Reverse Mismatch Research Articles

Determinants and Prognoses of Visual-Functional Mismatches After Mechanical Reperfusion in ST-Elevation Myocardial Infarction.

Discordance between the anatomy and physiology of the coronary has important implications for managing patients with stable coronary disease, but its significance in ST-elevation myocardial infarction has not been fully elucidated. The retrospective study involved patients diagnosed with ST-elevation myocardial infarction (STEMI) who underwent percutaneous coronary intervention (PCI), along with quantitative coronary angiography (QCA) and quantitative flow ratio (QFR) assessments. Patients were stratified into four groups regarding the severity of the culprit vessel, both visually and functionally: concordantly negative (QCA-diameter stenosis [DS] ≤ 50% and QFR > 0.80), mismatch (QCA-DS > 50% and QFR > 0.80), reverse mismatch (QCA-DS ≤ 50% and QFR ≤ 0.80), and concordantly positive (QCA-DS > 50% and QFR ≤ 0.80). Multivariable logistic regression analyses were conducted to identify the clinical factors linked to visual-functional mismatches. Kaplan‒Meier analysis was conducted to estimate the 18-month adverse cardiovascular events (MACE)-free survival between the four groups. The study involved 310 patients, with 68 presenting visual-functional mismatch, and 51 exhibiting reverse mismatch. The mismatch was associated with higher angiography-derived microcirculatory resistance (AMR) (adjusted odds ratio [aOR]=1.016, 95% CI: 1.010-1.022, P<0.001). Reverse mismatch was associated with larger area stenosis (aOR=1.044, 95% CI: 1.004-1.086, P=0.032), lower coronary flow velocity (aOR=0.690, 95% CI: 0.567-0.970, P<0.001) and lower AMR (aOR=0.947, 95% CI: 0.924-0.970, P<0.001). Additionally, the mismatch group showed the worst 18-month MACE-free survival among the four groups (Log rank test p = 0.013). AMR plays a significant role in the occurrence of visual-functional mismatches between QCA-DS and QFR, and the mismatch group showed the worst prognosis.

Unusual perfusion patterns on perfusion-only SPECT/CT scans in COVID-19 patients

PurposeWe aimed at examining both the incidence and extent of different lung perfusion abnormalities as well as the relationship between them on Tc-99m macroaggregated albumin (MAA) perfusion-only SPECT/CT scans in COVID-19 patients.MethodsNinety-one patients (71.4 ± 13.9 years; range: 29–98 years, median age: 74 years; 45 female and 46 male) with confirmed SARS-CoV-2 virus infection were included in this retrospective study. After performing perfusion-only Tc-99m MAA SPECT/CT scans, visual, semi-quantitative assessment of the subsequent perfusion abnormalities was carried out: mismatch lesions (MM; activity defects on SPECT images identical to apparently healthy parenchyma on CT images), matched lesions (MA; activity defects with corresponding parenchymal lesions on CT scans), and reverse mismatch lesions (RM; parenchymal lesions with preserved or increased tracer uptake). Lesion-based and patient-based analysis were performed to evaluate the extent, severity, and incidence of each perfusion abnormality. Statistical tests were applied to investigate the association between the experienced perfusion impairments.ResultsModerately severe parenchymal lesions were detected in 87 (95.6%) patients. Although, 50 (54.95%) patients were depicted to have MM lesions, the whole patient cohort was mildly affected by this abnormality. MA lesions of average moderate severity were seen in most of the patients (89.01%). In 65 (71.43%) patients RM lesions were found with mild severity on average. Positive association was detected between total CT score and total RM score and between total CT score and total MA score. Significantly higher total CT scores were experienced in the subgroup, where RM lesions were present.ConclusionsHeterogeneous perfusion abnormalities were found in most of COVID-19 patients: parenchymal lesions with normal, decreased or increased perfusion and perfusion defects in healthy lung areas. These phenomena may be explained by the failure of the hypoxic pulmonary vasoconstriction mechanism and presence of pulmonary thrombosis and embolism.

Absolute Resting 13N-Ammonia PET Myocardial Blood Flow for Predicting Myocardial Viability and Recovery of Ventricular Function after Coronary Artery Bypass Grafting

ObjectiveWe aimed to evaluate the feasibility of resting myocardial blood flow (rMBF), quantified with dynamic 13 N-Ammonia (NH3) PET, for identifying myocardial viability and predicting improvement of left ventricular ejection fraction (LVEF) after coronary artery bypass grafting (CABG). MethodsNinety-three patients with coronary artery disease (CAD) and chronic LVEF < 45%, scheduled for CABG, had dynamic 13NH3 PET and 18F-FDG PET imaging. The perfusion/metabolism polar maps were categorized in four patterns: normal (N), mismatch (M1), match (M2) and reverse mismatch (RM). The value of rMBF for identifying viable myocardium (M1, RM) and post CABG improvement of LVEF≥8% was analyzed by receiver operating characteristic (ROC) curves. Correlations of rMBF in segments to ΔLVEF post CABG were verified. ResultsMean rMBFs were significantly different (N=0.60±0.14; M1=0.44±0.07, M2=0.34±0.08, RM=0.53±0.09 ml/min/g, P<0.001). The optimal rMBF cutoff to identify viable myocardium was 0.42 ml/min/g (sensitivity=88.3%, specificity=82.0%) and 0.43 ml/min/g for predicting improvement of LVEF ≥8% (74.6%, 80.0%). The extent and rMBF of combined M1/RM demonstrated a moderate to high correlation to improved LVEF (r=0.78, 0.71, P<0.001). ConclusionResting MBF, derived by dynamic 13NH3 PET, may be positioned as a supplement to 18F-FDG PET imaging for assessing the presence of viable myocardium and predicting potential improvement of LVEF after CABG.

Impact of left bundle branch block on myocardial perfusion and metabolism: A positron emission tomography study

BackgroundBetter understanding of pathophysiological changes, induced by left bundle branch block (LBBB), may improve patient selection for cardiac resynchronization therapy (CRT). Therefore, we assessed the effect of LBBB on regional glucose metabolism, 13N-NH3-derived absolute and semiquantitative myocardial blood flow (MBF), and their relation in non-ischemic CRT candidates. MethodsTwenty-five consecutive non-ischemic patients with LBBB underwent 18F-FDG and resting dynamic 13N-NH3 PET/CT prior to CRT implantation. Regional 18F-FDG uptake, absolute MBF, and late 13N-NH3 uptake were analyzed and corresponding septal-to-lateral wall ratios (SLR) were calculated. Segmental analysis was performed to evaluate “reverse mismatch,” “mismatch,” and “match” patterns, based on late 13N-NH3/18F-FDG uptake ratios. ResultsA significantly lower 18F-FDG uptake was observed in the septum compared to the lateral wall (SLR 0.53 ± 0.17). A similar pattern was observed for MBF (SLR 0.68 ± 0.18), whereas late 13N-NH3 uptake showed a homogeneous distribution (SLR 0.96 ± 0.13). 13N-NH3/18F-FDG “mismatch” and “reverse mismatch” segments were predominantly present in the lateral (52%) and septal wall (61%), respectively. ConclusionsNon-ischemic CRT candidates with LBBB demonstrate lower glucose uptake and absolute MBF in the septum compared to the lateral wall. However, late static 13N-NH3 uptake showed a homogenous distribution, reflecting a composite measure of altered regional MBF and metabolism, induced by LBBB.

Anatomical-functional discordance between quantitative coronary angiography and diastolic pressure ratio during wave-free period.

This study sought to determine the predictors of anatomical-functional discordance between quantitative coronary angiography (QCA) derived diameter stenosis (QCA-DS) and diastolic pressure ratio during wave-free period (dPRWFP ). The discrepancy between angiographical stenosis and physiological significance is frequently experienced in clinical practice. Although the anatomical-functional discordance between angiography and fractional flow reserve (FFR) has been intensively investigated, that of resting index including dPRWFP remains to be elucidated. In a total of 647 angiographically intermediate lesions with QCA-DS between 30 and 70% in 502 patients, predictors of having QCA-DS >50% and dPRWFP > 0.89 (QCA-dPRWFP mismatch), and those of having QCA-DS ≤50% and dPRWFP ≤ 0.89 (QCA-dPRWFP reverse mismatch) were determined. FFR ≤0.80 was defined as positive FFR and the predictors of QCA-FFR discordance were determined as well. QCA-dPRWFP mismatch and reverse mismatch were observed in 27.5 and 17.6% of cases, respectively. The predictors of mismatch were non-left anterior descending artery (LAD) lesion, large minimal lumen diameter, low baseline heart rate, and high coronary flow reserve (CFR), while those of reverse mismatch were LAD lesion, non-culprit lesion of acute coronary syndrome, long lesion length, low left ventricular ejection fraction, and low CFR and index of microcirculatory resistance. Age, sex, and the culprit vessel of prior myocardial infarction were not significant determinants of QCA-dPRWFP discordance unlike QCA-FFR discordance derived from the same cohort. Anatomical-functional discordance between angiography and dPRWFP was not uncommon. Predictors differed between QCA-dPRWFP discordance and QCA-FFR discordance.

Determinants of visual-functional mismatches as assessed by coronary angiography and quantitative flow ratio.

We aimed to evaluate the determinants of visual-functional mismatches between quantitative coronary angiography (QCA) and the quantitative flow ratio (QFR). The fractional flow reserve (FFR) has been established as a method to estimate the functional stenosis severity of coronary artery disease and to optimize decision-making for revascularization. The QFR is a novel angiography-derived computational index that can estimate the FFR without pharmacologically induced hyperemia or the use of pressure wire. A total of 504 de novo intermediate-to-severe stable lesions that underwent angiographic and physiological assessments were analyzed. All lesions were divided into four groups based on the significance of visual (QCA-diameter stenosis [DS] > 50% and ≤ 50%) and functional (QFR ≤ 0.80 and > 0.80) stenosis severity. Patient characteristics, angiographic findings, and physiological indices were compared. One-hundred seventy-eight lesions (35.3%) showed discordant visual-functional assessments; mismatch (QCA-DS > 50% and QFR > 0.80) in 75 lesions (14.9%) and reverse mismatch (QCA-DS ≤ 50% and QFR ≤ 0.80) in 103 lesions (20.4%), respectively. Reverse mismatch was associated with non-diabetes, lower ejection fraction, higher Duke jeopardy score, and lower coronary flow reserve (CFR). Mismatch was associated with smaller QCA-DS, larger reference diameter, shorter lesion length, lower Duke jeopardy score, and higher CFR. Lesion location and microcirculatory resistance was not associated with the prevalence of mismatches. Reverse mismatch group had the higher prevalence of discordant decision-makings between QFR and FFR than the other three groups. The CFR and subtended myocardial mass were predictors of visual-functional mismatches between QCA-DS and the QFR. Caution should be exercised in lesions showing QCA-DS/QFR reverse mismatch.

Clinical significance of quantitative assessment of glucose utilization in patients with ischemic cardiomyopathy

BackgroundThe aim of this study was to prospectively quantify the rate of myocardial glucose uptake (MRGlu) in myocardium with different perfusion-metabolism patterns and determine its prognostic value in patients with ischemic cardiomyopathy. Methods and Results79 patients with ischemic cardiomyopathy were prospectively enrolled for dynamic cardiac FDG PET, and then followed for at least 6 months. Perfusion-metabolism patterns were determined based on visual score analysis of 201Tl SPECT and FDG PET. MRGlu was analyzed using the Patlak kinetic model. The primary end-point was cardiovascular mortality. Significantly higher MRGlu was observed in viable compared with non-viable areas. Negative correlations were found between MRGlu in transmural match and a history of hyperlipidemia, statin usage, and triglyceride levels. Diabetic patients receiving dipeptidyl peptidase-4 inhibitors (DPP4i) had a significantly lower MRGlu in transmural match, mismatch, and reverse mismatch. Patients with MRGlu in transmural match ≥ 23.40 or reverse mismatch ≥ 36.90 had a worse outcome. ConclusionsMyocardial glucose utilization was influenced by substrates and medications, including statins and DPP4i. MRGlu could discriminate between viable and non-viable myocardium, and MRGlu in transmural match and reverse mismatch may be prognostic predictors of cardiovascular death in patients with ischemic cardiomyopathy.

The salvageable brain in acute ischemic stroke. The concept of a reverse mismatch: a mini-review.

Recent studies have opened a new era in treatment of acute ischemic stroke, enabling thrombolysis or thrombectomy far beyond the standard therapeutic "time windows". These therapeutic protocols are built on various combinations of perfusion parameters, lesion volume, and neurological assessment. However, on top of the brain perfusion, there are other multiple factors that might modify the probability of neuronal apoptosis and necrosis following focal cerebral ischemia. We hypothesize that a diagnostic approach with measurements of selected biochemical parameters in the brain, in addition to those based solely on perfusion or MR diffusion, might allow for more personalized management protocols. Moreover, some local processes in the brain, triggered by acute ischemia or its consequences other than hypoperfusion directly, like, for example, excitotoxicity, might lead to apoptosis of the cells in the brain localized also beyond the area of hypoperfusion. This phenomenon might be responsible for the expansion of the brain damage much beyond the initial perfusion deficit or beyond the initial diffusion (DWI) restriction area, reported for example in T2W or FLAIR MRI in some stroke patients who have no other reasons to deteriorate (a reverse DWI - T2W / FLAIR, a reverse perfusion - DWI, or a reverse DWI - DWI mismatch).

P3578Determinants of visual-functional mismatches as assessed by coronary angiography and 3-D angiography-based quantitative flow ratio

Abstract Background Quantitative flow ratio (QFR) is a novel three-dimensional quantitative coronary angiography (QCA)-based computational index that can estimate fractional flow reserve (FFR) without pharmacologically induced hyperemia or the use of a pressure wire. Purpose We aimed to evaluate the determinants of visual-functional mismatches between conventional two-dimensional QCA and QFR. Methods A total of 504 de novo intermediate-to-severe lesions from 504 patients with stable angina who underwent angiographical and physiological assessments were analyzed. All lesions were divided into four groups based on the significance of visual (QCA-diameter stenosis [DS] &gt;50% and ≤50%) and functional (QFR &lt;0.80 and ≥0.80) stenosis severity. Patient characteristics, angiographic findings, QFR computations, and physiological indices were compared among the four groups. Results Among 504 lesions, 153 lesions (30.4%) showed concordantly negative (DS ≤50% and QFR &gt;0.80) and 170 lesions (33.7%) showed concordantly positive (DS &gt;50% and QFR ≤0.80) visual and functional assessments. Among 181 lesions (35.9%) with discordant results, 75 lesions (14.9%) showed a mismatch (DS &gt;50% and QFR &gt;0.80) and 106 lesions (21.0%) showed a reverse mismatch (DS ≤50% and QFR ≤0.80), respectively. Reverse mismatch was associated with smaller reference diameter (odds ratio [OR] 0.561; P=0.036), greater DS (OR 1.039, P=0.013), lower coronary flow reserve (CFR) (OR 0.571, P&lt;0.001, non-diabetes mellitus (OR 2.141, P=0.013) and lower ejection fraction (OR 0.961, P=0.011). Mismatch was associated with smaller DS (OR 0.914, P&lt;0.001), shorter lesion length (OR 0.894, P=0.001), higher CFR (OR 1,633, P&lt;0.001), and lower estimated glomerular filtration rate (OR, 0.968, P=0.001). Lesion location and the index of microcirculatory resistance was not associated with the prevalence of reverse mismatch or mismatch. Conclusions There was a high prevalence of visual-functional mismatches between QCA-DS and QFR, and CFR was an important functional factor of mismatches. Our results suggested the difference between predictors of reported visual-functional mismatches of QCA/FFR and those of QCA/QFR.

Ten-year-old children with a history of bronchopulmonary dysplasia have regional abnormalities in ventilation perfusion matching.

The ratio of ventilation to blood flow is an important determinant for regional gas exchange in the lung and hypoxemia is one of the clinical hallmarks in infants with bronchopulmonary dysplasia (BPD). We have previously demonstrated ventilation/perfusion ratio (V/Q) abnormalities in infants with BPD at 36 weekś postconceptional age. The status of V/Q matching in older children with a history of BPD in infancy is unknown. In this study, we examined if 10-year-old children with a history of BPD had V/Q impairments. Three-dimensional V/Q-scintigraphy (SPECT) was performed in 26 children. In the BPD group, lung volume with mismatch, (V>Q) was larger compared to areas with reverse mismatch (Q>V), 26.2% and 11.8%, respectively, implying that perfusion defects contribute more than ventilation defects in the V/Q mismatch. Also, the mean fractional distribution of V and Q to V/Q in children with BPD was reduced compared to healthy children, 31% and 51% compared to 64% and 89%, respectively (P < 0.01). At 10 years of age children with a history of BPD had ventilation/perfusion abnormalities, with prominent perfusion defects. These V/Q abnormalities suggest the presence of residual alveolar-capillary impairment.

Comparison between instantaneous wave-free ratio versus morphometric assessments by intracoronary imaging

Anatomical measurements obtained by intracoronary imaging devices are reported to correlate significantly with fractional flow reserve (FFR). Instantaneous wave-free ratio (iFR) is a nonhyperemic index of stenosis severity with discordant reports regarding its accuracy in relation to FFR. There is no information on the correlation of iFR with measurements derived from intracoronary imaging devices. The purpose of this study was to assess the relationship among iFR, intravascular ultrasound (IVUS), and optical frequency domain imaging (OFDI) parameters. Eighty lesions in 72 patients who underwent elective angiography and had intermediate lesions were enrolled. All lesions were assessed by iFR, FFR, IVUS, and OFDI. iFR was ≤0.89 in 21 (26%) lesions and FFR was ≤0.80 in 41 (51%) lesions. iFR correlated significantly with both IVUS-derived minimum lumen area (MLA) (r = 0.375, p = 0.003) and OFDI-derived MLA (r = 0.357, p = 0.005). FFR also correlated significantly with both IVUS-derived MLA (r = 0.472, p < 0.001) and OFDI-derived MLA (r = 0.445, p < 0.001). Among the lesions with FFR ≤0.80, iFR>0.89 (mismatch) was observed in 20 lesions. There was no lesion with iFR ≤0.89 (reverse mismatch) among the lesions with FFR>0.80. The lesion location among three major coronary vessels was related with the discrepancy between iFR and FFR (p = 0.007). In conclusion, iFR and FFR showed a significant correlation with IVUS and OFDI measurements. The discrepancy of iFR and FFR was associated with the lesion locations.

Influence of visual-functional mismatch on coronary flow profiles after percutaneous coronary intervention: a propensity score-matched analysis.

The aims of this study are to clarify whether discrepancies between angiographic and fractional flow reserve (FFR) measurements (visual-functional mismatch) influence coronary flow profiles after percutaneous coronary intervention. While current guidelines FFR-guided revascularization, clinical practice most commonly relies on angiographic evaluation, which may under- or over-estimate the functional relevance of the lesion. Our retrospective analysis involved 274 vessels from 264 patients with stable angina pectoris who underwent FFR, index of microvascular resistance, and coronary flow reserve (CFR) measurements before and after PCI. Visual-functional concordance and discordance (reverse mismatch) were defined as angiographic stenosis > 50% with FFR ≤ 0.80 and angiographic stenosis ≤ 50% with FFR ≤ 0.80, respectively. Propensity score-matched cohort included 132 lesions (66 lesions: concordant findings, 66 lesions: reverse mismatch). The change in coronary flow profiles after PCI was assessed in terms of FFR, CFR, index of microvascular resistance (IMR), and mean transit time (Tmn). Compared with concordant territories, reverse mismatch territories were associated with lower pre-PCI IMR, higher pre-PCI CFR, greater minimum lumen diameter and smaller reference diameter (all comparisons, P < 0.05). After propensity score matching, the prevalence and extent of coronary flow improvement after PCI, evaluated by CFR and Tmn, were both remained significantly greater in concordant territories (all comparisons, P < 0.05). The prevalence and extent of coronary flow improvement after PCI assessed by the physiologic indices was significantly greater in visual-functional concordant lesions, suggesting that these coronary physiologic changes were associated with discrepancy between angiographic measurements.

Neuroendocrine Neoplasms: A Case Report with Complete Reverse Mismatch and the Correlation with Differentiation Rate

Neuroendocrine Neoplasms: A Case Report with Complete Reverse Mismatch and the Correlation with Differentiation Rate

Reverse Mismatch Pattern in Cardiac 18F-FDG Viability PET/CT Is Not Associated With Poor Outcome of Revascularization: A Retrospective Outcome Study of 91 Patients With Heart Failure.

Revascularization strategies in patients with ischemic heart failure (HF) should be based on evidence of reversible perfusion defects and myocardial viability. Myocardial viability assessment is preferably based on dual isotope PET using perfusion and metabolism tracers. However, in a nonnegligible subset of HF patients, reverse mismatch (RM) pattern (reduced glucose uptake relative to perfusion) of unknown origin is observed. We aimed to investigate determinants of RM and the impact of RM on the subsequent improvement in left ventricular function by revascularization. Ninety-one patients (12 women, 25 with diabetes) with HF undergoing Rb perfusion PET and hyperinsulinemic-euglycemic clamp F-FDG viability PET were retrospectively reviewed. Follow-up time was 12 to 33 months. In 30 of 91 patients, hypometabolic myocardium exceeded the percentage of hypoperfused myocardium; however, only in 12 of 91 patients was the RM considered significant (percentage RM in the left ventricle, 42.5 ± 12.9 [reverse patients] vs 14.1 ± 8.6 [scar and hibernation patients]; P < 0.001). Diabetes status per se did not predict RM, but a significant inverse correlation between insulin sensitivity and RM was observed. The frequency of hospitalization, cardiac death, and myocardial infarctions were not significantly higher in RM patients. Reverse mismatch patients benefited from revascularization to the same extent as patient with normal metabolic patterns. Reverse mismatch is common among HF patients (~15%) and is inversely correlated to insulin sensitivity. It is not, however, associated with increased cardiac morbidity and mortality and does not predict a worse outcome after revascularization.

Visual-Functional Mismatch Between Coronary Angiography, Fractional Flow Reserve, and Quantitative Coronary Angiography.

Anatomical and functional mismatches are not uncommon in the assessment of coronary lesions. The aim of this study was to identify clinical and lesion-specific factors affecting angiographic, anatomical, and functional mismatch in intermediate coronary lesions. In patients who underwent coronary angiography for clinical reasons, fractional flow reserve (FFR), and quantitative coronary angiography (QCA) analyses for intermediate stenotic lesions were performed simultaneously. Mismatches between the measured values were analyzed. A total of 95 intermediate lesions were assessed simultaneously by visual angiography, FFR, and QCA. The visual-FFR mismatch was found in 40% of the lesions while reverse visual-FFR mismatch was determined in nearly 14% of the lesions. Mismatch and reverse mismatch between FFR and QCA parameters were observed in 10 and 23% of the lesions. FFR value was significant in 32% of the lesions while visually significant stenosis was shown in 61% of the lesions. Among the visual-FFR reverse mismatch group, the prevalence of culprit lesions within the left anterior descending (LAD) was significantly higher than other vessels (p value < 0.02). There were high frequencies of angiographic, QCA, and functional mismatches in analyses of intermediate coronary lesions. LAD lesions showed the highest mismatch. Angiographic or QCA estimation of lesion severity has consistently resulted in inappropriate stenting of functionally nonsignificant lesions or undertreatment of significant lesions based on FFR.

Abstract 10412: The Effect of Positive Remodeling Area Index and Large Plaque Burden over Fractional Flow Reserve

Introduction: Coronary angiographic anatomical stenosis has not been well correlated with physiological fractional flow reserve (FFR), however, the mechanism of the discordance remains poorly understood. We focused on the patients who had no anatomical significant stenosis by coronary angiogram (CAG) but physiological significant stenosis by FFR (reverse mismatch) in the proximal or mid left anterior descending artery (LAD). We explored what coronary CT angiography (CCTA) findings of the target lesion of the LAD predict abnormal FFR. Methods: ECG-gated CCTA was performed using SOMATOM Definition AS+ (128 slice Siemens) and CAG underwent within 4 weeks. FFR was measured using a pressure guide wire (verrata, Volcano) during ATP infusion. Forty consecutive reverse mismatch (with no anatomical stenosis and FFR≦0.8) pts and 40 no mismatch (with no anatomical stenosis and FFR&gt;0.8) pts were selected. Results: There were no significant differences in mean age (72±10y vs 74±8y), gender (M/F 21/19 vs 28/12), coronary risk factors (DM (9 vs 17), HT(32 vs 30), dyslipidemia (23 vs 18), Smoking (5 vs 4)), angle of LAD and LCX (70±21vs71±20 deg.), proximal reference lumen area (0.14±0.14 vs 0.14±0.11 mm2) and vessel area (0.15±0.04 vs 0.15±0.06mm2), distal reference lumen area (0.11±0.12 vs 0.10±0.04mm2) and vessel area (0.14±0.13 vs 0.12±0.04mm2), grade of plaque calcification, and presence of low density plaque (8 vs 7 pts) between no mismatch and reverse mismatch groups. However, vessel area (0.21±0.07mm2, P=0.0004) and positive remodeling area index (1.40±0.26, P&lt;0.0001) at the minimum lumen area (MLA) in reverse mismatch group were higher than those (0.16±0.05mm2, 1.01±0.18) in no mismatch groups, respectively. AUC of remodeling area index was 0.924 for diagnosis of reverse mismatch on ROC analysis. Sensitivity was 82.5%, specificity was 84.6% when the remodeling area index was 1.13. Conclusions: Even if anatomical significant stenosis is not observed, FFR was depressed in patients with large vessel area and positive remodeling area index derived from CCTA at MLA. Large plaque at MLA may be one of the mechanisms of reverse mismatch.

Septal and anterior reverse mismatch of myocardial perfusion and metabolism in patients with coronary artery disease and left bundle branch block.

The effects of left bundle branch block (LBBB) on left ventricular myocardial metabolism have not been well investigated. This study evaluated these effects in patients with coronary artery disease (CAD).Sixty-five CAD patients with complete LBBB (mean age, 61.8 ± 9.7 years) and 65 without LBBB (mean age, 59.9 ± 8.4 years) underwent single photon emission computed tomography, positron emission tomography, and contrast coronary angiography. The relationship between myocardial perfusion and metabolism and reverse mismatch score, and that between QRS length and reverse mismatch score and wall motion score were evaluated.The incidence of left ventricular septum and anterior wall reverse mismatching between the two groups was significantly different (P < 0.001 and P = 0.002, respectively). The incidences of normal myocardial perfusion and metabolism in the left ventricular lateral and inferior walls were also significantly different between the two groups (P < 0.001 and P < 0.001, respectively). The incidence of septal reverse mismatching in patients with mild to moderate perfusion was significantly higher among those with LBBB than among those without LBBB (P < 0.001). In CAD patients with LBBB, septal reverse mismatching was significantly more common among those with mild to moderate perfusion than among those with severe perfusion defects (P = 0.002). The correlation between the septal reverse mismatch score and QRS length was significant (P = 0.026).In patients with CAD and LBBB, septal and anterior reverse mismatching of myocardial perfusion and metabolism was frequently present; the septal reverse mismatch score negatively correlated with the QRS interval.

The Mismatch Myth in American Higher Education: A Synthesis of Empirical Evidence at the Law School and Undergraduate Levels

This paper presents a comprehensive examination of the empirical literature testing the academic mismatch hypothesis as it applies to affirmative action and students of color in U.S. higher education. The primary focus of this paper is the mismatch research addressing American legal education (Part II). This includes a detailed assessment of the empirical basis of claims made by Richard Sander and, more recently, by Doug Williams, showing flaws in their work, including questionable claims and methodological choices. In particular, this paper calls into question all research using the LSAC Bar Passage Study data that treats schools in tiers 2 and 3 in that study as separate and hierarchically ordered, arguing that this treatment is statistically unjustified and due to idiosyncrasies in the data and factors that in fact distinguish these tiers serves to enhance the odds of finding a mismatch effect while lowering the likelihood of finding reverse mismatch effects. The paper also reviews research on mismatch at the undergraduate level (Part III), specifically examining the outcomes of graduation rates and earnings and again finding that the mismatch hypothesis lacks empirical support and is, if anything, empirically less plausible than claims made for a reverse mismatch effect. In examining both legal and undergraduate education, this paper both critiques work that purports to find evidence of mismatch and references numerous studies that find no evidence of mismatch effects or evidence of reverse mismatch effects, including studies that use state of the art methods to control for selection bias. Overall the social science evidence points clearly in one direction: affirmative action as practiced today is not plagued by mismatch effects; indeed the evidence indicates that underrepresented minority students tend to do better over the life course if they attend the most selective school that will admit them.

Segmental Hyperperfusion in Lobar Pneumonia Visualized with Respiratory-gated Four-Dimensional Pulmonary Perfusion Positron Emission Tomography–Computed Tomography

A 64-year-oldman underwent a respiratory-gated four-dimensional pulmonary perfusion positron emission tomography (PET)/computed tomography (CT) for preoperative regional lung function quantification. This was performed after intravenous administration of Gamacroaggregated albumin (1–3). At the time of imaging, he had a productive cough, fever, and subsequent clinical diagnosis of bronchopneumonia. Images demonstrated an area of hyperperfusion localized to an area of dense collapse/consolidative change in the lateral segment of the right middle lobe (Figure 1 and supplemental video E1). The abnormality was also clearly apparent on the nonattenuation correction images, excluding an attenuation artifact. Studies have typically documented matched ventilation–perfusion or reverse mismatch phenomenon in pneumonia (4). Although occlusive obstruction of lobar airways is usually accompanied by reflex hypoxic vasoconstriction, the local release of inflammatory mediators with vasodilatory properties with infection results in failure of this mechanism and shunting leading to hypoxia (5). The histopathologic correlate is the red hepatization phase of lobar pneumonia. Tc-macroaggregated albumin single-photon emission computed tomography/CT had also been performed in this patient, but no corresponding perfusion abnormality was found. Although this was performed 72 hours earlier, the CT abnormality was similar; we contend that in addition to the superior imaging characteristics of PET, the absence of respiratory gating and attenuation correction contributed to lack of abnormality on single-photon emission computed tomography. The higher spatial and temporal resolution of PET combined with four-dimensional acquisition (6) provides a major advance in image quality and may improve our understanding of pulmonary physiology in a spectrum of diseases. n

Relationship between myocardial viability, myocardial blood flow and coronary anatomy by positron emission tomography integrated with multislice computed tomography

The relationship between myocardial viability, myocardial blood flow and the degree of epicardial coronary stenosis in patients with coronary artery disease and left ventricular dysfunction is unclear. Objective The purpose of this study is to determine whether positron emission tomography (PET) viability patterns and myocardial flow at rest correlate with the degree of epicardial coronary stenosis. Methods Myocardial viability was evaluated in 27 patients by the combined analysis of 13N-Ammonia (13NH3) perfusion and 18F-2-fluoro-2-deoxyglucose (FDG) metabolism to identify four PET patterns: match (concordant reduced uptake of both radiotracers), mismatch (hypoperfusion with preserved FDG uptake), reverse mismatch (preserved perfusion and reduced FDG uptake) and preserved uptake of both radiotracers. Myocardial blood flow was calculated using a two-compartment model. Coronary artery stenosis was classified as mild ( 50%), severe (>70%) and critical (≥90%). Results In the 459 analyzed segments, 33% were match, 12% mismatch, 11% reversemismatch and 44% preserved patterns. Mismatch, reverse-mismatch and preserved patterns exhibited higher flows than the match pattern (p<0.01). Fifteen coronary lesions were mild, 7 moderate, 20 severe and 39 critical. There was no correlation between the degree of coronary stenosis and viability patterns (R<0.2, p=NS) or blood flow values (R=0.12). Analysis by vascular territory did not correlate with the degree of coronary stenosis (p=NS). Conclusions Lack of correlation between PET viability patterns, degree of epicardial stenosis and myocardial blood flow suggest that coronary anatomy can neither differentiate viable from necrotic myocardium nor predict the functional status of myocardial flow in patients with left ventricular dysfunction.