- Non-measurable: All other lesions including small lesions (longest diameter <20 mm with conventional techniques or < 10 mm with spiral CT scan) and truly non-measurable lesions. Lesions considered to be truly non-measurable include the following: bone lesions, leptomeningeal disease, ascites, pleural/cutis/pulmonis, abdominal masses that are not confirmed and followed by imaging techniques, and cystic lesions.