Gabriel C Camargo

Comparison of the prognostic value of myocardial perfusion imaging using a CZT-SPECT camera with a conventional anger camera

BackgroundRecent studies have shown that myocardial perfusion imaging (MPI) in cadmium-zinc-telluride (CZT) cameras allow faster exams with less radiation dose but there are little data comparing its prognosis information with that of dedicated cardiac Na-I SPECT camerasObjectiveThe objective of this study is to compare the prognostic value of MPI using an ultrafast protocol with low radiation dose in a CZT-SPECT and a traditional one.MethodsGroup 1 was submitted to a two-day MIBI protocol in a conventional camera, and group 2 was submitted to a 1-day MIBI protocol in CZT camera. MPI were classified as normal or abnormal, and perfusion scores were calculated. Propensity score matching methods were performedResults3554 patients were followed during 33±8 months. Groups 1 and 2 had similar distribution of age, gender, body mass index, risk factors, previous revascularization, and use of pharmacological stress. Group 1 had more abnormal scans, higher scores than group 2. Annualized hard events rate was higher in group 1 with normal scans but frequency of revascularization was similar to normal group 2. Patients with abnormal scans had similar event rates in both groupsConclusionNew protocol of MPI in CZT-SPECT showed similar prognostic results to those obtained in dedicated cardiac Na-I SPECT camera, with lower prevalence of hard events in patients with normal scan.

Is Cardiac Magnetic Resonance One of Cardiology's Magic Crystal Balls?∗

“ Its hard to make predictions—especially about the future .”—Robert Storm Petersen [(1)][1] Predictions are even harder in medicine, when so much individual variability and system complexity occurs. Nonetheless, we should not shun this important task. Few imaging modalities offer a more

Artifact suppression of SSFP cine sequences at 3T using a novel automatic 3D shimming algorithm

Methods A total of 20 consecutive patients scheduled to undergo a clinically indicated CMR in normal sinus rhythm and able to perform apnea were prospectively enrolled to be scanned in a 3T system (MAGNETOM Verio, Siemens, Germany). Frequency scout images were acquired in two and four chamber views and the frequency offset associated with least banding artifacts involving the heart was manually set (Figure 1) for the acquisition of short and long axis segmented cine SSFP images covering the entire ventricular volumes (bandwidth of 700-750 Hz/ pixel and echo spacing of 3.4 ms). The same sequences were then repeated with the offset reset to 0 Hz (only change made) but with the use of a novel 3D shimming algorithm restricted to the heart (instead of the entire FOV) based on a patient specific GRE fieldmap previously generated (WIP Siemens, Germany). Images were blindly evaluated for segmental function (normal vs. abnormal), and the presence of artifacts within the heart (none, minor or important the latter meaning that at least one myocardial segment could not be assessed). Ventricular volumes were also blindly mea-

Myocardial iron quantification using modified Look-Locker inversion recovery (MOLLI) T1 mapping at 3 Tesla

Background Quantification of myocardial iron overload is critical for the management of patients with hemochromatosis. The effects of excess iron on T1 and T2* relaxation times correlate directly with tissue iron concentration. T2* became the clinical standard at 1.5T as it can be easily obtained in a fast one breath-hold ECG gated multi-echo GRE sequence. At 3T, however, T2* quantification can be limited by pronounced susceptibility artifacts and signal sampling restraints due to shorter T2* times at higher iron concentrations . Since myocardial T1 time is up to thirty times longer than T2*, it can be quantified with short echo-time inversionrecovery sequences even at high iron concentrations, and is less sensitive to susceptibility artifacts. We aimed to validate a recently developed modified LookLocker inversion recovery (MOLLI) sequence to quantify myocardial T1 in healthy controls and patients with iron overload at 3T, comparing to standard GRE based multi-echo T2* times at 1.5T. Methods A total of 15 normal volunteers and 7 chronic anemia patients (with a myocardial T2* measure <20 ms at 1.5T in the last 2 years, five of these on iron chelating therapy) were prospectively enrolled. Myocardial T2* and T1 times were quantified in the same day, the former using a breath-hold multi-echo GRE sequence at 1.5T (Symphony, Siemens, Erlangen, Germany) and the latter using the T1 mapping -MOLLI sequence at 3T (Verio, Siemens, Erlangen, Germany). All ROIs were placed at mid-interventricular septum, carefully avoiding the blood pool (Fig 1). All analyses were blinded. Results All patients had regular heart rhythm and all MRI exams showed diagnostic image quality. Volunteers and patients had significantly different mean myocardial T2* (27.2 ms +/- 3.9 vs. 15.4 ms +/- 6.3 p<0.05 respectively) and T1 times 1175.7 ms +/- 22.8 vs. 952.1 ms +/- 173.2 p<0.05 respectively). 3T T1 times strongly correlated with 1.5T T2* times (r=0.95 and Fig 2). Using the 3T T1 cut-off of 1130 ms, sensitivity and specificity for 3T

Real-time cardiac magnetic resonance cine imaging with sparse sampling and iterative reconstruction for left-ventricular measures: Comparison with gold-standard segmented steady-state free precession.

BACKGROUND Segmented cine imaging with a steady-state free-precession sequence (Cine-SSFP) is currently the gold standard technique for measuring ventricular volumes and mass, but due to multi breath-hold (BH) requirements, it is prone to misalignment of consecutive slices, time consuming and dependent on respiratory capacity. Real-time cine avoids those limitations, but poor spatial and temporal resolution of conventional sequences has prevented its routine application. We sought to examine the accuracy and feasibility of a newly developed real-time sequence with aggressive under-sampling of k-space using sparse sampling and iterative reconstruction (Cine-RT). METHODS Stacks of short-axis cines were acquired covering both ventricles in a 1.5T system using gold standard Cine-SSFP and Cine-RT. Acquisition parameters for Cine-SSFP were: acquisition matrix of 224×196, temporal resolution of 39ms, retrospective gating, with an average of 8 heartbeats per slice and 1-2 slices/BH. For Cine-RT: acquisition matrix of 224×196, sparse sampling net acceleration factor of 11.3, temporal resolution of 41ms, prospective gating, real-time acquisition of 1 heart-beat/slice and all slices in one BH. LV contours were drawn at end diastole and systole to derive LV volumes and mass. RESULTS Forty-one consecutive patients (15 male; 41±17years) in sinus rhythm were successfully included. All images from Cine-SSFP and Cine-RT were considered to have excellent quality. Cine-RT-derived LV volumes and mass were slightly underestimated but strongly correlated with gold standard Cine-SSFP. Inter- and intra-observer analysis presented similar results between both sequences. CONCLUSIONS Cine-RT featuring sparse sampling and iterative reconstruction can achieve spatial and temporal resolution equivalent to Cine-SSFP, providing excellent image quality, with similar precision measurements and highly correlated and only slightly underestimated volume and mass values.

Pulmonary Artery Compression and Invasion by a Ruptured Giant Thoracic Aortic Aneurysm: A Rare Presentation

Graphical abstract

Prevalence and Prediction of Obstructive Coronary Artery Disease in Patients Undergoing Primary Heart Valve Surgery

Background The prevalence of coronary artery disease (CAD) in valvular patients is similar to that of the general population, with the usual association with traditional risk factors. Nevertheless, the search for obstructive CAD is more aggressive in the preoperative period of patients with valvular heart disease, resulting in the indication of invasive coronary angiography (ICA) to almost all adult patients, because it is believed that coronary artery bypass surgery should be associated with valve replacement. Objectives To evaluate the prevalence of obstructive CAD and factors associated with it in adult candidates for primary heart valve surgery between 2001 and 2014 at the National Institute of Cardiology (INC) and, thus, derive and validate a predictive obstructive CAD score. Methods Cross-sectional study evaluating 2898 patients with indication for heart surgery of any etiology. Of those, 712 patients, who had valvular heart disease and underwent ICA in the 12 months prior to surgery, were included. The P value < 0.05 was adopted as statistical significance. Results The prevalence of obstructive CAD was 20%. A predictive model of obstructive CAD was created from multivariate logistic regression, using the variables age, chest pain, family history of CAD, systemic arterial hypertension, diabetes mellitus, dyslipidemia, smoking, and male gender. The model showed excellent correlation and calibration (R² = 0.98), as well as excellent accuracy (ROC of 0.848; 95%CI: 0.817-0.879) and validation (ROC of 0.877; 95%CI: 0.830 - 0.923) in different valve populations. Conclusions Obstructive CAD can be estimated from clinical data of adult candidates for valve repair surgery, using a simple, accurate and validated score, easy to apply in clinical practice, which may contribute to changes in the preoperative strategy of acquired heart valve surgery in patients with a lower probability of obstructive disease.

Influence of the tilt angle of Percutaneous Aortic Prosthesis on Velocity and Shear Stress Fields

Background Due to the nature of the percutaneous prosthesis deployment process, a variation in its final position is expected. Prosthetic valve placement will define the spatial location of its effective orifice in relation to the aortic annulus. The blood flow pattern in the ascending aorta is related to the aortic remodeling process, and depends on the spatial location of the effective orifice. The hemodynamic effect of small variations in the angle of inclination of the effective orifice has not been studied in detail. Objective To implement an in vitro simulation to characterize the hydrodynamic blood flow pattern associated with small variations in the effective orifice inclination. Methods A three-dimensional aortic phantom was constructed, reproducing the anatomy of one patient submitted to percutaneous aortic valve implantation. Flow analysis was performed by use of the Particle Image Velocimetry technique. The flow pattern in the ascending aorta was characterized for six flow rate levels. In addition, six angles of inclination of the effective orifice were assessed. Results The effective orifice at the -4º and -2º angles directed the main flow towards the anterior wall of the aortic model, inducing asymmetric and high shear stress in that region. However, the effective orifice at the +3º and +5º angles mimics the physiological pattern, centralizing the main flow and promoting a symmetric distribution of shear stress. Conclusion The measurements performed suggest that small changes in the angle of inclination of the percutaneous prosthesis aid in the generation of a physiological hemodynamic pattern, and can contribute to reduce aortic remodeling.

Factors Associated With Coronary Artery Disease Progression Assessed By Serial Coronary Computed Tomography Angiography

Background Coronary computed tomography angiography (CCTA) allows for noninvasive coronary artery disease (CAD) phenotyping. Factors related to CAD progression are epidemiologically valuable. Objective To identify factors associated with CAD progression in patients undergoing sequential CCTA testing. Methods We retrospectively analyzed 384 consecutive patients who had at least two CCTA studies between December 2005 and March 2013. Due to limitations in the quantification of CAD progression, we excluded patients who had undergone surgical revascularization previously or percutaneous coronary intervention (PCI) between studies. CAD progression was defined as any increase in the adapted segment stenosis score (calculated using the number of diseased segments and stenosis severity) in all coronary segments without stent (in-stent restenosis was excluded from the analysis). Stepwise logistic regression was used to assess variables associated with CAD progression. Results From a final population of 234 patients, a total of 117 (50%) had CAD progression. In a model accounting for major CAD risk factors and other baseline characteristics, only age (odds ratio [OR] 1.04, 95% confidence interval [95%CI] 1.01-1.07), interstudy interval (OR 1.03, 95%CI 1.01-1.04), and past PCI (OR 3.66, 95%CI 1.77-7.55) showed an independent relationship with CAD progression. Conclusions A history of PCI with stent placement was independently associated with a 3.7-fold increase in the odds of CAD progression, excluding in-stent restenosis. Age and interstudy interval were also independent predictors of progression.

Initial experience with a cardiac multi-contrast real-time cine prototype integrating sparse sampling and iterative reconstruction.

Methods All patients were submitted to a conventional cardiac magnetic resonance study (Magnetom Aera, Siemens AG Healthcare, Germany) that included shortand long-axis steady-state free-precession (SSFP) segmented cine measurements (spatial resol.: 1.5x1.5 mm; slice thickness: 7 mm; temporal resol.: 40 ms; 7 heart beats (HB)/slice), modified Look-Locker inversion recovery post-contrast T1 mapping (spatial resol.: 1.6x1.6 mm; slice thickness: 8 mm; 17 HB/slice), and segmented spoiled gradient-echo late gadolinium enhancement (LGE) images (spatial resol.: 1.6x1.6 mm; slice thickness: 8 mm; 8-10 HB/slice). Followed by multi-TI real-time cine performed in the same cardiac planes (spatial resol.: 2.1x2.1 mm; slice thickness: 8 mm; temporal resol.: 45 ms; 4 HB/slice). The multi-TI cine prototype has been described in detail elsewhere, but briefly it consists of an inversion recovery highly accelerated SSFP 2D real-time cine sequence, featuring sparse sampling and k-t regularization. Using an offline reconstruction algorithm based on a registration and motion-propagation strategy, a full-length cine can be reconstructed for each acquired TI (fig. 1) and also a pseudo-T1 map cine. Results A total of 12 consecutive patients (61% male, 50±19 yrs) were included. All sequences were successfully performed and reconstructed, rendering good-quality images on subjective analysis. In all patients, a multi-TI cine, with ideal myocardial nulling, could be produced for simultaneous cardiac function and LGE analysis. Figure 2 illustrates a case of myocardial infarction with evident apical fibrosis on LGE and post-contrast T1 map, associated with akinesia of the involved segments on standard cines. On multi-TI cine, both abnormalities could be fully appreciated. In a subject with myocarditis, subtle mesocardial LGE without segmental contractility dysfunction was also adequately depicted on multi-TI cines (fig. 1). Conventional cine and LGE together required more time and breath-holds than multi-TI cines (745±210 seconds and 13±1 BH vs. 357±39 seconds and 3±0 BH respectively).