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Biomedical subjects

B Sigel

Publications and source records attributed to B Sigel.

135 records · Page 8Linked to original sources
PubMedDate not supplied

Accuracy of intraoperative ultrasonography in diagnosing liver metastasis from colorectal cancer: evaluation with postoperative follow-up results.

The accuracy of intraoperative ultrasonography in diagnosing liver metastasis was evaluated at the time of surgery and at follow-up in 189 patients with colorectal cancers. Evaluation at the time of operation revealed that the sensitivity of intraoperative ultrasonography (93.3%) was significantly (p less than 0.0001) higher than that of preoperative ultrasonography (41.3%), conventional computed tomography (47.1%), and surgical exploration (66.3%). Twenty-two of 104 metastatic liver tumors were detected solely by intraoperative ultrasonography in 18 patients (9.5% of total patients). These 22 tumors were small in size (4 x 4 mm to 15 x 18 mm) and nonpalpable during operation. During the postoperative follow-up period of 18 months or more (mean 35.6 months, median 37.1 months) after colorectal surgery, liver metastases that were unrecognized during surgery appeared in 13 (6.9%) patients. Re-evaluation based on these follow-up results indicated that the sensitivity of intraoperative ultrasonography decreased to 82.3%, which was still significantly (p less than 0.0005) better than that of other methods. Intraoperative ultrasonography was capable of identifying 18 of 31 (58.1%) patients in whom liver metastases were otherwise unrecognized at the time of operation. Intraoperative ultrasonography is more accurate in diagnosing liver metastasis than traditional screening methods, and may have a beneficial impact on the management of colorectal cancer.

Colorectal Neoplasms↗
PubMedDate not supplied

Ultrasonography of blood during stasis and coagulation.

A series of in vitro and animal experiments were performed to determine ultrasonic features of blood during stasis and coagulation. Liquid whole blood became echogenic within a few seconds to 3 minutes following the onset of stasis. This occurred in citrated human blood allowed to stand and in occluded segments of vena cava and aorta of dogs. Mechanical agitation of the blood in stasis caused a disappearance of echoes. This echogenicity occurred with gray-scale and real-time ultrasonography using 7.5-mHz transducers, but was not observed with 3.5-mHz transducer used in real-time scanning. Whole blood clot was echogenic both with 7.5- and 3.5-mHz scanning. Fibrin clot was sonolucent. Echogenicity with stasis did not occur with plasma, serum, or packed erythrocytes. The development of echogenicity required the presence of fibrinogen or its products plus erythrocytes. The echogenicity of blood during stasis detectable by high-frequency ultrasonography probably was related to physical layering of blood products. The disappearance of reflective echoes following agitation suggested that the layering could be readily disrupted.

Animals↗
PubMedDate not supplied

Effect of plasma proteins and temperature on echogenicity of blood.

An explanation is proposed for the echogenicity to ultrasound scanning at 5 mHz and above of unclotted blood under conditions of stasis. In vitro experiments using blood from normal subjects and from patients with myeloma revealed that: 1) lysis of red cells prevented echogenicity, 2) echogenicity increased with increasing hematocrit, fibrinogen and other macromolecules, and temperature, and 3) blood from myeloma patients showed increased echogenicity and rouleau formation, a form of aggregation seen on peripheral smears. From these experiments it was concluded that red cell aggregation is a major cause of echogenicity of unclotted blood, requiring both intact red cells and conditions which are known to enhance red cell aggregation, such as the presence of macromolecules and increased temperature.

Blood↗
PubMedDate not supplied

Ultrasonic detection of red cell aggregation immediately preceding blood clotting.

High-resolution ultrasonic imaging of circulating blood was used to study the relation between red cell aggregation and blood clotting in vitro. A reversible increase in echogenicity produced by red cell aggregation occurred in moving heparinized blood as shear rate was decreased. We induced clotting of the heparinized blood by administration of protamine. At both low (1.6 sec-1) and moderate (22.6 sec-1) mean shear rates, transient homogenous increased echogenicity indicative of red cell aggregation preceded blood clotting. In separate experiments, we established that protamine can cause increased echogenicity due to red cell aggregation which can be reversed by adding heparin to circulating suspended red cells in the absence of clotting factors. Presumably, these effects of protamine and heparin are due to electrostatic bonding involving red cell surfaces. We conclude from these studies that red cell aggregation precedes clotting of heparinized blood by protamine at low and moderate shear rates.

Blood Coagulation↗
PubMedDate not supplied

Detection of experimental arterial defects by portable and serial biplanar operative arteriography.

The accuracy of arteriography in detecting vascular defects similar to those encountered during vascular surgery was evaluated experimentally. Intimal flaps, thrombi, and strictures were created in dog aortas and studied under circumstances resembling operating room conditions by single-view portable and serial biplanar contrast arteriography. The specificity of both types of arteriography was comparable and high for detecting vascular defects. The sensitivity for diagnosing strictures was also comparable and high. However, both radiographic techniques were relatively insensitive in the detection of small intimal flaps and thrombi. In the detection of these two types of defects, serial biplanar arteriography was significantly more sensitive than portable arteriography. The degree of the superiority of serial bi-plane and the possible clinical insignificance of small defects indicates that portable arteriography in the operating room may still be an adequate methodology.

Angiography↗