Evaluation of the Accuracy of Measurement of Lymph Node Size by Computed Tomography

Abstract

Computed tomography (CT) has now assumed a major role in the evaluation of the mediastinal lymph nodes. However several potential problems exist in the use of CT for the evaluation of mediastinal lymph nodal metastases from lung cancer; CT criteria for nodal involvement by tumor rely on nodal size. Accurate methods of measuring the size of lymph nodes have yet been established.
We investigated the size of 40 mediastinal nodes which were measured on CT by 20 independent blind observers. The mean standard deviation of nodal size was 2.9 mm (range: 1.2-8.5mm). The mean standard deviation of nodal size using the shortest dimension as indicator was smaller than that of nodal size using the largest dimension (p<0.01). Neither the site of mediastinal lymph node or the use of contrast enhanced CT images had any significant difference in the standard deviation of nodal size. However the use of contrast enhanced CT images slightly inproved the accuracy of measurement of nodal size than by the plain CT images.
In conclusion, we need to adopt the using shortest dimension of lymph nodes as an indicator and contrast enhanced CT images for diagnosis of mediastinal lymph node metastases to improve diagnostic accuracy.