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Biomedical subjects

B Sigel

Publications and source records attributed to B Sigel.

At least 37 records · Page 2Linked to original sources
PubMed1992

Cellularity and fibrin mesh properties as a basis for ultrasonic tissue characterization of blood clots and thrombi.

This in vitro study was designed to evaluate the ability of ultrasonic tissue characterization (UTC) based on power spectrum analysis of backscattered radio-frequency echo signals to distinguish two prominent variables of thrombi: cellularity (primarily red cell content) and fibrin-mesh density. Six types of clots simulating thrombus components were prepared by varying red-cell and platelet concentrations and shear forces during clotting. Data were acquired with a linear-array transducer, digitized, and analyzed in terms of slope and intercept parameters obtained from normalized power spectra of radio-frequency echo signals. Increased cellularity and fibrin-mesh density both produced lower slope and higher intercept values, which permitted statistically significant discrimination of cellularity and mesh density in the six types of clots analyzed. Shearing forces and (to a lesser degree) platelet concentrations increased fibrin-mesh density. This study suggests that UTC based upon the power spectrum of echo signals may be used to detect and follow compositional differences that have clinical relevance in the diagnosis and follow-up of thrombi.

Blood Coagulation↗
PubMed1992

Operative color Doppler imaging for vascular surgery.

Operative color Doppler imaging (CDI) was performed during 57 vascular operations (24 carotid, 24 lower extremity, six renal artery, and three other operations), and its benefits were assessed in comparison to B-mode imaging. Pre-reconstruction operative CDI was used selectively in 18 operations, and post-reconstruction operative CDI was used routinely in all operations. In 16 operations (28.6%), post-reconstruction CDI diagnosed vascular defects such as intimal flaps (n = 4), anastomotic stenoses (n = 7), and in situ bypass arteriovenous fistulas (n = 4). Vascular defects at eight operations required immediate repair. Operative CDI had advantages over B-mode imaging in (1) detection of preoperatively unknown vascular abnormalities before reconstruction, (2) faster recognition of vascular defects after reconstruction, (3) unique ability to detect problems (i.e., arteriovenous fistulas) that were unidentifiable by B-mode imaging, and (4) provision of supplemental blood flow information.

Blood Flow Velocity↗
PubMed1992

Intraoperative ultrasonography.

Four major benefits of intraoperative ultrasonography (IOU) were determined after its use in more than 2400 operations. They are the acquisition of new information not otherwise available, complement of or replacement for operative radiography, guidance of surgical procedure, and confirmation of completion of operation. IOU also has the advantages of safety, speed, higher accuracy, acquisition of more information, and wider application over operative radiography. Intraoperative color Doppler imaging, which has been introduced recently, seems to provide additional beneficial information during cardiovascular and general surgery. We believe that IOU should have a wider application and that surgeons and radiologists should develop cooperative working relations similar to those that exist for operative radiography.

Cardiovascular System↗
PubMed1992

The value of operative ultrasonography in diagnosing tumor extension of carcinoma of the stomach.

Operative ultrasonography was performed during operations to improve the accuracy of diagnosing the extent of the spread of carcinoma of the stomach in the following areas: tumor invasion in the gastric wall (31 patients), para-aortic lymph node metastasis (30 patients) and hepatic metastasis (30 patients). The over-all diagnostic accuracy rates of operative ultrasonography were 81 per cent for determining the depth of tumor invasion, 80 per cent for carcinoma of the mucosa, 70 per cent for carcinoma of the submucosa, 83 per cent for carcinoma of the proper muscle, 80 per cent for carcinoma of the subserosa and 100 per cent for carcinoma of the extraserosa. The over-all accuracy of operative ultrasonography in diagnosing para-aortic lymph node metastasis was 93 per cent. In comparison with the results of preoperative studies, the accuracy (sensitivity) of operative ultrasonography was significantly superior in diagnosing metastasis to the lymph nodes. In three of 30 operations, preoperatively unrecognized and nonpalpable (occult) hepatic metastases were identified by operative ultrasonography. Operative ultrasonography provides more accurate information regarding the spread of carcinoma of the stomach, and thus may be helpful in deciding upon the type of surgical procedure or in avoiding unnecessary tissue dissection.

Carcinoma↗
PubMed1991

Technique of ultrasonic detection and mapping of abdominal wall adhesions.

A technique for noninvasive ultrasound examination to detect and map abdominal wall adhesions is described. The examination is based on the demonstration of movement of abdominal viscera during real-time imaging. This movement is called viscera slide and either occurs spontaneously as a result of respiratory movement or may be induced by manual compression. Abdominal wall adhesions produce a restriction of viscera slide. Ultrasonic demonstration of restricted viscera slide has been used for the precise localization and mapping of abdominal wall adhesions prior to abdominal surgery. The technique may be particularly useful in providing safe initial access in patients undergoing laparoscopy who are at increased risk for trocar injury of viscera due to abdominal wall adhesions resulting from previous surgery or peritonitis.

Abdominal Muscles↗
PubMed1991

Surgical treatment of peptic ulcer disease.

Elective surgery for peptic ulcer disease has diminished significantly over the past 15 years. However, emergency surgery has not shown a decline. Some series have even reported an increase in hospitalizations and operations for hemorrhage. The appropriate surgical procedure for peptic ulcer disease must be tailored to the specific needs of the individual patient. During emergency operations for hemorrhage from duodenal ulcer, we recommend suture ligature of the bleeding vessel and vagotomy-pyloroplasty for high-risk patients, or vagotomy-antrectomy for the lower-risk patient. Bleeding gastric ulcers should be resected, if possible. For massive hemorrhage from stress ulceration requiring surgery, near-total or total gastrectomy should be performed. Perforated duodenal ulcers are best managed by closure and a definitive ulcer operation, such as vagotomy-pyloroplasty. Perforated gastric ulcers are best excised but may be simply closed if conditions do not favor resection. In these situations, biopsy should be performed. We recommend truncal vagotomy-antrectomy for patients presenting with obstruction. Vagotomy (truncal or proximal gastric) with drainage is an acceptable alternative in this situation. For patients with intractable ulcer disease or for those who are noncompliant, proximal gastric vagotomy is the preferred operation. However, other operations may need to be considered, depending on the specific situation. Recurrent ulceration needs appropriate work-up to determine the possible cause. Although patients with ulcer recurrence initially may be placed on medical treatment, about 50% will require reoperation. The most effective procedure for peptic ulcer disease is truncal vagotomy-antrectomy, which has a recurrence rate of less than 1%. The procedure with the least morbidity and the fewest undesirable side effects is proximal gastric vagotomy. Ulcer recurrence after proximal gastric vagotomy or truncal vagotomy-pyloroplasty is in the range of 10% to 15%.

Gastrectomy↗
PubMed1991

Detection of preoperatively unrecognized multiple pancreatic pseudocysts by intraoperative ultrasonography. Report of two cases.

During two pancreatic operations, intraoperative ultrasonography detected multiple pancreatic pseudocysts that were unrecognized preoperatively. In each operation, a single pseudocyst was detected by preoperative ultrasonography, computed tomography, and intraoperative surgical exploration. In addition, high-resolution ultrasonography used during the operations also identified and precisely localized additional smaller pseudocysts. Also, the use of color Doppler imaging during the operations enabled the delineation of small blood vessels around the pseudocysts. The accurate diagnosis of multiple pseudocysts and the precise anatomic information provided by intraoperative ultrasonography permitted appropriate surgical treatment of the pancreatic pseudocysts which, in turn, might help prevent recurrence of the disease.

Adult↗
PubMed1990

Transdiaphragmatic liver scanning: a new intraoperative imaging technique for examination of the liver from the thoracic cavity.

In order to examine the liver during thoracotomy, a new intraoperative imaging technique called "transdiaphragmatic liver scanning" was developed. Transdiaphragmatic scanning performed with high-frequency transducers provided clear visualization of the entire liver from the thoracic cavity through the diaphragm. In our study, transdiaphragmatic scanning was used in 27 thoracotomy operations performed for the treatment of malignant diseases, including lung and esophageal cancers. One 5-mm liver cyst, one 3-mm x 4-mm hemangioma, and one 5-mm x 6-mm ill-defined lesion (possible metastasis), all of which were unrecognized preoperatively, were detected. In 3 operations, preoperatively suspected liver metastases were excluded by transdiaphragmatic scanning. Because transdiaphragmatic scanning provides high-resolution images of the liver and is the only method capable of examining the liver during thoracotomy, this intraoperative scanning technique may become a useful tool in the evaluation of liver metastases from thoracic or mediastinal malignancies.

Cysts↗
PubMed1990

Operative ultrasound guidance for various surgical procedures.

Although percutaneous ultrasound-guided technique is currently a common practice, the use of ultrasound for the purpose of guidance during surgery has not been widely practiced. Over a period of 10 years, we performed operative ultrasonography in 2,314 operations. In 321 of these operations, operative ultrasound guidance was performed for direct assistance of various surgical procedures, particularly during operations on the brain and spinal cord, liver, pancreas, and kidney. Procedures guided by operative ultrasound were classified into the following categories: intraoperative needle placement for fluid aspiration (n = 38), agent injection (n = 14), catheter introduction (n = 27), biopsy (n = 57), surgical tissue dissection for incision (n = 48), resection (n = 82) of organs, and extraction (n = 55) of stones or foreign bodies. Operative ultrasound guidance facilitates various surgical procedures and is considered a useful modality for reducing operative complications, shortening operating time, performing otherwise impossible procedures, and, at times, developing new surgical operations.

Humans↗
PubMed1990

Ultrasonic tissue characterization of blood clots.

Ultrasonic tissue characterization based on an analysis of the power spectrum of backscattered signals obtained with ultrasound was used to distinguish morphologic components of blood clots. The three morphologic features for which discrimination was attempted were loose fibrin, red-cell, and dense fibrin clots. The UTC was able to distinguish the morphologic blood components tested. This in vitro work was based on the analysis of parameters related to ultrasound-tissue interaction and on inferences related to the physical properties of scatterer properties (scatterer size, scatterer concentration, and ratio of scatterer to medium acoustic impedances). The ability to distinguish these blood-clot components suggests that UTC may be able to distinguish red from white thrombi and to assess the structures and changes within thrombi associated with the age of the thrombus, their mechanical properties, and treatment monitoring.

Blood Coagulation↗
PubMed1990

University-based postresidency training programs in surgical oncology.

The issue of postresidency training in surgical oncology engenders much debate, particularly as it impacts on general surgery training. With the goal of enhancing instruction in surgical oncology in the future, a survey was conducted to assess the role of surgical oncology programs and educational activities within university-based surgery training programs. The results of the study demonstrate an increased emphasis on surgical oncology training over the past five years. The findings also indicate that education activity in surgical oncology in all departments of surgery has increased greatly, as demonstrated by an increased number of specific teaching rounds and conferences. The impact of this increased awareness on the future of surgical oncology training is discussed.

Curriculum↗
PubMed1989

The fate of unrepaired minor technical defects detected by intraoperative ultrasonography during carotid endarterectomy.

This report describes the natural history of unrepaired minor technical defects detected by intraoperative B-mode ultrasonography during carotid endarterectomy. Intraoperative ultrasonography was used to assess the technical adequacy of 80 carotid endarterectomies. Sixty-two arteries were normal on intraoperative ultrasound examination, whereas the remaining 18 arteries had a total of 21 minor residual technical defects. The 21 minor defects consisted of four internal carotid artery lesions, nine common carotid artery lesions, and eight external carotid artery lesions, 19 had 1 to 3 mm intimal flaps, and two had small stenoses. Sixteen of the 19 intimal flaps resolved before the first postoperative ultrasound study. These arteries had normal examination results, which indicated that these intimal flaps had healed. The two stenoses detected intraoperatively could not be detected by postoperative carotid duplex scanning at 1 month follow-up. No statistically significant relationship was found between the presence of a minor residual defect on intraoperative ultrasonography and the subsequent development of recurrent stenosis or occlusion in any of the arteries assessed. These data suggest that certain minor technical defects in the carotid artery that were detected by intraoperative ultrasonography are benign and may not require repeat exploration of the carotid artery for repair.

Actuarial Analysis↗
PubMed1989

Ultrasonic evaluation of erythrocyte aggregation dynamics.

The dynamics of aggregation and disaggregation of blood of varying hematocrit in oscillatory flow in a distensible horizontal tube was determined by measuring the developing echo intensity of the blood samples with a 10 MHz B-mode ultrasonic scanner. Early aggregation could be detected within 10 sec. of stoppage of flow. The rate of echo intensity buildup and thus, presumably the rate of aggregation when flow was stopped was inversely related to hematocrit, as was the rate of echo intensity reduction when flow was resumed. Polycythemic blood of 60% hematocrit showed no echo intensity increase over 5 min. Increasing the shear stress when flow was resumed resulted in rapid decreases in aggregation. In all cases, disaggregation following flow resumption was faster than aggregation following flow stoppage.

Adult↗