Early Postoperative Magnetic Resonance Imaging Findings Related to Electrocauterization for Cerebellar Reduction During Chiari Decompression Surgery.

BACKGROUND: Cerebellar tonsillar reduction or resection can be performed as part of the surgical management of Chiari type 1 malformation when it is accompanied by symptomatic brainstem compression or syringomyelia. The purpose of this study is to characterize the early postoperative magnetic resonance imaging (MRI) findings in patients with Chiari type 1 malformations who undergo cerebellar tonsillar reduction via electrocautery. METHODS: The extent of cytotoxic edema and microhemorrhages demonstrated on MRI scans obtained within 9 days following surgery was assessed and correlated with neurological symptoms. RESULTS: Cytotoxic edema was found on all postoperative MRI examinations included in this series, with superimposed hemorrhage in 12 of 16 patients (75%) and was primarily located along the margins of the cauterized inferior cerebellum. Cytotoxic edema was present beyond the margins of the cauterized cerebellar tonsils in 5 of 16 patients (31%) and was associated with new focal neurological deficits in 4 of 5 patients (80%). CONCLUSION: Cytotoxic edema and hemorrhages along the cerebellar tonsil cautery margins can be expected findings in early postoperative MRI in patients who undergo Chiari decompression accompanied by tonsillar reduction. However, the presence of cytotoxic edema beyond these regions can be associated with new focal neurological symptoms.

Advances in the Radiological Evaluation of and Theranostics for Glioblastoma.

Imaging is essential for evaluating patients with glioblastoma. Traditionally a multimodality undertaking, CT, including CT cerebral blood profusion, PET/CT with traditional fluorine-18 fluorodeoxyglucose (18F-FDG), and MRI have been the mainstays for diagnosis and post-therapeutic assessment. However, recent advances in these modalities, in league with the emerging fields of radiomics and theranostics, may prove helpful in improving diagnostic accuracy and treating the disease.

MRI radiomics and potential applications to glioblastoma.

MRI plays an important role in the evaluation of glioblastoma, both at initial diagnosis and follow up after treatment. Quantitative analysis via radiomics can augment the interpretation of MRI in terms of providing insights regarding the differential diagnosis, genotype, treatment response, and prognosis. The various MRI radiomic features of glioblastoma are reviewed in this article.

Characterizing Lymph Node Burden With Elective Unilateral Neck Irradiation in Human Papillomavirus-Positive Tonsil Squamous Cell Carcinoma: Defining the Upper Limits.

Objectives Elective unilateral neck irradiation in well-lateralized tonsil carcinoma for N2b disease is controversial. Metrics regarding nodal burden beyond the N-stage to define the upper limit of this de-escalation approach remain limited. We investigated the role of nodal number, level, and volume on outcomes in patients with well-lateralized tonsil carcinoma treated with this approach. Methods A total of 37 patients received radiotherapy (RT) with unilateral neck coverage for well-lateralized tonsil cancer. Of patients, 95% had p16+ disease, and 81% were staged with positron emission tomography/computed tomography. The majority of patients received definitive chemoradiation on prospective de-escalation trials. Ten patients had ipsilateral neck dissections and were treated adjuvantly. The median RT dose to the ipsilateral neck (generally II-IV) was 45 Gy. The effects of nodal number, max dimension, volume, and level on recurrence-free survival (RFS) and overall survival (OS) were to be analyzed via Cox proportional hazards (Cox-PH). Results After a median follow-up of 3.9 years, two-year RFS and two-year OS were 100% and 97%, respectively. Given the 0% contralateral recurrence rate, Cox-PH analysis was not performed. Of patients, 70% were American Joint Committee on Cancer (AJCC) 7th edition N2b, with a median number of nodes, number of nodal levels, max dimension, and volume of two, one, 3.4 cm, and 15.6 cc, respectively. There were several patients with low-lying nodes; aggregate nodal volume measured was up to 85.4 cc. Conclusion Unilateral neck irradiation in well-lateralized tonsil carcinoma resulted in no contralateral recurrence. Nodal volume, level, and number do not seem to have a significant impact on outcomes.

Semantic Segmentation of Extraocular Muscles on Computed Tomography Images Using Convolutional Neural Networks.

Computed tomography (CT) imaging of the orbit with measurement of extraocular muscle size can be useful for diagnosing and monitoring conditions that affect extraocular muscles. However, the manual measurement of extraocular muscle size can be time-consuming and tedious. The purpose of this study is to evaluate the effectiveness of deep learning algorithms in segmenting extraocular muscles and measuring muscle sizes from CT images. Consecutive CT scans of orbits from 210 patients between 1 January 2010 and 31 December 2019 were used. Extraocular muscles were manually annotated in the studies, which were then used to train the deep learning algorithms. The proposed U-net algorithm can segment extraocular muscles on coronal slices of 32 test samples with an average dice score of 0.92. The thickness and area measurements from predicted segmentations had a mean absolute error (MAE) of 0.35 mm and 3.87 mm2, respectively, with a corresponding mean absolute percentage error (MAPE) of 7 and 9%, respectively. On qualitative analysis of 32 test samples, 30 predicted segmentations from the U-net algorithm were accepted while 2 were rejected. Based on the results from quantitative and qualitative evaluation, this study demonstrates that CNN-based deep learning algorithms are effective at segmenting extraocular muscles and measuring muscles sizes.

Computed Tomography Imaging Artifacts in the Head and Neck Region: Pitfalls and Solutions.

Computed tomography (CT) artifacts are aberrations that usually degrade the image quality of CT images, but occasionally provide insights regarding actual imaging findings. The presence of artifacts can be attributed to various sources, including patient, scanner, and postprocessing factors. Artifacts can lead to diagnostic errors by obscuring findings or by being misinterpreted as actual lesions. This article reviews various types of CT artifacts that can be encountered in the head and neck region and explain how these artifacts may be mitigated. While we cannot fully eliminate the occurrence of CT artifacts, building an awareness of their cause provides reading physicians the tools to detect and read through their presence. Further, this knowledge may be applied to contribute to protocol adjustments to improve a site's overall imaging practice.

MR Imaging Artifacts in the Head and Neck Region: Pitfalls and Solutions.

MR Imaging artifacts are features appearing in MR images that are not present in the original anatomy. MR imaging artifacts can be patient-related, hardware-related, or signal-processing-related and affect diagnostic quality or mimic pathology. It is necessary to take MR imaging artifacts into consideration when interpreting images. A basic knowledge of MR imaging physics and the potential origin of MR imaging artifacts can help to find solutions to eliminate or reduce the influence of artifacts on image quality by adjusting acquisition parameters appropriately for a better diagnosis.

Pearls and Pitfalls of 18FDG-PET Head and Neck Imaging.

18FDG-PET plays an important role in cancer imaging. However, there are certain challenges with interpreting head and neck 18FDG-PET. In this article, examples of technical issues that can undermine the interpretation of the scans, normal physiologic activity that can mimic lesions or obscure lesions, and causes of false positives and false negatives on posttreatment cancer imaging are discussed. In addition, suggestions for addressing potential pitfalls on head and neck 18FDG-PET are highlighted.

Postsurgical and Postradiation Findings in the Head and Neck Imaging.

Surgical procedures and radiation therapy can have recognizable features on diagnostic imaging that should be recognized by the radiologist. Although it is a good practice to reference the surgical and clinical notes regarding any procedures that may have been performed in the head and neck, this information is not always available. Selected examples of posttreatment findings and potential mimics are described and depicted in the following sections.

Implants and Foreign Bodies on Head and Neck Imaging.

A wide variety of foreign bodies can be encountered on head and neck imaging. These foreign bodies might include comestible foreign bodies, retained foreign bodies from trauma, and surgically implanted devices. The imaging features of these items are reviewed in this article.

Normal Anatomic Structures, Variants, and Mimics of the Temporal Bone.

Various anatomic structures and variants in the temporal bone are potential radiological mimics and surgical hazards. The imaging features of normal variants and lesions with similar imaging appearance are presented in this article. Throughout the article, salient features that can help elucidate the distinguishing features between mimics and imaging pitfalls are presented.

Multimodality management of sinonasal teratocarcinosarcoma in a 76-year-old Alaska Native female during the COVID-19 pandemic.

Sinonasal teratocarcinosarcoma is a rare, highly aggressive tumor of the anterior skull base composed of malignant epithelial, mesenchymal, and neural tissue. Examination of cases in patients in minority populations is important in order to better understand the behavior of this neoplasm and outcomes of treatment in our nation's diverse population.

Imaging of the Postoperative Eye and Orbit.

There is a plethora of surgical procedures that are performed in the eye and orbit. The consequences of these procedures can often be observed on diagnostic imaging through the presence of various implants and altered anatomy. The expected postoperative changes in the eye and orbit, the impact of implants on image quality and safety, and potential associated complications are reviewed in this article. Conventional computed tomography and MR imaging scans are useful for the postoperative assessment of the eye and orbit. The computed tomography and MR imaging findings related to the postoperative eye and orbit are reviewed in this article.

Differentiating low and high grade mucoepidermoid carcinoma of the salivary glands using CT radiomics.

BACKGROUND: The purpose of this study is to determine if Haralick texture analysis on CT imaging of mucoepidermoid carcinomas (MEC) can differentiate low-grade and high-grade tumors. METHODS: A retrospective review of 18 patients with MEC of the salivary glands, corresponding CT imaging and pathology report was performed. Tumors were manually segmented and image analysis was performed to calculate radiomic features. Radiomic features were compared between low-grade and high-grade MEC. A multivariable logistic regression model and receiver operating characteristic analysis was performed. RESULTS: A total of 18 patients (mean age, 51, range 9-83 years, 8 men and 10 women) were included. Nine patients had low-grade pathology and nine patients had high-grade pathology. Of the 18 cases, 7 (39%) occurred in the parotid gland and 11 (61%) occurred in minor salivary glands. No individual feature was significantly different between low-grade and high-grade MEC. A logistic regression model including surface regularity, energy and information measure II of correlation was performed and was able to predict high-grade MEC accurately (sensitivity 89%, specificity 68%). The area under the receiver operating characteristic curve was 0.802. CONCLUSIONS: High-grade MEC tend to have a low energy, high correlation texture as well as surface irregularity. Together, these three features may comprise a tumor phenotype that is able to predict high-grade pathology in MECs.

Radiomic Model Predicts Lymph Node Response to Induction Chemotherapy in Locally Advanced Head and Neck Cancer.

This study developed a pretreatment CT-based radiomic model of lymph node response to induction chemotherapy in locally advanced head and neck squamous cell carcinoma (HNSCC) patients. This was a single-center retrospective study of patients with locally advanced HPV+ HNSCC. Forty-one enlarged lymph nodes were found from 27 patients on pretreatment CT and were split into 3:1 training and testing cohorts. Ninety-three radiomic features were extracted. A radiomic model and a combined radiomic-clinical model predicting lymph node response to induction chemotherapy were developed using multivariable logistic regression. Median age was 57 years old, and 93% of patients were male. Post-treatment evaluation was 32 days after treatment, with a median reduction in lymph node volume of 66%. A three-feature radiomic model (minimum, skewness, and low gray level run emphasis) and a combined radiomic-clinical model were developed. The combined model performed the best, with AUC = 0.85 on the training cohort and AUC = 0.75 on the testing cohort. A pretreatment CT-based lymph node radiomic signature combined with clinical parameters was able to predict nodal response to induction chemotherapy for patients with locally advanced HNSCC.

Baseline Computed Tomography Radiomic and Genomic Assessment of Head and Neck Squamous Cell Carcinoma.

PURPOSE: To determine the relationship between computed tomography (CT) radiomic features and gene expression levels in head and neck squamous cell carcinoma (HNSCC). METHODS: This retrospective study included 66 patients with HNSCC primary lesions (36 oropharyngeal, 6 hypopharyngeal, 10 laryngeal, 14 oral cavity). Gene expression information for 6 targetable genes (fibroblast growth factor receptor [FGFR]1, epidermal growth factor receptor [EGFR], FGFR2, FGFR3, EPHA2, PIK3CA) was obtained via Agilent microarrays from samples collected between 1997 and 2010. Pretreatment contrast-enhanced soft tissue neck CT scans were reviewed, and 142 radiomics features were derived. R was used to calculate Pearson correlation coefficients were calculated between gene expression levels and each radiomic feature. P values were adjusted using the false discovery rate (FDR) method. RESULTS: There were significant correlations between FGFR1 and 5 gray level cooccurrence matrix (GLCM) features with FDR-adjusted P values less than 0.05: inertia (r = 0.366, FDR-adjusted P = 0.006), absolute value (r = 0.31, FDR-adjusted P = 0.024), contrast (r = 0.366, FDR-adjusted P = 0.006), difference average (r = 0.31, FDR-adjusted P = 0.024), and difference variance (r = 0.37, FDR-adjusted P = 0.005). There was 1 correlated feature for FGFR2 with an FDR-adjusted P value less than 0.05: fractal dimension box-coarse (r = 0.33, FDR-adjusted P = 0.018). There was 1 correlated feature for EPHA2 with an FDR-adjusted P value less than 0.05: GLCM entropy (r = -0.28, FDR-adjusted P = 0.049). Six of the 7 features that showed significant correlation belonged to the GLCM class of features. CONCLUSIONS: The CT radiomic features demonstrate correlations with FGFR1 status in HNSCC and should be further investigated for their potential to predict FGFR1 status.

Normative measurements of parotid lymph nodes on CT imaging.

PURPOSE: The goal of this study is to characterize the normal size of parotid lymph nodes among healthy adult patients on CT. METHODS: This was a single-center retrospective observational study of 543 patients who underwent maxillofacial CT scans between January 2019 and July 2019. The long and short axis diameters of the largest lymph nodes in the bilateral superficial parotid glands were measured. RESULTS: Among the 543 patients, 407 subjects with a mean age of 47.0 ± 18.4 years had a total of 719 detectable intraparotid lymph nodes. The mean patient age was 47.0 ± 18.4 years. Of all 719 measured intraparotid lymph nodes, the measured long and short axis diameter means were 4.4 ± 1.4 mm and 3.3 ± 1.1 mm, respectively. In our study, 96% (689/719) of all lymph nodes had a long axis diameter of 7 mm or less and 93% (671/719) of all lymph nodes had a short axis diameter of 5 mm or less. Younger patients had significantly larger lymph nodes than older patients in both long axis (4.5 vs 4.3 mm; P = 0.03) and short axis (3.4 vs 3.1 mm, P = 0.01) measurements. CONCLUSION: Our findings suggest 5 mm as an upper limit of normal for the short axis diameter of superficial intraparotid lymph nodes.

Neuroimaging of septo-optic dysplasia-plus with midbrain hypoplasia and ophthalmoplegia.

Septo-optic dysplasia is a rare brain malformation that can be associated with anomalous cortical development, such as schizencephaly, which is referred to as septo-optic dysplasia plus. This report describes septo-optic dysplasia-plus associated with unilateral atrophy of the midbrain and oculomotor nerve deficiency, which was diagnosed on MRI in a teenage male who presented with ophthalmoplegia.