Contemporary Imaging and Reporting Strategies for Head and Neck Cancer: MRI, FDG PET/MRI, NI-RADS, and Carcinoma of Unknown Primary-AJR Expert Panel Narrative Review.

CT, MRI, and FDG PET/CT play major roles in the diagnosis, staging, treatment planning, and surveillance of head and neck cancers. Nonetheless, an evolving understanding of head and neck cancer pathogenesis, advances in imaging techniques, changing treatment regimens, and a lack of standardized guidelines have led to areas of uncertainty in the imaging of head and neck cancer. This narrative review aims to address four issues in the contemporary imaging of head and neck cancer. The first issue relates to the standard and advanced sequences that should be included in MRI protocols for head and neck cancer imaging. The second issue relates to approaches to surveillance imaging after treatment of head and neck cancer, including the choice of imaging modality, the frequency of surveillance imaging, and the role of standardized reporting through the Neck Imaging Reporting and Data System. The third issue relates to the role of imaging in the setting of neck carcinoma of unknown primary. The fourth issue relates to the role of simultaneous PET/MRI in head and neck cancer evaluation. The authors of this review provide consensus opinions for each issue.

Imaging Aspects of the Hippocampus.

The hippocampus is one of the most sophisticated structures in the brain, owing to its complex anatomy, intriguing functions, relationship with other structures, and relevant associated symptoms. Despite being a structure analyzed for centuries, its anatomy and physiology in the human body are still being extensively studied, as well as associated pathologic conditions and potential biomarkers. It can be affected by a broad group of diseases that can be classified as congenital, degenerative, infectious or inflammatory, neoplastic, vascular, or toxic-metabolic disease. The authors present the anatomy and close structures, function, and development of the hippocampus, as well as an original algorithm for imaging diagnosis. The algorithm includes pathologic conditions that typically affect the hippocampus and groups them into nodular (space occupying) and nonnodular pathologic conditions, serving as a guide to narrow the differential diagnosis. MRI is the imaging modality of choice for evaluation of the hippocampus, and CT and nuclear medicine also improve the analysis. The MRI differential diagnosis depends on anatomic recognition and careful characterization of associated imaging findings such as volumetric changes, diffusion restriction, cystic appearance, hyperintensity at T1-weighted imaging, enhancement, or calcification, which play a central role in diagnosis along with clinical findings. Some pathologic conditions arising from surrounding structures such as the amygdala are also important to recognize. Pathologic conditions of the hippocampus can be a challenge to diagnose because they usually manifest as similar clinical syndromes, so the imaging findings play a potential role in guiding the final diagnosis. Online supplemental material is available for this article. ©RSNA, 2022.

Sialographic analysis of parotid ductal abnormalities associated with Sjogren's syndrome.

OBJECTIVES: To analyze the location and degree of parotid ductal abnormalities associated with Sjogren's syndrome (SS) and to correlate findings with the duration of the disease. To develop a classification system based on contemporary sialography techniques and employ the system to grade findings on sialograms. To assess the role for therapeutic intervention in patients with SS. METHODS: Retrospective chart review of a consecutive series of 337 sialograms done by the senior investigator over a 10-year period identified 26 sialograms in patients who met the criteria for SS as defined by the American-European Consensus Group (2002). A classification system was developed to grade the degree of ductal abnormalities identified on the sialograms. Individual, initial blinded review of these sialograms was performed by two head and neck radiologists to identify and grade abnormalities. Radiographic findings were correlated with patient history including symptom duration. RESULTS: All patients with SS had stenoses within the ductal system. About 73.1% of patients had stenoses in each branch of the ductal system (primary, secondary, and tertiary ducts). In 19% of patients, the main duct was of normal caliber despite the presence of stenosis in the more proximal ducts (secondary and tertiary ducts). Peripheral (proximal) duct dilation was characterized among those affected in patterns classified as destructive (34.6%), cavitary (26.9%), globular (11.5%), or punctate (11.5%). A statistically significant positive correlation (p = .0360) was identified between symptom duration and degree of main ductal stenosis. CONCLUSION: Sialography may be useful to objectively assess the degree of parotid ductal damage in SS employing a newly proposed classification system. This assessment may assist clinicians in tailoring management to selectively include ductal dilation.

Safety and effectiveness of Factor Eight Inhibitor Bypassing Activity for direct oral anticoagulant-related hemorrhage reversal.

BACKGROUND: The incidence of patients who present with life-threatening bleeding complications has been increasing as the use of direct oral anticoagulation (DOAC) has increased. Therefore, effective reversal agents are urgently needed. Current guidelines recommend the use of prothrombin complex concentrates (PCCs) and activated PCCs (aPCC) for reversal of DOAC anticoagulant activity in the setting of traumatic and non-traumatic intracranial hemorrhage (ICH). However, little data is available. OBJECTIVE: Herein, we investigated the safety and effectiveness of Factor Eight Inhibitor Bypassing Activity [FEIBA (an aPCC)] in a population of patients who required emergent reversal of DOAC for hemorrhage or urgent surgical interventions. METHODS: This is a case series study. Medical records from patients who required emergent reversal of DOAC for life threatening hemorrhage or urgent surgical interventions were collected from February 1, 2014, to April 1, 2017 and reviewed. Data, including demographics as well as safety, outcomes, and dosing of FEIBA for reversal of DOAC effects were collected and descriptive statistics were obtained. RESULTS: Forty-two patients who received FEIBA were included in the study. The rates of thrombotic events (10%), hemorrhage progression (10%), and observed mortality (29%) were similar to rates previously published in the limited literature evaluating aPCC use in this population. CONCLUSION: This case series suggests that FEIBA administration is relatively safe and effective to reverse DOACs in the setting of hemorrhage or need for urgent surgical procedures. Until target-specific reversal agents are available, future studies are warranted to evaluate the effectiveness of aPCC administration for DOAC-associated hemorrhagic complications.

Computed Tomography Angiogram Derived From Computed Tomography Perfusion Done with Low Iodine Volume Protocol Preserves Diagnostic Yield for Middle Cerebral Artery-M2 Occlusions.

BACKGROUND: Computed tomography angiogram (CTA) derived from computed tomography perfusion (CTP) has been proposed to avoid addition of separate CT perfusion protocol for selection of large vessel occlusion in acute stroke patients. Previous studies have validated this technique for proximal large vessel occlusions. In this study, we test reliability for identifying M2 occlusions on CTA derived from CTP. METHODS: Through a retrospective search of the institutional thrombectomy database, we identified 28 cases with M2-MCA occlusion, of which 24 met the inclusion criteria for analysis. An additional 20 cases without M2-MCA occlusion (either normal or M1-MCA occlusion) were randomly mixed in the database to reduce observer bias. The baseline images of the CTP study in these 48 cases were then independently analyzed by 3 readers with varying level of expertise. The digital subtraction angiography (DSA) images were also independently reviewed where available. The percentage of agreement among reviewers as well as the probability of agreement of the reviewers, when compared to the DSA findings was also calculated. RESULTS: The observed agreement for the image quality amongst the 3 readers (n = 48) varied between 0.78 and 0.95 and tended to be higher for the M1 segment MCA and lower for distal M2-MCA. The observed agreements comparing 3 image reviewers versus DSA in M2 patients (n = 24) was 98% for identifying occlusion (95% CI 95%-100%), 94% for identifying proximal M2 occlusion (95% CI 88%-98%), and 91% (95% CI 84%-97%) and 90% (95% CI 83%-95%), respectively for correctly identifying inferior and superior branch of M2 occlusion. CONCLUSION: CTA data derived from CT Perfusion study preserves diagnostic yield for correctly identifying M2 occlusion.

Cerebral Microbleeds are an Independent Predictor of Hemorrhagic Transformation Following Intravenous Alteplase Administration in Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Intravenous alteplase (rt-PA) increases the risk of hemorrhagic transformation of acute ischemic stroke. The objective of our study was to evaluate clinical, laboratory, and imaging predictors on forecasting the risk of hemorrhagic transformation following treatment with rt-PA. We also evaluated the factors associated with cerebral microbleeds that increase the risk of hemorrhagic transformation. METHODS: Consecutive patients with acute ischemic stroke admitted between January 1, 2009 and December 31, 2013 were included in the study if they received IV rt-PA, had magnetic resonance imaging (MRI) of the brain on admission, and computed tomography or MRI of the brain at 24 (18-36) hours later to evaluate for the presence of hemorrhagic transformation. The clinical data, lipid levels, platelet count, MRI, and computed tomography images were retrospectively reviewed. RESULTS: The study included 366 patients, with mean age 67 ± 15 years; 46% were women and 88% were white. The median National Institutes of Health Stroke Scale (NIHSS) score was 6 (interquartile range 3-15). Hemorrhagic transformation was observed in 87 (23.8%) patients and cerebral microbleeds were noted in 95 (25.9%). Patients with hemorrhagic transformation tended to be older, nonwhite, have atrial fibrillation, higher baseline NIHSS score, lower cholesterol and triglyceride levels, and cerebral microbleeds and nonlacunar infarcts. Patients with cerebral microbleeds were more likely to be older, have hypertension, hyperlipidemia, previous history of stroke, and prior use of antithrombotics. On multivariate analysis race, NIHSS score, nonlacunar infarct, and presence of cerebral microbleeds were independently associated with hemorrhagic transformation following treatment with rt-PA. CONCLUSIONS: Presence of cerebral microbleeds is an independent predictor of hemorrhagic transformation of acute ischemic stroke following treatment with rt-PA.

Genetic Syndromes Associated with Central Nervous System Tumors.

Several genetic tumor syndromes have associated central nervous system (CNS) neoplasms. The spectrum of syndromes that have intracranial tumor manifestations includes ataxia telangiectasia, Cowden syndrome, familial adenomatous polyposis, hereditary non-polyposis-related colorectal cancer, Li-Fraumeni syndrome, Gorlin syndrome, neurofibromatosis types 1 and 2, multiple endocrine neoplasia type 1, tuberous sclerosis complex, von Hippel-Lindau disease, and Turcot syndrome. Many of these disorders are inherited in an autosomal dominant fashion, and identification of the associated genetic defects has led to improved understanding of the molecular pathways involved in tumorigenesis, helping pave the way to the emergence of molecularly targeted therapeutics. Recognition of individuals and families at risk for such tumors is critical to improve clinical care and optimize proper genetic counseling. To contribute effectively, the radiologist should recognize the common varieties of tumors and characteristic neuroimaging manifestations seen in each familial syndrome. A fundamental understanding of the genetics and molecular pathogenesis of these tumors is critical in understanding the development of specific and unique tumors in each entity. In this article, we review the most common genetic tumor syndromes with associated intracranial neoplasms, with emphasis on recent genetic and molecular biology data, clinical manifestations, and management as well as the controversies and current recommendations for screening and surveillance. A detailed overview of all the major and pertinent CNS imaging features will be elucidated, including computed tomography, magnetic resonance imaging, and, in relevant cases, magnetic resonance spectroscopy. ©RSNA, 2016.

The Many Faces of Granulomatosis With Polyangiitis: A Review of the Head and Neck Imaging Manifestations.

OBJECTIVE: Wegener granulomatosis has recently been renamed as granulomatosis with polyangiitis (GPA). In this review, we examine the clinical criteria and pathologic and pathophysiologic mechanisms of GPA, with an emphasis on findings encountered in the realm of head and neck imaging. Particular attention is paid to generating an appropriate differential diagnosis, because many of the imaging features of GPA overlap with those of other diseases, most notably lymphoma and sarcoidosis. Recent therapeutic advancements have underscored the importance of the radiologist in suggesting the diagnosis early, resulting in earlier treatment and decreased patient morbidity. This is particularly true for the head and neck manifestations of GPA; although they are less common, they often herald a refractory disease course that requires aggressive immunosuppressive therapy. Knowledge of common and uncommon imaging findings enables the radiologist to diagnose GPA early enough to start treatment promptly and reduce patient morbidity. CONCLUSION: Although there are no reliable pathognomonic imaging features for GPA, the present article attempts to identify patterns of disease that are suggestive of the disease. The diagnosis ultimately relies on a constellation of radiographic findings, laboratory values, and accurate clinical history.

Limited Wegener's Granulomatosis Presenting with an Isolated Abduction Deficit.

Wegener's granulomatosis often affects the orbit, typically presenting with painful proptosis. The authors describe a 14 year-old girl, with limited Wegener's granulomatosis, who initially presented with an isolated painless abduction deficit that spontaneously resolved over several weeks. She subsequently developed painful proptosis and diplopia, followed by facial and oral nodules. This case demonstrates that limited Wegener's granulomatosis can rarely present with an isolated painless abduction deficit.

Impact of a Reading Room Coordinator on Efficiency of On-Call Radiology Residents.

OBJECTIVES: Few level I trauma, tertiary care, academic centers have a paid, permanent reading room coordinator (RRC) to facilitate image management services during off-hour calls, to minimize interruptions to reading workflow. The purpose of this study is to investigate the effect of an RRC on the efficiency of radiology residents signing preliminary reports for emergency department (ED) and inpatient studies. METHODS: A pre- and postintervention retrospective review was performed, using carestream PACS to retrieve imaging studies read on call during two time periods-July 1 to December 1, 2019 (pre-RRC), and July 1 to December 1, 2021 (post-RRC). Efficiency of residents signing preliminary reports was measured by turnaround time (TAT), defined as the time from when a study was marked complete by a technologist to when a preliminary report was signed by a resident, in PACS. RESULTS: In the above time periods, residents interpreted a total of 64,406 studies on call. For ED studies, the mean TAT was 7.0 min shorter post-RRC, compared with pre-RRC (95% confidence interval [CI]: -7.8 to -6.1, (t = 15.50, degrees of freedom (df) = 31,866, P < .0001). The percentage of ED studies signed within 30 min increased from 57.7% to 65.8%, an increase of 8.1% (95% CI: 7.0% to 9.1%) after employing an RRC (χ2 = 228.11, df = 1, P < .0001). For inpatient studies, the mean TAT was 10.2 min shorter post-RRC (95% CI: -12.3 to -8.0, t = 9.22, df = 25,193, P < .0001). CONCLUSIONS: An RRC increased radiology resident on-call workflow efficiency, facilitating care for patients in both the ED and inpatient setting.

The ASNR International Collaborations Committee: Cultivating a Global Learning Community.

The American Society of Neuroradiology has expanded its global presence, driven by the efforts of the International Collaborations Committee. This committee is actively involved in training radiologists and fostering collaborations worldwide in the fields of education, research, and community service. This article explores key initiatives of the committee, such as the Anne G. Osborn ASNR International Outreach Professor Program, the International Imaging Series, and Virtual Reading Rooms. Additionally, we provide insight into recent developments related to the pandemic and outline future opportunities.

Proposal for standardized ultrasound analysis of the salivary glands: Part 1 submandibular gland.

Objectives: The Salivary Gland Committee of the American Academy of Otolaryngology-Head and Neck Surgery seeks to standardize terminology and technique for ultrasonograpy used in the evaluation and treatment of salivary gland disorders. Methods: Development of expert opinion obtained through interaction with international practitioners representing multiple specialties. This committee work includes a comprehensive literature review with presentation of case examples to propose a standardized protocol for the language used in ultrasound salivary gland assessment. Results: A multiple segment proposal is initiated with this focus on the submandibular gland. We provide a concise rationale for recommended descriptive language highlighted by a more extensive supplement that includes an extensive literature review with additional case examples. Conclusion: Recommendations are provided to improve consistency both in performing and reporting submandibular gland ultrasound.

ACR Appropriateness Criteria® Dizziness and Ataxia: 2023 Update.

Diagnostic evaluation of a patient with dizziness or vertigo is complicated by a lack of standardized nomenclature, significant overlap in symptom descriptions, and the subjective nature of the patient's symptoms. Although dizziness is an imprecise term often used by patients to describe a feeling of being off-balance, in many cases dizziness can be subcategorized based on symptomatology as vertigo (false sense of motion or spinning), disequilibrium (imbalance with gait instability), presyncope (nearly fainting or blacking out), or lightheadedness (nonspecific). As such, current diagnostic paradigms focus on timing, triggers, and associated symptoms rather than subjective descriptions of dizziness type. Regardless, these factors complicate the selection of appropriate diagnostic imaging in patients presenting with dizziness or vertigo. This document serves to aid providers in this selection by using a framework of definable clinical variants. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Advanced imaging of head and neck infections.

When head and neck infection is suspected, appropriate imaging contributes to treatment decisions and prognosis. While contrast-enhanced CT is the standard imaging modality for evaluating head and neck infections, MRI can better characterize the skull base, intracranial involvement, and osteomyelitis, implying that these are complementary techniques for a comprehensive assessment. Both CT and MRI are useful in the evaluation of abscesses and thrombophlebitis, while MRI is especially useful in the evaluation of intracranial inflammatory spread/abscess formation, differentiation of abscess from other conditions, evaluation of the presence and activity of inflammation and osteomyelitis, evaluation of mastoid extension in middle ear cholesteatoma, and evaluation of facial neuritis and labyrinthitis. Apparent diffusion coefficient derived from diffusion-weighted imaging is useful for differential diagnosis and treatment response of head and neck infections in various anatomical sites. Dynamic contrast-enhanced MRI perfusion may be useful in assessing the activity of skull base osteomyelitis. MR bone imaging may be of additional value in evaluating bony structures of the skull base and jaw. Dual-energy CT is helpful in reducing metal artifacts, evaluating deep neck abscess, and detecting salivary stones. Subtraction CT techniques are used to detect progressive bone-destructive changes and to reduce dental amalgam artifacts. This article provides a region-based approach to the imaging evaluation of head and neck infections, using both conventional and advanced imaging techniques.

Gadolinium as a contrast agent for infusion sialograms in patients with iodine allergy.

Objectives: To assess the adequacy of gadolinium in sialography as an alternative contrast agent for patients with iodine allergies. To directly compare images taken with gadolinium versus iodine-based contrast agents using the Iowa Sialography Classification System. Methods: Retrospective chart review was performed on patients undergoing sialography between February 2008 and July 2022. Patients with sialograms obtained with gadolinium were identified and matched to similar sialograms obtained with iodine-based contrast agent. Patients were matched based on duct location, duct side, and initial radiology findings. Blinded reevaluation of sialograms was performed first independently and then by consensus by two head and neck radiologists to evaluate overall image adequacy and grade using the Iowa Sialography Classification System. Results: Four patients with six sialograms (one bilateral parotid and one parotid + submandibular) obtained with gadolinium were identified and reevaluated. Five patients with six sialograms (one bilateral parotid) obtained with iodine-based were matched to the gadolinium sialograms. The overall adequacy of images for gadolinium sialograms was graded at an average of 4.25 (4 = good and 5 = excellent); whereas, the overall adequacy of iodine-based sialograms was graded at an average of 5. Inter-observer variability was observed in three sialograms obtained with gadolinium (50%), while no interobserver variability was observed in sialograms obtained with iodine-based contrast agent. Conclusion: Gadolinium is an adequate alternative to use in sialography for patients with iodine allergies undergoing contemporary digital infusion sialography. Adverse reactions to iodine contrast agents are rare in sialography; however, the precautionary use of gadolinium is acceptable for the diagnostic and therapeutic benefits in sialography.Level of Evidence: IV.

ACR Appropriateness Criteria® Staging and Post-Therapy Assessment of Head and Neck Cancer.

Imaging of head and neck cancer at initial staging and as part of post-treatment surveillance is a key component of patient care as it guides treatment strategy and aids determination of prognosis. Head and neck cancer includes a heterogenous group of malignancies encompassing several anatomic sites and histologies, with squamous cell carcinoma the most common. Together this comprises the seventh most common cancer worldwide. At initial staging comprehensive imaging delineating the anatomic extent of the primary site, while also assessing the nodal involvement of the neck is necessary. The treatment of head and neck cancer often includes a combination of surgery, radiation, and chemotherapy. Post-treatment imaging is tailored for the evaluation of treatment response and early detection of local, locoregional, and distant recurrent tumor. Cross-sectional imaging with CT or MRI is recommended for the detailed anatomic delineation of the primary site. PET/CT provides complementary metabolic information and can map systemic involvement. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Tinnitus: 2023 Update.

Tinnitus is abnormal perception of sound and has many subtypes. Clinical evaluation, audiometry, and otoscopy should be performed before ordering any imaging, as the choice of imaging will depend on various factors. Type of tinnitus (pulsatile or nonpulsatile) and otoscopy findings of a vascular retrotympanic lesion are key determinants to guide the choice of imaging studies. High-resolution CT temporal bone is an excellent tool to detect glomus tumors, abnormal course of vessels, and some other abnormalities when a vascular retrotympanic lesion is seen on otoscopy. CTA or a combination of MR and MRA/MRV are used to evaluate arterial or venous abnormalities like dural arteriovenous fistula, arteriovenous malformation, carotid stenosis, dural sinus stenosis, and bony abnormalities like sigmoid sinus wall abnormalities in cases of pulsatile tinnitus without a vascular retrotympanic lesion. MR of the brain is excellent in detecting mass lesions such as vestibular schwannomas in cases of unilateral nonpulsatile tinnitus. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

ACR Appropriateness Criteria® Sinonasal Disease: 2021 Update.

This article presents guidelines for initial imaging utilization in patients presenting with sinonasal disease, including acute rhinosinusitis without and with suspected orbital and intracranial complications, chronic rhinosinusitis, suspected invasive fungal sinusitis, suspected sinonasal mass, and suspected cerebrospinal fluid leak. CT and MRI are the primary imaging modalities used to evaluate patients with sinonasal disease. Given its detailed depiction of bony anatomy, CT can accurately demonstrate the presence of sinonasal disease, bony erosions, and anatomic variants, and is essential for surgical planning. Given its superior soft tissue contrast, MRI can accurately identify clinically suspected intracranial and intraorbital complications, delineate soft tissue extension of tumor and distinguish mass from obstructed secretions.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Imaging of Facial Trauma Following Primary Survey.

Maxillofacial trauma patients comprise a significant subset of patients presenting to emergency departments. Before evaluating for facial trauma, an emergency or trauma physician must perform a primary survey to ensure patient stabilization. Following this primary survey, this document discusses the following clinical scenarios for facial trauma: tenderness to palpation or contusion or edema over frontal bone (suspected frontal bone injury); pain with upper jaw manipulation or pain overlying zygoma or zygomatic deformity or facial elongation or malocclusion or infraorbital nerve paresthesia (suspected midface injury); visible nasal deformity or palpable nasal deformity or tenderness to palpation of the nose or epistaxis (suspected nasal bone injury); and trismus or malocclusion or gingival hemorrhage or mucosal hemorrhage or loose teeth or fractured teeth or displaced teeth (suspected mandibular injury). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.