Arterial Spin-Labeling in Routine Clinical Practice, Part 1: Technique and Artifacts

Abstract

SUMMARY:The routine use of arterial spin-labeling (ASL) in a clinical population has led to the depiction of diverse brain pathologic features. Unique challenges in the acquisition, postprocessing, and analysis of cerebral blood flow (CBF) maps are encountered in such a population, and high-quality ASL CBF maps can be generated consistently with attention to quality control and with the use of a dedicated postprocessing pipeline. Familiarity with commonly encountered artifacts can help avoid pitfalls in the interpretation of CBF maps. The purpose of this review was to describe our experience with a heterogeneous collection of ASL perfusion cases with an emphasis on methodology and common artifacts encountered with the technique. In a period of 1 year, more than 3000 pulsed ASL cases were performed as a component of routine clinical brain MR evaluation at both 1.5 and 3T. These ASL studies were analyzed with respect to overall image quality and patterns of perfusion on final gray-scale DICOM images and color Joint Photographic Experts Group (JPEG) CBF maps, and common artifacts and their impact on final image quality were categorized.

Arterial Spin-Labeling in Routine Clinical Practice, Part 2: Hypoperfusion Patterns

“…Knowledge of artifacts and physical parameters of the perfusion sequence permits accurate analysis of the cause of locally diminished signal intensity, and these are discussed in detail in Part 1 of this series. 1 The inversion label applied to inflowing spins in the neck, for example, decays on the order of seconds during image acquisition and results in an overall decrease in signal intensity on the more superior sections. In patients with delayed MTT, this effect is particularly pronounced (though, paradoxically, high signal intensity may also be observed, as discussed in later sections).…”

Common data elements in radiologic imaging of traumatic brain injury

“…More recently, CTP has been used in TBI studies (63,64), but there are few papers using perfusion-weighted MRI (65). MRI arterial spin labeling is finding its place as an alternate approach to image perfusion without the use of a contrast agent (66)(67)(68)(69). Numerous studies have been published on patients with mild TBI imaged with technetium-99m-labeled hexamethylpropyleneamine oxime ( 99m Tc-HMPAO) SPECT, from the acute to chronic stage (60,(70)(71)(72)(73)(74)(75)(76)(77)(78).…”

Does MR Perfusion Imaging Impact Management Decisions for Patients with Brain Tumors? A Prospective Study

“…35 This method includes single subtraction with thin section TI 1 periodic saturation 36 with a flow-sensitive alternating inversion recovery 37,38 ; postprocessing involves subtraction of tag/control image pairs, motion correction, segmentation of the anatomic T1-weighted image, and voxelwise computation of CBF maps, which are then colored by using a standard scale and the resultant JPEG of the map sent to the PACS. 35 The DSC images were acquired with a gradient echo-planar imaging sequence during the second pass of a standard-dose (0.1 mmol per kg) bolus of gadopentetate dimeglumine (Magnevist; Bayer Schering Pharma, Berlin, Germany). Eleven to 16 axial sections were positioned to cover the tumor on the basis of the T2-weighted and FLAIR images.…”