Summary of tumor response assessment and definitions for RECIST, Choi and MASS criteria

Measurements and lesion evaluationsDiameter*1DiameterDiameter
CT attenuation (HU)CT attenuation (HU)
Marked central necrosis*2
Response criteria*3≥30% diameter decrease≥20% diameter decrease, ≥40HU decrease, or marked central necrosis≥10% diameter decrease, or ≥15% density decrease

*1: The longest diameters for non-nodal lesions and short axis for nodes were used according to RECIST1.1 [31]. This was applied to size measurement for Choi and MASS criteria in the present study.

*2: Marked central necrosis is defined as >50% of the enhancing central portion of a predominantly solid enhancing mass subjectively changing to near fluid attenuation (necrosis) after treatment [25].

*3: The sum of the diameters of all target lesions and the average of CT density measured in HU are used to assess response, comparing the values on the follow-up scan during therapy in reference to the values on the baseline pretherapy scan.