Regulation of intrinsic polarity establishment by a differentiation-type MAPK pathway in S. cerevisiae.

All cells establish and maintain an axis of polarity that is critical for cell shape and progression through the cell cycle. A well-studied example of polarity establishment is bud emergence in the yeast Saccharomyces cerevisiae, which is controlled by the Rho GTPase Cdc42p. The prevailing view of bud emergence does not account for regulation by extrinsic cues. Here, we show that the filamentous growth mitogen activated protein kinase (fMAPK) pathway regulates bud emergence under nutrient-limiting conditions. The fMAPK pathway regulated the expression of polarity targets including the gene encoding a direct effector of Cdc42p, Gic2p. The fMAPK pathway also stimulated GTP-Cdc42p levels, which is a critical determinant of polarity establishment. The fMAPK pathway activity was spatially restricted to bud sites and active during the period of the cell cycle leading up to bud emergence. Time-lapse fluorescence microscopy showed that the fMAPK pathway stimulated the rate of bud emergence during filamentous growth. Unregulated activation of the fMAPK pathway induced multiple rounds of symmetry breaking inside the growing bud. Collectively, our findings identify a new regulatory aspect of bud emergence that sensitizes this essential cellular process to external cues.

Detection of femoroplasty on pre- and post-arthroscopic comparison radiographs following treatment of femoroacetabular impingement syndrome: multi-reader accuracy and agreement study.

OBJECTIVE: To assess diagnostic accuracy and agreement among radiologists in detecting femoroplasty on pre- and post-arthroscopic comparison frog lateral and anteroposterior (AP) pelvic radiographs after treatment of femoroacetabular impingement (FAI) syndrome. MATERIALS AND METHODS: In this retrospective, cross-sectional study, 86 patients underwent hip arthroscopy (52 with and 34 without femoroplasty) for treatment of FAI syndrome. Three radiologists blinded to clinical data and chronological order of the pre- and post-arthroscopic comparison radiographs independently examined AP pelvis and frog lateral radiographs to detect femoroplasty changes. Statistical analysis outputs included diagnostic accuracy parameters and inter- and intra-observer agreement. RESULTS: Identification of femoroplasty in the frog lateral projection has mean sensitivity 70%, specificity 82%, inter-observer agreement κ 0.74-0.76 and intra-observer agreement κ 0.72-0.85. Using the AP pelvis projection to detect femoroplasty has mean sensitivity 32%, specificity 71%, inter-observer agreement κ 0.47-0.65, and intra-observer agreement κ, 0.56-0.84. CONCLUSIONS: Radiologists are only moderately sensitive, though more specific, in femoroplasty detection in the frog lateral projection. The AP pelvis projection yields lower sensitivity and specificity. Both projections have moderate inter- and intra-observer agreement.

An Audio/Video Reporting Workflow to Supplement Standardized Radiology Reports.

Radiology studies are inherently visual and the information contained within is best conveyed by visual methodology. Advanced reporting software allows the incorporation of annotated key images into text reports, but such features may be less effective compared with in-person consultations. The use of web technology and screen capture software to create retrievable on-demand audio/visual reports has not yet been investigated. This approach may preempt potential curbside consultations while providing referring clinicians with a more engaged imaging service. In this work, we develop and evaluate a video reporting tool that utilizes modern screen capture software and web technology. We hypothesize that referring clinicians would find that recorded on-demand video reports add value to clinical practice, education, and that such technology would be welcome in future practice. A total of 45 case videos were prepared by radiologists for 14 attending and 15 trainee physicians from emergency and internal medicine specialties. Positive survey feedback from referring clinicians about the video reporting system was statistically significant in all areas measured, including video quality, clinical helpfulness, and willingness to use such technology in the future. Trainees unanimously found educational value in video reporting. These results suggest the potential for video technology to re-establish the radiologist's role as a pivotal member of patient care and integral clinical educator. Future work is needed to streamline these methods in order to minimize work redundancy with traditional text reporting. Additionally, integration with an existing PACS and dictation system will be essential to ensuring ease of use and widespread adoption.

The bioequivalence of frozen plasma prepared from whole blood held overnight at room temperature compared to fresh-frozen plasma prepared within eight hours of collection.

BACKGROUND: Overnight, room temperature hold of whole blood (WB) before leukoreduction and component processing offers significant logistic and cost advantages over WB processed within 8 hours. Plasma prepared from WB held at room temperature overnight (PF24RT24WB) may result in a degradation of plasma coagulation protein activities compared to plasma frozen within 8 hours of collection. In this study, we intended to evaluate the bioequivalence (BE) of PF24RT24WB prepared using a new WB collection, leukoreduction, and storage system compared to fresh-frozen plasma (FFP) after 12 months of frozen storage. STUDY DESIGN AND METHODS: We conducted a three-center, three-arm evaluation of the LEUKOSEP HWB-600-XL test system (Hemerus Medical LLC) compared to the RZ2000 control (Fenwal, Inc.). FFP was prepared from WB held at room temperature more than 6 hours and placed at less than -18 °C by 8 hours for control (n = 60) and test (n = 60) arms. PF24RT24WB (n = 60) was prepared with the test system from WB held at room temperature and then filtered and processed 20 to 24 hours postcollection. Frozen plasma was tested at 3, 6, and 12 months using a comprehensive panel of protein and coagulation factor assays. RESULTS: The test FFP was BE for all coagulation factors and tested proteins at 12 months. As expected, PF24RT24WB had a reduced Factor (F)VIII activity compared to control FFP (87.1%; 90% confidence interval, 79.4%-93.3%) with the lower confidence limit less than 80%. All other factors were within the BE region. CONCLUSION: Leukoreduced FFP and PF24RT24WB prepared using the LEUKOSEP HWB-600-XL system has been shown to be BE to control leukoreduced FFP with an expected decrease in FVIII activity after overnight hold.

Additive solution-7 reduces the red blood cell cold storage lesion.

BACKGROUND: Transfusion of long-stored red blood cells (RBCs) is associated with decreased in vivo RBC recovery, delivery of RBC breakdown products, and increased morbidity and mortality. Reducing the burden of this RBC "storage lesion" is a major challenge in transfusion medicine. Additive solution-7 (AS-7) is a new RBC storage solution designed to improve RBC metabolism by providing phosphate and increasing buffering capacity. STUDY DESIGN AND METHODS: Storage quality in AS-7 was measured in a prospective, randomized, three-center trial using units of whole blood from healthy human subjects whose RBCs were stored for up to 56 days in AS-7 (n = 120) or for 42 days in the control solution AS-1 (n = 60). RESULTS: Hemolysis and shedding of protein-containing microvesicles were significantly reduced in RBCs stored in AS-7 for 42 and 56 days compared with RBCs stored in AS-1. Autologous in vivo recoveries of RBCs stored in AS-7 was 88 ± 5% at 42 days (n = 27) and 82 ± 3% at 56 days (n = 27), exceeding recoveries of RBCs stored in currently used solutions. CONCLUSION: Increasing the phosphate, pH range, and buffer capacity of a RBC storage system allowed RBCs to be stored better and longer than currently approved storage systems. AS-7 ameliorates the long-term storage lesion resulting in significantly increased viability in vitro and in vivo.

Autopage and the use of computer scripts to automate microtasks.

Paging referring clinicians with imaging results is a frequently repeated "microtask" performed by practicing radiologists. Many institutions use online alpha-paging systems to provide this integral part of safe and efficient patient care. Although sending an alpha-page can often be accomplished within one minute, current tools may disrupt workflow by distracting users with a series of tedious mouse clicks. We describe the development, evaluation, and updates of a portable tool that sends alpha-pages to referring clinicians using two keystrokes. This software integrates study information obtained from the Picture Archiving and Communication System (PACS) with an existing hospital paging system.

Kaposiform Lymphangiomatosis as a Cause of Vaginal Bleeding & Discharge: A Case Report.

BACKGROUND: Prepubertal vaginal bleeding is a common presentation for pediatric adolescent gynecologists with a broad differential diagnosis that historically may not have included complex lymphatic anomalies. However, given recent consensus criteria and imaging capabilities, this may be a condition that pediatric adolescent gynecologists see more frequently in the future. CASE: We present a case of a 5-year-old pre-pubertal girl whose only presenting symptoms of a rare complex lymphatic anomaly was copious vaginal bleeding. After three vaginoscopies, two hysteroscopies, two pelvic MRIs, and a percutaneous ultrasound guided core needle biopsy, this patient was eventually diagnosed with Kaposiform lymphangiomatosis at age 9 years-old, and she is now being treated medically with sirolimus, a mammalian target of rapamycin (mTOR) inhibitor, with improvement in her symptoms. SUMMARY AND CONCLUSION: Complex lymphatic anomalies should be considered after initial and secondary workups for pre-pubertal vaginal bleeding or copious vaginal discharge are negative. Furthermore, this case illustrates the value of pelvic MRI in the setting of unknown cause of vaginal bleeding when typical workup is negative.

A randomized controlled trial evaluating recovery and survival of 6% dimethyl sulfoxide-frozen autologous platelets in healthy volunteers.

BACKGROUND: Availability of platelets (PLTs) is severely limited by shelf life in some settings. Our objective was to determine and compare to Food and Drug Administration (FDA) criteria the PLT recovery and survival of autologous PLTs cryopreserved at -65°C or less in 6% dimethyl sulfoxide (DMSO) reconstituted with a no-wash method (cryopreserved PLTs [CPPs]) compared to autologous fresh PLTs. STUDY DESIGN AND METHODS: This was a randomized, Phase I study analyzing PLT viability and in vitro function in consenting healthy subjects. Apheresis PLTs (APs) were collected in plasma. APs were suspended in 6% DMSO, concentrated, and placed at not more than -65°C for 7 to 13 days. Frozen CPPs were thawed at 37°C and resuspended into 25 mL of 0.9% NaCl. Control PLTs (fresh autologous) and CPPs were labeled with (111) In or (51) Cr, and recovery and survival after reinfusion were determined using standard methods. A panel of in vitro assays was completed on APs and CPPs. RESULTS: After frozen storage, CPPs retained 82% of AP yield and showed increased PLT associated P-selectin and reduced responses to agonists. CPP 24-hour recovery (41.6 ± 9.7%) was lower than for fresh PLTs (68.4 ± 8.2%; p < 0.0001) and did not meet the current FDA criterion. CPPs had diminished survival compared to fresh PLTs (7.0 ± 2.1 days vs. 8.4 ± 1.2 days, respectively; p = 0.018), but did meet and exceed the FDA criterion for survival. CONCLUSION: While 24-hour recovery does not meet FDA criteria for liquid-stored PLTs, the CPP survival of circulating PLTs was surprisingly high and exceeded the FDA criteria. These data support proceeding with additional studies to evaluate the clinical effectiveness of CPPs.

Interictal PET and ictal subtraction SPECT: sensitivity in the detection of seizure foci in patients with medically intractable epilepsy.

PURPOSE: Interictal positron emission tomography (PET) and ictal subtraction single photon emission computed tomography (SPECT) of the brain have been shown to be valuable tests in the presurgical evaluation of epilepsy. To determine the relative utility of these methods in the localization of seizure foci, we compared interictal PET and ictal subtraction SPECT to subdural and depth electrode recordings in patients with medically intractable epilepsy. METHODS: Between 2003 and 2009, clinical information on all patients at our institution undergoing intracranial electroencephalography (EEG) monitoring was charted in a prospectively recorded database. Patients who underwent preoperative interictal PET and ictal subtraction SPECT were selected from this database. Patient characteristics and the findings on preoperative interictal PET and ictal subtraction SPECT were analyzed. Sensitivity of detection of seizure foci for each modality, as compared to intracranial EEG monitoring, was calculated. KEY FINDINGS: Fifty-three patients underwent intracranial EEG monitoring with preoperative interictal PET and ictal subtraction SPECT scans. The average patient age was 32.7 years (median 32 years, range 1-60 years). Twenty-seven patients had findings of reduced metabolism on interictal PET scan, whereas all 53 patients studied demonstrated a region of relative hyperperfusion on ictal subtraction SPECT suggestive of an epileptogenic zone. Intracranial EEG monitoring identified a single seizure focus in 45 patients, with 39 eventually undergoing resective surgery. Of the 45 patients in whom a seizure focus was localized, PET scan identified the same region in 25 cases (56% sensitivity) and SPECT in 39 cases (87% sensitivity). Intracranial EEG was concordant with at least one study in 41 cases (91%) and both studies in 23 cases (51%). In 16 (80%) of 20 cases where PET did not correlate with intracranial EEG, the SPECT study was concordant. Conversely, PET and intracranial EEG were concordant in two (33%) of the six cases where the SPECT did not demonstrate the seizure focus outlined by intracranial EEG. Thirty-three patients had surgical resection and >2 years of follow-up, and 21 of these (64%) had Engel class 1 outcome. No significant effect of imaging concordance on seizure outcome was seen. SIGNIFICANCE: Interictal PET and ictal subtraction SPECT studies can provide important information in the preoperative evaluation of medically intractable epilepsy. Of the two studies, ictal subtraction SPECT appears to be the more sensitive. When both studies are used together, however, they can provide complementary information.

FDG PET of Isolated Right Ventricular Sarcoidosis.

ABSTRACT: A 62-year-old man with a history of allergic rhinitis and lightheadedness was admitted after an episode of sustained ventricular tachycardia detected by Holter monitor. A chest CT revealed peribronchial nodules, and mediastinal and hilar lymphadenopathy. The findings raised concern for sarcoidosis. MRI and FDG PET/CT were performed and revealed cardiac sarcoidosis isolated to the right ventricle only. Sarcoidosis of the right ventricle, sparing the left ventricle, is an extremely uncommon entity.

Analysis of treatment sequence and outcomes in patients with relapsed malignant peripheral nerve sheath tumors.

Background: Malignant peripheral nerve sheath tumors (MPNST) are aggressive soft tissue sarcomas originating from cellular components within the nerve sheath. The incidence of MPNST is highest in people with neurofibromatosis type 1 (NF1), and MPNST is the leading cause of death for these individuals. Complete surgical resection is the only curative therapeutic option, but is often unfeasible due to tumor location, size, or presence of metastases. Evidence-based choices of chemotherapy for recurrent/refractory MPNST remain elusive. To address this gap, we conducted a retrospective analysis of our institutional experience in treating patients with relapsed MPNST in order to describe patient outcomes related to salvage regimens. Methods: We conducted a retrospective electronic health record analysis of patients with MPNST who were treated at Johns Hopkins Hospital from January 2010 to June 2021. We calculated time to progression (TTP) based on salvage chemotherapy regimens. Results: Sixty-five patients were included in the analysis. Upfront therapy included single or combined modalities of surgery, chemotherapy, or radiotherapy. Forty-eight patients received at least 1 line of chemotherapy, which included 23 different regimens (excluding active clinical studies). Most patients (n = 42, 87.5%) received a combination of doxorubicin, ifosfamide, or etoposide as first-line chemotherapy. Salvage chemotherapy regimens and their TTP varied greatly, with irinotecan/temozolomide-based regimens having the longest average TTP (255.5 days, among 4 patients). Conclusions: Patients with advanced or metastatic MPNST often succumb to their disease despite multiple lines of therapy. These data may be used as comparative information in decision-making for future patients and clinical trials.

A randomized controlled trial comparing autologous radiolabeled in vivo platelet (PLT) recoveries and survivals of 7-day-stored PLT-rich plasma and buffy coat PLTs from the same subjects.

BACKGROUND: A recent review concluded that there was inadequate evidence to show a difference between buffy coat (BC) and platelet (PLT)-rich plasma (PRP) PLT concentrates prepared from whole blood. We hypothesized that 7-day-stored BC-PLTs would have superior autologous recoveries and survivals compared to PRP-PLTs and that both would meet the Food and Drug Administration (FDA) criteria for poststorage viability. STUDY DESIGN AND METHODS: This was a randomized, crossover study design in healthy subjects who provided informed consent. Each participant donated a unit of whole blood on two occasions. In random order, either BC-PLTs or PC-PLTs were prepared after a 20 ± 2 °C overnight hold of the whole blood. PLTs were stored under standard conditions. On Day 7, fresh PLTs were prepared from 43 mL of autologous whole blood. The fresh PLTs paired with either BC-PLTs or PRP-PLTs were alternately labeled with (111) In or (51) Cr and simultaneously reinfused to determine recoveries and survivals. In vitro assays were performed on Days 1 and 7. RESULTS: Fourteen subjects completed the study at two sites. No differences in poststorage PLT viabilities were observed between BC-PLTs and PRP-PLTs; recovery differences averaged 3.7 ± 2.4% (± SE, p = 0.15) and survival differences averaged 0.48 ± 0.56 days (p = 0.41). Neither type of PLTs met the current FDA criteria for either poststorage PLT recoveries or survivals. CONCLUSION: We were unable to demonstrate that single-unit BC-PLTs stored for 7 days have superior poststorage viability compared to PRP-PLTs. Failure to meet the minimum FDA criteria for poststorage PLT viability raises questions regarding the acceptance thresholds of these metrics.

Stored red blood cell viability is maintained after treatment with a second-generation S-303 pathogen inactivation process.

BACKGROUND: Transfusion-transmitted infections and immunologic effects of viable residual lymphocytes remain a concern in red blood cell (RBC) transfusion. Pathogen reduction technologies for RBC components are under development to further improve transfusion safety. S-303 is a frangible anchor-linker-effector with labile alkylating activity and a robust pathogen reduction profile. This study characterized the viability of RBCs prepared with a second-generation S-303 process and stored for 35 days. STUDY DESIGN AND METHODS: This was a two-center, single-blind randomized, controlled, crossover study in 27 healthy subjects. S-303 (test) or control RBCs were prepared in random sequence and stored for 35 days, at which time an aliquot of radiolabeled RBCs was transfused. The 24-hour recovery, RBC life span, and in vitro metabolic and viability variables were analyzed. RESULTS: The mean 24-hour RBC recovery and hemolysis of test RBCs were similar to control RBCs and were consistent with the Food and Drug Administration (FDA) guidance for RBC viability. The mean differences in life span and median life span (T(50) ) of circulating test RBCs were 13.7 and 6.8 days, while the mean difference in the area under the curve of surviving RBCs was 1.38%, in favor of control RBCs. There were no clinically relevant abnormal laboratory values after the infusion of test RBCs. All crossmatch assays of autologous S-303 RBCs were nonreactive. CONCLUSIONS: RBCs prepared using the S-303 pathogen inactivation process were physiologically and metabolically suitable for transfusion after 35 days of storage, met the FDA guidance criteria for 24-hour recovery, and did not induce antibody formation.

Toxicity and reductions in intracellular calcium levels following uptake of a tetracycline antibiotic in Arabidopsis.

Plant responses to natural stresses have been the focus of numerous studies; however less is known about plant responses to artificial (i.e., man-made) stress. Chlortetracycline (CTC) is widely used in agriculture and becomes an environmental contaminant when introduced into soil from manure used as fertilizer. We show here that in the model plant Arabidopsis (Arabidopsis thaliana), root uptake of CTC leads to toxicity, with growth reductions and other effects. Analysis of protein accumulation and in vivo synthesis revealed numerous changes in soluble and membrane-associated proteins in leaves and roots. Many representative proteins associated with different cellular processes and compartments showed little or no change in response to CTC. However, differences in accumulation and synthesis of NAD-malic enzyme in leaves versus roots suggest potential CTC-associated effects on metabolic respiration may vary in different tissues. Fluorescence resonance energy transfer (FRET) analysis indicated reduced levels of intracellular calcium are associated with CTC uptake and toxicity. These findings support a model in which CTC uptake through roots leads to reductions in levels of intracellular calcium due to chelation. In turn, changes in overall patterns and levels of protein synthesis and accumulation due to reduced calcium ultimately lead to growth reductions and other toxicity effects.

Estimation of Chest Wall Attenuation of 123I Emissions in Substernal Goiter: A Phantom Study.

In patients with substernal goiter, the generally accepted theory is that thyroid uptake measurements with iodine isotopes are underestimated because of attenuation by the chest wall. The extent of this underestimation is not well known. In this study, we calculated the attenuation of 123I emissions using a cadaver chest wall with a thyroid probe to better understand the potential severity of this underestimation. Methods: A 11.1-MBq capsule of 123I was measured using a thyroid probe directly in a standard neck phantom and behind a cadaver chest wall that included the soft tissues and bony structures (sternum). Results: The calculated attenuation of the iodine capsule was 18% for the neck phantom and 35% for the cadaver chest wall. Conclusion: Thyroid uptake in cases of substernal goiter may be underestimated by standard techniques using a neck phantom. The composition of the chest wall can vary greatly, and the substernal extent of the goiter would be difficult to calculate with high accuracy on a routine basis. Comparison between the cadaveric specimen and the phantom does give us a rough estimation of the differences in attenuation. Our findings suggest that attenuation by the chest wall can be substantial. Knowledge of the extent of the substernal component of the thyroid gland may be useful if the uptake measurement is used to calculate doses for treating hyperthyroidism in patients with substernal goiter.

The impact of particulate electron paramagnetic resonance oxygen sensors on fluorodeoxyglucose imaging characteristics detected via positron emission tomography.

During a first-in-humans clinical trial investigating electron paramagnetic resonance tumor oximetry, a patient injected with the particulate oxygen sensor Printex ink was found to have unexpected fluorodeoxyglucose (FDG) uptake in a dermal nodule via positron emission tomography (PET). This nodule co-localized with the Printex ink injection; biopsy of the area, due to concern for malignancy, revealed findings consistent with ink and an associated inflammatory reaction. Investigations were subsequently performed to assess the impact of oxygen sensors on FDG-PET/CT imaging. A retrospective analysis of three clinical tumor oximetry trials involving two oxygen sensors (charcoal particulates and LiNc-BuO microcrystals) in 22 patients was performed to evaluate FDG imaging characteristics. The impact of clinically used oxygen sensors (carbon black, charcoal particulates, LiNc-BuO microcrystals) on FDG-PET/CT imaging after implantation in rat muscle (n = 12) was investigated. The retrospective review revealed no other patients with FDG avidity associated with particulate sensors. The preclinical investigation found no injected oxygen sensor whose mean standard uptake values differed significantly from sham injections. The risk of a false-positive FDG-PET/CT scan due to oxygen sensors appears low. However, in the right clinical context the potential exists that an associated inflammatory reaction may confound interpretation.

ACR Appropriateness Criteria® Pneumonia in the Immunocompetent Child.

Pneumonia is one of the most common acute infections and the single greatest infectious cause of death in children worldwide. In uncomplicated, community-acquired pneumonia in immunocompetent patients, the diagnosis is clinical and imaging has no role. The first role of imaging is to identify complications associated with pneumonia such as pleural effusion, pulmonary abscess, and bronchopleural fistula. Radiographs are recommended for screening for these complications and ultrasound and CT are recommended for confirmation. The second role of imaging is to identify underlying anatomic conditions that may predispose patients to recurrent pneumonia. CT with intravenously administered contrast is recommended for this evaluation. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Suspected Small-Bowel Obstruction.

Small-bowel obstruction is a common cause of abdominal pain and accounts for a significant proportion of hospital admissions. Radiologic imaging plays the key role in the diagnosis and management of small-bowel obstruction as neither patient presentation, the clinical examination, nor laboratory testing are sufficiently sensitive or specific enough to diagnose or guide management. This document focuses on the imaging evaluation of the two most commonly encountered clinical scenarios related to small-bowel obstruction: the acute presentation and the more indolent, low-grade, or intermittent presentation. This document hopes to clarify the appropriate utilization of the many imaging procedures that are available and commonly employed in these clinical settings. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Antenatal Hydronephrosis-Infant.

Antenatal hydronephrosis is the most frequent urinary tract anomaly detected on prenatal ultrasonography. It occurs approximately twice as often in males as in females. Most antenatal hydronephrosis is transient with little long-term significance, and few children with antenatal hydronephrosis will have significant obstruction, develop symptoms or complications, and require surgery. Some children will be diagnosed with more serious conditions, such as posterior urethral valves. Early detection of obstructive uropathy is necessary to mitigate the potential morbidity from loss of renal function. Imaging is an integral part of screening, diagnosis, and monitoring of children with antenatal hydronephrosis. Optimal timing and appropriate use of imaging can reduce the incidence of late diagnoses and prevent renal scarring and other complications. In general, follow-up neonatal ultrasound is recommended for all cases of antenatal hydronephrosis, while further imaging, including voiding cystourethrography and nuclear scintigraphy, is recommended for moderate or severe cases, or when renal parenchymal or bladder wall abnormalities are suspected. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.