Hyperdense Appearance Research Articles

Cerebral Venous Sinus Thrombosis Presenting as Intracerebral Hemorrhage and Subarachnoid Hemorrhage: A Case Report

We present a 66-year-old male presenting with sudden onset of headache. Medical decompression was done and neuroimaging of plain cranial CT angiogram (CTA) and CT venogram (CTV) showed components of subarachnoid hemorrhage, intracerebral hemorrhage and hyperdense appearance of the superior sagittal sinus and proximal left transverse sinus. The following were done to look for etiologic factors: 1. fungal swab to determine the cause of the intracerebral hemorrhage secondary to venous thrombosis as the patient presented with a chronic history of sinusitis, 2. coagulopathy workup to look for a hypercoagulable state, and 3. workup for systemic disease of autoimmune in etiology. Anticoagulation was safely initiated within several days given the regression of the intracerebral hemorrhage along with stable findings of subarachnoid hemorrhage. Here we report cerebral venous sinus thrombosis rarely presenting as acute subarachnoid hemorrhage and intracerebral hemorrhage. Keywords: Cerebral venous thrombosis, superior sagittal sinus thrombosis, subarachnoid hemorrhage, intracerebral hemorrhage

Acute intestinal obstruction in systemic lupus Erythematosus: Case report and review of the literature

Introduction: Gastrointestinal manifestations in systemic lupus erythematosus are common and may involve any segment of the digestive tract. Lupus enteritis is one of the manifestations responsible for abdominal pain. Its treatment is based essentially on corticosteroids. The use of immunosuppressive drugs is reserved for recurrent forms or in case of failure of corticosteroids. Materials and methods: We report a case of “acute intestinal obstruction in systemic lupus erythematosus” in the Department of Emergency visceral surgery. Results: Mrs. SQ, S, 24 years old, was diagnosed one week ago with systemic lupus erythematosus at the beginning of treatment, with a history of pancreatitis stage E, history of current illness goes back to 05 days before her admission by the installation of a sub-occlusive syndrome made of cessation of matter and gas associated with food vomiting, with cessation of matter and gas in the last 48 hours. Para-clinical The Abdomen without preparation showed hydroaeric levels. With an abdominal CT scan which showed: CT scan appearance in favor of bowel obstruction with evidence of a transitional level above the umbilical: inflammatory stenosis? The spontaneously hyper-dense appearance of the colonic lumen and some ileal intestines is most probably related to a digestive hemorrhage that could be part of lupus enteritis given the patient’s past history with the spontaneously hyper-dense appearance of the colonic lumen and ileal intestines most probably related to a digestive hemorrhage. And distension of the jejunal and some ileal coves, measuring: 36mm in maximum diameter, the seat of hydrophobic level with a transitional level above umbilical. Significant gastric distension. No parietal pneumatosis with no parietal enhancement defect. In view of the clinical symptomatology and the CT scan results, the patient underwent an exploratory laparotomy with the following findings: Absence of peritoneal effusion with the presence of a 3 cm distension of the bowel without any sign of flange, stenosis, or detectable obstacle, with the performance of multiple biopsies at the level of the greater omentum, the mesentery, and the anterior parietal peritoneum Conclusion: Intestinal pseudo-obstruction is a rarely reported manifestation during systemic lupus erythematosus. It is a rare but potentially serious manifestation that can reveal the disease or occur during the course of the disease. The use of immunosuppressive drugs is reserved for recurrent forms or in case of failure of corticosteroids. However, recurrences are frequent. Azathioprine is an alternative therapy to control the disease. However, recurrences are frequent. Azathioprine is an alternative therapy to control the disease.

Diabetic Striatopathy; A Differential Worth Considering in Diabetic Patients with Acute Onset Hyperkinetic Movements or Basal Ganglia (Striatal) Abnormalities on Imaging. (P8-4.007)

<h3>Objective:</h3> To describe a rare but interesting neurologic complication of uncontrolled diabetes; diabetic striatopathy, and to discuss its presentation as an uncommon etiology of acute hyperkinetic movement disorders. <h3>Background:</h3> Diabetic striatopathy is described as a hyperglycemic state in conjunction with striatal abnormalities on imaging and or the presence of hyperkinetic movements such as chorea. Imaging abnormalities described include hyperdense appearance of the striatum on CT and hyperintensity of the striatum on T1 MRI sequence. Associated hyperkinetic movements are thought to be reversible with correction of hyperglycemia. Given its rarity and ease of being misdiagnosed, we present a case of a 74-year-old woman with imaging findings consistent with Diabetic striatopathy. She presented in-extremis from an outside hospital for neurosurgical evaluation of a left basal ganglia hemorrhage. Her past medical history included uncontrolled type 2 diabetes and hypertension. <h3>Design/Methods:</h3> Not Applicable <h3>Results:</h3> Physical examination revealed an intubated, comatose, hypotensive patient with an irregular pulse. Her Laboratory values suggested uncontrolled diabetes with a hemoglobin A1C of “&gt; 17.0%” (beyond the laboratory’s upper limit) and serum glucose of 611. She had profound diabetic ketoacidosis. A non-contrasted head CT revealed what was initially thought to be a left basal ganglia hemorrhage; same interpretation as the outside hospital but was later favored to likely represent “nonketotic hyperglycemic chorea” and less likely a basal ganglia hemorrhage by the attending radiologist. MRI confirmed this with T1 hyperintensity in the left striatum. <h3>Conclusions:</h3> Our patient passed away from her severe metabolic derangements and no hyperkinetic movements were observed. However, her presentation highlighted to us an important and underrecognized differential of basal ganglia hemorrhage on imaging especially in the setting of uncontrolled diabetes. The paucity of information surrounding its pathophysiology, poses an area of potential research. Often cited as associated with hyperglycemic nonketotic state, it was enlightening to see it in diabetic ketoacidosis. <b>Disclosure:</b> Dr. Durojaye has nothing to disclose. Dr. Sammond has nothing to disclose. Dr. Moosavi has nothing to disclose.

412 Polytetrafluoroethylene(PTFE) Pledgets Masquerading As A Pseudo-Aneurysm Of Left Ventricle Apex. A Case Report

Abstract Background TransCatheter Aortic Valve Implantation (TAVI) is now established as an alternative for open aortic valve replacement in high-risk patients with severe calcified degenerative aortic stenosis. Case presentation Here we report a case of a 78 tears old female patient who presented six months following transapical TAVI with a pulsatile mass over the left anterior mini thoracotomy wound. Transthoracic echocardiography showed suspicion of a left ventricular apical aneurysm with no evidence of free pericardial fluid.Contrast enhanced CT reported a large pseudo-aneurysm arising from the apex of the left ventricle extending through the left anterior thoracic wall. She was scheduled for emergency surgical exploration via median sternotomy. Upon median sternotomy there were dense pericardial adhesions limiting the mobilization of the heart specially the apex, which necessitated establishment of cardiopulmonary bypass. The heart was arrested, and the dissection was completed. The cavity in connection with the ventricular apex had purulent contents and the site of the TAVI ventriculotomy was secure with the PTFE pledgets in place with no evidence of leakage. Samples of the cavity fluids had pus cells, but no organisms were grown. The patient made an uneventful recovery and was discharged home 6 days postoperatively. Discussion PTFE pledgets are frequently used in cardiac surgery to support surgical closure. These pledgets on a contrast enhanced CT scan can make it difficult to correctly diagnose and may mimic anastomotic leaks as both give similar hyper-dense appearance on contrast enhanced CT scan

An Uncommon Hyperosmolar Nonketotic Condition

Hyperglycemia may present with neurological symptoms. This rare condition is called non-ketotic hemichorea-hemiballismus (HCHB). When investigating the causes of neurological symptoms in these cases, magnetic resonance imaging (MRI) imaging typically has a hyperintense appearance in T1 sections and a variable intense appearance in T2. A 68-year-old female patient was admitted to the emergency department with speech disorder. Blood sugar elevation and cranial tomography revealed hyperdense appearance in the left caudate nucleus and lentiform nucleus. The patient was hospitalized with a preliminary diagnosis of HCHB. Magnetic resonance in hyperintense T1W sequences in the nucleus caudatus hood and corpus on the left, putamen, globus pallidus, Significant hypointense signal changes were observed in T2W sequences. The patient was admitted to the hospital for treatment and his blood sugar regulation was restored. HCHB is a rare condition in emergency. After the regulation of blood sugar, neurological picture regression is observed. Blood sugar levels should be checked and appropriate treatment should be given in patients presenting with neurological symptoms.

Predicting cerebral edema in ischemic stroke patients.

To produce a scoring system for predicting the development of edema in ischemic stroke patients without edema on admission. This retrospective study included 572 ischemic stroke patients (73.3 ± 13.0years, 300 male) without signs of cerebral edema on the first CT scan, which was performed on admission. Another scan was normally performed 3days later, and subsequently whenever needed. Edema was defined as cerebral hypodensity with compression of lateral ventricles. The main clinical, laboratory, and instrumental variables obtained during the first 24h were related to the appearance of edema on the CT scans performed after the first one. Cerebral edema occurred in 158 patients (27.6%) after a median time of 4days. The variables independently associated with edema development were (odds ratio, 95% CI) the following: (1) total anterior circulation syndrome (4.20, 2.55-6.93; P < 0.0001), (2) hyperdense appearance of middle cerebral artery (4.12, 2.03-8.36; P = 0.0001), (3) closed eyes (2.53, 1.39-4.60; P = 0.002), (4) vomiting (3.53, 1.45-8.60; P = 0.006), (5) lacunar cerebral syndrome (0.36, 0.17-0.77; P = 0.008); and (6) white matter lesions (0.53, 0.33-0.86; P = 0.01). Counting one positive point for the first four variables and one negative point for the last two variables, a scoring system (E-score) was built. Cerebral edema could be predicted when the score was ≥ 1 (positive predictive value 61.6%, specificity 85.3%, sensitivity 62.0%). The area under the receiver operating characteristic curve was 0.78. In ischemic stroke patients, six variables obtained during the first 24h of hospitalization were predictive of subsequent cerebral edema development.

Septic cavernous sinus thrombosis

AbstractAlthough septic cavernous sinus thrombosis represents a rare cerebral vascular event, the morbidity and mortality can be profound. Diagnosis of this disease remains challenging, despite recent advances in imaging technology. We present a 71‐year‐old man who presented with symptoms of retro‐orbital pain, swelling and a recent history of being treated for bacterial sinusitis. An initial non‐contrast head computed tomography showed a dilated, hyperdense appearance of his left superior ophthalmic vein, with subsequent magnetic resonance imaging suggestive of bilateral ophthalmic vein thrombosis likely from cavernous sinus origin. The patient had blood cultures positive for Streptococcus anginosus, and was successfully treated with several weeks of i.v. antibiotics and anticoagulation.

The computed tomographic findings of pulmonary epithelioid hemangioendothelioma

The aim of this study is to analyse the computed tomographic (CT) findings of pulmonary epithelioid haemangioendothelioma (EHE). The CT features and clinical presentations of six patients (five women, one man; mean age, 53years) with pathology-proven pulmonary EHE were reviewed. Noncontrast CT images were available for three patients and enhanced CT images for three patients. The image characteristics included the number of tumours, tumour location and size, tumour margins, the presence of calcification/necrosis/cavity, the presence of perivascular location, the presence of pleural lesions, tumour homogeneity at contrast-enhanced CT, tumour enhancement relative to the adjacent muscle and the presence of extrapulmonary lesions. Multiple nodules/masses with irregular margin were shown in all cases, and reticulonodular opacities and ground-glass opacities were found in one case. Overall, the six cases showed 178 nodules/masses, 90% (160/178) of which were <1cm in diameter. The average size of the largest nodules/masses in each case was 2.7cm. The nodules/masses were mostly (93%, 166/178) located in the subpleural region (<2cm from the pleura). A total of 48% (86/178) of nodules/masses showed punctate calcification in four of six cases. All nodules/masses showed perivascular location. Pleural indentation was shown in all cases, as well as pleural-thickening in five cases and pleural effusion in two cases. On contrast-enhanced CT, EHE showed a mildly heterogeneous hyperdense appearance. With predilection for subpleural and perivascular location, typical pulmonary EHE appears as multiple irregular nodules with punctate calcification and pleural indentation.

The CT findings of pancreatic acinar cell carcinoma in five cases

ObjectivesThe aim of this study is to analyze the computed tomographic (CT) findings of pancreatic acinar cell carcinoma (ACC). Materials and methodsThe CT features and clinical presentations of five patients (four men, one woman; mean age, 52 years) with pathology-proven pancreatic ACC were reviewed. The image characteristics included the lesion location and size, the exophytic nature of the tumor, intratumoral hemorrhage, calcification, the presence of cystic or necrotic components, bile or pancreatic duct dilation, attenuation on the noncontrast image, attenuation on the arterial- and venous-phase images, peripancreatic invasion, peripancreatic lymphadenopathy, and distant metastases. ResultsThe tumors were located at the pancreatic tail in three cases and at the pancreatic head in two cases. The average lesion size was 5.3 cm. Exophytic features and cystic/necrotic components were found in 80% (4/5) and 60% (3/5) of cases, respectively. The ACC showed a mild hypodense appearance on noncontrast CT in 100% (3/3) of cases and a hypodense appearance on arterial-/venous-phase CT in 80% (4/5) of cases. The exception was one lesion that showed a significantly hyperdense appearance and a mildly hyperdense appearance on the arterial- and venous-phase images. None of the CT images showed enhancement of a capsule, calcification, intratumoral hemorrhage, bile or pancreatic duct dilation, vascular encasement, or distant metastatic disease, but three cases showed peripancreatic invasion and lymphadenopathy. ConclusionsWith persistent mild enhancement, the typical ACC appears as an exophytic tumor with a focal cystic/necrotic component and the lack of ductal dilatation. The predilection for older male patients and elevated serum alpha fetoprotein are useful clinical features for confirming an ACC diagnosis.

Correlative ROI Calculation of MCAs: Another Promising Primary Sign of Acute Infarction?

The purpose of this project was to calculate the ROI of the middle cerebral artery (MCA) in patients with acute stroke to establish if this measurement could be used as another primary sign of infarction even if other established primary signs of infarction are absent. CT brain scans of 465 patients, who presented in the emergency room in the first six hours after the onset of symptoms, were studied retrospectively. Two polygonal ROIs were drawn on the M1 segments of both middle cerebral arteries and three parameters were calculated automatically: HU density, volume and surface of the corresponding artery segment. The age and gender of each patient were also recorded, as well as the CT findings (including the hyperdense appearance of MCA and the insular ribbon sign) and the neurological findings. The range of calculated ROIs was between 9 HU and 134 HU. A statistically significant difference was reported in ROI measurement between the right and left MCA in patients with left (or right) hemiparesis respectively. A significant difference was also reported between the ROIs of the right and left MCA in patients with acute ischemic stroke in the region of the brain supplied by the left (or right) MCA respectively. ROI measurement of MCA is easy to apply and interpret during the CT scan and might serve as an additional primary sign of infarction.

The role of exudation in chronic subdural hematomas

Chronic subdural hematomas (SDHs) are a local inflammatory process that causes the formation of a granulation tissue often referred to as the external or outer membrane. This membrane has abnormally permeable macrocapillaries. Therefore, exudation from the macrocapillaries in the outer membrane of chronic SDH may play an important role in the enlargement of chronic SDH. In this study the authors investigated the role of exudation in chronic SDH. The authors examined 24 patients (16 men and eight women; age range 38-86 years [mean age 61.4 years]) with 27 chronic SDHs. The clinical status of the patients was evaluated according to the classification described by Markwalder. The diagnosis was established on computed tomography (CT) scans in all cases. The authors also used the Nomura Classification for judging the lesion's appearance on CT scans. Immediately after the diagnosis, all patients were administered 20 mCi (740 mBq) technetium-99m human serum albumin. Four hours later, blood and SDH samples were taken and radioactivity levels were measured in each. The ratio of activity of the samples taken from chronic SDH to the radioactivity of blood was determined as a percentage and defined as the exudation rate. On the follow-up CT scan obtained on postoperative Day 20, subdural collections thicker than 5 mm were determined to be a reaccumulation. The correlations between the exudation rate and age of the patients, clinical grades, CT appearances, and amount of reaccumulation were investigated. In this series the average exudation rate was 13.24% (range 2.05-28.88%). The mean exudation rates according to the clinical grades assigned to patients were as follows: Grade 0, 8.67 +/- 5.64% (three patients); Grade 1, 5.07 +/- 1.43% (eight patients); Grade 2, 17.87 +/- 3.73% (seven patients); and Grade 3, 19.65 +/- 7.67% (six patients). Exudation rates in patients with Grades 2 and 3 were significantly higher than those in Grades 0 and 1 (p < 0.05). The mean exudation rates according to the lesion's appearance on CT scans were found as follows: hypodense appearance, 6.55 +/- 4.52% (eight patients); isodense appearance, 11.07 +/- 6.32% (five patients); hyperdense appearance, 19.47 +/- 13.61% (three patients); and mixed-density appearance, 17.40 +/- 5.80% (nine patients). The differences among the groups were significant (p < 0.05). The average exudation rate was statistically higher in the patients with reaccumulation (16.30 +/- 8.16%) than that in the patients without reaccumulation (9.96 +/- 6.84%) (p < 0.05). The exudation rate in chronic SDH is correlated with a higher clinical grade (Markwalder Grade 2 or 3), mixed-density CT appearance, and reaccumulation. Therefore, exudation from macrocapillaries in the outer membrane of chronic SDH probably plays an important role in the pathophysiology and the growth of chronic SDH.

Bithalamic infarcts: embolism of the top of basilar artery or deep cerebral venous thrombosis?

Bithalamic infarcts are usually attributed to thromboembolism of the top of the basilar artery. However, in some cases, deep cerebral venous thrombosis and thrombosis of cerebral venous sinuses was proved to be the cause. The case of a 47-year-old female with ischemic thalamic and mesencephalic lesions is reported, that was attributed to thrombosis of internal cerebral veins. In cases of bithalamic infarcts, apart from the top of the basilar artery syndrome, deep cerebral venous thrombosis should be taken into consideration. Neuroimaging findings such as generalized cerebral edema, multiple infarcts or hemorrhages, hyperdense appearance of cerebral sinuses or veins and filling defects in the cerebral venous sinuses in contrast-CCT, can lead to the proper diagnosis.

The hyperdense sylvian fissure MCA ”dot“ sign: a marker of acute CT ischemia

P40 Background: The hyperdense appearance of the middle cerebral artery is now a familiar early warning of large cerebral infarction, brain oedema and poor prognosis. Less well described, however, is the hyperdensity associated with embolic occlusion of branches of the middle cerebral artery seen in the sylvian fissure (MCA ”dot“ sign). The aim of this study was to define this sign, and to determine the incidence, its diagnostic value, and reliability. Methods: Computed tomographic (CT) scans performed on patients with acute ischemic stroke within 3 hours of symptom onset were analysed for signs of thromboembolic stroke and evidence of early CT ischemia. Two neuroradiologists and two stroke neurologists initially blinded to all clinical information, and then with knowledge of the affected hemisphere evaluated scans for the presence of a hyperdense MCA sign (HMCA), a hyperdense sylvian fissure MCA ”dot“ sign, and for early MCA territory ischemic changes. Results: Of 100 consecutive patients presenting within 3 hours of symptom onset early CT ischemia was seen in 74 % of the baseline CT scans. The HMCA sign was seen in 5% of CT scans whereas the MCA ”dot“ sign was seen in 16% of which 2 were associated with a HMCA sign. The presence of a HMCA sign was associated with a greater probability of dependence or death than when a MCA ”dot“ sign was observed or no hyperdensity was seen (P&lt;0.05). All 5 patients with a HMCA sign, including 2 with an associated MCA ”dot“ sign were either dead or dependent at 3 months. Patients with a dot sign alone had independent outcomes in 64% of cases (P&lt;0.8). Balanced kappa statistics for both signs were in the moderate to good range when the side of stroke was known. Conclusions: The hyperdense sylvian fissure MCA ”dot“ sign is an early marker of thromboembolic occlusion of the distal MCA and of its branches.

The hyperdense sylvian fissure MCA "dot" sign: a marker of acute CT ischemia

P40 Background: The hyperdense appearance of the middle cerebral artery is now a familiar early warning of large cerebral infarction, brain oedema and poor prognosis. Less well described, however, is the hyperdensity associated with embolic occlusion of branches of the middle cerebral artery seen in the sylvian fissure (MCA ”dot“ sign). The aim of this study was to define this sign, and to determine the incidence, its diagnostic value, and reliability. Methods: Computed tomographic (CT) scans performed on patients with acute ischemic stroke within 3 hours of symptom onset were analysed for signs of thromboembolic stroke and evidence of early CT ischemia. Two neuroradiologists and two stroke neurologists initially blinded to all clinical information, and then with knowledge of the affected hemisphere evaluated scans for the presence of a hyperdense MCA sign (HMCA), a hyperdense sylvian fissure MCA ”dot“ sign, and for early MCA territory ischemic changes. Results: Of 100 consecutive patients presenting within 3 hours of symptom onset early CT ischemia was seen in 74 % of the baseline CT scans. The HMCA sign was seen in 5% of CT scans whereas the MCA ”dot“ sign was seen in 16% of which 2 were associated with a HMCA sign. The presence of a HMCA sign was associated with a greater probability of dependence or death than when a MCA ”dot“ sign was observed or no hyperdensity was seen (P Conclusions: The hyperdense sylvian fissure MCA ”dot“ sign is an early marker of thromboembolic occlusion of the distal MCA and of its branches.

Hyperechoic middle cerebral artery: acute occlusion detected by transcranial duplex ultrasonography.

The authors describe the appearance of acute thromboembolic occlusion of the middle cerebral artery (MCA) using transcranial duplex ultrasonography. Acute occlusion of the MCA commonly leads to severe cerebral infarction. In patients with acute MCA occlusion, secondary edema and elevated intracranial pressure are major causes of increased morbidity and mortality. Thus, the prompt detection of occlusion influences early therapy, including thrombolysis and increased control of intracranial pressure. The hyperdense appearance of the acutely occluded MCA as seen using computed tomography (CT) has been extensively reported in the literature. However, its appearance using transcranial duplex ultrasonography has not been reported. The authors report four patients who had clinical features of ischemia throughout the MCA territory. All patients were studied with CT and transcranial duplex ultrasonography within 6 hours of the onset of symptoms. Head CT of all four patients showed a hyperdense MCA sign with infarction of the MCA territory. Transcranial duplex studies using either pulsed Doppler or color Doppler sonography displayed a hyperechoic MCA with no evidence of flow. Subsequent duplex ultrasonography and magnetic resonance angiography showed all four patients had ipsilateral occlusion of the internal carotid artery. Transcranial duplex ultrasonography assists in the early diagnosis of acute MCA occlusion. The affected vessel is displayed as a hyperechoic structure associated with no flow using Doppler examination.

Stereotactic management of colloid cysts: factors predicting success

Stereotactic aspiration is a valuable surgical alternative for colloid cysts when used alone or in conjunction with microsurgical resection. Since 1981, the authors have performed computerized tomography (CT)-guided stereotactic aspiration as the initial procedure in 22 patients with colloid cysts; stereotactic aspiration alone was successful in 11 patients (50%). Of the 11 patients in whom aspiration failed, stereotactic endoscopic resection was attempted in three and was successful in one. Seven patients required a craniotomy and microsurgical removal of the cyst performed via a transcortical approach. The preoperative CT appearance in eight cases of a hypodense or isodense cyst correlated favorably with successful aspiration of the cyst in six patients. A hyperdense appearance on the preoperative CT scan in 14 cases was associated with subtotal aspiration in 13 patients; five required craniotomy for removal. Preoperative magnetic resonance (MR) imaging in eight patients provided excellent anatomical definition of the cyst and its relationship to other structures of the third ventricle, but it was not possible to correlate successful aspiration with cyst appearance on MR images with short or long relaxation time sequences. The authors' 9-year experience suggests that preoperative CT studies accurately determine size, predict viscosity, and help to define a group of colloid cyst patients for whom stereotactic cyst aspiration will likely be successful. Unsuccessful stereotactic aspiration was related to two features: the high viscosity of the intracystic colloid material (nine patients), or deviation of the cyst away from the aspiration needle due to small cyst volume (two patients). Because of its simplicity and low risk, stereotactic surgery can be offered to selected patients as the initial procedure of choice. Craniotomy can be reserved for those whose imaging studies predict failure or for those whose cyst cannot be aspirated.

Dense middle cerebral artery sign: an indicator of poor outcome in middle cerebral artery area infarction.

Thirteen patients with a dense appearance of the horizontal part of the middle cerebral artery (MCA) "dense middle cerebral artery sign" in CT scans taken within 24 hours after onset of ischaemic stroke had considerably poorer prognosis than controls with stroke, but without the sign. A hyperdense appearance of the MCA is known to be associated with thromboembolism, but dense middle cerebral artery sign is also an early warning of a large infarction, brain oedema and poor prognosis in infarction in the MCA area.