A New Frontier in Temporal Bone Imaging: Photon-Counting Detector CT Demonstrates Superior Visualization of Critical Anatomic Structures at Reduced Radiation Dose

• Published in: American journal of neuroradiology : AJNR Vol. 43; no. 4; pp. 579 - 584
• Main Authors: Benson, J C, Rajendran, K, Lane, J I, Diehn, F E, Weber, N M, Thorne, J E, Larson, N B, Fletcher, J G, McCollough, C H, Leng, S
• Format: Journal Article
• Language: English
• Published: United States American Society of Neuroradiology 01.04.2022
• Subjects: Editor's Choice; Female; Head & Neck; Humans; Middle Aged; Phantoms, Imaging; Photons; Radiation Dosage; Temporal Bone - diagnostic imaging; Tomography, X-Ray Computed - methods
• ISSN: 0195-6108; 1936-959X
• DOI: 10.3174/ajnr.a7452

Photon-counting detector CT is a new technology with a limiting spatial resolution of ≤150 μm. In vivo comparisons between photon-counting detector CT and conventional energy-integrating detector CT are needed to determine the clinical impact of photon counting-detector CT in temporal bone imaging. Prospectively recruited patients underwent temporal bone CT examinations on an investigational photon-counting detector CT system after clinically indicated temporal bone energy-integrating detector CT. Photon-counting detector CT images were obtained at an average 31% lower dose compared with those obtained on the energy-integrating detector CT scanner. Reconstructed images were evaluated in axial, coronal, and Pöschl planes using the smallest available section thickness on each system (0.4 mm on energy-integrating detector CT; 0.2 mm on photon-counting detector CT). Two blinded neuroradiologists compared images side-by-side and scored them using a 5-point Likert scale. A post hoc reassignment of readers' scores was performed so that the scores reflected photon-counting detector CT performance relative to energy-integrating detector CT. Thirteen patients were enrolled, resulting in 26 image sets (left and right sides). The average patient age was 63.6 [SD, 13.4] years; 7 were women. Images from the photon-counting detector CT scanner were significantly preferred by the readers in all reconstructed planes ( < .001). Photon-counting detector CT was rated superior for the evaluation of all individual anatomic structures, with the oval window (4.79) and incudostapedial joint (4.75) receiving the highest scores on a Likert scale of 1-5. Temporal bone CT images obtained on a photon-counting detector CT scanner were rated as having superior spatial resolution and better critical structure visualization than those obtained on a conventional energy-integrating detector scanner, even with a substantial dose reduction.