Imaging acute Imaging acute pancreatitispancreatitis

Dr/Ahmed BahnassyDr/Ahmed Bahnassy

MBCHB-MD-FRCRMBCHB-MD-FRCR

Consultant Radiologist-RMHConsultant Radiologist-RMH

Acute Pancreatitis Acute Pancreatitis PathophysiologyPathophysiology

• Blockage of the pancreatic duct leads to increased Blockage of the pancreatic duct leads to increased pressure in pancreatic duct and rupture. pressure in pancreatic duct and rupture.

• Pancreatic fluid (proteolytic and lipolytic enzymes) ruptures Pancreatic fluid (proteolytic and lipolytic enzymes) ruptures into pancreas parenchyma and anterior pararenal space into pancreas parenchyma and anterior pararenal space

Gore and Levine, Textbook of Gastrointestinal Radiology

Anterior Pararenal SpaceAnterior Pararenal Space

• Kidney –like Kidney –like pancreas-is pancreas-is retroperitonealretroperitoneal

• Shares Anterior Shares Anterior pararenal pararenal space with space with duodenum, duodenum, ascending and ascending and descending descending coloncolon

• Anterior to Anterior to Aorta, IVC, and Aorta, IVC, and kidneyskidneys

Robbins and Cotran, Pathologic Basis of Disease

The long range The long range inflammatory missilesinflammatory missiles

• Peripancreatic Peripancreatic fluid can spread fluid can spread through through diaphragmatic diaphragmatic hiatuses ,peritonhiatuses ,peritoneal recesses, or eal recesses, or retropritoneal retropritoneal fascial planes to fascial planes to present in present in remote sites.remote sites.

Targets of Inflammatory spreadTargets of Inflammatory spread in Acute Pancreatitis in Acute Pancreatitis

• 1= spread into the lesser 1= spread into the lesser sac sac

• 2 = spread into the 2 = spread into the transverse mesocolon transverse mesocolon

• 3 = spread into the root 3 = spread into the root of the bowel mesentery of the bowel mesentery

• 4 = extension into the 4 = extension into the duodenum duodenum

• 5= inferior spread into 5= inferior spread into the remainder anterior the remainder anterior pararenal spacepararenal space

• 6=RP fluid colecting 6=RP fluid colecting down to scrotum,or even down to scrotum,or even thighthigh

Gore and Levine, Textbook of Gastrointestinal Radiology

Imaging Goals in PancreatitisImaging Goals in Pancreatitis

1.1. Exclude other abdominal disorders that can Exclude other abdominal disorders that can mimic acute pancreatitismimic acute pancreatitis

– DDx: acute cholecystitis, bowel obstruction or DDx: acute cholecystitis, bowel obstruction or infarction, perforated viscus, renal colic, duodenal infarction, perforated viscus, renal colic, duodenal diverticulitis, aortic dissection, appendicitis, and diverticulitis, aortic dissection, appendicitis, and ruptured abdominal aortic aneurysmruptured abdominal aortic aneurysm

2.2. Confirm clinical diagnosis of acute Confirm clinical diagnosis of acute pancreatitispancreatitis

3.3. Staging the disease, by evaluation of the Staging the disease, by evaluation of the extent and nature of pancreatic injury and extent and nature of pancreatic injury and peripancreatic inflammationperipancreatic inflammation

Abdominal Plain FilmAbdominal Plain FilmFindings of Acute Findings of Acute

Pancreatitis on Pancreatitis on Abdominal Plain FilmAbdominal Plain Film– Duodenal ileusDuodenal ileus in 42% of in 42% of

patients patients – Colon cutoffColon cutoff (paucity of (paucity of

gas distal to splenic gas distal to splenic flexure due to spasm of flexure due to spasm of colon affected by spread colon affected by spread of pancreatic of pancreatic inflammation)inflammation)

– Pancreatic abscessPancreatic abscess (gas (gas bubbles)bubbles)

– Abdominal fat necrosis Abdominal fat necrosis and saponificationand saponification (effects (effects of activated lipase on fatty of activated lipase on fatty tissues)tissues)

Plain Chest FilmPlain Chest Film

• 1/3 of acute pancreatitis patients have pulmonary 1/3 of acute pancreatitis patients have pulmonary changes secondary to superior spread of pancreatic changes secondary to superior spread of pancreatic inflammation to diaphragm and lung bases inflammation to diaphragm and lung bases

• Findings of Acute Pancreatitis Findings of Acute Pancreatitis on Plain Chest Film:on Plain Chest Film:– pleural effusionspleural effusions (seen on 10% of (seen on 10% of

chest films)chest films)– basal atelectasisbasal atelectasis– pulmonary infiltratespulmonary infiltrates– elevated diaphragmelevated diaphragm– Acute Respiratory Distress Acute Respiratory Distress

SyndromeSyndrome Gore and Levine, Textbook of Gastrointestinal Radiology

Colon cut-off signColon cut-off sign

UltrasoundUltrasound• IndicationsIndications

– Good screening test in mild disease, suspected biliary Good screening test in mild disease, suspected biliary pancreatitis, and thin patients lacking fat planes for good CT pancreatitis, and thin patients lacking fat planes for good CT evaluationevaluation

• UsesUses– Exclude a diagnosis of gallstonesExclude a diagnosis of gallstones– Follow up of pseudocystsFollow up of pseudocysts– Doppler of cystic masses to rule out pseudoaneurysmDoppler of cystic masses to rule out pseudoaneurysm

• Major LimitationsMajor Limitations– Bowel gas Bowel gas – US cannot specifically reveal areas of necrosis US cannot specifically reveal areas of necrosis

Pictorial Pictorial reviewreview

Color doppler roleColor doppler role

Computed TomographyComputed Tomography

““CT is the premier imaging test in the diagnosis CT is the premier imaging test in the diagnosis and management of patients with acute and management of patients with acute pancreatitis. It visualizes the gland, the pancreatitis. It visualizes the gland, the retroperitoneum, the abdominal ligaments, the retroperitoneum, the abdominal ligaments, the mesenteries, and the omenta in their entirety.”mesenteries, and the omenta in their entirety.”

Think stepwizeThink stepwize

Patent Airways surrounded by collapsed alveolar air spaces

Lower chest CT: ConsolidationLower chest CT: Consolidation

Bilateral fluid accumulation in dependent lung regions

Chest CT: Pleural EffusionChest CT: Pleural Effusion

ROI: 5 HU (simple fluid)

Pancreas and Anterior Pararenal Pancreas and Anterior Pararenal SpaceSpace

Bilateral renal halo signBilateral renal halo sign• The halo appears as The halo appears as

ground-glass ground-glass attenuation on imaging, attenuation on imaging, due to enhancement of due to enhancement of the perirenal fat from the perirenal fat from the retroperitoneal the retroperitoneal collection of pancreatic collection of pancreatic exudates. Bilateral exudates. Bilateral perirenal fluid perirenal fluid collections are rarecollections are rare and and suggest pancreatitis.suggest pancreatitis.

Pseudocyst in Lesser Sac or Gastric WallPseudocyst in Lesser Sac or Gastric Wall

ROI:

•12 HU (simple fluid)

•69mm x 36mm

Evaluation for Pancreatic NecrosisEvaluation for Pancreatic Necrosis

Focal areas of necrosis show enhancement of less than 30 HU in early arterial phase

Due to high attenuation exudates, presence of pancreatic necrosis cannot be assessed unless the gland is imaged during late arterial-early portal venous phase of rapid bolus intravenous injection of contrast patchy areas of absence of enhancement, fragmentation, and liquefaction necrosis can be seen.

Extensive pancreatic Extensive pancreatic necrosisnecrosis

Normal BowelWall Edematous,

Inflamed Bowel Wall

Inflamed Fat

Normal Fat

Inflammation Spreads to the Transverse ColonInflammation Spreads to the Transverse Colon

Splenic Vein thrombosisSplenic Vein thrombosis

Splenic vein thrombosis occurs in 2% to 4% of patients with chronic pancreatitis. This event leads to isolated gastric varices with resulting gastrointestinal hemorrhage.

Fluid CollectionsFluid Collections

Course:Course:Superolateral to Superolateral to the region of the the region of the lesser sac, lesser sac, becoming becoming contiguous with contiguous with the greater the greater curvature of the curvature of the stomachstomach

Structure:Structure:ill-defined, with ill-defined, with indistinct indistinct marginsmargins

Image courtesy Dr. Anne Kim

ROI: 16 HU (simple fluid)

Pancreatic AscitesPancreatic Ascites

Dependent fluid collection between liver and diaphragm

ROI: 14 HU

Traditional CT severity Traditional CT severity indexindex

Modified CT severity index-Modified CT severity index-easier wayeasier way

Prognostic value of CTSIPrognostic value of CTSI

I-Pancreatic cancer I-Pancreatic cancer presenting as acute presenting as acute

pancreatitispancreatitis

II-Hemorrhagic PancreatitisII-Hemorrhagic Pancreatitis

• RareRare• Noted clinically by ↓ in hematocritNoted clinically by ↓ in hematocrit

CT scan demonstrates hemorrhagic pancreatitis as a heterogeneous mass in the area of the pancreatic bed (*). Arrow indicates active extravasation (hemorrhage).

70 year-old woman with hemorrhagic pancreatitis

III-Autoimmune III-Autoimmune pancreatitispancreatitis

• Focal or diffuse Focal or diffuse enlargementenlargement

• Delayed enhancement.Delayed enhancement.• Capsule like rim.Capsule like rim.

in 1995 researchers described a form of pancreatitis associated with autoimmune manifestations. Today it's known that about 5-6 percent of all cases of chronic pancreatitis are autoimmune in nature.