Real-time Sonograms Research Articles

Real-time image fusion for successful percutaneous radiofrequency ablation of hepatocellular carcinoma.

Percutaneous radiofrequency ablation (RFA) is an established nonsurgical curative treatment for hepatocellular carcinoma (HCC). Because of its efficiency and safety, sonography is the most commonly used imaging modality when performing RFA. However, the presence of HCC nodules that are inconspicuous when using conventional sonography is a major drawback of RFA and limits its feasibility as a treatment for HCC. However, a new technology has been developed that synthesizes high-resolution multiplanar reconstruction images using 3-dimensional data and is combined with a position-tracking system using magnetic navigation. With this technology, real-time sonograms can be fused with corresponding computed tomographic, magnetic resonance imaging, or even sonographic volume data; this process is known as real-time image fusion. In this article, we describe this novel imaging method as a useful tool for successful RFA treatment of HCC.

Delineation of brain tumor margins using intraoperative sononavigation: Implications for tumor resection

Sonography has been employed for real-time intraoperative delineation of tumor boundaries during resection of brain tumors. However, the variably hyperechoic appearance of brain edema or gliosis surrounding the brain may interfere with accurate depiction of tumor margins. The goal of the present study was to use sononavigation, which provides coregistration between real-time sonograms and MRI scans, to assess the accuracy of sonographic determination of tumor margins. Sononavigation was performed on 12 brain tumors (7 metastatic brain tumors, 2 meningiomas, 1 anaplastic oligodendroglioma, 1 anaplastic pilocytic astrocytoma, and 1 anaplastic astrocytoma). Sonograms of tumor margins were categorized into 1 of 3 types: in type 1, the tumor margin was clearly visualized and corresponded to the margin of the enhanced lesion on MR scan in all areas; in type 2, the tumor margin was clearly seen in some areas but was obscure in others due to hyperechoic edema; and in type 3, the tumor margin was indistinguishable from surrounding tissues in all areas. Three metastatic brain tumors and 1 meningioma were categorized as type 1. Three metastatic brain tumors, 1 meningioma, and 1 anaplastic oligodendroglioma were categorized as type 2. The anaplastic pilocytic astrocytoma, 1 metastatic brain tumor (which consisted mainly of necrotic tissue), and the anaplastic astrocytoma were categorized as type 3. These data assist in determining whether the sonographic appearance of tumor margins is accurate and whether to rely on information from either sonography (type 1) or the sononavigation system when resecting tumor types 1, 2, and 3. Sononavigation can help categorize the sonographic tumor margins into 3 different patterns, and this categorization can assist in determining which imaging modalities are needed to better delineate the tumor margins for subsequent resection.

Efficacy of Percutaneous Microwave Coagulation Therapy for Nodular Hepatic Tumor: A Preliminary Study

Purpose: Percutaneous microwave coagulation therapy (PMCT) uses a new energy source, microwave, in the treatment of solid neoplasms. We evaluated the efficacy of PMCT for nodular hepatic tumors in nine patients. Materials and Methods: Between December 1998 and June 1999, we performed PMCT in six patients with hepatocellular carcinoma (HCC), two with one and three metastatic nodules each from colon cancer, and one with adenomatous hyperplasia. Four patients were female and five were male, and their age ranged between 44 and 71 (mean, 58.8) years. Under sonographic guidance a 14-gauge guiding needle was inserted percutaneously toward the lesion, and within it a needle electrode was precisely positioned. Microwave 2450MHz in frequency and with 60 or 80 watt emission was generated for 80~90 seconds. We evaluated the ultrasound findings obtained during the procedure, pre-PMCT and follow-up CT images, changes in tumor marker(AFP or CA19-9) levels and the results of liver function tests, and complications arising during the six-month period following PMCT. Results: Immediately after microwave emission, characteristic hyperechogenicity appeared on the realtime sonogram. Two patients with HCC underwent CT before PMCT, and typical enhancement during the arterial phase and washout during the portovenous phase was observed. In one patient, two metastatic lesions from colon cancer showed delayed enhancement on pre-PMCT CT. Initial follow-up CT, performed between 1 and 4 weeks after the PMCT procedure, showed that eight lesions-including two HCCs which were highly enhanced on CT before PMCT-showed no contrast enhancement, and three others showed delayed enhancement. Two of the eight lesions which showed no contrast enhancement at initial follow-up CT were markedly decreased in size (from 2.9 and 4.0 cm to 1.0 and 2.0 cm, respectively) at subseqent follow-up 3 months and 6 months later, respectively. One of the three lesions showing delayed enhancement had increased in size from 4.1 to 5.5 cm at subsequent follow-up CT, 2 months later. Serum AFP or CA19-9 levels decreased in four of six patients (66.7%) who were followed up for 6 months. Transient elevation of aspartate aminotransferase(AST) levels were noted in all patients. PMCT-related complications included intrahepatic arterioportal shunt in two patients, pleural effusion in one, skin burn in one, intraperitoneal hemorrhage in one, and mild fever, abdominal pain and nausea in seven. No complications were serious, however.Conclusion: Our preliminary experiences suggest that PMCT is a safe and effective treatment modality for nodular hepatic tumors.

A review of the measurement of blood velocity and related quantities using Doppler ultrasound

Ultrasound systems can be used to investigate blood flow by use of the Doppler effect. The flow information may be displayed as either a real-time sonogram or a two-dimensional colour image. Estimates of maximum velocity using commercial systems are in error by typically 10-100 per cent; this is associated with the inability of the single-beam Doppler method to measure the true direction of flow, and with geometric spectral broadening. Vector Doppler systems acquire Doppler information along two beam directions and are able to measure accurately the velocity and direction of motion within the scan plane. The small beam width of modern Doppler systems means that the condition of uniform insonation, required for estimation of mean velocity from mean frequency shift, is not valid except for the very smallest vessels. Other quantities related to the velocity may also be estimated, such as the volumetric flow and wall shear stress. Flow visualization using colour flow imaging suffers from dependence of the displayed colour on the direction of blood motion. The vector Doppler technique may be extended to colour flow to give improved visualization of flow, in which there is no angle dependence within the scan plane.

Sonographic findings following conservative surgery and irradiation for breast carcinoma

Postoperative care of patients who have received conservative surgery for breast cancer and subsequent radiotherapy is of ever greater significance. Both the clinical and the mammographic investigation are difficult in the post-irradiation phase. The present study was designed to appraise the value of real-time sonography in this group of patients. 106 patients were examined postoperatively with a high-resolution hand-held real-time scanner. The following alterations, found in the real-time sonogram, were compared to the normal sonographic appearance: (total echogenicity, feasibility of diagnosing the scar region, skin thickening, double contour of the skin, echogenicity of subcutaneous fat, Cooper's ligaments, striping, echogenicity of glandular tissue, architecture of glandular tissue). These alterations do not deter appraisal of the sonograms in the search for recurrences. Six out of seven recurrences, demonstrated histologically, were detected and correctly diagnosed by sonography. These results make real-time sonography the supplementary method of first choice in postoperative care of conservatively treated breast cancer patients.

Parathyroid carcinoma: high-frequency sonographic features.

The authors reviewed the features on high-frequency (10 MHz), realtime sonograms of parathyroid carcinoma in eight patients to identify characteristics that could preoperatively distinguish malignant from benign lesions. The mean diameter of the eight carcinomas was 2.4 cm. They were typically ovoid or round and had a lobulated contour. The carcinomas were predominantly hypoechoic relative to the adjacent thyroid, but two of the eight contained both hypoechoic and hyperechoic regions, and three contained cystic spaces. Two carcinomas were grossly invasive on ultrasonographic (US) examination, although seven were proved histologically to be invasive. High-resolution US provides a noninvasive means to localize primary and locally recurrent parathyroid carcinomas preoperatively but fails to distinguish carcinomas from large adenomas reliably, except in cases with extensive invasion of adjacent structures.

Ultrasonography of mediastinal teratoma.

We have studied real-time sonograms of 11 surgically proven benign mediastinal teratomas. Eight cystic teratomas were sonographically visualized as various kinds of masses: four complex, two solid, and two cystic. The echo patterns of cystic teratomas were determined by the serous or nonserous nature of the cysts. In the presence of serous fluid, the tumor was visualized as a cystic mass. If, on the other hand, the cyst of the tumor was nonserous or was sebaceous, it appeared as a solid or complex tumor. The remaining three solid teratomas, which had some small cysts, appeared as complex tumors.

Sonographic evaluation of inferior vena caval obstruction: correlative study with vena cavography.

Sonographic findings of obstruction of the inferior vena cava (IVC) in 14 cases are described and correlated with venographic findings. The causes of the obstruction were membrane (five cases), thrombosis (three), and intraluminal tumor invasion by hypernephroma, hepatoma, and adrenal carcinoma in six. Sonographic examination revealed highly echogenic segmental obliteration or membrane in membranous obstruction and echogenic intraluminal mass in thrombotic occlusion. Absence of an identifiable patent lumen in a technically satisfactory study was another finding in thrombotic obstruction. On real-time sonograms, the normal respiratory changes of the IVC were absent when there was complete occlusion. Transhepatic collaterals, patency of other segments of the IVC, and associated malignancy were additional sonographic findings. Comparison to venography suggested that in addition to ease and safety, sonography has advantages in delineation of the cephalad extent of occlusion, dynamic evaluation of the IVC below the obstruction, and the simultaneous evaluation of adjacent organs.

Main systolic blood flow patterns in the left and right ventricular outflow tracts determined by Doppler echocardiography.

The main blood flow velocity patterns in the LVOT and RVOT were recorded by pulsed Doppler echocardiography in 28 normal healthy cases, in two athletes, and in 85 patients with atrial septal defects, pulmonary regurgitation, tetralogy of Fallot, aortic regurgitation, mitral stenosis, aortic stenosis, mitral regurgitation, hypertrophic cardiomyopathy, ischemic heart disease, and pulmonary hypertension. Blood flow velocities were displayed using a graphic system to form a real time sonogram, using Fast Fourier Transformation. In the normal group, the blood flow velocity was 1.69 KHz in LVOT, and 1.71 KHz in RVOT. In AR and T/F but not MS, there was high blood flow velocity in the LVOT, and the peak of blood flow velocity was shifted to mid-to late systole. In ASD and VSD with a L-R shunt, high blood flow velocity occurred in the RVOT, and the peak velocity shifted to early systole. Pulmonary hypertension occasionally produced a W- or V-shaped curve. In normal subjects, a small "a" wave could be detected in the LVOT recording. The "a" wave began at point B on the AML tracer of the M-mode echocardiography, reached maximum velocity at point C, and returned to zero (baseline) at point C'. The "a" wave was coincident with the R wave of the ECG, and with the Ia of the phonocardiogram (PCG). The normal velocity of the "a" wave was 602 Hz, and the a/H ratio was 0.36. In cases of HCM and IHD, the "a" wave velocity and the a/H ratio correlated with the end diastolic pressure and the peak dP/dT. These data suggest that the Doppler blood flow patterns in the LVOT and RVOT can indicate volume overload in the right and left ventricles, and that the "a" wave velocity and a/H ratio can provide new information concerning cardiac performance.

Sonographic assessment of renal length in normal children.

Renal length was measured from normal real-time sonograms of 203 pediatric patients and graphed to provide a "growth chart" of normal renal size vs. age. Mean renal lengths are reported for each year of age. For children older than 1 year, the regression equation is: renal length (cm) = 6.79 + 0.22 X age (years). For babies younger than 1 year, the equation is: renal length (cm) = 4.98 + 0.155 X age (months).

Normal infant brain anatomy: correlated real-time sonograms and brain specimens.

An investigation of the identifiable real-time sonographic features of the normal infant brain in the horizontal, coronal, inclined coronal, and midsagittal planes was undertaken. Correlations were made of sonograms of intact brains in vitro, corresponding brain sections, and sonograms in vivo. A large number of anatomic structures could be consistently depicted including cisterns, fissures, faix cerebri, tentorium cerebelli, ventricles, brainstem, cerebellum, basal ganglia, thalami, and corpus callosum. Pulsations of intracranial arteries, visible by real-time sonography, were of considerable help in identifying various structures. The investigation provides a reference of sonographic anatomy of the brain displayed in four clinically useful imaging planes.