Intracranial circulation: preliminary clinical results with three-dimensional (volume) MR angiography

Article Abstract:

Magnetic resonance (MR) angiography (blood vessel imaging) was used to evaluate vascular anatomy (blood vessels) in 40 patients with suspected cerebrovascular disease (damage to the blood vessels in the brain). A three-dimensional MR imaging technique was used to measure changes in direction and speed of cerebral blood flow to determine the volume capacity of blood vessels supporting various portions of the cerebral (brain) anatomy. Cerebrovascular disease (CBV) is characterized by ischemia (tissue starved for oxygen due to poor blood flow) or bleeding (hemorrhage). An advantage of MR angiography, versus other means of evaluating CBV, is its noninvasive nature. MR also provides multiple images of complex areas of brain anatomy in which blood vessel abnormalities may occur. MR angiography was able to evaluate blood vessel openings (patency) in small vessels, which is a useful adjunct in the examination of young children. Pediatric angiography is frequently limited by the inability of young children to tolerate anesthetics and contrast agents (substances injected to enhance image quality) needed to image small blood vessels. MR angiography does not require injection of a contrast agent nor does it require anesthesia. The technique used in the research was not able to provide good images in cases of suspected vascular occlusive (blockage) disease, nor was it successful in demonstrating lesions (areas of abnormal tissue growth) with slow blood flow. Researchers conclude that the technique employed in this study can provide accurate images of intracranial blood circulation when performed in conjunction with more standard two-dimensional MR imaging techniques. It was most useful in evaluating patients with intracranial aneurysms (bulging of blood vessels at weak points in the vessel walls).

Case studies, Brain hemorrhage, Blood vessels, Angiography

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Carotid artery reconstruction following extracorporeal membrane oxygenation

Article Abstract:

Extracorporeal membrane oxygenation (ECMO) is a technique of oxygenating the blood using an artificial membrane located outside of the body; it is used to treat infants with severe lung disease. Although the technique is associated with a high rate of complications and death, it has been used to maintain children who are at great risk from respiratory damage. ECMO is described as increasingly successful (some reports as high as 92 percent) in the treatment of newborns who have shown no improvement with less invasive techniques. In most cases the technique involves rerouting blood returning from the tissues to the vena cava into the ECMO unit, where gas exchange and oxygenation occur. From there the blood is returned to the body by a catheter into the right carotid artery. Previous procedures have permanently tied off the carotid artery, one of the principal arteries supplying the brain, at the point that the need for ECMO has ended. However, a new technique involving reconstruction of the carotid artery after removal of the catheter has been used with some success. The present study compares four cases in which the carotid artery was repaired after removal of the ECMO equipment with one case in which the artery was tied-off (ligated) following the end of ECMO therapy. All children who underwent repair of the carotid artery were spared neurologic damage, which is a frequent consequence of ECMO treatment and carotid artery ligation. The blood flow through the carotid artery was examined in these children by means of ultrasonic imaging. The repair technique, which is described in detail, is seen as a relatively simple procedure that appears to reduce the chance of significant neurologic damage as a result of ECMO. (Consumer Summary produced by Reliance Medical Information, Inc.)

Surgery, Carotid artery, Carotid arteries

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Parenchymal and vascular magnetic resonance imaging of the brain after extracorporeal membrane oxygenation

Article Abstract:

Newborns with intractable respiratory failure may be treated with extracorporeal membrane oxygenation (ECMO), a procedure in which the venous blood is diverted outside the body to a machine that oxygenates the blood, and it is then returned to the body. It has been found that although most infants treated with ECMO suffer no adverse consequences of the treatment, some infants develop neurologic abnormalities including seizures, brain hemorrhage (bleeding), infarction (cessation of blood supply to an area of the brain) and brain atrophy (wasting). Advances in imaging now make it possible to study brain blood flow with magnetic resonance imaging (MRI) via a noninvasive angiographic technique. This technique may be used in conjunction with conventional brain imaging. A report is presented of use of this three-dimensional MRI angiography combined with conventional MRI to evaluate the parenchyma (functional tissue) and blood vessels of the brain in 30 patients who had survived ECMO. MRI findings were abnormal in 33 percent of patients. An abnormal MRI was found more often in babies who had neurologic abnormalities on examination at the time of hospital discharge. In all patients, magnetic resonance angiography showed good blood flow within the brain. The combination of MRI and MRI angiography permits better definition of the deep structures of the brain and the intracranial vasculature than do other neurologic imaging techniques. In combination, these two tests offer the possibility of providing a single, noninvasive approach for evaluating the intracranial blood flow as these children grow to adulthood. (Consumer Summary produced by Reliance Medical Information, Inc.)

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