Interobserver agreement with the new BI-RADS terminology is good and validates the US lexicon. Subcategories 4a, 4b, and 4c are useful in predicting the likelihood of malignancy.

Low dose (<3 mSv) noncontrast CT (NCCT) is the imaging study of choice for accurate evaluation of patients with acute onset of flank pain and suspicion of stone disease (sensitivity 97%, specificity 95%). NCCT can reliably characterize the location and size of an offending ureteral calculus, identify complications, and diagnose alternative etiologies of abdominal pain such as appendicitis. By comparison, the sensitivity of radiographs (59%) and ultrasound (24-57%) for the detection of renal and ureteral calculi is relatively poor. Ultrasound can accurately diagnose pelvicaliectasis and ureterectasis, but it may take several hours for these findings to develop. In the pregnant patient, however, ultrasound is a first line test as it does not expose the fetus to ionizing radiation. MR is an accurate test for the diagnosis of pelvicaliectasis and ureterectasis, but is less sensitive than CT for the diagnosis of renal and ureteral calculi. For patients with known stone disease whose stones are visible on radiographs, radiographs are a good tool for post-treatment follow-up.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every two years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Imaging plays a key role in the diagnostic evaluation of women for infertility. The pelvic causes of female infertility are varied and range from tubal and peritubal abnormalities to uterine, cervical, and ovarian disorders. In most cases, the imaging work-up begins with hysterosalpingography to evaluate fallopian tube patency. Uterine filling defects and contour abnormalities may be discovered at hysterosalpingography but typically require further characterization with hysterographic or pelvic ultrasonography (US) or pelvic magnetic resonance (MR) imaging. Hysterographic US helps differentiate among uterine synechiae, endometrial polyps, and submucosal leiomyomas. Pelvic US and MR imaging help further differentiate among uterine leiomyomas, adenomyosis, and the various müllerian duct anomalies, with MR imaging being the most sensitive modality for detecting endometriosis. The presence of cervical disease may be inferred initially on the basis of difficulty or failure of cervical cannulation at hysterosalpingography. Ovarian abnormalities are usually detected at US. The appropriate selection of imaging modalities and accurate characterization of the various pelvic causes of infertility are essential because the imaging findings help direct subsequent patient care.

Clinical diagnosis of the cause of abdominal pain in a pregnant patient is particularly difficult because of multiple confounding factors related to normal pregnancy. Magnetic resonance (MR) imaging is useful in evaluation of abdominal pain during pregnancy, as it offers the benefit of cross-sectional imaging without ionizing radiation or evidence of harmful effects to the fetus. MR imaging is often performed specifically for diagnosis of possible appendicitis, which is the most common illness necessitating emergency surgery in pregnant patients. However, it is important to look for pathologic processes outside the appendix that may be an alternative source of abdominal pain. Numerous entities other than appendicitis can cause abdominal pain during pregnancy, including processes of gastrointestinal, hepatobiliary, genitourinary, vascular, and gynecologic origin. MR imaging is useful in diagnosing the cause of abdominal pain in a pregnant patient because of its ability to safely demonstrate a wide range of pathologic conditions in the abdomen and pelvis beyond appendicitis.