- Measurable disease, defined as at least 1 malignant lesion that could be accurately and serially measured in at least 1 dimension and for which the greatest diameter is > or = 10 mm as measured by spiral computed tomography (CT) scan or magnetic resonance imaging (MRI), or > or = 20 mm with conventional techniques. A caliper can be used for the measurement of superficial cutaneous metastases which are > or = 10 mm.