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Biomedical subjects

S J Bakke

Publications and source records attributed to S J Bakke.

At least 19 recordsLinked to original sources
PubMed1992

Embolization of intracranial arteriovenous malformations and fistulas with polyvinyl alcohol particles and platinum fibre coils.

In order to reduce the recanalization rate of arteriovenous malformations and multiple dural arteriovenous fistulas, embolization was carried out with polyvinyl alcohol (PVA) particles combined with platinum fibre coils in 20 patients. The malformation was occluded more effectively than by PVA alone. Distal deposition of the emboli was obtained by improved steerable catheters (Tracker-18-unibody) and guidewires. The complication rate was lower than usually reported from studies using glue as embolic agent. It was concluded that the combination of PVA and fibre coils enhances the safety and effectiveness of embolization therapy and reduces the frequency of recanalization of intracranial AVMs.

Adult↗
PubMed1992

MR imaging of pituitary macroadenomas before and after transsphenoidal surgery.

MR findings before and after transsphenoidal surgery were evaluated in 6 cases. T1-weighted (TR/TE 600/20) sagittal and coronal images with 2 or 4 acquisitions were obtained, using 3-mm slice thickness and 0.3-mm interslice gaps. Of 18 MR examinations, 13 included coronal i.v. contrast medium enhanced images. Image quality, sinus cavernosus invasion, identification of normal pituitary tissue and tumor size were examined. All MR studies clearly demonstrated the macroadenomas whether 2 or 4 acquisitions were used, and whether i.v. contrast medium was administered or not. Surgically confirmed sinus cavernosus infiltration was seen in 4 patients. The pituitary stalk was identified separate from the tumor in 2 patients, and the gland in one. There was reduction in tumor size over time, indicating that final radiologic assessment after transphenoidal surgery is best performed 4 to 6 months postoperatively. It should not be necessary to routinely include i.v. contrast medium injection in the postoperative evaluation of macroadenomas.

Adenoma↗
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

[Magnetic resonance angiography--the start of the end of conventional angiography?].

Magnetic resonance angiography (MRA) is a new, non-invasive technique using magnetic resonance imaging to create projection images of vessels. The article gives a simplified explanation of the basic principles involved, and presents the preliminary experiences at Rikshospitalet, the National Hospital of Norway, using magnetic resonance angiography in the study of carotid and renal arteries. It is concluded that this method holds promise for more extensive use in the future. The method is likely to replace at least some of the routine conventional angiography performed today.

Angiography↗
PubMed1991

[Pseudotumor cerebri].

Pseudotumor was diagnosed in six patients aged three to 38 years during an eight year period. The diagnosis was based on headache, choked disks and normal cerebrospinal fluid and CT scans. Other symptoms were visual impairment, VIth nerve palsy and ataxia. Sagital sinus trombosis was excluded by angiography or magnetic resonance imaging. Pharmacological treatment with digitoxin, acetazolamide, furosemide or corticisteroids reversed clinical symptoms and signs in two patients. In the other four, shunt surgery with cerebrospinal fluid diversion to the right atrium or the peritoneal cavity rapidly reversed clinical symptoms and signs.

Adolescent↗
PubMed1990

[Portal vein thrombosis. Etiology, complications and therapy].

In a retrospective study of 25 patients with portal vein thrombosis the etiology has been disclosed in 44%. The most common causes were infection, cirrhosis and a myeloproliferative syndrome. The most common mode of presentation was gastrointestinal bleeding (44%). 12 patients (48%) died, the majority after life-threatening variceal bleeding. Today we restrict ourselves to treating the complications of portal hypertension. The aim for the future must be to diagnose and dissolve the thrombi shortly after formation.

Adolescent↗
PubMed1990

[Magnetic tomography and backache].

Magnetic resonance imaging (MRI) is a well documented method for diagnosis of spinal disease. We discuss the changes in the number of myelographies and spinal CT examinations carried out at our department after having had our own MRI unit for two years.

Back Pain↗
PubMed1990

Haemodynamic aspects of clinical cerebral angiography. Concurrent two vessel monitoring using transcranial Doppler ultrasound.

To overcome the technical limitations which have precluded noninvasive Doppler ultrasound in investigation of rapid cerebral haemodynamic responses in two cerebrovascular beds at the same time, we have modified a commercial 2 MHz pulsed Doppler instrument with online spectrum analysis. Two probes are activated intermittently, recording eight averaged Doppler-shifted spectra from each probe sequentially. Concurrent recordings of blood velocity in both middle cerebral arteries were performed during 25 selective iohexol carotid angiography runs in 13 patients with near normal cerebral vasculature. The technique permitted the differentiation between the specific responses confined to the recipient vascular bed, and the general responses occurring in remote brain areas as well. The specific response to iohexol was biphasic; a significant decrease in blood velocity occurred less than 4 s after the bolus entry, probably due to the high viscocity of iohexol. Between 4 and 12 s. blood velocity was significantly increased, reflecting the cerebrovascular response to hypertonic solutions. The blood velocity on the opposite side increased from less than 4 s through 45 s after iohexol. This concurs with studies using electromagnetic flowmetry, and suggests that these general responses are elicited by anxiety, discomfort and pain. Thus, no general responses were seen during angiography under general anaesthesia. Eight patients investigated during catheter flushing with normal saline showed a biphasic specific response reciprocal to that due to iohexol. A significant blood velocity peak occurred less than 4 s after the bolus entry, followed by a decrease between 4 and 60 s. The saline injections produced no pain and evoked no significant general response.

Adolescent↗
PubMed1990

Patency and flow velocity profiles in the internal carotid artery assessed by digital subtraction angiography and Doppler studies two years after endarterectomy.

A follow-up of 55 patients 2 years after a total of 60 carotid endarterectomies. Fifty-two patients who had a total of 57 endarterectomies survived the first 2 post-operative years and were re-examined using pulsed Doppler spectral analysis and intravenous digital subtraction angiography (IVDSA). One patient had died following a stroke and 2 after a cardiac infarction. The Doppler and IVDSA examinations revealed a non-symptomatic restenosis of the relevant internal carotid artery in 2 patients. There were no relevant occlusions and no symptomatic re-stenoses were detected. Spectral spreading of the Doppler signal at the site of the endarterectomy was found in 18% of the internal carotid arteries, whereas wall irregularities (diameter reduction less than 10%) were demonstrated in 25% by IVDSA. A stenosis or occlusion was found in 14 (25%) of the 57 ipsilateral external carotid arteries.

Blood Flow Velocity↗
PubMed1990

Hydrocephalus in an achondroplastic child treated by venous decompression at the jugular foramen. Case report.

A 10-month-old child with achondroplasia with progressive head enlargement, ventriculomegaly, and wide subarachnoid spaces over the hemispheres was referred for evaluation. A steady-state lumbar infusion test revealed increased cerebrospinal fluid (CSF) outflow resistance (14 mm Hg/ml/min), and intra-arterial digital subtraction angiography (DSA) demonstrated bilateral venous outflow obstruction due to stenosis of the jugular foramen. Surgical decompression by opening the right jugular foramen relieved the clinical signs of intracranial hypertension. During the following year, the patient's head enlargement was moderate with relative normalization of size. Repeat DSA demonstrated improved venous runoff on the right side, and a steady-state lumbar infusion test demonstrated reduced CSF outflow resistance (10 mm Hg/ml/min). Venous decompression is causal therapy and may prove to be preferable to shunting in children with hydrocephalus and bilateral stenosis of the jugular foramen.

Achondroplasia↗
PubMed1989

MRI in cervical disk herniation.

Eleven operated herniated disks in 10 patients were evaluated preoperatively with plain films, myelography and magnetic resonance imaging. Plain X-ray was a valuable supplement to MRI for studying the bony changes. Myelography showed 7 of 11 herniated disks while MRI gave correct diagnosis in all. It is concluded that MRI can replace myelography and computerized tomography in the preoperative evaluation of cervical herniated disk. The other examinations may be supplementary in some cases.

Adult↗
PubMed1989

Cerebral vasospasm diagnosis by means of angiography and blood velocity measurements.

We investigated 76 patients with known subarachnoid haemorrhage (SAH) in order to compare the results of angiography and non-invasive Doppler recordings of cerebral artery blood velocity in the diagnosis of cerebral vasospasm. One radiologist and one neurovascular surgeon assessed angiographic spasm visually on a four-level scale. The radiologist's ratings were the term of reference for the study. When there was angiographic spasm of the middle cerebral artery (MCA), the MCA blood velocity was higher and the blood velocity in the distal extracranical internal carotid artery (ICA) was lower than when MCA spasm was scored as absent. Analysis by Kappa statistics, a measure for the agreement between two independent judges with correction for random coincidence, revealed moderate agreement between angiographic spasm and the absolute MCA blood velocity (Kappa = 0.47). However, there was substantial agreement (Kappa = 0.64) between angiographic spasm and the index calculated from dividing the blood velocity in the MCA (VMCA) by the blood velocity in the ipsilateral ICA (VICA). The results indicate that this VMCA/VICA index gives more appropriate information on MCA spasm. Congenitally asymmetric circles of Willis with one wide dominant ACA showed normal blood velocities. In asymmetry induced by vasospasm, the diameter of the major ACA was normal or even reduced, and the blood velocity was significantly elevated. Hence, the agreement between blood velocity recordings and angiographic findings was substantial (Kappa = 0.64) when considering together the findings from both sides of the anterior circle of Willis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Regional cerebral blood flow (rCBF) and cerebral vasoreactivity in patients with retinal ischaemic symptoms.

Regional cerebral blood flow (rCBF) and cerebral vasoreactivity were assessed in 28 consecutive patients who presented with retinal ischaemic symptoms, without clinical or cerebral CT evidence of cerebral ischaemia. rCBF was measured using xenon-133 inhalation and single photon emission computed tomography before and 20 minutes after the intravenous administration of 1 g acetazolamide. The findings suggest that patients with retinal ischaemic symptoms alone due to carotid atherosclerosis often have a carotid lesion which is of haemodynamic significance with regard to cerebral perfusion and vasoreactivity. Furthermore, localized areas with reduced cerebral perfusion may also be present in some patients, without evidence of precerebral carotid occlusive disease.

Acetazolamide↗
PubMed1988

Cerebral vasospasm after subarachnoid haemorrhage investigated by means of transcranial Doppler ultrasound.

Measurements of flow velocity in defined segments of the basal cerebral arteries can be obtained through the intact adult skull using 2 MHz pulsed Doppler ultrasound. We compared flow velocity in these vessels with findings from 56 cerebral angiographies obtained in 51 patients at from day 1 to day 21 after subarachnoid haemorrhage (SAH). The diameter of the proximal segment of the middle cerebral, anterior cerebral, and posterior cerebral arteries (MCA, ACA, and PCA, respectively) were measured from anteroposterior films produced in one angiographic laboratory. In patients investigated on day 1-2, the median MCA diameter was 2.8 mm with range 2.3-3.4 mm. The median flow velocity was 56 cm/s, range 36-88 cm/s (within normal limits). There was a clear inverse relationship between the MCA diameter and MCA flow velocity. Eleven of the 13 MCA's having diameter 1.5 mm or less showed flow velocity in excess of 140 cm/s. This seems a useful limit to diagnose pronounced MCA spasm (50% diameter reduction) with this method. Further clues to the severity of MCA spasm were obtained from the ratio calculated dividing the MCA flow velocity by the flow velocity in the ipsilateral, extracranial internal carotid artery (ICA), since spasm probably does not involve the neck vessels. This ratio was from 1.1 to 2.3, median 1.7 at day 1-2, but rose to over 10 in patients with the most severe MCA lumen narrowing. The PCA flow velocity was inversely related to the PCA diameter. Assessment of ACA spasm requires considering findings from both hemispheres combined, since the two proximal ACA's usually anastomose through the anterior communicating artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Amaurosis fugax: clinical, Doppler and angiographic findings.

Clinical, Doppler and angiographic findings are described in 53 consecutive patients who presented with amaurosis fugax (AF) in a total of 57 eyes; 4 had non-simultaneous attacks in both eyes. Atherosclerotic lesions were detected on Doppler or angiographic (conventional arteriography and/or intravenous digital subtraction angiography) examination in 36 (63%) of the relevant precerebral internal carotid arteries (ICA) in 34 patients. Nineteen (53%) of these lesions caused a diameter reduction of more than 75%. Patient age was the most important factor in predicting the presence of relevant carotid occlusive disease, all 36 lesions being found in patients over 50 years of age. Two unusual cases of AF are described; in one AF was caused by stenosis of the ipsilateral ophthalmic artery, and in another by occlusion of the brachiocephalic artery with a steal syndrome from the right common carotid artery (CCA) to the right subclavian artery.

Adolescent↗