Y Zhou*, A Scott, C Lee, E Eastman, Cedars-Sinai Medical Center, Los Angeles, CA

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  Y Zhou

TU-F115-IePD-F8-5 (Tuesday, 7/12/2022) 1:15 PM - 1:45 PM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 8

Purpose: Iodine and iron load measurement accuracy using dual energy CT has been previously studied in simple phantoms. In multi-phase liver CT scans, lesions carry various iodine loads whereas the liver parenchyma is perfused with different iodine. It will be important to quantify the iodine and iron against the ground truth in a similar environment. We designed an anthropomorphic liver phantom for this purpose.

Methods: Lesions of various shapes (ellipsoidal, spherical, and lobular) with known iodine (0.5–6.3 cc with 0.42-1.47 mg/cc) and iron loads (0.78-6.3 cc with 9.79-40 mg/cc) were placed in the simulated liver. The realistically shaped liver (~16 cm in craniocaudal) with adequate x-ray attenuations was embedded in the abdomen phantom (32x25x18 cm) containing thoracic and lumbar spines. The non-contrast, arterial, and venous phases were simulated by perfusing the liver parenchyma with different iodine concentrations (0, 0.68, and 1.89 mg/cc) in three consecutive slabs (4 cm each). GE Revolution CT was used at the dual energy mode in three repeated scans with CTDIvol of 14 mGy. Material decompositions were made in iodine/water and Fe₃O₄/water pairs. Regions of interest well within each detectable lesion were used to measure the iodine and iron concentrations. Depending on the lesion size, three to five consecutive slices of 2.5 mm were utilized.

Results: In comparison with the ground truth, the measured iodine concentrations in eight lesions and in the liver parenchyma showed an error of 14.1% on average with a range from -1.9 – 33.5%. The measured iron concentrations in six lesions showed an error of 13.9% on average with a range from 8.9 – 23.2%.

Conclusion: By use of the fast-kVp switch dual energy CT, the iodine and iron concentrations were measured to the accuracy of 14% on average in the liver lesions of the anthropomorphic phantom simulating a multi-phase liver study.

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