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Cranial

Introduction Transcranial ultrasound (US) is commonly used to evaluate complications of prematurity, in which case it may be used as a screening tool, or to evaluate infants with seizures, apnea, bradycardia, or falling hematocrit. When used to screen premature infants, it is often performed around day 5 of life, with further imaging performed as needed. Head US is also useful in older infants presenting with macrocephaly,…

Carotid Artery

Clinical Correlation The most common disease affecting the carotid arteries is atherosclerosis. Other less common, but clinically important conditions include dissection, trauma, and carotid body tumors. The carotid bifurcation is a common location for the development of atherosclerotic plaque. Although usually asymptomatic, atherosclerosis of the carotid bifurcation may become unstable and cause monocular blindness, transient cerebral ischemia, or stroke. Monocular blindness may be temporary (also known…

Ocular

Introduction Ocular point-of-care ultrasound (POCUS) can rapidly identify ocular emergencies, including the diagnoses of lens detachment/dislocations, retinal detachment, vitreous detachment, vitreous hemorrhage, ocular infections, the presence of foreign bodies, and secondary signs of elevated intracranial pressure. In a fast-paced clinical practice, a fully dilated ophthalmologic examination may be impractical, and studies have shown that many practitioners lack the clinical skills to perform it effectively. The benefits…

Neck Masses

Introduction In the emergency department setting, the use of head and neck ultrasound has become a valuable tool to expedite the diagnosis of familiar diseases and facilitate common procedures. For head and neck pathology, ultrasound is often favored over computed tomography (CT) because it is readily available at the bedside and does not expose the patient to ionizing radiation. In this chapter we will describe the…

Peritonsillar Abscess

Clinical Considerations Patients with soft tissue infections of the oropharynx and neck commonly present to the emergency department and other frontline medical providers. Peritonsillar abscess (PTA) is the most common deep infection of the neck and face. PTAs develop from tonsillitis, which progress to peritonsillar cellulitis and then onto abscesses. Although peritonsillar cellulitis and PTAs may be considered a spectrum of disease, they are important to…

Ultrasound Artifacts

Introduction Ultrasound artifacts represent a false portrayal of image anatomy or image degradations related to false assumptions regarding the propagation and interaction of ultrasound with tissues, as well as malfunctioning or maladjusted equipment. Understanding how artifacts are generated and how they can be recognized is crucial, which places high demands on the knowledge of the sonographer and the interpreting physician. Most artifacts arise from violations of…

Physics of Ultrasound

Imaging systems using ultrasound have attained a large presence as point-of-care (PoC) devices across many clinical domains over the past 10 years. The success of ultrasound for this purpose is attributed to several characteristics, including the low cost and portability of ultrasound devices, the nonionizing nature of ultrasound waves, and the ability to produce real-time images of the acoustic properties of the tissues and tissue structures…

MRI of the Ovaries and Adnexa

▪ Introduction The evaluation of the adnexa pivots on the unique spectroscopic capability of magnetic resonance (MR) to differentiate between lesions of different tissue composition, such as lipid (dermoid cyst), water (functional ovarian cyst), and hemorrhage (endometrioma). Improved tissue contrast elevates the sensitivity for neoplastic and malignant features compared with other modalities. The most common indications for MRI of the ovaries and adnexa include characterization of…

MRI of the Uterus, Cervix, and Vagina

▪ Introduction Magnetic resonance imaging (MRI) serves as the most comprehensive and conclusive imaging modality available to image the female pelvis. The inherent zonal anatomy of the uterus is exquisitely depicted as a function of the different water content and histology of each mural layer. The predictable MR appearance of the uterus renders identification of abnormalities straightforward ( Fig. 9.1 ). Improved tissue contrast elevates the…

MRI of the Gastrointestinal System

▪ Introduction Although computed tomography (CT) has been and still is the mainstay for imaging the gastrointestinal (GI) tract, small bowel and colorectal magnetic resonance (MR) applications have been developed and increasingly adopted in recent years. MR enterography evaluates the small bowel for inflammatory processes, such as Crohn’s disease, neoplasms, and etiologies of obstruction and bleeding. Colorectal applications include rectal cancer staging, anal fistula evaluation, and…

MRI of the Adrenal Glands and Retroperitoneum

▪ Introduction Extreme sensitivity to the microscopic lipid—present in the form of cholesterol and cholesterol/lipid-based derivatives and adrenal adenomas—and the ability to detect other substances, such as hemorrhage, are the major reasons why MRI is so useful in adrenal imaging. Deviation from either normal Y-shaped morphology or microscopic lipid content generally connotes pathology. Typical indications for MRI in renal and adrenal imaging include indeterminate adrenal lesion…

MRI of the Kidneys, Ureters, and Urinary Bladder

▪ Introduction The tissue contrast and spectroscopic properties of magnetic resonance imaging (MRI) recommend its use as a problem solver for renal and urinary imaging. The unsurpassed ability to discriminate cystic from solid lesions and higher sensitivity to solid, neoplastic elements explains the superiority of MRI compared with other imaging modalities for imaging the kidney. Regarding the collecting system, ureters, and bladder, MRI features exquisite tissue…

MRI of the Pancreas and Spleen

▪ Pancreas Anatomy and Function The pancreas is a nonencapsulated organ of the digestive system located within the retroperitoneum, posterior to the stomach and anterior to the spine. The pancreas is approximately 2 inches wide and 6 to 8 inches in length. The pancreas can be subdivided into the head, uncinate process, neck, body, and tail ( Fig. 5.1 ). The head and uncinate process are…

MRI of the Gallbladder and Biliary System

▪ Gallbladder Anatomy The gallbladder is an ovoid cystic organ along the undersurface of the liver at the interlobar fissure, between the right and the left lobes of the liver. Although the size and shape of the gallbladder vary with the fasting state, it is approximately 10 cm long and 3 to 5 cm in diameter. The normal capacity of the gallbladder is approximately 50 mL.…

MRI of Diffuse Liver Disease

▪ Introduction Diffuse liver processes range from incidental signal and/or enhancement derangements, such as steatosis or transient hepatic intensity differences (THIDs), to serious, and potentially end-stage parenchymal disorders, such as cirrhosis and Budd-Chiari Syndrome (BCS). Segmental, or geographic lesions typically fall into one of two categories—(abnormal) signal or enhancement lesions. Diffuse liver disorders stratify into either: 1) primarily signal, 2) fundamental morphology, or 3) imaging occult…

MRI of Focal Liver Lesions

▪ Introduction Magnetic resonance imaging (MRI) is the most comprehensive and definitive noninvasive modality for evaluating the liver. A combination of enhancement characteristics and exquisite tissue contrast allows for the characterization of liver lesions. Unique artifacts—such as susceptibility and chemical shift—allow for sensitive detection of hepatic iron and lipid deposition, respectively. Common indications for liver MRI include liver lesion characterization, hepatic steatosis quantification and surveillance, liver…

Introduction and Physics of Body MRI

▪ Magnetic Resonance Imaging: What is the Objective? Magnetic resonance imaging (MRI) exploits the inherent magnetism of the protons that constitute the human body in a creative way—through manipulation with radiofrequency (Rf) energy in the presence of a strong magnetic field. This manipulation induces the protons to emit energy, which is detected and reconstructed into an image. The human body—not ostensibly magnetic—is effectively magnetized by a…

CT in Musculoskeletal Nontrauma

In this chapter entities such as disk disease and the osseous structures of the spinal canal will be discussed again, as well as postoperative spine changes. The appearances of the bones in the setting of some systemic diseases are additional descriptions in this chapter as are the incidentally encountered abnormalities in the axial skeleton and ribs when evaluation of chest-abdomen-pelvis imaging is performed. Metallic implants and…