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Biomedical subjects

R B Klop

Publications and source records attributed to R B Klop.

6 recordsLinked to original sources
PubMed1993

Carotid bifurcation imaging: magnetic resonance angiography compared to conventional angiography and Doppler ultrasound.

PURPOSE: to evaluate the clinical usefulness of the two dimensional "Time of Flight" (2D TOF) Magnetic Resonance Angiography technique (MRA) in imaging the carotid bifurcation as compared to conventional angiography and pulsed and colour Doppler ultrasound. METHODS: in 19 patients with possible cerebrovascular disease and eight volunteers, contrast angiography was compared with MRA in 21 carotid bifurcations and with Doppler ultrasound in 23 bifurcations by two independent observers. In 19 bifurcations, all three techniques were available for comparison. Internal carotid arteries were graded normal/minimal disease, mild, moderate or severe stenosis, or occluded. RESULTS: overall agreement between contrast angiography and MRA existed in 62% for one observer and 76% for the other. When MRA and Doppler agreed, agreement between these two investigations and contrast angiography existed in 77-81%. The major problem with MRA was overestimation of moderately stenosed vessels; 50% of the vessels with a moderate stenosis on contrast angiography were judged severely stenosed on MRA. An occlusion was never mistaken for a stenosis by MRA. Evaluating the separate slices, acquired in the 2D TOF MRA investigation, appeared to be essential to avoid this mistake. CONCLUSION: at present 2D TOF MRA is not clinically useful for diagnosing the degree of carotid artery stenosis. MRA has a clear tendency to overestimate the degree of stenosis especially moderately severe stenoses. To date, there are no objective methods to correct for this mistake. Technical improvements may make MRA a better diagnostic tool in the future.

Adolescent↗
PubMed1992

Outcome of progression from carotid stenosis to occlusion.

The incidence of symptoms at the moment the internal carotid artery (ICA) occludes was assessed in 33 patients. Duplex scanning was performed to determine the progression from stenosis to ICA occlusion. There were 24 patients with a primary stenosis and nine with a restenosis after a carotid endarterectomy. In 18% (6/33) the occlusion was accompanied by a stroke. A transient ischaemic attack (TIA) was seen in 12% (4/33) of patients and 70% (23/33) remained asymptomatic. There was no difference in stroke rate between patients with primary stenosis (4/24:17%) and those with restenosis (2/9:22%). The mean follow-up was 3.2 years and the mean elapse time to occlusion in patients with a stroke was 20 months, with a TIA, 32 months, and in asymptomatic patients, 44 months. It was also shown that a stenosis of greater than 80% diameter reduction had a faster progression (mean 1 year) than a less than 80% stenosis (mean 3.5 years) (p = 0.04). Patients with a stenosis greater than 80% tended to have a higher incidence (40%:2/5) of stroke at the time of occlusion than patients with a stenosis less than 80% (14%:2/28). The results show that an occlusion of the ICA is accompanied by a stroke in 18% of the cases and that patients with a rapid progression and/or greater than 80% stenosis are at high risk. From this point of view a carotid endarterectomy should be considered in order to prevent an occlusion of the ICA and a high risk of stroke.

Aged↗
PubMed1991

Screening of the internal carotid arteries in patients with peripheral vascular disease by colour-flow duplex scanning.

The prevalence of internal carotid arterial disease was assessed in 416 consecutive patients with peripheral arterial disease (PAD). Colour-flow duplex scanning was performed to determine the extent of the disease. Major internal carotid artery disease (MICAD), meaning 75% stenosis and/or occlusion, was found in 14.9% (62) of the patients; 12.5% (52) had unilateral disease and 2.4% (10) had bilateral disease. In 7.7% (32) there was a stenosis of 75-99%. An occlusion was seen in 7.2% (30). No correlation was found between the severity of the internal carotid artery disease and the severity of the peripheral arterial disease. The 16.0% (60) prevalence in MICAD in patients with obstructive disease was significantly higher than the 4.7% (2) in aneurysm patients (p less than 0.05). The results show that there was no correlation between MICAD and the risk factors: hypertension, gender, age, diabetes mellitus, hypercholestolaemia, smoking and ischaemic heart disease. The high prevalence of MICAD in patients with PAD suggests that it would be useful to start a screening programme to determine if high grade stenosis should be operated upon.

Aged↗