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arXiv · 1910.11315

Bone Material Analogues for PET/MRI Phantoms

Dharshan Chandramohan·Peng Cao·Misung Han·Hongyu An·John J. Sunderland·Paul E. Kinahan·Richard Laforest·Thomas A. Hope·Peder E. Z. Larson
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Abstract

Purpose: To develop bone material analogues that can be used in construction of phantoms for simultaneous PET/MRI systems. Methods: Plaster was used as the basis for the bone material analogues tested in this study. It was mixed with varying concentrations of an iodinated CT contrast, a gadolinium-based MR contrast agent, and copper sulfate to modulate the attenuation properties and MRI properties (T1 and T2*). Attenuation was measured with CT and 68Ge transmission scans, and MRI properties were measured with quantitative ultrashort echo time pulse sequences. A proof-of-concept skull was created by plaster casting. Results: Undoped plaster has a 511 keV attenuation coefficient (~0.14 cm-1) similar to cortical bone (0.10-0.15 cm-1), but slightly longer T1 (~500 ms) and T2* (~1.2 ms) MR parameters compared to bone (T1 ~ 300 ms, T2* ~ 0.4 ms). Doping with the iodinated agent resulted in increased attenuation with minimal perturbation to the MR parameters. Doping with a gadolinium chelate greatly reduced T1 and T2*, resulting in extremely short T1 values when the target T2* values were reached, while the attenuation coefficient was unchanged. Doping with copper sulfate was more selective for T2* shortening and achieved comparable T1 and T2* values to bone (after 1 week of drying), while the attenuation coefficient was unchanged. Conclusions: Plaster doped with copper sulfate is a promising bone material analogue for a PET/MRI phantom, mimicking the MR properties (T1 and T2*) and 511 keV attenuation coefficient of human cortical bone.

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Dharshan Chandramohan, Peng Cao, Misung Han, Hongyu An, John J. Sunderland, Paul E. Kinahan, Richard Laforest, Thomas A. Hope, Peder E. Z. Larson. 2019-10-24. Bone Material Analogues for PET/MRI Phantoms. https://doi.org/10.1002/mp.14079

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