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Showing papers on "Perfusion scanning published in 2010"


Journal ArticleDOI
TL;DR: Results demonstrate the persistent effects of cognitive fatigue in the fronto-parietal network after a period of heavy mental work and indicate the critical role of this attentional network in mediating time-on-task (TOT) effects.

349 citations


Journal ArticleDOI
TL;DR: Cardiac hybrid PET/CT imaging allows accurate noninvasive detection of coronary artery disease in a symptomatic population and is feasible and can be performed routinely with <10 mSv in most patients.
Abstract: Background—Computed tomography (CT) is increasingly used to detect coronary artery disease, but the evaluation of stenoses is often uncertain. Perfusion imaging has an established role in detecting ischemia and guiding therapy. Hybrid positron emission tomography (PET)/CT allows combination angiography and perfusion imaging in short, quantitative, low-radiation-dose protocols. Methods and Results—We enrolled 107 patients with an intermediate (30% to 70%) pretest likelihood of coronary artery disease. All patients underwent PET/CT (quantitative PET with 15 O-water and CT angiography), and the results were compared with the gold standard, invasive angiography, including measurement of fractional flow reserve when appropriate. Although PET and CT angiography alone both demonstrated 97% negative predictive value, CT angiography alone was suboptimal in assessing the severity of stenosis (positive predictive value, 81%). Perfusion imaging alone could not always separate microvascular disease from epicardial stenoses, but hybrid PET/CT significantly improved this accuracy to 98%. The radiation dose of the combined PET and CT protocols was 9.3 mSv (86 patients) with prospective triggering and 21.8 mSv (21 patients) with spiral CT. Conclusion—Cardiac hybrid PET/CT imaging allows accurate noninvasive detection of coronary artery disease in a symptomatic population. The method is feasible and can be performed routinely with 10 mSv in most patients. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00627172. (Circulation. 2010;122:603-613.)

341 citations


Journal ArticleDOI
TL;DR: CT perfusion imaging maps were significantly different among commercial software even when using identical source data, presumably because of differences in tracer-delay sensitivity.
Abstract: The abnormal area and relative values of CT perfusion imaging were significantly different among commercially available software packages provided by CT manufacturers.

298 citations


Journal ArticleDOI
TL;DR: Patients and medical professionals are scrutinizing the need for diagnostic testing and how radiation exposure can be reduced and there are three critical questions that physicians must consider and answer with regard to radiation exposure and performing MPI in a particular patient.

276 citations


Journal ArticleDOI
TL;DR: DWI is established as useful and should be considered more useful than noncontrast CT for the diagnosis of acute ischemic stroke within 12 hours of symptom onset and the diagnostic accuracy of DWI in evaluating cerebral hemorrhage is outside the scope of this guideline.
Abstract: Objective: To assess the evidence for the use of diffusion-weighted imaging (DWI) and perfusionweighted imaging (PWI) in the diagnosis of patients with acute ischemic stroke. Methods: We systematically analyzed the literature from 1966 to January 2008 to address the diagnostic and prognostic value of DWI and PWI. Results and Recommendations: DWI is established as useful and should be considered more useful than noncontrast CT for the diagnosis of acute ischemic stroke within 12 hours of symptom onset. DWI should be performed for the most accurate diagnosis of acute ischemic stroke (Level A); however, the sensitivity of DWI for the diagnosis of ischemic stroke in a general sample of patients with possible acute stroke is not perfect. The diagnostic accuracy of DWI in evaluating cerebral hemorrhage is outside the scope of this guideline. On the basis of Class II and III evidence, baseline DWI volumes probably predict baseline stroke severity in anterior territory stroke (Level B) but possibly do not in vertebrobasilar artery territory stroke (Level C). Baseline DWI lesion volumes probably predict (final) infarct volumes (Level B) and possibly predict early and late clinical outcome measures (Level C). Baseline PWI volumes predict to a lesser degree the baseline stroke severity compared with DWI (Level C). There is insufficient evidence to support or refute the value of PWI in diagnosing acute ischemic stroke (Level U). Neurology ® 2010;75:177–185

269 citations


Journal ArticleDOI
TL;DR: The data suggest that pcASL provides a reliable whole brain CBF measurement in young and elderly adults whose results converge with those obtained with the traditional 15O‐water PET perfusion imaging method.
Abstract: Arterial spin labeling (ASL) offers MRI measurement of cerebral blood flow (CBF) in vivo, and may offer clinical diagnostic utility in populations such as those with early Alzheimer's disease (AD). In the current study, we investigated the reliability and precision of a pseudo-continuous ASL (pcASL) sequence that was performed two or three times within one hour on eight young normal control subjects, and 14 elderly subjects including 11 with normal cognition, one with AD and two with Mild Cognitive Impairment (MCI). Six of these elderly subjects including one AD, two MCIs and three controls also received (15)O-water positron emission tomography (PET) scans 2 h before their pcASL MR scan. The instrumental reliability of pcASL was evaluated with the intraclass correlation coefficient (ICC). The ICCs were greater than 0.90 in pcASL global perfusion measurements for both the young and the elderly groups. The cross-modality perfusion imaging comparison yielded very good global and regional agreement in global gray matter and the posterior cingulate cortex. Significant negative correlation was found between age and the gray/white matter perfusion ratio (r = -0.62, p < 0.002). The AD and MCI patients showed the lowest gray/white matter perfusion ratio among all the subjects. The data suggest that pcASL provides a reliable whole brain CBF measurement in young and elderly adults whose results converge with those obtained with the traditional (15)O-water PET perfusion imaging method. pcASL perfusion MRI offers an alternative method for non-invasive in vivo examination of early pathophysiological changes in AD.

261 citations


Journal ArticleDOI
TL;DR: A combination protocol involving adenosine perfusion CT imaging and cardiac CT Angiography in a dual-source technique is feasible, and CT perfusion adds incremental value to cardiac CT angiographic in the detection of significant CAD.
Abstract: A combined dual-source CT protocol for assessment of myocardial perfusion and coronary anatomy is feasible, with acceptable contrast material and radiation doses; moreover, the addition of myocardial stress perfusion CT improves the diagnostic accuracy of cardiac CT angiography and enables simultaneous assessment of anatomy and perfusion in a single examination.

224 citations


Journal ArticleDOI
TL;DR: This work tested the hypothesis that acute stroke magnetic resonance imaging (MRI) predicts MMI within 6 hours of stroke onset and found it to be true.
Abstract: Objective Early identification of patients at risk of space-occupying “malignant” middle cerebral artery (MCA) infarction (MMI) is needed to enable timely decision for potentially life-saving treatment such as decompressive hemicraniectomy. We tested the hypothesis that acute stroke magnetic resonance imaging (MRI) predicts MMI within 6 hours of stroke onset. Methods In a prospective, multicenter, observational cohort study patients with acute ischemic stroke and MCA main stem occlusion were studied by MRI including diffusion-weighted imaging (DWI), perfusion imaging (PI), and MR-angiography within 6 hours of symptom onset. Multivariate regression analysis was used to identify clinical and imaging predictors of MMI. Results Of 140 patients included, 27 (19.3%) developed MMI. The following parameters were identified as independent predictors of MMI: larger acute DWI lesion volume (per 1 ml odds ratio [OR] 1.04, 95% confidence interval [CI] 1.02–1.06; p 82 ml predicted MMI with high specificity (0.98, 95% CI 0.94–1.00), negative predictive value (0.90, 0.83–0.94), and positive predictive value (0.88, 0.62–0.98), but sensitivity was low (0.52, 0.32–0.71). Interpretation Stroke MRI on admission predicts malignant course in severe MCA stroke with high positive and negative predictive value and may help in guiding treatment decisions, such as decompressive surgery. In a subset of patients with small initial DWI lesion volumes, repeated diagnostic tests are required. ANN NEUROL 2010

202 citations


Journal ArticleDOI
TL;DR: The results support that additional rest imaging is not required in patients who have a normally appearing initial stress study, and support that a significant reduction in radiation exposure can be achieved with such an approach.

199 citations


Journal ArticleDOI
TL;DR: Quantitative PR by CMR differentiates moderate from severe stenoses in patients with known or suspected CAD, whereas QI does not, and determines the severity of CAS subtending myocardial scar.

159 citations


Journal ArticleDOI
TL;DR: PC ASL is an alternative to DSC-MRI for the evaluation of perfusion in brain tumours and can be used in patients with renal failure because no contrast injection is needed.
Abstract: Introduction The purpose of this study was to compare the non-invasive 3D pseudo-continuous arterial spin labelling (PC ASL) technique with the clinically established dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC-MRI) for evaluation of brain tumours.

Journal ArticleDOI
TL;DR: The current status of functional renal imaging with focus on DWI and DCE-MRI (dynamic contrast-enhanced MRI), as well as BOLD (blood-oxygenation level dependent) MRI, DTI (diffusion tensor imaging) and arterial spin labeling (ASL).

Journal ArticleDOI
TL;DR: Adenosine-stress volumetric first pass CT perfusion imaging is feasible and may enable the evaluation of qualitative and semi quantitative parameters of myocardial perfusion in a comparable fashion as MRI.
Abstract: Objective To evaluate the feasibility of adenosine-stress dynamic myocardial volume perfusion imaging with second generation dual source computed tomography (CT) for the qualitative and quantitative assessment of myocardial blood flow (MBF) compared with stress perfusion and viability magnetic resonance imaging (MRI). Material and methods Ten patients (8 male, 2 female, mean age 62.7 +/- 7.1 years) underwent stress/rest perfusion and delayed-enhancement MRI, and a cardiac CT protocol comprising prospectively electrocardiogram -triggered coronary CT angiography, dynamic adenosine-stress myocardial perfusion imaging using a "shuttle" mode, and delayed enhancement acquisitions. Two independent observers visually assessed myocardial perfusion defects. For semi-quantitative evaluation, CT- and MRI-derived myocardial-to-left ventricular upslope indices were compared. Additionally, absolute MBF was quantified based on dynamic perfusion CT and correlated with semi quantitative CT measurements. Myocardial perfusion analysis was performed on a segmental basis. Analysis used paired t tests, Wilcoxon signed-rank test, linear correlation, and Bland-Altman statistics. Results A total of 149 segments (93.1%) were suitable for analysis. Sensitivity, specificity, positive and negative predictive values for detection of myocardial perfusion defects at CT compared with MRI were 86.1%, 98.2%, 93.9%, and 95.7%, respectively. Semiquantitative analysis of CT data showed significant differences between ischemic and nonischemic myocardium with a signal intensity upslope that was comparable with MRI-derived values (CT: 5.2 +/- 2 SI/s, MRI: 4.8 +/- 2.3 SI/s, P > 0.05). Moderate correlation was observed between absolute CT quantification of MBF and semi-quantitative CT measurements. Mean total dose length product for the entire cardiac CT protocol was 1290.4 +/- 233.3 mGy cm. Conclusion Adenosine-stress volumetric first pass CT perfusion imaging is feasible and may enable the evaluation of qualitative and semi quantitative parameters of myocardial perfusion in a comparable fashion as MRI.

Journal ArticleDOI
TL;DR: An overview of the physical and biological principles behind PET imaging and its main clinical applications in cardiology, namely the assessment of MBF and metabolism is provided.
Abstract: In developed countries, coronary artery disease (CAD) continues to be a major cause of death and disability. Over the past two decades, positron emission tomography (PET) imaging has become more widely accessible for the management of ischemic heart disease. Positron emission tomography has also emerged as an important alternative perfusion imaging modality in the context of recent shortages of molybdenum-99/technetium-99m ((99m)Tc). The clinical application of PET in ischaemic heart disease falls into two main categories: first, it is a well-established modality for evaluation of myocardial blood flow (MBF); second, it enables assessment of myocardial metabolism and viability in patients with ischaemic left ventricular dysfunction. The combined study of MBF and metabolism by PET has led to a better understanding of the pathophysiology of ischaemic heart disease. While there are potential future applications of PET for plaque and molecular imaging, as well as some clinical use in inflammatory conditions, this article provides an overview of the physical and biological principles behind PET imaging and its main clinical applications in cardiology, namely the assessment of MBF and metabolism.

Journal ArticleDOI
TL;DR: Renal carcinoma perfusion parameters determined with dynamic contrast-enhanced CT can help predict biologic response to antiangiogenic drugs before beginning therapy and help detect an effect after a single cycle of treatment.
Abstract: Perfusion parameters such as tumor blood flow and tumor blood volume calculated from dynamic contrast-enhanced CT in patients with metastatic renal carcinoma may serve as biomarkers for detecting tumor response to antiangiogenic therapies.

Journal ArticleDOI
TL;DR: An incremental stroke protocol that includes CT perfusion increases diagnostic performance for stroke diagnosis and inter- and intraobserver agreement.
Abstract: CT perfusion improves stroke diagnosis by relatively inexperienced readers over that achieved with noncontrast CT alone or a combination of noncontrast CT and CT angiography, with improved inter- and intraobserver agreement.

Journal ArticleDOI
TL;DR: Optical microangiography is a recently developed volumetric imaging technique that is capable of producing 3-D images of dynamic blood perfusion within microcirculatory tissue beds in vivo and its recent developments that use a constant modulation frequency introduced in the spectral interferograms to achieve the blood perfusions imaging are discussed.
Abstract: Optical microangiography (OMAG) is a recently developed volumetric imaging technique that is capable of producing 3-D images of dynamic blood perfusion within microcirculatory tissue beds in vivo . The imaging contrast of OMAG image is based on the intrinsic optical scattering signals backscattered by the moving blood cells in patent blood vessels, thus, it is a label-free imaging technique. In this paper, I will first discuss its recent developments that use a constant modulation frequency introduced in the spectral interferograms to achieve the blood perfusion imaging. I will then introduce its latest development that utilizes the inherent blood flow to modulate the spectral interferograms to realize the blood perfusion imaging. Finally, examples of using OMAG to delineate the dynamic blood perfusion, down to capillary level resolution, within living tissues are given, including cortical blood perfusion in the brain of small animals and blood flow within human retina and choroids.

Journal ArticleDOI
TL;DR: Application of the BHC algorithm is helpful for improving accuracy of myocardial perfusion at dynamic volume CT and to validate a beam-hardening artifact correction algorithm that considers fluid-filled vessels and chambers important sources of beam hardening.
Abstract: Application of a cardiac-specific beam-hardening correction software algorithm is helpful for improving accuracy of myocardial perfusion at dynamic volume CT

Journal ArticleDOI
TL;DR: In this paper, remote ischemic conditioning (rIC) was shown to increase the myocardial salvage in patients with ST-segment elevation mycardial infarction (STEMI) and extensive myocardia area at risk (AAR).
Abstract: Background— We have found that remote ischemic conditioning (rIC), adjunctive to primary angioplasty, increases myocardial salvage in patients with ST-segment elevation myocardial infarction (STEMI) and extensive myocardial area at risk (AAR). The present substudy aimed to evaluate the short-term effects of rIC on left ventricular (LV) function. Methods and Results— Patients with a first STEMI were randomized to rIC (4 cycles of 5 minutes upper-limb ischemia) during transfer to primary percutaneous coronary intervention (pPCI) (n=123) versus pPCI alone (n=119). Ejection fraction (EF), LV volumes, (2D and 3D echocardiography and myocardial perfusion imaging), and speckle-tracking global longitudinal strain were compared between treatment groups. There was no significant difference in LV function at day 1 (EF-2D, 0.51±0.10 versus 0.49±0.10; P =0.22) and after 30 days (EF-2D, 0.54±0.08 versus 0.53±0.10) between the rIC and the pPCI-alone groups. In patients with extensive AAR ≥35% of LV (n=53), EF after 30 days was higher after rIC than after pPCI alone (EF-2D, 0.51±0.07 versus 0.46±0.09; P =0.05). In patients with anterior infarction (n=97), rIC preserved LV function on day 1 (EF-2D, 0.51±0.11 versus 0.46±0.11; P =0.03) and persistently after 30 days (EF-2D, 0.55±0.08 versus 0.50±0.11; P =0.04; EF-myocardial perfusion imaging, 0.55±0.10 versus 0.49±0.12; P =0.02). These patients had similar AAR, whereas rIC reduced infarct size from 16% to 7% of LV ( P =0.01). Conclusions— Although no significant overall effect was observed, rIC seemed to result in modest improvement in LV function in high-risk patients prone to develop large myocardial infarcts. These results need to be confirmed in larger trials. Clinical Trial Registration— URL: . Unique identifier: [NCT00435266][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00435266&atom=%2Fcirccvim%2F3%2F6%2F656.atom

Journal ArticleDOI
TL;DR: In pre-SIRT planning, 99mTc-MAA SPECT/CT is valuable for identifying extrahepatic visceral sites at risk for postradioembolization complications.
Abstract: Selective internal radiation therapy (SIRT), a catheter-based liver-directed modality for treating primary and metastatic liver cancer, requires appropriate planning to maximize its therapeutic response and minimize its side effects. 99mTc-macroaggregated albumin (MAA) scanning should precede the therapy to detect any extrahepatic shunting to the lung or gastrointestinal tract. Our aim was to compare the ability of SPECT/CT with that of planar imaging and SPECT in the detection and localization of extrahepatic 99mTc-MAA accumulation and to evaluate the impact of SPECT/CT on SIRT treatment planning and its added value to angiography in this setting. Methods: Ninety diagnostic hepatic angiograms with 99mTc-MAA were obtained for 76 patients with different types of cancer. All images were reviewed retrospectively for extrahepatic MAA deposition in the following order: planar, non–attenuation-corrected SPECT, and SPECT/CT. Review of angiograms and follow-up of patients with abdominal shunting served as reference standards. Results: Extrahepatic accumulation was detected by planar imaging, SPECT, and SPECT/CT in 12%, 17%, and 42% of examinations, respectively. The sensitivity for detecting extrahepatic shunting with planar imaging, SPECT, and SPECT/CT was 32%, 41%, and 100%, respectively; specificity was 98%, 98%, and 93%, respectively. The respective positive predictive values were 92%, 93%, and 89%, and the respective negative predictive values were 71%, 73%, and 100%. The therapy plan was changed according to the results of planar imaging, SPECT, and SPECT/CT in 7.8%, 8.9%, and 29% of patients, respectively. Conclusion: In pre-SIRT planning, 99mTc-MAA SPECT/CT is valuable for identifying extrahepatic visceral sites at risk for postradioembolization complications.

Journal ArticleDOI
TL;DR: Normal and ischemic perfusion patterns are reviewed followed by an illustrative series of technical/diagnostic challenges of CTP interpretation in the setting of acute stroke syndromes.
Abstract: CTP has a growing role in evaluating stroke. It can be performed immediately following NCCT and has advantages of accessibility and speed. Differentiation of salvageable ischemic penumbra from unsalvageable core infarct may help identify patients most likely to benefit from thrombectomy or thrombolysis. Still, CTP interpretation can be complex. We review normal and ischemic perfusion patterns followed by an illustrative series of technical/diagnostic challenges of CTP interpretation in the setting of acute stroke syndromes.

Journal ArticleDOI
TL;DR: On October 8, 2009, the US Food and Drug Administration issued an initial notification regarding a safety investigation of facilities performing brain perfusion CT (PCT) scans that indicated that the FDA had become aware of radiation overexposures during PCT imaging performed to.
Abstract: On October 8, 2009, the US Food and Drug Administration (FDA) issued an initial notification regarding a safety investigation of facilities performing brain perfusion CT (PCT) scans. This alert indicated that the FDA had become aware of radiation overexposures during PCT imaging performed to

Journal ArticleDOI
TL;DR: This pilot study derived an imaging metric (HPV) that reflects local perfusion changes in GBMs that was found to show a significantly improved correlation to TTP as compared with more commonly used metrics.
Abstract: In this pilot study, we have derived an imaging metric (hyperperfusion volume) that reflects local perfusion changes in glioblastomas and have found that this metric has significantly improved correlation to time to progression as compared with more commonly used metrics.

Journal ArticleDOI
TL;DR: CT pulmonary angiography and perfusion scanning have equivalent clinical negative predictive value and image quality in the care of pregnant patients and the choice of study should be based on other considerations, such as radiation concern, radiographic results, alternative diagnosis, and equipment availability.
Abstract: OBJECTIVE. The purpose of this study was to evaluate the equivalence of CT pulmonary angiography and perfusion scanning in terms of diagnostic quality and negative predictive value in the imaging of pulmonary embolism (PE) in pregnancy.MATERIALS AND METHODS. Between 2000 and 2007 at a university hospital and a large private hospital, 199 pregnant patients underwent 106 CT pulmonary angiographic examinations and 99 perfusion scans. Image quality was evaluated, and the findings were reread by radiologists and compared with the original clinical readings. Three-month follow-up findings of PE and deep venous thrombosis were recorded.RESULTS. PE was found in four of the 106 patients (3.7%) who underwent CT pulmonary angiography. The overall image quality was poor in 5.6% of cases, acceptable in 17.9%, and good in 76.4%. Fourteen CT and nine radiographic studies showed other clinically significant abnormalities. Six patients had indeterminate CT pulmonary angiographic findings, three had normal perfusion scans,...

Journal ArticleDOI
TL;DR: In this paper, the authors used contrast-enhanced multidetector CT to predict voltage-defined scar and border zone and integrate its scar reconstructions into clinical mapping systems to guide ventricular tachycardia ablations.
Abstract: Background— Advances in contrast-enhanced multidetector CT enable detailed characterization of the left ventricular myocardium. Myocardial scar and border zone (BZ), as the target of ventricular tachycardia ablations, displays abnormal anatomic, dynamic, and perfusion characteristics during first-pass CT. This study assessed how contrast-enhanced CT can predict voltage-defined scar and BZ and integrate its scar reconstructions into clinical mapping systems to guide ventricular tachycardia ablations. Methods and Results— Eleven patients with ischemic cardiomyopathy underwent contrast-enhanced CT before ventricular tachycardia ablation. Segmental anatomic (end-systolic and end-diastolic wall thickness), dynamic (wall thickening, wall motion), and perfusion (hypoenhancement) characteristics were evaluated. Receiver operating characteristic curves assessed the ability of CT to determine voltage-defined scar and BZ segments. Three-dimensional epi- and endocardial surfaces and scar borders were reconstructed, coregistered, and compared to voltages using a 17-segment model. Abnormal anatomic, dynamic, and perfusion data correlated well with abnormal (<1.5 mV) endocardial voltages ( r =0.77). Three-dimensional reconstruction integrated into the clinical mapping system (registration accuracy, 3.31±0.52 mm) allowed prediction of homogenous abnormal voltage (<1.5 mV) in 81.7% of analyzed segments and correctly displayed transmural extent and intramural scar location. CT hypoperfusion correlated best with scar and BZ areas and encompassed curative ablations in 82% cases. Conclusions— Anatomic, dynamic, and perfusion imaging using contrast-enhanced CT allows characterization of left ventricular anatomy and 3D scar and BZ substrate. Integration of reconstructed 3D data sets into clinical mapping systems supplements information of voltage mapping and may enable new image approaches for substrate-guided ventricular tachycardia ablation.

Journal ArticleDOI
TL;DR: Preliminary results on 400 patients with 1,096 DCE-US demonstrated that AUC could be a robust parameter to predict response, and the technique is supported by the French National Cancer Institute.
Abstract: Dynamic contrast-enhanced ultrasonography (DCE-US) is a new functional technique enabling a quantitative assessment of solid tumor perfusion using raw linear data. DCE-US allows the calculation of parameters as slope of wash-in or area under the curve (AUC) representing, respectively, blood flow or blood volume. Reduction in tumor vascularization can easily be detected in responders after 1 or 2 weeks and is correlated with progression-free survival and overall survival in renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC). DCE-US is supported by the French National Cancer Institute (INCa), which is currently studying the technique in metastatic breast cancer, melanoma, colon cancer, gastrointestinal stromal tumors and renal cell carcinoma, as well as in primary hepatocellular carcinoma, to establish the optimal perfusion parameters and timing for quantitative anticancer efficacy assessments. Currently 490 patients are included in 20 centers and the preliminary results on 400 patients with 1,096 DCE-US demonstrated that AUC could be a robust parameter to predict response.

Journal ArticleDOI
TL;DR: Three-dimensional perfusion imaging allows a significant reduction in the error caused by transducer positioning, and significantly improves the reliability of quantitative perfusion time estimates in a rat kidney model.
Abstract: Objectives:Contrast-enhanced ultrasound imaging has demonstrated significant potential as a noninvasive technology for monitoring blood flow in the microvasculature. With the application of nondestructive contrast imaging pulse sequences combined with a clearance-refill approach, it is possible to c

Journal ArticleDOI
TL;DR: A functional lung-imaging measure that provides a more mechanistically oriented phenotype that differentiates smokers with and without evidence of emphysema susceptibility is demonstrated.
Abstract: Recent evidence suggests that endothelial dysfunction and pathology of pulmonary vascular responses may serve as a precursor to smoking-associated emphysema. Although it is known that emphysematous destruction leads to vasculature changes, less is known about early regional vascular dysfunction which may contribute to and precede emphysematous changes. We sought to test the hypothesis, via multidetector row CT (MDCT) perfusion imaging, that smokers showing early signs of emphysema susceptibility have a greater heterogeneity in regional perfusion parameters than emphysema-free smokers and persons who had never smoked (NS). Assuming that all smokers have a consistent inflammatory response, increased perfusion heterogeneity in emphysema-susceptible smokers would be consistent with the notion that these subjects may have the inability to block hypoxic vasoconstriction in patchy, small regions of inflammation. Dynamic ECG-gated MDCT perfusion scans with a central bolus injection of contrast were acquired in 17 NS, 12 smokers with normal CT imaging studies (SNI), and 12 smokers with subtle CT findings of centrilobular emphysema (SCE). All subjects had normal spirometry. Quantitative image analysis determined regional perfusion parameters, pulmonary blood flow (PBF), and mean transit time (MTT). Mean and coefficient of variation were calculated, and statistical differences were assessed with one-way ANOVA. MDCT-based MTT and PBF measurements demonstrate globally increased heterogeneity in SCE subjects compared with NS and SNI subjects but demonstrate similarity between NS and SNI subjects. These findings demonstrate a functional lung-imaging measure that provides a more mechanistically oriented phenotype that differentiates smokers with and without evidence of emphysema susceptibility.

Journal ArticleDOI
TL;DR: Robust technique and accurate data analysis are required for reliable computed tomography perfusion (CTp) imaging and free breathing is adequate for CTp imaging of the head, neck and pelvis.
Abstract: Robust technique and accurate data analysis are required for reliable computed tomography perfusion (CTp) imaging. Multislice CT is required for high temporal resolution scanning; 16-slice (or 64-slice) scanners are preferred for adequate volume coverage. After tumour localization, the volume of CTp imaging has to be positioned to include the maximum visible area of the tumour and an adequate arterial vessel. Dynamic scans at high temporal resolution (at least 1-s gantry rotation time) are performed to visualize the first pass of contrast agent within the tumour; repeated scans with low temporal resolution can be planned for late enhancement assessment. A short bolus of conventional iodinated contrast agent, preferably with high iodine concentration, is power injected at a high flow rate (>4 ml/s) in the antecubital vein. The breath-hold technique is required for CTp imaging of the chest and upper abdomen to avoid respiratory motion; free breathing is adequate for CTp imaging of the head, neck and pelvis. Using dedicated software, a region of interest (ROI) has to be placed in an adequate artery (as arterial input) to obtain density-time curves; according to different kinetic models, colour maps of different CTp parameters are generated and generally overlaid on CT images. Additional ROIs can be positioned in the tumour, and in all other parts of the CTp volume, to obtain the values of the CTp parameters within the ROI.

Journal ArticleDOI
TL;DR: Dual-modality simultaneous imaging or multimodal sequential imaging techniques facilitate integration of information on both myocardial perfusion and coronary anatomy, and thus have the potential to improve diagnostic and prognostic evaluation, which could translate into improved care of patients.
Abstract: Advances in cardiovascular imaging have resulted in the development of multiple noninvasive techniques to evaluate myocardial perfusion and coronary anatomy, each of which has unique strengths and limitations. For example, CT angiography can directly visualize the presence of atherosclerosis, but the hemodynamic effect of many lesions identified by this technique is unknown. Alternatively, myocardial perfusion imaging enables a physiological assessment, but it may underestimate the extent of atherosclerosis in patients with multivessel disease. Dual-modality simultaneous imaging or multimodal sequential imaging techniques facilitate integration of information on both myocardial perfusion and coronary anatomy, and thus have the potential to improve diagnostic and prognostic evaluation, which could translate into improved care of patients. This Review discusses the strengths and limitations of the currently available individual noninvasive techniques for imaging coronary anatomy and myocardial perfusion. Approaches to integration of these imaging modalities are described, followed by an exploration of the clinical utility and future directions of hybrid imaging.