Comparison of two mechanical ultrasound devices with and without echogenic contrast dye.

To evaluate the impact and limitations of intracoronary ultrasound, 64 segments of 13 isolated coronary arteries were examined and 2 mechanical devices (device A, 30 MHz 5Fr [CVIS] and device B, 20 MHz 4.8Fr [Diasonics/Boston Scientific] were compared with the corresponding histologic specimens. Luminal dimensions were assessed with and without echogenic contrast dye (Laevovist, Schering AG, Germany). After application of contrast dye, correlation of luminal area between histology and ultrasound was improved from r = 0.62 to r = 0.77 (device B; p < 0.05) and from r = 0.82 to r = 0.88 (device A; p = NS). Low accuracy of lumen measurements in segments < 2.5 mm could be improved by application of contrast dye. The number of quadrants in which wall thickness measurements were impossible was significantly higher for device B (n = 56; 22%) than for device A (n = 28; 11%); p < 0.01. This may be due to the different ringdown diameters of both systems (B, 2.6 mm; A, 2.0 mm; p < 0.0001). In assessing wall thickness only in segments of > 2.5 mm, a reliable correlation between ultrasound and histology was found (A, r = 0.80; B, r = 0.60). Sensitivity of plaque (n = 51) detection was lower for device B (63%) than for device A (82%, p < 0.05), and measurements correlated with histology only for device A. There are considerable differences in the accuracy of ultrasound measurements between mechanical systems. Nevertheless, additional application of contrast dye can improve accuracy of luminal measurements, especially in smaller vessels.

Hemispheric asymmetry of feedback-related potentials in a positioning task: comparison of right- and left-handed subjects.

Previous research has demonstrated that delayed nonverbal information feedback (IF) about the correctness of a positioning movement is preceded by a contingent negative variation (CNV) which is larger over the right hemisphere independent of movement side. It was hypothesized that this asymmetry is a manifestation of functional hemispheric specialization, and that, therefore, the distribution of the differences between CNV amplitude measures of the two hemispheres should be different in right-handed and left-handed subjects. The latter group should show a mean asymmetry score closer to zero, and a larger between-subject variance of the asymmetry scores. The present investigation was intended to test these assumptions in samples of rigorously defined right-handers (n = 12) and left-handers (n = 8). The results revealed the expected group differences of the CNV asymmetry scores. In addition, the P1-N1 peak-to-peak amplitude of the IF-evoked potentials was similarly lateralized as the pre-IF CNV and showed the same group differences. In contrast, the handedness groups did not differ in the contralateral lateralization of the movement-related potential shift in the same task.

Somatosensory evoked potentials to mechanical disturbances of positioning movements in man: gating of middle-range components.

Somatosensory evoked potentials (SEPs) and EMG responses to mechanical disturbances of positioning movements of the index finger were recorded from normal subjects who performed smooth flexions against the constant load of a torque motor in order to reach a specified target zone. According to a random series 60% of the movements were disturbed by step increases or decreases of the load which subjects had to compensate for (movement condition, MC). As control procedures (a) the same stimuli were applied while the subject had to maintain a constant finger position against the same load (hold condition, HC), and (b) comparable mechanical stimuli were administered to the stationary relaxed finger (resting condition, RC). In MC and HC, the EMG responses consisted of a long-latency (53-61 msec) reflex component, and a 'voluntary' component (98-134 msec). In all 3 conditions, the sequential SEP deflections measured over the sensorimotor cortex included peaks P85 (ipsilateral), N150 (bilateral) and P220 (bilateral). A contralateral N90 component (onset latency 55-60 msec), present in HC and RC, was markedly reduced or absent in MC. Neither in the preceding nor in the consecutive SEP components were there any significant condition-dependent differences, though the N150 showed a trend to diminished amplitude in MC as well. The suppression of SEP components in MC is discussed in terms of efferent and afferent 'gating' actions exerted on the somatosensory input during movement.

In vitro assessment of luminal dimensions of coronary arteries by intravascular ultrasound with and without application of echogenic contrast dye.

To evaluate the impact and limitations of intracoronary ultrasound in the assessment of lumen, we examined 80 segments of 20 isolated coronary arteries with a mechanical ultrasound device (CVIS) comparing the results of ultrasound with the corresponding histological specimens. Ultrasound was performed with and without echogenic contrast dye (Laevovist, Schering AG, FRG). After application of contrast dye, correlation of luminal area between histology and ultrasound was improved from r = 0.85 to r = 0.89 (p = ns). Accuracy of lumen measurements was low in segments < 2.5 mm; only after application of contrast dye a relationship between ultrasound and histological measurements was found. In all cases in which a deviation of more than 20% between ultrasound and histology was observed, this deviation could be reduced by the application of contrast dye. There are considerable limitations in the accuracy of ultrasound measurements in the near field. Thus, further improvement of intracoronary ultrasound devices is mandatory. However, with the use of the currently available systems, additional application of echogenic contrast dye can improve accuracy of luminal measurements, especially in smaller size vessels.