Publications by authors named "Olav Jansen"

195 Publications

Metallic Implants in MRI - Hazards and Imaging Artifacts.

Rofo 2021 May 12. Epub 2021 May 12.

Department for Radiology and Neuroradiology, Molecular Imaging North Competence Center (MOIN CC), Section Biomedical Imaging, University Hospital Schleswig-Holstein - Campus Kiel, Kiel University, Germany.

Background:  Magnetic resonance imaging (MRI) is an examination method for noninvasive soft tissue imaging without the use of ionizing radiation. Metallic implants, however, may pose a risk for the patient and often result in imaging artifacts. Due to the increasing number of implants, reducing these artifacts has become an important goal. In this review, we describe the risks associated with implants and provide the background on how metal-induced artifacts are formed. We review the literature on methods on how to reduce artifacts and summarize our findings.

Method:  The literature was searched using PubMed and the keywords "MRI metal artifact reduction", "metallic implants" and "MRI artefacts/artifacts".

Results And Conclusion:  The MRI compatibility of implants has to be evaluated individually. To reduce artifacts, two general approaches were found: a) parameter optimization in standard sequences (echo time, slice thickness, bandwidth) and b) specialized sequences, such as VAT, OMAR, WARP, SEMAC and MAVRIC. These methods reduced artifacts and improved image quality, albeit at the cost of a (sometimes significantly) prolonged scan time. New developments in accelerated imaging will likely shorten the scan time of these methods significantly, such that routine use may become feasible.

Key Points:   · Metallic implants may pose a risk for patients and often cause artifacts.. · Imaging artifacts can be reduced by parameter optimization or special sequences.. · Metal artifacts are reduced with a lower TE, smaller voxel size, larger matrix, and higher bandwidth.. · SPI, STIR, VAT, SEMAC, MAVRIC, and MAVRIC-SL are specialized MR sequences that can reduce artifacts further..

Citation Format: · Peschke E, Ulloa P, Jansen O et al. Metallic Implants in MRI - Hazards and Imaging Artifacts. Fortschr Röntgenstr 2021; DOI: 10.1055/a-1460-8566.
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http://dx.doi.org/10.1055/a-1460-8566DOI Listing
May 2021

MRI-findings in idiopathic intracranial hypertension (Pseudotumor cerebri).

Rofo 2021 May 12. Epub 2021 May 12.

Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein - Campus Kiel, Germany.

Background:  Pseudotumor cerebri, also known as idiopathic intracranial hypertension, is a disorder of increased intracranial pressure of unknown etiology. Main symptom is headache which has a characteristic similar to other headache diseases, therefore the idiopathic intracranial hypertension often remains undetected. The incidence is 1/100 000 with the number of unreported cases being much higher. This article highlights the essential role of MRI in the differential diagnosis.

Methods:  A literature search was carried out on idiopathic intracranial hypertension and Pseudotumor cerebri in English and German. Original and Review articles as well as case reports were taken into account. Since the main focus of the article is MRI diagnostics, some images were selected to illustrate the characteristic MRI morphological features.

Results And Conclusion:  The diagnosis of idiopathic intracranial hypertension is based on an exclusion procedure. Most common syndromes are headache, transient visual obscurations, pulsatile tinnitus and nausea. In the presence of an underlying cause for the increased intracranial pressure one speaks of a secondary intracranial hypertension. The diagnostics include a detailed medical history, neurological and ophthalmic examination, lumbar puncture, and neuroradiological imaging procedures. MRI, in particular, has become increasingly important in recent years, since signs for changes in cerebrospinal fluid pressure are now detectable and well-defined. The therapeutic approaches are symptom-oriented and aim to lower the pressure. With a precise diagnosis and timely start of therapy, idiopathic intracranial hypertension has a good prognosis, especially with regard to the preservation of eyesight.

Key Points:   · The idiopathic intracranial hypertension is an important differential diagnosis for unspecific headache and impaired vision. · Overweight women in childbearing age are particularly affected. · The most important component in diagnostics is MRI.

Citation Format: · Juhász J, Hensler J, Jansen O. MRT-Befunde bei der idiopathischen intrakraniellen Hypertension (Pseudotumor cerebri). Fortschr Röntgenstr 2021; DOI: 10.1055/a-1447-0264.
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http://dx.doi.org/10.1055/a-1447-0264DOI Listing
May 2021

A realistic way to investigate the design, and mechanical properties of flow diverter stents.

Expert Rev Med Devices 2021 Apr 23. Epub 2021 Apr 23.

Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany.

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http://dx.doi.org/10.1080/17434440.2021.1920923DOI Listing
April 2021

Does the primary soft-tissue sarcoma configuration predict configuration of recurrent tumors on magnetic resonance imaging?

Acta Radiol 2021 04 14:2841851211008381. Epub 2021 Apr 14.

Department for Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Campus Kiel, Germany.

Background: Soft-tissue sarcomas (STS) are rare malignancies of the soft tissue.

Purpose: To assess whether the magnetic resonance imaging (MRI) configuration of primary STS can predict the configuration of a recurring tumor and whether the MRI configuration of multiple recurrences differs in one and the same patient.

Material And Methods: Thirty-nine patients with histologically proven recurrent STS were included in this retrospective study and underwent pre- and post-treatment MRI. Three main configurations of primary and recurrent tumors were identified: polycyclic/multilobulated; ovoid/nodular; and streaky.

Results: Sixty recurrent lesions were detected: 34 ovoid/nodular; 15 polycyclic/multilobulated; and 11 streaky. Five recurrences were multifocal and eight were bifocal. Of 39 patients, 28 (71.8%) presented one recurrence within the MRI follow-up period ( = 0.006); in 10 patients (25.6%), up to three different configurations of recurring STS were identified in one patient. Recurrences of polycyclic/multilobulated primaries were mostly ovoid/nodular (48%;  = 0.003) or polycyclic/multilobulated (37%;  = 0.014), and recurring ovoid/nodular STS significantly most often showed the same configuration as the primary tumor (85%;  < 0.001). Primary STS with a streaky configuration recurred in all three configurations in roughly equal proportions. Homogeneity/heterogeneity and tumor borders are significantly associated with the configuration of recurrences.

Conclusion: Primary STS configuration may help predict recurrent tumor configuration when the primary STS had a polycyclic/multilobulated or ovoid/nodular configuration. However, recurrent STS configuration can also differ from primary STS configuration, especially when the primary STS had a streaky configuration, rendering recurrent STS difficult to predict. Different configurations of recurrent STS in one and the same patient are common.
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http://dx.doi.org/10.1177/02841851211008381DOI Listing
April 2021

Diagnostic value of MRI for detecting recurrent soft-tissue sarcoma in a long-term analysis at a multidisciplinary sarcoma center.

BMC Cancer 2021 Apr 13;21(1):398. Epub 2021 Apr 13.

Department for Radiology and Neuroradiology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Str. 3, 24105, Kiel, Germany.

Background: Soft-tissue sarcomas (STS) are rare tumors of the soft tissue. Recent diagnostic studies on STS mainly dealt with only few cases of STS and did not investigate the post-therapeutic performance of MRI in a routine clinical setting. Therefore, we assessed the long-term diagnostic accuracy of MRI for detecting recurrent STS at a multidisciplinary sarcoma center.

Methods: In all, 1055 postoperative follow-up MRIs of 204 patients were included in the study. MRI follow-up scans were systematically reviewed for diagnostic values (true-positive/-negative and false-positive/-negative results) in detecting recurrences. Pathological reports and follow-up MRIs were set as baseline references.

Results: The median age of the patients was 55.3 ± 18.2 years. Of the patients, 34.8% presented with recurrences. Here, 65 follow-up scans were true positive, 23 false positive, 6 false negative, and 961 true negative. The overall sensitivity and specificity of MRI for detecting recurrences were 92 and 98%, respectively, with an accuracy of 97%. For intramuscular lesions and after surgery alone the sensitivity was higher (95 and 97%, respectively) than for subcutaneous lesions and surgery with additional radiation therapy (83 and 86%, respectively), at similarly high specificities (96-98%). The 6 false-negative results were found in streaky (n = 2) and small ovoid/nodular (n = 4) recurring lesions. The false-positive lesions imitated streaky (n = 14), ovoid/nodular (n = 8), and polycyclic/multilobulated recurring tumors (n = 1). All false-positive results were found in patients in whom the primary tumors were polycyclic/multilobulated in appearance.

Conclusion: MRI shows a high diagnostic accuracy for detecting recurrent STS, with a high sensitivity and specificity. The diagnostic accuracy decreases in subcutaneous lesions and after surgery with radiation therapy, compared to intramuscular lesions and surgery alone. Radiologists should pay particular attention to streaky and small ovoid/nodular recurring lesions and patients with polycyclic/multilobulated primary tumors.
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http://dx.doi.org/10.1186/s12885-021-08113-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8042876PMC
April 2021

Risk of Stroke before Revascularisation in Patients with Symptomatic Carotid Stenosis: A Pooled Analysis of Randomised Controlled Trials.

Eur J Vasc Endovasc Surg 2021 Apr 5. Epub 2021 Apr 5.

Department of Neurology and Stroke Centre, Department of Clinical Research, University Hospital, University of Basel, Basel, Switzerland; Stroke Research Centre, Department of Brain Repair and Rehabilitation, UCL Queen Square Institute of Neurology, University College London, London, UK. Electronic address:

Objective: Current guidelines recommending rapid revascularisation of symptomatic carotid stenosis are largely based on data from clinical trials performed at a time when best medical therapy was potentially less effective than today. The risk of stroke and its predictors among patients with symptomatic carotid stenosis awaiting revascularisation in recent randomised controlled trials (RCTs) and in medical arms of earlier RCTs was assessed.

Methods: The pooled data of individual patients with symptomatic carotid stenosis randomised to stenting (CAS) or endarterectomy (CEA) in four recent RCTs, and of patients randomised to medical therapy in three earlier RCTs comparing CEA vs. medical therapy, were compared. The primary outcome event was any stroke occurring between randomisation and treatment by CAS or CEA, or within 120 days after randomisation.

Results: A total of 4 754 patients from recent trials and 1 227 from earlier trials were included. In recent trials, patients were randomised a median of 18 (IQR 7, 50) days after the qualifying event (QE). Twenty-three suffered a stroke while waiting for revascularisation (cumulative 120 day risk 1.97%, 95% confidence interval [CI] 0.75 - 3.17). Shorter time from QE until randomisation increased stroke risk after randomisation (χ = 6.58, p = .011). Sixty-one patients had a stroke within 120 days of randomisation in the medical arms of earlier trials (cumulative risk 5%, 95% CI 3.8 - 6.2). Stroke risk was lower in recent than earlier trials when adjusted for time between QE and randomisation, age, severity of QE, and degree of carotid stenosis (HR 0.47, 95% CI 0.25 - 0.88, p = .019).

Conclusion: Patients with symptomatic carotid stenosis enrolled in recent large RCTs had a lower risk of stroke after randomisation than historical controls. The added benefit of carotid revascularisation to modern medical care needs to be revisited in future studies. Until then, adhering to current recommendations for early revascularisation of patients with symptomatic carotid stenosis considered to require invasive treatment is advisable.
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http://dx.doi.org/10.1016/j.ejvs.2021.02.024DOI Listing
April 2021

Recanalization after cerebral venous thrombosis. A randomized controlled trial of the safety and efficacy of dabigatran etexilate versus dose-adjusted warfarin in patients with cerebral venous and dural sinus thrombosis.

Int J Stroke 2021 Apr 4:17474930211006303. Epub 2021 Apr 4.

Faculty of Medicine, University Duisburg-Essen, Essen, Germany.

Background: The effect of different anticoagulants on recanalization after cerebral venous thrombosis has not been studied in a randomized controlled trial.

Methods: RE-SPECT CVT (ClinicalTrials.gov number: NCT02913326) was a Phase III, prospective, randomized, parallel-group, open-label, multicenter, exploratory trial with blinded endpoint adjudication. Acute cerebral venous thrombosis patients were allocated to dabigatran 150 mg twice daily, or dose-adjusted warfarin, for 24 weeks, after 5-15 days' treatment with unfractionated or low-molecular-weight heparin. A standardized magnetic resonance protocol including arterial spin labeling, three-dimensional time-of-flight venography, and three-dimensional contrast-enhanced magnetic resonance angiography was obtained at the end of the treatment period. Cerebral venous recanalization at six months was assessed by two blinded adjudicators, using the difference in a score of occluded sinuses and veins (predefined secondary efficacy endpoint) and in the modified Qureshi scale (additional endpoint), between baseline and the end of the treatment.

Results: Of 120 cerebral venous thrombosis patients randomized, venous recanalization could be evaluated in 108 (55 allocated to dabigatran and 53 to warfarin, 1 patient had a missing occlusion score at baseline). No patient worsened in the score of occluded cerebral veins and sinuses, while 33 (60%) on dabigatran and 35 (67%) on warfarin improved. The mean score change from baseline in the occlusion score was similar in the two treatment groups (dabigatran -0.8, SD 0.78; warfarin -1.0, SD 0.92). In the modified Qureshi score, full recanalization was adjudicated in 24 (44%) and 19 (36%), and partial recanalization in 23 (42%) and 26 (49%) patients in the dabigatran and warfarin arms, respectively. No statistically significant treatment difference in the modified Qureshi score could be detected ( = 0.44).

Conclusion: The majority of patients with cerebral venous thrombosis, anticoagulated with either dabigatran or warfarin for six months, showed partial or complete recanalization of occluded sinuses and veins at the end of the treatment. Trial registry name: ClinicalTrials.gov URL: https://clinicaltrials.gov Registration number: NCT02913326.
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http://dx.doi.org/10.1177/17474930211006303DOI Listing
April 2021

Pseudo-Enhancement in Intracranial Aneurysms on Black-Blood MRI: Effects of Flow Rate, Spatial Resolution, and Additional Flow Suppression.

J Magn Reson Imaging 2021 Mar 10. Epub 2021 Mar 10.

Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel, Germany.

Background: Vessel-wall enhancement (VWE) on black-blood MRI (BB MRI) has been proposed as an imaging marker for a higher risk of rupture and associated with wall inflammation. Whether VWE is causally linked to inflammation or rather induced by flow phenomena has been a subject of debate.

Purpose: To study the effects of slow flow, spatial resolution, and motion-sensitized driven equilibrium (MSDE) preparation on signal intensities in BB MRI of patient-specific aneurysm flow models.

Study Type: Prospective.

Subjects/flow Aneurysm Model/virtual Vessels: Aneurysm flow models based on 3D rotational angiography datasets of three patients with intracranial aneurysms were 3D printed and perfused at two different flow rates, with and without Gd-containing contrast agent.

Field Strength/sequence: Variable refocusing flip angle 3D fast-spin echo sequence at 3 T with and without MSDE with three voxel sizes ((0.5 mm) , (0.7 mm) , and (0.9 mm) ); time-resolved with phase-contrast velocity-encoding 3D spoiled gradient echo sequence (4D flow MRI).

Assessment: Three independent observers performed a qualitative visual assessment of flow patterns and signal enhancement. Quantitative analysis included voxel-wise evaluation of signal intensities and magnitude velocity distributions in the aneurysm.

Statistical Tests: Kruskal-Wallis test, potential regressions.

Results: A hyperintense signal in the lumen and adjacent to the aneurysm walls on BB MRI was colocalized with slow flow. Signal intensities increased by a factor of 2.56 ± 0.68 (P < 0.01) after administering Gd contrast. After Gd contrast administration, the signal was suppressed most in conjunction with high flows and with MSDE (2.41 ± 2.07 for slow flow without MSDE, and 0.87 ± 0.99 for high flow with MSDE). A clear result was not achieved by modifying the spatial resolution .

Data Conclusions: Slow-flow phenomena contribute substantially to aneurysm enhancement and vary with MRI parameters. This should be considered in the clinical setting when assessing VWE in patients with an unruptured aneurysm.

Evidence Level: 2 TECHNICAL EFFICACY: Stage 2.
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http://dx.doi.org/10.1002/jmri.27587DOI Listing
March 2021

Practicability and Diagnostic Yield of One-Stop Stroke CT with Delayed-Phase Cardiac CT in Detecting Major Cardioembolic Sources of Acute Ischemic Stroke : A Proof of Concept Study.

Clin Neuroradiol 2021 Mar 10. Epub 2021 Mar 10.

Department for Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.

Purpose: Recurrent stroke is considered to increase the incidence of severe disability and death. For correct risk assessment and patient management it is essential to identify the origin of stroke at an early stage. Transthoracic echocardiography (TTE) is the initial standard of care for evaluating patients in whom a cardioembolic source of stroke (CES) is suspected but its diagnostic capability is limited. Transesophageal echocardiography (TEE) is considered as gold standard; however, this approach is time consuming, semi-invasive and not always feasible. We hypothesized that adding a delayed-phase cardiac computed tomography (cCT) to initial multimodal CT might represent a valid alternative to routine clinical echocardiographic work-up.

Material And Methods: Patients with suspected acute cardioembolic stroke verified by initial multimodal CT and subsequently examined with cCT were included. The cCT was evaluated for presence of major CES and compared to routine clinical echocardiographic work-up.

Results: In all, 102 patients with suspected acute CES underwent cCT. Among them 60 patients underwent routine work-up with echocardiography (50 TTE and only 10 TEE). By cCT 10/60 (16.7%) major CES were detected but only 4 (6.7%) were identified by echocardiography. All CES observed by echocardiography were also detected by cCT. In 8 of 36 patients in whom echocardiography was not performed cCT also revealed a major CES.

Conclusion: These preliminary results show the potential diagnostic yield of delayed-phase cCT to detect major CES and therefore could accelerate decision-making to prevent recurrence stroke. To confirm these results larger studies with TEE as the reference standard and also compared to TTE would be necessary.
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http://dx.doi.org/10.1007/s00062-021-01003-7DOI Listing
March 2021

Configuration of soft-tissue sarcoma on MRI correlates with grade of malignancy.

Radiol Oncol 2021 01 29;55(2):158-163. Epub 2021 Jan 29.

Department for Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Campus Kiel, Germany.

Background: The aim of the study was to assess whether the configuration of primary soft-tissue sarcoma (STS) on MRI correlates with the grade of malignancy.

Patients And Methods: 71 patients with histologically proven STS were included. Primary STS were examined for configuration, borders, and volume on MRI. The tumors were divided into high-grade (G3), intermediate-grade (G2) and low-grade (G1) STS according to the grading system of the French Federation of Cancer Centers Sarcoma Group (FNCLCC).

Results: 30 high-grade, 22 intermediate-grade and 19 low-grade primary STS lesions were identified. High- and intermediate-grade (G3/2) STS significantly most often appeared as polycyclic/multilobulated tumors (p < 0.001 and p = 0.002, respectively). Low-grade (G1) STS mainly showed an ovoid/nodular or streaky configuration (p = 0.008), and well-defined borders. The appearance of high-, intermediate- and low-grade STS with an ovoid/nodular configuration were mainly the same on MRI. All streaky G3/2 sarcoma and 17 of 20 patients with polycyclic/multilobulated G3 sarcoma showed infiltrative borders. High-grade streaky and polycyclic/multilobulated STS are larger in volume, compared to intermediate- and low-grade STS.

Conclusions: Configuration of STS on MRI can indicate the grade of malignancy. Higher-grade (G2/3) STS most often show a polycyclic/multilobulated configuration, while low-grade STS are mainly ovoid/nodular or streaky. Infiltrative behavior might suggest higher-grade STS in streaky and polycyclic/multilobulated STS.
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http://dx.doi.org/10.2478/raon-2021-0007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8042815PMC
January 2021

High-resolution, non-contrast-enhanced magnetic resonance angiography of the wrist, hand and digital arteries using optimized implementation of Cartesian quiescent interval slice selective (QISS) at 1.5 T.

Magn Reson Imaging 2021 05 11;78:58-68. Epub 2021 Feb 11.

Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany.

Purpose: Non-contrast-enhanced (CE) magnetic resonance angiography (MRA) techniques are of considerable interest for diagnosing vascular diseases in the upper extremities owing to the possibility of repeated examinations, sufficient coverage of the measurement volume, and because possible side effects of administering iodine- or gadolinium-based contrast agents and radiation exposure can be avoided. The aim of this study was to investigate the feasibility of an optimized electrocardiogram (ECG) triggered Cartesian quiescent interval slice selective (QISS) technique for MRA of hand arteries.

Material And Methods: Both hands of 20 healthy volunteers (HVs) were examined using an optimized QISS-MRA pulse sequence at 1.5 Tesla. The wrist and hand arterial trees were divided into 36 segments. Cross-sectional areas (CSA) of all arterial segments were measured. For the technical evaluation of the pulse sequence, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed and six imaging artifacts were graded. Two experienced observers used an ordinal scoring system to assess the image quality of each arterial segment. Interobserver agreement was determined.

Results: The median CSA was 7.3 mm in the ulnar and radial artery, 3.2 mm in the four common digital arteries, and 1.5 mm in five proper digital arteries. The median SNR and CNR of the third common proper arteries were 45.9 and 20.3, respectively. None of the arterial segments were contaminated by venous enhancement. The image quality of arterial segments for both hands was considered as diagnostic in 87.2% of all 1440 segments. An interobserver agreement of 0.67 for both hands was determined for image quality of arterial segments using a five-grade scoring system. Optimized QISS-MRA allows as the first MRA technique the classification of superficial palmar arch (SPA) and deep palmar arch (DPA) variants. 5 new SPA and 6 new DPA variants could be classified using QISS-MRA in comparison with previous studies using CE computed tomography angiography and using fixed cadaver hands.

Conclusions: By using this optimized 2D Cartesian QISS-MRA protocol, contrast agent-free angiography of the wrist and hand arteries provided a high in-plane spatial resolution and an excellent visualization of small digital arteries.
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http://dx.doi.org/10.1016/j.mri.2021.02.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7979532PMC
May 2021

The SITS Open Study: A Prospective, Open Label Blinded Evaluation Study of Thrombectomy in Clinical Practice.

Stroke 2021 Mar 10;52(3):792-801. Epub 2021 Feb 10.

Department of Clinical Neuroscience (N.A., S.H., N.W.), Karolinska Institutet, Stockholm, Sweden.

Background And Purpose: We designed SITS (Safe Implementation of Treatment in Stroke) Open to determine benefit and safety of thrombectomy in clinical practice for large artery occlusion stroke, using selected stent retrievers plus standard care versus standard care alone.

Methods: SITS Open was a prospective, open, blinded evaluation, international, multicenter, controlled, nonrandomized registry study. Centers lacking access to thrombectomy contributed controls. Primary end point was categorical shift in modified Rankin Scale score at 3 months in the per protocol (PP) population. Principal secondary outcomes were symptomatic intracranial hemorrhage, functional independency (modified Rankin Scale score 0-2) and death at 3 months. Patients independently evaluated by video-recorded modified Rankin Scale interviews blinded to treatment or center identity by central core laboratory were regarded as PP population. Propensity score matching with covariate adjusted analysis was performed.

Results: During 2014 to 2017, 293 patients (257 thrombectomy, 36 control) from 26 centers in 10 countries fulfilled intention-to-treat and 200 (170 thrombectomy, 30 control) PP criteria; enrollment of controls was limited by rapid uptake of thrombectomy. In PP analysis, median age was 71 versus 71 years, and baseline National Institutes of Health Stroke Scale 17 versus 17 in the thrombectomy and control arms, respectively. The propensity score matching analysis for PP showed a significant shift for modified Rankin Scale at 3 months favoring the thrombectomy group (odds ratio, 3.8 [95% CI, 1.61-8.95]; =0.002). Regarding safety, there were 4 cases of symptomatic intracranial hemorrhage in the thrombectomy group (2.4%) and none in the control group.

Conclusions: In clinical practice, thrombectomy for patients with large artery occlusion stroke is superior to standard of care in our study. Registration: URL: https://www.clinicaltrials.gov. Unique Identifier: NCT02326428.
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http://dx.doi.org/10.1161/STROKEAHA.120.031031DOI Listing
March 2021

Absence of Consistent Sex Differences in Outcomes From Symptomatic Carotid Endarterectomy and Stenting Randomized Trials.

Stroke 2021 Jan 25;52(2):416-423. Epub 2021 Jan 25.

Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).

Background And Purpose: CREST (Carotid Revascularization Endarterectomy Versus Stenting Trial) reported a higher periprocedural risk for any stroke, death, or myocardial infarction for women randomized to carotid artery stenting (CAS) compared with women randomized to carotid endarterectomy (CEA). No difference in risk by treatment was detected for women relative to men in the 4-year primary outcome. We aimed to conduct a pooled analysis among symptomatic patients in large randomized trials to provide more precise estimates of sex differences in the CAS-to-CEA risk for any stroke or death during the 120-day periprocedural period and ipsilateral stroke thereafter.

Methods: Data from the Carotid Stenosis Trialists' Collaboration included outcomes from symptomatic patients in EVA-3S (Endarterectomy Versus Angioplasty in Patients With Symptomatic Severe Carotid Stenosis), SPACE (Stent-Protected Angioplasty Versus Carotid Endarterectomy in Symptomatic Patients), ICSS (International Carotid Stenting Study), and CREST. The primary outcome was any stroke or death within 120 days after randomization and ipsilateral stroke thereafter. Event rates and relative risks were estimated using Poisson regression; effect modification by sex was assessed with a sex-by-treatment-by-trial interaction term, with significant interaction defined a priori as ≤0.10.

Results: Over a median 2.7 years of follow-up, 433 outcomes occurred in 3317 men and 1437 women. The CAS-to-CEA relative risk of the primary outcome was significantly lower for women compared with men in 1 trial, nominally lower in another, and nominally higher in the other two. The sex-by-treatment-by-trial interaction term was significant (=0.065), indicating heterogeneity among trials. Contributors to this heterogeneity are primarily differences in periprocedural period. When the trials are nevertheless pooled, there were no significant sex differences in risk in any follow-up period.

Conclusions: There were significant differences between trials in the magnitude of sex differences in treatment effect (CAS-to-CEA relative risk), indicating pooling data from these trials to estimate sex differences might not be valid. Whether sex is acting as an effect modifier of the CAS-to-CEA treatment effect in symptomatic patients remains uncertain. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00190398 (EVA-3S) and NCT00004732 (CREST). URL: https://www.isrctn.com; Unique identifier: ISRCTN57874028 (SPACE) and ISRCTN25337470 (ICSS).
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http://dx.doi.org/10.1161/STROKEAHA.120.030184DOI Listing
January 2021

Torsional Characterization of Braided Flow Diverter Stents : A New Method to Evaluate Twisting Phenomenon.

Clin Neuroradiol 2021 Jan 24. Epub 2021 Jan 24.

Chair for Inorganic Functional Materials, Kiel University, Kiel, Germany.

Purpose: In the interventional treatment of cerebral aneurysms, flow diverter (FD) stents have played a significant role for more than a decade. Many studies have shown good aneurysm occlusion rates and low complication profiles. However, feared complications include acute thrombotic vessel occlusion due to stenotic deformation of the FD during release, the so-called twisting. This work investigates the behavior of different stent types to causative torsion forces in a mechanical model.

Materials And Methods: Torsion characterization equipment was custom built, and two different FD stents (Derivo, Acandis and P64, Phenox) with n = 3 were tested. One end of the FD was fixed while the other end was twisted while measuring the torsion force.

Results: In torsional force vs. the twisting angle graph, a very sharp decrease and increase in force was recorded when the stent collapsed or reopened, respectively, making it possible to characterize for twisting. All six devices showed partial/complete collapse on torsion and showed significant delayed reopening on untwisting. Interestingly on repeated testing, the stent collapsed at earlier angles, probably due to microscopic material defects. Slight variations between stents of the same type suggest that more extensive data sets are needed.

Conclusions: We report a new method to characterize torsion for braided FD stents, which is reliable and reproducible. Additionally, the delayed reopening and the tendency to collapse at earlier angles on consequent testing maneuvers can be significant for clinical usage.
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http://dx.doi.org/10.1007/s00062-020-00991-2DOI Listing
January 2021

3D-printed, patient-specific intracranial aneurysm models: From clinical data to flow experiments with endovascular devices.

Med Phys 2021 Apr 17;48(4):1469-1484. Epub 2021 Feb 17.

Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Kiel, Germany.

Purpose: Flow models of intracranial aneurysms (IAs) can be used to test new and existing endovascular treatments with flow modulation devices (FMDs). Additionally, 4D flow magnetic resonance imaging (MRI) offers the ability to measure hemodynamics. This way, the effect of FMDs can be determined noninvasively and compared to patient data. Here, we describe a cost-effective method for producing flow models to test the efficiency of FMDs with 4D flow MRI.

Methods: The models were based on human radiological data (internal carotid and basilar arteries) and printed in 3D with stereolithography. The models were printed with three different printing layers (25, 50, and 100 µm thickness). To evaluate the models in vitro, 3D rotational angiography, time-of-flight MRI, and 4D flow MRI were employed. The flow and geometry of one model were compared with in vivo data. Two FMDs (FMD1 and FMD2) were deployed into two different IA models, and the effect on the flow was estimated by 4D flow MRI.

Results: Models printed with different layer thicknesses exhibited similar flow and little geometric variation. The mean spatial difference between the vessel geometry measured in vivo and in vitro was 0.7 ± 1.1 mm. The main flow features, such as vortices in the IAs, were reproduced. The velocities in the aneurysms were similar in vivo and in vitro (mean velocity magnitude: 5.4 ± 7.6 and 7.7 ± 8.6 cm/s, maximum velocity magnitude: 72.5 and 55.1 cm/s). By deploying FMDs, the mean velocity was reduced in the IAs (from 8.3 ± 10 to 4.3 ± 9.32 cm/s for FMD1 and 9.9 ± 12.1 to 2.1 ± 5.6 cm/s for FMD2).

Conclusions: The presented method allows to produce neurovascular models in approx. 15 to 30 h. The resulting models were found to be geometrically accurate, reproducing the main flow patterns, and suitable for implanting FMDs as well as 4D flow MRI.
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http://dx.doi.org/10.1002/mp.14714DOI Listing
April 2021

Long-term diagnostic value of MRI in detecting recurrent aggressive fibromatosis at two multidisciplinary sarcoma centers.

Eur J Radiol 2021 Jan 12;134:109406. Epub 2020 Nov 12.

Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Germany; Department for Interventional Radiology and Neuroradiology, Klinikum Hochsauerland, Arnsberg, Germany.

Purpose: To assess the diagnostic accuracy of MRI in detecting recurrent aggressive fibromatosis (AF) during long-term follow-up at two multidisciplinary sarcoma centers.

Methods: Seventy-nine patients from two sarcoma centers were included in this IRB-approved study and were examined postoperatively using 1.5-T MRI. MRI follow-up scans were reviewed for true-positive/-negative and false-positive/-negative results. Available pathological reports and MRI follow-ups were set as reference.

Results: The median age of the patients was 38.1 ± 15.3 years. Of the patients 27.9 % showed recurrent AF lesions. The most common localizations of AF were the axilla/shoulder (n = 15) and the thigh (n = 11). From 498 postoperative MRI follow-ups, 24 true-positive, 16 false-positive, 6 false-negative, and 452 true-negative MRI follow-ups were identified. The overall sensitivity and specificity for detecting recurrent AF was 80 % and 97 %, respectively. There was no significant difference in the diagnostic accuracy at the two sarcoma centers. All false-negative results were found in small lesions. False-positive results mostly mimicked streaky (n = 10) and small ovoid/nodular (n = 5) lesions. The configuration of recurrent AF was significantly most often fascicular (50 %; p = 0.001-0.005).

Conclusion: MRI shows a high long-term diagnostic value in detecting AF recurrences. Nevertheless, radiologists should pay close attention when lesions are small, as they may remain undetected. Although the configuration of recurrent AF is most often fascicular, recurrences may also appear in different shapes.
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http://dx.doi.org/10.1016/j.ejrad.2020.109406DOI Listing
January 2021

Choosing an Effective and Safe Direct Aspiration Setup for Tortuous Anatomy in Acute Ischemic Stroke: In vitro Study in a Physiological Flow Model.

Rofo 2021 May 19;193(5):544-550. Epub 2020 Nov 19.

Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Kiel, Germany.

Purpose:  A direct aspiration first pass technique (ADAPT) is an effective thrombectomy option in patients with acute ischemic stroke. Balloon guide catheters (BGC) seem to improve the efficacy of stent retrievers and ADAPT. The last generation 6F aspiration catheters require 9F BGCs, which are rigid devices that are challenging to position in a tortuous anatomy. In this experimental study the efficacy of 6F ADAPT alone and 5F ADAPT combined with 8F BGC was evaluated.

Materials And Methods:  Either a fibrin rich (white) clot or an RBC rich (red) clot was placed in the M1 segment of a transparent silicon phantom. Physiological hemodynamic conditions were maintained. The clots were retrieved by 6F aspiration catheter via 8F long sheath or 5F aspiration catheter via a flexible 8F BGC. Thrombectomy was performed under direct visual control. The primary endpoints were the number of passes and the number of distal emboli.

Results:  Ten experiments were made with each clot model and thrombectomy technique (n = 40). Full recanalization could be achieved in every experiment. First pass mTICI 3 could be achieved by 6F ADAPT in 80 % of red clots and 90 % of white clots. Distal emboli were caused in 10 % and 20 %, respectively. When using 5F ADAPT combined with BGC, a first pass mTICI 3 rate of 90 % in red clots and 100 % in white clots could be achieved. A 10 % rate of distal emboli occurred in both groups. In almost all experiments (both techniques), the thrombi clogged the aspiration catheter. No statistically significant differences could be found between the techniques and clot models.

Conclusion:  6F ADAPT without BGC was as effective as 5F ADAPT combined with a flexible 8F BGC, with both techniques showing high first-pass recanalization rates and low distal emboli rates. Especially in the case of a tortuous anatomy, these setups should be considered as alternatives to a rigid 9F BGC. The thrombus compositions seemed to be irrelevant in this setting.

Key Points:   · 6F ADAPT with no BGC and 5F ADAPT with BGC were very effective and performed equally.. · Both techniques should be considered in tortuous anatomy.. · In this setting the clot composition showed no effect on the recanalization rate..

Citation Format: · Madjidyar J, Nerkada L, Larsen N et al. Choosing an Effective and Safe Direct Aspiration Setup for Tortuous Anatomy in Acute Ischemic Stroke: In vitro Study in a Physiological Flow Model. Fortschr Röntgenstr 2021; 193: 544 - 550.
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http://dx.doi.org/10.1055/a-1288-1475DOI Listing
May 2021

Cerebral Imaging in Patients with COVID-19 and Neurological Symptoms: First Experience from two University Hospitals in Northern Germany.

Rofo 2020 Nov 19. Epub 2020 Nov 19.

Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein, Campus Kiel, Germany.

Purpose:  To describe findings on cerebral imaging in patients with COVID-19 and neurological symptoms at two German university hospitals.

Materials And Methods:  Patients with COVID-19 and neurological symptoms and cerebral imaging (CT or MRI) were included. A chart review regarding neurological symptoms, COVID-19 and imaging findings was conducted.

Results:  12 patients (4 females, age 68 ± 12 years) could be included. Three patients had acute findings. Two patients had acute and subacute cerebral ischemia, one patient had additional intracranial hemorrhages and presumed central pontine myelinolysis. One patient had presumed COVID-19-associated pansinusitis.

Conclusion:  Findings on cerebral imaging in patients with COVID-19 are uncommon and nonspecific. However, cerebral ischemia is regularly encountered and patients should be evaluated for stroke symptoms.

Key Points:   · Approx. 20 % of patients with COVID-19 develop neurological symptoms.. · Findings on cerebral imaging in patients with COVID-19 are heterogeneous and nonspecific.. · The most common findings are cerebral ischemia and hemorrhages..

Citation Format: · Jensen-Kondering U, Neumann A, Margraf N et al. Cerebral Imaging in Patients with COVID-19 and Neurological Symptoms: First Experience from two University Hospitals in Northern Germany. Fortschr Röntgenstr 2020; DOI: 10.1055/a-1265-7209.
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http://dx.doi.org/10.1055/a-1265-7209DOI Listing
November 2020

Comparison of photoacoustic and fluorescence tomography for the imaging of ICG-labelled liposomes in the medullary cavity in mice.

Photoacoustics 2020 Dec 1;20:100210. Epub 2020 Oct 1.

Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein Kiel, Kiel University, Am Botanischen Garten 14, 24118 Kiel, Germany.

Few reports quantitatively compare the performance of photoacoustic tomography (PAT) fluorescence molecular tomography (FMT) . We compared both modalities for the detection of signals from injected ICG liposomes in the tibial medullary space of 10 BALB/c mice and . Signals significantly correlated between modalities (R² = 0.69) and within each modality (PAT: R² = 0.70, FMT: R² = 0.76). Phantom studies showed that signals at 4 mm depth are detected down to 3.3 ng ICG by PAT and 33 ng by FMT, with a nominal spatial resolution below 0.5 mm in PAT and limited to 1 mm in FMT. Our study demonstrates comparable sensitivity, but superior sensitivity and resolution for our ICG liposomes of the VevoLAZR the FMT2500. PAT provides a useful new tool for the high-resolution imaging of bone marrow signals, for example for monitoring drug delivery.
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http://dx.doi.org/10.1016/j.pacs.2020.100210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7569329PMC
December 2020

Dural Arteriovenous Fistulae After Cerebral Venous Thrombosis.

Stroke 2020 11 25;51(11):3344-3347. Epub 2020 Sep 25.

Faculty of Medicine, University Duisburg-Essen, Germany (H.-C.D.).

Background And Purpose: This analysis examined the frequency of dural arteriovenous fistulae (dAVF) after cerebral venous thrombosis (CVT) in patients included in a randomized controlled trial comparing dabigatran etexilate with dose-adjusted warfarin (RE-SPECT CVT [A Clinical Trial Comparing Efficacy and Safety of Dabigatran Etexilate With Warfarin in Patients With Cerebral Venous and Dural Sinus Thrombosis]), who had systematic follow-up magnetic resonance (MR) imaging.

Methods: RE-SPECT CVT was a Phase 3, prospective, randomized, parallel-group, open-label, multicenter, exploratory trial with blinded end point adjudication. We allocated patients with acute CVT to dabigatran 150 mg twice daily or dose-adjusted warfarin, for 24 weeks and obtained a standardized MR protocol including time-of-flight MR angiography, 3-dimensional phase-contrast venography, and 3-dimensional contrast-enhanced MR venography at the end of the treatment period. A blinded adjudication committee assessed the presence of dAVF in a predefined substudy of the trial.

Results: We analyzed development of dAVF in 112 of 120 randomized patients; 57 allocated to dabigatran and 55 to warfarin. For 3 (2.7%) of these 112 patients, quality of follow-up imaging was insufficient to evaluate dAVF. A dAVF (Borden I) was found in 1 patient (0.9%) allocated to warfarin; however, this dAVF was already present at baseline. The patient did not present with hemorrhage at baseline or during the trial and was asymptomatic at follow-up.

Conclusions: Despite systematic imaging, we found no new dAVF 6 months after CVT. Routine follow-up cerebral MR angiography aiming to detect new dAVF 6 months after CVT has a very low yield. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02913326.
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http://dx.doi.org/10.1161/STROKEAHA.120.031235DOI Listing
November 2020

Derivo embolization device in the treatment of unruptured intracranial aneurysms: a prospective multicenter study.

J Neurointerv Surg 2021 Jun 8;13(6):541-546. Epub 2020 Sep 8.

Department of Intracranial Endovascular Therapy, Alfried Krupp Krankenhaus Essen, Essen, Germany.

Background: Flow diverters (FD) are used regularly for the endovascular treatment of unruptured intracranial aneurysms. We aimed to assess the safety and effectiveness of the Derivo embolization device (DED) with respect to long-term clinical and angiographic outcomes.

Methods: A prospective multicenter trial was conducted at 12 centers. Patients presenting with modified Rankin Score (mRS) of 0-1, treated for unruptured intracranial aneurysms with DED were eligible. Primary endpoint was the mRS assessed at 18 months with major morbidity defined as mRS 3-5. Satisfactory angiographic occlusion was defined as 3+4 on the Kamran scale.

Results: Between July 2014 and February 2018, 119 patients were enrolled. Twenty-three patients were excluded. Ninety-six patients, 71 (74%) female, mean age 54±12.0 years, were included in the analysis. Mean aneurysm size was 14.2±16.9 mm. The mean number of devices implanted per patient was 1.2 (range 1-3). Clinical follow-up at 18 months was available in 90 (94%) patients, resulting in a mean follow-up period of 14.8±5.2 months. At last available follow-up of 96 enrolled patients, 91 (95%) remained mRS 0-1. The major morbidity rate (mRS 3-5) was 3.1% (3/96), major stroke rate was 4.2% (4/96), and mortality was 0%. Follow-up angiographies were available in 89 (93%) patients at a median of 12.4±5.84 months with a core laboratory adjudicated satisfactory aneurysm occlusion in 89% (79/89).

Conclusion: Our results suggest that DED is a safe and effective treatment for unruptured aneurysms with high rates of satisfactory occlusion and comparably low rates of permanent neurological morbidity and mortality.

Trial Registration: DRKS00006103.
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http://dx.doi.org/10.1136/neurintsurg-2020-016303DOI Listing
June 2021

The novel Tenzing 7 delivery catheter designed to deliver intermediate catheters to the face of embolus without crossing: clinical performance predicted in anatomically challenging model.

J Neurointerv Surg 2020 Sep 3. Epub 2020 Sep 3.

Radiology, California Pacific Medical Center, San Francisco, California, USA.

Background: In large vessel occlusionstroke, navigation of aspiration catheters (AC) can be impeded by vessel tortuosity and the ophthalmic artery origin. A novel tapered delivery catheter was designed to facilitate delivery without disturbing the embolus. We assessed AC deliverability in vitro and validated the observations in a first-in-human experience.

Methods: In a vascular model with three challenging craniocervical scenarios, two commercial AC were advanced from the carotid to the middle cerebral artery by four neurointerventionalists. Catheter deliverability with standard microwire and microcatheter (MC) combinations and the Tenzing 7 (T7) Delivery Catheter (Route 92 Medical, San Mateo, CA) were compared. Operators rated aspects of catheter deliverability on a 5-point scale. Results were compared with device delivery patterns at a neurovascular center before and after clinical introduction of T7.

Results: In vitro, success rate and speed were higher with T7 (96%; mean 30±10 s) than with MC (65%; 72±47 s, p<0.001 each), with fewer interactions with the occlusion site (T7: 54% vs MC: 77%, p=0.004). T7 received superior ratings regarding carotid artery deflection (T7: 2, IQR1-3 vs MC: 3, IQR2-3, p<0.001), guide catheter pushback (T7: 2, IQR1-3 vs MC: 3, IQR3-3, p<0.001) and ophthalmic artery passage (T7: 1.5, IQR1-2 vs MC: 4, IQR3-5, p<0.001). Before introduction of T7 at a single center, delivery of AC to a large vessel occlusion without crossing was achieved in 15/123 cases (12%). With T7, this rate was 28/31 patients (90.3%).

Conclusion: Compared with microcatheter and microwire combinations, T7 improves aspiration catheter delivery in vitro, minimizing the need to cross the occlusion. Initial clinical experience appears to validate the model's observations.
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http://dx.doi.org/10.1136/neurintsurg-2020-016412DOI Listing
September 2020

Intratumoral Distribution of Lactate and the Monocarboxylate Transporters 1 and 4 in Human Glioblastoma Multiforme and Their Relationships to Tumor Progression-Associated Markers.

Int J Mol Sci 2020 Aug 29;21(17). Epub 2020 Aug 29.

Department of Neurosurgery, University Medical Center Schleswig-Holstein UKSH, Campus Kiel, 24105 Kiel, Germany.

(1) Background: Metabolic reprogramming has been postulated to be one of the hallmarks of cancer, thus representing a promising therapeutic target also in glioblastoma multiforme (GBM). Hypoxic tumor cells produce lactate, and monocarboxylate transporters (MCTs) play an important role in its distribution; (2) Methods: We examined the distribution of lactate by multi voxel magnetic resonance spectroscopic imaging and ELISA in glioblastoma multiforme (GBM) patients. In addition, we investigated the expression and cellular localization of MCT1, MCT4, and of several markers connected to tumor progression by quantitative PCR and immunofluorescence double-staining in human GBM ex vivo tissues; (3) Results: The highest lactate concentration was found at the center of the vital parts of the tumor. Three main GBM groups could be distinguished according to their regional gene expression differences of the investigated genes. MCT1 and MCT4 were found on cells undergoing epithelial to mesenchymal transition and on tumor stem-like cells. GBM cells revealing an expression of cellular dormancy markers, showed positive staining for MCT4; (4) Conclusion: Our findings indicate the existence of individual differences in the regional distribution of MCT1 and MCT4 and suggest that both transporters have distinct connections to GBM progression processes, which could contribute to the drug resistance of MCT-inhibitors.
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http://dx.doi.org/10.3390/ijms21176254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7504270PMC
August 2020

Multimodal validation of focal enhancement in intracranial aneurysms as a surrogate marker for aneurysm instability.

Neuroradiology 2020 Dec 17;62(12):1627-1635. Epub 2020 Jul 17.

Forschungscampus STIMULATE, University of Magdeburg, Magdeburg, Germany.

Purpose: Circumferential enhancement on MR vessel wall imaging has been proposed as a biomarker of a higher risk of rupture in intracranial aneurysms. Focal enhancement is frequently encountered in unruptured aneurysms, but its implication for risk stratification and patient management remains unclear. This study investigates the association of focal wall enhancement with hemodynamic and morphological risk factors and histologic markers of wall inflammation and degeneration.

Methods: Patients with an unruptured middle cerebral artery aneurysm who underwent 3D rotational angiography and 3T MR vessel wall imaging showing focal wall enhancement were included. Hemodynamic parameters were calculated based on flow simulations and compared between enhanced regions and the entire aneurysm surface. Morphological parameters were semiautomatically extracted and quantitatively associated with wall enhancement. Histological analysis included detection of vasa vasorum, CD34, and myeloperoxidase staining in a subset of patients.

Results: Twenty-two aneurysms were analyzed. Enhanced regions were significantly associated with lower AWSS, lower maxOSI, and increased LSA. In multivariate analysis, higher ellipticity index was an independent predictor of wall enhancement. Histologic signs of inflammation and degeneration and higher PHASES score were significantly associated with focal enhancement.

Conclusion: Focal wall enhancement is colocalized with hemodynamic factors that have been related to a higher rupture risk. It is correlated with morphological factors linked to rupture risk, higher PHASES score, and histologic markers of wall destabilization. The results support the hypothesis that focal enhancement could serve as a surrogate marker for aneurysm instability.
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http://dx.doi.org/10.1007/s00234-020-02498-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7666674PMC
December 2020

Clinical and radiological differences between patients with probable cerebral amyloid angiopathy and mixed cerebral microbleeds.

J Neurol 2020 Dec 8;267(12):3602-3608. Epub 2020 Jul 8.

Department of Neurology, University of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Str. 3, Haus D, 24105, Kiel, Germany.

Background: The key imaging features of cerebral amyloid angiopathy (CAA) are lobar, cortical, or cortico-subcortical microbleeds, macrohaemorrhages and cortical superficial siderosis (cSS). In contrast, hypertensive angiopathy is characterized by (micro) haemorrhages in the basal ganglia, thalami, periventricular white matter or the brain stem. Another distinct form of haemorrhagic microangiopathy is mixed cerebral microbleeds (mixed CMB) with features of both CAA and hypertensive angiopathy. The distinction between the two entities (CAA and mixed CMB) is clinically relevant because the risk of haemorrhage and stroke should be well balanced if oral anticoagulation is indicated in CAA patients. We aimed to comprehensively compare these two entities.

Methods: Patients with probable CAA according to the modified Boston criteria and mixed CMB without macrohaemorrhage were retrospectively identified from our database. Comprehensive comparison regarding clinical and radiological parameters was performed between the two cohorts.

Results: Patients with CAA were older (78 ± 8 vs. 74 ± 9 years, p = 0.036) and had a higher prevalence of cSS (19% vs. 4%, p = 0.027) but a lower prevalence of lacunes (73% vs. 50%, p = 0.018) and deep lacunes (23% vs. 51%, p = 0.0003) compared to patients with mixed CMB. Logistic regression revealed an association between the presence of deep lacunes and mixed CMB. The other collected parameters did not reveal a significant difference between the two groups.

Conclusions: CAA and mixed CMB demonstrate radiological differences in the absence of macrohaemorrhages. However, more clinically available biomarkers are needed to elucidate the contribution of CAA and hypertensive angiopathy in mixed CMB patients.
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http://dx.doi.org/10.1007/s00415-020-10038-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7674181PMC
December 2020

Clinical Value of Noncontrast-Enhanced Radial Quiescent-Interval Slice-Selective (QISS) Magnetic Resonance Angiography for the Diagnosis of Acute Pulmonary Embolism Compared to Contrast-Enhanced Computed Tomography and Cartesian Balanced Steady-State Free Precession.

J Magn Reson Imaging 2020 11 14;52(5):1510-1524. Epub 2020 Jun 14.

Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, Kiel, Germany.

Background: Free-breathing noncontrast-enhanced (non-CE) magnetic resonance angiography (MRA) techniques are of considerable interest for the diagnosis of acute pulmonary embolism (APE), due to the possibility for repeated examinations, avoidance of side effects from iodine-based contrast agents, and the absence of ionizing radiation exposure as compared to CE-computed tomographic angiography (CTA).

Purpose: To analyze the clinical performance of free-breathing and electrocardiogram (ECG)-gated radial quiescent-interval slice-selective (QISS)-MRA compared to CE-CTA and to Cartesian balanced steady-state free precession (bSSFP)-MRA.

Study Type: Prospective.

Subjects: Thirty patients with confirmed APE and 30 healthy volunteers (HVs).

Field Strength/sequence: Radial QISS- and bSSFP-MRA at 1.5T.

Assessment: Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed to compare the pulmonary imaging quality between MRA methods. The pulmonary arterial tree was divided into 25 branches and an ordinal scoring system was used to assess the image quality of each pulmonary branch. The clinical performance of the two MRA techniques in accurately assessing APE was evaluated with respect to CE-CTA as the clinical reference standard.

Statistical Tests: Wilcoxon signed-rank and Spearman's correlation tests were performed. Sensitivity and specificity of the MRA techniques were determined using CE-CTA as the clinical reference standard.

Results: Thrombus-mimicking artifacts appeared more frequently in lobar and peripheral arteries of patients with Cartesian bSSFP than with radial QISS-MRA (pulmonary trunk: 12.2% vs. 14.0%, P = 0.64; lobar arteries: 35.6% vs. 22.0%, P = 0.005, peripheral arteries: 74.4% vs. 49.0%, P < 0.001). The relative increases in SNR and of CNR provided by radial QISS-MRA with respect to Cartesian bSSFP-MRA were 30-35% (P-values of SNR/CNR, HVs: 0.09/0.09, patients: 0.03/0.02). The image quality of pulmonary arterial branches was considered good to excellent in 77.2% of patients with radial QISS-MRA and in 43.2% with Cartesian bSSFP-MRA (P < 0.0001). The clinical performance of radial QISS-MRA was higher than Cartesian bSSFP-MRA for grading embolism, with a total sensitivity of 86.0% vs. 80.6% and a specificity of 93.3% vs. 84.0%, respectively.

Data Conclusion: Radial QISS-MRA is a reliable and safe non-CE angiographic technique with promising clinical potential compared to Cartesian bSSFP-MRA and as an alternative technique to CE-CTA for the diagnosis of APE.

Level Of Evidence: 1 TECHNICAL EFFICACY STAGE: 3.
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http://dx.doi.org/10.1002/jmri.27240DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7655522PMC
November 2020

Ternary encoded super-selective arterial spin labeling for time-resolved flow territory mapping.

Phys Med Biol 2020 05 11;65(10):10NT01. Epub 2020 May 11.

Department of Radiology and Neuroradiology, UKSH Campus Kiel, Kiel, Germany. Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

Arterial spin labeling (ASL) is a non-contrast enhanced method for perfusion measurements. The obtained information is in general a snap-shot of the whole-brain perfusion. Image acquisition is performed after a certain delay time after the labeling of the arterial blood. Time-resolved information alongside flow territory mapping of individual arteries can become useful for the collection of important information such as arterial crossflow, and revascularization. Therefore, a method is presented that combines time-resolved flow territory mapping within a single scan based on encoding of the acquisition cycle using a ternary matrix approach. The super-selective tagging process is divided in individual blocks following a ternary matrix encoding scheme. In each block, the position of the labeling focus changes its position to each of the major brain feeding arteries. Contrary to conventional ASL approaches, no control condition is acquired and the individual flow territories are calculated by combining the label images only. The method was successfully evaluated in healthy volunteers. Each flow territory could be visualized over several post labeling delays within a single scan of approximately five minutes. Comparison of signal intensity (relative perfusion) did not show statistically significant differences between the methods. Encoding super-selective ASL using a ternary matrix allows for the vessel-selective and time-resolved acquisition of perfusion territories within a single scan.
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http://dx.doi.org/10.1088/1361-6560/ab7ef0DOI Listing
May 2020

Early experience with a novel net temporary bridging device (Cascade) to assist endovascular coil embolization of intracranial aneurysms.

J Neurosurg 2020 Jan 24:1-9. Epub 2020 Jan 24.

2Vall d'Hebron Research Institute (VHIR), Vall d'Hebron University Hospital, Barcelona, Spain.

Objective: The goal of this study was to evaluate the effectiveness and safety of a new noncompletely occlusive net-assisted remodeling technique in which the Cascade net device is used for temporary bridging of intracranial aneurysms.

Methods: Between July 2018 and May 2019, patients underwent coil embolization with the Cascade net device within 4 centers in Europe. Analysis of angiographic (modified Raymond-Roy classification [MRRC]) and clinical outcomes data was conducted immediately following treatment and at the 6-month follow-up.

Results: Fifteen patients were included in the study (mean age 58 ± 13 years, 11/15 [73.3%] female). Ten patients had unruptured aneurysms, and 5 presented with ruptured aneurysms with acute subarachnoid hemorrhage. The mean aneurysm dome length was 6.27 ± 2.33 mm and the mean neck width was 3.64 ± 1.19 mm. Immediately postprocedure, MRRC type I (complete obliteration) was achieved in 11 patients (73.3%), whereas a type II (residual neck) was achieved in 4 patients (26.7%). Follow-up examination was performed in 7/15 patients and showed stabilization of aneurysm closure with no thromboembolic complications and only 1 patient with an increased MRRC score (from I to II) due to coil compression.

Conclusions: Initial experience shows that the use of a new noncompletely occlusive net-assisted remodeling technique with the Cascade net device may be safe and effective for endovascular coil embolization of intracranial aneurysms.
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http://dx.doi.org/10.3171/2019.11.JNS192477DOI Listing
January 2020

MRI in patients with implanted active devices: how to combine safety and image quality using a limited transmission field?

Eur Radiol 2020 May 23;30(5):2571-2582. Epub 2020 Jan 23.

Department of Radiology and Neuroradiology, University Hospital Schleswig-Holstein Campus Kiel, Arnold-Heller-Straße 3, Haus 41, 24105, Kiel, Germany.

Objectives: Radio frequency (RF) pulses in magnetic resonance imaging (MRI) can interact with implanted devices and cause tissue damage. However, there are new devices that can safely perform measurements with liberal MRI conditions such as an RF transmission field B ≤ 2.0 μT. We investigated whether MRI in this case is limited for these technical reasons.

Methods: We selected typical MRI protocols of six body regions (brain, cervical spine, lumbar spine, knee, liver, heart) using two typical 1.5T MRI scanners. Overall, we adapted 62 sequences to B conditions and evaluated their diagnostic quality. For this, we measured signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR), and geometric deviation (GD) as quality parameters, using phantom studies. For questionnaire studies, we selected pairs of original and adapted sequences in healthy volunteers. Blinded radiologists rated the images as single sequence rating and in direct comparison.

Results: Roughly one-third of the checked sequences were below the B limit. Here, 56 of the 62 adapted sequences showed at least the same image quality in single ratings. A reduction in SNR and/or CNR was found with 31 sequences and only one sequence with considerably increased GD. Especially, sequences with original high B values, PD sequences, and sequences of the Siemens knee and heart protocol were difficult to adapt, whereas most TSE and IR sequences had no clinical limitations.

Conclusion: By limiting the transmission field to B ≤ 2.0 μT, clinically relevant MR sequences can be adapted with nearly no reduction in image quality. Despite limiting the transmission field, high-quality MR imaging is possible. We could derive strategies for adaptation.

Key Points: • Despite limiting the transmission field, high-quality MRI is possible. • We could derive strategies for adapting the sequences to B≤ 2.0 μT. • This enables high-quality MRI of different body regions for patients with AD.
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http://dx.doi.org/10.1007/s00330-019-06599-6DOI Listing
May 2020

Neuroimaging Of Cold Allodynia Reveals A Central Disinhibition Mechanism Of Pain.

J Pain Res 2019 11;12:3055-3066. Epub 2019 Nov 11.

Division of Neurological Pain Research and Therapy, Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.

Purpose: Allodynia refers to pain evoked by physiologically innocuous stimuli. It is a disabling symptom of neuropathic pain following a lesion within the peripheral or central nervous system. In fact, two different pathophysiological mechanisms of cold allodynia (ie, hypersensitivity to innocuous cold) have been proposed. The peripheral sensitization of nociceptive neurons can produce cold allodynia, which can be induced experimentally by a topical application of menthol. An alternative mechanism involves reduced inhibition of central pain processing by innocuous cold stimuli. A model to induce the latter type of allodynia is the conduction block of peripheral A-fiber input.

Patients And Methods: In the presented study, functional MRI was used to analyze these two different experimental models of cold allodynia. In order to identify the underlying cerebral activation patterns of both mechanisms, the application of menthol and the induction of a mechanical A-fiber blockade were studied in healthy volunteers.

Results: The block-induced cold allodynia caused significantly stronger activation of the medial polymodal pain processing pathway, including left medial thalamus, anterior cingulate cortex, and medial prefrontal cortex. In contrast, menthol-induced cold allodynia caused significantly stronger activity of the left lateral thalamus as well as the primary and secondary somatosensory cortices, key structures of the lateral discriminative pathway of pain processing. Mean pain intensity did not differ between both forms of cold allodynia.

Conclusion: Experimental cold allodynia is mediated in different cerebral areas depending on the underlying pathophysiology. The activity pattern associated with block-induced allodynia confirms a fundamental integration between painful and non-painful temperature sensation, ie, the cold-induced inhibition of cold pain.
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http://dx.doi.org/10.2147/JPR.S216508DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6857664PMC
November 2019