How to measure target lesion in RECIST?

To measure a target lesion in RECIST (Response Evaluation Criteria in Solid Tumors), one should take the longest diameter of the lesion as the measurement. This should be done using computed tomography (CT) or magnetic resonance imaging (MRI) scans. The measurement should be taken in the same plane and at the same level for each follow-up scan to ensure consistency. Any changes in the size of the lesion should be recorded and compared to the baseline measurement to determine the response to treatment. It is important to follow the standardized guidelines of RECIST for accurate and reliable assessment of tumor response.

RECIST Target Lesion Measurement Technique Tumor Assessment Imaging Criteria