Looking Into the Future: The Current and Future State of IR in Canada.

This review explores the priorities and future opportunities of interventional radiology in Canada.

Renal hemofiltration prevents metabolic acidosis and reduces inflammation during normothermic machine perfusion of the vascularized composite allograft: A preclinical study.

INTRODUCTION: Recent experimental evidence suggests normothermic machine perfusion of the vascularized composite allograft results in improved preservation compared to static cold storage, with less reperfusion injury in the immediate post-operative period. However, metabolic acidosis is a common feature of vascularized composite allograft perfusion, primarily due to the inability to process metabolic by-products. We evaluated the impact of combined limb-kidney perfusion on markers of metabolic acidosis and inflammation in a porcine model. METHODS: Ten paired pig forelimbs were used for this study, grouped as either limb-only (LO, n = 5) perfusion, or limb-kidney (LK, n = 5) perfusion. Infrared thermal imaging was used to determine homogeneity of perfusion. Lactate, bicarbonate, base, pH, and electrolytes, along with an inflammatory profile generated via the quantification of cytokines and cell-free DNA in the perfusate were recorded. RESULTS: The addition of a kidney to a limb perfusion circuit resulted in the rapid stabilization of lactate, bicarbonate, base, and pH. Conversely, the LO circuit became progressively acidotic, correlating in a significant increase in pro-inflammatory cytokines. Global perfusion across the limb was more homogenous with LK compared to LO. CONCLUSION: The addition of a kidney during limb perfusion results in significant improvements in perfusate biochemistry, with no evidence of metabolic acidosis.

Simultaneous versus rapid serial interventions in a hybrid operating suite for severely injured patients: a prospective evaluation of differences in RAPTOR techniques and outcomes.

BACKGROUND: Open surgical and percutaneous endovascular procedures aimed at arresting traumatic life-threatening hemorrhage are usually performed in rapid serial fashion by surgeons and interventional radiologists; truly simultaneous procedures require modifications in technique, workflow and team collaboration. The primary objective of this study was to prospectively audit outcomes in patients with ongoing hemorrhage who underwent truly simultaneous open and percutaneous procedures. METHODS: We prospectively evaluated the cases of all severely injured patients who required an open and percutaneous procedure within the hybrid RAPTOR (resuscitation with angiography, percutaneous techniques and operative repair) suite at the Foothills Medical Centre, Calgary, Alberta, Canada, between Apr. 4, 2013, and Dec. 5, 2019. We compared outcomes between the truly simultaneous and rapid serial cases. RESULTS: Thirty-five patients (31 [89%] male, median age 46 yr, median Injury Severity Score 30, blunt mechanism in 26 cases [74%]) underwent a hybrid intervention in the RAPTOR suite to stop ongoing hemorrhage during the study period. Twenty-three patients (66%) had a rapid serial procedure, and 12 (34%) had a truly simultaneous procedure. Demographic characteristics were similar between the 2 groups. Compared to the rapid serial group, a higher proportion of patients in the truly simultaneous group were hemodynamically unstable (11 [92%] v. 13 [56%], p = 0.03) and required damage-control procedures (10 [83%] v. 12 [52%], p = 0.03). The time from hospital arrival to procedure initiation was shorter for the truly simultaneous group (mean 31 min v. 59 min, p = 0.02), and a lower proportion had initial radiologic studies (3 [25%] v. 16 [70%], p = 0.01). The median hospital length of stay, intensive care unit stay and mortality rate were similar between the 2 groups. CONCLUSION: Truly simultaneous open and percutaneous procedures to stop ongoing hemorrhage were unique in both patient and procedural details. For the most severely injured patients, the provision of truly simultaneous modalities is necessary to achieve clinical outcomes equivalent to those of less ill patients.

Distinct Cellular Mechanisms Underlie Smooth Muscle Turnover in Vascular Development and Repair.

RATIONALE: Vascular smooth muscle turnover has important implications for blood vessel repair and for the development of cardiovascular diseases, yet lack of specific transgenic animal models has prevented it's in vivo analysis. OBJECTIVE: The objective of this study was to characterize the dynamics and mechanisms of vascular smooth muscle turnover from the earliest stages of embryonic development to arterial repair in the adult. METHODS AND RESULTS: We show that CD146 is transiently expressed in vascular smooth muscle development. By using CRISPR-Cas9 genome editing and in vitro smooth muscle differentiation assay, we demonstrate that CD146 regulates the balance between proliferation and differentiation. We developed a triple-transgenic mouse model to map the fate of NG2+CD146+ immature smooth muscle cells. A series of pulse-chase experiments revealed that the origin of aortic vascular smooth muscle cells can be traced back to progenitor cells that reside in the wall of the dorsal aorta of the embryo at E10.5. A distinct population of CD146+ smooth muscle progenitor cells emerges during embryonic development and is maintained postnatally at arterial branch sites. To characterize the contribution of different cell types to arterial repair, we used 2 injury models. In limited wire-induced injury response, existing smooth muscle cells are the primary contributors to neointima formation. In contrast, microanastomosis leads to early smooth muscle death and subsequent colonization of the vascular wall by proliferative adventitial cells that contribute to the repair. CONCLUSIONS: Extensive proliferation of immature smooth muscle cells in the primitive embryonic dorsal aorta establishes the long-lived lineages of smooth muscle cells that make up the wall of the adult aorta. A discrete population of smooth muscle cells forms in the embryo and is postnatally sustained at arterial branch sites. In response to arterial injuries, existing smooth muscle cells give rise to neointima, but on extensive damage, they are replaced by adventitial cells.

Contrast-enhanced US in Local Ablative Therapy and Secondary Surveillance for Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) has a high incidence of recurrence following therapy. Therefore, secondary surveillance (scheduled follow-up imaging after treatment) is an important part of disease management. The recent approval in the United States for use of a microbubble-based contrast agent for US liver imaging promotes the increased use of contrast-enhanced US (CEUS) in patients with HCC. Although the criteria for the diagnosis of HCC at CEUS are well described, there is a paucity of published literature describing the role of CEUS in ablative therapy and secondary surveillance. In the setting of ablative therapy, CEUS can have vital roles, including patient selection, intraprocedural guidance, and immediate postprocedural assessment. Although CEUS is not widely used, the authors found that it can be used to accurately detect residual or recurrent tumor, characterize the geographic pattern of recurrence (intrazonal, extrazonal, segmental, or remote), and assess for tumor in vein. In addition, similar to primary surveillance, secondary surveillance includes assessment of the entire liver for evaluation of new nodules. Arterial phase hyperenhancement is the reference standard characteristic of disease recurrence at secondary surveillance with CEUS. ©RSNA, 2019 See discussion on this article by Rodgers.

Clinical IR in Canada: The Evolution of a Revolution.

PURPOSE: To investigate the current status and evolution of both the interventional radiologist's role as a clinician and the practice of interventional radiology (IR) over the past decade in Canada. MATERIALS AND METHODS: In 2015, an online survey was e-mailed to 210 interventional radiologists, including all Canadian active members of the Canadian Interventional Radiology Association (CIRA) and nonmembers who attended CIRA's annual meeting. Comparisons were made between interventional radiologists in academic versus community practice. The results of the 2015 survey were compared with CIRA's national surveys from 2005 and 2010. RESULTS: A total of 102 interventional radiologists responded (response rate 49%). Significantly more academic versus community interventional radiologists performed chemoembolization, transjugular intrahepatic portosystemic shunt, aortic interventions, and arteriovenous malformation embolization (P < .05). Ninety percent of respondents were involved in longitudinal patient care, which had increased by 42% compared with 2005; 46% of interventional radiologists had overnight admitting privileges, compared with 39% in 2010 and 29% in 2005. Eighty-six percent of interventional radiologists accepted direct referrals from family physicians, and 83% directly referred patients to other consultants. Sixty-three percent participated in multidisciplinary tumor board. The main challenges facing interventional radiologists included a lack of infrastructure, inadequate remuneration for IR procedures, and inadequate funding for IR equipment. Significantly more community versus academic interventional radiologists perceived work volume as an important issue facing the specialty in 2015 (60% vs 34%; P = .02). CONCLUSIONS: Over the past decade, many Canadian interventional radiologists have embraced the interventional radiologist-clinician role. However, a lack of infrastructure and funding continue to impede more widespread adoption of clinical IR practice.

Interventional Radiology in Canada: Current Challenges and Future Directions.

OBJECTIVE: We aim to define the practice of interventional radiology (IR) in Canada, barriers that have been faced by interventional radiologists, and ways in which the Canadian Interventional Radiology Association (CIRA) have attempted to address these issues. CONCLUSION: IR has faced significant challenges in the Canadian setting. Recognizing the need to address these challenges, leaders in the field of IR in Canada founded the CIRA to serve as our national voice and lobby group.

Strategies to Reduce Ischemia Reperfusion Injury in Vascularized Composite Allotransplantation of the Limb.

An important and often underinvestigated contributor to solid organ transplant rejection is ischemia reperfusion injury. This pathophysiological response releases damaging reactive oxygen species and cell stress signals that initiate inflammation, which has a critical role in priming the immune system for allorecognition. In time, this renders graft dysfunction and how this response is mediated in composite tissues remains unknown. Current protocols are drawn from solid organ transplantation with little scientific basis as to how this informs current hand transplantation practices. In addition to preservation flush and allograft cooling, machine perfusion is placing itself experimentally as a concept that could act to promote viability and increase the critical ischemic window, which is especially beneficial at a time of limited donors. With the increasing prevalence worldwide of hand transplantation, we review the potential contribution of ischemia reperfusion injury to hand allograft rejection including both current and experimental strategies.

The dynamic anatomy and patterning of skin.

The skin is often viewed as a static barrier that protects the body from the outside world. Emphasis on studying the skin's architecture and biomechanics in the context of restoring skin movement and function is often ignored. It is fundamentally important that if skin is to be modelled or developed, we do not only focus on the biology of skin but also aim to understand its mechanical properties and structure in living dynamic tissue. In this review, we describe the architecture of skin and patterning seen in skin as viewed from a surgical perspective and highlight aspects of the microanatomy that have never fully been realized and provide evidence or concepts that support the importance of studying living skin's dynamic behaviour. We highlight how the structure of the skin has evolved to allow the body dynamic form and function, and how injury, disease or ageing results in a dramatic changes to the microarchitecture and changes physical characteristics of skin. Therefore, appreciating the dynamic microanatomy of skin from the deep fascia through to the skin surface is vitally important from a dermatological and surgical perspective. This focus provides an alternative perspective and approach to addressing skin pathologies and skin ageing.

Endovascular therapy for acute trauma: a pictorial review.

The traditional role of radiology in the multidisciplinary approach to modern trauma care has been primarily diagnostic and noninvasive. With the advent of more sophisticated and faster imaging equipment, computed tomography has further entrenched its role as the workhorse of trauma imaging. However, the specialty has evolved over the years with various therapeutic techniques now part of the interventional radiology armamentarium. Several of these techniques have become essential for the management of critically ill trauma patients. This article provides an overview of the common imaging findings of vascular and solid organ trauma from head to toe and subsequent endovascular interventions in these critically ill trauma patients.

Delayed intimal blowout after endovascular repair of aortic dissection.

The authors have seen four cases of asymptomatic delayed intimal injury adjacent to a stent graft diagnosed 7 to 16 months after thoracic endovascular aortic repair. Endovascular repeat intervention was successfully performed in three of the four cases as described in the present report. A second consecutive "intimal blowout" in one patient remains under close radiologic surveillance. Possible causes for the intimal blowouts, including stent-graft size, landing zone anatomy, and intrinsically weak aortic tissue, are discussed.

Explaining With Examples: Lessons Learned From Crowdsourced Introductory Description of Information Visualizations.

Data visualizations have been increasingly used in oral presentations to communicate data patterns to the general public. Clear verbal introductions of visualizations to explain how to interpret the visually encoded information are essential to convey the takeaways and avoid misunderstandings. We contribute a series of studies to investigate how to effectively introduce visualizations to the audience with varying degrees of visualization literacy. We begin with understanding how people are introducing visualizations. We crowdsource 110 introductions of visualizations and categorize them based on their content and structures. From these crowdsourced introductions, we identify different introduction strategies and generate a set of introductions for evaluation. We conduct experiments to systematically compare the effectiveness of different introduction strategies across four visualizations with 1,080 participants. We find that introductions explaining visual encodings with concrete examples are the most effective. Our study provides both qualitative and quantitative insights into how to construct effective verbal introductions of visualizations in presentations, inspiring further research in data storytelling.

A pilot prospective cohort study using experimental quantification of early peripheral nerve regeneration with high-frequency three-dimensional tomographic ultrasound (HFtUS).

Quantification of peripheral nerve regeneration after injury relies upon subjective outcome measures or electrophysiology assessments requiring fully regenerated neurons. Nerve surgeons and researchers lack objective, quantifiable information on the site of surgical repair and regenerative front. To address this need, we developed a quantifiable, visual, clinically available measure of early peripheral nerve regeneration using high-frequency, three-dimensional, tomographic ultrasound (HFtUS). We conducted a prospective, longitudinal study of adult patients with ulnar and/or median nerve injury of the arm undergoing direct epineurial repair within 5 days of injury. Assessment of morphology, volumetric and 3D grey-scale quantification of cross-sectional views were made at baseline up to 15 months post-surgery. Sensory and motor clinical outcome measures and patient reported outcome measures (PROMs) were recorded. Five participants were recruited to the study. Our data demonstrated grey-scale values (an indication of axonal density) increased in distal stumps within 2-4 months after repair, returning to normal as regeneration completed (4-6 months) with concomitant reduction in intraneural volume as surgical oedema resolved. Two patients with abnormal regeneration were characterized by increased intraneural volume and minimal grey-scale change. HFtUS may quantify early peripheral nerve regeneration offering a window of opportunity for surgical intervention where early abnormal regeneration is detected.

CohortVA: A Visual Analytic System for Interactive Exploration of Cohorts based on Historical Data.

In history research, cohort analysis seeks to identify social structures and figure mobilities by studying the group-based behavior of historical figures. Prior works mainly employ automatic data mining approaches, lacking effective visual explanation. In this paper, we present CohortVA, an interactive visual analytic approach that enables historians to incorporate expertise and insight into the iterative exploration process. The kernel of CohortVA is a novel identification model that generates candidate cohorts and constructs cohort features by means of pre-built knowledge graphs constructed from large-scale history databases. We propose a set of coordinated views to illustrate identified cohorts and features coupled with historical events and figure profiles. Two case studies and interviews with historians demonstrate that CohortVA can greatly enhance the capabilities of cohort identifications, figure authentications, and hypothesis generation.

DPVisCreator: Incorporating Pattern Constraints to Privacy-preserving Visualizations via Differential Privacy.

Data privacy is an essential issue in publishing data visualizations. However, it is challenging to represent multiple data patterns in privacy-preserving visualizations. The prior approaches target specific chart types or perform an anonymization model uniformly without considering the importance of data patterns in visualizations. In this paper, we propose a visual analytics approach that facilitates data custodians to generate multiple private charts while maintaining user-preferred patterns. To this end, we introduce pattern constraints to model users' preferences over data patterns in the dataset and incorporate them into the proposed Bayesian network-based Differential Privacy (DP) model PriVis. A prototype system, DPVisCreator, is developed to assist data custodians in implementing our approach. The effectiveness of our approach is demonstrated with quantitative evaluation of pattern utility under the different levels of privacy protection, case studies, and semi-structured expert interviews.

The incidence and management of peripheral nerve injury in England (2005-2020).

Peripheral nerve injury (PNI) is a significant health problem that confers lifelong impact on those injured. Current interventions are purely surgical; however, outcomes remain poor. There is a lack of high-quality epidemiological data that is needed to identify populations involved, current healthcare demands, and ensure resources are distributed to the greatest effect, to reduce the injury burden. METHODS: Anonymized hospital episode statistical (HES) data on admitted patient care was obtained from NHS Digital for all National Health Service (NHS) patients sustaining PNI of all body regions between 2005 and 2020. Total numbers of finished consultant episodes (FCEs) or FCEs/100,000 population were used to demonstrate changes in demographic variables, anatomical locations of injury, mechanisms of injury, speciality, and main operation. RESULTS: There was a mean national incidence of 11.2 (95% CI 10.9, 11.6) events per 100,000 population per year. Males were at least twice as likely (p < 0.0001) to sustain a PNI. Upper limb nerves at or distal to the wrist were most commonly injured. Knife injuries increased (p < 0.0001), whereas glass injuries decreased (p < 0.0001). Plastic surgeons increasingly managed PNI (p = 0.002) as opposed to orthopaedic surgeons (p = 0.006) or neurosurgeons (p = 0.001). There was an increase in neurosynthesis (p = 0.022) and graft procedures (p < 0.0001) during the study period. DISCUSSION: PNI is a significant national healthcare problem predominantly affecting distal, upper limb nerves of men of working age. Injury prevention strategies, improved targeted funding and rehabilitation pathways are needed to reduce the injury burden and improve patient care.

Clinical consensus statement: Establishing the roles of locoregional and systemic therapies for the treatment of intermediate-stage hepatocellular carcinoma in Canada.

BACKGROUND: Hepatocellular carcinoma (HCC) a leading cause of cancer mortality worldwide and approximately one-third of patients present with intermediate-stage disease. The treatment landscape of intermediate-stage HCC is rapidly evolving due to developments in local, locoregional and systemic therapies. Treatment recommendations focused on this heterogenous disease stage and that take into account the Canadian reality are lacking. To address this gap, a pan-Canadian group of experts in hepatology, transplant, surgery, radiation therapy, nuclear medicine, interventional radiology, and medical oncology came together to develop consensus recommendations on management of intermediate-stage HCC relevant to the Canadian context. METHODS: A modified Delphi framework was used to develop consensus statements with strengths of recommendation and supporting levels of evidence graded using the AHA/ACC classification system. Tentative consensus statements were drafted based on a systematic search and expert input in a series of iterative feedback cycles and were then circulated via online survey to assess the level of agreement. RESULTS & CONCLUSION: The pre-defined ratification threshold of 80 % agreement was reached for all statements in the areas of multidisciplinary treatment (n = 4), intra-arterial therapy (n = 14), biologics (n = 5), radiation therapy (n = 3), surgical resection and transplantation (n = 7), and percutaneous ablative therapy (n = 4). These generally reflected an expansion in treatment options due to developments in previously established or emergent techniques, introduction of new and more active therapies and increased therapeutic flexibility. These developments have allowed for greater treatment tailoring and personalization as well as a paradigm shift toward strategies with curative intent in a wider range of disease settings.

Iatrogenic Arteriovenous Fistula: A Rare Complication of Pacemaker Implantation.

Severe vascular complications associated with pacemaker implantation are rare. Typically, they are overt, and require immediate resolution. We present 2 patients with insidious presentation of arteriovenous fistulae due to pacemaker implantation that were recognized early post-implantation. Both were repaired endovascularly and had good outcomes post-repair. (Level of Difficulty: Intermediate.).

A new proposal for secondary surveillance following potentially curative therapy of HCC: alternating MRI and CEUS.

PURPOSE: A high recurrence rate following ablative therapy of hepatocellular carcinoma (HCC) necessitates routine follow-up imaging (secondary surveillance) to facilitate early re-treatment. We evaluate our unique secondary surveillance algorithm (with use of alternating MRI and CEUS) by assessment of the relative diagnostic accuracy of MRI and CEUS in detection of residual/recurrent tumor. Potential benefits of alternating surveillance are compared to the use of MRI alone. MATERIALS AND METHODS: This prospective observational IRB approved study included 231 patients with 354 treated tumors between January 2017 and June 2020. Treated lesions underwent secondary surveillance for a minimum of 7 months and up to 3 years, median follow-up 14 months. Secondary surveillance involved MRI performed at 1 month after treatment, followed by CEUS and MRI at alternate 3-month intervals (i.e., CEUS at month 4, MRI at month 7, etc.), for a total of 2 years. An equivocal finding on one imaging modality triggered expeditious evaluation with the alternate modality. Arterial phase hyperenhancement and washout comprise the classic features of recurrent tumor on both modalities. RESULTS: A total of 746 MRI and 712 CEUS examinations were performed, and a total of 184 tumor recurrences detected, MRI (n = 82) and CEUS (n = 102) (p = 0.19). There was no difference in the sensitivity (71.0-85.0% and 80.9-92.0%), specificity (97.4-99.2% and 98.5-99.9%), and area under the ROC curve (0.85-0.92 and 0.91-0.96) between MRI and CEUS, respectively. 23 of 82 recurrent tumors identified on MRI were equivocal and confirmed with expedited CEUS. 9 equivocal cases on MRI were disproved by expedited CEUS. On CEUS, 1 of the 102 recurrent tumors was equivocal and confirmed on MRI, and 2 equivocal CEUS cases were disproved by MRI. CONCLUSION: MRI and CEUS performed similarly in our secondary surveillance algorithm for HCC in their ability to detect tumor recurrence, and showed no significant difference in their relative diagnostic test accuracy measures. Of greater interest, equivocal results on MRI (typically due to difficulty in distinguishing tumor recurrence from post-treatment change/shunting) were either confirmed or disproven by CEUS in all cases. Secondary surveillance of treated HCC with alternating MRI and CEUS shows equivalent performance of each modality. CEUS resolves equivocal MRI and optimally demonstrates APHE and washout in tumor recurrence.

Arginase Signalling as a Key Player in Chronic Wound Pathophysiology and Healing.

Arginase (ARG) represents an important evolutionarily conserved enzyme that is expressed by multiple cell types in the skin. Arg acts as the mediator of the last step of the urea cycle, thus providing protection against excessive ammonia under homeostatic conditions through the production of L-ornithine and urea. L-ornithine represents the intersection point between the ARG-dependent pathways and the urea cycle, therefore contributing to cell detoxification, proliferation and collagen production. The ARG pathways help balance pro- and anti-inflammatory responses in the context of wound healing. However, local and systemic dysfunctionalities of the ARG pathways have been shown to contribute to the hindrance of the healing process and the occurrence of chronic wounds. This review discusses the functions of ARG in macrophages and fibroblasts while detailing the deleterious implications of a malfunctioning ARG enzyme in chronic skin conditions such as leg ulcers. The review also highlights how ARG links with the microbiota and how this impacts on infected chronic wounds. Lastly, the review depicts chronic wound treatments targeting the ARG pathway, alongside future diagnosis and treatment perspectives.