Ultra low-dose of gadobenate dimeglumine for late gadolinium enhancement (LGE) imaging in acute myocardial infarction: A feasibility study

Papillary Muscle Involvement during Acute Myocardial Infarction: Detection by Cardiovascular Magnetic Resonance Using T1 Mapping Technique and Papillary Longitudinal Strain

Papillary muscle (PPM) involvement in myocardial infarction (MI) increases the risk of secondary mitral valve regurgitation or PPM rupture and may be diagnosed using late gadolinium enhancement (LGE) imaging. The native T1-mapping (nT1) technique and PPM longitudinal strain (PPM-ls) have been used to identify PPM infarction (iPPM) without the use of the contrast agent. This study aimed to assess the diagnostic performance of nT1 and PPM-ls in the identification of iPPM. Forty-six patients, who performed CMR within 14-30 days after MI, were retrospectively enrolled: sixteen showed signs of iPPM on LGE images. nT1 values were measured within the infarcted area (IA), remote myocardium (RM), blood pool (BP), and anterolateral and posteromedial PPMs and compared using ANOVA. PPM-ls values have been assessed on cineMR images as the percentage of shortening between end-diastolic and end-systolic phases. Higher nT1 values and lower PPM-ls were found in infarcted compared to non-infarcted PPMs (nT1: 1219.3 ± 102.5 ms vs. 1052.2 ± 80.5 ms and 17.6 ± 6.3% vs. 21.6 ± 4.3%; p-value < 0.001 for both), with no significant differences between the nT1 of infarcted PPMs and IA and between the non-infarcted PPMs and RM. ROC analysis demonstrated an excellent discriminatory power for nT1 in detecting the iPPM (AUC = 0.874; 95% CI: 0.784-0.963; p < 0.001). nT1 and PPM-ls are valid tools in assessing iPPM with the advantage of avoiding contrast media administration.

Magnetic resonance imaging contrast enhancement synthesis using cascade networks with local supervision

PURPOSE

Gadolinium-based contrast agents (GBCAs) are widely administrated in MR imaging for diagnostic studies and treatment planning. Although GBCAs are generally thought to be safe, various health and environmental concerns have been raised recently about their use in MR imaging. The purpose of this work is to derive synthetic contrast enhance MR images from unenhanced counterpart images, thereby eliminating the need for GBCAs, using a cascade deep learning workflow that incorporates contour information into the network.

METHODS AND MATERIALS

The proposed workflow consists of two sequential networks: (1) a retina U-Net, which is first trained to derive semantic features from the non-contrast MR images in representing the tumor regions; and (2) a synthesis module, which is trained after the retina U-Net to take the concatenation of the semantic feature maps and non-contrast MR image as input and to generate the synthetic contrast enhanced MR images. After network training, only the non-contrast enhanced MR images are required for the input in the proposed workflow. The MR images of 369 patients from the multimodal brain tumor segmentation challenge 2020 (BraTS2020) dataset were used in this study to evaluate the proposed workflow for synthesizing contrast enhanced MR images (200 patients for five-fold cross-validation and 169 patients for hold-out test). Quantitative evaluations were conducted by calculating the normalized mean absolute error (NMAE), structural similarity index measurement (SSIM), and Pearson correlation coefficient (PCC). The original contrast enhanced MR images were considered as the ground truth in this analysis.

RESULTS

The proposed cascade deep learning workflow synthesized contrast enhanced MR images that are not visually differentiable from the ground truth with and without supervision of the tumor contours during the network training. Difference images and profiles of the synthetic contrast enhanced MR images revealed that intensity differences could be observed in the tumor region if the contour information was not incorporated in network training. Among the hold-out test patients, mean values and standard deviations of the NMAE, SSIM, and PCC were 0.063±0.022, 0.991±0.007 and 0.995±0.006, respectively, for the whole brain; and were 0.050±0.025, 0.993±0.008 and 0.999±0.003, respectively, for the tumor contour regions. Quantitative evaluations with five-fold cross-validation and hold-out test showed that the calculated metrics can be significantly enhanced (p-values ≤ 0.002) with the tumor contour supervision in network training.

CONCLUSION

The proposed workflow was able to generate synthetic contrast enhanced MR images that closely resemble the ground truth images from non-contrast enhanced MR images when the network training included tumor contours. These results suggest that it may be possible to minimize the use of GBCAs in cranial MR imaging studies.

Myocardial motion-corrected phase-sensitive inversion recovery late gadolinium enhancement in free breathing paediatric patients: a comparison with single-shot coherent gradient echo ("TrueFISP") phase-sensitive inversion recovery

AIM

To investigate the value of motion-corrected (MOCO) phase-sensitive inversion recovery (PSIR) late gadolinium enhancement (LGE) compared with single-shot balanced steady-state gradient echo ("TrueFISP", Siemens) PSIR in free breathing paediatric patients.

MATERIALS AND METHODS

In this retrospective study, 238 paediatric patients underwent clinical contrast-enhanced cardiovascular magnetic resonance imaging (CMRI). Both the single-shot TrueFISP PSIR and MOCO PSIR sequences were performed on each child. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists rated the quality of the images on a scale of 1-5 (1 = poor, 5 = very good). Bland-Altman, linear regression, and intraclass correlation coefficient were used to compared the extent of LGE of the single-shot TrueFISP PSIR and MOCO PSIR. Imaging artefacts were described and compared.

RESULTS

Children ranged in age from 60 days to 17 years with an average age of 8.1 ± 3.8 years. MOCO PSIR had higher SNR and CNR than the single-shot TrueFISP PSIR (p<0.001). Mean quality ratings for short-axis imaging were 4 (interquartile range, 3-4) for single-shot TrueFISP PSIR and 4 (interquartile range, 4-5) for MOCO PSIR (p<0.001). The scan time was faster for single-shot TrueFISP PSIR than for MOCO PSIR. The myocardial LGE results were similar with high agreement between the single-shot TrueFISP PSIR and MOCO PSIR (ICC = 0.955-0.986).

CONCLUSION

The MOCO PSIR sequence is feasible in children. MOCO PSIR is robust at high heart rates and can be performed without breath-holding with higher image-quality ratings than the single-shot TrueFISP PSIR.

Motion-corrected free-breathing late gadolinium enhancement combined with a gadolinium contrast agent with a high relaxation rate: an optimized cardiovascular magnetic resonance examination protocol

OBJECTIVE

This prospective study investigated the feasibility of an optimized cardiovascular magnetic resonance (CMR) examination protocol using the motion-corrected (MOCO), balanced steady-state free precession (bSSFP), phase-sensitive inversion recovery (PSIR) sequence combined with a gadolinium contrast agent with a high relaxation rate in patients who cannot hold their breath.

METHODS

Fifty-one patients with heart disease underwent CMR examinations twice and these were performed with different late gadolinium enhancement (LGE) imaging sequences (fast low-angle shot [FLASH] sequence vs. MOCO sequence) and different gadolinium contrast agents (gadopentetate dimeglumine vs. gadobenate dimeglumine) with a 48-hour interval. LGE image quality, total time spent in the whole study, and time taken to perform LGE imaging were compared for the two CMR examinations.

RESULTS

LGE images with the MOCO bSSFP PSIR sequence showed significantly higher image quality compared with those with the segmented FLASH PSIR sequence. There was a significant difference between the total scan time for the two examinations and different LGE sequences.

CONCLUSIONS

The MOCO bSSFP PSIR sequence effectively improves the quality of LGE images. Changing the CMR scanning protocol by combining the MOCO bSSFP PSIR sequence with a gadolinium contrast agent with a high relaxation rate effectively shortens the scan time.Clinical trial registration number: ChiCTR-ROC-17013978.

Late gadolinium enhancement is a risk factor for major adverse cardiac events in unrecognised myocardial infarction without apparent symptoms: a meta-analysis

AIM

To assess the prognostic role of unrecognised myocardial infarction (UMI) detected at late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMRII).

MATERIALS AND METHODS

Electronic databases including PubMed, EMBASE, Medline, and Cochrane were searched systematically for studies exploring the predictive value of UMI detected by LGE-CMRI for major adverse cardiac events (MACEs) and all-cause mortality in patients without apparent symptoms. Pooled hazard ratios (HRs) along with their 95% confidence intervals (CIs) were obtained from a random-effects model. Subgroup analyses were performed according to the different participants and outcomes.

RESULTS

Eight studies (2,009 participants) were identified comprising 442 patients with UMI detected at LGE-CMRI and 1,567 without UMI. The presence of UMI on LGE was associated with a significantly increased risk for MACEs (HRs: 3.44, 95% CI: 2.06 to 5.75; p<0.001) and all-cause mortality (HRs: 2.43, 95% CI: 1.00 to 5.87; p=0.05). In the subgroup analysis, the presence of UMI on LGE remained significantly associated with the risk of MACEs in patients with suspected coronary artery disease (HRs: 3.82, 95% CI: 2.49 to 5.85; p<0.01) and diabetes mellitus (HRs: 4.97, 95% CI: 3.02 to 8.18; p<0.01).

CONCLUSION

The presence of UMI detected by LGE-CMRI is associated with an increased risk of MACEs and all-cause mortality in patients without symptoms. LGE-CMRI could provide important prognostic information and guide risk stratification in patients with UMI.

WITHDRAWN: Risks and Benefits of Gadolinium-Based Contrast Enhanced MRI

The Publisher regrets that this article is an accidental duplication of an article that has already been published in [Seminars in Ultrasound, CT, and MRI, 41/2 (2020) 170–182], https://dx.doi.org/10.1053/j.sult.2019.12.005. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal

Preliminary study: Breast cancers can be well seen on 3T breast MRI with a half-dose of gadobutrol

BACKGROUND

Dynamic contrast enhanced (DCE) breast MRI is highly sensitive for breast cancer and requires gadolinium-based contrast agents (GBCA)s, which have potential safety concerns.

PURPOSE

Test whether breast cancers imaged by 3T DCE breast MRI with 0.05 mmol/kg of gadobutrol are detectable.

METHODS

Analysis of 3T DCE breast MRIs with half dose of gadobutrol from patients included in an IRB-approved and HIPPA-compliant prospective study of breast PET/MRI. Between 11/7/2014 and 3/2/2018, 41 consecutive women with biopsy-proven breast cancer that was at least 2 cm, multi-focal or multi-centric, had axillary metastasis, or had skin involvement who gave informed consent were included. Two breast radiologists independently recorded lesion conspicuity on a 4-point scale (0 = not seen, 1 = questionably seen, 2 = adequately seen, 3 = certainly seen), and measured the lesion. Size was compared between radiologists and with size on available mammogram, ultrasound, MRI, and surgical pathology. Inter-reader agreement was assessed by kappa coefficient for conspicuity. Lesion size comparisons were assessed using the Spearman rank correlation.

RESULTS

In 40 patients (ages 28.4-80.5, 51.9 years), there were 49 cancers. 10.1% of lesions were 1 cm or less and 26.5% of lesions were 2 cm or less. Each reader detected 49/49 cancers. Conspicuity scores ranged from 2 to 3, mean 2.9/3 for both readers (p = 0.47). Size on half-dose 3T DCE-MRI correlated with size on surgical pathology (r = 0.6, p = 0.03) while size on mammogram and ultrasound did not (r = 0.25, p = 0.46; r = 0.25, p = 0.42).

CONCLUSION

All breast cancers in this cohort, as small as 0.4 cm, were seen on 3T DCE breast MRI with 0.05 mmol/kg dose of gadobutrol.

MicroRNA-146b induces the PI3K/Akt/NF-κB signaling pathway to reduce vascular inflammation and apoptosis in myocardial infarction by targeting PTEN

The aim of the present study was to investigate the function of microRNA-146b on myocardial infarction and the mechanism. An MTT assay, Annexin V/propidium iodide (PI) apoptosis assay, ELISA kits, western blot analysis and a caspase-3/8 activity assay were used to measure cell growth, vascular apoptosis inflammatory factors, and the B-cell lymphoma 2-associated X protein (Bax), phosphatase and tensin homolog (PTEN), phosphoinositide 3-kinase (PI3K)/Akt/nuclear factor (NF)-κB signaling pathway. The expression of microRNA-146b was downregulated in the myocardial infarction rat model, compared with the control group. In an in vitro model of myocardial infarction, the downregulation of microRNA-146b increased inflammatory factors, vascular apoptosis, caspase-3/8 activity and the protein expression of Bax. MicroRNA-146b reduced vascular apoptosis, caspase-3/8 activity and the protein expression of Bax. MicroRNA-146b also regulated the PI3K/Akt/NF-κB signaling pathway to mediate vascular inflammation and apoptosis in myocardial infarction by PTEN. A PI3K inhibitor decreased the effect of microRNA-146b on vascular inflammation and apoptosis following myocardial infarction. In conclusion, microRNA-146b mediated vascular inflammation and apoptosis in patients with myocardial infarction, which may be associated with activation of the PI3K/Akt/NF-κB signaling pathway by PTEN.

Early myocardial gadolinium enhancement in patients with myocarditis: Validation of "Lake Louise consensus" criteria using a single bolus of 0.1mmol/Kg of a high relaxivity gadolinium-based contrast agent

OBJECTIVES

Global early gadolinium enhancement (EGE) is an accepted cardiac magnetic resonance (CMR) criterion for diagnosis of myocarditis. However, recommended enhancement thresholds are based specifically on standard-relaxivity Gd-chelates. We evaluated the performance of a high relaxivity MR contrast agent for detection of myocardial hyperemia in patients referred for endomyocardial biopsy (EMB).

METHODS

We retrospectively enrolled 54 patients (mean age: 44.1 years [range=18-77years]; 72% men) with suspected myocarditis who underwent CMR and EMB within four weeks of clinical onset. CMR imaging protocol included T2-weighted short tau inversion-recovery sequence, EGE and late gadolinium enhanced (LGE) imaging. For EGE imaging, free-breathing ECG-gated turbo spin echo T1-weighted (TSE T1w) sequences were acquired before and within the first three minutes after gadobenate dimeglumine (0.1mmol/Kg) administration. The ratio (EGEr) between myocardial and musculoskeletal early enhancement was calculated. Myocardial edema, EGE and late gadolinium enhancement (LGE) were correlated with EMB results. Receiver operating characteristic (ROC) curve analysis of EGE values was applied on the overall population.

RESULTS

EMB revealed myocarditis in 34/54 patients. Sensitivity, specificity and accuracy values of 0.61, 0.85 and 0.70, respectively, were obtained for a standard EGE threshold (EGEr>4.0). ROC analysis revealed an area under the curve of 0.701 for EGEr (IC95%:0.556-0.846, p=0.014) and 0.706 for absolute enhancement (IC95%:0.563-0.849, p=0.012). Sensitivity, specificity and accuracy values were 0.67, 0.80 and 0.72, respectively, for myocardial edema and 0.76, 0.75 and 0.76, respectively, for LGE.

CONCLUSIONS

High relaxivity contrast agents provide comparable results to standard-relaxivity chelates for EGE assessment in diagnosing myocarditis.