LN-RADS, RECIST 1.1 and Node-RADS Classification in the Assessment of Lymph Nodes

Comparison of the LN-RADS, RECIST 1.1 and Node-RADS Classification in the Assessment of Lymph Nodes in MRI and CT in Relation to Histopathological Results - a Prospective, Randomised Study

The project aims to evaluate the value of the new LN-RADS scales for lymph node classification in CT and MR and to compare this method with two other methods RECIST 1.1 and Node-RADS.

The main tested system in the study is LN-RADS, the comparators are RECIST 1.1 and Node-RADS criteria.

Lymph nodes are a key diagnostic and therapeutic element in oncology. Despite the technological progress, the detection of neoplastic changes in the lymph nodes is of low effectiveness, which results from the imperfection of the criteria used. Currently, the most widely used criterion is the RECIST 1.1 guideline developed in the 1990s, according to which the lymph node dimension in the short axis with a cut-off point of 10 mm is decisive. Lymph nodes smaller than 10 mm across are considered normal. It is a criterion with a high error rate, both due to the false-negative diagnoses (with small metastases below 10 mm) and false-positive diagnoses (in the case of inflammatory lymphadenopathy).

A particular disadvantageous situation is when the metastatic nodes and their transverse dimension is less than 10 mm, because they are treated as healthy nodes and the degree of the disease advancement is underestimated. As a result, the patient is not treated properly - no complete lymphadenectomy, no radiotherapy to the area of these nodes or insufficient systemic treatment. In all cases, underestimating the stage of the neoplastic diseases increases the risk of the recurrence.

LN-RADS accounts small metastases in nodes about 3 mm in size, thus about 20% more metastatic nodes may be detected compared to RECIST 1.1 method. This means that currently, according to RECIST 1.1 rules, approx. 20% of patients have missed nodal metastases and consequently receive insufficient treatment resulting in relapse. Previous studies have shown that RECIST 1.1 shows a high level of underestimation of metastatic nodes. The Node-RADS system, as the second comparator next to RECIT 1.1, is a fairly new system moving towards the structural assessment of lymph nodes, but proposed arbitrarily, without hard evidence for its effectiveness. Despite the publication of the Node-RADS system in a medical journal, it is not validated. The Node-RADS has numerous limitations and weaknesses that reduce its value.

Inclusion Criteria:

• diagnosed or suspected cancer,
• planned lymph node biopsy or lymphadenectomy,
• planned or performed CT/MRI covering an area of the body with lymph nodes, - verified histopathologically or cytologically,
• informed consent to participate in the study.

Exclusion Criteria:

• non-diagnostic CT/MRI images of lymph nodes due to reasons such as movement artifacts, artifacts from metal elements and any other factors that do not allow for proper assessment of the nodes,
• inconclusive histopathological or cytological results, which do not allow the nodes to be classified into one of two groups - benign or malignant.