High resolution three-dimensional cardiac perfusion imaging using compartment-based k-t principal component analysis.

Three-dimensional myocardial perfusion imaging requires significant acceleration of data acquisition to achieve whole-heart coverage with adequate spatial and temporal resolution. The present article introduces a compartment-based k-t principal component analysis reconstruction approach, which permits three-dimensional perfusion imaging at 10-fold nominal acceleration. Using numerical simulations, it is shown that the compartment-based method results in accurate representations of dynamic signal intensity changes with significant improvements of temporal fidelity in comparison to conventional k-t principal component analysis reconstructions. Comparison of the two methods based on rest and stress three-dimensional perfusion data acquired with 2.3 × 2.3 × 10 mm(3) during a 225 msec acquisition window in patients confirms the findings and demonstrates the potential of compartment-based k-t principal component analysis for highly accelerated three-dimensional perfusion imaging.

Accelerated cardiac perfusion imaging using k-t SENSE with SENSE training.

In k-t sensitivity encoding (SENSE), MR data acquisition performed in parallel by multiple coils is accelerated by sparsely sampling the k-space over time. The resulting aliasing is resolved by exploiting spatiotemporal correlations inherent in dynamic images of natural objects. In this article, a modified k-t SENSE reconstruction approach is presented, which aims at improving the temporal fidelity of first-pass, contrast-enhanced myocardial perfusion images at high accelerations. The proposed technique is based on applying parallel imaging on the training data in order to increase their spatial resolution. At a net acceleration of 5.8 (k-t factor = 8, training profiles = 11) accurate representations of dynamic signal-intensities were achieved. The efficacy of this approach as well as limitations due to noise amplification were investigated in computer simulations and in vivo experiments.

Dynamic 3-dimensional stress cardiac magnetic resonance perfusion imaging: detection of coronary artery disease and volumetry of myocardial hypoenhancement before and after coronary stenting.

OBJECTIVES: The aim of this study was to establish a new, dynamic 3-dimensional cardiac magnetic resonance (3D-CMR) perfusion scan technique exploiting data correlation in k-space and time with sensitivity-encoding and to determine its value for the detection of coronary artery disease (CAD) and volumetry of myocardial hypoenhancement (VOLUME(hypo)) before and after percutaneous coronary stenting. BACKGROUND: Dynamic 3D-CMR perfusion imaging might improve detection of myocardial perfusion deficits and could facilitate direct volumetry of myocardial hypoenhancement. METHODS: In 146 patients with known or suspected CAD, a 3.0-T CMR examination was performed including cine imaging, 3D-CMR perfusion under adenosine stress and at rest followed by delayed enhancement imaging. Quantitative invasive coronary angiography defined significant CAD (≥ 50% luminal narrowing). Forty-eight patients underwent an identical repeat CMR examination after percutaneous stenting of at least 1 coronary lesion. The 3D-CMR perfusion scans were visually classified as pathologic if ≥ 1 segment showed an inducible perfusion deficit in the absence of delayed enhancement. The VOLUME(hypo) was measured by segmentation of the area of inducible hypoenhancement and normalized to left-ventricular myocardial volume (%VOLUME(hypo)). RESULTS: The 3D-CMR perfusion resulted in a sensitivity, specificity, and diagnostic accuracy of 91.7%, 74.3%, and 82.9%, respectively. Before and after coronary stenting, %VOLUME(hypo) averaged to 14.2 ± 9.5% and 3.2 ± 5.2%, respectively, with a relative VOLUME(hypo) reduction of 79.4 ± 25.4%. Intrareader and inter-reader reproducibility of VOLUME(hypo) measurements was high (Lin's concordance correlation coefficient, 0.96 and 0.96, respectively). CONCLUSIONS: The 3D-CMR stress perfusion provided high image quality and high diagnostic accuracy for the detection of significant CAD. The VOLUME(hypo) measurements were highly reproducible and allowed for the assessment of the treatment effect achievable by percutaneous coronary stenting.

High resolution 3D cardiac perfusion imaging using compartment-based k-t PCA.

k-t PCA is a a regularized image reconstruction method to recover images from highly undersampled dynamic magnetic resonance data. It is based on the decomposition of the training and the undersampled data into temporally and spatially invariant terms using principal component analysis. In this paper, a compartment-based k-t PCA reconstruction approach is presented, with the objective of improving highly undersampled, high-resolution 3D myocardial perfusion magnetic resonance imaging (MRI) by constraining the temporal content of different spatial compartments in the image series based on the bolus arrival times and prior knowledge about the signal intensity-time curves.

Clinical feasibility of accelerated, high spatial resolution myocardial perfusion imaging.

OBJECTIVES: The aim of this study was to assess the clinical feasibility and diagnostic performance of an acceleration technique based on k-space and time (k-t) sensitivity encoding (SENSE) for rapid, high-spatial resolution cardiac magnetic resonance (CMR) myocardial perfusion imaging. BACKGROUND: The assessment of myocardial perfusion is of crucial importance in the evaluation of patients with known or suspected coronary artery disease. CMR myocardial perfusion imaging performs favorably compared to single photon-emission computed tomography and offers higher spatial resolution, particularly when combined with scan acceleration techniques such as k-t SENSE. A previous study showed that k-t SENSE accelerated myocardial perfusion CMR with 5-fold acceleration is feasible and delivers high diagnostic accuracy for the detection of coronary artery disease. Higher acceleration factors have not been attempted clinically because of concerns over temporal blurring effects of the time-varying signal during contrast bolus passage. METHODS: Twenty patients underwent myocardial perfusion CMR imaging using a 3.0-T whole-body CMR imager before diagnostic X-ray coronary angiography. Perfusion images were obtained using an extension of the k-t SENSE method using parallel imaging to double the spatial resolution of the k-t SENSE training images. This extension, termed k-t SENSE+, permitted 8-fold nominal scan acceleration and an in-plane spatial resolution of up to 1.1 x 1.1 mm(2). Perfusion scores were derived by 2 blinded observers for 16 myocardial segments and compared to quantitative analysis of X-ray coronary angiography. RESULTS: CMR data were successfully obtained in all 20 patients. High diagnostic accuracy was achieved using CMR, as reflected by areas under the receiver-operator characteristic curve of 0.94 and 0.82 for detecting stenoses >50% and >75%, respectively. Observer agreement between 2 readers had a kappa value of 0.92. The areas under the receiver-operator characteristic curves for the left anterior descending, left circumflex, and right coronary artery territories with stenoses >50% were 0.75, 0.92, and 0.79, respectively. CONCLUSIONS: Accelerated CMR perfusion imaging is clinically feasible and offers excellent diagnostic performance in detecting coronary stenosis.