DSC Acquisition & Reconstruction
Ashley Stokes1

1Barrow Neurological Institute, United States


Dynamic susceptibility contrast (DSC) MRI methods provide valuable information regarding cerebral perfusion. In this talk, I will discuss current recommendations for best practices in clinical DSC-MRI acquisition and reconstruction. I will also highlight more recent technological advancements for DSC-MRI, along with the associated advantages and trade-offs of these methods. This talk will provide both a basic foundation for understanding current DSC-MRI protocols and insight into future directions for DSC-MRI acquisition and reconstruction.

Outcome / Objectives

At the end of this lecture, participants should be able to:

  • Understand the basic requirements for pulse sequence parameters to obtain DSC-MRI
  • Understand the advantages and potential trade-offs associated with more recent advances in DSC-MRI data acquisition


  • Cerebral perfusion is typically assessed with T2* weighted signals using dynamic susceptibility contrast (DSC) MRI
  • Best practices for standard DSC-MRI acquisition and reconstruction will be discussed
  • More recent advances in DSC acquisition and reconstruction will also be highlighted


Dynamic susceptibility contrast (DSC) MRI involves the dynamic acquisition of data before, during, and after injection of an exogenous paramagnetic contrast agent. Analysis of this dynamic time-course provides perfusion metrics such as cerebral blood volume (CBV) and flow (CBF). The ability to calculate these perfusion parameters (and with a certain amount of accuracy) depends on the acquisition and reconstruction method chosen. Various acquisition strategies for DSC-MRI and their advantages and tradeoffs will be discussed.


There are two types of contrast typically used for DSC-MRI: gradient-echo (T2*) or spin-echo (T2). Gradient-echo and spin-echo sequences have fundamentally different sensitivities to vessel size; gradient-echo contrast has higher vessel sensitivity to vessels of all sizes, while spin-echo contrast is maximally sensitive to capillary-sized vessels [1–3]. As a result, gradient-echo acquisitions have higher CNR per dose and tend to be the preferred method clinically. Drawbacks to gradient-echo acquisitions include susceptibility-induced signal dropouts at air-tissue interfaces and perfusion parameters that primarily reflect large vessels. On the other hand, spin-echo acquisitions – with their reduced sensitivity to susceptibility-induced image distortion and enhanced specificity to microvasculature – may be advantageous for certain pathologies. While traditional single-echo DSC acquisitions require an a priori choice between gradient-echo and spin-echo contrast, more advanced methods can acquire both types of contrast within a single sequence to circumvent the individual disadvantages [4–8].

Acquisition Readout

For DSC-MRI, rapid imaging (temporal resolution ≤ 1.5 s) is required to accurately sample the dynamic contrast-induced MR signal changes [9]. Due to these temporal requirements, the most commonly used acquisition strategy for DSC-MRI is single-shot echo planar imaging (EPI). These sequences provide good spatial coverage (typically 15-25 slices for whole brain coverage) with high temporal resolution and are widely available on clinical platforms. The main drawbacks to EPI-based acquisitions are signal dropout (particularly around sinuses and, in the case of tumors, around resection cavities) and image distortion. More advanced readout options have been developed to overcome these drawbacks; these options include advanced EPI readouts and non-Cartesian readouts. One effective method to reduce EPI image distortion is to split the k-space traversal into multiple shots using a segmented or interleaved EPI readout [10–13]. Non-Cartesian acquisitions, such as spiral [14] or radial [15] readouts, may provide further benefit over EPI: these acquisitions tend to be more robust to motion, have increased time efficiency, and may permit more aggressive undersampling to improve temporal and/or spatial resolution. While non-Cartesian options lack the distortions associated with EPI, these methods may induce other types of image artifacts (e.g., spiral-induced blurring) that impact the resulting perfusion quantification. While generally less available clinically, these advanced methods can provide significant advantages over traditional DSC-MRI methods with single-shot EPI.

Parameter Selection

The standard protocol for DSC-MRI acquisition includes a TE of 25-35ms, TR less than or equal to 1.5 seconds, and flip angle between 60 and 70 degrees [9]. These parameters are often chosen to maximize the T2* weighting, while maintaining acceptable SNR and minimizing T1 weighting. While single-echo acquisitions are commonly used, advanced multi-echo acquisitions have the advantage of both insensitivity to T1 effects and tunable TEs for both optimal tissue and arterial input function (AIF) characterization [16]. The minimum requirements for spatial resolution are generally 1-3 mm in-plane and 3-5 mm through-plane, with adequate slice coverage for whole brain imaging. The trade-off between spatial and temporal resolution may be tuned based on the clinical application, where temporal resolution may be sacrificed for finer spatial resolution or vice versa. The dynamic scan time is generally determined by the pathology of interest, with a minimum total scan time of 2 minutes.

Acceleration Methods

DSC-MRI has considerable competing pulse sequence demands to both sample fast (to characterize rapid signal changes) and with high resolution (to resolve anatomical structures). In order to attain adequate temporal and spatial resolution, some form of image acceleration is often required. This is typically achieved using k-space undersampling strategies, with corresponding image reconstruction methods to avoid the resulting undersampling artifacts. For example, in parallel imaging, additional information from receiver coils is exploited for image reconstruction, either in image-space (SENSitivity Encoding (SENSE)) or k-space (GeneRalized Autocalibrating Partial Parallel Acquisition (GRAPPA)). Other methods of undersampling include partial Fourier acquisitions, where high-frequency k-space is undersampled and reconstructed from the remaining k-space, or view-sharing methods, where the undersampled data is reconstructed from other dynamic time-frames. A sliding window view-sharing method, where k-space is split into interleaves and consecutive “windows” are combined for image reconstruction, has been used to improve DSC-MRI temporal resolution [15,17]. Keyhole view-sharing techniques have also been proposed for DSC-MRI [18], where center low-frequency k-space is acquired at each dynamic, while the high-frequency information is obtained from a reference image and is shared among the undersampled dynamic images. A promising new method of image acceleration is simultaneous multi-slice (SMS) acquisitions, which leverages multi-band RF pulses to acquire multiple slices simultaneously that are then separated using parallel imaging. SMS was recently shown to improve slice coverage in a gradient- and spin-echo DSC-MRI sequence; in principle, either spatial or temporal resolution could be improved using SMS [19].


This work was supported by NIH/NCI R01 CA158079, the Arizona Biomedical Research Commission (ADHS16-162414), and the Barrow Neurological Foundation.


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Proc. Intl. Soc. Mag. Reson. Med. 26 (2018)