Introduction to CT Abdomen and Pelvis: Anatomy and Approach

This segment provides an introduction to abdominal CT scans, emphasizing the importance of understanding basic CT principles, Hounsfield units, and windowing techniques before diving into specific cases. It encourages viewers to watch a preliminary video on CT basics and discusses the structure of the two-part video series. The first part will focus on normal CT anatomy, measurements, variants, and clinical pearls, while the second part will address common findings, critical diagnoses, and clinical situations. The speaker also introduces peritoneal cavity concepts, explaining the peritoneum's role in lining the abdominal cavity and enveloping organs, and distinguishes between the parietal and visceral peritoneum.

The paragraph delves into peritoneal anatomy, discussing the peritoneum's folds and the concept of peritoneal ligaments, including the omentum and mesentery. It highlights the clinical importance of understanding peritoneal ligaments as pathways for disease spread, using the example of omental caking in the case of peritoneal metastases from ovarian cancer. The speaker also describes the peritoneal spaces and their relevance in identifying abnormalities like ascites or blood after trauma.

This section continues the exploration of abdominal anatomy, focusing on peritoneal and retroperitoneal spaces. It explains the distinction between these spaces in the context of the peritoneal cavity and ligaments, and introduces the concept of the greater omentum in relation to abdominal pathology. The speaker also discusses the retroperitoneal structures, such as the kidneys within the perirenal space, and the importance of fascia in understanding the spread of diseases like pancreatitis.

The speaker discusses the clinical relevance of extraperitoneal spaces, particularly in the context of trauma and pelvic fractures. The explanation includes the importance of identifying the type of bladder rupture—extraperitoneal or intraperitoneal—and the treatment implications of each. The segment also covers various extraperitoneal spaces, such as the pre-vesicle space and the space of Retzius, and their significance in clinical scenarios.

This segment provides a detailed look at liver anatomy, including the division of the liver into eight segments based on hepatic veins and the portal vein. It explains the functional split of the liver into left and right lobes and introduces the concept of segmental anatomy for describing abnormalities. The speaker also touches on common locations for focal fat in the liver and the importance of understanding liver vasculature.

The speaker discusses the anatomy of the gallbladder, including its division into the fundus, body, and neck, and the potential for stones to cause obstructions and acute cholecystitis. The segment also covers the biliary system, explaining the flow from the hepatic ducts through the common hepatic duct, cystic duct, and common bile duct, and the importance of measuring the common bile duct's diameter in different age groups.

This paragraph provides an overview of the pancreas and kidney anatomy. It describes the pancreas's division into the head, neck, body, and tail, and the importance of recognizing variants like pancreatic divisum. The speaker also covers the adrenal glands' position and size, and the kidneys' structure, including the cortex, medulla, and collecting system, highlighting the changes in renal enhancement patterns during different phases of contrast imaging.

The speaker discusses kidney pathology, such as the stratified nephrogram appearance indicative of conditions like pyelonephritis, and the importance of differentiating causes of abnormal enhancement patterns. The segment also covers pelvic anatomy, including the bladder, rectum, vagina, cervix, uterus, ovaries, and the method of locating the ovaries by following vascular pedicles.

This segment offers a comprehensive review of bowel anatomy, starting from the esophagus and moving through the stomach, duodenum, and both small and large intestines, to the appendix and colon. It also discusses the ileocecal valve's significance and how to identify the appendix. The speaker covers the '369 rule' for determining bowel dilation and provides an overview of the abdominal vasculature, including the celiac axis, superior mesenteric artery, and the inferior mesenteric artery.

The speaker discusses lymph node stations in the abdomen and pelvis, explaining how to identify and assess them for abnormalities based on size, shape, and clinical context. The segment then outlines a systematic approach to reviewing an abdominal and pelvic CT scan, emphasizing the importance of a general overview, checking for free intraperitoneal gas and fluid, and methodically assessing each organ and structure for abnormalities.

This paragraph focuses on the diagnosis of acute appendicitis, describing the identification of inflammatory changes, a stone at the base of the appendix, and a dilated inflamed appendix. The speaker emphasizes the importance of a thorough scan review, even after identifying a clear abnormality, to ensure no findings are missed and discusses the steps to follow in the scan review process, including assessing the vasculature, hepatic system, bones, soft tissues, and reformats for a comprehensive evaluation.

The final segment stresses the importance of not missing critical diagnoses in abdominal CT scans, such as pancreatic cancer, and discusses strategies for identifying liver hypodensities and determining their benign or worrisome nature. The speaker mentions that future videos will cover abnormal cases in more detail, focusing on ensuring that viewers can recognize and respond to critical findings in each organ.