In vivo demonstration of a real-time temporal SNR acoustic output adjustment method.

This work proposes a novel method of temporal signal-to-noise ratio (SNR) guided adaptive acoustic output adjustment and demonstrates this approach during in vivo fetal imaging. Acoustic output adjustment is currently the responsibility of sonographers, but ultrasound safety studies show recommended ALARA (As Low As Reasonably Achievable) practices are inconsistently followed. This study explores an automated ALARA method that adjusts the Mechanical Index (MI) output, targeting imaging conditions matching the temporal noise perception threshold. A 28 dB threshold SNR is used as the target SNR, following prior work showing relevant noise quantities are imperceptible once this image data quality level is reached. After implementing adaptive output adjustment on a clinical system, the average MI required to achieve 28 dB SNR in an eleven-volunteer fetal abdomen imaging test ranged from 0.17 to 0.26. The higher MI levels were required when imaging at higher frequencies. During tests with 20-second MI adjustment imaging periods, the degree of motion impacted the adaptive performance. For stationary imaging views, target SNR levels were maintained in 90% of SNR evaluations. When scanning between targets the imaging conditions were more variable, but the target SNR was still maintained in 71% of the evaluations. Given the relatively low MI recommended when performing MI adjustment and the successful adjustment of MI in response to changing imaging conditions, these results encourage adoption of adaptive acoustic output approaches guided by temporal SNR.

Human Observer Sensitivity to Temporal Noise During B-Mode Ultrasound Scanning: Characterization and Imaging Implications.

This work measures temporal signal-to-noise ratio (SNR) thresholds that indicate when random noise during ultrasound scanning becomes imperceptible to expert human observers. Visible noise compromises image quality and can potentially lead to non-diagnostic scans. Noise can arise from both stable acoustic sources (clutter) or randomly varying electronic sources (temporal noise). Extensive engineering effort has focused on decreasing noise in both of these categories. In this work, an observer study with five practicing sonographers was performed to assess sonographer sensitivity to temporal noise in ultrasound cine clips. Understanding the conditions where temporal noise is no longer visible during ultrasound imaging can inform engineering efforts seeking to minimize the impact this noise has on image quality. The sonographers were presented with paired temporal noise-free and noise-added simulated speckle cine clips and asked to select the noise-added clips. The degree of motion in the imaging target was found to have a significant effect on the SNR levels where noise was perceived, while changing imaging frequency had little impact. At realistic in vivo motion levels, temporal noise was not perceived in cine clips at and above 28 dB SNR. In a case study presented here, the potential of adaptive intensity adjustment based on this noise perception threshold is validated in a fetal imaging scenario. This study demonstrates how noise perception thresholds can be applied to help design or tune ultrasound systems for different imaging tasks and noise conditions.

Validation of a sonographic checklist for the detection of histologic placenta accreta spectrum.

BACKGROUND: To standardize research terminology and to reduce unanticipated placenta accreta spectrum, the European Working Group for Abnormally Invasive Placenta developed a consensus checklist for reporting suspected placenta accreta spectrum observed during an antenatal ultrasound. The diagnostic accuracy of the European Working Group for Abnormally Invasive Placenta checklist has not been assessed. OBJECTIVE: This study aimed to test the performance of the European Working Group for Abnormally Invasive Placenta sonographic checklist in predicting histologic placenta accreta spectrum. STUDY DESIGN: This was a multisite, blinded, retrospective review of transabdominal ultrasound studies performed between 26 to 32 weeks' gestation for subjects with histologic placenta accreta spectrum between 2016 and 2020. We matched a control cohort of subjects without histologic placenta accreta spectrum in a 1:1 ratio. To reduce reader bias, we matched the control cohort for known risk factors including previa, number of previous cesarean deliveries, previous dilation and curettage, in vitro fertilization, and clinical factors affecting image quality including multiple gestation, body mass index, and gestational age at the ultrasound. Nine sonologists from 5 referral centers, blinded to the histologic outcomes, interpreted the randomized ultrasound studies using the European Working Group for Abnormally Invasive Placenta checklist. The primary outcome was the sensitivity and specificity of the checklist to predict placenta accreta spectrum. Two separate sensitivity analyses were performed. First, we excluded subjects with mild disease (ie, only assessed subjects with histologic increta and percreta). Second, we excluded interpretations from the 2 most junior sonologists. RESULTS: A total of 78 subjects were included (39 placenta accreta spectrum, 39 matched control). Clinical risk factors and image quality markers were statistically similar between the cohorts. The checklist sensitivity (95% confidence interval) was 76.6% (63.4-90.6) and the specificity (95% confidence interval) was 92.0% (63.4-99.9) with a positive and negative likelihood ratio of 9.6 and 0.3, respectively. When we excluded subjects with mild placenta accreta spectrum disease, the sensitivity (95% confidence interval) increased to 84.7% (73.6-96.4) and the specificity was unchanged at 92.0% (83.2-99.9). Sensitivity and specificity were unchanged when the interpretations from the 2 most junior sonologists were excluded. CONCLUSION: The 2016 European Working Group for Abnormally Invasive Placenta checklist for interpreting placenta accreta spectrum has a reasonable performance in detecting histologic placenta accreta spectrum and excluding cases without placenta accreta spectum.

The Role of Perinatal Palliative Care in Fetal Neurology.

OBJECTIVES: Many serious or life-threatening neurologic conditions are first diagnosed during the fetal period, often following a routine ultrasound or sonographic evaluation after an abnormal aneuploidy screen. Such conditions represent a worrisome or unexpected finding for expectant parents, making the perinatal period a critical time point to engage and empower families encountering complex neurologic clinical scenarios. This review covers the role of perinatal palliative care in these settings. STUDY DESIGN: This study is a topical review RESULTS: The prenatal identification of structural abnormalities of the brain or spinal cord, radiographic signs of hemorrhage or ischemic injury, or evidence of genetic or metabolic conditions should prompt involvement of a fetal palliative care team. The inherent prognostic uncertainty is challenging for prenatally diagnosed neurologic conditions which have difficult to predict short and long-term outcomes. While many of these conditions lead to the birth of an infant with neurodevelopmental challenges, few result in in utero demise. Palliative care beginning in the perinatal period provides an additional layer of support for families navigating complex decision-making during their pregnancy and provides continuity of care into the newborn period. Palliative care principles can help guide discussions around genetic and other diagnostic testing, fetal surgery, and birth planning. A multidisciplinary team can help support families with decision-making and through bereavement care in the setting of fetal or neonatal death. CONCLUSION: Early palliative care team involvement can provide a more holistic approach to counseling, facilitate planning, and ensure that a family's goals and wishes are acknowledged throughout an infant's care trajectory. KEY POINTS: · Many serious or life-threatening neurologic conditions are diagnosed during the fetal period.. · Palliative care principles should be incorporated in the fetal period for affected patients.. · Palliative care clinicians can aid parents and clinicians in shared decision-making.. · Palliative care principles should be employed by all care providers in relevant cases..

An Automated Region-Selection Method for Adaptive ALARA Ultrasound Imaging.

The objective of this work was to develop an automated region of the interest selection method to use for adaptive imaging. The as low as reasonably achievable (ALARA) principle is the recommended framework for setting the output level of diagnostic ultrasound devices, but studies suggest that it is not broadly observed. One way to address this would be to adjust output settings automatically based on image quality feedback, but a missing link is determining how and where to interrogate the image quality. This work provides a method of region of interest selection based on standard, envelope-detected image data that are readily available on ultrasound scanners. Image brightness, the standard deviation of the brightness values, the speckle signal-to-noise ratio, and frame-to-frame correlation were considered as image characteristics to serve as the basis for this selection method. Region selection with these filters was compared to results from image quality assessment at multiple acoustic output levels. After selecting the filter values based on data from 25 subjects, testing on ten reserved subjects' data produced a positive predictive value of 94% using image brightness, the speckle signal-to-noise ratio, and frame-to-frame correlation. The best case filter values for using only image brightness and speckle signal-to-noise ratio had a positive predictive value of 97%. These results suggest that these simple methods of filtering could select reliable regions of interest during live scanning to facilitate adaptive ALARA imaging.

Management of Preterm Premature Rupture of Membranes in the Late Preterm Period.

Importance: For patients who present with prelabor rupture of membrane (PROM) in the late preterm period (34 to 36 6/7 weeks), management remains unclear due to lack of consensus. However, recent guidelines have suggested that shared decision-making may be used and expectant management can be considered up to 37 0/7 weeks. Objective: In this article, we review the contemporary studies comparing the risks and benefits of immediate delivery versus expectant management for patients with late preterm prelabor rupture of membranes (PPROM). Evidence Acquisition: Original research articles, review articles, and guidelines on management of late PPROM. Results: Three randomized clinical trials and 2 meta-analyses comparing expectant management and immediate delivery outcomes in late PPROM showed no significant difference in neonatal sepsis rates between groups. Expectant management increased the likelihood that pregnancies reached term while decreasing the rate of cesarean delivery. However, data suggest an increased risk of antepartum hemorrhage among patients in the expectant management groups, as well as higher rates of histologic chorioamnionitis. Conclusions and Relevance: We recommend that clinicians offer expectant management as an alternative to immediate delivery in the setting of late PPROM through a shared decision-making process that clearly outlines the risks and benefits.

A prospective blinded comparison of second trimester fetal measurements by expert and novice readers using low-cost novice-acquired 3D volumetric ultrasound.

RATIONALE AND OBJECTIVES: Two-dimensional (2D) ultrasound (US) is operator dependent, requiring operator skill and experience to selectively identify and record planes of interest for subsequent interpretation. This limits the utility of US in settings in which expert sonographers are unavailable. Three-dimensional (3D) US acquisition of an anatomic target, which enables reconstruction of any plane through the acquired volume, might reduce operator dependence by providing any desired image plane for interpretation, without identification of target planes of interest at the time of acquisition. We applied a low-cost 3DUS technology because of the wider potential application compared with dedicated 3DUS systems. We chose second trimester fetal biometric parameters for study because of their importance in maternal-fetal health globally. We hypothesized that expert and novice interpretations of novice-acquired 3D volumes would not differ from each other nor from expert measurements of expert-acquired 2D images, the clinical reference standard. MATERIALS AND METHODS: This was a prospective, blinded, observational study. Expert sonographers blinded to 3DUS volumes acquired 2DUS images of second trimester fetuses from 32 subjects, and expert readers performed interpretation, during usual care. A novice sonographer blinded to other clinical data acquired oriented 3DUS image volumes of the same subjects on the same date. Expert readers blinded to other data assessed placental location (PL), fetal presentation (FP), and amniotic fluid volume (AFV) in novice-acquired 3D volumes. Novice and expert raters blinded to other data independently measured biparietal diameter (BPD), humerus length (HL), and femur length (FL) for each fetus from novice-acquired 3D volumes. Corresponding gestational age (GA) estimates were calculated. Inter-rater reliability of measurements and GAs (expert 3D versus expert 2D, novice 3D versus expert 2D, and expert 3D versus novice 3D) were assessed by intraclass correlation coefficient (ICC). Mean inter-rater measurement differences were analyzed using one-way ANOVA. RESULTS: 3D volume acquisition and reconstruction required mean 30.4 s (±5.7) and 70.0 s (±24.0), respectively. PL, FP, and AFV were evaluated from volumes for all subjects; mean time for evaluation was 16 s (±0.0). PL, FP, and AFV could be evaluated for all subjects. At least one biometric measurement was possible for 31 subjects (97%). Agreement between rater pairs for a composite of all measures was excellent (ICCs ≥ 0.95), and for individual measures was good to excellent (ICCs ≥ 0.75). Inter-rater differences were not significant (p > .05). CONCLUSIONS: Expert and novice interpretations of novice-acquired 3DUS volumes of second trimester fetuses provided reliable biometric measures compared with expert interpretation of expert-acquired 2DUS images. 3DUS volume acquisition with a low-cost system may reduce operator dependence of ultrasound.

An Automated ALARA Method for Ultrasound: An Obstetric Ultrasound Feasibility Study.

OBJECTIVES: Ultrasound users are advised to observe the ALARA (as low as reasonably achievable) principle, but studies have shown that most do not monitor acoustic output metrics. We developed an adaptive ultrasound method that could suggest acoustic output levels based on real-time image quality feedback using lag-one coherence (LOC). METHODS: Lag-one coherence as a function of the mechanical index (MI) was assessed in 35 healthy volunteers in their second trimester of pregnancy. While imaging the placenta or the fetal abdomen, the system swept through 16 MI values ranging from 0.15 to 1.20. The LOC-versus-MI data were fit with a sigmoid curve, and the ALARA MI was selected as the point at which the fit reached 98% of its maximum. RESULTS: In this study, the ALARA MI values were between 0.35 and 1.03, depending on the acoustic window. Compared to a default MI of 0.8, the pilot acquisitions suggested a lower ALARA MI 80% of the time. The contrast, contrast-to-noise ratio, generalized contrast-to-noise ratio, and LOC all followed sigmoidal trends with an increasing MI. The R2 of the fit was statistically significantly greater for LOC than the other metrics (P < .017). CONCLUSIONS: These results suggest that maximum image quality can be achieved with acoustic output levels lower than the US Food and Drug Administration limits in many cases, and an automated tool could be used in real time to find the ALARA MI for specific imaging conditions. Our results support the feasibility of an automated, LOC-based implementation of the ALARA principle for obstetric ultrasound.

Physician Barriers and Facilitators for Screening for Congenital Heart Disease With Routine Obstetric Ultrasound: A National United States Survey.

OBJECTIVES: Prenatal detection of congenital heart disease with obstetric screening remains at less than 50% in most population studies, far from what is thought to be achievable. We sought to identify barriers/facilitators for screening from the perspective of interpreting physicians and to understand how these barriers/facilitators may be associated with interpretation of screening images. METHODS: Our mixed-methods studies included 4 focus groups in centers across the United States with obstetric, maternal-fetal medicine, and radiology providers who interpreted obstetric ultrasound studies. Themes around barriers/facilitators for fetal heart screening were coded from transcripts. A national Web-based survey was then conducted, which quantitatively measured reported barriers/facilitators and measured physicians' ability to interpret fetal heart-screening images. Multivariable generalized linear random-effect models assessed the association between barriers/facilitators and the accuracy of image interpretation at the image level. RESULTS: Three main themes were identified in the focus groups: intrinsic barriers (ie, comfort with screening), external barriers (ie, lack of feedback), and organizational barriers (ie, study volumes). Among 190 physician respondents, 104 interpreted ultrasound studies. Perceptions of barriers varied by practice setting, with nontertiary providers having lower self-efficacy and perceived usefulness of cardiac screening. Facilitators associated with the odds of accurate interpretation of screening images were knowledge (odds ratio, 2.54; P = .002) and the volume of scans per week (odds ratio, 1.01 for every additional scan; P = .04). CONCLUSIONS: Some of the main barriers to cardiac screening identified and prioritized by physicians across the United States were knowledge of screening and minimal volumes of scans. Targeting these barriers will aid in improving prenatal detection of congenital heart disease.

Clinical Utility of Fetal Short-Lag Spatial Coherence Imaging.

In this study, we evaluate the clinical utility of fetal short-lag spatial coherence (SLSC) imaging. Previous work has documented significant improvements in image quality with fetal SLSC imaging as quantified by measurements of contrast and contrast-to-noise ratio (CNR). The objective of this study was to examine whether this improved technical efficacy is indicative of the clinical utility of SLSC imaging. Eighteen healthy volunteers in their first and second trimesters of pregnancy were scanned using a modified Siemens SC2000 clinical scanner. Raw channel data were acquired for routinely examined fetal organs and used to generate fully matched raw and post-processed harmonic B-mode and SLSC image sequences, which were subsequently optimized for dynamic range and other imaging parameters by a blinded sonographer. Optimized videos were reviewed in matched B-mode and SLSC pairs by three blinded clinicians who scored each video based on overall quality, target conspicuity and border definition. SLSC imaging was highly favored over conventional imaging with SLSC scoring equal to (28.2 ± 10.5%) or higher than (63.9 ± 12.9%) B-mode for video pairs across all examined structures and processing conditions. Multivariate modeling revealed that SLSC imaging is a significant predictor of improved image quality with p ≤ 0.002. Expert-user scores for image quality support the application of SLSC in fetal ultrasound imaging.

Multidisciplinary approach to manage antenatally suspected placenta percreta: updated algorithm and patient outcomes.

BACKGROUND: Due to the significant morbidity and mortality associated with placenta percreta, alternative management options are needed. Beginning in 2005, our institution implemented a multidisciplinary strategy to patients with suspected placenta percreta. The purpose of this study is to present our current strategy, maternal morbidity and outcomes of patients treated by our approach. METHODS: From 2005 to 2014, a retrospective cohort study of patients with suspected placenta percreta at an academic tertiary care institution was performed. Treatment modalities included immediate hysterectomy at the time of cesarean section (CHYS), planned delayed hysterectomy (interval hysterectomy 6 weeks after delivery) (DH), and fertility sparing (uterine conservation) (FS). Prognostic factors of maternal morbidity were identified from medical records. Complications directly related to interventional procedures and DH was recorded. Descriptive statistics were utilized. RESULTS: Of the 21 patients with suspected placenta percreta, 7 underwent CHYS, 13 underwent DH, and 1 had FS with uterine preservation. Of the 20 cases that underwent hysterectomy, final pathology showed 11 increta, 7 percreta, and 2 inconclusive. 19/20 cases underwent interventional radiology (IR) procedures. Selective embolization was utilized in 14 cases (2/7 CHYS; 12/13 DH). The median time from cesarean section (CS) to DH was 41 [26-68] days. There were no cases of emergent hysterectomy, delayed hemorrhage, or sepsis in the DH group. Both estimated blood loss and number of packed red blood cell transfusions were significantly higher in the CHYS group. 3/21 cases required massive transfusion (2 CHYS, 1 FS) with median total blood product transfusion of 13 units [12-15]. The four IR-related complications occurred in the DH group. Incidence of postoperative complications was similar between both groups. Median hospital length of stay (LOS) after CHYS was 4 days [3-8] compared to DH cohort: 7 days [3-33] after CS and 4 days [1 -10] after DH. The DH cohort had a higher rate of hospital readmission of 54% (7/13) compared to 14% (1/7) CHYS, most commonly due to pain. There were no maternal deaths. CONCLUSION: This multidisciplinary strategy may appear feasible; however, further investigation is warranted to evaluate the effectiveness of alternative approaches to cesarean hysterectomy in cases of morbidly adherent placenta.

In vivo application of short-lag spatial coherence and harmonic spatial coherence imaging in fetal ultrasound.

Fetal scanning is one of the most common applications of ultrasound imaging and serves as a source of vital information about maternal and fetal health. Visualization of clinically relevant structures, however, can be severely compromised in difficult-to-image patients due to poor resolution and the presence of high levels of acoustical noise or clutter. We have developed novel coherence-based beamforming methods called Short-Lag Spatial Coherence (SLSC) imaging and Harmonic Spatial Coherence imaging (HSCI), and applied them to suppress the effects of clutter in fetal imaging. This method is used to create images of the spatial coherence of the backscattered ultrasound as opposed to images of echo magnitude. We present the results of a patient study to assess the benefits of coherence-based beamforming in the context of first trimester fetal exams. Matched fundamental B-mode, SLSC, harmonic B-mode, and HSCI images were generated using raw radio frequency data collected on 11 volunteers in the first trimester of pregnancy. The images were compared for qualitative differences in image texture and target conspicuity as well as using quantitative imaging metrics such as signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and contrast. SLSC and HSCI showed statistically significant improvements across all imaging metrics compared with B-mode and harmonic B-mode, respectively. These improvements were greatest for poor quality B-mode images where contrast of anechoic targets was improved from 15 dB in fundamental B-mode to 27 dB in SLSC and 17 dB in harmonic B-mode to 30 dB in HSCI. CNR improved from 1.4 to 2.5 in the fundamental images and 1.4 to 3.1 in the harmonic case. These results exhibit the potential of coherence-based beamforming to improve image quality and target detectability, especially in high noise environments.

Medical and surgical treatment of placenta percreta to optimize bladder preservation.

BACKGROUND: Placenta percreta is associated with significant morbidity and mortality. Interventions are dictated by hemodynamic stability, desire to retain future fertility, and efforts to reduce surgical morbidity at time of delivery. CASES: Two cases of antenatally diagnosed placenta percreta with bladder invasion are presented. Conservative management was used, including endovascular interventions, leaving the placenta in situ, methotrexate, and delayed hysterectomy. Postoperative outcomes were acceptable, with no significant hemorrhagic complications or need for extensive bladder reconstruction. CONCLUSION: Antenatal diagnosis of placenta percreta with bladder invasion is essential in the multidisciplinary management of this potentially catastrophic condition. A comprehensive approach including delayed hysterectomy after medical management resulted in an excellent clinical outcome.

Preterm premature rupture of membrane management--inpatient versus outpatient: a retrospective review.

The purpose of this study was to evaluate the outcome of patients with preterm premature rupture of membranes (PPROM) managed as inpatients who would have been candidates for outpatient management by prior published criteria. A retrospective review of medical records of PPROM subjects enrolled in a prospective cohort study was performed. Similar criteria to those established in a randomized trial for home management of PPROM by Carlan et al were applied. Assuming local residence, 65 subjects met the criteria for outpatient management. Demographic and delivery information were collected. Of the 65 subjects, 12 (18%) delivered <2 hours from the sentinel event. Adverse outcomes in these 12 subjects could have been devastating had they been managed as outpatients. Given the susceptibility of these subjects to obstetric emergencies, patients with PPROM at a viable gestational age should be considered for management as inpatients in a tertiary-care facility.

First trimester screening.

Screening for aneuploidy has traditionally been reserved for women of advanced maternal age. More recent advances in serum screening and ultrasound technology have allowed women of all ages to be offered screening in the second and even first trimester. These methods and their effectiveness are discussed.

Prenatal diagnosis of a trauma-related fetal epidural hematoma.

BACKGROUND: Prenatal diagnosis of fetal intracranial hemorrhage has important etiologic, management, and prognostic implications. Ultrasonography and magnetic resonance imaging (MRI) have been used to identify and evaluate this condition. We present the first reported case of epidural hematoma diagnosed prenatally. CASE: A 25-year-old para 3 was referred for evaluation of a suspected fetal intracranial abnormality following an alleged assault. Ultrasonography and MRI were used to diagnose an epidural hematoma prenatally. The fetus subsequently died in utero. Autopsy confirmed the presence of an epidural hematoma. CONCLUSION: Ultrasonography and MRI were useful in diagnosing a fetal epidural hematoma. Unfortunately, no known effective in utero therapy exists for this rare problem.