Is Histologic Thrombus Composition in Acute Stroke Linked to Stroke Etiology or to Interventional Parameters?

BACKGROUND AND PURPOSE: Detailed insight into the composition of thrombi retrieved from patients with ischemic stroke by mechanical thrombectomy might improve pathophysiologic understanding and therapy. Thus, this study searched for links between histologic thrombus composition and stroke subtypes and mechanical thrombectomy results. MATERIALS AND METHODS: Thrombi from 85 patients who had undergone mechanical thrombectomy for acute ischemic stroke between December 2016 and March 2018 were studied retrospectively. Thrombi were examined histologically. Preinterventional imaging features, stroke subtypes, and interventional parameters were re-analyzed. Statistical analysis was performed with the Kruskal-Wallis test, Mann-Whitney U test, or Spearman correlation as appropriate. RESULTS: Cardioembolic thrombi had a higher percentage of macrophages and a tendency toward more platelets than thrombi of large-artery atherosclerotic stenosis (P = .021 and .003) or the embolic stroke of undetermined source (P = .037 and .099) subtype. Thrombi prone to fragmentation required the combined use of contact aspiration and stent retrieval (P = .021) and were associated with an increased number of retrieving maneuvers (P = .001), longer procedural times (P = .001), and a higher lymphocyte content (P = .035). CONCLUSIONS: We interpreted the higher macrophage and platelet content in cardioembolic thrombi compared with large-artery atherosclerotic stenosis or embolic stroke of undetermined source thrombi as an indication that the latter type might be derived from an atherosclerotic plaque rather than from an undetermined cardiac source. The extent of thrombus fragmentation was associated with a more challenging mechanical thrombectomy and a higher lymphocyte content of the thrombi. Thus, thrombus fragmentation not only might be caused by the recanalization procedure but also might be a feature of a lymphocyte-rich, difficult-to-retrieve subgroup of thrombi.

Transdural Blood Supply in Cerebral Arteriovenous Malformations: A Systematic Evaluation of Angioarchitecture.

BACKGROUND AND PURPOSE: Arterial transdural blood supply is a rare angiographic phenomenon in cerebral AVMs. This study aimed to evaluate angiographic transdural blood supply characteristics and to describe the clinical peculiarities of these lesions. MATERIALS AND METHODS: A prospective AVM data base of 535 patients, enrolled from 1990 to 2016, was analyzed retrospectively. Clinical information was reviewed through patients' medical charts and radiologic studies. Patients with previous AVM treatment were excluded (n = 28). RESULTS: Patients with (n = 32, male/female ratio = 10:22; mean age, 46 ± 15 years; range, 13-75 years) and without transdural blood supply (n = 475, male/female ratio = 260:215; mean age, 40 ± 18 years; range, 2-87 years) did not show significant differences in clinical presentation (age, hemorrhage, seizures, chronic headache). The predominant nidus size in patients with transdural blood supply was ≥30 mm, with significantly more patients with large AVMs (>60 mm, P = .001). To describe the transdural blood supply, we used 3 grades based on the angiographic transdural blood supply proportion and intensity of AVM nidus perfusion (I-III). Fifty-seven percent of patients with chronic headache had a strong and substantial transdural nidus perfusion (III) and a high-flow transdural blood supply. CONCLUSIONS: Cerebral AVMs with transdural blood supply represent a rare and heterogeneous subgroup. Lesions can be graded by quantifying the transdural blood supply of the nidus and by capturing hemodynamic characteristics. The broad spread of angiographic features and comparable clinical patterns of patients with or without transdural blood supply raises questions about the relevance of the transdural blood supply to the natural history risk of an AVM and the intention for treatment.

11C-MET PET/MRI for detection of recurrent glioma.

INTRODUCTION: Radiological assessment of brain tumors is widely based on the Radiology Assessment of Neuro-Oncology (RANO) criteria that consider non-specific T1 and T2 weighted images. Limitation of the RANO criteria is that they do not include metabolic imaging techniques that have been reported to be helpful to differentiate treatment related changes from true tumor progression. In the current study, we assessed if the combined use of MRI and PET with hybrid 11C-MET PET/MRI can improve diagnostic accuracy and diagnostic confidence of the readers to differentiate treatment related changes from true progression in recurrent glioma. METHODS: Fifty consecutive patients with histopathologically proven glioma were prospectively enrolled for a hybrid 11C-MET PET/MRI to differentiate recurrent glioma from treatment induced changes. Sole MRI data were analyzed based on RANO. Sole PET data and in a third evaluation hybrid 11C-MET-PET/MRI data were assessed for metabolic respectively metabolic and morphologic glioma recurrence. Diagnostic performance and diagnostic confidence of the reader were calculated for the different modalities, and the McNemar test and Mann-Whitney U Test were applied for statistical analysis. RESULTS: Hybrid 11C-MET PET/MRI was successfully performed in all 50 patients. Glioma recurrence was diagnosed in 35 of the 50 patients (70%). Sensitivity and specificity were calculated for MRI (86.11% and 71.43%), for 11C-MET PET (96.77% and 73.68%), and for hybrid 11C-MET-PET/MRI (97.14% and 93.33%). For diagnostic accuracy hybrid 11C-MET-PET/MRI (96%) showed significantly higher values than MRI alone (82%), whereas no significant difference was found for 11C-MET PET (88%). Furthermore, by rating on a five-point Likert scale significantly higher scores were found for diagnostic confidence when comparing 11C-MET PET/MRI (4.26 ± 0,777) to either PET alone (3.44 ± 0.705) or MRI alone (3.56 ± 0.733). CONCLUSION: This feasibility study showed that hybrid PET/MRI might strengthen RANO classification by adding metabolic information to conventional MRI information. Future studies should evaluate the clinical utility of the combined use of 11C-MET PET/MRI in larger patient cohorts.

Posterior Reversible Encephalopathy Syndrome: The Spectrum of MR Imaging Patterns.

AIM: The aim of this study was to describe lesion patterns, distribution, and evolution in posterior reversible encephalopathy syndrome (PRES) in a larger single-center population. METHODS: Scans and follow-up, if available, of 50 patients with PRES between 2002 and 2011 were reviewed retrospectively. Lesion patterns, extent, and signal intensity changes were identified and graded on fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted images. Hemorrhagic changes were identified on T2* or susceptibility-weighted images, and gadolinium enhancement on T1-weighted images was identified if available. RESULTS: The most frequently affected regions on FLAIR were the frontal lobes in 54 %, occipital lobes in 34.3 %, and parietal lobes in 31.0 % of cases, thus 65.3 % in the posterior regions. Temporal lobes were affected in 10.6 %, the cerebellum in 6.5 %, and basal ganglia in 1.6 %. Division into vascular supply showed involvement in the anterior circulation in 66.5 % and in the posterior circulation in 33.5 % of cases. On diffusion-weighted imaging (DWI), vasogenic edema was observed in 6.9 %, cytotoxic edema in 9.1 %, and both in 2 % of cases. In 31.9 %, there was shine through, and in 15.9 %, there was shine through as well as cytotoxic or vasogenic edema. Topologic distribution on DWI showed affection of the frontal lobes in 43.5 %, occipital lobes in 25.8 %, parietal lobes in 17.7 %, temporal lobes in 11.3 %, and cerebellum in 1.6 %. T2* or susceptibility-weighted images showed spot-like hemosiderin accumulation in 17.2 % of cases. In 23.1 %, enhancement was seen. Follow-up magnetic resonance imaging showed complete resolution in 66.6 % of patients. CONCLUSION: The spectrum of imaging findings in PRES is wide. Almost always subcortical and cortical structures are involved. Although posterior changes are prominent in this syndrome, frontal involvement is more frequent than posterior on FLAIR imaging and DWI. On DWI, mixed patterns are not uncommon. Reversibility generally takes place independent of DWI pathology. Hypertension was not a prognostic factor.

Benefit of second catheter angiography in patients with nontraumatic subarachnoidal hemorrhage.

PURPOSE: This study aimed to determine the yield of repetitive catheter angiography (digital subtraction angiography (DSA)) for the detection of causative vascular lesions in patients with nontraumatic subarachnoidal hemorrhage (SAH) and negative initial DSA. We hypothesize that a second DSA might be helpful to detect an initially occult bleeding source. METHODS: We retrospectively evaluated 649 patients with acute SAH and invasive catheter angiographies between 2004 and 2012. In 90 SAH patients initial imaging was negative concerning a causative bleeding source. A total of 113 repetitive DSA were performed. Two neuroradiologists reanalyzed the initial imaging and the result of the reangiography independently. RESULTS: In 4/90 patients (4.5 %) bleeding source was first detected in the second or third DSA. In all other patients, no causative vascular lesion was found. Reasons for the initially false negative diagnostics were one dissecting aneurysm and thrombosis of three aneurysms within the acute phase of SAH. CONCLUSIONS: Repetitive DSA revealed the cause of SAH in 4.5 % of the cases. These findings have a therapeutic and prognostic impact. We think that at least a second DSA should be part of diagnostic work-up in patients with SAH and missing bleeding source, even considering the risk of an additional invasive angiography itself.

Silent embolism after stent-assisted coiling of cerebral aneurysms: diffusion-weighted MRI study of 75 cases.

PURPOSE: New ischemic brain lesions are common findings after cerebral diagnostic angiography and endovascular therapy. Diffusion-weighted MRI (DWI) can be used for detection of these lesions. The aim of the present study was to investigate the incidence of DWI lesions after stent-assisted coiling and the evaluation of possible risk factors. METHODS: The study included a total of 75 consecutive patients treated with stent-assisted coiling. Post-procedural DWI of the brain was performed to detect ischemic lesions. Demographic data, aneurysm characteristics and angiographic parameters were correlated with properties of DWI lesions. RESULTS: In post-procedural DWI, 48 of the 75 patients (64%) had 163 DWI lesions in a pattern consistent with embolic events. The number of patients with DWI lesions was significantly increased in older patients (≥55 years) and longer intervention times (≥120 min). The ischemic brain volume was significantly increased in older patients (≥55 years) as well as in patients who were implanted with a shorter stent (<20 mm). CONCLUSIONS: Thromboembolic events are common after stent-assisted coiling with an incidence comparable to DWI studies after coiling alone. Despite several devices and low operator experience, stent-assisted coiling for intracranial aneurysms has a very low risk of permanent neurologic disability. Further studies are necessary to improve the safety of stent-assisted coiling for patients in conditions with increased risk potential (age, procedure time, stent length).

[Reangiography after perimesencephalic subarachnoid hemorrhage]. / Reangiographie nach perimesenzephaler Subarachnoidalblutung.

BACKGROUND: This study aimed to determine the value of digital subtraction angiography (DSA) for the detection of causative vascular lesions in patients with perimesencephalic subarachnoid hemorrhage (SAH) after initially negative noninvasive and invasive neurovascular imaging, such as computed tomography angiography (CTA), DSA and magnetic resonance angiography (MRA). MATERIALS AND METHODS: We analyzed the value of repeated DSA for the detection of causative vascular lesions in 750 patients presenting to our institution with SAH and including 30 with a purely perimesencephalic pattern of subarachnoidal hemorrhage and initially negative noninvasive and invasive neurovascular imaging over a 10-year period. RESULTS: Repeated DSA demonstrated a causative vascular lesion in 1 patient (3.3%) but no causative vascular lesions were detected in the other patients. CONCLUSIONS: Repeated DSA can be used to detect a source of hemorrhage after initially negative imaging diagnostics in some rare cases. Such a finding has a therapeutic and prognostic impact especially for aneurysms in the posterior circulation which bear a higher risk of renewed hemorrhaging. Therefore, we believe that repeated DSA should be recommended in patients with perimesencephalic SAH even under consideration of the risk of complications caused by a second invasive DSA.