Prenatal three-dimensional ultrasound: perception of sonographers, sonologists and undergraduate students.

OBJECTIVE: To assess the perception of non-pregnant sonographers, sonologists and undergraduate students on the use of three-dimensional (3D) ultrasound technology in fetal medicine. METHODS: This was a study of two groups of non-pregnant subjects. Group I included 520 (305 female, 215 male) medical professionals who completed a questionnaire after attending a lecture on 3D imaging. Factors such as gender, career and having children were analyzed with respect to the attendee's responses about use of 3D ultrasound for medical purposes and for reassurance. Group II included 137 (75 female, 60 male, two unknown) undergraduate students from bioengineering, psychology and physiology classes who completed a questionnaire after attending a brief presentation on two-dimensional and 3D fetal imaging. Factors such as gender and area of educational interest were analyzed with respect to the students' responses about the use of 3D ultrasound for medical purposes and for parental-fetal attachment. RESULTS: In Group I, 63% said that they would like to have a 3D ultrasound examination in the future, while 14% said that they would not. Common reasons given for wanting a 3D ultrasound exam in the future were for medical purposes (39%) or reassurance (18%). The main differences perceived between two-dimensional (2D) and 3D ultrasound were medical advantages (65%) and parental reassurance (28%). 62.4% of Group I thought 3D technology should be in wide use in obstetric ultrasound and 73.6% thought that 3D ultrasound would reassure parents carrying normal fetuses. Gender, age and career did not have a significant influence on perception of 3D ultrasound. In Group II, the majority (91%) said they could see a remarkable difference between 2D and 3D ultrasound. 83% responded that they would like to have a 3D ultrasound examination of their own baby in the future for the following reasons: 34% for the detailed picture, 31% for increased abnormality detection, 13% for reassurance or curiosity; 8% thought it would be unnecessary or a negative experience. Concerning parental-fetal attachment, 72% thought 3D ultrasound would have a positive effect. The majority of Group II (93%) thought 3D ultrasound would be valuable and 56% thought 3D ultrasound would assist in diagnosing fetal abnormalities. There was no significant relationship between gender, age or area of interest and the perception of 3D ultrasound. CONCLUSIONS: Responses by sonographers and physicians suggest that 3D ultrasound will have a role in the future for medical indications and in reassuring patients carrying normal fetuses. Our results also suggest that undergraduate students believe that 3D ultrasound will be a valuable technique in obstetrics and that it will have a positive effect on parental-fetal attachment.

Gigahertz modulation of GaAs-based bipolar cascade vertical cavity surface-emitting lasers.

The high-frequency modulation characteristics of GaAs-based bipolar cascade vertical cavity surface-emitting lasers operating at 980 nm with GaAs tunnel junctions and p-doped Al0.98Ga0.02As oxide apertures have been measured. We achieve -3 dB laser output modulations of 6.5 GHz for two-stage and 9.4 GHz for three-stage devices in response to small-signal current injection at an operating temperature of -50 degrees C.

Observation of nonlinear optical phenomena in air and fused silica using a 100 GW, 1.54 mum source.

A 100-GW optical parametric chirped-pulse amplifier system is used to study nonlinear effects in the 1.54 mum regime. When focusing this beam in air, strong third-harmonic generation (THG) is observed, and both the spectra and efficiency are measured. Broadening is observed on only the blue side of the third-harmonic signal and an energy conversion efficiency of 0.2% is achieved. When propagated through a 10-cm block of fused silica, a collimated beam is seen to collapse and form multiple filaments. The measured spectral features span 400-2100 nm. The spectrum is dominated by previously unobserved Stokes emissions and broad emissions in the visible.

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.

A comprehensive analysis of DgN(CT) coefficients for pendant-geometry cone-beam breast computed tomography.

The use of a computed tomography (CT) scanner specifically designed for breast imaging has been proposed by several investigators. In this study, the radiation dose due to breast CT was evaluated using Monte Carlo techniques over a range of parameters pertinent to the cone-beam pendant geometry thought to be most appropriate. Monte Carlo dose computations were validated by comparison with physical measurements made on a prototype breast CT scanner under development in our laboratory. The Monte Carlo results were then used to study the influence of cone angle, the use of a beam flattening ("bow-tie") filter, glandular fraction, breast length and source-to-isocenter distance. These parameters were studied over a range of breast diameters from 10 to 18 cm, and for both monoenergetic (8-140 keV by 1 keV intervals) and polyenergetic x-ray beams (30-100 kVp by 5 kVp intervals. Half value layer at 80 kVp = 5.3 mm Al). A parameter referring to the normalized glandular dose in CT (DgN(CT)) was defined which is the ratio of the glandular dose in the breast to the air kerma at isocenter. There was no significant difference (p = 0.743) between physically measured and Monte Carlo derived results. Fan angle, source-to-isocenter distance, and breast length have relatively small influences on the radiation dose in breast CT. Glandular fraction (0% versus 100%) for 10 cm breasts at 80 kVp had approximately a 10% effect on DgN(CT), and a 20% effect was observed for an 18 cm breast diameter. The use of a bow-tie filter had the potential to reduce breast dose by approximately 40%. X-ray beam energy and breast diameter had significant influence on the DgN(CT) parameters, with higher DgN(CT) values for higher energy beams and smaller breast diameters. DgN(CT) values (mGy/mGy) at 80 kVp ranged from 0.95 for an 8 cm diam 50% glandular breast to 0.78 for an 18 cm 50% glandular breast. The results of this investigation should be useful for those interested computing the glandular breast dose for geometries relevant to dedicated breast CT.

Time-resolved measurements of self-focusing pulses in air.

The spatial, spectral, and temporal properties of self-focusing 798-nm 100-fs pulses in air are experimentally measured with high-resolution, single-shot techniques at a set propagation distance of 10.91 m. The data, obtained with an initially collimated Gaussian beam, show significant evolution of spatial narrowing as well as temporal and spectral changes at intensities lower than those required for significant ionization of air.

Potential of three-dimensional ultrasound in neonatal and paediatric neurosonography.

The aim of this study was to describe the potential of three-dimensional ultrasound (3D US) in paediatric and neonatal neurosonography. The potential applications are illustrated based on our experience in 150 patients using three different 3D US techniques at two different sites. Various disease entities throughout the paediatric age have been evaluated. The potential of 3D US, including 3D US of the cerebral vessels based on colour Doppler data, is discussed based on comparison with conventional 2D US or other imaging (as available), and with regard to the literature. In our experience, 3D US is feasible in neonatal and paediatric neurosonography. It reduces imaging time, improves demonstration of complex anatomy and vasculature, and allows for evaluation of anatomy/pathology in any plane. The 3D US furthermore improves volume assessment (e.g. in hydrocephalus), and comparison with CT, MRI and during follow-up, with a potentially improved standardisation and documentation. The 3D US additionally offers an ideal modality for training and education, as the brain and the neonatal spine can be virtually rescanned at the workstation. Yet, limitations such as areas inaccessible to 2D US, limited resolution and motion artefacts have to be acknowledged. Three-dimensional US has the potential to become a valuable additional imaging tool in paediatric neurosonography.

Dedicated breast CT: radiation dose and image quality evaluation.

PURPOSE: To evaluate the feasibility of breast computed tomography (CT) in terms of radiation dose and image quality. MATERIALS AND METHODS: Validated Monte Carlo simulation techniques were used to estimate the average glandular dose (AGD). The calculated photon fluence at the detector for high-quality abdominal CT (120 kVp, 300 mAs, 5-mm section thickness) was the benchmark for assessing the milliampere seconds and corresponding radiation dose necessary for breast CT. Image noise was measured by using a 10-cm-diameter cylinder imaged with a clinical CT scanner at 10-300 mAs for 80, 100, and 120 kVp. A cadaveric breast was imaged in the coronal plane to approximate the acquisition geometry of a proposed breast CT scanner. RESULTS: The AGD for 80-kVp breast CT was comparable to that for two-view mammography of 5-cm breasts (compressed breast thickness). For thicker breasts, the breast CT dose was about one-third less than that for two-view mammography. The maximum dose at mammography assessed in 1-mm(3) voxels was far higher (20.0 mGy) than that at breast CT (5.4 mGy) for a typical 5-cm 50% glandular breast. CT images of an 8-cm cadaveric breast (AGD, 6.3 mGy) were subjectively superior to digital mammograms (AGD, 10.1 mGy) of the same specimen. CONCLUSION: The potential of high signal-to-noise ratio images with low anatomic noise, which are obtainable at dose levels comparable to those for mammography, suggests that dedicated breast CT should be studied further for its potential in breast cancer screening and diagnosis.

Feasibility of performing a virtual patient examination using three-dimensional ultrasonographic data acquired at remote locations.

OBJECTIVE: To evaluate the feasibility of performing three-dimensional ultrasonographic studies that meet American Institute of Ultrasound in Medicine and American College of Radiology ultrasonographic examination guidelines with review off-line and at remote locations. METHODS: One hundred patients were studied at 2 institutions using high-end two-dimensional clinical ultrasonographic scanners and commercially available three-dimensional ultrasonography for a variety of organ systems (first- and second-trimester fetus, abdomen, and female pelvis). We evaluated several parameters, including measurements, completeness of organ visualization, abnormalities identified, image quality, number of volumes required, and discrepancies between interpretations. RESULTS: Overall, three-dimensional ultrasonography could produce diagnostic-quality results comparable with those of two-dimensional ultrasonography. Three-dimensional ultrasonographic image quality was lower than that of two-dimensional ultrasonography. Two- and three-dimensional ultrasonographic measurements were comparable (<5% difference), as was the extent of organ visualization, although some structures were challenging for both two- and three-dimensional ultrasonography. In general, organs completely imaged in the scanner field of view required 1 to 1.5 volumes, whereas larger organs required between 3 and 6 volumes. Differences among reviewers' interpretations highlighted the need for standardization of acquisition and reviewing protocols for sonographers and physicians. CONCLUSIONS: Our results show that it is clinically feasible to acquire three-dimensional ultrasonographic data at one site and to obtain accurate interpretation by off-line review at another within the context of providing high-quality clinical diagnostic studies.

Three-dimensional ultrasound in obstetrics and gynecology.

Three-dimensional ultrasound is a new modality finding its way into clinical practice. Most of the major ultrasound vendors are now developing three-dimensional ultrasound capabilities. We expect that although three-dimensional ultrasound will not replace two-dimensional ultrasound, many additional benefits will be identified and its use will continue to grow. The ability to evaluate anatomy and pathology with multiplanar and surface-rendered images provides physicians additional valuable clinical information. Volume data allows for a specific point in space to be evaluated from many different orienta tions by rotating, slicing, and referencing the slice to other orthogonal slices. It also allows for new volume-rendering displays that show depth, curvature, and surface images not available with conventional methods. The current limitations of image resolution, intuitive interfaces for obtaining and displaying optimal images, and technologic limitations for data storage and manipulation (including real-time three-dimensional ultrasound) will surely be overcome in the near future.

Value of three-dimensional US for optimizing guidance for ablating focal liver tumors.

PURPOSE: To determine if three-dimensional ultrasound (3D US), by nature of its ability to simultaneously evaluate structures in three orthogonal planes and to study relationships of devices to tumor(s) and surrounding anatomic structures from any desired orientation, adds significant additional information to real-time 2D US used for placement of devices for ablation of focal liver tumors. MATERIALS AND METHODS: Sixteen patients underwent focal ablation of 23 liver tumors during two intraoperative cryoablation (CA) procedures, three intraoperative radiofrequency ablation (RFA) procedures, 11 percutaneous ethanol injections (PEI) procedures, and six percutaneous RFA procedures. After satisfactory placement of the ablative device(s) with 2D US guidance, 3D US was used to reevaluate adequacy to device position. Information added by 3D US and resultant alterations in device deployment were tabulated. RESULTS: 3D US added information in 20 of 22 (91%) procedures and caused the operator to readjust the number or position of ablative devices in 10 of 22 (45%) of procedures. Specifically, 3D US improved visualization and confident localization of devices in 13 of 22 (59%) procedures, detected unacceptable device placement in 10 of 22 (45%), and determined that 2D US had incorrectly predicted device orientation to a tumor in three of 22 (14%). CONCLUSIONS: Compared to conventional 2D US, 3D US provides additional relationship information for improved placement and optimal distribution of ablative agents for treatment of focal liver malignancy.

Fetal lip and primary palate: three-dimensional versus two-dimensional US.

PURPOSE: To determine if three-dimensional (3D) ultrasonography (US) improves the ability to define the location and extent of facial clefting prenatally compared with two-dimensional (2D) US. MATERIALS AND METHODS: Thirty-one fetuses suspected of having a facial cleft were examined prospectively with 2D and 3D US. Follow-up was performed in all fetuses. RESULTS: Twenty-eight fetuses had a cleft lip at birth. The location of the cleft lip was correctly identified in all fetuses with 3D US and in 26 of 28 with 2D US. Twenty-two fetuses had a cleft primary palate. Nineteen and nine of 22 cleft palates were identified by using 3D and 2D US, respectively. Three fetuses suspected of having a facial cleft at 2D US had a normal palate at 3D US and at birth. CONCLUSION: Three-dimensional US is useful to identify the location and extent of facial clefting. The advantages of 3D US are the following: (a) The face may be viewed in a standard orientation, (b) the defect may be viewed systematically by using an interactive display, and (c) the rendered image provides landmarks for the planar images. Patient decisions may be affected, since they can view the abnormality on a recognizable 3D rendered image.

Three-dimensional ultrasonographic imaging of the neonatal brain in high-risk neonates: preliminary study.

The aim of this investigation was to compare the utility of three-dimensional ultrasonography versus two-dimensional ultrasonography in imaging the neonatal brain. Thirty patients in the neonatal intensive care unit underwent two-dimensional and three-dimensional ultrasonography. The resultant two- and three-dimensional images recorded on film and three-dimensional volumes (reviewed on a workstation) were evaluated independently. Comparable numbers of normal and abnormal studies were diagnosed by each modality. Axial images were considered useful in approximately 50% of three-dimensional cases. Image quality, overall and in the far-field, was rated higher on two-dimensional images. Three-dimensional sonographic acquisition time in the neonatal intensive care unit (1.7 min+/-0.7 standard deviation) was significantly shorter than that for two-dimensional sonography (9.0+/-4.5 min). The total time for evaluation on the three-dimensional workstation (4.4+/-1.1 min) was significantly less than that for two-dimensional images on film (10.6+/-4.7 min). In conclusion, three-dimensional ultrasonography is a promising, diagnostically accurate, and efficient imaging tool for evaluation of the neonatal brain; however, visualization must improve before it can replace two-dimensional ultrasonography.

Adjunctive 3D US for achieving portal vein access during transjugular intrahepatic portosystemic shunt procedures.

PURPOSE: To evaluate the usefulness of information provided by three-dimensional ultrasound (3D US) and to determine whether 3D US decreased the number of passes required to obtain portal vein (PV) access during creation of transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS: Intermittent 3D US volume acquisitions were obtained during creation of TIPS in 20 patients. Useful information provided by 3D US was tabulated. The number of passes required to achieve PV access was recorded and results were compared retrospectively to 25 patients who underwent TIPS without 3D US. RESULTS: 3D US documented that the operator's opinion of which hepatic vein had been selected was incorrect in nine patients (45%), detected unfavorable PV anatomy that required modification of equipment or technique in seven patients (35%), permitted estimation of the trajectory required to access the targeted PV in all patients (100%), assisted in selecting the optimal point along the hepatic vein for origination of the needle pass in 11 patients (55%), allowed avoidance of a large hepatocellular carcinoma in one patient (5%), and confirmed that access into the main PV was intrahepatic in four patients (20%). The mean number of needle passes decreased from 10.4 in the historic control group to 4.6 in the 3D US group (P = .0001). CONCLUSION: 3D US provided imaging information that detected technical errors and altered anatomy, and provided positional and directional information to significantly improve needle pass efficiency.

Adjunctive 3D US for achieving portal vein access during transjugular intrahepatic portosystemic shunt procedures.

PURPOSE: To evaluate the usefulness of information provided by three-dimensional ultrasound (3D US) and to determine whether 3D US decreased the number of passes required to obtain portal vein (PV) access during creation of transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS: Intermittent 3D US volume acquisitions were obtained during creation of TIPS in 20 patients. Useful information provided by 3D US was tabulated. The number of passes required to achieve PV access was recorded and results were compared retrospectively to 25 patients who underwent TIPS without 3D US. RESULTS: 3D US documented that the operator's opinion of which hepatic vein had been selected was incorrect in nine patients (45%), detected unfavorable PV anatomy that required modification of equipment or technique in seven patients (35%), permitted estimation of the trajectory required to access the targeted PV in all patients (100%), assisted in selecting the optimal point along the hepatic vein for origination of the needle pass in 11 patients (55%), allowed avoidance of a large hepatocellular carcinoma in one patient (5%), and confirmed that access into the main PV was intrahepatic in four patients (20%). The mean number of needle passes decreased from 10.4 in the historic control group to 4.6 in the 3D US group (P = .0001). CONCLUSION: 3D US provided imaging information that detected technical errors and altered anatomy, and provided positional and directional information to significantly improve needle pass efficiency.

Fetal skeletal dysplasia: three-dimensional US--initial experience.

PURPOSE: To compare the prenatal ultrasonographic (US) features of skeletal dysplasia by using two-dimensional (2D) and three-dimensional (3D) US to determine whether 3D US can reveal additional diagnostic information. MATERIALS AND METHODS: Seven pregnant women suspected of having skeletal dysplasia were examined by using 2D US and 3D US. Data regarding the thorax, spine, face, limbs, hands, and feet were compared. Multiplanar and volume-rendered US images were evaluated. RESULTS: The skeletal dysplasias studied included camptomelic dysplasia (n = 2), thanatophoric dysplasia (n = 1), osteogenesis imperfecta (n = 1), arthrogryposis (n = 2), and short-limbed dysplasia (n = 1). Three-dimensional US, by allowing review in a standard anatomic orientation, was better than 2D US in depicting abnormal spatial relationships such as short ribs, splayed digits, and absent bones. Three-dimensional US enabled the acquisition of additional information in two fetuses with facial abnormalities and in two fetuses with scapular aplasia or hypoplasia (one fetus had both facial and scapular anomalies); it enabled a specific diagnosis in one fetus. The archiving capabilities of 3D US allow the review and manipulation of data after the patient has left the clinic. CONCLUSION: In three of seven patients, 3D US provided additional information in the evaluation of skeletal dysplasias, as compared with 2D US.