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Biomedical subjects

R H Greenspan

Publications and source records attributed to R H Greenspan.

At least 19 recordsLinked to original sources
PubMed1992

Relation of plain chest radiographic findings to pulmonary arterial pressure and arterial blood oxygen levels in patients with acute pulmonary embolism.

Abnormalities of the plain chest radiograph of 123 patients with acute pulmonary embolism (PE) and no prior cardiac or pulmonary disease were related to the pulmonary arterial mean pressure, the partial pressure of oxygen in arterial blood, and the alveolar-arterial oxygen gradient. Patients with either a prominent central pulmonary artery or cardiomegaly had higher pulmonary arterial mean pressures than did patients with atelectasis, a pulmonary parenchymal abnormality or pleural effusion (p less than 0.001). These radiographic findings give clues to the severity of pulmonary hypertension in acute PE and suggest that pulmonary infarction or hemorrhage is associated with less severe PE.

Acute Disease↗
PubMed1992

Complications and validity of pulmonary angiography in acute pulmonary embolism.

BACKGROUND: The Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) addressed the value of ventilation/perfusion scans in acute pulmonary embolism (PE). The present study evaluates the risks and diagnostic validity of pulmonary angiography in 1,111 patients who underwent angiography in PIOPED: METHODS AND RESULTS: Complications were death in five (0.5%), major nonfatal complications in nine (1%), and less significant or minor in 60 (5%). More fatal or major nonfatal complications occurred in patients from the medical intensive care unit than elsewhere: five of 122 (4%) versus nine of 989 (1%) (p less than 0.02). Pulmonary artery pressure, volume of contrast material, and presence of PE did not significantly affect the frequency of complications. Renal dysfunction, either major (requiring dialysis) or less severe, occurred in 13 of 1,111 (1%). Patients who developed renal dysfunction after angiography were older than those who did not have renal dysfunction: 74 +/- 13 years versus 57 +/- 17 years (p less than 0.001). Angiograms were nondiagnostic in 35 of 1,111 (3%), and studies were incomplete in 12 of 1,111 (1%), usually because of a complication. Surveillance after negative angiograms showed PE in four of 675 (0.6%). Angiograms, interpreted on the basis of consensus readings, resulted in an unchallenged diagnosis in 96%. CONCLUSIONS: The risks of pulmonary angiography were sufficiently low to justify it as a diagnostic tool in the appropriate clinical setting. Clinical judgment is probably the most important consideration in the assessment of risk.

Acute Disease↗
PubMed1992

The diagnosis of acute pulmonary embolism in patients with chronic obstructive pulmonary disease.

The clinical features and noninvasive tests, including ventilation perfusion (V/Q) lung scans, were assessed in 108 patients with chronic obstructive pulmonary disease (COPD) suspected of having pulmonary embolism (PE). Twenty-one (19 percent) of 108 patients had PE. In the majority of patients, it was impossible to distinguish between patients with and without PE by clinical assessment alone. However, when a high clinical index of suspicion was present, PE was confirmed by angiography in three of three patients, but the V/Q scan was of intermediate probability. No roentgenographic abnormalities distinguished between PE and no PE. There was no difference between the alveolar-arterial oxygen gradients in either group, nor was there evidence of a reduction in the PaCO2 in patients with PE who had prior hypercapnia. Among the 108 patients with COPD, high, intermediate, low, and normal/near normal probability scans were present in 5 percent, 60 percent, 30 percent, and 5 percent, respectively. The frequency of PE in these V/Q scan categories was five (100 percent) of five, 14 (22 percent) of 65, two (6 percent) of 33, and zero (0 percent) of five, respectively. In conclusion, in the majority of patients, the V/Q scan diagnosis is usually intermediate and such patients require further investigational studies, including angiography. However, among the few patients who demonstrated a high probability lung scan, there was a high positive predictive value for PE effectively avoiding the need for further studies. In those patients with low probability or near normal/normal V/Q scans, the negative predictive value was not lower than the general hospital population.

Acute Disease↗
PubMed1988

Indium-111-oxinate labeled swine platelets and their survival in vivo.

Since the fibrinolytic system of the swine is close to that of human, the use of a swine model may assume increasing prominence in future studies of thrombosis. Swine platelets were labeled with 111In in a modified Tyrode's solution, suspended in plasma, then injected intravenously into swine. The average radioactivity incorporated into the platelets was 44 +/- 27%. The recovery of labeled platelets at 5 minutes post-injection was 81.7 +/- 5.3%. The platelets retained their label throughout their life span. The survival of 111In-platelets was described by a one component exponential equation, with a life span of 157.9 +/- 25.3 hrs.

Animals↗
PubMed1987

Radiographic differentiation between different etiologies of pulmonary edema.

We compared the plain chest radiographs of critically ill patients who had different types of pulmonary edema and evaluated the radiographs according to a standardized score sheet of findings. We included 94 total cases of pulmonary edema: 49 with cardiogenic, 33 with permeability, and 12 with renal/overhydration pulmonary edema. Patients with cardiogenic edema had enlarged hearts, vascular engorgement, septal lines, and absence of air bronchograms significantly more often than patients with permeability pulmonary edema. Renal/overhydration patients had enlarged hearts significantly more often than patients with permeability edema. There were no other statistically significant differences. Heart size and presence or absence of septal lines could have been used to distinguish cardiogenic and permeability edema in 83% of cases.

Capillary Permeability↗
PubMed1984

Preliminary observations on magnetic resonance imaging in refractory epilepsy.

We are studying the use of magnetic resonance (MR) imaging in localization of epileptogenic foci in patients with medically refractory partial epilepsy. Imaging is performed using a prototype resistive unit operating at 0.15 T. All studies include 7 mm axial sections obtained with a partial saturation sequence (TR = 200 msec) in which signals are recovered with a spin echo (TE = 11 msec) and images reconstructed using a modified 2D Fourier transform technique. Since the temporal lobe and limbic system are the commonest site of seizure foci in this group of patients, examinations were performed with the plane of section parallel to the temporal horns of the lateral ventricles. Consensus interpretations by a radiologist, neurologist and neurosurgeon have recognized findings considered possibly abnormal in six of 11 epilepsy patients and none of six normal volunteers. These preliminary results indicate that further study is warranted in this group of patients. Critical evaluation of such findings must be carried out in a larger group including normals and patients with a variety of neurologic disorders.

Adolescent↗
PubMed1983

Perfusion of nonventilated lung: failure of hypoxic vasoconstriction?

Alveolar hypoxia is a well established cause of regional vasoconstriction such that nonventilated segments are not perfused. The paradoxical situation of retained perfusion of nonventilated lung has seldom been discussed. Three clinical examples are illustrated. In each case coexistent chronic obstructive lung disease may have contributed to this unexpected finding by reducing pulmonary vascular capacity such that blood flow diversion from hypoxic segments was not possible.

Aged↗
PubMed1983

Optimal resources for examination of the heart and lungs: cardiac catheterization and radiographic facilities. Examination of the Chest and Cardiovascular System Study Group.

This is a revision of the 1976 report published under the auspices of the Inter-Society Commission for Heart Disease Resources. These guidelines provide a description of optimal resources, personnel, and working arrangements and should not be used to set minimal, standard, or uniform criteria or practices for all institutions. Included in the report are specifications for radiologic and physiologic equipment, description of case loads for maintaining safe and effective performance and considerations or complication rates. Also discussed are professional staff qualifications and relationships between physicians and technical and administrative services personnel. Other topics reviewed included laboratory location, electrical safety, and radiation protection as well as optimal facilities and equipment criteria for conventional x-rays. Newer imaging modalities are briefly considered, primarily to to emphasize that the field is rapidly changing. It is not possible, however to make specific recommendations concerning how these modalities will complement and/or replace more conventional techniques and approaches now considered appropriate and optimal.

American Heart Association↗
PubMed1982

Initial clinical evaluation of a whole body nuclear magnetic resonance (NMR) tomograph.

A nuclear magnetic resonance (NMR) imaging system is described, and preliminary results from its clinical use are presented. The properties and detection of the magnetisation due to hydrogen protons are outlined, and a rotating frame is introduced to describe the motion of the magnetisation. Radiofrequency (RF) pulses are used to rotate the magnetisation, and slice selection is achieved using a 90 degree RF pulse and a magnetic field gradient. Data acquisition and image reconstruction are explained. Three scanning sequences are described: repeated free induction decay (FID), inversion - recovery, and spin-echo. These sequences produce images whose pixel values have different dependencies on hydrogen proton density, T1 and T2. Inversion-recovery images show striking differentiation between grey and white matter in the brain. The absence of bone artifact is a significant advantage over X-ray computed tomography in the posterior fossa, where rapid repeated FID sequences can also be used to demonstrate flow effects. The considerable soft tissue contrast available with NMR is of value in demonstrating disease within the liver where T1 appears to be sensitive but relatively nonspecific diagnostic parameter. High resolution scans are of value in demonstrating the adrenal gland and spinal cord.

Brain↗
PubMed1982

The efficacy of full-lung tomography in the detection of early metastatic disease from melanoma.

In a prospective study, 62 patients with proved melanoma and negative chest radiographs underwent full-lung tomography. Of 109 examinations performed, 12 patients had positive findings on tomography; nine were false-positive and three were true-positive. Of the true-positive examinations, two patients already had widespread metastatic disease and one had an advanced local lesion. Clinical staging and therapy were changed in only one patient as a result of information provided by full-lung tomography. It appears from these results that full-lung tomography is of limited use in detection of metastases from melanoma in the presence of a negative chest radiograph.

Adult↗
PubMed1981

Magnetic resonance properties of hydrogen: imaging the posterior fossa.

Posterior fossa scans were performed on five healthy volunteers using a nuclear magnetic resonance (NMR) machine constructed by Thorn-EMI Ltd. Three different NMR scanning sequences were used. In the first, a type of saturation-recovery technique was used to produce images strongly dependent on the density of hydrogen nuclei, but with some dependence on the spin-lattice relaxation time (T1). In the second, an inversion-recovery technique was used to produce images with a stronger dependence on the spin-lattice relaxation time. In the third, a spin-echo technique was used to obtain images with a dependence on the spin-spin relaxation time (T2). All three types of NMR image were unaffected by bone artifact. Visualization of brain adjacent to the skull base was obtained without loss of detail due to partial-volume effect from bone. The saturation-recovery images highlighted arteries and veins that were clearly visible without the use of contrast agents. The inversion-recovery images showed remarkable gray-white matter differentiation enabling internal structure to be seen within the brainstem and cerebellum. The trigeminal nerve and ganglion were also seen outside the brain. Experience with the spin-echo technique is limited, but the images at the base of the brain show considerable soft-tissue detail. The NMR images of the posterior fossa in this study were comparable in quality to those obtained from a new rotate-rotate x-ray computed tomography machine and were superior in several respects.

Adult↗
PubMed1980

Detection of metastatic disease from carcinoma of the breast: limited value of full lung tomography.

Until now no large prospective study has been made to evaluate the efficacy of full lung tomography in detection of pulmonary metastases from carcinoma of the breast in the presence of a negative chest radiograph. In the current study, 144 patients with proven breast carcinoma and a negative chest radiograph underwent full lung tomography. Nodules were demonstrated in three patients and, in two of them, presumably reflected metastatic disease. Both patients had advanced extrapulmonary metastatic disease at the time of full lung tomography and in neither case did a change in therapy result. One presumed false-positive observation was also made. Because of the low propensity for carcinoma of the breast to metastasize to the lungs, full chest tomography does not appear warranted as a screening procedure in these patients.

Adult↗
PubMed1980

Thoracic manifestations of liver disease.

The close proximity of the liver to the right lung may be the basis for thoracic changes that occur in the presence of lung disease, or such changes may occur as part of the natural course of the disease. Whatever the etiology, the selective use of plain film radiography, fluoroscopy, radionuclide scanning, gallium scanning, and computed tomography will facilitate diagnosis and management.

Amebiasis↗
PubMed1978

Chest pain in the nontraumatized patient.

The radiologist plays an important role in the examination of nontraumatized patients with chest pain presenting in the emergency room. In some instances, a diagnosis can be made on the basis of the initial radiograph. In others, consultation with the referring physician may either make the diagnosis or indicate a need for additional view or other imaging procedures. In this discussion, medical conditions associated with various radiographic appearances of the chest have been considered. We have not attempted to be encyclopedic, but have confined ourselves to the more common or distinctiive radiographic findings. Obviously, chest pain can occur from many other causes including primary disease in the neck, abdomen, and skeletal system.

Cardiomegaly↗
PubMed1977

Detection of metastatic malignant melanoma by chest roentgenography.

The latest premortem chest roentgenogram on 17 patients with known metastatic malignant melanoma was examined and the results were compared with the findings in the chest at autopsy. In nine of the 17, disease not visible on the roentgenogram was found at autopsy. Preliminary data would indicate that a significant number of these metastases could have been identified premortem by other radiographic modalities, e.g., tomography.

Adult↗