MR imaging diagnoses endometriosis so reliably that it outperformed the surgical gold standard for confirming its presence, according to an Oxford University study.
Dr. Stephen Golding, a lecturer in radiology at Oxford, studied 56 women with possible endometriosis. He compared MRI results with the subjects' laparoscopy findings.
The MR protocol was based on a triplanar series. Sagittal and coronal T2-weighted images optimized the visualization of zonal pelvic anatomy, he said. These were combined with axial T1-, T2-, and fat-saturated T2-weighted images used mainly for tissue characterization.
Classical endometrioma, hemorrhagic cyst, and peritoneal plaque are revealed as bright T1 signal indicative of hemoglobin residing in these abnormalities, Golding said.
Twenty-seven of 56 patients were diagnosed with endometriosis, and 29 were deemed free of the disease based on MRI findings. Surgery confirmed 24 positive MRI findings and identified three false positives. Twenty-seven negative MRI findings were also confirmed, and MRI diagnosed two cases that were not identified during surgery, Golding said.
The study drew the following conclusions regarding MRI's appropriateness for diagnosing endometriosis:
- sensitivity: 88%
- specificity: 93%
- accuracy: 91%
- positive predictive value: 92%
- negative predictive value: 90%
Two of the false positives reported with MR may actually reflect failures in the ability of laparoscopy to uncover deep deposits of disease, according to Golding. If MRI was actually correct in these instances, its accuracy would rise to 94% and its specificity to 100%.
These findings suggest the possibility of using MRI to obviate the need for laparoscopy to confirm endometriosis, Golding said. Some surgeons at the Oxford-affiliated John Radcliffe Hospital have already come to that conclusion.
"If the surgeon is happy with the MR finding, the patient does not go on for confirmation," he said. "Patients may avoid laparoscopy, and that is good medicine."
