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Karl-Olof Lövblad

Publications and source records attributed to Karl-Olof Lövblad.

11 recordsLinked to original sources
PubMed2006

Intracranial aneurysm stenting: follow-up with MR angiography.

Intracranial stenting is increasingly being used to treat intracranial aneurysms and stenoses. We wanted to assess the utility of magnetic resonance angiography (MRA) in the follow-up of patients treated with various types of intracranial stents and to assess the utility of performing gadolinium-enhanced MRA. A total of 19 patients having undergone intracranial stenting for aneurysms were imaged by MRI at 1.5T. A total of 20 stents were placed in 19 patients. In addition to conventional T2- and diffusion-weighted MRI, 3D time-of-flight MRA was performed before and after contrast administration. In the case of metallic INX stents (N = 7), there was a signal drop at the level of the vessel. which did not allow to evaluating the parent vessel, whereas this was visible in Nitinol stents (N = 8). Additionally a stent with a wire had a small artifact (N = 3). Contrast administration also improved vessel lumen visualization. In the case of Nitinol stents, MRA can be used to reliably demonstrate the vessel lumen after intracranial stenting. The use of postcontrast 3D time-of-flight imaging helps improve the intraluminal definition.

Adult↗
PubMed2005

Actual diagnostic approach to the acute stroke patient.

Since acute stroke is now considered a potentially treatable medical emergency, a rapid and correct diagnosis must be made. The first step is to exclude hemorrhage, then to visualize any early ischemic changes, demonstrate the presence of hypoperfusion and locate the presence of a vascular underlying pathology as well as elucidate the presence of a potential penumbra (tissue at risk). Thanks to improvements and advances in both MR and CT technology, this can now be done in a number of ways. At the moment, CT is the most widely available and fast method for obtaining imaging of the brain and neck vessels of patients presenting with acute stroke. MRI can provide more precise information, although it remains slightly more time-consuming, but is, however, the method of choice for follow-up imaging. The main point is to take the one-stop-shopping approach where imaging of the vessels and brain is done from the aortic arch to the circle of Willis in one single session in order to have all the necessary information in the acute phase.

Brain Ischemia↗
PubMed2003

Magnetic resonance imaging of the ischaemic penumbra.

Acute cerebral ischaemia should no longer be considered a tragic untreatable event but a medical emergency. To be able to start therapy, imaging is needed to assess the presence of a potential penumbra, i.e. an area of the brain which is hypoperfused but not yet definitively infarcted. With the development of diffusion and perfusion MR techniques, the concept of a penumbra model has been developed in which it corresponds to the acute mismatch between diffusion and perfusion volumes. This penumbra should constitute the target for potential therapies.

Brain Ischemia↗
PubMed2002

Perfusion MRI abnormalities in the absence of diffusion changes in a case of moyamoya-like syndrome in neurofibromatosis type 1.

We report on a 12-year-old boy with neurofibromatosis type 1 who suffered a transient ischemic attack. Angiography revealed occlusion of intracranial arteries, moyamoya vessels and leptomeningeal collaterals. The conventional T2-weighted and the diffusion-weighted MRI images demonstrated no pathology. Dynamic first-pass postgadolinium T2* perfusion-weighted MRI depicted altered hemodynamics in the vascular territory of the left middle cerebral artery, which defined this region as ischemic tissue at risk. The patient suffered a repeat transient ischemic attack 5 days later.

Cerebral Angiography↗
PubMed2002

Fast contrast-enhanced MR whole-brain venography.

Our aim was to assess the value of a new fast contrast-enhanced MR venography (CE-MRV) sequence in the investigation of normal and diseased cerebral veins. Conventional time-of-flight (TOF) MRV is time consuming, with imaging for a single sequence taking many minutes. MRI was performed with a clinical 1.5-T scanner; conventional TOF MRV followed by CE-MRV was performed using a modified 3D first-pass MR angiography sequence. Ten control subjects without cerebral pathology were studied as well as ten patients with cerebral venous thrombosis for a total of 20 studies with both sequences. CE-MRV was able to provide a set of complete MRV images in a significantly shorter time than conventional MRV sequencing could. The field of view also provided greater coverage of the vessels of the head and neck. CE-MRV also provided more extensive small vein detail and provided a better demonstration of intraluminal defects, despite a slightly lower resolution. Both methods were equally suited for the demonstration of venous thrombosis and demonstrated all cases equally well; however, CE-MRV provided more detailed information by showing partially obstructed sinuses and by showing better the presence of cortical collateral venous drainage.

Adolescent↗
PubMed2002

Non-traumatic neurological emergencies: emergency neuroradiological interventions.

This article summarizes recent developments in the growing field of interventional neuroradiology for the treatment of acute cerebrovascular disease. We describe the possibilities in endovascular therapy of acute cerebral aneurysms using electrolytically detachable coils combined with trispan neck bridging devices and stent implantation to occlude acute wide neck aneurysms. Techniques and results of local intra-arterial thrombolytic therapy in acute stroke and central retinal artery occlusion are described and we discuss the potential for rapid, large-burden thrombus removal in cases of internal carotid artery thrombosis by rheolytic thrombectomy, percutaneous transluminal angioplasty and stent implantation. Emergency endovascular therapy using the transvenous approach to treat severe intracranial or intraocular hypertension and multifocal haemorrhagic venous infarction due to cerebral sinus thrombosis or dural fistulas is also described. In cases of acute bleeding of head and neck lesions following trauma, tumours after radiotherapy, arteriovenous malformations, epistaxis or from iatrogenic origin, angiography plays a major role in localizing the source of bleeding and occluding the damaged vessel during the same session using the same endovascular approach.

Adolescent↗
PubMed2002

Movement control of manipulative tasks in patients with Gilles de la Tourette syndrome.

When a hand-held object is moved, grip and load force are accurately coordinated for establishing grasp stability. In the present work, the question was raised whether patients with Gilles de la Tourette syndrome (TS), who show tic-like movements, are impaired in grip-load force control when executing a manipulative task. To this end, we assessed force regulation during action patterns that required rhythmical unimanual or bimanual (iso-directional/anti-directional) movements. Results showed that the profile of grip-load force ratio was characterized by maxima and minima that were realized at upward and downward hand positions, respectively. TS patients showed increased force ratios during unimanual and bimanual movements, compared with control subjects, indicative of an inaccurate specification of the precision grip. Functional imaging data complemented the behavioural results and revealed that secondary motor areas showed no (or greatly reduced) activation in TS patients when executing the movement tasks as compared with baseline conditions. This indicates that the metabolic level in the secondary motor areas was equal during rest and task performance. At the neuronal level, this observation suggests that these cortical areas were continuously involved in movement preparation. Based on these data, we conclude that the ongoing activation of secondary motor areas may be explained by the TS patients' involuntary urges to move. Accordingly, interference will prevent an accurate planning of voluntary behaviour. Together, these findings reveal modulations in movement organization in patients with TS and exemplify degrading consequences for manual function.

Adult↗
PubMed2002

Use of diffusion-weighted magnetic resonance imaging in differentiating purulent brain processes from cystic brain tumors.

OBJECT: Brain abscesses and other purulent brain processes represent potentially life-threatening conditions for which immediate correct diagnosis is necessary to administer treatment. Distinguishing between cystic brain tumors and abscesses is often difficult using conventional imaging methods. The authors' goal was to study the ability of diffusion-weighted (DW) magnetic resonance (MR) imaging to differentiate between these two pathologies in patients within the clinical setting. METHODS: Diffusion-weighted MR imaging studies and calculation of the apparent diffusion coefficient (ADC) values were completed in a consecutive series of 16 patients harboring surgically verified purulent brain processes. This study group included 11 patients with brain abscess (one patient had an additional subdural hematoma and another also had ventriculitis), two with subdural empyema, two with septic embolic disease, and one patient with ventriculitis. Data from these patients were compared with similar data obtained in 16 patients matched for age and sex, who harbored surgically verified neoplastic cystic brain tumors. In patients with brain abscess, subdural empyema, septic emboli, and ventriculitis, these lesions appeared hyperintense on DW MR images, whereas in patients with tumor, the lesion was visualized as a hypointense area. The ADC values calculated in patients with brain infections (mean 0.68 x 10(3) mm2/sec) were significantly lower than those measured in patients with neoplastic lesions (mean 1.63 x 10(3) mm2/sec; p < 0.05). CONCLUSIONS: Diffusion-weighted MR imaging can be used to identify infectious brain lesions and can help to differentiate between brain abscess and cystic brain tumor, thus making it a strong additional imaging modality in the early diagnosis of central nervous system purulent brain processes.

Adult↗
PubMed2002

Contrast-enhanced 3D MR angiography of the carotid artery: comparison with conventional digital subtraction angiography.

BACKGROUND AND PURPOSE: Since 1996, several preliminary studies have shown the usefulness of contrast material-enhanced MR angiography for imaging supraaortic vessels. The aim of this study was to compare the accuracy of contrast-enhanced 3D MR angiography with that of digital subtraction angiography (DSA) in the evaluation of carotid artery stenosis. METHODS: A blinded comparison of first-pass contrast-enhanced MR angiography with conventional DSA was performed in 120 patients (240 arteries). MR angiography was performed with a 1.5-T magnet with gradient overdrive equipment, by using a coronal radiofrequency-spoiled 3D fast low-angle-shot sequence after the intravenous injection of gadodiamide. The guidelines of the North American Symptomatic Carotid Endarterectomy Trial for measuring stenosis of the internal carotid artery were applied on maximum intensity projection (MIP) images and conventional catheter angiograms. RESULTS: Grading of stenoses on MR angiograms agreed with grading of stenoses on DSA images in 89% of arteries. In the severe stenosis group (70-99%), agreement was 93%. All internal carotid occlusions (n = 28) and seven of nine pseudo-occlusions were accurately detected with contrast-enhanced MR angiography. The correlation between MR angiography and DSA for determination of minimal, moderate, and severe stenoses and occlusion was statistically significant (r = 0.91, P<.001). CONCLUSIONS: This investigation with a large number of patients confirms that contrast-enhanced MR angiography could become a diagnostic alternative to DSA in the treatment of patients with carotid artery disease.

Adolescent↗
PubMedDate not supplied

Hearing loss and vertigo in superficial siderosis of the central nervous system.

PURPOSE: Otoneurologic findings in patients with superficial siderosis (SS) of the central nervous system are described. A 20-year-old man with acute vertigo, dizziness, with a history of head trauma in childhood; an 87-year-old woman with severe disequilibrium appearing after peridural anesthesia; and a 55-year-old woman with recurrent episodes of positional vertigo and progressive ataxia, suffering from a lumbar ependymoma are described; all patients complained of progressive bilateral hearing loss and tinnitus. Methods and results Otoneurologic examination showed bilateral sensorineural hearing loss, disturbed ocular pursuit and optokinetic nystagmus, incomplete visual suppression of the vestibulo-ocular reflex during rotatory pendular testing, right hyporeflexia, and bilateral caloric areflexia. Cerebral magnetic resonance imaging (MRI) revealed rims of hypointensity surrounding the brainstem and linear hypointensities following the surface of the cerebellar folia. CONCLUSIONS: The etiology stems from subarachnoid hemorrhage, but the source of bleeding may remain obscure. Bilateral hearing loss is described in 95% and disequilibrium in 90% because of peripheral vestibular deficit and cerebellar ataxia. In patients with progressive bilateral cochleo-vestibular deficit of unknown etiology, MRI is the examination of choice to confirm SS.

Adult↗