Impact of systolic dominant pulmonary venous flow morphology on outcomes after mitral transcatheter edge-to-edge repair.

BACKGROUND: The prognostic significance of intraprocedural pulsed-wave Doppler analysis of pulmonary venous flow (PVF) during mitral transcatheter edge-to-edge repair (TEER) remains understudied. We aimed to investigate the prognostic value of systolic dominant-PVF (SD-PVF) morphology post-TEER. METHODS: In a retrospective analysis from December 2019 to December 2022, patients undergoing mitral TEER were categorized into SD-PVF and systolic blunting (SB)-PVF groups based on post-TEER morphology. The primary endpoint was a composite of all-cause mortality or heart failure hospitalization at 1 year. We investigated the association of PVF morphology post-TEER with the primary endpoint at 1 year using Cox regression and compared the prognostic accuracy of PVF variables through receiver operating characteristic (ROC) curve analysis. RESULTS: Among 187 patients (mean age 76.4 ± 10.5 years, 51.3% primary etiology), residual mitral regurgitation (MR) ≤mild was observed in 147 (82.4%) patients and 105 (56.2%) had SD-PVF post-TEER. Patients with SD-PVF had a lower incidence of >2+ residual MR after clip deployment, at 30 days (2.1% vs. 13.1%; p = 0.005) and at 1 year (1.4% vs. 9%; p = 0.08). SD-PVF post-TEER was independently associated with the primary endpoint (HR = 0.59, 95% CI = 0.39-0.87; p = 0.009). ROC curve analysis of the prognostic accuracy of SD-PVF demonstrated an AUC of 0.64 (95% CI = 0.54-0.73), comparable to other quantitative measures of PVF. CONCLUSION: Assessing PVF morphology after clip deployment offers a simple prognostic tool for patients undergoing mitral TEER. Multicenter cohorts will be necessary to further investigate its prognostic value.

Systematic Approach to Pediatric Macrocephaly.

Macrocephaly, defined as a head circumference greater than 2 standard deviations above the mean, is a relatively common presenting symptom in the pediatric population at routine well-child examinations and a common indication for neuroimaging. Multiple imaging modalities are complementary in evaluating macrocephaly, including US, CT, and MRI. The differential diagnosis for macrocephaly is broad, and many disease processes lead to macrocephaly only when the sutures are open. In patients with closed sutures, these entities instead lead to increased intracranial pressure, according to the Monroe-Kellie hypothesis, which states that there is an equilibrium between intracranial constituents due to the fixed intracranial volume. The authors describe a useful paradigm for classifying macrocephaly by identifying which of the four components of the cranium (ie, cerebrospinal fluid, blood and vasculature, brain parenchyma, or calvarium) has an increased volume. Patient age, additional imaging findings, and clinical symptoms are also useful features. Most cases in the pediatric population are due to increased cerebrospinal fluid spaces, such as benign enlargement of the subarachnoid space, which must be carefully distinguished from subdural fluid collections in patients with accidental or nonaccidental trauma. Other common causes of macrocephaly are discussed, including hydrocephalus secondary to an aqueductal web, hemorrhage, or a neoplasm. The authors also provide information on some of the rarer diseases for which imaging may provide the impetus for genetic testing (eg, overgrowth syndromes and metabolic disorders). ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Imaging the Cerebral Veins in Pediatric Patients: Beyond Dural Venous Sinus Thrombosis.

The range of intracranial venous anomalies in children differs from that in adults. As a commonly encountered highly morbid disease, sinovenous thrombosis has been discussed extensively in the literature, and the associated imaging considerations are similar in pediatric and adult patients. The authors shift the focus to less frequently discussed cerebral venous diseases in pediatric patients. First, the practical embryology pertinent to malformations, syndromes, and variants such as vein of Galen aneurysmal malformation, Sturge-Weber syndrome, and developmental venous anomalies are discussed. Second, anatomic considerations that are applicable to neuroimaging in pediatric patients with cerebral venous anomalies are reviewed. In the discussion of anatomy, special attention is given to the medullary venous system that serves the cerebral white matter, superficial cortical veins (tributaries of the dural venous sinuses), and bridging veins, which carry blood from the superficial cortical veins through the potential subdural space into the dural venous sinuses. Third, the selection of imaging modalities (US, CT and CT venography, and MRI) is addressed, and various MR venographic pulse sequences (time-of-flight, phase-contrast, and contrast-enhanced sequences) are compared. Finally, a broad variety of congenital and acquired superficial and deep venous diseases in children are reviewed, with emphasis on less frequently discussed entities involving the medullary (eg, deep medullary venous engorgement and thrombosis, periventricular hemorrhagic venous infarction due to germinal matrix hemorrhage), cortical (eg, cortical venous thrombosis), and bridging (eg, acute and chronic manifestations of injury in abusive head trauma) veins, as well as the deep veins and dural venous sinuses (eg, varix). © RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Imaging of Vertebral Artery Dissection in Children: An Underrecognized Condition with High Risk of Recurrent Stroke.

Vertebral artery dissection (VAD) is a common cause of a rare condition, pediatric posterior circulation arterial ischemic stroke (PCAIS). VAD is clinically important due to the risk of multifocal and continuing infarcts from artery-to-artery thromboembolism, with the potential for occlusion of arteries that perfuse the brainstem. Early diagnosis is important, as recurrent stroke is a common effect of VAD in children. Although the relative efficacies of different treatment regimens for VAD in children remain unsettled, early initiation of treatment can mitigate the risk of delayed stroke. Clinical diagnosis of PCAIS may be delayed due to multiple factors, including nonspecific symptoms and the inability of younger patients to express symptoms. In fact, subacute or chronic infarcts are often present at initial imaging. Although the most common cause of isolated PCAIS is VAD, imaging of the cervical arteries has been historically underused in this setting. Cervical vascular imaging (MR angiography, CT angiography, and digital subtraction angiography) for VAD must be optimized to detect the sometimes subtle findings, which may be identified at initial or follow-up imaging. Osseous variants of the craniocervical junction and upper cervical spine and other extrinsic lesions that may directly injure the vertebral arteries or lead to altered biomechanics have been implicated in some cases. The authors review characteristic imaging features and optimized imaging of VAD and associated PCAIS and related clinical considerations. Identification of VAD has important implications for evaluation, treatment, and imaging follow-up, as this condition may result in progressive arteriopathy and recurrent stroke. © RSNA, 2023 Supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Three-dimensional printing, holograms, computational modelling, and artificial intelligence for adult congenital heart disease care: an exciting future.

Congenital heart disease (CHD) is often comprised of complex three-dimensional (3D) anatomy that must be well understood to assess the pathophysiological consequences and guide therapy. Thus, detailed cardiac imaging for early detection and planning of interventional and/or surgical treatment is paramount. Advanced technologies have revolutionized diagnostic and therapeutic practice in CHD, thus playing an increasing role in its management. Traditional reliance on standard imaging modalities including echocardiography, cardiac computed tomography (CT) and magnetic resonance imaging (MRI) has been augmented by the use of recent technologies such as 3D printing, virtual reality, augmented reality, computational modelling, and artificial intelligence because of insufficient information available with these standard imaging techniques. This has created potential opportunities of incorporating these technologies into routine clinical practice to achieve the best outcomes through delivery of personalized medicine. In this review, we provide an overview of these evolving technologies and a new approach enabling physicians to better understand their real-world application in adult CHD as a prelude to clinical workflow implementation.

Transcatheter mitral valve repair for primary mitral regurgitation.

The landscape of transcatheter mitral valve repair devices continues to expand, with many technologies undergoing investigation in patients with primary mitral regurgitation (MR). Transcatheter edge-to-edge repair (TEER) of the mitral valve is currently approved for management of patients with severe primary MR who are deemed to be high risk surgical candidates. The current review will focus on an integrative clinical and echocardiographic approach to guide patient selection, intra-procedural imaging guidance, and post procedural follow up in patients undergoing TEER. This review will also highlight future directions in transcatheter repair techniques of the mitral valve.

Patient-specific preprocedural planning for tricuspid valve repair and replacement procedures.

PURPOSE OF REVIEW: Despite the prevalence of tricuspid valve regurgitation disorders, isolated interventions on tricuspid valves were previously infrequent due to high mortality rates and lack of advanced clinical imaging technology. Due to advancements in cardiovascular imaging and interventional technologies tricuspid valve repairs and replacement interventions became increasingly more attainable. RECENT FINDINGS: Noninvasive clinical imaging of the tricuspid valve can be challenging, providing anincomplete assessment of unique tricuspid anatomy. 3D printing technology represents an additional tool for more comprehensive preprocedural planning of tricuspid interventions and observation of tricuspid valve geometry. Patient-specific 3D printed replicas of tricuspid valve apparatus are especially useful in highly complicated cases, where physiological tricuspid replicas allow benchtop observation of individual patient's anatomy, device implantation in physiological tricuspid valves and interactions of devices with native tricuspid tissue, frequently leading to optimization or change in operational strategy. SUMMARY: Comprehensive use of clinical imaging including echocardiography, computed tomography, and cardiac magnetic resonance along with 3D printed modeling is key to successful tricuspid repair and replacements. Patient-specific 3D printed models of tricuspid anatomy can facilitate preprocedural planning, educate patients and clinicians, and improve device design, leading to the overall improvement of patients' outcomes and care.

Intentional bioprosthetic tricuspid valve fracture to facilitate transcatheter valve-in-valve deployment.

While transcatheter valve-in-valve (ViV) implantation may reduce the number of lifetime surgical reinterventions in some patients with congenital heart disease, in other patients the bioprosthetic valve ring can lead to patient-prosthesis mismatch due to reduction of internal diameter if a transcatheter valve is implanted. A 49-year-old woman with multiple prior cardiac surgeries presented with heart failure due to bioprosthetic tricuspid valve stenosis. Initial predilation valvuloplasty suggested conventional ViV implant would produce patient-prosthesis mismatch, therefore, we intentionally fractured the bioprosthetic valve ring to facilitate optimal hemodynamics with implantation of a 29 mm transcatheter valve.

Mitral regurgitation: a contemporary review of percutaneous mitral valve repair and role of periprocedural imaging.

PURPOSE OF REVIEW: This article aims to review recent landmark clinical trials that have resulted in a paradigm shift in the management of patients with mitral regurgitation. This article additionally highlights the instrumental role that structural heart disease (SHD) imaging plays in evaluation of mitral regurgitation and determining candidacy for transcatheter mitral valve repair (TMVr), in addition to the procedural guidance and detection of complications. RECENT FINDINGS: Edge-to-edge TMVr with the MitraClip device (Abbott Vascular, Santa Clara, California) was initially studied and subsequently approved by the US Food and Drug Administration (FDA) for treatment of primary mitral regurgitation in 2013. After the publication of a landmark clinical trial in 2018, the indications have been expanded and FDA has subsequently, in 2019, approved TMVr for patients with functional mitral regurgitation. This has been paralleled by advances in cardiac imaging with more emphasis on the role of SHD imagers as a part of the heart team. SUMMARY: TMVr has revolutionized the management of mitral regurgitation and relies heavily on SHD imaging to ensure optimal outcomes.

Functional assessment of bioprosthetic mitral valves by cardiovascular magnetic resonance: An in vitro validation and comparison to Doppler echocardiography.

BACKGROUND: A comprehensive non-invasive evaluation of bioprosthetic mitral valve (BMV) function can be challenging. We describe a novel method to assess BMV effective orifice area (EOA) based on phase contrast (PC) cardiovascular magnetic resonance (CMR) data. We compare the performance of this new method to Doppler and in vitro reference standards. METHODS: Four sizes of normal BMVs (27, 29, 31, 33 mm) and 4 stenotic BMVs (27 mm and 29 mm, with mild or severe leaflet obstruction) were evaluated using a CMR- compatible flow loop. BMVs were evaluated with PC-CMR and Doppler methods under flow conditions of; 70 mL, 90 mL and 110 mL/beat (n = 24). PC-EOA was calculated as PC-CMR flow volume divided by the PC- time velocity integral (TVI). RESULTS: PC-CMR measurements of the diastolic peak velocity and TVI correlated strongly with Doppler values (r = 0.99, P < 0.001 and r = 0.99, P < 0.001, respectively). Across all conditions tested, the Doppler and PC-CMR measurement of EOA (1.4 ± 0.5 vs 1.5 ± 0.7 cm2, respectively) correlated highly (r = 0.99, P < 0.001), with a minimum bias of 0.13 cm2, and narrow limits of agreement (- 0.2 to 0.5 cm2). CONCLUSION: We describe a novel method to assess BMV function based on PC measures of transvalvular flow volume and velocity integration. PC-CMR methods can be used to accurately measure EOA for both normal and stenotic BMV's and may provide an important new parameter of BMV function when Doppler methods are unobtainable or unreliable.

Role of 3-dimensional transesophageal echocardiography in guiding transcatheter mitral valve replacement.

BACKGROUND: Transcatheter mitral valve replacement technologies have been developed to treat a wide range of mitral valve pathologies including primary and secondary mitral regurgitation, mitral stenosis, in addition to degenerative bioprosthetic valves and failed annuloplasty rings. OBJECTIVE: Transesophageal echocardiography, particularly with use of 3-dimensional imaging is key in successfully guiding these interventions. In this review, we highlight the key role of 3D transesophageal echocardiography in guiding TMVR, including valve-in-native valve, valve-in-prosthetic valve, valve-in-prosthetic ring, and valve-in-mitral annular calcification interventions.

Hemodynamic and Echocardiographic Comparison of the Lotus and CoreValve Transcatheter Aortic Valves in Patients With High and Extreme Surgical Risk: An Analysis From the REPRISE III Randomized Controlled Trial.

BACKGROUND: Comparative echocardiographic data on transcatheter aortic valve replacement systems from randomized trials are limited. The REPRISE III trial (Repositionable Percutaneous Replacement of Stenotic Aortic Valve through Implantation of Lotus Valve System - Randomized Clinical Evaluation) is a multicenter, randomized comparison of a mechanically expanded (Lotus) versus self-expanding (CoreValve) transcatheter aortic valve replacement device. This analysis rigorously assesses Doppler-derived valve hemodynamics and the impact on outcomes at 1 year in patients with extreme/high surgical risk treated with Lotus and CoreValve from REPRISE III. METHODS: REPRISE III includes patients with extreme- and high-risk aortic stenosis. Patients were enrolled at 55 centers. All transthoracic echocardiograms with Doppler were obtained following a standard protocol up to 12 months postimplant and analyzed by a core laboratory. Valve size, mean gradient, aortic valve area, and Doppler velocity index and their impact on clinical outcomes are reported. Additional parameters including paravalvular leak were evaluated using a multiparametric approach. RESULTS: A total of 912 patients were randomly assigned (2:1 ratio; 607 Lotus:305 CoreValve). Median age was 84 years, 51% of the patients were women, and the Society of Thoracic Surgeons score was 6.8±4.1. CoreValve demonstrated lower gradients and larger aortic valve area and Doppler velocity index than Lotus at discharge; the difference decreased in subsequent follow-up up to a year (all P<0.01). Lotus had lower rates of paravalvular leak that persisted over time (P<0.05). Similar outcomes were seen when comparing each valve type by size group (small, medium, large). The hemodynamic differences between valves did not translate into worse clinical outcomes. All-cause mortality was not different between the 2 groups in any of the 3 valve sizes. When comparing patients with normal valve gradients (<20 mm Hg, n=780) with those with abnormal gradients (>20 mm Hg, n=48) in the entire patient population, all-cause mortality was not different. This was also not significant when evaluating each valve type separately. Similarly, there were no differences for aortic valve area >1.1 cm2 or <1.1 cm2 and for Doppler velocity index >0.35 or <0.35 (all P=not significant). CONCLUSIONS: Lotus had significantly greater freedom from moderate or severe paravalvular leak and smaller valve area and higher gradients than CoreValve. The hemodynamic differences were not associated with any clinical differences in the composite end point of mortality, disabling stroke, and moderate paravalvular leak or with quality of life at 1 year of follow-up. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02202434.

ToxCast Chemical Landscape: Paving the Road to 21st Century Toxicology.

The U.S. Environmental Protection Agency's (EPA) ToxCast program is testing a large library of Agency-relevant chemicals using in vitro high-throughput screening (HTS) approaches to support the development of improved toxicity prediction models. Launched in 2007, Phase I of the program screened 310 chemicals, mostly pesticides, across hundreds of ToxCast assay end points. In Phase II, the ToxCast library was expanded to 1878 chemicals, culminating in the public release of screening data at the end of 2013. Subsequent expansion in Phase III has resulted in more than 3800 chemicals actively undergoing ToxCast screening, 96% of which are also being screened in the multi-Agency Tox21 project. The chemical library unpinning these efforts plays a central role in defining the scope and potential application of ToxCast HTS results. The history of the phased construction of EPA's ToxCast library is reviewed, followed by a survey of the library contents from several different vantage points. CAS Registry Numbers are used to assess ToxCast library coverage of important toxicity, regulatory, and exposure inventories. Structure-based representations of ToxCast chemicals are then used to compute physicochemical properties, substructural features, and structural alerts for toxicity and biotransformation. Cheminformatics approaches using these varied representations are applied to defining the boundaries of HTS testability, evaluating chemical diversity, and comparing the ToxCast library to potential target application inventories, such as used in EPA's Endocrine Disruption Screening Program (EDSP). Through several examples, the ToxCast chemical library is demonstrated to provide comprehensive coverage of the knowledge domains and target inventories of potential interest to EPA. Furthermore, the varied representations and approaches presented here define local chemistry domains potentially worthy of further investigation (e.g., not currently covered in the testing library or defined by toxicity "alerts") to strategically support data mining and predictive toxicology modeling moving forward.

Clinical Utility of Multidetector Computed Tomography in Redo Valve Procedures.

BACKGROUND: Transesophageal echocardiography (TEE) is recommended for diagnosis in patients suspected of prosthetic valve dysfunction, but could be limited in its ability to identify the etiology of these dysfunctions and to assess extracardiac structures. Our objective is to examine the usefulness of multidetector computed tomography (MDCT) in establishing the etiology of the dysfunctions and its clinical utility in preoperative assessment in these patients. METHODS: Twenty-two prosthetic heart valves from 20 consecutive patients who had a preoperative MDCT and underwent redo prosthetic valve procedures from December 2008 to February 2013 were examined retrospectively. Results from MDCT and TEE were compared to intraoperative findings. Extravalvular MDCT findings including coronary artery/bypass graft, high-risk features for reoperative cardiac surgery, and extracardiac findings were also assessed. RESULTS: MDCT correctly identified 15 valve regurgitation and seven valve obstructions compared to intraoperative findings. Both TEE and MDCT were able to correctly identify the etiologies in 93% (14/15) of regurgitant valves. However, MDCT was better able to identify the etiology of obstructive valves than TEE (86% [6/7] vs. 43% [3/7]) compared to intraoperative findings. In patients who had preoperative invasive angiography, MDCT correctly identified two patients with significant coronary artery disease (CAD) and ruled out 11 without significant CAD. Furthermore, MDCT detected five high-risk features for postoperative complications and eight clinically relevant extracardiac findings. CONCLUSIONS: MDCT displayed comparable or better diagnostic performance than TEE for identifying the type of dysfunction and its etiology, as well as providing additional coronary and other extravalvular evaluations useful for preoperative planning.

Bioprosthetic Mitral Transcatheter Transapical Valve-in-Valve Implantation for Mitral Stenosis in an End-Stage Renal Disease Patient.

Transcatheter mitral valve-in-valve implantation (TMVIV) is an option for patients with mitral prosthetic valve dysfunction who are at high risk for surgical valve replacement. Efficacy and safety of TMVIV is at its infancy. We report a high-risk symptomatic dialysis-dependent end-stage renal disease patient with severe bioprosthetic mitral valve stenosis who had TMVIV performed successfully.

Mandibular condyle erosion and sclerosis in pediatric patients treated with radiotherapy to the head and neck region.

Head and neck radiotherapy in children is associated with significant acute and late morbidities. Temporomandibular joint dysfunction and trismus has been widely reported in patients receiving radiotherapy for sarcomas and nasopharyngeal carcinoma; however, erosion of the mandibular condyle is a rare sequela of modern radiotherapy techniques. In this report, we present three cases of erosion of the temporomandibular joint amongst pediatric patients treated with radiotherapy for distinct head, neck and brain malignancies.

Spatio-temporal modelling of heat stress and climate change implications for the Murray dairy region, Australia.

The Murray dairy region produces approximately 1.85 billion litres of milk each year, representing about 20 % of Australia's total annual milk production. An ongoing production challenge in this region is the management of the impacts of heat stress during spring and summer. An increase in the frequency and severity of extreme temperature events due to climate change may result in additional heat stress and production losses. This paper assesses the changing nature of heat stress now, and into the future, using historical data and climate change projections for the region using the temperature humidity index (THI). Projected temperature and relative humidity changes from two global climate models (GCMs), CSIRO MK3.5 and CCR-MIROC-H, have been used to calculate THI values for 2025 and 2050, and summarized as mean occurrence of, and mean length of consecutive high heat stress periods. The future climate scenarios explored show that by 2025 an additional 12-15 days (compared to 1971 to 2000 baseline data) of moderate to severe heat stress are likely across much of the study region. By 2050, larger increases in severity and occurrence of heat stress are likely (i.e. an additional 31-42 moderate to severe heat stress days compared with baseline data). This increasing trend will have a negative impact on milk production among dairy cattle in the region. The results from this study provide useful insights on the trends in THI in the region. Dairy farmers and the dairy industry could use these results to devise and prioritise adaptation options to deal with projected increases in heat stress frequency and severity.

Contrasting pediatric specialty provider opinion between contextualized and structured radiology reports.

BACKGROUND: Structured reporting (SR) replaced narrative (free text) reporting and utilizes templated headings and subheadings with findings typically based on the anatomy included in the examination. Its use has been widely advocated by radiology and non-radiology organizations as the new reporting standard. There are, however, shortcomings to SR, such as templated text not addressing a specific clinical indication. Contextual reporting (CR) fills this gap. CR is a type of SR which is tailored to a narrow clinical indication by including pertinent positive and negative findings for that specific clinical entity. OBJECTIVE: This study assesses provider preferences for CR as compared to SR in the pediatric practice environment using a survey methodology. METHODS & MATERIALS: Surveys with examples of SR and CR reports were sent electronically to two groups. One group was focused on neurological diseases and included pediatric specialists in neurosurgery, neurology, ENT, ED, and ophthalmology (190 people), referred to as the pediatric neuroimaging group. The pediatric neuroimaging group survey contained examples of CR and SR reports of an orbital CT for orbital cellulitis and a head CT for stroke. The other group was focused on gastrointestinal diseases, and included pediatric specialists in gastroenterology, general surgery, and the ED (159 people), referred to as the pediatric gastrointestinal (GI) imaging group. The pediatric GI imaging group survey contained example reports of an abdominal CT for appendicitis and an MRI enterography for Crohn's disease. Surveys utilizing a 5-point Likert scale were analyzed via Fischer's exact test with a p-value deemed statistically significant at less than 0.05. RESULTS: 349 individuals were contacted to participate in the survey. There were 81 (23 %, 81/349) survey respondents; 41 (22 %, 41/190) from the neuro group, and 40 (25 %, 40/159) from the GI group. 56 % (45/81) of all respondents preferred CR reports over traditional SR reports, while 29 % (23/81) did not. Most respondents (59 %, 48/81) indicated that CR reports are easier to interpret than traditional SR reports. Respondents from the pediatric neuroimaging group favored CR reports to a lesser degree (44 %, 36/81) compared to respondents from the pediatric GI imaging group (68 %, 55/81). CONCLUSIONS: We learned from this survey that it would be beneficial to be very intentional about selecting clinical indications where CR would be most valued rather than trying to develop CR for any specific clinical indication. The study results indicate it is reasonable to continue further efforts at exploring the utility of contextualized reports.

Physical and Computational Modeling for Transcatheter Structural Heart Interventions.

Structural heart disease interventions rely heavily on preprocedural planning and simulation to improve procedural outcomes and predict and prevent potential procedural complications. Modeling technologies, namely 3-dimensional (3D) printing and computational modeling, are nowadays increasingly used to predict the interaction between cardiac anatomy and implantable devices. Such models play a role in patient education, operator training, procedural simulation, and appropriate device selection. However, current modeling is often limited by the replication of a single static configuration within a dynamic cardiac cycle. Recognizing that health systems may face technical and economic limitations to the creation of "in-house" 3D-printed models, structural heart teams are pivoting to the use of computational software for modeling purposes.