Transendoscopic ultrasound in ventricular lesions

BackgroundAfter transendoscopic sonocatheters had been tested in the laboratory for imaging characteristics and practicability, clinical application was studied with special reference to imaging and navigation capabilities, practicability, safety, and preliminary indications.MethodsIntraoperative ENS images prepared during surgery on 75 selected patients between 1996 and 2005 were examined. There were 35 female and 40 male patients, and their mean age was 42 years (range, 2-69 years). Within this series, there were 28 cases of ventricular lesions (ventricular hematomas, tumors, and colloid cyst included, 35 cases) with different diagnosis. In most cases, Aloka sono equipment (Aloka Deutschland, Düsseldorf, Germany) was used because equipment supplied by this company had yielded superior imaging results in the laboratory. This work with patients differed from the laboratory work in that 2 sizes (diameters) of catheters were used: 6-F catheters for block-shaft endoscopes and 8-F for hollow-shaft endoscopes.ResultsImaging: In clinical use, the sonocatheter has superior imaging and navigation abilities to those seen in anatomical laboratory work. Real-time and online characteristics represent changes such as shifting, pulsation, CSF flow, blood flow, and changes in size and form of structures. When confronted with clinical problems, this technique still has some limitations such as short penetration depth of 3-cm radius and lack of scanning anterior to the endoscope. Navigation: The scan is radial 360° and in an orthogonal plane to the axis of the endoscope. At the tip of the endoscope it delivers an image that looks geometrically like a “brain radar.” Because of its real-time characteristic, ENS has a navigation capacity that markedly differs from usual neuronavigation, but is intuitively usable. Endoneurosonography was applied in 8 hydrocephali, 3 colloid cysts, 5 intraventricular hematomas, 1 septostomy, 11 ETVs, 2 cystostomies, 4 multiple cysts, and 1 tumor biopsy cases. Three illustrative cases are presented.ConclusionEndoneurosonography is a tool for intraoperative real-time and online high-resolution imaging, and neuronavigation of endoscopes with a working channel at least 2 mm in diameter; it also has application in a wide variety of ventricular lesions. Endoneurosonography is limited by short penetration depth and not scanning ahead to the endoscope anteriorly.