Fetal MRI: incidental findings in the mother

Incidence of New, Nonphysiologic Maternal Findings on Fetal Magnetic Resonance Imaging

OBJECTIVE

 Fetal magnetic resonance imaging (MRI) is increasingly used for evaluation of fetal anomalies, and rates of incidental maternal findings are not well characterized. Our objective was to evaluate the rate of incidental maternal findings at the time of antenatal MRI performed for fetal indications.

STUDY DESIGN

 This was a retrospective cohort study that included all fetal MRIs performed between 2018 and 2023 at a single tertiary care institution with a multidisciplinary fetal diagnosis and treatment center. The electronic medical record was reviewed to identify all documented maternal findings and any new, nonphysiologic maternal findings. The latter was defined as previously unknown abnormalities of maternal structures unrelated to normal physiology.

RESULTS

 Our study included 834 imaging events, performed at an average gestational age of 23 weeks. The most common indication for imaging was fetal anomaly (81.1%). The most common imaging type was fetal brain MRI (81.4%). Overall, 16.2% reported a maternal finding and 7% reported a new, nonphysiologic finding. The most common new, nonphysiologic findings were renal cysts (n = 11), liver cysts (n = 6), and gallstones or gallbladder sludge (n = 5). Compared with imaging events that included a fetal brain MRI, imaging events that included a fetal body MRI had a significantly higher rate of any maternal findings (53.0 vs. 10.4%, p < 0.001) and new, nonphysiologic maternal findings (26.9 vs. 3.7%, p < 0.001).

CONCLUSION

 Our results suggest that the risk of identifying new, nonphysiologic maternal findings on fetal MRI is low. The rate of any maternal and new, nonphysiologic maternal findings may differ by fetal MRI type due to differences in imaging depth and extent of radiology subspecialist review. These data should be incorporated into pretest counseling for patients planning to have fetal MRI.

KEY POINTS

· The rate of incidental maternal findings on fetal MRI was 7%-lower than previously reported.. · Incidental maternal findings were more common on fetal body versus brain MRI.. · Maternal BMI did not impact incidence of new, nonphysiologic maternal findings.. · Our results could inform pretest counseling and consent discussions around fetal MRI..

Incidental maternal findings on fetal MRI

AIM

To evaluate the type and frequency of maternal findings incidentally identified during fetal magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A retrospective single-centre study was undertaken which included all consecutive fetal MRI studies performed between July 2017 and May 2021 at a tertiary institution. Two fellowship-trained radiologists reviewed the studies independently to determine the type and frequency of incidental maternal findings of both no clinical significance (requiring no further follow-up) and of clinical significance (requiring further follow-up, work-up, and/or management). Differences in acquisition were resolved by two-reader consensus. Non-diagnostic MRI examinations or abdominal MRI examinations indicated for maternal complications were excluded from review.

RESULTS

A total of 455 consecutive fetal MRI examinations performed in 429 women were included. Mean age was 30 years (SD 5.5 years). At least one incidental maternal finding was identified in 58% (265/455) of studies. Umbilical hernias (35%), maternal hydronephrosis (19%), and maternal hydro-ureter (15%) were the most common. Only two studies (0.5%) showed clinically significant incidental maternal findings (pancreatic pseudocyst and ovarian cyst).

CONCLUSIONS

Incidental maternal findings are common on fetal MRI but rarely require further follow-up, work-up, and/or management.

Maternal and fetal incidental findings on antenatal magnetic resonance imaging

BACKGROUND

Magnetic resonance imaging (MRI) examinations are increasingly used in antenatal clinical practice. Incidental findings are a recognized association with imaging and although in some circumstances their identification can alter management, they are often associated with increased anxiety, for both patient and clinician, as well as increased health care costs.

OBJECTIVE

This study aimed to evaluate the incidence of unexpected findings in both the mother and fetus during antenatal MRI examinations.

MATERIALS AND METHODS

A retrospective study was undertaken over a five-year period at St.. Thomas' Hospital in London. Maternal incidental findings were recorded from all clinical reports of all fetal MRIs performed (for clinical reasons and in healthy volunteers) during this period. Fetal incidental findings were recorded only in cases where women with uncomplicated pregnancies were participating as healthy volunteers.

RESULTS

A total of 2,569 MRIs were included; 17% of women had maternal incidental findings. Of these, 1,099 were women with uncomplicated pregnancies who undertook research MRIs as healthy volunteers; fetal incidental findings were identified in 12.3%.

CONCLUSION

Incidental findings are a common occurrence in antenatal MRI. Consideration should be given to counseling women appropriately before imaging and ensuring that robust local protocols are in place for follow-up and further management of such cases.

Lumbar Intervertebral Disc Degeneration as a Common Incidental Finding in Young Pregnant Women as Observed on Prenatal Magnetic Resonance Imaging

Background: Obstetric imaging, subserving fetal evaluation, may yield incidental maternal findings. Based on prenatal magnetic resonance (MR) imaging, this study aims to investigate incidental intervertebral disc degeneration and displacement in young, pregnant women. Methods: This retrospective study included the sagittal 1.5 Tesla, T2-weighted lumbar spine images of 943 pregnant Central Europeans (age range, 18-47 years), who initially had undergone MR imaging because of sonographically suspected fetal abnormalities. Qualitatively, 4715 lumbar intervertebral discs were evaluated for degeneration using a modified Pfirrmann MR classification (nondegenerated, low-grade, moderate, and high-grade degeneration), as well as for displacement. In addition to descriptive statistics, an ordinal regression analysis was performed to analyze the relationship between degeneration and the women's age, and body weight. Results: With regard to the highest degree of degeneration in each woman, 578 (61.3%) showed low-grade, 211 (22.4%) moderate, and 154 (16.3%) high-grade degeneration, and no woman had entirely nondegenerated discs. For the span from 18 to 47 years of age, moderate and high-grade degeneration increased from 6.7% to 36.7% and from 13.3% to 22.4%, respectively. Of 943 women, 57 (6%) had disc displacements, of which 97% were in conjunction with high-grade degeneration. There was a statistically significant relationship (p < 0.001) between degeneration and age, and between degeneration and body weight. Conclusions: In young pregnant women, lumbar intervertebral disc degeneration is a ubiquitous, incidental finding, increasing from the late second decade of life onward, which may be part of physiological aging, as opposed to a small percentage of incidental disc displacements.