Development and validation of novel and quantitative MRI methods for cancer evaluation

Quantitative imaging biomarkers (QIB) offer the opportunity to further the evaluation of cancer at presentation as well as predict response to anti-cancer therapies before and early during treatment with the ultimate goal of truly personalised medical care and the mitigation of futile, often detrimental, therapy. Few QIBs are successfully translated into clinical practice and there is increasing recognition that rigorous methodologies and standardisation of research pipelines and techniques are required to move a theoretically useful biomarker into the clinic. To this end, I have aimed to give an overview of what I believe to be some of key elements within the research field beginning with the concept of imaging biomarkers, introducing concepts in development and validation, before providing a summary of the current and future utility of a range of quantitative MR imaging biomarkers techniques within the oncological imaging field. The original, prospective, research moves from the technical and analytical validation of a novel QIB use (T1 mapping in cancer), first in vivo qualification of this biomarker in cancer patient response assessment and prediction (sarcoma and breast cancer as well as prostate cancer separately), and then moving on to application of more established QIBs in cancer evaluation (R2*/BOLD imaging in head and neck cancer) as well as how existing MR data can be post-processed to improved cancer evaluation (further metrics derived from diffusion weighted imaging in head and neck cancer and textural analysis of existing clinical MR images utility in prostate cancer detection)

Methodological considerations in quantification of oncological FDG PET studies

Contains fulltext : 87741.pdf (publisher's version ) (Closed access) Contains fulltext : 87741-1.pdf (postprint version ) (Open Access)PURPOSE: This review aims to provide insight into the factors that influence quantification of glucose metabolism by FDG PET images in oncology as well as their influence on repeated measures studies (i.e. treatment response assessment), offering improved understanding both for clinical practice and research. METHODS: Structural PubMed searches have been performed for the many factors affecting quantification of glucose metabolism by FDG PET. Review articles and references lists have been used to supplement the search findings. RESULTS: Biological factors such as fasting blood glucose level, FDG uptake period, FDG distribution and clearance, patient motion (breathing) and patient discomfort (stress) all influence quantification. Acquisition parameters should be adjusted to maximize the signal to noise ratio without exposing the patient to a higher than strictly necessary radiation dose. This is especially challenging in pharmacokinetic analysis, where the temporal resolution is of significant importance. The literature is reviewed on the influence of attenuation correction on parameters for glucose metabolism, the effect of motion, metal artefacts and contrast agents on quantification of CT attenuation-corrected images. Reconstruction settings (analytical versus iterative reconstruction, post-reconstruction filtering and image matrix size) all potentially influence quantification due to artefacts, noise levels and lesion size dependency. Many region of interest definitions are available, but increased complexity does not necessarily result in improved performance. Different methods for the quantification of the tissue of interest can introduce systematic and random inaccuracy. CONCLUSIONS: This review provides an up-to-date overview of the many factors that influence quantification of glucose metabolism by FDG PET.01 juli 201

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 128, May 1974

This special bibliography lists 282 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1974

Myocardial perfusion and resistive vessel function in coronary artery disease

Myocardial blood flow (MBF) is regulated by the coronary resistive vessels which continuously adapt the coronary blood flow he myocardial metabolic requirements, modulated by neural and humoral mechanisms, and this adaptation can compensate for increased resistance of an epicardial stenosis to a considerable extent. In patients with coronary artery disease, we postulate t dysfunction of the coronary resistive vessels may cause or contribute to myocardial ischaemia. Thus, impaired myocardial fusion maybe due to the abnormal behaviour of collateral and resistive vessels rather than to epicardial disease alone. We ipose that this alteration in resistive vessel function occurs, not only in regions subtended by epicardial disease, but is present in rote myocardium and may be altered by coronary intervention such as coronary angioplasty (PTCA) and after myocardial irction (MI). To investigate coronary resistive vessel function, positron emission tomography (PET) may be used to evaluate ional MBF using the flow tracer lsO-labelled water. Using vasodilator (or vasoconstrictor) stimuli, the coronary vasodilator ponse (CVR=maximal/basal coronary [myocardial] blood flow), an index of coronary resistive vessel function, may be measured 1 compared in regions of interest and in remote myocardium.Recovery of Resistive Vessel Dysfunction After Successful PTCA. To investigate the frequency and the time course of abnormal onary resistive vessel function after successful PTCA, patients with single vessel coronary disease and normal left ventricular ction underwent intracoronary (IC) Doppler measurement of coronary flow velocity, before and after successful PTCA, at basal I after intravenous (IV) dipyridamole. PET was performed on 3 occasions after PTCA. There was no change in CVR at Doppler ;r PTCA. In patients without restenosis, the CVR was reduced in the PTCA region for >7 days, but returned to normal at 3 nths, due to increased basal MBF for >7 days in the PTCA region, with a reduction in the dipyridamole-induced maximal MBF > 24 hours.Altered Nitric Oxide Synthesis/Release and Resistive Vessel Dysfunction After PTCA. Impaired production or release of nitric de (NO) in the from resistive vessel endothelium may cause this alteration in the CVR after PTCA. As the CVR to exogenous rates is enhanced by the endothelial dysfunction, large doses of IC sodium nitroprusside, an NO donor, were infused at the peak ?ct of IV dipyridamole to test this hypothesis using Doppler catheterisation in patients with single vessel disease, roprusside in doses sufficient to cause ultimately a fall in blood pressure did not augment the dipyridamole-induced increase in onary blood flow velocity.Altered Flow and Metabolism in Regions Subtended by Angiographically Normal Arteries in Coronary Artery Disease. The ional CVR was measured using PET in patients with stable single vessel disease. In a second group of patients and controls, [ultaneous arterial and great cardiac vein catheterisation was done at rest and during atrial pacing to measure myocardial tabolism in regions subtended by a diseased artery or by an angiographically normal artery with epicardial disease elsewhere. ; CVR was reduced in remote regions compared to controls. In the second group, at maximal pacing, there was net lactate duction in the diseased region compared to net extraction in both the remote and control.Resistive Vessel Dysfunction in Infarcted and Remote Myocardium After MI. To investigate acute resistive vessel dysfunction, ients were studied after thrombolysis for MI. Regional MBF and the CVR in infarct and remote regions was assessed, after a an of 8 days and 6 months after MI by PET. At early scanning^ the CVR was markedly reduced in the infarct region, and was tted to the amount of residual viable tissue. There was no correlation between the CVR and residual stenosis area. The remote R was less than that in remote regions, subtended by a normal artery, in controls with stable single vessel disease without MI. late scanning, the CVR improved in the infarct region, but the CVR in the remote region still remained lower than in controls.Impaired Flow Response to Cold Pressor in Collateral-Dependent Myocardium. To investigate the response of collateralpendent myocardium to reflex sympathetic stimulation (cold pressor stress), patients with stable angina and normal left itricular function were studied, in whom one coronary artery was occluded (without previous MI), and the other arteries were ;iographically normal supplying collaterals. Regional MBF and glucose uptake (using 18F-deoxyglucose) was measured using r at basal and at cold pressor. With cold pressor, no patients developed ECG changes. The cold pressor response (cold ssor/basal MBF) was low in the collateralised region, compared to remote regions, due to vasoconstriction in the majority, but in absence of demonstrable ischaemia.In summary, there is coronary resistive vessel dysfunction after PTCA which recovers over 3 months due to acute impairment of response to dipyridamole and a longer increase in basal flow, possibly due to the previous stenosis. This impairment is not due iltered production or release of NO in the microcirculation. In stable disease, there is both an impaired CVR and altered tabolism during pacing in regions subtended by a normal artery. This remote alteration is impaired acutely by myocardial irction elsewhere, with only incomplete recovery over at least 6 months. In addition to reduced vasodilator function, resistive sels in patients with atherosclerosis, have an increased tendency to vasoconstrict to a sympathetic stimulus. Thus, the erosclerotic process and the sympathetic nervous system may both play a role in determining the degree of resistive vessel function, which may cause or contribute to myocardial ischaemia in patients with coronary artery disease

Assessment of longitudinal strain in acute ST-Elevation Myocardial Infarction.

INTRODUCTION : Coronary Artery Disease is the leading cause of death worldwide. Every year about 100,000 people in the United States suffer acute Myocardial Infarction (AMI)1. The AMI incidence though shows declining trend in the west it is on the rise in the developing world. Effective management of this increasing epidemic imposes a technical challenge as well as a socioeconomic burden to the third world countries. In addition to the routine clinical and Electrocardiographic (ECG) evaluation, Echocardiography is an integral part of AMI management. Assessment of overall Left ventricular (LV) function and the regional wall motion of individual myocardial segments is the essence of Echocardiography in the patients with AMI. Traditionally the regional wall motion is assessed subjectively by 2D imaging and objectively by calculation of wall motion score index. Global LV function is usually assessed by Teichzolts and Simpson`s methodologies. These modalities have their own limitations in patients with Acute myocardial infarction. Tissue Doppler imaging offsets some of the disadvantages of 2D echocardiography but by itself has several disadvantages in the assessment of regional and overall LV function. The introduction of Strain imaging has added substance to the imaging of patients with AMI. Strain and strain rate imaging has overcome the disadvantages of 2D as well as Tissue Doppler imaging and has stood the test of time since its introduction a decade ago. The modality of Strain imaging is fast advancing with the initial reports of Doppler based strain imaging now giving way to strain by 2D Speckle tracking. This study utilizes Longitudinal strain derived by 2D speckle tracking for assessment of regional and global LV function in patients with AMI and compares the same with traditional parameters like Wall motion score index and 2D derived Ejection Fraction (EF). AIM OF THE STUDY : To assess longitudinal strain of individual segments and global LV function by strain imaging in patients with acute ST‐elevation myocardial infarction and to compare them with wall motion score index and Simpson`s method respectively. CONCLUSION : Echocardiography, done using two methods‐ subjective assessment of wall motion as well as objective measurement of deformation (strain), in patients with acute myocardial infarction detected myocardial regions involved as well as the overall Left Ventricular function. These measurements, the WMSI and Strain correlated with each other with regards to the regional as well as global LV function. Analysis based on coefficient of correlation showed peak systolic longitudinal strain as good as WMSI in this prediction. Thus, advanced technological analysis of wall motion using strain imaging did contribute additional value compared with a conventional assessment such as wall motion score index and Simpson`s method

Aerospace medicine and biology. A continuing bibliography with indexes, supplement 195

This bibliography lists 148 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1979