Article Figures & Data
Figures
- Fig 1.
A and B, The relative frequencies of scores 1–5 are shown for the neuroradiologists (A) and the otologists (B) and for high-dose and low-dose CT. C, The pooled insufficient scores are shown for the neuroradiologists and the otologists for high-dose versus low-dose CT.
- Fig 2.
Axial CT section of the right temporal bone obtained with a CTDIvol of 63 mGy (A) (14-month-old patient; DLP, 223 mGy cm; estimated Deff, 1.4 mSv) and with the low-dose protocol (B) (16-month-old child; CTDIvol, 10.8 mGy; DLP, 46.9 mGy cm; estimated Deff, 0.35 mSv). Critical structures like the modiolus and the thin bony lamella separating the internal auditory canal from the cochlea (1) and the spiral osseous lamina (2) are delineated well despite the higher image noise.
- Fig 3.
The same patients as in Fig 2. Oblique axial image, reformatted in the stapes main plane, a high-dose scan (A) versus a low-dose scan (B). The posterior stapes crus (1) and the incudostapedial articulation (2) are identifiable on both scans.
Tables
- Table 1:
Synopsis of the 23 anatomic structures reviewed and the respective primary criteria for image quality assessment
Structure/Condition Review Criteria Cochlea Normal contour, 2.5 turns Cochlear patency Ability to discern intracochlear ossifications Spiral osseous lamina Presence, integrity Modiolus Presence, integrity Labyrinth Contour, density Vestibular aqueduct Contour, density Cochlear aqueduct Contour, density Cochlear nerve canal Presence Bony lamella at auditory canal fundus Presence, integrity of bony lamella separating the internal auditory canal from the cochlea Internal auditory canal Contour Facial nerve canal, cochlear segment Contour, course Facial nerve canal, tympanic segment Contour, course Facial nerve canal, mastoid segment Contour, course Middle ear cavity Aeration Malleus Presence of all parts Incus Presence of all parts Stapes Presence of all parts Round window Presence, aperture Round window niche Borders, aeration Oval window Presence, borders, footplate position Internal carotid artery canal Borders, osseous wall dehiscence Jugular foramen Borders, osseous wall dehiscence Mastoid Bony borders, aeration - Table 2:
Mean effective doses (millisievert) for 3 age groups when scanned with local low- and high-dose protocols in comparison with literature-derived calculated effective doses and literature-derived effective doses
Age Low-Dose Protocol High-Dose Protocol Swartz et al 20098a Thomas et al 20089b Lutz et al 20075b CTDI DLP Deff CTDI DLP Deff CTDI kV mAs Deff kV mAs Deff kV mAs Deff 1 year old 8.8 40 0.3 63 285 1.8 34 120 150 0.9–1 120 200 2.6 – – – 5 year old 10.8 49 0.25 63 288 1.4 45 120 200 0.97–1.1 120 200 1.7 – – – Adult – – – – – – – 120 320 1.2–1.3 – – – 120 140 0.3 -
a Indicates literature derived calculated effective doses.
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b – indicates literature-derived effective doses.
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When available, CTDI (milligray), DLP (milligray × centimeter), and kilovolt/milliampere-second are shown also for literature-derived protocols.
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