3D pulmonary perfusion MRI and MR angiography of pulmonary embolism in pigs after a single injection of a blood pool MR contrast agent

Abstract

The purpose of this study was to assess the feasibility of contrast-enhanced 3D perfusion MRI and MR angiography (MRA) of pulmonary embolism (PE) in pigs using a single injection of the blood pool contrast Gadomer. PE was induced in five domestic pigs by injection of autologous blood thrombi. Contrast-enhanced first-pass 3D perfusion MRI (TE/TR/FA: 1.0 ms/2.2 ms/40 degrees; voxel size: 1.3 x 2.5 x 4.0 mm3; TA: 1.8 s per data set) and high-resolution 3D MRA (TE/TR/FA: 1.4 ms/3.4 ms/40 degrees; voxel size: 0.8 x 1.0 x 1.6 mm3) was performed during and after a single injection of 0.1 mmol/kg body weight of Gadomer. Image data were compared to pre-embolism Gd-DTPA-enhanced MRI and post-embolism thin-section multislice CT (n = 2). SNR measurements were performed in the pulmonary arteries and lung. One animal died after induction of PE. In all other animals, perfusion MRI and MRA could be acquired after a single injection of Gadomer. At perfusion MRI, PE could be detected by typical wedge-shaped perfusion defects. While the visualization of central PE at MRA correlated well with the CT, peripheral PE were only visualized by CT. Gadomer achieved a higher peak SNR of the lungs compared to Gd-DTPA (21 +/- 8 vs. 13 +/- 3). Contrast-enhanced 3D perfusion MRI and MRA of PE can be combined using a single injection of the blood pool contrast agent Gadomer.

Time-resolved echo-shared parallel MRA of the lung: observer preference study of image quality in comparison with non-echo-shared sequences

“…Compared with conventional monophasic MRA or CTA, it features improved arterial-venous discrimination, reduced sensitivity to motion artifacts, and additional functional information, such as lung perfusion [3,4,7,12,13]. Unfortunately, depending on the temporal resolution, the spatial resolution of time-resolved MRA is often limited.…”

Value of high spatial and high temporal resolution magnetic resonance angiography for differentiation between idiopathic and thromboembolic pulmonary hypertension: initial results

“…MR perfusion techniques were used in some studies for diagnosis of PE [6,16,17]. The perfusion patterns resulting from PE were focal defects with sharp margins.…”

“…(2) Time-resolved MRA techniques (TR-MRA) are available, resulting in two data sets: (a) reduced spatial resolution angiography of the pulmonary arteries, and (b) perfusion-weighted data sets of the lung parenchyma [6]. The second approach seems very promising, as 3D data sets of the whole lung are acquired in 1.5 s, almost eliminating breathing artefacts.…”

Magnetic resonance imaging of acute pulmonary embolism

“…In addition, several MRA studies (e.g. time-resolved pulmonary MRA, high-resolution pulmonary MRA, and wholebody MR venography) may be performed after a single bolus injection [19]. Currently, with the exception of Switzerland, pulmonary MRA with gadofosveset trisodium has to be regarded as off-label use.…”