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L Søndergaard

Publications and source records attributed to L Søndergaard.

43 records · Page 3Linked to original sources

Mitral and aortic valvular flow: quantification with MR phase mapping.

When magnetic resonance phase mapping is used to quantitate valvular blood flow, the presence of higher-order-motion terms may cause a loss of phase information. To overcome this problem, a sequence with reduced encoding for higher-order motion was used, achieved by decreasing the duration of the flow-encoding gradient to 2.2 msec. Tested on a flow phantom simulating a severe valvular stenosis, the sequence was found to be robust for higher-order motion within the clinical velocity range. In eight healthy volunteers, mitral and aortic volume flow rates and peak velocities were quantified by means of phase mapping and compared with results of the indicator-dilution technique and Doppler echocardiography, respectively. Statistically significant correlations were found between phase mapping and the other two techniques. Similar studies in patients with valvular disease indicate that phase mapping is also valid for pathologic conditions. Phase mapping may be used as a noninvasive clinical tool for flow quantification in heart valve disease.

Aortic Valve↗

Accuracy and precision of MR velocity mapping in measurement of stenotic cross-sectional area, flow rate, and pressure gradient.

Reliability of magnetic resonance (MR) velocity mapping to assess severity of stenosis was assessed in vitro. Steady flow at different flow rates through five stenoses with a central orifice area ranging from 17 to 176 mm2 was measured with velocity mapping performed perpendicular to the stenotic jet. Besides determination of the stenotic cross-sectional area and flow rate, the pressure gradient was calculated with the modified Bernoulli equation and compared with manometer measurements. Cross-sectional areas were measured with an accuracy of > or = 76%, a precision of > or = 91%, and an error of < or = 19 mm2. Flow rates had an accuracy of > or = 72%, a precision of > or = 94%, and an error of < or = 1.4 L/min. The modification of the Bernoulli equation limited its reliability to stenoses with areas of 35-113 mm2. Pressure gradients were calculated with an accuracy of > or = 80%, a precision of > or = 88%, and an error of < or = 15 mm Hg. The method was applied in a single patient with aortic stenosis and gave estimates that agreed with those obtained by heart catheterization.

Aortic Valve↗

In vivo quantification of the unidirectional influx constant for Gd-DTPA diffusion across the myocardial capillaries with MR imaging.

The authors present an in vivo method for measuring the unidirectional influx constant (Ki) for gadolinium diethylenetriaminepentaacetic acid (DTPA) diffusion across the capillary membrane in the human myocardium with magnetic resonance imaging. Ki is related to the extraction fraction (E) and the perfusion (F) by the equation Ki = E.F.Ki was obtained by using the longitudinal relaxation rate (R1) as a measure of the myocardial concentration of Gd-DTPA in the mathematical model for transcapillary transport across capillary membranes. Myocardial enhancement after Gd-DTPA injection was followed by using inversion-recovery Turbo-FLASH (fast low-angle shot) images obtained in real time. The results were comparable to those obtained from studies with positron emission tomography in humans and invasive studies in animals. A method for obtaining the input function noninvasively is also presented. Comparison with direct arterial blood sampling showed that the noninvasive input function may be even more accurate with regard to timing and curve shape than the invasive input function. The procedure may therefore prove useful in clinical studies.

Adult↗

Mental disorders in medical inpatients and the association to severity of illness, self-rated physical disability, and health perception.

In a study of 294 consecutive medical inpatients, the authors assessed a subsample of 157 patients for psychiatric diagnoses using an extensive semistructured interview, Schedules for Clinical Assessment in Neuropsychiatry (SCAN). Patients rated their health and physical functioning, and medical consultants assessed them for chronic and life-threatening diseases. A life-threatening condition increased odds for having a psychiatric diagnosis by 3.1 times (95% Confidence Interval (CI): 1.03-9.1), while a chronic medical disease had no such impact (OR=1.1; 95% CI: 0.5-2.3). In women, mental disorders were strongly associated with self-rated disability (OR=6.7; 95% CI: 1.6-27.8) and self-rated health (OR=9.4; 95% CI: 2.7-32.4). This association was absent in men (OR(disability)=0.7; 95% CI: 0.2-2.7; OR(health)=1.6; 95% CI: 0.6-4.7). Analyses included adjustment for age and gender.

Adult↗

Long distance running and osteoarthrosis.

In order to evaluate the effect of long-term, long distance running on the incidence of degenerative joint disease in the lower extremities, we examined the hips, knees, and ankles of 30 long distance runners who had been serious competitive runners in the early 1950s (at the age of 20 to 30 years). Of three runners who were no longer active, one had stopped running in the late 1970s because of osteoarthrosis of both the lower and upper extremity joints. The remaining 27 runners (90%) were still active, having run 20 to 40 km/week (12 to 24 miles/week) for a median of 40 years. Subjective, objective, and roentgenographic data were compared with the data for 27 nonrunning controls matched as to age, weight, height, and occupation. No differences in joint alignment, range of motion, or complaints of pain were found between runners and nonrunners. Roentgenographic examinations for cartilage thickness, grade of degeneration, and osteophytosis were also without significant differences between the two groups. Thus, our observations suggest that a lifetime of long distance running at mileage levels comparable to those of recreational runners today is not associated with premature osteoarthrosis in the joints of the lower extremities.

Aged↗