Strengths, weaknesses, opportunities, and threat analysis of dual-energy CT in head and neck imaging.

Technological development of dual-energy computed tomography (DECT) can play an important role in head and neck area. Multiple innovative applications have evolved, optimizing images, achieving metallic artifact reduction, differentiating materials with better primary tumor delineation, thyroid cartilage and bone invasion. Furthermore, quantification algorithms allow measuring iodine concentration, reflecting the blood supply of a lesion indirectly. DECT enables acquiring images with lower radiation doses and iodine intravenous contrast load to obtain the same CT values.. However, DECT uses ionizing radiation, which does not occur with MRI, and requires long post-processing times. Artifacts on iodine maps may be a potential source of pseudolesions. Besides, photon-counting CT scanners are a promising technique that may displace some DECT advantages. A review analyzing the current status of DECT applied to head and neck imaging from the scope of strengths, weaknesses, opportunities, and threatsanalysis would be very interesting to facilitate a realistic, fact-based, data-driven look of this technique.

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.

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, 130kV, tin filter and iterative reconstruction). Images and radiation doses were compared to 36 patients (group 2) acquired in a 16-MDCT (120kV 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±0.04mSv for the 32-MDCT and 1.25±0.30mSv 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±0.04mSv).

[Valuation of automatized ASPECTS as an artificial intelligence tool in daily clinical]. / Valoración del ASPECTS automatizado como herramienta de inteligencia artificial en la práctica clínica diaria.

AIMS: To evaluate an automated ASPECTS (ASPECTS-a) software against two radiologists' reading of CT scans requested from the Emergency Department. Describe the most frequent failures of the ASPECTS-a. MATERIAL AND METHODS: All the cranial CT Scans requested by the Emergency Department in one month were collected. The following data were recorded: age, sex, the reason for requesting the study, and imaging findings. A program was used that provides an ASPECTS score automatically. Subsequently, 2 radiologists independently reviewed all of the studies and provided the visual ASPECTS (ASPECTS-v). In case of discrepancy, a new reading was made by consensus. RESULTS: A total of 295 brain CT scans (45.1% male) with a mean age of 65 ± 20.0 years were included. 91.8% were interpreted as ASPECTS-v 10 in both cerebral hemispheres by both readers. ASPECTS-a scored 45% with ASPECTS 10 in both cerebral hemispheres. In 152 (51.5%) the ASPECTS-a and the ASPECTS-v did not coincide. The causes of the discrepancy were mainly due to segmentation errors (usually due to asymmetric atrophies). Most of the segmentation errors were located in the head of the caudate nucleus, observed in 60 studies. CONCLUSIONS: ASPECTS-a is a powerful and helpful tool, but human supervision is always necessary, particularly in groups of patients with pre-existing brain changes.

TITLE: Valoración del ASPECTS automatizado como herramienta de inteligencia artificial en la práctica clínica diaria.Objetivos. Evaluar un software del Alberta Stroke Program Early CT Score (ASPECTS) automatizado (ASPECTS-a) frente a la lectura de dos radiólogos en las tomografías computarizadas (TC) solicitadas desde el servicio de urgencias. Describir los fallos más frecuentes del ASPECTS-a. Material y métodos. Se recogieron las TC cerebrales solicitadas por el servicio de urgencias en el período de un mes. Se registraron los siguientes datos: edad, sexo, motivo de solicitud del estudio y hallazgos en la prueba de imagen. Se utilizó un programa que proporciona una puntuación del ASPECTS automáticamente. Posteriormente, dos radiólogos examinaron de forma independiente todos los estudios y realizaron un ASPECTS visual (ASPECTS-v). En caso de discrepancia, se hizo una nueva lectura en consenso. Se compararon los resultados del ASPECTS-a con el ASPECTS-v. Resultados. Se realizaron un total de 295 TC cerebrales urgentes con una edad media de 65 ± 20 años. El 91,8% lo interpretaron los dos lectores como ASPECTS 10 en ambos hemisferios cerebrales. El ASPECTS-a puntuó el 45% con ASPECTS 10 en ambos hemisferios cerebrales. En 152 (51,5%), el ASPECTS-a y el ASPECTS-v no coincidieron. Las causas de la discrepancia fueron fundamentalmente por errores en la segmentación (generalmente por atrofias asimétricas). La mayor parte de los errores en la segmentación se localizaban en la cabeza del núcleo caudado, lo que se observó en 60 estudios. Conclusiones. El ASPECTS-a es una herramienta potente y de gran ayuda, pero siempre es necesaria una supervisión humana, particularmente en grupos de pacientes con cambios cerebrales preexistentes.

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. / La tomografía computarizada de peñascos con dosis ultrabaja, utilizando filtro de estaño, detectores de alta resolución y reconstrucción iterativa, permite una adecuada valoración de las estructuras del peñasco.

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).