Image resampling and discretization effect on the estimate of myocardial radiomic features from T1 and T2 mapping in hypertrophic cardiomyopathy.

Radiomics is emerging as a promising and useful tool in cardiac magnetic resonance (CMR) imaging applications. Accordingly, the purpose of this study was to investigate, for the first time, the effect of image resampling/discretization and filtering on radiomic features estimation from quantitative CMR T1 and T2 mapping. Specifically, T1 and T2 maps of 26 patients with hypertrophic cardiomyopathy (HCM) were used to estimate 98 radiomic features for 7 different resampling voxel sizes (at fixed bin width), 9 different bin widths (at fixed resampling voxel size), and 7 different spatial filters (at fixed resampling voxel size/bin width). While we found a remarkable dependence of myocardial radiomic features from T1 and T2 mapping on image filters, many radiomic features showed a limited sensitivity to resampling voxel size/bin width, in terms of intraclass correlation coefficient (> 0.75) and coefficient of variation (< 30%). The estimate of most textural radiomic features showed a linear significant (p < 0.05) correlation with resampling voxel size/bin width. Overall, radiomic features from T2 maps have proven to be less sensitive to image preprocessing than those from T1 maps, especially when varying bin width. Our results might corroborate the potential of radiomics from T1/T2 mapping in HCM and hopefully in other myocardial diseases.

Diagnostic and Prognostic Role of Cardiac Magnetic Resonance Before Implantable Cardioverter Defibrillator.

The use of cardiac magnetic resonance (cMR) to assess remodeling and tissue characterization in primitive and secondary cardiomyopathies has progressively increased, and it carries important prognostic informations. The aim of this study was to assess the overall clinical value of cMR before implantable cardioverter defibrillator (ICD). All patients referred to our center for an ICD implantation and submitted to cMR (n = 134) were analyzed. All the cMR diagnostic findings and following clinical events were reviewed to assess clinical relevance in patients care. The use of cMR before ICD implantation has progressively increased during the decade studied (13% to 53%, p <0.001). Subjects who underwent cMR were younger, more often female, with lower NYHA class and higher ejection fraction (p <0.05 for all). Unexpected diagnostic findings were observed in 34 patients (25%), resulting in an immediate therapeutic strategy modification in 13%. A pattern of fibrosis leading to a change in the disease's etiology and thrombus detection were the most frequent cMR findings, followed by anatomical incidental findings. Any grade of fibrosis carried a higher annual incidence of combined death or ventricular arrhythmias (9.92% vs 1.83%, p = 0.02). Annual event rate was related to the extent of scarring. In conclusion, we observed a progressively increase of cMR utilization before ICD implantation during the last decade. This practice has yielded a significant increase of new diagnostic findings, carrying unique prognostic information linked to tissue characterization.

T1 and T2 mapping in the identification of acute myocardial injury in patients with NSTEMI.

AIMS: To test T1 and T2 mapping in the assessment of acute myocardial injury in patients with non-ST-segment elevation myocardial infarction (NSTEMI), evaluated before revascularization. METHODS: Forty-seven patients with acute NSTEMI underwent cardiac magnetic resonance (CMR) at 1.5 T, including T1 and T2 mapping. RESULTS: Coronary angiography (CA) evidenced an obstructive coronary artery disease (CAD) in 36 patients (80%) and a non-obstructive CAD in 11 patients (20%). Edema was detected in 51.1/65.9% of patients in T1/T2 maps, respectively. This difference was due to artifacts in T1 maps. T1/T2 values were significantly higher in the infarcted myocardium (IM) compared with the remote myocardium (RM) (in T1: 1151.6 ± 53.5 ms vs. 958.2 ± 38.6 ms, respectively; in T2: 69 ± 6 ms vs. 51.9 ± 2.9 ms, respectively; p < 0.0001 for both). We found both an obstructive CAD at CA and myocardial edema at CMR in 53.2% of patients, while 8.5% of patients had a non-obstructive CAD and no edema. However, 25.5% of patients had an obstructive CAD without edema, while 12.8% of patients showed edema despite a non-obstructive CAD. Furthermore, in 6 of the edema-positive patients with multi-vessels obstructive CAD, CMR identified myocardial edema in a vascular territory different from that of the lesion supposed to be the culprit at CA. CONCLUSIONS: In a non-negligible percentage of NSTEMI patients, T1 and T2 mapping detect myocardial edema without significant stenosis at CA and vice versa. Therefore, CA and CMR edema imaging might provide complementary information in the evaluation of NSTEMI.

[Teamwork for cardiac imaging: coronary computed tomography angiography and low-dose radiation exposure: a cardiology center experience]. / Teamwork per l'imaging cardiaco: tomografia computerizzata coronarica e bassa dose di esposizione radiologica, esperienza di un centro cardiologico.

BACKGROUND: Multidetector coronary computed tomography angiography (CCTA) is increasingly used for noninvasive imaging of the coronary arteries. Radiation exposure, however, is a potential limitation to a more extensive use of this imaging modality. We aimed to demonstrate that a professional teamwork approach, including a cardiologist and a radiologist in performing CCTA, may allow to obtain best quality exams with very low radiation doses. METHODS: A total of 998 consecutive patients underwent CCTA in accordance with the most recent guidelines. The following procedures were undertaken to reduce the radiation dose: (a) preliminary cardiological evaluation to check for CCTA eligibility; (b) optimized heart rate control with beta-blockers and/or ivabradine; and (c) the use of nonstandardized computed tomography protocols and algorithms for dose reduction. RESULTS: All the patients underwent a preliminary cardiological evaluation; 89% of them were pretreated with oral or intravenous beta-blockers and/or ivabradine; 806 patients (81%) were scanned by means of prospective gating, which allowed a radiation dose exposure of 161 ± 68.64 mGy; 192 patients (19%) underwent a retrospective gating protocol, with a radiation dose exposure of 1135.15 ± 485.87 mGy. In 13 patients (1%) CCTA was uninterpretable because of artifacts. Exam quality was not affected by the use of low-dose computed tomography scanning. Coronary calcium score and/or left ventricular functional analysis were never performed. CONCLUSIONS: The preliminary selection and preparation of patients and optimized scanner utilization allow a substantial reduction in radiation dose for most of the patients submitted to CCTA without affecting image quality. In our experience, a team approach was necessary to allow a "low-dose learning curve" and a progressive reduction in radiation doses administered to patients by means of the prospective gating protocol.

Simultaneous strain-volume analysis by three-dimensional echocardiography: validation in normal subjects with tagging cardiac magnetic resonance.

OBJECTIVE: The aim of this study is to compare three-dimensional echocardiography strain-volume analysis with tagging cardiac magnetic resonance (cMR) measurements. BACKGROUND AND METHODS: Strain-volume analysis represents a noninvasive method to assess myocardial function and volumes simultaneously. It can be derived from echocardiography and speckle-tracking; however, it shows some variability that can limit clinical utilization. A three-dimensional approach partially overcomes these limitations since full-volume acquisition avoids images being foreshortened and geometrical reconstruction. In the study presented here, 23 healthy subjects were studied by three-dimensional echocardiography and cMR during the same session. Images were stored and the better cardiac cycle was chosen for simultaneous analysis of volumes and longitudinal (Long) and circumferential (Circ) strain. By means of full-volume acquisition all parameters can be calculated for each frame of the cardiac cycle using the speckle-tracking method. With cMR, left ventricle volumes were calculated as recommended; myocardial strains were computed in short-axis and long-axis views using the tagging technique. For each patient, volumes and strain values were plotted in a Cartesian system for strain-volume analysis. Data were compared between the two methods using Bland-Altman analysis based on mean difference and 95% limits of agreement (LoA). RESULTS: The volume as measured by three-dimensional echocardiography and cMR was comparable with the slightly higher end-diastolic volumes measured by cMR (mean difference 15.24 ml; LoA -53.6 to 26.5 ml, end-systolic volume 0.3 ml; LoA -19.9 to 20.5 ml). Long shortening was very similar in the two methods (1.5%; LoA -3.9 to 7%), whereas Circ strain was systematically lower with cMR (-8.5%; LoA -15.5 to -1.5%). Very similar values between three-dimensional echo and cMR both for Slope of strain-volume curves (-0.015; LoA -0.08 to 0.05) and ratio (-0.001; LoA -0.04 to 0.04) were observed in the longitudinal plane. Analysis of strain-volume per patient showed a significant correlation coefficient between techniques for both Long Slope (r = 0.65; P = 0.001) and Long Ratio (r = 0.70; P = 0.001). CONCLUSION: Longitudinal strain-volume analysis performed with three-dimensional speckle-tracking echocardiography is closely comparable with cMR, which is usually considered the gold standard for volume and function assessment.

[Prevalence of cardiac and extracardiac incidental findings in the evaluation of coronary artery disease by multidetector computed tomography]. / Prevalenza di reperti occasionali cardiaci ed extracardiaci nella valutazione delle coronarie con tomografia computerizzata multidetettore.

BACKGROUND: With the widespread use of multidetector computed tomography (MDCT) coronary angiography, cardiac and extracardiac incidental findings in cardiac imaging might be detected. The aim of this study was to determine the prevalence of cardiac and extracardiac incidental findings in a population of consecutive patients undergoing coronary MDCT. METHODS: A total of 840 consecutive patients with known or suspected heart disease underwent cardiac MDCT. All patients were assessed with 64-slice MDCT; the examination was performed by limiting the anatomical region examined between the bifurcation of the trachea and the cardiac apex with the aim of obtaining excellent image quality and low cardiac radiological exposure. RESULTS: Overall, 81 incidental findings in 72 patients (9%) were identified, of which 18 were cardiac (2%) and 63 extracardiac (7%). Extracardiac incidental findings were mainly represented by pulmonary nodules (19%). CONCLUSIONS: A significant number of cardiac and extracardiac incidental findings were observed at cardiac MDCT, with the prevalence depending on technical aspects of image acquisition and patient characteristics. Incidental findings should be carefully searched for and reported because they may have an impact on clinical follow-up indications that is not without cost and risk.

Myocardial T1 and T2 mapping in diastolic and systolic phase.

The aim of this study was to evaluate the regional (i.e. myocardial segments) variability as well as the overall image quality of cardiac T1 and T2 maps obtained in diastole and in systole. In 22 healthy subjects (group-1), diastolic T1 and T2 maps were obtained at 1.5 T in short-axis view at basal, mid-ventricular and apical level, as well as in 4-chamber (4 ch) and in 2-chamber (2 ch) views. In another group of 25 patients (group-2), the maps were obtained in both diastole and systole. In the group-1, 15.4% of myocardial segments in T1 maps and 0.8% of myocardial segments in T2 maps, mainly located at apical level, showed relevant artifacts and/or partial-volume effect and had to be discarded. We found no significant difference in T1 values among basal, mid-ventricular and apical segments. T2 values at apical level were significantly higher than at basal and mid-ventricular level (short-axis, p < 0.0001; 4 ch, p < 0.009; 2 ch, p = 0.0002 at ANOVA tests). In the group-2, 21.1%/5.3% and 4.0%/0.8% of segments showed relevant artifacts in diastolic/systolic T1 and T2 maps, respectively. Apical T2 values were significantly lower in systole than in diastole. In systole, there were no significant differences in T1/T2 among basal, mid-ventricular and apical segments. The overall quality of T1 and T2 maps drops in apical segments. This could be problematic when evaluating focal myocardial changes. The acquisition in systole increases the number of evaluable segments.

[T1 and T2 mapping: new perspectives in cardiac magnetic resonance imaging]. / T1 e T2 mapping: nuove prospettive in risonanza magnetica cardiaca.

Cardiac magnetic resonance (MR) imaging is currently considered the gold standard for characterizing changes in myocardial structure, in particular to assess myocardial edema and focal fibrosis. In spite of this potential capability, the traditional MR sequences usually employed for these purposes have significant limitations and provide only qualitative information. Recent developments in cardiac MR imaging techniques currently provide clinically-feasible mapping of T1 and T2 relaxation times, thus providing a quantitative assessment of the parameters of interest. Myocardial edema can be evaluated using T2 mapping techniques. These have shown a superior performance compared to the traditional T2-weighted and STIR sequences, both in acute inflammatory cardiomyopathies and in acute ischemic injury. T1 mapping techniques, performed both with and without contrast medium, enable to quantify diffuse myocardial fibrosis and to assess myocardial edema and infiltration. This article will review current methodologies for cardiac T1 and T2 parametric mapping and their potential and limitations in the assessment of myocardial damage.

Evaluation of Brugada syndrome by cardiac magnetic resonance.

Brugada syndrome (BrS) has been originally considered to occur in structural normal hearts. However recent pathological and imaging data suggest that structural and functional changes may be present in this syndrome. This study was designed to elucidate whether any macroscopic heart abnormality is detectable in patients with BrS. For this purpose we used cardiac magnetic resonance (CMR). Twenty-nine patients displaying the BrS type-1 ECG pattern and 29 healthy controls underwent CMR (1.5 Tesla). Left (LV) and right ventricular (RV) dimensions, function and regional contractility were evaluated. Late-gadolinium-enhancement (LGE) imaging was obtained in 24 patients. We found no difference between BrS patients and controls regarding LV and RV dimensions and ejection fraction. RV wall motion abnormalities (WMA) were detected in 19 patients (65.5%) and in 22 control subjects (75.9%). The majority of these WMA were attributable to areas of hypokinesia and found in the RV inferior wall. None of the patients showed LGE. No differences were detected between controls and the different subgroups of BrS patients according to symptoms, family history and spontaneous type-1 ECG pattern. BrS patients do not differ from normal subjects with regard to dimensions and global function of both LV and RV. BrS patients may show RV-WMA, however similar changes are also present in healthy subjects and may therefore represent a physiological behaviour of RV. The lack of LGE further confirms the absence of myocardial structural damage. Our results indicate that BrS seems to occur in individuals with structurally and functionally normal heart.

Large vestibular aqueduct syndrome: audiological, radiological, clinical, and genetic features.

PURPOSE: The aim of this study was to analyze the clinical, audiological, radiological, and genetic features of a group of patients affected with large vestibular aqueduct syndrome. MATERIALS AND METHODS: Seventeen patients affected with large vestibular aqueduct syndrome (LVAS), diagnosed by means of high-resolution magnetic resonance imaging of the inner ear, with 3-dimensional reconstructions of the labyrinth and by high-resolution spiral computed tomography of the temporal bone, performed only on the oldest patients, have been submitted to a complete audiological evaluation, a thyroid functional and ultrasonographic study, and a molecular study of the PDS gene. RESULTS: The clinical presentation of LVAS was very variable in our group of patients. The enlarged vestibular aqueduct was bilateral in 15 cases and unilateral in 2; it was the only malformation of the labyrinth in 12 patients, whereas it was associated with other inner ear anomalies in the other 5. The hearing loss was very variable in degree (from mild to profound), age at onset, and progression. Moreover, among the 17 patients, 10 were clinically affected by Pendred's syndrome (PS), 3 by distal renal tubular acidosis associated with large vestibular aqueduct, whereas in 3 patients the large vestibular aqueduct was not syndromal. Finally, we identified mutations in the PDS gene in 5 of 10 patients with PS. CONCLUSIONS: Our data underscore the frequent role of the large vestibular aqueduct syndrome in the pathogenesis of sensorineural hearing loss and the overall wide variability in its audiological features. It is also highlighted that LVAS is often part of some syndromal diseases, most of which are PS, which is often misdiagnosed because of the varying degree of thyroid symptoms. This study also underscores the possible role of hydro-electrolyte and acid-base endolymphatic fluid disorders in the pathogenesis of enlarged vestibular aqueduct syndrome.

3-D CT and MRI co-registration in the assessment of cochlear implantation.

BACKGROUND: The aim of this study was to evaluate the feasibility of co-registering preoperative MRI and postoperative CT and to assess the position of the electrode within the cochlea. MATERIAL/METHODS: In a series of 14 patients, high-resolution MRI datasets of the cochlea obtained before implantation and multirow CT datasets obtained after implantation were co-registered using a stereoscopic display and volume-rendering platform (Dextroscope, Volume Interactions/Bracco, Singapore). Image co-registration was performed with a semi-automatic method (multipoint plus freehand fusion). RESULTS: In 2 patients the electrode was correctly inserted in the middle turn of the cochlea and the assigned rank was 4 (corresponding to the initial tract of the middle turn). In 8 patients the rank was 3, meaning that the electrode tip reached the upper portion of the basal turn. In 4 patients the rank was 2, meaning that the electrode tip reached the middle portion of the basal turn; in two of these patients, electrode kinking was observed. CONCLUSIONS: Co-registration of preoperative MRI and postoperative CT is feasible and represents a unique method to assess electrode position within the membranous labyrinth.