Percutaneous renal intervention: comparison of 2-D and time-resolved 3-D (4-D) ultrasound for minimal calyceal dilation using an ultrasound phantom and fluoroscopic control

The rapid advances made by ultrasound in recent years have increasingly taken 3-D ultrasound (3DUS) and 4-D ultrasound (4DUS) from the research setting to the patient's bedside. There are still unexplored areas like renal percutaneous intervention, where 4DUS has yet to be proven an effective tool. Ultrasound-only guidance in renal percutaneous access is used in selected well-dilated pelvi-calyceal systems (PCS), and fluoroscopy is often utilized as an adjunct. Our aim was to compare 2-D and 4-D guidance for punctures, with fluoroscopy as control, using an in vitro ultrasound phantom. Agar and latex were the tissue-mimicking materials used for the construction of the phantom. The latex targets were designed to simulate multidirection-facing minimally dilated renal calyces. Two interventional fellows punctured the "calyces" using first 2DUS and then 4DUS guidance, making use of a different set of targets each time. The time to puncture, time to introduction of wire, quality of puncture (judged on fluoroscopy) and global rating of both modalities were documented. There was no significant difference between the times to puncture using 2DUS (1.8 min) and 4DUS (2 min). Nor was there a significant difference in the quality of puncture. 4DUS had a higher median difficulty rating. The multiplanar reformatted (MPR) longitudinal and transverse images were found to be the most useful for needle guidance. Cross hairs in all MPR images were not just useful in aligning the images on target but also as surrogate targets. The phantom was found to be robust, with only one instance of air introduction after 30 punctures. We have found that 4DUS is at least as good as 2DUS in terms of quality of punctures in vitro. The technology still has some way to go as frame rates, transducer size and resolution improve.     

Validity of Freehand 3-D Ultrasound System in Measurement of the 3-D Surface Shape of Shoulder Muscles

Freehand 3-D ultrasound (3DUS) system is a promising technique for accurately assessing muscle morphology. However, its accuracy has been validated mainly in terms of volume by examining lower limb muscles. This study was aimed at validating 3DUS in the measurements of 3-D surface shape and volume by comparing them with magnetic resonance imaging (MRI) measurements while ensuring the reproducibility of participant posture by focusing on the shoulder muscles. The supraspinatus, infraspinatus and posterior deltoid muscles of 10 healthy men were scanned using 3DUS and MRI while secured by an immobilization support customized for each participant. A 3-D surface model of each muscle was created from the 3DUS and MRI methods, and the agreement between them was assessed. For the muscle volume, the mean difference between the two models was within –0.51 cm³. For the 3-D surface shape, the distances between the closest points of the two models and the Dice similarity coefficient were calculated. The results indicated that the median surface distance was less than 1.12 mm and the Dice similarity coefficient was larger than 0.85. These results suggest that, given the aforementioned error is permitted, 3DUS can be used as an alternative to MRI in measuring volume and surface shape, even for the shoulder muscles.     

Accuracy of Carotid Artery Stenosis Quantification with 4-D-Supported 3-D Power-Doppler versus Color-Doppler and 2-D Blood Velocity-Based Duplex Ultrasonography

Assessment of the severity of internal carotid artery stenosis is relevant to therapeutic decisions. Direct measurement of stenosis in static three-dimensionally rendered ultrasonographic color-Doppler images after an orientation with 4-D gray-scale views (4D/3D-C-US) was recently observed to be metrically non-inferior to angiography. In the study described here, power-Doppler (Christian Doppler was a physicist) ultrasonography (4D/3D-P-US) was prospectively compared with angiography, 4D/3D-C-US and 2-D duplex ultrasonography (DUS) in a similar fashion using blinded observers. Percentage stenosis was measured in 36 patients. Continuous percentage stenosis measures (standard deviation of difference and concordance correlation coefficient) between angiography and 4D/3D-P-US did not differ from the results between angiography observers (p > 0.05). Dichotomous diagnosis with 4D/3D-P-US resulted in κ values similar to the inter-rater agreement of angiography and the inter-method agreement of 4D/3D-C-US and DUS compared with angiography. Binary accuracy did not differ between 4D/3D-P-US, 4D/3D-C-US and DUS (p > 0.5). In conclusion, stenosis grading using 4D/3D-P-US exhibited non-inferior inter-method agreement with angiography at good accuracies, similar to 4D/3D-C-US and DUS.     

Validation of 3D ultrasound vessel wall volume: an imaging phenotype of carotid atherosclerosis

Carotid atherosclerotic lesions are a major cause of stroke and the identification and quantification of such lesions in patients is important for the development of a better understanding of atherogenesis in high risk populations and for the design of studies to assess treatment efficacy. Our objective was to develop and validate a new three-dimensional ultrasound (3DUS) measurement or phenotype of carotid atherosclerosis, vessel wall volume (VWV), which is a three-dimensional measurement of vessel wall thickness and plaque within the carotid arteries measured in 3DUS images. To assess both intraobserver and interscan variability, 3DUS images were acquired from the right and left carotid arteries of ten subjects with carotid atherosclerosis scanned twice within a period of 2 wk. For both VWV and total plaque volume (TPV), an expert observer performed five measurement trials of all images acquired at baseline scan and 2-wk rescan with a 5-d period between measurement trials for images. Images were re-randomized for each measurement trial and both TPV and VWV were measured by observers who were blinded to subject identification for each time-point measurement. Coefficients of variation (COV) and intraclass correlation coefficients (ICC), for VWV measurements indicated higher intraobserver (scan COV = 4.6% ICC = 0.95, rescan COV = 3.4%, ICC = 0.96) and interscan reproducibility (COV = 5.7%, ICC = 0.85) than TPV measurements (intraobserver variability scan COV = 22.7% ICC = 0.85, rescan COV = 21.1% ICC = 0.88 and interscan variability, COV = 31.1%, ICC = 0.83), although absolute variances for both phenotypes were very similar (VWV = 90 mm3, TPV = 80 mm3).     

Evaluation of the Accuracy of 3‐Dimensional Ultrasonography of the Kidney Using an In Vitro Renal Model

Objective. Three‐dimensional ultrasonography (3DUS) has recently become a reality because of advances in ultrasound probes and machine processing ability. We have developed an anthropomorphic phantom of the human loin to assess both the accuracy of 3DUS of the kidney and its potential usefulness for training in ultrasonographically guided percutaneous renal intervention. Methods. The model was built with easily available and inexpensive materials such as agar and latex with known ultrasonographic properties. The accuracy of 2‐dimensional ultrasonography (2DUS) and 3DUS was assessed by measuring the dimensions of the pelvicalyceal system (PCS) ultrasonographically (pelvis width and calyx diameters) and then comparing these with measurements obtained at the time of construction. Radiology interventional trainees then punctured the PCS with 2DUS and 4‐dimensional ultrasonographic (real‐time/time‐resolved 3DUS) guidance and reported the phantom's performance. Results. The 3‐dimensional nature of the model's PCS could be clearly visualized on 2DUS and 3DUS, and the scan characteristics were very similar to those in real life. Measurements using 3DUS proved to be closer to the true dimensions of the model's PCS than those using 2DUS. The mean error percentage for 2DUS measurements was ?10.2%, and that for 3DUS was ?2.2% (P < 0.0001). Interventional trainees were satisfied with the “tissue feel” and level of difficulty posed on puncturing the phantom. Conclusions. Three‐dimensional ultrasonography proved to be more accurate than 2DUS for intrarenal measurements using this in vitro renal model. Three‐dimensional ultrasonography has the potential to ease diagnostic renal scanning with the ability to further scrutinize and postprocess the scanned volumes. The model was realistic in its anthropomorphic properties and simulated human tissue during puncture.     

Treatment of deeply located acute intravascular thrombi with therapeutic ultrasound guided by diagnostic ultrasound and intravenous microbubbles.

OBJECTIVE: We sought to determine the added value of simultaneous imaging of intravenously infused microbubbles that are being used to dissolve an intravascular thrombus with therapeutic ultrasound (TUS). METHODS: In a chronic canine arteriovenous graft occluded by a thrombus, TUS (1 MHz) was applied through a 6-cm-thick tissue-mimicking phantom (measured mean +/- SD peak negative pressure through the phantom, 958 +/- 104 kPa) during an intravenous infusion of either saline (n = 6 occlusions) or lipid-encapsulated microbubbles (ImaRx Therapeutics, Inc, Tucson, AZ). Therapeutic ultrasound was intermittently applied during the microbubble infusion either at set time intervals (n = 6 occlusions) or when simultaneous diagnostic ultrasound (DUS) indicated a sustained presence of microbubbles (n = 12 occlusions). Success was defined as return of rapid flow within the graft (grade 3 flow). RESULTS: Diagnostic ultrasound showed microbubbles moving through small channels within the thrombus before angiographic evidence of flow in the graft. This guided the timing of TUS application better than using set time intervals. Angiographic clearance of the thrombus and restoration of grade 3 flow at 45 minutes of treatment were seen in 33% of deeply located thrombosed grafts treated with TUS at set time intervals and 92% of grafts treated with TUS guided by DUS (P < .001 compared with set time intervals). CONCLUSIONS: The use of TUS with intravenous microbubbles has a high success rate in recanalizing deeply located thrombosed arteriovenous grafts when performed with DUS guidance.     

二维、三维超声技术检测正常胎儿胸腺的研究

目的 建立胎儿胸腺二维各径线和三维体积的正常值,并比较胎儿胸腺的二维、三维超声测量.方法 采集567例正常胎儿胸腺的二维超声测值,包括最大横径、前后径、上下径、最大横截面积及三维超声体积.结果 567例胎儿中541例胎儿满意获得胎儿胸腺的最大横径、前后径、上下径和最大横截面积和体积.胎儿胸腺二维各径线、三维体积均随孕周的增加而增加,与孕周均呈直线相关,三维体积与孕周的相关性明显高于二维超声测值(P＜0.05).结论 本研究建立了胎儿胸腺二维超声面积、周长、直径、横径和三维超声体积的正常参考值.三维超声测量胎儿胸腺体积与孕周相关性更高,提示较二维超声测量更为准确.

Abstract：

Objective To establish the normative data of the 2D and 3D ultrasound (US)measurements of the developing fetal thymus and comparing the 2DUS and 3DUS measurements of the fetal thymus. Methods The normal fetuses' thymus of 567 cases were assessed, and maximum transverse diameter(MTD),antero posterior diameter (APD), suprainferior diameter (SID), maximum transverse area (MTA) were measured by 2DUS,and thymic volume(TV) was measured by 3DUS. Results 2DUS,3DUS assessments of the fetal thymic MTD, APD, SID, MTA and TV were possible in 541 of 567 normal singletons. The fetal thymic 2D diameters/area and 3D volume grow with the gestational age(GA) in linear correlation. The 3D-US TV measurements and GA was significantly higher than that of any individual 2DUS measurements and GA ( P ＜0.05). Conclusions This study presents the normative data of the 2DUS and 3DUS measurements of the developing fetal thymus. 3DUS fetal thymus volume is more significantly correlated to GA than the other 2DUS measurements, which indicates 3DUS measurement of the fetal thymus is more accurate than that of 2DUS.     

Ovarian volume measurements in mice with high-resolution ultrasonography.

OBJECTIVE: The aim of our study was to evaluate the intraobserver and interobserver variability of ovarian volume measurements in mice with high-resolution 2-dimensional ultrasonography (2DUS) and 3-dimensional ultrasonography (3DUS). METHODS: Ovaries of 10 nude mice were visualized with a small-animal ultrasound scanner and a 40-MHz probe. For each ovary, volume was measured 3 times by 2 independent readers using both 2DUS and 3DUS methods. The 2DUS method used a biplane ellipsoid model. The 3DUS method estimated the volume by integrating 10 to 12 parallel image planes of the ovary after semiautomated outlining of the boundaries. For each type of measurement, intraobserver and interobserver standard error of measurement (SEM) values and minimal detectable volume changes were calculated by analysis of variance. RESULTS: Two-dimensional ultrasonography showed much poorer reproducibility, with higher absolute intraobserver and interobserver SEM values (0.50 and 0.61 mm3, respectively) than 3DUS (0.20 and 0.35 mm3; P < .01). Relative intraobserver and interobserver SEM values were also much higher for 2DUS (12.20% and 14.88%) than for 3DUS (5.12% and 8.97%; P < .01). The minimal volume changes that could be detected with a 95% confidence level in successive measurements by the same (or different) observers were 33.90% (41.22%) for 2DUS and 14.10% (24.87%) for 3DUS. CONCLUSIONS: High-resolution 3DUS can provide a reliable tool for noninvasive, longitudinal ovarian volume measurements in mice.     

三维超声用于青少年特发性脊柱侧凸评估的信度与效度研究

目的:探索三维超声成像技术在临床上评估和测量青少年特发性脊柱侧凸(AIS)患者椎体侧凸角度的可行性;通过与磁共振成像(MRI)的测量方法比较,评价三维超声测量结果的信度与效度。方法:16例AIS女性患者在同一上午进行三维超声和MRI的全脊柱扫描。将三维超声和MRI的图像进行随机分配,两位评测者随机抽取图像进行测量;所有图像均需进行3次测量,每次测量间隔1周,且测量过程中对两位评测者采取盲法。在冠状面上,三维超声成像采用椎板中心法(COL)测量AIS的椎体侧凸角度;而MRI成像采用Cobb方法。通过计算组内相关系数(ICC[2,k])评价三维超声测量方法的信度;通过与MRI测量结果比较,采用配对t检验及Pearson相关系数,评价三维超声测量方法的效度。结果:在冠状面上,三维超声成像COL测量方法评估AIS患者椎体侧凸角度具有较高的评测者内和评测者间信度(ICC[2,K]0.9,P0.05)。三维超声成像COL测量方法和MRI成像Cobb测量方法评估AIS椎体侧凸角度的结果之间没有显著性差异(P0.05);两种测量方法具有较高的相关性(r0.9)。结论:三维超声成像技术可用于评估AIS患者椎体在冠状面上的侧凸角度,具有较高的信度和效度。     

Emergency Room Use of “Fast-Track” Ultrasound in Acute Stroke: An Observational Study

Early information on vascular status in acute stroke is essential. We analyzed whether duplex ultrasound (DUS) using a fast-track protocol provides this information without relevant delay. One hundred forty-six patients were prospectively enrolled. DUS was performed by sonographers with two levels of experience. The carotid and vertebral arteries, as well as all basal cerebral arteries, were bilaterally analyzed. Criteria for vessel analysis were (i) normal or stenosis <50%, (ii) stenosis ≥50% and (iii) occlusion. The mean duration of the ultrasound investigation was 6:07 ± 2:06 min with a significant difference between more and less experienced investigators (p < 0.0001). Insonation times decreased during the study in both groups. The sensitivity, specificity, positive predictive value and negative predictive value of ultrasound findings in comparison with computed tomography angiography were 73%, 99%, 84% and 98%, respectively. Our data suggest that “fast track” DUS is feasible and reliable. The time required for DUS assessment depends on the sonographer´s experience.     

An anthropomorphic tissue-mimicking phantom of the oesophagus for endoscopic ultrasound

This study details the design and construct of an anthropomorphic phantom of the oesophagus suitable for use with endoscopic ultrasound (EUS) and 3-D volume measurements. The phantom was constructed using agar-based tissue-mimicking material (TMM) of different acoustical properties to simulate various anatomical and pathologic features. The acoustical properties were measured with a scanning acoustical macroscope. An Olympus GF-UM200 echo-endoscope and digital position measurement arm were used to scan the phantom at 7.5 and 12 MHz. Comparative dimensional measurements were performed on the phantom via 2-D and 3-D EUS. TMM attenuation varied between 0.1 and 0.5 dB/cm.MHz. Backscatter power, relative to normal TMM, was from 0 to -12.2 dB, with an average speed of sound of 1537 +/- 1.9 m/s. Measurements of objects within the phantom by 2-D and 3-D EUS had mean errors of 8% and 2.2%, respectively. The construction of the anthropomorphic EUS phantom facilitated EUS training and research and development studies.     

Three-dimensional Ultrasound Quantification of Intensive Statin Treatment of Carotid Atherosclerosis

This study was designed to evaluate 3-D ultrasound (3DUS)–derived vessel wall volume (VWV), a 3-D measurement of the carotid artery intima and media, including atherosclerotic plaque, in patients enrolled in a randomized placebo-controlled three-month study of intensive atorvastatin treatment. Thirty-five subjects with carotid stenosis >60% who provided written informed consent and completed a randomized, double-blind, placebo-controlled study were evaluated at baseline and at three months after receiving either 80 mg atorvastatin (16 subjects, nine male, mean age 68 ± 8.6 y) or placebo (19 subjects, 15 male, mean age 70 ± 9.4 y) daily. 3DUS images were acquired and 3DUS VWV was manually segmented by a single observer. Individual lumen and wall segmentation contours were also used to generate carotid atherosclerosis thickness difference maps by establishing correspondence between points along the vessel wall and lumen segmentation contour surfaces, and digitally subtracting registered baseline and follow-up thickness maps. 3DUS VWV increased by 70 ± 140 mm³ (+4.9 ± 10.3%) in the placebo group and decreased by 30 ± 110 mm³ (-1.4 ± 7.7%) in the atorvastatin group (p < 0.05). Two-dimensional maps generated from the VWV measurements show localized heterogeneity and vessel wall thickness changes for all subjects, mainly in the common carotid artery. Carotid 3DUS VWV is a quantitative measure of atherosclerosis burden including the intima, media and plaque, with sensitivity to detect changes over short periods of time. Quantitative VWV thickness difference maps provide visual evidence of the spatial and temporal dynamics of carotid artery changes. (E-mail: gep@imaging.robarts.ca)     

Comparison of B‐Mode Ultrasound, 3‐Dimensional Ultrasound,and Magnetic Resonance Imaging Measurements of Carotid Atherosclerosis

Objective. We compared the intraobserver and interscan variability of carotid atherosclerosis measured using B‐mode ultrasound for quantifying intima media thickness (IMT), 3‐dimensional ultrasound (3DUS) for quantifying vessel wall volume (VWV) and total plaque volume (TPV), and magnetic resonance imaging (MRI) for measuring VWV. We also evaluated the associations of these measurements and sample sizes required to detect specific changes in patients with moderate atherosclerosis. Methods. Ten patients were evaluated with B‐mode ultrasound, MRI, and 3DUS twice within 14 ± 2 days. Measurements of IMT, MRI VWV, 3DUS VWV, and 3DUS TPV were performed by single observers using manual (VWV and TPV) and semiautomated (IMT) segmentation. Results. Intraobserver coefficients of variation were 3.4% (IMT), 4.7% (3DUS VWV), 6.5% (MRI VWV), and 23.9% (3DUS TPV). Interscan coefficients of variation were 8.1% (MRI VWV), 8.9% (IMT), 13.5% (3DUS VWV), and 46.6% (3DUS TPV). Scan‐rescan linear regressions were significant for 3DUS TPV (R² = 0.57), 3DUS VWV (R² = 0.59), and IMT (R² = 0.75) and significantly different (P < .05) for MRI VWV (R² = 0.87). Conclusions. B‐mode ultrasound‐derived IMT provided the highest intraobserver and interscan reproducibility. Three‐dimensional measurements of VWV derived from 3DUS and MRI provided both high sensitivity and high intraobserver and interscan reliability.     

Flow Patterns in Carotid Bifurcation Models Using Pulsed Doppler Ultrasound: Effect of Concentric vs. Eccentric Stenosis on Turbulence and Recirculation

Hemodynamics play a significant role in stroke risk, where thrombus formation may be accelerated in regions of slow or recirculating flow, high shear and increased turbulence. An in vitro investigation was performed with pulsed Doppler ultrasound (DUS) using the complete spectral data to investigate the three-dimensional (3-D) distribution of advanced parameters that may have potential for making a more specific in vivo diagnosis of carotid disease and stroke risk. The effect of stenosis symmetry and the potential of DUS spectral parameters for visualizing regions of recirculation or turbulence were explored. DUS was used to map pulsatile flow in four model geometries representing two different plaque symmetries (eccentricity) and two stenosis severities (mild, severe). Qualitative comparisons were made with flow patterns visualized using digital particle imaging. Color-encoded maps of DUS spectral parameters (mean velocity, spectral-broadening index and turbulence intensity) clearly distinguished regions of slow or recirculating flow and disturbed or turbulent flow. Distinctly different flow patterns resulted from stenoses of equal severity but different eccentricity. Noticeable differences were seen in both the size and location of recirculation zones and in the paths of high-velocity jets. Highly elevated levels of turbulence intensity were seen distal to severe stenosis. Results demonstrated the importance of plaque shape, which is typically not considered in standard diagnosis, in addition to stenosis severity. (E-mail: poepping@uwo.ca).     

Functional assessment of high-grade ICA stenosis with duplex ultrasound and transcranial Doppler

Background: Duplex ultrasound (DUS) has shown a >90% accuracy compared to angiography, concerning the degree of internal carotid artery (ICA) stenosis. However, uncertainty may occur in a severe stenosis, in which peak systolic velocity (PSV) may decrease owing to high flow resistance or high backward pressure. We investigated intracranial collateral flows using transcranial Doppler (TCD) to further evaluate the hemodynamic significance of high‐grade ICA stenosis. Methods: In this retrospective study, 320 consecutive symptomatic patients were examined. The degree of ICA stenosis and collateral capacity in the circle of Willis was investigated by DUS and TCD. In addition, magnetic resonance angiography (MRA) was added in a subgroup of 204 patients. The criterion for hemodynamic significant ICA stenosis was established collateral flow. Results: In 91% of all symptomatic vessels (291 vessels), an ICA stenosis of ≥70% was found. Established collateral flow always indicated precerebral carotid artery disease of ≥70%. Furthermore, in 11% of the whole study material, collateral reserve capacity was found despite high‐grade (≥70%) ICA stenosis. PSV in ICA <2·5 m s^?1 was combined with established collateral flow and MRA stenosis of ≥70% in 9% (19 arterial systems). In 4%, doubt existed concerning the degree of stenosis after DUS. Conclusion: Transcranial Doppler helps to determine whether an ICA stenosis is of hemodynamic significance and to assess collateral patterns. Established collateral blood flow will help to identify patients with ≥70% (ECST) carotid artery disease. TCD might be of value when flow velocity criteria combined with plaque assessment by DUS are inclusive. Other diagnostic methods may also be considered.     

Effects of ultrasound on maternal-fetal bonding: a comparison of two- and three-dimensional imaging.

OBJECTIVES: The purpose of this study was to evaluate the effect of two-dimensional (2DUS) compared to three-dimensional ultrasound (3DUS) imaging on the maternal-fetal bonding process. METHODS: Fifty mothers who had 2DUS and 50 who had 2DUS and 3DUS were included in the study. A postpartum survey by telephone interview was carried out to assess maternal-fetal bonding. Bonding was evaluated by analysis of extent of prenatal image sharing, maternal ability to form a mental picture of the baby and mother's comments about their ultrasound images. Data were analyzed using the independent t-test, Chi-square and Mann-Whitney U-tests. RESULTS: Mothers who received 3DUS showed their ultrasound images to more people (median, 27.5; interquartile range, 14.5-40.0) than mothers receiving 2DUS alone (median, 11.0; interquartile range, 5.0-25.5) (P < 0.001, Z = -3.539). Eighty-two percent of the subjects screened with 3DUS had a greater tendency to form a mental picture of the baby postexamination compared to 39% of the 2DUS subjects (P < 0.001, Z = -3.614). Mothers receiving a 3DUS study were more likely to receive comments on the similarities/differences of the neonate compared to those having 2DUS studies. Furthermore, 70% of the mothers receiving 3DUS felt they 'knew' the baby immediately after birth vs. 56% of the mothers receiving 2DUS (P = 0.009, Z = -2.613). Both 2DUS and 3DUS experiences were positive, however, the comments made by the mothers undergoing 3DUS (n = 18) were more exclamatory (amazed, wonderful, fabulous) than those undergoing 2DUS (n = 4). Patients having a 3DUS examination consistently scored higher than those having a 2DUS examination alone for all categories of maternal-fetal bonding. CONCLUSION: 3DUS appears to more positively influence the perceptions of mothers to their babies postbirth compared to 2DUS. Specifically, mothers who had 3DUS showed their ultrasound images to a greater number of people compared to mothers who had 2DUS alone and this may represent mother's social support system. 3DUS may have a greater impact on the maternal-fetal bonding process.     

Three‐ and 4‐Dimensional Ultrasound in Obstetric Practice

OBJECTIVE: The purpose of this article was to review the published literature on 3-dimensional ultrasound (3DUS) and 4-dimensional ultrasound (4DUS) in obstetrics and determine whether 3DUS adds diagnostic information to what is currently provided by 2-dimensional ultrasound (2DUS) and, if so, in what areas. METHODS: A PubMed search was conducted for articles reporting on the use of 3DUS or 4DUS in obstetrics. Seven-hundred six articles were identified, and among those, 525 were actually related to the subject of this review. Articles describing technical developments, clinical studies, reviews, editorials, and studies on fetal behavior or maternal-fetal bonding were reviewed. RESULTS: Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, especially facial clefts. There is also evidence that 3DUS provides additional diagnostic information in neural tube defects and skeletal malformations. Large studies comparing 2DUS and 3DUS for the diagnosis of congenital anomalies have not provided conclusive results. Preliminary evidence suggests that sonographic tomography may decrease the examination time of the obstetric ultrasound examination, with minimal impact on the visualization rates of anatomic structures. CONCLUSIONS: Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical role of 3DUS and 4DUS for the diagnosis of congenital heart disease and central nervous system anomalies. Future studies should determine whether the information contained in the volume data set, by itself, is sufficient to evaluate fetal biometric measurements and diagnose congenital anomalies.     

Artificial Intelligence-Powered Measurement of Left Ventricular Ejection Fraction Using a Handheld Ultrasound Device

The aim of this study was to assess the accuracy of an algorithm for automated measurement of left ventricular ejection fraction (LVEF) available on handheld ultrasound devices (HUDs). One hundred twelve patients admitted to the cardiology department underwent assessment performed with an HUD. In each case, the four-chamber apical view was obtained, and LVEF was calculated with LVivo software. Subsequently, during the examination performed with the use of the stationary echocardiograph, the 3-D measurement of LVEF was recorded. The average LVEFs measured with LVivo and the 3-D reference method were 46 ± 14% and 48 ± 14%, respectively. The correlation between the measurements obtained with the HUD and 3-D evaluation was high (r = 0.92, 95% confidence interval: 0.87–0.95, p < 0.0001). The mean difference between the LVEF obtained with LVivo and the 3-D LVEF was not significant (mean difference: –0.61%, 95% confidence interval: –1.89 to 0.68, p = 0.31). The LVivo software despite its limitations is capable of the accurate LVEF measurement when the acquired views are of at least good imaging quality.     

Reliability of Human Achilles Tendon Stiffness Measures Using Freehand 3-D Ultrasound

Achilles tendon (AT) stiffness is an important property of both human locomotor performance and injury mechanics. Freehand 3-D ultrasound (3-DUS) is a promising method for measuring stiffness of the Achilles tendon, particularly the free AT (2–6 cm proximal to calcaneus), which is commonly injured. The aim of this study was to investigate the test–retest reliability of freehand 3-DUS in measuring free AT stiffness in humans. The free Achilles tendon length of healthy participants (n = 10) was scanned on the same day on two consecutive occasions (1 h apart) during rest and isometric plantar flexion contractions at 20%, 40% and 60% of maximum force. The slope of the force–elongation curve over these force levels represented individual stiffness (N/mm). Relative reliability was assessed using the intra-class correlation coefficient (ICC), and absolute reliability was estimated with the standard error of measurement (SEM) and smallest detectable change. Systematic bias in stiffness measures was explored by comparing test and retest distributions and Bland–Altman plots. The test–retest reliability of free AT stiffness measured using freehand 3-DUS was excellent [ICC = 0.994, 95% confidence interval [CI]: 0.978–0.999)]. The mean stiffness values at test (361.83 N/mm [170.77]) and retest (364.98 N/mm [168.57]) did not significantly differ (p = 0.72), and the smallest detectable change was 52.14 N/mm. The Bland–Altman plot indicated the absence of systematic bias (95% CI: –22.18 to 15.88). Freehand 3-DUS provides reliable and precise measures of tendon stiffness and can be used to detect small changes in free AT stiffness in response to load or tendon pathology.     

In vitro measurement of muscle volume with 3-dimensional ultrasound.

The aim was to test the accuracy of muscle volume measurements with a new 3-dimensional (3-D) ultrasound system, which allows a freehand scanning of the transducer with an improved quality of the ultrasound images and therefore the outlines of the muscles. Five resected cadaveric hand muscles were insonated and the muscle volumes calculated by 3-D reconstructions of the acquired 2-D ultrasound sections. Intra-reader, inter-reader and follow-up variability were calculated, as well as the volume of the muscle tissue measured by water displacement. In the results, 3-D ultrasound and water displacement measurements showed an average deviation of 10.1%; Data of 3-D ultrasound measurements were: intra-reader variability 2.8%; inter-reader variability 2.4% and follow-up variability 2.3%. 3-D measurements of muscle volume are valid and reliable. Serial sonographic measurements of muscle may be able to quantitate changes in muscle volume that occur in disease and recovery.