Chronic inflammatory disease of the male lower genito-urinary tract

The underlying aetiology and pathophysiology of chronic abacterial prostatitis is poorly understood. The study of patients with chronic prostatitis and normal controls by transrectal ultrasound identified seven signs associated with a diagnosis of chronic prostatitis. A cohort of sixty patients with chronic abacterial prostatitis (CABP), based on standard localisation criteria, was constructed. These patients underwent transrectal ultrasound and subsequent guided biopsy of any parenchymal abnormalities, thereby overcoming the problem of urethral contamination. The tissue so obtained was submitted for microbiological, histological and immunological study. Within the cohort no organism was isolated consistently from either prostatic secretion or tissue. In particular Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum could not be identified. A chronic inflammatory infiltrate was detected in 85% of the cohort, yet no controls, thereby vindicating the biopsy technique. However, no specific histological pattern could be attributed to CABP. Immunological analysis of the prostatic tissue suggested the inflammatory process was stimulated by a persistent antigen and was in keeping with a cell mediated, type IV hypersensitivity reaction. Urinary flow rates were subnormal in 27% of the cohort. In selected cases, intraprostatic urinary reflux was demonstrated, and postulated, as being responsible for the transportation of the inciting antigen, whose nature remains unknown, yet probably is non-organismal. Serum PSA was unhelpful in diagnosis and management of CABP. No evidence of a psychological role in the aetiology of CABP was identified. A possible link between acute epididymitis and inflammatory prostatic disease was noted on transrectal ultrasound; intraprostatic and vasal reflux being a proposed unifying factor. In acute epididymitis the role of Chlamydia trachomatis and Enterobacteriaceae was confirmed, and Ureaplasma urealyticum discovered. Thus CABP* appears to be an active immunological reaction in response to a persistent antigen whose nature, although unknown, is possibly non-organismal and transported into the prostate by urinary reflux

Segmentation of skin lesions in 2D and 3D ultrasound images using a spatially coherent generalized Rayleigh mixture model

This paper addresses the problem of jointly estimating the statistical distribution and segmenting lesions in multiple-tissue high-frequency skin ultrasound images. The distribution of multiple-tissue images is modeled as a spatially coherent finite mixture of heavy-tailed Rayleigh distributions. Spatial coherence inherent to biological tissues is modeled by enforcing local dependence between the mixture components. An original Bayesian algorithm combined with a Markov chain Monte Carlo method is then proposed to jointly estimate the mixture parameters and a label-vector associating each voxel to a tissue. More precisely, a hybrid Metropolis-within-Gibbs sampler is used to draw samples that are asymptotically distributed according to the posterior distribution of the Bayesian model. The Bayesian estimators of the model parameters are then computed from the generated samples. Simulation results are conducted on synthetic data to illustrate the performance of the proposed estimation strategy. The method is then successfully applied to the segmentation of in vivo skin tumors in high-frequency 2-D and 3-D ultrasound images

Toward quantitative limited-angle ultrasound reflection tomography to inform abdominal HIFU treatment planning

High-Intensity Focused Ultrasound (HIFU) is a treatment modality for solid cancers of the liver and pancreas which is non-invasive and free from many of the side-effects of radiotherapy and chemotherapy. The safety and efficacy of abdominal HIFU treatment is dependent on the ability to bring the therapeutic sound waves to a small focal ”lesion” of known and controllable location within the patient anatomy. To achieve this, pre-treatment planning typically includes a numerical simulation of the therapeutic ultrasound beam, in which anatomical compartment locations are derived from computed tomography or magnetic resonance images. In such planning simulations, acoustic properties such as density and speed-of-sound are assumed for the relevant tissues which are rarely, if ever, determined specifically for the patient. These properties are known to vary between patients and disease states of tissues, and to influence the intensity and location of the HIFU lesion. The subject of this thesis is the problem of non-invasive patient-specific measurement of acoustic tissue properties. The appropriate method, also, of establishing spatial correspondence between physical ultrasound transducers and modeled (imaged) anatomy via multimodal image reg-istration is also investigated; this is of relevance both to acoustic tissue property estimation and to the guidance of HIFU delivery itself. First, the principle of a method is demonstrated with which acoustic properties can be recovered for several tissues simultaneously using reflection ultrasound, given accurate knowledge of the physical locations of tissue compartments. Second, the method is developed to allow for some inaccuracy in this knowledge commensurate with the inaccuracy typical in abdominal multimodal image registration. Third, several current multimodal image registration techniques, and two novel modifications, are compared for accuracy and robustness. In conclusion, relevant acoustic tissue properties can, in principle, be estimated using reflected ultrasound data that could be acquired using diagnostic imaging transducers in a clinical setting

Pressure Wave Velocity Using High-Frame-Rate Ultrasound Imaging for Urodynamic Study

Benign Prostatic Hyperplasia (BPH) is a noncancerous urologic condition in aging males where an overgrowth of the prostate gland occurs. It notably leads to lower urinary tract symptoms ranging from inconvenient nocturia to severe damage of the bladder from blockage, infection, and bladder stones. High-frame-rate ultrasound (HiFRUS) has enabled significant advances in urology through visualization of high temporal urinary flow dynamics within the male urinary tract during voiding. Such work has shown that characteristic flow patterns for pathological states found within the diseased male urinary tract, such as urethral obstruction, can be used for non-invasive assessment. However, complementing urinary flow are pressure wave dynamics propagating locally along the urethral tissue wall that has not been studied before. Here HiFRUS is utilized again to visualize and study in-vitro these local dynamics for a new metric to assess the male urinary tract state called the pressure wave velocity (PreWV). This research presents the first investigation on how significant the initiation of voiding in the collapsed and tortuous geometry of the urinary tract, which is common to BPH, are on the regional and subregional PreWV response. A new tortuous flow phantom platform was devised to facilitate an in-vitro urodynamic study to collect PreWV data using HiFRUS and perform tissue Doppler analysis. To study the effect in changing the tortuous geometry, the male urinary tract is modelled by two deformable bent geometry phantoms, one with 30° bend and another with 45° bend. These phantoms were fabricated using a lost-core strategy protocol. To study the effect in changing the collapsed state, the phantoms were deflated and encased in a tissue mimicking slab where the opening of the collapsed lumen was controlled in a flow circuit setup. In this setup, initiation of voiding by a diseased patient was mimicked with a flow pump set at 15% duty cycle, 7 mL/s peak flow rate and 4 second period. HiFRUS imaging views near the inlet, at the bend, and near the outlet in each phantom were acquired through plane-wave imaging using a 192-channel linear array transducer connected to an ultrasound open research platform. Tissue Doppler analysis was employed on the beamformed frames to obtain the arrival times of the wall velocity at each lateral position in 0.1 mm lateral steps along the segmented phantom walls. Global PreWV results from this analysis were validated with the ground truth PreWV measured by pressure sensors that were connected to the inlet and outlet ports of the imaging setup. Regional and subregional PreWV results were validated through statistical analysis and agreed with theory regarding pressure wave propagation in human tissue. For both the 30° and 45° phantoms, no statistical significance was observed on the PreWV near the inlet and outlet when compared to the ground truth (p>0.14; N=11). The subregional PreWV after the bend site showed a relative decrease in PreWV of 44% and 58% for the 30° and 45° phantoms respectively when compared to the subregional PreWV before the bend (p<0.001; N=11). Furthermore, a noticeable difference in the bend regional PreWV was observed when comparing the 30° and 45° phantoms (p<0.001; N=11). It was found that a 15° increase in the phantom bend angle translated to 4 times increase in the difference between the subregional PreWV before and after the bend, thus highlighting the significance of the tortuous and collapsed geometry effects on the PreWV mapping. Overall, this work establishes PreWV as a novel metric to assess the urinary tract at sub-millisecond temporal resolution using HiFRUS and may serve as a complementary method to non-invasively distinguish pathological states due to BPH in future urodynamic studies