The illustration left shows the results of a study comparing Ferrotran-enhanced MRI lymphangiography (MRL) with 11CCholine PET–CT for detection of lymph node metastases. The size of the detected metastatic lymph nodes is shown on the X-axis and the number of detected nodes on the Y-axis. It is immediately obvious that Choline PET–CT is markedly inferior to MRL for detecting metastatic lymph nodes smaller than 8 mm.
Notably, up to 83% of all metastatic lymph nodes in prostate cancer patients are smaller than 8 mm, and approximately 50% of these small nodes are less than 3 mm in diameter. [Birkhauser, Eur Urol 2013; Fortuin, Eur Urol 2013].