Needle Tip Detection Using Ultrasound Probe for Vertical Punctures: A Simulation and Experimental Study.

Current ultrasound-guided punctures are difficult to perform as they are performed at an angle to the ultrasound image of the affected area, resulting in longer puncture times, lower success rates, and higher unexpected injury rates. Vertical puncture techniques have also been investigated, but the principle of needle tip detection remains unclear. To optimize ultrasound probes for puncture, the principle of needle tip detection should be understood. This study aimed to verify the principle of needle tip detection and optimal measurement conditions for vertical puncture. Needle tip detection was performed in animal experiments using a probe with a central puncture slit. Moreover, the needle tip was detected at short distances using a puncture spacer. We also investigated the signal from the needle tip using a ring probe and confirmed the principle of needle tip detection, effect of needle tip angle, and insertion depth on needle tip detection through simulation and experiments. Needle tip detection using ultrasound-guided waves was described, and the relationship among needle tip angle, detection intensity, and phase change was verified. The needle tip can be detected by the leakage of the ultrasound-guided wave generated inside the needle tip.

Parieto-Occipital Interhemispheric Transfalcine, Trans-Bitentorial Approach for Radical Resection of Falcotentorial Meningiomas.

OBJECTIVE: Falcotentorial meningioma occurs close to the falcotentorial edges and the confluence of the vein of Galen. The posterosuperior approach conventionally used to reach this site does not allow direct visualization of the tumor matrix, making detachment difficult. Meningiomas at this location are therefore among those that are not well amenable to radical resection. We devised an alternative anterolateral approach that, when used in addition to the posterosuperior approach, provides an operating field which allows to overview large, bilaterally extending tumors. We report this parieto-occipital interhemispheric transfalcine, trans-bitentorial approach, together with associated procedural modifications. METHODS: We used the approach in four patients with falcotentorial meningioma between February 2008 and July 2017. We began by extending a parieto-occipital craniotomy slightly beyond the midline, to pass across the most caudal bridging vein on the rostral side. We then created a fan-shaped fenestration as large as possible in the falx, between the superior sagittal sinus and the inferior sagittal and straight sinuses (window 1). We further performed wedge-shaped resections of both tentorial edges to the left and right of window 1 (windows 2 and 3). Tumor debulking was then carried out via these three windows (the triple-window method). Finally, we detached the tumor in the area of the falcotentorial edges and the confluence of the vein of Galen. To obtain a superorostral operating field as wide as possible from laterally, thereby exposing the potential blind spots, the operating surgeon used both hands while retracting the precuneus, and the assistant surgeon used both hands to turn over the falcotentorial edges (twosome four-hand retractorless microsurgery). RESULTS: The wide operating field provided by this parieto-occipital interhemispheric transfalcine, trans-bitentorial approach and twosome four-hand retractorless microsurgery provides a direct view of delicate structures at the falcotentorial edges and the confluence of the vein of Galen, a site that is most likely to be a blind spot in conventional approaches. Retraction of the precuneus on the nondominant side enabled radical resection with no neurologic deficit in any of the patients. CONCLUSIONS: The parieto-occipital interhemispheric transfalcine, trans-bitentorial approach with the triple-window method opens an anterolateral operating field in addition to a posterosuperior operating field in large tumors located in the falcotentorial and pineal region, extending anteroposteriorly and bilaterally. The twosome four-hand retractorless technique via this approach enables visualization of the tumor matrix at sites, which are barely visible with the conventional approach. Thus, the tumor can be removed more radically and safely.

Radical Resection of Craniopharyngioma: Discussions Based on Long-term Clinical Course and Histopathology of the Dissection Plane.

OBJECTIVE: Craniopharyngioma is a benign tumor. However, sometimes, this tumor may recur repeatedly even after apparent total resection. This study investigated the requirements for ideal radical treatment, based on a discussion of the long-term clinical course and pathological findings in surgical patients. METHODS: We performed 81 surgical procedures for 67 patients with craniopharyngioma between February 1990 and December 2015. We classified patients into Groups I-III according to emphasis of surgery in chronological order, so we investigated the tumor recurrence rate and the necessity for postoperative hormonal replacement. RESULTS: Multiple comparison of results from the three groups found significant differences in recurrence rate between Groups I and II (P = 0.0111) and Groups I and III (P = 0.0056). Although there were no differences in recurrence rate between Groups II and III, mortality rate of Group III was lower than that of Group II. No significant difference was seen between any group in terms of hormonal replacement. CONCLUSIONS: These results strongly suggest that the radical resection used to treat patients in Group III should be given priority as the procedure for removing craniopharyngioma.

Intracranial epidermoid cyst with proliferative folliculosebaceous epithelium: Report of a rare case and discussion on pathogenesis.

Intracranial epidermoid cysts are rarely known to increase in size over a brief period. While malignant transformations of epidermoid cyst have been previously described, no reports to date have described rapid proliferation accompanied by mature hair follicles and sebaceous glands without malignant transformations. The present case involved a 71-year-old man who visited a local physician with disturbance of equilibrium. A mass lesion was detected at the left cerebellopontine angle and was subsequently removed. Histopathological diagnosis of this lesion was as an epidermoid cyst. Seventeen years after this initial surgery, worsened left hypoacusis, disorientation, eating disorder and gait disturbance appeared, and the patient visited the physician again. Local recurrence of the lesion was observed, and the patient was referred to our hospital for its removal. Intraoperative findings revealed a pearly white tumor, histopathologically diagnosed as an epidermoid cyst. Three years later, local recurrence was observed, and the cyst was again removed. Intraoperative findings revealed a partially pearly white tumor similar to the tumor observed during the second surgery, but the majority of the tumor was non-shiny, ochre-colored and suckable. Histopathological diagnosis was an epidermoid cyst with an epidermis-like structure. Postoperative activities of daily living were independent thereafter, but from March of the following year, he began to experience increasing difficulty in walking and subsequently visited our hospital again. Tumor recurrence was observed and was removed again in November of the same year. Intraoperative findings revealed a tumor that was primarily ochre-colored, non-shiny, brittle and suckable. The histopathological diagnosis was folliculosebaceous epithelial proliferative lesion accompanied by an epidermis-like epithelium and a differentiation into hair follicles and sebaceous gland,s and the tumor was determined to be an epidermoid cyst with proliferative folliculosebaceous epithelium.

Real-time 3D Photoacoustic Visualization System with a Wide Field of View for Imaging Human Limbs.

Background: A breast-specific photoacoustic imaging (PAI) system prototype equipped with a hemispherical detector array (HDA) has been reported as a promising system configuration for providing high morphological reproducibility for vascular structures in living bodies. Methods: To image the vasculature of human limbs, a newly designed PAI system prototype (PAI-05) with an HDA with a higher density sensor arrangement was developed. The basic device configuration mimicked that of a previously reported breast-specific PAI system. A new imaging table and a holding tray for imaging a subject's limb were adopted. Results: The device's performance was verified using a phantom. Contrast of 8.5 was obtained at a depth of 2 cm, and the viewing angle reached up to 70 degrees, showing sufficient performance for limb imaging. An arbitrary wavelength was set, and a reasonable PA signal intensity dependent on the wavelength was obtained. To prove the concept of imaging human limbs, various parts of the subject were scanned. High-quality still images of a living human with a wider size than that previously reported were obtained by scanning within the horizontal plane and averaging the images. The maximum field of view (FOV) was 270 mm × 180 mm. Even in movie mode, one-shot 3D volumetric data were obtained in an FOV range of 20 mm in diameter, which is larger than values in previous reports. By continuously acquiring these images, we were able to produce motion pictures. Conclusion: We developed a PAI prototype system equipped with an HDA suitable for imaging limbs. As a result, the subject could be scanned over a wide range while in a more comfortable position, and high-quality still images and motion pictures could be obtained.

A new Approach to El Niño Prediction beyond the Spring Season.

The enormous societal importance of accurate El Niño forecasts has long been recognized. Nonetheless, our predictive capabilities were once more shown to be inadequate in 2014 when an El Nino event was widely predicted by international climate centers but failed to materialize. This result highlighted the problem of the opaque spring persistence barrier, which severely restricts longer-term, accurate forecasting beyond boreal spring. Here we show that the role played by tropical seasonality in the evolution of the El Niño is changing on pentadal (five-year) to decadal timescales and thus that El Niño predictions beyond boreal spring will inevitably be uncertain if this change is neglected. To address this problem, our new coupled climate simulation incorporates these long-term influences directly and generates accurate hindcasts for the 7 major historical El Niños. The error value between predicted and observed sea surface temperature (SST) in a specific tropical region (5°N-5°S and 170°-120°W) can consequently be reduced by 0.6 Kelvin for one-year predictions. This correction is substantial since an "El Niño" is confirmed when the SST anomaly becomes greater than +0.5 Kelvin. Our 2014 forecast is in line with the observed development of the tropical climate.