Rationale: For clinical application, a sufficient reproducibility of 99mTc-HYNIC annexin-V quantitative uptake measurements must be demonstrated to allow a study of cell-death changes induced by chemotherapy over time and intersubject. Thus, the aim of this study was to estimate the intra-, inter-, and day-to-day reproducibility of quantitative 99mTc-HYNIC annexin-V tumor uptake values in patients suffering from head and neck carcinomas.
Methods: Thirteen (13) patients suffering from clinically suspected, histologically confirmed squamous head and neck carcinomas were prospectively included in the study. All patients were scheduled to undergo a spiral computed tomography scan and two 99mTc-HYNIC annexin-V scintigraphies within 3-5 days from each other, referred to as day 1 and day 2 of scintigraphy. The percentage of uptake of the injected dose of 99mTc-HYNIC annexin-V in tumor lesions on scintigrams divided by the tumor volume, as derived from CT, was determined twice within an interval of 2 weeks by observer 1 and once by observer 2 on day 1 of scintigraphy and once on day 2 of scintigraphy by observer 1.
Results: The mean of the difference for the intra-, inter-, and day-to-day measurements were -3.4%, 2.4%, and -6%, respectively. No systematic bias was observed for the mean of the differences for the intra-, inter-, and day-to-day measurements. The respective confidence intervals for the mean of the differences of intra-, inter-, and day-to-day variability were -8.2%-1.4%, -2.9%-7.8%, and -14.7%-2.7%.
Conclusion: The reproducibility of quantitative 99mTc-HYNIC annexin-V tumor uptake measurements using a manual method appears to be acceptable for clinical use.