Sarah Power

Nanotechnology and its relationship to interventional radiology. Part II: Drug Delivery, Thermotherapy, and Vascular Intervention.

Nanotechnology can be defined as the design, creation, and manipulation of structures on the nanometer scale. This two-part review is intended to acquaint the interventionalist with the field of nanotechnology, and provide an overview of potential applications, while highlighting advances relevant to interventional radiology. Part 2 of the article concentrates on drug delivery, thermotherapy, and vascular intervention. In oncology, advances in drug delivery allow for improved efficacy, decreased toxicity, and greater potential for targeted therapy. Magnetic nanoparticles show potential for use in thermotherapy treatments of various tumours, and the effectiveness of radiofrequency ablation can be enhanced with nanoparticle chemotherapy agents. In vascular intervention, much work is focused on prevention of restenosis through developments in stent technology and systems for localised drug delivery to vessel walls. Further areas of interest include applications for thrombolysis and haemostasis.

Value of CT angiography in anterior circulation large vessel occlusive stroke: Imaging findings, pearls, and pitfalls

Hyperacute stroke imaging is playing an increasingly important role in determining management decisions in acute stroke patients, particularly patients with large vessel occlusive stroke who may benefit from endovascular intervention. CT angiography (CTA) is an important tool in the work-up of the acute stroke patient. It reliably detects large occlusive thrombi in proximal cerebral arteries and is a quick and highly accurate method in identifying candidates for endovascular stroke treatment. In this article we review the imaging findings on CTA in acute large vessel occlusive stroke using a pictorial case based approach. We retrospectively reviewed CTA studies in 48 patients presenting with acute anterior circulation large vessel occlusive stroke who were brought for intra-arterial acute stroke intervention. We discuss and illustrate patterns of proximal intracranial arterial occlusion, collateralization to the occluded territory, as well as reviewing some important pearls, pitfalls and teaching points in CTA assessment of the acute stroke patient. Performed from the level of the aortic arch CTA also gives valuable information regarding the state of other vessels in the acute stroke patient, identifying additional significant vascular stenoses or occlusions, and as we illustrate, can demonstrate other clinically significant findings which may impact on patient management and outcome.

Outcome Prediction in Acute Stroke Patients Considered for Endovascular Treatment: a Novel Tool

Functional outcome following emergent intra-arterial thrombectomy is variable and likely reflects the heterogeneous characteristics of acute stroke patients. The aims of our study were (1) to study which pre-treatment variables correlate with functional outcome and (2) to devise a tool which would reliably predict outcome. Prospective data of patients treated with intra-arterial mechanical thrombectomy in our institution between 2010 and 2012 were collected. A preliminary univariate analysis of baseline variables was performed and data outliers were identified by constructing scatter and box plots. Systematic bivariate analysis was then carried out using a linear regression model and the individual contributing weights of the variables to outcome calculated. The B and constant values from the regression were used to construct a predictive formula. Fifty-seven patients, 35 males (61.4%) and 22 females (38.6%) with a mean age of 62.3 years (range 26–87) were included in the cohort. Statistical correlations of baseline variables and functional outcome showed that age, National Institutes of Health Stroke Scale at presentation and CT leptomeningeal collaterals were strongly correlated (p<0.01), and were later included in the linear regression model. A tool was devised from the regression formula combining weighted inputs of the three variables. Regression statistics and residual analysis were then performed to assess the accuracy and reliability of the proposed tool. The proposed tool is easy to use and reliably predicts functional outcome prior to endovascular therapy. It may help clinical decision-making in the acute setting and offers ‘tailor-made’ outcome expectations.

Endovascular treatment for acute ischaemic stroke with large vessel occlusion: the experience of a regional stroke service.

AIM To report the experience of a regional stroke referral service with endovascular treatment for patients with acute ischaemic stroke (AIS) and large vessel occlusion. MATERIALS AND METHODS A prospective review was undertaken of 93 consecutive cases receiving endovascular treatment for AIS over a 42-month period (January 2010 to June 2013). The National Institutes of Health Stroke Scale (NIHSS), location of large vessel occlusion, details of endovascular procedure, and degree of reperfusion achieved (Thrombolysis In Cerebral Infarction [TICI] score) were recorded. Mortality and functional outcome (modified Rankin Scale [mRS]) were measured at 90 days. RESULTS The mean patient age was 62 years (range 26-87 years). The mean NIHSS at presentation was 16 (range 6-29). All patients had confirmed proximal large-artery occlusion on computed tomography (CT) angiography: 87 in the anterior circulation, six in the posterior circulation. Of the 93 patients treated, 64 (69%) received intravenous thrombolysis. Successful reperfusion (TICI grade 2a to 3) was achieved in 80 (86%) cases. There were 13 (14%) cases of failed vessel recanalisation (TICI grade 0). Good functional outcome (mRS ≤2) was achieved in 51 (55%) cases. The 90-day mortality was 20 (22%) cases. Fifty-seven (61%) cases were transferred from outside centres. There was no significant increase in morbidity or mortality for transferred patients. CONCLUSION Successful endovascular recanalisation can result in good functional outcomes for patients with AIS and large vessel occlusion. Our interventional neuroradiology service provides endovascular treatment as part of a regional stroke service without increase in morbidity or mortality for patients transferred from outside institutions.

Nanotechnology and its Relationship to Interventional Radiology. Part I: Imaging

Nanotechnology refers to the design, creation, and manipulation of structures on the nanometer scale. Interventional radiology stands to benefit greatly from advances in nanotechnology because much of the ongoing research is focused toward novel methods of imaging and delivery of therapy through minimally invasive means. Through the development of new techniques and therapies, nanotechnology has the potential to broaden the horizon of interventional radiology and ensure its continued success. This two-part review is intended to acquaint the interventionalist with the field of nanotechnology, and provide an overview of potential applications, while highlighting advances relevant to interventional radiology. Part I of the article deals with an introduction to some of the basic concepts of nanotechnology and outlines some of the potential imaging applications, concentrating mainly on advances in oncological and vascular imaging.

Endovascular thrombectomy beyond 12 hours of stroke onset: a stroke network’s experience of late intervention

Background Selected patients with proximal anterior circulation ischemic stroke who demonstrate limited infarct and sufficient penumbra may benefit from endovascular thrombectomy (EVT) beyond conventional time limits. Objective To perform a retrospective review of all cases of EVT performed at our institution for proximal anterior circulation acute ischemic stroke with onset >12 hours. Materials and methods Patients were assessed with non-contrast CT brain and multiphase CT angiography, with Alberta Stroke Program Early CT Score (ASPECTS) and collateral grade informing patient selection. Data, including patient demographics, workflow, neuroimaging findings, procedural details, recanalization rates, and 90-day functional outcomes, were collected. Results Of the 542 consecutive endovascular thrombectomy cases performed during the study period, 25 (4.6%) were >12 hours from stroke onset. Median age was 69 years (IQR 55–80), median National Institute of Health Stroke Scale score on presentation was 14 (IQR 11–18.5), median ASPECTS was 8 (IQR 8–9), and rate of moderate–good collateral status was 96% (n=24). Median time to groin puncture was 14 hours 40 min (IQR 12 hours 36 min – 16 hours 18 min). Rate of successful recanalization (modified Thrombolysis in Cerebral infarction 2b–3) was 88% (n=22). Rate of functional independence (90-day modified Rankin Scale score 0–2) was 52% (n=13). There were no cases of symptomatic intracranial haemorrhage and 90-day mortality rate was 12% (n=3). Conclusion With the use of ASPECTS and collateral grade to guide patient selection, good functional outcome with acceptable safety parameters may be achieved in patients undergoing EVT beyond 12 hours from stroke onset.

Drip and ship versus direct to endovascular thrombectomy: The impact of treatment times on transport decision-making:

Introduction In ischaemic stroke care, fast reperfusion is essential for disability free survival. It is unknown if bypassing thrombolysis centres in favour of endovascular thrombectomy (mothership) outweighs transport to the nearest thrombolysis centre for alteplase and then transfer for endovascular thrombectomy (drip-and-ship). We use conditional probability modelling to determine the impact of treatment times on transport decision-making for acute ischaemic stroke. Materials and methods Probability of good outcome was modelled using a previously published framework, data from the Irish National Stroke Register, and an endovascular thrombectomy registry at a tertiary referral centre in Ireland. Ireland was divided into 139 regions, transport times between each region and hospital were estimated using Google’s Distance Matrix Application Program Interface. Results were mapped using ArcGIS 10.3. Results Using current treatment times, drip-and-ship rarely predicts best outcomes. However, if door to needle times are reduced to 30 min, drip-and-ship becomes more favourable; even more so if turnaround time (time from thrombolysis to departure for the endovascular thrombectomy centre) is also reduced. Reducing door to groin puncture times predicts better outcomes with the mothership model. Discussion This is the first case study modelling pre-hospital transport for ischaemic stroke utilising real treatment times in a defined geographic area. A moderate improvement in treatment times results in significant predicted changes to the optimisation of a national acute stroke patient transport strategy. Conclusions Modelling patient transport for system-level planning is sensitive to treatment times at both thrombolysis and thrombectomy centres and has important implications for the future planning of thrombectomy services.

Decreasing incidence of subarachnoid hemorrhage

Objective To determine the incidence and trends in subarachnoid hemorrhage in Ireland using data from a national database. Materials and methods We performed a retrospective nationwide query of the Irish Hospital In-patient Enquiry System (HIPE). This is a national database of all in-patient activity in acute public hospitals in Ireland. Each HIPE entry records one episode of in-patient care. The study period ranged from 1997 to 2015. Population data was obtained from the Irish Central Statistics Office, and the annual prevalence of smoking from the Irish National Tobacco Control Office. We were therefore able to calculate both crude annual acute subarachnoid hemorrhage (SAH) incidence rates, as well as population-standardized rates, and compared them with trends in the annual smoking rates. Results The mean number of SAH cases per year is 549, with 465 cases in 1997 and 517 in 2015 (range: 465–624). The absolute incidence of SAH, therefore, remained relatively stable. Due to population increases over time, the population-adjusted rate of SAH therefore decreased, from 126.9/million people/year in 1997 to 111.5/million people/year in 2015. Nationally, there was a decrease in smoking prevalence, from 31% in 1998 to 19.2% in 2015. There was a statistically significant correlation between decreasing smoking rates and decreasing population-adjusted incidence of SAH (P=<0.0001). Conclusions Our data suggests that the incidence of non-traumatic subarachnoid hemorrhage in our population appears to be decreasing, a decrease which is correlated with decreasing smoking rates. This provides important data both in terms of the epidemiology of SAH, as well as the possible role of public-health interventions in tackling both smoking and declining rates of SAH.

Two Cases of Intraventricular Hemorrhage in Young Patients

We present 2 cases of intraventricular hemorrhage (IVH) in young patients. Case 1 is a 33-year-old man who presented with collapse after acute onset occipital headache. On admission to hospital brainstem activity was absent. CT brain (figure 1a) showed a large acute intraventricular hemorrhage, underlying intraventricular mass and obstructive hydrocephalus. Autopsy examination confirmed massive intraventricular hemorrhage. Coronal section of the brain (Figure 1b) shows destruction of the diencephalon and underlying tumor fragments. Case 2 is a 28-year-old woman who presented with recent onset headache. T1W MR post contrast (Figure 1c) showed an enhancing tumor involving the 3 ventricle and right thalamus. She underwent burrhole biopsy during which there was significant intra-tumoral hemorrhage. She did not regain consciousness post-operatively and imaging confirmed a large thalamic hemorrhage.