Erika Rubesova MD, Presenter: Nothing to Disclose

Chardonnay Julia Vance, Abstract Co-Author: Nothing to Disclose

Sabine Bammer, Abstract Co-Author: Nothing to Disclose

Sanjeev Dutta, Abstract Co-Author: Nothing to Disclose

Richard Allen Barth MD, Abstract Co-Author: Nothing to Disclose

Fetal MRI has significantly improved detection and characterization in utero of abdominal congenital anomalies. However, some gastro-intestinal pathology is still difficult to diagnose since normal volumes of the fetal colon over a range of gestational ages (GA) have not yet been established. The fetal colon is easily recognized on T1 weighted images because meconium (consisting mainly of sterols, fatty acids, amino acids, organic acids and ketone bodies) has a hyperintense signal compared to the surrounding fetal tissues. The purpose of this study is to provide normal colon volumes for different GA.

This retrospective and prospective pilot study was performed on 64 fetuses which exhibited no gastrointestinal anomalies. Patients were scanned on a 1.5 Tesla GE Signa magnet. Axial, sagital and coronal T1 weighted FGRE images were acquired with a TR/TE of 165/2.6ms, 90° flip angle, 384x192 matrix size, 5mm slice thickness, 38cm FOV, for a total acquisition time of 51 seconds. The volume of the colon was selected by two different investigators by outlining the hyperintense meconium signal slice by slice on a GE Advantage Workstation 4.1: colon volumes were calculated by the software. Colon volumes are reported relative to the GA and to the abdominal diameters, and used for a normative curve. A Bland and Altman inter-observer and intra-observer study was performed.

From 64 scanned fetuses, 10 were excluded because of movement artifacts in the images. Normal colon volumes increased exponentially with GA and abdominal diameter. The range of colon volumes between 22 and 37 weeks was 1.9 to 51 mL. The variation of volumes was greater at advanced GA. There was good inter-observer and intra-observer correlation.

The results of this pilot study suggest there is an exponential growth curve of the fetal colon in utero, and provide preliminary volumetric measurements of the normal fetal colon between 22 and 37 weeks of GA.

This 3D MRI study provides normal biometric measurements of the fetal colon to assist in evaluation of intestinal pathology.

Rubesova, E, Vance, C, Bammer, S, Dutta, S, Barth, R, Three-dimensional MR Imaging Measurements of the Normal Fetal Colon Volume.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4429555.html