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Nuclear Imaging

Nuclear imaging is the radiologic examination using radiopharmaceuticals, which are radioactive substances taken up by specific types of cells. Nuclear medicine is more concerned with the functional and molecular aspects of the organ or pathology being investigated rather than the structure. Radiopharmaceuticals are administered to the patient and in vivo distribution is recorded. Nuclear imaging has been widely used to diagnose and follow up certain diseases. Multiple organ systems can be evaluated, including the cardiovascular system, where ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage is detected; endocrine system, where thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy activity is evaluated; hepatobiliary system, where cystic duct Cystic duct The duct that is connected to the gallbladder and allows the emptying of bile into the common bile duct. Cholecystitis obstruction can be seen; and skeletal system where tumors/ metastasis Metastasis The transfer of a neoplasm from one organ or part of the body to another remote from the primary site. Grading, Staging, and Metastasis or fractures are localized.

Last updated: 6 May, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Terminology and Technological Aspects

Mechanism

  • Nuclear medicine differs from the rest of radiology because it involves functional rather than structural imaging.
  • Radioisotopes: unstable forms of an element that emit detectable particles as they decay into more stable forms
  • Radiopharmaceuticals:
    • Artificially produced isotopes bound to pharmaceuticals (radioisotope + an organic molecule) 
    • Administered to patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship and used in nuclear medicine
    • The organic molecule allows isotopes to concentrate within a specific target organ.
    • The radioisotope emits detectable ionizing radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma (high-energy rays) when it decays, which is visualized during imaging.

Image creation

Equipment:

  • The machine is equipped with a gamma camera that detects radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma and forms an image.
  • Components of the gamma camera:
    • Collimator: 1st layer between the patient and the crystal. The collimator is made of lead with holes to reduce scatter.
    • Crystal: emits faint light after interacting with gamma rays
    • Photomultiplier tubes: detect and convert light from the crystal into electrical signals
    • Electronics for processing data: analyze signals and produce viewable images 

Imaging techniques:

  • Single-photon emission computed tomography (SPECT):
    • Uses gamma-emitting radioisotopes
    • A 3D nuclear imaging made by multiple 2D images acquired at different angles
  • PET:
    • Uses positron-emitting radioisotopes
    • Superior image quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement (contrast and resolution) but more expensive
  • Combined imaging techniques:
    • CT (PET-CT or SPECT-CT) or MRI is integrated.
    • Improved localization of lesions
Spect ct system

A SPECT/CT system with relevant components labeled in the photograph on the right

Image: “NM19 290” by Kieran Maher. License: Public Domain

Common nuclear medicine exams

Hepatobiliary Iminodiacetic Acid Scan

  • HIDA scan (cholescintigraphy):
    • Examination of the gallbladder Gallbladder The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Gallbladder and Biliary Tract: Anatomy
    • The radiopharmaceutical is normally taken up by the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy and excreted through the biliary system as bile Bile An emulsifying agent produced in the liver and secreted into the duodenum. Its composition includes bile acids and salts; cholesterol; and electrolytes. It aids digestion of fats in the duodenum. Gallbladder and Biliary Tract: Anatomy.
    • Radiopharmaceutical: technetium-99m iminodiacetic acid
    • Isotope: technetium-99m
  • Indications: 
    • Acute cholecystitis Cholecystitis Cholecystitis is the inflammation of the gallbladder (GB) usually caused by the obstruction of the cystic duct (acute cholecystitis). Mechanical irritation by gallstones can also produce chronic GB inflammation. Cholecystitis is one of the most common complications of cholelithiasis but inflammation without gallstones can occur in a minority of patients. Cholecystitis with equivocal ultrasound findings
    • Biliary atresia Atresia Hypoplastic Left Heart Syndrome (HLHS)
    • Biliary leak
    • Biliary dyskinesia Biliary dyskinesia A motility disorder characterized by biliary colic, absence of gallstones, and an abnormal gallbladder ejection fraction. It is caused by gallbladder dyskinesia and/or sphincter of oddi dysfunction. Cholecystectomy: Cholecystokinin Cholecystokinin A peptide, of about 33 amino acids, secreted by the upper intestinal mucosa and also found in the central nervous system. It causes gallbladder contraction, release of pancreatic exocrine (or digestive) enzymes, and affects other gastrointestinal functions. Cholecystokinin may be the mediator of satiety. Gastrointestinal Secretions is administered and gallbladder Gallbladder The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Gallbladder and Biliary Tract: Anatomy ejection fraction Ejection fraction Cardiac Cycle is calculated.
  • Contraindication: allergy Allergy An abnormal adaptive immune response that may or may not involve antigen-specific IgE Type I Hypersensitivity Reaction to the radiotracer ( anaphylaxis Anaphylaxis An acute hypersensitivity reaction due to exposure to a previously encountered antigen. The reaction may include rapidly progressing urticaria, respiratory distress, vascular collapse, systemic shock, and death. Type I Hypersensitivity Reaction
Table: Interpretation of HIDA scans
Imaging finding Interpretation
Bile Bile An emulsifying agent produced in the liver and secreted into the duodenum. Its composition includes bile acids and salts; cholesterol; and electrolytes. It aids digestion of fats in the duodenum. Gallbladder and Biliary Tract: Anatomy ducts visible Normal hepatic function
Filling of the gallbladder Gallbladder The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Gallbladder and Biliary Tract: Anatomy Patent cystic duct Cystic duct The duct that is connected to the gallbladder and allows the emptying of bile into the common bile duct. Cholecystitis
Radiotracer is seen in the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy Patent common bile duct common bile duct The largest bile duct. It is formed by the junction of the cystic duct and the common hepatic duct. Gallbladder and Biliary Tract: Anatomy
No radiotracer is seen in the gallbladder Gallbladder The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Gallbladder and Biliary Tract: Anatomy Obstructed gallbladder Gallbladder The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Gallbladder and Biliary Tract: Anatomy (acute cholecystitis Cholecystitis Cholecystitis is the inflammation of the gallbladder (GB) usually caused by the obstruction of the cystic duct (acute cholecystitis). Mechanical irritation by gallstones can also produce chronic GB inflammation. Cholecystitis is one of the most common complications of cholelithiasis but inflammation without gallstones can occur in a minority of patients. Cholecystitis)
No radiotracer is seen in the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy Biliary atresia Atresia Hypoplastic Left Heart Syndrome (HLHS)
Radiotracer outside the biliary system Biliary leak

Ventilation and Perfusion Scan

  • Phases:
    • Ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing phase:
      • The patient breathes in the radiopharmaceutical, typically Xenon-133, in the form of an aerosol (other option: technetium-99m diethylenetriaminepentaacetate (DTPA)).
      • Small particles then are deposited into the alveoli Alveoli Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place. Acute Respiratory Distress Syndrome (ARDS) and images are acquired.
    • Perfusion phase:
      • An injectable radiopharmaceutical (technetium-99m macroaggregated albumin Albumin Serum albumin from humans. It is an essential carrier of both endogenous substances, such as fatty acids and bilirubin, and of xenobiotics in the blood. Liver Function Tests (MAA)) is administered. 
      • Technetium-99m MAA enters the pulmonary vessels and images are acquired.
  • Indications: 
    • For evaluation of pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism when CT pulmonary angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery is contraindicated:
      • IV contrast allergy Allergy An abnormal adaptive immune response that may or may not involve antigen-specific IgE Type I Hypersensitivity Reaction
      • Pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care 
      • Renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome
    • Preoperative estimates of lung function: preparation for surgical excision
  • Contraindication: allergy Allergy An abnormal adaptive immune response that may or may not involve antigen-specific IgE Type I Hypersensitivity Reaction to radiotracers ( anaphylaxis Anaphylaxis An acute hypersensitivity reaction due to exposure to a previously encountered antigen. The reaction may include rapidly progressing urticaria, respiratory distress, vascular collapse, systemic shock, and death. Type I Hypersensitivity Reaction) 
  • Normal VQ scan findings:
    • Normal perfusion: uniform uptake in the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy with areas of photopenia in the region of the heart and hila 
    • Normal ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing: radiotracer homogeneously washing into the lung with quick washout and no evidence of air trapping
    • Always obtain a chest radiograph prior to a VQ scan to exclude consolidation Consolidation Pulmonary Function Tests, which gives a false-positive result.
Table: VQ scan interpretation based on Prospective Investigation of Pulmonary Embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism Diagnosis (PIOPED) revised criteria
Category Findings
High probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability of pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism More than 2 large mismatched segmental defects
Intermediate probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability of pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism
  1. 2 large, mismatched segmental defects (borderline high probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability)
  2. 1 moderate to 2 large, segmental defects or any other pattern difficult to characterize as high or low probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability (true intermediate probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability)
  3. Single matched defect with a normal chest radiograph (borderline low probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability)
Low probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability for pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism
  1. Non-segmental perfusion defects
  2. Any perfusion defect with a substantially larger radiographic finding
  3. Matched ventilation Ventilation The total volume of gas inspired or expired per unit of time, usually measured in liters per minute. Ventilation: Mechanics of Breathing/perfusion defect with a normal chest radiograph
  4. Any amount of small perfusion defects with a normal chest radiograph
Normal No matched or mismatched defects

Bone Scan

  • The skeletal system can be assessed using nuclear medicine.
    • The radiopharmaceutical that is used chemoadsorbs to the hydroxyapatite crystals Hydroxyapatite crystals A group of compounds with the general formula m10(PO4)6(OH)2, where m is barium, strontium, or calcium. The compounds are the principal mineral in phosphorite deposits, biological tissue, human bones, and teeth. They are also used as an anticaking agent and polymer catalysts. Calcium Hemostasis and Bone Metabolism in the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types matrix; thus, areas of bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types turnover can be identified.
    • Increased bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types turnover is seen in fractures, tumors, and acute infection.
    • Isotope: technetium-99m
    • Radiopharmaceutical: methylene diphosphonate
  • Imaging:
    • Images are obtained 4 hours after injection, allowing the radiotracer to be taken up by the bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types.
    • Anterior and posterior images are obtained.
  • Indications: 
    • Bony metastases screening Screening Preoperative Care
    • Evaluation of fractures (e.g., stress fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures) that are not visible on a radiograph
    • Infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease
Table: Interpretation of bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types scan
Results Description Accuracy Examples
Normal
  • Symmetric uptake
  • Urinary bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess and skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy are normally bright
True negative False negative False negative An FN test result indicates a person does not have the disease when, in fact, they do. Epidemiological Values of Diagnostic Tests
Normal skeleton Purely lytic metastasis Metastasis The transfer of a neoplasm from one organ or part of the body to another remote from the primary site. Grading, Staging, and Metastasis
Abnormal Asymmetric increased uptake True positive False positive False positive An FP test result indicates that a person has the disease when they do not. Epidemiological Values of Diagnostic Tests
  • Degenerative changes Degenerative Changes Spinal Stenosis
  • Osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis

Cardiac Scan

  • Also known as myocardial perfusion imaging
  • Detects variation in blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure and myocardial extraction of radiotracers 
  • Materials: 
    • Isotopes: 
      • Technetium-99m
      • Thallium-201 
    • Radiopharmaceuticals:
      • Sestamibi 
      • Teboroxime
  • Procedure:
    • In normal coronary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology, significant arterial dilatation is seen in response to exercise/stress.
    • Stenotic areas do not show dilatation; thus, ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage and ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) changes occur. 
    • In a cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) scan, stress is either:
      • Induced by exercise by running on a treadmill
      • Pharmacologically induced by giving adenosine Adenosine A nucleoside that is composed of adenine and d-ribose. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Class 5 Antiarrhythmic Drugs or dobutamine Dobutamine A catecholamine derivative with specificity for beta-1 adrenergic receptors. Sympathomimetic Drugs to those who cannot run 
  • Imaging is obtained at both stress and rest.
  • Radiopharmaceuticals are injected when 85% of the maximum predicted heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology (MPHR) is reached.
  • Indications:
    • Myocardial ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage or infarction evaluation
    • Wall-motion abnormalities: performed using ECG-gated SPECT scan
    • Calculate left ventricular ejection Ventricular ejection Cardiac Cycle fraction
  • Normal cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) scan obtained in 3 different planes:
    • The top row of each set is performed under cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) stress.
    • Bottom row of each set is performed at rest.
    • Normal flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure to all aspects of the heart at both rest and stress
  • Abnormal cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) scans:
    • Myocardial ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage: areas of photopenia (i.e., decreased uptake) under stress, which improve at rest
    • Myocardial infarction Myocardial infarction MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction: persistent photopenia (i.e., decreased uptake) despite rest state

Thyroid Scan

  • The thyroid gland Thyroid gland The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy transports iodine Iodine A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126. 90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically. Thyroid Hormones; thus, radioiodine is used to detect the function of the whole gland or nodules.
  • Radiopharmaceuticals:
    • Radioactive iodine Iodine A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126. 90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically. Thyroid Hormones (iodine-123)
    • Technetium-99 pertechnetate
  • Indications: 
    • Thyroid nodules Thyroid nodules A thyroid nodule is a disordered growth of thyroid cells that produces a mass in the thyroid gland. Most thyroid nodules are benign and detected either by the patient or by the clinician on examination. In other cases, a thyroid nodule is found in radiologic imaging incidentally. Ruling out of malignancy is important. Thyroid Nodules
    • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with thyrotoxicosis Thyrotoxicosis A hypermetabolic syndrome caused by excess thyroid hormones which may come from endogenous or exogenous sources. The endogenous source of hormone may be thyroid hyperplasia; thyroid neoplasms; or hormone-producing extrathyroidal tissue. Thyrotoxicosis is characterized by nervousness; tachycardia; fatigue; weight loss; heat intolerance; and excessive sweating. Thyrotoxicosis and Hyperthyroidism
    • Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with thyroid cancer Thyroid cancer Thyroid cancer is a malignancy arising from the thyroid gland cells: thyroid follicular cells (papillary, follicular, and anaplastic carcinomas) and calcitonin-producing C cells (medullary carcinomas). Rare cancers are derived from the lymphocytes (lymphoma) and/or stromal and vascular elements (sarcoma). Thyroid Cancer:
    • Therapeutic use: radioactive thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy ablation (in Graves’ disease Graves’ disease A common form of hyperthyroidism with a diffuse hyperplastic goiter. It is an autoimmune disorder that produces antibodies against the thyroid stimulating hormone receptor. These autoantibodies activate the TSH receptor, thereby stimulating the thyroid gland and hypersecretion of thyroid hormones. These autoantibodies can also affect the eyes (Graves ophthalmopathy) and the skin (Graves dermopathy). Thyrotoxicosis and Hyperthyroidism or thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy carcinoma) using higher doses of radioactive iodine Iodine A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126. 90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically. Thyroid Hormones (iodine-131 destroys thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy cells)
  • Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation:
    • Pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care 
    • Lactation Lactation The processes of milk secretion by the maternal mammary glands after parturition. The proliferation of the mammary glandular tissue, milk synthesis, and milk expulsion or let down are regulated by the interactions of several hormones including estradiol; progesterone; prolactin; and oxytocin. Breastfeeding
Table: Interpretation of thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy scan
Uptake Pattern Diagnosis
Increased Nodular (hot nodule Nodule Chalazion) Toxic adenoma Toxic Adenoma Thyrotoxicosis and Hyperthyroidism
Diffuse Graves’ disease Graves’ disease A common form of hyperthyroidism with a diffuse hyperplastic goiter. It is an autoimmune disorder that produces antibodies against the thyroid stimulating hormone receptor. These autoantibodies activate the TSH receptor, thereby stimulating the thyroid gland and hypersecretion of thyroid hormones. These autoantibodies can also affect the eyes (Graves ophthalmopathy) and the skin (Graves dermopathy). Thyrotoxicosis and Hyperthyroidism
Normal Symmetric uptake with no defects
Decreased Nodular (cold nodule Nodule Chalazion) Thyroid cancer Thyroid cancer Thyroid cancer is a malignancy arising from the thyroid gland cells: thyroid follicular cells (papillary, follicular, and anaplastic carcinomas) and calcitonin-producing C cells (medullary carcinomas). Rare cancers are derived from the lymphocytes (lymphoma) and/or stromal and vascular elements (sarcoma). Thyroid Cancer
Diffuse Hashimoto thyroiditis Thyroiditis Thyroiditis is a catchall term used to describe a variety of conditions that have inflammation of the thyroid gland in common. It includes pathologies that cause an acute illness with severe thyroid pain (e.g., subacute thyroiditis and infectious thyroiditis) as well as conditions in which there is no clinically evident inflammation and the manifestations primarily reflect thyroid dysfunction or a goiter (e.g., painless thyroiditis and fibrous Riedel’s thyroiditis). Thyroiditis

Other Imaging Modalities by System

  • Imaging of the CNS ( brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification, spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy, and vertebral column Vertebral column The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy): 
    • Radiography is often used to evaluate fractures of the vertebral column Vertebral column The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy
    • CT is a good choice to determine head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma and exclude intracranial hemorrhage Intracranial hemorrhage Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most sahs originate from a saccular aneurysm in the circle of willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage
    • MRI provides more detailed images of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification and spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy, allowing identification Identification Defense Mechanisms of infarction, tumors, disc herniation Herniation Omphalocele, and demyelinating disease.
  • Pulmonary radiology Pulmonary Radiology Pulmonary, or chest, imaging includes imaging of the lungs and surrounding structures in the thorax. Imaging of the chest represents a substantial portion of the imaging tests that are routinely performed. Common imaging methods include X-ray, CT, MRI, and ultrasonography (US). Imaging of the Lungs and Pleura and imaging of the mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy
    • Radiography is the preferred initial imaging study for viewing lung pathology. 
    • CT provides more detailed views of the lung parenchyma, mediastinal structures, and vasculature. 
    • MRI is not often used, but may be employed for evaluating malignancies and cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) disease. 
    • Ultrasound can be used for rapid bedside-trauma assessment and for guiding procedures ( thoracentesis Thoracentesis Aspiration of fluid or air from the thoracic cavity. It is coupled sometimes with the administration of drugs into the pleural cavity. Thoracic Surgery).
  • Breast imaging Breast Imaging Female breasts, made of glandular, adipose, and connective tissue, are hormone-sensitive organs that undergo changes along with the menstrual cycle and during pregnancy. Breasts may be affected by various diseases, in which different imaging methods are important to arrive at the correct diagnosis and management. Mammography is used for breast cancer screening and diagnostic evaluation of various breast-related symptoms. Imaging of the Breast
    • Mammography Mammography Radiographic examination of the breast. Breast Cancer Screening is often the initial choice for breast cancer screening Breast cancer screening Breast cancer is the most common cancer in women and the 2nd-leading cause of cancer-related deaths in women in the United States. Early detection and improved pathology-specific treatments have resulted in a decrease in death rates. Breast Cancer Screening
    • MRI can be used to further evaluate and stage breast cancers. 
    • Ultrasound is helpful in the evaluation of lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs nodes and in guiding biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma.
  • Imaging of the abdomen and renal imaging Renal imaging The renal system is composed of 2 kidneys, 2 ureters, a bladder, and a urethra. Varying conditions such as infections, cysts, solid masses, ischemia, and mechanical obstruction can affect the renal system. Evaluation of diseases rely on imaging methods such as radiography, ultrasonography, CT, and MRI. Some of these are also used to guide tissue sampling (e.g., renal biopsy). Imaging of the Urinary System
    • Radiography is often used to evaluate for kidney stones Kidney stones Nephrolithiasis is the formation of a stone, or calculus, anywhere along the urinary tract caused by precipitations of solutes in the urine. The most common type of kidney stone is the calcium oxalate stone, but other types include calcium phosphate, struvite (ammonium magnesium phosphate), uric acid, and cystine stones. Nephrolithiasis, bowel obstruction Bowel obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Ascaris/Ascariasis, and pneumoperitoneum Pneumoperitoneum A condition with trapped gas or air in the peritoneal cavity, usually secondary to perforation of the internal organs such as the lung and the gastrointestinal tract, or to recent surgery. Pneumoperitoneum may be purposely introduced to aid radiological examination. Perforated Viscus. In addition, barium may be used to assess swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility and bowel function. 
    • CT and MRI provide more detailed assessments of the abdominal viscera and vasculature. 
    • Nuclear medicine can be used to assess gallbladder Gallbladder The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Gallbladder and Biliary Tract: Anatomy function, gastric emptying Gastric emptying The evacuation of food from the stomach into the duodenum. Gastrointestinal Motility, and GI bleeding.
  • Imaging of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy and ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries: Anatomy
    • Ultrasound is the most commonly used modality to evaluate the ovary and uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy, including assessing pregnancies and determining the cause of abnormal uterine bleeding Abnormal Uterine Bleeding Abnormal uterine bleeding is the medical term for abnormalities in the frequency, volume, duration, and regularity of the menstrual cycle. Abnormal uterine bleeding is classified using the acronym PALM-COEIN, with PALM representing the structural causes and COEIN indicating the non-structural causes. Abnormal Uterine Bleeding
    • CT and MRI provide more detailed views and are often useful in assessing cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change, malignancies, and benign Benign Fibroadenoma masses.
  • Imaging of the musculoskeletal system: 
    • Radiography is often used to exclude fractures. 
    • CT is more sensitive to bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types pathology, including osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis
    • MRI is preferred for soft-tissue evaluation, such as assessing for malignancy Malignancy Hemothorax and myositis. 
    • Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types scan can be useful in determining occult fractures, osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis, and metabolic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types disease.

References

  1. Brandon, D.C., Thomas, A.J., Ravizzini, G.C. (2014). Introduction to nuclear medicine. https://accessmedicine.mhmedical.com/content.aspx?bookid=1562&sectionid=95875470
  2. Elsayes, K.M., Oldham, S.A. (Eds.) (2014). Introduction to Diagnostic Radiology. McGraw-Hill. 
  3. Chen, M.M., Whitlow, C.T. (2011). Chapter 1. Scope of Diagnostic Imaging. In Chen M.M., Pope T.L., Ott D.J.(Eds.). Basic Radiology, 2e. McGraw-Hill.

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