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Urinary Tract

Over the years, radiopharmaceuticals and scintigraphic techniques have been developed to assess different aspects of renal function. Using a variety of radiopharmaceuticals, these techniques can answer clinical questions not possible with ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). Some indications for nuclear scintigraphy are listed in Box 11.1 . These include problem-solving and quantification applications that break down roughly into issues related to function…

Gastrointestinal System

The use of a radionuclide to measure gastric transit was first described in 1966. Radionuclide gastric emptying scintigraphy has long been the standard methodology for measuring gastric transit. In this section, the recommended standardized gastric emptying protocol is described in some detail, followed by a discussion of esophageal and intestinal transit ( Fig. 10.1 ). Other topics include gastrointestinal bleeding, Meckel, peritoneal, and salivary gland scans.…

Hepatic, Biliary, and Splenic Scintigraphy

Liver, biliary, and splenic scintigraphy have played an important diagnostic imaging role in patient management since the 1960s. Today’s radiopharmaceuticals have mechanisms of uptake and localization that take advantage of the complex anatomy and physiology of the liver ( Table 9.1 ; Figs. 9.1 to 9.4 ). Although many of the radiopharmaceuticals, methodologies, and indications have changed, hepatobiliary and splenic scintigraphy continue to provide unique functional…

Endocrine System

Thyroid Disease—Radionuclide Diagnosis and Therapy In 1941, the first patient was treated for thyroid cancer with radioiodine. Since then, radioiodine has proven invaluable in the assessment of thyroid disorders and treatment of thyroid cancer, Graves disease, and toxic thyroid nodules. Today, radioiodine I-123 and I-131 remain important diagnostic and therapeutic modalities, and the use of positron emission tomography (PET) iodine-124 is growing. Thyroid Anatomy and Physiology…

The Pulmonary System

Introduction: The Ventilation–Perfusion Lung Scan Particles slightly larger than red blood cells can be radiolabeled and injected into a peripheral vein. After passing through the heart and central pulmonary arteries, they finally lodge in the peripheral lung capillaries, creating a map of pulmonary blood flow that can be imaged with a gamma camera. Similarly, inhalation of a radiolabeled gas or aerosol can allow ventilation imaging. These…

The Skeletal System

Made up of inorganic calcium hydroxyapatite (Ca 10 [PO 4 ] 6 [OH] 2) crystal and an organic matrix of collagen and blood vessels, the skeleton is constantly changing and remodeling. This physiological activity can be imaged with radioactive analogs of calcium, phosphate, or hydroxyl ions (OH – ) that can localize to the bone, with areas of growth or repair resulting in increased turnover. Whereas…

Molecular Imaging

Molecular imaging (MI) allows noninvasive visualization and quantification of functions occurring at the cellular or molecular level. This can involve several different techniques ( Table 5.1 ), but tagging a targeted probe with a radioactive molecule is one of the most important. This label makes imaging and quantitation possible with only small (or tracer) amounts of the probe, helping to minimize the impact on the patient…

Radiopharmaceuticals

An unstable atom that undergoes radioactive decay in order to achieve stability is known as a radionuclide. The radiation these atoms emit can sometimes be used in medical imaging and therapy. Agents approved for such uses in humans that incorporate radioactive molecules are referred to as radiopharmaceuticals. Radiopharmaceuticals can portray physiology, biochemistry, or pathology in the body without causing any significant physiological effect. They are also…

Single-Photon Emission Computed Tomography, Positron Emission Tomography, and Hybrid Imaging

Data Acquisition of Emission Tomographyn Conventional or planar radionuclide imaging suffers a major limitation in the loss of object contrast as a result of background radioactivity. In the planar image, radioactivity underlying and overlying the object of interest is superimposed on that coming from the object. The fundamental goal of tomographic imaging systems is a more accurate portrayal of the three-dimensional (3D) distribution of radioactivity in…

Radiation Detection & Ancillary Instrumentation

The passage of radiation, such as x-rays and gamma rays, through a given material leads to ionizations and excitations that can be used to quantify the amount of energy deposited. This property allows measurement of the level of intensity of a radiation beam or small amounts of radionuclides, including from within the patient. The appropriate choice of detection approach depends on the purpose. In some cases,…

Radioactivity and Radionuclides

In nuclear medicine, radiopharmaceuticals given to the patient emit the radiation used to create images or perform therapy. In order to understand how these agents perform and what safety considerations are involved in their use, it is necessary to be familiar with some basic aspects of the physics behind radioactive decay. This chapter discusses radioactive molecules, different types of radioactive decay, and how these emissions interact…

Paget’s Disease

Introduction Paget's disease, or osteitis deformans, is a chronic metabolic disorder characterized by increased bone turnover and breakdown secondary to excessive and disorganized osteoclastic and osteoblastic activity ( Fig. 48.1 ). The precise etiology is still unclear. The excessive breakdown of bone is followed by the formation of weak and abnormal bone. Over time this robust and disordered bone metabolism can result in enlarged and/or deformed…

Otospongiosis

Introduction Otospongiosis, also known as otosclerosis, is a progressive primary bone disorder of abnormal bone resorption and deposition. The majority of cases result in a progressive conductive hearing loss with severe cases evolving to a combination of conductive and sensorineural hearing loss. The clinical prevalence of otospongiosis is estimated to be 0.3%, although histologic studies have reported a prevalence between 8% and 11%, indicating that many…

Vocal Cord Augmentation/Injection Laryngoplasty

Introduction Injection laryngoplasty is performed for treatment of vocal cord paralysis, which may have a variety of causes ( Box 46.1 ). Imaging during a Valsalva maneuver demonstrates the mechanical and physiologic barriers that patients with unilateral vocal cord paralysis endure ( Fig. 46.1 ). Vocal cord augmentation procedures attempt to overcome these barriers by medializing the affected vocal fold, thus allowing for better phonation and…

Esthesioneuroblastoma

Introduction Esthesioneuroblastoma (olfactory neuroblastoma) is an uncommon malignancy of the nasal cavity. Esthesioneuroblastoma represents 3% to 6% of sinonasal malignancies and has an estimated incidence of 0.4 cases per 1 million people. This tumor has been reported across a wide age range (2 to 94 years) and has no sex predilection. Some case series document a bimodal age peak in the second and sixth decades ;…

Paraganglioma

Introduction Paragangliomas of the head and neck are rare neoplasms of neural crest cell origin. The four most common sites for paragangliomas within the head and neck are at the carotid body, the jugular foramen, in the middle ear, and along the vagus nerve. Rarely, paragangliomas have been found within the larynx, orbit, thyroid gland, nasopharynx, mandible, soft palate, face, and cheek. Carotid body tumors account…

Labyrinthitis

Introduction Labyrinthitis, also known as otitis interna, is an inflammatory disorder of the inner ear. Inflammation of the perilymphatic spaces results in secondary changes within the membranous labyrinth, the most common symptoms of which are sensorineural hearing loss and vertigo. Causes of labyrinthitis are most commonly classified either by mode of spread (tympanogenic, meningogenic, hematogenic, posttraumatic) or by causative agent (viral, bacterial, autoimmune, syphilitic). Viruses are…

Cholesteatoma

Introduction A cholesteatoma is a cystic mass filled with keratin and lined by stratified squamous epithelium. Cholesteatoma is not a neoplasm and can be thought of most simply as skin in the wrong place. Although a cholesteatoma is histologically identical to an epidermoid or epidermal inclusion cyst, the term “cholesteatoma” is preferred for a lesion located in the middle or external ear ( Fig. 42.1 ).…

Sjögren Syndrome

Introduction Sjögren syndrome (SS) is a chronic autoimmune disorder characterized by inflammatory destruction of the body's exocrine glands and may be considered primary or secondary, in association with other autoimmune disorders, such as collagen vascular diseases. Although SS can present with a variety of symptoms, both glandular and extraglandular, initial presenting symptoms most commonly include decreased secretions of the major and minor salivary glands, leading to…