急性胰腺炎影像学诊断

Chris Allmon, HMS III Gillian Lieberman, MD 1 Imaging Acute Pancreatitis • Chris Allmon, Harvard Medical School Year III • Gillian Lieberman, MD July 2006 Chris Allmon, HMS III Gillian Lieberman, MD 2 Acute Pancreatitis Pathophysiology • Blockage of the pancreatic duct leads to increased pressure in pancreatic duct and rupture. • Pancreatic fluid (proteolytic and lipolytic enzymes) ruptures into pancreas parenchyma and anterior pararenal space Chris Allmon, HMS III Gillian Lieberman, MD Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 3 Anatomy of the Pancreas Chris Allmon, HMS III Gillian Lieberman, MD Netter, Atlas of Human Anatomy Chris Allmon, HMS III Gillian Lieberman, MD 4 Anterior Pararenal Space • Kidney is retroperitoneal • Shares Anterior pararenal space with duodenum, ascending and descending colon • Anterior to Aorta, IVC, and kidneys Chris Allmon, HMS III Gillian Lieberman, MD Robbins and Cotran, Pathologic Basis of Disease Chris Allmon, HMS III Gillian Lieberman, MD 5 Avenues of Spread of Inflammation and Fluid in Acute Pancreatitis • 1= spread into the lesser sac • 2 = spread into the transverse mesocolon • 3 = spread into the root of the bowel mesentery • 4 = extension into the duodenum • 5= inferior spread into the remainder anterior pararenal space D = duodenum; L = lung; P = Pancreas; S = Spleen; SBM = Small bowel Mesentery; TC = transverse colon Chris Allmon, HMS III Gillian Lieberman, MD Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 6 Our Patient • CC: – 37 yo male, HIV+, alcoholic with chronic pancreatitis complaining of 3 days of epigastric pain • Hospital Course: – 18 days in the ICU – Intubated HD 2-15 – Discharged HD 20 Chris Allmon, HMS III Gillian Lieberman, MD Note: All subsequent radiographs, except “Normal Pancreas” are from our patient. Chris Allmon, HMS III Gillian Lieberman, MD 7 Imaging Goals in Pancreatitis 1. Exclude other abdominal disorders that can mimic acute pancreatitis – DDx: acute cholecystitis, bowel obstruction or infarction, perforated viscus, renal colic, duodenal diverticulitis, aortic dissection, appendicitis, and ruptured abdominal aortic aneurysm 2. Confirm clinical diagnosis of acute pancreatitis 3. Staging the disease, by evaluation of the extent and nature of pancreatic injury and peripancreatic inflammation • Menu of Tests: Plain Film,Ultrasound,CT,MR Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 8 Abdominal Plain Film • Use: Quick and easy study useful in ruling out items in the differential requiring urgent surgery like appendicitis • Findings of Acute Pancreatitis on Abdominal Plain Film – Duodenal ileus in 42% of patients – Colon cutoff (paucity of gas distal to splenic flexure due to spasm of colon affected by spread of pancreatic inflammation) – Pancreatic abscess (gas bubbles) – Abdominal fat necrosis and saponification (effects of activated lipase on fatty tissues) Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 9 Our Patient: Duodenal Ileus Radiograph courtesy of Dr. Anne Kim Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 10 Plain Chest Film • 1/3 of acute pancreatitis patients have pulmonary changes secondary to superior spread of pancreatic inflammation to diaphragm and lung bases • Findings of Acute Pancreatitis on Plain Chest Film: – pleural effusions (seen on 10% of chest films) – basal atelectasis – pulmonary infiltrates – elevated diaphragm – Acute Respiratory Distress Syndrome Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 11 Our Patient: Pleural Effusion and Lower Lobe Atelectasis Image courtesy Dr. Anne Kim Rapid appearance of air bronchograms suggest Atelectasis Diaphragms are Silhouetted out by Effusion Chris Allmon, HMS III Gillian Lieberman, MD 12 Ultrasound • Indications – Good screening test in mild disease, suspected biliary pancreatitis, and thin patients lacking fat planes for good CT evaluation • Uses – Exclude a diagnosis of gallstones – Followup of pseudocysts – Doppler of cystic masses to rule out pseudoaneurysm • Major Limitations – Bowel gas hinders visualization of pancreas and extrapancreatic spread of inflammation visualization in 1/3 to 1/2 of patients. – US cannot specifically reveal areas of necrosis – an extremely important prognostic indicator – Liver is internal reference for echogenicity and is often abnormal in pancreatitis patients Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 13 Image courtesy Dr. Anne Kim Our Patient: Ultrasound Evaluation Dirty shadows due to overlying bowel gas Calipers assessing diameter of common bile duct Chris Allmon, HMS III Gillian Lieberman, MD 14 Other Imaging Studies in Acute Pancreatitis • Barium Studies – Inflammation of the posterior stomach with speculation – Atony and enlarged duodenal sweep of duodenal ileus • Endoscopic Retrograde Cholangiopancreatography – ERCP is rarely used in acute pancreatitis because it can exacerbate inflammation or cause infection • Angiography – Usually not performed unless pseudoaneurysm is suspected on CT that can be embollically treated • MR – Used in patients with contraindications to iodonated contrast, to better delineate hemorrhagic complications, and to accurately define the morphology of pancreatic and bile ducts Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 15 Computed Tomography “CT is the premier imaging test in the diagnosis and management of patients with acute pancreatitis. It visualizes the gland, the retroperitoneum, the abdominal ligaments, the mesenteries, and the omenta in their entirety.” - Textbook of Gastrointestinal Radiology, Gore and Levine, 2000 Chris Allmon, HMS III Gillian Lieberman, MD 16 Patent Airways surrounded by collapsed alveolar air spaces Image courtesy of Dr. Anne Kim Our Patient’s CT: Atelectasis Chris Allmon, HMS III Gillian Lieberman, MD 17 Bilateral fluid accumulation in dependent lung regions Image courtesy of Dr. Anne Kim Our Patient’s CT: Pleural Effusion ROI: 5 HU (simple fluid) Chris Allmon, HMS III Gillian Lieberman, MD 18 Image courtesy of Dr. Anne Kim Pancreas and Anterior Pararenal Space Normal •Homogeneous parenchyma •Distinct fat planes Our Patient’s Acute Pancreatitis •diffuse enlargement with shaggy, irregular borders •“Boggy,” heterogeneous parenchyma •Adjacent fat planes are thickened with inflammation in anterior pararenal space Chris Allmon, HMS III Gillian Lieberman, MD 19 Image courtesy Dr. Anne Kim Our Patient’s Pseudocyst in Lesser Sac or Gastric Wall ROI: •12 HU (simple fluid) •69mm x 36mm Gore and Levine, Textbook of Gastrointestina l Radiology Chris Allmon, HMS III Gillian Lieberman, MD 20 Our Patient’s Evaluation for Pancreatic Necrosis Focal areas of necrosis show enhancement of less than 30 HU in early arterial phase These Three ROIs: •72 HU, 66 HU, and 45 HU Image courtesy of Dr. Anne Kim Chris Allmon, HMS III Gillian Lieberman, MD 21 Normal Bowel Wall Edematous, Inflamed Bowel Wall Inflamed Fat Normal Fat Radiograph courtesy Dr. Anne Kim Our Patient’s Inflammation Spreads to the Transverse Colon Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 22 Our Patient’s Splenic Vein Occlusion Image courtesy Dr. Anne Kim Chris Allmon, HMS III Gillian Lieberman, MD 23 Our Patient’s Volume Rendering Reconstruction: Splenic Vein Occlusion Splenic Artery (Occluded Splenic V. not visible) Image courtesy Dr. Anne Kim Chris Allmon, HMS III Gillian Lieberman, MD 24 Our Patient’s Fluid Collection Course: Superolateral to the region of the lesser sac, becoming contiguous with the greater curvature of the stomach Structure: ill-defined, with indistinct margins Image courtesy Dr. Anne Kim ROI: 16 HU (simple fluid) Chris Allmon, HMS III Gillian Lieberman, MD 25 Following the Course of Two Fluid Collections in Our Patient Image courtesy of Dr. Anne Kim Chris Allmon, HMS III Gillian Lieberman, MD 26 Our Patient’s Pancreatic Ascites Dependent fluid collection between liver and diaphragm ROI: 14 HU Image courtesy Dr. Anne Kim Chris Allmon, HMS III Gillian Lieberman, MD 27 Pancreatitis: Still A Major Diagnostic Challenge • CT has dramatically improved the diagnosis and treatment of acute pancreatitis, but… 1. Only 1 in 3 severe cases of acute pancreatitis is recognized to be severe at initial presentation. 2. 42% of fatal cases of acute pancreatitis do not have the correct diagnosis before autopsy. Gore and Levine, Textbook of Gastrointestinal Radiology Chris Allmon, HMS III Gillian Lieberman, MD 28 Sources • Textbook of Gastrointestinal Radiology / [edited by] Richard M. Gore, Marc S. Levine. London : W. B. Saunders Co., c2000. • Netter, Frank H. (Frank Henry), 1906-1991. Atlas of Human Anatomy / by Frank H. Netter; John T. Hansen, consulting editor. Teterboro, N.J. : Icon Learning Systems, 2003. • Robbins and Cotran Pathologic Basis of Disease. Philadelphia : Elsevier Saunders, c2005. Chris Allmon, HMS III Gillian Lieberman, MD 29 Acknowledgements • Anne “AC” Kim, MD • Gillian Lieberman, MD • Pamela Lepkowski • Larry Barbaras, Webmaster Imaging Acute Pancreatitis Acute Pancreatitis Pathophysiology Anatomy of the Pancreas Anterior Pararenal Space Avenues of Spread of Inflammation and Fluid in Acute Pancreatitis Our Patient Imaging Goals in Pancreatitis Abdominal Plain Film Our Patient: Duodenal Ileus Plain Chest Film Our Patient: Pleural Effusion and Lower Lobe Atelectasis Ultrasound Our Patient: Ultrasound Evaluation Other Imaging Studies in Acute Pancreatitis Computed Tomography Our Patient’s CT: Atelectasis Our Patient’s CT: Pleural Effusion Pancreas and Anterior Pararenal Space Our Patient’s Pseudocyst in Lesser Sac or Gastric Wall Our Patient’s Evaluation for Pancreatic Necrosis Our Patient’s Inflammation Spreads to the Transverse Colon Our Patient’s Splenic Vein Occlusion Our Patient’s Volume Rendering Reconstruction: Splenic Vein Occlusion Our Patient’s Fluid Collection Following the Course of Two Fluid Collections in Our Patient Our Patient’s Pancreatic Ascites Pancreatitis: Still A Major Diagnostic Challenge Sources Acknowledgements