Sonography and magnetic resonance (MR) imaging are not associated with fetal risk and are preferred options for imaging in pregnancy
In general, radiation exposure during radiography, computed tomography (C), or nuclear medicine imaging delivers a dose much lower than that associated with fetal harm. If needed to supplement sonography or MR imaging or if more readily available, these should not be withheld
With MR imaging, gadolinium contrast use should be restricted unless it significantly improves diagnostic accuracy to benefit fetal or matenal outcome
Data from American College of Obstetricians and Gynecologists, 20ln7a.
dose, a gadolinium-based contrast agent caused slight developmental delay in rabbit fetuses. De Santis and associates described 26 women given a gadolinium derivative in the first trimester without adverse fetal efects (Kanal, 2013). According to Briggs and colleagues (2015), the American College of Obstetricians and Gynecologists (2017a), and the American College of Radiology (2015), routine use of gadolinium is not recommended unless there are potential benefits that outweigh fetal risks. his recommendation stems from a possible dissociation of the toxic gadolinium ion from its ligand in amnionic Ruid and potential prolonged exposure of the fetus.
In some cases, MR imaging may be complementary to CT, and in others, MR imaging is preferable. Maternal central nervous system abnormalities, such as brain tumors or spinal trauma, are more clearly seen with MR imaging. As discussed in Chapter 40 (p. 723), MR imaging has provided valuable insights into the pathophysiology of preeclampsia (Twickler, 2007; Zeeman, 2003, 2014). It is invaluable in the diagnosis of neurological emergencies (Edlow, 2013). To evaluate the maternal abdomen and retroperitoneal space, MR imaging is a superb technique. It is chosen by many to determine the degree and extent of placenta accreta and its variants (Chap. 41, p. 780). It has been employed for detection and localization of adrenal tumors, renal lesions, gastrointestinal lesions, and pelvic masses in pregnancy. For evaluating neoplasms of the chest, abdomen, and pelvis in pregnancy, it has particular value (Boyd, 2012; Tica, 2013). MR urography has been used successfully for renal urolithiasis (Mullins, 2012). As discussed in Chapter 37 (p. 672), CT and MR imaging are useful for evaluation of puerperal infections, but MR imaging provides better visualization of the bladder Rap area following cesarean delivery (Brown, 1999; Twickler, 1997). MR imaging now includes evaluation of right lower quadrant pain in pregnancy, specifically appendicitis (Fig. 46-5) (Baron, 2012; Dewhurst, 2013; Furey, 2014; Pedrosa, 2009; Tsai, 2017). Investigators have also found other disorders of the gastrointestinal tract to be easily diagnosed with MR imaging (Chap. 54, p. 1043). Finally, cardiac MR imaging has shown promise in investigating normal physiology, complex defects, and cardiomyopathies (Kramer, 2015; Nelson, 2015; Stewart, 2016).