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Featured Application: Importance of the evaluation of radiation doses to highly radiosensitive organs in children using dental cone beam computed tomography, given that children are highly sensitive to radiation. Dental cone beam computed tomography (CBCT) is a diverse 3D X-ray imaging technique that has enabled clear visualization of the teeth and surrounding structures. The most common diagnostic purpose of dental CBCT examination in children is ectopic eruption and impacted teeth, and a small field of view (FOV) is often used. Since it is difficult for children to control their body movements, reducing the rotation angle is effective. However, no studies have examined the effects of different rotation angles on radiation doses to highly radiosensitive organs in children using small FOVs. The purpose of this study was to examine the effects of small FOVs (4 × 4 cm and 6 × 6 cm) and rotation angles (360° and 180°) on doses that highly sensitize organs in children using dental CBCT. The entrance surface doses to lenses, thyroid lobes, parotid glands, and sublingual glands of a pediatric whole-body phantom were measured. By reducing the FOV from 6 × 6 cm to 4 × 4 cm, the dose to the sublingual gland could be significantly decreased. Additionally, by reducing the rotation angle from 360° to 180°, the lens dose can be decreased significantly. As the rate of dose reduction varies among organs, it is important to consider the relative positions of different organs with respect to the FOV and the trajectory of the X-ray tube. [ABSTRACT FROM AUTHOR]

Introduction: A squamous cell carcinoma of the oral cavity or mobile tongue represents the sixth most common type of cancer worldwide. Patient work‐up procedures vary among institutions, though generally include clinical, imaging, and histopathology examinations. This study had two aims: assess the accuracy of ultrasound (US) and magnetic resonance imaging (MRI) for evaluating tumor thickness of ventral tongue squamous cell carcinoma, and ascertain the effects of biopsy on imaging results. Methods: We retrospectively examined the medical records of 69 patients diagnosed and treated for ventral tongue squamous cell carcinoma stage T1 or T2. We compared tumor thickness in US and MRI results with histological thickness measured using specimens obtained in a partial glossectomy. Results: The mean difference between thickness measured with MRI before the biopsy procedure and that of the pathological specimens was 0.28 mm while that between US imaging results before the biopsy and histologic thickness was 0.75 mm. Furthermore, following the biopsy, the mean difference between thickness shown by MRI and that of the histological specimens was 0.89 mm, and between US findings and histologic thickness was 2.67 mm. There was a positive correlation between thickness shown by MRI and US when performed before the biopsy and the pathological result. Conclusions: MRI and US results appear to have adequate accuracy for estimating the thickness of T1‐and T2 lesions of the tongue when scanning is performed prior to a biopsy procedure. Furthermore, the present findings confirm the clinical impression that inflammatory changes induced by a biopsy often alter later imaging findings. [ABSTRACT FROM AUTHOR]

Objective: We analysed the correlation between magnetic resonance images of the parotid and submandibular glands and the salivary flow rate in patients with Sjögren's syndrome. Methods: We retrospectively reviewed magnetic resonance images (heterogeneous signal‐intensity distribution and gland volume on T1‐ and fat‐suppressed T2‐weighted images, and multiple high‐signal‐intensity spots on magnetic resonance sialograms in the parotid and submandibular glands) obtained from 66 patients who were diagnosed with Sjögren's syndrome. We evaluated the relationship between these imaging features and their salivary flow rates in stimulated and unstimulated conditions. Results: We found that as the disease progressed, both the heterogeneous signal‐intensity distribution and the volumes of the parotid and the submandibular glands were significantly related to the stimulated and the unstimulated salivary flow rate. These imaging features were more highly correlated in assessments of the submandibular gland than in those of the parotid gland for both stimulated and unstimulated salivary flow rates. Conclusions: Magnetic resonance image features of heterogeneity and smaller volume in the submandibular gland are reliable for predicting hyposalivation related to the progression of Sjögren's syndrome. [ABSTRACT FROM AUTHOR]

This report showed a case of temporomandibular joint (TMJ) ankylosis suspected to be associated with ankylosing spondylitis based on the observation of bony ankylosis of the cervical spine on computed tomography (CT) images. A 53-year-old man presented with a chief complaint of difficulty in opening his mouth. His medical history indicated that in his 20s, he became aware of the difficulty in moving his neck. CT revealed marked osteoarthritic changes in the right mandibular condyle, suggesting fibrotic TMJ ankylosis. In addition, bony ankylosis of the cervical vertebral body and facet joints from the axis (C2) to C5 in continuity was observed. CT of the entire spine also showed bony deformity of the sacroiliac joints and bony ankylosis. Based on these findings, ankylosing spondylitis was suspected. The possibility of an ankylosing spondylitis complication should be considered in cases of TMJ ankylosis if bony ankylosis of the cervical spine is observed., Competing Interests: Conflicts of Interest: None, (Copyright © 2024 by Korean Academy of Oral and Maxillofacial Radiology.)

Objectives: Arrested pneumatisation (AP) is an anatomic variant of the sphenoid sinus. Since AP remains underrecognised, otolaryngologists and radiologists may mistake AP for a lesion and perform follow-up imaging studies. We investigated the imaging findings of CT, MRI, and F-18 fludeoxyglucose (FDG)-positron emission tomography (PET) for AP, and discussed the differences between AP and other skull base lesions., Methods: We reviewed multidetector low CT imaging of 442 patients (285 men and 157 women; age range, 19-93 years; mean age, 67.8 years) who underwent FDG-PET/CT for head and neck tumours between January 2019 and December 2019. The imaging findings of AP were reviewed on CT, MRI, FDG-PET/CT, and compared with those of fibrous dysplasia, chordoma, chondrosarcoma, multiple myeloma, and bone invasion of nasopharyngeal carcinoma., Results: AP was identified in 22 patients (14 men and 8 women; age range, 24-93 years; mean age, 67.0 years) based on criteria from previous reports. AP manifested with well-circumscribed sclerotic margins on CT, without evidence of expansion. AP showed high-signal intensity on T 1 -/ T 2 weighted MRI. FDG-PET revealed non-significant uptake [maximum standardised uptake value (SUV max ): 0.85 (range, 0.4-1.27)] in AP. Contrastingly, skull base lesions showed expansion, poorly circumscribed boundaries without osteosclerotic margins, and moderate-to-severe FDG uptake (SUV max : 1.8-8.4)., Conclusions: The characteristic imaging findings of AP, namely non-expansile on CT and non-uptake on FDG-PET, may aid in its differentiation from other skull base lesions.

Positron emission tomography (PET)/computed tomography (CT) has improved sensitivity and resolution using silicon photomultiplier as a photosensor. Previously, only a fixed setting was available for the shooting time of 1 bed, but now, the shooting time can be changed for each bed. Time can be shortened or extended depending on the target area. A few studies reported on image reconstruction conditions for head and neck cancer in whole-body PET/CT examinations. Thus, this study aimed to optimize the imaging conditions of the head and neck region during whole-body imaging. A cylindrical acrylic container with a 200 mm diameter was used to simulate the head and neck area using a PET/CT system equipped with a semiconductor detector. Spheres of 6-30 mm in diameter were enclosed in the 200 mm diameter cylindrical acrylic vessel. Radioactivity in 18F solution (Hot:BG ratio 4:1) was enclosed in a phantom following the Japanese Society of Nuclear Medicine (JSNM) guidelines. Background radioactivity concentration was 2.53 kBq/mL. List mode acquisition of 1,800 s was collected at 60-1,800 s with the field of view of 700 mm and 350 mm. The image was reconstructed by resizing the matrix to 128 × 128, 192 × 192, 256 × 256, and 384 × 384, respectively. The imaging time per bed in the head and neck should be at least 180 s, and the reconstruction conditions should be a field of view (FOV) of 350 mm, matrix sizes of ≥ 192, and a Bayesian penalized likelihood (BPL) reconstruction with a β-value of 200. This allows detection of > 70% of the 8-mm spheres in the images.