CTSS and neoplasm: Margin probe (radiofrequency spectroscopy), Clear Edge (bioimpedance spectroscopy) and several near infrared spectroscopy (NIRS) devices applicable for indocyanine (ICG)-based tumor detection are already clinically approved [19,20], whereas the first clinical studies have been performed with intelligent knife (iKnife, rapid evaporative ionization mass spectrometry) [36], MassSpecPen (mass spectrometry of water droplets that have been brought into contact with the tissue) [37] and Lumicell (imaging of cathepsin-activatable fluorescent dye) [38].