Fine structure of the Panorex image.

The plane of focus free of blur margin, as well as the rate of increase of blur margin both medial and lateral to the plane of focus, has been described in the Panorex panoramic x-ray machine by means of a continuous phantom. The average of readings made at ninety-eight separate film positions yields a focaltrough thickness of 4.3 mm. if a blur margin of 10 per cent of the phantom's film image is accepted, the percentage blur increasing directly with trough thickness. The factor enlargement of objects at the plane of focus is uniform at 1.25 and increases along with percentage blur more rapidly for objects medial to the plane of focus than for objects lateral to it.     

Methemoglobin reductase: inactivation and protection against inactivation during disc gel electrophoresis

Methemoglobin reductase was found to be inactivated during electrophoresis on ammonium persulfate polymerized polyacrylamide gels. Hemoglobin in various states of ligation offers protection from inactivation. Thiols such as dithiothreitol also offer protection but the effect due to hemoglobin is not provided by its sulfhydryl groups.     

Intravenous digital subtraction angiography of the intracranial veins and dural sinuses

When combined with computed tomography, IV DSA is usually of sufficient quality to replace conventional angiography in most patients with abnormalities of the larger intracranial veins and sinuses. Preoperatively, IV DSA can be used to evaluate normal anatomic variations of venous outflow to determine what sinuses can be safely occluded if necessary in the region of the temporal bone, jugular fossa, and base of the skull. Patients with glomus jugular tumors and carotid-cavernous fistulas also need conventional angiograms to define the feeding vessels of these lesions for obliteration by embolization or surgery.     

IgG synthesis rate in evaluation of multiple sclerosis in a community hospital

We obtained CSF and serum from 21 patients with definite MS in a community hospital. Ninety percent of patients had an elevated IgG synthesis rate, comparable with the sensitivity of oligoclonal bands (0.95) or the IgG index (0.90) and better than the IgG% (0.47) in definite MS. We found that no area hospital routinely employs the IgG synthesis rate. The low-sensitivity IgG% and the dimensionless IgG index can be abandoned. The linear IgG synthesis rate and oligoclonal band scanning should be the CSF tests of choice.     

Intraarterial digital subtraction angiography in diagnostic arteriography

Intraarterial digital subtraction angiography (DSA) was performed in 133 diagnostic arteriographic procedures during a 10-month period. The increased contrast resolution of DSA permitted the use of a dilute (15%) contrast material. A significant reduction in contrast material dose compared with conventional film-screen arteriography and intravenous DSA was thus achieved. This was especially advantageous in patients with diminished renal function. The dilute contrast material also resulted in less patient discomfort. Subtracted images were available immediately on cathode ray tube display, resulting in faster procedures, and a considerable saving in film cost compared with conventional arteriography. It is concluded that intraarterial DSA is a useful technique that may replace conventional film-screen arteriography in many applications.     

Long-segment femoropopliteal stenoses: is angioplasty a boon or a bust?

Analysis of 193 femoropopliteal angioplasties demonstrated patency rates in the stenotic group of 75.5% at 6 months and 54.4% at 54 months. The patency rates for the occlusive group were 93.7% at 6 months and 72.9% at 54 months; these rates were significantly better than those in patients with stenoses. A group of 14 patients with long-segment (greater than 7 cm) stenosis had the highest risk of early failure, with a 6-month patency of 23.1%. After removal of the long-segment stenosis group from the results, there were no significant differences between the long-term patencies for stenotic and occlusive lesions. If angioplasty of long stenoses is attempted, a high initial success rate but early failure should be anticipated.