Added Value of Contrast-enhanced US for Evaluation of Female Pelvic Disease.

Since the first application of contrast-enhanced US (CEUS) in the late 1960s, the use of US contrast agents has grown tremendously, and this examination has proved to be a valuable adjunct to diagnostic US for detection and characterization of disease. Also, CEUS has emerged as an excellent option for evaluation of indeterminate lesions that require additional imaging, given its excellent safety profile, including that in patients with end-stage renal disease or allergies to contrast material who are unable to undergo contrast-enhanced CT or MRI. US traditionally has been considered the imaging modality of choice for evaluation of the female pelvis, followed by MRI and rarely fluoroscopy, CT, PET, or angiography. CEUS has the potential to add significant value in imaging gynecologic disease, and indications for its use in the female pelvis are expected to continue evolving. It can aid in evaluation of nonvascular structures, such as assessment of tubal patency, uterine cavity morphology, and pelvic fistulas. CEUS can help characterize poorly vascularized gynecologic tumors or tissues with slow flow by using qualitative and quantitative parameters and aid in image-guided interventions or biopsies by facilitating visualization of lesions that are difficult to see with other imaging modalities. The authors provide an overview of current applications of US contrast agents in the female pelvis and discuss associated factors such as technique, interpretation, and image optimization. They also discuss the limitations of CEUS and describe its utility in the evaluation of female pelvic disease by using an organ system case-based approach. © RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Scintigraphy of Gastrointestinal Motility: Best Practices in Assessment of Gastric and Bowel Transit in Adults.

Various radiologic examinations and other diagnostic tools exist for evaluating gastrointestinal diseases. When symptoms of gastrointestinal disease persist and no underlying anatomic or structural abnormality is identified, the diagnosis of functional gastrointestinal disorder is frequently applied. Given its physiologic and quantitative nature, scintigraphy often plays a central role in the diagnosis and treatment of patients with suspected functional gastrointestinal disorder. Most frequently, after functional gallbladder disease is excluded, gastric emptying scintigraphy (GES) is considered the next step in evaluating patients with suspected gastric motility disorder who present with upper gastrointestinal symptoms such as dyspepsia or bloating. GES is the standard modality for detecting delayed gastric emptying (gastroparesis) and the less commonly encountered clinical entity, gastric dumping syndrome. Additionally, GES can be used to assess abnormalities of intragastric distribution, suggesting specific disorders such as impaired fundal accommodation or antral dysfunction, as well as to evaluate gastric emptying of liquid. More recently, scintigraphic examinations for evaluating small bowel and large bowel transit have been developed and validated for routine diagnostic use. These can be performed individually or as part of a comprehensive whole-gut transit evaluation. Such scintigraphic examinations are of particular importance because clinical assessment of suspected functional gastrointestinal disorder frequently fails to accurately localize the site of disease, and those patients may have motility disorders involving multiple portions of the gastrointestinal tract. The authors comprehensively review the current practice of gastrointestinal transit scintigraphy, with diseases and best imaging practices illustrated by means of case review. ©RSNA, 2024 See the invited commentary by Maurer and Parkman in this issue.

Imaging after Pancreatic Surgery: Expected Findings and Postoperative Complications.

Pancreatic surgery is considered one of the most technically challenging surgical procedures, despite the evolution of modern techniques. Neoplasms remain the most common indication for pancreatic surgery, although inflammatory conditions may also prompt surgical evaluation. The choice of surgical procedure depends on the type and location of the pathologic finding because different parts of the pancreas have separate vascular supplies that may be shared by adjacent organs. The surgical approach could be conventional or minimally invasive (laparoscopic, endoscopic, or robotic assisted). Because of the anatomic complexity of the pancreatic bed, perioperative complications may be frequently encountered and commonly involve the pancreatic-biliary, vascular, lymphatic, or bowel systems, irrespective of the surgical technique used. Imaging plays an important role in the assessment of suspected postoperative complications, with CT considered the primary imaging modality, while MRI, digital subtraction angiography, and molecular imaging are considered ancillary diagnostic tools. Accurate diagnosis of postoperative complications requires a solid understanding of pancreatic anatomy, surgical indications, normal postoperative appearance, and expected postsurgical changes. The practicing radiologist should be familiar with the most common perioperative complications, such as anastomotic leak, abscess, and hemorrhage, and be able to differentiate these entities from normal anticipated postoperative changes such as seroma, edema and fat stranding at the surgical site, and perivascular soft-tissue thickening. In addition to evaluation of the primary operative fossa, imaging plays a fundamental role in assessment of the adjacent organ systems secondarily affected after pancreatic surgery, such as vascular, biliary, and enteric complications. Published under a CC BY 4.0 license. Test Your Knowledge questions are available in the supplemental material. See the invited commentary by Winslow in this issue.

Placenta Accreta Spectrum Disorders: Update and Pictorial Review of the SAR-ESUR Joint Consensus Statement for MRI.

Placenta accreta spectrum (PAS) disorders are a major cause of maternal morbidity and mortality and are increasing in incidence owing to a rising rate of cesarean delivery. US is the primary imaging tool for evaluation of PAS disorders, which are most often diagnosed during routine early second-trimester US to assess fetal anatomy. MRI serves as a complementary modality, providing value when the diagnosis is equivocal at US and evaluating the extent and topography of myoinvasion for surgical planning in severe cases. While the definitive diagnosis is established by a combined clinical and histopathologic classification at delivery, accurate antenatal diagnosis and multidisciplinary management are critical to guide treatment and ensure optimal outcomes for these patients. Many MRI features of PAS disorders have been described in the literature. To standardize assessment at MRI, the Society of Abdominal Radiology (SAR) and European Society of Urogenital Radiology (ESUR) released a joint consensus statement to provide guidance for image acquisition, image interpretation, and reporting of PAS disorders. The authors review the role of imaging in diagnosis of PAS disorders, describe the SAR-ESUR consensus statement with a pictorial review of the seven major MRI features recommended for use in diagnosis of PAS disorders, and discuss management of these patients. Familiarity with the spectrum of MRI findings of PAS disorders will provide the radiologist with the tools needed to more accurately diagnose this disease and make a greater impact on the care of these patients. ©RSNA, 2023 Supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Jha and Lyell in this issue.

Pathologic Conditions at Imaging of the Spermatic Cord.

A wide range of benign and malignant processes can affect the spermatic cord (SC). Familiarity with and recognition of the characteristic imaging features of these entities are imperative for accurate diagnosis and optimal clinical care. While some SC diseases are self-limiting, others can result in infertility and potentially life-threatening infection or bleeding if they are left untreated. Therefore, correct diagnosis is important for life-saving treatment and preservation of fertility. Disorders including anomalies of the vas deferens and the processus vaginalis, arterial and venous diseases (torsion of the SC and varicoceles), infection, trauma, and neoplasms are the most pertinent entities with which radiologists should be familiar when assessing the SC. Knowing what to expect in a patient who has undergone SC interventions is imperative. US has a fundamental role in the initial examination of patients who present with symptoms that indicate abnormalities of the SC, such as suspected posttraumatic testicular retraction or SC torsion. Other imaging techniques including abdominal and pelvic MRI and CT have their own importance. For correct interpretation of the findings and to establish an accurate diagnosis, it is crucial to have a thorough knowledge of the anatomy, the utility and limitations of various imaging modalities, optimal imaging and scanning techniques, and the imaging features of various benign and malignant pathologic conditions that can involve the SC. Online supplemental material is available for this article. ©RSNA, 2022.

Manifestations of Sickle Cell Disorder at Abdominal and Pelvic Imaging.

Sickle cell disorder (SCD) refers to a spectrum of hematologic disorders that cause a characteristic clinical syndrome affecting the entire body. It is the most prevalent monogenetic hemoglobinopathy worldwide, with a wide range of focal and systemic expressions. Hemoglobin gene mutation leads to the formation of abnormal sickle-shaped red blood cells, which cause vascular occlusion and result in tissue and organ ischemia and infarction. Recurrent episodes of acute illness lead to progressive multisystem organ damage and dysfunction. Vaso-occlusion, hemolysis, and infection as a result of functional asplenia are at the core of the disease manifestations. Imaging plays an essential role in the diagnosis and management of SCD-related complications in the abdomen and pelvis. A thorough understanding of the key imaging findings of SCD complications involving hepatobiliary, gastrointestinal, genitourinary, and musculoskeletal systems is crucial to timely recognition and accurate diagnosis. The authors aim to familiarize the radiologist with the SCD spectrum, focusing on the detection and evaluation of manifestations that may appear at imaging of the abdomen and pelvis. The topics the authors address include (a) the pathophysiology of the disease, (b) the placement of SCD among hemoglobinopathies, (c) the clinical presentation of SCD, (d) the role of imaging in the evaluation and diagnosis of patients with SCD who present with abdominal and pelvic manifestations in addition to extraperitoneal manifestations detectable at abdominal or pelvic imaging, (e) imaging features associated with common and uncommon sequelae of SCD in abdominal and pelvic imaging studies, and (f) a brief overview of management and treatment of patients with SCD. Online supplemental material is available for this article. ©RSNA, 2022.

Fluoroscopic Evaluation of Duodenal Diseases.

The duodenum can be affected by a variety of abnormalities because of its development during embryogenesis and its dual intra- and retroperitoneal location. If small bowel embryogenesis is disturbed, congenital errors occur. Although some congenital variants may be asymptomatic and inconsequential to the patient, other anomalies can result in life-threatening emergencies such as malrotation, leading to midgut volvulus. Many infectious processes affect the duodenum, including duodenal ulcers and opportunistic infection in patients with HIV/AIDS or Crohn disease. Small bowel malignancies are uncommon but important to recognize, because the duodenum can be involved in polyposis syndromes or the development of primary adenocarcinoma, neuroendocrine tumors, lymphoma, and metastasis. Although endoscopy is currently the most used diagnostic method to assess the lumen of the upper gastrointestinal tract, fluoroscopy is a valuable adjunct technique and the study of choice for many diseases, specifically those for which anatomic and functional information is required. Fluoroscopy is also commonly used postoperatively to assess for complications such as obstruction and extraluminal leaks. Compared with endoscopy, fluoroscopy is an inexpensive and noninvasive technique that provides salient anatomic information and allows delineation of the duodenal mucosa and assessment of real-time duodenal motility. The authors examine the broad spectrum of conditions that can involve the duodenum, including congenital, infectious, inflammatory, and neoplastic abnormalities, and review their typical appearances at fluoroscopy. Online supplemental material is available for this article. ©RSNA, 2022.

Imaging Review of Obstetric Sequelae of Maternal Diabetes Mellitus.

Diabetes mellitus, whether preexisting or gestational, poses significant risk to both the mother and the developing fetus. A myriad of potential fetal complications in the setting of diabetic pregnancies include, among others, congenital anomalies, delayed fetal lung maturity, macrosomia, and increased perinatal morbidity and mortality. Congenital anomalies most commonly involve the nervous, cardiovascular, genitourinary, and musculoskeletal systems. Delayed fetal lung maturity, probably secondary to hyperglycemia suppressing surfactant secretion, is a major determinant of perinatal morbidity and mortality. Besides the potential complications encountered during cesarean delivery in macrosomic fetuses, vaginal delivery is also associated with increased risks of shoulder dystocia, clavicular and humeral fractures, and brachial plexus palsy. Maternal complications are related to the increased risk of hypertensive diseases of pregnancy and associated preeclampsia and hemolysis, elevated liver function, and low platelets (HELLP) syndrome, as well as complications encountered at the time of delivery secondary to fetal macrosomia and cesarean delivery. Additional conditions encountered in the setting of maternal diabetes include polyhydramnios, placental thickening, and two-vessel umbilical cord, each of which is associated with adverse fetal and maternal outcomes including fetal growth restriction, preterm labor, placental abruption, and premature rupture of membranes. Imaging plays a vital role in the evaluation of the mother and the fetus and can provide invaluable information that can be used by maternal fetal medicine to manage this patient population effectively. The authors review the pathophysiologic alterations induced by diabetes in pregnancy, discuss the imaging spectrum of diabetic embryopathy, and provide a detailed review of potential associated maternal complications. Online supplemental material is available for this article. ©RSNA, 2021.

Imaging Cancer in Pregnancy.

Pregnancy-associated cancer (PAC) is defined as cancer that is detected during pregnancy and up to 1 year postpartum. Although rare (~1:1000 pregnancies), PAC is increasing owing to postponed childbearing and advanced maternal age at conception. Cancer-related symptoms masked by physiologic gestational changes may delay diagnosis. Imaging, clinical management, and treatment require a carefully choreographed multidisciplinary team approach. The risk-benefit of every imaging modality, the strategies to balance the safety of mother and fetus, and the support of the patient and family at every step are crucial. US and MRI are preferred imaging modalities that lack ionizing radiation. Radiation dose concerns should be addressed, noting that most imaging examinations (including mammography, radiography, CT, and technetium 99m-labeled sulfur colloid sentinel lymph node staging) are performed at radiation levels below thresholds at which deterministic side effects are seen. Dose estimates should be provided after each examination. The use of iodinated intravenous contrast material is safe during pregnancy, but gadolinium-based contrast material should be avoided. Accurate diagnosis and staging combined with gestational age affect decisions about surgery and chemotherapy. Whole-body MRI with diffusion-weighted sequences is ideal to screen for primary and metastatic sites, determine disease stage, identify biopsy targets, and guide further cancer site-specific imaging. The authors provide an update of the imaging triage, safety considerations, cancer-specific imaging, and treatment options for cancer in pregnancy. An invited commentary by Silverstein and Van Loon is available online. Online supplemental material is available for this article. ©RSNA, 2022.

Role of Imaging in Obstetric Interventions: Criteria, Considerations, and Complications.

US has an established role in the prenatal detection of congenital and developmental disorders. Many pregnant women undergo US at 18-20 weeks of gestation for assessment of fetal anatomy and detection of structural anomalies. With advances in fetoscopy and minimally invasive procedures, in utero fetal interventions can be offered to address some of the detected structural and physiologic fetal abnormalities. Most interventions are reserved for conditions that, if left untreated, often cause in utero death or a substantially compromised neonatal outcome. US is crucial for preprocedural evaluation and planning, real-time procedural guidance, and monitoring and assessment of postprocedural complications. Percutaneous needle-based interventions include in utero transfusion, thoracentesis and placement of a thoracoamniotic shunt, vesicocentesis and placement of a vesicoamniotic shunt, and aortic valvuloplasty. Fetoscopic interventions include myelomeningocele repair and tracheal balloon occlusion for congenital diaphragmatic hernia. In rare cases, open hysterotomy may be required for repair of a myelomeningocele or resection of a sacrococcygeal teratoma. Monochorionic twin pregnancies involve specific complications such as twin-twin transfusion syndrome, which is treated with fetoscopic laser ablation of vascular connections, and twin reversed arterial perfusion sequence, which is treated with radiofrequency ablation. Finally, when extended placental support is necessary at delivery for repair of congenital high airway obstruction or resection of lung masses, ex utero intrapartum treatment can be planned. Radiologists should be aware of the congenital anomalies that are amenable to in utero interventions and, when necessary, consider referral to centers where such treatments are offered. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ©RSNA, 2021.

Use of Methotrexate in Gynecologic and Obstetric Practice: What the Radiologist Needs to Know.

Methotrexate (MTX) is the primary pharmaceutical agent that is used for management of disorders arising from trophoblastic tissue. Its widespread international use is mostly attributable to its noninvasive, safe, and effective characteristics as a treatment option for ectopic pregnancy (EP) and gestational trophoblastic disease (GTD), with the large added benefit of fertility preservation. Although the effects of MTX usage are well documented in the gynecologic and obstetric literature, there is a scarcity of radiologic literature on the subject. Depending on the type of EP, the route of MTX administration and dosage may vary. US plays an essential role in the diagnosis and differentiation of various types of EPs, pregnancy-related complications, and complications related to MTX therapy, as well as the assessment of eligibility criteria for MTX usage. A knowledge of expected imaging findings following MTX treatment, including variability in echogenicity and shape of the EP, size fluctuations, changes in vascularity and gestational sac content, and the extent of hemoperitoneum, is essential for appropriate patient management and avoidance of unnecessary invasive procedures. A recognition of sonographic findings associated with pregnancy progression and complications such as tubal or uterine rupture, severe hemorrhage, septic abortion, and development of arteriovenous communications ensures prompt patient surgical management. The authors discuss the use of MTX in the treatment of disorders arising from trophoblastic tissue (namely EP and GTD), its mechanism of action, its route of administration, and various treatment regimens. The authors also provide a focused discussion of the role of US in the detection and diagnosis of EP and GTD, the assessment of the eligibility criteria for MTX use, and the identification of the sonographic findings seen following MTX treatment, with specific emphasis on imaging findings associated with MTX treatment success and failure. Online supplemental material is available for this article. ©RSNA, 2021.

Multimodality Imaging Evaluation of Fetal Spine Anomalies with Postnatal Correlation.

Congenital anomalies of the spine are associated with substantial morbidity in the perinatal period and may affect the rest of the patient's life. Accurate early diagnosis of spinal abnormalities during fetal imaging allows prenatal, perinatal, and postnatal treatment planning, which can substantially affect functional outcomes. The most common and clinically relevant congenital anomalies of the spine fall into three broad categories: spinal dysraphism, segmentation and fusion anomalies of the vertebral column, and sacrococcygeal teratomas. Spinal dysraphism is further categorized into one of two subtypes: open spinal dysraphism and closed spinal dysraphism. The latter category is further subdivided into those with and without subcutaneous masses. Open spinal dysraphism is an emergency and must be closed at birth because of the risk of infection. In utero closure is also offered at some fetal centers. Sacrococcygeal teratomas are the most common fetal pelvic masses and the prognosis is variable. Finally, vertebral body anomalies are categorized into formation (butterfly and hemivertebrae) and segmentation (block vertebrae) anomalies. Although appropriate evaluation of the fetal spine begins with US, which is the initial screening modality of choice, MRI is increasingly important as a problem-solving tool, especially given the recent advances in fetal MRI, its availability, and the complexity of fetal interventions. Online supplemental material is available for this article. ©RSNA, 2021.

Prospective Clinical Trials: 10-year Trends in Radiology.

Online supplemental material is available for this article.

An Algorithmic Approach to Complex Fetal Abdominal Wall Defects.

OBJECTIVE. The purpose of this article is to describe the imaging findings associated with complex fetal abdominal wall defects and provide an algorithmic method for arriving at a final diagnosis. CONCLUSION. Fetal ventral abdominal wall defects are a complex group of conditions with a broad spectrum of associated multisystem anomalies and manifestations. Correct characterization and classification of these defects require not only familiarity with imaging findings but also a systematic approach to avoid diagnostic confusion.

Imaging Evaluation of Fallopian Tubes and Related Disease: A Primer for Radiologists.

A wide range of benign and malignant processes can affect one or both fallopian tubes. Familiarity with and recognition of the characteristic imaging features of these diseases and conditions are imperative for accurate diagnosis and prompt patient management. Disorders including pelvic inflammatory disease (hydrosalpinx and pyosalpinx in particular), isolated tubal torsion and ovarian torsion with fallopian tube involvement, endometriosis manifesting as hematosalpinx and adhesions, ectopic pregnancy, and malignancies are the most important entities that radiologists should be familiar with when assessing the fallopian tubes. Some fallopian tube diseases are self-limiting, while others can result in infertility or even potentially life-threatening infection or bleeding if left untreated. Therefore, correct diagnosis is important for appropriate life-saving treatment and preserving fertility. Understanding the physiologic features of the fallopian tube and the role of this organ in the pathogenesis of pelvic neoplasms is equally important. Knowledge of what to expect in a patient who has undergone uterine and fallopian tube interventions, such as uterine ablation and fallopian tube ligation, and of the potential associated complications (eg, postablation sterilization syndrome) also is pertinent. The imaging modalities used for the evaluation of fallopian tube disease and patency range from commonly used examinations such as US, CT, and MRI to other modalities such as hysterosalpingography and hysterosonography performed by using US contrast material. The ability to differentiate fallopian tube conditions from other adnexal and pelvic pathologic entities by using a variety of imaging modalities allows the radiologist to make a timely diagnosis and ensure proper clinical management. Online supplemental material is available for this article. ©RSNA, 2020.

Imaging Evaluation of Abdominopelvic Gunshot Trauma.

Firearm-related injuries, or gunshot wounds (GSWs), are among the most important worldwide public health problems, resulting in considerable annual morbidity, disability, and mortality. GSWs to the abdomen and pelvis are associated with substantial injuries to multiple organs and tissues. Imaging plays an important role in identifying these injuries, dictating nonoperative management, and determining imaging and clinical follow-up, as well as helping manage potential long-term complications. CT is the primary imaging modality used to evaluate these injuries and their complications, including use of reconstructed multiplanar volume-rendered images. The authors discuss the ballistics and mechanisms of firearm injury, CT findings, trajectory analysis, and applications of different imaging modalities above and beyond CT in evaluation of GSWs. Imaging findings and classifications of the severity of injuries to solid and hollow organs and vascular, musculoskeletal, and neurologic systems are reviewed. Key complications associated with gunshot injuries to the abdomen and pelvis are presented. The challenges of imaging in the acute trauma setting and potential pitfall mimics at imaging, particularly at CT, are also described. A step-by-step guide for thorough and comprehensive evaluation of GSWs to the abdomen and pelvis is introduced, with tips for optimizing effective communication with the clinical team. Online supplemental material is available for this article. ©RSNA, 2020.

CT Detectability of Small Low-Contrast Hypoattenuating Focal Lesions: Iterative Reconstructions versus Filtered Back Projection.

Purpose To investigate performance in detectability of small (≤1 cm) low-contrast hypoattenuating focal lesions by using filtered back projection (FBP) and iterative reconstruction (IR) algorithms from two major CT vendors across a range of 11 radiation exposures. Materials and Methods A low-contrast detectability phantom consisting of 21 low-contrast hypoattenuating focal objects (seven sizes between 2.4 and 10.0 mm, three contrast levels) embedded into a liver-equivalent background was scanned at 11 radiation exposures (volume CT dose index range, 0.5-18.0 mGy; size-specific dose estimate [SSDE] range, 0.8-30.6 mGy) with four high-end CT platforms. Data sets were reconstructed by using FBP and varied strengths of image-based, model-based, and hybrid IRs. Sixteen observers evaluated all data sets for lesion detectability by using a two-alternative-forced-choice (2AFC) paradigm. Diagnostic performances were evaluated by calculating area under the receiver operating characteristic curve (AUC) and by performing noninferiority analyses. Results At benchmark exposure, FBP yielded a mean AUC of 0.79 ± 0.09 (standard deviation) across all platforms which, on average, was approximately 2% lower than that observed with the different IR algorithms, which showed an average AUC of 0.81 ± 0.09 (P = .12). Radiation decreases of 30%, 50%, and 80% resulted in similar declines of observer detectability with FBP (mean AUC decrease, -0.02 ± 0.05, -0.03 ± 0.05, and -0.05 ± 0.05, respectively) and all IR methods investigated (mean AUC decrease, -0.00 ± 0.05, -0.04 ± 0.05, and -0.04 ± 0.05, respectively). For each radiation level and CT platform, variance in performance across observers was greater than that across reconstruction algorithms (P = .03). Conclusion Iterative reconstruction algorithms have limited radiation optimization potential in detectability of small low-contrast hypoattenuating focal lesions. This task may be further complicated by a high degree of variation in radiologists' performances, seemingly exceeding real performance differences among reconstruction algorithms. © RSNA, 2018 Online supplemental material is available for this article.

Fetal Urinary Tract Anomalies: Review of Pathophysiology, Imaging, and Management.

OBJECTIVE: Common fetal anomalies of the kidneys and urinary tract encompass a complex spectrum of abnormalities that can be detected prenatally by ultrasound. Common fetal anomalies of the kidneys and urinary tract can affect amniotic fluid volume production with the development of oligohydramnios or anhydramnios, resulting in fetal pulmonary hypoplasia and, potentially, abnormal development of other fetal structures. CONCLUSION: We provide an overview of common fetal anomalies of the kidneys and urinary tract with an emphasis on sonographic patterns as well as pathologic and postnatal correlation, along with brief recommendations for postnatal management. Of note, we render an updated classification of fetal abnormalities of the kidneys and urinary tract based on the presence or absence of associated urinary tract dilation. In addition, we review the 2014 classification of urinary tract dilation based on the Linthicum multidisciplinary consensus panel.

Placental Imaging: Normal Appearance with Review of Pathologic Findings.

The placenta plays a crucial role throughout pregnancy, and its importance may be overlooked during routine antenatal imaging evaluation. Detailed systematic assessment of the placenta at ultrasonography (US), the standard imaging examination during pregnancy, is important. Familiarity with the normal and abnormal imaging appearance of the placenta along with the multimodality and methodical approach for evaluation of its related abnormalities is necessary, so that radiologists can alert clinicians regarding appropriate prompt management decisions. This will potentially decrease fetal and maternal morbidity and mortality. This article reviews early placental formation and the expected imaging appearance of the placenta during pregnancy, as well as variations in its morphology. It also discusses various placental diseases and their potential clinical consequences. Placental pathologic conditions include abnormalities of placental size, cord insertion, placental and cord location, and placental adherence. Other conditions such as bleeding in and around the placenta, as well as trophoblastic and nontrophoblastic tumors of the placenta, are also discussed. US with Doppler imaging is the initial imaging modality of choice for placental evaluation. Magnetic resonance (MR) imaging is reserved for equivocal cases or when additional information is needed. Computed tomography (CT) has a limited role in evaluation of placental abnormalities because of the ionizing radiation exposure and the relatively limited assessment of the placenta; however, CT can provide important information in specific circumstances, particularly evaluation of trauma and staging of choriocarcinoma. This article also addresses recent techniques and updates in placental imaging, including elastography, diffusion-weighted MR imaging, and blood oxygen level-dependent (BOLD) MR imaging. These advanced imaging techniques may provide additional information in evaluation of abnormal placental adherence and new insights into placental pathophysiology in selected patients. Online supplemental material is available for this article. ©RSNA, 2017.