Four Steps in Diagnosing Complete Agenesis of the Corpus Callosum in Prenatal Life.

PURPOSE: Among congenital brain anomalies, complete agenesis of the corpus callosum (cACC) including cases of callosal hypoplasia has a prevalence of 1.8 per 10 000 in the general population. It is also one of the most challenging brain anomalies to detect during the mid-trimester ultrasound scan. Standard axial planes do not provide enough information to make the definitive diagnosis of cACC. MATERIALS AND METHODS: From our library of images and ultrasound reports, we reviewed our most recent cases of complete agenesis of the corpus callosum in the fetus at the mid-trimester scan. In our analysis we included only cases that were confirmed postnatally or by autopsy. Exams were performed between January 2010 and June 2012. All of the patients were scanned transabdominally by means of 2 D and static 3 D. From the 2 D and 3 D images we identified 4 anatomical views that consistently gave us enough information to identify cACC: axial biparietal transthalamic view (AX1); axial biparietal falx view (AX2); coronal transthalamic view (COR); mid-sagittal view (SAG). RESULTS: From our library 30 cases were selected with confirmed cACC postnatally or in autopsy findings. The mean gestational age at the time of referral to our center was 20.7 weeks (range 19 - 23 weeks). In all analyzed cases sufficient 2 D images were found and in 93.3 % of them informative 3 D volumes were also available for off-line review. We identified the following patterns of cACC at the mid-trimester scan: A- normal size of 3 rd ventricle + normal size of the lateral ventricles or mild ventriculomegaly; B1- dilated 3 rd ventricle + normal size of the lateral ventricles; B2- dilated 3 rd ventricle + mild or moderate ventriculomegaly; C- dilated 3 rd ventricle + severe ventriculomegaly; D- gross dilatation of 3 rd ventricle with the appearance of interhemispheric cyst. The AX1 view revealed: absence of the cavum septum pellucidi in all cases; dilatation of the third ventricle in 86.6 % of cases; separation of frontal horns in 83.3 % of cases; ventriculomegaly in 73.3 % of cases, including 13.6 % with severe forms. The AX2 view showed separation of the interhemispheric fissure (IHF) in 90 % of cases and upward displacement of the 3 rd ventricle in 80 % of cases. The COR view confirmed separation of the interhemispheric fissure in 90 % of cases including gross separation in 7.4 % of cases; absence of CC fibers at this level and descent of the falx towards the roof of the 3 rd ventricle in all cases, and upward displacement of the 3 rd ventricle in 80 % of cases. The SAG view revealed the absence of the CSP-CC complex in all cases and dilatation of the 3 rd ventricle in 86.6 % of cases. CONCLUSION: 1. We suggest a stepwise ultrasound diagnostic approach for cACC and variations of this condition. 2. We suggest a classification of characteristic patterns found in fetuses with proven cACC based on findings presented in axial views.

The Prospective External Validation of International Ovarian Tumor Analysis (IOTA) Simple Rules in the Hands of Level I and II Examiners.

Objective: To externally validate the International Ovarian Tumor Analysis (IOTA) Simple Rules (SR) by examiners with different levels of sonographic experience defined by the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) and to assess the morphological ultrasound features of the adnexal tumors classified as inconclusive based on IOTA SR. Materials and Methods: In the two-year prospective study adnexal tumors were assessed preoperatively with transvaginal ultrasound by examiners with different levels of experience (level 1- IOTA SR1, level 2-IOTA SR2). Additionally, an expert (level 3) evaluated all tumors by subjective assessment (SA). If the rules could not be applied, the tumors were considered inconclusive. The final diagnosis was based on the histopathological result of the removed mass. The diagnostic performance measures for the assessed model were sensitivity, specificity, negative (LR-) and positive(LR+) likelihood ratios, accuracy (ACC) and diagnostic odds ratio (DOR). Results: 226 women with adnexal tumors scheduled for surgery were included in the stutdy. The prevalence of malignancy was 36.3 % in the group of all studied tumors and was 52.5 % in the inconclusive group (n = 40) (p = 0.215). Fewer tumors were classified as inconclusive by level 2 examiners compared to level 1 examiners [20 (8.8 %) vs. 40 (17.7 %); p = 0.008], resulting from the discrepancy in the evaluation of acoustic shadows and the vascularization within the tumor. For level 1 examiners a diagnostic strategy using IOTA SR1 +MA (assuming malignancy when SR inconclusive) achieved a sensitivity, specificity and DOR of 96.3 %, 81.9 %, 13.624 respectively. For level 2 examiners the diagnostic strategy for IOTA SR2 +MA achieved a sensitivity, specificity and DOR of 95.1 %, 89.6 %, 137,143, respectively. Adding SA by an expert (or level 3 examiner) when IOTA SR were not applicable improved the specificity of the test and achieved a DOR of 505.137 (SR1 +SA) and 293.627 (SR2 +SA). The SA by an expert proved to have the best diagnostic performance with a DOR of 5768.857, and a sensitivity and specificity of 97.6 % and 99.3 % respectively. Within the inconclusive group the most common tumors were unilocular-solid (n-13), solid (n-8) and multilocular-solid (n-10) ones. All multilocular tumors were classified as inconclusive because of their size (≥ 100 mm) and were found to be benign by pathology. Most of the inconclusive tumors with cystic content presented low-level (43.75 %) echogenicity, followed by ground-glass (34.37 %), mixed (12.5 %) and anechoic (9.4 %). Conclusion: The study results show excellent diagnostic performance of IOTA Simple Rules followed by subjective expert assessment in inconclusive tumors irrespective of the level of experience, while subjective assessment by an expert still has the highest diagnostic odds ratio. The number of inconclusive cases seems to depend on the level of ultrasound expertise and less experienced examiners have a tendency to overestimate blood flow and a presence of acoustic shadows within the tumors. IOTA SR were not applicable either because no benign or malignant features were found or both were identified. Within inconclusive tumors the majority of cases comprise malignant masses that are either unilocular-solid, solid tumors or small multilocular-solid ones with a diameter of less than 100 mm.