agar and Cerebral-Hemorrhage

Stereotactic aqua-stream and aspiration (SASA) has been used for the evacuation of intracerebral hematomas. The authors have introduced ultrasound imaging (US) to monitor the evacuations of the hematoma during the surgical procedure. Hematomas were reproduced in an agar hematoma model which showed that if air collected in the hematoma cavity, it produced a strong artifact, and the hematoma could not be monitored. In the clinical trial, hematomas were visualized, and the surgical procedures were monitored in real time. The needle of the SASA and the air that collected in the hematoma cavity produced only weak artifacts, and the SASA water jet showed as a hyperechoic region on US, so that the procedure could be monitored in real time. In all cases, the average amount of evacuated hematoma exceeded 92%, as calculated from the preoperative and postoperative computed tomography images. The level of consciousness improved from a preoperative level of 1-20 (Japan Coma Scale) to 0-3 postoperatively. The addition of US monitoring to computed tomography guided stereotactic evacuation of hematomas with SASA enabled hypertension-associated intracranial hematomas to be evacuated more safely and more completely than has been achieved hitherto.

Topics: Agar; Aged; Artifacts; Cerebral Hemorrhage; Drainage; Equipment Design; Female; Hematoma; Humans; Hypertension; Male; Models, Structural; Monitoring, Intraoperative; Stereotaxic Techniques; Tomography, X-Ray Computed; Ultrasonography; Water

Old hemorrhagic lesions in the brain are characteristically surrounded by a band of hemosiderin-containing tissue. This region is typically of low signal intensity on long-echo-time (TE) radio-frequency (RF) spin-echo magnetic resonance (MR) images and on gradient-echo MR images. To determine the cause of signal loss in this band, the authors measured the signal that arises from imaging such a region with use of an RF spin-echo technique with a 180 degrees pulse incrementally displaced from TE/2. The incremental loss of signal was small. Using an agar phantom containing iron particles, the authors also showed that signal loss results primarily from diffusion in magnetic gradients. They conclude that most signal loss in the dark band surrounding areas of late-stage hemorrhage arises from diffusion in areas of magnetic inhomogeneity.

Topics: Adult; Agar; Brain Neoplasms; Cerebral Hemorrhage; Child; Female; Ferrosoferric Oxide; Hemangioma, Cavernous; Humans; Image Enhancement; Iron; Magnetic Resonance Imaging; Male; Mineral Oil; Models, Structural; Oxides; Plant Oils; Propylene Glycols; Water