Measurement of endothelial function is useful in atherosclerotic clinical research. Although optimal methodology for evaluating endothelial function has yet to be determined, it is one of the most useful methods of using ultrasonography to evaluate flow-mediated dilatation (FMD). FMD increases with increase in concentration of nitric oxide (NO), which is induced by shear stress. Impaired FMD reflects loss of NO, which correlates with early onset of atherosclerosis. FMD measurement requires a laboratory equipped with a high-resolution ultrasound linear array probe (7-15MHz) and an arm rest with a stereotactic clamp. Recently developed echo-tracking systems are preferable because they more easily visualize the vessel without producing compression and mechanical distortion. Ideally, patients should be fasting and measurements should be taken in the morning. The cuff should be placed on a radial artery; degree of cuff inflation is standardized to 50 mmHg above the patient′s systolic pressure; duration of cuff inflation should be 5 minutes; brachial artery FMD should be calculated; and nitroglycerin-mediated dilatation should be also evaluated. FMD measurements can be used to detect early coronary artery disease, cerebral artery disease, or peripheral artery disease in the clinical setting. Further, some reports indicate that FMD can be also used to predict the prognosis of cardiovascular events. In summary, FMD measurement using ultrasonographic technology provides a simple and useful way to evaluate endothelial function, which is correlated with early atherosclerosis.

View full abstract

We assessed the usefulness of ultrasonography in the lungs. We attempted qualitative diagnosis of subpleural lesions by power Doppler sonography, fast fourier transformation (FFT) analysis, three-dimensional color Doppler sonography, Levovist^®- and Sonazoid^®-enhanced ultrasonography, and B-flow color. Other clinical applications are US-guided biopsy using color Doppler sonography, response evaluation in lung cancer, and body surface ultrasound-guided bronchofiberscopy. We herein report that ultrasonography is equally useful in the lungs as compared with other regions.

View full abstract

In patients with acute ischemic stroke, transcranial Doppler (TCD) sonography is mainly used to detect microembolic signals with long-term monitoring, and it provides important information for stroke mechanisms and the effectiveness of antithrombotic agents. TCD is also useful to check the presence of right-to-left shunt via heart/lung with intravenous injection of gas microbubbles during the Valsalva maneuver. Transcranial color-coded sonography (TCCS) is mainly used to evaluate occlusive intracranial arteries and collateral cerebral circulation via the circle of Willis. TCD/TCCS are simple and noninvasive procedures that are convenient for repetitive real-time evaluation at the bedside. The therapeutic time window for ischemic stroke is about 3 to 6 hours from onset, and early recanalization of the occluded artery within the time window is strongly associated with a good clinical outcome. TCD/TCCS are the only useful tools to monitor the recanalization status of the occluded artery in the very short time window. The image resolution of TCCS is inferior to that of digital subtraction angiography, 3-dimensional CT angiography, and magnetic resonance angiography, and interpretation of examination results may be affected by the skill of the examiner. Education and training are essential for TCD/TCCS to serve as standard imaging modalities in patients with cerebrovascular disease. Recently, it was reported that the combination of TCD/TCCS with intravenous plasminogen activator (rt-PA) therapy in patients with hyperacute ischemic stroke, i.e., sonothrombolysis, shows promise in terms of improving the recanalization rate of occluded arteries and the clinical outcome. The additional usage of an ultrasound contrast agent (Levovist^®) with rt-PA therapy and TCD may further increase the recanalization rate. In Japan, Furuhata et al. found that 500-kHz continuous wave ultrasound was safe and effective for accelerating clot lysis in in vitro and in vivo experiments. A new integrated device with a commercially available diagnostic unit and a therapeutic unit with a 500-kHz continuous wave probe is already being developed, and a clinical trial for hyperacute ischemic stroke will be conducted in the near future.

View full abstract

Severe carotid artery stenosis is a principle causes of ischemic stroke. For the patient with carotid stenosis, carotid endarterectomy (CEA) and carotid artery stenting (CAS) can prevent ischemic cerebrovascular diseases. In these carotid interventions, periprocedural neurological complications are caused primarily by (1) distal embolism, (2) decrease cerebral blood flow, and (3) hyperperfuion. Periprocedural transcranial Doppler (TCD) monitoring can detect changes in blood flow velocity and microemboli in real-time and, is useful for early detection and management of complications. In CEA, TCD detected microembolic signals (MES) during dissection and wound closure, >90% middle cerebral artery (MCA) velocity decrease during the period of cross-clamping, and >100% pulsatility index increase at clamp release, all of which have been associated with intraoperative stroke. In CAS using balloon protection devices, >90% MCA velocity decrease at balloon occlusion and MES after balloon protection release are related to development of neurological symptoms and new ischemic lesions. In CAS using filter protection devices, decrease in MCA velocity during protection suggests occurrence of no flow/slow flow phenomenon, both of which are associated with higher risk of distal embolic stroke. In both CEA and CAS, post-operative >100% increase in MCA velocity may be associated with development of hyperperfusion syndrome. TCD monitoring thus appears useful during and after carotid interventions when monitoring is deemed necessary.

View full abstract

Sonazoid^®, a second-generation contrast agent, was approved in 2007. It offers in vivo stability, and contrast effects are due to resonance without destruction, allowing real-time perfusion of brain tissues. Its use also allows a new technique, the flush-replenishment (FR) method. This method breaks the contrast agent in the scan volume by high acoustic pressure, followed by observation of replenishment, which enables repeated evaluation of perfusion imaging. We could evaluate not only the main trunks of the cerebral arteries but also the microvasculature in real time, and accumulation combined with the FR method enabled us to delineate the microvasculature. Semiquantitative evaluation of brain perfusion including vasodilatory reserve capacity using acetazolamide could also be assessed by setting regions of interest and creating a time-intensity curve. This method may be useful in the evaluation of cerebrovascular reserve capacity in patients with occlusive cerebrovascular diseases, such as in the decision-making process for bypass surgery Transcranial contrast-enhanced ultrasonography is less invasive and is feasible at the bedside. This method allows real-time evaluation of the vascular anatomy following perfusion of the brain parenchyma, even though there is a limited window of observation. We hope Sonazoid^® will be approved for use in the cerebrovascular region.

View full abstract

Conventional sonographic study is defined by the two-dimensional (2D) method. However, 2D sonographic images are sometimes difficult to understand, and it may be difficult to reproduce the image of a given slice after the examination. Sonographic three-dimensional (3D) images are usually made using a freehand method, which introduces the problems of distortion, reconstruction, and image accuracy. We sought to study the brain using this new 3D sonographic modality. This modality was enabled by the development of a transducer capable of interpreting the entire volume of the target internal tissue in a single two-dimensional image. This transducer contains more than 2500 elements, as opposed to the previous conventional transducers with about 128 elements. After the examination, volume data can be used to calculate the distance, area and volume of the object. Method: This sonographic 3D study was carried out using the iE33 ultrasound system with an X3-1 probe that was able acquire dynamic 3D images in real time. We analyzed the volume data and reconstructed such images as the surgeon′s view, perfusion images, and optional cross sections of the target, and also calculated distance, area, and volume. Results and discussion: The new 3D sonographic modality produces ideal images in real time, images that are dynamic but not distorted. Further, the 3D images are superior in terms of orientation, sensitivity to the skill of the examiner, and ability to analyze volume data. We can detect brain perfusion by contrast-enhanced sonographic pulse inversion harmonic imaging (PIHI). The real time contrast sonographic imaging method with pulse inversion harmonic imageing has revealed some characteristics of cerebral perfusion. Perfusion was observed through real time 3D perfusion images using Matrix array. We are convinced of the usefulness of this method for use in perioperative neurosurgical studies.

View full abstract

The leading causes of cerebral injury during cardiovascular (CV) surgery are cerebral blood flow (CBF) insufficiency and embolism. TCD can detect both CBF velocity and micro-emboli in cerebral arteries. However, the middle cerebral artery (MCA) cannot always be detected by the temporal bone approach in elderly Japanese, in whom monitoring of the extra-cranial internal carotid artery (ICA) by the infra-mandible approach is recommended. CBF velocity measured by TCD is useful for cardiopulmonary bypass or selective cerebral perfusion. Most HITS/MES detected by TCD during CV surgery indicate micro-bubbles. However, many micro-bubbles cause cerebral injury. Cerebral protection therapy is needed in case numerous HITS/MES are detected during CV surgery.

View full abstract

Cranial ultrasonography is an essential examination for newborns and infants. Its use avoids exposure to radiation and the need to sedate the patient. Further, ultrasonography can be used repeatedly at the bedside and with good resolution. We use a sector probe because the narrow anterior fontanella serves as the echo window. Echo images obtained from newborns and infants are very clear. We establish four basal sections in the saggital and coronal regions to maintain the objectivity of the images. The major advantage of cranial ultrasonography derives from its ability to visualize shape using B mode. Ultrasonography is the method of choice in diagnosing cranial hemorrhage, periventricular leukomalacia, infections (congenital cytomegalovirus infection, encephalitis and meningitis), malformation (Dandy-Walker syndrome, and agenesis of the corpus callosum). The pathophysiology of newborn asphyxia, cranial hemorrhage, and hydrocephalus can be estimated from cranial blood flow. Three dimensional ultrasonography is a new technology now being used to examine various organs. It enables us to measure the volumes of the lateral ventricles and grasp the shape of objects in three dimensions. Although, histologic diagnosis using ultrasonography remains difficult, RF signal analysis may make it possible.

View full abstract

Objective: To evaluate sonographic confirmation of nasogastric tube placement. Materials and methods: (1) A nasogastric tube in water was examined by ultrasonography. (2) A nasogastric tube in a healthy volunteer was examined by ultrasonography. (3) Nasogastric tube placement was examined by ultrasonography in 10 patients who had a nasogastric tube inserted to treat their diseases and for whom the placement had already been confirmed by radiography. Results: (1) The nasogastric tube was visualized as two to four hyperechoic parallel lines in longitudinal view. (2) The nasogastric tube was visualized both at the cervical esophagus and the abdominal esophagus. Nasogastric tube placement was confirmed. (3) Of 10 patients, the nasogastric tube was visualized at the cervical esophagus in eight patients and at the abdominal esophagus in four patients. Conclusion: Nasogastric tube placement can be confirmed by ultrasonography.

View full abstract

Purpose: To evaluate the significance of amniotic pocket (AP) measurements after 37 weeks of gestation for assessing the possibility of occurrence of non-reassuring fetal status (NRFS) during labor. Methods: The study population consisted of term patients (37-41 weeks of gestation) with singleton pregnancy, excluding admissions due to preterm rupture of membrane and for elective cesarean section (n=966). Subjects were divided into the following three groups; Group A: diagnosed as oligohydramnios during outpatient check-up, Group B: diagnosed as oligohydramnios at admission with onset of labor, and a control group. Frequencies of prompt delivery (emergent C/S or instrumental delivery) due to NRFS in each group were evaluated, and cutoff values of AP to predict prompt delivery were calculated. We also assessed sequential changes in AP before diagnosis of oligohydramnios. Results: The number of cases in Group A, Group B, and control were 26 (2.7%), 75 (7.8%), and 865 (89.5%), respectively. Frequencies of prompt delivery due to NRFS in Group A and B were 26.9% (p<0.001) and 16.0% (p=0.015), respectively, which were higher than control (7.9%). Frequencies of emergency cesarean section in Group A and control were 14.3% and 2.6%, respectively, and these were significant difference between them (p<0.001). A cutoff value of AP for predicting prompt delivery was calculated as 21 mm based on ROC curve. In the group diagnosed with oligohydramnios, AP was in the range of 20-30 mm 2 weeks and 1 week before the diagnosis in 65% and 83% of the cases, respectively. Conclusion: Measurement of AP is useful for predicting non-reassuring fetal status during labor in not only outpatients but also inpatients with onset of labor. Our results suggest that cases in which AP is less than 30 mm at outpatient check-up require intensive follow-up.

View full abstract

Calcific tendinitis of the longus colli is an under-recognized cause of acute cervical pain. Clinically, it can be misdiagnosed as retropharyngeal abscess, meningitis, or traumatic injury. The diagnosis is made radiographically by identification of prevertebral soft tissue calcification. We present a case of calcific tendonitis of the longus colli detected by ultrasonography. The case was a 92-year-old man with a chief complaint of fever and posterior headache. MRI revealed diffuse swelling of the longus colli muscle as the signal intensity changed, especially on T2-weighted images. Although plain X-ray and CT did not show prevertebral soft tissue calcification, cervical ultrasonography revealed calcification of the longus colli. The patient was treated by medication with NSAIDs and local rest using a neck collar. After 11 days, MRI showed disappearance of soft tissue swelling, and ultrasonography revealed a decrease in the calcification. Ultrasonography may be useful for diagnosis of calcific tendonitis of the longus colli muscle.

View full abstract