patients to feel safe and comfortable during MRI scans of any body condition, including prostate MRI. It is easier to relax and lie still when required to do so if one is not preoccupied and worried about rectal pressure.
I know that use of the endorectal coil is still prevalent in many academic and community settings. But because I know the sophistication of our technology, the caliber of our imaging, the experience level of our interpretations, and our philosophy of patient-centered care, I am confident that we are delivering the highest clinical imaging standards with assured patient comfort.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
[i] O’Donohoe RL, Dunne RM, Kimbrell V, Tempany CM. Prostate MRI using an external phased array wearable pelvic coil at 3T: comparison with an endorectal coil. Abdom Radiol (NY). 2019 Mar;44(3):1062-1069.