Variation in Fetal Weight Percentile Estimates.

OBJECTIVES: Weight percentiles are generally reported without any indication of error. This variation can lead a fetus being mistakenly classified erroneously as having intrauterine growth restriction (IUGR) or macrosomia. The goal of this study was to compare estimated weight percentiles with the actual observed weight percentile for each gestational age in a large cohort of fetuses being scanned in our institution. METHODS: After IRB approval the radiology information system data base was retrospectively searched for all obstetrical US reports obtained during the late second and third trimesters from July 1, 2014, until July 1, 2020. Demographic information, fetal weight, and weight percentile information were obtained from these reports. Quantile-quantile plots were created for all gestational ages and all ethnicities. RESULTS: Our study included 6259 ultrasounds in 4060 patients. Mean maternal age of the total group was 31.68 years (ranging 15-53 years). When all subjects were considered, the median values in our QQ plots approximated the line of identity. However, there was considerable variation for a given estimate, implying that estimated fetal weight percentiles are only very rough predictors of the actual percentile. CONCLUSION: Estimated fetal weight percentiles are only very rough predictors of the actual percentile. We therefore suggest that estimates of the weight percentile should be reported along with an estimate of the expected variation. Recognition of variations in weight percentile should be considered in the greater clinical context, and could potentially prevent misdiagnosis of growth restriction and macrosomia as well as the subsequent overutilization of resources, unnecessary interventions, and maternal stress.

Role of portable ultrasound during a short-term medical service trip to rural Guatemala: a collaborative mission of trainees and physicians.

INTRODUCTION: Access to health care in developing countries is scarce. One solution to this problem has been for doctors from the USA to provide single-visit care through short-term medical service trips. There is interest in using ultrasound imaging as a portable diagnostic tool; however, data describing its usefulness are scarce. Therefore, the goal of this study was to determine the usefulness of portable ultrasound imaging during a medical service trip to rural Guatemala. METHODS: A multidisciplinary team of physicians examined patients at a mobile clinic in Antigua, Guatemala. Patients with clinical indications for ultrasound had their suspected diagnoses recorded before ultrasound testing. After imaging, updated diagnoses were recorded and compared with the pre-test suspected diagnoses to determine how often ultrasound results changed the medical management of the patients and to assess the most common indications for ultrasound imaging. RESULTS: During the trip, 205 patients were seen. Of these, 24 (12%) were given ultrasound exams. The results of 13 (54%) exams altered their medical management, and the remaining 11 (46%) exams confirmed the pre-test suspected diagnoses. The most common indications for ultrasound testing were suspected cardiac (11 patients, 46%) and gastrointestinal (8 patients, 33%) diseases. CONCLUSION: Portable ultrasound imaging improved the medical team's ability to diagnose disease and clinically manage patients in a rural medical service trip. Ultrasound imaging may provide a low-cost solution to the growing demand for care in developing countries.

Trouble With the Curve: Pearls and Pitfalls in the Evaluation of Fetal Growth.

OBJECTIVES: Poor fetal growth is one of the most important findings on an obstetric ultrasound (US) examination. First-trimester US is the most accurate means for dating pregnancies; however, dating based on last menstrual period remains the standard for determining gestational age. Discrepancies between menstrual and US dating can lead to the overdiagnosis of in utero growth restriction (IUGR). This article will demonstrate that as long as the fetal growth falls along a curve that parallels normal growth curves, appropriate growth has occurred regardless of the gestational age and weight percentile that has been assigned to the fetus. METHODS: Following Institutional Review Board approval (HSD-00002969), 860 third-trimester fetal US examinations were retrospectively evaluated from January 1 through July 1, 2017, to determine whether they had normal growth curves. Outcome data on all cases were obtained from review of the medical records. RESULTS: Of 216 fetuses (25%) suspected of IUGR based on a weight below the 10th percentile, 6 developed true IUGR: 5 that led to emergent delivery of fetuses weighing less than a 1000 g and 1 in utero fetal demise. The remaining 210 fetuses all had normal outcomes. CONCLUSIONS: As long as the fetal growth falls along a curve that parallels normal growth curves, appropriate growth has occurred regardless of the gestational age and weight percentile that has been assigned to the fetus.

Histotripsy: The Next Generation of High-Intensity Focused Ultrasound for Focal Prostate Cancer Therapy.

This article reviews the most current methods and technological aspects of high-intensity focused ultrasound (HIFU), which is termed histotripsy. The rationale for focal therapy for prostate carcinoma rather than prostatectomy, which is being used extensively throughout Europe and Asia, is presented, and an argument for why HIFU is the modality of choice for primary therapy and recurrent disease is offered. The article presents a review of the technical advances including higher ultrasound beam energy than current thermal HIFU which allows for more accurate tissue targeting, less collateral tissue damage, and faster treatment times. Finally, the article presents a discussion about the advantage of ultrasound guidance for histotripsy in preference to magnetic resonance imaging guidance primarily based on cost, ease of application, and portability.

Propagation Imaging in the Demonstration of Common Shear Wave Artifacts.

In this article, we describe our experience with shear wave propagation imaging (SWPI) as an adjunct to 2-dimensional (2D) shear wave elastography (SWE) in a cohort of patients being evaluated for diffuse liver disease. Two-dimensional SWE has been extensively studied in previous publications; however, 2D SWE using propagation images has not been widely described in the literature to date. We observed that when certain artifacts occurred on the color elastograms, highly characteristic changes to shear wave propagation contours were seen, which can help clarify the cause of the artifacts. To our knowledge, the use of SWPI to explain the etiology of artifacts has never been published before. The artifacts described in this article include the capsule reverberation artifact, penetration limitation or dropout artifact, artifact due to blood vessels, shadowing artifact, tissue motion artifact, and near-field distortion/precompression artifact. Hence, the purpose of this article is to show examples of common artifacts seen on 2D SWE as depicted on corresponding SWPI to demonstrate that both types of image displays are complementary to each other.

Fetal Urinary Tract Anomalies: Review of Pathophysiology, Imaging, and Management.

OBJECTIVE: Common fetal anomalies of the kidneys and urinary tract encompass a complex spectrum of abnormalities that can be detected prenatally by ultrasound. Common fetal anomalies of the kidneys and urinary tract can affect amniotic fluid volume production with the development of oligohydramnios or anhydramnios, resulting in fetal pulmonary hypoplasia and, potentially, abnormal development of other fetal structures. CONCLUSION: We provide an overview of common fetal anomalies of the kidneys and urinary tract with an emphasis on sonographic patterns as well as pathologic and postnatal correlation, along with brief recommendations for postnatal management. Of note, we render an updated classification of fetal abnormalities of the kidneys and urinary tract based on the presence or absence of associated urinary tract dilation. In addition, we review the 2014 classification of urinary tract dilation based on the Linthicum multidisciplinary consensus panel.

Comparison of Superb Microvascular Imaging With Color Flow and Power Doppler Imaging of Small Hepatocellular Carcinomas.

OBJECTIVES: The purpose of this study was to compare Superb Microvascular Imaging (SMI; Toshiba America Medical Systems, Tustin, CA) with conventional color flow Doppler (CFD) and power Doppler (PD) imaging in the liver to distinguish between malignant and benign liver neoplasms. METHODS: After Institutional Review Board approval (number 449984-ED), patients undergoing routine pre-radiofrequency ablation planning ultrasound examinations for suspected hepatocellular carcinomas (HCCs) of less than 2 cm in diameter between January 1, 2015, and July 1, 2016, were prospectively identified. Four readers reviewed the ultrasound images independently for the presence or absence of flow centrally and along the periphery of the lesion. RESULTS: Higher peripheral vessel grades were found on SMI than CFD (P < .001) and PD (P < .001) imaging: in particular, more grade 2 (39% versus 16% and 11%, respectively) and grade 3 (8% versus 0% and 0%). Overall, more central and peripheral vessels were found on SMI than CFD and PD imaging for both HCC lesions (P < .001) and benign lesions (P < .001). Vascular grades were significantly higher in HCC lesions than benign lesions in nearly all cases, although the corresponding area under the curve values were relatively low, at 0.54 to 0.59 for the central vessel grades and 0.63 to 0.64 for the peripheral vessel grades. CONCLUSIONS: More central and peripheral vessels were found around liver lesions on SMI than on CFD and PD imaging. Although there was significantly more vascularity on the periphery of malignant liver lesions than benign lesions, the overall diagnostic performance based on this criterion alone was relatively low, with an area under the curve of 0.64.

Increased fetal lung T2 signal is not due to increasing surfactant concentration: an in vitro T2 mapping analysis.

OBJECT: The aim of this study was to perform in vitro T2 mapping of serial dilutions of pharmaceutical surfactant. MATERIALS AND METHODS: Magnetic resonance imaging. Magnetic resonance scanning was performed on serial dilutions of surfactant on large bore clinical magnets at a field strength of 1.5 T Philips and 3.0 T (Achieva TX, Philips Healthcare, the Netherlands). RESULTS: The curves demonstrate a small increasing trend between surfactant concentration and R2 (shortened T2's), with a 7.3% increase in R2 for each doubling of surfactant concentration (95% confidence interval: 6.1-8.6%, p < 0.001). CONCLUSIONS: The increasing lung/liver T2 signal ratio seen in fetal lungs with increasing gestational age is not due to increasing surfactant concentration. © 2016 John Wiley & Sons, Ltd.

The Sonographic Stenosis Index: A New Specific Quantitative Measure of Transplant Hepatic Arterial Stenosis.

OBJECTIVES: This study evaluates the sensitivity and specificity of stenosis index (SI), which accounts for the entire spectral Doppler waveform, to detect significant transplant hepatic arterial stenosis. MATERIALS AND METHODS: In this institutional review board-approved, HIPAA compliant study, we retrospectively analyzed 69 patients who had catheter angiography for suspected transplant hepatic arterial stenosis (THAS) between January 2006 and December 2010; all patients had Doppler ultrasound within 30 days before angiography. Patients with angiographic stenosis requiring intervention were considered positive for THAS. Stenosis index was calculated from each patient's spectral Doppler ultrasound images by obtaining the ratio of the area under the high-frequency signal to low-frequency signal in the spectral Doppler. Resistive index (RI) and pulsatility index (PI) were also calculated. Receiver operator curve analysis was performed and the area under the curve (AUC) was compared among the three metrics. RESULTS: Forty-eight of 69 patients had THAS by angiography requiring intervention; 21patients had no angiographic evidence of THAS. SI was significantly different (P < .001) between patients with THAS (SI = 1.04 ± 0.20) and those without THAS (SI = 1.39 ± 0.30). Stenosis index had an AUC of 0.86 for detecting THAS, which was significantly higher than that from RI (AUC = 0.68, P = .038 for the comparison) and PI (AUC = 0.70, P = .029). For SI < 1.35, the sensitivity for THAS was 94% and specificity was 52%. For RI < 0.5, the sensitivity was 96% and the specificity was 29%. CONCLUSIONS: Stenosis index is more accurate than the resistive index and the pulsatility index for detecting transplant hepatic artery stenosis.

Comprehensive imaging review of abnormalities of the umbilical cord.

A complete fetal ultrasonographic (US) study includes assessment of the umbilical cord for possible abnormalities. Knowledge of the normal appearance of the umbilical cord is necessary for the radiologist to correctly diagnose pathologic conditions. Umbilical cord abnormalities can be related to cord coiling, length, and thickness; the placental insertion site; in utero distortion; vascular abnormalities; and primary tumors or masses. These conditions may be associated with other fetal anomalies and aneuploidies, and their discovery should prompt a thorough fetal US examination. Further workup and planning for a safe fetal delivery may include fetal echocardiography and karyotype analysis. Doppler US is a critical tool for assessment and diagnosis of vascular cord abnormalities. US also can be used for follow-up serial imaging evaluation of conditions that could result in fetal demise. Recent studies suggest that three- or four-dimensional Doppler US of the fetal umbilical cord and abdominal vasculature allows more accurate diagnosis of vascular abnormalities. Doppler US also is invaluable in assessment of fetal growth restriction since hemodynamic changes in the placenta or fetus would appear as a spectral pattern of increased resistance to forward flow in the fetal umbilical artery. Early detection of umbilical cord abnormalities and close follow-up can reduce the risk of morbidity and mortality and assist in decision making.

Fetal lung maturity assessment with MRI fetal lung-to-liver signal-intensity ratio.

OBJECTIVE: The purpose of this study was to retrospectively determine whether the ratio of fetal lung-to-liver signal intensities at single-shot fast spin-echo MRI is associated with fetal gestational age. MATERIALS AND METHODS: All fetal MRI examinations over a 4-year period were reviewed. All MRI examinations were performed with a 1.5-T magnet for indications other than lung maturity. Only examinations performed with a single-shot fast spin-echo sequence of the fetal chest and abdomen were included in the study. Images from a total of 82 fetal MRI examinations were evaluated. Gestational age ranged from 20 weeks to 39 weeks 3 days. Two board-certified subspecialty-trained radiologists with 11 and 17 years of experience blinded to estimated gestational age (EGA) reviewed the images independently. The regions of interest (ROIs) of the fetal lung and liver were drawn in the same plane and on the same image in each case. Fetal EGA was determined either by first-trimester ultrasound when available or by last menstrual period. Linear regression analysis was used to analyze the relation between the lung-to-liver signal-intensity ratio (LLSIR) in the ROIs and fetal EGA for both readers. The association between the LLSIRs estimated by the two readers was assessed by Bland-Altman plot. RESULTS: Summary statistics for LLSIR showed a median value of 2.29 for reader 1 and 2.21 for reader 2. The mean value for reader 1 was 2.4 and for reader 2 was 2.5. The Pearson correlation coefficients between the LLSIR and EGA variables were 0.44 for reader 1 and 0.45 for reader 2. Linear regression analysis showed a statistically significant association between LLSIR and EGA for both readers (p < 0.0004). This ratio increased in a linear manner as EGA progressed. CONCLUSION: Fetal LLSIR at single-shot fast spin-echo MRI is associated with fetal gestational age.

Ultrasound Attenuation Imaging vs MRI-PDFF, Echogenicity and Liver Function for Assessing Degree of Steatosis in NAFLD and Non-NAFLD Patients.

ABSTRACT: Nonalcoholic fatty liver disease (NAFLD) is a primary cause of parenchymal liver disease globally. There are currently several methods available to test the degree of steatosis in NAFLD patients, but all have drawbacks that limit their use.The objective of this study is to determine if a new technique, ultrasound (US) attenuation imaging (ATI), correlates with magnetic resonance proton density fat fraction imaging and hepatic echogenicity as seen on gray scale US imaging.Fifty-four patients were recruited at the University of Washington Medical Center from individuals who had already been scheduled for hepatic US or magnetic resonance imaging (MRI). All participants then underwent both hepatic MRI proton density fat fraction and US. Ultrasound images were then evaluated using ATI with 2 observers who individually determined relative grayscale echogenicity.Analysis showed positive correlation between ATI- and MRI-determined fat percentage in the case group (Spearman correlation: 0.50; P = 0.015). Furthermore, participants with NAFLD tended to have a higher ATI than controls (median: 0.70 vs 0.54 dB/cm/MHz; P < 0.001).This study demonstrates that US ATI combined with grayscale imaging is an effective way of assessing the degree of steatosis in patients with moderate to severe NAFLD.

Assessment of the liver strain among cirrhotic and normal livers using tagged MRI.

PURPOSE: To use magnetization tagged magnetic resonance imaging (MRI) (tag-MRI) to quantify cardiac induced liver strain and compare strain of cirrhotic and normal livers. MATERIALS AND METHODS: Tag-MRI was performed at 1.5T on eight subjects with no history of liver disease and 10 patients with liver cirrhosis. A breath-hold peripheral pulse-gated (PPG) conventional tag-MRI cine sequence was performed with planes to include the left lobe of the liver and the inferior wall of the heart. Commercially available software HARP (Diagnosoft, Palo Alto, CA) was used for image analysis and strain calculation. Three regions-of-interest (ROIs) were selected: segment II of the liver near the heart (A), right liver lobe far from the heart (B), and the left ventricular wall (C). The average and maximal (max) strain were measured in A, B, and C. The maximum strains were used to generate a cardiac-corrected strain gradient: (maxA-maxB)/maxC. Results were compared with Student's t-test (SPSS, Chicago, IL). RESULTS: In subjects with no history of liver disease vs. cirrhotic patients, the average strain was 22% ± 7% vs. 4% ± 3% (P < 0.001), the max strain was 63% ± 15% vs. 17% ± 5% (P < 0.001), and the corrected strain gradient was 0.52 ± 0.16 vs. 0.11% ± 0.08%. CONCLUSION: There is a significant difference in liver strain measured with tag-MRI between subjects with no history of liver disease and patients with cirrhosis.

Evaluation and management of disorders of sex development: multidisciplinary approach to a complex diagnosis.

Various disorders of sex development (DSD) result in abnormal development of genitalia, which may be recognized at prenatal ultrasonography, immediately after birth, or later in life. Current methods for diagnosing DSD include a thorough physical examination, laboratory tests to determine hormone levels and identify chromosomal abnormalities, and radiologic imaging of the genitourinary tract and adjacent organs. Because of the complex nature of DSD, the participation of a multidisciplinary team is required to address the patient's medical needs as well as any psychosocial issues that the patient or the family may encounter after the diagnosis. The first step in the management of DSD is sex assignment, which is based on factors such as the genotype; the presence, location, and appearance of reproductive organs; the potential for fertility; and the cultural background and beliefs of the patient's family. The primary goal of sex assignment is to achieve the greatest possible consistency between the patient's assigned sex and his or her gender identity. Once the sex is assigned, the next step in management might be surgery, hormone therapy, or no intervention at all. Patients with ovotesticular DSD and gonadal dysgenesis may require a gonadectomy, followed by reconstructive surgery. Some patients may need hormone replacement therapy during puberty. An understanding of the immediacy of families' need for sex assignment and clinicians' need for reliable diagnostic imaging results will help radiologists participate effectively in the prenatal and postnatal assessment of patients with DSD.

Imaging of uncommon retroperitoneal masses.

Retroperitoneal masses not arising from major solid organs are uncommon. Although there is no simple method of classifying retroperitoneal masses, a reasonable approach is to consider the masses as predominantly solid or cystic and to subdivide these into neoplastic and nonneoplastic masses. Because the treatment options vary, it is useful to be able to differentiate these masses by using imaging criteria. Although the differential diagnosis of retroperitoneal masses can be narrowed down to a certain extent on the basis of imaging characteristics, patterns of involvement, and demographics, there is still a considerable overlap of imaging findings for these masses, and histologic examination is often required for definitive diagnosis. Computed tomography (CT) and magnetic resonance (MR) imaging play an important role in characterization and in the assessment of the extent of the disease and involvement of adjacent and distant structures. Familiarity with the CT and MR imaging features of various retroperitoneal masses will facilitate accurate diagnosis and staging for aggressive lesions.

EXIT procedure: technique and indications with prenatal imaging parameters for assessment of airway patency.

Successful management of fetal conditions in which airway obstruction is anticipated is now possible because of advances in prenatal imaging and the development of innovative techniques to secure the fetal airway before complete separation of the fetus from the maternal circulation. Fetal ultrasonography and fetal magnetic resonance imaging are complementary imaging modalities in the assessment of fetuses with potential airway obstruction. The ex utero intrapartum therapy (EXIT) procedure is used to secure the fetal airway before complete delivery of the fetus. However, successful intrapartum treatment of fetuses who may need prolonged placental support depends on a multidisciplinary assessment in which the benefits of the EXIT procedure for the fetus are weighed against the risk of maternal complications that may occur during prolongation of the intrapartum period to secure the fetal airway. This multidisciplinary approach requires an understanding of the types of lesions in which intrapartum fetal airway access would be beneficial, a knowledge of the prenatal images that would best delineate the anatomic defect and thus help guide the best approach to securing the airway, and consensus and coordination among medical ethicists, radiologists, obstetric anesthesiologists and obstetricians, pediatric surgeons and anesthesiologists, and neonatologists.

Utility of multiplanar and three-dimensional reconstructions from computed tomography performed for maternal indications for visualizing fetal anatomy and estimating gestational age.

OBJECTIVE: The purpose of this article was to determine the usefulness of multiplanar and 3-dimensional (3D) reconstructions of computed tomographic (CT) data from scans performed for maternal indications for visualizing fetal anatomy and estimating gestational age. MATERIALS AND METHODS: Eighteen pregnant patients who had abdominopelvic CT scanning performed for maternal indications formed the study group. Two independent reviewers created multiplanar and 3D-reconstructed images of the fetus from these CT scans and analyzed them for fetal anatomy and gestational age. Fetal dose estimates were also obtained. RESULTS: Computed tomographic fetal biometry generally agreed well with ultrasound estimates. Computed tomographic and ultrasound estimates were within 3 to 4 weeks of each other 95% of the time for the 2 reviewers. Pearson correlation coefficients were 0.989 for reviewer 1 and 0.985 for reviewer 2. Fetal anatomic survey revealed that it was easier to see bones and fluid-filled structures such as the stomach and urinary bladder than intracranial, intrathoracic, and intra-abdominal soft tissue structures. Estimated fetal dose was 28.5 (10.7) mGy using the Imaging Performance Assessment of CT Scanner calculator and 23.7 (7.7) mGy when taking maternal perimeter and fetal depth into account with the method of Angel et al. CONCLUSIONS: It is technically feasible to produce clinically useful images of the fetus using standard multiplanar reconstructions and 3D algorithms already in place for CT scanning. As CT scans continue to be performed under certain circumstances, particularly the emergency department setting, evaluation of maternal CT scans for potentially useful information about the fetus such as gestational age and gross anatomic survey can be obtained at estimated fetal radiation doses much lower than the actionable level of 150 mGy.