Perfusion scanning

About: Perfusion scanning is a research topic. Over the lifetime, 9496 publications have been published within this topic receiving 223860 citations. The topic is also known as: perfusion imaging.

Calf muscle perfusion at peak exercise in peripheral arterial disease: measurement by first-pass contrast-enhanced magnetic resonance imaging.

Abstract: Peripheral arterial disease (PAD) is a condition characterized by flow-limiting atherosclerosis in the vessels supplying the lower limbs. Currently, between eight and 12 million Americans are affected by PAD and the incidence is expected to rise as the population ages (1). As a consequence of impaired tissue perfusion, PAD patients can experience pain, diminished exercise capacity, and tissue loss, with some ultimately requiring amputation (2). Improving blood flow is a major therapeutic goal in patients with PAD and a number of innovative approaches beyond revascularization have been investigated, although effective pharmacologic therapies that increase tissue perfusion are still lacking (3–5). A noninvasive technique capable of measuring tissue perfusion would be of great clinical value for assessing the severity of PAD and monitoring response to novel therapeutic interventions designed to enhance skeletal muscle perfusion. First-pass gadolinium-enhanced MRI is a robust technique well validated for evaluating myocardial perfusion (6–9). First-pass gadolinium-enhanced MRI is performed using a T1-weighted sequence to visualize a gadolinium-based contrast agent in transit through tissue. Signal intensity changes in the muscle parallel contrast concentration, and time-intensity curves (TIC) can be generated in regions of interest. In myocardium, the TIC upslope correlates well with measures of micro-sphere blood flow (10–12). While first-pass gadolinium-enhanced MRI has been used to evaluate blood flow in skeletal muscle among healthy individuals under predominantly nonphysiologic stress (13,14), its utility in identifying and characterizing perfusion in patients with PAD has not been extensively explored. The purpose of this study was to develop and evaluate a novel MR approach for measuring skeletal muscle perfusion semiquantitatively during exercise-induced ischemia in both mild to moderate PAD patients and normal subjects following isometric exercise within the MR environment.

Routine Clinical Quantitative Rest Stress Myocardial Perfusion for Managing Coronary Artery Disease: Clinical Relevance of Test-Retest Variability

Abstract: Objectives Positron emission tomography (PET) quantifies stress myocardial perfusion (in cc/min/g) and coronary flow reserve to guide noninvasively the management of coronary artery disease. This study determined their test-retest precision within minutes and daily biological variability essential for bounding clinical decision-making or risk stratification based on low flow ischemic thresholds or follow-up changes. Background Randomized trials of fractional flow reserve–guided percutaneous coronary interventions established an objective, quantitative, outcomes-driven standard of physiological stenosis severity. However, pressure-derived fractional flow reserve requires invasive coronary angiogram and was originally validated by comparison to noninvasive PET. Methods The time course and test-retest precision of serial quantitative rest-rest and stress-stress global myocardial perfusion by PET within minutes and days apart in the same patient were compared in 120 volunteers undergoing serial 708 quantitative PET perfusion scans using rubidium 82 (Rb-82) and dipyridamole stress with a 2-dimensional PET-computed tomography scanner (GE DST 16) and University of Texas HeartSee software with our validated perfusion model. Results Test-retest methodological precision (coefficient of variance) for serial quantitative global myocardial perfusion minutes apart is ±10% (mean ΔSD at rest ±0.09, at stress ±0.23 cc/min/g) and for days apart is ±21% (mean ΔSD at rest ±0.2, at stress ±0.46 cc/min/g) reflecting added biological variability. Global myocardial perfusion at 8 minutes after 4-min dipyridamole infusion is 10% higher than at standard 4 min after dipyridamole. Conclusions Test-retest methodological precision of global PET myocardial perfusion by serial rest or stress PET minutes apart is ±10%. Day-to-different-day biological plus methodological variability is ±21%, thereby establishing boundaries of variability on physiological severity to guide or follow coronary artery disease management. Maximum stress increases perfusion and coronary flow reserve, thereby reducing potentially falsely low values mimicking ischemia.

Limited reliability of computed tomographic perfusion acute infarct volume measurements compared with diffusion-weighted imaging in anterior circulation stroke.

Abstract: Background and Purpose—Diffusion-weighted imaging (DWI) can reliably identify critically ischemic tissue shortly after stroke onset. We tested whether thresholded computed tomographic cerebral blood flow (CT-CBF) and CT-cerebral blood volume (CT-CBV) maps are sufficiently accurate to substitute for DWI for estimating the critically ischemic tissue volume. Methods—Ischemic volumes of 55 patients with acute anterior circulation stroke were assessed on DWI by visual segmentation and on CT-CBF and CT-CBV with segmentation using 15% and 30% thresholds, respectively. The contrast:noise ratios of ischemic regions on the DWI and CT perfusion (CTP) images were measured. Correlation and Bland–Altman analyses were used to assess the reliability of CTP. Results—Mean contrast:noise ratios for DWI, CT-CBF, and CT-CBV were 4.3, 0.9, and 0.4, respectively. CTP and DWI lesion volumes were highly correlated (R2=0.87 for CT-CBF; R2=0.83 for CT-CBV; P<0.001). Bland–Altman analyses revealed little systemic bias (−2.6 mL) but ...

Severe Occlusive Carotid Artery Disease: Hemodynamic Assessment by MR Perfusion Imaging in Symptomatic Patients

Abstract: BACKGROUND AND PURPOSE: Cerebral hemodynamic status has been reported to influence the occurrence and outcome of acute stroke. The purpose of this study was to assess hemodynamic compromise in symptomatic patients with severe occlusive disease of the carotid artery by the use of echo-planar perfusion imaging. METHODS: Spin-echo echo-planar perfusion imaging was performed in 11 patients (two had bilateral disease) with severe stenosis or occlusion of the carotid artery who had experienced either a recent transient ischemic attack or minor stroke. Relative cerebral blood volume (rCBV) maps and relative mean transit time (rMTT) maps were generated from the time-concentration curve. Findings on T2-weighted images, angiograms, rCBV maps, and rMTT maps were compared and assessed qualitatively and quantitatively. RESULTS: Although the abnormalities on T2-weighted images were absent, minimal, and/or unrelated to the degree of stenosis or collateral circulation, rMTT maps showed much larger and more distinct perfusion abnormalities along the vascular distribution of the affected vessels in all 13 vascular territories of the 11 patients. Despite obvious abnormalities on rMTT maps, none of the patients had evidence of decreased rCBV in the affected brain tissue (increased in three, normal in eight). A statistically significant difference in rMTT values was found between the affected and unaffected brain tissue, whereas no significant difference was seen in rCBV values. CONCLUSION: Echo-planar perfusion imaging is a noninvasive and rapid method for evaluating the hemodynamics in severe occlusive carotid artery disease and the compensatory vascular changes, and it may be useful in patient management.