3D Super‐Resolution Motion‐Corrected MRI: Validation of Fetal Posterior Fossa Measurements

Abstract

Background and Purpose Current diagnosis of fetal posterior fossa anomalies by sonography and conventional MRI is limited by fetal position, motion, and by 2D, rather than 3D, representation. In this study, we aimed to validate the use of a novel MRI technique, 3D Super-Resolution Motion-Corrected MRI, to image the fetal posterior fossa. Methods From a database of pregnant women who received fetal MRIs at our institution, images of 49 normal fetal brains were reconstructed. Six measurements of the cerebellum, vermis, and pons were obtained for all cases on 2D conventional and 3D reconstructed MRI, and the agreement between the two methods was determined using concordance correlation coefficients. Concordance of axial and coronal measurements of the transcerebellar diameter was also assessed within each method. Results Between the two methods, the concordance of measurements was high for all six structures, (p<0.001), and was highest for larger structures such as the transcerebellar diameter. Within each method, agreement of axial and coronal measurements of the transcerebellar diameter was superior in 3D reconstructed MRI compared to 2D conventional MRI (p<0.001). Conclusions This comparison study validates the use of 3D Super-Resolution Motion-Corrected MRI for imaging the fetal posterior fossa, as this technique results in linear measurements that have high concordance with 2D conventional MRI measurements. Lengths of the transcerebellar diameter measured within a 3D reconstruction are more concordant between imaging planes, as they correct for fetal motion and orthogonal slice acquisition. This technique will facilitate further study of fetal abnormalities of the posterior fossa.

Biometric assessments of the posterior fossa by fetal MRI: A systematic review

“…A total of 804 studies were initially screened and 59 publications were included in the final systematic review 4,5,7,15‐69 (Figure 1) (Table S1). Separate publications with duplicated data from those included were assessed 51,70‐80 …”

“…The use of qualitative assessments alone of the PF in fetal MRI should no longer be common practice – qualitative assessments are not completely accurate, 7 and quantitative measurements can be combined with qualitative for a more thorough assessment 20,26,37,50,62,86 The development of centile calculators 54 should make the use of quantitative measures easier. We demonstrate here the variety of measurements currently used globally, without each adding to the diagnostic picture – consistency in use is needed to standardise the evaluation of images.…”

Model‐based super‐resolution reconstruction of T2 maps

“…In the frame of this study, motion correction schemes were not explored, but could be used to facilitate a better alignment of different orientations and improve the reconstruction. The area of motion correction and compensation has been well studied specifically for SR reconstruction in fetal imaging . Future work will aim to incorporate these strategies to further improve the robustness of the SR‐T 2 mapping.…”

3D MRI image super‐resolution for brain combining rigid and large diffeomorphic registration

“…The solution of X from a set of is ill‐posed [38, 41]. There is a family of estimators which are maximum likelihood.…”

“…Owing to the solid theoretical basis and easy implementation, registration‐based super‐resolution methods are still of great use in clinical practice. In previous similar works [40–42], LR data for super‐resolution basically come from the same time slot, especially for human brain. This restriction limits the use of super‐resolution in many cases.…”