A high-resolution MRI study of linear growth of the human fetal skull base

Abstract

The skull base, otherwise referred to as the basicranium or cranial base, plays a key role in the process of skull development, providing both support for the brain and an architectural component of the craniofacial complex. Consequently, the fetal skull base has been the focus of numerous studies employing various methods, including sectioning, plain radiography and CT. This paper investigates high-resolution (hr) MRI as an alternative method for looking at and quantifying the fetal skull base. The evaluation tests two basic hypotheses drawn from previous studies. These suggest that the anterior segment of the midline skull base grows more rapidly than the posterior segment and that the width of the posterior cranial fossa increases disproportionately in relation to its length. I imaged 42 formalin preserved human fetuses from museum collections with hrMRI. The T2-weighted image voxels were significantly smaller than those acquired with conventional clinical MRI. Landmarks of the fetal skull base were identified on reformatted axial and sagittal images. Bivariate plots revealed that the growth rate of the anterior skull base is almost twice that of the posterior skull base and that increases in the width of the posterior cranial fossa exceed those in its length. These findings confirm those of previous investigations and show that hrMRI offers a way forward in noninvasive quantification of fetal morphology.

Brain expansion and comparative prenatal ontogeny of the non-hominoid primate cranial base

“…Their method may have averaged-out the subtle but significant (slope=0.28) intervening changes of cranial base angle seen in the present investigation. Lastly, all the aforementioned studies employed radiographic techniques and so radio-translucent cartilaginous parts of the fetal basicranium may not have been properly imaged (see Jeffery, 2002b). With these technicalities in mind, it would appear the reported angulations are not comparable to those outlined in the present study.…”

Cranial base angulation and growth of the human fetal pharynx

“…All measurements were computed from landmark coordinates taken from midline hrMR images or parasagittal images close to the midline with the ImageJ software package (Wayne Rasband) and Align3D plugin (Nick Parker). Previous studies have shown that this is a precise and accurate method for studying fetal morphology (Jeffery, 2002;Jeffery and Spoor, 2004). It should be remembered, however, that previous studies also indicate that head orientation influences laryngeal position (Magriples and Laitman, 1987).…”

“…Consequently, the head region of each fetus was noninvasively scanned with high-resolution magnetic resonance imaging (hrMRI). This technique offers a number of advantageous over traditional methods such as sectioning or plain film radiography described in detail elsewhere (Jeffery, 2002). The major benefits include that hrMRI is noninvasive and can demonstrate soft as well as hard tissues, albeit indirectly by contrast against softer tissues (i.e., greater water or fat content).…”

“…The major benefits include that hrMRI is noninvasive and can demonstrate soft as well as hard tissues, albeit indirectly by contrast against softer tissues (i.e., greater water or fat content). Details of the imaging gradients, probes, and pulse sequence employed are also given in detail elsewhere (Jeffery, 1999(Jeffery, , 2002(Jeffery, , 2003Jeffery and Spoor, 2002). For each specimen, the hrMRI acquisition matrix was maintained at 256 ϫ 256.…”

Developmentally Regulated Expression of Msx1, Msx2 and Fgfs in the Developing Mouse Cranial Base

“…However, the anterior cranial base has a more active and more prolonged growth process that lasts to a very late growth stage. 4,5 This feature is a prerequisite for coordinated craniofacial development and growth. The basicranium also differs from other portions of the endochondral skeleton; to a great extent, the development and growth of the basicranium are under the influence of the brain, and the final shape and size of the basicranium follow that of the brain.…”