Detecting and monitoring blood loss is always a challenging dilemma in emergency settings. The diameter of the inferior vena cava (IVC) in trauma patients may be useful in this way. This has been classically done with computed tomography (CT); however, doing it with ultrasound as a bedside easily available modality is a relatively novel approach. Between January 2006 and March 2006, 88 injured patients referred to our center were investigated. The patients were divided in to two groups: a shock group (n = 11, 12.5%) and a control group (n = 77, 87.5%) who were trauma patients with normal blood pressure. The maximum anteroposteroir diameter of IVC was measured ultrasonographically both in inspiration (i) and expiration (e) by M-mode in the subxyphoid area. The difference between the diameters of IVCe and IVCi was regarded as collapsibility, and collapsibility index was defined as IVCe - IVCi/IVCe. Statistical analysis included Mann-Whitney U test and correlation analysis. The average diameters of IVCe and IVCi in the shock group at arrival were significantly smaller than in the control group (5.6 +/- 0.8 mm, 4.0 +/- 0.7 mm versus 11.9 +/- 2.2 mm, 9.6 +/- 2.0 mm; P < 0.0001). The maximum diameter of IVC in the shock group was in a 30-year-old male patient with an IVCe and IVCi of 7.0 and 5.3 mm, respectively. Correlation analysis revealed a negative correlation between the diameter of IVCe (r = 0.72) and IVCi (r = 0.73) and the presence of shock. Regarding the collapsibility index, the mean collapsibility index of IVC was significantly higher in the shock group compared to patients in the control group (27% versus 20%; P < 0.001). The diameter of IVC was found to correlate with shock in trauma patients. The measurement of the IVC may be an important addition to the ultrasonographic evaluation of trauma and other potentially volume-depleted patients and can be added to the focused assessment with sonography for trauma (FAST) of the trauma patient with minimum additional time.

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There is an extensive spectrum of autoimmune entities that can involve the central nervous system, which has expanded with the emergence of new imaging modalities and several clinicopathologic entities. Clinical presentation is usually non-specific, and imaging has a critical role in the workup of these diseases. Immune-mediated diseases of the brain are not common in daily practice for radiologists and, except for a few of them such as multiple sclerosis, there is a vague understanding about differentiating them from each other based on the radiological findings. In this review, we aim to provide a practical diagnostic approach based on the unique radiological findings for each disease. We hope our diagnostic approach will help radiologists expand their basic understanding of the discussed disease entities and narrow the differential diagnosis in specific clinical scenarios. An understanding of unique imaging features of these disorders, along with laboratory evaluation, may enable clinicians to decrease the need for tissue biopsy.

Learning Objectives: On successful completion of this activity, participants should be able to (1) describe the neural pathways and basic anatomy of the commonly involved cranial nerves with perineural spread of tumor; (2) recognize the imaging findings of perineural spread in head and neck cancers on functional and anatomic imaging; and (3) explain the definition, pathogenesis, and clinical significance of perineural spread. Financial Disclosure: The authors of this article have indicated no relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through March 2022. Perineural spread (PNS) refers to tumor growth along large nerves, a macroscopic analog of microscopic perineural invasion. This phenomenon most commonly occurs in the head and neck, but its incidence varies with histologic tumor subtype. PNS results from a complex molecular interplay between tumor cells, nerves, and connective stroma. PNS is clinically underdiagnosed despite its impact on patients' prognosis and management. The role of 18 F-FDG PET in assessment of PNS in head and neck cancer remains to be explored, in contrast to MRI as the established gold standard. In patients with PNS, 18 F-FDG PET shows both abnormality along the course of the involved nerve and muscular changes secondary to denervation. Assessment of PNS on 18 F-FDG PET requires knowledge of relevant neural pathways and can be improved by correlation with anatomic imaging, additional processing of images, and review of clinical context.

Micrognathia, but not ICP, was associated with more significant OSA compared to controls. Both midface and mandibular hypoplasia contribute to OSA in these populations. OSA improved after surgical correction in most infants with micrognathia, and improved without intervention before palate repair in infants with ICP.

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The sellar, suprasellar, and parasellar space contain a vast array of pathologies, including neoplastic, congenital, vascular, inflammatory, and infectious etiologies. Symptoms, if present, include a combination of headache, eye pain, ophthalmoplegia, visual field deficits, cranial neuropathy, and endocrine manifestations. A special focus is paid to key features on CT and MRI that can help in differentiating different pathologies. While most lesions ultimately require histopathologic evaluation, expert knowledge of skull base anatomy in combination with awareness of key imaging features can be useful in limiting the differential diagnosis and guiding management. Surgical techniques, including endoscopic endonasal and transcranial neurosurgical approaches are described in detail.

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