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.

CT Perfusion Mean Transit Time Maps Optimally Distinguish Benign Oligemia from True “At-Risk” Ischemic Penumbra, but Thresholds Vary by Postprocessing Technique

Abstract: BACKGROUND AND PURPOSE: Various CTP parameters have been used to identify ischemic penumbra. The purpose of this study was to determine the optimal CTP parameter and threshold to distinguish true “at-risk” penumbra from benign oligemia in acute stroke patients without reperfusion. MATERIALS AND METHODS: Consecutive stroke patients were screened and 23 met the following criteria: 1) admission scanning within 9 hours of onset, 2) CTA confirmation of large vessel occlusion, 3) no late clinical or radiographic evidence of reperfusion, 4) no thrombolytic therapy, 5) DWI imaging within 3 hours of CTP, and 6) either CT or MR follow-up imaging. CTP was postprocessed with commercial software packages, using standard and delay-corrected deconvolution algorithms. Relative cerebral blood flow, volume, and mean transit time (rCBF, rCBV and rMTT) values were obtained by normalization to the uninvolved hemisphere. The admission DWI and final infarct were transposed onto the CTP maps and receiver operating characteristic curve analysis was performed to determine optimal thresholds for each perfusion parameter in defining penumbra destined to infarct. RESULTS: Relative and absolute MTT identified penumbra destined to infarct more accurately than CBF or CBV*CBF (P CONCLUSIONS: Appropriately thresholded absolute and relative MTT-CTP maps optimally distinguish “at-risk” penumbra from benign oligemia in acute stroke patients with large-vessel occlusion and no reperfusion. The precise threshold values may vary, however, depending on the postprocessing technique used for CTP map construction.

Reproducibility of quantitative CT perfusion imaging

Abstract: The ability to demonstrate regions of abnormal cerebral blood flow in the setting of acute stroke is of diagnostic and prognostic importance. It may also influence therapeutic strategies. The advantage of CT perfusion imaging is its ability to give quantifiable measurements of cerebral blood flow on any modern CT machine without the need to buy specialized equipment. The aim was to assess day-to-day variability of values of cerebral blood volume obtained with this technique. Seven patients with cerebral gliomas were studied using dynamic CT perfusion imaging on two occasions, approximately 24 h apart to reduce variability from diurnal variations. Regions of interest were produced in predominately middle cerebral artery locations in both hemispheres on the first and second CT perfusion studies. Absolute values for cerebral blood flow were produced for these regions and were correlated with flows obtained in the same regions of interest on the follow-up study. The Pearson correlation coefficient obtained was 0.884. CT perfusion imaging is easily performed on conventional modern CT equipment and demonstrates little variability in measures of absolute cerebral blood flow within individuals when studied on two occasions within 24 h.

Cortical Regional Hyperperfusion in Nonconvulsive Status Epilepticus Measured by Dynamic Brain Perfusion CT

Abstract: BACKGROUND AND PURPOSE: Nonconvulsive status epilepticus (NCSE) is associated with a mortality rate of up to 18%, therefore requiring prompt diagnosis and treatment. Our aim was to evaluate the diagnostic value of perfusion CT (PCT) in the differential diagnosis of NCSE versus postictal states in patients presenting with persistent altered mental states after a preceding epileptic seizure. We hypothesized that regional cortical hyperperfusion can be measured by PCT in patients with NCSE, whereas it is not present in postictal states. MATERIALS AND METHODS: Nineteen patients with persistent altered mental status after a preceding epileptic seizure underwent PCT and electroencephalography (EEG). Patients were stratified as presenting with NCSE (n = 9) or a postictal state (n = 10) on the basis of clinical history and EEG data. Quantitative and visual analysis of the perfusion maps was performed. RESULTS: Patients during NCSE had significantly increased regional cerebral blood flow (P > .0001), increased regional cerebral blood volume (P > .001), and decreased (P > .001) mean transit time compared with the postictal state. Regional cortical hyperperfusion was depicted in 7/9 of patients with NCSE by ad hoc analysis of parametric perfusion maps during emergency conditions but was not a feature of postictal states. The areas of hyperperfusion were concordant with transient clinical symptoms and EEG topography in all cases. CONCLUSIONS: Visual analysis of perfusion maps detected regional hyperperfusion in NCSE with a sensitivity of 78%. The broad availability and short processing time of PCT in an emergency situation is a benefit compared with EEG. Consequently, the use of PCT in epilepsy may accelerate the diagnosis of NCSE. PCT may qualify as a complementary diagnostic tool to EEG in patients with persistent altered mental state after a preceding seizure.

Imaging techniques in nuclear cardiology for the assessment of myocardial viability.

Abstract: The assessment of myocardial viability has become an important aspect of the diagnostic and prognostic work-up of patients with ischemic cardiomyopathy. Although revascularization may be considered in patients with sufficient viable myocardium, patients with predominantly scar tissue should be treated medically. Patients with left ventricular dysfunction who have viable myocardium are the patients at highest risk because of the potential for ischemia but at the same time benefit most from revascularization. It is important to identify viable myocardium in these patients, and radionuclide myocardial scintigraphy is an excellent tool for this. Single-photon emission computed tomography perfusion scintigraphy (SPECT), whether using (201)thallium, (99m)Tc-sestamibi, or (99m)Tc-tetrofosmin, in stress and/or rest protocols, has consistently been shown to be an effective modality for identifying myocardial viability and guiding appropriate management. Metabolic and perfusion imaging with positron emission tomography (PET) radiotracers frequently adds additional information and is a powerful tool for predicting which patients will have an improved outcome from revascularization. New techniques in the nuclear cardiology field, like attenuation corrected SPECT, dual isotope simultaneous acquisition (DISA) SPECT and gated FDG PET are promising and will further improve the detection of myocardial viability. Also the combination of multislice computed tomography scanners with PET opens possibilities of adding coronary calcium scoring and non-invasive coronary angiography to myocardial perfusion imaging and quantification. Evaluation of the clinical role of these creative new possibilities warrants investigation.