A technique for image salvage in MR.
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Adolescent↗
Biomedical subjects
G Lund
Publications and source records attributed to G Lund.
The preliminary evaluation of Mn DTPA as a potential contrast agent for nuclear magnetic resonance imaging.
The pharmacokinetics of 54Mn administered as Mn-diethylenetriamine pentaacetic acid (DTPA) are being investigated to determine if tissue-specific uptake of manganese could be observed while increasing urinary excretion. This chelation and increased excretion should reduce toxicity. In order to obviate the need for repetitive quantitative nuclear magnetic resonance imaging (NMR) we have substituted tracer amounts of a radioisotope of manganese, Mn-54, for the stable ion. By 6 hours, 58 +/- 7% of the injected dose had been excreted in the urine. Peak liver accumulation occurred within 30 minutes (0.50 +/- 0.14% injected dose/g X kg body weight). The pancreas also showed a relatively high accumulation of tracer (0.25 +/- 0.04%/g X kg body weight), reaching a peak at 4 hours. The pancreas to liver ratios were highest at 6 hours (0.7). There was also a substantial accumulation of the manganese in bile. The blood concentration fell very rapidly with little tracer remaining in the blood at 1 hour. Based on these pharmacokinetics, imaging experiments were conducted before, immediately after, and 9 or 24 hours postinjection. These images showed enhanced kidneys and, later (at 9 hours), an excellent parenchymal-collecting system differentiation. The gallbladder was negatively enhanced. The liver showed either increased or decreased signal strength relative to skeletal muscle depending on the pulse sequence used. We conclude that Mn++, administered as Mn-DTPA, merits further investigation as an NMR contrast agent.
Animals↗
Tattooing of eyelids: magnetic resonance imaging artifacts.
We describe artifacts (linear densities and distortion of the shape of the globe) on Magnetic Resonance Imaging (MRI) of the brain and orbits that result from the tattooing of human eyelids with iron oxide particles. Similar artifacts are frequently seen with certain types of external eye cosmetics and dental fillings or braces that contain ferromagnetic materials. The artifacts are most likely due to the distortion of the local magnetic field by the iron oxide. The artifact was reproduced when a tattooed pig's ear was scanned. Plain x-ray films did not detect the iron oxide. These small artifacts should be recognized and not confused with abnormalities due to foreign bodies of surgical material.
Animals↗
Transcatheter closure of patent ductus arteriosus in piglets.
To better determine the risks of transcatheter closure of a patent ductus arteriosus (PDA), a model of PDA was made in newborn piglets by using 5- to 7-mm angioplasty catheters to dilate the probe PDA. This maneuver resulted in a permanent PDA in most piglets. Four to 6 weeks later PDA closure was attempted using the Rashkind PDA occluder. Twelve such procedures were attempted, using clean but nonsterile technique. Nine of 12 PDAs were successfully closed. Two failures were the result of inability to successfully traverse the PDA. This problem was solved by using a long sheath to position the device properly. Four complications occurred, all related to device release: left pulmonary artery embolization in 1 case, femoral artery embolization in 1, torn pulmonic valve cusp in 1 and lodgment of a prosthesis on a pulmonic valve cusp. Two successfully implanted devices were infected at necropsy. This study demonstrates the value of a piglet model in testing transcatheter PDA occlusion devices, the importance of sterile technique in such procedures, the hazards of device retrieval through the right heart and the feasibility of transcatheter PDA closure.
Angioplasty, Balloon↗
Detachable steel spring coils for vessel occlusion.
Spring coils for vessel occlusion were modified to include a screw-on attachment for delivery wire, which permitted safe and accurate placement of the coils. We successfully implanted coils in a dog and a lamb. They were easily retrieved from within the delivery catheters and the vessels, which is not possible with conventional coils. Coil design is described.
Blood Vessels↗
Percutaneous catheter balloons: failure to deflate.
Three examples of permanently inflated transluminal catheter balloons are presented. Two of these occurred during attempted percutaneous transluminal angioplasty. Nonsurgical solutions, which were successful in each case, are described. Percutaneous puncture with a needle or a larger diameter coaxial catheter under fluoroscopic guidance may be useful when this complication occurs during attempted balloon angioplasty or embolization with proximal balloon occlusion in large vessels.
Aged↗
Retrievable vena caval filter percutaneously introduced.
A vena caval filter than can be introduced percutaneously via the femoral vein is described. We placed these filters in five patients without complications. Experimental work in filter removal one to two weeks after insertion in dogs has been performed.
Animals↗
Percutaneous removal of ureteral calculi: clinical and experimental results.
Between May 1983 and October 1984, 51 patients who had 68 ureteral stones underwent treatment at the University of Minnesota. All 68 stones were removed successfully using percutaneous techniques. The 100% success rate is a great improvement over previous results at our institution. The primary factors appear to be the development of the retrograde-flush technique, familiarity with and access to a wider range of methods, and the increasing use of the retrograde ureterorenoscope to see stones in the lower ureter. The average patient was a 45-year-old man who had no other medical problems. The average hospital stay was 6.8 days. Experimental studies with dogs indicate that injection rates of up to 30 ml/sec of contrast material through a retrograde catheter in the ureter are safe if a vent is present in the upper collecting system.
Adult↗
Obliteration of the gallbladder without formal cholecystectomy. A feasibility study.
Obliteration of the gallbladder without formal cholecystectomy was attempted in 36 rabbits, using an open technique for cannulation of the gallbladder during laparotomy. The gallbladder was cannulated, the proximal cystic duct was occluded with cyanoacrylate-nitrocellulose 2% wt/wt, and the gallbladder mucosa was exposed to various sclerosing agents to induce fibrosis. Heated 60% diatrizoate meglumine and absolute alcohol induced a controllable chronic cholecystitis with transmural fibrosis within two weeks, a result not seen with morrhuate sodium or in the control groups. All animals survived without complications, and no instances of common bile duct damage or occlusion was noted. The results reported are promising and indicate the need for further studies of this technique for its efficacy and safety.
Animals↗
Infantile peliosis hepatis. A case report.
Peliosis in a 13-month-old infant is described. This patient appears to be the youngest reported case. The radiologic diagnosis of peliosis is difficult. The condition may be confused with other more common liver diseases. Peliosis is best assessed angiographically.
Diagnosis, Differential↗
Radiologic diagnosis of wandering spleen complicated by splenic volvulus and infarction.
Wandering spleen is a rare condition caused by malattachment of the dorsal mesogastrium. This condition is prone to torsion of the splenic pedicle leading to splenomegaly, hypersplenism, and infarction. Preoperative diagnosis can be suggested radiologically. A case of wandering spleen is reported and its embryologic, clinical, and radiographic features are discussed.
Adult↗
The thoracic paraspinal shadow: a review of the appearances in pathological conditions.
Alterations of the thoracic paraspinal shadow may give valuable information about pathological conditions of the spine, the paraspinal soft tissues, pleura and lungs. The causes of a distorted paraspinal shadow are reviewed and the main conditions illustrated by 15 selected cases.
Connective Tissue Diseases↗
Radiotherapy of T4 bladder carcinoma.
A 16% 5-year crude survival was observed in 159 irradiated patients with T4NXMO bladder carcinoma. The presence of a T4a tumour and a good performance status were important prognostic parameters. The combination of radiotherapy and weekly injections of 5-FUra (12 mg/kg) resulted in a significant 2-year survival increase. New regimens of combined radiotherapy/chemotherapy should be developed for patients with T4NXMO bladder carcinoma. The palliation effect of radiotherapy should further be evaluated, preferably in prospective studies comparing radiotherapy with other types of palliation treatment.
Aged↗
Immunoassays for measles virus nucleocapsid antigen: effect of antigen-antibody complexes.
An inhibition radioimmunoassay and a two-site immunoradiometric (four-layer) assay for the quantification of measles virus nucleocapsid antigen were established and their sensitivities compared. Both assays exhibited threshold sensitivities of from 1 to 10 ng nucleocapsid antigen per ml. Concentrations of reagents used in the assays were shown to be an important factor determining the sensitivities of the assays. Purified mumps or parainfluenza 2 virus nucleocapsids did not compete with measles virus nucleocapsids in the inhibition assay but some degree of cross-reactivity with canine distemper virus nucleocapsid was observed. Pretreatment of virus-infected cells with detergent had a significant effect on the amount of antigen detectable by the assays. SDS greatly decreased the reactivity of measles virus nucleocapsid but Triton X-100 and, to a larger degree, sodium deoxycholate released antigen from the cells in quantities greater than that detected when no detergent pretreatment was employed. Complexing of antibodies to measles virus nucleocapsids in vitro decreased dramatically the threshold sensitivity of the nucleocapsid assays. The antigen-antibody complexes could be disrupted and the components separated but the conditions employed destroyed 90% of the antigenic reactivity of the nucleocapsid and also had a deleterious effect on the antibody. Nucleocapsid antigen was readily detected in brains from hamsters with acute measles encephalitis. The assays, however, were not sensitive enough for routine detection of antigen in brains from hamsters with chronic measles encephalitis.
Animals↗
Rotational kymography. Technique for automated analysis of cine left ventriculograms.
A new device provides an automatic photographic record of left ventricular contraction and expansion. A radially slotted disk is interposed between the moving cine left ventriculogram and a disk of photographic film. By rotating either the slotted disk or the film, a kymographic record of regional wall motion is obtained. Unlike more complex computer programs, the speed as well as the magnitude of contraction can be determined.
Automation↗
Percutaneous arterial grafting.
A new technique for percutaneous arterial grafting was developed using a unique metal alloy (nitinol) with a heat dependent memory. Ten tightly wound nitinol coils (5-15 mm in diameter and 2-5 cm in length) were straightened in ice water and passed via catheter into the iliac artery or abdominal aorta of nine animals. Long term patency (15 weeks) was demonstrated in all but one graft. In one animal, an experimentally created abdominal aortic aneurysm was successfully treated by interposition of a nitinol graft. This new technique may be a valuable adjunct to conventional treatment of both obstructive and aneurysmal arterial disease in man.
Alloys↗
Percutaneous renal stone removal. Use of carbon dioxide as contrast material.
The successful performance of a percutaneous nephrostomy requires contrast material in the renal collecting system. For an exact delineation of all renal calices in a patient allergic to iodine, carbon dioxide was injected into the renal pelvis. The stone was removed successfully.
Adult↗
Kimray-Greenfield vena cava filter: percutaneous introduction.
A percutaneous technique is described for the introduction of Kimray-Greenfield filters into the vena cava through either the internal jugular or femoral approach.
Catheterization↗