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Updated: Dec 19, 2025
Positron Emission Tomography Imaging for In Vivo Measuring of Myelin Content in the Lysolecithin Rat Model of Multiple Sclerosis
Published on: February 28, 2021
Inversion recovery zero echo time (IR-ZTE) imaging for direct myelin detection in human brain: a feasibility study
Hyungseok Jang1, Michael Carl2, Yajun Ma1
1Department of Radiology, University of California San Diego, San Diego, CA, USA.
Background:
Myelin alteration is closely associated with neurological diseases such as multiple sclerosis (MS). Unfortunately, due to myelin's extremely short T2* (~0.3 ms or shorter at 3T), it cannot be directly imaged with conventional MR imaging techniques. Recently, ultrashort echo time (UTE) imaging-based methods have been proposed for direct imaging of myelin. In this study, we explore the feasibility and efficacy of inversion recovery prepared zero echo time (IR-ZTE) imaging for direct volumetric imaging of myelin in white matter of the brain in vivo.
Methods:
In the proposed method, an adiabatic IR preparation pulse is used to suppress long T2 white matter signal, followed by dual echo ZTE imaging where the remaining long T2 components, including gray matter, are suppressed by dual echo subtraction. In the implementation of ZTE, the sampling strategy introduced in Water- and Fat-Suppressed Proton Projection MRI (WASPI) was incorporated to acquire the k-space data missing due to the radiofrequency (RF) transmit/receiver switching time. The IR-ZTE sequence was implemented on a 3T clinical MR system and evaluated using a myelin phantom composed of six different myelin concentrations (0% to 20%), a cadaveric human brain, four healthy volunteers, and seven MS patients.
Results:
In the myelin phantom experiment, the ZTE signal intensity showed high linearity to the myelin concentrations (R2=0.98). In the ex vivo and in vivo experiments, the IR-ZTE sequence provided high contrast volumetric imaging of myelin in human brains. The IR-ZTE sequence was able to detect demyelinated foci lesions in all MS patients.
Conclusions:
Adiabatic IR prepared dual echo ZTE imaging allows for direct, volumetric imaging of myelin in white matter of the brain in vivo.
Insights
Directly imaging brain myelin in vivo is now possible using inversion recovery prepared zero echo time (IR-ZTE) imaging. This new method effectively visualizes myelin and detects lesions in multiple sclerosis (MS) patients.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Radiology
Background:
- Myelin alterations are key indicators of neurological diseases like multiple sclerosis (MS).
- Conventional MRI techniques struggle to image myelin directly due to its extremely short T2* relaxation time.
- Ultrashort echo time (UTE) imaging methods offer potential for direct myelin visualization.
Purpose of the Study:
- To explore the feasibility and efficacy of inversion recovery prepared zero echo time (IR-ZTE) imaging.
- To achieve direct volumetric imaging of myelin in the brain's white matter in vivo.
- To assess IR-ZTE's capability in detecting demyelination in MS patients.
Main Methods:
- An adiabatic inversion recovery (IR) preparation pulse suppresses long T2 signals.
- Dual echo zero echo time (ZTE) imaging with echo subtraction minimizes remaining long T2 components.
- The Water- and Fat-Suppressed Proton Projection MRI (WASPI) sampling strategy was incorporated into the ZTE sequence.
- The IR-ZTE sequence was implemented on a 3T clinical MRI system and validated with phantoms, a cadaveric brain, healthy volunteers, and MS patients.
Main Results:
- ZTE signal intensity demonstrated high linearity with myelin concentrations in phantom experiments (R²=0.98).
- The IR-ZTE sequence achieved high-contrast volumetric myelin imaging in ex vivo and in vivo human brain samples.
- Demyelinated lesions were successfully detected in all MS patients using the IR-ZTE sequence.
Conclusions:
- Adiabatic IR prepared dual echo ZTE imaging enables direct, volumetric visualization of brain white matter myelin in vivo.
- This technique holds promise for improved diagnosis and monitoring of myelin-related neurological disorders.
- IR-ZTE imaging represents a significant advancement in neuroimaging for myelin assessment.
