A new method for validation of quantitative measurement by intravascular ultrasound in vivo

Studies in vitro show that intravascular ultrasound (IVUS) underestimates vessel and lumen dimensions. In order to validate IVUS measurement in vivo, we conducted a comparative study during catheterization in fifty patients. The patients underwent IVUS examinations for the purpose of diagnosis or treatment of coronary artery disease. The IVUS system was a 3.5 F, 20 MHz IVUS catheter (Sonicath catheter of Boston Scientific Co.) and a Hewlett Packard console. After examination of the coronary artery, the IVUS probe was withdrawn back into the guiding catheter to measure the average lumen diameter of the guiding catheter (8 F, Cordis). This measurement in vivo (VI) was compared with the true lumen diameter provided by the manufac Department of Cardiology, University of Essen, Essen, Germany (Liu FQ, Ge JB, Baumgart D, Haude M, Caspari G, Grge G, Eick B and Erbel R) turer (MA) and determined by on line quantitative angiography (HICOR, Siemens) (HI). In addition, the IVUS measurement in vitro (VT) was also taken with the same guiding catheter in waterbath at 37℃. The results showed that IVUS underestimated the true lumen diameter by 2.2%±2.6% in vivo, by 3.1%±1.8% in vitro, while HICOR owerestimated the true lumen diameter by 23.0%±6.8%. There was no difference between the IVUS measurements in vivo and in vitro. In summary, IVUS was very accurate for the measurement of a 8 F guiding catheter in vivo with only a minor underestimation, and IVUS measurement was far more reliable than the on line quantitative angiography.

Which fetal growth charts should be used?A retrospective observational study in China

Background:The fetal growth charts in widest use in China were published by Hadlock>35 years ago and were established on data from several hundred of American pregnant women.After that,>100 fetal growth charts were published around the world.We attempted to assess the impact of applying the long-standing Hadlock charts and other charts in a Chinese population and to compare their ability to predict newborn small for gestational age(SGA).Methods:For this retrospective observational study,we reviewed all pregnant women(n=106,455)who booked prenatal care with ultrasound measurements for fetal biometry at the Shenzhen Maternity and Child Healthcare Hospital between 2012 and 2019.A fractional polynomial regression model was applied to generate Shenzhen fetal growth chart ranges for head circumference(HC),biparietal diameter(BPD),abdominal circumference(AC),and femur length(FL).The differences between Shenzhen charts and published charts were quantified by calculating the Z-score.The impact of applying these published charts was quantifed by calculating the proportions of fetuses with biometric measurements below the 3rd centile of these charts.The sensitivity and area under the receiver operating characteristic curves of published charts to predict neonatal SGA(birthweight<10th centile)were assessed..Results:Following selection,169,980 scans of fetal biometry contributed by 41,032 pregnancies with reliable gestational age were analyzed.When using Hadlock references(<3rd centile),the proportions of small heads and short femurs were as high as 8.9%and 6.6%in late gestation,respectively.The INTERGROWTH-21st standards matched those of our observed curves better than other charts,in particular for fat-free biometry(HC and FL).When using AC<10th centile,all of these references were poor at predicting neonatal SGA.Conclusions:Applying long-standing Hadlock references could misclassify a large proportion of fetuses as SGA.INTERGROWTH-21st standard appears to be a safe option in China.For fat-based biometry,AC,a reference based on the Chinese population is needed.In addition,when applying published charts,particular care should be taken due to the discrepancy of measurement methods.