3D volume extraction of cerebrovascular structure on brain magnetic resonance angiography data sets

Abstract Background Radial self-navigated (RSN) whole-heart coronary cardiovascular magnetic resonance angiography (CCMRA) is a free-breathing technique that estimates and corrects for respiratory motion. However, RSN has been limited to a 1D rigid correction which is often insufficient for patients with complex respiratory patterns. The goal of this work is therefore to improve the robustness and quality of 3D radial CCMRA by incorporating both 3D motion information and nonrigid intra-acquisition correction of the data into a framework called focused navigation (fNAV). Methods We applied fNAV to 500 data sets from a numerical simulation, 22 healthy subjects, and 549 cardiac patients. In each of these cohorts we compared fNAV to RSN and respiratory resolved extradimensional golden-angle radial sparse parallel (XD-GRASP) reconstructions of the same data. Reconstruction times for each method were recorded. Motion estimate accuracy was measured as the correlation between fNAV and ground truth for simulations, and fNAV and image registration for in vivo data. Percent vessel sharpness was measured in all simulated data sets and healthy subjects, and a subset of patients. Finally, subjective image quality analysis was performed by a blinded expert reviewer who chose the best image for each in vivo data set and scored on a Likert scale 0–4 in a subset of patients by two reviewers in consensus. Results The reconstruction time for fNAV images was significantly higher than RSN (6.1 ± 2.1 min vs 1.4 ± 0.3, min, p < 0.025) but significantly lower than XD-GRASP (25.6 ± 7.1, min, p < 0.025). Overall, there is high correlation between the fNAV and reference displacement estimates across all data sets (0.73 ± 0.29). For simulated data, healthy subjects, and patients, fNAV lead to significantly sharper coronary arteries than all other reconstruction methods (p < 0.01). Finally, in a blinded evaluation by an expert reviewer fNAV was chosen as the best image in 444 out of 571 data sets (78%; p < 0.001) and consensus grades of fNAV images (2.6 ± 0.6) were significantly higher (p < 0.05) than uncorrected (1.7 ± 0.7), RSN (1.9 ± 0.6), and XD-GRASP (1.8 ± 0.8). Conclusion fNAV is a promising technique for improving the quality of RSN free-breathing 3D whole-heart CCMRA. This novel approach to respiratory self-navigation can derive 3D nonrigid motion estimations from an acquired 1D signal yielding statistically significant improvement in image sharpness relative to 1D translational correction as well as XD-GRASP reconstructions. Further study of the diagnostic impact of this technique is therefore warranted to evaluate its full clinical utility.

Download Full-text

Dilatation of the entire thoracic aorta in patients with bicuspid aortic valve: a magnetic resonance angiography study

VASA ◽

10.1024/0301-1526.34.3.181 ◽

2005 ◽

Vol 34 (3) ◽

pp. 181-185 ◽

Cited By ~ 12

Author(s):

Westhoff-Bleck ◽

Meyer ◽

Lotz ◽

Tutarel ◽

Weiss ◽

...

Keyword(s):

Magnetic Resonance ◽

Magnetic Resonance Angiography ◽

Aortic Valve ◽

Pulmonary Artery ◽

Aortic Arch ◽

Thoracic Aorta ◽

Aortic Root ◽

Ascending Aorta ◽

Descending Aorta ◽

Severe Aortic Regurgitation

Background: The presence of a bicuspid aortic valve (BAV) might be associated with a progressive dilatation of the aortic root and ascending aorta. However, involvement of the aortic arch and descending aorta has not yet been elucidated. Patients and methods: Magnetic resonance angiography (MRA) was used to assess the diameter of the ascending aorta, aortic arch, and descending aorta in 28 patients with bicuspid aortic valves (mean age 30 ± 9 years). Results: Patients with BAV, but without significant aortic stenosis or regurgitation (n = 10, mean age 27 ± 8 years, n.s. versus control) were compared with controls (n = 13, mean age 33 ± 10 years). In the BAV-patients, aortic root diameter was 35.1 ± 4.9 mm versus 28.9 ± 4.8 mm in the control group (p < 0.01). The diameter of the ascending aorta was also significantly increased at the level of the pulmonary artery (35.5 ± 5.6 mm versus 27.0 ± 4.8 mm, p < 0.001). BAV-patients with moderate or severe aortic regurgitation (n = 18, mean age 32 ± 9 years, n.s. versus control) had a significant dilatation of the aortic root, ascending aorta at the level of the pulmonary artery (41.7 ± 4.8 mm versus 27.0 ± 4.8 mm in control patients, p < 0.001) and, furthermore, significantly increased diameters of the aortic arch (27.1 ± 5.6 mm versus 21.5 ± 1.8 mm, p < 0.01) and descending aorta (21.8 ± 5.6 mm versus 17.0 ± 5.6 mm, p < 0.01). Conclusions: The whole thoracic aorta is abnormally dilated in patients with BAV, particularly in patients with moderate/severe aortic regurgitation. The maximum dilatation occurs in the ascending aorta at the level of the pulmonary artery. Thus, we suggest evaluation of the entire thoracic aorta in patients with BAV.

Download Full-text

Diagnostic accuracy of magnetic resonance angiography for acute pulmonary embolism - a systematic review and meta-analysis

VASA ◽

10.1024/0301-1526/a000509 ◽

2016 ◽

Vol 45 (2) ◽

pp. 149-154 ◽

Cited By ~ 2

Author(s):

Jie Li ◽

Lei Feng ◽

Jiangbo Li ◽

Jian Tang

Keyword(s):

Pulmonary Embolism ◽

Magnetic Resonance ◽

Magnetic Resonance Angiography ◽

Diagnostic Accuracy ◽

Acute Pulmonary Embolism ◽

Meta Analysis ◽

Likelihood Ratios ◽

Summary Receiver Operating Characteristic ◽

Acute Pe ◽

Limited Sensitivity

Abstract. Background: The aim of this meta-analysis was to evaluate the diagnostic accuracy of magnetic resonance angiography (MRA) for acute pulmonary embolism (PE). Methods: A systematic literature search was conducted that included studies from January 2000 to August 2015 using the electronic databases PubMed, Embase and Springer link. The summary receiver operating characteristic (SROC) curve, sensitivity, specificity, positive likelihood ratios (PLR), negative likelihood ratios (NLR), and diagnostic odds ratio (DOR) as well as the 95 % confidence intervals (CIs) were calculated to evaluate the diagnostic accuracy of MRA for acute PE. Meta-disc software version 1.4 was used to analyze the data. Results: Five studies were included in this meta-analysis. The pooled sensitivity (86 %, 95 % CI: 81 % to 90 %) and specificity (99 %, 95 % CI: 98 % to 100 %) demonstrated that MRA diagnosis had limited sensitivity and high specificity in the detection of acute PE. The pooled estimate of PLR (41.64, 95 % CI: 17.97 to 96.48) and NLR (0.17, 95 % CI: 0.11 to 0.27) provided evidence for the low missed diagnosis and misdiagnosis rates of MRA for acute PE. The high diagnostic accuracy of MRA for acute PE was demonstrated by the overall DOR (456.51, 95 % CI: 178.38 - 1168.31) and SROC curves (AUC = 0.9902 ± 0.0061). Conclusions: MRA can be used for the diagnosis of acute PE. However, due to limited sensitivity, MRA cannot be used as a stand-alone test to exclude acute PE.

Download Full-text