The high-resolution computed tomography technique.
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Algorithms↗
Biomedical subjects
J R Mayo
Publications and source records attributed to J R Mayo.
Low-dose high-resolution CT of lung parenchyma.
To evaluate the efficacy of low-dose high-resolution computed tomography (HRCT) in the assessment of lung parenchyma, three observers reviewed the scans of 31 patients. The 1.5-mm-collimation, 2-second, 120-kVp scans were obtained at 20 and 200 mA at selected identical levels in the chest. The observers evaluated the visualization of normal pulmonary anatomy, various parenchymal abnormalities and their distribution, and artifacts. The low-dose and conventional scans were equivalent in the evaluation of vessels, lobar and segmental bronchi, and anatomy of secondary pulmonary lobules, and in characterizing the extent and distribution of reticulation, honeycomb cysts, and thickened interlobular septa. The low-dose technique failed to demonstrate ground-glass opacity in two of 10 cases (20%) and emphysema in one of nine cases (11%), in which they were evident but subtle on the high-dose scans. These differences were not statistically significant. Linear streak artifact was more prominent on images acquired with the low-dose technique, but the two techniques were judged equally diagnostic in 97% of cases. The authors conclude that HRCT images acquired at 20 mA yield anatomic information equivalent to that obtained with 200-mA scans in the majority of patients, without significant loss of spatial resolution or image degradation due to linear streak artifact.
Adult↗
High resolution computed tomography. Technical aspects.
High resolution computed tomography (CT) may be defined as thin section (1-2 mm collimation) CT optimized by using a high-spatial-frequency (bone) algorithm. Further improvement of the image may be obtained by targeting the scan to a small field of view. This article reviews the technical aspects that influence the quality of the CT image as well as some of the scanning protocols used in the assessment of patients who have diffuse lung disease.
Humans↗
Imaging of diffuse lung diseases. Past, present, and future.
For many years the plain chest radiograph was the only imaging modality used in the assessment of patients who had diffuse lung disease. Presently, high resolution computed tomography (CT) and lung scintigraphy play a major role in the assessment of these patients. Use of magnetic resonance (MR) imaging in the assessment of the lung parenchyma has been limited by poor signal-to-noise ratio and physiologic motion. Recent improvements in technique, however, have allowed assessment of patients with diffuse lung disease. It is likely that MR imaging will play an increasing role in the assessment of these patients in the near future.
Humans↗
Coronary angioplasty after coronary bypass surgery: initial results and late outcome in 422 patients.
From 1978 to 1988, coronary angioplasty was performed in 422 patients with prior coronary artery bypass surgery (264 patients with native coronary artery angioplasty and 158 patients with graft angioplasty). Angioplasty was successful in 84%, unsuccessful but uncomplicated in 11% and complicated by one or more major cardiac events in 5% (myocardial infarction 5%, emergency bypass surgery 2% and death 0.2%). Follow-up data were obtained in 99% of 356 patients with successful angioplasty. At a mean of 33 +/- 26 months, 92% were alive, 73% had improvement in angina and 61% were free of angina. One or more of the following late events occurred in 67 patients (19%): myocardial infarction (6%), elective reoperation (13%) and cardiac death (6%). Repeat angioplasty was performed in 27%, with a success rate of 89% and no deaths. Initial success rates were equal in native vessel versus graft angioplasty, but late outcome was less favorable with the latter because of a higher rate of infarction (11% versus 4%, p less than 0.05) and need for reoperation (19% versus 10%, p less than 0.05). The initial success rate was higher in vein grafts less than 1 year old compared with grafts 1 to 4 years or greater than 4 years after operation (92% versus 85% versus 83%, respectively) and adverse late events were less frequent after angioplasty in recent vein grafts (less than 1 year 13%, 1 to 4 years 35%, greater than 4 years 29%; less than 1 versus greater than 1 year, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Angina Pectoris↗
Computed tomography of cardiac and pericardial tumors.
Computed tomography (CT) scans in 30 patients with neoplastic involvement of the heart and pericardium were retrospectively reviewed. Computed tomography was compared with echocardiography in three of four patients with large primary cardiac tumors and in three patients with metastatic pericardial disease. Computed tomography was superior to echocardiography in determining tumor extent and site of origin of a right atrial sarcoma, as well as in assessing tumor extent and presence of pulmonary arterial hypertension in a left atrial malignant fibrous histiocytoma and a left atrial myxoma. Pericardial effusions were detected by echocardiography in two out of three patients with metastatic pericardial disease, but the malignant nature of the effusion was not recognized; in all three cases CT showed nodular pericardial thickening. Of the 23 patients with evidence on CT of direct extension of anterior mediastinal masses, bronchogenic carcinoma or mesothelioma to the pericardium 21 had nodular pericardial thickening and 2 diffuse thickening; only 6 had pericardial effusion. We conclude that CT is useful in the characterization of large primary cardiac tumors that are incompletely visualized with echocardiography. Computed tomography is superior to echocardiography in assessing tumor involvement of the pericardium because pericardial effusions are often absent; CT is also superior in identifying nodular pericardial thickening.
Adult↗
Magnetic resonance imaging of hydrostatic pulmonary edema in isolated dog lungs: comparison with computed tomography.
Magnetic resonance imaging (MRI) is considered inferior to computed tomography (CT) in the assessment of lung parenchyma, being hampered by low proton density, magnetic susceptibility effects, flow, and cardiac and respiratory motion. In this study the authors assessed the potential usefulness of MRI by comparing it with corresponding CT images of the lung in the absence of motion. They studied eight excised normal canine lung lobes inflated with oxygen before and after induction of pulmonary edema produced by intravascular infusion of saline at 30 cm H2O. T1, T2 and proton density weighted, 5-mm thick, gapped, multislice sequences were performed at 1.5 T. Magnetic resonance images were compared with corresponding 5-mm collimation CT scans at identical levels both before and after the induction of pulmonary edema. The MR and CT scans were assessed independently by two chest radiologists. In normal lung, there was equivalent visualization of vessels down to 1 mm and bronchi to 2 mm in diameter. T1 and proton density scans demonstrated lower spatial resolution but greater contrast than the corresponding CT images. In pulmonary edema both T1 and proton density sequences demonstrated peribronchial edema with greater contrast than CT. Air-space filling was equally well demonstrated by either technique. The authors conclude that, in motionless lung, MRI has lower spatial but greater contrast resolution than CT. It is potentially superior to CT in assessing focal and diffuse lung disease if cardiac and respiratory motion artifacts can be minimized or suppressed.
Animals↗
Angioplasty of unusually large coronary arteries using the hugging balloon technique via a single guiding catheter.
Unusually large native coronary arteries, in particular those supplying expansive regions of myocardium, may not be adequately dilated using currently available coronary angioplasty catheters. The "hugging balloon" technique, in which two dilatation catheter balloons are simultaneously inflated side-by-side, has been previously described for lesions in large saphenous vein grafts using the double guiding catheter (and dual entry site) technique. With the development of large lumen guiding catheters and lower profile dilatation catheters, we report the initial use of the hugging balloon technique via a single guiding catheter in oversized native coronary arteries.
Angiography↗
Complex coronary angioplasty: use of a new microprobe balloon catheter.
Since the introduction of coronary angioplasty by Gruntzig et al. (Circulation [Suppl II] 56:84, 1977), a key determinant to overall success has been advancement in equipment technology. Major advances have been made in the availability of low-profile catheters in the last 5 years that have facilitated penetration of high-grade distal and complex lesions. The USCl probe TM catheter is an example of a low-profile catheter that has shown favorable applicability in dilating high-grade stenoses. Preliminary data indicate that this device has good trackability and an extremely low profile, which allows penetration of stenoses where other current low-profile catheters have failed.
Angina Pectoris↗
Chronic diffuse infiltrative lung disease: comparison of diagnostic accuracy of CT and chest radiography.
The accuracies of chest radiography and computed tomography (CT) in the prediction of specific diagnoses in 118 consecutive patients with chronic diffuse infiltrative lung disease (DILD) were compared. The radiographs and CT scans were independently assessed by three observers without knowledge of clinical or pathologic data. The observers listed the three most likely diagnoses in order of probability and recorded the degree of confidence they felt in their first-choice diagnosis on a three-point scale. Confidence level 1 (definite) was reached with 23% of radiographic and 49% of CT scan readings, and the correct diagnosis was made with 77% and 93% of those readings, respectively (P less than .001). The correct first-choice diagnosis regardless of the level of confidence was made with 57% of radiographic and 76% of CT scan readings (P less than .001). The CT scan interpretations were most accurate in silicosis (93%), usual interstitial pneumonia (89%), lymphangitic carcinomatosis (85%), and sarcoidosis (77%). Observers correctly predicted whether a transbronchial or open lung biopsy was indicated with 65% of radiographs and 87% of CT scans (P less than .001). It is recommended that CT be performed before lung biopsy in all patients with chronic DILD.
Adult↗
Blood MR signal suppression by preexcitation with inverting pulses.
A cardiac-gated sequence has been developed for functional cardiac imaging. It uses a nonselective 180 degrees preinverting pulse before a spin-echo (SE) readout sequence with an echo time (TE) of 28 msec. In seven healthy volunteers this sequence provided superior wall-to-chamber contrast in end diastole and end systole when compared with the following sequences: SE, TE = 28 msec; SE, TE = 28 msec with dephasing gradients; and SE, TE = 28 msec with presaturation bands.
Adult↗
Chronic eosinophilic pneumonia: CT findings in six cases.
We reviewed the chest radiographs and CT scans in six patients with proved chronic eosinophilic pneumonia. In all patients, the chest radiographs showed patchy air-space consolidation, and in five of six cases, the consolidation was most marked in the middle and upper lung zones. In only one patient was the classic pattern of air-space consolidation that is confined to the outer third of the lungs readily apparent. In three patients, the consolidation appeared to be diffuse, although a slight peripheral predominance was present. In two patients, a peripheral predominance was difficult to appreciate, even in retrospect. The CT scans in all cases showed peripheral air-space consolidation. In addition, mediastinal adenopathy was identified on CT scans in three cases. This has not been described before in association with chronic eosinophilic pneumonia. A follow-up CT scan in one patient showed resolution of the adenopathy and marked improvement in the peripheral air-space disease within 2 weeks. We conclude that patients with chronic eosinophilic pneumonia show predominantly peripheral air-space consolidation on CT scans, even when this distribution is not readily apparent on the radiograph. CT may be helpful in the diagnosis when the clinical findings are suggestive, but the radiographic pattern is nonspecific.
Adult↗
High-resolution CT of the lungs: an optimal approach.
The influences of kilovolt peak, milliamperage, reconstruction algorithm, targeting, and image magnification on thin-section (1.5-mm) computed tomography (CT) of the lung were studied in phantoms and patients. Retrospective targeted reconstruction (25-cm field of view) improved spatial resolution, while magnification did not. The bone reconstruction algorithm improved spatial resolution, compared with the standard algorithm, and in patients, bone algorithm images were considered superior to standard reconstructions. Although using the bone algorithm increases the visible image noise, increasing the kilovolt peak and the milliamperage can reduce this noise. However, in the patients studied, this reduction in noise was not usually judged as significant, except in the posterior, paravertebral part of the lung. An optimal technique for CT of the lung parenchyma should include thin-collimation, targeted scans reconstructed with a high-spatial-frequency algorithm and, in some patients, increased kilovolt peak or milliamperage.
Bone and Bones↗
The double-fissure sign: a motion artifact on thin-section CT scans.
A motion artifact has been observed that may affect the number of fine interstitial lines seen at thin-section (1.5-mm-collimation) computed tomography (CT) for the evaluation of interstitial lung disease. In 14 of 42 patients, one or both major fissures appeared as two parallel lines rather than as a single line. This was more common in the left lung base. Using a phantom, the authors were able to reproduce the phenomenon by simulating cardiac motion. Therefore, this motion may lead to an artifactual increase in the number of interstitial lines.
Humans↗
Assessment of multiple sclerosis lesions by magnetic resonance imaging.
Fifty patients clinically suspected to have multiple sclerosis (MS), who were classified by Schumacher's criteria into three clinical categories (definite, probable, or possible MS), underwent complete brain magnetic resonance (MR) scans. The T2-weighted spin echo (SE) pulse sequence was more sensitive than inversion recovery (IR) in detecting MS lesions. Greater than 50% of the lesions demonstrated by SE were missed on the corresponding IR slices. However, lesions in the brainstem were more readily assessed using IR. MS lesions appeared larger on SE than on IR. Fifty-five percent of SE-demonstrated lesions were 1 to 2 cm or larger in size, while only 32% of IR-demonstrated lesions were greater than 1 cm. Axial and coronal planes of study demonstrated the same number, size, and location of lesions.
Adult↗
Stereoselective inhibition of prostaglandin-induced calcium release from platelet membranes by trimetoquinol.
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15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
Elevated alpha-fetoprotein levels in the 45,x (Turner syndrome) fetus with cystic hygroma. Case reports.
A 45,X fetus with cystic hygroma, associated with an elevated amniotic alpha-fetoprotein (AFP) level (greater than 80 microgram/ml). Is described, as are macroscopic and microscopic characteristics of this fetus and two other female fetuses with cystic hygroma. The ultrasonographic diagnosis of fetal cystic hygroma is discussed. The association of a high amniotic AFP level with cystic hygroma is considered. The relationship between cystic hygroma and pterygium colli in liveborn infants with Turner syndrome, and the evolution of neck webbing, as seen in the adult with turner syndrome, is also discussed.
Adult↗
Evidence for the nonenzymatic and irreversible binding of cytembena to rat liver microsomes in vitro.
Characteristics of the irreversible binding of cytembena (CYT) to rat liver microsomal proteins have been investigated in vitro. Binding of [14C]CYT to rat liver microsomal proteins remained unchanged in the presence of SKF-525A or after heat denaturation and was not dependent upon the presence of pyridine nucleotide (NADPH or NADH). Ethacrynic acid, cysteine, dithiothreitol, and lysine were found to block the irreversible binding of [14C]CYT to microsomal proteins in a dose-dependent manner. The rank order of effectiveness as inhibitors of CYT binding was ethacrynic acid greater than cysteine greater than dithiothreitol greater than lysine. In other studies, CYT was shown to preferentially form adducts with cysteine rather than lysine or glycine. Using structural analogs and metabolites of CYT, it was found that 4-methoxybenzoylacrylic acid and beta-benzoylacrylic acid were effective competitors of [14C]CYT binding to liver microsomal proteins. By contrast, 4-methoxybenzoylpropionic acid, 5-(4-methoxyphenyl)dihydro-2(3H)furanone and 4-hydroxy-4-(4-methoxyphenyl)butyric acid were ineffective as inhibitors of the irreversible binding of CYT. These data suggest that sulfhydryl groups are involved in the nonenzymatic binding of CYT and that the presence of a carbon-carbon double bond in CYT, in debrominated metabolites or structural analogs, is requisite for an interference of the binding of CYT to microsomal proteins.
Acrylates↗