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Biomedical subjects

M Wintermark

Publications and source records attributed to M Wintermark.

At least 19 recordsLinked to original sources
PubMed2006

Cerebral vascular autoregulation assessed by perfusion-CT in severe head trauma patients.

PURPOSE: To use perfusion-CT technique in order to characterize cerebral vascular autoregulation in a population of severe head trauma patients with features of cerebral edema either on the admission or on the follow-up conventional noncontrast cerebral CT. MATERIAL AND METHODS: A total of 80 perfusion-CT examinations were obtained in 42 severe head trauma patients with features of cerebral edema on conventional noncontrast cerebral CT, either on admission or during follow-up. Perfusion-CT results, i.e. the regional cerebral blood volume (rCBV) and flow (rCBF), were correlated with the mean arterial pressure (MAP) measured during each perfusion-CT examination. Ratios were defined to integrate the concept of cerebral vascular autoregulation, and cluster analysis performed, which allowed identification of different subgroups of patients. MAP values and perfusion-CT results in these groups were compared using Kruskal-Wallis and Wilcoxon (Mann-Whitney) tests. Moreover, the functional outcome of the 42 patients was evaluated 3 months after trauma on the basis of the Glasgow Outcome Scale (GOS) score and similarly compared between groups. RESULTS: Three main groups of patients were identified: 1) 22 perfusion-CT examinations were collected in 13 patients, characterized by high rCBV and rCBF values and by significant dependence of perfusion-CT rCBV and rCBF results on MAP values (p<0.001), 2) 23 perfusion-CT examinations collected in 19 patients showing perfusion-CT results similar to control trauma subjects, and 3) 33 perfusion-CT collected in 16 patients, with low rCBV and rCBF values and near-independence of perfusion-CT results with respect to MAP values. The first group was interpreted as showing impaired cerebral vascular autoregulation, which was preserved in the third group. The second group was associated with the best functional outcome; it was linked to the first group, because eight patients went from one group to the other from admission to follow-up. CONCLUSION: Perfusion-CT in severe head trauma patients was able to provide direct and quantitative assessment of cerebral vascular autoregulation with a single measurement. It could hence be used as a guide for brain edema therapy, as well as to monitor the treatment efficiency.

Adult↗
PubMed2006

Quantitative measurement of blood-brain barrier permeability using perfusion-CT in extra-axial brain tumors.

Non-invasive assessment of vascular permeability is of main importance in the diagnosis, treatment and follow-up of intracranial tumors. Perfusion-CT is one of the imaging options available, which affords quantitative assessment of cerebral blood volume and blood-brain barrier permeability. Herein we report two cases of extra-axial tumors studied with perfusion-CT. Comparison with perfusion-MRI was available in one case. High permeability values, as measured by perfusion-CT, reflected the absence of blood-brain barrier in these extra-axial tumors.

Aged, 80 and over↗
PubMed2006

Vasospasm after subarachnoid hemorrhage: utility of perfusion CT and CT angiography on diagnosis and management.

PURPOSE: To evaluate the utility of perfusion CT (PCT) combined with CT angiography (CTA) for the diagnosis and management of vasospasm, by using conventional digital subtraction angiography (DSA) as the gold standard. METHODS: We retrospectively identified 27 patients with acute subarachnoid hemorrhage who had undergone CTA/PCT, DSA, and transcranial Doppler (TCD) ultrasonography within a time interval of 12 hours of one another. The patients' charts were reviewed for treatment of vasospasm. CTA, PCT, TCD, and DSA examinations were independently reviewed and quantified for vasospasm. PCT thresholds, CTA findings, noncontrast CT (NCT) hypodensities, and TCD thresholds were evaluated for accuracy, sensitivity, and specificity, as well as for negative (NPV) and positive predictive values (PPV) in the prediction of angiographic vasospasm and endovascular treatment, considering DSA as the gold standard. RESULTS: Thirty-five CTA/PCT, TCD, and DSA examinations were performed on these 27 patients. A total of 123 arterial territories in 11 patients demonstrated angiographic vasospasm. Six patients underwent endovascular therapy. CTA qualitative assessment and PCT-derived mean transit time (MTT) with a threshold at 6.4 seconds represented the most accurate (93%) combination for the diagnosis of vasospasm, whereas MTT considered alone represented the most sensitive parameter (NPV, 98.7%). A cortical regional cerebral blood flow value </=39.3 (mL x 100 g(-1)x min(-1)) represented the most accurate (94.8%) indicator for endovascular therapy. PCT had significantly higher PPV (89.9%) than TCD (62.9%). CONCLUSIONS: A CT survey combining CTA and PCT represents an accurate screening test in patients with suspected vasospasm. However promising, the value of PCT for selecting the best management strategy in such patients will need to be further investigated.

Adolescent↗
PubMed2006

Restricted diffusion in bilateral optic nerves and retinas as an indicator of venous ischemia caused by cavernous sinus thrombophlebitis.

A 44-year-old man developed bilateral blindness following severe periorbital cellulitis and pansinusitis. CT and MR imaging demonstrated bilateral cavernous sinus thrombosis. Diffusion-weighted imaging revealed reduced apparent diffusion coefficient in bilateral optic nerves, suggesting optic nerve ischemia caused by the cavernous sinus thrombophlebitis (CST). Following surgical debridement of pansinusitis, antimicrobial therapy, and anticoagulation, the patient recovered from the infectious episode but sustained permanent bilateral blindness. This case shows that both retinal and optic nerve ischemia can be the cause of blindness after CST. Arguments supporting an arterial-versus-venous origin for the ischemia are discussed.

Adult↗
PubMed2005

Posttraumatic pseudolipoma: MRI appearances.

The goal of this study was to describe the MRI characteristics of posttraumatic pseudolipomas. Ten patients with previous history of blunt trauma or local surgery were investigated with MRI at the level of their deformity. The etiology was blunt trauma in eight patients and postoperative trauma in two. For all patients medical documentation, in the form of clinical history and physical examination, confirmed that a visible hematoma was present acutely at the same location following the injury and that the contour deformity subsequently appeared. All patients underwent liposuction. Preoperative bilateral MRI examinations were performed on all patients. The mean clinical follow-up was 17.8 months. MRI examinations were interpreted in consensus by two experienced musculoskeletal radiologists with attention to fatty extension (subcutaneous fatty thickness and anatomical extension), asymmetry compared with the asymptomatic side, the presence or absence of fibrous septae or nonfatty components, and patterns of contrast enhancement. Ten posttraumatic pseudolipomas were identified. Clinically, they showed as subcutaneous masses with the consistency of normal adipose tissue. Their locations were the abdomen (n=1), hip (n=1), the upper thigh (n=6), the knee (n=1), and the ankle (n=1). On MRI examinations, using the contralateral side as a control, pseudolipomas appeared as focal fatty masses without a capsule or contrast enhancement. Posttraumatic pseudolipomas may develop at a site of blunt trauma or surgical procedures often antedated by a soft tissue hematoma. Characteristic MRI findings are unencapsulated subcutaneous fatty masses without contrast enhancement.

Adipose Tissue↗
PubMed2005

Comparative overview of brain perfusion imaging techniques.

Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are: Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT), Xenon-enhanced Computed Tomography (XeCT), Dynamic Perfusion-computed Tomography (PCT), Magnetic Resonance Imaging Dynamic Susceptibility Contrast (DSC), Arterial Spin-Labeling (ASL), and Doppler Ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow (CBF) or volume (CBV). All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview, established by consensus among specialists of the various techniques. For clinicians, this paper should offers a clearer picture of the pros and cons of currently available brain perfusion imaging techniques, and assist them in choosing the proper method in every specific clinical setting.

Cerebrovascular Circulation↗
PubMed2003

[Perfusion-CT guided acute stroke management].

The easily accessible and available PCT reliably identifies reversible and irreversible ischaemia in acute stroke patients. These knowledge will allow treatment strategies to become more appropriate and individualized. Patients with significant penumbra may be candidates for treatment with dangerous or costly medication, and patients without may not, independently of duration of stroke symptoms. Furthermore, PCT also has the scientific potential to identify appropriate patients for therapeutic trials. Finally, salvage of PCT-defined penumbra could be used as a surrogate marker for effectiveness of interventions.

Cerebrovascular Circulation↗
PubMed2002

Comparison of admission perfusion computed tomography and qualitative diffusion- and perfusion-weighted magnetic resonance imaging in acute stroke patients.

BACKGROUND AND PURPOSE: Besides classic criteria, cerebral perfusion imaging could improve patient selection for thrombolytic therapy. The purpose of this study was to compare quantitative perfusion CT imaging and qualitative diffusion- and perfusion-weighted MRI (DWI and PWI) in acute stroke patients at the time of their emergency evaluation. METHODS: Thirteen acute stroke patients underwent perfusion CT and DWI or PWI on admission. The size of infarct and ischemic lesion (infarct plus penumbra) on the admission perfusion CT was compared with that of the MR abnormalities as shown on the DWI trace and on the relative cerebral blood volume, cerebral blood flow, time to peak, and mean transit time maps calculated from PWI studies. RESULTS: The most significant correlation was found between infarct size on the admission perfusion CT and abnormality size on the admission DWI map (r=0.968, P<0.001). A significant correlation was also observed between the size of the ischemic lesion (infarct plus penumbra) on the admission perfusion CT and the abnormality size on the mean transit time map calculated from admission PWI (r=0.946, P<0.001). Information about cerebral infarct and total ischemia (infarct plus penumbra) carried by both imaging techniques was similar, with slopes of 0.913 and 0.905, respectively. CONCLUSIONS: An imaging technique may be helpful in the identification of cerebral penumbra in acute stroke patients and thus in the selection of patients for thrombolytic therapy. Perfusion CT and DWI/PWI are equivalent in this task.

Acute Disease↗
PubMed2002

[Imaging of patients post blunt trauma to the chest].

Blunt chest traumas are a major concern in the setting of high-speed deceleration accidents, since they are associated with a high mortality rate. However, their prompt diagnosis and treatment allows for significant improvement of blunt chest trauma patient's clinical prognosis. If chest radiograph remains the initial screening test, the role of CT is increasing since it provides fast, sensitive, accurate and exhaustive survey of blunt chest trauma patients. The purpose of this article is to review the various radiological and CT patterns of blunt chest lesions.

Adolescent↗
PubMed2001

Blunt trauma of the heart: CT pattern of atrial appendage ruptures.

Blunt trauma patients with myocardial ruptures rarely survive long enough to reach a trauma center; however, for the survivors, prompt diagnosis and surgery are mandatory and save up to 80% of patients. Preoperative diagnosis of myocardial ruptures is assessed by echocardiography or, more rarely, by angiocardiography. We report two cases of blunt trauma patients with an atrial appendage rupture which could be retrospectively identified on admission CT survey.

Adult↗
PubMed2001

Blunt traumatic rupture of a mainstem bronchus: spiral CT demonstration of the "fallen lung" sign.

Tracheo-bronchial injuries occur in less than 1 % of blunt chest trauma patients. Indirect signs, such as pneumomediastinum, pneumothorax, and/or subcutaneous emphysema, are revealed on admission plain films and chest CT survey. In most instances, however, tracheobronchoscopy is mandatory in assessing the definite diagnosis of tracheo-bronchial lesion. Occasionally, an abnormal course of a mainstem bronchus or a "fallen lung" sign, featuring a collapsed lung in a dependent position, hanging on the hilum only by its vascular attachments, may allow for CT diagnosis of a blunt traumatic bronchial injury.

Adult↗
PubMed2001

Quantitative assessment of regional cerebral blood flows by perfusion CT studies at low injection rates: a critical review of the underlying theoretical models.

Viability of the cerebral parenchyma is dependent on cerebral blood flow (CBF), which is usually kept in a very narrow range due to efficient autoregulation processes and can be altered in a variety of pathological conditions. An accurate method allowing for a quantitative assessment of regional cerebral blood flows (rCBF) and available for the routine clinical practice would, for sure, greatly contribute to improving the management of patients with cerebrovascular diseases. Different imaging techniques are now available to evaluate rCBF: positron emission tomography; single photon emission CT; stable-xenon CT; perfusion CT; and perfusion MRI. Each of these imaging techniques uses an indicator, with specific biological properties, and is supported by a model, which consists of a few simplifying assumptions, necessary to state and solve the equations giving access to rCBF. The obtained results are more or less reliable, depending on whether modeling hypotheses are fulfilled by the used indicator. The purpose of this article is to review the various supporting models in the assessment of rCBF, with special emphasis on perfusion CT studies at low injection rates and on iodinated contrast material used as an indicator.

Cerebrovascular Circulation↗
PubMed2001

The Macklin effect: a frequent etiology for pneumomediastinum in severe blunt chest trauma.

STUDY OBJECTIVES: To review the etiology and pathophysiology of pneumomediastinum in severe blunt trauma, with a special interest in one of its possible origins, the Macklin effect. The Macklin effect relates to a three-step pathophysiologic process: blunt traumatic alveolar ruptures, air dissection along bronchovascular sheaths, and spreading of this blunt pulmonary interstitial emphysema into the mediastinum. The clinical relevance of the Macklin effect was also evaluated. SETTING: A university hospital serving as a reference trauma center. PATIENTS: A selection of 51 patients with severe blunt trauma between 1995 and 2000. INCLUSION CRITERIA: Severe trauma or high-speed deceleration justifying chest CT; if chest CT demonstrated a pneumomediastinum, bronchoscopy and esophagoscopy were performed to rule out tracheobronchial or esophageal injury. DESIGN: Retrospective analysis of patients' clinical files, chest CT, and bronchoscopy and esophagoscopy reports. The Macklin effect was diagnosed when an air collection adjacent to a bronchus and a pulmonary vessel could be clearly identified on the chest CT. Clinical relevance of the Macklin effect was statistically evaluated regarding its repercussions on the pulmonary gas exchange function, the respective durations of intensive care and total hospital stay, and the associated injuries. RESULTS: Twenty (39%) Macklin effects and 5 tracheobronchial injuries (10%) were identified. One tracheobronchial injury occurred simultaneously with the Macklin effect. The presence of the Macklin effect affected neither the clinical profile nor the result of pulmonary gas analysis on hospital admission, but was associated with a significant (p < 0.001) lengthening of the intensive care stay. CONCLUSIONS: The Macklin effect is present in 39% of severe blunt traumatic pneumomediastinum detected by CT. Its identification does not rule out a tracheobronchial injury. The Macklin effect reflects severe trauma, since it is associated with significantly prolonged intensive care stay.

Adolescent↗
PubMed2001

Simultaneous measurement of regional cerebral blood flow by perfusion CT and stable xenon CT: a validation study.

BACKGROUND AND PURPOSE: Knowledge of cerebral blood flow (CBF) alterations in cases of acute stroke could be valuable in the early management of these cases. Among imaging techniques affording evaluation of cerebral perfusion, perfusion CT studies involve sequential acquisition of cerebral CT sections obtained in an axial mode during the IV administration of iodinated contrast material. They are thus very easy to perform in emergency settings. Perfusion CT values of CBF have proved to be accurate in animals, and perfusion CT affords plausible values in humans. The purpose of this study was to validate perfusion CT studies of CBF by comparison with the results provided by stable xenon CT, which have been reported to be accurate, and to evaluate acquisition and processing modalities of CT data, notably the possible deconvolution methods and the selection of the reference artery. METHODS: Twelve stable xenon CT and perfusion CT cerebral examinations were performed within an interval of a few minutes in patients with various cerebrovascular diseases. CBF maps were obtained from perfusion CT data by deconvolution using singular value decomposition and least mean square methods. The CBF were compared with the stable xenon CT results in multiple regions of interest through linear regression analysis and bilateral t tests for matched variables. RESULTS: Linear regression analysis showed good correlation between perfusion CT and stable xenon CT CBF values (singular value decomposition method: R(2) = 0.79, slope = 0.87; least mean square method: R(2) = 0.67, slope = 0.83). Bilateral t tests for matched variables did not identify a significant difference between the two imaging methods (P >.1). Both deconvolution methods were equivalent (P >.1). The choice of the reference artery is a major concern and has a strong influence on the final perfusion CT CBF map. CONCLUSION: Perfusion CT studies of CBF achieved with adequate acquisition parameters and processing lead to accurate and reliable results.

Adult↗
PubMed2000

Imaging of blunt chest trauma.

In western European countries most blunt chest traumas are associated with motor vehicle and sport-related accidents. In Switzerland, 39 of 10,000 inhabitants were involved and severely injured in road accidents in 1998. Fifty two percent of them suffered from blunt chest trauma. According to the Swiss Federal Office of Statistics, traumas represented in men the fourth major cause of death (4%) after cardiovascular disease (38%), cancer (28%), and respiratory disease (7%) in 1998. The outcome of chest trauma patients is determined mainly by the severity of the lesions, the prompt appropriate treatment delivered on the scene of the accident, the time needed to transport the patient to a trauma center, and the immediate recognition of the lesions by a trained emergency team. Other determining factors include age as well as coexisting cardiac, pulmonary, and renal diseases. Our purpose was to review the wide spectrum of pathologies related to blunt chest trauma involving the chest wall, pleura, lungs, trachea and bronchi, aorta, aortic arch vessels, and diaphragm. A particular focus on the diagnostic impact of CT is demonstrated.

Diagnosis, Differential↗
PubMedDate not supplied

Using 80 kVp versus 120 kVp in perfusion CT measurement of regional cerebral blood flow.

Perfusion CT studies of regional cerebral blood flow (rCBF), involving sequential acquisition of cerebral CT sections during IV contrast material administration, have classically been reported to be achieved at 120 kVp. We hypothesized that using 80 kVp should result in the same image quality while significantly lowering the patient's radiation dose, and we evaluated this assumption. In five patients undergoing cerebral CT survey, one section level was imaged at 120 kVp and 80 kVp, before and after IV administration of iodinated contrast material. These four cerebral CT sections obtained in each patient were analyzed with special interest to contrast, noise, and radiation dose. Contrast enhancement at 80 kVp is significantly increased (P < .001), as well as contrast between gray matter and white matter after contrast enhancement (P < .001). Mean noise at 80 kVp is not statistically different (P = .042). Finally, performance of perfusion CT studies at 80 kVp, keeping mAs constant, lowers the radiation dose by a factor of 2.8. We, thus, conclude that 80 kVp acquisition of perfusion CT studies of rCBF will result in increased contrast enhancement and should improve rCBF analysis, with a reduced patient's irradiation.

Brain↗