Precision surgery with an electromagnetically induced current convergence probe application in aneurysm treatment, angioplasty, and brain tumor resection in in vivo and in vitro models.

A hand-held probe, or one introduced through a catheter, rapidly produces an extremely high, tissue-vaporizing temperature in a precisely defined manner enabling surgeons or interventional radiologists to perform angioplasty, thrombose aneurysms, and vaporize tumors. The probe is operated in a near field of an inductive coil, and the current induced in the biologic tissue is converged maximally at the tip of the probe at the resonance frequency of both the inductor and the probe, producing a maximum temperature in excess of 1400 degrees C. Radio-frequency power controls the probe-tip temperature. The operation of the probe is comparable to that of a CO2 or YAG laser and is complementary to laser-surgical techniques. The low cost relative to lasers and simplicity of the device including its disposable components make the prospect of commercialization of this device promising.

Pseudocoarctation of the aorta.

We report a case of a 50-year-old man with pseudocoarctation of the aorta that we examined with magnetic resonance imaging (MRI) and digital subtraction angiography (DSA). The MR images demonstrated the characteristic "kink" of the aorta and the absence of true coarctation. These appearances were confirmed by DSA, but we believe MRI to be the better method for examining the aorta because it is non-invasive and has the ability to display the mediastinal anatomy in the sagittal plane, in addition to the axial and coronal planes.

Angiopyroplasty using electromagnetically induced focused heat.

A metal-tipped catheter capable of inducing and withstanding extremely high temperatures suitable for angiopyroplasty has been developed. The probe utilizes external radiofrequency (RF) energy focused on the tip. A relatively inexpensive catheter and RF source make this a very plausible alternative to laser systems.

Electromagnetically induced focused heat in the treatment of surgically created aneurysm models.

A hand-held radiofrequency (rf) probe of a novel design based on the principle of the induced current convergence was used to treat aneurysm models using focused hyperthermia. Aneurysms were created surgically in rats by a side-to-side anastomosis between the inferior vena cava and the abdominal aorta or by grafting a donor abdominal aorta from one rat onto the abdominal aorta of another rat. Aneurysms were treated by inserting the 0.3-mm diameter probe tip into the fundus and applying the power for brief periods (0.5-1.5 sec) using a foot pedal. Collapse of the fundus was observed as the result of the heat-induced thrombosis. Thermal distribution in the immediate vicinity of the probe as well as the heating rate were measured in a uniformly dielectric phantom and in rat vessels. The aneurysms were histologically examined immediately, three days, and three weeks after the treatment. Complete obliteration of the aneurysms and patency of the parent arteries were confirmed. Partial integrity of the vessels around the lesion was also confirmed.

Gangrene of the foot: a complication of phlebography.

One believes there is a necessity to bring to widespread attention a most serious complication of what is often considered a mundane radiological examination - lower extremity contrast venography. So mundane is it considered in fact, that outside of resident teaching programs, an informal telephone survey of 15 hospitals from 240 beds to 780 beds revealed that a number of injections and examinations: (a) were conducted entirely by technologists without any pretense of radiologist supervision; (b) that the radiologist "supervised" the injection (i.e. was in the "immediate vicinity") or; (c) injection was preferentially done by the radiologist, but no reason was seen why a skilled non-physician could not conduct the examination.

Abandonment of endoprosthetic drainage technique in malignant biliary obstruction.

This report discusses a 3-year experience with the techniques of internal/external catheter and endoprosthetic stent drainage in 175 patients with obstructive jaundice. In 166 patients, the obstruction was bypassed satisfactorily. The complications encountered with these techniques are compared, and the radiation doses involved are emphasized. It is not necessary to put patients through the extra time and pain related to the placement of the endoprosthesis, because internal/external catheter placement produces the same desired result of biliary decompression without the higher radiation doses to the radiologist.

The use of high-speed film/screen combinations to improve diagnostic image quality.

Increased film speed, when used with the same intensifying screens, results in an increase in quantum "noise." Nevertheless, this increased noise is not the primary degrading factor of diagnostic quality during arteriography and cross-table myelography. The authors show that the use of high-speed film/screen combinations decreases the threshold diameter for blood vessel detectability on arteriograms. Also, these combinations can be used to increase the contrast between opacified spinal fluid and surrounding bone during cross-table myelography.

Results of testing of an angiographic catheter.

A catheter composed of two dissimilar plastics has been found to be virtually indestructible under severe experimental conditions. Compared with four other types of commercially available catheters, it rates well in terms of flow rate, bursting strength, memory, radiodensity, and thrombogenicity.

Sonography of hypertensive portal venous system: correlation with arterial portography.

Sixteen patients with portal hypertension and bleeding from gastroesophageal varices were studied prospectively by sonography and arterial portography. Sonography was able to demonstrate anechoic venous structures in characteristic sites in the upper abdomen corresponding with portosystemic collateral veins seen with arterial portography. Of four patients with sonographic visualization of a dilated umbilical vein, three were seen with angiography. Two patients had periportal collateral veins seen with both methods. Of 10 patients with retrograde opacification of the left gastric vein, nine were seen with sonography. Although all 16 patients had endoscopic proof of gastroesophageal varices, only 12 were demonstrated by angiography. Of these 12 patients, 10 had sonographic visualization of varices alone the gastroesophageal junction and lesser curvature of the stomach. One patient with opacification of a gastrorenal communication also had left upper quadrant venous abnormalities at sonography. Sonography is useful in the noninvasive identification of portosystemic collateral vessels in patients with portal hypertension.

Some normal variations of knee arthrograms and their anatomical significance.

Knees obtained after amputation were fixed with formalin after the joint space was distended with air. The joints were then either dissected or frozen and sectioned vertically with a band saw in planes comparable to those visualized during arthrography. By comparing these anatomical specimens and arthrograms, the anatomical explanations for some normal variations visible or arthrograms could be identified. These variations included the appearance of the popliteus tendon and the posterior part of the lateral meniscus, the air-filled cul-de-sac posterior to the medial meniscus, and the interconnections of the joint space and the gastrocnemius and semimembranosus bursae.

An angiographic approach to hepatobiliary diseases.

Abdominal aortography and celiacomesenteric angiography preceded or followed by cholangiography and portography provide the most comprehensive approach and thorough angiographic evaluation of hepatobiliary-pancreatic diseases. Transhepatic catheterization and subsequent embolization of gastroesophageal veins are of great value in actively bleeding, as well as in stable, varices. Exit embolization of the needle tract minimizes the possibility of the leakage of blood or of bile.

Arteriographic bleeding: a new sign.

A new sign of arteriographic bleeding, diastolic clearance of angiographic contrast medium selectively from the bleeding vessel, is described. The use of this sign must be confined to rapidly bleeding end-vessel distributions or when nonopacified collateral circulation is not a consideration. It should not be confused with the normal washout of contrast substance in areas of multiple parent vessel collateral circulation where intermittent opacification is a normal feature.