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M Blomley

Publications and source records attributed to M Blomley.

At least 19 recordsLinked to original sources
PubMed2004

Liver tumors: evaluation with contrast-enhanced ultrasound.

The development and clinical introduction of microbubble contrast agents has had a particular impact on the detection and differential diagnosis of liver tumors. The first approach widely employed made use of high-transmission power ultrasound, which destroyed the microbubbles in the process of imaging them. It is particularly successful for those agents that have a liver-specific post-vascular phase because, like liver-specific agents used in other imaging modalities such as magnetic resonance imaging and nuclear medicine, malignancies do not retain the contrast, so they stand out with very high conspicuity. Used this way with color Doppler or variants of it, more subcentimeter lesions can be demonstrated with ultrasound than with computed tomography. However, the destructive nature of this approach meant that continuous real-time scanning was impossible. Two developments allowed this to be redressed: new classes of microbubbles with perfluoro gasses instead of air and the invention of multipulse scanning modes that are sensitive to the nonlinear (harmonic) responses of the microbubbles and suppresses tissue signals. This low-power approach is now used almost exclusively, and it has the advantage of displaying the arterial phase of blood supply to a mass and a later phase when the bubbles are trapped in the sinusoids so that the vascular volume of the tissue is depicted. Malignancies typically show a low signal intensity in this phase, regardless of whether they are hyper- or hypovascular in terms of their arterial supply. This allows them to be detected with high sensitivity and much more easily than the destructive modes allowed. In addition, the arterial supply that can be now depicted in real time has characteristics that allow most benign masses to be distinguished from each other and from malignancies, thus improving specificity. Microbubbles also can be used as tracers to provide functional information that can detect occult metastases and cirrhosis noninvasively.

Acoustics↗
PubMed2002

Multi-centre clinical study evaluating the efficacy of SonoVue (BR1), a new ultrasound contrast agent in Doppler investigation of focal hepatic lesions.

OBJECTIVES: SonoVue is a new ultrasound contrast agent, which consists of stabilised microbubbles of a sulphur hexafluoride gas. The aim of the study was to assess its efficacy in the Doppler investigation of focal hepatic lesions. MATERIALS AND METHODS: Seventy patients with focal liver tumours were studied. Four doses (0.3, 0.6, 1.2 and 2.4 ml) of SonoVue were administered intravenously with at least 10 min delay between each injection. A complete colour/power and spectral Doppler imaging investigation of the lesions was performed at baseline pre-dosing and after each SonoVue injection. All examinations were recorded on SVHS videotapes. Baseline and post contrast videotapes were reviewed by the on-site (un-blinded) investigators and by two off-site blinded readers (a) to grade the global quality of the Doppler scans of the focal lesions vascularity and the normal parenchymal vessels (b) to measure the duration of clinically useful Doppler signal enhancement and (c) to determine the diagnostic accuracy and performance of the enhanced versus unenhanced scans using histopathology, tumour markers, CT and/or MR as the reference standard. RESULTS: A statistically significant improvement was observed at all four SonoVue doses in the off site assessment of global quality of the Doppler examination of tumoral and normal parenchymal vessels in comparison with the baseline (P < 0.05). The median duration of clinically useful enhancement was significantly increased with increasing doses (P < 0.001), ranging between 1.4-2.2 min for the lowest dose and 3.2-3.8 min for the highest dose for the off-site readers. On-site assessment of diagnostic accuracy showed a significant increase in the specificity of the Doppler diagnoses (P < 0.0016) with an increase in the positive and negative predictive values and in the likelihood ratio in differentiating between benign and malignant lesions. Off-site evaluation showed a significant increase in the accuracy of enhanced Doppler diagnosis in comparison with the baseline performance. CONCLUSION: The results suggest that SonoVue is effective in improving the display of tumoral vascularisation and may be useful in the characterisation of focal liver lesions.

Contrast Media↗
PubMed2001

Measuring changes in human tumour vasculature in response to therapy using functional imaging techniques.

Antiangiogenic and antivascular agents provide new approaches to treating tumours. These may avoid many of the problems experienced with current approaches such as inherent and acquired resistance to treatment. Tumours do not grow beyond 1-2 mm(3) in size without the development of new vessels (Folkman, 1971). Such neo-vascularization (angiogenesis) allows tumour cells to increase their nutrient supply, survive and proliferate despite the new vessels often having structural and functional differences compared to normal tissue vasculature. Treatments targeted at tumour vasculature have produced impressive results in animal models (Lindsay et al, 1996; Watson et al, 1996; O'Reilly, 1997; Horsman et al, 1998). These therapies are now entering clinical trials. However, the successful introduction of these therapies into clinical practice will require the development of reliable ways to assess angiogenesis and its modification or inhibition in vivo. Here we discuss some of the emerging imaging techniques that may be useful.

Diagnostic Imaging↗
PubMed2001

Quantification of blood flow.

Traditionally, Doppler ultrasound has been used to estimate blood flow as the mean velocity multiplied by the vessel area, but this is subject to significant errors and may be difficult to perform accurately. Microbubbles, developed as contrast agents for ultrasound, were initially envisaged as useful for increasing the intensity of echoes and thus rescuing Doppler studies that were technical failures because of attenuated signals or very slow flow. However, they can act as tracers and, by analogy with isotope techniques, can be used to measure blood flow with transit-time methods which exploit both arterial and venous time-intensity data. An acceptable compromise is to acquire both a tissue intensity curve and one from the feeding artery. The transit of microbubbles across an organ or tissue can be used to estimate haemodynamic alterations, e.g. the arterialisation of the supply to the liver in malignancies and cirrhosis and the delayed arterio-venous transit in the transplant kidney during rejection. The fragility of microbubbles can be turned to advantage by being exploited to create a negative bolus by exposing a tissue slice to a high power beam. The rate of refilling of this slice by circulating microbubbles can then be followed with a low-intensity monitoring beam and the resulting rising exponential curve analysed to extract indices of both the reperfusion rate (the slope) and the fractional vascular volume (the asymptote). The product of these is a measure of true tissue perfusion.

Blood Flow Velocity↗
PubMed1999

Liver-specific imaging with SHU 563A: diagnostic potential of a new class of ultrasound contrast media.

The purpose of this study was to evaluate the imaging properties and diagnostic potential of the novel polymeric ultrasound contrast agent SHU 563 A. After i. v. injection, the agent circulates in the blood pool for about 10 min and is then subsequently sequestered by the RES cells predominantly in the liver. The acoustic emission capabilities enable a very sensitive detection during the blood pool phase and after uptake in the RES cells, contributing to differential diagnosis as well as detection of liver lesions. During a multicenter study, 28 patients with liver lesions were examined. In all patients the results were compared to baseline ultrasound and Contrast enhanced Spiral CT. With respect to lesion size and location, very good agreement between SHU 563 A ultrasound and Spiral CT was achieved. Additional lesions could be shown in the RES phase by SHU 563 A enhanced ultrasound. 26 further patients were examined in other indications. The results in all 54 patients indicate good safety and tolerance of SHU 563 without limitations for diagnostic use. SHU 563 A enhanced ultrasound adds significantly to the detection and delineation of focal liver lesions by improving conspicuity due to RES based contrast after uptake.

Adenocarcinoma↗
PubMed1999

Imaging of tumour therapy responses by dynamic CT.

The objective of this study was to investigate whether functional CT with Patlak analysis could be used to demonstrate acute changes associated with radiotherapy. Patlak analysis yields fractional vascular volume and contrast clearance per unit volume (a measure of permeability). Four tumour types (prostate, bronchus, breast and cervix) were studied pre-radiotherapy and at 1-2 weeks and 6-12 weeks post-therapy. Significant rises in fractional vascular volume and contrast clearance were shown at 1-2 weeks. These indices were still significantly elevated at 6-12 weeks post-therapy. In the prostates perfusion values were also elevated reflecting a hyperemic response to radiotherapy. Dynamic CT with Patlak analysis can be used to measure important pathophysiological indices which may prove useful in assessing response to therapy of tumours.

Breast Neoplasms↗
PubMed1995

Embolization of hepatic artery pseudo-aneurysm facilitated by selective injection of thrombin and thrombin-soaked coils.

A case of recurrent haemobilia due to a pseudo-aneurysm of the right hepatic artery is presented. The patient required long-term anticoagulant therapy and, in order to achieve rapid haemostasis, thrombin was used as an adjunct to coil embolization. Rapid thrombosis of the pseudo-aneurysm occurred after selective injection of 200 units of thrombin, and thrombin-soaked coils were employed to occlude the arterial supply.

Aneurysm↗
PubMed1994

Gadolinium chelate MR contrast agents.

Several Gadolinium chelates are now available or will shortly become available. They differ in being, variously, ionic or non-ionic and in being of higher or lower osmolality. Although they differ in detail of chemical structure, they are all based on the same general principle and all possess the same extracellular distribution pharmacokinetics (Gd BOPTA excepted), typical for their molecular size. In terms of efficacy there is no convincing evidence that any one is clinically superior to the others. As regards reducing osmolality, it is not self evident that, in the recommended and currently widely used dosage regimens, high osmolality presents any real clinical problems. However, if 'high dosage' regimens or dynamic bolus imaging come to be more widely used, then the newer agents may be perceived to have clinical advantages.

Contrast Media↗