Diagnostic techniques: their strengths and weaknesses.

The diagnostic techniques available for estimating tumour volume in patients are reviewed, using tumours in the lungs and lymph nodes to illustrate the advantages and disadvantages. Tumour growth in lymph nodes is very difficult to assess using lymphography but useful information has been obtained in highly selected patients. The introduction of ultrasound and CT have provided a method of assessing tumour size once it has broken out beyond the confines of the node. In general, CT appears to be the most accurate method of estimating tumour regression and growth of abdominal tumour at the present time. Physical imaging techniques have been used in various other sites for estimating tumour volume but the main advantages and disadvantages of conventional radiology, ultrasound and CT have been illustrated. Isotope scanning and thermography have not been widely used to quantify tumour volume because other techniques provide better delineation of the tumour margin which is the most important factor. However, even the most accurate methods available today are still dependent on subjective visual assessment.