Noncontrast and contrast enhanced computed tomography for diagnosing acute appendicitis: A retrospective study for the usefulness

Appendicitis mimicking the CT appearance of an appendiceal mucinous neoplasm

Occasionally, radiologically diagnosed acute appendicitis is found to harbour underlying appendiceal neoplasm on post-surgical histopathology. Conversely, a situation in which radiologically, the appendix demonstrates features consistent with an underlying tumour but post-operative pathology finds no evidence of neoplastic change is rare. We describe a case of a 50-year-old man who presented with a markedly dilated "mass-like" appendix with minimal inflammatory changes on a computed tomography scan. Radiological findings were suspicious for an appendiceal neoplasm/mucocele (i.e. low-grade mucinous neoplasm). However, the post-surgical histopathological diagnosis did not concur with the radiological diagnosis and instead demonstrated findings compatible with acute appendicitis without neoplastic change. In this case report we provide a histopathological correlation and an explanation as to how this may have happened with the hope of helping radiologists avoid this pitfall in the future.

Effect of intravenous contrast for CT abdomen and pelvis on detection of urgent and non-urgent pathology: can repeat CT within 72 hours be avoided?

PURPOSE

To determine if administering IV contrast for CT abdomen and pelvis improves detection of urgent and clinically important non-urgent pathology in patients with urgent clinical symptoms compared to patients not receiving IV contrast, and in turn to determine whether repeat CT exams on the same patient within 72 h were of low diagnostic benefit if the first CT was performed with IV contrast.

METHODS

We evaluated 400 consecutive patients who had CT abdomen and pelvis (CT AP) examinations repeated within 72 h. For each patient, demographic data, reason for examination, examination time stamps, and examination technique were documented. CT AP radiology reports were reviewed and both urgent and non-urgent pathology was extracted.

RESULTS

Of 400 patients, 63% had their initial CT AP without contrast. Administration of IV contrast for the first CT AP was associated with increased detection of urgent findings compared with non-contrast CT (p = 0.004) and a contrast-enhanced CT AP following an initial non-contrast CT AP examination better characterized both urgent (p = 0.002) and non-urgent findings (p < 0.001). Adherence to ACR appropriateness criteria for IV contrast administration was associated with increased detection of urgent pathology on the first CT (p = 0.02), and the second CT was more likely to be performed with IV contrast if recommended by the radiologist reading the first CT (p = 0.0006).

CONCLUSION

In the absence of contraindications, encouraging urgent care physicians to preferentially order IV contrast-enhanced CT AP examinations in adherence with ACR appropriateness criteria may increase detection of urgent pathology and avoid short-term repeat CT AP.