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Abstract Background Myocardial infarction (MI) documented by late gadolinium enhancement (LGE) has clinical and prognostic importance, but its detection is sometimes compromised by poor contrast between blood and MI. MultiContrast Delayed Enhancement (MCODE) is a technique that helps discriminate subendocardial MI from blood pool by simultaneously providing a T2-weighted image with a PSIR (phase sensitive inversion recovery) LGE image. In this clinical validation study, our goal was to prospectively compare standard LGE imaging to MCODE in the detection of MI. Methods Imaging was performed on a 1.5 T scanner on patients referred for CMR including a LGE study. Prospective comparisons between MCODE and standard PSIR LGE imaging were done by targeted, repeat imaging of slice locations. Clinical data were used to determine MI status. Images at each of multiple time points were read on separate days and categorized as to whether or not MI was present and whether an infarction was transmural or subendocardial. The extent of infarction was scored on a sector-by-sector basis. Results Seventy-three patients were imaged with the specified protocol. The majority were referred for vasodilator perfusion exams and viability assessment (37 ischemia assessment, 12 acute MI, 10 chronic MI, 12 other diagnoses). Forty-six patients had a final diagnosis of MI (30 subendocardial and 16 transmural). MCODE had similar specificity compared to LGE at all time points but demonstrated better sensitivity compared to LGE performed early and immediately before and after the MCODE (p = 0.008 and 0.02 respectively). Conventional LGE only missed cases of subendocardial MI. Both LGE and MCODE identified all transmural MI. Based on clinical determination of MI, MCODE had three false positive MI’s; LGE had two false positive MI’s including two of the three MCODE false positives. On a per sector basis, MCODE identified more infarcted sectors compared to LGE performed immediately prior to MCODE (p < 0.001). Conclusion While both PSIR LGE and MCODE were good in identifying MI, MCODE demonstrated more subendocardial MI’s than LGE and identified a larger number of infarcted sectors. The simultaneous acquisition of T1 and T2-weighted images improved differentiation of blood pool from enhanced subendocardial MI.

Background: MRI T2* and R2* mapping have gained clinical acceptance for noninvasive assessment of iron overload. Lower field MRI may offer increased measurement dynamic range in patients with high iron concentration and may potentially increase MRI accessibility, but it is compromised by lower signal‐to‐noise ratio that reduces measurement precision. Purpose: To characterize a high‐performance 0.55 T MRI system for evaluating patients with liver iron overload. Study Type: Prospective. Population: Forty patients with known or suspected iron overload (sickle cell anemia [n = 5], ß‐thalassemia [n = 3], and hereditary spherocytosis [n = 2]) and a liver iron phantom. Field strength/sequence: A breath‐held multiecho gradient echo sequence at 0.55 T and 1.5 T. Assessment: Patients were imaged with T2*/R2* mapping 0.55 T and 1.5 T within 24 hours, and 16 patients returned for follow‐up exams within 6–16 months, resulting in 56 paired studies. Liver T2* and R2* measurements and standard deviations were compared between 0.55 T and 1.5 T and used to validate a predictive model between field strengths. The model was then used to classify iron overload at 0.55 T. Statistical Tests: Linear regression and Bland–Altman analysis were used for comparisons, and measurement precision was assessed using the coefficient of variation. A P‐value < 0.05 was considered statistically significant. Results: R2* was significantly lower at 0.55 T in our cohort (488 ± 449 s−1 at 1.5 T vs. 178 ± 155 s−1 at 0.55 T, n = 56 studies) and in the patients with severe iron overload (937 ± 369 s−1 at 1.5 T vs. 339 ± 127 s−1 at 0.55 T, n = 23 studies). The coefficient of variation indicated reduced precision at 0.55 T (3.5 ± 2.2% at 1.5 T vs 6.9 ± 3.9% at 0.55 T). The predictive model accurately predicted 1.5 T R2* from 0.55 T R2* (Bland Altman bias = −6.6 ± 20.5%). Using this model, iron overload at 0.55 T was classified as: severe R2* > 185 s−1, moderate 81 s−1 < R2* < 185 s−1, and mild 45 s−1 < R2* < 91 s−1. Data Conclusion: We demonstrated that 0.55 T provides T2* and R2* maps that can be used for the assessment of liver iron overload in patients. Evidence Level: 2 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Purpose: To develop an isotropic high‐resolution stack‐of‐spirals UTE sequence for pulmonary imaging at 0.55 Tesla by leveraging a combination of robust respiratory‐binning, trajectory correction, and concomitant‐field corrections. Methods: A stack‐of‐spirals golden‐angle UTE sequence was used to continuously acquire data for 15.5 minutes. The data was binned to a stable respiratory phase based on superoinferior readout self‐navigator signals. Corrections for trajectory errors and concomitant field artifacts, along with image reconstruction with conjugate gradient SENSE, were performed inline within the Gadgetron framework. Finally, data were retrospectively reconstructed to simulate scan times of 5, 8.5, and 12 minutes. Image quality was assessed using signal‐to‐noise, image sharpness, and qualitative reader scores. The technique was evaluated in healthy volunteers, patients with coronavirus disease 2019 infection, and patients with lung nodules. Results: The technique provided diagnostic quality images with parenchymal lung SNR of 3.18 ± 0.0.60, 4.57 ± 0.87, 5.45 ± 1.02, and 5.89 ± 1.28 for scan times of 5, 8.5, 12, and 15.5 minutes, respectively. The respiratory binning technique resulted in significantly sharper images (p < 0.001) as measured with relative maximum derivative at the diaphragm. Concomitant field corrections visibly improved sharpness of anatomical structures away from iso‐center. The image quality was maintained with a slight loss in SNR for simulated scan times down to 8.5 minutes. Inline image reconstruction and artifact correction were achieved in <5 minutes. Conclusion: The proposed pulmonary imaging technique combined efficient stack‐of‐spirals imaging with robust respiratory binning, concomitant field correction, and trajectory correction to generate diagnostic quality images with 1.75 mm isotropic resolution in 8.5 minutes on a high‐performance 0.55 Tesla system. [ABSTRACT FROM AUTHOR]

Background: Myocardial infarction (MI) documented by late gadolinium enhancement (LGE) has clinical and prognostic importance, but its detection is sometimes compromised by poor contrast between blood and MI. MultiContrast Delayed Enhancement (MCODE) is a technique that helps discriminate subendocardial MI from blood pool by simultaneously providing a T2-weighted image with a PSIR (phase sensitive inversion recovery) LGE image. In this clinical validation study, our goal was to prospectively compare standard LGE imaging to MCODE in the detection of MI. Methods: Imaging was performed on a 1.5 T scanner on patients referred for CMR including a LGE study. Prospective comparisons between MCODE and standard PSIR LGE imaging were done by targeted, repeat imaging of slice locations. Clinical data were used to determine MI status. Images at each of multiple time points were read on separate days and categorized as to whether or not MI was present and whether an infarction was transmural or subendocardial. The extent of infarction was scored on a sector-by-sector basis. Results: Seventy-three patients were imaged with the specified protocol. The majority were referred for vasodilator perfusion exams and viability assessment (37 ischemia assessment, 12 acute MI, 10 chronic MI, 12 other diagnoses). Forty-six patients had a final diagnosis of MI (30 subendocardial and 16 transmural). MCODE had similar specificity compared to LGE at all time points but demonstrated better sensitivity compared to LGE performed early and immediately before and after the MCODE (p = 0.008 and 0.02 respectively). Conventional LGE only missed cases of subendocardial MI. Both LGE and MCODE identified all transmural MI. Based on clinical determination of MI, MCODE had three false positive MI's; LGE had two false positive MI's including two of the three MCODE false positives. On a per sector basis, MCODE identified more infarcted sectors compared to LGE performed immediately prior to MCODE (p < 0.001). Conclusion: While both PSIR LGE and MCODE were good in identifying MI, MCODE demonstrated more subendocardial MI's than LGE and identified a larger number of infarcted sectors. The simultaneous acquisition ofT1 and T2-weighted images improved differentiation of blood pool from enhanced subendocardial MI. [ABSTRACT FROM AUTHOR]

T2-weighted MRI of edema in acute myocardial infarction (MI) provides a means of differentiating acute and chronic MI, and assessing the area at risk of infarction. Conventional T2-weighted imaging of edema uses a turbo spin-echo (TSE) readout with dark-blood preparation. Clinical applications of dark-blood TSE methods can be limited by artifacts such as posterior wall signal loss due to through-plane motion, and bright subendocardial artifacts due to stagnant blood. Single-shot imaging with a T2-prepared SSFP readout provides an alternative to dark-blood TSE and may be conducted during free breathing. We hypothesized that T2-prepared SSFP would be a more reliable method than dark-blood TSE for imaging of edema in patients with MI. In patients with MI (22 acute and nine chronic MI cases), T2-weighted imaging with both methods was performed prior to contrast administration and delayed-enhancement imaging. The T2-weighted images using TSE were nondiagnostic in three of 31 cases, while six additional cases rated as being of diagnostic quality yielded incorrect diagnoses. In all 31 cases the T2-prepared SSFP images were rated as diagnostic quality, correctly differentiated acute or chronic MI, and correctly determined the coronary territory. Free-breathing T2-prepared SSFP provides T2-weighted images of acute MI with fewer artifacts and better diagnostic accuracy than conventional dark-blood TSE. Magn Reson Med 57:891-897, 2007. Published 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]