Development and validation of an in vivo analysis tool to identify changes in carotid plaque tissue types in serial 3-D ultrasound scans.

We have developed a three-dimensional (3-D) B-mode acquisition system suitable for imaging carotid plaques in vivo. A texture classification system using 157 statistical and textural algorithms, previously developed in our laboratory and shown to predict the contents of in vitro carotid plaques, was applied to in vivo 3-D image sets obtained from patients with both symptomatic and asymptomatic carotid artery plaques. Delineation of plaque boundaries is more difficult using in vivo images than in vitro images of excised plaques embedded in agar. This study has examined inter- and intraobserver variability studies to assess the degree of selectivity of the plaque region-of-interest (ROI) and assess the degree of repeatability for potential use in comparing serial scans. An interobserver limit of agreement of +/-12.9% and an intraobserver limit of repeatability of <2% were obtained. These results show that the plaque ROI selection is subjective, but is repeatable within acceptable limits.

Salivary gland tumours: is colour Doppler imaging of added value in their preoperative assessment?

Using a Toshiba SSA-270A Colour Duplex Scanner, 15 patients with suspected parotid and submandibular gland tumours had preoperative duplex scanning done. Peak systolic doppler shifts (fmax) were recorded and their vascularity was also subjectively scored. There were no arteries identified within the substance of contralateral normal glands. All recordings were analysed retrospectively and an independent histological assessment of tumours was made. Pleomorphic adenomas (n = 9) had a median peak systolic frequency (fmax) of 0.8 kHz, while adenolymphomas (n = 4) had a fmax of 1.65 and the two malignant tumours had fmax of 4.5 (P = 0.007 Kruskal-Wallis test). There appears to be a strong correlation between the fmax and the subjective vascular score (Corr 0.92). Colour duplex scanning is a non-invasive procedure which may be of help in the preoperative assessment of salivary gland tumours.

Temporal instabilities associated with a planar high purity germanium detector.

Experiments have been performed which show that a grooved planar high purity germanium semiconductor detector may give rise to time variant counting rates in energy regions below prominent spectral peaks. It is postulated that this effect is due to prolonged or incomplete charge collection in the vicinity of the bottom of the groove, and is caused by distortions in the applied electric field in this region. Such effects may lead to changes in the minimum detectable count rate in x-ray fluorescence measurements; these can be reduced by collimating incident photons on the central region of the detector but the resulting reduction in efficiency lowers the overall sensitivity.

Angiographic contrast media relax isolated rabbit aorta through an endothelium-independent mechanism that may not depend on the presence of the iodine atom.

Systemically administered iodinated angiographic contrast media evoke vasodilatation through mechanisms that are at present poorly understood. In the current investigation we have evaluated the role of the vascular endothelium in responses to an iso-osmolar formation of the non-ionic dimer iodixanol and a hyperosmolar formulation of the non-ionic monomer iopromide. Isolated rabbit aortic ring preparations with endothelium intact or removed by gentle abrasion were mounted in organ baths containing oxygenated Holman's solution, and cumulative concentration-response curves for relaxation to the contrast media were constructed after pre-constriction by phenylephrine (300 nM) in the presence of indomethacin to inhibit prostaglandin synthesis. Endothelial denudation did not influence the ability of either iodixanol or iopromide to relax the aortic ring preparations. Iopromide was significantly more potent than iodixanol when expressed in terms of iodine concentration (mg I ml-1), but both agents were equipotent when expressed in terms of molarity (mM). We conclude that relaxation of isolated rabbit aortic rings to iodixanol and iopromide under conditions where there is no fluid flow is endothelium-independent, and therefore not mediated by release of the potent endogeneous nitrovasodilator endothelium-derived relaxing factor (EDRF). Furthermore, their relaxant activity under the in vitro experimental conditions employed is attributable to a direct action on vascular smooth muscle by factors in addition to osmolality, and may depend on features that are not specifically associated with the presence of the iodine atom.

The haemodynamic effects of iodinated water soluble radiographic contrast media: a review.

All classes of iodinated water-soluble radiographic contrast media (RCM) are vasoactive with the iso-osmolar dimers inducing the least changes in the vascular tone. The mechanisms responsible for RCM-induced changes in the vascular tone are not fully understood and could be multifactorial. A direct effect on the vascular smooth muscle cells causing alterations in the ion exchanges across the cell membrane is thought to be an important factor in RCM-induced vasodilatation. The release of the endogenous vasoactive mediators adenosine and endothelin may also play a crucial role in the haemodynamic effects of RCM particularly in the kidney. In addition, the effects of RCM on blood rheology can cause a reduction in the blood flow in the microcirculation. The purpose of this review is to discuss the pathophysiology of the haemodynamic effects of RCM and to offer some insight into the biology of the endothelium and vascular smooth muscle cells as well as the pharmacology of the important vasoactive mediators endothelin and adenosine.

The effect of head rotation on the diameter of the internal jugular vein: implications for free tissue transfer.

PURPOSE: To determine the effects of medial (inwards) and lateral (outwards) rotation of the head on the transverse diameter of the internal jugular vein. MATERIAL: The original study sample included 26 patients. Duplex ultrasound was used to measure the transverse diameter of the internal jugular vein at a fixed point on either side of the neck. Measurements were taken with the head central (neutral position), rotated laterally and medially. RESULTS: Using Student's t-test we found that lateral rotation of the head produced a reduction in the mean of the transverse diameters of the left and right ipsilateral vein from 6.9 mm to 5.4 mm (p < 0.03) and 5.9 mm to 5.0 mm (p = 0.2173) respectively. One patient excluded from the study because of previous neck surgery showed complete occlusion of the ipsilateral internal jugular vein on lateral rotation of the head. CONCLUSION: There is a possibility that patency of the vein could be compromised if the head is turned laterally. This situation may arise immediately after surgery in the ventilated and paralysed patient when the head may be unsupported. It could be of particular importance if the vein has been used as a recipient vein for free tissue transfer.

Post-sternotomy internal mammary arteriovenous fistula.

Arteriovenous fistula from the mammary artery is a rare complication following cardiac surgery. The fistula usually develops within the first 2 weeks after surgery and is initially asymptomatic. Typically, a continuous machinery murmur is heard along the parasternal border of the chest wall. A patient with an arteriovenous fistula between the right internal mammary artery and mammary vein following a combined aortic valve and coronary bypass operation is described. A transthoracic colour Doppler scan led to the diagnosis of the fistula. Because of potential late complications endovascular embolisation of the fistula was successfully performed.

Stress reduction and preventing hypertension: preliminary support for a psychoneuroendocrine mechanism.

Our objective was to identify endocrine-related mechanisms capable of mediating preventive effects of stress reduction in hypertensive heart disease. Since beneficial effects of stress reduction accrue over time, this cross-sectional, descriptive study sought differences between healthy students not practicing a systematic technique for reducing stress (the average stress, or AS, group, n = 33) and a similar group who for 8.5 years had practiced the Transcendental Meditation (TM) technique, used widely to reduce stress (the low stress, or LS, group, n = 22). The two groups of students, matched for age and area of study, performed timed collections of urine that included (separately) the entire waking and sleeping portions of 1 day. They also completed the Profile of Mood States and the State-Trait Anxiety Inventory, self-report instruments sensitive to subjective level of stress. Urine samples were analyzed for adrenocortical steroids by radioimmunoassay, for Na+, K+, Mg2+, Ca2+, and Zn2+ by atomic absorption spectrometry, and for neurotransmitter metabolites by reverse-phase, high-performance, liquid chromatography, and spectrophotometry. The two groups differed significantly on most measures. Specifically, the LS group was lower in cortisol and aldosterone and higher in dehydroepiandrosterone sulfate (DS) and the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA). Excretion of sodium, calcium, zinc, and the norepinephrine metabolite, vanillylmandelic acid (VMA), was also lower in this group, as were Na+/K+ ratio, mood disturbance, and anxiety. In women practicing TM, cortisol correlated inversely and DS directly with number of months of TM practice. The results identify improvements in mood state, adrenocortical activity, and kidney function as probable factors in the preventive and treatment effects of stress reduction. Because suboptimal levels of these parameters result from chronic, subjective stress, the findings add mechanistic support to the contention that hypertensive heart disease is avoidable, even in modern industrialized societies.

Stress, steroids, and "ojas": neuroendocrine mechanisms and current promise of ancient approaches to disease prevention.

Recent research on causes of disease and aging has increasingly supported the importance of stress. One theory of the relationship between stress and disease is based on the concept of homeostasis, a term coined by Cannon over 50 years ago to signify those states and mechanisms responsible for the "staying power of the body". Bernard, Cannon, Selye and other leading researchers held that full, normal function of the self-regulating or homeostatic power of the body maintains the balanced, integrated condition we recognize as health. Failures in this capacity, such as those produced by frequent stressful experiences, can result in disease or death. Theories of health and disease surprisingly similar to this have existed since ancient times, and in widely different cultures. This review discusses both the fundamental elements of these theories and the current neuroendocrine research supporting their validity and immediate relevance. The connections between ancient and modern knowledge described herein were made possible largely by the work of Maharishi Mahesh Yogi, a scholar and teacher of the ancient vedic tradition of India. A key part of Ayurveda that has been obscure to modern science is the substance "ojas", which the classical texts say maintains balance of the physiology. In this article, specific steroids or steroid classes are proposed as likely candidates for both the "ordinary" and the "superior" types of ojas described in Ayurveda. Current evidence for the functions of these steroids, as well as their role in stress, disease and the maintenance of health, is reviewed. The knowledge of Ayurveda, as recently brought to light by Maharishi, includes methods for recovering and maintaining optimal function of steroidal systems. Such effects may help mediate the improvements in health and increased longevity attributed to Ayurveda and other ancient methods.

Abdominal aortic aneurysm detection by common femoral artery Doppler ultrasound waveform analysis.

The aim of this research was to determine the effects of abdominal aortic aneurysm (AAA) on blood flow patterns in the common femoral artery (CFA) and to determine the feasibility of detecting AAA by analysis of the CFA Doppler waveform. CFA Doppler waveforms were measured from 30 patients with AAA and 30 normal patients without significant atherosclerotic disease. On visual inspection of the CFA waveforms five features were noted, predominantly in the AAA group, as being different from a normal CFA waveform: (1) spectral broadening on the systolic down stroke; (2) transient velocity spikes on the systolic down stroke; (3) an irregular reverse flow pattern; (4) simultaneous forward and reverse flow; and (5) waveform elongation with the reverse flow component extending throughout diastole. Based on visual identification of these five features it was possible to predict AAA with 93% sensitivity and 70% specificity in patients without significant atherosclerotic disease.

Quantitative assessment of intra-vascular volume in human Achilles tendinopathy.

This study was to evaluate the clinical relevance of neo-vascularization using 3D power Doppler ultrasonography (PDU) in Achilles tendinopathy. A 53-year-old male with chronic mid-portion Achilles tendinopathy was investigated. Quantitative assessment was performed over a twenty four day period. The mean visual analog scale (VAS) score and Victorian Institute of Sports Assessment-Achilles (VISA-A) score were compared with the 3D PDU findings. The overall volume of the neo-vascularization dropped from 463 mm(3) to 117 mm(3) at the final scan. This coincided with considerable improvement in both VAS and VISA-A scores, from 8 to 0 and 2 to 92 respectively.

Are Doppler studies a useful method of assessing neovascularization in human Achilles tendinopathy? A systematic review and suggestions for optimizing machine settings.

Achilles tendinopathy describes a painful condition. The symptoms include localized swelling and tenderness, and the condition is often associated with altered tendon structure and neovascularization. Doppler ultrasound has been used in Achilles neovascularization and despite the lack of standardization and machine settings, recent research has demonstrated a potential relationship between pathology and the presence of neovascularization. This paper is a systematic review of the published studies which have used Doppler ultrasound in the assessment of Achilles neovascularization, and a prospective study to suggest a degree of optimization for future studies.

Power Doppler in the assessment of pelvic masses in a low risk group.

Discrimination between benign and malignant adnexal masses aids in optimising the management of women with pelvic tumours. A grading system incorporating grey-scale and power Doppler measurements might increase the accuracy of pre-operative assessment. The present study aimed to assess the sensitivity and specificity of a grading system including grey-scale and power Doppler findings. A total of 179 women who had undergone power Doppler Ultrasound for a pelvic mass between April 2001 and March 2003 were identified. Masses were surveyed by grey-scale and power Doppler and graded in relation to the estimated risk of malignancy. Clinicians were provided with the findings. The results were compared with the findings at surgery. A total of 74.3% were premenopausal. Some 94.4% (n = 169) had benign; 1.7% borderline and 3.9% malignant histology. A total of 69% underwent surgery. Specificity was 72.2 - 95.9%; sensitivity 55.6 - 88.9% and negative predictive value 97.6 - 99.2%. Power Doppler as an additional diagnostic aid may help the clinician in the management of pelvic masses. Further research is needed to clarify sensitivity and specificity.

Haemodynamic and rheological effects of contrast media: the role of viscosity and osmolality.

All currently available iodinated contrast media (CM) produce some form of haemodynamic or rheological change when injected. These effects are thought to be due primarily to the osmolality and viscosity of the CM. The new hexa-iodinated contrast agent Visipaque has the advantage of being iso-osmotic with blood at all clinically relevant concentrations, but is more viscous than the monomers at equivalent iodine concentrations. The purpose of this review is to discuss the relative importance of osmolality and viscosity in the clinical situation.

The effect of iodixanol, a new isotonic contrast agent, on femoral blood flow in man.

Both ionic and non-ionic contrast media (CM) injected intra-arterially produce peripheral vasodilatation and a sensation of heat or even pain. This effect has been considered to be predominantly related to the osmolality of the CM used. Iodixanol is a non-ionic dimeric CM which can be made isotonic with blood at iodine concentrations up to 400 mg/ml. To assess the degree of peripheral vasodilatation following aortic injection of iodixanol, the change in femoral artery blood flow has been assessed non-invasively. Dupex ultrasound flow-velocity records were taken from the contralateral femoral artery in 10 patients undergoing transfemoral aortography. Volume flow, mean velocity, pulsatility index and peak systolic velocity were continuously recorded before and up to 2 min after injection of 60 ml of iodixanol at an iodine concentration of 320 mg/ml (iodixanol 320). Transient changes consistent with vasodilatation were observed in all patients. The greatest changes were observed during the time period 18-24 s after injection. Volume flow, mean velocity and pulsatility index all changed significantly from baseline (mean changes of 80.6%, 73% and -42.7% respectively). Peak systolic velocity did not change significantly. Intra-arterial injections of isotonic iodixanol 320 produces a significant increase in femoral blood flow in man. Factors other than hypertonicity must therefore be implicated in the vasodilatory effect of contrast media.

Electromyography in anaesthesia. A comparison between two methods.

Two instruments measuring evoked compound muscle action potentials (EMG) produced by train of four stimulation of the ulnar nerve were compared. The neuromuscular transmission section of a Datex Anaesthesia and Brain Monitor (ABM), which utilises an integration technique to measure the EMG, and the Medelec MS6 , by which amplitude of the EMG was recorded and measured were attached to the same electrodes placed over adductor pollicis. Eight patients scheduled for surgery requiring non-depolarising neuromuscular blockade were studied. The changes in neuromuscular transmission measured by the two methods correlated well, with no statistically significant difference in results. The ABM provides a simple and accurate automatic measurement of evoked EMG for use in the study of neuromuscular transmission.

Myasthenia gravis and atracurium. A case report.

The degree, duration of and recovery from neuromuscular blockade induced by atracurium in a patient with myasthenia gravis were monitored and recorded using the evoked compound muscle action potentials (EMG). The anaesthetic and perioperative management were simplified by the use of this technique. The significance of the behaviour of atracurium is discussed.

Transvaginal color Doppler in the detection of external iliac vein thrombosis in pregnancy.

A case is described where transvaginal color Doppler was used to demonstrate upward external iliac vein extension of thrombus at 26 weeks' gestation. Normally, transabdominal color Doppler can visualize the iliac vessels, but in advanced pregnancy the uterus obstructs the view. This technique is useful in determining of there is a 'high' deep vein thrombosis in pregnancy, and may also prove useful in the obese patient.

Effects of iodinated contrast media on peripheral blood flow.

All types of clinically employed iodinated roentgen contrast media (CM) cause vasodilatation after i.a. and i.v. administration, regardless of precise molecular structure. It is now apparent, however, that at iodine concentrations which provide equivalent angiographic contrast, this is significantly less with newer hexa-iodinated dimers, such as iodixanol and iotrolan, than older generations of compounds. The cellular mechanisms that underly the vasodilator effects of CM still remain to be fully elucidated but may include a) effects attributable to hyperosmolality; b) stimulation of the release of endogenous vasoactive mediators; and c) direct relaxant effects upon vascular smooth muscle. This review will discuss the possible contributions of these mechanisms to the vasodilatation observed in the clinical situation.