Spectrum Analysis Of Echo Signals Research Articles

Ultrasonic tissue-type imaging of the prostate: Implications for biopsy and treatment guidance

Improved means of imaging prostate cancer would enable more-effective biopsy and treatment guidance and potentially would provide a reliable means of monitoring non-surgical therapy. Current, commonly used, conventional means of imaging the prostate do not reliably depict cancerous lesions, and as a result, biopsy needles are placed with respect to visible anatomic features of the gland, treatment tends to involve the entire gland, and monitoring of non-surgical therapy is based predominantly on blood PSA levels, and in many cases, periodic biopsies. Conventional transrectal ultrasound often is the imaging modality of choice for prostate biopsy and treatment procedures, but it offers no advantages in terms of reliably depicting cancerous regions of the gland. However, new methods of tissue-type imaging that are based on spectrum analysis of echo signals and that utilize artificial neural networks for classification offer promise of reliably distinguishing cancerous lesions from non-cancerous tissue in the prostate. The classifier produced an ROC-curve area of 0.84 for 617 biopsied locations compared to areas of 0.64 for conventional assessments of the same locations in biopsy-guidance B-mode images. The potential improvement in imaging sensitivity implied by the ROC curves is more than 50%. If current validation studies confirm these initial results, then an effective, inexpensive, noninvasive means of imaging prostate-cancer foci and therefore of guiding biopsies and treatments will be available to urologists and radiation oncologists.

Ultrasonic spectral-parameter imaging of the prostate

Spectrum analysis of the radiofrequency echo signals obtained from ultrasonically scanning the prostate may provide information capable of distinguishing cancerous from noncancerous tissue. In American men, prostate cancer is the highest-incidence cancer and the second-highest cancer killer. It is diagnosed using ultrasonically guided biopsies, which are limited by the low sensitivity and specificity of the guidance method. Spectrum analysis of the echo signals uses information that is discarded by conventional ultrasound imaging technology. The inclusion of this information shows differences between the ultrasound-scattering properties of cancerous and noncancerous prostate tissues. Spectrum analysis of ultrasonic echoes provides parameter values that can be related to scattering properties of tissue and can be compared to database parameter value ranges associated with cancerous and noncancerous tissues. Images can be generated to display parameter values, scatterer properties, or most likely tissue type. Results to date suggest that these differences may be sufficient to improve biopsy guidance significantly and therefore to improve the efficacy of biopsy-based diagnosis of prostate cancer. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 11–25, 1997