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ECR 2018 / C-1576
Overview of CT evaluation in acute appendicitis: an illustrated semiological guide
Congress: ECR 2018
Poster No.: C-1576
Type: Educational Exhibit
Keywords: Inflammation, Education and training, Acute, Technical aspects, Structured reporting, Education, CT-Angiography, CT, Gastrointestinal tract, Emergency, Abdomen, CT-Colonography
Authors: M. E. Ispas, R. Dumitru, I. G. Lupescu; Bucharest/RO
DOI:10.1594/ecr2018/C-1576

Findings and procedure details

CT technique

 

Our most common technique is scanning between the diaphragm to the pubic symphysis, using both intravenous and oral administration of contrast (on a 16 or 64 slice MDCT). Oral contrast was preferred and administered depending on the clinical status of the patient. The CT protocols are listed below:

 

  • NECT - 1000 ml of oral contrast (positive or negative) was administered 1 hour prior to the examination (5 mm collimation, pitch = 1.0, 120 kV, 180 mAs)
  • CECT – injection of 1.5 ml/kg of non iodine based contrast media, 350-370 mgI/ml, with a power injector flow of 3 mL/s, bolus tracking in the abdominal abdominal aorta near the celiac trunk origin threshold of 120 UH (5 mm collimation, pitch = 1.0, 120 kV, 180 mAs)

-        Arterial phase  - 30-35 s after the onset of injection

-        Portal phase – 70-90 s after the onset of injection

  • Low dose NECT – 1000 ml of oral contrast (positive or negative) was administered 1 hour prior to the examination (5 mm collimation, pitch = 1.25, 120 kV, 30 mAs)

 

LDCT= 1,2 ± 0,2 mSv  vs Standard CT= 7.2±0.6 mSv

 

 

CT findings

 

1.    CT CRIERIA for acute appendicitis

        Table 5. Appendicular inflammatory signs [2]

 

Interpretation

CT findings

Reccommendation

Excludes AA

<6 mm, > 6 mm gas filled

Other causes or RLQ pain

Possbile AA

6-10 mm without other CT signs

Observation

Probable AA

6-10 mm + wall thickening

Surgery if symtpomatic

Definite AA

>10 mm or 6-10 mm + wall thickening + fat stranding

Surgery if symptomatic

Additional signs: wall thickening or hyperenhacement, mural stratification, intramural gas, appendicolith

 

 

Fig. 1: Appendicular signs. CECT portal phase (a) sagital MPR: appendicular thickening (arrow), (b) coronal MPR: periappendicular fat stranding (arrow), (c) axial: enhancement of the appendiceal wall (arrow)
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

Fig. 2: Appendicular signs: CECT portal phase (a): mural tristratification of the appendix (arrow) and NECT (b): appendicolith (arrow) associated with fat stranding and peritoneal free air (dashed arrow), suggestive of perforated appendicitis
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

                              Table 6. Cecal inflammatory signs [2], [24]

 

Cecal apical thickening

Inflammatory parietal thickening of the cecal apex

Arrowhead sign

Thickening of the appendiceal orifice leading to an obstruction of the contrast material in the cecal lumen, assuming an arrowhead configuration pointing at the appendix

Cecal bar sign

The apperance of an inflammatory soft tissue at the base of the appendix, separating it from the contrast filled cecum

 

Fig. 3: Cecal signs. CECT portal phase, positive oral contrast (a) axial- focal cecal thickening secondary to the local inflammatory process (arrow), (b) axial - arrowhead sign: the enteric contrast material in the cecal lumen points to the appendix, assuming an “arrowhead” configuration (arrow), (c) coronal MPR – cecal bar sign: separation of the contrast-filled cecum from the appendix by an inflammatory soft tissue band (circle)
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

2.       COMPLICATIONS

 

 

CT findings: defect in the enhancing appendiceal wall associated with extraluminal air and appendicolith

 

Fig. 4: Complicated appendicitis with perforation and abscess. CECT portal phase (a) coronal MPR, (b) coronal MIP and NECT axial (c) show an important inflammatory process of the right lower quadrant with fat stranding (*), appendicolith (dashed arrow), peritoneal free air (arrow) and periappendicular abscess (arrowhead).
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

CT findings: loculated rim-enhancing fluid collection 

 

Fig. 5: Complicated appendicitis with abscess. CECT portal phase, illustrates an appendicular thickening (arrowhead) and extraluminal appendicolith (dashed arrow), circumscribed by a large abscess (arrow)
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

CT findings: thickening and enhancement of the peritoneum associated with ascites 

 

Fig. 6: Complicated appendicitis with peritonitis and abscess. CECT arterial phase axial (a) and portal phase coronal MIP (b) show a large fluid collection containing gas (arrow), associated with focal thickening of the RLQ peritoneum (arrowhead) and periappendicular fat stranding (*)
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania
  • GANGRENOUS APPENDICITIS  Fig. 7

CT findings: patchy areas of nonperfusion of the appendiceal wall, pneumatosis 

 

Fig. 7: Gangrenous appendicitis. CECT portal phase (a,b,c) show an enlarged appendix with patchy parietal areas of non-perfusion (arrow) complicated with a periappendicular abscess (*) with tendency to form a cutaneous fistula (dashed arrow), suggestive of a gangrenous appendicitis, confirmed intraoperatively
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

3.            DIFFERENTIAL DIAGNOSIS

       

  • MESENTERIC LYMPHADENITIS Fig. 8

 CT findings: enlarged lymphadenopathy with normal appendix 

 

Fig. 8: Mesenteric lymphadenitis. Patient with RLQ pain and negative ultrasound. CECT portal phase (a) coronal MPR and axial (b) show a few periappendicular inflammatory lymph nodes (arrows) suggestive of mesenteric lymphadenitis, the most common pathology found in negative appendectomy
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania
  • CECAL DIVERTICULITIS  Fig. 9

CT findings: inflammed diverticula with normal appendix 

 

Fig. 9: Cecal diverticulitis. Patient with acute RLQ pain and known sigmoid diverticulosis. CECT arterial phase (a,b) show additional cecal diverticula (arrow) with inflammatory fat stranding (*) and normal appendix (arrowhead), suggestive of cecal diverticulitis , otherwise a rare cause of RLQ pain
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

CT findings: fat-attenuation mass with hyperattenuating rim 

 

Fig. 10: Epiploic appendagitis. Patient with acute RLQ and negative ultrasound. CECT portal phase (axial) shows a small fat-attenutation mass with hyperattenuating rim (long arrow), infiltration of mesenteric fat (*) and focal thickening of the surrounding parietal peritoneum (small arrow), suggestive of epiploic appendagitis
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

CT findings: well-circumscribed region of inflammed omental fat with perilesional inflammatory changes

 

Fig. 11: Omental infarction. Young patient with RLQ pain for 3 days and recent subfebrile rise in temperature. CECT arterial phase axial (a) and portal phase coronal MPR (b) illustrate a well circumscribed region of inflammed omental fat with haziness of inflammatory stranding (arrow), intraoperatively diagnosed as omental infarction
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

CT findings: proeminent circumferential wall thickening of the terminal ileum and right colon

 

Fig. 12: Crohn's disease. Patient with daily watery stools and abdominal cramps, worsened in the last 24 hours. CECT portal phase (a) axial and (b) coronal MPR show a circumferential wall thickening of the terminal ileum (long arrow), parietal stratification - “target sign” (arrowhead) and hypervascular appearance of the mesentery - ”comb sign” (*), all signs suggestive of active Crohn's disease
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

CT findings: thickened appendix with no periappendicular inflammatory abnormalities 

 

Fig. 13: Appendiceal carcinoma. 76 years old patient with weight loss and hematochezia. NECT coronal MPR (a), CECT arterial and portal phase coronal MIP (b,c) show a thickened appendix (dash arrow) associated with large appendicolith (long arrow) and thickening of the cecum (arrowhead), but with no periappendicular inflammatory changes, rising the suspicion of a tumoral cause (confirmed intraoperatively)
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania
  •   APPENDICEAL MUCOCELE  Fig. 14

 

CT findings: well-capsulated cystic RLQ mass 

 

Fig. 14: Appendiceal mucocele. Patient with long-standing RLQ pain. CECT portal phase 10 mm MPR (a) and axial (b) show a well-capsulated cystic mass in the pericecal region without periappendiceal inflammation (long arrow), suggestive of appendiceal mucocele
References: Department of Radiology, Medical Imaging and Interventional Radiology, Fundeni Clinical Institute, Bucharest, Romania

 

 

4.             IMAGING REPORT

 

The imaging report must contain all the findings summarised in table 7.

                           

                 Table 7. Structured imaging report of acute appendicitis

 

Clinical data/ Antecendents

Other prior imaging methods 

CT tehnique

CT findings

 

 

1.      Diameter

2.      Wall thickeness

3.      Periappendiceal strandings/fluid/abscess

4.      Adjacent bowel wall thickening

5.     Appendicolith

Other abdominal findings (incidental, anatomical variants)

Conclusions

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