Marco Gatti

Cardiovascular magnetic resonance as a reliable alternative to cardiovascular computed tomography and transesophageal echocardiography for aortic annulus valve sizing

To assess the accuracy and reproducibly of cardiovascular magnetic resonance (CMR) in the measurement of the aortic annulus and in process of valve sizing as compared to intra-operative sizing, cardiovascular computed tomography (CCT) and transesophageal echocardiography (TEE). Retrospective study on 42 patients who underwent aortic valve replacement from September 2010 to September 2015, with available records of pre surgery annulus assessment by CMR, CCT and TEE and of peri-operative assessment. In CCT and CMR, the annular plane was considered a virtual ring formed by the lowest hinge points of the valvular attachments to the aorta. In TEE the annulus was measured at the base of leaflet insertion in the mid-esophageal long-axis view using the X-plane technique. Two double-blinded operators performed the assessments for each imaging technique. Intra-operative evaluation was performed using Hegar dilators. Continuous variables were studied with within-subject ANOVA, Bland–Altman (BA) plots, Wilcoxon’s and Friedman’s tests; trends were explored with scatter plots. Categorical variables were studied with Fisher’s exact test. The intra- and inter-operator reliability was satisfying. There were no significant differences between the annulus dimensions measured by CMR and either one of the three references. Valve sizing for CoreValve by CMR had the same good agreement with CCT and TEE, with a 78 % match rate; for SAPIEN XT the agreement was slightly better (82 %) for CCT than for TEE (66 %). MR performs well when compared to the surgical reference of intra-operative sizing and stands up to the level of the most used imaging references (CCT and TEE).

Impact of a New Adaptive Statistical Iterative Reconstruction (ASIR)-V Algorithm on Image Quality in Coronary Computed Tomography Angiography

RATIONALE AND OBJECTIVES A new postprocessing algorithm named adaptive statistical iterative reconstruction (ASIR)-V has been recently introduced. The aim of this article was to analyze the impact of ASIR-V algorithm on signal, noise, and image quality of coronary computed tomography angiography. MATERIALS AND METHODS Fifty consecutive patients underwent clinically indicated coronary computed tomography angiography (Revolution CT; GE Healthcare, Milwaukee, WI). Images were reconstructed using filtered back projection and ASIR-V 0%, and a combination of filtered back projection and ASIR-V 20%-80% and ASIR-V 100%. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated for left main coronary artery (LM), left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA) and were compared between the different postprocessing algorithms used. Similarly a four-point Likert image quality score of coronary segments was graded for each dataset and compared. A cutoff value of P < .05 was considered statistically significant. RESULTS Compared to ASIR-V 0%, ASIR-V 100% demonstrated a significant reduction of image noise in all coronaries (P < .01). Compared to ASIR-V 0%, SNR was significantly higher with ASIR-V 60% in LM (P < .01), LAD (P < .05), LCX (P < .05), and RCA (P < .01). Compared to ASIR-V 0%, CNR for ASIR-V ≥60% was significantly improved in LM (P < .01), LAD (P < .05), and RCA (P < .01), whereas LCX demonstrated a significant improvement with ASIR-V ≥80%. ASIR-V 60% had significantly better Likert image quality scores compared to ASIR-V 0% in segment-, vessel-, and patient-based analyses (P < .01). CONCLUSIONS Reconstruction with ASIR-V 60% provides the optimal balance between image noise, SNR, CNR, and image quality.

MR with Gd-EOB-DTPA in assessment of liver nodules in cirrhotic patients

To date the imaging diagnosis of liver lesions is based mainly on the identification of vascular features, which are typical of overt hepatocellular carcinoma (HCC), but the hepatocarcinogenesis is a complex and multistep event during which, a spectrum of nodules develop within the liver parenchyma, including benign small and large regenerative nodule (RN), low-grade dysplastic nodule (LGDN), high-grade dysplastic nodule (HGDN), early HCC, and well differentiated HCC. These nodules may be characterised not only on the basis of their respective different blood supplies, but also on their different hepatocyte function. Recently, in liver imaging the introduction of hepatobiliary magnetic resonance imaging contrast agent offered the clinicians the possibility to obtain, at once, information not only related to the vascular changes of liver nodules but also information on hepatocyte function. For this reasons this new approach becomes the most relevant diagnostic clue for differentiating low-risk nodules (LGDN-RN) from high-risk nodules (HGDN/early HCC or overt HCC) and consequently new diagnostic algorithms for HCC have been proposed. The use of hepatobiliary contrast agents is constantly increasing and gradually changing the standard of diagnosis of HCC. The main purpose of this review is to underline the added value of Gd-EOB-DTPA in early-stage diagnoses of HCC. We also analyse the guidelines for the diagnosis and management of HCC, the key concepts of HCC development, growth and spread and the imaging appearance of precursor nodules that eventually may transform into overt HCC.

Recent advances in non-invasive magnetic resonance imaging assessment of hepatocellular carcinoma

Magnetic resonance (MR) imaging of the liver is an important tool for the detection and characterization of focal liver lesions and for assessment of diffuse liver disease, having several intrinsic characteristics, represented by high soft tissue contrast, avoidance of ionizing radiation or iodinated contrast media, and more recently, by application of several functional imaging techniques (i.e., diffusion-weighted sequences, hepatobiliary contrast agents, perfusion imaging, magnetic resonance (MR)-elastography, and radiomics analysis). MR functional imaging techniques are extensively used both in routine practice and in the field of clinical and pre-clinical research because, through a qualitative rather than quantitative approach, they can offer valuable information about tumor tissue and tissue architecture, cellular biomarkers related to the hepatocellular functions, or tissue vascularization profiles related to tumor and tissue biology. This kind of approach offers in vivo physiological parameters, capable of evaluating physiological and pathological modifications of tissues, by the analysis of quantitative data that could be used in tumor detection, characterization, treatment selection, and follow-up, in addition to those obtained from standard morphological imaging. In this review we provide an overview of recent advanced techniques in MR for the diagnosis and staging of hepatocellular carcinoma, and their role in the assessment of response treatment evaluation.

Con motivo del centenario de la Revista Española de Enfermedades Digestivas (REED)

BACKGROUND AND PURPOSE magnetic resonance enterography has been increasingly used for the diagnosis and follow-up of Crohns disease (CD). The purpose of the study was to compare the apparent diffusion coefficient (ADC) with wall enhancement for the differentiation of severe, moderate or no inflammation activity in the ileum. METHODS a prospective, blinded study was conducted of 46 CD patients with a clinical Crohns disease activity index (CDAI) ≥ 220 and a simple endoscopic score for Crohns disease (ES-CD) ≥ 7, which yielded 58 inflamed segments with CD. Twenty controls were also included. All segments were characterized by four ADC readings. The two different enhancement patterns observed in inflamed segments, transmural or mucosal, were associated with severely (23) or moderately (35) active CD. RESULTS the ADC value decreased from 2.79 ± 0.35 x 10-3 mm2/s for normal segments to 1.81 ± 0.39 x 10-3 mm2/s for the moderately inflamed segments and 1.15 ± 0.20 x 10-3 mm2/s for severely inflamed segments (p ≤ 0.0001). ROC curve analysis on the basis of the three ADC distributions showed a very good discrimination capability with an area under the curve of 0.95. Three groups were defined as follows: normal ileum ADC > 2.4 x 10-3 mm2/s, moderate stages of inflammation 1.5 x 10-3 mm2/s < ADC ≤ 2.4 x 10-3 mm2/s and severe stages of ADC ≤ 1.5 x 10-3 mm2/s. CONCLUSIONS the ADC value reliably discriminates between normal and inflamed ileum and also distinguishes between severe and moderate inflammation.

Plan optimization for mediastinal radiotherapy: Estimation of coronary arteries motion with ECG-gated cardiac imaging and creation of compensatory expansion margins

BACKGROUND AND PURPOSE Inadvertent heart and coronary arteries (CA) irradiation may increase the risk of coronary artery disease (CAD) in patients receiving thoracic irradiation. To date, the entity of cardiac-related CA displacement and the possible margins to be used for planning organs at risk volume (PRV) have been poorly described. Aim of this study was to quantify CA displacement and to estimate PRV through the use of ECG-gated computed tomography (CT) scans. MATERIAL AND METHODS Eight patients received an ECG-gated intravenous contrast enhanced CT for non-cancer related reasons. Nine data sets were reconstructed over the entire R-R cycle with a dedicated retrospective algorithm and the following structures were delineated: Left main trunk (LM), left anterior descending (LAD), left circumflex (CX) and right coronary artery (RCA). CA displacements across the different cardiac phases were evaluated in left-right (X), cranio-caudal (Y) and anteroposterior (Z) directions using the McKenzie-van Herk formula (1.3 * Σ + 0.5 * σ). RESULTS The following CA displacements were found in X, Y and Z coordinates: 3.6, 2.7 and 2.7 mm for LMT, respectively; 2.6, 5.0 and 6.8 mm for LAD, respectively; 3.5, 4.5 and 3.7 mm for CX, respectively; 3.6, 4.6 and 6.9 mm for RCA, respectively. Based on the mean displacements, we created a PRV of 3 mm for LM, 4 mm for CX and 5 mm for LAD and RCA. CONCLUSION CA showed relevant displacements over the heart cycle, suggesting the need for a specific PRV margin to accurately estimate the dose received by these structures and optimize the planning process.

Evaluation of incidence of acute transient dyspnea and related artifacts after administration of gadoxetate disodium: a prospective observational study

AimsTo evaluate motion artifacts, breath-hold failure, acute transient dyspnea, and clinical parameters during hepatic arterial phase of gadoxetate disodium-enhanced magnetic resonance (MR) imaging.MethodsThis was an institutional review board-approved observational prospective study (written informed consent acquired) performed in 250 consecutive patients, who underwent liver MR with a multiarterial phase technique. Oxygen saturation (SatO2) and heart rate (HR) were monitored, while patients reported subjective symptoms. Breath-holds were assessed using prospective acquisition correction technique (PACE) monitors. Three readers independently analyzed all images to establish the presence of motion artifacts. Nonparametric statistical testing and Fleiss’ kappa were used.ResultsNo statistical differences in SatO2 and HR values were observed during the entire length of MR examination. The PACE graphs showed an altered breath-hold in 16/250 patients (6.4%), however only 6 patients self-reported symptoms during the procedure, and among these 6 subjects, only 2 suffered from acute transient dyspnea (0.8%). Motion-related artifacts increased mostly in the third arterial phase of gadoxetate disodium acquisition (p < 0.0001): The artifacts incidence was 2.9% in the first phase; 4.0% in the second; and 19.5% in the third. This increase was mainly due to patients’ inability to hold their breath for the entire duration of the examination. However, at least one gadoxetate disodium arterial phase without motion artifacts and adequate for acquisition timing, was acquired in all MR examinations.ConclusionThe incidence of breath-hold failure and acute transient dyspnea after gadoxetate disodium administration increased during the third arterial phase only. Our protocol allowed the acquisition of at least one arterial phase not compromised by motion artifacts and adequate for acquisition timing, in all patients.

eComment. Re: Is cardiac magnetic resonance imaging as accurate as echocardiography in the assessment of aortic valve stenosis?

Aortic stenosis (AS) is the most frequent degenerative valvular heart disease in Western countries and its prevalence increases with an ageing population [1]. Interestingly, Wong and colleagues [2] have analysed a very common clinical scenario of a 72-year old man with an incidental diagnosis of AS on routine transthoracic echocardiography to answer the question: “Is cardiac magnetic resonance (CMR) imaging as accurate as echocardiography in the assessment of aortic valve stenosis?” They selected and level-headedly examine 12 out of more than 200 papers to reach the answer and they conclude that CMR is as accurate as echocardiography in the evaluation of patients with aortic valve stenosis, and that CMR has better interand intraobserver reliability and demonstrates an advantage over echocardiography in the detection of severe AS with greater specificity and sensitivity. It must also be emphasized that dobutamine stress echocardiography may help to differentiate between severe AS and pseudo severe AS and to assess the presence of LV contractile or flow reserve, which has been associated with better prognosis in patients undergoing surgical aortic valve replacement [3]. The advent of new echocardiographic techniques, such as speckle tracking echocardiography has also enabled the detection of eventually associated early myocardial damage in the left ventricle and have a good correlations with the extent of myocardial scar assessed found at MR late gadolinium enhancement (LGE) [4]. The contrast enhanced CMR with the LGE evaluation or better still, the new technique of T1 mapping could evidence the presence of scar, replacement focal fibrosis or interstitial diffuse fibrosis that are associated with worse prognosis [5]. Overall, the final conclusion of the authors that “the final choice, however, is as likely to be influenced by the availability of magnetic resonance imaging and expertise in interpreting the results as on accuracy and reliability” clearly represent the everyday real-life scenario.