Radio-frequency and optically transparent radome de-icing materials: fluorine-doped tin oxide

Ice-elimination systems are very common in radio-frequency (RF) structures like radomes. For a radome application, the de-icing materials must be predominantly transparent to broadband RF radiation and have an adequate heating performance to remove the ice. The current development of high-performance radome de-icing materials is limited with a trade-off between the sheet resistance and RF transmission because one cannot be improved without sacrificing the other. We report for the first time a transparent conductive oxide (TCO) film as a lightweight and high optically transparent radome de-icing material. In this research, we prepared fluorine-doped tin oxide (FTO) films by horizontal ultrasonic spray pyrolysis (USP) deposition and found that the sheet resistance varied from 9 to 5000 Ω sq⁻¹ with 0.219 to 90.0% RF transmission. Dassault CST software was used to validate the RF transmission at the X-band (8.2 to 12.4 GHz) region. The FTO films also exhibited sufficient optical transparency with efficient voltage-induced heating performance. With optimized electrical properties and RF transparency, FTO films will be good candidates for next-generation radome de-icing materials.

Ice-elimination systems are very common in radio-frequency (RF) structures like radomes.     

Differentiation between Cystic Pituitary Adenomas and Rathke Cleft Cysts: A Diagnostic Model Using MRI

BACKGROUND AND PURPOSE:Cystic pituitary adenomas may mimic Rathke cleft cysts when there is no solid enhancing component found on MR imaging, and preoperative differentiation may enable a more appropriate selection of treatment strategies. We investigated the diagnostic potential of MR imaging features to differentiate cystic pituitary adenomas from Rathke cleft cysts and to develop a diagnostic model.MATERIALS AND METHODS:This retrospective study included 54 patients with a cystic pituitary adenoma (40 women; mean age, 37.7 years) and 28 with a Rathke cleft cyst (18 women; mean age, 31.5 years) who underwent MR imaging followed by surgery. The following imaging features were assessed: the presence or absence of a fluid-fluid level, a hypointense rim on T2-weighted images, septation, an off-midline location, the presence or absence of an intracystic nodule, size change, and signal change. On the basis of the results of logistic regression analysis, a diagnostic tree model was developed to differentiate between cystic pituitary adenomas and Rathke cleft cysts. External validation was performed for an additional 16 patients with a cystic pituitary adenoma and 8 patients with a Rathke cleft cyst.RESULTS:The presence of a fluid-fluid level, a hypointense rim on T2-weighted images, septation, and an off-midline location were more common with pituitary adenomas, whereas the presence of an intracystic nodule was more common with Rathke cleft cysts. Multiple logistic regression analysis showed that cystic pituitary adenomas and Rathke cleft cysts can be distinguished on the basis of the presence of a fluid-fluid level, septation, an off-midline location, and the presence of an intracystic nodule (P = .006, .032, .001, and .023, respectively). Among 24 patients in the external validation population, 22 were classified correctly on the basis of the diagnostic tree model used in this study.CONCLUSIONS:A systematic approach using this diagnostic tree model can be helpful in distinguishing cystic pituitary adenomas from Rathke cleft cysts.

Pituitary adenoma is a benign neoplasm that arises from the adenohypophysis and is the most common intrasellar pathology, accounting for 10%–15% of all intracranial neoplasms.^1,2 Typical imaging findings of an uncomplicated pituitary adenoma include slow enhancement compared with that of the pituitary gland, lateral deviation of the infundibulum, and isointense signal intensity relative to gray matter on T1-weighted imaging.³ Intratumoral hemorrhage and ischemic infarction are common with larger pituitary adenomas, which may result in hemorrhagic or cystic changes or both, leading to various signal intensities on MR imaging.^4–8Rathke cleft cyst (RCC) is a benign epithelial cyst believed to originate from the remnants of the Rathke pouch.⁹ Typical imaging findings include a nonenhancing, noncalcified, intrasellar/suprasellar cyst with an intracystic nodule.^9–12 Depending on its cystic content and the presence of an associated intracystic nodule, an RCC may show various signal intensities on both T1- and T2-weighted images.^13–15 More specifically, T1 hyperintensity and T2 hypointensity of an RCC associated with a high intracystic protein content can mimic cystic pituitary adenoma with hemorrhage, which makes imaging diagnosis of a cystic pituitary adenoma or an RCC a challenge.Preoperative differentiation between a cystic pituitary adenoma and an RCC is important for treatment planning.^16–18 Partial resection of the wall and evacuation of cyst contents are sufficient for an RCC, whereas a cystic pituitary adenoma may require total resection, not only to relieve mass effect but also to correct hormone excess.^9,19–21 Unnecessary surgical excision of an RCC may lead to serious complications, such as CSF leaks, infection, and hypothalamic injury, though the incidences thereof are very low.^21,22 Thus, obtaining the correct preoperative diagnosis with which to determine the proper surgical indication and to plan the optimal surgical procedure is a major concern for neurosurgeons.⁹ To date, several characteristic MR imaging appearances of pituitary adenomas and RCCs have been reported,^{2,9,12,20,23–25} but there are some cases for which the diagnoses are inconclusive when 1 or 2 imaging findings are used, and none of the studies has systemically analyzed the MR imaging appearances of cystic pituitary adenomas to differentiate them from RCCs. Therefore, we evaluated the diagnostic potential of a multifactor analysis of MR imaging findings and developed a diagnostic tree model to increase the diagnostic accuracy in differentiating cystic pituitary adenomas and RCCs before surgery.     

Accuracy of Diffusion Tensor Imaging for Diagnosing Cervical Spondylotic Myelopathy in Patients Showing Spinal Cord Compression

ObjectiveTo assess the performance of diffusion tensor imaging (DTI) for the diagnosis of cervical spondylotic myelopathy (CSM) in patients with deformed spinal cord but otherwise unremarkable conventional magnetic resonance imaging (MRI) findings.ResultsThe MD, LD, and RD cut-off values were 1.079 × 10^-3, 1.719 × 10^-3, and 0.749 × 10^-3 mm²/sec, respectively, and that of FA was 0.475. Sensitivity, specificity, positive predictive value and negative predictive value were: 100 (4/4), 44.8 (13/29), 20 (4/20), and 100 (13/13) for MD; 100 (4/4), 27.6 (8/29), 16 (4/25), and 100 (8/8) for FA; 100 (4/4), 58.6 (17/29), 25 (4/16), and 100 (17/17) for MD∩FA; 100 (4/4), 68.9 (20/29), 30.8 (4/13), and 100 (20/20) for LD∩FA; and 75 (3/4), 68.9 (20/29), 25 (3/12), and 95.2 (20/21) for RD∩FA in percentage value. Diagnostic performance comparisons revealed significant differences only in specificity between FA and MD∩FA (p = 0.003), FA and LD∩FA (p < 0.001), FA and RD∩FA (p < 0.001), MD and LD∩FA (p = 0.024) and MD and RD∩FA (p = 0.024).ConclusionFractional anisotropy combined with MD, RD, or LD is expected to be more useful than FA and MD for diagnosing CSM in patients who show deformed spinal cords without signal changes on MRI.     

Ultrasound-Guided Percutaneous Removal of Wooden Foreign Bodies in the Extremities with Hydro-Dissection Technique

ObjectiveWe described the technique of ultrasound (US)-guided percutaneous removal of the foreign bodies (FB) with hydro-dissection in the radiologic department and presented video files of several cases.ResultsThe mean time required for the entire procedure was approximately 20 minutes. There were no significant complications during the US-guided removal or long-term complications after the procedure. All 4 FBs were successfully removed from the soft tissue under US guidance.ConclusionUltrasound-guided percutaneous removal of the FBs with hydro-dissection in the radiology department is a less invasive and safe method over surgical removal in the operating room. Additionally, the use of a guide wire and serial dilator may help minimize soft tissue injury and facilitate the introduction of forceps.     

Atypical Unilateral Posterior Reversible Encephalopathy Syndrome Mimicking a Middle Cerebral Artery Infarction

Posterior reversible encephalopathy syndrome (PRES) is usually a reversible clinical and radiological entity associated with typical features on brain MR or CT imaging. However, the not-so-uncommon atypical radiological presentations of the condition are also present and they may go unrecognised as they are confused with other conditions. Here, we report a very rare case of atypical, unilateral PRES in a 49-year-old uremic, post-transplant female patient who presented with seizures. Initial MRI showed high-grade occlusion of the left middle cerebral artery (MCA) and lesions suggestive of subacute infarction in the ipsilateral frontotemporoparietal lobe. Patient symptoms had resolved a day after the onset without any specific treatment but early follow-up CT findings suggested hemorrhagic transformation. Follow-up MRI performed 2 years later showed complete disappearence of the lesions and persisting MCA occlusion.     

Microcatheter Looping to Facilitate Aneurysm Selection in Coil Embolization of Paraclinoid Aneurysms

ObjectiveDescribed herein is a microcatheter looping technique to facilitate aneurysm selection in paraclinoid aneurysms, which remains to be technically challenging due to the inherent complexity of regional anatomy.ResultsThrough this looping technique, a total of 59 paraclinoid aneurysms were successfully treated. After aneurysm selection as described, single microcatheter technique (n = 25) was most commonly used to facilitate coiling, followed by balloon protection (n = 21), stent protection (n = 7), multiple microcatheters (n = 3), and stent/balloon combination (n = 3). Satisfactory aneurysmal occlusion was achieved through coil embolization in 44 lesions (74.6%). During follow-up of 53 patients (mean interval, 10.9 ± 5.9 months), only one instance (1.9%) of major recanalization was observed. There were no complications related to microcatheter looping.ConclusionThis microcatheter looping method facilitates safe and effective positioning of microcatheter into domes of paraclinoid aneurysms during coil embolization when other traditional microcatheter selection methods otherwise fail.