Citations

Abstract Background and Purpose Artifact from cochlear implant electrodes degrades image resolution on CT. Here, we describe the use of coregistered pre‐ and postoperative CT images to reduce metallic artifact from the electrodes to assess its position more accurately within the cochlear lumen. Methods Pre‐ and postoperative CTs were reviewed after coregistration/overlay of both exams. Images were evaluated by two neuroradiologists for scalar location of electrodes tip (± scalar translocation), tip fold over, and angular depth of insertion. Results Thirty‐four patients were included in the final cohort. Transscalar migration was present in three (8.8%) cases (one case demonstrated tip fold over), with initial disagreement regarding transscalar migration in 1 out of 34 patients (2.9%). Agreement regarding depth of insertion was present in 31 (91.1%) cases. Five‐point Likert scales were used to compare the ability to resolve the proximity of electrodes to the lateral/outer cochlear wall without and with overlay, which is a qualitative measure of artifact from the array. Likert scores showed definitive benefit of metal artifact reduction using overlayed images with an average score of 4.34. Conclusion This study demonstrates a novel technique of using fused coregistration of pre‐ and postoperative CTs for the purpose of artifact reduction/electrode localization. It is anticipated that this technique will permit more accurate localization of the electrodes for improvement in surgical technique and electrode array design.

Background Computed tomography (CT) angiography collateral score (CTA-CS) is an important clinical outcome predictor following mechanical thrombectomy for ischemic stroke with large vessel occlusion (LVO). The present multireader study aimed to evaluate the performance of e-CTA software for automated assistance in CTA-CS scoring. Materials and Methods Brain CTA images of 56 patients with anterior LVO were retrospectively processed. Twelve readers of various clinical training, including junior neuroradiologists, senior neuroradiologists, and neurologists graded collateral flow using visual CTA-CS scale in two sessions separated by a washout period. Reference standard was the consensus of three expert readers. Duration of reading time, inter-rater reliability, and statistical comparison of readers’ performance metrics were analyzed between the e-CTA assisted and unassisted sessions. Results e-CTA assistance resulted in significant increase in mean accuracy (58.6% to 67.5%, p = 0.003), mean F1 score (0.574 to 0.676, p = 0.002), mean precision (58.8% to 68%, p = 0.007), and mean recall (58.7% to 69.9%, p = 0.002), especially with slight filling deficit (CTA-CS 2 and 3). Mean reading time was reduced across all readers (103.4 to 59.7 s, p = 0.001), and inter-rater agreement in CTA-CS assessment was increased (Krippendorff's alpha 0.366 to 0.676). Optimized occlusion laterality detection was also noted with mean accuracy (92.9% to 96.8%, p = 0.009). Conclusion Automated assistance for CTA-CS using e-CTA software provided helpful decision support for readers in terms of improving scoring accuracy and reading efficiency for physicians with a range of experience and training backgrounds and leading to significant improvements in inter-rater agreement.

Abstract Background Carotid intraplaque hemorrhage (IPH) is considered a strong marker of histologically defined plaque vulnerability leading to cerebrovascular ischemic events. Cerebral microbleeds (CMBs) represent hemorrhage-prone small vessel disease and they are a common finding on brain MRI in patients with cerebrovascular disease. However, the potential mechanism and the risk for CMBs are not clear. The characteristics of carotid lesions have been considered relevant in the relationship between carotid artery atherosclerosis and the presence of CMBs. The potential association between carotid IPH histologically defined and CMBs has not been investigated yet. Purpose We have previously reported the prevalence of IPH in patients with non-obstructive carotid disease in patients who underwent carotid endarterectomy (CEA). In this study, we aimed to investigate whether the presence and the extent of carotid IPH are related to the existence of CMBs. We hypothesized that patients with carotid IPH would have a higher risk of CMBs. Methods This retrospective study enrolled 101 consecutive patients undergoing CEA with symptomatic (including ischemic stroke, TIA, and amaurosis fugax) or asymptomatic ipsilateral carotid artery disease. Carotid plaque specimens were collected at CEA from all the patients and stained with Movat Pentachrome to identify the presence and the extent (%) of IPH. Neck CTA was obtained to measure the degree of carotid stenosis. Brain MRI was pre-surgically performed and CMBs were studied using T2*-weighted gradient-recalled echo (GRE) or susceptibility-weighted imaging (SWI) sequence. The CMBs were counted and localized. Clinical and biochemical data, comorbidities, and medications were recorded. The association between carotid IPH and CMBs was examined adjusted for other risk factors. Results The presence of carotid IPH was in 57 (56.4%) patients. CMBs were more observed in patients with carotid IPH compared to those without IPH [19 (33.3%) vs 5 (11.4%); p=0.010]. Logistic regression analysis demonstrated an association between the extent of IPH in the carotid atheroma and the presence of CMBs [OR 1.051 (95% CI 1.012–1.090); p=0.009]. Moreover, the carotid IPH extent was associated with the number of CMBs (p=0.004). In patients with CMBs, the median degree of ipsilateral carotid stenosis was 40% (35–65%) and it was 70% (50–80%) in those without CMBs, with a significant difference between the two groups (p=0.049). Conclusions In patients undergoing CEA, the histologically defined presence of carotid IPH and its extent are associated with CMBs on brain MR imaging. CMBs may be a potential mechanism for cerebrovascular events in patients with carotid atherosclerotic IPH and they may be an imaging marker that can distinguish the severity of the carotid artery disease. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Mayo Clinic Foundation

Background and Purpose After cochlear implantation, metallic artifact can obscure nearby structures on CT images, which is problematic in patients with facial nerve stimulation (FNS). This study evaluated the usefulness of co-registered pre- and post-operative examinations to evaluate the cochlear implant and adjacent structures. Materials and Methods A retrospective review was completed of consecutive patients that underwent CT imaging of the temporal bone before and after placement of a cochlear implant. Two blinded neuroradiologists independently reviewed all available examinations. All examinations were assessed for the presence or absence of dehiscence of the osseous ridge between the cochlea and facial nerve canal (FNC). Pre-operative and fused pre- and post-operative examinations were compared in their ability to visualize the osseous ridge using a 5-point Likert scale (ranging from 1 = unfused images were substantially superior to 5 = fused images were substantially superior). The electrode closest to the FNC were noted. Results Of 34 included patients, 13 (38.2%) were female and 21 (61.8%) were male; average age was 72.2. Seven patients (20.6%) had frank dehiscence between the cochlea and FNC. Fused images were superior to the post-operative study alone for assessing the integrity of the osseous partition between the cochlea and FNC and for reducing artifact from the electrode array (average Likert scores for both reviewers were 4.4 and 4.7). There was good agreement between reviewers in noting electrode closest to the FNC (concordance correlation coefficient=0.82). Conclusions Following cochlear implantation, co-registered pre- and post-operative CT images are superior to conventional images in assessing the anatomic relationship between the cochlea and FNC.

Objectives The aim of this study is to introduce the infrapedicular approach to CT-guided spine interventions, a specialized technique that can safely expand the scope of spine lesions amenable to treatment, and to document the feasibility in a variety of procedural scenarios to the extent possible with a retrospective case series. Methods Data from 24 cases performed at a single institution over a 10-year period were retrospectively reviewed to assess the technical feasibility and safety profile of the technique. Results The infrapedicular approach enabled a technically satisfactory procedural result in 24 cases (mean age 63.9 years, range 35–83 years). Two peri-procedural complications occurred, including a small pneumothorax and a cerebrospinal fluid leak, both of which resolved with conservative treatment. No lasting injurious effects or additional complications were identified. The infrapedicular approach was found to be particularly useful in multiple technically challenging scenarios: it facilitates access to lesions in the inferior vertebral body, allows biopsy, cement augmentation, or ablation of high thoracic lesions difficult to treat due to limitations of steep angulation of fluoroscopy and CT scanners, and enables treatment of large lesions by using multiple overlapping probes.

Background and purpose Radiation therapy is an important component of treatment in patients with malignancies of the head, neck, and spine. However, radiation to these regions has well-known potential side effects, many of which can be encountered on imaging. In this manuscript, we review selected radiographic manifestations of therapeutic radiation to the head, neck, and spine that may be encountered in the practice of radiology. Methods We conducted an extensive literature review of known complications of radiation therapy in the head, neck, and spine. We excluded intracranial and pulmonary radiation effects from our search. We selected complications that had salient, recognizable imaging findings. We searched our imaging database for illustrative examples of these complications. Results Based on our initial literature search and imaging database review, we selected cases of radiation-induced tumors, radiation tissue necrosis (osteoradionecrosis and soft tissue necrosis), carotid stenosis and blowout secondary to radiation, enlarging thyroglossal duct cysts, radiation myelopathy, and radiation-induced vertebral compression fractures. Conclusions We describe the clinical and imaging features of selected sequelae of radiation therapy to the head, neck, and spine, with a focus on those with characteristic imaging findings that can be instrumental in helping to make the diagnosis. Knowledge of these entities and their imaging findings is crucial for accurate diagnosis. Not only do radiologists play a key role in early detection of these entities, but many of these entities can be misinterpreted if one is not familiar with them.

In the evaluation of embolic strokes of undetermined source, great emphasis is often placed on cardiovascular disease, namely on atrial fibrillation. Other pathophysiologic mechanisms, however, may also be involved. Carotid artery intraplaque hemorrhage (IPH)—the presence of blood components within an atheromatous plaque—has become increasingly recognized as a possible etiologic mechanism in some cryptogenic strokes. IPH is a marker of plaque instability and is associated with ipsilateral neurologic ischemic events, even in nonstenotic carotid plaques. As recognition of carotid IPH as an etiology of embolic strokes has grown, so too has the complexity with which such patients are evaluated and treated, particularly because overlaps exist in the risk factors for atrial fibrillation and IPH. In this article, we review what is currently known about carotid IPH and how this clinical entity should be approached in the context of the evaluation of embolic strokes of undetermined source.

Object We sought to determine the safety and efficacy in secondary stroke prevention of carotid endarterectomy (CEA) in patients with symptomatic non-stenotic carotid artery disease (SyNC). Methods This was a single-centre retrospective case series. All patients who underwent CEA for unilateral anterior circulation cerebrovascular events with ipsilateral <50% carotid stenosis from 2002 to 2020 were included. Imaging hallmarks including the degree of luminal stenosis and the presence of various vulnerable plaque characteristics (eg, intraplaque haemorrhage (IPH) on MR angiography, ulceration or low-density plaque on CT angiography) were assessed. The presence of vulnerable plaque characteristics was compared between arteries ipsilateral to the ischaemic event and contralateral arteries. The prevalence of perioperative/intraoperative complications, as well as recurrent ischaemic events at follow-up was determined. Results Thirty-two patients were included in the analysis, of which 25.0% were female. Carotid arteries ipsilateral to an ischaemic event had a significantly higher prevalence of IPH when compared with contralateral arteries (80.0% vs 0.0%; p<0.001). There were no intraoperative complications. One patient (3.1%) developed symptoms of transient ipsilateral ischaemia 1 day following CEA which resolved without treatment. In a median follow-up of 18.0 months (IQR 5.0–36.0), only one patient (3.1%) experienced a transient neurologic deficit with complete resolution (annualised rate of recurrent stroke after CEA of 1.5% for a total follow-up of 788 patient-months following CEA). All other patients (31/32, 96.9%) were free of recurrent ischaemic events. Conclusion CEA appears to be safe and well-tolerated in patients with SyNC. Additional studies with larger cohorts and longer follow-up intervals are needed in order to determine the role of CEA in this patient population.