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41.
42.
A total of 140 sets of abdominal radiographs were reviewed independently by four qualified diagnostic radiologists. The degree of interobserver agreement was determined by calculating kappa values for 19 commonly used radiographic signs and diagnoses. There was fair to excellent interobserver agreement for 11 signs and diagnoses and poor agreement for the remaining eight. The signs and diagnoses for which agreement is poor cannot be considered reliable and include particularly large bowel obstruction and nonspecific gas pattern. 相似文献
43.
The effects of section separation on image contrast and calculated T1 relaxation times were investigated in healthy volunteers and a phantom using an early commercial version magnetic resonance imaging system. The effects are explained qualitatively on the basis of side lobes of excitation occurring outside the selected section resulting in reduction of the time permitted for T1 relaxation. The options for dealing with imperfect section selection, including separation of the sections (i.e., leaving gaps) and nonsequential excitation, are illustrated and the trade-offs involved in each explained. 相似文献
44.
Fifty ASA Class III patients were divided randomly into two equal groups for induction of anaesthesia with diazepam 0.25 mg/kg, or midazolam 0.15 mg/kg. All subjects were premedicated with a narcotic and monitored by ECG, radial arterial catheter and a spirometer for measurement of minute ventilation. The QF interval (time period from the Q wave of the ECG to the foot of the radial artery pulse), mean arterial pressure, heart rate and minute ventilation were recorded before, during and immediately after the induction of anaesthesia. Although mean arterial pressure fell slightly (6%) following midazolam, all other cardiovascular variables were stable in both groups. Minute ventilation was depressed to 70% of control by both drugs and nearly one-half the diazepam patients complained of pain on injection compared with only one midazolam patient. These data suggest that midazolam is a reasonable alternative to diazepam for induction of anaesthesia in the high-risk patient. 相似文献
45.
In two groups of 31 healthy patients undergoing minor elective surgery, anesthesia was induced intravenously with either midazolam maleate, 0.2 mg/kg, or thiopental, 3.5 mg/kg. All subjects received 2 micrograms/kg fentanyl 5 min before the induction agents. Induction time with midazolam was significantly longer than with thiopental (97.1 +/- 10.9 sec vs 59.4 +/- 5.0 sec) and time to orientation postoperatively was significantly longer after midazolam (31.7 +/- 4.2 min vs 11.0 +/- 1.1 min). Continued recovery after orientation, measured by a series of psychomotor tests, was also significantly longer with midazolam than with thiopental. Anterograde amnesia was evident in 84.8% of the midazolam treated patients and in only 31.4% of the thiopental group. This degree of absence of recall was acknowledged positively by the affected patients. The protracted recovery period may limit the use of midazolam in short surgical procedures. 相似文献
46.
Perforation of the inferior vena cava with aortic and vertebral penetration by a suprarenal Greenfield filter 总被引:1,自引:0,他引:1
Various complications have been reported after insertion of the Greenfield filter. This report describes an unusual complication after suprarenal placement of this filter: spreading of the filter struts, with perforation of the inferior vena cava, and penetration of the aorta and a vertebral body, followed by fracture of one of the struts. 相似文献
47.
48.
Cardiovascular function during controlled hypotension induced by adenosine triphosphate or sodium nitroprusside in the anesthetized dog 总被引:3,自引:0,他引:3
The present study was undertaken to compare the hemodynamic effects of adenosine triphosphate (ATP) and sodium nitroprusside (NP) given in equieffective doses to induce hypotension during halothane anesthesia. Eight dogs, instrumented with pressure and ultrasonic dimension transducers for assessment of left ventricular (LV) performance, were given both NP and ATP. Regional blood flow was measured by radioactive microspheres. After 20 min of infusion, both drugs decreased systemic arterial pressure by 36% with minimal changes in cardiac index (CI), LV end-diastolic pressure, or heart rate. However, hypotension produced by ATP was associated with a greater CI (3.84 +/- 0.32 vs 2.97 +/- 0.35 L X min-1 X m-2) than was NP and also associated with a further decrease in systemic vascular resistance (14.4 +/- 1.4 vs 17.7 +/- 2.2 mm Hg X L-1 X min X m2). Left ventricular global function, measured by the slope of the linear regression line of the LV end-systolic pressure-diameter relation (Ees), did not change significantly after either drug. Blood flow to the coronary bed was significantly greater with ATP than with NP (231.6 +/- 30.6 vs 81.7 +/- 6.1 ml X min-1 X 100 g-1). Except for an increase in hepatic arterial blood flow with NP, neither ATP nor NP significantly altered blood flow to the brain, spinal cord, spleen, kidney, jejunum, muscle, and skin. Controlled hypotension by ATP was stable and rapidly reversible without rebound hypertension. The results of this study indicate that ATP is a rapidly acting, effective hypotensive agent that compares favorably with NP. 相似文献
49.
High-resolution MR imaging with local coils 总被引:4,自引:0,他引:4
We propose the following rules to govern the choice of local coils by the practicing radiologist: 1. Smaller coils permit smaller FOVs and better resolution. The coil should be as small as possible. 2. Match the ROS of the coil to the FOV, which will be determined by the anatomic region of interest. 3. For the case of a choice between surface coils or between a surface and a whole- or partial-volume coil, the anatomic region should lie on the high side of the crossover point. For the case of a choice among whole-volume coils, the smallest coil that surrounds the region of interest should be chosen. 4. Considerations in regard to the anatomic shape or the need to vary the position of the structure may alter the choice of coil from that obtained by S/N considerations alone. 相似文献
50.
White-matter lesions in MR imaging of clinically healthy brains of elderly subjects: possible pathologic basis 总被引:9,自引:0,他引:9
Patchy white-matter lesions occur in the magnetic resonance (MR) imaging brain studies of 20%-30% of neurologically healthy elderly subjects. To determine the frequency of histologically verifiable white-matter lesions at autopsy in such subjects the authors examined serial, microscopic, whole brain sections from 15 clinically healthy subjects aged 52-72 years. Small white-matter lesions were found in 12. In these 12, zones of atrophic perivascular demyelination were present in eight brains. These are not the familiar thrombotic, embolic, or ischemic vascular lesions that produce acute necrosis. This mild vascular insufficiency produces atrophy, which has been recognized in the pathology literature but whose clinical significance remains unknown. Other lesions seen were small vascular malformations in the centrum ovale in four brains, diverticula of the lateral ventricle extending into the white matter in three, and an isolated central white-matter infarction in one. All of these lesions are probably the basis of the patchy white-matter lesions seen on MR imaging studies in the neurologically healthy elderly population. 相似文献