A proposed scheduling model to improve use of computed tomography facilities.

A nonpreemptive queuing system based upon operations management theory is used to evaluate expected steady state wait periods for traditional and distributed CT scheduling models. Both models are constructed using two classes of patient service--emergent and nonemergent. The former model uses only one point of service per scanner while the latter employs multiple points of service in order to accomplish all of the functions necessary to complete a CT scan. Sample data are drawn from a tertiary care hospital-based system using a traditional service model. Comparison of a traditional and distributed service system, each with emergent and nonemergent service classes, shows that breaking as many activities as possible out of the scanner should provide substantial improvements in cost efficiency and service for patients having CT scans. Nonemergent patients may experience as much as an 89% reduction in steady-state wait times while emergent patients may experience as much as a 59% reduction in wait times. The cost efficiencies recognized either through increased scanner utilization or reduced scanner needs, even with only modest improvements, should more than offset any additional personnel needed to implement a distributed model. Proper implementation of a distributed scheduling model for CT scanning can provide substantial cost efficiencies and improvements in service for both nonemergent and emergent CT scans.

Percutaneous transjugular portosystemic shunt.

OBJECTIVE: --To determine the effectiveness of the Palmaz balloon expandable stent for the creation of a transjugular intrahepatic portosystemic shunt. The device is designed to achieve portal decompression in patients with variceal hemorrhage secondary to portal hypertension. DESIGN: --Transjugular intrahepatic portosystemic shunting was performed in eight patients during a 9-month period. Mean follow-up was 5 months. PATIENTS: --All patients had cirrhosis with portal hypertension and varices. Bleeding occurred in seven patients from esophageal varices and in one patient from hemorrhoids. MAIN OUTCOME MEASURES: --Shunt patency and recurrent variceal hemorrhage. RESULTS: --Shunts created from a transjugular approach between a hepatic and a portal vein (diameters of 8 to 12 mm) lowered the average portosystemic pressure gradient from 36 to 11 mm Hg. Mean postoperative hospital stay was 7.7 days. Complete variceal decompression after transjugular intrahepatic portosystemic shunt placement was identified endoscopically in all eight patients. The patient treated for hemorrhoids rebled and was treated successfully by transfemoral balloon expansion of the shunt diameter from 8 to 12 mm. All shunts were patent at 1 to 9 months (mean, 5 months) of follow-up. CONCLUSION: --Initial results suggest that transjugular intrahepatic portosystemic shunt is a safe and effective method of portal decompression for the treatment of variceal hemorrhage.

Percutaneous placement of a balloon-expandable intraluminal graft for life-threatening subclavian arterial hemorrhage.

A balloon-expandable intraluminal graft was percutaneously deployed in the left subclavian artery of a 43-year-old woman. This graft was made of a stainless steel, 30-mm Palmaz balloon-expandable iliac stent completely covered with a thin coat of silicone. The procedure was successful in managing and preventing life-threatening hemorrhage as a large-bore catheter was removed from the subclavian artery via its subcutaneous tunnel. Surgical repair of the high brachial-axillary sheath insertion site was required after percutaneous deployment of the graft. However, the grafting procedure succeeded in obviating a thoracotomy. At follow-up of 6 months, despite diminution in brachial pulse volume recordings, the patient is asymptomatic at rest. She experiences mild fatigue with extremes of upper extremity exercise and declines angiographic follow-up and further intervention.

Compact contrast material bolus with a new 5-F angiographic catheter.

The conventional pigtail catheter was compared with the 5-F Tennis Racquet catheter for abdominal aortography with digital subtraction angiography. Resulting aortograms were judged on the basis of the quality of aortic opacification and renal artery visualization. The authors concluded that the Tennis Racquet catheter produces a more compact contrast material bolus, and its use is associated with acquisition of superior abdominal aortograms.

Medical student perceptions of diagnostic radiology. Influence of a senior radiology elective.

To assess the impact of a four-week elective on medical student perceptions of diagnostic radiology, we gave questionnaires to 96 senior students on the first and last days of the rotation. Eighty-five anonymous entrance responses and 73 exit responses were obtained during a 13-month interval. Compared with other clinical specialties, the students viewed radiology as third, behind surgery and medicine, in terms of required breadth of knowledge, skill, training, and "glamour." Radiology was also perceived to have the lightest workload with the exception of psychiatry. Responses did not significantly change after completion of the elective. Perceived advantages and disadvantages of radiology were studied in detail in a subset of students. Exit responses indicated that the elective promoted favorable perceptions of radiology but did not change the relative rankings of the various specialties. It appears that at our institution basic attitudes concerning radiology are formed prior to the senior radiology elective and are affected only moderately during the elective.

Hickman nodule: a mimic of metastatic disease.

A characteristic small subcutaneous soft-tissue mass can be seen on the computed tomographic scans of patients after removal of Hickman catheters. The mass is indistinguishable from subcutaneous metastatic deposits seen with a variety of malignant tumors. This potentially confusing finding can be differentiated from true metastatic disease by the characteristic location of the subcutaneous nodule in the second or third anterior intercostal space, along the midclavicular line, and by the absence of other subcutaneous masses.

Neuroimaging of scuba diving injuries to the CNS.

Diving accidents related to barotrauma constitute a unique subset of ischemic insults to the CNS. Victims may demonstrate components of arterial gas embolism, which has a propensity for cerebral involvement, and/or decompression sickness, with primarily spinal cord involvement. Fourteen patients with diving-related barotrauma were studied with MR imaging of the brain and spinal cord and with CT of the brain. In four patients with presumed cerebral gas embolism, cranial MR was abnormal in three patients while CT was abnormal in only one. Twelve patients had decompression sickness and spinal cord symptoms. MR documented spinal cord abnormalities in three patients. However, scans obtained early in our study were frequently limited by technical constraints. MR of the brain is more sensitive than conventional CT scanning techniques in detecting and characterizing foci of cerebral ischemia caused by embolic barotrauma to the CNS. Although spinal MR may be less successful in the localization of spinal cord lesions related to decompression sickness, these lesions were previously undetectable by other neuroimaging methods.

Aortobronchopulmonary fistula complicating aortic aneurysm: diagnosis in four cases.

Aortobronchopulmonary fistula, a fistulous connection between the aorta and lung, is uniformly fatal in untreated cases. However, with early recognition and surgery, the survival rate exceeds 80%. We have had four patients with aortobronchopulmonary fistula, all of which resulted from thoracic aortic aneurysms (two after grafting of thoracic aortic aneurysms, one mycotic, one atherosclerotic). All four patients presented with hemoptysis. All four had a chest radiograph, which in two showed the aneurysm and in three showed airspace disease adjacent to the aorta. The aneurysm was shown by CT in one of two patients and by aortography in two of three patients. Neither CT nor aortography showed the fistula. Aortobronchopulmonary fistula was proved by surgery in two of the patients and by autopsy in the other two. A high index of suspicion is necessary to make the diagnosis of aortobronchopulmonary fistula. The diagnosis should be considered in patients who have minor or major hemoptysis, with either coexisting thoracic aortic aneurysms or history of thoracic aneurysm repair.