CT MODULES 11 & 12

Abdominal Aortic Aneurysm (AAA)

A condition in which the walls of the aorta in the abdomen weaken and blood leaks into the layers of the vessel, causing it to bulge.

Thrombosis

formation of a blood clot that either partially or completely blocks a vessel. The blockage restricts or prevents blood flow.

Acquired hernias

usually develop later in life

Calcium Scoring

vital tool in detecting the presence of calcifications and their impact on circulation. Calcifications are a sign of atherosclerosis and coronary heart disease. The amount and density of the calcium is used as a predictor of risk for a cardiac event. A patient's calcium score is measured using the Agatston calcium scoring algorithm. An Agatston score of zero is normal and indicates that no calcifications were observed. Typically this means that the patient's risk of having a heart attack in the next two to five years is low. In general, the higher a patient's Agatston score, the more severe the atherosclerosis.

ischemia vs infarction

*Ischemia = Reduced blood flow to the tissue*, which can lead to pain • EXAMPLE: Myocardial Ischemia (MI) = heart attack - Inverted T-wave - Injury is indicated w/elevated ST segment - Infarction w/significant Q waves - Right axis deviation (RAD) - Occurs in left ventricle ???? only *Infarction = the end point of this ischemia that results in death of tissue *due to absent blood supply

Hodgkin and non-Hodgkin lymphoma

2 main types of lymphoma classifications based on the types of cells involved

Hodgkin

All _________ lymphomas involve Reed-Sternberg cells, but nonHodgkin lymphomas do not. Lymphomas can appear in any part of the body and although the type can only be identified by pathologic means, medical imaging such as CT can assist in determining the location and size of associated masses. CT also can play a prominent role in staging the extent of lymphoma spread and organ involvement

Sarcoma Origins

Although sarcomas can develop in any part of the body, 60% of sarcomas originate in the arms or legs, 30% in the abdomen or trunk and 10% in the head or neck. Osteosarcoma and Ewing sarcoma are the 2 most common sarcomas that originate in bone. These 2 types of sarcomas are more common in children, adolescents and teenagers than adults.

Appendicitis

An inflammation of the vermiform appendix, appendicitis is a serious disorder thought to be caused by blockages inside the organ, such as from fecal matter, foreign bodies or, rarely, intestinal worms. Because the appendix primarily is composed of lymphatic tissue, enlargement or infection of other lymph nodes also might contribute to appendicitis. If the inflammation leads to rupture, acute peritonitis can result, therefore surgical intervention before rupture occurs is preferred. Even when CT or ultrasound examinations are inconclusive or negative for appendicitis, surgery might be indicated because of the patient's clinical presentation

CT Numbers and Pathology

An understanding of CT numbers is critical to CT pathology because the grayscale shades produced by the CT numbers serve as a roadmap for pathological identification; when the lungs fill with fluid, when cerebral edema infiltrates the cranium or when blood pools and displaces normal tissue, the resulting CT numbers and visual representation of anatomy are different than what we would normally anticipate. As simple as this concept sounds, it is the basis of pathological identification in CT: Do the resulting CT numbers differ from what we would expect to see on a normal CT image of this anatomy? If they do, we should suspect pathology

Classifications of Aneurysms

Arterial walls are composed of 3 layers: the outermost adventitia, the middle media and the innermost intima. When an aneurysm forms it might affect only 1 layer of the arterial wall or all 3 layers. Aneurysms are classified as either true or false aneurysms. False aneurysms also are called pseudoaneurysms. In true aneurysms, marked A and B on the image, all 3 layers of the vessel wall are involved. These 2 types of true aneurysms are classified as saccular and fusiform.

Ovarian Cyst

CT generally is not used to evaluate the genitourinary system, primarily because of the ionizing radiation dose used in CT imaging. Pathology associated with these organs can be noted as incidental findings when imaging other organs

Coronary Artery Calcification

Calcium deposits in the arteries of the heart are a form of atherosclerosis. These deposits can cause narrowing or complete blockage of a vascular lumen. Narrowing can cause severe chest pain known as angina pectoris caused by reduced blood flow to the heart. Complete blockage causes a heart attack because blood flow is completely blocked to a specific portion of the heart.

Clinical Presentation of Appendicitis

Clinical symptoms of acute appendicitis can include periumbilical or right lower quadrant abdominal pain, nausea, vomiting and low-grade fever. Children usually have higher fevers than adults. If appendicitis is suspected in a patient, a white blood cell count often is ordered. A positive white blood cell count for a patient with appendicitis usually is between 14,000 to 16,000 mm3 indicating mild leukocytosis. A white blood cell count higher than 20,000 mm3 generally indicates a rupture of the appendix and peritonitis.

Renal Cysts

Cysts are fluid-filled enclosed sacs that can occur in any area of the body. Renal cysts are found in the renal parenchyma. These cysts can be described as either simple or complex in nature. Simple cysts normally are filled with fluid and appear round, oval or spherical. They also have smooth, thin walls. Simple cysts usually are asymptomatic and clinically insignificant. Complex cysts have areas that contain fluid, but also are more solid in composition. A solitary cyst can be present in cases of complex cysts, or numerous complex cysts can be present. The composition of each cyst can be obtained by performing a region of interest (ROI) measurement of its Hounsfield, or CT, numbers

Appendicitis

If appendicitis is suspected in a patient, a white blood cell count often is ordered. A positive white blood cell count for a patient with appendicitis usually is 14,000 to 16,000 mm3, indicating mild leukocytosis. A white blood cell count higher than 20,000 mm3 generally indicates a ruptured appendix and peritonitis

Symptoms of Sarcoma

Most patients who have sarcomas experience pain, swelling and tenderness at the site of the tumor. If the tumor is located near, or involves nerves, the pain can be severe. Initially, a patient might present with symptoms such as fever, malaise, anemia and weight loss. The tumor can weaken the bone significantly and pathologic fracture might be 1 of the first symptoms of the sarcoma.

Pancreatic Cancer

Pancreatic cancer is a malignancy of the pancreatic cells. There are 2 types of pancreatic cancer, exocrine and endocrine, with exocrine being the most common type. Pancreatic exocrine cancer originates in the ducts that transport pancreatic juices. Endocrine pancreatic cells manufacture certain types of hormones. Exocrine pancreatic cancer also is referred to as islet cell cancer. In 2010 there were an estimated 43,000 new cases of pancreatic cancer in the US. About 37,000 people died from the disease

Small Bowel Obstruction

Physical blockage of the small intestines; CT imaging of the abdomen and pelvis with both intravenous and oral contrast was recommended; marked ectasia, or dilation, of the small bowel loops, with multiple air-fluid levels

Stages of Hodgkin Lymphoma

Stage I is when there is only involvement of 1 region of lymph nodes, such as those in one of the axillary areas. Involvement of 2 lymph node regions on the same side of the diaphragm, such as both axillae, is classified as stage II. When lymph nodes above and below the diaphragm are involved, the disease is described as stage III. Stage IV, the most advanced stage, is defined as the presence of the disease in organs beyond the lymphatic system

Hounsfield Unit/CT Number

The mathematical unit that describes a shade of gray is called the Hounsfield unit (HU) or the CT number. This table shows the various CT numbers for different substances. Water is always assigned zero and serves as the basis from which other CT numbers are calculated. All other values represent various shades of gray. Structures that are dense are assigned the highest CT numbers. Bone, with a CT number near +1,000, appears white on a CT image. Air is associated with the lowest CT number at -1,000 and is displayed as black on the CT image.

phytobezoar

Undigested vegetable fiber collecting in the stomach is called ____________.

trichobezoars

a bezoar that consists of matted hair

appendicolith

calcified deposit within the appendix and is a common finding in approximately 30% of children who have acute appendicitis. When the presence of an appendicolith is combined with acute abdominal pain, the probability of acute appendicitis increases to 90%, and the chance of a ruptured appendix increases by 50%. Although the significance of an appendicolith is still up for debate, some in the medical community believe its presence is enough to warrant an appendectomy as a preventive measure.

Hydrocephalus

a buildup of fluid inside the cranium, hydrocephalus causes pressure to increase inside the head. This pressure increase is caused by enlargement of the ventricles of the brain because cerebrospinal fluid (CSF) cannot drain adequately. Overproduction of CSF also can cause hydrocephalus when more fluid is produced than can be adequately drained. Either of these conditions causes ventricular enlargement and pressure on the brain by forcing the brain against the cranial vault. Ultimately, this causes damage to the brain tissue. Most cases of hydrocephalus are congenital and caused by the presence of a myelomeningocele, other genetic defect or some types of infection during pregnancy. In adults, hydrocephalus can be caused by of a number of conditions, including closed head injury, ruptured aneurysm, stroke, brain tumor, meningitis or postcerebral surgery complication.

Bezoar

a collection of foreign material, such as hair, fiber, plastic or other indigestible matter inside the digestive tract. This material cannot pass through the intestine so it usually collects at the stomach outlet

Treatments for Ewing Sarcoma

a include chemotherapy to systemically destroy the malignant cells, surgery to remove as much of the tumor as possible and radiation therapy to eradicate residual disease in the tumor bed or to prevent the growth and spread of an unresected tumor. These options often are used in combination

Diverticula

a result of a weakness in the muscle layers of the digestive system that causes a "pocket." Although most common in the large intestine, diverticula can also appear in the esophagus, stomach and small intestine. Diverticulitis occurs when 1 or more diverticula become inflamed or infected; the condition is classified as uncomplicated or complicated. Uncomplicated diverticulitis symptoms are abdominal cramping, bloating, flatulence and irregular defecation. It can be controlled with a high fiber diet. Complicated diverticulitis symptoms are rectal bleeding and anemia. The infected diverticula can develop abscesses, or even perforate. These are serious complications requiring medical attention.

Hemangioma

abnormal collection of blood vessels. Hemangiomas usually involve the skin or internal organs. Although internal hemangiomas often appear similar to masses, they are histologically benign

Pleural Effusion

accumulation of fluid in the pleural cavity. It is caused by more fluid being produced than can be adequately absorbed by the body. The condition may be symptomatic or asymptomatic, depending on the amount of fluid buildup. When symptoms occur, they usually include cough, dyspnea, pain and pressure

Types of Adrenal Gland Masses

adenomas, cysts, lipomas, metastatic lesions from other cancers and pheochromocytomas. Adenomas can be either benign or malignant. Simple cysts, as ©2017 ASRT. All rights reserved. CT Basics Module 12 Pathology Part 2 well as lipomas, are usually benign. Metastatic lesions of the adrenal gland are malignancies that have spread from primary cancers in the body, most commonly the lungs. Pheochromocytomas are primary lesions of the adrenal glands and the only type associated with the adrenal medulla. About 90% of pheochromocytomas are benign. Lipomas are masses mostly composed of adipose tissue. Although lipomas might be found in the adipose tissue surrounding the adrenal glands, this is not a common finding.

Lymphoma

any cancerous neoplasm that originates in the body's lymphatic system. The lymphatic system is shown in this illustration. In lymphoma, the white blood cells behave abnormally by dividing faster or surviving longer than their normal counterparts. The abnormal cells are called Reed-Sternberg, or R-S, cells

Lymphadenopathy

any disease process affecting a lymph node or nodes; Whenever available, positron emission tomography combined with CT (PET-CT) is the procedure of choice for performing staging examinations, although staging is completed in many institutions using CT alone, or using PET-CT post procedural fusion. Post procedural fusion is an older fusion technique that was common before the advent of integrated PET/CT scanners in which the CT data and the PET data were acquired on independent scanners and fused by a radiologist or technologist at a later time. Staging involves a battery of medical tests to determine the spread of the cancer. This usually includes blood chemistry tests, complete blood count, CT of the chest, abdomen and pelvis, a PET scan, or a PET-CT scan. Staging provides information required to plan a treatment approach. Treatment varies according to the stage of the lymphoma

Colon Cancer

any malignancy that originates in the tissues of the colon and rectum. The National Institutes of Health describe most of these cancers as adenocarcinomas, meaning that their origins lie in the cells that manufacture and secrete mucus and other fluid. In 2010, the National Cancer Institute Surveillance Epidemiology and End Results report estimated 142,000 people living in the United States would receive a diagnosis of colon cancer. Of those, it was estimated that 51,000, or approximately 36%, would die of cancer of the colon and rectum. In addition, the report states that 1 in 20 people will be diagnosed with this type of cancer within their lifetimes.

Hepatic Hemangioma

benign. most common liver tumor.

Tricophytobezoars, or hairy footballs

bezoars containing both hair and food

Pulmonary Embolus

blockage of an artery in the lung. Most often the clot originates as a DVT that breaks off and travels to the lung. Unexplained shortness of breath, chest discomfort, a light-headed feeling, fainting, rapid pulse, sweating or coughing up blood are common symptoms

deep vein thrombosis

blood clot forms in a large vein, usually in a lower limb; Common symptoms of DVT include swelling, pain, cramping, unusual warmth or changing skin color of the affected lower leg, including the foot and ankle.

Toxoplasmosis Transmission

can be acquired by eating undercooked food or drinking infested water. The most common way that individuals contract this disease is to touch a contaminated object and then touch their mouth with unwashed hands. Symptoms in adults include swollen lymph glands, mild fevers, muscle aches, headaches, tiredness, confusion, and pain that last for a few days to several weeks. Toxoplasmosis is commonly present in people however few display symptoms because the immune system usually keeps the parasite from causing illness. Severe infections can result in brain damage and damage to the eyes, and may become chronic. Toxoplasma gondii also can be transmitted through exposure to the feces of an infected cat. In fact, some people refer to toxoplasmosis as "cat scratch fever." Like humans, cats rarely have symptoms when first infected, so most people don't know if their cat has been exposed to toxoplasma. Tests are not available to determine if a cat is infected. For this reason women are discouraged from changing litter boxes during pregnancy.

Bochdalek and diaphragmatic hernias

can be either acquired or congenital

Sinus Mass

can occur in any of the paranasal sinuses but most often occur in the frontal and maxillary areas. These masses can be benign or malignant. They also can be extensions of other neoplasms or metastases from other tumors. These masses can remain entirely contained within the affected sinus, or enlarge to displace or invade other structures. Symptoms often mimic those of sinusitis.

Toxoplasmosis

caused by Toxoplasma gondii, a single cell parasite. At any given time, millions of people worldwide are infected with toxoplasmosis, although the majority of those infected have no symptoms because their immune systems are healthy enough to prevent the parasite from causing illness. Toxoplasmosis can be passed from an infected mother to her child at birth, or be acquired later in life

Ischemic stroke

caused by a clot blocking a blood vessel and stopping blood flow to the brain

Cerebrovascular Accident

caused by the blockage or rupture of vessels transporting oxygenated blood to the brain tissue. If the brain tissue is without oxygen for a long period of time, the tissue necroses; Symptoms of stroke include sudden numbness or weakness on one side of the body, sudden confusion, difficulty seeing with 1 or both eyes, trouble walking, dizziness and the sudden onset of a severe headache.

Hemorrhagic stroke

caused by the rupture of a blood vessel, allowing blood to escape into the surrounding tissue

Subdural Hematoma

collection of blood under the dura mater

Cerebral Arteriovenous Malformation

defects in the body's circulatory system. Described as a tangle of arteries and veins, an AVM is thought to occur when organs form during development. About 300,000 Americans are estimated to have AVMs, but only an estimated 36,000 have symptoms. AVMs can occur anywhere in the body, but those located in the arteries and veins of the head are of particular concern. Cerebral AVMs will leak or rupture in approximately 2% to 4% of people who have them.

Hodgkin Lymphoma

disease marked by chronic enlargement of lymph nodes spreading to other nodes in an orderly way

Lung Carcinoma

malignant tumor arising from the lungs and bronchi

Sarcoma

masses or tumors that originate in bone, blood vessels, fat, fibrous tissue, muscles and other types of connective or supporting body tissues. Most sarcomas are malignant. Sarcoma comprises only about 1% of all adult cancers, but is responsible for 15% of all cancers in children

Aneurysm

n abnormal widening or ballooning of an artery or vein. Although aneurysms can occur in almost any artery or vein, arterial aneurysms are of the most concern because of arteries' high pressure. Although aneurysms can occur anywhere in the body, the most common locations include the abdominal aorta, cerebral arteries, thoracic aorta, mesenteric artery, splenic artery and popliteal artery of the lower extremity. Aneurysms can be caused by congenital factors or can form as the result of high blood pressure, atherosclerosis, smoking or an infection in the blood vessel. Aneurysms might be asymptomatic, enlarge enough to cause symptoms or spontaneously rupture. An aneurysm rupture can occur suddenly and in many cases can be fatal.

Pancreatitis

n inflammation of the pancreas that typically requires immediate medical attention and possible hospitalization. It has multiple causes and symptoms but commonly occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. Pancreatitis can be acute or chronic. Symptoms include severe upper abdominal pain that radiates to the back, nausea and vomiting that can be exacerbated with eating. A CT scan of the abdomen and pelvis was performed with both intravenous and oral contrast

Adrenal myelolipomas

rare benign tumors composed of adipose tissue, lymphocytes and hemopoietic cells. Unless the mass causes aberrant secretions of the affected adrenal gland or progressively increases in size, the mass usually is not surgically removed but rather is evaluated on a routine schedule using CT scans

Incisional Hernia

occur after surgery and are found adjacent to or along surgical suture lines. Tension on the suture line is thought to contribute significantly to the formation of these hernias. An incisional hernia can develop immediately after surgery or later, but most occur within the first 2 years following surgery. Most incisional hernias are repaired surgically.

Hernia

occur when the contents of a body cavity protrude through the tissues holding them in place, generally a muscular sac or wall. Although hernias can occur in many areas of the body, most involve portions of the intestine or abdominal fat. Hernias can be congenital or the result of traumatic forces. They can be asymptomatic or cause mild to severe pain.

Aneurysm Dissection

occurs when a hemorrhage causes a split along the length of the inner layer of the vessel wall called the intima. This causes a channel to form between the intima and the outer layers. Dissections are classified according to where they are located. Stanford type A dissections occur in the ascending portion of the aorta, and type B dissections occur in the descending portion. Although aneurysms can occur in any vessel within the body, dissecting aneurysms occur most frequently in the thoracic aorta. Many aortic dissections are fatal.

Gallstones (cholelithiasis)

pigmented or hardened cholesterol stones formed as a result of bile crystallization

congenital hernias

present at birth and are caused by embryonic developmental defects

Adrenal Glands

produce hormones that help regulate blood pressure, heart rate, the metabolism of food and other vital functions. The adrenal cortex secretes steroid hormones and mineralocorticoids that regulate levels of potassium, sodium and other minerals in the blood. The adrenal medulla produces adrenaline and noradrenaline. The adrenal glands secrete these hormones in response to exercise, stress and low levels of glucose.

Cholecystitis

s inflammation of the gallbladder and may often be referred to as billiary colic. Cholecystitis can be either acute or chronic in nature. Symptoms of acute cholecystitis are sudden and include right upper quadrant pain, periumbilical pain, low-grade fever, nausea, vomiting and rebound tenderness. In more than 95% of cases, cholecystitis is a complication of stones within the gallbladder that have gravitated into the common bile duct, preventing its drainage. The presence of stones within the gallbladder is termed cholelythiasis. The term choledocholithiasis describes stones in the common bile duct.

Traumatic Injury

serious damage to the human body from some external force. Although trauma can be emotional or physical, in medical imaging, trauma usually pertains to injury to the body as a result of a physical injury. Traumatic injury can affect only internal organs or the skeletal system, or it can affect both the internal organs and skeletal system

Polysplenia-associated Abnormalities

several abnormalities are associated with polysplenia, including a shorter-than-normal pancreas, renal abnormalities, ventricular septal defect and vascular abnormalities.

Inguinal hernias

the most common type, comprising 75% of all of those diagnosed. Inguinal hernias occur in the groin, where a portion of the intestine, omentum, or both, form a sac from the peritoneum. The sac pushes through the weakest point in the groin wall

Meningiomas

tumors that originate in the meningeal layers surrounding the brain and spinal cord. Meningiomas make up between 13% and 20% of all intracranial tumors. Occurring most often in middleaged women, these tumors are both clinically and histologically benign.

Pancolitis

ulcerative colitis spread throughout the entire colon.