Mudassar Kamran

Early experience in the treatment of intra-cranial aneurysms by endovascular flow diversion: a multicentre prospective study.

Introduction Flow diversion is a new approach to the endovascular treatment of intracranial aneurysms which uses a high density mesh stent to induce sac thrombosis. These devices have been designed for the treatment of complex shaped and large size aneurysms. So far published safety and efficacy data on this approach is sparse. Material and Methods Over 8 months, standardized clinical and angiographic data were collected on 70 patients treated with a flow diverter device (SILK flow diverter (SFD)) in 18 centres worldwide. Treatment and early follow up details were audited centrally. SFDs were deployed alone in 57 (81%) or with endosaccular coils in 10 (14%) aneurysms, which included: 44 (63%) saccular, 26 (37%) fusiform shapes and 18 (26%) small, 37 (53%) large, 15 (21%) giant sizes. Treatment outcome data up to 30 days were reported for all patients, with clinical (50 patients) and imaging (49 patients) follow up (median 119 days) data available. Results Difficulties in SFD deployment were reported in 15 (21%) and parent artery thrombosis in 8 (11%) procedures. Procedural complications caused stroke in 1 and serious extracranial bleeding in 3 patients; 2 of whom developed fatal pneumonias. Delayed worsening of symptoms occurred in 5 patients (3 transient, 1 permanent neurological deficit, and 1 death) and fatal aneurysm bleeding in 1 patient. Overall permanent morbidity rates were 2 (4%) and mortality 4 (8%). Statistical analysis revealed no significant association between complications and variables related to treated aneurysm morphology or rupture status. Conclusion This series is the largest reporting outcome of the new treatment approach and provides data for future study design. Procedural difficulties in SFD deployment were frequent and anti-thrombosis prophylaxis appears to reduce the resulting clinical sequelae, but at the cost of morbidity due to extracranial bleeding. Delayed morbidity appears to be a consequence of the new approach and warrants care in selecting patients for treatment and future larger studies.

Assessment of angiographic outcomes after flow diversion treatment of intracranial aneurysms: a new grading schema

IntroductionFlow diverter (FD) devices have emerged as an alternative treatment for a subgroup of intracranial aneurysms. The principle of endovascular flow diversion is inherently different from endosaccular coil embolisation. To monitor the angiographic outcomes for FDs, a sensitive and reliable new measure is required. Oxford Neurovascular and Neuroradiology Research Unit developed a grading schema while conducting a registry to audit outcomes of patients treated using a particular FD (SILK flow diverter; Balt Extrusion, Montmorency, France). The aim of this study is to assess the applicability and reproducibility of the new schema.MethodsThe proposed grading schema is designed for saccular- or fusiform-shaped aneurysms. For both, it documents the degree of aneurysm occlusion using a five-point scale and the parent artery patency on a three-point scale. Two neuroradiologists used the schema to independently rate 55 angiograms showing comparable treatment and follow-up angiograms of patients treated with a FD. Inter-observer agreement was estimated using the weighted kappa co-efficient.ResultsBoth readers found the schema easy to apply. Overall, there were ten discordant readings for degrees of aneurysm occlusion and two for parent artery patency. Inter-observer agreement was excellent for both the assessment of aneurysm occlusion (k=0.89; C.I.=0.81–0.99) and parent artery patency (k=0.90; C.I.=0.76–1.0).ConclusionThe proposed schema is sufficiently sensitive to register gradual aneurysm occlusion and parent artery patency on interval angiograms. It is reproducible and is applicable to both saccular and fusiform aneurysms. More data on follow-up of FD-treated aneurysms is needed to prove its efficacy in predicting the long-term behaviour of treated aneurysms.

C-arm flat detector computed tomography: the technique and its applications in interventional neuro-radiology

IntroductionFlat detector computed tomography (FDCT) is an imaging tool that generates three-dimensional (3-D) volumes from data obtained during C-arm rotation using CT-like reconstruction algorithms. The technique is relatively new and, at current levels of performance, lags behind conventional CT in terms of image quality. However, the advantage of its availability in the interventional room has prompted neuro-radiologists to identify clinical settings where its role is uniquely beneficial.MethodsWe performed a search of the online literature databases to identify studies reporting experience with FDCT in interventional neuro-radiology. The studies were systematically reviewed and their findings grouped according to specific clinical situation addressed.ResultsFDCT images allow detection of procedural complications, evaluation of low-radiopacity stents and assessment of endosaccular coil packing in intra-cranial aneurysms. Additional roles are 3-D angiography that provides an accurate depiction of vessel morphology with low concentrations of radiographic contrast media and a potential for perfusion imaging due to its dynamic scanning capability. A single scan combining soft tissue and angiographic examinations reduces radiation dose and examination time. Ongoing developments in flat detector technology and reconstruction algorithms are expected to further enhance its performance and increase this range of applications.ConclusionFDCT images provide useful information in neuro-interventional setting. If current research confirms its potential for assessing cerebral haemodynamics by perfusion scanning, the combination would redefine it as an invaluable tool for interventional neuro-radiology procedures. This facility and its existing capabilities of parenchymal and angiographic imaging would also extend its use to the triage of acute stroke patients.

Simple Measurement of Aneurysm Residual after Treatment: the SMART scale for evaluation of intracranial aneurysms treated with flow diverters

BackgroundPrimary endovascular reconstruction with flow diversion represents a fundamental paradigm shift in the technique of endovascular aneurysm treatment. Unlike coil embolization, often there remains residual post-procedural filling within the aneurysm with flow diverters, the curative reconstruction presumably occurring over a period of weeks. Thus, conventional grading scales for post-procedural aneurysm occlusion and recanalization are inadequate. The aim of this paper is to propose a new angiographic grading scale that addresses this fundamentally new treatment option.MethodA five-point grading scale describes the location of residual flow within the aneurysm in the venous phase [grade 1: patent aneurysm with diffuse inflow; grade 2: residual filling of the aneurysm dome (saccular) or wall (fusiform); grade 3: only residual neck (saccular) or only intra-aneurysmal filling with former boundaries covered (fusiform); grade 4: complete occlusion].FindingsGrade 0 represents any aneurysm, regardless of occlusion rate with early phase, coherent inflow jet. Intra-aneurysmal flow stagnation is categorized into: (a) none, (b) capillary phase, and (c) venous phase. Prevailing parent vessel hemodynamics with in-stent stenosis (ISS) are divided into none (ISS0), mild (ISS1), moderate (ISS2), severe (ISS3), and total (ISS4) occlusion. The proposed grading scales allow assessment of the hemodynamic consequences of stent placement on endosaccular in-flow, stasis, and location of stasis as well as parent vessel hemodynamics.ConclusionsFurther studies need to show the applicability and possible predictive value of this new grading scale on the efficacy of the stent in promoting intra-aneurysmal flow stagnation, thus creating the potential to harmonize the results of future papers. This may help to optimize treatment and future device design.

C-Arm Flat Detector CT Parenchymal Blood Volume Thresholds for Identification of Infarcted Parenchyma in the Neurointerventional Suite

BACKGROUND AND PURPOSE: C-arm flat detector CT parenchymal blood volume imaging allows functional assessment of the brain parenchyma in the neurointerventional suite. This study aimed to determine the optimal C-arm flat detector CT parenchymal blood volume thresholds for demarcating irreversibly infarcted brain parenchyma by using areas of restricted diffusion on MR imaging as a surrogate marker for infarction. MATERIALS AND METHODS: Twenty-six patients with delayed cerebral ischemia following aneurysmal SAH underwent research C-arm CT parenchymal blood volume scans by using a biplane angiography system and contemporaneous MR imaging. Infarct and peri-infarct tissue VOIs and their homologous VOIs in the contralateral uninvolved hemisphere were delineated on the basis of the review of DWI, PWI, and ADC images. Voxel-based receiver operating characteristic curve analysis was performed to estimate the optimal absolute and normalized parenchymal blood volume values for demarcating the infarct voxels. RESULTS: For 12 patients with areas of restricted diffusion (infarct volume, 6.38 ± 7.09 mL; peri-infarct tissue volume, 22.89 ± 21.76 mL) based on the voxel-based receiver operating characteristic curve analysis, optimal absolute and normalized parenchymal blood volume thresholds for infarction were 2.49 mL/100 g (area under curve, 0.76; sensitivity, 0.69; specificity, 0.71) and 0.67 (area under curve, 0.77; sensitivity, 0.69; specificity, 0.72), respectively (P value < .01). For the moderate-to-severely ischemic peri-infarct zone, mean parenchymal blood volume values of the involved hemisphere VOIs were lower compared with the uninvolved hemisphere VOIs (P value < .01). However, for the mild-to-moderately ischemic peri-infarct zone, there was no statistically significant difference between the mean parenchymal blood volume values of the involved and uninvolved hemisphere VOIs (P value > .05). CONCLUSIONS: C-arm flat detector CT parenchymal blood volume maps in conjunction with optimal thresholds are sensitive and specific for the estimation of irreversibly infarcted parenchyma. Parenchymal blood volume maps allow reliable detection of moderate-to-severe ischemia; however, the potential for underestimation of mild-to-moderate ischemia exists.

Ischemic stroke in children: new aspects of treatment.

From the NIHROxford Biomedical Research Centre (I.G.) and Nuffield Department of Surgery (M.K.), University of Oxford, Oxford, United Kingdom; Department of Neurology, Saarland University, Homburg, Germany (S.W., K.F.); Department of arly treatment of stroke in children and infants is essential, but success is not supported by data. Recent studies have demonstrated a mortality rate of up to 3%-11% and persistent neurologic deficit in 68%-74% of affected children. The epidemiology of thrombembolism is vastly different in pediatric patients and adults. In children, the most common underlying conditions are sickle cell disease and heart disease. Other risk factors include head trauma, infections, anemia, leukocytosis, and prothrombotic disorders. Transient cerebral arteriopathy due to unilateral intracranial arterial wall disease is another frequent cause of childhood acute ischemic stroke (AIS), specifically in previously healthy children. Here the focus should be on a rigorous assessment of anti-inflammatory treatment. The treatment of AIS is evolving at a quick pace, and acute mechanical interventions to restore cerebral blood flow are now a reality in the management of acute stroke. We reviewed the available literature and identified 7 published reports on mechanical recanalization in acute stroke in children. Here we review the currently available evidence on acute arterial AIS and highlight recent advances and possible future advances in the use of mechanical devices to treat stroke in this vulnerable population. We identified references for this review through searches of PubMed from 1980 to 2010 with the terms ‘‘acute,’’ ‘‘stroke,’’ ‘‘stroke treatment,’’ ‘‘children,’’ ‘‘childhood,’’ ‘‘child,’’ ‘‘artery occlusion,’’ ‘‘pediatric,’’ ‘‘girl,’’ ‘‘boy,’’ ‘‘endovascular,’’ ‘‘pediatrics,’’ ‘‘mechanical recanalization,’’ and ‘‘stroke trials.’’ We also identified articles through searches of the authors’ personal files. Only articles published in English were reviewed. For ethical reasons, previous and ongoing stroke trials have conventionally excluded children. Thus, current treatment methodologies do not include a uniform treatment approach for the pharmacologic and interventional management of AIS in the pediatric population. Guidelines are scarce, do not involve mechanical recanalization, and are mainly those set forth by the American College of Chest Physicians and the Royal College of Physicians. These guidelines do not provide sufficient recommendations for the acute management of ischemic stroke, and are based mainly on consensus and expert opinion.

Non-invasive assessment of vasospasm following aneurysmal SAH using C-arm FDCT parenchymal blood volume measurement in the neuro-interventional suite: Technical feasibility.

Introduction Cerebral vasospasm is the leading cause of morbidity and mortality in patients with aneurysmal subarachnoid haemorrhage (SAH) surviving the initial ictus. Commonly used techniques for vasospasm assessment are digital subtraction angiography and transcranial Doppler sonography. These techniques can reliably identify only the major vessel spasm and fail to estimate its haemodynamic significance. To overcome these issues and to enable comprehensive non-invasive assessment of vasospasm inside the interventional suite, a novel protocol involving measurement of parenchymal blood volume (PBV) using C-arm flat detector computed tomography (FDCT) was implemented. Materials and methods Patients from the neuro-intensive treatment unit (ITU) with suspected vasospasm following aneurysmal SAH were scanned with a biplane C-arm angiography system using an intravenous contrast injection protocol. The PBV maps were generated using prototype software. Contemporaneous clinically indicated MR scan including the diffusion- and perfusion-weighted sequences was performed. C-arm PBV maps were compared against the MR perfusion maps. Results Distribution of haemodynamic impairment on C-arm PBV maps closely matched the pattern of abnormality on MR perfusion maps. On visual comparison between the two techniques, the extent of abnormality indicated PBV to be both cerebral blood flow and cerebral blood volume weighted. Conclusion C-arm FDCT PBV measurements allow an objective assessment of the severity and localisation of cerebral hypoperfusion resulting from vasospasm. The technique has proved feasible and useful in very sick patients after aneurysmal SAH. The promise shown in this early study indicates that it deserves further evaluation both for post-SAH vasospasm and in other relevant clinical settings.

Time density curve analysis for C-arm FDCT PBV imaging

Introduction Parenchymal blood volume (PBV) estimation using C-arm flat detector computed tomography (FDCT) assumes a steady-state contrast concentration in cerebral vasculature for the scan duration. Using time density curve (TDC) analysis, we explored if the steady-state assumption is met for C-arm CT PBV scans, and how consistent the contrast-material dynamics in cerebral vasculature are across patients. Methods Thirty C-arm FDCT datasets of 26 patients with aneurysmal-SAH, acquired as part of a prospective study comparing C-arm CT PBV with MR-PWI, were analysed. TDCs were extracted from the 2D rotational projections. Goodness-of-fit of TDCs to a steady-state horizontal-line-model and the statistical similarity among the individual TDCs were tested. Influence of the differences in TDC characteristics on the agreement of resulting PBV measurements with MR-CBV was calculated. Results Despite identical scan parameters and contrast-injection-protocol, the individual TDCs were statistically non-identical (p < 0.01). Using Dunns multiple comparisons test, of the total 435 individual comparisons among the 30 TDCs, 330 comparisons (62%) reached statistical significance for difference. All TDCs deviated significantly (p < 0.01) from the steady-state horizontal-line-model. PBV values of those datasets for which the TDCs showed largest deviations from the steady-state model demonstrated poor agreement and correlation with MR-CBV, compared with the PBV values of those datasets for which the TDCs were closer to steady-state. Conclusion For clinical C-arm CT PBV examinations, the administered contrast material does not reach the assumed ‘ideal steady-state’ for the duration of scan. Using a prolonged injection protocol, the degree to which the TDCs approximate the ideal steady-state influences the agreement of resulting PBV measurements with MR-CBV.

Whole brain C-arm computed tomography parenchymal blood volume measurements.

Introduction C-arm flat detector computed tomography (FDCT) parenchymal blood volume (PBV) imaging in the neuro-interventional suite is a new technique for which detailed whole brain measurements have not been previously reported. This study aims to create a catalogue of PBV measurements for various anatomical regions encompassing the whole brain, using a three-dimensional volume-of-interest (3D-VOI) analysis. Methods We acquired and analysed 30 C-arm FDCT datasets from 26 patients with aneurysmal subarachnoid haemorrhage (SAH), as part of a prospective study comparing C-arm computed tomography (CT) PBV with magnetic resonance perfusion-weighted imaging (MR-PWI). We calculated the PBV values for various brain regions with an automated analysis, using 58 pre-defined atlas-based 3D-VOIs encompassing the whole brain. VOIs partially or completely overlapping regions of magnetic resonance diffusion weighted imaging (MR-DWI) abnormality or magnetic resonance cerebral blood flow (MR-CBF) asymmetry were excluded from the analysis. Results Of the 30 C-arm CT PBV datasets, 14 (54%; 12 patients) had areas of restricted diffusion, the majority of which were focal. The PBV values for the cerebral cortex and cerebral white matter were 4.01 ± 0.47 (mean ± SD) and 3.01 ± 0.39 ml per 100 ml. Lobar PBV values were: frontal lobe 4.2 ± 0.8, temporal lobe 4.2 ± 0.9, parietal lobe 3.9 ± 0.7 and occipital lobe 4.3 ± 0.8 ml/100 ml. The basal ganglia and brainstem PBV values were 3.4 ± 0.7 and 4.6 ± 0.6 ml/100 ml, respectively. Conclusions Compared with the typical reference cerebral blood volume (CBV) values reported in the literature for Positron Emission Tomography (PET), the PBV values were relatively high for the white matter and relatively low for the cortical grey matter. The reported catalogue of PBV values for various brain regions would be useful to inform future studies and could be used in clinical practice, when interpreting PBV maps.

An approach to the symbolic representation of brain arteriovenous malformations for management and treatment planning

IntroductionThere is currently no standardised approach to arteriovenous malformation (AVM) reporting. Existing AVM classification systems focuses on angioarchitectural features and omit haemodynamic, anatomical and topological parameters intuitively used by therapists.MethodsWe introduce a symbolic vocabulary to represent the state of an AVM of the brain at different stages of treatment. The vocabulary encompasses the main anatomic and haemodynamic features of interest in treatment planning and provides shorthand symbols to represent the interventions themselves in a schematic representation.ResultsThe method was presented to 50 neuroradiologists from14 countries during a workshop and graded 7.34 ± 1.92 out of ten for its usefulness as means of standardising and facilitating communication between clinicians and allowing comparisons between AVM cases. Feedback from the survey was used to revise the method and improve its completeness. For an AVM test case, participants were asked to produce a conventional written report and subsequently a diagrammatic report. The two required, on average, 6.19 ± 2.05 and 5.09 ± 3.01 min, respectively. Eighteen participants said that producing the diagram changed the way they thought about the AVM test case.ConclusionIntroduced into routine practice, the diagrams would represent a step towards a standardised approach to AVM reporting with consequent benefits for comparative analysis and communication as well as for identifying best treatment strategies.