The Use of Dual Energy CT Iodine Maps for Targeting Core Needle Viable Tissue Biopsies

Background: Dual Energy CT scanner utilize the different x-ray absorption behavior of different materials (like iodine) from concurrently high and low kVp data to acquire images available for post processing techniques.
Dual energy post processing techniques can be used to create quantitative iodine maps to reflect iodine density in each of the images, thus to differentiate vascular rich tissue from necrotic tissue and to aim the biopsy needle to the viable tissue.

Purpose: Using post-processed iodine map images of mediastinal /retroperitoneal lesions in candidate patients for core needle biopsies of the mass, and direct the biopsy needle for viable tissue. Thus, acquiring an informative tissue sample for an optimal histopathological diagnosis.

Methods: Biopsies were performed on a Dual Source scanner (SOMATOM Force, Siemens). We used the iodine maps, which were acquired using the Syngo.via software, to target the needle for tissue sampling in 4 patients with mediastinal masses and 1 patient with retroperitoneal mass. The region of interest (ROI) with iodine density values above 1.1 mg/ml were selected for biopsy, and these image slices with the selected ROI were used as a reference for guiding the needle during the biopsy sampling. Samples were sent to histopathological evaluations.

Results: Histopathological results from all samples were sufficient to give a precise histologic diagnosis. All procedures resulted without major or minor complications except one post biopsy pneumothorax.

Conclusion: Using Iodine-maps before sampling tissues, whether in the mediastinum or in other regions, could help the radiologists to direct the biopsy needle to a more viable tissue that correlates with higher iodine densities, and thus increase the samples quality for optimal histopathological diagnosis and decrease the chance to obtain necrotic tissue sample . Although the small number of cases, using iodine maps seems promising to improve future histopathological diagnosis and further investigations would be encouraged.