Myocardial extracellular volume fraction radiomics analysis for differentiation of reversible versus irreversible myocardial damage and prediction of left ventricular adverse remodeling after ST-elevation myocardial infarction.

OBJECTIVES: Our study sought to explore the prognostic value of radiomic TA (texture analysis) on quantitative ECV (extracellular volume) fraction mapping to differentiate between reversible and irreversible myocardial damage and to predict left ventricular adverse remodeling in patients with reperfused STEMI (ST-elevation myocardial infarction). METHODS: This observational prospective cohort study identified 70 patients (62 ± 9 years, 62 men [85.70%]) with STEMI for TA who consecutively performed native and contrast T1 mapping. Texture features were extracted from each stack of ECV mapping based on ROI (region of interest) analysis. RESULTS: After texture feature selection and dimension reduction, five selected texture features were found to be statistically significant for differentiating the extent of myocardial injury. ROC (receiver operating characteristic) curve analysis for the differentiation of unsalvageable infarction and salvageable myocardium demonstrated a significantly higher AUC (area under the curve) (0.91 [95% CI, 0.86-0.96], p < 0.0001) for horizontal fraction than other texture features (p < 0.05). LVAR (left ventricular adverse remodeling) was predicted by those selected features. The differences in qualitative and quantitative baseline parameters and horizontal fractions were significant between the patients with and without LVAR. LGE (late gadolinium enhancement) and horizontal fraction features of infarcted myocardium in acute STEMI were the only two parameters selected in forming the optimal overall multivariable model for LVAR at 6 months. CONCLUSIONS: Radiomic analysis of ECV could discriminate reversible from irreversible myocardial injury after STEMI. LGE as well as radiomics TA (texture analysis) of ECV may provide an alternative to predict LVAR and functional recovery. KEY POINTS: • ECV quantification was able to differentiate between infarcted myocardium and non-infarcted myocardium. • Radiomics analysis of ECV could discriminate reversible from irreversible myocardial injury. • Radiomics TA analysis shows a promising similarity with LGE findings which could aid the prognosis of myocardial infarction patients.

Utilization of MR imaging in myodural bridge complex with relevant muscles: current status and future perspectives.

The aim of this study is to review and discuss the literature on the utilization of magnetic resonance imaging (MRI) in investigating the structure and feasible function of the myodural bridge complex (MDBC) with relevant muscles, which will be useful to understand the function of the MDB. The myodural bridge (MDB) is a soft tissue connective bridge that provides a fascial continuity between the musculature/ligament and cervical spinal dura mater (SDM) in the suboccipital areas. All of these involved structures are referred to as the MDBC. It would transfer tensile forces effectively from involved suboccipital muscles/ligament to SDM during head movement. Despite present achievements, its anatomic and functional role is still unclear. MRI enables not only in vivo visualization of ligaments, musculature and spinal dura with conventional T1W, T2W and PDW imaging, but also functional evaluation of MDBC with relevant muscles, such as muscles' fatty infiltration, cross-sectional area changes and injuries. Though some functional MRI techniques have not been used for the MDBC with relevant muscles now, these techniques have great potential to better understand function of MDBC including its suspected clinical role. MRI is likely the most powerful tool to study MDBC and relevant muscles with only limited exploration so far.

The feasibility of differentiating colorectal cancer from normal and inflammatory thickening colon wall using CT texture analysis.

To investigate the diagnostic value of texture analysis (TA) for differentiating between colorectal cancer (CRC), colonic lesions caused by inflammatory bowel disease (IBD), and normal thickened colon wall (NTC) on computed tomography (CT) and assess which scanning phase has the highest differential diagnostic value. In all, 107 patients with CRC, 113 IBD patients with colonic lesions, and 96 participants with NTC were retrospectively enrolled. All subjects underwent multiphase CT examination, including pre-contrast phase (PCP), arterial phase (AP), and portal venous phase (PVP) scans. Based on these images, classification by TA and visual classification by radiologists were performed to discriminate among the three tissue types. The performance of TA and visual classification was compared. Precise TA classification results (error, 2.03-12.48%) were acquired by nonlinear discriminant analysis for CRC, IBD and NTC, regardless of phase or feature selection. PVP images showed a better ability to discriminate the three tissues by comprising the three scanning phases. TA showed significantly better performance in discriminating CRC, IBD and NTC than visual classification for residents, but there was no significant difference in classification between TA and experienced radiologists. TA could provide useful quantitative information for the differentiation of CRC, IBD and NTC on CT, particularly in PVP images.

Detecting sub-voxel microvasculature with USPIO-enhanced susceptibility-weighted MRI at 7 T.

BACKGROUND: Susceptibility weighted imaging (SWI) combines phase with magnitude information to better image sub-voxel veins. Recently, it has been extended to image very small sub-voxel arteries and veins by injecting intravenously the ultra-small superparamagnetic iron oxide, Ferumoxytol. OBJECTIVE: To determine practical experimental imaging parameters for sub-voxel cerebral vessels at 7 T. METHODS: Six Wistar-Kyoto rats aged 7-13 weeks were imaged. For a given spatial resolution, SWI was acquired pre- and post- Ferumoxytol with doses of 2, 4, 6 and 8 mg/kg and echo times (TEs) of 5, 10 and 15 ms at each dose. The spatial resolutions of 62.5 × 125 × 250 µm3 (acquisition time of 7.5 min) and 62.5 × 62.5 × 125 µm3 (30 min) were used. Both SWI and quantitative susceptibility mapping (QSM) data were analyzed. Contrast-to-noise ratio (CNR) was measured and used to determine the optimal practical imaging parameters for detection of small cortical penetrating arteries. RESULTS: For a given spatial resolution with an aspect ratio (frequency: phase: slice) of 2:4:8 relative to the vessel size, we found the TE-dose index (TE x dose) must be at least 40 ms·mg/kg for both SWI and QSM to reveal the most vessels. The higher the TE-dose index, the better the image quality for both SWI and QSM up to 60 ms·mg/kg. CONCLUSIONS: There is an optimal TE-dose index for improved visualization of sub-voxel vessels. Choosing the smallest TE and the largest allowed dose made it possible to run the sequence efficiently. In practice, the aspect ratio of 2:4:8 and the TE-dose index ranging from 40 to 60 ms·mg/kg provided the optimal and most practical solution.