Effect of DiscoGel treatment of the intervertebral disc at MRI.

AIM: To determine the impact of ethanol gel chemonucleolysis (EGCh) on the radiological picture of the treated intervertebral disc, the relationship between the initial radiological status and the clinical status of the patient after EGCh treatment, and the optimal radiographic criteria for qualifying a patient for EGCh treatment. MATERIALS AND METHODS: The study involved a group of 45 patients (25 men and 20 women) aged 23-68 years (46 ± 11) who underwent an EGCh procedure after qualification, radiography, and clinical questionnaire evaluation. RESULTS: The results showed a decrease in the size of the protrusion and Gadolinium-Enhanced (GI) zone in the treated intervertebral disc. The presence of a high-intensity zone (HIZ) on baseline magnetic resonance imaging was found to be a good predictor of the timing and outcome of treatment, and an increase in disc height was observed in adjacent segments. CONCLUSION: These findings suggest that EGCh is a promising treatment for spine diseases, and the HIZ on baseline magnetic resonance imaging can be used as a qualification criterion for this procedure.

Uncertainty principle of signal-averaged electrocardiography.

BACKGROUND: Signal-averaged ECG (SAECG) reproducibility is reported to have a component that is independent of residual noise. Methods and Results-In group 1, multiple paired SAECGs were obtained to noise levels of 0.3+/-0.1 and 0.5+/-0.2 microV. For the 0.5- and 0. 3-microV noise recordings, QRS duration (QRSd) was 101.2+/-11.3 and 104.6+/-9.6 ms, respectively (P<0.0001), and the differences in paired QRSd (DeltaQRSd) were normally distributed, with variances of 11.4 and 26.2 ms(2) (P<0.0001). Paired SAECGs were obtained in group 2 patients without and with late potentials; DeltaQRSd variance was 3.3 and 217.9 ms(2) (P<0.0001). In group 3, >/=10 SAECGs were acquired at noise levels of 0.2 to 0.8 microV, in 0.1-microV increments. QRSd increased as noise level decreased. The variance was greater in low-noise (0.2 to 0.4 microV) versus higher-noise (0. 5 to 0.8 microV) recordings. In group 4, SAECGs were analyzed with bidirectional and Bispec filters, with no difference in QRSd between the 2 filters and a normally distributed DeltaQRSd. A computer simulation demonstrated that alterations in the phase relationship of noise to signal results in a normal distribution of signal end points. CONCLUSIONS: Within the acceptable noise range for SAECG, lower noise results in longer QRSd and larger variance, suggesting that more accurate recordings may have less reproducibility. The random timing of noise relative to signal results in the distribution/variance of repeated measurements. Statistical strategies may be used to reduce some of this variance and may enhance the diagnostic utility of SAECG.

The effect of vascular curvature on three-dimensional reconstruction of intravascular ultrasound images.

OBJECTIVE: To characterize the effect of vessel curvature on the geometric accuracy of conventional three-dimensional reconstruction (3DR) algorithms for intravascular ultrasound image data. BACKGROUND: A common method of 3DR for intravascular ultrasound image data involves geometric reassembly and volumetric interpolation of a spatially related sequence of tomographic cross sections generated by an ultrasound catheter withdrawn at a constant rate through a vascular segment of interest. The resulting 3DR is displayed as a straight segment, with inherent vascular curvature neglected. Most vascular structures, however, are not straight but curved to some degree. For this reason, vascular curvature may influence the accuracy of computer-generated 3DR. METHODS: We collected image data using three different intravascular ultrasound catheters (2.9 Fr, 4.3 Fr, 8.0 Fr) during a constant-rate pullback of 1 mm/sec through tubing of known diameter with imposed radii of curvature ranging from 2 to 10 cm. Image data were also collected from straight tubing. Image data were digitized at 1.0-mm intervals through a length of 25 mm. Two passes through each radius of curvature were performed with each intravascular ultrasound catheter. 3DR lumen volume for each radius of curvature was compared to that theoretically expected from a straight cylindrical segment. Differences between 3DR lumen volume of theoretical versus curved (actual) tubes were quantified as absolute percentage error and categorized as a function of curvature. Tubing deformation error was quantified by quantitative coronary angiography (QCA). RESULTS: Volumetric errors ranged from 1% to 35%, with an inverse relationship demonstrated between 3DR lumen volume and segmental radius of curvature. Higher curvatures (r < 6.0 cm) induced greater lumen volume error when compared to lower curvatures (r > 6.0 cm). This trend was exhibited for all three catheters and was shown to be independent of tubing deformation artifacts. QCA-determined percentage diameter stenosis indicated no deformation error as a function of curvature. Total volumetric error contributed by tubing deformation was estimated to be 0.05%. CONCLUSIONS: Catheter-dependent geometrical error arises in three-dimensionally reconstructed timed linear pullbacks of intravascular ultrasound images due in part to uniplanar vascular curvature. Three-dimensional reconstruction of timed linear pullbacks is robust for vessels with low radii of curvature; however, careful interpretation of three-dimensional reconstructions from timed linear pullbacks for higher radii of curvature is warranted. These data suggest that methods of spatially correct three-dimensional reconstruction of intravascular ultrasound images should be considered when more pronounced vascular curvature is present.