Localisation of the petrous internal carotid artery relative to the vidian canal on computed tomography: a case-control study evaluating the impact of petroclival chondrosarcoma.

BACKGROUND: The vidian canal (VC) is normally a reliable anatomical landmark for locating the petrous internal carotid artery (pICA). This study determined the influence of petroclival chondrosarcoma on the relationship between the VC and pICA. METHODS: Nine patients (3 males, 6 females; median age 49) with petroclival chondrosarcoma, and depiction of the pICA on contrast-enhanced CT, were retrospectively studied. CT-based measurements were performed by two observers, both in the presence of the petroclival chondrosarcoma (case) and on the contralateral control side. The antero-posterior (AP) and craniocaudal (CC) measurements from the posterior VC to the pICA, whether the pICA was in the trajectory of the VC, and the coronal relationship of the pICA anterior genu with the VC were recorded. RESULTS: Chondrosarcoma usually displaced the pICA anteriorly (8/9 cases) and superiorly (6/9 cases) relative to the normal side with mean AP and CC measurements of 3.9 mm v 7.2 mm (p = 0.054) and 4.4 mm v 1.4 mm (p = 0.061). The VC trajectory less frequently intersected the pICA cross-section in the presence of chondrosarcoma however it was in the line of the eroded dorsal VC in one case. The anterior genu of the pICA was displaced more laterally by chondrosarcoma but usually remained superior to the VC. CONCLUSION: Petroclival chondrosarcoma variably influences the anatomical relationship between the VC and the pICA, hence requiring an individualised approach. The pICA is usually anterosuperiorly displaced, and the anterior genu remains superior to the VC, however it may be located in the line of the canal.

Role of Thyroidectomy in Recurrent Laryngeal Carcinoma.

OBJECTIVE: Management of recurrent laryngeal cancer presents a major challenge, and salvage laryngectomy is complicated by previous oncologic treatments. Thyroidectomy as part of salvage laryngectomy adds a nonnegligible degree of morbidity. The purpose of this study is to assess the rate of thyroid gland invasion in patients undergoing salvage laryngectomy to determine relevant predictive factors. STUDY DESIGN: Case series with chart review. SETTING: Department of Otorhinolaryngology, Head and Neck Surgery, Guy's Hospital, London, United Kingdom. METHODS: A retrospective review of patients undergoing salvage laryngectomy between 2009 and 2019 was undertaken. Preoperative cross-sectional imaging and histopathological analysis were performed to define evidence and predictors of thyroid gland invasion (TGI). RESULTS: Fifty-one patients had salvage laryngectomy. Histological evidence of TGI was found in 4 patients (7.8%). No significant relationship was found between histological TGI and subsite of primary carcinoma, degree of differentiation, T staging, or radiological TGI. Preoperative computed tomography had a high negative predictive value for TGI. CONCLUSION: Thyroidectomy should be carefully considered in patients undergoing salvage laryngectomy, and its extent should be defined on an individual basis. Total thyroidectomy should not routinely be performed in salvage laryngectomy or pharyngolaryngectomy in patients with no preoperative radiological evidence of TGI on cross-sectional imaging, unless there is intraoperative evidence of TGI.

Neurosurgical Approaches to the Skull Base: A Guide for the Radiologist.

Skull base surgery relies on the assessment of detailed neuroimaging studies to assist with surgical planning. We review typical neuroimaging features associated with common neurosurgical skull base approaches, highlighting relevant imaging anatomy and pertinent postoperative imaging appearances.

Imaging of the Vestibular Schwannoma: Diagnosis, Monitoring, and Treatment Planning.

Appropriate imaging strategies for the detection, treatment planning, and posttreatment monitoring of vestibular schwannomas will be discussed. The typical and variant imaging appearances of vestibular schwannomas, as well as the imaging features that should prompt consideration of differential diagnoses, will be illustrated. Understanding the natural history of vestibular schwannomas, optimal measurement and definition of tumour growth helps the radiologist evaluate for the failure of conservative management and requirement for surgery or radiotherapy. In order to determine the success of conservative management, the radiologist is required to understand the natural history of vestibular schwannomas and how tumour growth is defined. Finally, the imaging features which help guide appropriate treatment with surgery or radiotherapy will be highlighted, and the expected posttreatment imaging changes will be described.

Imaging of Developmental Skull Base Abnormalities.

The skull base is a critical structure in the craniofacial region, supporting the brain and vital facial structures in addition to serving as a passageway for important structures entering and exiting the cranial cavity. This paper will review and highlight some of the embryology, developmental anatomy, including ossification, and related abnormalities of the anterior, central and posterior skull base using illustrative cases and tables. Pathologies such as dermoids/epidermoids, cephaloceles, nasal gliomas, glioneuronal heterotopias, various notochordal remnants, persistent craniopharyngeal canal, teratomas, platybasia, basilar invagination, clival anomalies and Chiari malformations will be discussed. Developmental pearls and pitfalls will also be highlighted.

New and Advanced Magnetic Resonance Imaging Diagnostic Imaging Techniques in the Evaluation of Cranial Nerves and the Skull Base.

The skull base and cranial nerves are technically challenging to evaluate using magnetic resonance (MR) imaging, owing to a combination of anatomic complexity and artifacts. However, improvements in hardware, software and sequence development seek to address these challenges. This section will discuss cranial nerve imaging, with particular attention to the techniques, applications and limitations of MR neurography, diffusion tensor imaging and tractography. Advanced MR imaging techniques for skull base pathology will also be discussed, including diffusion-weighted imaging, perfusion and permeability imaging, with a particular focus on practical applications.

Utilization of SEMAC-VAT MRI for Improved Visualization of Posterior Fossa Structures in Patients With Cochlear Implants.

OBJECTIVE: The number of cochlear implant (CI) users is ever increasing worldwide, as is the utilization of magnetic resonance imaging (MRI) as a key diagnostic modality for pathology of the brain and surrounding structures. Despite advances in MRI compatibility with CI, metal artefact remains a significant issue that needs to be addressed. We test our hypothesis that the slice encoding for metal artefact correction and view angle tilting (SEMAC-VAT) metal artefact reduction technique improves demonstration of posterior fossa structures on MRI in CI recipients. STUDY DESIGN: A retrospective case review. SETTING: A tertiary referral hearing implant and skull base center. INTERVENTIONS: Dedicated MRI of the posterior fossa using T1 spin echo post-gadolinium sequences with and without the application of SEMAC-VAT in CI recipients. MAIN OUTCOME MEASURES: Extent and severity of the artefact and visualization of surrounding anatomic structures with and without the application of SEMAC-VAT, allowing for direct comparison. RESULTS: Eight CI recipients with nine CI devices were analyzed. We noted a significant reduction in signal void and improved visibility of the ipsilateral hemisphere in every case. Penumbra size increased although there was improved visibility through the penumbra. There was improved visualization of key intracranial structures, such as the ipsilateral internal auditory canal, cerebellopontine angle, cerebellar hemisphere, and brainstem. CONCLUSIONS: Application of SEMAC-VAT produces a significant reduction in signal void and improved visualization of key structures within the temporal bone and posterior cranial fossa in patients with CIs without the need for removal of the internal magnet.

Localization of the Sphenopalatine Ganglion Within the Pterygopalatine Fossa on Computed Tomography Angiography-A Potential Role in the Setting of Sphenopalatine Ganglion Microstimulator Implantation.

OBJECTIVES: A recent approach to treatment of cluster headaches (CH) employs a microstimulator device for on-demand neuromodulation of the sphenopalatine ganglion (SPG) during an acute CH attack. A precise anatomical localization of the SPG within the pterygopalatine fossa (PPF) is optimal in order to position the SPG electrode array. This study aims to investigate a novel approach for SPG localization using computed tomography angiographic studies (CTA). MATERIALS AND METHODS: Two independent observers identified the location of the SPG on 54 computed tomography angiographic studies (CTA) and measured its position relative to the vidian canal (VC). The qualitative confidence of identification, morphology, position within the PPF and its relation to vascular structures were also recorded. RESULTS: The SPG was detectable in 88% of cases with a variable position. The most frequent positions were superior (56%) and lateral (99%) relative to the VC with a mean (±SD) craniocaudal distance of 0.34 mm (±1.38) and a mean mediolateral distance of 3.04 mm (±1.2). However, in a considerable proportion of cases, the SPG was identified inferiorly to the VC (33%). Interobserver and intraobserver agreement for SPG location were moderate and strong respectively. CONCLUSIONS: Since localization of SPG on CTAs is feasible and reproducible, it has future clinical potential to aid placement, optimal positioning and individualized programming of the electrode array.

Head and neck manifestations of granulomatosis with polyangiitis.

Granulomatosis with polyangiitis is a rare autoimmune condition which causes respiratory tract granulomas, small to medium vessel vasculitis and renal disease. Head and neck manifestations are some of the most common presentations of the condition, with a significant proportion of patients experiencing sinonasal disease alone. The recognition of suggestive imaging findings, in combination with clinical history and serology, aids the diagnosis and appropriate treatment. This pictorial review describes and illustrates the head and neck imaging features of granulomatosis with polyangiitis, highlighting the range of CT and MRI findings of upper aerodigestive tract, orbital and skull-base disease. Recognition of the radiological appearances is of importance, since clinical presentations may be non-specific and limited disease may have negative serology. Imaging features may overlap with other pathologies so important differential diagnoses will be considered, and these are particularly relevant in the context of treatment resistance.

Recent advances in MRI of the head and neck, skull base and cranial nerves: new and evolving sequences, analyses and clinical applications.

MRI is an invaluable diagnostic tool in the investigation and management of patients with pathology of the head and neck. However, numerous technical challenges exist, owing to a combination of fine anatomical detail, complex geometry (that is subject to frequent motion) and susceptibility effects from both endogenous structures and exogenous implants. Over recent years, there have been rapid developments in several aspects of head and neck imaging including higher resolution, isotropic 3D sequences, diffusion-weighted and diffusion-tensor imaging as well as permeability and perfusion imaging. These have led to improvements in anatomic, dynamic and functional imaging. Further developments using contrast-enhanced 3D FLAIR for the delineation of endolymphatic structures and black bone imaging for osseous structures are opening new diagnostic avenues. Furthermore, technical advances in compressed sensing and metal artefact reduction have the capacity to improve imaging speed and quality, respectively. This review explores novel and evolving MRI sequences that can be employed to evaluate diseases of the head and neck, including the skull base.

Skull base ligamentous mineralisation: evaluation using computed tomography and a review of the clinical relevance.

OBJECTIVES: To determine the frequency, morphologic and demographic characteristics, and clinical relevance of the mineralisation of six skull base ligaments (interclinoid, caroticoclinoid, petrosphenoid, posterior petroclinoid, pterygospinous, and pterygoalar). METHODS: This is a retrospective review of 240 CT scans of the paranasal sinuses (ages 6-80 years). A limited systematic review was performed primarily using Embase and Medline databases. RESULTS: Ligamentous mineralisation was well delineated on CT and occurred at ≥ 1 location in 58.3% of patients. There was a nonsignificant trend towards a greater incidence with advancing age. The interclinoid and posterior petroclinoid ligaments were most commonly mineralised (22.1% and 18.3%, respectively); the petrosphenoid and pterygoalar ligaments were least frequently mineralised (10.8% and 6.3%, respectively). The mean age of patients with posterior petroclinoid mineralisation was significantly greater than those with interclinoid and petrosphenoid mineralisation and was not seen in patients aged 6-20 years. The literature review highlighted the clinically relevant potential for mineralised ligaments to cause barriers to surgical access (e.g. to the foramen ovale), increase the risk of neurovascular injury during surgery at the skull base (e.g. during anterior clinoidectomy), and predispose to neural impingement. CONCLUSIONS: Skull base ligamentous mineralisation is commonly encountered on CT imaging. Given the potentially significant clinical implications, an understanding of the morphological appearances is of importance to those planning interventions at the skull base. To the authors' knowledge, this study is the first to comprehensively evaluate such a wide range of skull base ligaments using CT. For some ligaments, the incidence on CT has not been previously described.

The characteristics of 76 atypical neurofibromas as precursors to neurofibromatosis 1 associated malignant peripheral nerve sheath tumors.

Background: Neurofibromatosis 1 (NF1) leads to the development of benign and malignant peripheral nerve sheath tumors (MPNST). MPNST have been described to develop in preexisting benign plexiform neurofibromas (PN) and have a poor prognosis. Atypical neurofibromas (ANF) were recently described as precursor lesions for MPNST, making early detection and management of ANF a possible strategy to prevent MPNST. We aimed to clinically characterize ANF and identify management approaches. Methods: We analyzed clinical, imaging, and pathology findings of all patients with NF1 and ANF at 3 institutions. Results: Sixty-three patients had 76 ANF (32M/31F; median age 27.1 y). On MRI, most ANF appeared as distinct nodular lesions and were 18F-fluorodeoxyglucose (FDG) avid. Forty-six ANF were associated with pain, 19 with motor weakness, 45 were palpable or visible, and 13 had no clinical signs. Completely resected ANF (N = 57) have not recurred (median follow-up, 4.1 y; range, 0-14 y). Four ANF transformed into MPNST and 17 patients had a history of MPNST in a different location than was their ANF. Conclusions: Growth of distinct nodular lesions, pain, and FDG-PET avidity should raise concern for ANF in NF1. Patients with ANF are at greater risk for development of MPNST. Complete resection of ANF may prevent development of MPNST.

Aneurysms in neurofibromatosis type 2: Evidence for vasculopathy?

There have been anecdotal reports of vasculopathy associated with Neurofibromatosis Type 2 (NF2). Given the increasing use of bevacizumab, a vascular endothelial growth factor inhibitor which results in an increased risk of bleeding, it is important to ascertain if there is a predisposition to vascular abnormalities in NF2. In our unit NF2 patients undergo annual MRI brain and internal auditory meatus imaging. We noted incidental intracranial aneurysms in some patients and sought to determine the prevalence of intracranial aneurysms in our cohort of NF2 patients. We conducted a retrospective audit of the MRI images of 104 NF2 patients from 2014 to 2016. Axial T2 brain MRI images were assessed for vascular abnormalities by two neuroradiologists blinded to patient's clinical details. Intracranial aneurysms were detected in four patients and an aneurysm clip related to previous surgery was noted in one additional patient. Using standard MRI imaging sequences alone we provide evidence of intracranial aneurysms in 4.4% of our cohort. This compares with an estimated overall prevalence of 3% in the general population. We discuss these findings as well as other evidence for a vasculopathy associated with NF2.

Diagnostic efficacy and therapeutic impact of computed tomography in the evaluation of clinically suspected otosclerosis.

OBJECTIVE: To assess the diagnostic efficacy and therapeutic impact of CT in evaluating patients with clinically suspected otosclerosis. METHODS: CT scans performed over a 5-year period for clinically suspected otosclerosis were retrospectively reviewed. CT diagnoses were correlated with subsequent surgical management. For otosclerosis positive cases, clinically significant extensions of otosclerosis were correlated with audiometry and the diagnosis was correlated with surgical findings. RESULTS: Of 259 CT studies, 46 % of patients were positive, 49 % negative and 5 % equivocal for otosclerosis. A relevant alternative CT diagnosis was evident in 33 % of the negative studies. One targeted surgery was performed for every four CT studies. CT outcome influenced the decision to perform stapedectomy in 41 % CT-positive versus 4 % CT-negative patients. CT-positive ears for otosclerosis could not be predicted from baseline clinical or audiometric criteria. Those with endosteal extension demonstrated lower bone conduction thresholds presurgically. The positive predictive value of CT diagnosis of otosclerosis was 100 %. CONCLUSIONS: CT demonstrated a high rate of clinically relevant diagnoses in both CT-positive and -negative for otosclerosis patients, and this frequently influenced surgical management. CT also added value by demonstrating relevant extensions of the otosclerotic foci, some of which were predictive of audiometric parameters. KEY POINTS: • CT demonstrates a high rate of alternative diagnoses in suspected otosclerosis, 1:3. • CT results in a high rate of targeted surgery in suspected otosclerosis, 1:4. • CT prevents exploratory surgery in suspected otosclerosis. • Endosteal extension of otosclerosis is predictive of lower bone conduction tresholds presurgically. • The PPV of CT diagnosis of otosclerosis was 100 %.

The Skull Base in the Evaluation of Sinonasal Disease: Role of Computed Tomography and MR Imaging.

The median anterior and central skull base forms an interface between the sinonasal and intracranial compartments. Due to the proximity of the intracranial structures, skull base involvement is a key assessment when evaluating the spread of sinonasal disease. This review describes the pertinent anatomy and the role of computed tomography and MR imaging in evaluating the median anterior and central skull base. The imaging appearances of pathologic processes that involve and traverse the skull base between the sinonasal and intracranial compartments are discussed and illustrated.

Role of thyroidectomy in advanced laryngeal and pharyngolaryngeal carcinoma.

OBJECTIVE: Total thyroidectomy (TThy) or hemithyroidectomy (HThy) in conjunction with a total laryngectomy (TL) or pharyngolaryngectomy (PL) for laryngeal carcinoma often results in hypothyroidism requiring life-long thyroid hormone replacement. The aims were to determine the incidence of thyroid gland (TG) invasion in patients undergoing TL or TPL with TThy or HThy for laryngeal or hypopharyngeal carcinoma and to assess predicative factors. STUDY DESIGN: Case series with chart review. SETTING: Guy's Hospital, London, UK. SUBJECTS AND METHODS: Thirty-five patients from 2004 to 2008 were reviewed. Specimens were examined to determine the incidence of TG invasion and predicative factors. Preoperative imaging was reviewed to assess the radiological evidence of TG invasion. RESULTS: TL and TThy were performed in 19 patients, TL and HThy in three patients, and PL and TThy in 13 patients. Surgery was performed for primary and recurrent carcinoma in 28 and eight patients, respectively. Histological evidence of invasion of the TG was found in three patients (8.5%). No significant relationship was found between TG invasion and patient's sex, subsite of primary carcinoma, stage of primary disease at surgery, degree of differentiation, or the presence of subglottic extension. In addition, no significant relationship was found between the presence of TG invasion and recurrent disease. Definite evidence of radiological invasion of the TG was seen in only one patient. CONCLUSIONS: Invasion of the TG in patients undergoing TL or TPL is a rare event and limits the need for TThy in most cases.

Hippocampal volume and cognitive function in anorexia nervosa.

We hypothesised that hippocampal volume would be reduced in underweight anorexia nervosa (AN) and associated with impaired hippocampus-dependent cognitive function. Hippocampal and whole brain volumes were measured in 16 women with AN and 16 matched healthy women using magnetic resonance imaging (MRI) and a manual tracing method. Participants also completed the Doors and People Test of hippocampus-dependent memory and an IQ test. After adjustment for total cerebral volume, there was significant bilateral reduction in hippocampal volume in the AN group (8.2% right; 7.5% left). There was no evidence of impaired hippocampus-dependent cognitive function and no evidence of a relationship between hippocampal volume and clinical features of AN. The reduced hippocampal volume in anorexia nervosa is not associated with changes in cognitive function. To understand the cause and consequence of hippocampal size and function, it will be important to integrate endocrine, neuropsychological and neuroimaging studies.