Sequential Registration-Based Segmentation of the Prostate Gland in MR Image Volumes.

Accurate and fast segmentation and volume estimation of the prostate gland in magnetic resonance (MR) images are necessary steps in the diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semi-automated segmentation of individual slices in T2-weighted MR image sequences. The proposed sequential registration-based segmentation (SRS) algorithm, which was inspired by the clinical workflow during medical image contouring, relies on inter-slice image registration and user interaction/correction to segment the prostate gland without the use of an anatomical atlas.

Inter-slice bidirectional registration-based segmentation of the prostate gland in MR and CT image sequences.

Purpose: Accurate segmentation and volume estimation of the prostate gland in magnetic resonance (MR) and computed tomography (CT) images are necessary steps in diagnosis, treatment, and monitoring of prostate cancer. This paper presents an algorithm for the prostate gland volume estimation based on the semiautomated segmentation of individual slices in T2-weighted MR and CT image sequences.

Methods: The proposed Inter-Slice Bidirectional Registration-based Segmentation (iBRS) algorithm relies on interslice image registration of volume data to segment the prostate gland without the use of an anatomical atlas.

Baroreflex mechanisms regulating the occurrence of neural spikes in human muscle sympathetic nerve activity.

This study tested the hypothesis that the discharge patterns of action potentials (APs) within bursts of postganglionic muscle sympathetic nerve activity (MSNA) are subject to arterial baroreflex control but in a manner that varies inversely with AP size. MSNA data were collected over 5 min of supine rest in 15 young and healthy individuals (8 males; 24 ± 4 yr of age; means ± SD). The baroreflex threshold and sensitivity diagrams were constructed for both the integrated sympathetic bursts and for the AP clusters.

Sympathetic neural recruitment patterns during the Valsalva maneuver.

Sympathetic nerve activity is an important regulator of blood pressure and blood flow in humans. Our understanding about how sympathetic neurons are recruited during baroreflex stress is limited. This paper investigates the sympathetic neural recruitment patterns during the Valsalva maneuver.

Recruitment pattern of sympathetic neurons during breath-holding at different lung volumes in apnea divers and controls.

We tested the hypothesis that breath-hold divers (BHD) attain higher level of sympathetic activation than controls due to the duration of breath-hold rather than a different recruitment strategy. In 6 control subjects and 8 BHD we measured muscle sympathetic neural activity (MSNA) prior to and during functional residual capacity (FRC) and total lung capacity (TLC) breath-holding. On a subset of subjects we applied a new technique for the detection of action potentials (APs) in multiunit MSNA.

Relationship between size and latency of action potentials in human muscle sympathetic nerve activity.

We employed a novel action potential detection and classification technique to study the relationship between the recruitment of sympathetic action potentials (i.e., neurons) and the size of integrated sympathetic bursts in human muscle sympathetic nerve activity (MSNA).

Sympathetic neural activation: an ordered affair.

Is there an ordered pattern in the recruitment of postganglionic sympathetic neurones? Using new multi-unit action potential detection and analysis techniques we sought to determine whether the activation of sympathetic vasomotor neurones during stress is governed by the size principle of recruitment. Multi-unit postganglionic sympathetic activity (fibular nerve) was collected from five male subjects at rest and during periods of elevated sympathetic stress (end-inspiratory apnoeas; 178 ± 37 s(mean ± S.D.

Spike detection in human muscle sympathetic nerve activity using a matched wavelet approach.

Sympathetic nerve recordings associated with blood pressure regulation can be recorded directly using microneurography. A general characteristic of this signal is spontaneous burst activity of spikes (action potentials) separated by silent periods against a background of considerable Gaussian noise. During measurement with electrodes, the raw muscle sympathetic nerve activity (MSNA) signal is amplified, band-pass filtered, rectified and integrated.

Performance analysis of stationary and discrete wavelet transform for action potential detection from sympathetic nerve recordings in humans.

Accurate investigation of the sympathetic nervous system is important in the diagnosis and study of various autonomic and cardiovascular control and disorders. Sympathetic function associated with blood pressure regulation in humans can be evaluated by recording muscle sympathetic nerve activity (MSNA), which is characterised by synchronous neuronal discharges separated by periods of neural silence dominated by colored gaussian noise. In this paper two common methods for detecting filtered action potential in MSNA recordings is compared.

Detection and classification of raw action potential patterns in human Muscle Sympathetic Nerve Activity.

The Muscle Sympathetic Nerve Activity (MSNA) consists of synchronous neural discharges separated by periods of neural silence dominated by heavy background noise. During measurement with electrodes, the raw MSNA signal is amplified, band-pass filtered, rectified and integrated. This integration process removes much neurophysiological information.