Introduction: We sought to compare in vivo and ex vivo spectral properties of a recurrent middle ear and mastoid cholesteatoma. Case Report: A 25-year-old male with clinically suspected recurrent cholesteatoma four years after a canal wall up mastoidectomy was consented for the study. He underwent preoperative computed tomography (CT) imaging of the temporal bone on a Photon Counting CT scanner followed by right tympanomastoidectomy with cholesteatoma removal. The cholesteatoma specimen was separated into mastoid and middle ear samples that were packed in two centrifuge tubes and placed in a phantom to scan on a dual energy computed tomography (DECT) scanner. Following post-processing, regions-of-interest (ROIs) were placed on pre- and post-operative images and iodine densities were compared. On in vivo images, iodine densities were 0.9 mg/mL in a mastoid ROI, 0.3 mg/mL in an aditus ad antrum ROI, −0.7 mg/mL in a middle ear ROI and 0 mg/mL in a right cerebellar ROI (used as reference). On ex vivo images, iodine densities were 0.1 mg/mL in both the mastoid and tympanic specimens. Conclusion: In vivo cholesteatoma iodine densities differed based on location. The mastoid iodine density was higher than ex vivo cholesteatoma iodine densities, which may reflect a combination of beam hardening artifact on in vivo images, sample rinsing before transfer to the centrifuge tubes, and different scanners used for in vivo and ex vivo images. Additional research is needed to better understand variations in in vivo and ex vivo findings to facilitate accurate dual energy spectral analysis.
Cottrell et al. (Sat,) studied this question.