Showing papers on "Perfusion scanning published in 2006"
TL;DR: For stroke patients treated 3 to 6 hours after onset, baseline MRI findings can identify subgroups that are likely to benefit from reperfusion therapies and can potentially identify sub groups that are unlikely to benefit or may be harmed.
Abstract: Objective
To determine whether prespecified baseline magnetic resonance imaging (MRI) profiles can identify stroke patients who have a robust clinical response after early reperfusion when treated 3 to 6 hours after symptom onset.
Methods
We conducted a prospective, multicenter study of 74 consecutive stroke patients admitted to academic stroke centers in North America and Europe. An MRI scan was obtained immediately before and 3 to 6 hours after treatment with intravenous tissue plasminogen activator 3 to 6 hours after symptom onset. Baseline MRI profiles were used to categorize patients into subgroups, and clinical responses were compared based on whether early reperfusion was achieved.
Results
Early reperfusion was associated with significantly increased odds of achieving a favorable clinical response in patients with a perfusion/diffusion mismatch (odds ratio, 5.4; p = 0.039) and an even more favorable response in patients with the Target Mismatch profile (odds ratio, 8.7; p = 0.011). Patients with the No Mismatch profile did not appear to benefit from early reperfusion. Early reperfusion was associated with fatal intracranial hemorrhage in patients with the Malignant profile.
Interpretation
For stroke patients treated 3 to 6 hours after onset, baseline MRI findings can identify subgroups that are likely to benefit from reperfusion therapies and can potentially identify subgroups that are unlikely to benefit or may be harmed. Ann Neurol 2006
1,210 citations
TL;DR: In a large population of matched pharmacologic stress patients, myocardial perfusion PET was superior to SPECT in image quality, interpretive certainty, and diagnostic accuracy.
482 citations
TL;DR: Thrombolytic therapy has led to a higher proportion of patients presenting to hospital early, and this, with parallel developments in imaging technology, has greatly improved the understanding of acute stroke pathophysiology.
Abstract: Summary Thrombolytic therapy has led to a higher proportion of patients presenting to hospital early, and this, with parallel developments in imaging technology, has greatly improved the understanding of acute stroke pathophysiology. Additionally, MRI, including diffusion-weighted imaging (DWI) and gradient echo, or T2*, imaging is important in understanding basic structural information—such as distinguishing acute ischaemia from haemorrhage. It has also greatly increased sensitivity in the diagnosis of acute cerebral ischaemia. The pathophysiology of the ischaemic penumbra can now be assessed with CT or MRI-based perfusion imaging techniques, which are widely available and clinically applicable. Pathophysiological information from CT or MRI increasingly helps clinical trial design, may allow targeted therapy in individual patients, and may extend the time scale for reperfusion therapy.
340 citations
TL;DR: It is shown in a limited sample of patients that CBF and CBV obtained from CTP can be sensitive and specific for infarction and should be investigated further in a prospective trial to assess their utility for differentiating between infarct and penumbra.
Abstract: Background and Purpose— We investigated whether computed tomography (CT) perfusion–derived cerebral blood flow (CBF) and cerebral blood volume (CBV) could be used to differentiate between penumbra and infarcted gray matter in a limited, exploratory sample of acute stroke patients. Methods— Thirty patients underwent a noncontrast CT (NCCT), CT angiography (CTA), and CT perfusion (CTP) scan within 7 hours of stroke onset, NCCT and CTA at 24 hours, and NCCT at 5 to 7 days. Twenty-five patients met the criteria for inclusion and were subsequently divided into 2 groups: those with recanalization at 24 hours (n=16) and those without (n=9). Penumbra was operationally defined as tissue with an admission CBF <25 mL · 100 g−1 · min−1 that was not infarcted on the 5- to 7-day NCCT. Logistic regression was applied to differentiate between infarct and penumbra data points. Results— For recanalized patients, CBF was significantly lower (P<0.05) for infarct (13.3±3.75 mL · 100 g−1 · min−1) than penumbra (25.0±3.82 mL · ...
274 citations
TL;DR: The goals of an imaging evaluation for acute stroke are to establish a diagnosis as early as possible and to obtain accurate information about the intracranial vasculature and brain perfusion for guidance in selecting the appropriate therapy.
Abstract: Stroke is a leading cause of mortality and morbidity in the developed world. The goals of an imaging evaluation for acute stroke are to establish a diagnosis as early as possible and to obtain accurate information about the intracranial vasculature and brain perfusion for guidance in selecting the appropriate therapy. A comprehensive evaluation may be performed with a combination of computed tomography (CT) or magnetic resonance (MR) imaging techniques. Unenhanced CT can be performed quickly, can help identify early signs of stroke, and can help rule out hemorrhage. CT angiography and CT perfusion imaging, respectively, can depict intravascular thrombi and salvageable tissue indicated by a penumbra. These examinations are easy to perform on most helical CT scanners and are increasingly used in stroke imaging protocols to decide whether intervention is necessary. While acute infarcts may be seen early on conventional MR images, diffusion-weighted MR imaging is more sensitive for detection of hyperacute ischemia. Gradient-echo MR sequences can be helpful for detecting a hemorrhage. The status of neck and intracranial vessels can be evaluated with MR angiography, and a mismatch between findings on diffusion and perfusion MR images may be used to predict the presence of a penumbra. The information obtained by combining various imaging techniques may help differentiate patients who do not need intravenous or intraarterial therapy from those who do, and may alter clinical outcomes.
270 citations
TL;DR: Administration of AdVEGF121 by direct intramyocardial injections resulted in objective improvement in exercise-induced ischemia in patients with refractory ischemic heart disease.
Abstract: The demonstration that angiogenic growth factors can stimulate new blood vessel growth and restore perfusion in animal models of myocardial ischemia has led to the development of strategies designed for the local production of angiogenic growth factors in patients who are not candidates for conventional revascularization. The results of recent clinical trials of proangiogenesis gene therapy have been disappointing; however, significant limitations in experimental design, in particular in gene transfer strategies, preclude drawing definitive conclusions. In the REVASC study cardiac gene transfer was optimized by direct intramyocardial delivery of a replication-deficient adenovirus-containing vascular endothelial growth factor (AdVEGF121, 4 x 10(10) particle units (p.u.)). Sixty-seven patients with severe angina due to coronary artery disease and no conventional options for revascularization were randomized to AdVEGF121 gene transfer via mini-thoracotomy or continuation of maximal medical treatment. Exercise time to 1 mm ST-segment depression, the predefined primary end-point analysis, was significantly increased in the AdVEGF121 group compared to control at 26 weeks (P=0.026), but not at 12 weeks. As well, total exercise duration and time to moderate angina at weeks 12 and 26, and in angina symptoms as measured by the Canadian Cardiovascular Society Angina Class and Seattle Angina Questionnaire were all improved by VEGF gene transfer (all P-values at 12 and 26 weeks < or =0.001). However, if anything the results of nuclear perfusion imaging favored the control group, although the AdVEGF121 group achieved higher workloads. Overall there was no significant difference in adverse events between the two groups, despite the fact that procedure-related events were seen only in the thoracotomy group. Therefore, administration of AdVEGF121 by direct intramyocardial injections resulted in objective improvement in exercise-induced ischemia in patients with refractory ischemic heart disease.
266 citations
TL;DR: Stress-induced signs of ischemia and significant coronary artery disease are highly prevalent after mediastinal irradiation in young patients, suggesting asymptomatic individuals at high risk for acute myocardial infarction or sudden cardiac death.
Abstract: Purpose Incidental cardiac irradiation during treatment of thoracic neoplasms has increased risks for subsequent acute myocardial infarction or sudden cardiac death. Identifying patients who have a high risk for a coronary event may decrease morbidity and mortality. The objective of this study was to evaluate whether stress imaging can identify severe, unsuspected coronary stenoses in patients who had prior mediastinal irradiation for Hodgkin's disease. Patients and Methods We enrolled 294 outpatients observed at a tertiary care cancer treatment center after mediastinal irradiation doses ≥ 35 Gy for Hodgkin's disease who had no known ischemic cardiac disease. Patients underwent stress echocardiography and radionuclide perfusion imaging at one stress session. Coronary angiography was performed at the discretion of the physician. Results Among the 294 participants, 63 (21.4%) had abnormal ventricular images at rest, suggesting prior myocardial injury. During stress testing, 42 patients (14%) developed perfu...
231 citations
TL;DR: This study compared CMRI with CA plus a standard invasive functional assessment (FFR) and demonstrated that CMRI is able to distinguish haemodynamically relevant from non-relevant coronary lesions with a high sensitivity and specificity and may contribute to clinical decision-making.
Abstract: Aims Cardiac magnetic resonance perfusion imaging (CMRI) is a promising technique for non-invasive measurement of myocardial perfusion reserve. Fractional flow reserve (FFR) is an established invasive method for functional assessment of coronary artery disease (CAD). To prospectively assess the diagnostic value of CMRI for the detection of haemodynamically significant coronary lesions, compared with coronary angiography (CA) and FFR.
Methods and results Forty-three patients with suspected or known CAD underwent CA, CMRI, and FFR measurement. First pass magnetic resonance perfusion examination was performed during hyperaemia (140 µg/kg/min adenosine over 6 min) and at rest. One hundred and twenty-nine perfusion territories were assessed by semi-quantitative evaluation of signal intensity–time curves using the myocardial perfusion reserve index (MPRI) [upslopestress(corrected)/upsloperest(corrected)]. Perfusion territories were categorized as normal (coronary stenosis≤50%), intermediate (stenosis>50% and FFR>0.75), or severe (stenosis>50% and FFR≤0.75 or total occlusion). MPRI values (±SD) were significantly different between the three categories [normal, 2.2±0.5 vs. intermediate, 1.8±0.5 ( P =0.005) and intermediate vs. severe, 1.2±0.3 ( P <0.001)]. An MPRI cut-off value of 1.5 (derived from receiver operating characteristics analysis) distinguished haemodynamically relevant (severe) from non-relevant (normal and intermediate) stenoses with a sensitivity of 88% (CI 74–100%) and a specificity of 90% (CI 84–96%).
Conclusion In contrast to earlier studies that compared CMRI with morphological examination (CA) alone, the present study compared CMRI with CA plus a standard invasive functional assessment (FFR) and demonstrated that CMRI is able to distinguish haemodynamically relevant from non-relevant coronary lesions with a high sensitivity and specificity and may therefore contribute to clinical decision-making.
198 citations
TL;DR: Diffusion and perfusion imaging, even with relatively short imaging and data processing times, provide important information for lesion characterization in patients with intraaxial brain tumors.
Abstract: Advanced magnetic resonance (MR) imaging techniques provide physiologic information that complements the anatomic information available from conventional MR imaging. We evaluated the roles of diffusion and perfusion imaging for the assessment of grade and type of histologically proven intraaxial brain tumors. A total of 28 patients with intraaxial brain tumors underwent conventional MR imaging (T2- and T1-weighted sequences after gadobenate dimeglumine injection), diffusion imaging and T2*-weighted echo-planar perfusion imaging. Examinations were performed on 19 patients during initial diagnosis and on nine patients during follow-up therapy. Determinations of relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) were performed in the solid parts of each tumor, peritumoral region and contralateral white matter. For gliomas, rCBV values were greater in high-grade than in low-grade tumors (3.87+/-1.94 versus 1.30+/-0.42) at the time of initial diagnosis. rCBV values were increased in all recurrent tumors, except in one patient who presented with a combination of recurrent glioblastoma and massive radionecrosis on histology. Low-grade gliomas had low rCBV even in the presence of contrast medium enhancement. Differentiation between high- and low-grade gliomas was not possible using diffusion-weighted images and ADC values alone. In the peritumoral areas of untreated high-grade gliomas and metastases, the mean rCBV values were higher for high-grade gliomas (1.7+/-0.37) than for metastases (0.54+/-0.18) while the mean ADC values were higher for metastases. The rCBV values of four lymphomas were low and the signal intensity-time curves revealed a significant increase in signal intensity after the first pass of gadobenate dimeglumine. Diffusion and perfusion imaging, even with relatively short imaging and data processing times, provide important information for lesion characterization.
179 citations
Journal Article•
TL;DR: In acute stroke patients, quantitative CTP can distinguish ischemic tissue likely to infarct from that likely to survive.
Abstract: BACKGROUND AND PURPOSE: The purpose of this study was to determine whether, in acute stroke patients treated with intra-arterial (IA) recanalization therapy, CT perfusion (CTP) can distinguish ischemic brain tissue destined to infarct from that which will survive. METHODS: Dynamic CTP was obtained in 14 patients within 8 hours of stroke onset, before IA therapy. Initial quantitative cerebral blood volume (CBV) and flow (CBF) values were visually segmented and normalized in the “infarct core” (region 1: reduced CBV and CBF, infarction on follow-up), “penumbra that infarcts” (region 2: normal CBV, reduced CBF, infarction on follow-up), and “penumbra that recovers” (region 3: normal CBV, reduced CBF, normal on follow-up). Normalization was accomplished by dividing the ischemic region of interest value by that of a corresponding, contralateral, uninvolved region, which resulted in CBV and CBF “ratios.” Separate CBV and CBF values were obtained in gray matter (GM) and white matter (WM). RESULTS: Mean CBF ratios for regions 1, 2, and 3 were 0.19 ± 0.06, 0.34 ± 0.06, and 0.46 ± 0.09, respectively (all P P 0.44 infarcted. GM versus WM CBF and CBV values were significantly different for region 2 compared with region 3 ( P CONCLUSIONS: In acute stroke patients, quantitative CTP can distinguish ischemic tissue likely to infarct from that likely to survive.
177 citations
TL;DR: The results demonstrate that cerebral perfusion is significantly altered in COPD patients and the relationship between decreased perfusion and cognitive impairment and the clinical significance of these results require further studies in larger populations.
Abstract: Objectives
To clarify cerebral perfusion distribution and cognitive functions in patients with chronic obstructive pulmonary disease (COPD) according to the hypoxia levels and to assess if there is a relationship between cognitive impairment and cerebral perfusion index.
TL;DR: CT perfusion imaging after cranioplasty revealed the improvement of cerebral blood flow not only on the symptomatic side but also on the contralateral side, in the first reported case of SSSF examined with CT perfusion Imaging before and after crANIoplasty.
TL;DR: Perfusional abnormalities in patients with REM behavior disorder were located in the brainstem, striatum, and cortex, which are consistent with the anatomic metabolic profile of Parkinson disease.
Abstract: Objective: To investigate the regional cerebral perfusion in patients with idiopathic REM behavior disorder (RBD) in order to establish the topography of networks involved. Methods: We performed cerebral blood flow evaluation using 99m Tc-Ethylene Cysteinate Dimer (ECD) SPECT on eight patients with polysomnographically confirmed RBD and nine age-matched controls. Comparisons were made using SPM2. Results: We found increased perfusion in the pons and putamen bilaterally and in the right hippocampus. In addition, we observed a decreased perfusion in frontal (Brodmann area [BA] 4, 6, 10, 43, 44, 47 bilaterally and left BA 9, 46) and temporo-parietal (BA 13, 22, 43 bilaterally and left BA 7, 19, 20, 21, 39, 40, 41, 42) cortices. Conclusion: Perfusional abnormalities in patients with REM behavior disorder were located in the brainstem, striatum, and cortex. These abnormalities are consistent with the anatomic metabolic profile of Parkinson disease.
Journal Article•
TL;DR: CASL and T2DSC perfusion methods are comparable in the characterization of meningiomas and CASL is of use in assessing tumor microcirculation.
Abstract: PURPOSE: The goal of the present study was to determine the utility of continuous arterial spin labeling (CASL) for characterization of meningioma by MR perfusion imaging and to compare these results with those obtained from the T2 dynamic susceptibility contrast (T2DSC) method and from histopathologic examination. METHODS: Twenty-one cases of meningiomas were examined at 1.5T. CASL perfusion imaging was implemented on the basis of multisection single-shot echo-planar imaging with velocity-driven adiabatic spin-inversion preparation. T2DSC perfusion imaging was also performed by using a double-echo spoiled gradient echo sequence in a section containing the tumor. By focusing on the regions of interest, maps of % signal intensity change and cerebral blood flow (CBF) were determined from CASL and cerebral blood volume (CBV). CBF and mean transit time (MTT) were obtained from T2DSC. The microvessel area (MVA) was determined from specimens immunostained with anti-CD31 in 14 cases by measuring the total amount of staining in each histologic section. Linear regression analysis was performed for rCBF values from both perfusion methods and for % signal intensity change and MVA. RESULTS: There was a significant correlation between CBF values determined from both perfusion methods ( r 2 = 0.73; P r 2 = 0.91; P CONCLUSIONS: CASL and T2DSC perfusion methods are comparable in the characterization of meningiomas. Further, CASL is of use in assessing tumor microcirculation.
TL;DR: These guidelines are an update of an earlier version of these guidelines that have been developed by the Quality Assurance Committee of the American Society of Nuclear Cardiology and are recognized that PET and PET/CT imaging is evolving rapidly and that these recommendations may need further revision in the near future.
TL;DR: Preliminary data hold out the promise that the cerebral blood supply in the elderly participates in the vasodilator response, and the prospect of increasing cerebral perfusion with cocoa flavanols is extremely promising.
Abstract: Foods and beverages rich in flavonoids are being heralded as potential preventive agents for a range of pathologic conditions, ranging from hypertension to coronary heart disease to stroke and dementia. We and others have demonstrated that short-term ingestion of cocoa, particularly rich in the subclass of flavonoids known as flavanols, induced a consistent and striking peripheral vasodilation in healthy people, improving endothelial function in a nitric oxide-dependent manner. The vasodilator response was reversed by N-nitro-L-arginine methyl ester, an arginine analog that blocks nitric oxide synthesis. Flavanol-poor cocoa induced much smaller responses. Because impairment of endothelial function is a nearly universal accompaniment of the aging process, we examined the peripheral vasodilator response to flavanol-rich cocoa in healthy older subjects. Observations point to a favorable response among the older. Together with peripheral vascular disease, cerebrovascular disease is responsible for significant mortality with advancing age. An association of decreased cerebral perfusion with dementia has been recently highlighted. The prospect of increasing cerebral perfusion with cocoa flavanols is extremely promising. Our still preliminary data hold out the promise that the cerebral blood supply in the elderly participates in the vasodilator response. With the modalities of transcranial Doppler and MRI, we have the capabilities of analyzing the potential benefits of flavanols on brain perfusion and, subsequently, on cognition.
TL;DR: Stress first-pass perfusion MR imaging followed by delayed-enhancement imaging is an accurate method to depict significant coronary stenosis in patients suspected of having or known to have coronary artery disease (CAD).
Abstract: Purpose: To prospectively determine the accuracy of a combined magnetic resonance (MR) imaging approach (stress first-pass perfusion imaging followed by delayed-enhancement imaging) for depicting clinically significant coronary artery stenosis (≥70% stenosis) in patients suspected of having or known to have coronary artery disease (CAD), with coronary angiography serving as the reference standard. Materials and Methods: The committee on human research approved the study protocol, and all participants gave written informed consent. This study was HIPAA compliant. Forty-seven patients (38 men and nine women; mean age, 63 years ± 5.3 [standard deviation]) scheduled for coronary angiography were prospectively enrolled: 33 were suspected of having CAD (group A) and 14 had experienced a previous myocardial infarction and were suspected of having new lesions (group B). The MR imaging protocol included cine function, gadolinium-enhanced stress and rest first-pass perfusion MR imaging, and delayed-enhancement MR i...
TL;DR: MIBG myocardial scintigraphy may improve the sensitivity in the detection ofDLB and provide a powerful differential diagnostic tool when it is difficult to distinguish cases of DLB from AD using brain perfusion SPECT.
Abstract: Purpose
Both decreased occipital perfusion on brain single-photon emission computed tomography (SPECT) and reduction in cardiac 123I-metaiodobenzylguanidine (MIBG) uptake are characteristic features of dementia with Lewy bodies (DLB), and potentially support the clinical diagnosis of DLB. The aim of this study was to compare the diagnostic value of these two methods for differentiation of DLB from Alzheimer’s disease (AD).
TL;DR: MDCT has the potential for visual and semiquantitative assessment of first-pass myocardial perfusion and MR imaging both allowed for the differentiation of hypoperfused and normal myocardium.
Abstract: To evaluate the feasibility of myocardial first-pass perfusion imaging with multidetector CT (MDCT) In five pigs, myocardial infaction was induced by permanent balloon occlusion of the left anterior descending coronary artery Dynamic contrast-enhanced MDCT (12×15 mm, 120 kV, 30 mAs, 64 acquisitions, 40 ml iopromide 370@4ml/s) and contrast-enhanced first-pass perfusion magnetic resonance (MR) imaging (TR 77 ms/TE 26 ms, 64 acquisitions, 005 mmol/kg Gd-DTPA) were performed Finally, the animals were sacrificed, and the heart was excised and stained with triphenyltetrazolin-chloride (TTC) Maximum signal intensity (SImax), contrast material arrival time (CAT), wash-in time (Tmax) and slope were calculated from time-density/signal-intensity curves The area of myocardial hypoperfusion was measured as the percentage of the left-ventricular area (%LV) Parameters were compared using Bland-Altman plots and Student's t-tests The hypoperfused area on MDCT was 193±45%LV (MR imaging 172±40%LV) The mean size of infarction was 187±57%LV with TTC Semiquantitative analysis of MR imaging and MDCT for SImax, Tmax and slope showed significant differences between normal and infarcted myocardium (P<005) No significant differences were found for CAT MDCT and MR imaging both allowed for the differentiation of hypoperfused and normal myocardium Results given in absolute values differed significantly between both imaging modalities (P<005) MDCT has the potential for visual and semiquantitative assessment of first-pass myocardial perfusion
TL;DR: Perfusion parameters derived from RT‐CES significantly improve the early detection of CAN compared to conventional CDUS and is a feasible method to evaluate microvascular perfusion in renal allograft recipients.
TL;DR: Parameters of CT perfusion correlated significantly with the severity of liver fibrosis and cirrhosis and there were no significant differences in TBV and MTT between each groups.
Abstract: This study assessed the utility of CT perfusion for quantitative assessment of liver function and fibrosis. Tissue blood flow (TBF), tissue blood volume (TBV), mean transit time (MTT) and hepatic arterial fraction (HAF) were measured with CT perfusion using the deconvolution algorithm in 38 patients with chronic liver diseases and 10 patients without liver disease. Using Child-Pugh classification, 21 patients were classified as Child A, 10 as Child B, and 7 as Child C. In 20 patients, the degree of fibrosis was quantitated in surgically-resected specimens and compared with the perfusion parameters. The mean TBF, TBV, MTT and HAF of patients with-out liver disease were 103.9+/-18 ml/min/100 g, 12.5+/-2.0 ml/100 g, 11.1+/-1.6 sec and 18.4+/-5.6%, respectively (+/-SD). The mean TBF of patients with Child A, B and C were 95.1+/-24, 86.7+/-29 and 75.5+/-6.5 ml/min/100 g, respectively. TBF tended to decrease with the severity of chronic liver disease. The mean HAF of patients with Child A, B and C were 18.6+/-8.3, 29.8+/-11.2 and 40.2+/-11.1%, respectively. HAF of patients without liver disease was significantly different from those of Child B and C (p<0.05, each). However, there were no significant differences in TBV and MTT between each groups. HAF correlated significantly with the degree of fibrosis (R2=0.588, p<0.05). Our results showed that parameters of CT perfusion correlated significantly with the severity of liver fibrosis and cirrhosis. Quantitative measurement of hepatic tissue blood flow by CT perfusion is useful for evaluation of the severity of disease and fibrotic change.
TL;DR: This result indicates that PTSD patients have alterations in cerebral perfusion of limbic regions and the frontal and temporal cortex without re-exposure to accident-related stimuli, and supports the hypothesis of the involvement of limbsic regions, which might be associated with the regulation of emotion and memory, in the pathophysiology of PTSD.
TL;DR: 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.
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.
TL;DR: Abnormal permeability of the human blood-brain barrier can be induced by wide-field low-frequency insonation and the observed excessive bleeding rate with low- frequency sonothrombolysis might be attributable to primary blood- brain barrier disruption by ultrasound.
Abstract: Background and Purpose— A recent study showed a dramatic increase in cerebral hemorrhage comprising atypical locations with low-frequency ultrasound–mediated recombinant tissue plasminogen activator–thrombolysis in humans. Here, we provide a possible explanation for this phenomenon by a side effect observed in a study using the similar ultrasound device.
Methods— The study was originally undertaken to investigate by transcranial Doppler sonography, positron emission tomography and perfusion MRI whether transcranial application of wide-field low-frequency ultrasound (300 kHz) improves cerebral hemodynamics in patients with cerebral small vessel disease.
Results— Showing no clear positive effect on cerebral hemodynamics in 4 patients and on cerebral perfusion (positron emission tomography) in 2 patients, the study has been terminated early because of a remarkable side effect in the first patient (a 62 year-old man) undergoing perfusion-MRI: detection of frontoparietal extravasation of Gadolinium contrast agent (applied during MRI perfusion imaging preinsonation) on MRI immediately postinsonation.
Conclusions— Abnormal permeability of the human blood-brain barrier can be induced by wide-field low-frequency insonation. The observed excessive bleeding rate with low-frequency sonothrombolysis might thus be attributable to primary blood-brain barrier disruption by ultrasound.
TL;DR: The cerebral blood flow ratio (comparing contralateral regions of interest) seems the best prognosticator for development of DCI.
Abstract: Background: Delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is difficult to predict. The authors studied the relation between several parameters of brain perfusion at admission and development of DCI. Methods: The authors analyzed the admission CT perfusion (CTP) scans of 46 patients scanned within 72 hours after SAH. They assessed cerebral blood volume (CBV) and flow (CBF), mean transit time (MTT), and time to peak (TTP) for eight predefined regions of interest. For patients with and without DCI, the authors compared perfusion quantitatively and semiquantitatively. With receiver-operator characteristic (ROC) curves, the authors assessed the relationship between DCI and perfusion parameters. To assess the potential prognostic value, they calculated sensitivity and specificity of optimal threshold values for the semiquantitative data. Results: DCI was not significantly related with quantitative perfusion values. For the semiquantitative data, patients with DCI had significantly more asymmetry in perfusion, and ROC curves indicated a good relation (0.75 to 0.81). Optimal threshold values distinguishing between patients with and without DCI were 0.77 for CBV and 0.72 for CBF ratios, and 0.87 seconds for MTT and 1.0 second for TTP differences. The corresponding sensitivity was 0.75 for all parameters; the specificity was 0.70 for CBV, 0.93 for CBF, 0.70 for MTT, and 0.90 for TTP. Conclusions: Delayed cerebral ischemia (DCI) is related to perfusion asymmetry on admission CT perfusion (CTP). The cerebral blood flow ratio (comparing contralateral regions of interest) seems the best prognosticator for development of DCI. Further studies are needed to investigate the additional value of CTP to other prognosticators for DCI and to validate the chosen threshold values.
TL;DR: Perfusion CT provides useful information for glioma grading and might have the potential to significantly impact clinical management and follow-up of cerebral gliomas.
Abstract: Regional cerebral blood volume (rCBV) and permeability surfaces (rPS) permit in vivo assessment of glioma microvasculature, which provides quite important pathophysiological information in grading gliomas. The aim of our study was to simultaneously examine rCBV and rPS in glioma patients to determine their correlation with histological grade using CT perfusion imaging. A total of 22 patients with gliomas underwent multislice CT perfusion imaging preoperatively. Low-grade and high-grade groups were categorized corresponding to WHO grade II gliomas and WHO grade III or IV gliomas, respectively, as determined by histopathological examination. rCBVs and rPSs were obtained from regions of maximal abnormality in tumor parenchyma on CBV and PS color perfusion maps. Perfusion parameters were compared using the Kruskal-Wallis test in order to evaluate the differences in relation to tumor grade. The Pearson coefficients of rCBV and rPS for each tumor grade were assessed using SPSS 13.0 software. rCBV and rPS provided significant P-value in differentiating glioma grade (low-grade gliomas 3.28±2.01 vs 2.12±3.19 ml/100 g/min, high-grade gliomas 8.87±4.63 vs 12.11±3.18 ml/100 g/min, P<0.05). Receiver operating characteristic (ROC) curves revealed better specificity and sensitivity in PS than in CBV for glioma grade. A significant correlation between rCBV and rPS was observed in high-grade gliomas (r=0.684). rCBVs in oligodendrogliomas were higher than in other low-grade gliomas, whereas their rPS values did not show a parallel difference. Perfusion CT provides useful information for glioma grading and might have the potential to significantly impact clinical management and follow-up of cerebral gliomas.
TL;DR: Investigation of perfusion changes in parkinsonian patients with visual hallucinations using single photon emission computed tomography imaging suggested that hypoperfusion of the visual pathway was closely related to visual hallucinations in Parkinson's disease.
Abstract: Little is known about the developing mechanisms of visual hallucinations in Parkinson's disease. This study aimed to investigate perfusion changes in parkinsonian patients with visual hallucinations using n-isopropyl-p-[123I]iodoamphetamine ([123I]IMP) single photon emission computed tomography imaging. A total of 70 consecutive patients, including 31 patients with visual hallucinations, and 39 patients without hallucinations, participated in this study. Patients with severe cognitive impairment (Mini-Mental State Examination score < 20), nonvisual hallucinations, or confusion were excluded. We compared brain perfusion changes between the two groups. We found that hallucinatory patients had significant perfusion reductions in the bilateral inferior parietal lobule, inferior temporal gyrus, precuneus gyrus, and occipital cortex compared to nonhallucinatory patients. These results suggested that hypoperfusion of the visual pathway was closely related to visual hallucinations in Parkinson's disease. © 2006 Movement Disorder Society
TL;DR: In this paper, the authors evaluated whether perfusion-weighted MR imaging (PWI) could usefully implement the routine preoperative imaging by detecting those areas bearing a higher yield for malignancy.
Abstract: Object. Biopsy targeting based on MR imaging alone may fail to identify malignant areas in brain gliomas. Considering the differences in relative Cerebral Blood Volume (rCBV) ratios reported among tumour grades, we evaluated whether perfusion-weighted MR imaging (PWI) could usefully implement the routine preoperative imaging by detecting those areas bearing a higher yield for malignancy to guide the stereotactic biopsy or the surgical removal. Clinical material and methods. We studied a series of 55 consecutive patients with newly diagnosed brain glioma using both conventional MR imaging and PWI in the preoperative assessment. The pathological diagnosis was established by stereotactic biopsy in 29 cases and by craniotomy in 24 cases. We evaluated the patient survival to detect undergrading. Discussion. Independent from contrast-enhancement, perfusion-weighted MR imaging improved the target selection in stereotactic biopsy guidance and the removal of malignant areas in tumours amenable to surgery. Particularly sensitive to the perfused part of the tumour as to small regional changes, rCBV maps allowed a better detection of malignant areas. The rCBV ratios correlated significantly to the tumour grade and the final outcome (p < 0.01). Conclusions. We found PWI valuable in the preoperative assessment of brain gliomas, discriminating high from low-grade gliomas. PWI can easily be performed on widely available MR imaging systems as part of the routine imaging of gliomas.
TL;DR: CUPI reflects the regional blood circulation of the calf muscle and shows a significantly longer TTP than control subjects, and is of clinical relevance for patients with peripheral arterial disease.
Abstract: Aims The purpose of this study was to establish contrast-enhanced ultrasound perfusion imaging (CUPI) of the lower extremities as a novel non-invasive diagnostic tool for patients with peripheral arterial disease (PAD).
Methods and results Ultrasound contrast agent (SonoVue™) was injected into a peripheral vein of 16 control subjects and 16 PAD patients and its appearance in the calf muscle was detected by low-energy harmonic ultrasound. Analysis of the wash-in curves revealed that PAD patients had a significantly longer time to peak intensity (TTP), i.e. duration of maximum contrast perfusion [37 s (19–79 s) in control subjects vs. 56 s (32–104 s) in PAD patients at rest, age-adjusted P =0.002]. Exercise stress test of the calf muscle resulted in a decrease of the TTP, maintaining the significant difference in TTP between the groups [19 s (8–37 s) in control subjects vs. 32 s (18–48 s) in PAD patients after exercise, age-adjusted P =0.004]. Neither ankle-brachial index and TTP nor age and TTP showed a significant correlation.
Conclusion CUPI reflects the regional blood circulation of the calf muscle. In this pilot study, PAD patients show a significantly longer TTP than control subjects. The clinical relevance of CUPI is topic of ongoing studies.
TL;DR: By exploiting the ability of CT systems to quantify contrast enhancement, CT perfusion imaging uses contrast media to assess vascular physiology and so improve diagnosis, prognosis, treatment selection and therapy monitoring.
Abstract: The availability of rapid imaging with multidetector CT systems and commercial analysis software has made perfusion imaging with CT an everyday technique, not only for the brain but also for other body organs. Perfusion imaging is usually performed as an adjunct to a conventional CT examination and is therefore particularly appropriate when a conventional CT is part of routine clinical protocols. The derived values are reproducible and have been validated against a range of reference techniques. Within neuroradiology, perfusion CT has attracted interest in the assessment of acute stroke but can also be used to assess secondary injury in head trauma and as an adjunct to CT angiography to evaluate cerebral spasm in subarachnoid haemorrhage. Within oncology, perfusion CT provides an imaging correlate for tumour vascularity that can be used to discriminate benign and malignant lesions, as an indicator of tumour aggressiveness, to reveal occult tumour and improve the delineation of tumours during radiotherapy planning, and as a functional assessment of tumour response to therapy. By exploiting the ability of CT systems to quantify contrast enhancement, CT perfusion imaging uses contrast media to assess vascular physiology and so improve diagnosis, prognosis, treatment selection and therapy monitoring.