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Papaioannou VE, Budohoski KP, Placek MM, Czosnyka Z, Smielewski P, Czosnyka M. Association of transcranial Doppler blood flow velocity slow waves with delayed cerebral ischemia in patients suffering from subarachnoid hemorrhage: a retrospective study. Intensive Care Med Exp 2021; 9:11. [PMID: 33768351 PMCID: PMC7994457 DOI: 10.1186/s40635-021-00378-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 02/17/2021] [Indexed: 11/25/2022] Open
Abstract
Background Cerebral vasospasm (VS) and delayed cerebral ischemia (DCI) constitute major complications following subarachnoid hemorrhage (SAH). A few studies have examined the relationship between different indices of cerebrovascular dynamics with the occurrence of VS. However, their potential association with the development of DCI remains elusive. In this study, we investigated the pattern of changes of different transcranial Doppler (TCD)-derived indices of cerebrovascular dynamics during vasospasm in patients suffering from subarachnoid hemorrhage, dichotomized by the presence of delayed cerebral ischemia. Methods A retrospective analysis was performed using recordings from 32 SAH patients, diagnosed with VS. Patients were divided in two groups, depending on development of DCI. Magnitude of slow waves (SWs) of cerebral blood flow velocity (CBFV) was measured. Cerebral autoregulation was estimated using the moving correlation coefficient Mxa. Cerebral arterial time constant (tau) was expressed as the product of resistance and compliance. Complexity of CBFV was estimated through measurement of sample entropy (SampEn). Results In the whole population (N = 32), magnitude of SWs of ipsilateral to VS side CBFV was higher during vasospasm (4.15 ± 1.55 vs before: 2.86 ± 1.21 cm/s, p < 0.001). Ipsilateral SWs of CBFV before VS had higher magnitude in DCI group (N = 19, p < 0.001) and were strongly predictive of DCI, with area under the curve (AUC) = 0.745 (p = 0.02). Vasospasm caused a non-significant shortening of ipsilateral values of tau and increase in SampEn in all patients related to pre-VS measurements, as well as an insignificant increase of Mxa in DCI related to non-DCI group (N = 13). Conclusions In patients suffering from subarachnoid hemorrhage, TCD-detected VS was associated with higher ipsilateral CBFV SWs, related to pre-VS measurements. Higher CBFV SWs before VS were significantly predictive of delayed cerebral ischemia.
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Affiliation(s)
- Vasilios E Papaioannou
- Department of Intensive Care Medicine, Alexandroupolis Hospital, Democritus University of Thrace, 68100, Alexandoupolis, Greece. .,Academic Neurosurgery Unit, Brain Physics Lab, Addenbrooke's Hospital, Box 167, Cambridge, CB20QQ, UK.
| | - Karol P Budohoski
- Academic Neurosurgery Unit, Brain Physics Lab, Addenbrooke's Hospital, Box 167, Cambridge, CB20QQ, UK.,Department of Neurosurgery, Cambridge University Hospitals, Cambridge, CB20QQ, UK
| | - Michal M Placek
- Academic Neurosurgery Unit, Brain Physics Lab, Addenbrooke's Hospital, Box 167, Cambridge, CB20QQ, UK.,Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, 50-370, Wrocław, Poland
| | - Zofia Czosnyka
- Academic Neurosurgery Unit, Brain Physics Lab, Addenbrooke's Hospital, Box 167, Cambridge, CB20QQ, UK
| | - Peter Smielewski
- Academic Neurosurgery Unit, Brain Physics Lab, Addenbrooke's Hospital, Box 167, Cambridge, CB20QQ, UK
| | - Marek Czosnyka
- Academic Neurosurgery Unit, Brain Physics Lab, Addenbrooke's Hospital, Box 167, Cambridge, CB20QQ, UK
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Lin TS, Hsu PY, Chang CH, Ko CL, Kuo YM, Wu YW, Yen RF, Wu CH, Li KJ, Hsein YC, Hsieh SC. Increased heterogeneity of brain perfusion is an early marker of central nervous system involvement in antiphospholipid antibody carriers. PLoS One 2017; 12:e0182344. [PMID: 28763503 PMCID: PMC5538638 DOI: 10.1371/journal.pone.0182344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 07/17/2017] [Indexed: 01/10/2023] Open
Abstract
Objective The non-criteria neuropsychiatric manifestations of antiphospholipid syndrome include headache, dizziness, vertigo, seizure, depression and psychosis. There were still no objective methods qualified to detect the early central nervous system involvement in non-criteria antiphospholipid syndrome. We evaluated the effectiveness of Tc-99m ECD SPECT in assessing circulatory insufficiency in the brains of patients with antiphospholipid antibodies and neuropsychiatric symptoms but without thromboembolism. Materials and methods Patients with a history of positive antiphospholipid antibodies and neuropsychiatric symptoms composed the case group; patients without antiphospholipid antibody served as the control group. Subjects with a history of thromboembolism or autoantibodies to extractable nuclear antigens were excluded. All patients received Tc-99m ECD SPECT studies and were classified by the number of positive antiphospholipid antibodies they carried. The heterogeneity of brain perfusion was defined as the coefficient of variation of the SPECT signals. Analysis of variance (ANOVA) was applied to evaluate the differences between the groups. Results Total 60 adult patients were included in this study. There were 54 patients in the case group and 6 patients in the control group. The mean age was 38.3 ± 11.5 years. There were 52 women and 8 men. There was no significant difference in the mean brain perfusion between groups (P = 0.69). However, Tc-99m ECD SPECT demonstrated significant heterogeneity of brain perfusion in relation to the number of antiphospholipid antibodies (P = 0.01). Conclusions This is the first study demonstrating that Tc-99m ECD SPECT can early detect the increased heterogeneity of brain circulation in non-criteria antiphospholipid antibody carriers.
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Affiliation(s)
- Ting-Syuan Lin
- Department of Internal Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, Taiwan
- Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City, Taiwan
| | - Pei-Ying Hsu
- Department of Nuclear Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, Taiwan
- Department of Nuclear Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei City, Taiwan
| | - Chin-Hao Chang
- Department of Medical Research, National Taiwan University Hospital, Taipei City, Taiwan
| | - Chi-Lun Ko
- Department of Nuclear Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, Taiwan
- Department of Nuclear Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei City, Taiwan
| | - Yu-Min Kuo
- Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan
| | - Yen-Wen Wu
- Department of Nuclear Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei City, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan
- Cardiology Division of Cardiovascular Medical Center and Department of Nuclear Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Yang-Ming University School of Medicine, Taipei City, Taiwan
| | - Ruoh-Fang Yen
- Department of Nuclear Medicine, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei City, Taiwan
| | - Cheng-Han Wu
- Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan
| | - Ko-Jen Li
- Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan
| | - Yenh-Chen Hsein
- Department of Laboratory Medicine, National Taiwan University Hospital, Yun-Lin Branch, Yun-Lin, Taiwan
| | - Song-Chou Hsieh
- Department of Internal Medicine, National Taiwan University Hospital, Taipei City, Taiwan
- * E-mail:
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McConnell ED, Wei HS, Reitz KM, Kang H, Takano T, Vates GE, Nedergaard M. Cerebral microcirculatory failure after subarachnoid hemorrhage is reversed by hyaluronidase. J Cereb Blood Flow Metab 2016; 36:1537-52. [PMID: 26661183 PMCID: PMC5012515 DOI: 10.1177/0271678x15608389] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 06/17/2015] [Indexed: 11/15/2022]
Abstract
Aneurysmal subarachnoid hemorrhage remains one of the more devastating forms of stroke due in large part to delayed cerebral ischemia that appears days to weeks following the initial hemorrhage. Therapies exclusively targeting large caliber arterial vasospasm have fallen short, and thus we asked whether capillary dysfunction contributes to delayed cerebral ischemia after subarachnoid hemorrhage. Using a mouse model of subarachnoid hemorrhage and two-photon microscopy we showed capillary dysfunction unrelated to upstream arterial constriction. Subarachnoid hemorrhage decreased RBC velocity by 30%, decreased capillary pulsatility by 50%, and increased length of non-perfusing capillaries by 15%. This was accompanied by severe brain hypoxia and neuronal loss. Hyaluronidase, an enzyme that alters capillary blood flow by removing the luminal glycocalyx, returned RBC velocity and pulsatility to normal. Hyaluronidase also reversed brain hypoxia and prevented neuron loss typically seen after subarachnoid hemorrhage. Thus, subarachnoid hemorrhage causes specific changes in capillary RBC flow independent of arterial spasm, and hyaluronidase treatment that normalizes capillary blood flow can prevent brain hypoxia and injury after subarachnoid hemorrhage. Prevention or treatment of capillary dysfunction after subarachnoid hemorrhage may reduce the incidence or severity of subarachnoid hemorrhage-induced delayed cerebral ischemia.
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Affiliation(s)
- Evan D McConnell
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, University of Rochester Medical Center, Rochester, NY, USA Department of Neurological Surgery, University of Rochester Medical Center, Rochester, NY, USA
| | - Helen S Wei
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, University of Rochester Medical Center, Rochester, NY, USA Department of Neurological Surgery, University of Rochester Medical Center, Rochester, NY, USA
| | - Katherine M Reitz
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, University of Rochester Medical Center, Rochester, NY, USA Department of Neurological Surgery, University of Rochester Medical Center, Rochester, NY, USA
| | - Hongyi Kang
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, University of Rochester Medical Center, Rochester, NY, USA Department of Neurological Surgery, University of Rochester Medical Center, Rochester, NY, USA
| | - Takahiro Takano
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, University of Rochester Medical Center, Rochester, NY, USA Department of Neurological Surgery, University of Rochester Medical Center, Rochester, NY, USA
| | - G Edward Vates
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, University of Rochester Medical Center, Rochester, NY, USA Department of Neurological Surgery, University of Rochester Medical Center, Rochester, NY, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Division of Glial Disease and Therapeutics, University of Rochester Medical Center, Rochester, NY, USA Department of Neurological Surgery, University of Rochester Medical Center, Rochester, NY, USA
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Di Ieva A, Esteban FJ, Grizzi F, Klonowski W, Martín-Landrove M. Fractals in the Neurosciences, Part II. Neuroscientist 2015; 21:30-43. [PMID: 24362814 DOI: 10.1177/1073858413513928] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
It has been ascertained that the human brain is a complex system studied at multiple scales, from neurons and microcircuits to macronetworks. The brain is characterized by a hierarchical organization that gives rise to its highly topological and functional complexity. Over the last decades, fractal geometry has been shown as a universal tool for the analysis and quantification of the geometric complexity of natural objects, including the brain. The fractal dimension has been identified as a quantitative parameter for the evaluation of the roughness of neural structures, the estimation of time series, and the description of patterns, thus able to discriminate different states of the brain in its entire physiopathological spectrum. Fractal-based computational analyses have been applied to the neurosciences, particularly in the field of clinical neurosciences including neuroimaging and neuroradiology, neurology and neurosurgery, psychiatry and psychology, and neuro-oncology and neuropathology. After a review of the basic concepts of fractal analysis and its main applications to the basic neurosciences in part I of this series, here, we review the main applications of fractals to the clinical neurosciences for a holistic approach towards a fractal geometry model of the brain.
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Affiliation(s)
- Antonio Di Ieva
- Division of Neurosurgery, St. Michael’s Hospital, University of Toronto, Toronto, Canada
- Centre for Anatomy and Cell Biology, Department of Systematic Anatomy, Medical University of Vienna, Vienna, Austria
| | - Francisco J. Esteban
- Systems Biology Unit, Department of Experimental Biology, University of Jaén, Jaén, Spain
| | - Fabio Grizzi
- Humanitas Clinical and Research Center, Rozzano, Milan, Italy
| | - Wlodzimierz Klonowski
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Miguel Martín-Landrove
- Centre for Molecular and Medical Physics and National Institute for Bioengineering, Universidad Central de Venezuela, Caracas, Venezuela
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Kapinos G. Redefining secondary injury after subarachnoid hemorrhage in light of multimodal advanced neuroimaging, intracranial and transcranial neuromonitoring: beyond vasospasm. ACTA NEUROCHIRURGICA. SUPPLEMENT 2015; 120:259-267. [PMID: 25366634 DOI: 10.1007/978-3-319-04981-6_44] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The classic idea that arterial narrowing, called vasospasm (VSP), represents the hallmark of secondary injury after subarachnoid hemorrhage, has been challenged. The more complex and pleiotropic pathophysiological repercussions from the irruption of arterial blood into the subarachnoid layers go beyond the ascribed VSP. Putting adjectives in front of this term, such as "symptomatic," "microdialytic," or "angiographic" VSP, is misleading. Delayed cerebral ischemia (DCI) is a better term but remains restrictive to severe hypoperfusive injury and neglects oligemia, edema, and metabolic nonischemic injuries. In recognition of these issues, the international conference on VSP integrated "neurovascular events" into its name ( www.vasospasm2013.com ) and a multidisciplinary research group was formed in 2010 to study subgroups of DCI/VSP and their respective significance.In three parts, this tiered article provides a broader definitional envelope for DCI and secondary neurovascular insults after SAH, with a rubric for each subtype of delayed neuronal dysfunction. First, it pinpoints the need for nosologic precision and covers current terminological inconsistency. Then, it highlights the input of neuroimaging and neuromonitoring in defining secondary injurious processes. Finally, a new categorization of deteriorating patients is proposed, going beyond a hierarchical or dichotomized definition of VSP/DCI, and common data elements are suggested for future trials.
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Affiliation(s)
- Gregory Kapinos
- Department of Neurosurgery, North Shore-LIJ Health System, 300 Community Drive, Tower, 9th floor, Manhasset, NY, 11030, USA,
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Wang F, Yin YH, Jia F, Jiang JY. Effects of topical administration of nimodipine on cerebral blood flow following subarachnoid hemorrhage in pigs. J Neurotrauma 2013; 30:591-6. [PMID: 19558207 DOI: 10.1089/neu.2009.0890] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We sought to explore whether topical administration of nimodipine improves the abnormal cerebral perfusion following subarachnoid hemorrhage (SAH) in pigs. Fourteen pigs were randomly divided into three groups: sham (n=4), SAH (n=5), or SAH + nimodipine (n=5). The SAH model was established by injecting fresh autologous nonheparinized arterial blood into the suprasellae cistern. Nimodipine or saline placebo (0.04 g/mL) were administered to the operative area on the fourth day after the SAH model was established. The cerebral blood flow (CBF) was measured 60 min after topical administration of nimodipine by cranial SPECT/CT scans with 5 mCi 99mTc-ECD injected intravenously. The CCR (corticocebellar ratio) was calculated by dividing the counts/voxel of the whole cerebral hemisphere by the average count/voxel in the cerebellar region of reference and RD (relative dispersion). A predictor for impaired autoregulation of CBF was calculated by dividing standard deviation (SD) of regional perfusion by mean perfusion (RD=SD/Mean). CCR and RD were applied to describe hemisphere CBF and perfusion heterogeneity. Cerebral perfusion significantly decreased in the SAH group (CCR: 1.382±0.192, RD: 0.417±0.015) compared to sham (CCR: 1.988±0.346, RD 0.389±0.015) (p<0.05). Abnormal cerebral perfusion status, however, was not significantly improved in the nimodipine + SAH group (CCR: 1.503±0.107, RD: 0.425±0.018) compared to the SAH group (p>0.05). Topical administration of nimodipine did not significantly improve CBF following SAH. These findings were not consistent with our previous data demonstrating that the topical administration of nimodipine significantly alleviates cerebral vasospasm following SAH detected by TCD. Potential mechanisms governing these disparate outcomes require further investigation.
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Affiliation(s)
- Fei Wang
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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Fractal analysis in radiological and nuclear medicine perfusion imaging: a systematic review. Eur Radiol 2013; 24:60-9. [PMID: 23974703 DOI: 10.1007/s00330-013-2977-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 06/28/2013] [Accepted: 07/05/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVES To provide an overview of recent research in fractal analysis of tissue perfusion imaging, using standard radiological and nuclear medicine imaging techniques including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) and single-photon emission computed tomography (SPECT) and to discuss implications for different fields of application. METHODS A systematic review of fractal analysis for tissue perfusion imaging was performed by searching the databases MEDLINE (via PubMed), EMBASE (via Ovid) and ISI Web of Science. RESULTS Thirty-seven eligible studies were identified. Fractal analysis was performed on perfusion imaging of tumours, lung, myocardium, kidney, skeletal muscle and cerebral diseases. Clinically, different aspects of tumour perfusion and cerebral diseases were successfully evaluated including detection and classification. In physiological settings, it was shown that perfusion under different conditions and in various organs can be properly described using fractal analysis. CONCLUSIONS Fractal analysis is a suitable method for quantifying heterogeneity from radiological and nuclear medicine perfusion images under a variety of conditions and in different organs. Further research is required to exploit physiologically proven fractal behaviour in the clinical setting. KEY POINTS • Fractal analysis of perfusion images can be successfully performed. • Tumour, pulmonary, myocardial, renal, skeletal muscle and cerebral perfusion have already been examined. • Clinical applications of fractal analysis include tumour and brain perfusion assessment. • Fractal analysis is a suitable method for quantifying perfusion heterogeneity. • Fractal analysis requires further research concerning the development of clinical applications.
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Modzelewski R, Janvresse E, de la Rue T, Vera P. Comparison of heterogeneity quantification algorithms for brain SPECT perfusion images. EJNMMI Res 2012; 2:40. [PMID: 22818866 PMCID: PMC3508867 DOI: 10.1186/2191-219x-2-40] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 06/18/2012] [Indexed: 11/21/2022] Open
Abstract
Background Several algorithms from the literature were compared with the original random walk (RW) algorithm for brain perfusion heterogeneity quantification purposes. Algorithms are compared on a set of 210 brain single photon emission computed tomography (SPECT) simulations and 40 patient exams. Methods Five algorithms were tested on numerical phantoms. The numerical anthropomorphic Zubal head phantom was used to generate 42 (6 × 7) different brain SPECT simulations. Seven diffuse cortical heterogeneity levels were simulated with an adjustable Gaussian noise function and six focal perfusion defect levels with temporoparietal (TP) defects. The phantoms were successively projected and smoothed with Gaussian kernel with full width at half maximum (FWHM = 5 mm), and Poisson noise was added to the 64 projections. For each simulation, 5 Poisson noise realizations were performed yielding a total of 210 datasets. The SPECT images were reconstructed using filtered black projection (Hamming filter: α = 0.5). The five algorithms or measures tested were the following: the coefficient of variation, the entropy and local entropy, fractal dimension (FD) (box counting and Fourier power spectrum methods), the gray-level co-occurrence matrix (GLCM), and the new RW. The heterogeneity discrimination power was obtained with a linear regression for each algorithm. This regression line is a mean function of the measure of heterogeneity compared to the different diffuse heterogeneity and focal defect levels generated in the phantoms. A greater slope denotes a larger separation between the levels of diffuse heterogeneity. The five algorithms were computed using 40 99mTc-ethyl-cysteinate-dimer (ECD) SPECT images of patients referred for memory impairment. Scans were blindly ranked by two physicians according to the level of heterogeneity, and a consensus was obtained. The rankings obtained by the algorithms were compared with the physicians' consensus ranking. Results The GLCM method (slope = 58.5), the fractal dimension (35.9), and the RW method (31.6) can differentiate the different levels of diffuse heterogeneity. The GLCM contrast parameter method is not influenced by a focal defect contrary to the FD and RW methods. A significant correlation was found between the RW method and the physicians' classification (r = 0.86; F = 137; p < 0.0001). Conclusions The GLCM method can quantify the different levels of diffuse heterogeneity in brain-simulated SPECT images without an influence from the focal cortical defects. However, GLCM classification was not correlated with the physicians' classification (Rho = −0.099). The RW method was significantly correlated with the physicians' heterogeneity perception but is influenced by the existence of a focal defect.
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Affiliation(s)
- Romain Modzelewski
- Laboratoire d'Informatique, de Traitement de l'Information et des Systemes (EA-LITIS 4108), QUANT, I, F, (Quantification en Imagerie Fonctionnelle, Faculty of Medicine, Rouen University, Saint Etienne du Rouvray, 76801, France.
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Kaya E, Öztürk F. Evaluation of Regional Brain Perfusion in Patients with Pseudoexfoliation Syndrome. Neuroophthalmology 2011. [DOI: 10.3109/01658107.2011.609287] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Modzelewski R, Janvresse E, de la Rue T, Vera P. Brain perfusion heterogeneity measurement based on Random Walk algorithm: choice and influence of inner parameters. Comput Med Imaging Graph 2009; 34:289-97. [PMID: 20036513 DOI: 10.1016/j.compmedimag.2009.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 09/09/2009] [Accepted: 11/30/2009] [Indexed: 11/25/2022]
Abstract
UNLABELLED A Random Walk (RW) algorithm was designed to quantify the level of diffuse heterogeneous perfusion in brain SPECT images in patients suffering from systemic brain disease or from drug-induced therapy. The goal of the present paper is to understand the behavior of the RW method on different kinds of images (extrinsic parameters) and also to understand how to choose the right parameters of the RW (intrinsic parameters) depending on the image characteristics (i.e. SPECT images). "Extrinsic parameters" are related to the image characteristics (level/size of defect and diffuse heterogeneity) and "intrinsic" parameters are related to the parameters of the method (number (N(rw)) and length of walk (L(rw)), temperature (T) and slowing parameter (S)). Two successive studies were conducted to test the influence of these parameters on the RW result. In the first study, calibrated checkerboard images are used to test the influence of "extrinsic parameters" (i.e. image characteristics) on the RW result (R-value). The R-value was tested as a function of (i) the size of black & white (B&W) squares simulating the size of a cortical defect, (ii) the intensity level gaps between the B&W squares simulating the intensity of the cortical defect and (iii) intensity (=variance) of noise, simulating the diffuse heterogeneity. The second study was constructed with simulated representative brain SPECT images, to test the "intrinsic" parameters. The R-value was tested regarding the influence of four parameters: S, T, N(rw) and L(rw). The third study is constructed so as to see if the classification by diffuse heterogeneity of real brain SPECT images is the same if it's made by senior clinicians or by RW algorithm. RESULTS Study 1: the RW was strongly influenced by all the characteristics of the images. Moreover, these characteristics interact with each other. The RW is influenced most by diffuse heterogeneity, then by intensity and finally by the size of a defect. Study 2: N(rw) and L(rw) values of 1000 give an optimal reproducibility of the measurement (mean standard deviation<0.1), a fast computation time (time<0.5s/image) and have a maximum difference in terms of R-value between the two extreme images corresponding to the range of the population studied. The best S and T values for SPECT images are 3 and 15, respectively. Study 3: A significant correlation was found between RW ranking and the physicians' consensus (rho=0.789; p<0.0001). CONCLUSION This study confirms that the RW method is able to measure the heterogeneity of brain SPECT images even in the presence of a large defect. However, the result of the method is strongly influenced by the "intrinsic" parameters, so the program should be calibrated for each different type of image.
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Affiliation(s)
- Romain Modzelewski
- QUANT.I.F. (Quantification en Imagerie Fonctionnelle) Team, LITIS Laboratory EA-CNRS 4018, Faculty of Medicine, Rouen University, 1, rue d'amiens, Rouen, France.
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Whiting J, Reavey-Cantwell J, Velat G, Fautheree G, Firment C, Lewis S, Hoh B. Clinical course of nontraumatic, nonaneurysmal subarachnoid hemorrhage: a single-institution experience. Neurosurg Focus 2009; 26:E21. [DOI: 10.3171/2009.2.focus092] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Angiogram-negative subarachnoid hemorrhage (SAH) accounts for 15% of nontraumatic SAH and has been reported with low morbidity and mortality rates. We report on a large series of patients with angiogram-negative SAH who experienced an atypical nonbenign clinical course.
Methods
Between December 2001 and November 2006, 95 patients with spontaneous nonaneurysmal SAH and negative initial angiographic evaluation were treated at the University of Florida. The authors retrospectively reviewed the patients' medical records and radiological images to determine associated morbidity and mortality.
Results
Aneurysms were found in 6 of the 95 patients on follow-up imaging after an initial negative angiogram (6.3% false negative rate); these patients were excluded leaving 89 patients as the study group. Hydrocephalus necessitating temporary CSF diversion developed in 22 of these patients (25%); 12 (13%) ultimately required permanent CSF diversion. Clinically significant vasospasm developed in 4 patients (4%), and 2 (2%) had cerebral infarctions. Three patients (3%) died.
Conclusions
The authors' experience with a large series of angiogram-negative SAH patients who had an atypical nonbenign clinical course associated with hydrocephalus, vasospasm, stroke, and mortality differs significantly from previously published case series of angiogram-negative SAH.
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Panerai RB. Complexity of the human cerebral circulation. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:1319-1336. [PMID: 19324711 DOI: 10.1098/rsta.2008.0264] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The cerebral circulation shows both structural and functional complexity. For time scales of a few minutes or more, cerebral blood flow (CBF) and other cerebrovascular parameters can be shown to follow a random fractal point process. Some studies, but not all, have also concluded that CBF is non-stationary. System identification techniques have been able to explain a substantial fraction of the CBF variability by applying linear and nonlinear multivariate models with classical determinants of flow (arterial blood pressure, arterial CO(2) and cerebrovascular resistance, CVR) as inputs. These findings raise the hypothesis that fractal behaviour is not inherent to CBF but might be simply transmitted from its determinants. If this is the case, future investigations could focus on the complexity of the residuals or the unexplained variance of CBF. In the low-frequency range (below 0.15 Hz), changes in CVR due to pressure and metabolic autoregulation represent an important contribution to CBF variability. A small body of work suggests that parameters describing cerebral autoregulation can also display complexity, presenting significant variability that might also be non-stationary. Fractal analysis, entropy and other nonlinear techniques have a role to play to shed light on the complexity of cerebral autoregulation.
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Affiliation(s)
- Ronney B Panerai
- Medical Physics Group, Department of Cardiovascular Sciences, University of Leicester, Leicester LE1 5WW, UK.
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Acute effect of intranasal estrogen on cerebral and cerebellar perfusion in postmenopausal women. Maturitas 2008; 59:72-82. [DOI: 10.1016/j.maturitas.2007.10.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Revised: 10/05/2007] [Accepted: 10/09/2007] [Indexed: 11/21/2022]
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