MEDISCHE BEELDVORMING

CENTRUM MEDISCHE BEELDVORMING

ARTIKELS

ABSTRACT 1

Large odontogenic keratocyst of the mandible: a combined intra/extra oral approach followed by enucleation.

Vercruysse M, D'Haeseleire P, Kunz S, Lutin B, et al. Stomatology Edu Journal, 2019, 6(2), 129-137

OBJECTIVE An odontogenic keratocyst (OKC) of the mandible is a benign intraosseus lesion of odontogenic origin characterized by a high recurrence rate. In this case report, we highlight the challenging diagnosis and propose a potential treatment for an extensive OKC with lingual expansion.

RESULTS The combined intra/extra oral approach seems a reasonable technique for the treatment of similar extensive OKC’s in order to avoid pathological fractures as well as guaranteeing total removal of the lesion.

ABSTRACT 2

Emergency intracranial stenting in acute stroke: predictors for poor outcome and for complications.

Stracke CP, Fiehler J, Andersson T, et al. Journal of the American Heart Association, 2020, 9, e012795

INTRODUCTION/BACKGROUND Stent‐retriever thrombectomy is the first-line therapy in acute stroke with intracranial large vessel occlusion. In case of failure of stent-retriever thrombectomy, rescue stent angioplasty might be the only treatment option to achieve permanent recanalization. This study aims at identifying predictors for poor outcome and complications in a large, multicenter cohort receiving rescue stent angioplasty.

MATERIALS/METHODS We performed a retrospective analysis of patients with large vessel occlusion who were treated with rescue stent angioplasty after stent-retriever thrombectomy between 2012 and 2018 in 7 neurovascular centers. We defined 2 binary outcomes: (1) functional clinical outcome (good modified Rankin Scale, 0–2; and poor modified Rankin Scale, 4–6) and (2) early symptomatic intracerebral hemorrhage. Impacts of clinical, radiological, and interventional parameters on outcomewere assessed in uni- and multivariable logistic regression models.

RESULTS Two hundred ten patients were included with target vessels located within the anterior circulation (136 of 210; 64.8%) and posterior circulation (74 of 210; 35.2%). Symptomatic intracerebral hemorrhage occured in 22 patients, 86.4% (19 of 22) after anterior and 13.6% (3 of 22) after posterior circulation large vessel occlusion. Good functional outcome was observed in 44.8% (73 of 163). A higher National Institutes of Health Stroke Scale on admission (adjusted odds ratio, 1.10; P=0.002), a higher premorbid modified Rankin Scale (adjusted odds ratio, 2.02; P=0.049), and a modified Thrombolysis in Cerebral Infarction score of 0 to 2a after stenting (adjusted odds ratio, 23.24; P<0.001) were independent predictors of poor functional outcome.

CONCLUSION Use of rescue stent angioplasty can be considered for acute intracranial large vessel occlusion in cases after unsuccessful stent-retriever thrombectomy. Likelihood of symptomatic intracerebral hemorrhage is higher in anterior circulation stroke.

ABSTRACT 3

Intracranial stenting after failed thrombectomy in patients with moderately severe stroke: a multicenter cohort study.

Meyer L, Fiehler J, Andersson T, et al. Frontiers in Neurology, 2020, 11, 97

INTRODUCTION/BACKGROUND Recently, acute intracranial stenting (ICS) has gained more interest as a potential bailout strategy for large vessel occlusions (LVO) that are refractory to thrombectomy. However, there are currently no reports on ICS in patients with moderately severe stroke discussing the question if implementing a permanent stent is feasible and leads to improved recanalization after failed thrombectomy.

MATERIALS/METHODS We analyzed a large multicenter database of patients receiving ICS for anterior circulation LVO after failed thrombectomy. Inclusion criteria were defined as: Moderately severe stroke (National Institute Health Stroke Scale (NIHSS) ≤9 on admission), anterior circulation LVO, acute ICS after failed stent retriever MT. Primary endpoint was the

rate of improved successful recanalization after ICS defined as a modified Thrombolysis In cerebral Infarction (mTICI) score≥2b. Favorable neurological outcome was defined as an early neurological improvement (ENI) of 4 points or reaching 0 with respect to baseline NIHSS.

RESULTS Forty-one patients met the inclusion criteria. A median of 2 retrievals were performed (IQR 1-4) prior decision-making for ICS. ICS led in 90.2% (37/41) of cases to a final mTICI≥2b with significant improvement (p < 0.001) after the last retrieval attempt. The median NIHSS decreased (p = 0.178) from 7 (IQR 3.5-8) on admission to 2.5 (IQR 0-8.25) at discharge. ENI was observed in 47.4% (18/38). sICH occurred in 4.8% (2/41).

CONCLUSION ICS after failed thrombectomy appears to effectively improve recanalization rates in patients with moderately severe strokes. Thus, ICS should be considered also for paABSTRACT 4

Preclinical evaluation of the ANCD thrombectomy device: safety and efficacy in a swine clot model.

Sanchez S, Bailey L, Andersson T, et al. Journal of NeuroInterventional Surgery, 2020, DOI: 10.1136/ neurintsurg-2019-015548 INTRODUCTION/BACKGROUND The Advanced Thrombectomy System (ANCD) provides a new funnel component designed to reduce clot fragmentation and facilitate retrieval in patients with stroke by locally restricting flow, allowing distal aspiration in combination with a stent retriever (SR). OBJECTIVE To evaluate the preclinical efficacy and safety of the ANCD in a swine clot model. MATERIALS/METHODS Soft and firm clots were implanted in the lingual and cervical arteries of 11 swine to obtain Thrombolysis in Cerebral Infarction (TICI) 0 blood flow. Mechanical thrombectomy was performed with either a balloon guide catheter+Solitaire 2 stent retriever (BGC+SR, n=13) or ANCD+SR (n=13). TICI flow was evaluated and successful revascularization was defined as TICI 3 (normal perfusion). To characterize tients with baseline NIHSS ≤9 if thrombectomy fails. safety, a total of 3 passes were performed in each vessel independent of recanalization. Tissues were explanted for histopathological analysis after 3 and 30 days, respectively.

RESULTS First pass reperfusion rates were ANCD+SR: 69% and BGC+SR: 46%. Reperfusion increased after the third pass in both groups (ANCD+SR: 100%, vs BGC+SR: 77%). Recanalization was achieved after an average of 1.4 and 1.9 passes in ANCD+SR and BGC+SR (p=0.095), respectively. Vessel injury was comparable in both groups; endothelial loss at 3 days was the most common injury seen (ANCD+SR: 1.78±1.22; BGC+SR: 2.03±1.20; p=0.73), while other histopathological markers were absent or minimal. Tissues downstream from targeted vessels also showed absence or minimal lesions across both groups.

CONCLUSION Results in a swine clot model support the high efficacy of the ANCD+SR without causing clinically significant vessel

injury potentially related to the new funnel component. ABSTRACT 5

Histological stroke clot analysis after thrombectomy: Technical aspects and recommendations.

Staessens S, Fitzgerald S, Andersson T, et al. International Journal of Stroke, 2019, DOI: 10.1177/1747493019884527

INTRODUCTION/BACKGROUND The recent advent of endovascular procedures has created the unique opportunity to collect and analyze thrombi removed from cerebral arteries, instigating a novel subfield in stroke research. Insights into thrombus characteristics and composition could play an important role in ongoing efforts to improve acute ischemic stroke therapy. An increasing number of centers are collecting stroke thrombi. This paper aims at providing guiding information on thrombus handling, procedures, and analysis in order to facilitate and standardize this emerging research field.

ABSTRACT 6

Endosaccular flow disruption: where are we now?

Bhogal P, Udani S, Andersson T, et al. Journal of NeuroInterventional Surgery, 2019, 11(10), 10241025

INTRODUCTION/BACKGROUND Endosaccular flow disruption is an innovative method of treating wide-necked complex aneurysms. Currently four types of devices have obtained the CE mark for use within Europe. These are the Woven EndoBridge device (WEB), the Luna Aneurysm Embolization System, the Medina Embolic Device (Medtronic), and the Contour Neurovascular System. The aim of this article is to provide an overview of these devices and to summarize the evidence in the literature pertaining to the treatment of intracranial aneurysms with them.

ABSTRACT 7

ANCD thrombectomy device: in vitro evaluation.

Sanchez S, Cortiñas I, Andersson T, et al. Journal of NeuroInterventional Surgery, 2020, 12(1), 77-81

INTRODUCTION/BACKGROUND Endovascular treatment of stroke, although highly effective, may fail to reach complete recanalization in around 20% of cases. The Advanced Thrombectomy System (ANCD) is a novel stroke thrombectomy device designed to reduce clot fragmentation and facilitate retrieval by inducing local flow arrest and allowing distal aspiration in combination with a stent retriever. We aimed to assess the preclinical efficacy of ANCD.

MATERIALS/METHODS Soft red blood cell (RBC)-rich (n=20/group) and sticky fi brin-rich (n=30/group) clots were used to create middle cerebral artery (MCA) occlusions in two vascular phantoms. Three different treatment strategies were tested: (1) balloon guide catheter + Solitaire (BGC+SR); (2) distal access catheter + SR (DAC+SR); and (3) ANCD+SR, until complete recanalization was achieved or to a maximum of three passes. The recanalization rate was determined after each pass.

RESULTS After one pass, ANCD+SR resulted in an increased recanalization rate (94%) for all clots together compared with BGC+SR (66%; p<0.01) or DAC+SR (80%; p=0.04). After the final pass the recanalization rate increased in all three groups but remained higher with ANCD+SR (100%) than with BGC+SR (74%; p<0.01) or DAC+SR (90%; p=0.02). The mean number of passes was lower with ANCD+SR (1.06) than with BGC+SR (1.46) or DAC+SR (1.25) (p=0.01). A logistic regression model adjusted for treatment arm, clot type, and model used showed that both RBC-rich clots (OR 8.1, 95% CI 1.6 to 13.5) and ANCD+SR (OR 3.9, 95% CI 1.01 to 15.8) were independent predictors of first-pass recanalization.

CONCLUSION In in vitro three-dimensional models replicating MCA-M1 occlusion, ANCD+SR showed significantly better recanalization rates in fewer passes than other commonly used combinations of devices.

ABSTRACT 8

Structural analysis of ischemic stroke thrombi: histological indications for therapy resistance.

Staessens S, Vanacker P, Francois O, Andersson T, et al. Haematologica, 2020, 105(2), 498-507

INTRODUCTION/BACKGROUND Ischemic stroke is caused by a thromboembolic occlusion of cerebral arteries. Treatment is focused on fast and effi cient removal of the occluding thrombus, either via intravenous thrombolysis or via endovascular thrombectomy. Recanalization, however, is not always successful and factors contributing to failure are not completely understood. Although the occluding thrombus is the primary target of acute treatment, little is known about its internal organization and composition. The aim of this study, therefore, was to better understand the internal organization of ischemic stroke thrombi on a molecular and cellular level. A total of 188 thrombi were collected from endovascularly treated ischemic stroke patients and analyzed histologically for fibrin, red blood cells (RBC), von Willebrand factor (vWF), platelets, leukocytes and DNA, using bright field and fluorescence microscopy. Our results show that stroke thrombi are composed of two main types of areas: RBC-rich areas and platelet-rich areas. RBC-rich areas have limited complexity as they consist of RBC that are entangled in a meshwork of thin fibrin. In contrast, platelet-rich areas are characterized by dense fibrin structures aligned with vWF and abundant amounts of leukocytes and DNA that accumulate around and in these platelet-rich areas. These findings are important to better understand why platelet-rich thrombi are resistant to thrombolysis and difficult to retrieve via thrombectomy, and can guide further improvements of acute ischemic stroke therapy.

ABSTRACT 9

The unexplained success of stentplasty vasospasm treatment : Insights using Mechanistic Mathematical Modeling.

Bhogal P, Pederzani G, Andersson T, et al. Clinical Neuroradiology, 2019, 29(4), 763-774

INTRODUCTION/BACKGROUND Cerebral vasospasm (CVS) following subarachnoid hemorrhage occurs in up to 70% of patients. Recently, stents have been used to successfully treat CVS. This implies that the force required to expand spastic vessels and resolve vasospasm is lower than previously thought.

OBJECTIVE We develop a mechanistic model of the spastic arterial wall to provide insight into CVS and predict the forces required to treat it.

MATERIALS/METHODS The arterial wall is modelled as a cylindrical membrane using a constrained mixture theory that accounts for the mechanical roles of elastin, collagen and vascular smooth muscle cells (VSMC). We model the pressure diameter curve prior to CVS and predict how it changes following CVS. We propose a stretch-based damage criterion for VSMC and evaluate if several commercially available stents are able to resolve vasospasm.

RESULTS The model predicts that dilatation of VSMCs beyond a threshold of mechanical failure is sufficient to resolve CVS without damage to the underlying extracellular matrix. Consistent with recent clinical observations, our model predicts that existing stents have the potential to provide sufficient outward force to successfully treat CVS and that success will be dependent on an appropriate match between stent and vessel.

CONCLUSION Mathematical models of CVS can provide insights into biological mechanisms and explore treatment approaches. Improved understanding of the underlying mechanistic processes governing CVS and its mechanical treatment may assist in the development of dedicated stents. ABSTRACT 10

Why does mechanical thrombectomy in large vessel occlusion sometimes fail? : A review of the literature.

Yeo LLL, Bhogal P, Andersson T, et al. Clinical Neuroradiology, 2019, 29(3), 401-414

INTRODUCTION/BACKGROUND Thrombectomy is a technique that has completely changed the management of acute stroke and current devices have shown that they can achieve upwards of 90% successful recanalization in selected cohorts. However, despite the effectiveness of these devices, there are a proportion of patients who still fail to achieve reperfusion of the affected vascular territory and an even larger portion of patients who have poor functional outcomes in spite of successful recanalization. There are no guidelines on how to treat these patients when such failures occur. In an effort to understand the underpinnings of how failed thrombectomy occurs, we extensively reviewed the current literature in clot properties, vascular access problems, stroke pathogenic mechanisms, embolic complications, failed procedures and pre-procedural imaging. A short summary of each of these contentious areas are provided and the current state of the art. Together these elements give a cohesive overview of the mechanisms of failed thrombectomy as well as the controversies facing the field. New techniques and devices can then be developed to minimize such factors during stroke thrombectomy.

ABSTRACT 11

Posterior communicating and anterior communicating arteries on pre-thrombectomy computed tomography scans are associated with good outcomes irrespective of leptomeningeal collateral status.

Yeo LLL, Andersson T, Holmberg Å, et al. Interventional Neuroradiology, 2019, 25(4), 364-370

INTRODUCTION/BACKGROUND Collateral blood flow is known to be an important factor that sustains the penumbra during acute stroke. We looked at both the leptomeningeal collateral circulation and the presence of anterior and posterior communicating arteries to determine the factors associated with good outcomes and mortality.

MATERIALS/METHODS We included all patients with acute ischaemic stroke in the anterior circulation, who underwent thrombectomy with

the same thrombectomy device from 2013 to 2016. We assessed the leptomeningeal circulation by the Tan, Miteff and Maas validated scoring systems on pre-treatment computed tomographic angiography scans and looked at collateral flow through anterior and posterior communicating arteries. The results were good functional outcomes at 3 months (modified Rankin scale 0-2) and mortality.

RESULTS A total of 147 consecutive acute stroke patients treated with the Embotrap device were included with a median National Institutes of Health stroke scale of 15 (range 2-26). On multivariate analysis only younger age (odds ratio (OR) 0.96/ year, 95% confidence interval (CI) 0.94-0.99, P = 0.026), lower National Institutes of Health stroke scale score (OR 0.87/point, 95% CI 0.80-0.93, P < 0.001), number of attempts (OR 0.80/attempt, 95% CI 0.65-0.99, P = 0.043) and the presence of a patent anterior communicating artery (OR 14.03, 95% CI 1.42-139.07, P = 0.024) were associated with good functional outcomes. The number of attempts (OR 1.66/attempt, 95% CI 1.21-2.29, P = 0.002) was significantly associated with mortality and the presence of a patent posterior communicating artery (OR 0.098, 95% CI 0.016-0.59, P = 0.011) was inversely associated with mortality.

CONCLUSION Our study shows that the presence of anterior and posterior communicating arteries is significantly associated with good functional outcomes and reduced mortality, respectively, independent of the leptomeningeal circulation status.

ABSTRACT 12

The aspirations of direct aspiration for thrombectomy in ischemic stroke: a critical analysis.

Andersson T, Wiesmann M, Nikoubashman O, et al. Journal of Stroke, 2019, 21(1), 2-9

INTRODUCTION/BACKGROUND The treatment of acute ischemic stroke by mechanical thrombectomy has been revolutionary, however most of the clinical trials were done with the use a stent retriever. At the same time, an alternative technique of thrombectomy through direct aspiration with a large bore distal access catheter at the face of the clot is rapidly gaining popularity. Nonetheless, the data supporting this new technique is not yet as mature as that available on stent retrievers. This review is a critical analysis of the evidence supporting the principle of direct aspiration thrombectomy and a discussion of its potential strengths and weaknesses in comparison to the available studies on stent retrievers. While this is by no means a conclusive review, it should serve as a yardstick of where the science is currently, and what are the next trials that are necessary.

ABSTRACT 13

Analysis of revascularisation in ischaemic stroke with EmboTrap (ARISE I study) and meta-analysis of thrombectomy.

Mattle HP, Scarrott C, Andersson T, et al. Interventional Neuroradiology, 2019, 25(3), 261-270

INTRODUCTION/BACKGROUND The goal of the analysis of revascularisation in ischaemic stroke with EmboTrap study (ARISE I) was to demonstrate the effectiveness of EmboTrap.

MATERIALS/METHODS ARISE I was an open label, single arm, multicentre, prospective study for the treatment of acute stroke due to large vessel occlusion. The primary outcome was revascularisation of the target vessel as measured by the modified thrombolysis in cerebrovascular infarction (mTICI) score of at least 2b following thrombectomy with EmboTrap. For comparison of the ARISE I results a meta-analysis of eight randomised controlled trials was performed.

RESULTS ARISE I enrolled 40 patients. Their baseline characteristics that are predictors of stroke outcome and procedure timings in ARISE I were similar to those reported in recent randomised controlled trials. The primary outcome, good revascularisation rates (mTICI 2b/3 scores) after three or fewer passes with EmboTrap were 75% (95% confidence interval (CI) 62-88%), which is the same as 74% found in randomised controlled trials (difference of 0.8%, P = 0.95). After additional EmboTrap passes or the use of another device mTICI 2b/3 scores rose to 85% (95% CI 74-96%), which was also similar to the randomised controlled trials (difference 11%, P = 0.38). The high revascularisation rates in ARISE I converted into 64% good clinical outcomes (modified Rankin scale ≤2) compared to 50% in randomised controlled trials (difference 14%; 95% CI -13.7-41.7%; P = 0.32).

CONCLUSION ARISE I demonstrates that thrombectomy using the EmboTrap stent retriever yields similar results to devices that were used in recent randomised controlled trials for the treatment of stroke due to large vessel occlusions.

ABSTRACT 14

Very late leptomeningeal collaterals-potential new way to subdivide modified thrombolysis in cerebral ischemia (mTICI) 2B.

Yeo LLL, Cervo A, Andersson T, et al. Clinical Neuroradiology, 2020, 30(1), 77-83

INTRODUCTION/BACKGROUND Studies have shown that the modified thrombolysis in cerebral ischemia (mTICI) 2B score is associated with better functional outcome; however, 50-99% reperfusion is a large range and there may be factors which can differentiate this further. The effects of very late leptomeningeal collaterals (VLLC) on mTICI-2B patients were studied.

MATERIALS/METHODS A prospectively collected registry of anterior circulation AIS patients treated with the EmboTrap revascularization device from 2013 to 2016 was evaluated. Imaging parameters and timings, including the mTICI score were verified by an external core laboratory blinded to the clinical data. The final angiogram was examined for the appearance of VLLC in predicting 3-month outcomes including excellent functional outcomes, defined as modified Rankin scale (mRS) 0-1, bleeding risk and mortality.

RESULTS A total of 177 consecutive anterior circulation stroke patients were included in the analysis. Of these 94 (53.1%) achieved only mTICI-2B reperfusion, 16/94 (17.0%) patients achieved excellent functional outcomes at 3 months and 26 (27.7%) had hyperdensity on follow-up computed tomography (CT). On univariate analysis, the presence of VLLC was inversely associated with excellent functional outcomes at 3 months and positively associated with mortality in patients with mTICI-2B reperfusion. On multivariate analysis VLLC was inversely associated with excellent outcomes (odds ratio 0.075, 95% confidence interval 0.007-0.765, P = 0.029) but not associated with mortality.

CONCLUSION The mTICI-2B grade may be further refined by secondary radiological markers. The VLLC sign is associated with the loss of excellent functional outcomes at 3 months. It is a simple sign to discriminate mTICI-2B into different grades but should be verified in larger populations from other centers. ABSTRACT 15

Posterior circulation occlusions may be associated with distal emboli during thrombectomy : factors for distal embolization and a review of the literature.

Yeo LLL, Holmberg A, Andersson T, et al. Clinical Neuroradiology, 2019, 29(3), 425-433

INTRODUCTION/BACKGROUND Distal embolization or movement of the thrombus to previously uninvolved vasculature are feared complications during stroke thrombectomy. We looked at associated factors in a consecutive series of patients who underwent thrombectomy with the same endovascular device.

MATERIALS/METHODS We included all patients with acute ischemic stroke in the anterior or posterior circulation, who underwent thrombectomy with the same thrombectomy device for acute stroke from 2013 to 2016. Distal embolization was defined as any movement of the thrombus into a previously uninvolved portion of the cerebral vasculature or the presence of thrombotic material further downstream in the affected vessel, which occurred after the initial angiogram. We studied patient-related as well as technical factors to determine their association with distal emboli.

RESULTS In this study 167 consecutive acute stroke patients treated with the emboTrap® device (Cerenovus, Irvine, CA, USA) were included with a median National Institutes of Health Stroke Scale (NIHSS) of 15 (range 2-30) and mean age of 67 years (SD 13.1 years). Of the patients in our cohort 20 (11.9%) experienced distal emboli, with 2.3% into a new territory and 9.6% into a territory distal to the primary occlusion. On univariate analysis, age, intravenous tissue plasminogen activator (tPA), posterior circulation occlusions, and general anesthesia were associated with distal emboli. On multivariate analysis, only posterior circulation occlusions (odds ratio OR 4.506 95% confidence interval CI 1.483-13.692, p = 0.008) were significantly associated with distal emboli. Distal embolization was not significantly associated with worse functional outcomes at 3 months, increased mortality or increased bleeding risk.

CONCLUSION Posterior circulation occlusions were significantly associated with distal emboli during thrombectomy, possibly due to the lack of flow arrest during such procedures. New techniques and devices should be developed to protect against embolic complications during posterior circulation stroke

thrombectomy.

ABSTRACT 16

The effective and collective dose to patients undergoing abdominopelvic and T trunk computed tomography examinations: A Belgian multicentre study.

Verstraeten K, De Roo B, et al. European Journal of Radiology, 2019, 111, 81-87

OBJECTIVE This study aims to evaluate the radiation exposure to patients undergoing an abdominopelvic or a chest and abdominopelvic (trunk) CT examination and to assess compliance to imaging referral guidelines.

MATERIALS/METHODS To this end, 357 standard abdominopelvic and trunk CT scans were collected from 8 Belgian institutions in 2011 and 2015. Effective dose (E) and collective dose were calculated using CT dose descriptors (CTDIvol and DLP), which were obtained from dose reports generated by the CT scanner. Subsequently, these CT requests were compared against the national referral guidelines to assess compliance. Population estimates for dose and compliance were obtained using multilevel linear regression and generalized estimating equation models.

RESULTS Between 2011 and 2015, a significant decrease of 28% in CTDIvol and DLP was found for abdominopelvic CT. The corresponding E decreased by 27%, and the collective dose by 23%. For trunk CT, a non-significant decrease of 6% was found in CTDIvol and a significant decrease of 14% in both DLP and E. However, the collective dose of trunk examinations increased by 39%. In 2011, 24% of the abdominopelvic examinations were not compliant with the guidelines, whereas this percentage dropped to 17% in 2015. Non-justified examinations accounted for 8% and 12% of all trunk CT scans in 2011 and 2015, respectively.

CONCLUSION Between 2011 and 2015, there was a decrease in dose for patients undergoing abdominopelvic or trunk CT in Belgium. However, a fraction of the estimated doses are linked to unnecessary CT examinations, which should be avoided. ABSTRACT 17

Surprising bone and soft tissue lesions of the chest: pictorial review.

Degrieck B, Bazzocchi MD, Verstraete K, et al. Seminars in Musculoskeletal radiology, 2019, 23, 85-96

CONCLUSION Although plain radiographs of the chest are usually requested to evaluate the heart, lung, and mediastinum, many bone and soft tissue, metabolic, and congenital lesions can be visible presenting as surprising lesions. Thorough analysis of the lesion characteristics on the chest radiograph, eventually in conjunction with more advanced imaging techniques and in combination with the clinical findings, will lead to the correct diagnosis.

ABSTRACT 18

Magnetic resonance imaging of third molars in forensic age estimation : comparison of the Ghent and Graz protocols focusing on apical closure.

De Tobel J, Parmentier G, Verstraete K, et al. International Journal of Legal Medicine., 2019, 133(2), 583592

OBJECTIVE To compare the Ghent and Graz magnetic resonance imaging (MRI) protocols for third molars, focusing on the assessment of apical closure. To study the influence of (1) voxel size and (2) head fixation using a bite bar. To compare both protocols with a ground truth of apical development.

MATERIALS/METHODS In eleven healthy volunteers 3T MRI was conducted, including four Ghent sequences and two Graz sequences, with and without bite bar. After removal, 39 third molars were scanned with 7T µMRI and µCT to establish the ground truth of apical development. Three observers in consensus evaluated assessability and allocated developmental stages.

RESULTS The Ghent T2 FSE sequence (0.33 x 0.33 x 2 mm³) was more assessable than the Graz T1 3D FSE sequence (0.59 x 0.59 x 1 mm³). Comparing assessability in both sequences with bite bar rendered P = 0.02, whereas comparing those without bite bar rendered P < 0.001. Within the same sequence, the bite bar increased assessability, with P = 0.03 for the Ghent T2 FSE and P = 0.07 for the Graz T1 3D FSE. Consid-

ering µCT as ground truth for staging, allocated stages on MRI were most frequently equal or higher. Among in vivo protocols, the allocated stages did not differ significantly.

CONCLUSION Imaging modality-specific and MRI sequence-specific reference data are needed in age estimation. A higher in plane resolution and a bite bar increase assessability of apical closure, whereas they do not affect stage allocation of assessable apices.

PRESENTATIES / CONGRESSEN

ABSTRACT 1

Cone-beam CT as a fast and promising technique to assess the microstructure of distal radii in clinical practice.

25th Congress of the European Society of Biomechanics Mys K, Stockmans F, Vanovermeire O, et al. June 2019, Vienna, Austria

Er is geen abstract beschikbaar.

ABSTRACT 2

A differential diagnosis pathway to guide genetic testing for SHH mutation.

European Society of Radioloogy Xu J, Vanovermeire O, Seynaeve P, et al. March 2020, Electronic Presentation Online System (EPOS)

CONCLUSION MR imaging can play a key role in the differential diagnosis of probable gene-induced malformations, especially when combined supratentorial and posterior fossa lesions are very complex. The imaging features may provide a clue for genetic testing. The supratentorial ventricular abnormalities and midline defects are suggestive for HPE. It is however mandatory in these patients to carefully examine the posterior fossa and check for the presence of cystic malformations. Hypoplasia with rotation and displacement of the vermis, size of and communication with the 4th ventricle, size of the posterior fossa and the presence of associated hydrocephalus allow to differentiate DWM and DWV from PBC and MCM. Further studies will be needed to decipher the significance of SHH and to characterize its function in DWC and HPE.

ABSTRACT 3

Endovascular treatment in stroke: Tools of the trade yesterday, today and tomorrow.

9th Annual Conference of the Neurological Society of India

Andersson T

February 2020, Kolkata, India

INTRODUCTION/BACKGROUND Endovascular treatment of ischemic stroke started with intra-arterial thrombolysis and anecdotal cases treated with snares and balloons. The first successful intra-arterial fibrinolysis for an intracranial artery occlusion was performed in 1979 by Zeumer.

RESULTS This new concept made the treatment easier, safer and more efficient. After this, several similar stent retrievers have been developed and approved but today also new ideas and concepts for EVT in AIS are being developed and tested as well as new pharmaceutical compounds for neuroprotection. Device development remains an interesting market ever since stent retriever thrombectomy for large vessel occlusion in combination with IVT was proven superior to stand-alone IVT in six randomized control studies up t 6-8 hours after onset. More recently this time window was extended for selected patients up to 16 and 24 hours after onset, respectively, increasing the potential number of patients even more.

CONCLUSION At present, mechanical thrombectomy for AIS can technically be done with direct contact aspiration or stent retriever. As the clinical as well as economic importance of a successful retrieval in only one attempt (so called “first pass effect”; FPE) has been clearly shown, a combination of retrievers and aspiration in combination with adjunctive tools like Balloon Guide Catheters (BGC) has been proven to further augment the chance of FPE. New retrievers based on yet other concepts are being developed and tested today. For instance, devices with small filaments actively deployed from a wire-like structure, or devices applying local flow-arrest just proximal to the thrombus before catchment. The last word remains to be said…

ABSTRACT 4

Flow diversion for intracranial aneurysms: the final solution?

9th Annual Conference of the Neurological Society of India

Andersson T

February 2020, Kolkata, India

CONCLUSION Ever since the introduction of the Pipeline flow-diverter (FD), the concept has gained increased popularity. This may not come as a big surprise as the technique can be seen as quite “seductive”. Today there are many FDs on the market, all with slight differences in the basic construction providing them with different features, for instance regarding mesh density, radial force and re-sheath ability. So-called surface modification has lately gained increased interest as this may potentially reduce the need for aggressive anti-aggregation, something that is a clear drawback not least in the treatment of ruptured aneurysms. Even though FDs were originally mainly developed to treat large and giant aneurysms, there has been a shift in FD indications, today often including also easy to coil or clip aneurysms. The risk with an “overuse” of FDs is highlighted in several recent meta-analyses in which the morbidity was around 20-25% whereas the mortality was found to be around 10-15%, reaching as high as 20% for posterior location, especially for fusiform aneurysms. In addition, there are well recognized problems with delayed rupture of the index aneurysm as well as appearance of delayed remote intracranial hemorrhages. One trial, randomizing patients to FD versus standard management, was halted due to safety concerns when an interim analysis revealed that 16% of the patients in the FD-arm were dead or dependent at 3 months and that 42% had not reached angiographic occlusion. Based on this, one may argue for a stricter use of FDs, limited to situations where no other good treatment option is available. This is mostly applicable to giant- as well as so called blood-blister aneurysms, sometimes closely located multiple aneurysms or for retreatment after clip or coil. But only exceptionally for fusiform and wide-necked aneurysms and basically never for those that have ruptured resulting in a subarachnoid hemorrhage. To conclude, FDs are great tools but should be used with care and on strict indications as the complication rate is high and the long-term effects unknown. ABSTRACT 5

Economic impact of First Pass Effect (FPE) in endovascular stroke treatment with the EMBOTRAP II device from the ARISE II study – Annual healthcare resource use economic analysis from a European perspective.

World Federation of Interventional and Therapeutic Neuroradiology (WFITN) 15th Annual Meeting

Andersson T

October 2019, Napels, Italië

INTRODUCTION/BACKGROUND First pass effect (FPE) is the ability of a thrombectomy device and the applied technique to achieve complete or near complete revascularization (modified Thrombolysis in Cerebral Ischemia [mTICI] ≥2c) in a single pass. FPE has been shown to be an independent predictor of good functional outcome (modified Rankin Scale [mRS] ≤2), which subsequently impacts healthcare costs. A post hoc analysis of ARISE-II data showed that FPE was associated with reduced costs for annual care based on 90-day mRS.

OBJECTIVE The purpose of this analysis was to assess the annual economic impact of achieving FPE in four European countries (France, Italy, Sweden, and United Kingdom [UK]).

MATERIALS/METHODS Clinical outcomes data were obtained from the ARISE-II study investigating the safety and efficacy of the EMBOTRAP II device (n=227). Patients who did not achieve mTICI≥2c were excluded. The proportions of patients achieving each mRS score at 90 days were assessed, stratified by FPE status. Costs for annual care after 90-days, based on the 90-day mRS and in 2018 country-specific currencies, were calculated and compared between patients that did or did not achieve FPE; incremental differences were calculated.

RESULTS In ARISE-II, 76% of patients (n=172) achieved mTICI ≥2c; among these patients, 53% achieved FPE. A significantly higher percentage of patients that achieved FPE had good functional outcomes vs. those that did not achieve FPE (80.5% vs. 61.0%, p=0.006) with lower estimated costs for annual care after 90-days, leading to per-patient cost-savings across all countries (€2,140 for France, €694 for Italy, SEK 12,777 for Sweden, and £2,041 for UK) (Table 1). In the absence of healthcare resource use and cost data reported

in ARISE-II, healthcare resource use after 90-days and subsequently, costs for healthcare resource use were obtained from the literature, which may not be generalizable across settings and is a limitation of this analysis. Additionally, the literature used to obtain the costs for annual care after 90days, based on 90-day mRS, did not report costs for death (i.e. mRS 6), which had a lower incidence among patients who achieved FPE (5.75% vs. 14.29%).

CONCLUSION Among patients with complete or near complete revascularization (mTICI≥2c), patients benefiting from FPE may be associated with annual cost-savings across European countries (France, Italy, Sweden, and UK) due to improved functional outcomes.

ABSTRACT 6

Cervical mediastinoscopy: Always Safe?

European Society of Thoracic Surgeons (ESTS) Dublin 2019 Clement C, Janssen M, Vanacker P, François O, Missant C, Lerut P, et al. Juni 2019, Dublin, Ierland

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