We performed a CT dynamic study during the first pass of an intravenously injected bolus of a iodinated contrast medium, followed by generation of the regional arm-brain circulation time (rABCT) image, in 11 patients with vascular malformations. All lesions could be detected as changes of rABCT, and the comparison with values of normal arteries and veins allowed the deduction of the hemodynamic conditions of the lesions. Seven cases showed evidence of altered distribution of rABCT in the corresponding brain hemisphere, suggesting a perfusion reserve impairment.

Angiography↗

PubMedDate not supplied

Functional vascular volume and blood-brain barrier permeability images by angio-CT in the diagnosis of cerebral lesions.

We performed angio-CT following i.v. administration of an iodinated contrast medium and analyzed the pixel contrast time-density curves from 4 to 10 min postinjection to derive vascular and volume BBB permeability images. This was performed by applying multiple regression analysis of pixel contrast curves versus blood contrast and integrated blood contrast curves. The two regression coefficients, mapped pixel by pixel, correspond respectively to vascular volume and BBB unidirectional transport rate. Initial application in a small number of normal subjects and patients allowed us to characterize areas of steady-state contrast enhancement according to changes of vascular volume and BBB permeability.

Blood Volume↗

PubMedDate not supplied

Functional perfusion and blood-brain barrier permeability images in the diagnosis of cerebral tumors by Angio CT.

We performed rapid sequential CT scanning following iv injection of a bolus of contrast medium and generated three functional images relating to intravascular circulation time (rABCT), vascular volume (Vv) density and blood-brain barrier (BBB) unidirectional constant uptake rate (Ki), respectively. This was accomplished by calculating the first mathematical moment of the monitored time-density curves about the injection time and from the multiple time graph analysis described by Patlack and co-workers. A satisfactory resolution was achieved, allowing separate appreciation of changes in rABCT both in large vessels and in tissue small vessels. Combined evaluation of rABCT and Vv images allowed us to differentiate between tumors.

Blood Volume↗

PubMedDate not supplied

Functional circulation and blood-brain permeability images by Angio CT in the assessment of cerebral ischemia.

We performed rapid sequential computerized tomography (CT) scanning following i.v. injection of a bolus of contrast medium, and generated three functional images related, respectively, to intravascular circulation time (rABCT), vascular volume density (Vv) and blood-brain barrier (BBB) unidirectional constant uptake rate (Ki). This was accomplished by calculating the first mathematical moment of the monitored time-density curves about the injection time, and by the multiple time graph analysis described by Patlack and coworkers. A satisfactory resolution was achieved, allowing separate appreciation of changes in rABCT both at large vessels and at tissue small vessels. Combined evaluation of rABCT and Vv images allowed us to draw qualitative conclusions about blood flow and perfusion reserve.

Basilar Artery↗

PubMedDate not supplied

Functional circulation images by angio-CT in the assessment of small deep cerebral infarctions.

We analyzed circulation time (rABCT) and vascular volume density images obtained by angio-computerized tomography (angio-CT) in 63 patients with small deep cerebral infarctions. Abnormalities in the rABCT image were found in 88% of the patients and in the vascular volume image in 48%. Two groups with different clinical pictures were picked out by rABCT changes: one with major-vessel involvement, the other with small-vessel involvement. The perfusional changes found were mainly due to altered vascular canalization rather than to altered vasomotility. The hemodynamic theory could explain the spatial relations between perfusion changes and CT hypodense areas without needing assumptions linking blood flow and metabolism.

Blood Viscosity↗

PubMedDate not supplied

Virus-inactivated factor VIII concentrate prevents postoperative bleeding in a patient with von Willebrand's disease.

A patient with von Willebrand's disease underwent cholecystectomy after replacement therapy with a factor VIII concentrate that had been sterilized by treatment with tri(n-butyl)phosphate and Tween 80. The patient received 53 units of factor VIII per kg of body weight prior to operation. In addition, a total of 280 units of factor VIII per kg was infused within 10 days after operation. This replacement regimen prevented excessive bleeding during surgery and supported normal hemostasis during the postoperative period. Analysis of the multimeric pattern and the functional assay of von Willebrand factor in factor VIII concentrates indicated that the procedures utilized for virus inactivation had no significant deleterious effect upon the quality of von Willebrand factor molecules.

Adult↗

PubMedDate not supplied

Congenital microangiopathic hemolytic anemia and thrombocytopenia with unusually large von Willebrand factor multimers and von Willebrand factor-cleaving protease.

Infantile or congenital cases of thrombotic microangiopathy have been reported that were familial and characterized by ongoing microangiopathic hemolysis and thrombocytopenia in the absence of regular fresh-frozen plasma transfusions. The authors describe a child with congenital microangiopathic hemolytic anemia and thrombocytopenia (CMHAT) who has received regular fresh-frozen plasma transfusions since infancy and has never had thrombotic complications. von Willebrand factor (vWF)-cleaving protease activity was studied in the patient's pretransfusion and posttransfusion plasma samples as well as in her parents' plasma. The effects of the patient's and a control subject's plasma on human microvascular endothelial cells were also investigated. Unusually large vWF multimers were present in the patient's plasma both before transfusion (thrombocytopenic) and after transfusion. Unlike cases of chronic relapsing thrombotic thrombocytopenic purpura, vWF-cleaving protease activity was present and treatment of cultured human endothelial cells with the patient's plasma did not induce apoptosis. These findings suggest that the patient with CMHAT may represent a different group in the broad spectrum of thrombotic microangiopathies.

ADAM Proteins↗

PubMedDate not supplied

Variable degradation of factor VIII-related protein in lyophilised concentrates of antihaemophilic factor (AHF).

Factor VIII-related properties (coagulant = VIII : C, 'Willebrand' factor = VIII R : WF, antigen = VIII R : AG) are measured in a constant proportion in normal plasma and certain preparations of highly purified factor VIII (relative ratios: 0.5--1.5). We tested these activities in some commercial, lyophilised concentrates of factor VIII and found a variable increase of the ratio VIII R : AG/VIII R : WF. The relative increase of VIII R : AG, and/or loss of VIII R : WF, was attributed to variable degradation of factor VIII-related protein(s) which was directly visualized by electrophoresis on 2.75% polyacrylamide gels in the presence of sodium dodecyl sulphate.

Antigens↗