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Biomedical subjects

B Smevik

Publications and source records attributed to B Smevik.

At least 19 recordsLinked to original sources
PubMed2000

[Magnetic tomography--new imaging techniques and future perspectives].

BACKGROUND: MRI is a promising imaging technique for diseases in most organ systems in children. MATERIAL AND METHODS: This review discusses MRI on the basis of the literature and our own experience. RESULTS: The value of MRI in paediatric neuroradiology is firmly established. In congenital heart defects and other reasons for cardiovascular imaging in children, the non-invasiveness of the method is appealing. MRI is already included in most international paediatric oncology protocols. Paediatric applications for MRI differ from those in adults as they focus on developmental and congenital abnormalities. Furthermore, some pathological conditions are unique to children. MRI is also a promising alternative to established methods for evaluation of the urinary tract. There are some specific problems with MRI in children. Immobilisation and sedation techniques include tight wrapping of the newborn with soft elastic bands, feeding immediately prior to the study, and allowing one parent into the magnet with the child. Midazolam and oral chloral hydrate are usually used for sedation. INTERPRETATION: MRI is of particular value in the paediatric age group as the method is capable of highly accurate imaging in a variety of congenital and paediatric diseases without the use of ionising radiation. Faster sequences and better resolution will further increase the use of MRI in children.

Adult↗
PubMed2000

Complementary investigations in bronchiectasis in children.

The different modalities suitable for image-guided diagnosis of bronchiectasis in children are described. Plain chest radiography is still the most important imaging method of respiratory disease in children, but when it comes to ascertaining the diagnosis of bronchiectasis, high-resolution computed tomography (CT) is currently the method of choice. Ultrafast computed tomography and multislice computed tomography have increased the value of computed tomography as a diagnostic tool by reducing the need for sedation or anaesthesia. Bronchography is as a rule no longer necessary to perform on this indication alone. If modern, high-quality computed tomography is not readily available, however, bronchography may still be necessary preoperatively.

Bronchiectasis↗
PubMed1997

[Catheter treatment of congenital heart defects. Arterial septal defects and open ductus arteriosus].

The results of new methods for catheter treatment of congenital heart defects are presented. Between 1989 and 1996 closure of a patent ductus arteriosus was performed in 66 instances on 63 patients, eight of which were with coils. Three patients were treated twice, one with an additional umbrella, two with coils. The overall complete closure rate for umbrellas was 75%, after two ducts, which were initially totally occluded, recanalized. In six more patients the procedure was either aborted or indication was not present. All six ducts treated with coils as the first procedure were completely closed. One of two patients who had residual leak after previous umbrella treatment achieved complete closure after subsequent coil implantation. Closure of atrial septal defects in the oval fossa was performed using the Amplatzer septal occluder in seven children. Complete closure was achieved in all of them. There have been no complications, in particular there have been no cases of embolization in any of the groups. The results seem to indicate that coil occlusion of a persistently patent duct may be at least as good as the umbrella in terms of complete closure. So far both methods have been safe, but experience with coils is limited. The closure of atrial septal defects shows encouraging results. We will continue to offer this treatment as an alternative to open heart surgery in carefully selected patients.

Adolescent↗
PubMed1997

Cure of infantile myofibromatosis with severe respiratory complications without antitumour therapy.

UNLABELLED: The prognosis of infantile myofibromatosis (IMF) depends on the organs involved: the prognosis is very poor if vital viscera are affected, but excellent if there is no visceral involvement. We report the case of a boy presenting with a pathological fracture at the age of 6 weeks. Progressive osteolytic lesions in the whole skeleton until the age of 8 months led to respiratory failure due to a softened thoracic wall requiring mechanical ventilation for 11 months. No pulmonary, laryngeal or other visceral involvement was found. In spite of the rapidly progressing disease and serious complications only supportive therapy was given. The lesions subsided gradually leaving slight deformities but normal function. At the age of 3.5 years the boy has an excellent quality of life. CONCLUSION: This case illustrates that even in progressing, complicated multifocal infantile myofibromatosis (without visceral involvement) the lesions can resolve without antitumour treatment if high quality intensive care is supplemented.

Bone Neoplasms↗
PubMed1996

[Embolization of congenital pulmonary arteriovenous malformations].

Patients with arteriovenous pulmonary malformations are at risk of developing secondary brain disease such as transient ischemic attacks, strokes or abscesses. Lethal haemothorax and haemoptysis also occur. 12 of 14 malformations in five patients were treated using a total of eight procedures. One patient experienced a transient unilateral hemiparesis, otherwise no complications occurred. None of the 43 deployed occlusion coils was lost through the fistulas. Complete occlusion was achieved in all lesions where coils could be placed in a stable position. One patient suffered a minor recurrence. The use of interlocking detachable coils (IDC) which can be retracted or repositioned prior to full deployment is recommended.

Adult↗
PubMed1994

[The "umbrella closure" of the ductus arteriosus].

The technical details of the method are outlined, and the Norwegian experience reported: From September 1988 to January 1994 we attempted to close open ducts with the Rashkind technique in 26 patients. Two ducts were too small to accept the device, and in one case the implanted device could not be released. This patient was referred to surgery. In the remaining 23 patients the device was left in place. The mean X-ray fluoroscopy time was 15 minutes. No complications occurred. In eight patients (35%) a residual shunt could be detected by ultrasonic Doppler technique, but in seven of them haemodynamical significance was lacking. The umbrella method is a good alternative to traditional treatment.

Adolescent↗
PubMed1993

Does the administration of systemic radiographic contrast media influence the acute changes in renal physiology following exposure to extracorporeal shock waves in dogs?

Five anesthetized dogs were studied for 4 to 5 hours after administration of extracorporeal shock waves to one kidney, the contralateral organ serving as control. Repetitive major doses of the nonionic monomeric radiographic contrast medium (CM) iohexol were injected intravascularly before and after application of the extracorporeal shock waves for further provocation of kidney function. Urinary excretion of electrolytes, N-acetyl-beta-glucosaminidase (NAG) and kallikrein, clearances of creatinine, inulin and para-amino-hippuric acid (PAH), serum aldosterone level and plasma renin activity (PRA) were determined. On the exposed side there was a significant fall in urinary osmolality. Effective renal plasma flow (ERPF) was reduced and glomerular filtration rate (GFR) was unchanged; thus filtration fraction (FF) was increased. Extraction of PAH was reduced, and true renal plasma flow was unchanged. Urinary osmolality on the control side was unchanged. There was a fall in ERPF and increased GFR; therefore, FF increased. The mean rise of PRA in the exposed kidney was significant after shock waves. Urine volume and urinary excretion of electrolytes and kallikrein were stable bilaterally. Relating the results to those obtained in identical canine experiments without CM, simultaneous administration of CM does not seem to significantly influence the changes in kidney function parameters caused by extracorporeal shock waves in the dog.

Acetylglucosaminidase↗
PubMed1993

Absence of activation of proteolytic enzymes by extracorporeal shock waves.

The mechanism of tissue damage by extracorporeal shock wave lithotripsy has not been clarified, but proteolytic enzymes are known to play an important role in tissue breakdown in response to other types of injury. Screening tests for activation of the proteolytic enzymes kallikrein, plasmin, trypsins 1 and 2, and granulocyte elastase therefore were performed for 4 to 5 hours in 14 dogs after unilateral treatment with 1500 or 2000 extracorporeal shock waves under anesthesia and vigorous hydration. We also studied the activity of the proenzymes prekallikrein, plasminogen, and prothrombin and three plasma protease inhibitors (kallikrein inhibitor, antiplasmin, and antithrombin III). Blood from both renal veins (treated and control kidneys) and the aorta and tissue samples of the injured renal parenchyma and corresponding areas of the control kidneys revealed no proteolytic enzyme activation by the shock waves and no decline in the activities of proenzymes and enzymes inhibitors. Significant proteolysis does not seem to play a part in the tissue injury induced by extracorporeal shock wave lithotripsy.

Animals↗
PubMed1992

Comparison of 12-bit and 8-bit gray scale resolution in MR imaging of the CNS. An ROC analysis.

A reduction in gray scale resolution of digital images from 12 to 8 bits per pixel usually means halving the storage space needed for the images. Theoretically, important diagnostic information may be lost in the process. We compared the sensitivity and specificity achieved by 4 radiologists in reading laser-printed films of original 12-bit MR images and cathode ray tube displays of the same images which had been compressed to 8 bits per pixel using a specially developed computer program. Receiver operating characteristic (ROC) curves showed no significant differences between film reading and screen reading. A paired 2-tailed t-test, applied on the data for actually positive cases, showed that the combined, average performance of the reviewers was significantly better at screen reading than at film reading. No such differences were found for actually negative cases. Some individual differences were found, but it is concluded that gray scale resolution of MR images may be reduced from 12 to 8 bits per pixel without any significant reduction in diagnostic information.

Central Nervous System↗
PubMed1991

[Cerebral hemorrhage in newborn infants. A 1-year case load].

Over a period of one year (1984) routine cerebral ultrasonography was performed on all premature infants (gestational age less than 37 weeks), all infants weighing less than 2,250 grams at birth and all other infants with clinical indications such as severe asphyxia, seizures etc. Altogether 209 infants were examined. The overall incidence of intracranial hemorrhage (ICH) was 18.7% (39 infants), and was 32.1% in premature infants and 6.2% in term infants. Most infants developed ICH before the third day of life. A strong correlation was found between gestational age and ICH, and between respiratory disease and ICH. No correlation was noted between ICH and parameters related to birth or maternal history. There was a higher incidence of ICH in transported infants than in inborn infants. Only four patients who died from large parenchymal bleedings showed clinical symptoms of ICH.

Cerebral Hemorrhage↗
PubMed1991

Acute morphological changes in canine kidneys after exposure to extracorporeal shock waves. A light and electron microscopic study.

The acute effects of extracorporeal shock waves on renal morphology were studied by light and electron microscopy in 14 dogs. One kidney received an average clinical number of exposures, the nonexposed, contralateral kidney serving as control. The original Dornier HM-3 generator was used in 3 animals, the modified version in 11. Intravascular radiographic contrast medium was administered in five animals. Damage was observed in all exposed kidneys, none in the contralateral control kidney. The effects were characterized by renal and perirenal hemorrhage and edema, parenchymal hemorrhagic foci with tissue destruction, often extending from cortex to medulla. In the nearby regions there was endothelial cell damage in arteries, veins and glomerular capillaries. Breaks in the wall of these vessels were detected with platelet plug formations and thrombi. In glomeruli, breaks of Bowman's capsule and epithelial cell damage with loss of foot processes were observed. A wide range of tubular cell damage was demonstrated, ranging from vacuolization to complete necrosis. Tubular lumina were filled with red cells, indicating renal origin of hematuria. The tissue damage was less pronounced in kidneys exposed to the modified lithotriptor than to the original. No difference in the quantity or quality of damage was detected whether radiographic contrast medium was administered or not.

Animals↗
PubMed1991

Do extracorporeal shock waves affect urinary excretion of glycosaminoglycans?

Urinary excretion of glycosaminoglycans (GAGs) was studied in 9 anaesthetised dogs and 10 patients with single kidneys. The animals were studied for 4 to 5 hours after administration of shock waves to 1 kidney, the contralateral organ serving as control. Urinary excretion of GAGs was measured on both sides. The patients were studied 0 to 24 and 32 to 56 h after extracorporeal shock wave lithotripsy (ESWL). In the animals an increased mean urinary excretion of GAGs was observed on both sides; this was more marked in the treated kidney. The increase reflects tissue injury in the exposed kidney induced by the extracorporeal shock waves. No increase in mean urinary excretion of GAGs was observed in the patients.

Adult↗
PubMed1990

[Magnetic tomography in congenital heart defects].

Magnetic resonance imaging (MR) has been shown to be valuable in defining cardiac anatomy in a variety of cardiac abnormalities. The article describes the technique and results of MR in 32 children with congenital heart disease. MR clearly depicts the anatomy of the great vessels, and may be used for the evaluation of palliative systemic-pulmonary artery shunts. In postoperative controls, MR may replace or postpone angio-cardiography. MR is also a promising technique for the evaluation of myocardial and valvular function. Especially in small children, the non-invasive nature of MR is of great importance.

Child, Preschool↗
PubMed1990

[Percutaneous closure of ductus arteriosus using the umbrella technic].

In four patients between three and five years of age we performed closure of open ductus arteriosus with the Rashkind umbrella technique after percutaneous approach from the right groin. The smallest internal ductus diameter measured between 2 and 4 mm, and pulmonary blood flow was from 1.4 to 2.0 times systemic flow. In all four patients, pulmonary artery pressure was normal. In three patients the ductus arteriosus was completely closed, in the fourth a small residual shunt persisted. There were no complications. We describe the method in detail.

Catheterization↗