Hope for infertility: Prototype allows MR, hysterosalpingography hybrid imaging

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The fusion of x-ray capabilities with functional imaging technology such as SPECT and PET has resulted in hybrid equipment such as PET/CT, SPECT/CT, and even positron emission mammography (PEM). The utilization of these modalities have resulted in greater diagnostic certainty and enhanced patient management through their advanced visualization capabilities. Until recently, fusing MRI with radiography has been problematic, with most solutions using a moving-bed patient system between MR and x-ray suites.

A team from the department of radiology at The Ottawa Hospital in Ottawa has added to the armamentarium of fusion imaging with the creation and deployment of a MRI/radiography system. Their solution employs a fixed-x-ray source and digital flat-panel detector inside the bore of a 0.5-Tesla magnet (Signa-SP, GE Healthcare).

“This fully integrated setup allows easy and rapid switching between radiography and MRI without needing to move the patient,” the authors wrote. Their investigation into utilization of the modality to conduct pelvic MRI followed by hysterosalpingography (HSG) for assessing fallopian tube patency was published in a recent issue of the American Journal of Roentgenology.

Photograph of hybrid radiography/MRI system shows position of x-ray tube (thin black arrows) and flat-panel detector (long white arrow) between two donut-shaped magnetic poles (thick black arrows) of 0.5-T magnet (Signa-SP, GE Healthcare). Foot pedals for fluoroscopy are indicated with short white arrow. Patients were placed in supine position for acquisition of MR images. For cannulation of cervix, patient was placed in lithotomy position using stirrups attached to inside of magnet. Image and caption by permission of the American Roentgen Ray Society.  

The team examined 10 patients with the hybrid modality, nine that were referred for infertility workups and one for uterine dehiscence after cesarean delivery.

“The fluoroscopic images were of good quality in all but one case,” they reported. “Inadequate x-ray tube output in an early prototype was the cause of poor image quality in that study. In the other nine cases, bilateral tubal patency was shown, with good resolution of the contrast-filled tubes and peritoneal spill. In two patients, contour abnormalities of the endometrial cavity were detected.”

The images from the studies were reviewed by two radiologists, an experienced body imager and a body-imaging fellow. The hybrid exams allowed the interpreting physicians to discover 13 fibroids in five patients; four of the patients’ fibroids were undetectable on HSG and the fifth presented with a contour abnormality of HSG that was determined to be an intramural fibroid abutting the endometrium on MRI. In addition, the utilization of MRI demonstrated malposition of the HSG catheter in three patients, which was able to be corrected during the exam.

Normal study in 36-year-old woman with infertility. Superimposition of coronal MR image and hysterosalpingogram (red) can be performed because two techniques have same field of view and are obtained without moving patient between studies. Image and caption by permission of the American Roentgen Ray Society.  

“We believe that our hybrid radiography/MRI system offers the advantage of incorporating two techniques into one system, thereby streamlining the workup of infertility and identifying unsuspected abnormalities,” the authors wrote.

“An exciting opportunity provided by the hybrid radiography/MRI system is the exact coregistration of the two techniques,” they noted. “As we have shown, this system has the potential to show the cause of hysterographic contour abnormalities with cross-sectional images of myometrial abnormalities, such as fibroids and adenomyosis. Improved image quality and coregistration of images may increase the utility of this new technology.”