The use of ultrasound in clinical practice is no longer limited to diagnostic imaging. Ultrasound technology now allows for the use of focused ultrasound energy for therapeutic purposes by delivering high-intensity focused ultrasound (HIFU) for applications such as tissue ablation, throrabolysis, enhanced drug delivery and hemostasis. HIFU is being promoted as a noninvasive method to treat certain primary solid tumors, metastatic disease. enhance drug delivery through the blood-brain barrier. and to promote thrombolysis in stroke victims. The field of medicine is evolving towards increasing use of noninvasive and minimally invasive therapies such as HIFU. The major effect of very high acoustic intensities in tissue is heat generation due to absorption of a portion of the acoustic energy. Focusing results in high intensities at a specific location and over only a small volume. This focusing minimizes the potential for thermal damage to tissue located between the transducer and the focal point as the intensities are much lower outside the focal region. There are also mechanical phenomena in addition to thermal effects that are associated with high acoustic intensities that are not present at lower intensities. Mechanical phenomena include cavitation, microstreaming, and radiation forces. This article provides an overview of HIFU including its mechanisms of action. current clinical applications, and future requirements to expand the clinical applications of this technique.
Bursts of focused ultrasound energy a billion times more intense than diagnostic ultrasound have become available commercially recently for clinical ablation of various biological soft tissues from prostate cancer to uterine fibroids. However, although that the use of High Intensity Focused Ultrasound (HIFU) for brain therapeutic applications was already envisioned in the early 5O’s, the targeting of brain with High Intensity Focused Ultrasound (HIFU) remains today a technological challenge. Due to the large discrepancy between the speed of sound in the bone and in the soft tissues associated with a high absorption of the bone. the ultrasonic wavefront is strongly distorted by the skull bone. resulting in a destruction of the focus. During the last decade, novel adaptive focusing techniques have been developed in order to correct the skull aberrations. The potential of time reversal focusing associated with the development of high power multi-element therapeutic transducers allow now the accurate focusing of high power ultrasound in the brain. Minimally invasive clinical tests on sheep will be presented as well as fully non-invasive tests on monkeys.
We have investigated the relationship between body mass index (BMI)and carotid atherosclerosis in 134 patients (84 men and 50 women) after cerebral infarction or hemorrhage. or ischemic heart disease (IHD). Associated risk factors (high blood pressure, diabetes mellitus and hyperlipidemia)were also evaluated. Carotid stenosis was measured by B-mode ultrasound imaging, and the degree of stenosis was expressed accoring to the criteria of the European Carotid Surgery Trial (ECST).We classified the participants into two groups, A (ECST<30%)and B(ECST<30%), and the results were as follows. 1)Approximately 68% of the subjects suffered brain infarction. 2)The mean BMI in groups A and B was 21.6 and 22.4, indicating that patients with more severe stenosis (group A)had a lower BMI, or were less obese. than patients in group B. 3)Patients with cerebral infarction had a higher BMI and more severe carotid stenosis. while the IHD group had a roughly equal BMI and less severe carotid stenosis. Thus, the present cross-sectional study of stroke or heart attack patients revealed no positive correlation between obesity and carotid atherosclerosis.
Introduction : The cavitron ultrasonic surgical aspirator (CUSA®)is often used for brain tumor surgery. This tool is capable of cutting bone if the CUSA handpiece is exchanged for a scratch-type bone scalpel handpiece (SONOPEr® with scalpel handpiece, M&M Co.) with piezoelectric microvibration. Recently, ultrasonic osteotomy has been widely used in orofacial surgery. spinal surgery. and neurosurgical microsurgery. Therefore, clinical studies of ultrasonic osteotomy using the bone scalpel are required. The aim of this study was to evaluate the effectiveness of ultrasonic scalpel osteotomy by comparing postoperative outcomes. surgical complications. and long—term outcome of osteoplastic laminotomy (OL) over a 3-year period using ultrasonic scalpel osteotomy versus conventional drill surgery (low-speed drill. 8000 rpm, 3M Zimmer). Materials & Methods : We compared retrospectively the outcome between an ultrasonic scalpel osteotomy group (S) and a non-use group (N) in patients who underwent cervical 0L between 1998 and 2003 performed by a single surgeon at our hospital. The evaluated items were operation duration. blood loss, hospital stay, complications. neuroimaging findings, neurological outcome, and 3-year outcome in terms of the Kamofsky scale. Results : The amount of bleeding was significantly lower in the S group (218.3±63.7 ml vs 766.9±572.4 ml; P<0.009), but there was no significant intergroup difference in operation time, hospitalization or spinal canal enlargement revealed by neuroimaging. Neurological outcome and 3-year outcome on the Kamofsky scale showed the same trend. There was no incidence of dural injury. nerve injury. or aspiration-related accident. Conclusions : Use of ultrasonic osteotomy using the piezoelectric effect may reduce the amount of bleeding in patients undergoing OL, and tends to facilitate more accurate laminoplasty and shorter hospitalization. This technique is equivalent to drill surgery in terms of operation time, postoperative outcome. and long-term outcome.
Objective : Improvements in the quality of ultrasound instrumentation have led to its increasing use during neurosurgery. However, as there are fewer reports on intraoperative ultrasound (IOUS) monitoring during spinal-than during intracranial surgery, we discuss its usefulness m spinal surgeiy. Methods : Between February 2006 and June 2007, 65 patients underwent spinal surgery with IOUS monitoring (GE LOGIQ g and 8c microconvex probe). Of these patients. 2 underwent foramen magnum decompression (FMD) for Chiari malformation. 10 laminoplasty, 4 cervical anterior fixation, 9 hemilaminectomy for lumbar canal stenosis, 31 were treated for lumbar disc hemiation, and g underwent tumor removal. Results : In patients undergoing FMD and cervical laminoplasty, pulsation of the cerebellar tonsil and the spinal cord and subarachnoid space anterior to the spinal cord confirmed sufficient decompression. In patients undergoing anterior fixation, decompression of the spinal cord and nerve root was obtained. At surgery for lumbar canal stenosis. decompression of the nerve root ipsi-and contralateral to the approach side was ascertained. During the removal of lumbar disc hemiation, nerve root decompression and residual hemiated material were identified. In patients undergoing removal of a spinal cord tumor. confirmation of its location just after laminectomy facilitated appropriate dural opening. Conclusion : Although IOUS is not widely used by neurosurgeons, it is easily performed. inexpensive, and provides real-time information that cannot be obtained under direct vision. We have found IOUS useful in spinal cord surgery.
Background and Purpose : Metabolic syndrome (MetS) is associated with an increased risk of ischemic stroke. and aortic arch atherosclerotic plaque S4 mm in thickness (AAP) is also associated with ischemic stroke. but the relationship between MetS and AAP is unclear. We investigated this relationship and its impact on ischemic stroke recurrence. Methods : In 475 patients admitted because of acute ischemic stroke during the past two years. we examined 151 patients who wereexamined by transesophageal echocardiography (TEE) and for whom ail data were aailable. We followed up the patients and investigated the relationship between MetS snd ischemic stroke recurrence. Results :AAP was found in 47 patients (31.1%). Multiple logistic regression analysis showed that age and MetS were associated with AAP (age:OR1.07 : 1.02-1.11, p = 0.003, MetS:0R3.11 : 1.44-6.74, p = 0.004) in analysis excluding DM (model 1), and that only age was associated with AAP (OR1.05 : 1.01-1.10, p = 0.004)in analysis exeluding MetS (model 2). During a mean follow-up period of 401 days. there were 19 (12.6%) ischemic stroke recurrences. The Cox proportional hazards regression model showed that only AAP was associated with recurrence (OR2.90 : 1. 16-7.28,0 = 0.023). Conclusions : MetS was associated with AAP in patients with acute ischemic stroke. and conventional risk factors other than aging were not associated. AAP was associated with ischemic stroke recurrence. but MetS was not.
In this study. we calculated the stiffness parameter p of the common carotid artery in children using the radio frequency (RF)echo tracking method. The subjects in this study included 84 patients who underwent cardiac ultrasonography. All had normal cardiac function and no cardiac load. Stiffness parameter was calculated using the following formula: = ln (Ps/Pd)/[(Ds-Dd)/Dd], where Pd and Dd are the end-diastolic pressure and diameter. and Ps and Ds are the end-systolic pressure and diameter, respectively. Parameterβincreased with age (r = 0.58, P<0.0001). Our results demonstrated that arterial stiffness increases with age in childhood. This study provides important information on the reference βvalues in childhood.