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.

Comparison of Computed Tomographic and Magnetic Resonance Perfusion Measurements in Acute Ischemic Stroke Back-to-Back Quantitative Analysis

Abstract: Background and Purpose—Magnetic resonance perfusion (MRP) and computed tomographic perfusion (CTP) are being increasingly applied in acute stroke trials and clinical practice, yet the comparability of their perfusion values is not well validated. The aim of this study was to validate the comparability of CTP and MRP measures. Methods—A 3-step approach was used. Step 1 was a derivation step, where we analyzed 45 patients with acute ischemic stroke who had both CTP and MRP performed within 2 hours of each other and within 9 hours of stroke onset. In this step, we derived the optimal perfusion map with the least difference between MRP and CTP. In step 2, the optimal map was validated on whole-brain perfusion data of 15 patients. Step 3 was to apply the optimal perfusion map to define cross-modality reperfusion from acute CTP to 24-hour MRP in 45 patients and, in turn, to assess how accurately this predicted 3-month clinical outcome. Results—Among 8 different perfusion maps included in this study, time to pea...

Augmentation of Muscle Blood Flow by Ultrasound Cavitation Is Mediated by ATP and Purinergic Signaling.

Abstract: Background: Augmentation of tissue blood flow by therapeutic ultrasound is thought to rely on convective shear. Microbubble contrast agents that undergo ultrasound-mediated cavitation markedly amplify these effects. We hypothesized that purinergic signaling is responsible for shear-dependent increases in muscle perfusion during therapeutic cavitation. Methods: Unilateral exposure of the proximal hindlimb of mice (with or without ischemia produced by iliac ligation) to therapeutic ultrasound (1.3 MHz, mechanical index 1.3) was performed for 10 minutes after intravenous injection of 2×10 8 lipid microbubbles. Microvascular perfusion was evaluated by low-power contrast ultrasound perfusion imaging. In vivo muscle ATP release and in vitro ATP release from endothelial cells or erythrocytes were assessed by a luciferin-luciferase assay. Purinergic signaling pathways were assessed by studying interventions that (1) accelerated ATP degradation; (2) inhibited P2Y receptors, adenosine receptors, or K ATP channels; or (3) inhibited downstream signaling pathways involving endothelial nitric oxide synthase or prostanoid production (indomethacin). Augmentation in muscle perfusion by ultrasound cavitation was assessed in a proof-of-concept clinical trial in 12 subjects with stable sickle cell disease. Results: Therapeutic ultrasound cavitation increased muscle perfusion by 7-fold in normal mice, reversed tissue ischemia for up to 24 hours in the murine model of peripheral artery disease, and doubled muscle perfusion in patients with sickle cell disease. Augmentation in flow extended well beyond the region of ultrasound exposure. Ultrasound cavitation produced an ≈40-fold focal and sustained increase in ATP, the source of which included both endothelial cells and erythrocytes. Inhibitory studies indicated that ATP was a critical mediator of flow augmentation that acts primarily through either P2Y receptors or adenosine produced by ectonucleotidase activity. Combined indomethacin and inhibition of endothelial nitric oxide synthase abolished the effects of therapeutic ultrasound, indicating downstream signaling through both nitric oxide and prostaglandins. Conclusions: Therapeutic ultrasound using microbubble cavitation to increase muscle perfusion relies on shear-dependent increases in ATP, which can act through a diverse portfolio of purinergic signaling pathways. These events can reverse hindlimb ischemia in mice for >24 hours and increase muscle blood flow in patients with sickle cell disease. Clinical Trial Registration: URL: http://clinicaltrials.gov. Unique identifier: NCT01566890.

Assessment of regional cerebral blood flow (rCBF) in stroke using SPECT and N-isopropyl-(I-123)-p-iodoamphetamine (IMP).

Abstract: In this study we assessed regional cerebral blood flow in patients with signs and symptoms of acute stroke using single-photon emission computed tomography (SPECT) and N-isopropyl I-123 p-iodoamphetamine (IMP). Twenty-five patients with acute cerebral infarction had both IMP brain perfusion studies and CT scans performed within one week of each other; 22 had positive and three had negative perfusion studies. Of the 22 patients who had positive perfusion studies, six had negative CT studies initially. In the 16 patients who had abnormal CT studies, eight of the studies depicted areas of edema that were smaller than the perfusion deficits noted on the IMP studies and eight had areas of edema that were approximately equal in size to the perfusion defect. Of the three patients with normal IMP studies, two had normal CT studies and one had a positive CT study showing a 3-mm lacunar infarction. Using eight control patients, mean count rates per tissue volume normalized for the injected dose was calculated. Similarly, the quantitative data from regions of interest in the stroke patients were calculated and compared to the control patients or to a normal region in the uninvolved hemisphere in the same patients. SPECT with IMP was used to assess regional brain perfusion in acute cerebral infarction. Perfusion abnormalities were seen in our patients when the CT scan was normal, and quantitative data could be used to approximate regional cerebral blood flow in these patients when compared to the normal patient population.