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J R Mayo

Publications and source records attributed to J R Mayo.

At least 19 recordsLinked to original sources
PubMed1992

High-resolution computed tomography of experimental hydrostatic pulmonary edema.

To better understand the distribution and clearance mechanisms of extravascular lung water (EVLW) in pulmonary edema, computed tomographic (CT) scans of isolated canine lungs were obtained. In this model, there is no active lymphatic drainage. Fourteen isolated lobes were inflated with oxygen, and edema was induced by infusion of normal saline solution. Two volumes of saline were used, 50 percent and 150 percent of initial wet lobar weight. Six 10-mm- and 1.5-mm-collimation CT scans were obtained at 10-mm intervals from the hilum to the periphery of the lobe before and after each of the two stages of pulmonary edema. The CT scans were reviewed independently by two chest radiologists and were assessed by CT densitometry. Both subjective analysis and CT densitometry showed a predominantly central peribronchial distribution of EVLW in the isolated lungs. Airway wall thickness also increased from the control value (average thickness, 1.0 mm) to 150 percent edema (average thickness, 1.5 mm) (p less than 0.001). We postulate that the peribronchial distribution of fluid is due to a pressure gradient from the alveolar interstitium to the interstitium around the blood vessels and airways at the hilum. This gradient may play a major role in the characteristic perihilar and peribronchial distribution of EVLW seen radiologically in patients with hydrostatic pulmonary edema.

Animals↗
PubMed1992

Tuberculosis of the thymus.

Tuberculosis is increasing in prevalence in North America, mainly due to HIV infection. We describe an unusual case of TB of the thymus in a HIV sero-negative Filipino immigrant who preoperatively was thought to have a thymoma. We describe the clinical, radiologic and pathologic findings and review the literature on TB of the thymus.

Adult↗
PubMed1992

Value of MR imaging in the evaluation of chronic infiltrative lung diseases: comparison with CT.

The value of MR imaging was compared with that of high-resolution CT in assessing chronic infiltrative lung disease in 25 patients. The cases included nine patients with usual interstitial pneumonia, six with sarcoidosis, four with hypersensitivity pneumonitis, and six with miscellaneous conditions. The diagnosis was proved by biopsy (n = 17) or by means of clinical, laboratory, and radiologic criteria (n = 8). All patients had 1.5-T MR imaging and CT of the chest. Cardiac-gated T1-, proton density-, and T2-weighted spin-echo sequences were obtained. Initially, the MR images were assessed independently; later they were compared directly with the corresponding CT scans. In six patients, MR images and CT scans were obtained before open lung biopsy, and the images and scans were assessed prospectively. CT was superior to MR imaging in the anatomic assessment of the lung parenchyma and in showing fibrosis. However, areas of air-space opacification (ground-glass opacities) were seen as well on MR as on high-resolution CT. In the six patients who had open lung biopsy, areas of air-space opacification seen on MR and on CT corresponded to areas of active alveolitis or air-space infiltrates pathologically. Follow-up in six patients showed equal degrees of change in the air-space opacification over time on MR and CT. We conclude that, although MR imaging is inferior to high-resolution CT in the assessment of chronic infiltrative lung diseases, it may play a role in the assessment and follow-up of patients with air-space opacification.

Adult↗
PubMed1992

MR imaging of the lungs: value of short TE spin-echo pulse sequences.

OBJECTIVE: An experimental short echo delay (TE = 7 msec) T1-weighted spin-echo sequence was compared with a conventional (TE = 20 msec) T1-weighted spin-echo sequence in the assessment of normal and abnormal lung parenchyma. Comparison was also made with high-resolution CT of abnormal lung parenchyma. SUBJECTS AND METHOD: At 1.5 T, an experimental short echo delay T1-weighted multislice spin-echo sequence (TR = RR interval, TE = 7 msec) was compared with an optimal conventional T1-weighted spin-echo sequence (TR = RR interval, TE = 20 msec, spatial presaturation). Ten healthy volunteers were examined with both sequences. The mean signal intensity and signal-to-noise ratios were calculated in lung parenchyma for both sequences. Two radiologists compared the visualization of normal lung parenchymal structures with the two techniques. In 24 patients with diffuse lung disease, results with both MR sequences and with high-resolution CT were compared. RESULTS: The signal intensity was significantly greater (p < .001) with the TE of 7 msec than with the TE of 20 msec, resulting in a 3.5-fold improvement in the signal-to-noise ratio. The 7-msec TE improved visualization of lung parenchymal structures, including peripheral vessels, interlobular septa or veins, and centrilobular arteries. In the patients with diffuse lung disease, pulmonary parenchymal abnormalities were better visualized on the images with TEs of 7 msec than on images with TEs of 20 msec. When compared with high-resolution CT, the sequence with a TE of 7 msec provided comparable assessment of air-space opacification and dense consolidation, but it was inferior to high-resolution CT in the anatomic assessment of lung parenchyma. CONCLUSION: This experimental spin-echo sequence with a TE of 7 msec significantly improves the signal-to-noise ratio, allowing improved visualization of normal and abnormal pulmonary parenchyma when compared with conventional spin-echo images with a TE of 20 msec. Although anatomic detail remains inferior to that seen with high-resolution CT, the improved image quality with a TE of 7 msec suggests that assessment and follow-up of parenchymal lung disease might be possible with MR, thereby avoiding ionizing radiation.

Adult↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1990

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↗
PubMed1990

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↗
PubMed1990

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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1987

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↗
PubMed1987

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↗