Gregor Richter

Flat-panel detector volumetric CT for visualization of subarachnoid hemorrhage and ventricles: preliminary results compared to conventional CT

IntroductionThe aim of this study was to compare flat-panel volumetric CT (VCT) to conventional CT (cCT) in the visualization of the extent of subarachnoid hemorrhage (SAH) and the width of the ventricles in patients with acute SAH.MethodsIncluded in the study were 22 patients with an acutely ruptured cerebral aneurysm who received VCT during coil embolization. VCT image quality, the extent of SAH (using a modified Fisher score and total slice number with SAH visible) and the width of the ventricles (Evans index) were evaluated by two experienced neuroradiologists (RAD1 and RAD2) and compared to the findings on cCT. Ten patients undergoing VCT for reasons other than SAH served as negative controls.ResultsInterobserver agreement in rating image quality was excellent for cCT (Kendall W value 0.94) and good for VCT (0.74). SAH was identified by RAD1 and RAD2 on VCT images in all patients. The modified Fisher scores underestimated the extent of SAH on VCT images in comparison with cCT images. Pearson’s correlation coefficient (r) regarding the number of image slices with SAH visible on cCT images compared with the number on VCT images was 0.85 for RAD1 and 0.84 for RAD2. The r value for the degree of interobserver agreement for the number of slices with SAH visible was 0.99 for cCT, and 0.95 for VCT images (n = 19), respectively. The width of the ventricles measured in terms of the Evans Index showed excellent concordance between the modalities (r = 0.81 vs. 0.82).ConclusionOur preliminary results indicate that VCT is helpful in evaluating SAH in the angiography suite. Additionally, reliable evaluation of ventricle width is feasible. However, there are limitations with regard to the visibility of SAH on VCT images in comparison to cCT images.

Visualisation of intracerebral haemorrhage with flat-detector CT compared to multislice CT: results in 44 cases

The aim of the study was to test the reliability of intracerebral haemorrhage (ICH) detection with C-arm-mounted flat-detector computed tomography (FD-CT) in the angio suite as compared to multislice CT (MSCT). In this study 44 patients with 45 ICH were included. All patients were investigated with MSCT and FD-CT during angiographic evaluation. As a control group we included 16 patients without ICH. In each haematoma we assessed volumetric data of the ICH and counted the numbers of ICH-positive slices. Using interobserver ratings, we additionally investigated the potential of FD-CT to serve as a diagnostic tool to detect ICH. In FD-CT three haematomas were not detected because of motion and beam-hardening artefacts in the region close to the skull base. The r value for the degree of interobserver agreement for the number of slices was 0.95 for MSCT and 0.94 for FD-CT. Measurements of the area and the calculated volume of the ICH showed high inter- and intraobserver agreement. Our results indicate that FD-CT is a helpful tool in the daily emergency management of ICH patients as detection of ICH was found to be nearly as reliable as in MSCT. Limitations of this technology are motion and beam-hardening artefacts that may mask small haematomas located in the posterior fossa or the skull base.

Early Administration of Low Molecular Weight Heparin after Spontaneous Intracerebral Hemorrhage

Background: Venous thromboembolism (VTE) is a common complication after stroke. Application of low molecular weight heparins (LMWH) has been proven to be beneficial for the prevention of VTE in ischemic stroke patients. However, there is no consensus whether and how to administer LMWH for prevention of thrombotic complications after acute spontaneous intracerebral hemorrhage (sICH), the main concern being possible hematoma growth. The objective of this study was to assess the safety of early subcutaneous LMWH in patients with sICH with respect to hemorrhage enlargement. Methods: A total of 97 patients with sICH were analyzed. LMWH (either enoxaparin-natrium or dalteparin-natrium) were initiated within 36 h after admission in all patients without clinical evidence of hemorrhage enlargement or an absence of evidence of hematoma growth on CT. Hematoma growth (significant when >33%, moderate when >20%) was assessed on follow-up CT between days 5 and 11. Results: None of the patients showed a significant hemorrhage growth. Between days 2 and 10, 2 patients experienced a moderate hematoma enlargement of 22.4 and 20.9%. None of the included patients developed a fatal lung embolism. Conclusions: Early application of subcutaneous LMWH for prevention of venous thromboembolism seems to be safe, and probably does not increase the risk of hematoma growth in patients with sICH.

Noninvasive Angiography (Magnetic Resonance and Computed Tomography) in the Diagnosis of Ischemic Cerebrovascular Disease

Noninvasive diagnostic imaging of the craniocervical and intracranial vasculature is a domain of computed tomography angiography (CTA), magnetic resonance angiography (MRA) and Doppler/duplex ultrasound, the latter not being the topic of this presentation. We give a methodological background for both, CTA and MRA, followed by a critical appraisal of both imaging modalities in the diagnosis of ischemic cerebrovascular disease. The contribution of noninvasive vascular imaging to vascular malformations (including aneurysms, fistulas and cerebral-vein thrombosis) is beyond the scope of this paper and therefore not covered.

Fluid flow simulation on the Cell Broadband Engine using the lattice Boltzmann method

In this paper we present a fast lattice Boltzmann fluid solver that has been performance optimized and tailored for the Cell Broadband Engine Architecture. Many design decisions were motivated by the long range objective to simulate blood flow in human blood vessels, especially in aneurysms, but have proven to be much more generally applicable. After explaining implementation details and how they were influenced by the target platform, the performance and memory requirements of this prototype solver are evaluated.

Myelography using flat panel volumetric computed tomography: a comparative study in patients with lumbar spinal stenosis.

Study Design. The technical feasibility of flat panel volumetric computed tomography (FPVCT) for lumbar myelographic imaging was evaluated in 20 patients and compared with multisclice computed tomography (MSCT). Objective. The purpose of this study was to determine the feasibility and sensitivity of FPVCT for myelographic imaging in lumbar spinal stenosis. Summary and Background Data. In the diagnosis of spinal stenosis, myelography and myelo-computed tomography (PCT) have been performed routinely for nearly 30 years. Rotational angiography is a new technique initially developed to visualize vessels but also allowing multiplanar reconstructed (MPR) CT images. The spatial resolution of FPCVT is even higher than in current MSCT. To date, this technique has not been evaluated for use in myelography. Methods. In 20 patients referred for CT for evaluation of low back pain, lumbar myelography was performed on a biplane angiography system equipped with flat panel detectors. FPVCT was provided from a volume data set out of a rotational acquisition and compared with MSCT performed on a 4-slice CT scanner. Hereby, for a total of 100 disc levels (range from L1–L2 to L5–S1), the narrowest dural cross-sectional diameter (D-CSD) and the dural cross-sectional area (D-CSA) referred to MSCT and FPVCT were calculated. Results. Mean D-CSD and C-CSA for all disc levels as measured by MSCT was 9.26 ± 3.0 mm and 63.2 ± 10.8 mm2, respectively. Compared with D-CSD and C-CSA measured by FPVCT, there was no statistically significant difference (9.48 ± 2.9 mm and 64.7 ± 11.2 mm2, respectively; P > 0.89). The most pronounced lumbar spinal stenosis was seen on L4/5 level with D-CSD of 6.6 ± 3.6 mm and 6.8 ± 3.2 mm and D-CSA of 53.7 ± 14.7 mm2 and 55.0 ± 14.3 mm2, respectively. Conclusion. In all patients, the diagnostic quality of the reconstructed FPVCT slice images is comparable to those acquired by MSCT. Using FPVCT, radiographic myelography and postmyelographic computed tomography can be performed with less radiation in a single session at the same imaging system.

Clinical severity predicts time to hospital admission in patients with spontaneous intracerebral hemorrhage.

Background: In this study we analyzed whether demographic, clinical and neuroradiological parameters are associated with time to hospital admission in patients with spontaneous intracerebral hemorrhage (ICH). We a priori hypothesized that the earlier a patient was admitted to hospital, the worse the clinical status would be. Methods: Demographic, clinical and neuroradiological parameters of consecutive patients with spontaneous ICH directly admitted to 2 neurological university departments were subjected to correlation, trichotomization and logistic regression analyses for prediction of (i) early hospital admission, and (ii) favorable clinical presentation at admission [dichotomized Glasgow Coma Scale (GCS) score ≧9]. Results: We analyzed 157 patients with a median age of 66 (39–93) years. Patient trichotomization according to the GCS revealed a significant difference (p < 0.001) between all groups with regard to the time from symptom onset to hospital admission: patients with a GCS score of 3–5 were admitted after 105 (40–300) min (mean: 113 ± 53), those with a GCS score of 6–9 after 180 (45–420) min (mean: 184 ± 95) and those with a GCS score of 10–15 after 300 (60–1,560) min (mean: 324 ± 367). There were significant correlations between (i) hematoma volume and GCS (r = –0.632; p < 0.001); (ii) time to admission and GCS (r = 0.596; p < 0.001), and (iii) Graeb scores for intraventricular hemorrhage and hematoma volume (r = 0.348; p < 0.001). In the multivariate regression model for prediction of time until hospital admission, presence of intraventricular hemorrhage and the GCS score on admission were significant. In the multivariate regression model for prediction of a GCS score of ≧9 on admission, hematoma volume and time until hospital admission were significant parameters. Conclusions: Clinically more severely affected patients were admitted to hospital earlier. This highlights the importance of most rapid diagnosis of ICH. Efforts should be made to get less severely affected patients admitted earlier as they might be ideal candidates for emerging innovative treatments.

Proton magnetic resonance spectroscopy in pituitary macroadenomas: preliminary results

OBJECT The aim of this study was to correlate proton MR (1H-MR) spectroscopy data with histopathological and surgical findings of proliferation and hemorrhage in pituitary macroadenomas. METHODS Quantitative 1H-MR spectroscopy was performed on a 1.5-T unit in 37 patients with pituitary macroadenomas. A point-resolved spectroscopy sequence (TR 2000 msec, TE 135 msec) with 128 averages and chemical shift selective pulses for water suppression was used. Voxel dimensions were adapted to ensure that the volume of interest was fully located within the lesion and to obtain optimal homogeneity of the magnetic field. In addition, water-unsuppressed spectra (16 averages) were acquired from the same volume of interest for eddy current correction, absolute quantification of metabolite signals, and determination of full width at half maximum of the unsuppressed water peak (FWHM water). Metabolite concentrations of choline-containing compounds (Cho) were computed using the LCModel program and correlated with MIB-1 as a proliferative cell index from a tissue specimen. RESULTS In 16 patients harboring macroadenomas without hemorrhage, there was a strong positive linear correlation between metabolite concentrations of Cho and the MIB-1 proliferative cell index (R = 0.819, p < 0.001). The metabolite concentrations of Cho ranged from 1.8 to 5.2 mM, and the FWHM water was 4.4-11.7 Hz. Eleven patients had a hemorrhagic adenoma and showed no assignable metabolite concentration of Cho, and the FWHM water was 13.4-24.4 Hz. In 10 patients the size of the lesion was too small (< 20 mm in 2 directions) for the acquisition of MR spectroscopy data. CONCLUSIONS Quantitative 1H-MR spectroscopy provided important information on the proliferative potential and hemorrhaging of pituitary macroadenomas. These data may be useful for noninvasive structural monitoring of pituitary macroadenomas. Differences in the FWHM water could be explained by iron ions of hemosiderin, which lead to worsened homogeneity of the magnetic field.

Treatment of intraventricular hemorrhage and hydrocephalus

Most cases of intraventricular hemorrhage (IVH) occur secondary to spontaneous intracerebral or subarachnoid hemorrhage. The main concern is development of hydrocephalus, which is related to a poor prognosis. Over the last years, several treatment options for IVH have been introduced, but prospective data regarding the efficacy of those therapies (external ventricular drainage, intraventricular fibrinolysis, lumbar drainage, endoscopic hematoma evacuation) do not yet exist. This review focuses on combined therapy using an external ventricular drain and intraventricular fibrinolysis with r-TPA for IVH-associated initial occlusive hydrocephalus. Moreover, a continuing treatment strategy for persistent malresorptive communicating hydrocephalus using lumbar drainage is described.ZusammenfassungDie intraventrikuläre Blutung (IVB) – meist sekundär im Anschluss an eine spontane intrazerebrale Blutung oder Subarachnoidalblutung – birgt als Hauptgefahr die Entwicklung eines Hydrozephalus, der mit einer schlechten Prognose assoziiert ist. In den letzten Jahren sind verschiedene Therapieoptionen zur Akutbehandlung der IVB beschrieben worden, jedoch basiert bislang kein Therapieansatz auf prospektiven Studien. Diese Übersichtsarbeit stellt die einzelnen Therapiemöglichkeiten der IVB vor, einschließlich der externen Ventrikeldrainage (EVD), der intraventrikulären Fibrinolyse, der Lumbaldrainage und der neuroendoskopischen Verfahren. Schwerpunkt wird die Darstellung der kombinierten Behandlung des – sich aufgrund intraventrikulärer Blutanteile entwickelnden – initialen okklusiven Hydrozephalus mittels einer EVD und der intraventrikulären Fibrinolyse mit rt-PA sein sowie die Erläuterung der weiterführenden Therapie des malresorptiven, kommunizierenden Hydrozephalus mittels Lumbaldrainage.SummaryMost cases of intraventricular hemorrhage (IVH) occur secondary to spontaneous intracerebral or subarachnoid hemorrhage. The main concern is development of hydrocephalus, which is related to a poor prognosis. Over the last years, several treatment options for IVH have been introduced, but prospective data regarding the efficacy of those therapies (external ventricular drainage, intraventricular fibrinolysis, lumbar drainage, endoscopic hematoma evacuation) do not yet exist. This review focuses on combined therapy using an external ventricular drain and intraventricular fibrinolysis with r-TPA for IVH-associated initial occlusive hydrocephalus. Moreover, a continuative treatment strategy for persistent malresorptive communicating hydrocephalus using lumbar drainage is described.

Technical feasibility of 2D–3D coregistration for visualization of self-expandable microstents to facilitate coil embolization of broad-based intracranial aneurysms: an in vitro study

IntroductionThe use of self-expandable microstents for treatment of broad-based intracranial aneurysms is widely spread. However, poor fluoroscopic visibility of the stents remains disadvantageous during the coiling procedure. Flat detector angiographic computed tomography (ACT) provides high resolution imaging of microstents even though integration of this imaging modality in the neurointerventional workflow has not been widely reported.MethodsAn acrylic glass model was used to simulate the situation of a broad-based sidewall aneurysm. After insertion of a self-expandable microstent, ACT was performed. The resulting 3D dataset of the Microstent was subsequently projected into a conventional 2D fluoroscopic roadmap. This 3D visualization of the stent supported the coil embolization procedure of the in vitro aneurysm.ResultsIn vitro 2D–3D coregistration with integration of 3D ACT data of a self-expandable microstent in a conventional 2D roadmap is feasible.ConclusionsUnsatisfying stent visibility constrains clinical cases with complex parent vessel anatomy and challenging aneurysm geometry; hence, this technique potentially may be useful in such cases. In our opinion, the clinical feasibility and utility of this new technique should be verified in a clinical aneurysm embolization study series using 2D–3D coregistration.