601 research outputs found
Imaging of VSOP Labeled Stem Cells in Agarose Phantoms with Susceptibility Weighted and T2* Weighted MR Imaging at 3T: Determination of the Detection Limit
Objectives: This study aimed to evaluate the detectability of stem cells labeled with very small iron oxide particles (VSOP) at 3T with susceptibility weighted (SWI) and T2* weighted imaging as a methodological basis for subsequent examinations in a large animal stroke model (sheep). Materials and Methods We examined ovine mesenchymal stem cells labeled with VSOP in agarose layer phantoms. The experiments were performed in 2 different groups, with quantities of 0–100,000 labeled cells per layer. 15 different SWI- and T2*-weighted sequences and 3 RF coils were used. All measurements were carried out on a clinical 3T MRI. Images of Group A were analyzed by four radiologists blinded for the number of cells, and rated for detectability according to a four-step scale. Images of Group B were subject to a ROI-based analysis of signal intensities. Signal deviations of more than the 0.95 confidence interval in cell containing layers as compared to the mean of the signal intensity of non cell bearing layers were considered significant. Results: Group A: 500 or more labeled cells were judged as confidently visible when examined with a SWI-sequence with 0.15 mm slice thickness. Group B: 500 or more labeled cells showed a significant signal reduction in SWI sequences with a slice thickness of 0.25 mm. Slice thickness and cell number per layer had a significant influence on the amount of detected signal reduction. Conclusion: 500 VSOP labeled stem cells could be detected with SWI imaging at 3 Tesla using an experimental design suitable for large animal models
Treatment Effect of CT-Guided Periradicular Injections in Context of Different Contrast Agent Distribution Patterns
Acutely manifesting radicular pain syndromes associated with degenerations of the lower
spine are frequent ailments with a high rate of recurrence. Part of the conservative management are
periradicular infiltrations of analgesics and steroids. The purpose of this study is to evaluate the
dependence of the clinical efficacy of CT-guided periradicular injections on the pattern of contrast
distribution and to identify the best distribution pattern that is associated with the most effective pain
relief. Using a prospective study design, 161 patients were included in this study, ensuring ethical
standards. Statistical analysis was performed, with the level of statistical significance set at p = 0.05.
A total of 37.9% of patients experienced significant but not long-lasting (four weeks on average)
complete pain relief. A total of 44.1% of patients experienced prolonged, subjectively satisfying pain
relief of more than four weeks to three months. A total of 18% of patients had complete and sustained
relief for more than six months. A significant correlation exists between circumferential, large area
contrast distribution including the zone of action between the disc and affected nerve root contrast
distribution pattern with excellent pain relief. Our results support the value of CT-guided contrast
injection for achieving a good efficacy, and, if necessary, indicative repositioning of the needle to
ensure a circumferential distribution pattern of corticosteroids for the sufficient treatment of radicular
pain in degenerative spine disease
Histogram Analysis of Diffusion Weighted Imaging in Low-Grade Gliomas: in vivo Characterization of Tumor Architecture and Corresponding Neuropathology
Background: Low-grade gliomas (LGG) in adults are usually slow growing and frequently
asymptomatic brain tumors, originating from glial cells of the central nervous system
(CNS). Although regarded formally as “benign” neoplasms, they harbor the potential of
malignant transformation associated with high morbidity and mortality. Their complex
and unpredictable tumor biology requires a reliable and conclusive presurgical magnetic
resonance imaging (MRI). A promising and emerging MRI approach in this context is
histogram based apparent diffusion coefficient (ADC) profiling, which recently proofed
to be capable of providing prognostic relevant information in different tumor entities.
Therefore, our study investigated whether histogram profiling of ADC distinguishes grade
I from grade II glioma, reflects the proliferation index Ki-67, as well as the IDH (isocitrate
dehydrogenase) mutation and MGMT (methylguanine-DNA methyl-transferase) promotor
methylation status.
Material and Methods: Pre-treatment ADC volumes of 26 LGG patients were used for
histogram-profiling. WHO-grade, Ki-67 expression, IDH mutation, and MGMT promotor
methylation status were evaluated. Comparative and correlative statistics investigating
the association between histogram-profiling and neuropathology were performed.
Results: Almost the entire ADC profile (p25, p75, p90, mean, median) was significantly
lower in grade II vs. grade I gliomas. Entropy, as second order histogram parameter
of ADC volumes, was significantly higher in grade II gliomas compared with grade I
gliomas. Mean, maximum value (ADCmax) and the percentiles p10, p75, and p90 of ADC
histogram were significantly correlated with Ki-67 expression. Furthermore, minimum
ADC value (ADCmin) was significantly associated with MGMT promotor methylation
status as well as ADC entropy with IDH-1 mutation status.
Conclusions: ADC histogram-profiling is a valuable radiomic approach, which helps
differentiating tumor grade, estimating growth kinetics and probably prognostic relevant
genetic as well as epigenetic alterations in LGG
Single-Center Experience With the Bare p48MW Low-Profile Flow Diverter and Its Hydrophilically Covered Version for Treatment of Bifurcation Aneurysms in Distal Segments of the Anterior and Posterior Circulation
Background and Purpose: Flow diversion has profoundly changed the way aneurysms
are treated. However, it conventionally requires dual antiplatelet medication and has yet
been considered off-label use in the posterior circulation or within peripheral vessels of the
anterior circulation. Here, we report our experience with the p48MW/p48MW hydrophilic
coating (HPC) in the anterior and posterior circulation. This novel low-profile flow diverter
is specifically designed for treatment of small peripheral vessels, and the p48MW HPC
has an anti-thrombotic polymer coating, which allows application of a single antiplatelet
function medication in conditions that expectably require further surgery.
Materials and Methods: Thirty-two patients were prospectively included. Twenty-six
treatments were performed with one flow diverter, four required two overlapping flow
diverters, one case demanded three overlapping flow diverters, and in one case,
extensive dissecting aneurysm telescoping with eight flow diverters was necessary.
Twenty-two complex bifurcation aneurysms were treated. Three months’ follow-up was
available for 14 patients.
Results: Deployment was uneventful in all cases. In four cases, undersizing was
unavoidable and resulted in significant shortening of the flow diverter, which demanded
implantation of further flow diverters to sufficiently treat the target aneurysm. Three
flow diverters required balloon angioplasty for optimal wall approximation. All parent
vessels remained patent. Available 3-month follow-up studies showed decreased influx
or delayed washout in all aneurysms; none was occluded completely. There were no
device-related clinical complications.
Conclusions: Implantation of the p48MW/p48MW HPC is safe and effective for
treatment of distally located cerebral aneurysms. Considering the reported rates of
ischemic complications associated with flow diversion of complex bifurcation aneurysms,
the p48MW/p48MW HPC potentially provides increased safety for complex bifurcation
aneurysms in the anterior and posterior circulation
Diffusion-weighted MRI reflects proliferative activity in primary CNS lymphoma
Purpose: To investigate if apparent diffusion coefficient (ADC) values within primary central nervous system lymphoma correlate with cellularity and proliferative activity in corresponding histological samples.
Materials and Methods: Echo-planar diffusion-weighted magnetic resonance images obtained from 21 patients with primary central nervous system lymphoma were reviewed retrospectively. Regions of interest were drawn on ADC maps corresponding to the contrast enhancing parts of the tumors. Biopsies from all 21 patients were histologically analyzed. Nuclei count, total nuclei area and average nuclei area were measured. The proliferation index was estimated as Ki-67 positive nuclei divided by total number of nuclei. Correlations of ADC values and histopathologic parameters were determined statistically. Results: Ki-67 staining revealed a statistically significant correlation with ADCmin (r = -0.454, p = 0.038), ADCmean (r = -0.546, p = 0.010) and ADCmax (r = -0.515, p = 0.017). Furthermore, ADCmean correlated in a statistically significant manner with total nucleic area (r = -0.500, p = 0.021). Conclusion: Low ADCmin, ADCmean and ADCmax values reflect a high proliferative activity of primary cental nervous system lymphoma. Low ADCmean values—in concordance with several
previously published studies—indicate an increased cellularity within the tumor
Nimodipine vs. Milrinone – Equal or Complementary Use? A Retrospective Analysis
Background: Cerebral vasospasm (CVS) continues to account for high morbidity and
mortality in patients surviving the initial aneurysmal subarachnoid hemorrhage (SAH).
Nimodipine is the only drug known to reduce delayed cerebral ischemia (DCI), but it
is believed not to affect large vessel CVS. Milrinone has emerged as a promising option.
Our retrospective study focused on the effectiveness of the intra-arterial application of
both drugs in monotherapy and combined therapy.
Methods: We searched for patients with aneurysmal SAH, angiographically confirmed
CVS, and at least one intra-arterial pharmacological angioplasty. Ten defined vessel
sections on angiograms were assessed before and after vasodilator infusion. The
improvement in vessel diameters was compared to the frequency of DCI-related cerebral
infarction before hospital discharge and functional outcome reported as the modified
Rankin Scale (mRS) score after 6 months.
Results: Between 2014 and 2021, 132 intra-arterial interventions (144 vascular
territories, 12 bilaterally) in 30 patients were analyzed for this study. The vasodilating
effect of nimodipine was superior to milrinone in all intradural segments. There was
no significant intergroup difference concerning outcome in mRS (p = 0.217). Only
nimodipine or the combined approach could prevent DCI-related infarction (both 57.1%),
not milrinone alone (87.5%). Both drugs induced a doubled vasopressor demand due to
blood pressure decrease, but milrinone alone induced tachycardia.
Conclusions: The monotherapy with intra-arterial nimodipine was superior to milrinone.
Nimodipine and milrinone may be used complementary in an escalation scheme with the
administration of nimodipine first, complemented by milrinone in cases of severe CVS.
Milrinone monotherapy is not recommended
Endovascular Treatment of Intracranial Aneurysms in Small Peripheral Vessel Segments—Efficacy and Intermediate Follow-Up Results of Flow Diversion With the Silk Vista Baby Low-Profile Flow Diverter
Background and Purpose: Low-profile flow diverter stents (FDS) quite recently
amended peripheral segments as targets for hemodynamic aneurysm treatment;
however, reports on outcomes, especially later than 3 months, are scarce. This study
therefore reports our experience with the novel silk vista baby (SVB) FDS and respective
outcomes after 8 and 11 months with special respect to specific adverse events.
Materials and Methods: Forty-four patients (mean age, 53 years) harboring 47
aneurysms treated with the SVB between June 2018 and December 2019 were included
in our study. Clinical, procedural, and angiographic data were collected. Follow-ups were
performed on average after 3, 8, and 11 months, respectively. Treatment effect was
assessed using the O’Kelly Marotta (OKM) grading system.
Results: Overall, angiographic follow-ups were available for 41 patients/45 aneurysms.
Occlusion or significant reduction in aneurysmal perfusion (OKM: D1, B1–B3 and
A2–A3) was observed in 98% of all aneurysms after 8 months. Only 2% of the treated
aneurysms remained morphologically unaltered and without an apparent change in
perfusion (OKM A1). Adverse events in the early post-interventional course occurred
in seven patients; out of them, mRS-relevant morbidity at 90 days related to FDS
treatment was observable in two patients. One death occurred in the context of
severe SAH related to an acutely ruptured dissecting aneurysm of the vertebral artery.
Conclusion: The SVB achieves sufficient occlusion rates of intracranial aneurysms
originating from peripheral segments, which are comparable to prior established
conventional FDS with acceptably low complication rates. However, alteration of a
hemodynamic equilibrium in distal localizations requires special attention to prevent
ischemic events
First Experience of Three Neurovascular Centers With the p64MW-HPC, a Low-Profile Flow Diverter Designed for Proximal Cerebral Vessels With Antithrombotic Coating
Background: In the last decade, flow diversion (FD) has been established as
hemodynamic treatment for cerebral aneurysms arising from proximal and distal cerebral
arteries. However, two significant limitations remain—the need for 0.027” microcatheters
required for delivery of most flow diverting stents (FDS), and long-term dual anti-platelet
therapy (DAPT) in order to prevent FDS-associated thromboembolism, at the cost
of increasing the risk for hemorrhage. This study reports the experience of three
neurovascular centers with the p64MW-HPC, a FDS with anti-thrombotic coating that
is implantable via a 0.021” microcatheter.
Materials and methods: Three neurovascular centers contributed to this retrospective
analysis of patients that had been treated with the p64MW-HPC between March 2020
and March 2021. Clinical data, aneurysm characteristics, and follow-up results, including
procedural and post-procedural complications, were recorded. The hemodynamic effect
was assessed using the O’Kelly–Marotta Scale (OKM).
Results: Thirty-two patients (22 female, mean age 57.1 years) with 33 aneurysms
(27 anterior circulation and six posterior circulation) were successfully treated with
the p64MW-HPC. In 30/32 patients (93.75%), aneurysmal perfusion was significantly
reduced immediately post implantation. Follow-up imaging was available for 23
aneurysms. Delayed aneurysm perfusion (OKM A3: 8.7%), reduction in aneurysm size
(OKM B1-3: 26.1%), or sufficient separation from the parent vessel (OKM C1-3 and
D1: 65.2%) was demonstrated at the last available follow-up after a mean of 5.9
months. In two cases, device thrombosis after early discontinuation of DAPT occurred.
One delayed rupture caused a caroticocavernous fistula. The complications were
treated sufficiently and all patients recovered without permanent significant morbidity.
Conclusion: Treatment with the p64MW-HPC is safe and feasible and achieves
good early aneurysm occlusion rates in the proximal intracranial circulation, which are
comparable to those of well-established FDS. Sudden interruption of DAPT in the
early post-interventional phase can cause in-stent thrombosis despite the HPC surface
modification. Deliverability via the 0.021” microcatheter facilitates treatment in challenging
vascular anatomies
CSF Surfactant Protein Changes in Preterm Infants After Intraventricular Hemorrhage
Introduction: Surfactant proteins (SP) have been shown to be inherent proteins of the
human CNS and are altered during acute and chronic disturbances of CSF circulation.
Aim of the study was to examine the changes of surfactant protein concentrations in CSF
of preterm babies suffering from intraventricular hemorrhage.
Patients and Methods: Consecutive CSF samples of 21 preterm infants with
intraventricular hemorrhages (IVH) and posthemorrhagic hydrocephalus (PHHC) were
collected at primary intervention, after 5–10 days and at time of shunt insertion 50
days after hemorrhage. Samples were analyzed for surfactant proteins A, B, C, and G by
ELISA assays and the results were compared to 35 hydrocephalus patients (HC) without
hemorrhage and 6 newborn control patients.
Results and Discussion: Premature patients with IVH showed a significant elevation
of surfactant proteins SP-A, C, and G compared to HC and control groups: mean
values for the respective groups were SP-A 4.19 vs. 1.08 vs. 0.38 ng/ml. Mean SP-C
3.63 vs. 1.47 vs. 0.48 ng/ml. Mean SP-G 3.86 vs. 0.17 vs. 0.2 ng/ml. SP-A and G
concentrations were slowly falling over time without reaching normal values. SP-C levels
declined faster following neurosurgical interventions and reached levels comparable to
those of hydrocephalus patients without hemorrhage.
Conclusion: Intraventricular hemorrhages of premature infants cause posthemorrhagic
CSF flow disturbance and are associated with highly significant elevations of surfactant
proteins A, C, and G independent of total CSF protein concentrations
Delayed Stroke after Aneurysm Treatment with Flow Diverters in Small Cerebral Vessels: A Potentially Critical Complication Caused by Subacute Vasospasm
Flow diversion (FD) is a novel endovascular technique based on the profound alteration
of cerebrovascular hemodynamics, which emerged as a promising minimally invasive therapy for
intracranial aneurysms. However, delayed post-procedural stroke remains an unexplained concern.
A consistent follow-up-regimen has not yet been defined, but is required urgently to clarify the
underlying cause of delayed ischemia. In the last two years, 223 patients were treated with six
different FD devices in our center. We identified subacute, FD-induced segmental vasospasm (SV) in
36 patients as a yet unknown, delayed-type reaction potentially compromising brain perfusion to a
critical level. Furthermore, 86% of all patients revealed significant SV approximately four weeks after
treatment. In addition, 56% had SV with 25% stenosis, and 80% had additional neointimal hyperplasia.
Only 13% exhibited SV-related high-grade stenosis. One of those suffered stroke due to prolonged
SV, requiring neurocritical care and repeated intra-arterial (i.a.) biochemical angioplasty for seven
days to prevent territorial infarction. Five patients suffered newly manifested, transient hemicrania
accompanying a compensatorily increased ipsilateral leptomeningeal perfusion. One treated vessel
obliterated permanently. Hence, FD-induced SV is a frequent vascular reaction after FD treatment,
potentially causing symptomatic ischemia or even stroke, approximately one month post procedure.
A specifically early follow-up-strategy must be applied to identify patients at risk for ischemia,
requiring intensified monitoring and potentially anti-vasospastic treatment
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