Nancy E. Budorick

Second-trimester echogenic bowel and chromosomal abnormalities

OBJECTIVE Our objective was to examine the outcomes of pregnancies in which echogenic bowel was detected in the second trimester. STUDY DESIGN Twenty-two cases with a prospective diagnosis of echogenic bowel were reviewed. Karyotypic studies were performed in 19 cases, and 17 families had deoxyribonucleic acid-based risk assessment for cystic fibrosis. The echogenicity of the bowel was retrospectively reviewed and graded as mild or bright. RESULTS Five cases of trisomy 21 and one case of trisomy 18 were detected; four of these had other ultrasonographic abnormalities. Twenty-seven percent of fetuses with echogenic bowel were aneuploid. Risk was greatest for cases with brightly echogenic bowel. No cystic fibrosis mutations were detected. The diagnosis of echogenic bowel was reproducible. CONCLUSION Brightly echogenic bowel in the second trimester was found to be associated with a significant risk of fetal aneuploidy.

Three-dimensional ultrasound of the fetal spine

Objective To describe normal fetal spinal anatomy displayed by three-dimensional ultrasound and to determine whether three-dimensional ultrasound improves visualization of specific spinal defects. Methods Fetuses (n = 28) (16 normal and 12 abnormal) were examined on standard two- and three-dimensional sonographic equipment. Results In 15 of 16 normal fetuses, the spine was visualized at least from the upper thoracic area to the lower sacrum in a single three-dimensional image, and in 14 normal fetuses continuity of the ribs and spine was depicted. Neural tube defects were identified on both two- and three-dimensional ultrasounds; however, three-dimensional ultrasound displayed the level of the defect more accurately in three of the five cases. Scoliosis was recognized easily on a single three-dimensional rendered image, whereas several two-dimensional images were needed for the examiner mentally to reconstruct the scoliosis. Conclusion Three-dimensional ultrasound may become an important tool for imaging of the fetal spine. Additional studies are necessary to determine the efficacy and cost effectiveness of this technology. However, our preliminary data suggest that presentation of the spine as a continuous structure rather than in independent two-dimensional views makes visualization of the spatial relationship of the spinal anatomy and adjacent structures easier. The ability to review the volume data using techniques not available on two-dimensional ultrasound may enable physicians to determine the extent of neural tube defects with more accuracy.

Prevalence of aneuploidy with a cardiac intraventricular echogenic focus in an at-risk patient population

The objective of this study was to determine the relative risk for aneuploidy in the presence of a cardiac intraventricular echogenic focus in a patient population at high risk for aneuploidy. A retrospective cohort study was conducted on patients referred to a fetal diagnostic center who were undergoing amniocentesis. Records and second trimester sonograms were reviewed. Approximately 5100 comprehensive prenatal sonograms were obtained over a 2 year study period. Karyotyping by amniocentesis was done in 2412 women; 84 of the karyotypes (3.5%) were abnormal. Fetuses with no ultrasonographic findings suggestive of aneuploidy had a 1.4% (28 of 1940) prevalence of significant chromosomal abnormalities. An intraventricular echogenic focus was found in 149 of the women with karyotype analysis; 15 had an abnormal karyotype. Fetuses with intraventricular echogenic foci had a relative risk of 3.30 of aneuploidy when compared to fetuses without echogenic cardiac foci. The presence of an isolated intraventricular echogenic focus carried a relative risk of 4.08 compared to those fetuses in which ultrasonography had no finding associated with aneuploidy. In conclusion, these preliminary data indicate that presence of an intraventricular echogenic cardiac focus carries an increased risk of fetal aneuploidy.

Feasibility of Performing a Virtual Patient Examination Using Three-dimensional Ultrasonographic Data Acquired at Remote Locations

To evaluate the feasibility of performing three‐dimensional ultrasonographic studies that meet American Institute of Ultrasound in Medicine and American College of Radiology ultrasonographic examination guidelines with review off‐line and at remote locations.

The single umbilical artery in a high-risk patient population: what should be offered?

To determine whether fetal echocardiography is warranted in cases of single umbilical artery in a population at risk for aneuploidy.

Three-dimensional ultrasound: display modalities in obstetrics.

Three‐dimensional ultrasound (3DUS) has recently been introduced into clinical practice. Various techniques are available for display of the volume data. We review the importance of selecting the proper display option and rendering mode depending on the specific diagnostic question. Current display options include (1) arbitrary planar images similar to conventional two‐dimensional US images, (2) surface rendering with emphasis on soft tissues or skeletal detail, (3) stereo viewing using liquid crystal glasses or red/blue glasses, and (4) cine review of gated studies. Rotation of volume data also is important in understanding/comprehending patient anatomy. The range of rotation angles varies depending on the clinical setting. Also data storage requirements increase as the number of views increases.

Spontaneous improvement of intrathoracic masses diagnosed in utero.

The diagnosis and pregnancy outcome for 14 fetuses with sonographically detected chest masses were reviewed retrospectively. Six lesions became smaller or less apparent during gestation or resolved between antenatal and perinatal imaging studies; these included all three types of cystic adenomatoid malformation (CAM), as well as one case of pulmonary sequestration (PS). This information is extremely important in counseling patients in the second trimester who are considering termination of pregnancy. The poor prognosis traditionally assigned to type II and type III CAM needs changing to reflect the phenomenon of improvement with excellent long‐term outcomes. Sonographic indicators of poor outcome were polyhydramnios, hydrops or marked cardiac deviation.

Three-dimensional ultrasonography of the fetal distal lower extremity: normal and abnormal.

The objective of this study was to compare two‐dimensional and three‐dimensional ultrasonographic evaluation of fetal distal lower extremities. Data from two‐dimensional and three‐dimensional ultrasonographic examinations from 40 distal lower extremities in 33 fetuses from a predominantly high‐risk patient population were compared. Three‐dimensional ultrasonography routinely provided three orthogonal planes (coronal, sagittal, and axial) for distal lower extremity evaluation. Specific features of distal lower extremity evaluation were not different using two‐dimensional and three‐dimensional ultrasonography. Rotation of the rendered volume provided assistance in assessing all but one of 40 distal lower extremities. Time from image acquisition to assessment for two views (coronal and sagittal) was longer with three‐dimensional ultrasonography (8.2 min) than with two‐dimensional ultrasonography (3.2 min). Confidence in the diagnosis of abnormal distal lower extremities was slightly improved using three‐dimensional ultrasonography compared to two‐dimensional ultrasonography. Pregnancy management was assisted in three of the four cases with isolated limb anomalies. In conclusion, three‐dimensional ultrasonography improves the ability to evaluate the fetal distal lower extremity because of the multiplanar nature of volume assessment and the ability to rotate volume data sets. In addition, it provides assistance in counseling families, particularly for cases involving isolated limb anomalies.

Fetal Radiation Dose During Gestation Estimated on an Anthropomorphic Phantom for Three Generations of CT Scanners

OBJECTIVE The purpose of this study is to determine fetal dose during four different stages of pregnancy for both pulmonary CT angiogram and abdominal and pelvic CT examination on 4-, 16-, and 64-MDCT scanners measured in an anthropomorphic phantom simulating a pregnant patient. MATERIALS AND METHODS Pulmonary angiograms and abdominal and pelvic studies were performed on a phantom on 4-, 16-, and 64-MDCT scanners. Fetal positioning and mean fetal depth were determined using data from ultrasound examinations of a large cohort of patients. Scans were performed for early pregnancy and for 10, 18, and 36 weeks. Gestational age, fetal dose, and entrance skin exposure were measured. RESULTS When constant parameters were used for pulmonary CT angiograms, the fetal radiation dose was not significantly associated with gestational age. For abdominal examinations, the 64-MDCT scanner imparted a 20% higher dose during the third trimester than did the other scanners. When scanning parameters were kept constant between machines, gestational age and fetal dose were not significantly different. However, when the manufacturer-recommended protocols for pregnant patients were used, the dose was significantly higher in the third trimester on the 64-MDCT scanner. CONCLUSION The 64-MDCT scanner is the most dose-efficient machine when the fetus is outside the direct scan volume, as in the case of pulmonary angiograms. For abdominal examinations, the 64-MDCT scanner imparted the highest fetal dose. This finding is attributable to the increased tube current used to penetrate the larger amount of soft tissue in late pregnancy. Abdominal shielding may reduce fetal dose without affecting diagnostic ability.

Linear echoes in the fetal cisterna magna

Linear echoes are seen in the fetal cisterna magna, (CM) on obstetrical sonography. These echoes often are paired, joining as they descend toward the base of the posterior fossa. Histologic correlation suggests that these echoes are most consistent with dural folds, which likely represent the inferior attachment of the falx cerebelli. A prospective series of 322 prenatal studies was performed in which the sonographer was asked to look for the linear echoes in the cisterna magna and image them. Linear echoes were identified in 84% of all fetuses studied. Identification of these echoes was dependent on CM size, in that they were seen less commonly when the CM was less than 3 mm in diameter. However, their identification was not dependent on gestational age. In addition, 18 fetuses with Dandy Walker cyst or Dandy Walker variant were evaluated and in 16 linear echoes were not seen. We conclude that recognition of normal anatomy within the fetal brain, specifically the fetal CM, is helpful for identifying abnormalities in the size of the CM, whether large or small.