Edward E. Christensen

The Relative Accuracy of Echocardiography, Intravenous CO2 Studies, and Blood-Pool Scanning in Detecting Pericardial Effusions in Dogs!

This study was an attempt to determine the relative accuracy of echocardiography, intravenous carbon dioxide, and blood-pool scanning in detecting pericardial effusions. Since we usually do not know how much fluid is present in the pericardial sac of humans with effusions and the volume cannot be easily changed, dogs were used in this investigation so that the size of the effusion could be accurately controlled. Materials and Methods The 25 mongrel dogs examined were of either sex and ranged in size from 10 to 23 kg. They were anesthetized with sodium pentobarbital, and catheters were placed in the pericardial sac percutaneously by the method described by Christensen et al. (3). For acute effusions, 6 per cent isosmotic dextran was used. It stayed in the pericardial space fairly well and did not draw in any additional fluid. To test for leakage around the catheter, 75 ml of dextran was injected into the pericardial sac of smaller dogs, 100 ml with larger dogs. The fluid was then removed, and, if all of it...

The effect of fatigue on resident performance.

Fourteen rested and fatigued residents read a set of 25 test radiographs on two separate occasions approximately one month apart. The radiographs were made with partial chest phantom using pulmonary nodules as test objects. Seven rested and 7 fatigued residents read the radiographs, and a month later the order of fatigue was reversed. Fatigued residents had worked a minimum of 15 consecutive hours before their interpretations. Performance did not deteriorate with fatigue, and the nodule detection rate was almost identical on both occasions.

Normal “Cupid's Bow” Contour of the Lower Lumbar Vertebrae

The inferior end plates of the 3d, 4th, and 5th lumbar vertebral bodies frequently have paired parasagittal concavities when viewed in the frontal projection. When viewed in the lateral projection, the concavities superimpose, lying in the posterior portion of the vertebral body. This normal contour of the end plate should not be confused with other vertebral body anomalies having clinical importance. The incidence and degree of end plate depression are discussed.

Radiographic techniques for balloon-occlusion pulmonary angiography.

Pulmonary angiography was performed in 125 patients with suspected pulmonary embolism. Standard angiographic techniques were combined with balloon occlusion of pulmonary arterial branches using a double lumen catheter and contrast material injection distal to the occlusion. Vessel opacification was fluoroscopically monitored and images obtained with either a conventional cut-film camera, a spot-film camera, or cineangiography. Balloon-occlusion angiography improved image quality and contributed substantially to the radiographic diagnosis of pulmonary embolism in most patients. The technique is useful in patients too ill to undergo conventional angiography and may be performed at the bedside.

Subpulmonic Pneumothorax in Patients with Chronic Obstructive Pulmonary Disease

A spontaneous pneumothorax is occasionally seen under the lung on upright views, apparently due to subpulmonic trapping of pleural air by adhesions. This is most likely to occur in patients with chronic obstructive pulmonary disease (COPD), especially if they have extensive parenchymal scarring from previous tuberculosis. The authors describe 4 patients who had subpulmonic pneumothorax, severe COPD, and parenchymal scarring and presented in respiratory failure. None had other clinical symptoms suggesting pneumothorax. Radiologists should be aware of this condition, since it is potentially lethal.

RADIONUCLIDE CORONARY ANGIOGRAPHY AND MYOCARDIAL BLOOD FLOW.

Abstract Regional myocardial blood flow in dogs was studied with a scintillation camera and two different data recording and processing systems: (a) videotape storage and a video scintillation counter, and (b) magnetic tape storage and a small computer system designed to operate with a scintillation camera. A tracer bolus of technetium serum albumin, pertechnetate ion, or xenon dissolved in normal saline was injected into a coronary artery to generate flow curves of four arbitrary myocardial areas. An experimental coronary embolism was produced. Detectable and apparently significant changes in regional blood flow have been produced in this manner.

Grid versus non-grid techniques for the detection of pulmonary nodules in a chest phantom.

A partial chest phantom was constructed to compare two commonly employed radiographic techniques, 70 kVp without a grid and 120 kVp with a grid, for the detection of pulmonary nodules. The phantom consisted of human ribs embedded in paraffin, the lungs of a dog injected with silicone rubber, a tissue equivalent wax heart and beeswax nodules. The nodules ranged in size from 3-7 mm. A series of 120 films was exposed, half with each technique, and the films were interpreted by three senior residents and seven staff radiologists. More nodules of all sizes except 3 mm were detected with the 120 kVp technique. The 3 mm nodules were rarely detected with either technique. The disadvantages of the 120 kVp technique were an approximate 50 percent increase in patient exposures and almost twice as many false-positive nodule detections.

The supraclavicular fossa

The presence of a supraclavicular fossa and the visibility of its floor on chest radiographs have been ignored in the radiological literature. In a study of 500 randomly selected chest radiographs, we could identify the floor of the fossa in 29% of patients. There is extreme normal variation in the visibility, depth, and symetry of the two sides. However, the fossa can occasionally stimulate a parenchymal lung abnormality such as a fluid level or an emphysematous bleb in the upper outer lung fields.

The Cutoff Characteristics of Rotating Grids

The cutoff characteristics of rotating grids are qualitatively and quantitatively different from those of comparable stationary grids. Rotating grids focus to a point in space so lateral decentering occurs in all directions from the central axis of the grid. Consequently, they cannot be used for oblique radiographic techniques. For any type or amount of decentering, cutoff is approximately one-third less for rotating grids.

Grid Cutoff with Oblique Radiographic Techniques

Many radiographic techniques involve tilting the x-ray tube so that the beam strikes the grid at an oblique angle. To avoid cutoff from focus-grid distance decentering, the focal spot of the x-ray tube should be positioned on the convergent line of the grid. If the focal length of the grid is used for the distance from the target to the center of the grid with oblique techniques, there is significant cutoff from focus-grid distance decentering.