Ultrasound has a low enough tissue attenuation coefficient to penetrate intervening tissues and deliver its energy to non-superficial objects, while maintaining the ability to focus the energy into small volumes. This confers a unique advantage over electromagnetic modalities such as laser beams or microwaves when applied to non-invasive and selective treatment of non-superficial tumors. During ultrasonic coagulation treatment, the tissue in the focal zone is heated above the critical temperature at a faster rate than the tissue heat diffusion, resulting in a well-defined coagulation volume similar to the focal spot. However, the small size of the spot leads to a long total treatment time. A split-focus method can multiply the coagulation volume and the throughput of treatment. Cytotoxic effects can be induced ultrasonically by activating specific chemicals by acoustic cavitation. This effect can be used as sonodynamic treatment if cavitation is produced efficiently in a well-controlled manner. Second-harmonic superimposition can reduce the ultrasonic intensity required to produce cavitation by more than one order of magnitude and can produce sonochemically active cavitation with traveling waves without depending on standing waves. A therapeutic system employing both of these new methods of treatment is now being developed.
To clarify the correlation between middle cerebral artery flow velocity during temporary occlusion of the internal carotid artery (ICA) and post-occlusion neurological deficits, the balloon occlusion test was carried out during pre-operative angiography. Seven patients, were selected (four men and three women; aged 35-70 years) . The diagnosis was carotid bifurcation stenosis in two patients, internal carotid-ophthalmic aneurysm in two, carotid-cavernous fistula in one, ICA aneurysmal dilatation due to aortitis in one, and tumor of the neck in one. Two patients had a transient neurological deficit during the balloon occlusion test. The mean pre-occlusion velocities were Vs: 65, Vm: 48 and Vd: 36 cm/s, and post-occlusion velocities were Vs: 19, Vm: 11.5 and Vd: 7 cm/s, with a decrease of 71%, 76% and 81%, respectively. The pulsatile index increased from 0.67 to 1.19, and the resistance index increased from 0.45 to 0.63. The other five patients without neurological deficits had mean pre-occlusion velocities of Vs: 80.4±9.9, Vm: 55.2±10.1 and Vd: 40±7.8cm/s, and post-occlusion velocities of Vs: 57.6±10.2, Vm: 48.4±10.0 and Vd: 40±7.4cm/s, with a decreased of 30±4%, 14±7% and, 1±4.7%, respectively. The pulsatile index decreased from 0.78 to 0.39 and the resistance index decreased from 0.5 to 0.31. The present results indicate that a decrease in Vm, along with a decrease in Vd, correlate well with post-occlusion neurological deficits.
Purpose: The aim of this study was to examine the relationship between plaque morphology and micro embolic signals (MES) detected by transcranial Doppler ultrasonography (TCD) . Patients and Methods: Clinical investigations were carried out on nine patients who underwent carotid endarterectomy (CEA), including carotid B-mode ultrasound of the carotid artery, perioperative TCD monitoring of the middle cerebral artery, and pathological examination of plaques. Patients were divided into two groups, the hyperechoic and hypoechoic group, according to the carotid Doppler ultrasound findings. TCD monitoring was performed 30 min preoperatively and every 3 days after surgery, and the plaques were examined pathologically for the presence of ulceration. Results: Preoperatively, the rate of detection of MES in ulcerative plaques was likely to be higher than that in non-ulcerative plaques. Intraoperatively, the average number of MES was 3.2 in the nine patients who underwent CEA, and the detection rate of MES was likely to be higher in the hypoechoic group than in the hyperechoic group. Postoperatively, no MES were detected. Conclusion: Surgery should be performed with extreme care, especially in patients with hypoechoic or ulcerative plaques. Perioperative sonology is useful for monitoring the safety of CEA.
Antiphospholipid antibody syndrome (APS), which produces various clinical manifestations including arteriovenous thrombosis, recurrent spontaneous abortion, and thrombocytopenia is recognized as one of the causes of cerebral infarction in young people. It has recently been reported that microembolic signals (MES) detected by transcranial Doppler sonography might be related to cerebral ischemia in APS patients. High intensity transient signals (HITS) were studied in a 38-year-old female with APS associated with a lupus-like condition for 15 months after cerebral infarction. Interestingly, both the number of HITS and the acoustic power of HITS increased remarkably during the acute phase. This is the first prospective case report of HITS in an APS patient who developed cerebral infarction.
Blood flow can be visualized at a higher resolution and higher frame rate with the new technique, B-Flow, than with CFM or PDI. Small signals were detected by digitally encoded ultrasound (DEU) using LOGIQ 700 EXPERT Series. DEU is the original GE technique. LOGIQ 700 can transmit the encoded pulses and decode them on receipt in order to improve SNR or to suppress unwanted signals. DEU improves major imaging methods such as B-mode and harmonic imaging, in terms of resolution, penetration and frame rate. The key aspects of B-Flow are Coded Excitation and tissue equalization. Coded Excitation can detect much weaker signals from blood cells. Tissue equalization can reduce non-moving tissue signals to the level of the flow signals; both signals may be displayed simultaneously without overlay (as in color-flow) .