PubMed · 6873963
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A Cohen, D Landsberg. 1983. Adaptive real-time wavelet detection.. https://doi.org/10.1109/tbme.1983.325133
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OBJECTIVES: In situ extracorporeal lithotripsy (EL) is the treatment of choice for ureteral lithiasis at our institution since the introduction of the painless lithotripters in clinical practice. The major objections to such clinical approach are: difficult ultrasound localization of ureteral calculi (if an ultrasound-guided lithotripter is used); lower energy of the painless piezoelectric compared to the spark gap system. To evaluate the efficacy of in situ EL of ureteral stones and to compare two different lithotripters (the spark gap fluoroscopically-guided Dornier HM3 versus the piezoelectric ultrasound-guided Wolf Piezolith 2300), we conducted a prospective randomized study. METHODS: 70 patients were randomly divided into two groups according to the following inclusion criteria: radiopaque stones of lumbar or prevesical tract (iliac and pelvic stones were excluded); stones with largest diameter not more than 2 cm. RESULTS AND CONCLUSION: The evaluation of the treatment was done by plain film (KUB) at 24 and 72 hrs and by ultrasound at 48 hrs to assess stone fragmentation using migration of the fragments more distally into the ureter as criteria for success. The results were comparable: 76.6% for extracorporeal piezoelectric lithotripsy (EPL) and 74% for extracorporeal shock wave lithotripsy (ESWL). Better results were observed in both groups for the prevesical stones. The focussing time required was also comparable.
A new implementation of the surface Laplacian derivation (SLD) method is described which reconstructs a realistically shaped, local scalp surface geometry using measured electrode positions, generates a local spectral-interpolated potential distribution function, and estimates the surface Laplacian values through a local planar parametric space using a stable numerical method combining Taylor expansions with the least-squares technique. The implementation is modified for efficient repeated SLD operations on a time series. Examples are shown of applications to evoked potential data. The resolving power of the SLD is examined as a function of the spatial signal-to-noise (SNR) ratio. The analysis suggests that the Laplacian is effective when the spatial SNR is greater than 3. It is shown that spatial low-pass filtering with a Gaussian filter can be used to reduce the effect of noise and recover useful signal if the noise is spatially incoherent.