Nonenhanced MR angiography of the pulmonary arteries using single-shot radial quiescent-interval slice-selective (QISS): a technical feasibility study

Abstract

BackgroundFor evaluation of the pulmonary arteries in patients suspected of pulmonary embolism, CT angiography (CTA) is the first-line imaging test with contrast-enhanced MR angiography (CEMRA) a potential alternative. Disadvantages of CTA include exposure to ionizing radiation and an iodinated contrast agent, while CEMRA is sensitive to respiratory motion and requires a gadolinium-based contrast agent. The primary goal of our technical feasibility study was to evaluate pulmonary arterial conspicuity using breath-hold and free-breathing implementations of a recently-developed nonenhanced approach, single-shot radial quiescent-interval slice-selective (QISS) MRA.MethodsBreath-hold and free-breathing, navigator-gated versions of radial QISS MRA were evaluated at 1.5 Tesla in three healthy subjects and 11 patients without pulmonary embolism or arterial occlusion by CTA. Images were scored by three readers for conspicuity of the pulmonary arteries through the level of the segmental branches. In addition, one patient with pulmonary embolism was imaged.ResultsScan time for a 54-slice acquisition spanning the pulmonary arteries was less than 2 minutes for breath-hold QISS, and less than 3.4 min using free-breathing QISS. Pulmonary artery branches through the segmental level were conspicuous with either approach. Free-breathing scans showed only mild blurring compared with breath-hold scans. For both readers, less than 1% of pulmonary arterial segments were rated as “not seen” for breath-hold and navigator-gated QISS, respectively. In subjects with atrial fibrillation, single-shot radial QISS consistently depicted the pulmonary artery branches, whereas navigator-gated 3D balanced steady-state free precession showed motion artifacts. In one patient with pulmonary embolism, radial QISS demonstrated central pulmonary emboli comparably to CEMRA and CTA. The thrombi were highly conspicuous on radial QISS images, but appeared subtle and were not prospectively identified on scout images acquired using a single-shot bSSFP acquisition.ConclusionsIn this technical feasibility study, both breath-hold and free-breathing single-shot radial QISS MRA enabled rapid, consistent demonstration of the pulmonary arteries through the level of the segmental branches, with only minimal artifacts from respiratory motion and cardiac arrhythmias. Based on these promising initial results, further evaluation in patients with suspected pulmonary embolism appears warranted.

Imaging of the pulmonary vasculature in congenital heart disease without gadolinium contrast: Intraindividual comparison of a novel Compressed SENSE accelerated 3D modified REACT with 4D contrast-enhanced magnetic resonance angiography

“…Therefore, many non-CE-MRA techniques have been developed in the past, including sequences based on turbo spin echo (TSE), spoiled gradient echo sequences, steadystate free precession (SSFP), and balanced SSFP (bSSFP) with SSFP and bSSFP being the most widely used for the assessment of the pulmonary vasculature in patients with CHD as well as other diseases affecting the pulmonary vessels, e.g. pulmonary hypertension (PH) [15][16][17][18][19]. Recently, a novel 3D Relaxation-Enhanced Angiography without Contrast and Triggering (REACT) sequence, a combination of non-volume-selective short tau inversion recovery (STIR) pulse, a T2 preparation (T2 prep) pulse, and dual gradient echo Dixon (mDIXON XD), was introduced.…”

Do radiologists detect chronic thromboembolic disease on computed tomography?

“…In studies on MRI in the detection of APE, primarily senior, experienced radiologists have reviewed the exams (65,(82)(83)(84)(85). However, in a clinical setting residents are commonly the primary reviewers (81).…”

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“…The high contrast to noise of the blood pool with a steady state free precession sequence means that it can serve as a non-contrast enhanced MR angiogram[ 53 ] when performed in 3D breathhold. Recent developments with 3D UTE SSFP and zero echo time sequences[ 54 ] also hold promise, however the lack of arterial and venous separation poses diagnostic limitations on this method when compared to state of the art CE MRA.…”