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RESCUING the ISCHEMIC PENUMBRA — OUR EXPIRIENCE 125 from January 2010 to October 2012

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RESCUING the ISCHEMIC PENUMBRA — OUR EXPIRIENCE 125 from January 2010 to October 2012 2013; 8(2): 123–130 UDK: 616.831-005-085.273 ISSN-1452-662X Originalni nau~ni rad RESCUING THE ISCHEMIC PENUMBRA— OUR EXPIRIENCE Milosavljevic Tamara,1 Ivkovic Aleksandar2 1 Special Hospital Niroshi, Nis, Serbia 2 Center of Radiology, Klinical Center Nis, Serbia Primljen/Received 31. 05. 2013. god. Prihva}en/Accepted 13. 11. 2013. god. Abstract: Objectives: Over one million strokes mia (lack of blood flow) caused by blockage (thrombo- per year are occurring in Europe. Brain stroke is one of sis, arterial embolism) or a hemorrhage (1).As a result, the most important death and disability causes in Europe the affected area of the brain cannot function, which and USA. The main role of perfusion is to determine the might result in an inability to move one or more limbs border of insult core and ischemic penumbra. Penumbra on one side of the body, inability to understand or for- can be saved with thrombolytic therapy but core have ir- mulate speech, or an inability to see one side of the vi- reversible injuries and represent death of brain cells. sual field (2). Aim: to determine the role of CT brain perfusion A stroke is a medical emergency and can cause in cases of acute brain stroke and following thrombo- permanent neurological damage and death. Risk fac- lytic therapy. tors for stroke include old age, high blood pressure, Methods: We examined 64 patients with acute previous stroke or transient ischemic attack (TIA), dia- brain stroke who received thrombolytic therapy after betes, high cholesterol, tobacco smoking and atrial fi- that. All patients were examining on 16 MDCT with 50 brillation (2). High blood pressure is the most impor- ml of iodine contrast agent following the standard pro- tant modifiable risk factor of stroke (2). It is the second cedure for CT perfusion. Patients were 34 male and 30 leading cause of death worldwide (3). An ischemic female with middle age of 64 years. MRI was made af- stroke is occasionally treated in a hospital with throm- ter thrombolytic therapy and compare with perfusion bolysis (also known as a “clot buster”), and some hem- results before therapy. orrhagic strokes benefit from neurosurgery. Treatment Results: Using an artery and a vein as reference to recover any lost function is termed stroke rehabilita- three parameters were measured — blood flow (CBF), tion, ideally in a stroke unit and involving health pro- blood volume (CBV) and mean transit time (MTT), for fessions such as speech and language therapy, physical each patient. Hemorrhagic was find in 9 (14.01%) pati- therapy and occupational therapy. Prevention of recur- ents after thrombolytic therapy. 4 (6.25%) other patients rence may involve the administration of antiplatelet develop new stroke of same but mostly other side of drugs such as aspirin and dipyridamole, control and re- brain. 8 (12.50%) more patients finished lethally. From duction of high blood pressure, and the use of statins. other 42 patients with thrombolytic therapy we can posi- Selected patients may benefit from carotid endarterec- tively say that in 31 (48.44%) patients penumbra was re- tomy and the use of anticoagulants (2). Strokes can be scued. For other 11 (17.19%) stroke was same size like classified into two major categories: ischemic and he- firstly involved core and penumbra but not bigger. morrhagic (4). Ischemic strokes are those that are cau- Conclusion: CT perfusion plays major role by sed by interruption of the blood supply, while hemorr- showing a curable parts of tissue in brain strokes. hagic strokes are the ones which result from rupture of Key worlds: penumbra, ischemia, CT perfusion, a blood vessel or an abnormal vascular structure. Abo- stroke. ut 87% of strokes are caused by ischemia and the rema- inder by hemorrhage. Some hemorrhages develop insi- INTRODUCTION de areas of ischemia (“hemorrhagic transformation”). A stroke, or cerebrovascular accident (CVA), is It is unknown how many hemorrhages actually start as the rapid loss of brain function due to disturbance in ischemic stroke (2). In an ischemic stroke, blood sup- the blood supply to the brain. This can be due to ische- ply to part of the brain is decreased, leading to dysfunc- 124 Milosavljevic Tamara, Ivkovic Aleksandar tion of the brain tissue in that area. There are four rea- imaging. The brain is continuously perfused with bloo- sons why this might happen: d during systole as well as diastole, with 15–20% of the — Thrombosis (obstruction of a blood vessel by a total cardiac output going to the brain. Cerebral blood blood clot forming locally) flow is approximately 800 ml/min. This high and con- — Embolism (obstruction due to an embolus from tinuous blood flow is necessary as the brain uses glu- elsewhere in the body) (2) cose, exclusively, for energy metabolism and is unable — Systemic hypo perfusion (general decrease in to store energy. Cerebral blood flow is equipped with blood supply, e.g., in shock) (5) an autoregulatory mechanism, which protects against — Venous thrombosis (6). hypoxia and low perfusion. It is a multifactorial mech- anism, involving neurogenic, myogenic, and meta- Stroke without an obvious explanation is termed bolic controls. This autoregulation tries to maintain a “cryptogenic” (of unknown origin); this constitutes mean arterial pressure of 60–100 mm Hg and a cerebral 30–40% of all ischemic strokes (2, 7). blood flow of 50–60 ml/100 gm of brain per minute. There are various classification systems for acute When the cerebral blood flow decreases, the autoreg- ischemic stroke. The Oxford Community Stroke Pro- ulatory mechanism tries to compensate by increasing ject classification (OCSP, also known as the Bamford the blood pressure and inducing vasodilatation. Howe- or Oxford classification) relies primarily on the initial ver, if the blood flow decreases so much that it falls be- symptoms; based on the extent of the symptoms, the low a critical level, infarction results (Table 1). stroke episode is classified as total anterior circulation infarct (TACI), partial anterior circulation infarct (PA- Table 1. Cerebral perfusion and corresponding CI), lacunar infarct (LACI) or posterior circulation in- blood flow levels farct (POCI). These four entities predict the extent of Brain perfusion Cerebral blood flow the stroke, the area of the brain affected, the underlying Normal > 50–60 ml/100 gm/min cause, and the prognosis (8, 9). The TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification is Oligemic 30–60 ml/100 gm/min based on clinical symptoms as well as results of further Ischemic 20–30 ml/100 gm/min investigations; on this basis, a stroke is classified as be- Infarction < 10 ml/100 gm/min ing due tothrombosis or embolism due to atherosclero- sis of a large artery, embolism of cardiac origin, occlu- Stroke imaging serves two purposes: first, to diag- sion of a small blood vessel, other determined cause, nose or confirm the occurrence of a stroke and, second, undetermined cause (two possible causes, no cause to assess the amount of potentially salvageable brain tis- identified, or incomplete investigation) (1–5, 10). sue and irreversibly infarcted tissue; both are necessary, CT perfusion is the method by which perfusion to the first for planning management strategy and the sec- an organ measured by CT is still a relatively new con- ond for prognostication. CT perfusion (CTP) is a tool cept, although the original framework and principles that has been successfully employed to assess the extent were concretely laid out as early as 1980 by Leon Axel of salvageable tissue. It is most commonly carried out at University of California San Francisco (2). It is most for neuroimaging using dynamic sequential scanning of commonly carried out for neuroimaging using dyna- a pre-selected region of the brain during the injection of mic sequential scanning of a pre-selected region of the a bolus of iodinated contrast material as it travels thro- brain during the injection of a bolus of iodinated con- ugh the vasculature. Various mathematical models can trast material as it travels through the vasculature (11). then be used to process the raw temporal data to ascerta- Various mathematical models can then be used to pro- in quantitative information such as rate of cerebral cess the raw temporal data to ascertain quantitative in- blood flow (CBF) following an ischemic stroke. formation such as rate of cerebral blood flow (CBF) fo- llowing an ischemic stroke or aneurismal subarachnoid AIM hemorrhage. Practical CT perfusion as performed on The aim of this retrospective study is to show modern CT scanners was first described by Ken Miles, possibilities of CT perfusion as diagnostic procedure in Mike Hayball and Adrian Dixon from Cambridge UK patients with acute ischemic attack. (3) and subsequently developed by many individuals including Matthias Koenig and Ernst Klotz in Ger- METHODS many (4), and later by Max Wintermark in Switzerland and Ting-Yim Lee in Ontario, Canada (5). We retrospectivly reviewed examination of 64 pa- It is important to understand the normal physiol- tients with acute brain stroke who have received throm- ogy of the brain for accurate interpretation of stroke bolytic therapy after that. All patients were examined RESCUING THE ISCHEMIC PENUMBRA — OUR EXPIRIENCE 125 from January 2010 to October 2012. The research in- as time–attenuation curves (TAC) from which T- cluded 34 (53.13%) male and 30 (46.87%) female, wi- TP/MTT, CBV,and CBF can be calculated for any area th average age of the patients 57.42188 ± 5.31 years, of interest. range 45–74 years. All patients were examined on GE Bright Speed 16 MDCT with 50 ml of iodine contrast RESULTS agent (Ultravist 300, Bayer) following the standard procedure for CT perfusion. All examinations were All patients were examined in short time period of 4 made in period of 4 hours after the first symptom.
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