Biomedical subjects

Andrew K W Wood

Publications and source records attributed to Andrew K W Wood.

5 recordsLinked to original sources

PubMed2006

Histopathological observations of the antivascular effects of physiotherapy ultrasound on a murine neoplasm.

This study evaluates the histopathological changes that follow insonation of a neoplasm with physiotherapy ultrasound. In 27 mice (C3HV/HeN strain), a subcutaneous melanoma (K1735(22)) was insonated with continuous physiotherapy ultrasound (1 MHz; spatial-average-temporal-average = 2.3 W cm(-2)). Analyses of contrast enhanced (0.1 mL Optison) power Doppler observations showed that insonation significantly (p < 0.05) increased the avascular area in the neoplasm. The predominant acute effect of insonating the neoplasm was an apparently irreparable dilation of the tumor capillaries with associated intercellular oedema; other immediate effects were haemorrage and increased intercellular fluid. Liquefactive necrosis of neoplastic cells was a delayed effect. There was a high correlation (R2 = 0.91) between the percent area affected on histologic examination and the percent increase in avascularity of the neoplasm in the Doppler study. In conclusion, physiotherapy ultrasound produced histologic changes in the tumor vasculature that were consistent with observations made by contrast enhanced power Doppler ultrasound.

Albumins↗

PubMed2005

Gadodiamide T1 relaxivity in brain tissue in vivo is lower than in saline.

In vivo measurements of gadodiamide (Gd-DTPA-BMA) T(1) relaxivity were performed at 4.7 T in injured and normal rat brains. Cerebral lesions were induced in nine rats by a localized freezing method. T(1) maps of the lesions were generated before and after injection of Gd-DTPA-BMA (0.1-0.6 mmol/kg). Samples of normal and necrotic brain were collected postmortem; the wet and dry weights were determined, and Gd content was measured by inductively coupled plasma mass spectroscopy. The in vivo relaxivity was determined by a linear fit of a plot of the change in relaxation rate following injection of the contrast agent as a function of Gd content. This analysis yielded a relaxivity in the injured brain of 2.8 sec(-1) mmol(-1) kg tissue water at 36 degrees C. The water weight fraction was 0.90 +/- SD 0.02 wt/wt in injured brain and 0.79 +/- 0.02 in normal brain. Relaxivity measurements were also performed on solutions of Gd-DTPA-BMA (0.0-0.6 mmol) and albumin (0-30% wt/wt) in normal saline at room and physiologic temperatures. The relaxivity in the albumin/saline increased with increasing solids content with values of 4.0-4.9 sec(-1) mmol(-1)kg at 21 degrees C and 3.4-4.5 sec(-1) mmol(-1) kg at 37 degrees C. The relaxivity of the tissues differed significantly from that of the saline solutions of comparable solids content, suggesting that the solids content of a tissue is not the only factor that determines in vivo relaxivity.

Animals↗

PubMed2005

The antivascular action of physiotherapy ultrasound on murine tumors.

This study was aimed at determining if physiotherapy ultrasound (US) affected the fragile and leaky angiogenic blood vessels in a tumor. In 22 C3HV/HeN mice, a subcutaneous melanoma (K1735(22)) was insonated (1, 2 or 3 min) with continuous 1-MHz low-intensity (spatial-average temporal-average = 2.28 W cm(-2)), physiotherapy US. Contrast-enhanced (0.1 mL Optison) power Doppler US observations were made and histogram analyses of the images were performed. Before insonation, all but 7% of the tumor was perfused. The avascular area in tumors receiving 3-min treatment increased to 82% (p < 0.001). A linear regression analysis showed that each min of insonation led to a 25% reduction in tumor vascularity; the antivascular activity persisted for 24 h. Histology demonstrated disruption of vascular walls and tumor cell death in areas of vascular congestion and thrombosis. Physiotherapy US particularly targeted the vascular structures, and the effects on tumor cells appeared to be secondary to the resultant ischemia.

Albumins↗

PubMed2004

A novel method for analysis of TOMROP data.

PURPOSE: To develop an efficient method for extracting maps of the corrected T1 from images generated using the T One by Multiple Read Out Pulses (TOMROP) sequence. MATERIALS AND METHODS: An expression is developed for the true T1 in terms of the parameters from a three-parameter fit of the TOMROP data. Solutions of gadodiamide in normal saline with concentrations of 0.0, 0.06, 0.11, 0.23, 0.46, and 0.91 mM were prepared and T1 measurements were performed using both the inversion recovery (IR) and the TOMROP methods. The TOMROP data were analyzed using the proposed technique and the results compared to those from the IR measurements. RESULTS: The T1 estimates generated from the TOMROP data using the proposed method were consistent with the IR results. However, systematic errors were observed in the T1 estimates when the repetition time was not sufficient for full recovery of axial magnetization. Relaxation times determined using the proposed method were within 1% of the spectroscopiclly determined values for T1 values in the range of 0.28-2.8 seconds when a suitable delay was employed. CONCLUSION: The proposed method of analysis was found to yield accurate T1 estimates when the assumptions used in the analysis were not violated.

Contrast Media↗

PubMed2003

Correlation of ultrasonographic observations with anatomic features and radiography of the elbow joint in dogs.

OBJECTIVE: To define the ultrasonographic appearance of the elbow joint of dogs and to develop an ultrasonographic imaging protocol to reliably accomplish complete evaluation of that joint. ANIMALS: 11 clinically normal mixed-breed dogs. PROCEDURE: Ultrasonographic observations (by use of a 5 to 10 MHz linear array probe) were made of 22 elbow joints in cadaveric forelimbs from clinically normal dogs. Images in standard anatomic planes were recorded with a multi-image camera, on videotape, or onto a computer. The anatomic plane of the ultrasonographic beam and position of the ultrasonographic probe were also recorded. Dissection of each elbow joint was performed, and anatomic features were correlated with ultrasonographic images. RESULTS: Structures clearly identified ultrasonographically included the lateral and medial humeral epicondyles, the humeroradial and humeroulnar joints, anconeal process, medial coronoid process, hyaline cartilage covering the proximal articular surface of the radius, collateral ligaments, tendons of triceps brachii and supinator muscles, and the supinator tendon and sesamoid in the supinator cartilage. An ultrasonographic imaging protocol for examination of the elbow joint was developed. CONCLUSIONS AND CLINICAL RELEVANCE: Precise correlations were established between the gross anatomic appearance of the elbow joint and the ultrasonographic images of its component structures. The ultrasonographic imaging protocol will enable complete examination of all regions of the joint for detection of pathologic lesions.

Animals↗