Aloha Meave

Fusion of positron emission tomography and coronary computed tomographic angiography identifies fluorine 18 fluorodeoxyglucose uptake in the left main coronary artery soft plaque

Case report. A 71 year-old man underwent F-18 FDG-PET scanning with noncontrast computed tomography (CT) for attenuation and anatomic correction (PET/CT) 1 year after surgical resection with diverting colostomy and adjuvant chemotherapy and radiotherapy for colonic adenocarcinoma. A PET/CT scan was done after 10 hours of fasting, 90 minutes after FDG injection. His medical history included type 2 diabetes mellitus controlled with metformin and glibenclamide, cigarette smoking for 15 years (8-10 cigarettes per day), chronic gastritis, heavy alcohol use, and esophageal varices. The patient denied any allergies, chest pain, or previous heart disease. FDG-PET/CT showed focal hypermetabolic activity in the rectum and its neighboring fatty tissue, liver, and multiple lymph nodes in the mediastinum and neck. In addition, noticeable FDG uptake was present in the aorta, most consistent with aortic atherosclerotic plaque, and in a structure that appeared to be within or adjacent to the left main coronary artery (Figure 1). To further investigate the latter finding, retrospectively gated 64-slice CCTA was performed on the same day with the Siemens HI-REZ Biograph 64 hybrid PET/CT scanner (Siemens Medical Solutions, Malvern, Pa). Analysis of the reconstructed 3-dimensional CCTA images identified significant coronary atherosclerosis, i n cluding a large noncalcified plaque in the left main coronary artery and the proximal left anterior descending artery, the latter associated with a 50% stenosis, as well as multiple areas of calcified plaque in the right coronary artery (Figure 2). Subsequent software fusion of CCTA and FDG-PET/CT images by use of the Cedars-Sinai CT-Fusion option in the QPS program (Cedars-Sinai Medical Center, Los Angeles, Calif) showed anatomic correspondence between the abnormal extra-aortic FDG uptake and the noncalcified plaque within the left main coronary artery (Figure 3). In view of these findings, the patient was referred to the cardiology clinic, and we recommended aspirin and statin therapy and further examination by coronary angiography. However, because of his current serious oncologic condition, coronary angiography was not performed. Discussion. There is mounting evidence that FDG-PET uptake reflects inflammation in atherosclerotic plaques. Animal studies with atherosclerotic rabbits have confirmed that FDG uptake corresponds with plaque macrophage content. In patients with angiographic evidence of internal carotid stenosis, Rudd et al found significantly higher FDG uptake in 8 symptomatic carotid plaques than in 6 contralateral asymptomatic plaques; normal carotid arteries exhibited no identifiable uptake. Major limitations of plaque imaging with FDG-PET in the coronary vessels include cardiac motion during PET, FDG uptake in adjacent structures such as the myocardium, and limited PET resolution. Despite these limitations, our case shows the ability of FDG-PET/CT and CCTA image fusion to identify and localize areas of noticeable FDG uptake in the proximal segments of the coronary arteries, which could be related to inflamed atherosclerotic lesions.

Left ventricular noncompaction: A proposal of new diagnostic criteria by multidetector computed tomography

BACKGROUND Left ventricular noncompaction (LVNC) is a cardiomyopathy characterized by a noncompacted myocardial layer in the left ventricle, primarily diagnosed by echocardiographic and magnetic resonance criteria. Multidetector computed tomography (MDCT) is an imaging method that has been increasingly used in cardiac evaluation. However, tomographic criteria to diagnose LVNC have not been determined. OBJECTIVES We assessed the structural characteristics of LVNC with MDCT and proposed tomographic criteria that may differentiate LVNC from healthy subjects and patients with other cardiomyopathies that might be associated with increased myocardial trabeculation. METHODS Between March 2007 and June 2009 we studied 10 consecutive patients with LVNC diagnosed by echocardiogram and/or magnetic resonance imaging who underwent electrocardiogram-gated coronary CT angiography. We evaluated the ratio of noncompacted to compacted myocardium (NC/C ratio) in end diastole in each of the 17 segments established by the American Heart Association (excluding the apex). The results were compared with 9 healthy subjects, 14 patients with hypertrophic cardiomyopathy, and 17 patients with dilated cardiomyopathy to determine the cutoff that would distinguish patients with LVNC. RESULTS When considering involvement of more than 1 segment, the NC/C ratio of 2.2 distinguished pathologic noncompaction, with sensitivity and specificity of 100% and 95%, respectively. In addition, the involvement of ≥2 segments allows the distinction of all patients with LVNC from other cardiomyopathies and from healthy subjects. CONCLUSIONS LVNC can be accurately diagnosed with MDCT when using a cutoff NC/C ratio of 2.2 at end diastole involving ≥2 segments.

Image quality and radiation dose of a prospectively electrocardiography-triggered high-pitch data acquisition strategy for coronary CT angiography: The multicenter, randomized PROTECTION IV study.

BACKGROUND Concerns have been raised about radiation dose of coronary CT angiography. Although high-pitch acquisition technique yields high potential for radiation dose savings, it is more vulnerable to artifacts, which impair diagnostic image quality. OBJECTIVE The purpose of this study was to compare 2 scan strategies for coronary CT angiography: a high-pitch helical scan first or a conventional scan first strategy. METHODS In this prospective, multicenter trial, we randomized 303 consecutive patients with a low and stable heart rate to either of the aforementioned mentioned strategies. Intravenous β-blockers were administered to achieve target heart rates. All scans were performed on a second-generation dual-source CT scanner. In case of nondiagnostic image quality, coronary CT angiography was allowed to be repeated. The primary end point was to demonstrate noninferior image quality in the high-pitch group. Image quality was assessed on a 4-point scale (1: nondiagnostic, 4: excellent). Secondary end point was total radiation dose. RESULTS In the high-pitch helical first group, repeat scanning was necessary in 21 patients compared with 14 patients in the conventional first scan group (P = .25). Image quality in the high-pitch group was noninferior compared to the conventional scan group (3.81 ± 0.35 vs. 3.83 ± 0.37; P for noninferiority <.0001). The total effective radiation dose estimate was 58% lower in the high-pitch group (2.0 ± 2.4 vs. 4.7 ± 4.8 mSv; P < .0001). CONCLUSIONS In patients with a low and stable heart rate diagnostic image quality can be maintained with a high-pitch helical scan first strategy while 58% of radiation dose can be saved.

Endothelial Dysfunction in Recently Diagnosed Type 2 Diabetic Patients Evaluated by PET

PurposeTo demonstrate the presence of endothelial dysfunction (ED) in asymptomatic patients with type 2 diabetes mellitus (DM) by using 13N-ammonia–positron emission tomography (PET). PET can identify ED by quantifying myocardial blood flow (MBF) during rest, cold pressor test (CPT), and pharmacologic stress. The endothelial-dependent vasodilation index (EDVI), myocardial flow reserve (MFR), and the percentage of the change between rest and CPT (%ΔMBF) are markers of endothelial function.ProceduresThirty-nine subjects were studied (19 women and 20 men); 22 recently diagnosed type 2 diabetic patients and 17 healthy controls (HC). A three-phase 13N-ammonia–PET was performed.ResultsMean EDVI was 1.208 ± 0.34 vs. 1.55 ± 0.37 (diabetic vs. HC group, respectively) (p = 0.002), MFR was 2.803 ± 1.39 vs. 3.27 ± 0.72 (p = NS), and the %ΔMBF was 20 ± 34% vs. 55 ± 37% (p = 0.002). Rest MBF and CPT MBF were normalized to the rate pressure product (RPP). EDVI′ and %ΔMBF′ were calculated using the corrected values for the RPP. Mean EDVI′ was (0.864 ± 0.250 vs. 1.110 ± 0.238, p = 0.004) and mean %ΔMBF′ was (−8.2 ± 14.7% vs. 4.5 ± 12.1%, p = 0.005).ConclusionsAsymptomatic, recently diagnosed type 2 diabetes patients present ED that can be quantified by 13N-ammonia–PET.

Endothelial Dysfunction in Systemic Lupus Erythematosus: Evaluation with 13N-Ammonia PET

Systemic lupus erythematosus (SLE) affects multiple organs and systems, severely involving the cardiovascular system. The aim of this study was to evaluate the presence of endothelial dysfunction with 13N-ammonia PET in asymptomatic SLE patients. Methods: We enrolled 16 women with SLE and 16 healthy women. Myocardial blood flow (MBF) was quantified in a 64-slice PET/CT scanner at rest, during a cold pressor test (CPT), and during stress. Endothelium-dependent vasodilation index, %ΔMBF, and myocardial flow reserve (MFR) were calculated. Results: There were 16 women in the SLE group (mean age ± SD, 31.4 ± 8.3 y) and 16 women in the healthy control group (31.5 ± 11.1 y). Mean endothelium-dependent vasodilatation index and %ΔMBF were significantly lower in SLE patients (1.18 ± 0.55 vs. 1.63 ± 0.65, P = 0.04, and 18 ± 55 vs. 63 ± 65, P = 0.04, respectively). MFR was also lower in the SLE group (2.41 ± 0.59 vs. 2.73 ± 0.77, P = 0.20). Conclusion: SLE patients who are free of active disease present abnormal coronary flow and endothelial dysfunction. It is necessary to develop and intensify treatment strategies directed to CAD in SLE patients.

Prognostic value of cardiovascular CT: Is coronary artery calcium screening enough? The added value of CCTA

Coronary artery disease (CAD) is the primary cause of death in adults in the United States. Only 50% of patients who present with a myocardial infarction have a prior history of CAD. Non-invasive cardiac imaging tests have been developed to diagnose CAD. Current guidelines and systematic reviews have tried to determine the prognostic value of the coronary artery calcium (CAC) scoring and the coronary computed tomography angiography (CCTA) for major adverse cardiovascular events. Several studies support the roles of CCTA and CAC scoring for the diagnosis of CAD in asymptomatic patients. Further studies are needed to confirm the superior role of CCTA over CAC scoring in symptomatic patients.

Relationship Between Quantitative Adverse Plaque Features From Coronary Computed Tomography Angiography and Downstream Impaired Myocardial Flow Reserve by 13N-Ammonia Positron Emission Tomography A Pilot Study

Background—We investigated the relationship of quantitative plaque features from coronary computed tomography (CT) angiography and coronary vascular dysfunction by impaired myocardial flow reserve (MFR) by 13N-Ammonia positron emission tomography (PET). Methods and Results—Fifty-one patients (32 men, 62.4±9.5 years) underwent combined rest–stress 13N-ammonia PET and CT angiography scans by hybrid PET/CT. Regional MFR was measured from PET. From CT angiography, 153 arteries were evaluated by semiautomated software, computing arterial noncalcified plaque (NCP), low-density NCP (NCP<30 HU), calcified and total plaque volumes, and corresponding plaque burden (plaque volumex100%/vessel volume), stenosis, remodeling index, contrast density difference (maximum difference in luminal attenuation per unit area in the lesion), and plaque length. Quantitative stenosis, plaque burden, and myocardial mass were combined by boosted ensemble machine-learning algorithm into a composite risk score to predict impaired MFR (MFR⩽2.0) by PET in each artery. Nineteen patients had impaired regional MFR in at least 1 territory (41/153 vessels). Patients with impaired regional MFR had higher arterial NCP (32.4% versus 17.2%), low-density NCP (7% versus 4%), and total plaque burden (37% versus 19.3%, P<0.02). In multivariable analysis with 10-fold cross-validation, NCP burden was the most significant predictor of impaired MFR (odds ratio, 1.35; P=0.021 for all). For prediction of impaired MFR with 10-fold cross-validation, receiver operating characteristics area under the curve for the composite score was 0.83 (95% confidence interval, 0.79–0.91) greater than for quantitative stenosis (0.66, 95% confidence interval, 0.57–0.76, P=0.005). Conclusions—Compared with stenosis, arterial NCP burden and a composite score combining quantitative stenosis and plaque burden from CT angiography significantly improves identification of downstream regional vascular dysfunction.

Multicenter Evaluation of Coronary Dual-Source CT Angiography in Patients with Intermediate Risk of Coronary Artery Stenoses (MEDIC): Study design and rationale

BACKGROUND The diagnostic performance of multidetector row CT to detect coronary artery stenosis has been evaluated in numerous single-center studies, with only limited data from large cohorts with low-to-intermediate likelihood of coronary disease and in multicenter trials. The Multicenter Evaluation of Coronary Dual-Source CT Angiography in Patients with Intermediate Risk of Coronary Artery Stenoses (MEDIC) trial determines the accuracy of dual-source CT (DSCT) to identify persons with at least 1 coronary artery stenosis among patients with low-to-intermediate pretest likelihood of disease. METHODS The MEDIC trial was designed as a prospective, multicenter, international trial to evaluate the diagnostic performance of DSCT for the detection of coronary artery stenosis compared with invasive coronary angiography. The study includes 8 sites in Germany, India, Mexico, the United States, and Denmark. The study population comprises patients referred for a diagnostic coronary angiogram because of suspected coronary artery disease with an intermediate pretest likelihood as determined by sex, age, and symptoms. All evaluations are performed by blinded core laboratory readers. RESULTS The primary outcome of the MEDIC trial is the accuracy of DSCT to identify the presence of coronary artery stenoses with a luminal diameter narrowing of 50% or more on a per-vessel basis. Secondary outcome parameters include per-patient and per-segment diagnostic accuracy for 50% stenoses and accuracy to identify stenoses of 70% or more. Furthermore, secondary outcome parameters include the influence of heart rate, Agatston score, body weight, body mass index, image quality, and diagnostic confidence on the accuracy to detect coronary artery stenoses >50% on a per-vessel basis. CONCLUSION The results of the MEDIC trial will assess the clinical utility of coronary CT angiography in the evaluation of patients with intermediate pretest likelihood of coronary artery disease.

Isolated Left Ventricular Apical Hypoplasia

the apex of the right ventricular cavity as the left intraventricular pressure increases. Differential diagnosis of this pathology requires the presence of left ventricular hypoplasia, aneurysms and ventricular diverticula. The ventricular hypoplasia is characterized by a small and hypertrophic ventricular chamber and dysplastic cardiac valves. The diverticul originates on the ventricular wall at a narrow joint and are more frequent in the LV. Ventricular aneurysms are acquired defects, located at a wide junction, that buckle during systole.

Assessment of Endothelial Function by Positron Emission Tomography

The study of endothelial dysfunction by positron emission tomography (PET) allows a non-invasive evaluation of the endotheliums role in the maintenance of tone and vascular homeostasis, thus the determination of regional myocardial flow, myocardial flow reserve, endothelium dependent vasodilatory index and inflammation level in the vascular wall in atherosclerosis and autoimmune diseases. Endothelial dysfunction results in significantly impaired physiological responses that often lead to the development of coronary atherosclerosis and coronary artery disease (CAD). PET allows the early recognition of endothelial dysfunction in order to evaluate a possible and beneficial response to medical interventions in the atherosclerosis process. This can help to establish a prognosis based in the early detection of patients at risk of CAD and offers the opportunity for early treatment. This article reviews the current knowledge regarding a non-invasive assessment for endothelial dysfunction and proposes the potential use of this promising technique for early detection of this prognostic marker in the coronary atherosclerotic process.