Advances in Diagnostic Imaging in the Field of Otolaryngology Made Possible by Ultra-High Resolution CT with AiCE
Prof. Satoshi Yoshioka
The Department of Otolaryngology / Head and Neck Surgery at our hospital encompasses a broad range of highly specialized fields which require precise imaging and understanding of both macroscopic and microscopic anatomy for the evaluation of a wide variety of anatomical structures and diseases. In diagnostic imaging exams, extremely detailed morphological analysis is essential for the assessment of function and pathology. In addition, imaging must be individualized for each patient to acquire the specific information required for treatment planning.
The development of CT technology has focused on increasing the number of detector rows, achieving faster gantry rotation, and reducing the exposure dose. In 2017, the introduction of the high-resolution CT system Aquilion Precision, which features remarkably high spatial resolution, led to a true revolution in clinical practice. This report describes the clinical advances in the field of otolaryngology that have been made possible by Aquilion Precision and the Deep Learning Reconstruction technology known as Advanced intelligent Clear-IQ Engine (AiCE)*.
The development of CT technology has focused on increasing the number of detector rows, achieving faster gantry rotation, and reducing the exposure dose. In 2017, the introduction of the high-resolution CT system Aquilion Precision, which features remarkably high spatial resolution, led to a true revolution in clinical practice. This report describes the clinical advances in the field of otolaryngology that have been made possible by Aquilion Precision and the Deep Learning Reconstruction technology known as Advanced intelligent Clear-IQ Engine (AiCE)*.
* Deep Learning technology is used in the design stage of image reconstruction processing in AiCE. The CT system itself does not have self-learning capabilities.
Clinical application of Aquilion Precision
1. Paranasal sinuses
In endoscopic surgery for patients with sinusitis, a preoperative assessment of the fine anatomy is essential. Of particular note are the frontal sinuses, etc., but since the surgery is performed in close proximity to the orbit, skull base, and other vital structures, an accurate preoperative assessment of the nasal and sinus anatomy, which varies from patient to patient, is necessary.
In endoscopic surgery for patients with sinusitis, a preoperative assessment of the fine anatomy is essential. Of particular note are the frontal sinuses, etc., but since the surgery is performed in close proximity to the orbit, skull base, and other vital structures, an accurate preoperative assessment of the nasal and sinus anatomy, which varies from patient to patient, is necessary.
Aquilion Precision can clearly depict thin bony structures adjacent to retained fluid, providing essential information for surgical planning to ensure safe and effective treatment.
Figure 1 shows a patient with rapidly progressive visual impairment and visual field defects. Aquilion Precision shows a lesion in the sphenoid sinus, the narrow optic canals, bony destruction advancing toward the cranial base, and extension of the lesion into the orbital tip. The lesion was later identified as a myeloma. Subtle pathologic changes in bony structures located within soft tissues could be clearly visualized, which was of great clinical value in evaluating the morphological characteristics of the lesion.
Figure 1 shows a patient with rapidly progressive visual impairment and visual field defects. Aquilion Precision shows a lesion in the sphenoid sinus, the narrow optic canals, bony destruction advancing toward the cranial base, and extension of the lesion into the orbital tip. The lesion was later identified as a myeloma. Subtle pathologic changes in bony structures located within soft tissues could be clearly visualized, which was of great clinical value in evaluating the morphological characteristics of the lesion.
Figure 1: Myeloma, 71-year-old man
: Extension of the tumor into the orbit and skull base is depicted along with fine bony destruction
2. Tongue and mouth
The prognosis of patients with tongue cancer is strongly influenced by the presence or absence of lymph node metastasis, which frequently occurs in patients with this type of cancer. The depth of invasion has been reported to be more important than the size of the primary tumor for evaluating the probability of lymph node metastasis and assessing the patient's prognosis. This has led to the inclusion of depth of invasion in the T classification for cancer staging. Aquilion Precision is extremely useful for assessing the depth of invasion.
The prognosis of patients with tongue cancer is strongly influenced by the presence or absence of lymph node metastasis, which frequently occurs in patients with this type of cancer. The depth of invasion has been reported to be more important than the size of the primary tumor for evaluating the probability of lymph node metastasis and assessing the patient's prognosis. This has led to the inclusion of depth of invasion in the T classification for cancer staging. Aquilion Precision is extremely useful for assessing the depth of invasion.
Figure 2: Deep invasion of tongue cancer in a 75-year-old woman
In Figure 2, the lesion was judged to be T1 according to the standard T classification. However, an image acquired by Aquilion Precision (Figure 2a) showed the presence of thin but deeply extending tumor invasion. The depth of invasion was judged to be 12 mm, and tumor resection with tongue reconstruction was performed based on the CT findings strongly suggestive of deep invasion. In subsequent pathological examination, the depth of invasion was found to be 11 mm (Figures 2c and 2d), showing excellent agreement with the findings of preoperative CT examination. As demonstrated in this case, Aquilion Precision can provide extremely useful information for the preoperative assessment of tongue cancer, serving as an innovative new approach to treatment planning.
Figure 2: Deep invasion of tongue cancer in a 75-year-old woman
3. Larynx
Extremely precise positional adjustment is required when performing surgical procedures such as repositioning of the vocal folds to restore phonation, and it has been reported that Aquilion Precision is clinically useful for preoperative evaluation and surgical planning in such cases.1
Extremely precise positional adjustment is required when performing surgical procedures such as repositioning of the vocal folds to restore phonation, and it has been reported that Aquilion Precision is clinically useful for preoperative evaluation and surgical planning in such cases.1
Application of AiCE in the field of otology
AiCE is an advanced reconstruction technology in which Deep Learning is trained to reduce noise in CT images in order to perform ultra-high resolution imaging at the same dose as a normal resolution scan. As a further extension of this technology, AiCE Inner Ear was released in the fall of 2022. By employing suitable parameters for high-definition images acquired by Aquilion Precision, it is possible to obtain images with even higher quality than those acquired by conventional systems. Some examples of the clinical application of Aquilion Precision at our hospital are presented below.
1. Morphological evaluation of cholesteatoma
In surgical procedures for cholesteatoma, the lesion is removed by opening the temporal bone. And in many cases, the ossicles are removed together with the lesion, necessitating reconstruction using cartilage, bone, or artificial materials. It is therefore essential to obtain a clear understanding of the extent of destruction to critical structures caused by the cholesteatoma. Figure 3 shows a patient with a progressive cholesteatoma. Invasion into the tegmen tympani has resulted in a defect in the cranial base. The low noise images obtained using AiCE (Figure 3b) allow the subtle morphological changes in the lesion to be clearly observed, providing useful information for preoperative evaluation to assess the spread of the lesion into other important structures such as the semicircular canals.
In surgical procedures for cholesteatoma, the lesion is removed by opening the temporal bone. And in many cases, the ossicles are removed together with the lesion, necessitating reconstruction using cartilage, bone, or artificial materials. It is therefore essential to obtain a clear understanding of the extent of destruction to critical structures caused by the cholesteatoma. Figure 3 shows a patient with a progressive cholesteatoma. Invasion into the tegmen tympani has resulted in a defect in the cranial base. The low noise images obtained using AiCE (Figure 3b) allow the subtle morphological changes in the lesion to be clearly observed, providing useful information for preoperative evaluation to assess the spread of the lesion into other important structures such as the semicircular canals.
Figure 3: Progressive cholesteatomatous tympanitis in a 77-year-old man
: Invasion into the tegmen tympani, resulting in a defect ( 
) in the cranial base
* Adaptive Iterative Dose Reduction 3D
Figure 4: Hypoplasia of the auditory ossicles in a 17-month-old girl
2. Low-dose scanning in pediatric patients
Figure 4 shows images of a patient with hypoplasia of the auditory ossicles. This patient was a young child, and scanning was therefore performed with the lowest possible dose. Because the patient was scanned at a CTDIvol of 10.8 mGy, the original image (Figure 4a) has high levels of noise, but with the use of AiCE (Figure 4c), the hypoplasia and malposition of the auditory ossicles and the vestigial stapes are clearly depicted. AiCE is particularly useful for the visualization and morphological evaluation of extremely small structures when performing lowdose scans in pediatric patients, including neonates and infants.
Figure 4 shows images of a patient with hypoplasia of the auditory ossicles. This patient was a young child, and scanning was therefore performed with the lowest possible dose. Because the patient was scanned at a CTDIvol of 10.8 mGy, the original image (Figure 4a) has high levels of noise, but with the use of AiCE (Figure 4c), the hypoplasia and malposition of the auditory ossicles and the vestigial stapes are clearly depicted. AiCE is particularly useful for the visualization and morphological evaluation of extremely small structures when performing lowdose scans in pediatric patients, including neonates and infants.
Figure 4: Hypoplasia of the auditory ossicles in a 17-month-old girl
3. Evaluation of decalcification and sclerotic lesions
Otosclerosis is characterized by slowly progressive calcification in the middle ear due to chronic inflammation, which leads to impaired mobility of the auditory ossicles. Surgical removal and cleaning are performed in these patients, and AiCE is useful for precisely visualizing the extent of calcification. Otosclerosis is a progressive condition in which abnormal bone calcification occurs in areas near the oval window and membranous cochlea, interfering with the movements of the stapes. The procedure for repair of the stapes is one of the most precise microsurgical procedures in which a millimeter-scale artificial auditory ossicle is implanted in an opening created in the stapedial footplate. Aquilion Precision combined with AiCE is particularly useful for preoperative evaluation in such cases. Figure 5 shows images of two patients with abnormal decalcification that is difficult to see in the AIDR 3D image (Figure 5a) or original image (Figure 5b) is clearly depicted with reduced noise levels in the AiCE images (Figures 5c and 5d).
Otosclerosis is characterized by slowly progressive calcification in the middle ear due to chronic inflammation, which leads to impaired mobility of the auditory ossicles. Surgical removal and cleaning are performed in these patients, and AiCE is useful for precisely visualizing the extent of calcification. Otosclerosis is a progressive condition in which abnormal bone calcification occurs in areas near the oval window and membranous cochlea, interfering with the movements of the stapes. The procedure for repair of the stapes is one of the most precise microsurgical procedures in which a millimeter-scale artificial auditory ossicle is implanted in an opening created in the stapedial footplate. Aquilion Precision combined with AiCE is particularly useful for preoperative evaluation in such cases. Figure 5 shows images of two patients with abnormal decalcification that is difficult to see in the AIDR 3D image (Figure 5a) or original image (Figure 5b) is clearly depicted with reduced noise levels in the AiCE images (Figures 5c and 5d).
Figure 5: Otosclerosis in two patients
: Abnormal decalcification4. Evaluation of fine anatomical structures
In recent years, following the introduction of innovative endoscopic procedures for the treatment of middle ear abnormalities, it has become increasingly important to obtain a clear understanding of the 3D anatomy of fine soft tissue structures such as the tendons and nerves in the ear. With AiCE, the tensor tympani muscle and tendon and the chorda tympani can be clearly visualized (Figure 6).
In recent years, following the introduction of innovative endoscopic procedures for the treatment of middle ear abnormalities, it has become increasingly important to obtain a clear understanding of the 3D anatomy of fine soft tissue structures such as the tendons and nerves in the ear. With AiCE, the tensor tympani muscle and tendon and the chorda tympani can be clearly visualized (Figure 6).
Figure 6: Visualization of the chorda tympani in a 47-year-old woman
: Chordae tympani running between the auditory ossicles behind the tympanic membrane and continuing downward in the temporal bone
: Tympanic membraneConclusion
In the field of otolaryngology, in which individualized care is of particular importance, we have found Aquilion Precision with AiCE to be of great clinical value and will continue to make efforts to further expand its clinical application.//
Satoshi Yoshioka, PhD
Assistant Professor, Department of Otolaryngology / Head and Neck Surgery,
Fujita Health University, Aichi, Japan
Assistant Professor, Department of Otolaryngology / Head and Neck Surgery,
Fujita Health University, Aichi, Japan
References
1 Miyamoto, M., et al. Eur. Arch. Otorhinolaryngol., 276:3159-3164, 2019.
This article is a translation of the INNERVISION magazine, Vol.38, No.6, 2023.
Disclaimer
The contents of this report include the personal opinions of the author based on his clinical experience and knowledge.
1 Miyamoto, M., et al. Eur. Arch. Otorhinolaryngol., 276:3159-3164, 2019.
This article is a translation of the INNERVISION magazine, Vol.38, No.6, 2023.
Disclaimer
The contents of this report include the personal opinions of the author based on his clinical experience and knowledge.
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