TL: Imaging 1 (July 31, 2024) - PDF

TL: IMAGING 1 Block: Foundations Block Director: James Proffitt, PhD Session Date: Wednesday, July 31, 2024 Time: 1:00 pm – 3:00 pm Instructor: William Rappaport, MD Department: Surgery Email: [email protected] / cdjpk1@gmail....

TL: IMAGING 1 Block: Foundations Block Director: James Proffitt, PhD Session Date: Wednesday, July 31, 2024 Time: 1:00 pm – 3:00 pm Instructor: William Rappaport, MD Department: Surgery Email: [email protected] / [email protected] Instructor: Stephane Chartier, DO Department: Medical Imaging Email: [email protected] INSTRUCTIONAL METHODS Primary Method: IM26: Team-Based Learning (TBL) ✓ Flipped Session ✓ Clinical Correlation Resource Types: RE18: Written or Visual Media (or Digital Equivalent) INSTRUCTIONS BEFORE CLASS Watch the Intro to Imaging ILM attached to The Intro to the Body Gross Lab [July 30 & Aug 1 afternoons]. Review the Introduction to the Body Lab Notes and associated images – recommend time for anatomical review and study prior to the TL session Read the notes for this session. READINGS N/A LEARNING OBJECTIVES: 1. Students will explain the advantages of a Chest Radiograph (CXR) in an Emergency Room patient with shortness of breath versus CT scan. 2. Students will explain the basics of reading a CXR including identification of critical anatomical markers. 3. Students will identify conditions where CT scan is superior to CXR. 4. Students will identify major abdominal organs on abdominal XR. 5. Students will identify the liver, spleen, pancreas, kidney, stomach, and colon on an abdominal CT scan with oral and intravenous (IV) contrast. 6. Students will describe the advantages and disadvantages of Ultrasound and CT in screening for abdominal trauma. Block: Foundations | RAPPAPORT / CHARTIER [1 of 8] TL: IMAGING 1 CURRICULAR CONNECTIONS Below are the competencies, educational program objectives (EPOs), course objectives, session learning objectives, disciplines and threads that most accurately describe the connection of this session to the curriculum. Related Related COs Competency\EPO Disciplines Threads LOs CO-02 LO-01 MK-09: Critical Clinical Diagnostic through thinking about skills Imaging/Radiology LO-06 medical science Anatomy and about the Radiology Acute Care diagnosis and Immunology treatment of disease NOTES RADIOGRAPHY AND CT Over approximately 80 million chest radiographs are performed every year in the US alone. Chest radiographs (X-rays) are the most common imaging test done due to low cost, relatively low dose of radiation, and simplicity (the patient can go to the radiology suite which houses the X-ray machine or a portable X-ray machine can be taken to a patient’s bedside). TECHNIQUE X-ray Radiography - X rays produced by an X-ray Tube enters the patient and some of these are absorbed by different structures based on density and the rest pass through the patient to form the image on an image detector. Computed Tomography - Uses X rays which are generated by a tube and pass through the patient to a ring of detectors and create cross sectional or tomographic images of a chosen volume of anatomy like the brain, chest or abdomen. CT has higher spatial resolution and less overlap of structures than normal radiographs (X-rays) and hence provides much greater detail of organs for example lungs, arteries and heart. However, CT uses more radiation to generate these images than simple X-rays and is more expensive than X-ray evaluation. In addition, a patient must be transported to the CT machine for evaluation versus with simple X-ray evaluation a portable can be performed at bedside for example the Emergency Department (ED) if the patient is too unstable for transportation. Block: Foundations | RAPPAPORT / CHARTIER [2 of 8] TL: IMAGING 1 CHEST RADIOGRAPHY AND NORMAL ANATOMY - Chest X-ray image various anatomical structures in thorax including - Trachea, carina, mainstem bronchi - Lungs and pleural spaces - Cardiovascular structures – heart and aorta, pulmonary arteries - Bones- ribs, spine and shoulder gridle Chest XR is based on opacity – bone is white (more opaque) and air is black (lucent). The lungs are darker because they are filled with air, soft tissue structures are more opaque (such as the hila, made of blood vessels and lymph nodes) and appear relatively lighter/grey. CHEST RADIOGRAPHY USES Block: Foundations | RAPPAPORT / CHARTIER [3 of 8] TL: IMAGING 1 Acute setting- Trauma - to identify rib fractures, pneumothorax (air in the pleural space), pneumonia, pleural effusions (fluid in the pleural space). Non emergent setting- preoperative chest evaluation, chronic cough. CHEST COMPUTED TOMOGRAPHY - Can be performed with or without intravenous iodinated contrast. Contrast helps identify intravascular pathology like pulmonary embolism, aortic dissection. CT is based on density; air is black and bone white. If contrast is used it increases density (white) and opacifies the inside of vessels such as the aorta and pulmonary arteries. CHEST CT ANATOMICAL STRUCTURES IMAGED - Tracheobronchial tree including endobronchial lesions, mediastinal lesions like lymph nodes, thymus, Cardiovascular structures including heart chambers and vessels in detail, lungs, diaphragm, bones, soft tissue. Block: Foundations | RAPPAPORT / CHARTIER [4 of 8] TL: IMAGING 1 CHEST CT USES Acute setting - pulmonary embolism, aortic dissection, trauma for fractures, pneumothorax, pneumomediastinum, visceral injury, aortic injury, lung contusion and laceration, empyema, lung abscess Non emergent setting - Lung cancer screening; CT scan can detect a lung cancer at a much smaller size than Chest X-ray (CT has higher sensitivity). CT is used for lung cancer screening in patients at high risk (people who have smoked tobacco for many years). By diagnosing the cancer at a smaller size CT improves survival. ABDOMINAL RADIOGRAPHS Anatomical structures identified liver opacity, bowel loops including small and large bowel, kidney outline, lumbar spine and pelvic bones. The viscera such as liver, spleen, pancreas and kidneys are not well visualized and their abnormalities are not identifiable on radiographs, hence abdominal ultrasound, CT or MRI (cross sectional imaging modalities) are more commonly used for evaluation of intrabdominal pathology. Block: Foundations | RAPPAPORT / CHARTIER [5 of 8] TL: IMAGING 1 Acute setting – Abdominal radiographs are useful in diagnosing Pneumoperitoneum (upright radiograph of lower chest and upper abdomen), Renal stones, dilated bowel loops and bowel obstruction Abdominal radiograph in a small bowel obstruction case, dilated air filled bowel loops are lucent (black), the liver is opaque (white) and lumbar vertebra are also opaque. A NG tube with radiodense line to mark tube is identified in the region of stomach. Block: Foundations | RAPPAPORT / CHARTIER [6 of 8] TL: IMAGING 1 ABDOMINAL CT Demonstrates detailed anatomy of all viscera including liver, spleen, pancreas, kidneys, adrenals, bowel loops, urinary bladder, and bones. In trauma CT scan gives much more detail as to organ injury versus abdominal radiographs or Ultrasound. (see below) Advantages & Disadvantages of Bedside x-ray evaluation in acutely ill patients with pulmonary pathology - Bedside chest radiograph is usually the first line of imaging in acutely ill patient as it’s easy to perform and has lower radiation and the patient can remain in the Emergency Department and be monitored versus CT scan. However, on a radiograph there is two dimensional representation of organs and hence loss of information. Bedside chest radiographs are useful in evaluation of pneumonia, pneumothorax, and pulmonary edema. On the other hand, although CT gives more radiation, it is very accurate for diagnosis of many acute diseases like pulmonary embolism, aortic dissection, traumatic injuries, empyema, abscess, bowel obstruction, perforation, lung masses and cancer, which are not evaluated or incompletely evaluated on radiographs. In the setting of acute trauma to the abdomen such as a Motor Vehicle Collision (MVC) where you suspect intra-abdominal organ injury and bleeding a focused Ultrasound (US) exam Block: Foundations | RAPPAPORT / CHARTIER [7 of 8] TL: IMAGING 1 (FAST) is a useful Emergency Department bedside technique to evaluate for hemoperitoneum (blood in the abdomen). The US can tell you if there is blood in the abdomen but may not be able tell you in most cases what organ is bleeding. US is fast, can be done at the bedside, and US involves no radiation exposure. CT provides much greater detail in abdominal trauma. On CT identification of the bleeding organ source is possible. For example, if a liver, spleen or kidney injury has resulted in hemoperitoneum the CT scan of the abdomen will identify organ injured and active bleeding which guides treatment. In summary an ultrasound is a rapid bedside investigation with no radiation exposure that identifies if there is blood in the abdomen from injury in motor vehicle accident. A CT tells you what organ is injured, amount of blood in the abdomen and if bleeding is still ongoing. Block: Foundations | RAPPAPORT / CHARTIER [8 of 8]