Dynamic Phantom for Flow Model in Magnetic Resonance Angiography

Purpose. To develop phantom for flow modeling in magnetic resonance angiography (MRA): relative contrast assessment, accuracy of the linear velocity and volumetric flow, what improve accuracy of diagnostic in cardiac and neurosurgical clinics (quality assessment of blood and cerebrospinal fluid motion). To compare scanners of different manufactures in points of the MRA efficiency using the developed phantom.Materials and methods. The main part of dynamic phantom consists of a disc filled with agarose gel (for linear and volumetric velocity control) and silicone tubes for fluid flow modelling. MR study was performed at MRI units of two manufactures for comparing quantitative assessments of MRA sequences: 2DTOF, 3DTOF, and at three MRI units of one firm for estimated accuracy calibration curve calculating and linear velocity and volumetric flow determination for PC MRA. Phantom study well correlate with clinical MRA results.Results. Obtained phantom scanning results in 2DTOF, 3DTOF sequences allow for objective comparing two MRI units of different manufactures. For 2DTOF mode was showed more effective signal enhancement affected by TOF effect for scanner of manufacture 2, then manufacture 1: 8.86 ± 0.88 и 6.07 ± 0.03 corresponding. For 3DTOF was observed rather more inflow relative contrast affected by TOF effect for scanner of manufacture 1: 6.06 ± 0.47 and 3.17 ± 0.83 corresponding. However, for manufacture 1 was showed more significant signal suppression for fat tissue, which improve vasculature visualization. Accuracy linear velocity fluid flow measurement in 2DPC is equal to ±2σ = ±0,4 by five pixels for three scanners of one manufacture. Using developed phantom was modelled MRA effects in 3DPC and Time-SLIP modes.Conclusions. The developed dynamic phantom can be used for calibration tests in MRA. The case of MRI units of two manufactures were compared quantitative assessments of MRA sequences and analyzed methods of enhancement fluid flow signal.

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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.

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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.

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