Appendicolith with Appendicitis

Appendicolith with Appendicitis

General considerations

• Also known as a fecolith, fecalith, coprolith
• Calcified deposit within the appendix
• Present in approximately 30% of children with acute appendicitis
• May be an incidental finding on an abdominal radiograph done for other purposes
• But, when associated with abdominal pain, there is a 90% probability of acute appendicitis
• Also 50% higher risk of appendiceal perforation
• Of some controversy, the finding of an appendicolith may be sufficient evidence to perform a prophylactic appendectomy in asymptomatic patients given the higher rate of perforation at the time of acute appendicitis
• One of several causes of obstruction of the appendiceal lumen leading to acute appendicitis which also include
• Lymphoid hyperplasia
• Foreign bodies
• Stricture
• Tumor
• Crohn’s disease
• For more on clinical and imaging findings of acute appendicitis, 

Imaging Findings

• The role of imaging is to confirm clinically suspected appendicitis, rule out another diagnosis or a complication of the disease

• Conventional radiography (abnormalities seen in <50%)
• Plain-film findings become more distinctive after perforation, while clinical findings subside
• Calcified, frequently laminated, appendicolith in RLQ (in 7-15%)
• It may lie higher in a retrocecal appendix
• Appendicolith in acute appendicitis means a high probability for perforation (50%), especially in children
• Appendicolith is usually 1 cm in size of larger
• Frequently laminated
• Other signs
• Localized dilatation of cecum from focal paralysis (cecal ileus)
• Small bowel obstruction pattern
• Soft-tissue mass and paucity or absence of intestinal gas in RLQ (more often with perforation and abscess)
• Extraluminal gas bubbles (usually only with perforation and abscess)
• Large pneumoperitoneum is rare because etiology of appendicitis involves obstruction of a very small lumen containing little air
• Focal increase in thickness of lateral abdominal wall
• Loss of properitoneal fat line on right side
• CT
• The imaging study of choice  (>95% accurate) is CT, or US
• Signs of acute appendicitis include
• Distended lumen
• Circumferentially thickened and enhancing wall
• Appendicolith – homogeneous or laminated calcification in up to 25% of cases
• Peri-appendicular inflammation-linear streaky densities in peri-appendicular fat
• Peri-cecal soft-tissue mass
• Abscess
• Poorly encapsulated
• Single or multiple fluid collection(s) with air
• Extraluminal contrast material
• Focal cecal wall thickening
• "Arrowhead" sign = funnel of contrast medium in cecum centering about occluded orifice of appendix

Complications

• Perforation (13-30%)

Treatment

• Appendectomy

Appendicolith with Appendicitis. Upper: Frontal close-up of right lower quadrant show a laminated stone in the region of the appendix consistent with a calcification that has formed in a viscous (white arrow). Lower: Coronal reconstruction with close-up of right lower quadrant shows a dilated appendix
with a thickened wall and surrounding infiltration of the fate (yellow arrow) containing an appendicolith (red arrow).

Annular Pancreas

Annular Pancreas

General Considerations

• Rare, congenital anomaly that may not become apparent until adult life
• Pancreas completely (or sometimes incompletely) encircles 2^nd portion of duodenum occasionally obstructing more proximal duodenum
• More commonly affects males
• Pancreas develops from two analogues
• Larger is dorsal bud which forms body and tail of gland
• Ventral bud is smaller and forms head of gland as well as parts of the hepatic duct and gallbladder
• Annular pancreas is believed to develop as a result of abnormalities in migration of the ventral bud such that the two buds join to encircle the duodenum
• Pancreatic duct from the annular portion may drain into the main pancreatic duct or directly into the duodenum

Clinical Findings

• Frequently asymptomatic
• May present either in infancy or, more commonly, 4^th-5^th decade of life
• In newborn, duodenal obstruction with bilious vomiting may be present
• May be associated with duodenal stenosis or atresia
• There is a 50% association with other congenital anomalies of involving the heart, trachea and esophagus and malrotation of the intestine
• In adult, there may be
• Upper abdominal colicky pain
• Postprandial fullness
• Vomiting
• Higher incidence of pancreatitis
• Peptic ulcers may develop

Imaging Findings

• In newborn, there may be a double bubble sign  from dilatation of the stomach and first portion of the duodenum 
• In, adult the diagnosis is usually suggested first by CT and can be confirmed with MRCP (magnetic resonance cholangiopancreatography) or ERCP (endoscopic retrograde cholangiopancreatography)
• UGI series    
• May show extrinsic compression on both lateral and medial walls of the  2^nd portion of duodenum
• CT
• May be mistaken for thickening of the duodenal wall
• On MRCP or ERCP, the duct of the annular pancreas usually originates anterior to the duodenum
  
  sweeps posteriorly and opens into the main pancreatic duct or ampulla

Differential Diagnosis

• Pancreatic divisum
• Failure of the dorsal and ventral pancreatic ducts to fuse resulting in the majority of secretions exiting via the accessory pancreatic duct of Santorini
• Pancreatic neoplasms
• Duplication cyst of the duodenum
• Duodenal atresia

Treatment

• Symptomatic newborns require surgical intervention
• Most symptomatic adults will undergo a surgical bypass of the duodenal obstruction

Complications

• Pancreatitis
• Peptic ulcer disease

Prognosis

• In newborn, except for the possible presence of other congenital anomalies, surgery is usually successful
• Surgery should be completely successful in an adult

Annular Pancreas. Three, contrast-enhanced axial CT images of the abdomen demonstrate the body and head of the pancreas (light blue arrows) completely encircling, but not obstructing, the duodenal loop (red *)

Accordion Sign

Accordion Sign

General Considerations

• The sign was originally described as alternating edematous haustral folds separated by mucosal ridges filled with oral contrast material
• Simulated appearance of an accordion
• It was first thought to be specific for severe Clostridium difficile–related colitis (pseudomembranous colitis)
• Almost all cases of pseudomembranous colitis are associated with recent antibiotic therapy
• C. difficile is the largest single cause of this sign

Clinical Findings

• C. difficile is a gram-positive anaerobic bacillus
• Can cause a spectrum of GI diseases ranging from mild diarrhea to fulminant life-threatening colitis

Imaging Findings

• The sign is due to the marked degree of colonic wall thickening caused by the pseudomembranes and edematous tissues that develop in C difficile colitis

Differential Diagnosis

• Cirrhosis with colonic edema
• Ischemic colitis

Accordion Sign. White oval highlights markedly thickened bowel wall with oral contrast trapped between haustral folds in a patient with known C difficile colitis. This is the "accordion sign."

Appendicitis

Appendicitis

• Incidence 
• 7-12% in Western world population
• Peak age
• 2nd-3rd decade

• Etiology 
• Obstruction of appendiceal lumen by
• Lymphoid hyperplasia
• Fecolith
• Foreign bodies
• Stricture
• Tumor
• Parasite
• Crohn’s disease

• Clinical findings 
• RLQ pain over appendix is a positive McBurney sign
• Leukocytosis
• Fever
• Nausea and vomiting
• Relatively higher rate of misdiagnosis in women between ages 20-40
• May have an atypical location

• Imaging Findings 
• Abdominal plain film (abnormalities seen in <50%)
• Plain-film findings become more distinctive after perforation, while clinical findings subside 

• May simulate other diseases
• Calcified, frequently laminated, appendicolith in RLQ (in 7-15%)
• Appendicolith and abdominal pain = 90% probability of acute appendicitis
• Appendicolith in acute appendicitis means a high probability for perforation
• "Cecal ileus" = local paralysis
• Small bowel obstruction pattern
• Soft-tissue mass and paucity or absence of intestinal gas in RLQ (more often with perforation)
• Extraluminal gas bubbles (again more often in perforation)
• Large pneumoperitoneum  is rare because etiology of appendicitis involves obstruction of a very small lumen
• Focal increase in thickness of lateral abdominal wall
• Loss of properitoneal fat line on right side
• BE / UGI (accuracy 50-84%):
• Failure to fill appendix with barium (normal finding in up to 35%)
• Indentation along medial wall of cecum (from edema at base of appendix / matted omentum / periappendiceal abscess)
• US (77-94% sensitive, 90% specific, 78-96% accurate)
• Useful in ovulating women (false-negative appendectomy rate in males 15%, in females 35%):
• Visualization of noncompressible appendix as a blind-ending tubular aperistaltic structure (seen only in 2% of normal adults, but in 50% of normal children)
• Target appearance of  >6 mm in total diameter on cross section (81%)
• Mural wall thickness >2 mm
• Diffuse hypoechogenicity (associated with higher frequency of perforation)
• Lumen may be distended with anechoic / hyperechoic material
• Loss of wall layers
• Visualization of appendicolith (6%)
• Localized periappendiceal fluid collection
• Prominent hyperechoic mesoappendix / pericecal fat
• Color Doppler US:
• Increased conspicuity from increase (in size + number) of vessels in and around the appendix
• Decreased resistance of arterial waveforms
• Continuous / pulsatile venous flow
• CT (87-98% sensitive, 83-97% specific, 93% accurate)
• Distended lumen
• Circumferentially thickened and enhancing wall
• Appendicolith = homogeneous / ringlike calcification (25%)
• Periappendicular inflammation-linear streaky densities in periappendicular fat
• Pericecal soft-tissue mass
• Abscess
• Poorly encapsulated
• Single or multiple fluid collection(s) with air
• Extraluminal contrast material
• Focal cecal wall thickening (80%)
• "Arrowhead" sign = funnel of contrast medium in cecum centering about occluded orifice of appendix

Yellow arrowheads point to appendicolith (upper) and appendix
with thickened and enhancing wall and peri-appendiceal stranding (lower)

• Complications
• Perforation (13-30%)

• Differential diagnosis (DDx)
• Colitis
• Diverticulitis
• Epiploic appendagitis
• Infectious enteritis
• Intussusception
• Crohn’s disease
• Mesenteric lymphadenitis
• Ovarian torsion
• Pelvic inflammatory disease

• Treatment 
• Appendectomy
• Finding of appendicolith is sufficient evidence to perform prophylactic appendectomy in asymptomatic patients (50% have perforation / abscess formation at surgery)

Achalasia

Achalasia

Definition

• Form of esophageal dysmotility characterized by loss of distal esophageal peristalsis and failure of lower esophageal sphincter relaxation 

Etiology & Pathophysiology 

• Usually idiopathic in origin
• Degeneration of neurons within the myenteric plexus of the esophageal smooth muscle
• Neuronal destruction is typically inflammatory in nature
• Histologically: lymphocytic infiltrate surrounding the plexus
• Predominantly involves the nitric-oxide producing inhibitory neurons
• Cause smooth muscle relaxation by inhibiting the acetylcholine producing excitatory neurons
• Loss of inhibitory input results in unopposed contractile stimulation and aperistalsis
• Acetylcholine producing neurons (which stimulate smooth muscle contraction) are relatively spared in this degenerative process 

Types

• Primary achalasia (idiopathic)
• Unknown cause of inflammatory neuronal degeneration
• Secondary achalasia (pseudoachalasia)
• Recognized pathologic causes of esophageal motility disorders often indistinguishable from primary achalasia
• Malignancy (especially gastric cancer)
• MEN, Type 2B
• Chagas’ disease
• Juvenile Sjögren’s
• Amyloidosis
• Chronic idiopathic intestinal
• Sarcoidosis
• Pseudo-obstruction
• Neurofibromatosis
• Eosinophilic gastroenteritis
• Fabry’s disease
• Scleroderma 

Epidemiology

• Annual incidence of 1 case per 100,000
• Men and women affected equally
• Occurs at any age
• Typically between 25-60 years of age
• Onset rare before adolescence 

Clinical Findings

• Dysphagia for solids and liquids predominate (85-95% of patients)
• Dysphagia for liquids especially should prompt evaluation for achalasia
• Difficulty belching
• Hiccups
• Weight loss
• Chest pain
• Usually secondary to failure of LES relaxation
• More common in younger patients and tends to regress
• Regurgitation of retained material in esophagus, especially upon lying down
• May lead to recurrent aspiration
• Heartburn in 40-60%
• Tend to have lower LES pressures than those without GERD
• Increased incidence of esophageal cancer
• Usually squamous cell
• Surveillance endoscopy not recommended (usually seen 15-20 years after development of achalasia) 

Imaging Findings

• Barium studies
• 95% diagnostic accuracy
• Early/Stage I
• Primary peristaltic waves absent with abnormal distal peristalsis
• Only minimal narrowing of the GE junction
• Occasionally may see nonpropulsive peristaltic waves in the esophageal body (“vigorous achalasia” secondary to tertiary waves)
• Progressive disease
• “Bird’s beak” appearance of GE junction
• Distal esophagus makes right angle before entering stomach
• Hurst phenomenon
• With the patient upright, barium builds up to a point where the hydrostatic pressure of the barium overcomes the LES pressure
• Occasional “spurt” of barium through the GE junction as it is intermittently  forced open
• Dilated, aperistaltic esophageal body; may assume a sigmoid shape
• Severe disease
• Significant esophageal body dilation with large amounts of fluid/food retention
• Entire esophagus atonic in late stages 

• Chest x-ray
• With severe disease, may readily see the large, dilated esophagus with air fluid level at the aortic arch or above
• Stomach bubble frequently absent 

• CT Scan
• Not typically used for diagnosis
• Seen as dilated luminal structure with retained debris and narrowing at level where it enters the stomach 

• Manometry
• Usually required for confirmation of diagnosis
• Elevated resting LES pressure
• Incomplete LES relaxation
• Absence of peristalsis 

• Endoscopy
• Must rule out malignancy
• Reveals dilated esophagus with normal mucosa
• Retained fluid/food
• Possible Candida infection secondary to esophageal stasis
• Endoscope should pass easily through LES with gentle pressure applied
• Unlike strictures caused by neoplasms, fibrosis etc 

Differential Diagnosis

• Reflux esophagitis with stricture
• Narrowing is usually higher than the EG junction
• Normal esophageal peristalsis
• Carcinoma
• Only minimal dilation with normal peristalsis
• Scleroderma
• Barium should empty when patient is upright
• Other associated GI abnormalities
• Chagas disease
• Not distinguishable by x-ray; history needed 

Treatment

• Medical therapy
• Nitrates, calcium channel blockers (nifedipine)
• Cause smooth muscle relaxation but with limited success
• Pneumatic dilation of the LES
• Tears muscle fibers of LES, thus weakening it
• Varying protocols regarding type and diameter of dilator, balloon inflation pressure and rate at which it is inflated, duration of inflation, and number of inflations per session
• Good short-term results, but many patients require further intervention, with successive dilations adding little benefit
• Potential complications of esophageal perforation (2-6%) and GERD
• Surgical myotomy
• LES muscle fibers cut
• Laparoscopy becoming more popular
• Good relief of symptoms in majority of patients with complication rate similar to that of dilation
• Superior method for achieving better long term results
• Debate as to whether fundoplication is necessary to prevent longstanding GERD
• Botulinum toxin injection
• Inhibits release of excitatory acetylcholine from nerve endings (thus causing lower LES pressures)
• Good short­-term results, but long term efficacy unknown

Achalasia. Upper: There is a large air-filled tubular structure that represents the dilated esophagus (white arrows). Lower: An esophagram shows a massively dilated esophagus (yellow arrows) down to the esophagogastric junction consistent with achalasia.

Air in the Biliary System Pneumobilia

Air in the Biliary System

Pneumobilia

General Considerations

• Air in the biliary tree, also known as pneumobilia
• Most frequently from the following causes
• Incompetent Sphincter of Oddi
• Recent instrumentation, as in ERCP, or surgery, as in spincterotomy
• Fistulous connection with the GI tract, as in gallstone ileus
• It is rarely due to gas-forming infection, as in cholangitis or emphysematous cholecystitis

Clinical Findings

• Usually benign or asymptomatic when caused by incompetent sphincter or surgery

Imaging Findings

• Several, air containing-tubular structures seen in the region of the hilus of the liver
• The common bile duct is frequently recognizable
• There may be other, left and right biliary radicals, filled with air
• Since air produces echogenic artifacts on ultrasound, pneumobilia is visible on US

Differential Diagnosis

• Portal venous gas
• Usually a more ominous finding than pneumobilia
• Can be differentiated by the peripheral nature of innumerable air-containing branching structures near the outer edge of the liver rather than centrally

Air in the Biliary System. Close-up of the right upper quadrant shows a tubular structure containing air (red arrow) representing the common bile duct and several air-containing biliary radicals (white arrows).