E2850. MRI of Pregnant Patients in the Emergency Setting: Imaging Highlights and Pitfalls
Authors
Toan Nguyen;
University of Texas Southwestern Medical Center
Charles Finch;
University of Texas Southwestern Medical Center
Jovan Begovic;
University of Texas Southwestern Medical Center
Taemee Pak;
University of Texas Southwestern Medical Center
Ivan Pedrosa;
University of Texas Southwestern Medical Center
Gaurav Khatri;
University of Texas Southwestern Medical Center
Background
Magnetic Resonance Imaging (MRI) is frequently employed for evaluation of acute abdominal pain in pregnant patients due to increased access and advances in MRI technology. Radiologists need to be familiar with MRI safety and techniques in pregnancy, and also be well-versed in characteristic acute MRI findings and pitfalls in pregnant patients.
Educational Goals / Teaching Points
This exhibit reviews MRI indications and contraindications, appropriate techniques, as well as imaging characteristics and pitfalls of various acute abdominopelvic pathologies in pregnant patients.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
MRI is often preferred over computed tomography for evaluation of acute abdominal symptoms in pregnant patients, particularly when ultrasound is unrevealing. Gadolinium-based contrast agents are contraindicated in most cases during pregnancy due to known deleterious effects on the fetus. Our institutional non-contrast Acute Abdomen MRI Protocol in pregnant patients consists of multiplanar T2-weighted (T2W), fat-suppressed T2W, non-contrast T1-weighted (T1W), diffusion-weighted, axial time-of-flight (TOF), and optional three-dimensional axial balanced steady state free precession sequences. In contrast to non-pregnant patients, in pregnant patients, the appendix is often displaced superiorly due to the gravid uterus. Sagittal T2W images help determine the orientation of the cecum which in turn helps determine the location of the appendix. Physiologic dilated gonadal vessels in the right lower quadrant/pelvis can mimic a dilated appendix. TOF images can help differentiate vessels with blood flowing perpendicular to the plane of image from the appendix. Physiologic hydronephrosis of pregnancy can mimic obstructive pathologic hydronephrosis but should be suspected based on the gradual tapering of the dilated ureter at the level of the iliac vessels at the pelvic inlet. Nephrolithiasis or other obstructive pathology should be considered when there is an abrupt transition of the ureter in the lower pelvis. A pseudo-stone may be seen in the ureter due to flow-related artifact on T2W single shot acquisitions and appear as a central non-dependent filling defect that does not persist on different planes of imaging. Upper abdominal conditions such as choledocholithiasis or pancreatitis, adnexal pathologies such as torsion, tubo-ovarian abscesses, or ovarian masses, and other critical entities such as hemo- or pneumoperitoneum and vascular thromboses have characteristic appearances on MRI.
Conclusion
MRI is becoming more instrumental in the evaluation of pregnant patients with acute abdominal symptoms. It is important for radiologists to be familiar with the MRI safety, techniques, imaging characteristics and pitfalls in the setting of pregnancy to enable safe and accurate diagnoses.
