Feasibility of clinical evaluation of individuals with increased risk for HPV-associated oropharynx cancer.

BACKGROUND: Human papillomavirus-associated oropharynx squamous cell carcinoma (HPV-OPSCC) has no known pre-malignant lesion. While vaccination offers future primary prevention, there is current interest in secondary prevention. The feasibility of clinical evaluation of individuals at increased risk for HPV-OPSCC is unclear. METHODS: Individuals with risk factors for HPV-OPSCC were enrolled in a prospective study (MOUTH). Participants positive for biomarkers associated with HPV-OPSCC were eligible for a clinical evaluation which comprised a head and neck examination and imaging with ultrasound and/or magnetic resonance imaging (MRI). This study was designed to evaluate feasibility of clinical evaluation in a screening study. RESULTS: Three hundred and eighty-four participants were eligible for clinical evaluation. Of the 384, 204 (53%) completed a head and neck examination or imaging. Of these, 66 (32%) completed MRI (n = 51) and/or ultrasound (n = 64) studies. CONCLUSIONS: Clinical evaluations, including head and neck examination and imaging, are feasible in the context of a screening study for HPV-OPSCC.

Predictors of survival and time to progression following operative management of intramedullary spinal cord astrocytomas.

PURPOSE: Surgical resection is considered standard of care for primary intramedullary astrocytomas, but the infiltrative nature of these lesions often precludes complete resection without causing new post-operative neurologic deficits. Radiotherapy and chemotherapy serve as potential adjuvants, but high-quality data evaluating their efficacy are limited. Here we analyze the experience at a single comprehensive cancer center to identify independent predictors of postoperative overall and progression-free survival. METHODS: Data was collected on patient demographics, tumor characteristics, pre-operative presentation, resection extent, long-term survival, and tumor progression/recurrence. Kaplan-Meier curves modeled overall and progression-free survival. Univariable and multivariable accelerated failure time regressions were used to compute time ratios (TR) to determine predictors of survival. RESULTS: 94 patients were included, of which 58 (62%) were alive at last follow-up. On multivariable analysis, older age (TR = 0.98; p = 0.03), higher tumor grade (TR = 0.12; p < 0.01), preoperative back pain (TR = 0.45; p < 0.01), biopsy [vs GTR] (TR = 0.18; p = 0.02), and chemotherapy (TR = 0.34; p = 0.02) were significantly associated with poorer survival. Higher tumor grade (TR = 0.34; p = 0.02) and preoperative bowel dysfunction (TR = 0.31; p = 0.02) were significant predictors of shorter time to detection of tumor growth. CONCLUSION: Tumor grade and chemotherapy were associated with poorer survival and progression-free survival. Chemotherapy regimens were highly heterogeneous, and randomized trials are needed to determine if any optimal regimens exist. Additionally, GTR was associated with improved survival, and patients should be counseled about the benefits and risks of resection extent.

Utility of 18F-fluorodeoxyglucose positron emission tomography in presurgical evaluation of patients with epilepsy: A multicenter study.

OBJECTIVE: 18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) is widely used in presurgical assessment in patients with drug-resistant focal epilepsy (DRE) if magnetic resonance imaging (MRI) and scalp electroencephalography (EEG) do not localize the seizure onset zone or are discordant. METHODS: In this multicenter, retrospective observational cohort study, we included consecutive patients with DRE who had undergone FDG-PET as part of their presurgical workup. We assessed the utility of FDG-PET, which was defined as contributing to the decision-making process to refer for resection or intracranial EEG (iEEG) or to conclude surgery was not feasible. RESULTS: We included 951 patients in this study; 479 had temporal lobe epilepsy (TLE), 219 extratemporal epilepsy (ETLE), and 253 epilepsy of uncertain lobar origin. FDG-PET showed a distinct hypometabolism in 62% and was concordant with ictal EEG in 74% in TLE and in 56% in ETLE (p < .001). FDG-PET was useful in presurgical decision-making in 396 patients (47%) and most beneficial in TLE compared to ETLE (58% vs. 44%, p = .001). Overall, FDG-PET contributed to recommending resection in 78 cases (20%) and iEEG in 187 cases (47%); in 131 patients (33%), FDG-PET resulted in a conclusion that resection was not feasible. In TLE, seizure-freedom 1 year after surgery did not differ significantly (p = .48) between patients with negative MRI and EEG-PET concordance (n = 30, 65%) and those with positive MRI and concordant EEG (n = 46, 68%). In ETLE, half of patients with negative MRI and EEG-PET concordance and three quarters with positive MRI and concordant EEG were seizure-free postsurgery (n = 5 vs. n = 6, p = .28). SIGNIFICANCE: This is the largest reported cohort of patients with DRE who received presurgical FDG-PET, showing that FDG-PET is a useful diagnostic tool. MRI-negative and MRI-positive cases with concordant FDG-PET results (with either EEG or MRI) had a comparable outcome after surgery. These findings confirm the significance of FDG-PET in presurgical epilepsy diagnostics.

Predictors of Free Flap Volume Loss in Nonosseous Reconstruction of Head and Neck Oncologic Defects.

OBJECTIVES: Free tissue reconstruction of the head and neck must be initially overcorrected due to expected postoperative free flap volume loss, which can be accelerated by adjuvant radiation therapy. In this study, we aim to identify patient and treatment-specific factors that may significantly contribute to this phenomenon and translate these characteristics into a predictive model for expected percent free flap volume loss in a given patient. METHODS: Patients with a history of oral cavity and/or oropharyngeal cancer who underwent nonosseous free flap reconstruction were reviewed between January 2009 and November 2018 at a tertiary care center. Demographics/characteristics, total radiation dose, radiation fractionation (RF), and pre/postradiation free flap volume as evaluated by computed tomography imaging were collected. Free flap volume was measured by a fellowship-trained neuroradiologist in all cases. Only patients receiving adjuvant radiotherapy with available pre/postradiation imaging were included. Multivariable linear regression modeling for prediction of free flap volume loss was performed with optimization via stepwise elimination. RESULTS: Thirty patients were included for analysis. Mean flap volume loss was 42.7% ± 17.4%. The model predicted flap volume loss in a significant fashion (P = .004, R2 = 0.49) with a mean magnitude of error of 9.8% ± 7.5%. Age (ß = 0.01, P = .003) and RF (ß = -0.01, P = .009) were individual predictors of flap volume loss. CONCLUSIONS: Our model predicts percent free flap volume loss in a significant fashion. Age and RF are individual predictors of free flap volume loss, the latter being a novel finding that is also modifiable through hyperfractionation radiotherapy schedules.

Parotid Warthin's tumor: novel MR imaging score as diagnostic indicator.

OBJECTIVES: Despite known characteristic radiologic and clinical features, differentiation between Warthin's tumor (WT) and other parotid tumors remains challenging. The purpose of this study was to more precisely assess the MR imaging features of WT and to develop a scoring system combining the most specific characteristics. METHODS: A total of 208 patients with parotid gland tumors and presurgical MRI were included. Tumors were divided into 5 histological subtypes, and different MRI features were compared between groups. An MRI scoring test was developed including MR parameters that contributed significantly in distinguishing WT from other tumors. RESULTS: The best MRI features for differentiating between WTs from other tumors included bilaterality (P = 0.002), multifocality (P < 0.001), ADC values <905.1 (P < 0.001), and high signal intensity on T1-W images (P < 0.001). Six or more points on the 14-point scoring MRI scale was associated with an area under the curve of 0.99 (Accuracy of 98%), while a cut-off value of 7 indicated 100% specificity and 100% positive predictive value. CONCLUSIONS: Ill-defined margins, low T1-W signal, and location in the upper 2/3 of the parotid gland excluded WTs in 100% of cases. The proposed scoring method allows WTs to be distinguished from other tumors with high accuracy.

Imaging of the Postoperative Skull Base and Cerebellopontine Angle.

For pathologic conditions affecting the skull base and cerebellopontine angle, imaging techniques have advanced to assess for residual disease, disease progression, and postoperative complications. Knowledge regarding various surgical approaches of skull base tumor resection, expected postoperative appearance, and common postsurgical complications guides radiologic interpretation. Complexity of skull base anatomy, small size of the relevant structures, lack of familiarity with surgical techniques, and postsurgical changes confound radiologic evaluation. This article discusses the imaging techniques, surgical approaches, expected postoperative changes, and complications after surgery of the skull base, with emphasis on the cerebellopontine angle, anterior cranial fossa, and central skull base regions.

Pembrolizumab for patients with leptomeningeal metastasis from solid tumors: efficacy, safety, and cerebrospinal fluid biomarkers.

BACKGROUND: The benefit of immune checkpoint inhibitors (ICIs) in patients with leptomeningeal metastases (LMM) is unknown. METHODS: We undertook a phase II trial of pembrolizumab in patients with LMM from solid tumors. Eligible patients had radiologic/cytologic LMM and Eastern Cooperative Oncology Group performance status 0-1. Pembrolizumab was administered intravenously at 200 mg q3W until disease progression/unacceptable toxicity. The primary endpoint was central nervous system (CNS) response after four cycles, defined radiologically/cytologically/clinically. Serial cerebrospinal fluid (CSF) was assessed for tumor-derived DNA (t-DNA) aneuploidy and cytokines. RESULTS: Thirteen of a planned 16 patients were treated between April 2017 and December 2019. The study closed early for poor accrual. Median age was 57 years (range: 22-79). Sixty-two percent of patients had tumors not traditionally ICI-responsive (hormone-receptor (HR)-positive breast carcinoma=39%; high-grade glioma=23%), while 38% had ICI-responsive tumors (non-small cell lung cancer (NSCLC)=23%, head and neck carcinoma=8%, cutaneous squamous carcinoma (CSC)=8%). CNS response was observed in 38% of patients at 12 weeks (95% CI 13.9% to 68.4%) by pre-defined criteria and LM-RANO, and 2 achieved durable complete responses (CSC=1, overall survival (OS) 3+ years; NSCLC=1, OS 9 months). Median CNS progression-free survival and OS was 2.9 months (95% CI 1.3 to NR) and 4.9 months (95% CI 3.7 to NR), respectively. Grade 3+ treatment-related adverse events occurred in 15% of patients. Sensitivity for LMM detection by t-DNA and cytopathology was 84.6% (95% CI 54.6% to 98.1%) and 53.9% (95% CI 25.1% to 80.8%), respectively. Pre-therapy and on-therapy CSF cytokine analysis demonstrated complete responders clustered together. CONCLUSIONS: Pembrolizumab conferred a 38% CNS response rate in patients with LMM, a tolerable safety profile, and deep responses in selected patients with ICI-responsive tumors. CSF t-DNA may be sensitive for LMM detection, and immunologic subsets of CNS response warrant further study. TRIAL REGISTRATION NUMBER: NCT03091478.

Immune-mediated ototoxicity associated with immune checkpoint inhibitors in patients with melanoma.

Immune checkpoint inhibitors (ICIs) are associated with a range of organ-specific toxicities known as immune-related adverse events (irAEs). Immune-mediated ototoxicity from ICIs is poorly described. Herein, we describe the clinical presentation, diagnostic evaluation and management of six ICI-treated patients who developed immune-mediated ototoxicity, identified by a multidisciplinary immune-related toxicity team. This is the largest case series to date and identifies bilateral high-frequency hearing loss and tinnitus as the most common reported symptoms and can be associated with abnormal speech reception thresholds and word recognition ability on audiogram in select patients. We propose multidisciplinary evaluation of patients with suspected otologic irAEs including referral to otolaryngology, audiometry evaluation±magnetic resonance imaging for evaluation of suspected immune-mediated ototoxicity.

Nonepithelial Tumors of the Larynx: Single-Institution 13-Year Review with Radiologic-Pathologic Correlation.

Nonepithelial tumors of the larynx are rare and represent a minority of all laryngeal neoplasms. Imaging has an important role in the diagnosis, treatment planning, and surveillance of these entities. However, unfamiliarity with these neoplasms can cause diagnostic difficulties for radiologists, especially because many of the imaging findings are nonspecific. By using a systematic approach based on clinical history, patient age and gender, lesion location, endoscopic results, and specific imaging findings, the differential diagnosis can often be narrowed. These tumors typically affect the submucosal layer, so if a tumor has an intact mucosa at endoscopy, a nonepithelial neoplasm is the most likely diagnosis. Nonepithelial tumors of the larynx can arise from the laryngeal cartilage or muscle or from the surrounding lymphoid tissue or blood vessels. Consequently, imaging findings typically correspond to the specific cell type from which it originated. Recognizing specific features (eg, metaplastic bone formation, macroscopic fat, or enhancement pattern) can often help narrow the differential diagnosis. In addition, identification of noncircumscribed borders of the lesion and invasion of the adjacent structures is key to diagnosis of a malignant process rather than a benign neoplasm. Understanding the pathologic correlation is fundamental to understanding the radiologic manifestations and is ultimately crucial for differentiation of nonepithelial laryngeal neoplasms. Online supplemental material is available for this article. ©RSNA, 2020.

Automatic analysis of global spinal alignment from simple annotation of vertebral bodies.

Purpose: Measurement of global spinal alignment (GSA) is an important aspect of diagnosis and treatment evaluation for spinal deformity but is subject to a high level of inter-reader variability. Approach: Two methods for automatic GSA measurement are proposed to mitigate such variability and reduce the burden of manual measurements. Both approaches use vertebral labels in spine computed tomography (CT) as input: the first (EndSeg) segments vertebral endplates using input labels as seed points; and the second (SpNorm) computes a two-dimensional curvilinear fit to the input labels. Studies were performed to characterize the performance of EndSeg and SpNorm in comparison to manual GSA measurement by five clinicians, including measurements of proximal thoracic kyphosis, main thoracic kyphosis, and lumbar lordosis. Results: For the automatic methods, 93.8% of endplate angle estimates were within the inter-reader 95% confidence interval ( CI 95 ). All GSA measurements for the automatic methods were within the inter-reader CI 95 , and there was no statistically significant difference between automatic and manual methods. The SpNorm method appears particularly robust as it operates without segmentation. Conclusions: Such methods could improve the reproducibility and reliability of GSA measurements and are potentially suitable to applications in large datasets-e.g., for outcome assessment in surgical data science.

From presumed benign neck masses to delayed recognition of human papillomavirus-positive oropharyngeal cancer.

OBJECTIVES/HYPOTHESIS: To describe patients with delayed diagnosis of human papillomavirus-positive oropharyngeal squamous cell carcinoma (HPV-OPC) after initial incorrect diagnosis of branchial cleft cyst or nondiagnostic workup of unilateral neck mass. STUDY DESIGN: Retrospective case series. METHODS: Patients with delayed diagnosis of HPV-OPC after initial nondiagnostic workup for unilateral neck mass were eligible. Medical record abstraction was performed to describe clinical characteristics at initial presentation and later diagnosis of HPV-OPC. To estimate nodal growth rates, the short axis diameter of the lymph nodes was determined from imaging reports. RESULTS: Six patients met eligibility criteria. After a median interval of 42 months (range, 3 months-7 years) from initial presentation with unilateral neck mass, patients were diagnosed with HPV-OPC. At the time of HPV-OPC diagnosis, five were AJCC eighth edition overall stage I, and one was stage II. Primary tumors were T0 or T1 in the majority (83.3%, n = 5). Among five patients with available serial imaging, despite diagnostic delay, three of five still had a single lymph node without involvement of additional nodes, whereas the remaining two developed additional suspicious nodes (ipsilateral and contralateral). Two of five developed evidence of extranodal extension. Median lymph node growth was 9.5% per year (range, -6% to 32%). CONCLUSIONS: Although the natural history of HPV-OPC is not well understood, this case series suggests that it can be slow growing and mimic benign processes, leading to diagnostic delays. Adults presenting with neck masses should undergo complete diagnostic evaluation. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:392-397, 2020.

Computed tomography performance in predicting extranodal extension in HPV-positive oropharynx cancer.

OBJECTIVES: To evaluate the performance characteristics of seven predetermined imaging features on pretreatment computed tomography (CT) in identifying extranodal extension (ENE) in cervical lymph node metastases from human papillomavirus-positive oropharyngeal carcinoma (HPV-OPC). STUDY DESIGN: Retrospective study. METHODS: Seventy-three patients with HPV-OPC who underwent primary surgery and cervical lymph node dissection were included. Preoperative contrast-enhanced CT (cCT) imaging was evaluated by two radiologists blinded to pathological results. Each cCT was scored for seven imaging features of interest: 1) indistinct capsular contours, 2) irregular nodal margins, 3) perinodal fat stranding, 4) perinodal fat planes, 5) nodal necrosis, 6) intranodal cysts, and 7) nodal matting. Logistic regression was employed to determine radiologist-specific odds ratios (OR) of predicting ENE for each imaging feature and radiologist-specific receiver operating characteristics (sensitivity [Sn], specificity [Sp], area under the curve [AUC], positive predictive value [PPV], negative predictive value [NPV]) for each imaging feature. RESULTS: Thirty-two (44%) patients had ENE-positive lymph nodes. The presence of irregular margins (ORA = 12.3, 95% confidence interval [CI]A = 2.3-65.9; ORB = 7.0, 95% CIB = 1.4-36.3) and absence of perinodal fat plane (ORA = 6.8, 95% CIA = 2.0-23.3; ORB = 14.2, 95% CIB = 1.7-120.5) were significantly associated with ENE for each radiologist. Irregular nodal margin status was most specific for ENE (SnA = 45%, SpA = 94%, AUCA = 69%, PPVA = 82%, NPVA = 73%; SnB = 28%, SpB = 95%, AUCB = 61%, PPVB = 80%, NPVB = 64%). Absence of perinodal fat plane was most sensitive for ENE (SnA = 87%, SpA = 50%, AUCA = 69%, PPVA = 59%, NPVA = 62%; SnB = 96%, SpB = 34%, AUCB = 65%, PPVB = 53%, NPVB = 63%). CONCLUSIONS: Of the seven imaging features hypothesized to be associated with ENE-status, the presence of irregular nodal margins and absence of perinodal fat plane were the most specific and sensitive features, respectively. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:1479-1486, 2020.

Utility of the Vidian Canal in Endoscopic Skull Base Surgery: Detailed Anatomy and Relationship to the Internal Carotid Artery.

OBJECTIVE: To investigate key anatomic features of the vidian canal that have a critical role in planning and performing endoscopic skull base surgeries. METHODS: We reviewed skull base computed tomographic images of 640 consecutive subjects. Studies were analyzed in axial, coronal and sagittal planes. RESULTS: The mean (±SD) length of the vidian canal was 15.4 ± 2.0 mm in female subjects and 16.6 ± 1.7 mm in male subjects, and the difference between genders was statistically significant (P < 0.001). The most common rostral-caudal course of the vidian canal was medial to lateral and was followed by the straight course, tortuous course, and lateral-to-medial course. The frequency of pneumatization pattern from most common to least common was types 0, III, II and I. Of 342 evaluated sides, the vidian canal was located below the level of the anterior genu of petrous ICA in 303 (89%) sides, at same level with the anterior genu of petrous ICA in twenty-five(7%) sides, and above the level of the anterior genu of petrous ICA in fourteen(4.1%) sides. CONCLUSIONS: A variety of previously undefined features of the vidian canal that can alter the course of surgical procedure were defined. The position of the vidian canal with respect to the petrous internal carotid artery (ICA) was extensively described. From a surgical standpoint, a working room inferior and medial to the vidian canal might not always be a safe approach, because the vidian canal could be located superior to the level of the anterior genu of petrous ICA according to our findings in the present study.

Imaging of Patients with Head and Neck Cancer: From Staging to Surveillance.

In this review, the authors summarize the latest imaging methods and recommendations for each of the various steps in managing patients with head and neck cancer, from staging of disease to posttreatment surveillance. Because staging of head and neck cancers is different for various subsites of the head and neck, imaging is discussed separately for each. A separate discussion of imaging of perineural spread, occult primary tumors, and lymph nodes is followed by a discussion of paradigms for surveillance imaging in the posttreatment neck.

Clinical Translation of the LevelCheck Decision Support Algorithm for Target Localization in Spine Surgery.

Recent work has yielded a method for automatic labeling of vertebrae in intraoperative radiographs as an assistant to manual level counting. The method, called LevelCheck, previously demonstrated promise in phantom studies and retrospective studies. This study aims to: (#1) Analyze the effect of LevelCheck on accuracy and confidence of localization in two modes: (a) Independent Check (labels displayed after the surgeon's decision) and (b) Active Assistant (labels presented before the surgeon's decision). (#2) Assess the feasibility and utility of LevelCheck in the operating room. Two studies were conducted: a laboratory study investigating these two workflow implementations in a simulated operating environment with 5 surgeons, reviewing 62 cases selected from a dataset of radiographs exhibiting a challenge to vertebral localization; and a clinical study involving 20 patients undergoing spine surgery. In Study #1, the median localization error without assistance was 30.4% (IQR = 5.2%) due to the challenging nature of the cases. LevelCheck reduced the median error to 2.4% for both the Independent Check and Active Assistant modes (p < 0.01). Surgeons found LevelCheck to increase confidence in 91% of cases. Study #2 demonstrated accuracy in all cases. The algorithm runtime varied from 17 to 72 s in its current implementation. The algorithm was shown to be feasible, accurate, and to improve confidence during surgery.

Evaluating oropharyngeal carcinoma with transcervical ultrasound, CT, and MRI.

OBJECTIVE: To compare transcervical ultrasonography (US) to standard cross-sectional imaging for the visualization of human papillomavirus-related oropharyngeal cancer (HPV-OPC). MATERIALS AND METHODS: Patients with HPV-OPC and available standard imaging (CT and/or MRI) were identified in clinic and prospectively enrolled. US was performed to visualize the oropharynx and lymph nodes. Tumor characteristics across imaging modalities were evaluated (CT versus MRI, and US versus standard imaging (SI)). RESULTS: Forty-three patients were included. The overall blinded detection rates for CT and MRI were 83% and 71%, respectively. The unblinded detection rate for US was 98%. Agreement of tumor anatomic subsite was moderate for both CT vs MRI (κ = 0.59) and US vs SI (κ = 0.47). Comparison of tumor size by CT and MRI showed statistically significant correlations in craniocaudal (CC), anteroposterior (AP), and mediolateral (ML) dimensions (RhoCC = 0.51, pCC = 0.038; RhoAP = 0.81, pAP < 0.0001; RhoML = 0.57, pML = 0.012). Tumor size estimates by US and SI showed statistically significant correlations in CC and AP, but not ML (RhoCC = 0.60, pCC = 0.003; RhoAP = 0.71, pAP < 0.0001; RhoML = 0.30, pML = 0.08). Tumor volume estimates improved correlations between US and SI (Rho = 0.66, p < 0.0001). Stratification of US patients into early and late imaging studies demonstrated an increase in correlation strength from early (Rho = 0.32, p = 0.32) to late groups (Rho = 0.77, p < 0.0001) demonstrating that ultrasound accuracy improved with experience. CONCLUSIONS: Our findings suggest that transcervical ultrasonography is a sensitive and relatively accurate adjunct to standard imaging for the evaluation of oropharyngeal tumors. Its cost, portability, and potential for in-clinic and serial imaging render US an attractive modality to further develop for imaging oropharyngeal tumors.

Joubert syndrome: neuroimaging findings in 110 patients in correlation with cognitive function and genetic cause.

BACKGROUND: Joubert syndrome is a clinically and genetically heterogeneous ciliopathy. Neuroimaging findings have not been systematically evaluated in a large cohort of patients with Joubert syndrome in correlation with molecular genetic cause and cognitive function. METHODS: Brain MRI of 110 patients with Joubert syndrome was included in this study. A comprehensive evaluation of brain MRI studies for infratentorial and supratentorial morphological abnormalities was performed. Genetic cause was identified by whole-exome sequencing, and cognitive functions were assessed with age-appropriate neurocognitive tests in a subset of patients. RESULTS: The cerebellar hemispheres were enlarged in 18% of the patients, mimicking macrocerebellum. The posterior fossa was enlarged in 42% of the patients, resembling Dandy-Walker malformation. Abnormalities of the brainstem, such as protuberance at the ventral contour of the midbrain, were present in 66% of the patients. Abnormalities of the supratentorial brain were present in approximately one-third of the patients, most commonly malrotation of the hippocampi. Mild ventriculomegaly, which typically did not require shunting, was present in 23% of the patients. No correlation between neuroimaging findings and molecular genetic cause was apparent. A novel predictor of outcome was identified; the more severe the degree of vermis hypoplasia, the worse the neurodevelopmental outcome was. CONCLUSIONS: The spectrum of neuroimaging findings in Joubert syndrome is wide. Neuroimaging does not predict the genetic cause, but may predict the neurodevelopmental outcome. A high degree of vermis hypoplasia correlates with worse neurodevelopmental outcome. This finding is important for prognostic counselling in Joubert syndrome.

Imaging of Perineural Spread in Head and Neck Cancer.

Perineural spread (PNS) of tumor is a recognized pattern of metastasis occurring in the head and neck. Imaging plays a critical role in identifying PNS for adequate staging and treatment planning. Understanding the major branches and pathways of cranial nerves V and VII, key anatomic landmarks, interconnections between these nerves, and pearls and pitfalls of PNS imaging can aid in early detection, appropriate therapy, and the best possible chance for cure.

High Resolution Three-Dimensional MR Imaging of the Skull Base: Compartments, Boundaries, and Critical Structures.

High-resolution 3D MRI of the skull base allows for a more detailed and accurate assessment of normal anatomic structures as well as the location and extent of skull base pathologies than has previously been possible. This article describes the techniques employed for high-resolution skull base MRI including pre- and post-contrast constructive interference in the steady state (CISS) imaging and their utility for evaluation of the many small structures of the skull base, focusing on those regions and concepts most pertinent to localization of cranial nerve palsies and in providing pre-operative guidance and post-operative assessment. The concept of skull base compartments as a means of conceptualizing the various layers of the skull base and their importance in assessment of masses of the skull base is discussed.