Multi-vendor reliability of arterial spin labeling perfusion MRI using a near-identical sequence: Implications for multi-center studies

Abstract

Introduction: A main obstacle that impedes standardized clinical and research applications of arterial spin labeling (ASL), is the substantial differences between the commercial implementations of ASL from major MRI vendors. In this study, we compare a single identical 2D gradient-echo EPI pseudo-continuous ASL (PCASL) sequence implemented on 3T scanners from three vendors (General Electric Healthcare, Philips Healthcare and Siemens Healthcare) within the same center and with the same subjects. Material and methods: Fourteen healthy volunteers (50% male, age 26.4 ± 4.7 years) were scanned twice on each scanner in an interleaved manner within 3 h. Because of differences in gradient and coil specifications, two separate studies were performed with slightly different sequence parameters, with one scanner used across both studies for comparison. Reproducibility was evaluated by means of quantitative cerebral blood flow (CBF) agreement and inter-session variation, both on a region-of-interest (ROI) and voxel level. In addition, a qualitative similarity comparison of the CBF maps was performed by three experienced neuro-radiologists. Results: There were no CBF differences between vendors in study 1 (p N 0.1), but there were CBF differences of 2-19% between vendors in study 2 (p b 0.001 in most gray matter ROIs) and 10-22% difference in CBF values obtained with the same vendor between studies (p b 0.001 in most gray matter ROIs). The inter-vendor inter-session variation was not significantly larger than the intra-vendor variation in all (p N 0.1) but one of the ROIs (p b 0.001). Conclusion: This study demonstrates the possibility to acquire comparable cerebral CBF maps on scanners of different vendors. Small differences in sequence parameters can have a larger effect on the reproducibility of ASL than hardware or software differences between vendors. These results suggest that researchers should strive to employ identical labeling and readout strategies in multi-center ASL studies.

Test-retest reliability of cerebral blood flow in healthy individuals using arterial spin labeling: Findings from the EMBARC study

“…Moreover, the inter scanner reliability was also good at rest (ICC = 0.69) and during motor activation (ICC = 0.61) [33]. Only one small study explored more three 3 Tesla MRI platforms – GE, Philip and Siemens [31]. The authors compared similar pCASL acquisition parameters within the same day in two parallel studies, one with eleven subjects, and a second with fourteen subjects (eleven subjects participated in both studies).…”

“…However, the study did not examine reliability across the three platforms as one unique group, but rather as two parallel investigations. Moreover, most other ASL reliability studies investigated CBF stability within a few hours [20,25,30,31] or within several days [20,24,25,29]. Overall, these studies reported high reliability for scans completed within the same day, and a decrease in reliability after several days.…”

“…Only two studies from the same group explored ASL reliability across two different scanner platforms, finding good reliability both at rest and during finger tapping in the motor cortex [33], and good reliability in mean global gray matter CBF at rest [34]. To date, only one study investigated ASL reliability across scanners of three different platforms [31], finding good reproducibility for most regions of interest studied, except posterior cingulate cortex, and concluding that differences in sequence parameters have greater impact on ASL reproducibility compared to differences in hardware/software across MRI scanner platforms. However, the study did not examine reliability across the three platforms as one unique group, but rather as two parallel investigations.…”

Arterial Spin Labeling Perfusion of the Brain: Emerging Clinical Applications

“…Since then, numerous other studies have been published, comparing different sequences on a single manufacturer (138), near identical sequences on different manufacturers (139), and combinations in between. The general results confirm the same level of reproducibility, within and between subject standard deviations as originally found in the QUASAR reproducibility study (137).…”

Comparison of Quantitative Cerebral Blood Flow Measurements Performed by Bookend Dynamic Susceptibility Contrast and Arterial Spin-Labeling MRI in Relapsing-Remitting Multiple Sclerosis

“…However, it should be noted that this is partly technical because we excluded the non-zero values which would otherwise artificially elevate the correlation coefficient without accurately reflecting meaningful CBF comparisons. Repeatability is a known problem with all perfusion techniques including pCASL 45 , Repeatability of H 2 [ 15 O] PET CBF has been recorded at 8% in WM and a 10% in GM over a two day interval between measurements 46 . Such variations are unlikely to have accounted for correlation differences given that pCASL and Bookend image acquisition were performed minutes apart Variability can be mitigated to some extent for pCASL using post-processing techniques that eliminate spurious voxels caused by small amounts of head motion 27 .…”