OBJECTIVETo compare the diagnostic value of gadolinium diethylenetriaminepenta-acetic acid (Gd-DTPA)-enhanced MRI with ultrasmall superparamagnetic iron oxide (USPIO)-enhanced MRI in differentiating reactive hyperplastic lymph nodes from metastatic lymph nodes in rabbit models.

METHODSReactive hyperplastic cervical lymph node model was established in 18 rabbits as hyperplasia group, and tumor-bearing lymph node model was established in another 18 rabbits as tumor group. For Gd-DTPA-enhanced MRI, T1WI and T2WI were performed on 9 animals of each model, and T1WI was acquired 80 seconds after administration of Gd-DTPA. For USPIO-enhanced MRI, T1WI, T2WI and T2*WI were performed on another 9 animals of each model before and 24 hours after administration of USPIO. MRI images were analyzed and correlated with surgical specimens and pathological results.

RESULTSIn the tumor group, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of Gd-DTPA-enhanced MRI were 62.5%, 91.3%, 88.2%, 70.0% and 76.6%, respectively. The corresponding values of USPIO-enhanced MRI were 95.0%, 90.9%, 90.5%, 95.2% and 92.9%, respectively. The sensitivity and accuracy of USPIO-enhanced MRI differ significantly from those of Gd-DTPA-enhanced MRI. In the hyperplasia group, the accuracy of Gd-DTPA-enhanced MRI was 74.2%, while 87.1% for USPIO-enhanced MRI.

CONCLUSIONUSPIO-enhanced MRI has higher accuracy in diagnosing metastatic lymph nodes than Gd-DTPA-enhanced MRI.