USA Online.pngSample Teaching Cases

Gastrointestinal Imaging

The following cases use radiography, fluoroscopy, CT and MRI to demonstrate gastrointestinal disease. Nuclear radiology and ultrasonography teaching cases are included in teaching case sections dedicated to those modalities.

Case GI.1

Case GI 1.png

Questions

1. What pathophysiology distinguishes a mechanical obstruction from a generalized adynamic ileus? Which is demonstrated in this case?

2. What is the differential diagnosis for mechanical obstruction?  Generalized adynamic ileus?

Answer Arrow.png


Case GI.2

CaseGI6.pngQuestions

1. In an adult, what is the least common location for this occurrence?

  1. Stomach
  2. Duodenum
  3. Jejunum
  4. Ileum
  5. Colon

2. Which of the following is the least likely explanation for this finding in an adult?

  1. Intestinal lymphoma
  2. Inverted Meckel diverticulum
  3. Iodiopathic
  4. Lipoma
  5. Pedunculated polyp

3. Upon diagnosis, what is the step?

  1. Air/contrast enema
  2. Embolic therapy
  3. Endoscopy
  4. Surgery
  5. Watchful waiting

Answer Arrow.png


Case GI.3

Case GI 2.png

Questions

1. What anatomic boundary is used in the TMN staging of this neoplasm?

  1. Mesorectal fascia
  2. Muscularis propria
  3. Perirectal fat
  4. Submucosa

2. What T-stage is this patient?

  1. T1
  2. T2
  3. T3
  4. T4

Answer Arrow.png


Case GI.4

Case GI 3.png

Questions

1. What are the most common etiologies for the demonstrated findings?

2. In the patient over 40 years of age whose initial presentation is unexplained, what would be the next appropriate study? Why?

3. According to the Revised Atlanta Classification system, what terms would be used to describe these fluid collections if the presentation were of less than 4 weeks duration? If greater than 4 weeks duration?

Answer Arrow.png


Case GI.5

CaseGI7b2.png

History

The patient is a 41-year-old male who presented with 8 weeks of non-radiating midepigastric abdominal pain. Past medical history includes hepatitis C secondary to IV drug abuse.

Questions

1. What clinical and/or laboratory information would be helpful in this case?

2. What therapeutic intervention(s) could be performed?

3. What is the differential diagnosis for these fluid collections?

Answer Arrow.png


Case GI.6

CaseGI7c.pngQuestions

1. What is the "double duct" sign?

2. What is the differential for the "double duct" sign?

Answer Arrow.png

Red Border.png

Answers

Case GI.1

Case GI 1.png

Diagnosis

Mechanical obstruction of the distal small bowel due to adhesions

Findings

Abdomen radiograph demonstrates multiple loops of dilated small bowel with normal caliber valvulae conniventes. In addition, multiple surgical clips and calcific atherosclerotic plaque in the aorta are seen.

Answers

1. What pathophysiology distinguishes a mechanical obstruction from a generalized adynamic ileus? Which is demonstrated in this case?

Mechanical obstruction is due to a pathologic process that physically blocks the forward movement of intraluminal contents, but the bowel has normal function including normal peristalsis. In mechanical obstruction, dilatation of the bowel is seen proximal to the location of the obstruction with collapse of the distal bowel, creating a transition point.

Conversely, an adynamic ileus is due to diffuse abnormal functioning bowel, often with atony and hypokinetic peristalsis. An adynamic ileus is a diffuse process affecting both small bowel and colon to varying degrees, demonstrating normal caliber bowel and wall thickness with multiple non-physiologic air-fluid levels. Physiologic air-fluid levels are seen in the stomach and cecum with a few air-fluid levels in the small bowel. More than three air-fluid levels in the small bowel or any air-fluid levels in the transverse or descending colon should be evaluated.

This case demonstrates mechanical obstruction of the distal small bowel, which was due to adhesions. The radiologist can guide the management of a mechanical obstruction by localizing the transition point.

2. What is the differential diagnosis for mechanical obstruction? Generalized adynamic ileus?

Mechanical obstruction is most commonly due to adhesions, but can be seen in patients with hernias, intussusception, volvulus, or tumors. An adynamic ileus is a frequent postoperative finding within 3 days of surgery. Other considerations include inflammation, infection, infarction, opioids, antacids, altered electrolytes, trauma, Hirschsprung disease (neonates), and Ogilvie syndrome. 

Next Arrow.png


Case GI.2

CaseGI6.png

Diagnosis

Jejunojejunal transient intussusception

Findings

Four axial contrast-enhanced CT images demonstrate a "target-appearing" segment of jejunum anterior to the left kidney.

Answers

1. In an adult, what is the least common location for this occurrence?

  1. Stomach
  2. Duodenum
  3. Jejunum
  4. Ileum
  5. Colon

2. Which of the following is the least likely explanation for this finding in an adult?

  1. Intestinal lymphoma
  2. Inverted Meckel diverticulum
  3. Iodiopathic
  4. Lipoma
  5. Pedunculated polyp

As demonstrated in this case by the “target” appearance of the jejunum anterior to the left kidney, enteroenteral intussusception (jejunojejunal, jejunoileal, ileoileal) is more common than colonic involvement in older children and adults. The stomach is the least frequently involved portion of the gastrointestinal tract. Risk increases with age; short segment intussusception may be transient, resolving spontaneously. Enteroenteral intussusception is associated with cystic fibrosis, HSP and hematologic dyscrasias. Additionally, a “lead point” should be considered, which could be a mass lesion, such as an inverted Meckel diverticulum, benign or malignant tumor (pedunculated polyps, lipomas or adenocarcinoma), or lymph node(s), or could be due to a focus of altered peristalsis. Depending on the clinical presentation, CT is most frequently used for diagnosis in an adult and identification of the lead point. Surgical reduction may be required. When diagnosis and treatment are rendered promptly, complications are rare. Complications of untreated intussusception include bowel infarction, necrosis, hemorrhage, perforation, peritonitis and sepsis. Recurrence is not infrequent.

Next Arrow.png


Case GI.3

Diagnosis

Rectal adenocarcinoma

Case GI 2.png

Findings

Magnetic resonance imaging before and after administration of intravenous contrast (Axial T2, T1, and T1 fat-sat gadolinium enhanced shown) demonstrated a 2.9 x 3.4 cm rectal mass, extending beyond the muscularis propria and mesorectal fat and through the mesorectal fascia. Several enlarged pelvic lymph nodes were identified (not shown).

Answers

1. What anatomic boundary is used in the TMN staging of this neoplasm?

  1. Mesorectal fascia
  2. Muscularis propria
  3. Perirectal fat
  4. Submucosa

The most important boundary in staging rectal cancer is the muscularis propria. The muscularis propria appears on T2 sequences as a hypointense layer between the hyperintense mucosa/submucosa layer and the hyperintense perirectal fat. Although not part of the TNM staging criteria for rectal cancer, an additional important MR imaging finding is the distance from the tumor to the mesorectal fascia, a thin hypointense layer surrounding the perirectal fat. A distance of less than 6 mm relates to high recurrence rates.

2. What T-stage is this patient?

  1. T1
  2. T2
  3. T3
  4. T4

The tumor in this patient traverses the perirectal fat and penetrates the mesorectal fascia, classifying this patient as having T4 rectal cancer. Tumor staging in rectal cancer is as follows:

  • T1: Tumor invades the submucosa, but not the muscularis propria
  • T2: Tumor invades the muscularis propria
  • T3: Tumor traverses the muscularis propria into the perirectal fat
  • T4: Tumor traverses the perirectal fat and invades the mesorectal fascia

Next Arrow.png


Case GI.4

Case GI 3.pngDiagnosis

Acute pancreatitis

Findings

Axial, contrasted CT images of the abdomen demonstrate peripancreatic fluid and inflammation.

Answers

1. What are the most common etiologies for the demonstrated findings?

Pancreatitis is commonly seen with gallstones and alcoholism.

2. In the patient over 40 years of age whose initial presentation is unexplained, what would be the next appropriate study? Why? 

In patients over 40 years of age with their initial episode of unexplained pancreatitis, contrast-enhanced CT following a pancreatic protocol should be used to exclude neoplasm.

3. According to the Revised Atlanta Classification system, what terms would be used to describe fluid collections if the presentation were of less than 4 weeks duration? If greater than 4 weeks duration? 

In interstitial edematous pancreatitis (IEP, non-necrotizing pancreatitis) of less than 4 weeks duration, fluid collections are described as sterile or infected “acute peripancreatic fluid collections,” whereas in necrotizing pancreatitis, the fluid collection could represent sterile or infected and be described as “parenchymal necrosis,” “peripancreatic necrosis,” or both. If greater than 4 weeks duration, fluid collections in IEP represent “pancreatic pseudocysts” and in necrotizing pancreatitis would represent “walled-off necrosis.” The term “pancreatic abscess” is no longer used.

Next Arrow.png


Case GI.5

CaseGI7bii.png

Diagnosis

Acute-on-chronic pancreatitis complicated by necrosis and formation of pseudocysts

History

The patient is a 41-year-old male who presented with 8 weeks of non-radiating midepigastric abdominal pain. Past medical history includes hepatitis C related to IV drug abuse.

Findings

Three contained abdominal fluid collections were identified by contrast-enhanced CT scan. The peripancreatic collection (2 arrows) measured 10.9 x 7.7 cm and 21 HU, while the subsplenic collection (1 arrow) measured 9.5 by 4.7 cm and 2 HU. A third fluid collection (not shown) was seen adjacent to the left lobe of the liver, measuring 4.7 by 4.6 cm and 11 HU.

Laboratory Data

The patient’s lipase and WBC count were elevated without a left shift, while his RBC, hemoglobin and hematocrit were decreased. The patient tested positive for Hepatitis B and C.

Answers

1. What clinical and/or laboratory information would be helpful in this case?

Imaging similarities make differentiating pseudocysts from other contained fluid collections difficult. The history of present illness is helpful when considering acute, subacute or chronic etiologies. In this case the duration of symptoms suggests a subacute to chronic etiology, and the patient denied a history of trauma. Other information to consider include fever, anemia, leukocytosis, coagulopathy, lipase, amylase, bilirubin, and liver associated enzymes.

2. What therapeutic intervention(s) could be performed?

Image-guided aspiration of the fluid collections and analysis of the fluid yields important information. Upon imaged-guided aspiration, fluid from pancreatic pseudocysts have elevated amylase, lipase, and enterokinases, but these are low in cystic tumors. Whereas carcinoembryonic antigen is often high in tumors but absent in pancreatic pseudocysts. Depending on the clinical situation, percutaneous drainage or enteric marsupialization can be used for definitive treatment of pancreatic pseudocysts. In this patient percutaneous drainage was attempted, but continued symptoms and complicated course lead to surgery with discovery of diffuse fibrosis, pancreatic necrosis, and hepatic and splenic pseudocysts. 

3. What is the differential diagnosis for these fluid collections? 

Fluid-filled collections in the mid abdomen and left upper quadrant can be due to infectious, traumatic and neoplastic causes. The differential diagnosis for multiple, contained abdominal fluid collections, include hematoma, abscess, cystic carcinoma, pseudomyxoma peritonei, enteric duplication cyst, pseudocyst, peritoneal inclusion cyst, tuberculosis, and echinococcal cyst amongst others.

Next Arrow.png


Case GI.6

CaseGI62.png

Diagnosis

Pancreatic ductal carcinoma

Findings

(A) Abdominal CT with contrast shows intrahepatic ductal dilatation (white arrows). (B) Abdominal CT with contrast shows intrahepatic ductal dilatation (white arrows) and extrahepatic ductal dilatation of the common bile duct (black arrow). (C) Abdominal CT with contrast shows intrahepatic ductal dilatation (white arrows), extrahepatic ductal dilatation of the common bile duct (black arrow), and pancreatic ductal dilatation (white arrowheads). Dilatation of the common bile duct and the hepatic duct is commonly called the “double duct sign”. (D) Abdominal CT with contrast shows an inflammatory mass (white arrows) at the pancreatic head with incorporation of the duodenum into the mass. Notice the focus of air identifying the lumen of the duodenum. In addition inflammatory changes are seen in the antropyloric region of the stomach (white arrowheads).

Answers

1. What is the "double duct" sign?

Dilatation  of the common bile and pancreatic ducts creates the "double duct" sign. The double duct sign indicates that there is obstruction of the pancreatobiliary ductal system, likely by mass effect at the head of the pancreas. 

2. What is the differential diagnosis in this case? 

Pancreatic ductal carcinoma, chronic pancreatitis, islet cell tumor, metastases, and lymphoma should be considered.

Pancreatic Ductal Carcinoma: These often present as an irregular, heterogeneous, poorly-enhancing mass with parenchymal atrophy distal to the tumor. Contiguous organ invasion into the duodenum, stomach and adjacent vessels can be seen as well as metastases in the liver, peritoneum, and regional lymph nodes. These tumors can occur in the pancreatic head (60%), body (20%), or tail (5%) or be diffuse (15%) and account for > 75% of pancreatic tumors. They are usually unresectable at time of presentation.

Chronic Pancreatitis: Chronic pancreatitis presents as focal or diffuse atrophy of the gland with a fibrotic mass in the pancreatic head and dilated main pancreatic duct. Chronic pancreatitis may be indistinguishable from cancer on imaging. Other findings in pancreatitis include:

  1. Ductal calculi
  2. Parenchymal calcification
  3. Distal CBD stricture w/ dilatation proximally
  4. Thickening of peripancreatic fascia
  5. Fat necrosis

Islet Cell Tumor: Islet cell tumors present as hypervascular primary and secondary tumors and may be functional or non-functional tumors. Ring enhancement is often seen in an insulinoma. Pancreatic ductal dilatation may not be seen.

Metastases: When metastases are suspected, the radiologist’s task is to look for primary tumors. Metastases may be hypovascular (e.g., lung, colon) or hypervascular (e.g., renal, melanoma) and rarely obstruct pancreatic and biliary ducts.

Lymphoma: Lymphoma may present as focal or diffuse glandular enlargement and rarely obstructs ducts. It can be widely disseminated in nodes.

Back Arrow.png

USA Online.png

For access to the USA Radiology Teaching Case Library and the USA Radiology eClassroom, visit our eCampus at USAonline.

USA faculty, residents, and students can obtain access by contacting Dr. McQuiston.

Email Newsletters

Connect With Us