Nuclear Medicine Central Nervous System and Systemic Imaging Lecture Review

Flashcards covering the anatomy, physiology, radiopharmaceuticals, and diagnostic procedures for major body systems as detailed in the Central Nervous System and Systemic Imaging lecture transcript.

Medulla oblongata

A passageway for nerve fiber tracts between the spinal cord and higher brain regions that contains reflex centers and cranial nerves.

Choroid plexus

A mass of blood vessels in the lateral ventricles that helps produce CSF.

Blood-brain barrier (BBB)

A physiological barrier that determines whether a tracer can cross into brain tissue; diffusible tracers are lipophilic and can cross, while nondiffusible tracers are hydrophilic and generally cannot.

99mTc-Ethyl Cysteinate Dimer (ECD/Neurolite)

A neutral lipophilic complex used for brain perfusion imaging that crosses the BBB and is converted to an anionic complex that becomes trapped.

123I-Ioflupane (DaTscan)

A radiopharmaceutical used to evaluate dopamine transporter activity in Parkinson syndromes, helping differentiate essential tremor from idiopathic Parkinson syndromes.

18F-Fluorodeoxyglucose (18F-FDG)

A glucose analog used for brain metabolic imaging that is phosphorylated to FDG-6-phosphate and trapped in cells; useful for epilepsy, tumors, and dementia.

Amyloid PET agents

Agents such as $^{18}F$-florbetapir ($Amyvid$), $^{18}F$-flutemetamol ($Vizamyl$), and $^{18}F$-florbetaben ($Neuraceq$) used to detect amyloid plaques in Alzheimer disease.

Acetazolamide (Diamox) challenge

A brain interventional study used to assess cerebrovascular reserve capacity by causing cerebrovascular vasodilation of about $20\%$ to $40\%$, increasing blood flow.

Cisternography

A procedure used to evaluate the formation, flow, and resorption of CSF, commonly using $^{111}In$-DTPA injected by lumbar puncture.

Organification

The step in thyroid hormone synthesis involving the formation of monoiodotyrosine (MIT) and diiodotyrosine (DIT) by the iodination of tyrosine.

99mTc-Sodium Pertechnetate (Thyroid)

A radiopharmaceutical trapped by the thyroid like iodide but not organified, used to evaluate thyroid structure and trapping.

99mTc-Macroaggregated Albumin (MAA)

A radiopharmaceutical used for lung perfusion imaging that traps particles sized $10$ to $90$ micrometers in the pulmonary capillary bed.

133Xe Gas

An inhaled gas used for ventilation imaging involving a closed system with initial breath-hold, equilibrium, and washout phases.

V/Q Mismatch

A diagnostic pattern for pulmonary embolism characterized by normal ventilation (V) with decreased perfusion (Q).

Hepatocytes

Liver cells that perform metabolic functions and excrete bile; evaluated using $^{99m}Tc$-labeled IDA derivatives.

Kupffer cells

Phagocytic cells in the liver that remove foreign particles from circulation, imaged using $^{99m}Tc$-Sulfur Colloid.

Acute Cholecystitis Pattern

Non-visualization of the gallbladder up to $4$ hours after tracer injection in cholescintigraphy, indicating cystic duct obstruction.

Sincalide (CCK)

A pharmaceutical used to stimulate gallbladder contraction to calculate the gallbladder ejection fraction; a value less than $35\%$ suggests abnormal function.

99mTc-Labeled Heat-Damaged RBCs

A specific agent used to localize functioning splenic tissue, especially useful for identifying accessory spleens.

Nephron

The functional unit of the kidney, composed of the glomerulus and the renal tubule.

99mTc-MAG3

A renal agent primarily secreted by tubules; used for measuring Effective Renal Plasma Flow (ERPF) and evaluating tubular function.

99mTc-DTPA (Renal)

A renal agent filtered by the glomeruli with minimal tubular secretion, used to measure Glomerular Filtration Rate (GFR).

Captopril Renography

A study used to evaluate renovascular hypertension by blocking the conversion of angiotensin I to angiotensin II, causing a drop in GFR in kidneys with renal artery stenosis.

99mTc-Phosphonate Compounds (MDP/HDP)

Radiopharmaceuticals that bind to hydroxyapatite in bone; uptake depends on blood flow and osteoblastic activity.

Three-phase bone scan

A diagnostic study including flow, blood pool, and delayed phases used to distinguish cellulitis from osteomyelitis.

Hibernating myocardium

Dysfunctional myocardial tissue due to chronic ischemia that remains viable; identified by poor perfusion but preserved energy metabolism on $^{18}F$-FDG imaging.

201Tl-Thallous Chloride

A potassium analog used for myocardial perfusion that redistributes over time, allowing for the differentiation of ischemia from infarction.

99mTc-Pyrophosphate (PYP)

A radiopharmaceutical used for imaging acute myocardial infarction, typically showing increased uptake $24$ to $72$ hours after the event.

Standardized Uptake Value (SUV)

A semiquantitative measure in PET imaging that compares tumor activity concentration to the injected dose normalized to body size.

67Ga-Citrate

A radiopharmaceutical that binds to transferrin and localizes in inflammation, infection, and certain tumors like lymphoma and Hodgkin disease.

123I- or 131I-MIBG

A tracer that resembles norepinephrine and is used to image neuroendocrine tumors such as pheochromocytoma and neuroblastoma.

Sentinel node biopsy

The identification and removal of the first lymph node(s) receiving drainage from a tumor site using a radiotracer and/or blue dye.

Meckel's Diverticulum Imaging

The use of $^{99m}Tc$-pertechnetate to detect ectopic gastric mucosa, which appears as persistent focal activity in the abdomen.

White Blood Cell (WBC) Imaging

The use of $^{111}In$- or $^{99m}Tc$-labeled leukocytes to locate sites of infection or inflammation via chemotaxis.

Dual-isotope subtraction technique

A parathyroid imaging method where a thyroid-only image is subtracted from a combined thyroid/parathyroid image to isolate the parathyroid glands.