MAGNETIC-RESONANCE SPECTROSCOPY DETECTS CANCER IN DRAINING LYMPH-NODES

The spread of cancer cells to draining lymph nodes is an important pro gnostic factor for many cancers and influences postoperative therapy i n patients. Histopathology is used routinely to assess if lymph nodes contain metastases. There are, however, time and resource constraints on the volume of lymph node tissue that can be examined by the patholo gist in a routine laboratory (less than 2% of each node), thus major s ampling errors are possible. Conventional histopathology also relies o n identifying aggregates of malignant cells for a positive diagnosis. Proton (H-1) magnetic resonance (MR) spectroscopy can detect chemical changes, specifically increased levels of lactate, choline, fucose and amino acids, in lymph nodes infiltrated by cancer. Increase in lactat e indicates the presence of anaerobically respiring cells, whereas cho line reports that the cells are replicating. Since MR spectroscopy can identify early infiltration by malignant cells, before cell clusters are visible under the light microscope, it detects micrometastases in lymph nodes missed histopathologically. Furthermore, MR spectroscopy e liminates sampling errors since the entire lymph node is examined.