Ultralow-dose CT of the petrous bone using iterative reconstruction technique, tin filter and high resolution detectors allows an adequate assessment of the petrous bone structures

M Novoa Ferro; E Santos Armentia; N Silva Priegue; C Jurado Basildo; C A Sepúlveda Villegas; C Delgado Sánchez-Gracián

doi:10.1016/j.rx.2020.07.001

Ultralow-dose CT of the petrous bone using iterative reconstruction technique, tin filter and high resolution detectors allows an adequate assessment of the petrous bone structures

Radiologia (Engl Ed). 2020 Aug 20:S0033-8338(20)30094-1. doi: 10.1016/j.rx.2020.07.001. Online ahead of print.

[Article in English, Spanish]

Authors

M Novoa Ferro¹, E Santos Armentia², N Silva Priegue², C Jurado Basildo², C A Sepúlveda Villegas², C Delgado Sánchez-Gracián²

Affiliations

¹ Servicio de Radiodiagnóstico, Hospital Povisa, Vigo, Pontevedra, España. Electronic address: montse.novoa.ferro@gmail.com.
² Servicio de Radiodiagnóstico, Hospital Povisa, Vigo, Pontevedra, España.

PMID: 32829911
DOI: 10.1016/j.rx.2020.07.001

Abstract

Objectives: To assess image quality and radiation dose in computed tomography (CT) studies of the petrous bone done with a scanner using a tin filter, high-resolution detectors, and iterative reconstruction, and to compare versus in studies done with another scanner without a tin filter using filtered back projection reconstruction.

Material and methods: Thirty two patients (group 1) were acquired with an ultra-low dose CT (32-MDCT, 130 kV, tin filter and iterative reconstruction). Images and radiation doses were compared to 36 patients (group 2) acquired in a 16-MDCT (120 kV and filtered back-projection). Muscle density, bone density, and background noise were measured. Signal-to-noise ratio (SNR) was calculated. To assess image quality, two independent radiologists subjectively evaluated the visualization of the different structures of the middle and inner ear (0 = not visualized, 3 = perfectly identified and delimited). Interobserver agreement was calculated. Effective dose at different anatomical levels with the dose-length product was recorded.

Results: In the quantitative analysis, there were no significant differences in image noise between the two groups. In the qualitative analysis, a similar or slightly lower subjective score was obtained in the delimitation of different structures of the ossicular chain and cochlea in the 32-MDCT, compared to 16-MDCT, with statistically significant differences. Mean effective dose (± standard deviation) was 0.16 ± 0.04 mSv for the 32-MDCT and 1.25 ± 0.30 mSv for the 16-MDCT.

Conclusions: The use of scanners with tin filters, high-resolution detectors, and iterative reconstruction allows to obtain images with adequate quality for the evaluation of the petrous bone structures with ultralow doses of radiation (0.16±0.04 mSv).

Keywords: Alta resolución; Estaño; Filter; Filtro; High resolution; Hueso temporal; Iterativa; Iterative reconstruction; Petrous bone; Peñasco; Temporal bone; Tin.