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354: Qualitative performance of fetal MRI compared to ultrasound in cases of multiple fetal anomalies
www.AJOG.org
Clinical Obstetrics, Diabetes, Labor, Medical-Surgical-Disease, Physiology/Endocrinology, Prematurity
354 Qualitative performance of fetal MRI compared to ultrasound in cases of multiple fetal anomalies Christina Herrera1, Amber Samuel1, Sherelle Laifer-Narin1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Pregnancies complicated by multiple fetal anomalies are a common indication for fetal MRI as an adjunct to diagnostic ultrasound (US). This study investigated the diagnostic performance of fetal MRI when compared to US alone for the accurate characterization of fetuses with multiple anomalies. STUDY DESIGN: In a retrospective review from 2003 to 2011 at a single tertiary-care center, potential cases were identified if an MRI was performed following sonographic concern for multiple fetal anomalies. Inclusion required documented neonatal outcomes or postmortem assessments. Inter-study reliability between MRI and US was assessed by calculating kappa. Diagnostic accuracy of adjunct MRI compared to US alone was assessed using qualitative statistics. RESULTS: 121 MRIs were performed due to antenatal sonographic concern for multiple fetal anomalies, of which 60 cases possessed documented neonatal or pathologic outcomes. The kappa for MRI compared with US was 0.28. The correct diagnosis was secured in 47% of cases by US and 50% of cases by MRI (table). Nearly all inaccurate sonographic diagnoses were due to additional postnatal findings (48%). While MRI was most commonly inaccurate due to additional postnatal findings (27%), discrepant postnatal findings (3%), discrepant and additional postnatal findings (13%), and false-positive imaging findings (5%) also contributed significantly to study inaccuracies. CONCLUSION: Agreement is poor between MRI and US for the characterization of fetuses with multiple anomalies. For either imaging modality, complete and accurate diagnosis of fetal anomalies occurs in approximately half of cases, with the majority of inaccuracies due to incomplete antenatal characterizations.
Qualitative performance of fetal MRI compared to ultrasound
Poster Session II
mented neonatal outcomes or postmortem assessments. Cases were classified by diagnosis. Test performance characteristics were calculated for each group, from which the number needed secure an additional accurate diagnosis by MRI was determined. Applying the cost per MRI at the study center to this estimate, the cost per additional accurate diagnosis was calculated using qualitative statistics. RESULTS: 799 MRIs were performed, of which 406 subjects possessed documented neonatal or pathologic outcomes. 131 distinct postnatal diagnoses were secured, of which MRI identified 51 (12.6%) that ultrasound failed to correctly characterize. When the most common diagnosis groups were considered, meningomyelocele had the lowest cost per additional correct diagnosis by MRI, and ventriculomegaly the highest (table). Cost per additional accurate diagnosis for cases of CDH, omphalocele, vein of Galen malformation, and Dandy Walker complex could not be calculated, as there were no pregnancies where MRI was accurate but ultrasound alone was not. CONCLUSION: There is a variable cost per additional diagnosis correctly secured that should be weighed when considering a pregnancy for adjunct fetal MRI. Further study should be directed at assessing the global cost-benefit of fetal MRI, as well as considering the value of MRI for prognostication and surgical planning purposes.
Cost per additional accurate diagnosis of fetal MRI
356 Estimated fetal weight 10-19% is an independent risk factor for small for gestational age infants Amy Turitz1, Hayley Quant1, Nadav Schwartz1, Michal Elovitz1, Jamie Bastek1 1 University of Pennsylvania Perelman School of Medicine, Maternal and Child Health Research Program, Obstetrics and Gynecology, Philadelphia, PA
OBJECTIVE: ACOG states that estimated fetal weight (EFW) ⬍10%
355 Comparative effectiveness of fetal MRI for the improvement of diagnostic accuracy Amber Samuel1, Sherelle Laifer-Narin1, Christina Herrera1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Fetal MRI is performed as an adjunct to routine ultrasound with the intent of improving diagnostic accuracy, yet data are limited to substantiate benefit to this costly imaging modality. This study analyzed the billed cost of fetal MRI relative to diagnostic information gained for patients with antenatal diagnoses of a fetal anomaly and known postnatal outcomes. STUDY DESIGN: This was a retrospective case review of all fetal MRIs performed between 2003 and 2011 at a single tertiary-care center. Potential cases were identified if an MRI was performed following sonographic concern for a fetal anomaly. Inclusion required docu-
suggests neonatal growth restriction. Data are poor to suggest whether EFW 10-19% (EFW10-19) is also predictive of small for gestational age (SGA) neonates. Therefore, our objective was to determine whether EFW10-19 is associated with both subsequent EFW ⬍10% (EFW10), as well as SGA ⬍10% (SGA10) or ⬍5% (SGA5). STUDY DESIGN: Retrospective cohort study (1/2008-12/2011) of all women with singleton pregnancies 26-36 weeks and ⱖ1 growth scan at our institution. Ultrasound-based weight was determined by the Hadlock equation (1984) and percentile growth by the Alexander growth curve. The association between EFW10-19 and subsequent EFW10, SGA10, and SGA5 were compared using chi square analyses. Odds of growth restriction with EFW10-19 were calculated using MVLR to control for confounders. Sensitivity (SN), specificity (SP), positive and negative predictive values (PPV, NPV), and areas under the receiver-operator curve (AUC) of EFW10-19 and EFW10 to predict SGA10 and SGA5 were calculated. RESULTS: The prevalence of EFW10 was 8.0%, EFW10-19 was 12.3%, SGA10 was 17.6%, and SGA5 was 8.3% (N⫽10,642). EFW10-19 on first growth scan (US1) was associated with a 4.4-fold increase (95%CI 1.7-11.5) in the risk of EFW10 on subsequent ultrasound, an 8.9-fold increase (95%CI 7.36-10.77) in SGA10, and a 7.5-fold increase (95%CI 5.9-9.8) in SGA5. EFW10 alone on US1 missed nearly 70% of SGA10 and 56.5% of SGA5 infants. EFW10-19 identified an additional 40.0% of SGA10 and 42.5% of SGA5 neonates. Test characteristics of EFW10-19 were not as strong as EFW10 (Table). AUCs to predict SGA were significantly greater for EFW10-19 than EFW10 but were only fair (10: 0.66 vs. 0.50, p⬍0.001; 5: 0.66 vs. 0.51, p⬍0.001).
Supplement to JANUARY 2013 American Journal of Obstetrics & Gynecology
S157
Clinical Obstetrics, Diabetes, Labor, Medical-Surgical-Disease, Physiology/Endocrinology, Prematurity
354 Qualitative performance of fetal MRI compared to ultrasound in cases of multiple fetal anomalies Christina Herrera1, Amber Samuel1, Sherelle Laifer-Narin1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Pregnancies complicated by multiple fetal anomalies are a common indication for fetal MRI as an adjunct to diagnostic ultrasound (US). This study investigated the diagnostic performance of fetal MRI when compared to US alone for the accurate characterization of fetuses with multiple anomalies. STUDY DESIGN: In a retrospective review from 2003 to 2011 at a single tertiary-care center, potential cases were identified if an MRI was performed following sonographic concern for multiple fetal anomalies. Inclusion required documented neonatal outcomes or postmortem assessments. Inter-study reliability between MRI and US was assessed by calculating kappa. Diagnostic accuracy of adjunct MRI compared to US alone was assessed using qualitative statistics. RESULTS: 121 MRIs were performed due to antenatal sonographic concern for multiple fetal anomalies, of which 60 cases possessed documented neonatal or pathologic outcomes. The kappa for MRI compared with US was 0.28. The correct diagnosis was secured in 47% of cases by US and 50% of cases by MRI (table). Nearly all inaccurate sonographic diagnoses were due to additional postnatal findings (48%). While MRI was most commonly inaccurate due to additional postnatal findings (27%), discrepant postnatal findings (3%), discrepant and additional postnatal findings (13%), and false-positive imaging findings (5%) also contributed significantly to study inaccuracies. CONCLUSION: Agreement is poor between MRI and US for the characterization of fetuses with multiple anomalies. For either imaging modality, complete and accurate diagnosis of fetal anomalies occurs in approximately half of cases, with the majority of inaccuracies due to incomplete antenatal characterizations.
Qualitative performance of fetal MRI compared to ultrasound
Poster Session II
mented neonatal outcomes or postmortem assessments. Cases were classified by diagnosis. Test performance characteristics were calculated for each group, from which the number needed secure an additional accurate diagnosis by MRI was determined. Applying the cost per MRI at the study center to this estimate, the cost per additional accurate diagnosis was calculated using qualitative statistics. RESULTS: 799 MRIs were performed, of which 406 subjects possessed documented neonatal or pathologic outcomes. 131 distinct postnatal diagnoses were secured, of which MRI identified 51 (12.6%) that ultrasound failed to correctly characterize. When the most common diagnosis groups were considered, meningomyelocele had the lowest cost per additional correct diagnosis by MRI, and ventriculomegaly the highest (table). Cost per additional accurate diagnosis for cases of CDH, omphalocele, vein of Galen malformation, and Dandy Walker complex could not be calculated, as there were no pregnancies where MRI was accurate but ultrasound alone was not. CONCLUSION: There is a variable cost per additional diagnosis correctly secured that should be weighed when considering a pregnancy for adjunct fetal MRI. Further study should be directed at assessing the global cost-benefit of fetal MRI, as well as considering the value of MRI for prognostication and surgical planning purposes.
Cost per additional accurate diagnosis of fetal MRI
356 Estimated fetal weight 10-19% is an independent risk factor for small for gestational age infants Amy Turitz1, Hayley Quant1, Nadav Schwartz1, Michal Elovitz1, Jamie Bastek1 1 University of Pennsylvania Perelman School of Medicine, Maternal and Child Health Research Program, Obstetrics and Gynecology, Philadelphia, PA
OBJECTIVE: ACOG states that estimated fetal weight (EFW) ⬍10%
355 Comparative effectiveness of fetal MRI for the improvement of diagnostic accuracy Amber Samuel1, Sherelle Laifer-Narin1, Christina Herrera1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Fetal MRI is performed as an adjunct to routine ultrasound with the intent of improving diagnostic accuracy, yet data are limited to substantiate benefit to this costly imaging modality. This study analyzed the billed cost of fetal MRI relative to diagnostic information gained for patients with antenatal diagnoses of a fetal anomaly and known postnatal outcomes. STUDY DESIGN: This was a retrospective case review of all fetal MRIs performed between 2003 and 2011 at a single tertiary-care center. Potential cases were identified if an MRI was performed following sonographic concern for a fetal anomaly. Inclusion required docu-
suggests neonatal growth restriction. Data are poor to suggest whether EFW 10-19% (EFW10-19) is also predictive of small for gestational age (SGA) neonates. Therefore, our objective was to determine whether EFW10-19 is associated with both subsequent EFW ⬍10% (EFW10), as well as SGA ⬍10% (SGA10) or ⬍5% (SGA5). STUDY DESIGN: Retrospective cohort study (1/2008-12/2011) of all women with singleton pregnancies 26-36 weeks and ⱖ1 growth scan at our institution. Ultrasound-based weight was determined by the Hadlock equation (1984) and percentile growth by the Alexander growth curve. The association between EFW10-19 and subsequent EFW10, SGA10, and SGA5 were compared using chi square analyses. Odds of growth restriction with EFW10-19 were calculated using MVLR to control for confounders. Sensitivity (SN), specificity (SP), positive and negative predictive values (PPV, NPV), and areas under the receiver-operator curve (AUC) of EFW10-19 and EFW10 to predict SGA10 and SGA5 were calculated. RESULTS: The prevalence of EFW10 was 8.0%, EFW10-19 was 12.3%, SGA10 was 17.6%, and SGA5 was 8.3% (N⫽10,642). EFW10-19 on first growth scan (US1) was associated with a 4.4-fold increase (95%CI 1.7-11.5) in the risk of EFW10 on subsequent ultrasound, an 8.9-fold increase (95%CI 7.36-10.77) in SGA10, and a 7.5-fold increase (95%CI 5.9-9.8) in SGA5. EFW10 alone on US1 missed nearly 70% of SGA10 and 56.5% of SGA5 infants. EFW10-19 identified an additional 40.0% of SGA10 and 42.5% of SGA5 neonates. Test characteristics of EFW10-19 were not as strong as EFW10 (Table). AUCs to predict SGA were significantly greater for EFW10-19 than EFW10 but were only fair (10: 0.66 vs. 0.50, p⬍0.001; 5: 0.66 vs. 0.51, p⬍0.001).
Supplement to JANUARY 2013 American Journal of Obstetrics & Gynecology
S157