ABSTRACT
BACKGROUND: In a country immersed in endless rounds of wars, retained metallic foreign bodies remain a significant dilemma in the daily practice of every Lebanese radiologist. When a shrapnel's hazard is of concern, the decision between performing or refusing a justified MRI exam is not always straightforward. In this small trial, we aimed to better understand the shrapnel's MRI safety by mimicking our daily practice. METHODS: Five shrapnel with an incremental increase in their long axis were put in an animal flesh and then introduced into a 3 T magnetic field. The behavior of each shrapnel was concretely assessed by performing before and after magnetic field exposure CT acquisitions. RESULTS: Translation along the z-axis ranged from 0.9 mm to 2.8 mm. Torque angle ranged between 2.8 and 54 degrees with an average of 15.62 degrees. CONCLUSIONS: Shrapnel's movements in the magnetic field are not negligible during the acute phase of injury where there is no reinforcing fibroblastic reaction and invite us to reconsider the MRI safety of these metallic foreign bodies. Standard radiographs may be sufficient, but a targeted CT scan may be of better value for a confident decision for assessment of shrapnel position near viscera and major vessels.
ABSTRACT
OBJECTIVE: The aim of this study is to assess the feasibility of visualizing the middle cerebral artery (MCA), establishing the normogram for MCA pulsatility index (PI) and peak systolic velocity (PSV), and calculating cerebroplacental ratio (CPR) at 12 to 14 weeks. STUDY DESIGN: Prospective cross-sectional study on 186 gravidas presenting for nuchal translucency (NT) assessment. Maternal body mass index (BMI), fetal crown-rump length (CRL), biparietal diameter (BPD), and NT were obtained. Color Doppler was utilized to visualize the MCA and measure PI, PSV, and umbilical artery PI. Normograms for MCA PI and PSV, and for CPR, were constructed. Regression analysis was used for the reference range of MCA PI and CPR according to CRL and BPD. Chi-square and t-test were utilized. p-Value of < 0.05 was considered significant. RESULTS: MCA was successfully visualized in 176/186 (94.6%), PI and PSV measured on 148/186 (79.6%) and 145/186 (78.0%), respectively, and CPR calculated in 133/186 (71.5%). There was no significant effect of BMI, CRL, or BPD on successful assessment of MCA or CPR. Normograms for MCA PI and CPR revealed no significant relation with CRL or BPD. CONCLUSION: MCA and CPR assessment is feasible at 12 to 14 weeks. A reference range for MCA Doppler indexes and CPR at 12 to 14 weeks has been established. This may prove helpful in the early evaluation of fetuses identified as at-risk for adverse neonatal outcome.
