[A biomechanical analysis of cyclical hand motor function: a pilot study in different Parkinsonian syndromes]. / Biomechanische Analyse zyklischer Handfunktionen : Eine Pilotstudie bei unterschiedlichen Parkinson-Syndromen.

INTRODUCTION: Clinical assessment of hand bradykinesia in Parkinson's disease (PD) focuses mainly on the frequency, amplitude and rhythm of movements, thereby subjectively evaluating the correct performance of hand movements. The aim of the study was to quantify hand bradykinesia with kinematic data in different Parkinsonian syndromes. PATIENTS AND METHODS: This retrospective study compared patients with idiopathic PD (IPD, n = 18), atypical Parkinson's syndrome (APS, n = 17), secondary Parkinson's syndrome (SPS, n = 18) and healthy controls (C, n = 18). All patients were receiving the best medical treatment. Hand movements were recorded using an ultrasound-system (Zebris®, Isny, Germany). Subjects were asked to perform pronation/supination of the forearm (diadochokinesis), flexion/extension of the hand (hand tapping) and tapping of the index finger. Mean amplitude, mean frequency and mean variability of movements were determined. RESULTS: APS patients had significant complex hand movement disability with reduced amplitude and frequency in combination with increased motion variability in all movement tasks. The key disturbance in the IPD group concerned the rhythm in hand tapping and index finger tapping in combination with moderately reduced velocity and range of motion in all conditions. The cyclical hand movement characteristics in SPS patients showed movement slowness with normal amplitude and variability in all motor conditions. CONCLUSION: Our results suggest that computerized quantitative analysis of cyclical hand movements can characterize and identify different representations of hand bradykinesia in different Parkinsonian disorders and hence may help clinicians to accurately assess therapeutic targets and outcome of interventions.

[Static posturography in selected Parkinson syndromes: quantitative analysis of postural control]. / Statische Posturographie bei ausgewählten Parkinson-Syndromen : Quantitative Beurteilung der posturalen Kontrolle.

OBJECTIVES: Idiopathic Parkinson's disease (IPD) is associated with postural disturbances and falls. The assessment of postural instability by the pull test may lead to inconclusive results. Static posturography measurements may give more reliable information regarding the differential diagnosis of Parkinson syndromes. PATIENTS AND METHODS: We compared results of the pull test and static posturography (sway area in eyes-open/eyes-closed conditions) in healthy controls (C) and patients with akinetic-rigid IPD (n=18), atypical Parkinson syndromes (APS; n=18) and secondary Parkinson syndromes (SPS; n=17). RESULTS: Static posturography and the pull test results did not differ significantly between controls and patients with akinetic-rigid IPD. APS patients had significantly greater postural sway areas when tested with eyes open compared to controls (APS: 16.89 vs C: 6.89 mm, p≤0.001) and IPD patients (APS: 16.89 vs IPD: 9.55 mm, p=0.005). The correlation in the APS group between the pull test and sway area in the eyes-open condition was significant (r=0.526, p=0.025). With eyes closed, postural instability in APS patients was not significantly increased (+2%, p=.847). SPS patients were more unstable under the eyes-closed condition compared to controls (sway area SPS: 26.29 vs C: 8.79 mm, p≤0.001), IPD patients (sway area SPS: 26.29 vs IPD: 11.06 mm, p≤0.001) and APS patients (sway area SPS: 26.29 vs APS: 17.28 mm, p=0.027), without a significant correlation to the pull test. The sway area in the SPS patients increased significantly by 67% (p=0.001) under the eyes-closed condition. CONCLUSION: Static posturography may be a helpful tool for the differentiation of Parkinson syndromes.

Thrombolytic therapy for acute stroke in Austria: data from the Safe Implementation of Thrombolysis in Stroke (SITS) register.

BACKGROUND: We aimed at determining the safety and efficacy of IV alteplase in Austrian versus non-Austrian centres as documented in the Internet-based registers Safe Implementation of Thrombolysis for Stroke - MOnitoring STudy (SITS-MOST) and - International Stroke Thrombolysis Register (SITS-ISTR). METHODS: We analysed patient data entered in the registers SITS-MOST and SITS-ISTR in the period December 2002 to 15 November 2007. RESULTS: Compared to the non-Austrian cohort (n=15153), the Austrian cohort (n=896) was slightly older [median, interquartile range (IQR): 70, 60-77 years vs. 69, 60-76 years, P=0.05] and included more women (44.6% vs. 41.0%, P=0.03). Austrian patients had a significantly shorter stroke onset-to-treatment time (OTT; median, IQR: 135, 105-160 min vs. 145, 115-170 min, P<0.0005). Symptomatic intracerebral haemorrhages were observed in 1.6% of Austrian and 1.7% of non-Austrian patients (P=0.82). At 3 months, 50.8% of Austrian and 53.0% of non-Austrian patients were independent (P=0.23), but death was less frequent in Austrian patients (12.1% vs. 14.9%, P=0.03). Multivariate analyses adjusted for demographic and baseline characteristics confirmed lower mortality at 3 months in the Austrian cohort (odds ratio 0.81, 95% confidence intervals 0.71-0.92, P=0.001). Longer OTT was associated with increased mortality at 3 months, with a hazard ratio of 1.02 (95% CI 1.01-1.03; P=0.005) for each 10-min increase in OTT. CONCLUSIONS: The implementation of intravenous alteplase for acute stroke has been safe and efficacious in Austrian centres. OTT and mortality were significantly lower in Austrian patients compared to non-Austrian SITS centres.

Worse blood pressure control in patients with cerebrovascular or peripheral arterial disease compared with coronary artery disease.

OBJECTIVES: Poor blood pressure (BP) control is common amongst patients with symptomatic atherothrombotic disease. It is unclear whether BP control and management differ across atherothrombotic disease subtypes. METHODS: We analysed the baseline data of 44,984 patients with documented coronary artery disease (CAD) only (n = 30,414), cerebrovascular disease (CVD) only (n = 11,359) and peripheral arterial disease (PAD) only (n = 3211) from the international REduction of Atherothrombosis for Continued Health Registry and investigated the impact of atherothrombotic disease subtype on BP control and use of antihypertensive drugs. RESULTS: The proportion of patients with BP controlled (<140/90 mmHg) was higher in CAD (58.1%) than in CVD (44.8%) or PAD (38.9%) patients (P < 0.001). Amongst patients with treated hypertension, CAD patients were more likely to have BP controlled than were CVD patients [odds ratio (OR) = 1.67; 95% confidence interval (CI) = 1.59-1.75] or PAD (OR = 2.30; 95% CI = 2.10-2.52). These differences were smaller in women than in men and decreased with age. Amongst treated patients, CAD patients were more likely to receive > or =3-drug combination therapies than were CVD (OR = 1.73; 95% CI = 1.64-1.83) or PAD (OR = 1.64; 95% CI = 1.49-1.80) patients. Adjustment for age, gender, waist obesity, diabetes, education level and world region did not alter the results. CONCLUSIONS: Coronary artery disease patients are more likely than CVD or PAD patients to have BP controlled and to receive antihypertensive drugs, particularly combination therapies. Promotion of more effective BP control through combination antihypertensive therapies could improve secondary prevention and therefore prevent complications in CVD and PAD patients.

High cardiovascular event rates in patients with asymptomatic carotid stenosis: the REACH Registry.

BACKGROUND AND PURPOSE: Data on current cardiovascular event rates in patients with asymptomatic carotid artery stenosis (ACAS) are sparse. We compared the 1-year outcomes of patients with ACAS > or =70% versus patients without ACAS in an international, prospective cohort of outpatients with or at risk of atherothrombosis. METHODS: The Reduction of Atherothrombosis for Continued Health Registry enrolled patients with either > or =3 atherothrombotic risk factors or established atherothrombotic disease. We investigated the 1-year follow-up data of patients for whom physicians reported presence/absence of ACAS at the time of inclusion. RESULTS: Compared with patients without ACAS (n = 30 329), patients with ACAS (n = 3164) had higher age- and sex-adjusted 1-year rates of transient ischaemic attack (3.51% vs. 1.61%, P < 0.0001), non-fatal stroke (2.65% vs. 1.75%, P = 0.0009), fatal stroke (0.49% vs. 0.26%, P = 0.04), cardiovascular death (2.29% vs. 1.52%, P = 0.002), the composite end-point cardiovascular death/myocardial infarction/stroke (6.03% vs. 4.29%, P < 0.0001) and bleeding events (1.41% vs. 0.81%, P = 0.002). In patients with ACAS, Cox regression analyses identified history of cerebrovascular ischaemic events as most important predictor of future stroke (HR 3.21, 95% CI 1.82-5.65, P < 0.0001). CONCLUSION: Asymptomatic carotid artery stenosis was associated with high 1-year rates of cardiovascular and cerebrovascular ischaemic events. Stroke was powerfully predicted by prior cerebrovascular ischaemic events.

Postprocedural high-density lipoprotein cholesterol predicts carotid stent patency at 1 year.

The durability of carotid artery stenting (CAS) is affected by the occurrence of myointimal proliferation and in-stent restenosis (ISR). We aimed to identify clinical, angiographic, and laboratory predictors of ISR, paying special attention to postprocedural metabolic factors. A total of 102 consecutive patients with successful CAS for > or =70% atherosclerotic internal carotid artery stenosis were followed up with neurological assessment and duplex sonography 1 day, 1 month, and 1 year after CAS. Lipid profile and hemoglobin A(1c) were tested at the 1-month follow-up visit. Ten (10%) patients had ISR > or =50% after 1 year. Compared with patients without ISR (n = 92), patients with ISR were more often current smokers (33% vs. 70%, P = 0.034) and had significantly lower 1-month high-density lipoprotein (HDL) cholesterol: median (range) 47 (24-95) mg/dl vs. 39.5 (25-50) mg/dl, P = 0.031. Multivariate logistic regression analyses identified 1-month HDL cholesterol >45 mg/dl as the only independent predictor of carotid stent patency at 1 year (P = 0.033, OR = 0.09, 95% CI 0.01-0.83). Postprocedural HDL cholesterol levels predict carotid stent patency at 1 year. With the possibility of elevation of HDL cholesterol by lifestyle changes and medication, this finding may have implications for the future management of patients undergoing CAS.

Timing of stenting of symptomatic carotid stenosis is predictive of 30-day outcome.

For patients with symptomatic carotid stenosis, benefit from carotid artery stenting (CAS) highly depends on the 30-day stroke and death rates. Identification of predictors of unfavourable outcome would help guide the patient selection. We analysed the influence of clinical and angiographic factors on the 30-day outcomes of 77 consecutive patients who underwent CAS for > or = 60% symptomatic carotid stenosis within 180 days of transient ischaemic attack or moderate stroke (modified Rankin Scale score < or = 3). The 30-day composite end-point for stroke (7.8%) and death of any cause (1.3%) was 9.1%. Patients with complicated CAS were older than patients with uncomplicated CAS (mean age 75.1 +/- 8.2 vs. 65.9 +/- 9.5 years, P = 0.015) and underwent stenting significantly earlier after the qualifying event: median delay 1.5 weeks (range: 0.2-3.0) vs. 3.2 weeks (range: 0.5-26), P = 0.004. In multivariate logistic regression analyses, age [odds ratio (OR) = 1.148; 95% confidence interval (CI): 1.011-1.304 and P = 0.033] and delay of treatment < 2 weeks (OR = 22.399; 95% CI: 2.245-223.445 and P = 0.008) remained the only variables significantly associated with 30-day outcome. CAS carries a considerable risk in old patients and when performed early (< 2 weeks) after the qualifying event. Future reports should address the timing of CAS.

Impact of instrumentation on DaTSCAN imaging: how feasible is the concept of cross-systems correction factor?

AIM: The aim of this investigation was to study the impact of applying different camera emission computed tomography (ECT) systems on semi-quantitative analysis of the novel dopamine transporter (DaT) radioligand [123I]-ioflupane (DaTSCAN) and whether applying a system-dependent correction factor is feasible to allow a migration of a ''normal'' reference data set between systems. METHODS: Two triple-head systems, PrismXP-3000 equipped with high resolution Fan-Beam (PRISM) and Irix (Philips Medical Systems, Europe) equipped with high resolution parallel whole collimators (IRIX), were compared in phantom and patient studies. Acquisition and quantification parameters were standardized. The anthropometric striatal calibration phantom (RSD Inc., CA, USA) at rising striatum: background ratios between 2-11 was studied. Fifty-one consecutive patients (25 females, age 64.5+/-11.9 years, and 26 males, age 60.6+/-12.7 years) were randomized to both cameras for acquisition time typically beginning 3.5 to 4.5 h after i.v. injection of 123I-Joflupane at 2.06+/-0.47 MBq/kg. Striatal uptake of the radioligand was categorized as normal or abnormal, and abnormal images were further subdivided into 3 severity levels. Striatum: cerebellum ratio (SCr) was determined by applying a fixed circular or rectangular striatal and fuzzy cerebellar regions. The effect of introducing scatter compensation (Sc) on quantification and on SCr was investigated. RESULTS: The regression coefficient (Rc) of SCr computed for both systems was close to identity (IRIX=0.999x (PRISM)+0.48 and 1.01x(PRISM)+0.86 for right and left striatum). Rc of SCr values in the phantom studies was closer to identity when Sc was added (IRIX=0.982x [PRISM]+0.724 with Sc vs 1.22x[PRISM]-0.32 without Sc). SCr values were higher for IRIX by 5-10%. Including Sc increased the percent recovery and the linear dynamic range for both systems; however, fan beam recovery decreased at low SCr values. The delineation of the striatal boundaries improved after applying Sc. Identifying the cerebellar region was easier with PRISM owing to significantly higher count statistics. Both systems performed equally well with respect to image quality. Visual scoring by 2 observers correlated significantly on the k-test (K: 0.883, T: 10, P<0.0001). CONCLUSION: A simple linear correction is applicable to ''normal'' reference data set to migrate from one system to another; however, data acquisition and quantification parameters need to be standardized. Higher recovery values are dependent on system resolution. The spatial distribution and image quality of DaTSCAN on different high-resolution systems applying standardized acquisition and reconstruction protocols is less operator dependent and does not affect visual rating of striatal DaT loss.

The natural course of Sneddon syndrome: clinical and magnetic resonance imaging findings in a prospective six year observation study.

Sneddon syndrome (SS) is increasingly recognised as a cause of ischaemic stroke in young adults. As the natural course of SS is not well defined, the authors performed a prospective six year clinical and neuroradiological follow up study. Thirteen patients with definite diagnosis of SS (livedo racemosa, characteristic skin biopsy, and history of stroke) entered a follow up programme that consisted of clinical examinations, two magnetic resonance imaging (MRI) investigations, and a comprehensive laboratory follow up protocol. The most frequent clinical findings during follow up had been headache (62%) and vertigo (54%). Seven patients (54%) suffered from transient ischaemic attacks, however, completed stroke has not been obtained during follow up. Progression of white matter lesions detected in MRI were present in 10 of 13 patients. Laboratory follow up protocol revealed transient antiphospholipid antibodies in two subjects. This prospective six year follow up study suggests a low incidence of territorial stroke but outlines progressive leucencephalopathy in patients with SS.

Rehabilitation approaches to stroke.

This article describes the state of the science in stroke rehabilitation dealing with three main topics: (1) General approach to stroke rehabilitation (stroke services and stroke units), (2) Neurophysiological and pharmacological interventions (facilitation of brain repair mechanisms) and (3) Experimental approaches (neuronal transplantation). Stroke rehabilitation is an active process beginning during acute hospitalisation, progressing to a systematic program of rehabilitation services and continuing after the individual returns to the community. There is world-wide consensus that stroke patients should be treated at specialised stroke unit with specially trained medical and nursing staff, co-ordinated multidisciplinary rehabilitation and education programs for patients and their families. Stroke Unit has been shown to be associated with a long-term reduction of death and of the combined poor outcomes of death and dependency, independent of patients age, sex, or variations in stroke unit organisations. No study has clearly shown to what extent the beneficial effect is due to specific rehabilitation strategies. New imaging studies in stroke patients indicate altered post stroke activation patterns, which suggest some functional reorganisation. Reorganisation may be the principle process responsible for recovery after stroke. It is assumed that different post ischaemic interventions like physiotherapy, occupational therapy, speech therapy, electrical stimulation, etc. facilitates such changes. Scientific evidence demonstrating the values of specific rehabilitation interventions after stroke is limited. Comparisons between different methods in current use have so far mostly failed to show that any particular physiotherapy, occupational therapy, speech therapy or stroke rehabilitation strategy is superior to another. Clinical data are strongly in favour of early mobilisation and training. Pharmacological interventions in animals revealed that norepinephrine, amphetamine and other alpha-adrenergic stimulating drugs can enhance motor performance after unilateral ablation of the sensory motor cortex. The clinical data in humans are rather contradictory. Neural grafting and neurogenesis are new potential modes of stroke therapy. Neural grafting enhanced functional outcome and reduced thalamic atrophy in rats only when combined with housing in enriched environments. Recent studies have shown that stem cells can differentiate to neurons in the adult human dentate gyrus in vivo.

To do or not to do? Magnetic resonance imaging in mild traumatic brain injury.

Clinical quantification of mild traumatic brain injury (MTBI) patients should be based on Glasgow coma scale (GCS) score, duration of loss of consciousness (LOC) and post-traumatic amnesia (PTA). In addition, a short practicable neuropsychological test might be useful in detecting minor memory and attentional deficits. MRI appears to be the most sensitive imaging method for assessing MTBI so far, but information regarding a visualized lesion is not usually utilized in the classification of MTBI. Magnetic resonance imaging (MRI) should, therefore, play a major role in any MTBI classification scheme. An appropriate MRI protocol has to be chosen using at least T1 weighted, T2 weighted, proton density and gradient-echo (GRE) sequence images, all in at least two planes, in order to detect and classify all lesions precisely. Owing to the fact that acute lesions may be missed, it is advisable to perform MRI in the first 2 weeks following trauma. Further research is necessary to clarify the relationship between chronic symptoms after MTBI and MRI abnormalities. It may, thus, be possible to provide optimal strategies for emergency department management, to define a group of patients with a need for acute and rehabilitative intervention after MTBI, and to predict their outcome.

Proton magnetic resonance spectroscopic imaging reveals differences in spinocerebellar ataxia types 2 and 6.

The objective of this study was to investigate cerebellar metabolism in patients with autosomal dominant cerebellar ataxia type 1 (ADCA-I) carrying two distinct mutations of spinocerebellar ataxia (SCA). Non-invasive image-guided proton magnetic resonance spectroscopy imaging (1H-MRSI) was performed in 4 patients with SCA2, and 3 patients carrying the SCA6 mutation. For MRSI, we employed a spin-echo sequence (TR = 1500 msec, TE = 135 msec, slice thickness = 15 mm, FOV = 240 mm) and a stimulated-echo sequence (TR = 1500 msec, TE = 20 msec, slice thickness = 15 mm, FOV = 240 mm). Measures included the peak integral ratios of neuronal and glial markers [N-acetylaspartate (NA) to creatine (Cr), choline-containing compounds (CHO) to Cr, and lactate (LAC) to Cr]. We found NA:Cr ratios were significantly lower in patients with SCA2 (40.4% lower) compared to patients carrying the SCA6 mutation. CHO:Cr ratios differed between the two mutations using short echo time (30.8% lower in SCA2), but not when applying long echo time 1H-MRSI. Measurements using long echo time revealed LAC peaks in all SCA2 patients. 1H-MRSI revealed metabolic differences between SCA2 and SCA6 patients. NA:Cr ratios were significantly lower in patients with the SCA2 mutation compared to the SCA6 mutation, and LAC signals were obtained in the cerebella of SCA2 patients. In addition, CHO:Cr ratios showed different behavior using short and long TE, indicating differences in relaxation times of choline compounds in SCA2.

The impact of peak saturation of the arterial input function on quantitative evaluation of dynamic susceptibility contrast-enhanced MR studies.

PURPOSE: The purpose of this work was to investigate systematic errors in dynamic contrast-enhanced MR perfusion studies due to peak saturation of the arterial input function (AIF) and to introduce a simple correction algorithm. METHOD: Computer simulations were performed to evaluate the influence of AIF peak saturation and to demonstrate the effectiveness of the presented correction algorithm. To compare the computer simulations with real MR data, MR perfusion measurements were performed on volunteers. RESULTS: The computer simulations show that AIF peak saturation leads to a systematic overestimation of cerebral blood volume (CBV) and cerebral blood flow (CBF) values, which was confirmed by comparing the obtained MR data with PET results. With use of an improved calculation algorithm correcting for AIF peak saturation, a significant improvement of the obtained CBV and CBF values could be demonstrated. CONCLUSION: Our results suggest that AIF peak saturation leads to a significant systematic error in the determination of CBV and CBF values and has necessarily to be taken into account for dynamic contrast-enhanced MR perfusion studies.

Magnetic resonance spectroscopy (MRS) in five patients with treated propionic acidemia.

Propionic acidemia is an inherited disorder caused by a defect of propionyl CoA carboxylase. Untreated, propionic acidemia leads to metabolic decompensation and toxic encephalopathy. We report on the magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) findings in five children who were properly treated by protein restriction and carnitine supplementation, during a phase of clinically and metabolically stable conditions. The examinations were performed on a whole-body 1.5 T scanner. During the observation period, from 1992 to 1996 we employed long echo time single-voxel spectroscopy and chemical shift imaging in addition to a conventional MRI protocol. The two children with the longest delay before onset of therapy showed cerebral atrophy. MRS yielded elevated lactate peaks in four of the children. These results indicate that MRS can detect metabolic alterations in the brains of children with propionic acidemia during metabolically stable conditions. The presence of lactate could be caused by hampered aerobic oxidation within the citrate cycle due to intracellular elevated propionic metabolites.

Survival with full neurologic recovery and no cerebral pathology after prolonged cardiopulmonary resuscitation with vasopressin in pigs.

OBJECTIVES: We sought to determine the effects of vasopressin and saline placebo in comparison with epinephrine on neurologic recovery and possible cerebral pathology in an established porcine model of prolonged cardiopulmonary resuscitation (CPR). BACKGROUND: It is unknown whether increased cerebral blood flow during CPR with vasopressin is beneficial with regard to neurologic recovery or detrimental owing to complications such as cerebral edema after return of spontaneous circulation. METHODS: After 4 min of cardiac arrest, followed by 3 min of basic life support CPR, 17 animals were randomly assigned to receive every 5 min either vasopressin (0.4, 0.4 and 0.8 U/kg; n = 6), epinephrine (45, 45 and 200 microg/kg; n = 6) or saline placebo (n = 5). The mean value +/- SEM of aortic diastolic pressure was significantly (p < 0.05) higher 90 s after each of three vasopressin versus epinephrine versus saline placebo injections (60 +/- 3 vs. 45 +/- 3 vs. 29 +/- 2 mm Hg; 49 +/- 5 vs. 27 +/- 3 vs. 23 +/- 1 mm Hg; and 50 +/- 6 vs. 21 +/- 3 vs. 16 +/- 3 mm Hg, respectively). After 22 min of cardiac arrest, including 18 min of CPR, defibrillation was attempted to achieve return of spontaneous circulation. RESULTS: All the pigs that received epinephrine and saline placebo died, whereas all pigs on vasopressin survived (p < 0.05). Neurologic evaluation 24 h after successful resuscitation revealed only an unsteady gait in all vasopressin-treated animals; after 96 h, magnetic resonance imaging revealed no cerebral pathology. CONCLUSIONS: During prolonged CPR, repeated vasopressin administration, but not epinephrine or saline placebo, ensured long-term survival with full neurologic recovery and no cerebral pathology in this porcine CPR model.

[Development and application of dynamic MR imaging in the evaluation of perfusion changes in rectal carcinoma during radiotherapy in clinical routine. Preliminary results]. / Entwicklung und Anwendung dynamischer MRT-Messungen zur Evaluierung von Perfusionsveränderungen bei Rektumkarzinomen unter Bestrahlung in der klinischen Routine. Erste Ergebnisse.

PURPOSE: This study was aimed at measuring microcirculatory parameters and contrast medium accumulation within the rectal carcinoma during fractionated radiotherapy in the clinical setting. MATERIAL AND METHODS: Perfusion data were observed in patients with rectal carcinoma (n = 8) who underwent a pre-operative combined chemo/radiotherapy. To acquire perfusion data, an ultrafast T1 mapping sequence was carried out on a 1.5-Tesla whole body imager to obtain T1 maps at intervals of 14 or 120 seconds. The overall measurement time was 40 minutes. The transaxial slice thickness (5 mm) was chosen in such a way that both arterial vessels and the tumor could be clearly identified. The gadolinium-DTPA (Gd-DTPA) concentration time curve was evaluated for arterial blood and tumor after intravenous constant rate infusion. The method allows a spatial resolution of 2 x 2 x 5 mm and a temporal resolution of 14 seconds. Patients underwent MR imaging before and at constant intervals during fractionated radiotherapy. RESULTS: Spatial and temporal resolution of dynamic T1 mapping was sufficient to reveal varying CM accumulation levels within the tumor and to identify the great arteries in the pelvis. In 6 patients Gd-DTPA concentration-time-curves were evaluated within the tumor during radiation. Pi index of Gd-DTPA versus radiation dose showed a significant increase in the first or second week of treatment, then either returned slowly to pretreatment level or a renewed increase was observed. The average Pi-value at the beginning was 0.16 (+/- 0.049), reaching highest level of 0.23 (+/- 0.058). In all groups the rise from the Pi-value to the Pi-maximum was statistically significant. The relative increase in perfusion ranged between 20 to 83%. CONCLUSION: The results show, that the ultrafast MR-technique described above provide a suitable tool for monitoring tumor microcirculation during therapeutic interventions and offers the potential for an individualized optimization of therapeutic procedures.

[Transcranial Doppler ultrasonography: stereotactically guided examinations using magnetic resonance angiography]. / Transkranielle Dopplersonographie--stereotaktisch geführte Untersuchungen unter Zuhilfenahme von Magnetresonanzangiographiedaten.

The accurate localization of specific intracranial blood vessels is a major difficulty with transcranial Doppler sonography (TCD). It was the purpose of this study to develop a system enabling stereotactic navigation during a TCD examination on the basis of high-resolution three-dimensional magnetic resonance angiographic (MRA) data. During TCD, the examiner is provided--on a computer screen--with a projected view of the respective intracranial vessel anatomy. With the aid of an optoelectronic localization system, the spatial orientation and localization of the US probe is determined in real time, and correlated with the patient's MRA data using a dedicated stereotactic mask. Subsequently, the US beam and the points of insonation are displayed on the screen overlaid on the vessel anatomy. In this way the examiner gains real time control of the localization of the respective intracranial vessel insonated. Points of insonation can be stored and recalled for follow-up examinations. In addition to the successful verification of the system, it was shown that, in comparison with conventional TCD, stereotactic navigation distinctly improves the reproducibility of repeat TCD examinations.