Neutrophil-specific 99mTc-labeled anti-CD15 monoclonal antibody imaging for diagnosis of equivocal appendicitis.
We evaluated 99mTc-labeled anti-CD15 immunoglobulin M monoclonal antibody (LeuTech) for diagnosing acute appendicitis in patients with an equivocal clinical presentation. LeuTech avidly binds to circulating and sequestered human polymorphonuclear neutrophils in vivo, eliminating in vitro cell labeling and blood handling.


METHODS
We studied 49 patients to evaluate the safety and efficacy of LeuTech imaging. 99mTc-labeled LeuTech was prepared on site using a lyophilized kit, 99mTc-labeled pertechnetate, and 2 different incubation techniques, 1 at room temperature and the other at 37 degrees C. The abdomen was serially imaged for up to 3 h after the intravenous administration of 370-740 MBq 99mTc-labeled LeuTech. Scans were read as positive or negative for acute appendicitis or other intraabdominal infection. The institutional diagnosis was established by surgery, other diagnostic studies, or 1-mo clinical follow-up.


RESULTS
Scans were positive for appendicitis in all 26 patients with appendicitis, for a sensitivity of 100%, and negative for appendicitis in 19 of 23 patients without appendicitis, for a specificity of 83%. Accuracy, positive predictive value, and negative predictive value were 92%, 87%, and 100%, respectively. Results were not different between the LeuTech preparations. The rate of laparotomies with negative findings in patients who underwent surgery was 10%. The average time from injection to LeuTech visualization in the appendix for cases positive for appendicitis was 9 min. No serious adverse reactions occurred.


CONCLUSIONS
LeuTech imaging is safe, rapid, and sensitive for diagnosis of appendicitis in equivocal cases. The potential advantages of LeuTech over currently available radiopharmaceuticals for infection imaging are ease of preparation, absence of blood handling, excellent image quality, no requirement for SPECT, and rapid diagnostic uptake.
Kipper
S L
SL
Department of Radiology, University of California, San Diego, USA.
Rypins
E B
EB
Evans
D G
DG
Thakur
M L
ML
Smith
T D
TD
Rhodes
B
B
D000208:Acute Disease; D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal; D001064:Appendicitis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007553:Isotope Labeling; D016256:Lewis X Antigen / Q000276:immunology; D008297:Male; D051379:Mice; D009504:Neutrophils / Q000276:immunology; D016719:Radioimmunodetection; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D013670:Sodium Pertechnetate Tc 99m
D000911:Antibodies, Monoclonal; D016256:Lewis X Antigen; D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m