Detecting small pulmonary nodules with spiral ultrashort echo time sequences in 1.5 T MRI.

OBJECTIVE: This study investigated ultrashort echo time (UTE) sequences in 1.5 T magnetic resonance imaging (MRI) for small lung nodule detection. MATERIALS AND METHODS: A total of 120 patients with 165 small lung nodules before video-associated thoracoscopic resection were enrolled. MRI sequences included conventional volumetric interpolated breath-hold examination (VIBE, scan time 16 s), spiral UTE (TE 0.05 ms) with free-breathing (scan time 3.5-5 min), and breath-hold sequences (scan time 20 s). Chest CT provided a standard reference for nodule size and morphology. Nodule detection sensitivity was evaluated on a lobe-by-lobe basis. RESULTS: The nodule detection rate was significantly higher in spiral UTE free-breathing (> 78%, p < 0.05) and breath-hold sequences (> 75%, p < 0.05) compared with conventional VIBE (> 55%), reaching 100% when nodule size was > 16 mm, and reaching 95% when nodules were in solid morphology, regardless of size. The inter-sequence reliability between free-breathing and breath-hold spiral UTE was good (κ > 0.80). Inter-reader agreement was also high (κ > 0.77) for spiral UTE sequences. Nodule size measurements were consistent between CT and spiral UTE MRI, with a minimal bias up to 0.2 mm. DISCUSSION: Spiral UTE sequences detect small lung nodules that warrant surgery, offers realistic scan times for clinical work, and could be implemented as part of routine lung MRI.

Applying Compressed Sensing Volumetric Interpolated Breath-Hold Examination and Spiral Ultrashort Echo Time Sequences for Lung Nodule Detection in MRI.

This prospective study aimed to investigate the ability of spiral ultrashort echo time (UTE) and compressed sensing volumetric interpolated breath-hold examination (CS-VIBE) sequences in magnetic resonance imaging (MRI) compared to conventional VIBE and chest computed tomography (CT) in terms of image quality and small nodule detection. Patients with small lung nodules scheduled for video-assisted thoracoscopic surgery (VATS) for lung wedge resection were prospectively enrolled. Each patient underwent non-contrast chest CT and non-contrast MRI on the same day prior to thoracic surgery. The chest CT was performed to obtain a standard reference for nodule size, location, and morphology. The chest MRI included breath-hold conventional VIBE and CS-VIBE with scanning durations of 11 and 13 s, respectively, and free-breathing spiral UTE for 3.5-5 min. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and normal structure visualizations were measured to evaluate MRI quality. Nodule detection sensitivity was evaluated on a lobe-by-lobe basis. Inter-reader and inter-modality reliability analyses were performed using the Cohen κ statistic and the nodule size comparison was performed using Bland-Altman plots. Among 96 pulmonary nodules requiring surgery, the average nodule diameter was 7.7 ± 3.9 mm (range: 4-20 mm); of the 73 resected nodules, most were invasive cancer (74%) or pre-invasive carcinoma in situ (15%). Both spiral UTE and CS-VIBE images achieved significantly higher overall image quality scores, SNRs, and CNRs than conventional VIBE. Spiral UTE (81%) and CS-VIBE (83%) achieved a higher lung nodule detection rate than conventional VIBE (53%). Specifically, the nodule detection rate for spiral UTE and CS-VIBE reached 95% and 100% for nodules >8 and >10 mm, respectively. A 90% detection rate was achieved for nodules of all sizes with a part-solid or solid morphology. Spiral UTE and CS-VIBE under-estimated the nodule size by 0.2 ± 1.4 mm with 95% limits of agreement from -2.6 to 2.9 mm and by 0.2 ± 1.7 mm with 95% limits of agreement from -3.3 to 3.5 mm, respectively, compared to the reference CT. In conclusion, chest CT remains the gold standard for lung nodule detection due to its high image resolutions. Both spiral UTE and CS-VIBE MRI could detect small lung nodules requiring surgery and could be considered a potential alternative to chest CT; however, their clinical application requires further investigation.

Long-term outcomes and left ventricular diastolic function of sarcomere mutation-positive and mutation-negative patients with hypertrophic cardiomyopathy: a prospective cohort study.

AIMS: Hypertrophic cardiomyopathy (HCM) is an inheritable disease that leads to sudden cardiac death and heart failure (HF). Sarcomere mutations (SMs) have been associated with HF. However, the differences in ventricular function between SM-positive and SM-negative HCM patients are poorly characterized. METHODS AND RESULTS: Of the prospectively enrolled 374 unrelated HCM patients in Taiwan, 115 patients underwent both 91 cardiomyopathy-related gene screening and cardiovascular magnetic resonance (45.6 ± 10.6 years old, 76.5% were male). Forty pathogenic/likely pathogenic mutations were identified in 52 patients by next-generation sequencing. The SM-positive group were younger at first cardiovascular event (P = 0.04) and progression to diastolic HF (P = 0.02) with higher N-terminal pro-brain natriuretic peptide (NT-proBNP) [New York Heart Association (NYHA) Class III/IV symptoms with left ventricular ejection fraction > 55%] than the SM-negative group (P < 0.001). SM-positive patients had a greater extent of late gadolinium enhancement (P = 0.01), larger left atrial diameter (P = 0.03), higher normalized peak filling rate (PFR) and PFR ratio, and a greater reduction in global longitudinal strain than SM-negative patients (all P ≤ 0.01). During mean lifelong follow-up time (49.2 ± 15.6 years), SM-positive was a predictor of earlier HF (NYHA Class III/IV symptoms) after multivariate adjustment (hazard ratio 3.5; 95% confidence interval 1.3-9.7; P = 0.015). CONCLUSION: SM-positive HCM patients had a higher extent of myocardial fibrosis and more severe ventricular diastolic dysfunction than those without, which may contribute to earlier onset of advanced HF, suggesting the importance of close surveillance and early treatment throughout life.

Empirical Mode Decomposition and Monogenic Signal-Based Approach for Quantification of Myocardial Infarction From MR Images.

Quantification of myocardial infarction on late Gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) images into heterogeneous infarct periphery (or gray zone) and infarct core plays an important role in cardiac diagnosis, especially in identifying patients at high risk of cardiovascular mortality. However, quantification task is challenging due to noise corrupted in cardiac MR images, the contrast variation, and limited resolution of images. In this study, we propose a novel approach for automatic myocardial infarction quantification, termed DEMPOT, which consists of three key parts: Decomposition of image into intrinsic modes, monogenic phase performing on combined dominant modes, and multilevel Otsu thresholding on the phase. In particular, inspired by the Hilbert-Huang transform, we perform the multidimensional ensemble empirical mode decomposition and 2-D generalization of the Hilbert transform known as the Riesz transform on the MR image to obtain the monogenic phase that is robust to noise and contrast variation. Then, a two-stage algorithm using multilevel Otsu thresholding is accomplished on the monogenic phase to automatically quantify the myocardium into healthy, gray zone, and infarct core regions. Experiments on LGE-CMR images with myocardial infarction from 82 patients show the superior performance of the proposed approach in terms of reproducibility, robustness, and effectiveness.

Introduction to Cardiovascular Magnetic Resonance: Technical Principles and Clinical Applications.

UNLABELLED: Cardiovascular magnetic resonance (CMR) is a set of magnetic resonance imaging (MRI) techniques designed to assess cardiovascular morphology, ventricular function, myocardial perfusion, tissue characterization, flow quantification and coronary artery disease. Since MRI is a non-invasive tool and free of radiation, it is suitable for longitudinal monitoring of treatment effect and follow-up of disease progress. Compared to MRI of other body parts, CMR faces specific challenges from cardiac and respiratory motion. Therefore, CMR requires synchronous cardiac and respiratory gating or breath-holding techniques to overcome motion artifacts. This article will review the basic principles of MRI and introduce the CMR techniques that can be optimized for enhanced clinical assessment. KEY WORDS: Cardiovascular MR • Coronary arteries • Flow quantification • Myocardial fibrosis • Myocardial perfusion • Myocardial scarring • Regional wall motion • Ventricular function.

Myocardial Regional Interstitial Fibrosis is Associated With Left Intra-Ventricular Dyssynchrony in Patients With Heart Failure: A Cardiovascular Magnetic Resonance Study.

Left ventricular (LV) dyssynchrony is associated with poor prognosis in patients with heart failure (HF). The mechanisms leading to LV dyssynchrony are not fully elucidated. This study evaluates whether myocardium regional variation in interstitial fibrosis is associated with LV dyssynchrony. Forty-two patients with systolic heart failure (SHF), 76 patients with heart failure with preserved ejection fraction (HFpEF) and 20 patients without HF received cardiovascular magnetic resonance imaging (MRI) study. LV was divided into 18 segments by short-axis view. In each segment, regional extracellular volume fraction (ECV) and the time taken to reach minimum regional volume (Tmv) were derived. Intra-LV dyssynchrony were represented by maximum difference (Dysyn_max) and standard deviation (Dysyn_sd) of all Tmv. The results showed that among the covariates, only age (1.87, 95% CI: 0.61-3.13, p = 0.004) and ECV (3.77, 95% CI: 2.72-4.81, p < 0.001) were positively associated with Tmv. The results remained robust in certain subgroups. In conclusion, we demonstrated that LV myocardium regional variation in interstitial fibrosis is closely related to LV intra-ventricular dyssynchrony irrespective of the LV global function. These data might help explain the pathophysiology of LV dyssynchrony and it's underlying mechanisms leading to poor prognosis.

Circulating biomarkers of collagen type I metabolism mark the right ventricular fibrosis and adverse markers of clinical outcome in adults with repaired tetralogy of Fallot.

BACKGROUND: Right ventricular (RV) fibrosis is common in patients with repaired tetralogy of Fallot (rTOF). Although accumulating evidence indicates the role of circulating biomarkers of collagen metabolism in left ventricular fibrosis, rTOF data are lacking. This study examined the expression profile and clinical relevance of circulating biomarkers of collagen type I metabolism in rTOF patients. METHODS: Serum biomarkers of collagen type I synthesis (carboxy-terminal propeptide of procollagen type I, PICP), degradation (carboxy-terminal telopeptide of collagen type I, CITP), and enzymes regulating collagen degradation (matrix metalloproteinases, and type I tissue inhibitor, TIMP-1) were measured in 70 rTOF and 91 control adults. All patients had complete clinical data and received cardiovascular magnetic resonance scans with late gadolinium enhancement (LGE). RESULTS: Compared to the controls, rTOF patients had higher PICP levels (p<0.001), PICP:CITP ratios (p<0.001), and TIMP-1 concentrations (p<0.001). Increasing PICP levels correlated with higher RV LGE scores (r=0.427, p<0.001), lower VO2max (r=-0.428, p=0.002), and larger RV volumes. Furthermore, stepwise multivariate linear regression analysis identified RV end-diastolic volume index >150mL/m(2) (ß=40.52, p=0.016), RV LGE score (ß=3.94, p=0.008), and age (ß=-1.77, p=0.011) as independent correlates of circulating PICP levels. CONCLUSIONS: Patients with rTOF exhibited a profibrotic state with excessive collagen type I synthesis and dysregulated degradation. Elevated circulating PICP levels might reflect RV fibrosis, and link to adverse markers of clinical outcome.

Effect of cardiac rehabilitation on myocardial perfusion reserve in postinfarction patients.

Cardiac rehabilitation is believed to increase myocardial perfusion reserve (MPR), but this has not been adequately studied because of poor delineation of infarcted myocardium in previous studies. The purpose of this study was to determine the effect of cardiac rehabilitation on MPR in the remote and infarcted myocardium with contrast-enhanced magnetic resonance imaging; 39 postinfarction patients were recruited for this study and randomly assigned to a training group (n = 20) or a nontraining group (n = 19). Those in the training group participated in a 3-month rehabilitation training program at an exercise intensity of 55% to 70% of peak oxygen uptake (VO2); those in the nontraining group continued their usual lifestyle. Nineteen age-, weight-, and height-matched subjects without cardiovascular risk factors were selected as healthy controls. After myocardial infarction, a reduction in perfusion reserve was seen not only in the infarcted myocardium, but also in the remote myocardium. In the training group, exercise capacity increased by 15% (p <0.01), to the same level as in healthy controls. The post-training MPR increased in both remote (30%, p <0.01) and infarcted myocardium (25%, p <0.05) and reached the same level as in healthy controls. The change in exercise capacity correlated with the change in MPR in the remote myocardium (r = 0.55, p <0.001 for peak VO2). In the nontraining group, exercise capacity and MPR were unchanged. In conclusion, cardiac rehabilitation improves perfusion reserve in both infarcted and remote myocardium, with a parallel increase in exercise capacity.