Designing of Test Object for Intrauterine T2*-relaxometry of Fetal Brain

Study objective. Quantitative magnetic resonance T2* relaxometry is a promising method for assessing changes in the fetal brain associated with hypoxic conditions, which remain invisible with structural MRI and ultrasound. To obtain reproducible quantitative data, as well as to adjust scanning parameters and develop T2* mapping methods, it is necessary to create a test object with reference characteristics close to the values of the fetal brain. The aim of the study is to create a test object (phantom) for model experiments to adapt the T2* relaxometry method to in utero neuroresearch.

Materials and Methods. A comparative study was conducted of materials potentially suitable for imitating the T2* time relaxation (TR) of the fetal brain. The phantom construction was created using fused deposition modeling 3D printing technology. The resulting phantom was examined on a 3 T scanner, and scanned three times over the course of a month on a 1.5 T scanner to determine the stability of its characteristics and the reproducibility of the results. The study protocol included multiecho GRE sequences, acquiring 16 echo-images (n (TE) = 16) and single-shot multi-echo GRE EPI sequences, acquiring 5 echo-images (n (TE) = 5) of a single slice, with T2* calculations, with and without accounting for macroscopic magnetic field inhomogeneities, respectively.

Results. T2*-TR analysis of the test materials revealed that agarose gels at concentrations of 0.4 and 0.7% demonstrate T2* values close to those of the fetal brain: at n (TE) = 16, taking into account macroscopic inhomogeneities of the magnetic field, the calculated T2*-TR at 1.5 / 3 T were: 266 (4.4) / 246 (4,7) ms for the 0.4 % sample and 161 (3.5) / 163 (5) ms for the 0.7 % sample. A series of repeated experiments demonstrated high stability of the phantom's T2*-TR values for one month after its preparing (coefficient of variation 2.85 and 0.36 %, respectively).

Conclusion. An original phantom for fetal T2*-relaxometry has been created, applicable in the scientific and clinical practice of quantitative MRI. 

1. Paraskun K. A., Savelov A. A., Koros­ tyshevskaya A. M. Possibilities of the T2* relaxometry method in the diagnosis of hy­ poxia of the fetal brain. Translational Medicine. 2025;12(2):171-181. (In Russ.). DOI

2. Baadsgaard K., Hansen D. N., Peters D. A., Frøkjær J. B., Sinding M., Sørensen A. T2* weighted fetal MRI and the correlation with placental dysfunction. Placenta. 2023 Jan;131:90-97. DOI

3. Blazejewska A. I., Seshamani S., McKown S. K., Caucutt J. S., Dighe M., Gatenby C., Studholme C. 3D in utero quantification of T2* relaxation times in human fetal brain tissues for age optimized structural and functional MRI. Magn. Reson. Med. 2017 Sep;78(3):909-916. DOI

4. Crasto N., Kirubarajan A., Sussman D. An­ thropomorphic brain phantoms for use in MRI systems: a systematic review. MAGMA. 2022 Apr;35(2):277-289. DOI

5. Cromb D., Steinweg J., Aviles Verdera J., van Poppel M. P. M., Bonthrone A. F., Lloyd D. F. A., Pushparajah K., Simpson J., Razavi R., Rutherford M., Counsell S. J., Hutter J. T2*- Relaxometry MRI to Assess Third Trimester Placental and Fetal Brain Oxygenation and Placental Characteristics in Healthy Fetuses and Fetuses With Congenital Heart Disease. J. Magn. Reson. Imaging. 2025 Mar;61(3): 1246-1255. DOI

6. Hernando D., Vigen K. K., Shimakawa A., Reeder S. B. R*(2) mapping in the pre­ sence of macroscopic B₀ field variations. Magn. Reson. Med. 2012 Sep;68(3):830-40. DOI

7. Keenan K. E., Ainslie M., Barker A. J., Boss M. A., Cecil K. M., Charles C., Chenevert T. L., Clarke L., Evelhoch J. L., Finn P., Gemb­ ris D., Gunter J. L., Hill D. L. G., Jack C. R. Jr., Jackson E. F., Liu G., Russek S. E., Sharma S. D., Steckner M., Stupic K. F., Trzasko J. D., Yuan C., Zheng J. Quantitative magnetic resonance imaging phantoms: A review and the need for a system phantom. Magn. Reson Med. 2018 Jan;79(1):48-61. DOI

8. Lauridsen M. H., Uldbjerg N., Henriksen T. B., Petersen O. B., Stausbøl-Grøn B., Matthiesen N. B., Peters D. A., Ringgaard S., Hjortdal V. E. Cerebral Oxygenation Measurements by Magnetic Resonance Ima­ ging in Fetuses With and Without Heart Defects. Circ. Cardiovasc. Imaging. 2017 Nov;10(11): e006459. DOI

9. Manganaro L., Bernardo S., Antonelli A., Vinci V., Saldari M., Catalano C. Fetal MRI of the central nervous system: State-of-theart. Eur. J. Radiol. 2017 Aug;93:273-283. DOI

10. Peyvandi S., Xu D., Wang Y., Hogan W., Moon-Grady A., Barkovich A. J., Glenn O., McQuillen P., Liu J. Fetal Cerebral Oxygenation Is Impaired in Congenital Heart Disease and Shows Variable Response to Maternal Hyperoxia. J. Am. Heart. Assoc. 2021 Jan 5;10(1):e018777. DOI

11. Saleem S. N. Fetal MRI: An approach to prac­ tice: A review. J. Adv. Res. 2014 Sep;5(5): 507-23. DOI

12. Vasylechko S., Malamateniou C., Nunes R. G., Fox M., Allsop J., Rutherford M., Rueckert D., Hajnal J. V. T2* relaxometry of fetal brain at 1.5 Tesla using a motion tolerant method. Magn. Reson. Med. 2015 May;73(5):1795-802. DOI

13. Yusuff H., Zorn P. E., Giraudeau C., Wach B., Choquet P., Chatelin S., Dillenseger J. P. Development of a cost-effective 3D-printed MRI phantom for enhanced teaching of sys­ tem performance and image quality concepts. MAGMA. 2025 Jul;38(3):561-574. DOI