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Module 11 Transcript

©2010 ASRT. All rights reserved. CT Basics: Module 1

CT Basics: Computed Tomography Fundamentals Module 11

1. Title Screen Welcome to Module 11 of CT Basics – CT Pathology. This module was written by Bettye G.

Wilson, M.A.Ed., R.T.(R)(CT), RDMS, FASRT. 2. License Agreement

3. Module Objectives

After completing this module, you should be able to:

Identify selected pathology on computed tomography (CT) images.

Name the causes of some of the pathology presented in the module.

Provide statistical data on the prevalence of certain pathologic conditions.

List symptoms associated with the presence of select pathology.

Distinguish between the CT appearance of normal organs and tissues from those involved in pathology.

Define the pathologic processes discussed in the module.

4. Introduction This module is designed to provide participants with knowledge of pathologic conditions and

their appearances on computed tomography (CT) images. Although ARRT certification and registration, as well as state licensure, prohibit technologists from diagnosing diseases, being able to identify pathologic conditions is essential to the knowledge base of technologists. This knowledge assists technologists in their ability to render images of high quality, which allows interpreting physicians to more accurately diagnose acute illnesses, identify pathologic conditions and assess the degree and extent of traumatic injuries. Because it is beyond the scope of this module to cover every pathologic condition that may be identified using CT, a limited number are included.

Radiologist interpretation or pathology reports are used in the discussion of each pathologic

condition and its appearance on CT images.

5. CT Image Display Before we discuss specific pathology and how it appears on a CT image, let’s review the concept

of Hounsfield units or CT numbers. After the image data has been acquired by the CT scanner and reconstructed by the computer, the image can be displayed. The CT image is very much like a radiograph in appearance. Individual anatomy is represented by different shades of gray. Areas of high density appear white, and areas of very low density appear black on the final image.

6. 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.

©2012 ASRT. All rights reserved. CT Basics: Module 11

One of the significant aspects of a CT image, or any digital image for that matter, is that the

image data not only displays a visual difference between tissue types, but there also is an actual mathematical difference between the individual image components. When image data is acquired by a CT scanner, it goes through a process known as quantization. During quantization, each voxel, or individual image element, is assigned a specific number to represent its brightness. Voxels that make up bone have a very specific range of numbers, as do air, muscle and fat. Quantization helps the computer to display the image data appropriately, depending on which tissue type is examined.

7. 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. This image is an excellent example. The circled areas on this image have the lowest CT numbers and appear black; however, we would not expect to see black areas in this part of the brain. They represent air in the cranial vault, an area where we would expect to see lighter shades of gray.

In the same way, 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. Let’s look at some specific cases.

8. Appendicitis

In this case the patient, a five-year old boy, presented with abdominal pain. The pain was located in his lower abdomen and was accompanied by nausea, vomiting and diarrhea. 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. This patient’s white blood cell count was elevated at 21,800 mm3.

A CT scan of the abdomen and pelvis was performed with both intravenous and oral contrast.

No prior images were available for comparison. According to the radiologist’s report, the lung bases demonstrated no significant nodules, infiltrates or effusions. The visualized heart and pericardium were unremarkable, as was the liver, spleen, pancreas, adrenal glands and kidneys. The abdominal aorta was normal in diameter and no significant retroperitoneal adenopathy was seen. However, pathology was noted in the lower abdomen.

9. Appendicitis

This slide shows an axial CT image of the patient’s pelvis. His appendix is markedly inflamed and dilated. It also has notably thick walls. On the left-hand side of the image you can see that the periappendicular fat demonstrates inflammatory stranding. These findings confirm a diagnosis of acute appendicitis. The line that transects the coronal image on the right-hand side demonstrates the level at which this axial image was acquired.

10. Appendicitis

Look at this axial CT image of the same patient, which was acquired at a lower level than the image on the previous slide as shown in the coronal view. A small appendicolith is visualized. An

©2012 ASRT. All rights reserved. CT Basics: Module 11

appendicolith is a 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.

11. Hernia

Hernias 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.

12. Types of Hernias

The various types of hernias can be divided into 2 categories: acquired or congenital. Acquired hernias usually develop later in life, and congenital hernias are present at birth and are caused by embryonic developmental defects. Some hernias, such as Bochdalek and diaphragmatic, can be either acquired or congenital.

Inguinal hernias are the most common type, comprising 75% of all of those diagnosed. Inguinal

hernias occur in the groin, when 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.

13. Incisional Hernia

Incisional hernias 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.

Let’s look at a case report of a patient with a hernia, explore the patient’s medical history and

how a patient may present to the CT department with this type of pathology.

14. Incisional Hernia Case Report A 40-year-old man with a history of Down syndrome reported to an outpatient imaging facility

for a CT scan of the abdomen and pelvis, with and without contrast, for evaluation of a protrusion along the suture line from prior abdominal surgery. It had been 2 months since his surgery. He was below average in height and above average in weight.

15. Incisional Hernia Case Report

The images on this slide are CT scout images, also referred to as scanograms. The image on the left is an AP projection and the image on the right is the lateral. Notice the large bright white areas on these images, which seemingly indicate large amounts of adipose tissue.

16. CT Images of Large Incisional Hernia

This animation shows noncontiguous images through the patient’s abdomen and pelvis. Use the slider bar to follow along with the description.

©2012 ASRT. All rights reserved. CT Basics: Module 11

Image 1 shows thinning of the musculature of the anterior abdominal wall. The beginning of the incisional hernia is shown on image 2. It is demonstrated by a breech in the wall with a small portion of bowel appearing to extend though the peritoneum and musculature. These images were acquired at the level of the kidneys.

Images 3 and 4 demonstrate continued development of the hernia. These 2 images were

acquired inferior to images 1 and 2 images. Note how the hernia appears larger in these images. Images 5 and 6 show increased hernia size and contents as the CT continues inferiorly into the

pelvis. Images 7 and 8 demonstrate that as the CT scan progresses inferiorly into the pelvis the hernia

grows even larger with increased abdominal contents. Image 9, acquired at the level of the acetabulum, appears to show the hernia decreasing in size,

as does image 10, acquired at the level of the trochanters. Images 11 and 12 continue to demonstrate a reduction in the size of the hernia. Images 12 and 13 are the final 2 images of the hernia. They were acquired at the level of the

midshaft of the femur. The radiologist’s findings suggest a large incisional hernia extending from the upper abdomen inferiorly through the pelvis. Surgical repair was performed because of the hernia’s size and the propensity for strangulation.

17. Knowledge Check

Answer the following question.

18. Knowledge Check Answer the following question.

19. Pancreatitis In this case, the patient presented with abdominal pain, had a history of pancreatitis and had

undergone cholecystectomy, which is the surgical removal of the gallbladder. Pancreatitis is an 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. 20. Pancreatitis

The findings of the current CT study were compared to a previous CT examination. The radiologist noted a slight progression of the patient’s bibasilar linear atelectasis since the previous CT exam. Atelectasis is a condition in which portions of the lung are compressed into an area smaller than normal size. Bibasilar means that this condition affects both the left and right lower lungs. The radiologist also observed mild thickening of the distal esophagus. Often a patient with this diagnosis has dysphagia, or difficulty swallowing. An endoscopy or esophagram may be performed as a follow-up study.

©2012 ASRT. All rights reserved. CT Basics: Module 11

21. Pancreatitis Here’s an image from the CT study of the patient with suspected pancreatitis. On this image you

can see a tiny cyst in the inferior right lobe of the liver. The gallbladder is absent because of the patient’s previous cholecystectomy. The radiologist noted a small splenule in the splenic hilum, which is not readily visible on this slice. A splenule is a tiny nodule of tissue found in a portion of the spleen.

The pancreas is somewhat thickened and there is peripancreatic fat stranding, which is linear or

curvilinear inflammatory changes that appear around an inflamed organ. There is minimal symmetric stranding seen in the connective and fatty tissue surrounding the kidneys. A 1.7-cm exophytic cyst can be seen on the posterolateral left kidney. Moderate atherosclerotic calcifications are present.

There are several colonic diverticula, a herniation through the muscle of the colon wall. Patients

with colonic diverticula usually do not have symptoms. Approximately 10% of these cases progress to diverticulitis. Some common symptoms of diverticulitis are pain in the lower left side of the abdomen, change in bowel movements, fever, nausea, vomiting, bloating and rectal bleeding. 22. Small Bowel Obstruction

In this case, the female patient presented with abdominal pain and distention that had been ongoing for 3 days. Her gallbladder had been removed recently. CT imaging of the abdomen and pelvis with both intravenous and oral contrast was recommended. 23. Small Bowel Obstruction

The radiologist noted minimal intrahepatic biliary ductal dilatation and no abnormalities within the liver and spleen. In addition, both the adrenal glands and pancreas appear normal. The kidneys demonstrate normal enhancement, and there is no evidence of obstructing stones or hydronephrosis, which is swelling of the kidney due to the back up of urine.

The large bowel loops are of relatively normal caliber. However, there is marked ectasia, or

dilation, of the small bowel loops, with multiple air-fluid levels. As we discussed earlier in this module, air appears black on the CT image. These findings are consistent with a high-grade small bowel obstruction. 24. Hydrocephalus

Defined as 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.

25. Hydrocephalus

The 2 axial CT images shown here, though “noisy,” are sufficient to demonstrate the increased ventricle size found in hydrocephalus.

26. Lymphoma

©2012 ASRT. All rights reserved. CT Basics: Module 11

Lymphoma is 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. There are 2 main types of lymphoma classifications based on the types of cells involved: Hodgkin and non-Hodgkin lymphoma. All Hodgkin lymphomas involve Reed-Sternberg cells, but non-Hodgkin 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.

27. Central Nervous System Lymphoma

This axial CT image of the brain shows lymphoma in the central nervous system of a patient with a compromised immune system due to HIV. The Centers for Disease Control and Prevention (CDC) defines this development as an AIDS-defining condition. People with compromised immune systems because of immunosuppressant drug use, organ transplantation and chemotherapy are also are at higher risk for developing lymphoma. The arrows in this image identify a midline shift caused by lymphoma, the lymphoma mass and the associated inflammatory process.

28. Hodgkin Lymphoma

This axial CT image of the chest shows a mass within the left anterior lung. The mass extends through the anterior chest wall and into the pectoral muscle. The patient has already been diagnosed with Hodgkin lymphoma. In this case the mass was treated and resolved. With appropriate treatment, Hodgkin lymphoma has the highest survival rate of all of the lymphoma types.

29. Lymphadenopathy

This abdominal CT image demonstrates several enlarged lymph nodes. The image was obtained during a CT scan of the abdomen and chest to stage Hodgkin lymphoma. 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. The enlarged abdominal lymph nodes within the circle on this image indicate their infiltration with lymphoma.

30. Stages of Hodgkin Lymphoma

Hodgkin lymphoma is divided into 4 distinct stages. 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. Treatment options vary with the stage of the disease and other factors.

31. Stage IV Lymphoma

©2012 ASRT. All rights reserved. CT Basics: Module 11

This axial CT image of the chest shows a stage IV lymphoma. Note the presence of lymphoma tissue in the pericardium and thoracic lymph nodes. You can also see a small pleural effusion.

32. Knowledge Check

Answer the following question.

33. Knowledge Check Here are the correct answers.

34. PET-CT CT was the diagnostic imaging procedure used in the staging of lymphoma and other cancers

before PET-CT imaging technology became available. The functional and metabolic information provided by PET fused with the anatomical and structural information provided by CT together provide diagnostic information that cannot be obtained by using either modality alone. PET-CT usually is the examination of choice for pinpointing the extent of disease and its response to treatment.

This image of the chest of a patient with Hodgkin lymphoma shows in the axial CT image that

the patient’s sternum has been invaded by lymphoma. The middle image using PET shows uptake of the radiopharmaceutical in the sternum. The fused PET-CT image on the right shows the location and extent of involvement of the sternum in the disease process.

35. Meningiomas

Meningiomas are 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 middle-aged women, these tumors are both clinically and histologically benign.

36. Meningiomas

This axial CT image of the head on the left shows a meningioma in the left frontoparietal area of the brain as interpreted by a neuroradiologist. The image on the right was obtained by postprocessing the CT image on the left. The extent of the meningioma is clearly identified in the left lower area of this image.

37. 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. For example, an ovarian cyst is easily identified by the radiologist on this CT image of the pelvis to evaluate for right lower quadrant pain.

38. 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.

39. Pancreatic Cancer

©2012 ASRT. All rights reserved. CT Basics: Module 11

These 2 axial CT images of the abdomen were acquired at the level of the pancreas. The image on the right shows a normally appearing pancreas, and the image on the left shows a large mass in the head of the pancreas. The radiologist’s finding for the image on the left was probable pancreatic cancer. The pathology report substantiated the radiologist’s interpretation.

40. Pleural Effusion

Pleural effusion is defined as an 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. 41. Pleural Effusion

A small pleural effusion in the right pleural space is shown on this axial CT image of the chest. This particular effusion is thought to have been caused by lymphoma invasion of the chest. 42. Pleural Effusion

This image shows a very large pleural effusion in the right side of the chest. The effusion encompasses almost all of the lung space, which would normally appear dark. Chest tube placement usually helps to alleviate this type of effusion. 43. 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.

44. Renal Cysts

This axial CT image shows numerous cystic structures in the parenchyma of the right kidney. The presence of more than 1 cyst is called polycystic disease. The composition of each cyst can be obtained by performing a region of interest (ROI) measurement of its Hounsfield, or CT, numbers.

45. Sarcoma

Sarcomas are 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.

46. Sarcoma Origins

Although sarcomas can develop in any part of the body, 60% of sarcomas originate in the arms or legs, 30% percent 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.

47. Symptoms of Sarcoma

The symptoms associated with sarcomas vary among individuals, and depend on the size and location of the tumor. 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

©2012 ASRT. All rights reserved. CT Basics: Module 11

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.

48. Sarcoma

The images on this page are of a 16-year-old male patient. The CT image on the left is a scanogram of the right humerus. The area of interest is located within the circle. Note the disrupted cortex of the bone within the area. Look at the image on the right. The axial CT image through the thorax and a portion of the right and left humeri clearly demonstrates the differences between the 2 bones.

49. Sarcoma of the Humerus

The CT images on this slide are sagittal images of the right humerus. They are contiguous and demonstrate the extent of the sarcoma lesion’s involvement in the bone and, to some extent, into the soft tissue.

50. Sarcoma of the Right Humerus

This animation is the 10 axial CT images through the right humerus. They are sequential, but not contiguous. On axial CT image 1, note that the humerus appears normal, but on image 2, some bony involvement appears to be indicated. Click on the image numbers to scroll through the images. You will notice that the tumor appears larger and to affect more of the bone, as well as some of the soft tissue.

51. CT-guided Biopsy of Sarcoma

The 2 images on this page are from the CT-guided biopsy procedure of the humeral lesion. Image 1 shows the biopsy needle approaching the areas selected for biopsy, and image 2 shows the needle within the tumor. The radiologist’s initial findings were of a large necrotizing mass within the shaft of the humerus extending from slightly inferior to the surgical neck, inferiorly to the epicondyles. The radiologist interpreted this as a possible sarcoma and suggested a biopsy to determine the type. The pathology report indicated that in this case Ewing sarcoma was the pathologic condition.

52. Treatments for Ewing Sarcoma

Treatment options for Ewing sarcoma 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.

53. Knowledge Check

Answer the following question.

54. Sinus Mass Sinus masses 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.

55. Sinus Mass

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This CT image of the maxillary sinuses shows a large mass in the right sinus. The radiologist’s finding indicates that a mass has displaced and possibly invaded the nasal cavity, and spread into the adjacent sinus cavity.

56. Sinus Mass

This image is a more anterior CT image of the same sinus mass shown on the preceding page. It shows further invasion from the mass, possibly extending into the left orbit.

57. Pulmonary Emboli Case Report

This patient complained of shortness of breath and had a history of thrombosis in the lower extremities. Thrombosis is the formation of a blood clot that either partially or completely blocks a vessel. The blockage restricts or prevents blood flow. In the lower extremities, it is referred to as a deep vein thrombosis, or DVT. Common symptoms of DVT include swelling, pain, cramping, unusual warmth or changing skin color of the affected lower leg, including the foot and ankle.

A previous CT pulmonary angiogram had demonstrated pulmonary emboli. A pulmonary

embolus is a 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. After images were obtained for localization and subsequent bolus tracking, the patient was administered intravenous contrast before undergoing another CT pulmonary angiogram.

58. Pulmonary Emboli

The key finding in this case was bilateral pulmonary emboli of varying chronicity. Look at these images. The specific findings include atherosclerotic calcifications in the coronary artery, which are fatty plaques that narrow the vessel, restricting blood flow. The report also noted a thrombus incorporating into the anterior wall of the branch of the left lower lobe of the pulmonary artery, an occlusive thrombus in the right middle lobe of the pulmonary artery and a vascular web in the right lower lobe in the pulmonary artery caused by a prior thrombus.

59. Toxoplasmosis

Toxoplasmosis is 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. People with compromised immune systems, such as those who are HIV positive, are especially vulnerable to the infection. In fact, the CDC lists toxoplasmosis as an AIDS-defining condition for those who are HIV positive.

60. Toxoplasmosis Transmission

Toxoplasmosis can be acquired by eating undercooked food or drinking infested water. 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.” Anyone who has received an organ transplant or blood transfusion from an infected donor also is at risk for the illness. The CDC reports that people taking certain chemotherapy drugs have increased risk as well.

61. Toxoplasmosis

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Toxoplasmosis is identified on this CT image of the brain obtained near the vertex of the skull. The parasitic lesions appear to involve both hemispheres of the brain.

62. Knowledge Check

Answer the following question.

63. Traumatic Injury There is no doubt that CT plays a crucial role in the evaluation of traumatic injury. The word

trauma is defined as 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. This axial CT image through the upper abdomen shows a lacerated liver secondary to blunt trauma. Trauma to the head can result in damage to the bones of the head and face, as well as injury to the brain. Traumatic brain injury is a serious disorder that can result in permanent brain damage or death.

Let’s examine a case report of a patient with head trauma, explore the patient’s medical history

and discover how a patient with head trauma might present to the CT department.

64. CT and Trauma CT scanners are increasingly being used for trauma situations because of the speed with which

images can be acquired and exquisite images that can be reconstructed from the image data. In addition, images can be acquired without the need to place the patient in various positions such as those required in trauma radiography.

When dealing with trauma the technologist should always take the utmost care with the

patient. All trauma patients should be treated as if they have fractures or other physical injuries until the images are able to rule out serious conditions. The technologist must also be aware that trauma, no matter how minor, can result in shock. If a patient is showing signs and symptoms of shock, the technologist should know the proper institutional procedure for dealing with such a situation.

Severe trauma rarely allows for traditional positioning on the CT couch. It is important for each

department and clinic that deals with trauma patients to have a set routine for trauma procedures. Institutions that regularly care for trauma patients should develop special procedures for patients that have been traumatized that require little if any movement of the injured area. 65. Head Trauma Case Report

A 30-year-old man was transported to an emergency department by ambulance. He had been struck by a falling tree. His injuries seemed to mostly involve the head and face. One of his eyes projected further out of the orbit than the other. Paramedics reported that he was alert and responsive during the transport. Physical assessment revealed an apparent depressed frontal bone fracture, numerous facial lacerations and facial flesh that was loose to the touch. Several CT examinations were performed and will be described on the following pages.

66. Subdural Hematoma

This patient was referred for a CT scan of the head after he fell and began complaining of confusion. This image shows several subdural hematomas of varying chronicities. The radiologist noted an acute on subacute right subdural hematoma with local mass effect and significant midline shift. In an

©2012 ASRT. All rights reserved. CT Basics: Module 11

uninjured individual, both sides of the brain look the same. In this case, you can see the difference in the 2 hemispheres of the brain. Swelling on the left side has pushed brain matter across the midline into the right hemisphere.

The right subdural hematoma contains areas of varying attenuation that is compatible with

acute on subacute hemorrhage. The left subdural hematoma is consistent with subacute hemorrhage. There is mass effect on the underlying cerebral sulci, particularly on the right. This patient also demonstrated an old area of infarction involving the left frontal lobe.

67. Facial Bones

Axial CT images of the facial bones were performed and demonstrate fractures of the left maxilla.

68. Facial Bones

The CT scans show the air-fluid level in both maxillary sinuses in the image on the left. The image on the right also shows bilateral zygomatic fractures.

69. CT Images Through the Orbits

The CT image on the left shows normal orbits and how their contents appear. The image on the right has been magnified to show an avulsed optic nerve and probable avulsion of the medial rectus muscle.

70. Frontal Bone Fractures

The 2 CT images shown on this page focus on the skull bones by adjusting the window to a bone setting. In this case, the CT images substantiate the presence of a severe fracture of the frontal bone with numerous fracture fragments.

71. Brain Injury

The severe head trauma sustained by this patient caused air to enter the cranial vault. The left CT image demonstrates air in the frontal area, while the image on the right shows pockets of air posteriorly.

72. Conclusion

As you have seen in this module, there are many different types of pathology that can be imaged using modern CT scanners. Although CT technologists are not asked to identify pathology on a certification exam or in normal CT practice, it is essential that they understand the various types of pathology that might be examined and identified using CT scanning.

73. Module Objectives

This concludes CT Basics Module 11 – CT Pathology. You should now be able to: 1. Identify selected pathology on computed tomography (CT) images. 2. Name the causes of some of the pathology presented in the module. 3. Provide statistical data on the prevalence of certain pathologic conditions. 4. List symptoms associated with the presence of select pathology. 5. Distinguish between the CT appearance of normal organs and tissues from those involved in

pathology. 6. Define the pathological processes discussed in the module.

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74. Bibliography About lymphoma. Lymphoma Research Foundation website. www.lymphoma.org/site/pp.asp?c=chk016PE/mE&b=1574105#development. Accessed August 1, 2012. About stroke. American Stroke Association website. www.strokeassociation.org/STROKEORG/AboutStroke/About-Stroke_UCM_308529_SubHomePage.jsp. Accessed February 28, 2012. Anderson C. Splenic aneurysm symptoms. eHow Health website. www.ehow.com/facts_5543963_splenic-aneurysm-symptoms.html. Accessed April 28, 2011. Aneurysms. Medline Plus website. www.nlm.nih.gov/medlineplus/aneurysms.html. Accessed May 23, 2011.

75. Bibliography Applegate KE. Goske MJ, Pierce G, Murphy D. Situs revisited: imaging of the heterotaxy syndrome. Radiographics. 1999;19:837-852. http://radiographics.rsna.org/content/19/4/837.full. Accessed February 28, 2012. Atelectasis. PubMed Health website. Reviewed September 15, 2010. www.ncbi.nim.nih.gov/pubmedhealth/PMH0001130/. Accessed July 29, 2011. Bezoar. The New York Times Health Guide. http://health.nytimes.com/health/guides/disease/bezoar/overview.html. Accessed February 28, 2012. Colon and rectal cancer. National Cancer Institute website. www.cancer.gov/cancertopics/types/colon-and-rectal. Accessed February 28, 2012. Definition of adrenal gland. Reviewed April 27, 2011. MedicineNet.com website. www.medterms.com/script/main/art.asp?articlekey=2154.

76. Bibliography Definition of bezoar. MedicineNet.com website. www.medterms.com/script/main/art.asp?articlekey=8898. Accessed February 28, 2011. Definition of splenic artery. Reviewed April 27, 2011. MedicineNet.com website. www.medterms.com/script/main/art.asp?articlekey=9357. Diseases of the aorta and its branches. The Merck Manual website. www.merckmanuals.com/professional/cardiovascular_disorders/diseases_of_the_aorta_and_its_branches/aortic_aneurysms.html. Accessed February 28, 2012. Ewings sarcoma FAQ. Updated May 17, 2003. CacerIndex.org. www.cancerindex.org/ccw/faq/ewings.htm.

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Kaushik NK, Sharma YP, Negi A, Jaswal A. Gastric trichobezoar. Published 1999. LearningRadiology.com website. www.learningradiology.com/archives05/COW%20158-Bezoar/bezoarcorrect.htm. McGee M. Adrenal tumors. HealthLine website. Published 2002. www.healthline.com/galecontent/adrenal-tumors. Parasites – toxoplasmosis. Centers for Disease Control and Prevention website. www.cdc.gov/parasites/toxoplasmosis/. Updated November 2, 2010. Accessed August 1, 2011. Understanding the lymphatic system. Lymphomation.org. www.lymphomation.org/lymphatic.htm. Accessed July 22, 2011.

77. Acknowledgements 78. Development Team 79. Final Slide