Ricardo P.J. Budde

Additional Heparin Preadministration Improves Cardiac Glucose Metabolism Suppression over Low-Carbohydrate Diet Alone in ¹⁸F-FDG PET Imaging.

Adequate suppression of cardiac glucose metabolism increases the interpretability and diagnostic reliability of 18F-FDG PET studies performed to detect cardiac inflammation and infection. There are no standardized guidelines, though prolonged fasting (>6 h), carbohydrate-restricted diets, fatty meals, and heparin loading all have been proposed. The aim of this study was to compare the 3 preparatory protocols used in our institution. Methods: 18F-FDG PET scans were selected and grouped according to 3 preparatory protocols (50 consecutive scans per group): 6-h fast (group 1), low-carbohydrate diet plus 12-h fast (group 2), and low-carbohydrate diet plus 12-h fast plus intravenous heparin preadministration (50 IU/kg) (group 3). Consecutive scans were retrospectively included from time frames during which the particular protocol was used. Group 1 included oncologic indications, and groups 2 and 3 infection or inflammation detection. Cardiac segments for which inflammation or infection foci had been confirmed on other imaging modalities were excluded from the analysis. 18F-FDG uptake in normal myocardium was scored according to a scale ranging from 0 (uptake less than that in left ventricle blood pool) to 4 (diffuse uptake greater than that in liver). Adequate suppression was defined as uptake less than that in liver and without any focus (scores 0–2). Results: Adequate suppression differed significantly between groups: 28% in group 1, 54% in group 2, and 88% in group 3 (P < 0.0001 for all comparisons). Conclusion: Single-dose heparin administration before 18F-FDG PET in addition to a low-carbohydrate diet significantly outperforms a low-carbohydrate diet alone in adequately suppressing cardiac glucose metabolism.

Are novel non-invasive imaging techniques needed in patients with suspected prosthetic heart valve endocarditis? A systematic review and meta-analysis

ObjectivesMultimodal non-invasive imaging plays a key role in establishing a diagnosis of PHV endocarditis. The objective of this study was to provide a systematic review of the literature and meta-analysis of the diagnostic accuracy of TTE, TEE, and MDCT in patients with (suspected) PHV endocarditis.MethodsStudies published between 1985 and 2013 were identified via search and cross-reference of PubMed/Embase databases. Studies were included if (1) they reported on the non-invasive index tests TTE, TEE, or MDCT; (2) data was provided on PHV endocarditis as the condition of interest; and (3) imaging results were verified against either surgical inspection/autopsy or clinical follow-up reference standards, thereby enabling the extraction of 2-by-2 tables.ResultsTwenty articles (including 496 patients) met the inclusion criteria for PHV endocarditis. TTE, TEE, and MDCTu2009+u2009TEE had a pooled sensitivity/specificity for vegetations of 29/100xa0%; 82/95xa0%, and 88/94xa0%, respectively. The pooled sensitivity/specificity of TTE, TEE, and MDCTu2009+u2009TEE for periannular complications was 36/93xa0%, 86/98xa0%, and 100/94xa0%, respectively.ConclusionsTEE showed good sensitivity and specificity for establishing a diagnosis of PHV endocarditis. Although MDCT data are limited, this review showed that MDCT in addition to TEE may improve sensitivity in detecting life-threatening periannular complications.Key Points• Multimodal imaging is an important ingredient of diagnostic workup for PHV endocarditis.• Transthoracic and transesophageal echography may miss life-threatening periannular complications.• MDCT can improve sensitivity for the detection of life-threatening periannular complications.

Achievable dose reduction using iterative reconstruction for chest computed tomography: A systematic review

OBJECTIVESnIterative reconstruction (IR) allows for dose reduction with maintained image quality in CT imaging. In this systematic review the reported effective dose reductions for chest CT and the effects on image quality are investigated.nnnMETHODSnA systematic search in PubMed and EMBASE was performed. Primary outcome was the reported local reference and reduced effective dose and secondary outcome was the image quality with IR. Both non contrast-enhanced and enhanced studies comparing reference dose with reduced dose were included.nnnRESULTSn24 studies were included. The median number of patients per study was 66 (range 23-200) with in total 1806 patients. The median reported local reference dose of contrast-enhanced chest CT with FBP was 2.6 (range 1.5-21.8) mSv. This decreased to 1.4 (range 0.4-7.3) mSv at reduced dose levels using IR. With non contrast-enhanced chest CT the dose decreased from 3.4 (range 0.7-7.8) mSv to 0.9 (range 0.1-4.5) mSv. Objective mage quality and diagnostic confidence and acceptability remained the same or improved with IR compared to FBP in most studies while data on diagnostic accuracy was limited.nnnCONCLUSIONnRadiation dose can be reduced to less than 2 mSv for contrast-enhanced chest CT and non contrast-enhanced chest CT is possible at a submillisievert dose using IR algorithms.

Confounders in FDG-PET/CT Imaging of Suspected Prosthetic Valve Endocarditis

Recently, 18F-fluorodeoxyglucose positron emission tomography with low-dose computed tomography forxa0attenuation correction and anatomical correlation (18F-FDG-PET/CT) has seen increasing use to help diagnose prosthetic heart valve (PHV) endocarditis. Based on the available evidence, 18F-FDG-PET/CT

Effect of antibiotics on FDG-PET/CT imaging of prosthetic heart valve endocarditis

Four consecutive 18F-FDG-PET/CT scans of the same patient with a prosthetic heart valve (PHV, Perimount 21 mm biological valve implanted 2 years prior) in the aortic position, with target-to-background ratios (TBR, SUVmax PHV divided by SUVmean aortic blood pool). Patient presented with fever, malaise, and diarrhoea after returning from a trip abroad. Fever persisted under initial antibiotic treatment with ceftriaxone and gentamycin, …

Cardiovascular imaging in pediatric patients using dual source CT

Cardiovascular CT acquisition protocol optimization in pediatric patients, including newborns is often challenging. This might be due to non-cooperative patients, the complexity and variety of diseases and the need for stringent dose minimization. Motion artifacts caused by voluntary and involuntary motion are most frequently seen in cardiac imaging with high heart and respiratory rates. Dual source scanners of the second and third generation are particularly well suited to respond to these challenges. This can be accomplished with advanced scan options, such as high pitch scanning, short rotation times, automated tube voltage selection, tube current modulation and iterative reconstruction.

Qualitative grading of aortic regurgitation: a pilot study comparing CMR 4D flow and echocardiography

Over the past 10xa0years there has been intense research in the development of volumetric visualization of intracardiac flow by cardiac magnetic resonance (CMR). This volumetric time resolved technique called CMR 4D flow imaging has several advantages over standard CMR. It offers anatomical, functional and flow information in a single free-breathing, ten-minute acquisition. However, the data obtained is large and its processing requires dedicated software. We evaluated a cloud-based application package that combines volumetric data correction and visualization of CMR 4D flow data, and assessed its accuracy for the detection and grading of aortic valve regurgitation using transthoracic echocardiography as reference. Between June 2014 and January 2015, patients planned for clinical CMR were consecutively approached to undergo the supplementary CMR 4D flow acquisition. Fifty four patients (median age 39xa0years, 32 males) were included. Detection and grading of the aortic valve regurgitation using CMR 4D flow imaging were evaluated against transthoracic echocardiography. The agreement between 4D flow CMR and transthoracic echocardiography for grading of aortic valve regurgitation was good (κxa0=xa00.73). To identify relevant, more than mild aortic valve regurgitation, CMR 4D flow imaging had a sensitivity of 100xa0% and specificity of 98xa0%. Aortic regurgitation can be well visualized, in a similar manner as transthoracic echocardiography, when using CMR 4D flow imaging.

Importance of the left ventricular outflow tract in the need for pacemaker implantation after transcatheter aortic valve replacement.

BACKGROUNDnThe interaction of left ventricular outflow tract (LVOT) and transcatheter heart valve (THV) is complex and may be device design specific. We sought to study LVOT characteristics and its relation with permanent pacemaker implantation (PPI) after transcatheter aortic valve replacement (TAVR).nnnMETHODSnWe studied 302 patients with a median age of 81years [75-84]. Computed tomography was used to assess LVOT in terms of amount of calcium, perimeter and device size relative to LVOT.nnnRESULTSnWe implanted a Medtronic CoreValve (MCS) in 203 patients, Edwards-Sapien XT (ESV-XT) in 38, Edwards-Sapien S3 (ESV-S3) in 26 and Lotus in 35 patients. Sixty-eight patients (22.5%) received a new PPI within 30days after the index procedure. The incidence of PPI was 22.7% with MCS, 10.5% with ESV-XT, 26.9% with ESV-S3 and 31.4% with Lotus. By multivariate analysis RBBB at baseline (OR 2.9 [1.2-6.9, p=0.014), second generation valves (OR 2.1 [1.0-4.5], p=0.048), DOI (OR 1.20 per 1mm increment, [1.09-1.31], p<0.001) and LVOT sizing (OR per 1% increment 1.03 [1.01-1.07], p=0.022) were associated with need for PPI. Sensitivity analyses suggest that a lesser degree of LVOT oversizing triggers PPI with second generation THVs vs. first generation THVs.nnnCONCLUSIONSnMore LVOT oversizing is associated with a higher need for permanent pacemaker implantation after TAVR, even more so with deeper THV implants and next generation devices (ESV-S3 and Lotus). Sizing algorithms should focus more on LVOT dimensions to reduce PPI.

Effect of radiation dose reduction and iterative reconstruction on computer-aided detection of pulmonary nodules: Intra-individual comparison

OBJECTIVEnTo evaluate the effect of radiation dose reduction and iterative reconstruction (IR) on the performance of computer-aided detection (CAD) for pulmonary nodules.nnnMETHODSnIn this prospective study twenty-five patients were included who were scanned for pulmonary nodule follow-up. Image acquisition was performed at routine dose and three reduced dose levels in a single session by decreasing mAs-values with 45%, 60% and 75%. Tube voltage was fixed at 120 kVp for patients ≥ 80 kg and 100 kVp for patients < 80 kg. Data were reconstructed with filtered back projection (FBP), iDose(4) (levels 1,4,6) and IMR (levels 1-3). All noncalcified solid pulmonary nodules ≥ 4 mm identified by two radiologists in consensus served as the reference standard. Subsequently, nodule volume was measured with CAD software and compared to the reference consensus. The numbers of true-positives, false-positives and missed pulmonary nodules were evaluated as well as the sensitivity.nnnRESULTSnMedian effective radiation dose was 2.2 mSv at routine dose and 1.2, 0.9 and 0.6 mSv at respectively 45%, 60% and 75% reduced dose. A total of 28 pulmonary nodules were included. With FBP at routine dose, 89% (25/28) of the nodules were correctly identified by CAD. This was similar at reduced dose levels with FBP, iDose(4) and IMR. CAD resulted in a median number of false-positives findings of 11 per scan with FBP at routine dose (93% of the CAD marks) increasing to 15 per scan with iDose(4) (95% of the CAD marks) and 26 per scan (96% of the CAD marks) with IMR at the lowest dose level.nnnCONCLUSIONnCAD can identify pulmonary nodules at submillisievert dose levels with FBP, hybrid and model-based IR. However, the number of false-positive findings increased using hybrid and especially model-based IR at submillisievert dose while dose reduction did not affect the number of false-positives with FBP.

Cloud-processed 4D CMR flow imaging for pulmonary flow quantification

OBJECTIVESnIn this study, we evaluated a cloud-based platform for cardiac magnetic resonance (CMR) four-dimensional (4D) flow imaging, with fully integrated correction for eddy currents, Maxwell phase effects, and gradient field non-linearity, to quantify forward flow, regurgitation, and peak systolic velocity over the pulmonary artery.nnnMETHODSnWe prospectively recruited 52 adult patients during one-year period from July 2014. The 4D flow and planar (2D) phase-contrast (PC) were acquired during same scanning session, but 4D flow was scanned after injection of a gadolinium-based contrast agent. Eddy-currents were semi-automatically corrected using the web-based software. Flow over pulmonary valve was measured and the 4D flow values were compared against the 2D PC ones.nnnRESULTSnThe mean forward flow was 92 (±30) ml/cycle measured with 4D flow and 86 (±29) ml/cycle measured with 2D PC, with a correlation of 0.82 and a mean difference of -6ml/cycle (-41-29). For the regurgitant fraction the correlation was 0.85 with a mean difference of -0.95% (-17-15). Mean peak systolic velocity measured with 4D flow was 92 (±49) cm/s and 108 (±56) cm/s with 2D PC, having a correlation of 0.93 and a mean difference of 16cm/s (-24-55).nnnCONCLUSIONn4D flow imaging post-processed with an integrated cloud-based application accurately quantifies pulmonary flow. However, it may underestimate the peak systolic velocity.