The purpose of this article was to determine the usefulness of multiplanar and 3-dimensional (3D) reconstructions of computed tomographic (CT) data from scans performed for maternal indications for visualizing fetal anatomy and estimating gestational age.
Eighteen pregnant patients who had abdominopelvic CT scanning performed for maternal indications formed the study group. Two independent reviewers created multiplanar and 3D-reconstructed images of the fetus from these CT scans and analyzed them for fetal anatomy and gestational age. Fetal dose estimates were also obtained.
Computed tomographic fetal biometry generally agreed well with ultrasound estimates. Computed tomographic and ultrasound estimates were within 3 to 4 weeks of each other 95% of the time for the 2 reviewers. Pearson correlation coefficients were 0.989 for reviewer 1 and 0.985 for reviewer 2. Fetal anatomic survey revealed that it was easier to see bones and fluid-filled structures such as the stomach and urinary bladder than intracranial, intrathoracic, and intra-abdominal soft tissue structures. Estimated fetal dose was 28.5 (10.7) mGy using the Imaging Performance Assessment of CT Scanner calculator and 23.7 (7.7) mGy when taking maternal perimeter and fetal depth into account with the method of Angel et al.
It is technically feasible to produce clinically useful images of the fetus using standard multiplanar reconstructions and 3D algorithms already in place for CT scanning. As CT scans continue to be performed under certain circumstances, particularly the emergency department setting, evaluation of maternal CT scans for potentially useful information about the fetus such as gestational age and gross anatomic survey can be obtained at estimated fetal radiation doses much lower than the actionable level of 150 mGy.
From the *Department of Radiology, Changi General Hospital, Singapore, Singapore; and †Department of Radiology, University of Washington, Seattle, WA.
Received for publication February 1, 2011; accepted April 19, 2011.
Reprints: Manjiri Dighe, MD, DMRE, University of Washington Medical Center, 1959 NE Pacific St, BB 308, Seattle, WA 98195-7115 (e-mail: email@example.com).