Chairs:
dirk schulze
kaan orhan
248: A WORKFLOW- AND PATIENT-COMFORT OPTIMIZED DENTAL-DEDICATED MRI COIL: TECHNICAL CHARACTERIZATION AND USER ACCEPTANCE EVALUATION
A. Greiser1, M. Keil1, J. Thöne1, S. Dennert1, G. Wigger1, T. Lanz2, M. Graf2, M. Geißner2, K. Kettless3, J. Rothard1
1Siemens Healthineers AG, Erlangen, Germany, 2RAPID Biomedical GmbH, Rimpar, Germany, 3Siemens Healthcare Denmark, Ballerup, Denmark
Aim: A dental-dedicated MR receive coil is proposed with optimal anatomical coverage, high sensitivity in the dentomaxillofacial (DMF) region, highest patient comfort and ease-of-use to facilitate clinical dental MRI at 0.55T with diagnostic quality in short examinations.
Material and Methods: Aiming for openness, reduced patient motion and easy handling & hygiene, a dental MR receive coil was developed with an asymmetric holder mechanism (RAPID Biomedical GmbH, Rimpar, Germany). The coil array consists of an arrangement of seven coil elements in a row, combining a rigid central element with an opening for the nose and mouth, and flexible flaps containing three more coil elements on each side to cover the DMF region. The mechanical holder structure enables precise positioning of the coil in close vicinity of the patient´s face and adjustment of height and angulation in proximity to the patient jaw. The coil was characterized regarding SNR vs. standard head-neck coil, patient and operator perception and diagnostic performance.
Results: High quality imaging of the DMF region could be performed in short exam times at 0.55T with the dedicated coil. Feedback on patient and operator perception was overall very positive. The relative signal-to-noise was shown to be comparable or higher in the relevant DMF structures compared to a standard head/neck coil, but lower in the brain region (SNR condyles: 341%, mandibular bone: 191%, sella: 91%, brain: 29%).
Conclusion: It is feasible to perform diagnostic dental-dedicated MRI at 0.55T with short scan times at high patient comfort using a dedicated dental coil.
257: FOCUSING ON THE DENTOMAXILLOFACIAL REGION IN DENTAL-DEDICATED MRI WORKFLOWS
A. Greiser1, C. Hayes1, M. Keil1, J. Thöne1, K. Iyer2, Y.Y. Kang3, L. Lauer1, K. Burzan4, D.R. Nixdorf5, R. Spin-Neto6
1Siemens Healthineers AG, Erlangen, Germany, 2Siemens Medical Solutions USA, Malvern, United States, 3Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China, 4Dentsply Sirona, Bensheim, Germany, 5University of Minnesota School of Dentistry, Division of TMD & Orofacial Pain, Minneapolis, United States, 6Aarhus University, Department of Dentistry and Oral Health, Aarhus, Germany
Aim: To test a set of technological features enabling a trained operator to perform focused dentomaxillofacial (DMF) MRI, without compromising on diagnostic image quality.
Material and Methods: A combination of methods to limit the imaging volume to the DMF region were implemented on a dental-dedicated 0.55 T MRI system (MAGNETOM Free.Max, Siemens Healthineers AG, Germany). These included the use of a dedicated surface coil, automated image volume positioning and optimization of scan parameters for a small field-of-view coverage, e.g., 6.0×6.0x2.5cm3, i.e., for tooth-specific and TMJ sections. To further ensure the focus on DMF also in larger FoV scans, as used in orthodontic applications, explicit 3D image volume restriction, positioned relative to cephalometric landmarks detected in scout images, was employed. For this purpose, an algorithm was trained (“AdaBoost”, n=70 volumes) to automatically detect these landmarks. The performance of the algorithm was assessed in an additional 133 subjects, including instances where metal artefacts due to retainers and prostheses were present.
Results: 3D image volume restriction was successful in 130/133 test cases. Even in cases with metal artefact, results were judged as acceptable, as the relevant landmarks were not affected. Detection quality was rated very good in 87.2%, good in 9.8%, marginal in 0.8% and failed in only 2.2% due to severe metal artefacts.
Conclusion: Focus in dental MRI using landmark detection in scout MR images is feasible and will enable time-efficient exams with dental-diagnostic image quality in dental-dedicated MRI.
264: IMAGING FINDINGS OF NASOPHARYNGEAL TUMORS IN PADIATRIC POPULATION
D. Haba1, D.-A. Ilinca1, D. Pomohaci1, B.I. Dobrovat1, C. Antohi1, D. Palade1, M.S.C. Haba2, A.E. Sirghe1, A. Nemtoi1, A. Nemtoi3
1University Grigore T. Popa Iasi, Surgery, Iasi, Romania, 2University Grigore T. Popa Iasi, Medicine II, Iasi, Romania, 3University „ Stefan cel Mare“, Department of Biomedical Sciences, Suceava, Romania
Aim: Nasopharyngeal lesions in paediatric ages are divided mostly into non-neoplastic and neoplastic masses. The purpose of this study is to present imaging aspects encountered over a period of 2 years in a group of children with nasopharyngeal lesions.
Methods: In the last year (Jan. 2023- Jan. 2024), a total of 113 paediatric patients were addressed to „N. Oblu Emergensy Hospital Iasi” for further imagistic investigation and specialised treatment having different brain diseases. We analised 80 patients via MRI, 32 patients with computer-tomography, and we complete this study with a paediatric patient in hospital evidence for a period of 3 years.
Results: Benign adenoidal hypertrophy was identified in 12 feminine patients and 14 male patients. Only 6 male patients had fibroadenoma and only 5 cases had different sized Thornwaldt cysts. The 6-year-old patient is from 2010, when he presented after 3 repetitive cases of bacterial tonsillitis. He undergoes a CT scan that shows serous otitis associated with manifested hypertrophy of the left posterior and lateral nasopharyngeal mucosa. One year post-treatment, the CT scan identifies a pulmonary metastasis, without a genuine intracranial extension of the primary lesion.
Conclusion: Nasopharyngeal carcinomas are rarely suspected clinically and imaging wise in a young patient. It is a must to promptly and efficiently examinate the key radiological elements of the nasopharyngeal mucosa changes in a patient with repetitive otitis and epistaxis for early diagnosis and timely appropriated therapy
256: TAILORING THE EXAMINATION WORKFLOW IN DENTAL-DEDICATED MRI
M. van de Stadt-Lagemaat1, M. Hellinger1, C. Krellmann1, M. Keil1, J. Thöne1, G. Krüger1, K. Kettless2, K. Burzan3, R. Spin-Neto4, A. Greiser1
1Siemens Healthineers AG, Erlangen, Germany, 2Siemens Healthcare A/S, Ballerup, Denmark, 3Sirona Dental Systems GmbH, Bensheim, Germany, 4Aarhus University, Department of Dentistry and Oral Health, Aarhus, Denmark
Aim: To develop an optimized examination workflow for dental-dedicated MRI by minimizing examination durations without compromising on image quality and diagnostic value.
Material and methods: Healthy volunteers were examined using a 0.55T scanner (MAGNETOM Free.Max, Siemens Healthineers, Erlangen, Germany), equipped with a dental-dedicated 7 channel array coil.
Examination workflows for three dental indications (temporomandibular joints (TMJ), orthodontics, tooth extraction) were created using optimized MR pulse sequences (2D: 6×6 cm2 FOV, in-plane resolution 0.3×0.3mm2 and section thickness 2 mm, proton-density-weighted turbo spin-echo sequences including deep-learning based image reconstruction; 3D: 15x18x18cm3 proton-density-weighted SPACE with compressed sensing and denoising, resolution 0.5×0.5×0.5mm3). Automatic view planning software was integrated in the workflow to reduce time-consuming user interactions. Overall examination times and nominal signal-to-noise (SNR) were assessed.
Results: Examinations could be completed within 15 minutes with diagnostic image quality (TMJ: 13:11 min, orthodontics: 11:52 min, tooth extraction: 14:28 min). The SNR in the clinical scans was sufficient in the relevant dentomaxillofacial structures, as confirmed by a dental radiologist (SNR condyles: 15.1, mandibular bone: 23.8, sella: 11.3, pulp: 13.4, brain: 3.1).
Conclusion: With the tested dental-dedicated workflow setup, including automated view planning and optimized sequences, examinations with diagnostic image quality can be performed in clinically acceptable examination times of less than 15 minutes. Shorter examination times contribute to better patient cooperation, which is generally beneficial for MR image quality. The tailored workflows with short examination times may improve acceptance of dental-dedicated MRI in dentistry.