3D cephalometry: a new approach for landmark identification and image orientation

Cephalometry is the scientific study of the measurement of the head in relation to specific reference points. In 3D CT cephalometry, these points are identified on three-dimensional surface models generated from computed tomography scans. In this study a new approach for 3D cephalometry is presented, which should improve reproducibility of the technique and allow accurate comparison of pre- and postoperative data

Suprahyoid Neck: Anatomy and Principle of Pathology

The suprahyoid neck extends from the hyoid bone inferiorly to the skull base, excluding the orbit, sinonasal and oral cavity. The suprahyoid neck is anatomically complex but can be organized into different spaces based on the fascial planes. Multiple systems with slightly different namings are adapted. As a consensus, 5 principal spaces and 2 posterior midline spaces can be recognized. Each space contains unique contents which are subject to a predictable set of disease processes. Localization of lesions to a particular space allows the generation of a limited radiologic differential diagnosis. This is termed a “space-specific diagnosis”. The anatomy and related pathology of the pharyngeal mucosal, the parapharyngeal, the carotid space, the masticator space, the parotid space, the retropharyngeal space, and the perivertebral space will be discussed. After the presentation, participants will be able to comprehend the anatomy of the suprahyoid neck, understand the concept of a space- specific diagnosis and formulate a (differential) diagnosis when encountering pathology in the suprahyoid neck region

Cranial Nerves: Anatomy and Imaging

Twelve pairs of cranial nerves control the sensory and motor functions of the head and neck region, with exception of the tenth nerve, the vagus nerve which also is responsible for the parasympathetic and viscerosensory innervation of the thoracoabdominal organs. MRI is the cornerstone in the study of cranial nerves. Next to the traditional sequences that depict general anatomical findings and pathological changes, two additional sequences should be included in every imaging protocol for cranial nerves. High-resolution steady-state free precession is important for the visualization of the cisternal courses of the cranial nerves. These sequences have a high spatial resolution and additionally show dark cranial nerves against a background of bright CSF. Three-dimensional T1-weighted GE sequences, preferentially with fat suppression, provide a good evaluation of nerve enhancement. The twelve cranial nerves are individually discussed from the intra-axial segments to the distal extracranial branches. There is a specific emphasis on the connections between different cranial nerves. Finally, new imaging techniques are highlighted

A new method for improved standardisation in three-dimensional computed tomography cephalometry

Interest for three-dimensional computed tomography cephalometry has risen over the last two decades. Current methods commonly rely on the examiner to manually point-pick the landmarks and/or orientate the skull. In this study, a new approach is presented, in which landmarks are calculated after selection of the landmark region on a triangular model and in which the skull is automatically orientated in a standardised way. Two examiners each performed five analyses on three skull models. Landmark reproducibility was tested by calculating the standard deviation for each observer and the difference between the mean values of both observers. The variation can be limited to 0.1 mm for most landmarks. However, some landmarks perform less well and require further investigation. With the proposed reference system, a symmetrical orientation of the skulls is obtained. The presented methods contribute to standardisation in cephalometry and could therefore allow improved comparison of patient data

YRS Survey

Residents have many questions concerning their training, education, and future, especially in a professional atmosphere that is considered difficult due to increasing financial and political restrictions in the health care system. To objectify this matter, the young radiologist section (YRS) created an online survey

Automated extraction of the femoral shaft axis and its distal entry point from full and reduced 3D models

During conventional total knee arthroplasty, the shaft or medial axis of the femur (FSA) is referenced by inserting an intramedullary rod (FIR), which is then used to position the femoral prosthesis. In this study, an automated technique, based on geometrical entity fitting, is presented for extracting the FSA and FIR from a 3D triangular surface mesh. The algorithms are tested using computed tomography scans of 50 cadaveric femurs. Furthermore, reduced models are processed and compared to the full models to study the feasibility of partially scanning the thigh. The mean deviations for two outer parts of 25% and a central part of 5% of the femoral length are smaller than 1 mm for the FSA and 0.3° and 0.5 mm for the orientation and entry point of a 150 mm long FIR. The automated methods could offer a valuable assistance to the surgeon for preoperative planning of FIR insertion

Retro-Odontoid Pseudotumor in a Patient with Atlanto-Occipital Assimilation

A retro-odontoid pseudotumor is an uncommon non-neoplastic mass. They are mostly associated with rheumatoid arthritis and atlanto-axial subluxation. The pathogenesis is degeneration of the transverse ligament due to chronic mechanical stress. In this case report, an atlanto-occipital assimilation altered the biomechanics of the cervical spine, causing chronic mechanical stress on the transverse ligament and subsequently the development of a retro-odontoid pseudotumor. This is in accordance with previous studies that have attributed the development of retro-odontoid pseudotumor to a loss of mobility of the cervical spine, in cases without associated rheumatoid arthritis or atlanto-axial subluxation