On the noise in "augmented T1‐weighted steady state magnetic resonance imaging". (14th December 2022)

• Record Type: Journal Article
• Authors: Leupold, Jochen; Kiselev, Valerij G.
• Is Part Of: NMR in biomedicine. Volume 36:Number 5(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-14
• Subjects: Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4886
• Languages: English
• ISSNs: 0952-3480

Abstract

Abstract: Recently, Ye and colleagues proposed a method for "augmented T1‐weighted imaging" (aT1 W). The key operation is a complex division of gradient‐echo (GRE) images obtained with different flip angles. Ye and colleagues provide an equation for the standard deviation of the obtained aT1 W signal. Here, we show that this equation leads to wrong values of the standard deviation of such an aT1 W signal. This is demonstrated by Monte Carlo simulations. The derivation of the equation provided by Ye and colleagues is shown to be erroneous. The error consists of a wrong handling of random variables and their standard deviations and of the wrong assumption of correlated noise in independently acquired GRE images. Instead, the probability distribution obtained with the aT1 W‐method should have been carefully analyzed, perhaps on the basis of previous literature on ratio distributions and their normal approximations. Abstract : We show fundamental errors in the noise analysis of the method for "augmented T1‐weighted imaging" from Ye and colleagues. The faultiness of their equation for the standard deviation of the signal obtained with their method is shown with Monte Carlo simulations. Also, errors in their derivation of said equation were identified.