Effect of anesthetic strategies on distal stroke thrombectomy in the anterior and posterior cerebral artery.

BACKGROUND: Numerous questions regarding procedural details of distal stroke thrombectomy remain unanswered. This study assesses the effect of anesthetic strategies on procedural, clinical and safety outcomes following thrombectomy for distal medium vessel occlusions (DMVOs). METHODS: Patients with isolated DMVO stroke from the TOPMOST registry were analyzed with regard to anesthetic strategies (ie, conscious sedation (CS), local (LA) or general anesthesia (GA)). Occlusions were in the P2/P3 or A2-A4 segments of the posterior and anterior cerebral arteries (PCA and ACA), respectively. The primary endpoint was the rate of complete reperfusion (modified Thrombolysis in Cerebral Infarction score 3) and the secondary endpoint was the rate of modified Rankin Scale score 0-1. Safety endpoints were the occurrence of symptomatic intracranial hemorrhage and mortality. RESULTS: Overall, 233 patients were included. The median age was 75 years (range 64-82), 50.6% (n=118) were female, and the baseline National Institutes of Health Stroke Scale score was 8 (IQR 4-12). DMVOs were in the PCA in 59.7% (n=139) and in the ACA in 40.3% (n=94). Thrombectomy was performed under LA±CS (51.1%, n=119) and GA (48.9%, n=114). Complete reperfusion was reached in 73.9% (n=88) and 71.9% (n=82) in the LA±CS and GA groups, respectively (P=0.729). In subgroup analysis, thrombectomy for ACA DMVO favored GA over LA±CS (aOR 3.07, 95% CI 1.24 to 7.57, P=0.015). Rates of secondary and safety outcomes were similar in the LA±CS and GA groups. CONCLUSION: LA±CS compared with GA resulted in similar reperfusion rates after thrombectomy for DMVO stroke of the ACA and PCA. GA may facilitate achieving complete reperfusion in DMVO stroke of the ACA. Safety and functional long-term outcomes were comparable in both groups.

Opsoclonus-Myoclonus-Ataxia Syndrome Due to Covid-19.

Opsoclonus-myoclonus syndrome (OMS) as a rare neurological encephalopathic entity associated with non-specific infections or cancer processes has been repeatedly described in the setting of SARS-CoV-2 infection. We report a case of a 53-year-old man with SARS-CoV-2 infection, who developed clinical features of opsoclonus-myoclonus ataxia syndrome including cognitive impairments with a prolonged course of disease. Of particular note, cerebrospinal fluid (CSF) analysis revealed the production of myelin oligodendrocyte glycoprotein (MOG) antibodies, suggesting an underlying neuroimmunological mechanism associated with infection with the novel SARS-CoV-2 virus.

Quantitative Diffusion-Weighted MRI of Neuroblastoma.

Neuroblastoma is the most common extracranial, malignant, solid tumor found in children. In more than one-third of cases, the tumor is in an advanced stage, with limited resectability. The treatment options include resection, with or without (neo-/) adjuvant therapy, and conservative therapy, the latter even with curative intent. Contrast-enhanced MRI is used for staging and therapy monitoring. Diffusion-weighted imaging (DWI) is often included. DWI allows for a calculation of the apparent diffusion coefficient (ADC) for quantitative assessment. Histological tumor characteristics can be derived from ADC maps. Monitoring the response to treatment is possible using ADC maps, with an increase in ADC values in cases of a response to therapy. Changes in the ADC value precede volume reduction. The usual criteria for determining the response to therapy can therefore be supplemented by ADC values. While these changes have been observed in neuroblastoma, early changes in the ADC value in response to therapy are less well described. In this study, we evaluated whether there is an early change in the ADC values in neuroblastoma under therapy; if this change depends on the form of therapy; and whether this change may serve as a prognostic marker. We retrospectively evaluated neuroblastoma cases treated in our institution between June 2007 and August 2014. The examinations were grouped as 'prestaging'; 'intermediate staging'; 'final staging'; and 'follow-up'. A classification of "progress", "stable disease", or "regress" was made. For the determination of ADC values, regions of interest were drawn along the borders of all tumor manifestations. To calculate ADC changes (∆ADC), the respective MRI of the prestaging was used as a reference point or, in the case of therapies that took place directly after previous therapies, the associated previous staging. In the follow-up examinations, the previous examination was used as a reference point. The ∆ADC were grouped into ∆ADCregress for regressive disease, ∆ADCstable for stable disease, and ∆ADC for progressive disease. In addition, examinations at 60 to 120 days from the baseline were grouped as er∆ADCregress, er∆ADCstable, and er∆ADCprogress. Any differences were tested for significance using the Mann-Whitney test (level of significance: p < 0.05). In total, 34 patients with 40 evaluable tumor manifestations and 121 diffusion-weighted MRI examinations were finally included. Twenty-seven patients had INSS stage IV neuroblastoma, and seven had INSS stage III neuroblastoma. A positive N-Myc expression was found in 11 tumor diseases, and 17 patients tested negative for N-Myc (with six cases having no information). 26 patients were assigned to the high-risk group according to INRG and eight patients to the intermediate-risk group. There was a significant difference in mean ADC values from the high-risk group compared to those from the intermediate-risk group, according to INRG. The differences between the mean ∆ADC values (absolute and percentage) according to the course of the disease were significant: between ∆ADCregress and ∆ADCstable, between ∆ADCprogress and ∆ADCstable, as well as between ∆ADCregress and ∆ADCprogress. The differences between the mean er∆ADC values (absolute and percentage) according to the course of the disease were significant: between er∆ADCregress and er∆ADCstable, as well as between er∆ADCregress and er∆ADCprogress. Forms of therapy, N-Myc status, and risk groups showed no further significant differences in mean ADC values and ∆ADC/er∆ADC. A clear connection between the ADC changes and the response to therapy could be demonstrated. This held true even within the first 120 days after the start of therapy: an increase in the ADC value corresponds to a probable response to therapy, while a decrease predicts progression. Minimal or no changes were seen in cases of stable disease.

Thrombectomy for secondary distal, medium vessel occlusions of the posterior circulation: seeking complete reperfusion.

BACKGROUND: Whether to approach distal occlusions endovascularly or not in medium-sized vessels secondary to proximal large vessel occlusion stroke remains unanswered. OBJECTIVE: To investigates the technical feasibility and safety of thrombectomy for secondary posterior circulation distal, medium vessel occlusions (DMVO). METHODS: TOPMOST (Treatment fOr Primary Medium vessel Occlusion STroke) is an international, retrospective, multicenter, observational registry of patients treated for distal cerebral artery occlusions. This study subanalysis endovascularly treated occlusions of the posterior cerebral artery in the P2 and P3 segment secondary preprocedural or periprocedural thrombus migration between January 2014 and June 2020. Technical feasibility was evaluated with the modified Thrombolysis in Cerebral Infarction (mTICI) scale. Procedural safety was assessed by the occurrence of symptomatic intracranial hemorrhage (sICH) and intervention-related serious adverse events. RESULTS: Among 71 patients with secondary posterior circulation DMVO who met the inclusion criteria, occlusions were present in 80.3% (57/71) located in the P2 segment and in 19.7% (14/71) in the P3 segment. Periprocedural migration occurred in 54.9% (39/71) and preprocedural migration in 45.1% (32/71) of cases. The first reperfusion attempt led in 38% (27/71) of all cases to mTICI 3. On multivariable logistic regression analysis, increased numbers of reperfusion attempts (adjusted odds ratio (aOR)=0.39, 95% CI 0.29 to 0.88, p=0.009) and preprocedural migration (aOR=4.70, 95% CI,1.35 to 16.35, p=0.015) were significantly associated with mTICI 3. sICH occurred in 2.8% (2/71). CONCLUSION: Thrombectomy for secondary posterior circulation DMVO seems to be safe and technically feasible. Even though thrombi that have migrated preprocedurally may be easier to retract, successful reperfusion can be achieved in the majority of patients with secondary DMVO of the P2 and P3 segment.

Mapping Cochlear Duct Length to Electrically Evoked Compound Action Potentials in Cochlear Implantation.

OBJECTIVE: Objective measurements may assist in indicating cochlear implants and in predicting outcomes of cochlear implantation surgery. Using electrically evoked compound action potentials (ECAP), information about the function of the auditory nerve can be obtained by analyzing responses to electrical stimulation transmitted and derived by the recording electrode. The aim of this study was to determine whether ECAP characteristics differ depending on the stimulated intracochlear region and the size of the cochlea. STUDY DESIGN: Retrospective cohort study. SETTING: University Medical center, tertiary academic referral center. PATIENTS: Patients undergoing cochlear implant surgery between 2015 and 2018. INTERVENTION: Cochlear implantation with FLEXsoft electrode arrays (length 31.5 mm, 12 stimulating channels). MAIN OUTCOME MEASURES: The cochlear duct length (CDL) and the cochlear coverage (CC) were measured using a new computed tomography-based software and correlated to the postoperative speech performance. Additionally, ECAP were measured and associated to the CDL. RESULTS: A total of 59 ears of 53 cochlear implant users with a mean age of 63.6 (SD 14.9) years were included. The mean estimated CDL was 35.0 (SD 2.2) mm. The mean CC was 90.3% (SD 5.5%). A total of 4,873 ECAP were measured. A statistically significant, moderate, negative correlation between the ECAP slope and the site of stimulation was found (r = -0.29, 95% confidence interval: -0.32 to -0.27, p < 0.0001). No correlation between the CC and the speech performance was found (r = -0.08, 95% confidence interval: -0.33 to 0.18 p = 0.52). CONCLUSION: ECAP slopes seem to be a reliable tool to identify the electrode's position inside the cochlea and also showed correlations to the anatomy of the patient. A combination of objective measurements such as anatomical parameters and ECAPs are helpful to assist the postoperative fitting and are promising tools to improve patient care.

Artificial Intelligence and Big Data. / Künstliche Intelligenz und Big Data.

Medical images play an important role in ophthalmology and radiology. Medical image analysis has greatly benefited from the application of "deep learning" techniques in clinical and experimental radiology. Clinical applications and their relevance for radiological imaging in ophthalmology are presented.

Differentiation of retropharyngeal calcific tendinitis and retropharyngeal abscess: a case series and review of the literature.

INTRODUCTION: Retropharyngeal calcific tendinitis (RCT) is a self-limiting aseptic inflammation of the tendon of the longus colli muscle, which can be clinically and radiologically misdiagnosed as abscess formation. This is a particular challenge for ENT specialists. However, articles about RCT are highly underrepresented in ENT journals and existing articles in ENT journals almost exclusively report overtreatment. METHODS: This study presents five patients, in which the diagnosis of RCT was delayed and of which one patient underwent incision and draining of a suspected retropharyngeal abscess under general anesthesia. In addition, the literature on the reported cases of RCT, between 1990 and 2020 was reviewed. For each case, epidemiological characteristics, complaints on presentation, symptoms, imaging and laboratory finding and treatment were summarized and compared to our own findings. RESULTS: In all the five patients, the correct diagnosis was delayed. One patient underwent incision and draining of a suspected RA under general anesthesia. All patients received antibiotic treatment. The literature review revealed a total of 116 reported cases of RCT. A total of 99 CT scans and 72 MRI showed soft tissue swelling in 89.6% and calcifications in 91.4% of the cases, 6.9% received invasive treatment. CONCLUSION: This article emphasizes the importance of knowledge about RCT and its management to avoid invasive and potentially harmful treatment. The focus in establishing the correct diagnosis of RCT is the identification and correct interpretation of clinical symptoms together with the specific radiological findings.

Surgical approach for complete cochlear coverage in EAS-patients after residual hearing loss.

INTRODUCTION: In cases with residual-hearing (RH) loss after cochlear implantation, a safe method is needed to provide full spectral resolution and as much auditory information as possible without implant replacement. Aim of this study was to prove the feasibility of accessing a partially inserted cochlear-implant-electrode for complete insertion to its maximum length through the external ear canal using a transcanal approach. METHODS: Two CI electrodes were customized with 18 stimulating channels. The electrode design enables the use of 12 active channels available for electrical stimulation inside the cochlea both after partial and full insertion. 10 CI electrodes were implanted in 10 fresh human cadaveric temporal bones. After initial partial insertion by posterior tympanotomy, the electrode was inserted to its maximum length via a transcanal approach. Radiographs and CT scans were performed to confirm the electrode position. The electrodes were investigated via x-ray after removal. RESULTS: X-ray and CT-scans confirmed the electrode prototypes covering an angular insertion depth between 236° to 307° after initial insertion. Accessing the electrode in the middle ear space was feasible and insertion to its full length was successful. Post-insertion CT confirmed insertion of the 28mm and 31.5mm electrode arrays covering an angular insertion depth between 360° and 540° respectively. No tip foldovers were detected. CONCLUSION: This study confirms the feasibility of extending the electrode insertion to its maximum insertion length using a transcanal approach in temporal bone specimens. This constitutes a second stage procedure on demand in EAS-surgery. This may be beneficial for EAS-patients providing electrical stimulation beyond the basal turn of the cochlea once the functional residual hearing is lost, without replacing the entire CI.

Endoscope-Assisted Microvascular Decompression for the Management of Hemifacial Spasm Caused by Vertebrobasilar Dolichoectasia.

OBJECTIVE: Vertebrobasilar dolichoectasia (VBD) is a rare cause of hemifacial spasm. The ectatic vessel hinders microscopic visualization of the root exit zone. The aim of this study was to evaluate the benefit of endoscopic visualization during microvascular decompression (MVD) in managing this type of neurovascular compression. METHODS: Retrospective evaluation of patients with VBD treated by endoscope-assisted MVD for hemifacial spasm between 2007 and 2016 was performed. A prospectively maintained database of all patients treated by MVD for hemifacial spasm was screened for vascular compression. Magnetic resonance imaging was evaluated to detect patients who had VBD according to defined criteria. The value of endoscopic inspection to detect offending vessels was analyzed, and clinical outcome was evaluated. RESULTS: VBD was detected in 11 of 290 patients (incidence 3.8%). In these patients, 12 MVD procedures were performed. The endoscope was useful in identifying the offending vessels and adjacent perforators without any brain retraction in all patients. At last clinical follow-up, all patients had almost complete to complete resolution of clinical symptoms. The interposing technique alone was effective with excellent results in 8 patients. Three patients required an additional transposition-fixation technique to achieve sufficient decompression. CONCLUSIONS: VBD is a rare cause of hemifacial spasm. Because of the large diameter of the offending vessel, MVD is technically more demanding. Endoscopic inspection with a 45° endoscope enables accurate visualization of the root exit zone, offending vessels, and perforating arteries. Furthermore, accurate placement of the Teflon pledgets can be confirmed leading to a favorable outcome.

Millimeter spatial resolution in vivo sodium MRI of the human eye at 7 T using a dedicated radiofrequency transceiver array.

PURPOSE: The aim of this study was to achieve millimeter spatial resolution sodium in vivo MRI of the human eye at 7 T using a dedicated six-channel transceiver array. We present a detailed description of the radiofrequency coil design, along with electromagnetic field and specific absorption ratio simulations, data validation, and in vivo application. METHODS: Electromagnetic field and specific absorption ratio simulations were performed. Transmit field uniformity was optimized by using a multi-objective genetic algorithm. Transmit field mapping was conducted using a phase-sensitive method. An in vivo feasibility study was carried out with 3-dimensional density-adapted projection reconstruction imaging technique. RESULTS: Measured transmit field distribution agrees well with the one obtained from simulations. The specific absorption ratio simulations confirm that the radiofrequency coil is safe for clinical use. Our radiofrequency coil is light and conforms to an average human head. High spatial resolution (nominal 1.4 and 1.0 mm isotropic) sodium in vivo images of the human eye were acquired within scan times suitable for clinical applications (∼ 10 min). CONCLUSIONS: Three most important eye compartments in the context of sodium physiology were clearly delineated in all of the images: the vitreous humor, the aqueous humor, and the lens. Our results provide encouragement for further clinical studies. The implications for research into eye diseases including ocular melanoma, cataract, and glaucoma are discussed. Magn Reson Med 80:672-684, 2018. © 2018 International Society for Magnetic Resonance in Medicine.

Four-Hand Suction-Irrigation Technique Leads to Gross Total Resection and Long-Term Progression-Free Survival in Fourth Ventricular Ependymoma.

BACKGROUND: Gross total resection is often avoided in posterior fossa ependymoma surgery because of the fear of permanent neurologic deficits after operation. However, the extent of resection is a major prognostic factor for progression-free and overall survival. This study evaluates the outcome of posterior fossa ependymoma gross total resection in adult patients using a 4-hand suction-irrigation technique at the floor of the fourth ventricle. METHODS: All surgical procedures for posterior fossa ependymomas performed since 2001 in the Department of Neurosurgery, University Medicine Greifswald were analyzed. RESULTS: Eight patients (2 women and 6 men; mean age, 41.9 years; range, 29-56 years) underwent surgery for posterior fossa ependymoma. All tumors were World Health Organization grade II. Tumor adherence was found to be in the caudal rhomboid fossa (between the obex and striae medullare, but below the facial colliculus) in all patients. The 4-hand suction-irrigation technique led to gross total resection in all patients (100%), without significant permanent neurologic deficits after surgery. None of the patients got further treatment (chemotherapy, radiation therapy, or second surgery). In none of these patients, tumor recurrence was seen on magnetic resonance imaging after a mean follow-up of 102 months (range, 14-181 months). CONCLUSIONS: Long-term progression-free survival in adult patients suffering from posterior fossa ependymoma is possible by gross total resection without adjuvant radio- or chemotherapy. By careful bimanual microsurgical dissection using the 4-hand suction-irrigation technique and avoidance of bipolar coagulation on the floor of the fourth ventricle, the risk for permanent neurologic deficits is low.

Prevalence and outcome of late-onset seizures due to autoimmune etiology: A prospective observational population-based cohort study.

OBJECTIVE: The increasing incidence of new-onset seizures with age is well known. Often, the etiology cannot be clarified. In the present study, patients with unprovoked late-onset seizures and without known neoplasm, who might have had paraneoplastic encephalitis, were investigated for a potentially underlying autoimmunity. METHODS: Sixty-six consecutive patients (36 women; aged ≥55 years) after having at least one seizure or seizures for ≤6 months were prospectively identified over a period of 4.75 years. All patients were tested for serum and cerebrospinal fluid (CSF) antibodies (Abs) to both neural cell-surface and intracellular antigens. Forty-five (68%) underwent brain magnetic resonance imaging (MRI). Follow-up in Ab-positive cases was ≥6 months. RESULTS: Two patients had high titers of anti-CASPR2 (contactin-associated protein-like 2) Abs in serum and CSF and fulfilled the diagnostic criteria of definite limbic encephalitis. Another two patients had bilateral encephalitic temporal MRI abnormalities. They also satisfied the criteria of definite limbic encephalitis, even though they had no Abs in serum or CSF. All four were in the age range of 55-70 years. They received immunotherapy and/or antiepileptic drug treatment and became seizure-free. SIGNIFICANCE: Our findings suggest that autoimmunity should be considered an important etiology in patients with late-onset seizures. Testing for neural antibodies and brain MRI may be worthwhile in this patient group.

3-Tesla Kinematic MRI of the Cervical Spine for Evaluation of Adjacent Level Disease After Monosegmental Anterior Cervical Discectomy and Arthroplasty: Results of 2-Year Follow-Up.

STUDY DESIGN: We prospectively evaluated adjacent disc levels after anterior cervical discectomy and arthroplasty (ACDA) using kinematic magnetic resonance imaging (MRI) and plain functional radiographs. OBJECTIVE: ACDA is an established treatment for degenerative cervical disc disease. The objective of this study was to evaluate the use of kinematic MRI for assessing the range of motion (ROM) before and after ACDA compared with plain functional radiographs and to evaluate adjacent degenerative disc disease (aDDD) at mid-term follow-up. SUMMARY OF BACKGROUND DATA: Twenty patients (12 females, 8 males; median age 45.6 ±â€Š6.9 yrs) treated by ACDA (BryanDisc; Medtronic, MN) underwent plain functional radiography and kinematic MRI of the cervical spine at 3 T before and 6 and 24 months after surgery. METHODS: A sagittal T2-weighted (T2w) 2D turbo spin echo (TSE) sequence and a 3D T2w dataset with secondary axial reconstruction were acquired. Signal intensity of all nonoperated discs was measured in regions of interest (ROI). Disc heights adjacent to the operated segment were measured. ROM was evaluated and compared with plain functional radiographs. Clinical outcome was evaluated using the visual analog scale (VAS) for head, neck and radicular pain, and the neck disability index (NDI). RESULTS: Mean ROM of the cervical spine on functional plain radiographs was 21.25 ±â€Š8.19°, 22.29 ±â€Š4.82°, and 26.0 ±â€Š6.9° preoperatively and at 6-month and 24-month follow-up, respectively. Mean ROM at MRI was 27.1 ±â€Š6.78°, 29.45 ±â€Š9.51°, and 31.95 ±â€Š9.58°, respectively. There was a good correlation between both techniques. Follow-up examinations demonstrated no signs of progressive degenerative disc disease of adjacent levels. All patients had clinical improvement up to 24 months after surgery. CONCLUSION: After ACDA, kinematic MRI allows evaluation of the ROM with excellent correlation to plain functional radiographs. Mid-term follow-up after ACDA is without evidence of progressive DDD of adjacent segments. LEVEL OF EVIDENCE: 3.

Ruptured Massa Intermedia Secondary to Hydrocephalus.

BACKGROUND: We report a case of ruptured massa intermedia (MI) as a sequela of hydrocephalus. CASE DESCRIPTION: A single case report is presented describing the sequelae of tumor bed hematoma after a posterior fossa hemangioblastoma resection in which the patient bled 3 days after surgery, resulting in secondary hydrocephalus and subsequently dilatation of the third ventricle, which resulted in rupture of the MI. The patient was managed on emergency basis with an external ventricular drain then endoscopically with a third ventriculostomy and clot extraction. CONCLUSIONS: Absent MI is not uncommon in hydrocephalic patients, and it is assumed to be the result of rupture from acute dilatation of the third ventricle. Our case report proves this assumption and documents the presence and absence of the MI before and after developing hydrocephalus.

Primary leptomeningeal melanoma of the cervical spine mimicking a meningioma-a case report.

Background and Importance Primary leptomeningeal melanoma (PLM) is highly malignant and exceedingly rare. Due to its rarity, diagnostic and treatment paradigms have been slow to evolve. We report the first case of a PLM that mimics a cervical spine meningioma and then discuss the current clinical, radiologic, and pathologic diagnostic methodologies as well as expected outcomes related to this disease. Clinical Presentation A 54-year-old woman presented a dural-based extramedullary solid mass ventral to the C2-C3 spinal cord causing spinal cord compression without cord signal changes, characteristic of meningioma. Intraoperative microscopic inspection revealed numerous black spots littering the surface of the dura; the tumor itself was yellow in appearance and had a soft consistency. Pathologic analysis of the specimen revealed a malignant melanin-containing tumor. No primary site was found, so a diagnosis of primary leptomeningeal melanoma was made, and the patient subsequently received interferon therapy. To date (2 years postoperatively), no local or systemic recurrence of the tumor has been identified. Conclusion As with most rare tumors, case reports constitute the vast majority of references to PLM. Only an increased awareness and an extensive report of each individual case can help diagnose and clarify the nature of PLM. Clinicians need to be aware of such malignant conditions when diagnosing benign tumoral lesions of the spine such as meningiomas.

Prevention of capsule opacification after accommodating lens refilling: pilot study of strategies evaluated in a monkey model.

PURPOSE: To test 2 strategies to prevent capsule opacification after accommodating lens refilling in a rhesus monkey model. SETTING: Animal laboratory and laboratory of European university medical centers. DESIGN: Experimental study. METHODS: Six rhesus monkeys had refilling of the lens capsular bag. In the first strategy, before it was filled with a silicone polymer, the capsular bag was treated with noncommercial sodium hyaluronate 1.0% containing cytotoxic substances. In the second strategy, the capsular bag was filled with clinically used sodium hyaluronate 1.0% (Healon) after treatment with actinomycin-D. Slitlamp inspection was performed during a follow-up of 40 to 50 weeks. After enucleation, magnetic resonance images were obtained and confocal fluorescence imaging was performed. RESULTS: Using the first strategy, capsule opacification developed in all eyes. Using the second strategy, 1 monkey did not develop capsule opacification after a 9-month follow-up. In a second monkey, the lens capsule remained clear for 3 months, after which the hyaluronate refill material was exchanged with a silicone polymer and capsule opacification developed. Combining these results with those in a previous study, the difference in opacification between silicone and sodium hyaluronate as refilling materials was statistically significant (P<.01). CONCLUSIONS: That no capsular bag fibrosis occurred in the presence of hyaluronate suggests that the properties of hyaluronate are the reason that remaining lens epithelial cells do not develop into fibrotic cells. The choice of a suitable lens-refilling material prevents the development of capsule opacification. FINANCIAL DISCLOSURE: Mr. Terwee was an employee of Abbott Medical Optics B.V. during the study period. No other author has a financial or proprietary interest in any material or method mentioned.

Ophthalmic magnetic resonance imaging at 7 T using a 6-channel transceiver radiofrequency coil array in healthy subjects and patients with intraocular masses.

OBJECTIVES: This study was designed to examine the feasibility of ophthalmic magnetic resonance imaging (MRI) at 7 T using a local 6-channel transmit/receive radiofrequency (RF) coil array in healthy volunteers and patients with intraocular masses. MATERIALS AND METHODS: A novel 6-element transceiver RF coil array that makes uses of loop elements and that is customized for eye imaging at 7 T is proposed. Considerations influencing the RF coil design and the characteristics of the proposed RF coil array are presented. Numerical electromagnetic field simulations were conducted to enhance the RF coil characteristics. Specific absorption rate simulations and a thorough assessment of RF power deposition were performed to meet the safety requirements. Phantom experiments were carried out to validate the electromagnetic field simulations and to assess the real performance of the proposed transceiver array. Certified approval for clinical studies was provided by a local notified body before the in vivo studies. The suitability of the RF coil to image the human eye, optical nerve, and orbit was examined in an in vivo feasibility study including (a) 3-dimensional (3D) gradient echo (GRE) imaging, (b) inversion recovery 3D GRE imaging, and (c) 2D T2-weighted fast spin-echo imaging. For this purpose, healthy adult volunteers (n = 17; mean age, 34 ± 11 years) and patients with intraocular masses (uveal melanoma, n = 5; mean age, 57 ± 6 years) were investigated. RESULTS: All subjects tolerated all examinations well with no relevant adverse events. The 6-channel coil array supports high-resolution 3D GRE imaging with a spatial resolution as good as 0.2 × 0.2 × 1.0 mm, which facilitates the depiction of anatomical details of the eye. Rather, uniform signal intensity across the eye was found. A mean signal-to-noise ratio of approximately 35 was found for the lens, whereas the vitreous humor showed a signal-to-noise ratio of approximately 30. The lens-vitreous humor contrast-to-noise ratio was 8, which allows good differentiation between the lens and the vitreous compartment. Inversion recovery prepared 3D GRE imaging using a spatial resolution of 0.4 × 0.4 × 1.0 mm was found to be feasible. T2-weighted 2D fast spin-echo imaging with the proposed RF coil afforded a spatial resolution of 0.25 × 0.25 × 0.7 mm. CONCLUSIONS: This work provides valuable information on the feasibility of ophthalmic MRI at 7 T using a dedicated 6-channel transceiver coil array that supports the acquisition of high-contrast, high-spatial resolution images in healthy volunteers and patients with intraocular masses. The results underscore the challenges of ocular imaging at 7 T and demonstrate that these issues can be offset by using tailored RF coil hardware. The benefits of such improvements would be in positive alignment with explorations that are designed to examine the potential of MRI for the assessment of spatial arrangements of the eye segments and their masses with the ultimate goal to provide imaging means for guiding treatment decisions in ophthalmological diseases.

Value of 3-dimensional high-resolution magnetic resonance imaging in detecting the offending vessel in hemifacial spasm: comparison with intraoperative high definition endoscopic visualization.

BACKGROUND: High-resolution 3-dimensional (3-D) magnetic resonance imaging (MRI) is widely used to predict the neurovascular anatomy within the cerebellopontine angle. OBJECTIVE: To assess the value of 3-D steady-state free precession imaging (SSFP) and time-of-flight magnetic resonance angiography (TOF MRA) in detecting the offending vessels in hemifacial spasm in comparison to intraoperative endoscopic visualization. METHODS: 42 patients underwent endoscope-assisted microvascular decompression (MVD). All available preoperative 3-D SSFP and TOF MRA images were checked. Intraoperative videos were captured by a high-definition endoscopic camera attached to endoscopes while exploring the area of facial nerve root exit zone (REZ). Evaluation of the 3-D images was performed by 2 independent groups of observers and compared with the operative findings. RESULTS: Three-D MRI had an average positive predictive value (PPV) of 89.1% in differentiating between simple and complex compression. Mean accuracy of the images in detection of the offending vessels was 83.3% and 77% according to the first and second groups of observers, respectively. Averaged inter-observer agreement between the 2 groups of observers was substantial, with an averaged Kappa coefficient (K) of 0.56. In the simple compression group, mean accuracy was 97% and 89.4% according to the first and second groups of observers, respectively. Averaged K for agreement was substantial (K = 0.65). CONCLUSION: According to endoscopic visualization, 3-D SSFP and TOF MRA images are accurate in detecting the offending vessels in simple compression of the facial nerve, and in predicting presence of a complex compression with variable sensitivity in identifying all offending vessels.

MR Microscopy of the human eye at 7.1 T and correlation with histopathology-proof of principle.

OBJECTIVE: Magnetic resonance imaging (MRI) at 1.5 and 3.0 Tesla with small surface coils is a well-established procedure in the diagnosis of masses of the eye and orbital cavity. Until now histological examination has been required to obtain definitive information on tumor extent or possible infiltration of surrounding structures. With ultra-high-field MRI, however, it is possible to evaluate tumor morphology as well as possible extension into surrounding structures with submillimeter spatial resolution. MATERIALS AND METHODS: We present a female patient with a uveal melanoma who underwent a preoperative MRI at 1.5 T (spatial resolution = 0.9 x 0.9 x 4 mm/voxel). Postoperatively, the enucleated specimen was examined in a 7.1 Tesla high-field MRI scanner (slice thickness = 500 µm, matrix size = 512 x 512 pixels, spatial resolution = 78 x 78 x 500 µm/voxel, acquisition time = 8:20 min per plane). Finally, the specimen was examined histologically, and the histological and MRI results were correlated. RESULTS: Ultra-high-field MRI at 7.1 Tesla visualized the uveal melanoma and anatomical structures of the bulb with high resolution, enabling definitive assessment of tumor morphology and extent. Subsequent histological examination confirmed the MRI findings regarding origin, internal structure, and extent of the tumor. CONCLUSION: MR microscopy correlates strongly with histology, suggesting that this new imaging modality has the potential for noninvasively assessing tumor morphology, extent, and infiltration of surrounding structures. The examination was performed ex vivo and demonstrates that diagnostic assessment of malignant masses is feasible using high-resolution MR microscopy.

In vivo 7.1 T magnetic resonance imaging to assess the lens geometry in rabbit eyes 3 years after lens-refilling surgery.

PURPOSE: To evaluate the utility of high-resolution magnetic resonance imaging (MRI) in assessing the normal and refilled lens geometry in rabbits after lens-refilling surgery. SETTING: University of Rostock, Rostock, Germany. DESIGN: Experimental study. METHODS: High-resolution ocular MRIs were acquired (7.1 T ClinScan) using a 2-channel coil with 4 coil elements and T2-weighted turbo spin-echo sequences (slice thickness 700 µm, field of view 40 mm × 40 mm) in rabbits after lens refilling surgery combined with intraoperative treatment to prevent lens epithelial cell proliferation. Single slices were used to assess the refilled lenses 3 years postoperatively. RESULTS: The entire geometry (cross-sectional area, radius of curvature, axial and equatorial diameters) of the crystalline and refilled lenses was visualized by in vivo 7.1T MRI 3 years postoperatively (in-plane resolution: 125 µm × 125 µm). In refilled eyes, the capsule and the homogenous silicone polymer remained in close contact with no visible interface. The dimensions of the refilled lens were significantly smaller than those of the crystalline lens of the contralateral eye. CONCLUSIONS: High-resolution MRI allows in vivo visualization and analysis of the spatial arrangement of the lens in rabbit eyes after lens refilling surgery and overcomes a number of major limitations in the quantitative evaluation of the lens shape. Further efforts are required to optimize the amount of polymer injected during lens refilling to achieve a predictable refractive outcome after lens refilling surgery. FINANCIAL DISCLOSURE: Drs. Stachs, Langner, Sternberg, Martin, Schmitz, Hosten and Guthoff have no financial or proprietary interest in any material or method mentioned. Additional financial disclosure is found in the footnotes.