Synthetic MRI for Clinical Neuroimaging: Results of the Magnetic Resonance Image Compilation (MAGiC) Prospective, Multicenter, Multireader Trial

L.N Tanenbaum,S.X Parameswaran,T.P Naidich,A.J Tsiouris,A Shankaranarayanan,M Goyen,P Quarterman,E.R Melhem,M.C Delano,A.N Johnson,A.S Field

doi:10.3174/ajnr.a5227

Abstract

Synthetic MR imaging enables reconstruction of various image contrasts from 1 scan, reducing scan times and potentially providing novel information. This study is the first large, prospective comparison of synthetic-versus-conventional MR imaging for routine neuroimaging. A prospective multireader, multicase noninferiority trial of 1526 images read by 7 blinded neuroradiologists was performed with prospectively acquired synthetic and conventional brain MR imaging case-control pairs from 109 subjects (mean, 53.0 ± 18.5 years of age; range, 19-89 years of age) with neuroimaging indications. Each case included conventional T1- and T2-weighted, T1 and T2 FLAIR, and STIR and/or proton density and synthetic reconstructions from multiple-dynamic multiple-echo imaging. Images were randomized and independently assessed for diagnostic quality, morphologic legibility, radiologic findings indicative of diagnosis, and artifacts. Clinical MR imaging studies revealed 46 healthy and 63 pathologic cases. Overall diagnostic quality of synthetic MR images was noninferior to conventional imaging on a 5-level Likert scale (P < .001; mean synthetic-conventional, -0.335 ± 0.352; Δ = 0.5; lower limit of the 95% CI, -0.402). Legibility of synthetic and conventional morphology agreed in >95%, except in the posterior limb of the internal capsule for T1, T1 FLAIR, and proton-density views (all, >80%). Synthetic T2 FLAIR had more pronounced artifacts, including +24.1% of cases with flow artifacts and +17.6% cases with white noise artifacts. Overall synthetic MR imaging quality was similar to that of conventional proton-density, STIR, and T1- and T2-weighted contrast views across neurologic conditions. While artifacts were more common in synthetic T2 FLAIR, these were readily recognizable and did not mimic pathology but could necessitate additional conventional T2 FLAIR to confirm the diagnosis.

Highlights

BACKGROUND AND PURPOSESynthetic MR imaging enables reconstruction of various image contrasts from 1 scan, reducing scan times and potentially providing novel information
While artifacts were more common in synthetic T2 FLAIR, these were readily recognizable and did not mimic pathology but could necessitate additional conventional T2 FLAIR to confirm the diagnosis
Synthetic MR imaging uses quantitative probing of multiple physical properties to reconstruct multiple contrasts from 1 scan

Summary

Methods

A prospective multireader, multicase noninferiority trial of 1526 images read by 7 blinded neuroradiologists was performed with prospectively acquired synthetic and conventional brain MR imaging case-control pairs from 109 subjects (mean, 53.0 Ϯ 18.5 years of age; range, 19 – 89 years of age) with neuroimaging indications. Each case included conventional T1- and T2-weighted, T1 and T2 FLAIR, and STIR and/or proton density and synthetic reconstructions from multiple-dynamic multiple-echo imaging. MDME uses a repeat version of the same gradientreversal process used to create a single gradient-echo to produce additional gradient-echoes after a single radiofrequency pulse This is known as multiple (or dual) echo gradient-echo, which is possible when complete loss of the transverse magnetization by T2* relaxation has not yet occurred. MDME parameters acquired in 1 scan are used in synthetic imaging to calculate pixel intensity, producing an appearance similar to that of conventional MR images with modifiable TE, TR, and TI.[5,11] synthetic (based on MDME) and conventional T1, T2, T1 FLAIR, T2 FLAIR, PD, and STIR contrast views were col-

Results

Discussion

Conclusion