Differentiation Of Tumor-bearing From Benign Lymph Nodes With SPIO-enhanced MR Imaging

Differentiation of Tumor-bearing from Benign Lymph Nodes with SPIO-enhanced MR Imaging Abstract Purpose: The reactive hyperplasia and tumor-bearing lymph node models in New Zealand White Rabbits were developed to investigate the potential value of superparamagnetic iron oxide particles (SPIO) in MR imaging to differentiate metastatic from benign lymph nodes. Materials and Methods: 1 .. 18 female New Zealand White Rabbits were divided into three groups at random: normal, reactive hyperplasia and tumor-bearing group. 2~ For the signal-time course study,four sequences of MR images(T1WI, PDWI,T2WI,T2*WI) were obtained before and lhr to 48hr after subcutaneous administration of SPIO at a dose of 10 pmol Fe at the unilateral hind foot,and the signal intensity was measured respectively on four sequences of images while the size of popliteal lymph node was measured only on T1W1. 3~ Reactively hyperplastic lymph node model was developed in 6 rabbits by intramuscular injection of egg-yolk emulsion(EYE) into the lateral upper hind limb,and tumor-bearing lymph node model was developed in another six rabbits by intramuscular injection of VX2 tumor suspension into the lateral upper hind limb. 4~ Four sequences of MR images(TIWI,PDWI,T2WI,T2*WI) of the popliteal lymph nodes of 6 VX2 carcinoma-bearing rabbits and 6 reactively ?? hyperplastic rabbits were obtained before and 12 hr after subcutaneous administration of SPIO at a dose of 10 ~tmo1 Fe at the unilateral hind foot, and the SI was measured respectively on four sequences of images while the size of popliteal lymph node was measured only on TIWI, 5~ After SPIO-enhanced MR imaging, the popliteal lymph nodes were resected, the size of which was measured, and then were fixed individually in formalin and processed for the pathological study.The pathological findings were analyzed and correlated with MIRI features. Results: I.. The reactive hyperplasia and tumor-bearing lymph node models in New Zealand White Rabbits were successfully induced respectively. 2~ On unenhanced images,the SI of the tumor-free and metastatic popliteal lymph nodes didn抰 differ significantly; and the size of reactive hyperplasia and metastatic popliteal lymph nodes did not differ significantly too,but each was larger than that of normal popliteal lymph nodes. 3.. After administration of SPIO,the SI of the normal popliteal lymph node reduced significantly at Ihr, and the maximal reduction of SI occurred at l2hr,and the SI reduced by 49%.. 59%.. 78% and 89% even at 48hr with TiWI.. PDWI.. T2WI.. T2*WI sequences respectively. 4.. On enhanced images, the SI decreased significantly in the reactive hyperplasia popliteal lymph nodes;while the SI of the tumor-replaced lymph nodes remained unchanged. 5.. Pathological findings showed that the reactive hyperplasia lymph ?棗 nodes remained normal structure and uptook SPIO as well as normal lymph nodes.however,the structure of the metastatic lymph nodes...