Department of Diagnostic Radiology

Tatsushi Kobayashi, Hirofumi Kuno, Yasunori Arai, Kaoru Shimada, Tomoaki Sasaki, Takashi Hiyama, Shioto Oda, Takahiro Morita, Rakuhei Nakama, Souta Masuoka, Yusuke Miyasaka, Toshihiro Horii

Introduction

The department of diagnostic radiology is committed to improving health through excellence in image-oriented patient care and research. Our department performs approximately 140,000 inpatient and outpatient examinations annually. Our department also conducts clinical scientific research and basic scientific studies, with the results translated directly into better patient care.

The Team and What We Do

Our department has four multi-slice CT scanners (one ultra-high-resolution CT, two area detector CT scanners and one dual-source CT), two 3T MRI systems, one interventional radiology (IR) CT system, one multi-axis c-arm CT system, two gamma cameras with the capacity for single photon emission CT (SPECT), two digital radiographic (DR) systems for fluoroscopy, two mammography (MMG) machines, and four computed radiographic (CR) systems. Our IR-CT systems use digital subtraction angiography with multi-detector computerized tomography (MDCT). One is equipped with a 320 multi-slice CT. A positron emission tomography (PET) scanner and baby cyclotron have been installed, and tumor imaging using 18F-FDG (fluorodeoxyglucose) has been performed. These all-digital image systems enhance the efficacy of routine examinations.

This department has ten staff radiologists, a senior resident and a resident. As part of our routine activities, every effort is made to produce an integrated report covering almost all examinations, such as MMG, contrast radiological procedures, CT, MRI, RI, PET, angiography and IR, mainly transarterial chemoembolization (TACE).

The number of cases examined in 2021 is shown in Table 1 and Table 2. Several conferences are routinely held at our department including pre- and postoperative conferences. Our department also contributes to deciding the treatment strategy through image presentations at the weekly tumor board conference (especially, the hepatobiliary-pancreatic and head-neck regions).

Table 1. Number of examinations in 2021


Table 2. Number of interventional radiology procedures in 2021

Research activities

The research activities of the Department of Diagnostic Radiology focus on diagnostic imaging and IR. These activities consist of 1) Development of new CT/MR imaging techniques and 2) Texture analysis and radiomics research. In addition, our department also conducts clinical scientific research and basic scientific studies, the results of which are translated directly into better patient care.

(1) Development of new CT/MR imaging techniques

A major focus of our department is the development of new imaging techniques using advanced CT/MR systems, including ultra-high-resolution CT (UHR CT), dual-energy CT (DECT), and area-detector CT (ADCT) for cancer patients.

UHR CT systems can provide images with a matrix size as large as 2048 × 2048 and slice thickness of 0.25 mm, which significantly increases resolution in the x-y axes and z axis. We work with UHR CT systems, mainly focusing on head and neck imaging to compare the delineation of delicate anatomical structures, such as microvessels and small lymph nodes, between UHRCT and conventional MDCT. DECT has the potential to improve the detection of pathologies and increase diagnostic confidence in the evaluation of a variety of cancers by using X-ray energy-dependent absorption behaviors of various materials. In addition, DECT allows for material decomposition so that iodine can be differentiated from soft tissue, and it can potentially provide additional further “contrast resolution” to standard contrast-enhanced CT images. Using spectral dual-energy images, we work with dual-source CT and ADCT systems, mainly focusing on lung, head and neck, and pancreatic cancer imaging. We are also working on a new imaging reconstruction technique: the artificial intelligence (AI)-based Advanced Intelligent Clear-IQ Engine (AiCE). We apply this AiCE technique to bone subtraction iodine (BSI) imaging that uses UHR CT or 320-row ADCT scanning. BSI imaging with AiCE is expected to help detect bone invasion, such as in the skull base/mandible, and accurately assess the extent of cancer cells' bone and soft tissue invasion. We are working on several validation studies, such as evaluating bone/soft tissue invasion in patients with head and neck cancer.

(2) Texture analysis and radiomics research

Our department also focuses on developing new techniques to determine diagnoses and predict prognoses, treatment responses, and outcomes from images and other associated data using texture analysis techniques and “radiomics.” Image texture is defined as a complex visual pattern within an image consisting of simpler sub-patterns with characteristic features, and texture analysis allows the mathematical detection of the subtle spatial arrangement of the gray levels among image pixels. Furthermore, “radiomics” extends traditional imaging consultation to include a deeper analysis of these medical images from various imaging modalities (e.g., CT, PET, and MRI) and refers to the extraction and analysis of a large number of advanced quantitative imaging texture features with high throughput. These radiomics data will impact personalized medicine, where treatment can be tailored toward patient-specific needs. One of our main areas of interest is connecting tumor-specific radiomic features with their clinical information, including treatment outcomes. Ultimately, we aim to translate these developments into clinical applications and decision support systems using machine learning algorithms. We primarily work with cross-sectional images, including CT and MRI, and specialize in cancer imaging, mainly focusing on head and neck cancer and esophageal cancers.

Clinical trials

We are conducting a multicenter clinical trial, “The single-armed confirmatory trial for immediate effectivity and safety of palliative arterial embolization for painful bone metastases. (JIVROSG/J-SUPPORT 1903),” as a representative facility, which started in March 2021. The purpose of this trial is to verify the safety and immediate effect of transarterial embolization as a palliative treatment for painful bone metastases and to establish it as a standard treatment. This research is funded by the Japan Agency for Medical Research and Development (AMED).

List of papers published

Journal

1. Sugawara H, Ito K, Watanabe H, Morita T, Yatabe Y, Watanabe SI, Kusumoto M. Clinical usefulness of PET/MRI in differentiating anterior mediastinal masses. Nuclear medicine communications, 43:92-99, 2022

2. Hiyama T, Kuno H, Sekiya K, Tsushima S, Oda S, Kobayashi T. Subtraction iodine imaging with area detector CT to improve tumor delineation and measurability of tumor size and depth of invasion in tongue squamous cell carcinoma. Japanese journal of radiology, 40:167-176, 2022

3. Masuoka S, Miyazaki O, Takahashi H, Tsutsumi Y, Hiyama T, Kitamura M, Okamoto R, Miyasaka M, Minami M, Nosaka S. Predisposing conditions for bacterial meningitis in children: what radiologists need to know. Japanese journal of radiology, 40:1-18, 2022

4. Masuoka S, Hiyama T, Kuno H, Morishita Y, Sakashita S, Kobayashi T. A case of Epstein-Barr virus-positive mucocutaneous ulcer of the hypopharynx: a mimicker of hypopharyngeal squamous cell carcinoma. International cancer conference journal, 11:71-74, 2022

5. Baba A, Hashimoto K, Kuno H, Masuda K, Matsushima S, Yamauchi H, Ikeda K, Yamazaki M, Taiki S, Ogane S, Kurokawa R, Ota Y, Nomura T, Ojiri H. Assessment of squamous cell carcinoma of the floor of the mouth with magnetic resonance imaging. Japanese journal of radiology, 39:1141-1148, 2021

6. Okumura M, Hojo H, Nakamura M, Hiyama T, Nakamura N, Zenda S, Motegi A, Hirano Y, Kageyama SI, Parshuram RV, Fujisawa T, Kuno H, Akimoto T. Radiation pneumonitis after palliative radiotherapy in cancer patients with interstitial lung disease. Radiotherapy and oncology: journal of the European Society for Therapeutic Radiology and Oncology, 161:47-54, 2021

7. Nakama R, Arai Y, Takei Y, Kobayashi T. Successful transcatheter arterial embolization for uretero-inferior epigastric arterial fistula: A rare complication of cutaneous ureterostomy. Urology case reports, 38:101726, 2021