⁶⁴Cu-/¹⁷⁷Lu-Cetuximab Theranostic Pair: May the Single ⁶⁴Cu-Cetuximab Diagnostic Scan Be Acquired at Any Time After...

Two independent equations were recently proposed for estimating ¹⁷⁷Lu-cetuximab cumulative activity, in a preclinical situation, from an initial ⁶⁴Cu-cetuximab diagnostic scan acquired at peak time of decay-uncorrected (t_peak-uncorr) or decay-corrected (t_peak-corr) time-activity curve of trapped ⁶⁴Cu-cetuximab, respectively. The standard uptake ratio (SUR) measured at t_peak-uncorr or t_peak-corr turned out to be a key metric in each equation, respectively. However, acquiring the diagnostic scan at t_peak-uncorr or t_peak-corr might be a limitation of the proposed method. Therefore, in an attempt to overcome this limitation, this note aims at theoretically investigating whether SUR(t_peak-uncorr) and/or SUR(t_peak-corr) could be derived from a diagnostic scan acquired at any time postinjection.