Biomedical subjects

L Søndergaard

Publications and source records attributed to L Søndergaard.

6 recordsLinked to original sources

PubMed1992

Quantification of complex flow using MR phase imaging--a study of parameters influencing the phase/velocity relation.

In this study, we describe how motion-induced phase angle is affected by different flow models and imaging parameters when using the MR flow phase mapping technique. In a phantom with straight as well as constricted tubes, simulating healthy and stenotic vessels, nonpulsatile flow in the velocity range 0-1 m/sec was maintained. The phase/velocity relation was studied for various degrees of complex flow caused by the constriction, and regions with a breakdown in linearity were determined. Further studies in these regions were made regarding the influence of pulse sequence parameters on the phase/velocity relation. The results showed that in poststenotic areas characterized by so-called separated flow, the phase/velocity relation became nonlinear due to dephasing effects. In regions with fully developed turbulent flow in straight tubes, however, no breakdown in linearity was observed. Parameters seen to have a substantial influence on the phase/velocity relation were first- and second-order velocity encoding and voxel size. Finally, a pilot in vivo demonstration of complex flow was done using a sequence designed to be robust with respect to linearity of the phase/velocity relation. The results indicate that the MR phase mapping technique can be used to measure flow quantitatively in regions with complex flow. This opens possibilities for future clinical use of the technique in the study of areas of complex flow such as valvular heart disease.

Aortic Valve Stenosis↗

PubMed1991

Long-term follow-up of the cemented Caffinière prosthesis for trapezio-metacarpal arthroplasty.

20 patients with 22 Caffinière prostheses in the trapezio-metacarpal joint were evaluated at a median of nine years after operation. The indication was degenerative osteoarthrosis in 20 cases and rheumatoid arthritis in two cases. We found 18 of the 22 (82%) original prostheses still in place, with satisfactory pain relief and good function. Three hands had been revised due to aseptic loosening, with replacement of two cups and one total prosthesis. Two of the revised prostheses were functioning well 6 1/2 and 10 years after the revision. We conclude that function does not deteriorate within the first nine years, that late loosening is not a significant problem with this prosthesis and that, if aseptic loosening occurs, it is possible to obtain good results by replacing the loose component.

Aged↗

PubMed1991

Early mobilizing treatment for grade III ankle ligament injuries.

Eighty patients with grade III lateral ligament ruptures were treated either with total immobilization in a walking plaster cast or early mobilization in a stabilizing orthosis. The criterion for entrance was a talar tilt of more than 9 degrees and an anterior translation of more than 10 mm at stress radiography, a previously stable ankle, and a contralateral ankle showing normal stress radiographic values. Ninety-one percent of the patients were evaluated at 7 weeks, 3 months, and 1 year postinjury. While functionally treated patients reached normal mobility and resumed work and sports earlier than immobilized patients there were no differences between the treatment groups in ankle stability or symptoms during activity after 1 year. Ninety-five percent of the ankles in either group were mechanically stable after treatment. Residual symptoms were present 1 year postinjury in 13% of the functionally treated ankles and in 9% of the cast-mobilized ankles. In lateral ankle ligament ruptures causing gross mechanical instability early mobilization results in a better early functional result; however, at 1 year postinjury there was no statistically significant difference in outcome as compared to cast-immobilized ankles.

Adolescent↗

PubMed1990

[Arthrosis of the lower limb and running].

In order to assess whether running training for many years predisposes to arthrosis in the lower limbs, the hips, knees and ankle joints of 30 runners who began running training at the beginning of the nineteen fifties were examined. Three of these runners were no longer active. One of these had given up late in the nineteen seventies on account of arthroses in the upper and lower limbs i.e. changes which can scarecely be attributed to the stresses of running. The remaining 27 (90%) had run 20-40 km/week throughout 40 years. Subjective, objective and radiological data were compared with data from 27 non-active control persons who were comparable as regards age, weight/height and occupational stress with the runners. We found no differences in joint mobility, axial deviations or complaints of pain between the two groups. Radiologically, the distances between the osseous joint surfaces in the hip and ankle joints and the degrees of degeneration in the knees were assessed according to Ahlback's classification without any differences being found between the groups. Our results suggest that running training to a moderate extent for many years does not predispose to arthrosis in the lower limbs in healthy individuals.

Adult↗

PubMedDate not supplied

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↗

PubMedDate not supplied

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↗