Radiographics最新文献

The temporomandibular joint constitutes a synovial connection between the mandible and the skull base and plays a pivotal role in functions such as jaw movement, chewing, and verbal and emotional expression. Temporomandibular joint dysfunction is observed in about 30% of the population, with a higher prevalence in young to middle-aged women. Interestingly, a majority of individuals affected do not report pain, and only 5%-10% of symptomatic cases necessitate therapeutic intervention. The most common temporomandibular joint disorder manifests as pain in the masticatory muscles and is referred to as myofascial syndrome. However, articular disorders are also very common, usually due to disk displacement and degenerative or inflammatory arthropathies. Less frequently, the temporomandibular joint may be affected by a range of congenital and acquired conditions such as trauma and neoplasms. Imaging becomes necessary for the small percentage of patients who do not respond to conservative management or when there is uncertainty in the diagnosis. A comprehensive understanding of the normal imaging appearance of the temporomandibular joint as well as the wide range of potential pathologic conditions is essential for conducting an accurate radiologic assessment. Moreover, collaboration among multidisciplinary teams and the correlation of imaging findings with arthroscopic observations are crucial to advancing the diagnosis and treatment of temporomandibular joint dysfunction. ^©RSNA, 2024 Supplemental material is available for this article.

A wide range of pathologic conditions can originate in the orbit. While it is common to approach the differential diagnosis based on disease categories, such as neoplastic and inflammatory, segmenting the orbit into anatomic compartments can direct the radiologist toward the most common pathologic conditions for each manifestation and space. The orbit can be divided into intraconal, conal, and extraconal compartments. Additionally, the optic nerve sheath complex and lacrimal apparatus can be partitioned into separate compartments due to their unique functions and pathologic features. By using this anatomic approach, the authors review the most common pathologic conditions affecting the orbit and discuss clinical and imaging findings that can guide the differential diagnosis for lesions with similar appearances. Published under a CC BY 4.0 license. Supplemental material is available for this article.

Hybrid PET/MRI has the potential to transform neuro-oncologic imaging, particularly in diagnosis and treatment planning of somatostatin receptor-expressing tumors of the head and neck. Hybrid PET/MRI combines high-resolution MRI with functional information from PET, providing precise anatomic information and overcoming difficulties in localization inherent to PET alone. There is a range of tumors in the head and neck that overexpress somatostatin receptors and are therefore amenable to evaluation with somatostatin receptor PET/MRI. These include meningiomas, paragangliomas, olfactory neuroblastomas, pituitary neuroendocrine tumors, middle ear neuroendocrine tumors, and medullary thyroid carcinomas. The combination of PET and MRI is superior to either modality alone and can address several unique diagnostic challenges associated with these lesions. The authors discuss the superior capabilities of somatostatin receptor PET/MRI, including improved lesion localization, more sensitive demonstration of disease extent, enhanced surveillance, optimized radiation therapy planning, and accurate prediction of response to somatostatin analog therapy. Although there are only a few dedicated PET/MRI units available in clinical practice, commercial software is now available that can automatically fuse PET/CT data with recently acquired MRI data, increasing the availability of this approach. Radiologists should be aware of the advantages of somatostatin receptor PET/MRI in evaluation of head and neck tumors as well as the potential pitfalls of this approach so that they can accurately advise clinicians and better interpret these studies. ^©RSNA, 2024 See the invited commentary by Shatzkes and Strauss in this issue.

The past decade has seen exponential advancements in molecular markers and the genetics of tumors, recognizing the limitations of conventional histopathology for grading, classification, and prognostication. Such advances have resulted in changes to classification systems, for example, with the incorporation of objective molecular and genetic information into the 2021 World Health Organization (WHO) classification of central nervous system tumors. The fifth edition of the WHO classification of head and neck tumors (HN5) (beta online version, 2022) also introduced major changes based on molecular markers, including additions, deletions, and reclassifications of entities, with the idea of being more objective and standardized. These changes are highly relevant to therapy decisions, prognosis, and clinical research and for patients with resistant diseases to explore options in clinical trials. The HN5, for the first time, included a radiologist as a member of the writing team to incorporate pertinent imaging findings into the classification. It is important for the radiologist, as an integral part of the multidisciplinary team, to be up to date about these changes for a better understanding of tumor biology, to integrate this into their clinical practice, and to provide more value in their interpretations. The authors provide a basic understanding of pathology and genetics for the radiologist, highlighting the molecular changes in epithelial (including squamous cell) and nonepithelial tumors of the head and neck. The authors also highlight newly recognized and reclassified tumor entities and provide a brief discussion on the genetic tumor syndromes. ^©RSNA, 2024 Supplemental material is available for this article. See the invited commentary by Junn and Baugnon in this issue.