Abdominal CT Scan Master Class 2025 PDF

Abdominal CT Scan Workshop Block 9 Dr. Andres Aranda. MD, Nephrology. WE MAKE DOCTORS Objectives 1. Review the Basic Principles of CT Scan 2. Recall the advantages of CT Scan over X-Ray 3. Understand the Different Views in Abdom...

Abdominal CT Scan Workshop Block 9 Dr. Andres Aranda. MD, Nephrology. WE MAKE DOCTORS Objectives 1. Review the Basic Principles of CT Scan 2. Recall the advantages of CT Scan over X-Ray 3. Understand the Different Views in Abdominal CT 4. Review the Advantages and Disadvantages of Non-Contrast vs. Contrast CT Scan 5. Recall the Structures to be Assessed on an Abdominal CT Scan 6. Follow a Checklist for Abdominal CT Scan Assessment CAT Scan Basics https://creator.nightcafe.studio/creation/GLUMXYLnltGs1GS3ILJo History A computed tomography (CT) scan, commonly referred to as a CT, is a radiological imaging study. The machine was developed by physicist Allan MacLeod Cormack and electrical engineer Godfrey Hounsfield. Their development awarded them the Nobel Prize in Physiology or Medicine in 1979. The first scanners were installed in 1974. CT scanners create images using a series of X- rays generated by a tube that is rapidly rotated around the examined object. https://x.com/atscommunity/status/520936890002722817 https://www.smithsonianmag.com/innovation/fifty-years-ago-the-first-ct-scan-let-doctors-see-inside-a-living-skull-180978792/ https://www.ncbi.nlm.nih.gov/books/NBK567796/  CT Scan Is essentially an x-ray study, where a series of rays are rotated around a specified body part, and computer-generated cross-sectional images are produced. Enables detailed examination of bones, organs, blood vessels, and soft tissues. Low-dose CT scans 10 mSV (10x abd Xray) The study was initially called a CAT scan representing computer axial tomography, where the table moved after each axial image was obtained. It involves ionizing radiation, which has the potential to cause biological tissue harm. They can have 50 to 1000 times higher radiation dose than conventional x-rays. They account for the largest portion of radiation after natural/environmental sources to the population. CT scans comprise approximately 50% of all medical radiation. https://www.youtube.com/watch?v=05IFgGhc5I4  X-Ray vs. CT Scan CT Scan: X-ray: High-resolution imaging, offering detailed views of Limited in detail. multiple structures. Primarily highlights bone density. Suitable for comprehensive evaluation of soft tissues, organs, and bones. Indications: It can be utilized in both inpatient and outpatient clinical settings. It can rule out serious illness. To make diagnosis, or narrow the differential diagnosis. This modality can also be used for cancer screening, staging, and follow-up. To perform biopsies adequately and to assist during a surgical procedure, or treatment. https://www.ncbi.nlm.nih.gov/books/NBK441888/figure/article-26080.image.f1/  Imaging: X-ray beams are used to create images that show tissues in two and three dimensions based on their density. The density of the structures is measured in Hounsfield units (HUs), which indicate how much X-ray energy is absorbed by specific tissues in the body.  Hounsfield Units (HU) Attenuation is directly related to Hounsfield Units. Hounsfield Units (HU) are the quantitative measure of tissue density in CT imaging. Hyperdense: Tissues denser than water have positive values (e.g., bone). +1000 Hypodense: Less dense tissues have negative values (e.g., air). -1000 Isodense: Water is the reference with a Hounsfield Unit of 0. Attenuation Attenuation is the reduction of X-ray beam intensity as it passes through tissues during a CT scan. Tissues attenuate X-rays differently based on their density. Dense structures, like bones, attenuate more X-rays and appear brighter. Less dense structures, like air or certain soft tissues, attenuate fewer X-rays and appear darker. Orientation and views: The axial scans (cross-sectional images) are most commonly used in clinical practice, but when needed, the CT can produce other views (sagittal or coronal). For axial scans, you can imagine that you're looking at the person through their feet while facing the person directly (your left is the right side on the scanned patient). https://www.kenhub.com/en/library/anatomy/how-to-read-an-abdominal-ct Orientation/ Technique Michael Hartung. ABDOMINAL CT ESSENTIALS HANDBOOK. www.medmastery.com Views in CT Scan Axial View Coronal View Sagittal View Non-Contrast vs. Contrast Abdominal CT Scan Involves imaging without the use of Involves the use of contrast agents to enhance contrast agents. visibility. Intravenous iodine-based, or oral barium- based contrast is used to visualize the digestive Utility: system. IV/ orally / rectal. Assessing baseline anatomy. Utility: Identifying calcifications, stones, and Enhancing visualization of, the GI tract, blood vessels fractures. and specific tissues. Minimizing the risk of contrast-related Identifying and characterizing lesions, tumors, and reactions. vascular abnormalities. Clinical Scenarios: Clinical Scenarios: Renal stones, bone fractures, initial Evaluating vascular structures, tumors, liver lesions. trauma assessments. Considerations: Patient Preparation. Balancing the need for enhanced visualization with potential risks. Non-contrast Contrast ORAL contrast RECTAL contrast https://www.researchgate.net/publication/40031631_Emergency_abdominal_radiology_T he_acute_abdomen/figures?lo=1  IV and ORAL contrast https://www.researchgate.net/publication/230566324_Simultaneous_Acute_Cholecystitis_and_Acute_Appendicitis_Treated_by_a_Sin gle_Laparoscopic_Operation/figures?lo=1 Abdominal CT Scan Abdominal CT Scan Offers a comprehensive view, enabling the visualization of diverse structures within the abdominal region: Gastrointestinal. Urinary / reproductive. Vascular. Musculoskeletal. Other organs and tissues (lymph nodes, soft tissue, etc.). Use a systematic approach: Be focused on one organ at the time. Evaluate th eorgan individually and thoroughly. The radiologist should not focus only on one structure, but rather on the entire scan. These techniques minimize the possibility of missing out on small structural changes and incidental findings that the patient may have. https://www.iienstitu.com/en/blog/systematic-approach Abdominal CT Scan Structural Assessment Checklist 1. Abdominal wall 2. Bones 3. Peritoneal cavity 4. Solid organs 5. Hollow organs 6. Blood vessels 1. Abdominal Wall Anatomy Abdominal CT Scan Structural Assessment 1.Abdominal Wall Psoas 2. Abdominal Bones Abdominal CT Scan Structural Assessment 2. Bones Ribs Vertebral column Hip bones https://radiopaedia.org/cases/how-to-read-a-ct-of-the- abdomen-and-pelvis?lang=us 3. Peritoneal Cavity  Abdominal CT Scan Structural Assessment 3. Peritoneal Cavity Looks for collections of air (pneumoperitoneum). Fluids and solid masses. Omenta Greater omentum Lesser omentum Mesenteries Mesentery proper Transverse mesocolon Sigmoid mesocolon Peritoneal recesses https://radiopaedia.org/cases/how-to-read-a-ct-of-the-abdomen-and-pelvis?lang=us 4. Solid Abdominal Organs Abdominal CT Scan Structural Assessment 4. Solid organs Liver Gallbladder Spleen Pancreas Suprarenal glands Kidneys https://radiopaedia.org/cases/how-to-read-a-ct-of- the-abdomen-and-pelvis?lang=us 5. Hollow Abdominal Organs Abdominal CT Scan Structural Assessment 5. Hollow organs Stomach Small intestine Duodenum Jejunum Ileum Large intestine Cecum Ascending colon Transverse colon Descending colon Sigmoid colon Rectum https://radiopaedia.org/cases/how-to-read-a-ct-of-the-abdomen-and-pelvis?lang=us 6. Abdominal Blood Vessels Abdominal CT Scan Structural Assessment 6. Blood Vessels Arteries Aorta Celiac Trunk SMA IMA Veins IVC Splenic vein SMV IMV https://radiopaedia.org/cases/how-to-read-a-ct-of-the-abdomen-and-pelvis?lang=us Diagnosis Data from Cline D, Maisel J, Sokolosky M, et al. Gastrointestinal emergencies. In: Cline D, Ma O, Cydulka R, et al, editors. Tintinall's emergency medicine just the facts. Kansas city (KS): McGraw-Hill Companies, Inc; 2012. p. 140-81; and Broder J. Diagnostic imaging for the emergency physician. Philadelphia: Elsevier Saunders; 2011. Abdominal Anatomy on Computed Tomography Abdominal Anatomy on Computed Tomography Speaker: Dr. Mahan Mathur, MD. Assistant Professor of Radiology and Biomedical Imaging, Yale University School of Medicine https://youtu.be/r6FXMZJGecg?si=Z0rseyfaTkilh_Kf Sources Student pre-lecture: https://www.kenhub.com/en/library/anatomy/how- to-read-an-abdominal-ct Master Class: Patel PR, De Jesus O. CT Scan. [Updated 2023 Jan 2]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK567796/ https://x.com/atscommunity/status/520936890002722817 https://www.smithsonianmag.com/innovation/fifty-years-ago-the-first-ct- scan-let-doctors-see-inside-a-living-skull-180978792/ https://radiopaedia.org/cases/how-to-read-a-ct-of-the-abdomen-and- pelvis https://radiopaedia.org/cases/normal-ct-of-the-abdomen-and-pelvis- male https://youtu.be/r6FXMZJGecg?si=uRkE_59CjyxejZ4V