Prospective Study of PET/MRI Tumor Response During Chemoradiotherapy for Patients With Low-risk and Intermediate-risk p16-positive Oropharynx Cancer.

OBJECTIVE: The objective of this study was to examine tumor response with positron emission tomography (PET)/magnetic resonance imaging (MRI) during chemoradiotherapy as a predictor of outcome in patients with p16-positive oropharynx cancer. MATERIALS AND METHODS: Patients with p16-positive oropharynx cancer were treated with chemoradiotherapy. Low-risk (LR) disease was defined as T1-T3 and N0-2b and ≤10 pack-years and intermediate-risk (IR) disease as T4 or N2c-3 or >10 pack-years. Patients underwent a PET/MRI scan pretreatment and at fraction 10. Change in value of imaging means were analyzed by analysis of variance. K-means clustering with Euclidean distance functions were used for patient clustering. Silhouette width was used to determine the optimal number of clusters. Linear regression was performed on all radiographic metrics using patient and disease characteristics. RESULTS: Twenty-four patients were enrolled with 7 LR and 11 IR patients available for analysis. Pretreatment imaging characteristics between LR and IR patients were similar. Patients with LR disease exhibited a larger reduction in maximum standardized uptake value (SUV) compared with IR patients (P<0.05). Cluster analysis defined 2 cohorts that exhibited a similar intratreatment response. Cluster 1 contained 7 of 7 LR patients and 8 of 11 IR patients. Cluster 2 contained 3 of 11 IR patients. Cluster 2 exhibited significant differences compared with cluster 1 in the change in primary tumor peak SUV and largest lymph node median SUV. CONCLUSIONS: We identified that IR p16-positive oropharynx cancers exhibit heterogeneity in their PET/MRI response to chemoradiotherapy. These data support further study of intratreatment imaging response as a potential mechanism to identify patients with IR oropharynx cancer suitable for treatment deintensification.

Anatomic development of the upper airway during the first five years of life: A three-dimensional imaging study.

PURPOSE: Normative data on the growth and development of the upper airway across the sexes is needed for the diagnosis and treatment of congenital and acquired respiratory anomalies and to gain insight on developmental changes in speech acoustics and disorders with craniofacial anomalies. METHODS: The growth of the upper airway in children ages birth to 5 years, as compared to adults, was quantified using an imaging database with computed tomography studies from typically developing individuals. Methodological criteria for scan inclusion and airway measurements included: head position, histogram-based airway segmentation, anatomic landmark placement, and development of a semi-automatic centerline for data extraction. A comprehensive set of 2D and 3D supra- and sub-glottal measurements from the choanae to tracheal opening were obtained including: naso-oro-laryngo-pharynx subregion volume and length, each subregion's superior and inferior cross-sectional-area, and antero-posterior and transverse/width distances. RESULTS: Growth of the upper airway during the first 5 years of life was more pronounced in the vertical and transverse/lateral dimensions than in the antero-posterior dimension. By age 5 years, females have larger pharyngeal measurement than males. Prepubertal sex-differences were identified in the subglottal region. CONCLUSIONS: Our findings demonstrate the importance of studying the growth of the upper airway in 3D. As the lumen length increases, its shape changes, becoming increasingly elliptical during the first 5 years of life. This study also emphasizes the importance of methodological considerations for both image acquisition and data extraction, as well as the use of consistent anatomic structures in defining pharyngeal regions.

Head position classification of medical imaging studies: an assessment and development of a protocol.

OBJECTIVES: To determine the optimal approach to reliably classify head position of head and neck medical imaging studies as flexion, neutral or extension for use in craniofacial and orthodontic research. METHODS AND MATERIAL: A prospective study scanned six participants in flexed, neutral and extended head positions. Additionally, a retrospective dataset of 46 CT studies were visually classified into six categories: flexion, neutral-flexion, neutral, neutral-extension, extension and flexion-extension. 14 landmarks were placed in the head and neck region of all studies to calculate 17 head position angle and distance measurements. Assessment of head position classification was performed for each measure, as well as all measures together using GUIDE forest. RESULTS: No single measure was sufficient to reliably classify head position in both retrospective and prospective imaging studies. Therefore, this study developed a head position protocol that considers multiple measures using two hybrid predictive models, to classify head position. Compared to visual assessment of head position, this protocol classified the imaging studies into the four head position categories with 82% neutral sensitivity and 100% neutral precision where the three neutral groups (neutral-flexion, neutral and neutral-extension) were grouped together. CONCLUSION: This study established a novel head position classification protocol that uses multiple measures accounting for both head and neck positions to reliably classify head positions in imaging studies as: flexion, neutral or extension. Given the limitation that no single measure reliably classified head position, this protocol is strongly recommended to researchers who need to account for head position to reach valid conclusions.

Auriculotemporal Nerve Involvement in Parotid Bed Malignancy.

OBJECTIVE: To identify and evaluate patients with parotid bed malignancy demonstrating radiographic findings of auriculotemporal (AT) nerve involvement. METHODS: A retrospective review of patients with parotid bed malignancy was performed to identify patients with imaging findings of AT nerve involvement and record associated clinical findings, symptoms, and pathology information. Independent, blinded review of radiographic images by a senior neuroradiologist was performed to identify imaging characteristics and categorize patients into highly likely or possible involvement groups. RESULTS: Of 547 patients identified with parotid bed malignancy, 23 patients exhibited radiographic findings suggestive of AT nerve involvement. Thirteen patients met criteria for highly likely involvement, and 10 patients met criteria for possible involvement. Cutaneous malignancy with metastasis to the parotid bed accounted for 11 of 23 patients, and the most common histology was squamous cell carcinoma (9 patients). Primary parotid malignancy accounted for 12 of 23 patients, and the most common histology was salivary ductal carcinoma (3 patients). All 13 highly likely patients reported periauricular pain, and 11 of 13 demonstrated facial weakness. Features suggesting advanced disease included radiographic findings of intracranial involvement (10/23 patients), nonsurgical primary treatment (13/23 patients), and positive margins on pathology report (7/10 patients). CONCLUSION: AT nerve involvement is an uncommon but important phenomenon that often occurs in the setting of advanced disease and is commonly associated with periauricular pain and coexisting facial weakness. Awareness of the associated clinical features and imaging patterns can allow for appropriate identification of this pattern of spread and help to optimize treatment planning.

Factors predicting the time-length variability of identically protocoled MRI exams.

BACKGROUND: Clinical variability in MRI exam durations can impede efficient MRI utilization. There is a paucity of data regarding the degree of variability of identically protocoled MRI studies and when nontechnological factors contribute to time-length variations in MRI exams. PURPOSE: To measure the magnitude of variation in MRI exam duration for identically protocoled MRI exams and to identify potential contributors to variations in MRI exam times. STUDY TYPE: Retrospective. SUBJECTS: 2705 identically protocoled MRI examinations of the cervical spine without contrast, comprehensive stroke exams, and comprehensive brain examinations performed on adult patients from June 30, 2016 through June 30, 2017. ASSESSMENT: MRI exam duration was obtained directly from the image data. Potential predictors for exam length variability were evaluated including patient age, patient gender, performing technologist, patient status (inpatient/outpatient/emergency department), MRI field strength, use of sedation, day of week, and the time of day. STATISTICAL TESTS: Linear regression analysis was performed for each individual variable after correcting for the MRI exam type. A multivariate mixed model was generated to assess for independent associations between the predictors and exam duration. RESULTS: There was substantial variability in the duration of the selected clinical MRI exams, with standard deviations (SDs) ranging between 19% and 29% of the mean exam length for each individual type of exam. The performing technologist was the most significant identified factor contributing to this variation in exam length; SD = 2.645 (P < 0.001). Compared with outpatient exams, inpatient exams required 4.18 minutes longer to complete (P < 0.001), and emergency department studies 1.86 minutes longer (P = 0.005). Male gender was associated with an additional 1.36 minutes of exam time (P < 0.001). DATA CONCLUSION: Nontechnical factors are associated with substantial variation in MRI exam times. These variations can be predicted based on relatively simple clinical and demographic factors, with implications for MRI exam scheduling, protocol design, staff training, and workflow design. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2019.

A General Framework for Monitoring Image Acquisition Workflow in the Radiology Environment: Timeliness for Acute Stroke CT Imaging.

Many facets of an image acquisition workflow leave a digital footprint, making workflow analysis amenable to an informatics-based solution. This paper describes a detailed framework for analyzing workflow and uses acute stroke response timeliness in CT as a practical demonstration. We review methods for accessing the digital footprints resulting from common technologist/device interactions. This overview lays a foundation for obtaining data for workflow analysis. We demonstrate the method by analyzing CT imaging efficiency in the setting of acute stroke. We successfully used digital footprints of CT technologists to analyze their workflow. We presented an overview of other digital footprints including but not limited to contrast administration, patient positioning, billing, reformat creation, and scheduling. A framework for analyzing image acquisition workflow was presented. This framework is transferable to any modality, as the key steps of image acquisition, image reconstruction, image post processing, and image transfer to PACS are common to any imaging modality in diagnostic radiology.

Imaging of temporal bone trauma.

Temporal bone trauma is commonly seen in patients with craniofacial injury and can be detected using multidetector computed tomography. A thorough understanding of the different types of temporal bone fracture patterns is needed to accurately describe the trajectory of injury as well as anticipated complications. Fractures should be described based on direction, segment of temporal bone involved, as well as involvement of the otic capsule. More importantly, the radiologist plays an integral role in identifying complications of temporal bone injury, which often have significant clinical implications.