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Rapid flow assessment of congenital heart disease with high-spatiotemporal-resolution gated spiral phase-contrast MR imaging.

ABSTRACT: To validate a prospectively triggered spiral phase-contrast magnetic resonance (MR) sequence accelerated with sensitivity encoding (SENSE) in a population of children and adults with congenital heart disease.The local research ethics committee approved this study, and written consent was obtained from all patients or guardians. Stroke volumes were quantified in 40 patients (mean age ± standard deviation: 21.4 years ± 13.8, age range: 3.0-61.3 years; 22 male patients aged 3.0-38.0 years [mean age, 17.2 years ± 10.5], 18 female patients aged 4.7-61.3 years [mean age, 26.6 years ± 15.9]) with congenital heart disease in the aorta (n = 40), main pulmonary artery (n = 38), right pulmonary artery (n = 22), and left pulmonary artery (n = 24). Stroke volumes were obtained with (a) breath-hold spiral phase-contrast MR imaging with SENSE, (b) conventional breath-hold cartesian phase-contrast MR imaging, and (c) reference free-breathing phase-contrast MR imaging. Stroke volumes were compared by using repeated-measures analysis of variance, Bland-Altman analysis, and correlation coefficients.Imaging time with the breath-hold spiral phase-contrast MR sequence was significantly lower than that with the conventional breath-hold phase-contrast MR sequence (~5 seconds vs ~16 seconds, respectively; P < .0001). There was excellent agreement in stroke volumes in all vessels between the reference free-breathing sequence (mean volume, 60.3 mL ± 27.3) and the two breath-hold sequences-spiral SENSE phase-contrast MR imaging (mean volume, 59.5 mL ± 27.1; P < .001) and conventional cartesian phase-contrast MR imaging (mean volume, 59.8 mL ± 27.6; P = .268). The limits of agreement were smaller with the spiral breath-hold sequence than with the conventional breath-hold sequence (-4.4 mL, 2.9 mL vs -10.3 mL, 9.3 mL, respectively); correlation was similar (r = 0.998 vs r = 0.984, respectively).Flow volumes can be accurately and reliably quantified by using a spiral SENSE phase-contrast MR sequence, with high spatiotemporal resolution obtained in a short breath hold.

SUBMITTER: Steeden JA

PROVIDER: S-EPMC3121014 | biostudies-other | 2011 Jul

REPOSITORIES: biostudies-other

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Project description:BackgroundReal-time cardiovascular magnetic resonance (CMR) assessment of ventricular volumes and function enables data acquisition during free-breathing. The requirement for high spatiotemporal resolution in children necessitates the use of highly accelerated imaging techniques.MethodsA novel real-time balanced steady state free precession (bSSFP) spiral sequence reconstructed using Compressed Sensing (CS) was prospectively validated against the breath-hold clinical standard for assessment of ventricular volumes in 60 children with congenital heart disease. Qualitative image scoring, quantitative image quality, as well as evaluation of biventricular volumes was performed. Standard BH and real-time measures were compared using the paired t-test and agreement for volumetric measures were evaluated using Bland Altman analysis.ResultsAcquisition time for the entire short axis stack (~?13 slices) using the spiral real-time technique was ~?20 s, compared to ~?348 s for the standard breath hold technique. Qualitative scores reflected more residual aliasing artefact (p?<?0.001) and lower edge definition (p?<?0.001) in spiral real-time images than standard breath hold images, with lower quantitative edge sharpness and estimates of image contrast (p?<?0.001). There was a small but statistically significant (p?<?0.05) overestimation of left ventricular (LV) end-systolic volume (1.0?±?3.5 mL), and underestimation of LV end-diastolic volume (-?1.7?±?4.6 mL), LV stroke volume (-?2.6?±?4.8 mL) and LV ejection fraction (-?1.5?±?3.0%) using the real-time technique. We also observed a small underestimation of right ventricular stroke volume (-?1.8?±?4.9 mL) and ejection fraction (-?1.4?±?3.7%) using the real-time imaging technique. No difference in inter-observer or intra-observer variability were observed between the BH and real-time sequences.ConclusionsReal-time bSSFP imaging using spiral trajectories combined with a compressed sensing reconstruction showed good agreement for quantification of biventricular metrics in children with heart disease, despite slightly lower image quality. This technique holds the potential for free breathing data acquisition, with significantly shorter scan times in children.

Project description:Background Dynamic contrast material-enhanced MR lymphangiography has recently emerged as a technique to image the lymphatic anatomy and identify lymphatic flow abnormalities; however, a method to quantify lymphatic flow in health and disease is needed. Purpose To develop a method to quantify thoracic lymphatic flow patterns using dynamic contrast-enhanced MR lymphangiography. Materials and Methods The following patients with dynamic contrast-enhanced MR lymphangiography images collected in 2015 and 2016 were retrospectively identified: group A, neonates with chylothorax; group B, children with heart failure complicated by plastic bronchitis; and group C, adults with lymphatic plastic bronchitis and without heart failure. An automated image segmentation method was developed for segmenting the contrast-enhanced lymphatic flow in spatiotemporal domains from the dynamic contrast-enhanced MR lymphangiography images. The lymphatic flow rates were quantified for individual patients on the basis of their spatiotemporal dynamic contrast-enhanced MR lymphangiography segmentation results, and the flow rates were compared among the three patient groups by using Wilcoxon rank sum tests. Results Twenty-two patients were evaluated: seven neonates (mean age, 49 days ± 71 [standard deviation]; three boys, four girls), 10 children (mean age, 8 years ± 3; seven boys, three girls), and five adults (mean age, 46 years ± 10; three men, two women). The proposed method was used to obtain lymphatic flow segmentation results with Dice scores of 0.80, 0.82, and 0.83 for patients from groups A, B, and C, respectively. The mean flow rates for groups A, B, and C were 1.8 mL/min ± 1.4, 4.0 mL/min ± 1.8, and 12.5 mL/min ± 3.8, respectively. The flow rate differed significantly between groups A and B (P = .002), groups A and C (P = .01), and groups B and C (P = .01). Conclusion An automatic spatiotemporal segmentation method was used to determine thoracic lymphatic flow rates in individual patients based on their dynamic contrast-enhanced MR lymphangiographic images. © RSNA, 2020 Online supplemental material is available for this article.

Project description:PurposeTo prospectively evaluate the feasibility of performing high-spatial-resolution (1-mm isotropic) time-resolved three-dimensional (3D) contrast material-enhanced magnetic resonance (MR) angiography of the peripheral vasculature with Cartesian acquisition with projection-reconstruction-like sampling (CAPR) and eightfold accelerated two-dimensional (2D) sensitivity encoding (SENSE).Materials and methodsAll studies were approved by the institutional review board and were HIPAA compliant; written informed consent was obtained from all participants. There were 13 volunteers (mean age, 41.9; range, 27-53 years). The CAPR sequence was adapted to provide 1-mm isotropic spatial resolution and a 5-second frame time. Use of different receiver coil element sizes for those placed on the anterior-to-posterior versus left-to-right sides of the field of view reduced signal-to-noise ratio loss due to acceleration. Results from eight volunteers were rated independently by two radiologists according to prominence of artifact, arterial to venous separation, vessel sharpness, continuity of arterial signal intensity in major arteries (anterior and posterior tibial, peroneal), demarcation of origin of major arteries, and overall diagnostic image quality. MR angiographic results in two patients with peripheral vascular disease were compared with their results at computed tomographic angiography.ResultsThe sequence exhibited no image artifact adversely affecting diagnostic image quality. Temporal resolution was evaluated to be sufficient in all cases, even with known rapid arterial to venous transit. The vessels were graded to have excellent sharpness, continuity, and demarcation of the origins of the major arteries. Distal muscular branches and the communicating and perforating arteries were routinely seen. Excellent diagnostic quality rating was given for 15 (94%) of 16 evaluations.ConclusionThe feasibility of performing high-diagnostic-quality time-resolved 3D contrast-enhanced MR angiography of the peripheral vasculature by using CAPR and eightfold accelerated 2D SENSE has been demonstrated.

Project description:PurposeThis study seeks to evaluate the use of quantitative texture parameters extracted from multiphasic contrast-enhanced magnetic resonance (MR) imaging in differentiating between benign and malignant masses (oncocytoma vs. clear cell and papillary RCC) and between common subtypes of renal cell carcinoma (clear cell vs. papillary RCC) in small renal masses (< 4 cm).MethodOne-hundred and forty-two renal lesions (90 clear cell and 22 papillary RCCs; 30 oncocytomas) were identified in a cohort of 41 patients (18 men, 23 women: mean age, 52.8 ± 14.4 years) who underwent preoperative multiphasic contrast-enhanced MR with four phases (unenhanced, arterial, venous, and delayed) between 2015 and 2016. In this study, texture features were extracted from entire cross-sectional tumoral region in three consecutive slices containing the largest cross-sectional area from each of the four phases. The change in imaging feature between precontrast imaging and each postcontrast phase was calculated. Data dimension reduction and feature selection were performed by conducting (1) pairwise Wilcoxon rank test followed by modified false discovery rate adjustment, and (2) Lasso regression. Multivariate modeling incorporating the selected features was performed using random forest classification method.ResultsHistogram imaging features were informative variables in differentiating between benign and malignant masses, while textures imaging features were of added value in differentiating between subtypes of RCCs. Papillary RCCs were distinguished from clear cell RCCs (sensitivity 65.5%, specificity 88%, and accuracy 77.9%), oncocytomas from clear cell RCCs (sensitivity 67.3%, specificity 88.9%, and accuracy 79.3%), and oncocytomas from papillary and clear cell RCCs (sensitivity 64.7%, specificity 85.9%, and accuracy 77.9%).ConclusionsA combination of histogram and texture imaging features on multiphasic MR can help differentiate histologic cell types in common small renal masses (< 4 cm).

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Rapid flow assessment of congenital heart disease with high-spatiotemporal-resolution gated spiral phase-contrast MR imaging.

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