Regional myocardial strain by cardiac magnetic resonance feature tracking for detection of scar in ischemic heart disease

BackgroundAlthough cardiac magnetic resonance (CMR) can accurately quantify global left ventricular strain using feature tracking (FT), it has been suggested that FT cannot reliably quantify regional strain. We aimed to determine whether abnormalities in regional strain measured using FT can be detected within areas of myocardial scar and to determine the extent to which the regional strain measurement is impacted by LV ejection fraction (EF).MethodsWe retrospectively studied 96 patients (46 with LVEF ≤ 40%, 50 with LVEF > 40%) with coronary artery disease and a late gadolinium enhancement (LGE) pattern consistent with myocardial infarction, who underwent CMR imaging (1.5T). Regional peak systolic longitudinal and circumferential strains (RLS, RCS) were measured within LGE and non-LGE areas. Linear regression analysis was performed for strain in both areas against LVEF to determine whether the relationship between strain and LGE holds across the LV function spectrum. Receiver-operating curve (ROC) analysis was performed in 33 patients (derivation cohort) to optimize strain cutoff, which was tested in the remaining 63 patients (validation cohort) for its ability to differentiate LGE from non-LGE areas.ResultsBoth RLS and RCS magnitudes were reduced in LGE areas: RLS = −10.4 ± 6.2% versus −21.0 ± 8.5% (p < 0.001); RCS = −10.4 ± 6.0% versus −18.9 ± 8.6%, respectively (p < 0.001), but there was considerable overlap between LGE and non-LGE areas. Linear regression revealed that it was partially driven by the natural dependence between strain and EF, suggesting that EF-corrected strain cutoff is needed to detect LGE. ROC analysis showed the ability of both RLS and RCS to differentiate LGE from non-LGE areas: area under curve 0.95 and 0.89, respectively. In the validation cohort, optimal cutoffs of RLS/EF = 0.36 and RCS/EF = 0.37 yielded sensitivity, specificity and accuracy 0.74–0.78.ConclusionAbnormalities in RLS and RCS within areas of myocardial scar can be detected using CMR-FT; however, LVEF must be accounted for.     

3D late gadolinium enhanced cardiovascular MR with CENTRA-PLUS profile/view ordering: Feasibility of right ventricular myocardial damage assessment using a swine animal model

AimsTo develop a high-resolution, 3D late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (MRI) technique for improved assessment of myocardial scars, and evaluate its performance against 2D breath-held (BH) LGE MRI using a surgically implanted animal scar model in the right ventricle (RV).Methods and resultsA k-space segmented 3D LGE acquisition using CENTRA-PLUS (Contrast ENhanced Timing Robust Acquisition with Preparation of LongitUdinal Signal; or CP) ordering is proposed. 8 pigs were surgically prepared with cardiac patch implantation in the RV, followed in 60 days by 1.5 T MRI. LGE with Phase-Sensitive Inversion Recovery (PSIR) were performed as follows: 1) 2DBH using pneumatic control, and 2) navigator-gated, 3D free-breathing (3DFB)-CP-LGE with slice-tracking. The animal heart was excised immediately after cardiac MR for scar volume quantification. RV scar volumes were also delineated from the 2DBH and 3DFB-CP-LGE images for comparison against the surgical standard. Apparent scar/normal tissue signal-to-noise ratio (aSNR) and contrast-to-noise ratio (aCNR) were also calculated.3DFB-CP-LGE technique was successfully performed in all animals. No difference in aCNR was noted, but aSNR was significantly higher using the 3D technique (p < 0.05). Against the surgical reference volume, the 3DFB-CP-LGE-derived delineation yielded significantly less volume quantification error compared to 2DBH-derived volumes (15 ± 10% vs 55 ± 33%; p < 0.05).ConclusionCompared to conventional 2DBH-LGE, 3DFB-LGE acquisition using CENTRA-PLUS provided superior scar volume quantification and improved aSNR.     

Three-dimensional turbo-spin-echo amide proton transfer-weighted and intravoxel incoherent motion MR imaging for type I endometrial carcinoma: Correlation with Ki-67 proliferation status

BackgroundTo evaluate 3-dimensional amide proton transfer weighted (APTw) imaging for type I endometrial carcinoma (EC), and investigate correlations of Ki-67 labelling index with APTw and intravoxel incoherent motion (IVIM) imaging.Methods54 consecutive patients suspected of endometrial lesions underwent pelvic APTw and IVIM imaging on a 3 T MR scanner. APTw values and IVIM-derived parameters (Dt, D*, f) were independently measured by two radiologists on 22 postoperative pathological confirmed of type I EC lesions. Results were compared between histological grades and Ki-67 proliferation groups. ROC analysis was performed. Pearson's correlation analysis was performed for APTw values and IVIM-derived parameters with Ki-67 labeling index.ResultsAPTw values and Dt, D*, f of all type I EC were 2.9 ± 0.1%, 0.677 ± 0.027 × 10⁻³ mm²/s, 31.801 ± 11.492 × 10⁻³ mm²/s, 0.179 ± 0.050 with inter-observer ICC 0.996, 0.850, 0.956, 0.995, respectively. APTw values of Ki-67 low-proliferation group (<30%, n = 8) were 2.5 ± 0.2%, significantly lower than the high-proliferation group (>30%, n = 14) with APTw values of 3.1 ± 0.1% (p = 0.016). Area under the curve was 0.768. APTw values of type I EC were moderately positively correlated with Ki-67 labelling index (r = 0.583, p = 0.004). There was no significant difference of Dt (p = 0.843), D* (p = 0.262), f (p = 0.553) between the two groups. No correlation was found between IVIM-derived parameters and Ki-67 labelling index (Dt, p = 0.717; D* p = 0.151; f, p = 0.153).Conclusion3D TSE APTw imaging is a feasible approach for detecting type I EC. Ki-67 labeling index positively moderately correlates with APTw not with IVIM.     

Tagged cine magnetic resonance imaging to quantify regional mechanical changes after acute myocardial infarction

PurposeThe conventional volumetric approaches of measuring cardiac function are load-dependent, and are not able to discriminate functional changes in the infarct, transition and remote myocardium. We examined phase-dependent regional mechanical changes in the infarct, transition and remote regions after acute myocardial infarction (MI) in a preclinical mouse model using cardiovascular magnetic resonance imaging (CMR).MethodsWe induced acute MI in six mice with left anterior descending coronary artery ligation. We then examined cardiac (infarct, transition and remote-zone) morphology and function utilizing 9.4 T high field CMR before and 2 weeks after the induction of acute MI. Myocardial scar tissue was evaluated by using CMR with late gadolinium enhancement (LGE). After determining global function through volumetric analysis, regional wall motion was evaluated by measuring wall thickening and radial velocities. Strain rate imaging was performed to assess circumferential contraction and relaxation at the myocardium, endocardium, and epicardium.ResultsThere was abnormal LGE in the anterior walls after acute MI suggesting a successful MI procedure. The transition zone consisted of a mixed signal intensity, while the remote zone contained viable myocardium. As expected, the infarct zone had demonstrated severely decreased myocardial velocities and strain rates, suggesting reduced contraction and relaxation function. Compared to pre-infarct baseline, systolic and diastolic velocities (v_S and v_D) were significantly reduced at the transition zone (v_S: −1.86 ± 0.16 cm/s vs −0.68 ± 0.13 cm/s, P < 0.001; v_D: 1.86 ± 0.17 cm/s vs 0.53 ± 0.06 cm/s, P < 0.001) and remote zone (v_S: −1.86 ± 0.16 cm/s vs −0.65 ± 0.12 cm/s, P < 0.001; v_D: 1.86 ± 0.16 cm/s vs 0.51 ± 0.04 cm/s, P < 0.001). Myocardial peak systolic and diastolic strain rates (SR_S and SR_D) were significantly lower in the transition zone (SR_S: −4.2 ± 0.3 s⁻¹ vs −1.3 ± 0.2 s⁻¹, P < 0.001; SR_D: 3.9 ± 0.3 s⁻¹ vs 1.3 ± 0.2 s⁻¹, P < 0.001) and remote zone (SR_S: −3.8 ± 0.3 s⁻¹ vs −1.4 ± 0.3 s⁻¹, P < 0.001; SR_D: 3.5 ± 0.2 s⁻¹ vs 1.5 ± 0.4 s⁻¹, P = 0.006). Endocardial and epicardial SR_S and SR_D were similarly reduced in the transition and remote zones compared to baseline.ConclusionsThis study, for the first time, utilized state-of-the art high-field CMR algorithms in a preclinical mouse model for a comprehensive and controlled evaluation of the regional mechanical changes in the transition and remote zones, after acute MI. Our data demonstrate that CMR can quantitatively monitor dynamic post-MI remodeling in the transition and remote zones, thereby serving as a gold standard tool for therapeutic surveillance.     

Diffusivity mapping of the ovaries: Variability of apparent diffusion and kurtosis variables over the menstrual cycle and influence of oral contraceptives

PurposeWe aimed to investigate whether quantitative diffusivity variables of healthy ovaries vary during the menstrual cycle and to evaluate alterations in women using oral contraceptives (OC).MethodsThis prospective study (S-339/2016) included 30 healthy female volunteers, with (n = 15) and without (n = 15) intake of OC between 07/2017 and 09/2019. Participants underwent 3T diffusion-weighted MRI (b-values 0–2000 s/mm²) three times during a menstrual cycle (T1 = day 1–5; T2 = day 7–12; T3 = day 19–24). Both ovaries were manually three-dimensionally segmented on b = 1500 s/mm²; apparent diffusion coefficient (ADC) calculation and kurtosis fitting (D_app, K_app) were performed. Differences in ADC, D_app and K_app between time points and groups were compared using repeated measures ANOVA and t-test after Shapiro-Wilk and Brown-Forsythe test for normality and equal variance.ResultsIn women with a natural menstrual cycle, ADC and kurtosis variables showed significant changes in ovaries with the dominant follicle between T1 vs T2 and T1 vs T3, whilst no differences were observed between T2 vs T3: ADC ± SD for T1 1.524 ± 0.160, T2 1.737 ± 0.160, and T3 1.747 ± 0.241 μm²/ms (p = 0.01 T2 vs T1; p = 1.0 T2 vs T3, p = 0.003 T3 vs T1); D_app ± SD for T1 2.018 ± 0.140, T2 2.272 ± 0.189, and T3 2.230 ± 0.256 μm²/ms (p = 0.003 T2 vs T1, p = 1.0 T2 vs T3, p = 0.02 T3 vs T1); K_app ± SD for T1 0.614 ± 0.0339, T2 0.546 ± 0.0637, and T3 0.529 ± 0.0567 (p < 0.001 T2 vs T1, p = 0.86 T2 vs T3, p < 0.001 T3 vs T1). No significant differences were found in the contralateral ovaries or in females taking OC.ConclusionPhysiological cycle-dependent changes in quantitative diffusivity variables of ovaries should be considered especially when interpreting radiomics analyses in reproductive women.     

Cardiac magnetic resonance tissue tracking in right ventricle: Feasibility and normal values

PurposeTo investigate right ventricular (RV) strain in patients without identified cardiac pathology using cardiac magnetic resonance tissue tracking (CMR TT).MethodsA total of 50 consecutive patients with no identified cardiac pathology were analyzed. RV longitudinal and circumferential strain was assessed by CMR TT. The age range was 4–81 years with a median of 32 years (interquartile range, 15 to 56 years).ResultsAnalysis time per patient was < 5 min. The peak longitudinal strain (E_ll) was − 22.11 ± 3.51%. The peak circumferential strains (E_cc) for global, basal, mid-cavity and apical segments were as follows: − 11.69 ± 2.25%, − 11.00 ± 2.45%, − 11.17 ± 3.36%, − 12.90 ± 3.34%. There were significant gender differences in peak E_cc at the base (P = 0.04) and the mid-cavity (P = 0.03) with greater deformation in females than in males. On Bland-Altman analysis, peak E_ll (mean bias, 0.22 ± 1.67; 95% CI − 3.05 to 3.49) and mid-cavity E_cc (mean bias, 0.036 ± 1.75; 95% CI, − 3.39 to 3.47) had the best intra-observer agreement and inter-observer agreement, respectively.ConclusionsRV longitudinal and circumferential strains can be quickly assessed with good intra-observer and inter-observer variability using TT.     

Self-navigated 3D whole-heart MRA for non-enhanced surveillance of thoracic aortic dilation: A comparison to CTA

PurposeTo prospectively compare image quality and reliability of a non-contrast, self-navigated 3D whole-heart magnetic resonance angiography (MRA) sequence with contrast-enhanced computed tomography angiography (CTA) for sizing of thoracic aortic aneurysm (TAA).MethodsSelf-navigated 3D whole-heart 1.5 T MRA was performed in 20 patients (aged 67 ± 9 years, 75% male) for sizing of TAA; a subgroup of 18 (90%) patients underwent additional contrast-enhanced CTA on the same day. Subjective image quality was scored according to a 4-point Likert scale and ratings between observers were compared by Cohen's Kappa statistics. For MRA, subjective motion blurring and signal inhomogeneity was rated according to a 3-point scale, respectively. Objective signal inhomogeneity of MRA was quantified as standard deviation of the voxel intensities in a circular region of interest (ROI) placed in the ascending aorta divided by their mean value. Continuous MRA and CTA measurements were analyzed with regression and Bland-Altman analysis.ResultsOverall subjective image quality as rated by two observers was 1 [interquartile range (IQR) 1–2] for self-navigated MRA and 1.5 [IQR 1–2] for CTA (p = 0.717). For MRA, perfect inter-observer agreement was found regarding presence of artefacts and subjective image sharpness (κ = 1). Subjective signal inhomogeneity agreed moderately between the observers (κ = 0.58, p = 0.007), however, it correlated strongly with objectively quantified inhomogeneity of the blood pool signal (r = 0.78, p < 0.0001). Maximum diameters of TAA as measured by self-navigated MRA and CTA showed very strong correlation (r = 0.99, p < 0.0001) without significant inter-method bias (bias −0.03 mm, lower and upper limit of agreement −0.74 and 0.68 mm, p = 0.749). Inter-observer correlation of aortic aneurysm as measured by MRA was very strong (r = 0.96) without significant bias (p = 0.695).ConclusionSelf-navigated 3D whole-heart MRA enables reliable contrast- and radiation free aortic dilation surveillance without significant difference to standardized CTA while providing predictable acquisition time and offering excellent image quality.     

Improved nerve conspicuity with water-weighting and denoising in two-point Dixon magnetic resonance neurography

BackgroundT₂-weighted, two-point Dixon fast-spin-echo (FSE) is an effective technique for magnetic resonance neurography (MRN) that can provide quantitative assessment of muscle denervation. Low signal-to-noise ratio and inadequate fat suppression, however, can impede accurate interpretation.PurposeTo quantify effects of principal component analysis (PCA) denoising on tissue signal intensities and fat fraction (FF) and to determine qualitative image quality improvements from both denoising and water-weighting (WW) algorithms to improve nerve conspicuity and fat suppression.Study typeProspective.SubjectsTwenty-one subjects undergoing MR neurography evaluation (11/10 male/female, mean age = 46.3±13.7 years) with 60 image volumes. Twelve subjects (23 image volumes) were determined to have muscle denervation based on diffusely elevated T₂ signal intensity.Field strength/sequence3 T, 2D, two-point Dixon FSE.AssessmentQualitative assessment included overall image quality, nerve conspicuity, fat suppression, pulsation and ringing artifacts by 3 radiologists separately on a three-point scale (1 = poor, 2 = average, 3 = excellent). Quantitative measurements for FF and signal intensity relative to normal muscle were made for nerve, abnormal muscle and subcutaneous fat.Statistical testsLinear and ordinal regression models were used for quantitative and qualitative comparisons, respectively; 95% confidence intervals (CIs) and p-values for pairwise comparisons were adjusted using the Holm-Bonferroni method. Inter-rater agreement was assessed using Gwet's agreement coefficient (AC₂).ResultsSimulations showed PCA-denoising reduced FF error from 2.0% to 1.0%, and from 7.6% to 3.1% at noise levels of 10% and 30%, respectively. In human subjects, PCA-denoising did not change signal levels and FF quantitatively. WW decreased fat signal significantly (−83.6%, p < 0.001). Nerve conspicuity was improved by WW (odds ratio, OR = 5.8, p < 0.001). Fat suppression was improved by both PCA (OR = 3.6, p < 0.001) and WW (OR = 2.2, p < 0.001). Overall image quality was improved by PCA + WW (OR = 1.7, p = 0.04).ConclusionsWW and PCA-denoising improved nerve conspicuity and fat suppression in MR neurography. Denoising can potentially provide improved accuracy of FF maps for assessing fat-infiltrated muscle.     

Cardiac MRI for the prognostication of heart failure with preserved ejection fraction: A systematic review and meta-analysis

BackgroundCardiac magnetic resonance imaging (MRI) is emerging as an important imaging tool in the assessment of heart failure with preserved ejection fraction (HFpEF). This systematic review and meta-analysis aim to synthesise and consolidate the current literature on cardiac MRI for prognostication of HFpEF.Methods designSystematic review and meta-analysis. Data sources: Scopus (PubMed and Embase) for studies published between 2008 and 2019. Eligibility criteria for study selection were studies that evaluated the prognostic role of cardiac MRI in HFpEF. Random effects meta-analyses of the reported hazard ratios (HR) for clinical outcomes was performed.ResultsInitial screening identified 97 studies. From these, only nine (9%) studies met all the criteria. The main cardiac MRI methods that demonstrated association to prognosis in HFpEF included late gadolinium enhancement (LGE) assessment of scar (n = 3), tissue characterisation with T1-mapping (n = 4), myocardial ischaemia (n = 1) and right ventricular dysfunction (RVSD) (n = 1). The pooled HR for all 9 studies was 1.52 (95% CI 1.05–1.99, P < 0.01). Sub-evaluation by cardiac MRI methods revealed varying HRs: LGE (net n = 402, HR = 1.6, 95% CI 0.42–2.78, P = 0.008); T1-mapping (n = 1623, HR = 1.25, 95% CI 0.891–1.60, P < 0.001); myocardial ischaemia or RVSD (n = 325, HR = 3.19, 95% CI 0.30–6.08, P = 0.03).ConclusionThis meta-analysis demonstrates that multiparametric cardiac MRI has value in prognostication of patients with HFpEF. HFpEF patients with a detectable scar on LGE, fibrosis on T1-mapping, myocardial ischaemia or RVSD appear to have a worse prognosis.PROSPERO registration numberCRD42020187228.     

Histogram parameters derived from T1 and T2 weighted images correlate with tumor infiltrating lymphocytes and tumor-stroma ratio in head and neck squamous cell cancer

PurposeThe present study used histogram analysis values derived from T1- and T2- weighted (w) images to elucidate possible associations with Tumor-infiltrating lymphocytes (TIL) and Vimentin expression in head and neck squamous cell cancer (HNSCC).Materials and methodsOverall, 28 patients (n = 8 female patient, 28.6%) with primary HNSCC of different localizations were involved in the study. Magnetic resonance imaging (MRI) was obtained on a 3 T MRI. The images were analyzed with a whole lesion measurement using a histogram approach. TIL- and vimentin-expression was calculated on biopsy samples before any form of treatment.ResultsSeveral T1-derived parameters correlated with the expression of TIL within the stroma compartment: mean (r = 0.42, p = 0.025), p10 (r = 0.50, p = 0.007), p25 (r = 0.42, p = 0.025), median (r = 0.39, p = 0.036), and mode (r = 0.39, p = 0.04). No T2-derived parameter correlated with the TIL within the stroma compartment. Several T2-derived parameters correlated with the expression of TIL within the tumor compartment: mean (r = −0.52, p = 0.004), max (r = −0.43, p = 0.02), p10 (r = −0.38, p = 0.04), p25 (r = −0.53, p = 0.004), p75 (r = −0.52, p = 0.004), p90 (r = −0.48, p = 0.009), median (r = −0.52, p = 0.004), mode (r = −0.40, p = 0.03). Kurtosis derived from T2w images had significant higher values in tumor-rich tumors, compared to stroma-rich tumors, (mean 5.5 ± 0.5 versus 4.2 ± 1.2, p = 0.028).ConclusionsHistogram analysis parameters derived from T1w and T2w images might be able to reflect tumor compartments and TIL expression in HNSCC.     

Oxygen non-stoichiometry and electrical conductivity of Pr2−xSrxNiO4±δ with x = 0–0.5

Oxygen non-stoichiometry and electrical conductivity of the Pr_2−xSr_xNiO_4±δ series with x = 0.0–0.5 were investigated in Ar/O₂ (pO₂ = 2.5 to 21 000 Pa) within a temperature range of 20–1000 °C. The equilibrium values of oxygen non-stoichiometry and electrical conductivity of these nickelates were determined as functions of temperature and oxygen partial pressure (pO₂). The nickelates with x = 0–0.5 appear to be p-type semiconductors in the investigated temperature and pO₂ ranges. The nickelates with x = 0.3–0.5 show very feebly marked pO₂ dependencies of the conductivity. Pr_1.7Sr_0.3NiO_4±δ shows the anomalies of the conductivity versus oxygen partial pressure which can be related to the orthorhombic–tetragonal crystal structure transformations. The conductivity of the Pr_2−xSr_xNiO_4±δ samples correlates with the average oxidation state of the nickel cations. The samples with x = 0.5 have the highest nickel oxidation state (≈ 2.5+), the highest [Ni³⁺]/[Ni²⁺] ratio close to 1 and show the highest conductivity (≈ 120 S/cm) in the whole pO₂ and temperature ranges investigated.     

A deep-learning semantic segmentation approach to fully automated MRI-based left-ventricular deformation analysis in cardiotoxicity

Left-ventricular (LV) strain measurements with the Displacement Encoding with Stimulated Echoes (DENSE) MRI sequence provide accurate estimates of cardiotoxicity damage related to breast cancer chemotherapy. This study investigated an automated LV chamber quantification tool via segmentation with a supervised deep convolutional neural network (DCNN) before strain analysis with DENSE images. Segmentation for chamber quantification analysis was conducted with a custom DeepLabV3+ DCNN with ResNet-50 backbone on 42 female breast cancer datasets (22 training-sets, eight validation-sets and 12 independent test-sets). Parameters such as LV end-diastolic diameter (LVEDD) and ejection fraction (LVEF) were quantified, and myocardial strains analyzed with the Radial Point Interpolation Method (RPIM). Myocardial classification was validated against ground-truth with sensitivity-specificity analysis, the metrics of Dice, average perpendicular distance (APD) and Hausdorff-distance. Following segmentation, validation was conducted with the Cronbach's Alpha (C-Alpha) intraclass correlation coefficient between LV chamber quantification results with DENSE and Steady State Free Precession (SSFP) acquisitions and a vendor tool-based method to segment the DENSE data, and similarly for myocardial strain analysis in the chambers. The results of myocardial classification from segmentation of the DENSE data were accuracy = 97%, Dice = 0.89 and APD = 2.4 mm in the test-set. The C-Alpha correlations from comparing chamber quantification results between the segmented DENSE and SSFP data and vendor tool-based method were 0.97 for LVEF (56 ± 7% vs 55 ± 7% vs 55 ± 6%, p = 0.6) and 0.77 for LVEDD (4.6 ± 0.4 cm vs 4.5 ± 0.3 cm vs 4.5 ± 0.3 cm, p = 0.8). The validation metrics against ground-truth and equivalent parameters obtained from the SSFP segmentation and vendor tool-based comparisons show that the DCNN approach is applicable for automated LV chamber quantification and subsequent strain analysis in cardiotoxicity.     

Transport properties of the Pr2−xSrxNiO4±δ ceramics with x = 0.3 and 0.6

As potential cathode materials Pr_2−xSr_xNiO_4±δ compositions with x = 0.3 and 0.6 were prepared at 1300 °C in air and their electrical conductivity and oxygen non-stoichiometry were investigated in the temperature range 20–1000 °C and oxygen partial pressure (pO₂) 1–21,000 Pa. Sr-doping allows partially to stabilize the Pr₂NiO_4±δ structure, but some phase transitions were observed in spite of that. The electrical conductivity and the oxygen mobility of the Pr- and La-containing ceramic nickelates with K₂NiF₄- type structure are 10–15% higher for Pr_2−xSr_xNiO_4−δ compounds at the same temperature and oxygen partial pressure.     

Intravoxel incoherent motion magnetic resonance imaging for breast cancer: A comparison with molecular subtypes and histological grades

PurposeThe purpose of this paper is to investigate whether the IVIM parameters (D, D *, f) helps to determine the molecular subtypes and histological grades of breast cancer.MethodsFifty-one patients with breast cancer were included in the study. All subjects were examined by 3 T Magnetic Resonance Imaging (MRI). Diffusion-weighted imaging (DWI) was undertaken with 16 b-values. IVIM parameters [D (true diffusion coefficient), D* (pseudo-diffusion coefficient), f (perfusion fraction)] were calculated. Histopathological reports were reviewed to histological grade, histological type, and immunohistochemistry. IVIM parameters of tumors with different histological grades and molecular subtypes were compared.ResultsD* and f were significantly different between molecular subtypes (p = 0.019, p = 0.03 respectively). D* and f were higher in the HER-2 group and lower in Triple negative (−) group (D*:36.8 × 10⁻³ ± 5.3 × 10⁻³ mm²/s, f:29.5%, D*:29.8 × 10⁻³ ± 5.6 × 10⁻³ mm²/s, f:21.5% respectively). There was a significant difference in D* and f between HER-2 and Triple (−) subgroups (p = 0,028, p = 0.024, respectively). D* was also significantly different between the HER-2 group and the Luminal group (p = 0,041). While histological grades increase, D and f values tend to decrease, and D* tends to increase. While the Ki-67 index increases, D* and f values tend to increase, and D tend to decrease.ConclusionD* and f values measured with IVIM imaging were useful for assessing breast cancer molecular subtyping. IVIM imaging may be an alternative to breast biopsy for sub-typing of breast cancer with further research.     

Synthetic T2-weighted images of the lumbar spine derived from an accelerated T2 mapping sequence: Comparison to conventional T2w turbo spin echo

ObjectivesTo evaluate the diagnostic usefulness of synthetic T₂-weighted images of the lumbar spine derived from ten-fold undersampled k-space data using GRAPPATINI, a combination of a model-based approach for rapid T₂ and M₀ quantification (MARTINI) extended by generalized autocalibrating partial parallel acquistion (GRAPPA).Materials and methodsOverall, 58 individuals (26 female, mean age 23.3 ± 8.1 years) were examined at 3 Tesla with sagittal and axial T₂w turbo spin echo (TSE) sequences compared to synthetic T₂₋weighted contrasts derived at identical effective echo times and spatial resolutions. Two blinded readers graded disk degeneration and evaluated the lumbar intervertebral disks for present herniation or annular tear. One reader reassessed all studies after four weeks. Weighted kappa statistics were calculated to assess inter-rater and intra-rater agreement. Also, all studies were segmented manually by one reader to compute contrast ratios (CR) and contrast-to-noise ratios (CNR) of the nucleus pulposus and the annulus fibrosus.ResultsOverall, the CR_T2w was 4.45 ± 1.80 and CR_T2synth was 4.71 ± 2.14. Both correlated (rsp = 0.768;p < 0.001) and differed (0.26 ± 1.38;p = 0.002) significantly. The CNR_T2w was 1.73 ± 0.52 and CNR_T2synth was 1.63 ± 0.50. Both correlated (rsp = 0.875;p < 0.001) and differed (−0.10 ± 0.25;p < 0.001) significantly. The inter-rater agreement was substantial to almost perfect (κ = 0.808–0.925) with the intra-rater agreement also substantial to almost perfect (κ = 0.862–0.963). The area under the curve of the receiver operating characteristics assessing disk herniation or annular tear ranged from 0.787 to 0.892.ConclusionsThis study concludes that synthetic images derived by GRAPPATINI can be used for clinical routine assessment with inter-rater and intra-rater agreements comparable to conventional T₂w TSE.     

Importance of through-plane heart motion correction for the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging

PurposeTo elucidate the influence of through-plane heart motion on the assessment of aortic regurgitation (AR) severity using phase contrast magnetic resonance imaging (PC-MRI).ApproachA patient cohort with chronic AR (n = 34) was examined with PC-MRI. The regurgitant volume (RVol) and fraction (RFrac) were extracted from the PC-MRI data before and after through-plane heart motion correction and was then used for assessment of AR severity.ResultsThe flow volume errors were strongly correlated to aortic diameter (R = 0.80, p < 0.001) with median (IQR 25%;75%): 16 (14; 17) ml for diameter>40mm, compared with 9 (7; 10) ml for normal aortic size (p < 0.001). RVol and RFrac were underestimated (uncorrected:64 ± 37 ml and 39 ± 17%; corrected:76 ± 37 ml and 44 ± 15%; p < 0.001) and ~ 20% of the patients received lower severity grade without correction.ConclusionThrough-plane heart motion introduces relevant flow volume errors, especially in patients with aortic dilatation that may result in underestimation of the severity grade in patients with chronic AR.     

Fat-saturated dark-blood cardiac T2 mapping in a single breath-hold

PurposeConventional cardiac T2 mapping suffers from the partial-voluming effect in the endocardium and epicardium due to the co-presence of intra-cavity blood and epicardial fat. The aim of the study is to develop a novel single-breath-hold Fat-Saturated Dark-Blood (FSDB) cardiac T2-mapping technique to mitigate the partial-voluming and improve T2 accuracy.MethodsThe proposed FSDB T2-mapping technique combines T2-prepared bSSFP, a novel use of double inversion-recovery with heart-rate-adaptive TI, and spectrally-selective fat saturation to mitigate partial-voluming from both the blood and fat. FSDB T2 mapping was compared to conventional T2 mapping via simulations, phantom imaging, healthy-subject imaging (n = 8), and patient imaging (n = 7). In the healthy subjects, a high-resolution coplanar anatomical imaging was performed to provide a gold standard for segmentation of endocardium and epicardium. T2 maps were registered to the gold standard image to evaluate any inter-layer T2 difference, which is a surrogate for partial-voluming.ResultsSimulations and phantom imaging showed that FSDB T2 mapping was accurate in a range of heartrates, off-resonance, and T2 values, and blood/fat reasonably nulled in a range of heartrates. In healthy subjects, FSDB T2 mapping showed similar T2 values over different myocardial layers in all 3 short-axis slices (e.g. basal epicardial/mid-wall/endocardial T2 = 42 ± 2 ms/41 ± 1 ms/42 ± 1 ms), whereas conventional T2 mapping showed considerably increased T2 in the endocardium and epicardium (e.g. basal epicardial/mid-wall/endocardial T2 = 48 ± 3 ms/43 ± 1 ms/49 ± 3 ms). The homogeneous T2 in the FSDB T2 mapping increased the apparent LV-wall thickness by 25–41% compared with the conventional method.ConclusionsThe proposed technique improves accuracy of myocardial T2 mapping against partial-voluming associated with both fat and blood, facilitating a multi-layer T2 evaluation of the myocardium. This technique may improve utility of cardiac T2 mapping in diseases affecting the endocardium and epicardium, and in patients with a small heart.     

Clinical evaluation of subtracted pointwise encoding time reduction with radial acquisition-based magnetic resonance angiography compared to 3D time-of-flight magnetic resonance angiography for improved flow dephasing at 3 Tesla

ObjectiveFlow dephasing artifacts within intracranial internal carotid artery (ICA) have been problematic for 3D time-of-flight magnetic resonance angiography (3D-TOF-MRA). This study aimed to evaluate pointwise encoding time reduction with radial acquisition subtraction-based MR angiography (PETRA-MRA) for decreasing flow dephasing artifacts compared to 3D-TOF-MRA in intracranial segments of ICA at 3 T.MethodsSixty healthy participants and seven patients with intracranial ICA aneurysms were enrolled to undergo 3D-TOF-MRA and PETRA-MRA. Two radiologists each evaluated the image quality of healthy participants using a 4-point scale (1: the best and 4: the worst). Quantitative analysis of the extent of homogeneity in signal intensity within the ICA and intracranial aneurysms was conducted using a parameter d: the higher the d value, the greater the signal homogeneity. Wilcoxon signed rank test, Chi-square test and the weighted kappa (κ) statistic were used for statistical analyses.ResultsThe image quality of PETRA-MRA with an overall score of 1.35 ± 0.53 was significantly better than that obtained with 3D-TOF-MRA, with an overall score of 3.50 ± 0.62 (Z = -9.56, p < 0.001). The parameter d of PETRA-MRA was higher than that of 3D-TOF-MRA for both 60 healthy participants (0.97 ± 0.05, 0.87 ± 0.11; z = -13.21, p < 0.001) and 7 patients with intracranial aneurysms (0.81 ± 0.18, 0.74 ± 0.16; z = -2.37, p = 0.018).ConclusionCompared with conventional 3D-TOF-MRA, PETRA-MRA remarkably improved the image quality with reduced flow dephasing artifacts in segments of intracranial ICA.     

Validation of non-contrast multiple overlapping thin-slab 4D-flow cardiac magnetic resonance imaging

BackgroundCardiac magnetic resonance (CMR) flow quantification is typically performed using 2D phase-contrast (PC) imaging of a plane perpendicular to flow. 3D-PC imaging (4D-flow) allows offline quantification anywhere in a thick slab, but is often limited by suboptimal signal, potentially alleviated by contrast enhancement. We developed a non-contrast 4D-flow sequence, which acquires multiple overlapping thin slabs (MOTS) to minimize signal loss, and hypothesized that it could improve image quality, diagnostic accuracy, and aortic flow measurements compared to non-contrast single-slab approach.MethodsWe prospectively studied 20 patients referred for transesophageal echocardiography (TEE), who underwent CMR (GE, 3 T). 2D-PC images of the aortic valve and three 4D-flow datasets covering the heart were acquired, including single-slab, pre- and post-contrast, and non-contrast MOTS. Each 4D-flow dataset was interpreted blindly for ≥moderate valve disease and compared to TEE. Flow visualization through each valve was scored (0 to 4), and aortic-valve flow measured on each 4D-flow dataset and compared to 2D-PC reference.ResultsDiagnostic quality visualization was achieved with the pre- and post-contrast 4D-flow acquisitions in 25% and 100% valves, respectively (scores 0.9 ± 1.1 and 3.8 ± 0.5), and in 58% with the non-contrast MOTS (1.6 ± 1.1). Accuracy of detection of valve disease was 75%, 92% and 82%, respectively. Aortic flow measurements were possible in 53%, 95% and in 89% patients, respectively. The correlation between pre-contrast single-slab measurements and 2D-PC reference was weak (r = 0.21), but improved with both contrast enhancement (r = 0.71) and with MOTS (r = 0.67).ConclusionsAlthough non-contrast MOTS 4D-flow improves valve function visualization and diagnostic accuracy, a significant proportion of valves cannot be accurately assessed. However, aortic flow measurements using non-contrast MOTS is feasible and reaches similar accuracy to that of contrast-enhanced 4D-flow.     

The value of ESWAN in diagnosis and differential diagnosis of prostate cancer: Preliminary study

ObjectiveTo evaluate the value of enhanced T2 star-weighted angiography (ESWAN) in diagnosis and differential diagnosis of prostate cancer by comparing the multiple indices of ESWAN in benign prostatic hyperplasia (BPH), prostate cancer (PCa) and the normal peripheral zone (PZ).MethodsTraditional MRI and ESWAN were performed on forty-nine clinically-diagnosed PCa patients, sixty BPH patients, and forty-six normal adult males. The ESWAN indices (magnitude value, phase value, R2* value and T2* value) measured on different regions of interest (ROIs) were analyzed. Additionally, receiver operating characteristic (ROC) analysis was performed to obtain the area under the curve (AUC), sensitivity, specificity, and optimal cut-off points of PCa and BPH, PCa and PZ respectively.ResultsThe magnitude value, phase value, R2* value and T2* value of PZ were 1529.43 ± 254.43, 0.0689 ± 0.1619, 16.57 ± 8.11, 82.75 ± 53.87, respectively; the magnitude value, phase value, R2* value, and T2* value of PCa were 1540.18 ± 338.62, − 0.0176 ± 0.0919, 26.93 ± 11.31, and 45.99 ± 17.43, respectively; the magnitude value, phase value, R2* value, and T2* value of BPH were 1579.49 ± 285.28, 0.0209 ± 0.0839, 20.69 ± 3.95, and 51.56 ± 8.90, respectively. Compared with normal PZ, phase value of PCa was lower (t = − 3.302, P = 0.001), R2* value higher (t = 5.326, P = 0.000), and T2* value lower (t = − 4.570, P = 0.000); compared with BPH, phase value of PCa was lower (t = − 2.261, P = 0.026), R2* value higher (t = 3.988, P = 0.000), and T2* value lower (t = − 2.155, P = 0.033). When PCa and PZ were distinguished, the AUC of magnitude value, phase value, R2* value, and T2* value were respectively 0.539 (P = 0.510), 0.679 (P = 0.0007), 0.811 (P < 0.0001), and 0.762 (P < 0.0001); the diagnosis efficiency of R2* value was higher than that of T2* value (P = 0.037), while the diagnosis efficiency of T2* value was equivalent to phase value (P = 0.256). When PCa was differentiated from BPH, the AUC of magnitude value, phase value, R2* value, and T2* value were 0.518 (P = 0.752), 0.612 (P = 0.039), 0.705 (P = 0.0001), and 0.685 (P = 0.0006), respectively; there was no statistical difference in the diagnostic efficiency of phase value, R2* value, and T2* value.ConclusionsThe phase value, R2* value and T2* value can distinguish PCa and normal PZ, PCa and BPH, so they are valuable for the diagnosis and differential diagnosis of PCa, moreover, the diagnostic efficiency of R2* value is better than other indices.