In vitro imaging of magnetite particles

Purpose: To find an optimal imaging modality for the assessment of magnetite agglomerations used as the heating sources during magnetic thermoablation of tumors. Methods: 1 to 107 mg of coated (starch) magnetite particles were directly administered to an in vitro tumor model (swine lymph nodes) and investigated immediately (radiography) or after being embedded within a 4 % agar-phantom (sonography). T-1-weighted MR images (TR = 400 ms, TE = 14 ms) were acquired from lymph nodes containing 0.5 to 25 mg magnetite. Results: All investigated magnetite masses were qualitatively detectable by radiography. Sonographically, only mass agglomerations containing 107 mg magnetite were appropriately discernible. MRT images revealed distinct susceptibility artifacts. Conclusions: Based on the investigated imaging modalities, radiography is the method of choice for assessment of magnetite agglomerations using relevant dosages for magnetic thermoablation of tumors.