Detection of acute appendicitis by technetium 99 HMPAO scanning

Area of Science:

• Nuclear Medicine
• Diagnostic Imaging
• Gastrointestinal Surgery

Background:

• Acute appendicitis diagnosis can be challenging.
• Current diagnostic methods like CT scans and ultrasound have limitations.
• Novel imaging techniques are needed to improve diagnostic accuracy.

Purpose of the Study:

• To evaluate the diagnostic utility of a Technetium 99-m Hexamethylpropyleneamineoxide (HMPAO) labeled white blood cell scan for acute appendicitis.
• To determine the sensitivity, specificity, and accuracy of this novel imaging technique.

Main Methods:

• A prospective, blinded study involving 30 patients with suspected appendicitis.
• Autologous white blood cells labeled with Tc-99 HMPAO were reinjected.
• Abdominal imaging was performed at 0.5, 2, and 4 hours postinjection.

Main Results:

• The Tc-99 HMPAO WBC scan demonstrated 81% sensitivity, 100% specificity, and 89% overall accuracy.
• A false negative rate of 19% and a false positive rate of 0% were observed.
• The scan successfully identified other intra-abdominal pathologies in patients without appendicitis.

Conclusions:

• The 4-hour Tc-99 HMPAO WBC scan is a valuable, noninvasive tool for confirming acute appendicitis.
• This imaging modality is particularly useful for ruling out appendicitis in patients with ambiguous abdominal pain.