Real-time sonography of fetal cardiac anatomy.
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Echocardiography↗
Biomedical subjects
L Axel
Publications and source records attributed to L Axel.
NMR imaging of the chest at 0.12 T: initial clinical experience with a resistive magnet.
The chests of 40 subjects were imaged with an experimental nuclear magnetic resonance (NMR) imager operating at a magnetic field of 0.12 T. There were six normal volunteers and 34 patients with abnormalities affecting different areas, including the chest wall, pleura, hila, mediastinum, and lung parenchyma, and including benign and malignant processes. In this initial clinical experience, NMR imaging provided useful information on the presence and extent of disease by its ability to distinguish different tissues and by the excellent demonstration of vascular structures.
Humans↗
NMR imaging of the abdomen at 0.12 T: initial clinical experience with a resistive magnet.
Forty-five patients with a variety of abdominal abnormalities and five normal volunteers were imaged on a 0.12 T resistive nuclear magnetic resonance system. Scans were obtained with saturation-recovery technique and short repetition times. The images reflected both proton density and T1 information. A variety of neoplastic and nonneoplastic disease processes involving the abdomen were imaged. Results suggest that clinically useful images clearly may be obtained at 0.12 T. In addition, saturation-recovery imaging with short repetition rates can detect a wide range of abdominal abnormalities.
Abdomen↗
Standard nomenclature for NMR.
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Magnetic Resonance Spectroscopy↗
Computed tomographic detection of retroperitoneal adenopathy.
This prospective study of 50 patients was designed to evaluate the effect of computed tomographic section spacing on the detection of retroperitoneal adenopathy. Contiguous 1-cm-thick sections were obtained in all patients and compared with scans obtained at 2-cm intervals in these same patients. In 45 of the 50 patients, there was agreement between the two sets of scans; in only two of the 50 cases were there major disagreements. These results suggest that scans obtained at 2-cm intervals are nearly as accurate as contiguous scans at 1-cm intervals in the detection of retroperitoneal adenopathy.
Humans↗
CT diagnosis of mediastinal thyroid.
Computed tomography (CT) is capable of specifically diagnosing mediastinal thyroid as the cause of a mediastinal mass. Five representative cases illustrate characteristic features of substernal thyroid. These include: (1) anatomic continuity with the cervical thyroid; (2) focal calcifications; (3) relatively high CT number; (4) rise in CT number after bolus administration of iodinated urographic contrast material; and (5) prolonged enhancement after contrast administration. While not all of these features are present in each case, a combination of these should permit accurate diagnosis in most cases.
Aged↗
Dynamic CT of hepatic masses with intravenous and intraarterial contrast material.
Seven patients with primary and metastatic hepatic tumors had dynamic computed tomographic scans obtained after an intravenous and an intrahepatic arterial bolus of contrast media. Four patients had hepatoma and three had hepatic metastasis from either a colonic, pancreatic, or leiomyosarcoma primary malignancy. Computed tomography was also performed after an intravenous drip infusion of contrast material. Time-density curves of the hepatic lesions after contrast administration were analyzed and compared. The results demonstrated that: (1) intrahepatic arterial delivery of contrast fluid resulted in the greatest contrast enhancement of lesions and detected more lesions than the intravenous bolus technique, which was superior to the drip infusion technique; (2) no consistent difference in the pattern of contrast enhancement was found between various hepatic lesions; (3) within multiple lesions of similar pathology in any one liver, a spectrum of contrast enhancement pattern was found; and (4) changes in contrast enhancement occurred rapidly and lesions changed from hypodense to isodense to hyperdense to isodense within 30--45 sec.
Carcinoma, Hepatocellular↗
Colonic "urticaria' pattern due to early ischemia.
The unusual radiographic pattern of bleblike mounds on the surface of the colon mucosa, previously described as colonic urticaria, was seen in 3 patients in whom no allergic state was present. This urticaria-like pattern was due to colonic distention in all 3, and represented only submucosal edema on the gross and microscopic specimens. We hypothesize that this pattern is due to early changes of ischemia caused by colon distention.
Adult↗
Dynamic computed tomography demonstration of hepatic arteriovenous fistula.
A traumatic hepatic arteriovenous fistula was located by dynamic computed tomography, and its flow characteristics were demonstrated by analysis of the scan sequence with curve fitting and functional imaging programs.
Aorta, Abdominal↗
Technical aspects and clinical applications of CT/X, a dynamic CT scanner.
CT/X is an X-ray computed tomographic scanner system designed for research in the clinical applications of rapid sequence scanning. The minimum scan time is 1.5 sec, and up to 18 images of the same cross section can be derived from scans taken over a 30 sec time interval. With this high image rate, the transit of a bolus of iodinated contrast medium can be followed through any cross section of the body. Rapid sequence scanning through a series of contiguous levels can also be performed, and 12 levels can be scanned in less than 50 sec. The short aggregate scan period minimizes the likelihood of interslice patient motion resulting in high quality multiplanar images. To fully exploit this capability, an imaging facility capable of reformatting axial transverse display data into a plane of arbitrary orientation has been incorporated into the system. A computer-electrocardiographic interface is also provided for use in retrospective cardiac gating. The capabilities of the scanner are illustrated with selective clinical studies.
Angiography↗
Functional imaging of the brain using computed tomography.
Data from rapid-sequence CT scans of the same cross section, obtained following bolus injection of contrast material, were analyzed by functional imaging. The information contained in a large number of images can be compressed into one or two gray-scale images which can be evaluated both qualitatively and quantitatively. The computational techniques are described and applied to the generation of images depicting bolus transit time, arrival time, peak time, and effective width.
Brain↗
Computed tomography: a new method for diagnosing tumor of the heart.
An unsuspected metastasis of liposarcoma of the heart was detected on a computed tomographic (CT) examination of the chest. Further CT study with i.v. contrast administration gave excellent delineation of the tumor. Compared with two-dimensional echocardiography and angiocardiography, CT was best at showing the myocardial and intrapericardial extension of the tumor, but did not show movement of the tumor during the cardiac cycle. CT is a useful noninvasive method for evaluating cardiac metastasis. Its advantages and disadvantages with respect to echocardiography and angiocardiography are discussed.
Angiocardiography↗
Dynamic computed tomography of the brain: techniques, data analysis, and applications.
Rapid sequence computed tomography (CT) scanning has many potential applications in studying intracranial physiologic events. However, visual inspection of these rapid sequence scans fails to extract the large amount of information inherent in the digital data. The concept of corrected mean transit time applied to rapid sequence scans after intravenous bolus injection of contrast material provides quantitative data on relative hemispheric flow. Use of histogram-based areas of interest permits accurate and reproducible identification of anatomic structures including arteries and gray and white matter. Gamma variate curve fit techniques reduce statistical noise. The concept of transit time can be expanded to the creation of functional CT images.
Blood Flow Velocity↗
Dynamic CT of the normal spleen.
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Adult↗
A method of calculating brain blood flow with a CT dynamic scanner.
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Arteries↗
The desirable properties of computed tomography scanners.
The purchase of a CT scanner is a costly venture. Given the number of companies in the field and the tremendous financial involved, certain guidelines must be considered: (a) reputation and longevity of the firm; (b) merits of the machine; and (c) possibility of updating technologically. The authors discuss the most desirable properties of the scanners and list advanced features which manufacturers should be able to supply in the near future.
Tomography, X-Ray Computed↗
Difference between liver and spleen CT numbers in the normal adult: its usefulness in predicting the presence of diffuse liver disease.
A constant relationship was found between the mean CT numbers of the liver and spleen in 100 normal adults. This relationship was characterized by a mean CT number consistently higher for the liver (24.9 +/- 4.6) than for the spleen (21.1 +/- 4.1). The range for liver CT numbers was 16.7-37.2, and for the spleen it was 14.9-34.3. The mean liver-spleen CT number difference for all subjects was 3.8 +/- 2.1 (p < 0.001); in every instance, the livers exhibiting the high mean CT numbers were in subjects with high mean spleen CT numbers, with the same concordance for low mean CT numbers. This relationship between liver and spleen may be useful in the clinical setting in which a normal liver with low CT numbers must be differentiated from one in which the CT number is low because of fatty infiltration; the fatty liver will exhibit a lower mean CT number than the spleen.
Adult↗
Cerebral blood flow determination by rapid-sequence computed tomography: theoretical analysis.
Dynamic computed tomography (CT) using rapid-sequence scanning can be used to determine cerebral blood flow noninvasively following an intravenous bolus injection of contrast material. Since the contrast material remains intravascular in the normal brain, principles of indicator dilution analysis for nondiffusible indicators are applied to the time course of the changes in contrast concentration. While a delay is introduced by the relatively prolonged intravenous injection, this can be corrected for if the arteries are seen on the scan; the corrected mean transit time of the first passage of the bolus through the vessels gives the blood flow per unit vascular volume. To find the blood flow per unit of total tissue volume requires measuring the concentration of contrast material in the blood, which cannot always be done directly from brain scans with current CT equipment; however, a relative volume for total tissue flow can be found by using the area under the curve of contrast concentration as a function of time, as this area is proportional to the fractional vascular volume of the tissue.
Cerebrovascular Circulation↗