Disease Definitions

Coronary Artery Disease

Build-up of plaque narrows coronary arteries causing reduced blood flow to the heart. NM: Reversible perfusion defects on stress MPI that improve at rest suggest ischemia.

Myocardial Ischemia

Reduced blood flow to the myocardium without permanent damage. NM: Reversible perfusion defects on stress images.

Myocardial Infarction

Death of heart muscle from prolonged ischemia. NM: Fixed perfusion defect present on both stress and rest images.

Congestive Heart Failure

Inability of the heart to pump blood effectively. NM: Reduced ejection fraction on MUGA scan (<50%) and ventricular dilation.

Cardiomyopathy

Disease of the heart muscle causing impaired function. NM: Reduced EF and abnormal wall motion on MUGA or perfusion abnormalities on MPI.

Cardiac Amyloidosis

Abnormal amyloid protein deposits within the myocardium. NM: Diffuse myocardial uptake on Tc-99m PYP scan greater than rib uptake is highly suggestive.

Angina

Chest pain caused by transient myocardial ischemia. NM: Reversible perfusion defects on stress imaging without infarction.

Left Bundle Branch Block

Delayed electrical conduction through the left ventricle. NM: Septal perfusion defects may occur despite normal coronary arteries; pharmacologic stress preferred.

AV Block (1st-3rd Degree)

Abnormal electrical conduction between atria and ventricles. NM: MUGA may demonstrate abnormal ventricular timing and reduced EF in severe disease.

Mitral Valve Regurgitation

Leakage of blood backward through the mitral valve. NM: Increased ventricular volumes and decreased EF on MUGA.

Pericarditis

Inflammation of the pericardial sac surrounding the heart. NM: Occasionally demonstrates diffuse inflammatory uptake on FDG PET.

Hyperlipidemia

Elevated blood lipids increasing risk of CAD. NM: No specific findings but may contribute to perfusion abnormalities from CAD.

Cardiac Hypertension

Chronic hypertension causing cardiac remodeling. NM: Left ventricular hypertrophy with possible perfusion defects and decreased EF.

Alzheimer's Disease

Progressive neurodegenerative disease causing dementia. NM: Bilateral temporoparietal hypometabolism on FDG PET.

Parkinson's Disease

Degeneration of dopamine-producing neurons causing movement abnormalities. NM: Reduced striatal uptake on DaTscan.

Lewy Body Dementia

Dementia associated with Lewy body protein deposits. NM: Reduced occipital metabolism on FDG PET and abnormal DaTscan.

Pick's Disease

Frontotemporal dementia affecting personality and behavior. NM: Frontal and temporal hypometabolism on FDG PET.

Epilepsy

Neurologic disorder causing recurrent seizures. NM: Interictal hypometabolism or ictal hyperperfusion localized to seizure focus.

Normal Pressure Hydrocephalus

Abnormal CSF accumulation causing gait disturbances and dementia. NM: Delayed tracer clearance and ventricular reflux on cisternography.

Obstructive Hydrocephalus

Blockage of CSF flow causing ventricular enlargement. NM: Delayed or absent CSF flow beyond obstruction.

Meningioma

Usually benign tumor arising from meninges. NM: Increased somatostatin receptor uptake on PET imaging.

Stroke

Sudden interruption of cerebral blood flow. NM: Focal perfusion defects or decreased FDG uptake in affected regions.

Transient Ischemic Attack

Temporary reduction in cerebral blood flow without permanent injury. NM: May demonstrate transient perfusion abnormalities.

Essential Tremor

Common movement disorder causing hand tremors. NM: Normal DaTscan distinguishes it from Parkinson's disease.

CSF Leak

Leakage of cerebrospinal fluid from dura. NM: Extravasation of tracer into nasal cavity or ears on cisternography.

COPD

Chronic airflow obstruction usually from smoking. NM: Matched ventilation-perfusion abnormalities on lung scans.

Chronic Bronchitis

Chronic inflammation causing mucus production and airflow limitation. NM: Delayed washout and matched V/Q defects.

Emphysema

Destruction of alveoli causing air trapping. NM: Delayed xenon washout and ventilation defects.

Pulmonary Embolism

Blockage of pulmonary arteries by blood clots. NM: Segmental perfusion defects with normal ventilation (mismatched defects).

Pulmonary Hypertension

Elevated pulmonary artery pressure straining the right heart. NM: Enlarged right ventricle and abnormal perfusion patterns.

Pneumonia

Infection of lung tissue. NM: Matched ventilation and perfusion abnormalities.

Hepatopulmonary Syndrome

Liver disease causing abnormal pulmonary vascular dilation. NM: Brain and kidney uptake on Tc-99m MAA scan indicates shunting.

Acute Tubular Necrosis

Acute kidney injury from tubular cell damage. NM: Delayed excretion with preserved perfusion on renal scan.

Pyelonephritis

Bacterial kidney infection. NM: Cortical defects on DMSA scan.

Horseshoe Kidney

Congenital fusion of both kidneys. NM: Fusion across the midline with lower pole connection.

Obstructive Hydronephrosis

Dilation of renal collecting system due to obstruction. NM: Delayed drainage despite Lasix administration.

Vesicoureteral Reflux

Backward urine flow from bladder into kidneys. NM: Retrograde tracer movement during cystography.

Renal Artery Stenosis

Narrowing of renal arteries causing hypertension. NM: Delayed uptake or excretion on ACE-inhibitor renography.

Acute Cholecystitis

Inflammation of the gallbladder from cystic duct obstruction. NM: Nonvisualization of gallbladder after 60 minutes.

Chronic Cholecystitis

Long-standing gallbladder inflammation. NM: Delayed gallbladder visualization (>1 hour).

GI Bleed

Active gastrointestinal hemorrhage. NM: Progressive movement of labeled RBC activity within bowel.

Meckel's Diverticulum

Congenital diverticulum containing ectopic gastric mucosa. NM: Focal uptake appearing simultaneously with gastric activity.

GERD

Backflow of stomach contents into the esophagus. NM: Demonstrates reflux during gastric emptying studies.

Biliary Atresia

Congenital absence or obstruction of bile ducts. NM: No bowel visualization despite good liver uptake.

Cholelithiasis

Gallstones within the gallbladder. NM: Often normal HIDA scan unless obstruction occurs.

Cirrhosis

Chronic liver scarring causing hepatic dysfunction. NM: Increased splenic and bone marrow uptake with reduced liver uptake.

Liver Hemangioma

Benign vascular liver lesion. NM: Progressive blood pool filling on delayed Tc-99m RBC images.

Hepatitis

Inflammation of the liver. NM: Delayed hepatic uptake and excretion on hepatobiliary imaging.

Sjogren's Disease

Autoimmune destruction of salivary glands. NM: Reduced salivary uptake and poor stimulated excretion.

Xerostomia

Dry mouth due to reduced saliva production. NM: Decreased salivary gland function and excretion.

Sialolithiasis

Salivary gland stones causing obstruction. NM: Delayed or absent stimulated excretion from affected gland.

Warthin's Tumor

Benign salivary gland tumor usually in the parotid gland. NM: Increased Tc-99m pertechnetate uptake that persists after stimulation.

Graves' Disease

Autoimmune hyperthyroidism causing diffuse thyroid overactivity. NM: Diffusely increased iodine uptake throughout the thyroid gland.

Hyperthyroidism

Overproduction of thyroid hormones. NM: Increased thyroid uptake values.

Hypothyroidism

Underproduction of thyroid hormones. NM: Decreased or absent thyroid uptake.

Multinodular Goiter

Multiple autonomously functioning thyroid nodules. NM: Patchy uptake with hot and cold nodules.

Plummer's Disease

Single autonomously functioning thyroid adenoma. NM: Single hot nodule suppressing remaining thyroid tissue.

Parathyroid Adenoma

Benign parathyroid tumor causing hyperparathyroidism. NM: Persistent sestamibi uptake on delayed imaging.

Hyperparathyroidism

Excessive PTH production causing elevated calcium. NM: Persistent sestamibi uptake if adenoma present.

Hypoparathyroidism

Reduced PTH production causing low calcium levels. NM: No specific nuclear medicine findings.

Papillary Thyroid Carcinoma

Most common thyroid cancer. NM: Usually appears as a cold nodule on thyroid scan.

Follicular Thyroid Carcinoma

Thyroid cancer with hematogenous spread potential. NM: Often a cold thyroid nodule with possible iodine-avid metastases.

Medullary Thyroid Carcinoma

Calcitonin-producing thyroid cancer. NM: Variable uptake on FDG PET or somatostatin receptor imaging.

Anaplastic Thyroid Carcinoma

Aggressive undifferentiated thyroid cancer. NM: FDG-avid lesion with little or no iodine uptake.

Hurthle Cell Carcinoma

Variant of follicular thyroid cancer. NM: Poor radioiodine uptake and often FDG avid.

Multiple Endocrine Neoplasia Type I

Inherited syndrome causing endocrine tumors. NM: Uptake depends on affected endocrine organ.

Addison's Disease

Adrenal insufficiency from adrenal gland destruction. NM: Rarely evaluated with adrenal imaging.

Osteoporosis

Reduced bone mineral density increasing fracture risk. NM: Bone scan usually normal unless fractures are present.

Paget's Disease

Abnormal bone remodeling causing enlarged weakened bones. NM: Intense uptake involving entire affected bone.

Osteoarthritis

Degenerative joint disease. NM: Increased uptake localized to affected joints.

Osteomyelitis

Bone infection causing inflammation and destruction. NM: Increased uptake on all three phases of bone scan.

Osteogenic Sarcoma

Malignant bone-forming tumor. NM: Intense focal uptake at tumor site with possible metastases.

Avascular Necrosis

Bone death due to disrupted blood supply. NM: Photopenic defect early followed by increased uptake during healing.

Rheumatoid Arthritis

Autoimmune inflammatory arthritis. NM: Symmetric increased uptake involving affected joints.

Synovitis

Inflammation of synovial tissue. NM: Increased uptake in affected joints.

Complex Regional Pain Syndrome

Chronic pain syndrome usually affecting extremities. NM: Increased periarticular uptake on delayed bone images.

Polycythemia Vera

Myeloproliferative disorder causing excess red blood cells. NM: Expanded marrow distribution on sulfur colloid scans.

Myelofibrosis

Bone marrow fibrosis impairing blood cell production. NM: Reduced marrow uptake with extramedullary hematopoiesis in liver and spleen.

Extramedullary Hematopoiesis

Blood cell production occurring outside bone marrow. NM: Increased sulfur colloid uptake in liver and spleen.

Metastatic Breast Cancer

Breast cancer spread to distant sites. NM: Multiple foci of increased uptake on bone scan or FDG PET.

Metastatic Prostate Cancer

Prostate cancer spread to distant sites. NM: PSMA PET demonstrates intense uptake in metastatic lesions.

Erdheim-Chester Disease

Rare histiocytic disorder affecting multiple organs. NM: Symmetric long bone uptake on bone scan and hypermetabolic lesions on FDG PET.