Accuracy in estimating fetal urinary bladder volume using a modified ultrasound technique.

OBJECTIVE: Fetal urine production at different gestational ages has been evaluated using ultrasound in several previous studies. In a recent study, we investigated the accuracy when estimating the bladder volume using the conventional ultrasound technique and found a total variability of 17.3-10.9% for bladder volumes of 5-40 mL. The variability is mainly caused by: (i) inappropriate image selection (the 'freezing error') and (ii) limitations when measuring on the frozen image (the 'frozen error'). The aim of this study was to reduce the total error by reducing the 'freezing' and the 'frozen error'. To this end, we used a modified manual ultrasound technique (adding a 'rocking' motion to the conventional method) and digitized the selected image. METHODS: Two patients for each gestational week from 24 to 40 weeks were selected. The fetal urinary bladder was examined with ultrasound three times within 1 min and documented on videotape. The volume, as assessed by the longitudinal section of the recorded bladder images, stored in digitized form, was evaluated on three occasions with > 24 h in between. The mean and variability (standard deviation, SD) were estimated. RESULTS: For fetal bladder volumes between 5 and 40 mL, the 'freezing error' (SD), the 'frozen error' and the 'total error' were 11.7-5.1%, 8.0-3.0% and 14.2-5.9%, respectively. Comparing the present with a previous study, when selecting images and assessing bladder volumes repeatedly within 1 min, SD was 12.9-5.5% vs. 17.3-10.9%. CONCLUSIONS: Using a modified ultrasound technique, the variability in fetal bladder volume estimation can be reduced.     

Measurement of fetal urine production by three-dimensional ultrasonography in normal pregnancy.

OBJECTIVES: Measurement of fetal urine production may provide a means of evaluating amniotic fluid volume, which is difficult to measure directly, and predicting fetal hypoxia. Although there have been some reports on fetal urine production, most of these have used two-dimensional (2D) ultrasonography to measure bladder volume. Three-dimensional (3D) ultrasonography is, however, known to be superior to 2D ultrasonography in some organ volume measurements. Thus, we undertook this study to measure bladder volumes using 3D ultrasonography and to establish a nomogram of fetal urine production rate (UPR) according to gestational age (GA). METHODS: One hundred and fifty-four women with a normal singleton pregnancy at 24 to 40 weeks' gestation were enrolled in this cross-sectional study. The women had no medical or obstetric complications affecting amniotic fluid volume. Fetal bladder volume was measured using 3D ultrasound imaging and Virtual Organ Computer-aided AnaLysis (VOCAL) with a rotational angle of 30 degrees and manual surface tracing technique. Bladder volume was measured two or three times within a 5-10-min interval and fetal UPR was calculated from serial measurements. When measurements were performed more than twice, we used the mean rate of calculated UPRs. UPR was then plotted against GA to establish the nomogram. RESULTS: Fetal UPR increased with GA from a median value of 7.3 mL/h at 24 weeks' gestation to 71.4 mL/h at term, and could be calculated from GA using the formula: Ln(UPR) = - 6.29582 + (0.43924 x GA) + (0.000432 x GA2), r2 = 0.63, P = 0.0046. Growth percentiles of UPR according to age are presented. CONCLUSIONS: Fetal UPR can be easily measured by 3D ultrasound assessment of bladder volume. This modality may be a promising alternative to conventional methods of amniotic fluid volume measurement such as amniotic fluid index and single deepest pocket, and might be an alternative option for predicting fetal hypoxia.     

Estimation of fetal urinary bladder volume using the sum-of-cylinders method vs. the ellipsoid formula.

OBJECTIVES: A changing hourly fetal urine production rate (HFUPR) has been demonstrated when fetuses are subjected to hypoxia, which is of clinical interest. Conventionally, calculations of the HFUPR have been based on repeated two-dimensional ultrasound bladder images during the filling phase and the formula for ellipsoids. However, the bladder shape changes from the ellipsoidal to super-ellipsoidal during filling and the volume could be underestimated. In this study the sum-of-cylinders method was used, a method which does not depend on the longitudinal bladder shape being an ellipse. METHODS: The volumes from 102 urinary bladder images from 34 fetuses (three per fetus) were assessed using the sum-of-cylinders method. These results were compared with the corresponding findings when using the ellipsoid formula on the identical material of bladder images in a previous study. RESULTS: When using the sum-of-cylinders method vs. the ellipsoid formula, the mean volume difference was +1.6 mL. Applying the sum-of-cylinders method for bladder volumes of 5-40 mL resulted in standard deviations of 8.8-3.5% vs. 12.9-5.5% when using the ellipsoid formula. No deviation was found when using the sum-of-cylinders method vs. a known volume formula for cylinders, which simulated super-ellipsoids on the computer screen. CONCLUSIONS: Volume calculation by the sum-of-cylinders method is independent of the longitudinal bladder shape when it comes to producing accurate estimations. This method demonstrated a systematically larger volume compared with the ellipsoid formula. The sum-of-cylinders method is therefore preferable for volume estimations of the fetal urinary bladder.     

Usefulness of a prevoiding transabdominal sonographic bladder scan for uroflowmetry in patients involved in clinical studies of benign prostatic hyperplasia.

OBJECTIVE: Flow rate measurements in clinical studies require an amount of voided urine greater than 125 to 150 mL. Often patients do not void sufficient amounts of urine, and having them produce repeated flows is often difficult. Transabdominal sonographic scanning of the bladder is a simple method for estimating bladder volume. We determined by sonography the prevoiding bladder volume needed to void a sufficient amount of urine. METHODS: Sixty-seven patients with a mean age +/- SD of 67.5 +/- 8.0 years underwent free flow rate measurement. Bladder volume was measured by transabdominal sonography when the patient had the sensation to void and after uroflowmetry to calculate residual urine. RESULTS: The voided volume was 220 +/- 127 mL; the postvoiding residual urine volume was 92 +/- 88 mL; and the bladder scan volume was 309 +/- 158 mL. Among all patients, 23.9% had insufficient voided volumes of less than 125 mL in the flow rate measurements, and 31.3% had voided volumes of less than 150 mL. There was a strong correlation between the prevoiding measured volume and the voided volume (r = 0.836; P < .0001). Linear regression analysis of the flow rate recording yielded the following formula: voided volume = 11,766 + (0.673 x prevoiding volume). CONCLUSIONS: Bladder scanning before uroflowmetry is a useful test for reducing the amount of nonevaluable flow rate data. If a voided volume of greater than 125 mL (>150 mL) is required, the mandatory prevoiding bladder scan volume should be greater than 200 mL (>250 mL), which would decrease the number of noneligible flow rate recordings from 23.9% to 4.5% (31.3% to 4.5%).     

Fetal trunk and head volume measured by three-dimensional ultrasound at 11 + 0 to 13 + 6 weeks of gestation in chromosomally normal pregnancies.

OBJECTIVE: To establish the relationship between fetal trunk and head volume measured by three-dimensional (3D) ultrasound and gestational age at 11 + 0 to 13 + 6 weeks of gestation. METHODS: The fetal trunk and head volume were measured using 3D ultrasound in 417 chromosomally normal fetuses from singleton pregnancies at 11 + 0 to 13 + 6 (median, 12 + 0) weeks of gestation. Regression analysis was used to determine the significance of the association between fetal volume and gestational age. The Bland-Altman analysis was used to compare the measurement agreement and bias for a single examiner and between different examiners. RESULTS: The fetal trunk and head volume increased linearly with gestation from a mean of 5.8 mL at 11 + 0 weeks to 33.3 mL at 13 + 6 weeks and 1 SD was 4.4 mL. There was also a significant linear association between fetal volume and crown-rump length (CRL), from a mean of 5.1 mL at a CRL of 45 mm to 37.5 mL at a CRL of 84 mm and 1 SD was 2.7 mL. However, within this gestational range, a doubling in CRL, from a mean of 48 mm at 11 + 0 weeks to 79 mm at 13 + 6 weeks, was associated with a 5-6-fold increase in fetal volume. The mean difference in fetal volume between paired measurements by the same sonographer was -0.87 mL (95% limits of agreement, -2.31 to 4.05 mL) and the mean difference between paired measurements by two sonographers was -1.09 mL (-5.49 to 3.32 mL). CONCLUSIONS: 3D ultrasound can provide a reproducible measurement of the fetal trunk and head volume in early pregnancy. At between 11 + 0 and 13 + 6 weeks there is a 5-6-fold increase in fetal volume but only a doubling in CRL.     

Evaluation of in vitro measurement accuracy of a three-dimensional ultrasound scanner

We have constructed a three-dimensional (3-D) ultrasound scanner to make examinations easier and more accurate. The accuracy of the 3-D scanner has been determined by scanning a three-dimensional model. Lengths, angles, and volume of the model were computed and compared to values determined from physical measurement. Distances between image planes were computed with a mean error of 0.4% of true value. Volume was computed with a mean error of 1.6%, or 0.64 mL +/- 0.72 mL (1 SD). We conclude that the 3-D scanner has a system error of less than 0.4%, that it does not introduce significant new errors, and that the principal source of measurement error is poor lateral resolution due to ultrasound beam width. We believe that the 3-D scanner may be a clinically useful instrument for quantitative echographic measurements.     

Accuracy of fetal lung volume assessed by three-dimensional sonography.

OBJECTIVE: To determine the accuracy and precision of prenatal three-dimensional (3D) ultrasound in estimating fetal lung volume using the rotational multiplanar technique (VOCAL) by comparing it to postmortem volume measurements. METHODS: Fetal lung volume was measured during 3D ultrasound examination using a rotational multiplanar technique in eight cases of congenital diaphragmatic hernia (CDH) (six left and two right-sided) and in 25 controls without pulmonary malformation, immediately before termination. Prenatal 3D sonographic estimates of fetal lung volume were compared with postmortem measurement of fetal lung volume achieved by water displacement. RESULTS: The intraclass correlation coefficient of fetal lung volume estimated by 3D ultrasound and measured at postmortem examination was 0.95 in CDH cases and 0.99 in controls. Based on Bland-Altman analysis, the bias, precision and limits of agreement were, respectively, 0.35 cm(3), 1.46 cm(3) and between -2.51 and + 3.21 cm(3) in cases with CDH and 0.08 cm(3), 2.80 cm(3) and between -5.41 and + 5.57 cm(3) in controls. The mean relative error of 3D ultrasound fetal lung volume measurement was -7.19% (from -42.70% to + 18.11%) in CDH cases and -0.72% (from -30.25% to + 19.22%) in controls, while the mean absolute error of 3D ultrasound fetal lung volume measurement was 1.40 (range, 0.71-2.52) cm(3) and 2.12 (range, 0.05-4.98) cm(3), respectively. Accuracy of 3D ultrasound for measuring fetal lung volumes was 84.86 (range, 57.30-99.48)% in cases with CDH and 91.38 (range, 69.75-99.45)% in controls. The mean intraobserver variability for lung volume estimated by 3D ultrasound was 0.28 cm(3) in controls and 0.17 cm(3) in CDH cases. CONCLUSION: Prenatal 3D ultrasound can estimate accurately fetal lung volume using the rotational multiplanar technique for volume measurements (VOCAL), even in fetuses with very small lungs, such as cases with isolated CDH.     

The effectiveness of implementing a bladder ultrasound programme in neurosurgical units

AIM: This paper reports an evaluation of the differences among rates of unnecessary catheterization, urinary retention and urinary tract infection before and after implementing a bladder ultrasound programme to assess urine volume. BACKGROUND: Bladder ultrasound is a non-invasive alternative to urethral catheterization for the determination of bladder urine volume. Much of the literature available on bladder ultrasound technology addresses the accuracy of the equipment, with little research on the clinical outcomes or benefits of the intervention. METHODS: A quasi-experimental design was adopted. Data were collected from March 2001 to May 2001 in a control group in two neurosurgical units in Taiwan. During July and August 2001, nurses were taught how to operate a portable ultrasound machine and how to implement the programme. Data were collected from September to November 2001 in the study group. RESULTS: The rates of unnecessary catheterization in the control group and the study group were 35.3% and 7.0%, respectively. The urine volume (more than 500 mL) in the control group and the study group were 13.4% and 20.3%, respectively. The study group had a statistically significantly lower average catheterization volume than that of the control group (676.9 mL vs. 777.1 mL, t = 1.84, P < 0.05). During 3 months before and after the implementation of the programme, the urinary tract infection rates in the control group and the study group were 3.47% and 2.87%, respectively. After 6 months the urinary tract infection rates decreased to 1.39%. CONCLUSION: The bladder ultrasound programme was successful and could be used to manage patients with urination disorders in neurosurgical units.     

Fetal head and abdominal circumferences: I. Evaluation of measurement errors

Several sources of error associated with the measurement of fetal head and abdominal circumferences (HC, AC) were examined using dynamic image ultrasound. Statistically significant systematic intraobserver errors were not seen unless technical differences in the images were present (HC only) and the range for random errors was 4-5% (2 SD) for both measurements. Although differences in the procedures used to acquire images for measurement had some effect on accuracy (HC only), the primary source of variations in measurements made by different investigators was the measurement methods. Different measuring devices gave different results and different investigators used the same devices differently. Under optimal measuring conditions, the interobserver error for experienced investigators was 1.2 (+/-4.3 SD)% for HC and 2.4 (+/-1.6 SD)% for AC. Comparison of prenatal and postnatal measurements indicated that there were no systematic differences for HC but for AC, the prenatal measurements were 6% greater. Random differences were +/-6% (2 SD) for HC and +/-13% (2 SD) for AC.     

Three-dimensional sonographic assessment of fetal urine production before and after laser surgery in twin-to-twin transfusion syndrome.

OBJECTIVE: Fetal urine production in twin-to-twin transfusion syndrome (TTTS) reflects the hemodynamic imbalance between the donor and recipient twins but it has not been measured in this particular condition. The aim of this study was to measure fetal urine production using three-dimensional (3D) ultrasound in donor and recipient twins before and after laser treatment for TTTS and to correlate this with umbilical venous volume flow (UVVF). METHODS: Urine production rate (UPR) was measured using 3D ultrasound with Virtual Organ Computer-aided AnaLysis (VOCAL) in 106 cases of severe TTTS. The rotation angle was set at 30 degrees . The bladder volume was measured twice in each fetus (V(1) and V(2)), with an interval of 5-30 min between measurements, in order to calculate the UPR. When V(2) > V(1), UPR was calculated using the formula: V(2) - V(1) /time interval. Together with UPR, UVVF was measured before and after treatment. Both parameters were corrected for fetal weight. Inter- and intraobserver variability were calculated in 16 cases using the intraclass correlation coefficient. RESULTS: Before laser treatment, UPR was significantly higher in recipients compared with donors (median, 14.8 and 0 mL/h/kg, mean 23.8 and 2.3 mL/h/kg, respectively, P < 0.001), and UPR was positively correlated with UVVF in both twins. Following laser treatment (48 h later), UPR decreased to 9 mL/h/kg (P < 0.001) in recipients, while there was no change in donors. UVVF increased significantly from a median value of 92 to 132 mL/min/kg (P < 0.01) in donors and decreased significantly from 150 to 99 mL/min/kg (P < 0.001) in recipients. CONCLUSIONS: In TTTS UPR is correlated to UVVF and reflects the hemodynamic imbalance between donor and recipient twins. Following laser treatment, UPR decreases in recipients but is unaffected in donors. However, changes in UVVF occur in both twins. This suggests that although fetal renal function is driven by fetal hemodynamics, there may be a lag in the recovery of renal function in the donor twin.     

Online artery diameter measurement in ultrasound images using artificial neural networks

An automated online technique is described for measurement of artery diameter in flow-mediated dilation (FMD) ultrasound (US) images, using artificial neural networks to identify and track artery walls. This allows FMD results to be calculated without the inherent delay of current retrospective methods. Two networks were trained to identify artery anterior and posterior walls using over 3200 examples from carotid artery images. Both networks correctly classified approximately 97% of the randomly selected test samples. The technique was verified using a physical model with absolute measurement error of -1.16% +/- 1.04% (mean +/- SD) over the diameter range 2 to 8 mm. Advantages of the technique include: online analysis; wall tracking optimisation before the study proper; measurement of diameter changes over the cardiac cycle; low FMD measurement variance; minimal image degradation; and no unwieldy image store. Measurement of artery diameter changes over the cardiac cycle was explored using simulated image sequences generated with a virtual US scanner.     

盆腔B超检查前膀胱充盈状况的研究

[目的]观察老年人盆腔B超检查前适量饮水后膀胱充盈与膀胱内尿量的关系,为做好检查前指导提供科学依据.[方法]随机选择行盆腔B超检查的95例住院老年人为受试对象,B超显示膀胱充盈度并测量膀胱容量;检查后立即排空膀胱并测量尿量;记录病人憋尿时的感受.[结果]膀胱充盈满意、基本满意、不满意者分别为63例、16例、16例;B超测膀胱容量及尿量分别为＞300mL、＞110 mL、＜100mL;膀胱充盈满意度与B超测膀胱容量、排出尿量密切相关;膀胱充盈满意者膀胱容量大、尿量多,较基本满意者、不满意者均有统计学差异;膀胱充盈满意者B超测膀胱容量及尿量均＞300 mL.憋尿时的感觉主要为烦躁出汗、小腹胀痛、急于解出小便及小量解出.不同膀胱充盈度者憋尿时的不适发生率无统计学差异,但膀胱充盈满意者中憋尿时的不适发生率较高.[结论]膀胱充盈度与膀胱内尿量密切相关,为使检查顺利进行,盆腔B超检查前应对饮水量给予指导,以保证膀胱内产生一定尿量;同时根据憋尿时的感受判断膀胱内充盈情况;急诊或不能耐受憋尿者可经导尿管注入150 mL～300 mL生理盐水以满足检查需要.     

Effectiveness of the portable ultrasound bladder scanner in the measurement of residual urine volume after total mesorectal extirpation

The measurement of residual urine volume by bladder catheterization causes quite some suffering to the patient and sometimes causes urinary tract infections. To evaluate the postoperative measurement of residual urine volume with a portable ultrasound bladder scanner (Bladder Scan BVI 3000) and the cost-benefit analysis as compared with postoperative catheterization we carried out a study on 30 patients with primary rectal cancer. The data were then compared with actual urine volumes. This was a prospective study dealing with the economical benefit of ultrasound scanning over catheterization during the hospital stay. The ultrasound bladder scanner was found to be a reliable method of estimating residual urine volume since its data correlated with actual volumes with a coefficient of 0.9. The results satisfied both physicians and patients. Ultrasound scanning of the bladder to measure residual urine volume reduced the frequency of catheterization by 38% as compared with the patients on intermittent catheterization, with 17.4 catheters saved for each patient. In conclusion, the ultrasound bladder scanner could protect patients from the discomfort and urethral injury which might have been caused by bladder catheters, thus decreasing medical expenses. This technique will play an important role in determining whether to conduct invasive urethral catheterization for postoperative urinary disturbance in rectal cancer.     

Striking findings concerning the variability in the measurement of the fetal renal collecting system.

OBJECTIVE: Using strict thresholds of normality, investigators have reported associations between fetal pyelectasis and aneuploidy, obstructive uropathy, postnatal pyeloplasty and vesicoureteral reflux. Although evidence continues to mount regarding the importance of fetal pyelectasis, little is known of the variability of collecting system measurements. To investigate the short-term variability and its relationship to bladder dilatation, the following study was conducted. DESIGN: During May and June 1996, 20 mid- and late-trimester patients with varying degrees of fetal pyelectasis were recruited into this study. Each consented to undergo periodic (every 15 min for 2 h) ultrasound measurements of the fetal renal collecting systems and bladder. To account for anatomic and technical variability in measurement, we used both the sum of the transverse and anterior-posterior (AP) measurements of the collecting systems, and AP measurement alone for comparison. The variability of the collecting system measurements was assessed based upon gestational age, magnitude of pyelectasis and fetal bladder size. RESULTS: We investigated 38 renal units in 20 patients (eight in the second trimester and 12 in the third). The mean(SE) AP diameter of all kidneys was 5.89(2.49) mm (range 15 (2-17) mm), and the sum of transverse and AP renal collecting system diameters was 13.91(5.73) mm (range 26 (4-31) mm). These data were normally distributed. When assessing the variability in individual kidneys over time, we found the mean variation (minimum to maximum) for the sum of the AP and transverse measurement to be 7.61(4.26) mm and for the AP measurement alone to be 3.80(2.49) mm. No relationship was found between variability of dilatation, magnitude of dilatation or fetal bladder size. Cyclic dilatation of the fetal bladder was observed in all cases. The mean time from maximal to minimal dilatation was 20 min (1.34 observations; range 12-30 min). CONCLUSIONS: We found the size of the fetal renal collecting system to be highly variable over the course of a 2-h period. Seventy per cent of cases (14 of 20) had both normal (< 4 mm) and abnormal values (> or = 4 mm) during the 2-h study period. Significant caution should be used when considering the implications of renal collecting system dilatation based upon a single AP measurement.     

Effect of maternal hydration on mild fetal pyelectasis.

The aim of our study was to determine whether maternal hydration status prior to prenatal sonography affects fetal renal pelvic diameter. The renal pelvic diameters of fetuses from two different institutions were compared prospectively. At one institution 74 women were asked to drink 32 to 48 ounces of water prior to undergoing sonography (hydration group), whereas at the second institution, no specific hydration regimen was requested of 176 subjects. The inclusion criteria were as follows: greater than 15 weeks' gestation, otherwise normal obstetrical sonogram, normal amniotic fluid volume, and negative family history for renal disease. Renal pelvic diameter, degree of maternal bladder fullness, and gestational age were compared between the two groups using logistic regression analysis and log-linear analysis. A P value < 0.01 was considered significant. Bladder fullness in the two groups differed significantly (P < 0.001). Logistic regression analysis showed a very strong effect of maternal bladder fullness on fetal renal pelvic diameter (P < 0.001). The log-linear analysis model showed a highly significant association between maternal bladder fullness and fetal renal pelvic diameter (P < 0.001). We conclude that maternal hydration influences fetal renal pelvic diameter. The larger fetal renal diameters seen in the hydrated group support physiologic theories that the effects of maternal hydration on amniotic fluid volume are partially mediated via fetal urine production.     

Development of three-dimensional power Doppler ultrasound imaging of fetoplacental vasculature

To develop an off-line system for three-dimensional (3-D) ultrasound (US) reconstruction of fetoplacental vasculature using colour segmentation and reconstruction software and to determine sources of error in fully freehand ultrasound image acquisition. US images were acquired freehand with the Acuson Sequoia (5C 2-MHz transducer) using power Doppler. After digital transfer to a personal computer, CQ Analysis software (Kinetic Imaging Ltd, Liverpool, UK) was used to segment the colour information from these images, and the resulting 8-bit grey-scale images were used for 3-D rendering using commercial software (VoxBlast, Vaytek Inc., Fairfield, IA, USA). 2-D scanning, software and freehand acquisition accuracy were assessed using a linear test rig and distance and volume phantoms (Dansk Phantom Service Ltd); 2-D scanning accuracy was within 1.3%, and software reconstruction accuracy within 1% for x and y planes and up to 3% for the z plane. Fully freehand acquisition was associated with a 12% to 18% mean percentage error in distance measurement in the plane of acquisition. Volumetric reconstruction inaccuracy was between 1.5% and 19.7% for precisely separated images and between 16.2% and 39.2% for fully freehand image acquisition. Rendered 3-D US vascular images clearly delineated vascular anatomy within the placenta and cord. Fully freehand 3-D US does have a role in off-line reconstruction of vascular anatomy, although variability in the z plane precludes its use for volumetric measurement. (E-mail: a.welsh@ic.ac.uk)     

三维超声测量正常中晚期单胎妊娠胎儿产尿率

目的 应用三维超声测量正常中晚期单胎妊娠胎儿的膀胱容量以估算不同孕期胎儿的产尿率,并探讨胎儿产尿率与孕周及羊水指数之间的关系.方法 对138例正常中晚期单胎妊娠胎儿进行三维超声检查,采用三维超声体积自动测量技术,间隔5～15 min,重复2～3次测量胎儿膀胱容量并计算产尿率.结果 胎儿的产尿率随孕周增加而增加,自孕24周的12.84 ml/h升至孕42周的64.70 ml/h,二者之间有明显相关关系(r=0.900,P<0.05).胎儿的产尿率与羊水指数无明显相关关系(r=-0.199,P>0.05).结论 运用三维超声体积自动测量技术测量正常中晚期单胎妊娠胎儿的膀胱容量变化可估算胎儿的产尿率,并可了解胎儿肾功能状态及宫内安危情况.     

Registration of 3D fetal neurosonography and MRI

We propose a method for registration of 3D fetal brain ultrasound with a reconstructed magnetic resonance fetal brain volume. This method, for the first time, allows the alignment of models of the fetal brain built from magnetic resonance images with 3D fetal brain ultrasound, opening possibilities to develop new, prior information based image analysis methods for 3D fetal neurosonography. The reconstructed magnetic resonance volume is first segmented using a probabilistic atlas and a pseudo ultrasound image volume is simulated from the segmentation. This pseudo ultrasound image is then affinely aligned with clinical ultrasound fetal brain volumes using a robust block-matching approach that can deal with intensity artefacts and missing features in the ultrasound images. A qualitative and quantitative evaluation demonstrates good performance of the method for our application, in comparison with other tested approaches. The intensity average of 27 ultrasound images co-aligned with the pseudo ultrasound template shows good correlation with anatomy of the fetal brain as seen in the reconstructed magnetic resonance image.     

Effect of premicturitional bladder volume on the accuracy of postvoid residual urine volume measurement by transabdominal ultrasonography: rate of bladder fullness is of great importance for preventing false-positive residue diagnosis.

OBJECTIVE: The purpose of this study was to evaluate the effect of premicturitional bladder volume (V1) on postvoid residual urine volume (V2) measurements and to assess the ideal V1 for an accurate V2 determination. METHODS: Twenty-five healthy men without any urinary symptoms constituted the study group. Measurements by transabdominal ultrasonography for V1 and V2 were performed for each subject at 3 different phases, each of which was preceded by oral intake of 1000 mL of water and accompanied by "mild," "moderate," and "severe" sensations of micturition, respectively. RESULTS: Mean +/- SD V1 and V2 during the first, second, and third phases were 117.7 +/- 70.3 and 1 +/- 1, 356.2 +/- 112.3 and 11.5 +/- 12 and 639.6 +/- 171.8 and 58.8 +/- 35.2 mL, respectively. With 50 mL as the cutoff value for a pathologic V2, 15 (60%) men had V2 in the third phase exceeding this value, whereas the same rate was calculated as 0% for either of the first 2 phases. No patient with V1 of less than 540 mL had V2 of greater than 50 mL. CONCLUSIONS: Postvoid residual urine volume measurements with an uncomfortably full bladder result in high false-positive postmicturitional residue values even in healthy young men. We strongly advise that V1 measurements of the bladder be performed before V2 measurements and that V2 not be measured if V1 is greater than 540 mL.     

Learning Curve for Automated Ultrasound Cystovolumetry in Patients With Localized Prostate Cancer

PurposeThe purpose of this study was to investigate the learning curve of automated ultrasound cystovolumetry in novice radiation nurses and to determine how much experience is required before reliable measurements can be obtained.MethodFive consecutive patients with localized prostate cancer who underwent intensity modulated radiation therapy were included in this study. Immediately before each irradiation, three novice radiation nurses with no experience in ultrasonography measured urinary bladder volume using an automated ultrasound cystovolumetry system (CUBEScan). Changes in the relative error of bladder volume were examined.ResultsThe mean value of the relative error decreased and became constant after the third irradiation, that is, the fifteenth measurement. The mean value of the relative error from the first to the third irradiation was 0.12 ± 0.03 (mean ± standard deviation [SD]), whereas that from the fourth to the tenth irradiation was 0.05 ± 0.03 (mean ± SD) (p = .03).ConclusionIt takes at least 15 measurements for a novice radiation nurse to be able to accurately measure bladder volume using the automated ultrasound cystovolumetry system.