IMAGING Quality control of an image-scoring method for nuchal translucency ultrasonography Nicolas Fries, MD; Marc Althuser, MD; Marianne Fontanges, MD; Claude Talmant, MD; Pierre S. Jouk, PhD; Malka Tindel, SM; Michel Duyme, PhD OBJECTIVE: The objective of the study was to describe a new image- scoring method (NISM) for the measurement of nuchal translucency and crown-rump length on ultrasound scans and to establish interre- viewer reliability. STUDY DESIGN: This NISM was based on 8 criteria on a scale of 4 levels (1-4) established on clearly defined ultrasound reference marks. Ten reviewers assessed the same images of 30 fetuses. After a short training period, the same images and those of 30 new fetuses were scored by these 10 reviewers. RESULTS: The differences in scores among the 10 reviewers were sig- nificant for 4 of 45 pairwise comparisons before training, but no pair- wise comparison was significant after training. Interreviewer variance was significantly lower after training (P = .045). The intraclass corre- lations before and after training were 0.75 and 0.82. For each criterion, the scores were dichotomized into 2 categories (1-2 vs 3-4). Kappa values for each criterion were substantial (0.61 to 0.80) or even almost perfect (0.81 to 1.00). CONCLUSION: This NISM was highly reliable for the total scores and for each criterion evaluating the image of nuchal translucency and crown-rump length and provides a relevant quality control tool for ul- trasound operators. Key words: Down’s syndrome, ongoing audit, 11 to 14 week scan, ultrasound screening Cite this article as: Fries N, Althuser M, Fontanges M, et al. Quality control of an image-scoring method for nuchal translucency ultrasonography. Am J Obstet Gynecol 2007;196:272.e1-272.e5. M easurements of nuchal translu- cency (NT) and crown-rump length (CRL) during the first trimester of pregnancy are already used effi- ciently to detect chromosomal abnor- malities. 1 This method can detect be- tween 70% and 90% of Down’s syndrome cases, with a false-positive rate of 5%, depending on whether this risk estimation is combined solely with the risk because of maternal age or also with first- or second-trimester mater- nal serum markers. 2-5 However, the performance of this technique depends largely on the preci- sion of ultrasound measurement. Since 1997, the Royal College of Obstetricians and Gynaecologists has recommended the use of quality control when measur- ing nuchal translucency. 6 Nicolaides and the Fetal Medicine Foundation 7 (FMF) defined methodological criteria for mea- suring NT. They set up a clinical audit based on analyzing 10 images selected by the operator and also on all the NT and CRL measurements to determine whether the median score of each oper- ator was close to the reference median. Working on the criteria established by the FMF, new image-scoring methods (ISMs) were then defined. Herman et al 8 developed an ISM based on 6 criteria for analyzing ultrasound images for NT measurement. A total score for each im- age could be obtained by adding together the total scores of 3 major criteria (scored 0 or 2) and 3 minor criteria (scored 0 or 1). This ISM scores the NT images but does not take into account the CRL. A high level of interreviewer re- liability between the scores obtained by 3 reviewers from the same hospital was ob- served. However, the agreement of this ISM was evaluated on only a 4-level cat- egorization of the total score. Wojdemann et al 9 developed an ISM based on whether each of the 4 criteria was acceptable. They found that the re- producibility of the ISM was low and concluded that such methods could not be recommended for ongoing quality control. Given that there has been no real agreement on these ISMs, further studies are necessary. Notably, the need to ana- lyze CRL images and study these evalua- tions criterion by criterion to improve clinical practice and reviewer training has become obvious. The aims of this study were therefore: (1) to describe a new ISM for analyzing the NT and CRL images on ultrasound scans; (2) to study interreviewer reliabil- ity for this ISM on the total score and the scores of each criterion before and after a short training session; and (3) to esti- Collège Français d’Echographie Foetale (Drs Fries, Althuser, Fontanges, and Talmant) Paris, France; Centre Pluridisciplinaire de Diagnostic Prénatal (Dr Jouk), Centre Hospitalier Universitaire de Grenoble, Grenoble, France; Centre National de la Recherche Scientifique (Ms Tindel and Dr Duyme), Laboratoire de Biostatistique Université Montpellier Nimes, Montpellier, France. Received May 13, 2006; revised July 23, 2006; accepted Oct. 11, 2006. Reprints: Dr N. Fries, Les Tonnelles, 131 Avenue de Lodève, Montpellier, 34080, France; fries@cfef.org. 0002-9378/$32.00 © 2007 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2006.10.866 Research www. AJOG.org 272.e1 American Journal of Obstetrics & Gynecology MARCH 2007