Biomedical subjects

M Essig

Publications and source records attributed to M Essig.

At least 37 records · Page 2Linked to original sources

PubMed2001

Frontotemporal dementia: clinical, neuroimaging, and molecular biological findings in 6 patients.

Establishing the diagnosis in patients with clinical signs and symptoms suggesting primary degenerative disease with marked frontal lobe involvement is difficult. Neuroimaging methods, in particular positron emission tomography (PET) with the tracer 18fluoro-2-deoxyglucose (FDG) and cerebrospinal fluid (CSF) examination of beta-amyloid and tau-protein levels may give additional information. We report five patients with clinical and radiological features of degenerative dementia with predominantly frontal involvement and one patient with primary progressive aphasia Diagnostic work-up included computed tomography (CT), magnetic resonance imaging (MRI), PET and tau-protein and beta-amyloid level determination in CSF. While neuropsychological performance varied among patients, CT and MRI demonstrated persistently frontal lobe involvement. PET revealed corresponding changes with frontal hypometabolism, but in addition, four patients (among them two with no corresponding temporal changes in CT or MRI) showed a decreased glucose uptake in the temporal cortices. CSF samples from five patients revealed elevated beta-amyloid 1-42 and tau levels in three and two patients, respectively. Reduced beta-amyloid 1-40 was found in two patients. We conclude that occurrence of clinical symptoms of frontotemporal dementia is accompanied by frontal hypometabolism regardless of additional clinical findings. The value of determination of beta-amyloid and tau protein levels remains to be determined.

Aged↗

PubMed2001

Mechanical strains induced by tubular flow affect the phenotype of proximal tubular cells.

The effects of flow-induced mechanical strains on the phenotype of proximal tubular cells were addressed in vivo and in vitro by subjecting LLC-PK(1) and mouse proximal tubular cells to different levels of flow. Laminar flow (1 ml/min) induced a reorganization of the actin cytoskeleton and significantly inhibited the expression of plasminogen activators [tissue-type (tPA) activity: 25% of control cells; tPA mRNA: 70% of control cells; urokinase (uPA) mRNA: 56% of control LLC-PK(1) cells]. In vivo, subtotal nephrectomy (Nx) decreased renal fibrinolytic activity and uPA mRNA content detectable in proximal tubules. Nx also induced a reinforcement of the apical domain of the actin cytoskeleton analyzed by immunofluorescence. These effects of flow on tPA and uPA mRNA were prevented in vitro when reorganization of the actin cytoskeleton was blocked by cytochalasin D and were associated, in vitro and in vivo, with an increase in shear stress-responsive element binding activity detected by an electrophoretic mobility shift assay in proximal cell nuclear extracts. These results demonstrate that tubular flow affects the phenotype of renal epithelial cells and suggest that flow-induced mechanical strains could be one determinant of tubulointerstitial lesions during the progression of renal diseases.

Actins↗

PubMed2000

Radiation-induced regional cerebral blood volume (rCBV) changes in normal brain and low-grade astrocytomas: quantification and time and dose-dependent occurrence.

PURPOSE: New tumor-conformal radiation-treatment modalities have been established with the intention to spare normal tissue while maintaining or improving local tumor control. To document radiation-induced changes in normal brain and low-grade astrocytoma we measured regional cerebral blood volumes (rCBV) using a dynamic susceptibility-weighted contrast-enhanced MR technique (DSC-MRI). We attempted to assess pretherapeutic rCBV values and time- and dose-dependent changes following radiotherapy. METHODS AND MATERIALS: For prospective and longitudinal assessment of rCBV in normal brain and low-grade astrocytoma, 25 patients with histologically proven fibrillary astrocytoma (WHO Grade II) were examined before radiotherapy and during follow-up. Based on CT- and MR-data sets in a stereotactic setup, three-dimensional (3D) treatment planning was done. Radiotherapy was delivered using fractionated stereotactic radiotherapy (FSRT) to mean and median total doses of 60.9 and 60 Gy, respectively (range, 55.8-66 Gy). During MR imaging for treatment planning and follow-up examinations, 55 T2-weighted gradient echo images were acquired before, during, and after intravenous contrast bolus injection. The acquired signal-time curves were converted into concentration-time curves. The area under the tissue concentration-time curve was calculated and normalized to an integrated arterial input function. Thus, absolute rCBV values could be calculated. RESULTS: Pretherapeutic mean rCBV for normal gray (GM) and white brain matter (WM) were 7.2 +/- 2.7 and 3.6 +/- 1.5 mL/100 g tissue, respectively. Mean rCBV for astrocytoma was 6.5 +/- 3.7 mL/100 g tissue. After radiotherapy, rCBV for GM and WM was significantly reduced (p < 0.01) in high-dose areas (40-100% of total dose). A nonsignificant reduction was measured in low-dose areas (up to 40% of total dose). Reduction of rCBV in astrocytomas to a plateau level of 4.6 +/- 0.4 mL/100 g tissue was measured at 6 months after radiotherapy and remained stable in locally controlled tumors. CONCLUSION: Monitoring of rCBV changes in normal brain and low-grade astrocytoma was feasible using a DSC-MRI technique. The method was able to document radiation effects in low-grade astrocytoma, even if the majority of tumors showed no change in diagnostic MR-imaging. Radiation induced decrease of rCBV in GM and WM was correlated to total dose delivered to a tissue area, with high doses causing a significant decrease. Minor decline of rCBV in GM and WM outside high-dose areas after stereotactic radiotherapy confirms the efficacy to spare normal brain tissue by the use of modern conformal radiotherapy techniques. Nonetheless, a critical minimal dose initiating rCBV changes is yet unknown.

Adult↗

PubMed2000

Stereotactic fractionated radiotherapy for chordomas and chondrosarcomas of the skull base.

PURPOSE: To investigate the treatment outcome of patients suffering from skull base chordoma or chondrosarcoma after fractionated stereotactic radiotherapy. METHODS AND MATERIALS: We report 45 patients treated for chordoma or chondrosarcoma with postoperative fractionated stereotactic radiotherapy between 1990 and 1997. Patients had CT and MRI for 3D treatment planning performed under stereotactic guidance. Median dose at isocenter was 66.6 Gy for chordomas and 64.9 Gy for chondrosarcomas. MRI imaging was obtained in intervals after therapy to evaluate local relapse. Survival was calculated according to the Kaplan-Meier method. RESULTS: All chondrosarcomas had achieved and maintained local control and recurrence-free status at follow-up of 5 years. Local control rate of chordomas was 82% at 2 years and 50% at 5 years. Survival was 97% at 2 years and 82% at 5 years. At maximum follow-up of 8 years local control and survival rate of chordomas was 40% (82%). Clinically significant late toxicity developed in one patient. CONCLUSIONS: Our results demonstrate the feasibility of fractionated photon beam therapy and its success in the treatment of skull base tumors. Modern 3D treatment techniques provide superior results compared to conventional techniques. The role of high-precision radiotherapy compared to particle beam therapy in the treatment of these tumors is not yet fully clear and further research is needed.

Adolescent↗

PubMed2000

Structural studies of indium and thallium insertion into the framework of the cluster compound Ti2Nb6Cl14O4.

We have investigated the possibility of altering the electronic configuration of the niobium oxochloride cluster compound Ti2Nb6Cl14O4 (I) by doping this material with monovalent cations that can fit into cavities present in its cluster framework. The doping of I with In+ and Tl+ ions resulted in the formation of MxTi2Nb6Cl14-xO4+x (M = In, x = 0.10, 0.20, 0.27; M = Tl, x = 0.10, 0.20) in which the M+ ions partially occupy these cavities. The crystal structure analysis indicated that the additional charge provided by M+ ions is compensated by substitution of chlorine by oxygen, which leads to the cluster electronic configuration being intact. Crystal data: In0.272Ti2Nb6Cl13.728O4.272, space group C2/c (No. 15), a = 12.679(2) A, b = 14.567(2) A, c = 12.632(3) A, beta = 95.26(2) degrees, Z = 4; Tl0.196Ti2Nb6Cl13.804O4.196, space group C2/c (no. 15), a = 12.732(1) A, b = 14.607(2) A, c = 12.662(2) A, beta = 95.28(1) degrees, Z = 4.

Journal Article↗

PubMed2000

[Growth factors. Role in the progression of renal lesions].

FROM PATHOPHYSIOLOGY TO THERAPEUTICS: Nephrologists are faced with the continuing problem of helping patients avoid the onset or retard the development of end-stage renal failure. Despite the treatments available, the risk is still high for patients and the cost a heavy burden for the public health budget. These facts underline the importance of a detailed understanding of the mechanisms leading to the destruction of renal parenchyma in order to develop therapeutic strategies capable of slowing the inevitable progression of kidney lesions. GROWTH FACTORS: It is currently recognized that a major reduction in the number of functional nephrons, whatever the initial cause, leads in itself to a progressive deterioration of healthy nephrons and finally to complete destruction of the kidney. The underlying mechanisms remain largely unknown. One possible mechanism would involve an overexpression of several growth factors in the damaged renal parenchyma. We present in this review experimental data obtained with various approaches, including pharmacological and/or dietetic modulations and the establishment of transgenic mouse lines, to demonstrate the key role played by growth factors in the progression of renal lesions. The pathways followed by these growth factors in the process of renal destruction as well as certain elements leading to their overexpression are also discussed.

Animals↗

PubMed2000

Assessment of cerebral gliomas by a new dark fluid sequence, high intensity REduction (HIRE): a preliminary study.

The purpose of this study was to assess the diagnostic potential of a new dark fluid sequence, high intensity reduction (HIRE) in the diagnostic workup of patients with cerebral gliomas. The HIRE sequence utilizes a very long T(2) value of the cerebrospinal fluid (CSF) to suppress its high signal contribution in T(2)-weighted imaging by a image subtraction technique. Fifteen patients with histologically confirmed cerebral gliomas were examined with T(2)-weighted fast spin-echo (FSE), T(1)-weighted SE, fast fluid-attenuated inversion recovery (FLAIR), and HIRE imaging using identical scan parameters. In patients with enhancing lesions, fast FLAIR and HIRE were added to the contrast-enhanced T(1)-weighted SE images. Images were analyzed in a qualitative and quantitative evaluation. In the qualitative analysis, lesion detection, lesion delineation, and differentiation between enhancing and non-enhancing tumor tissue were assessed in a two-reader study. For the quantitative analysis, lesion-to-background and lesion-to-CSF contrast and contrast-to-noise ratios were determined in a region of interest analysis. HIRE achieved a significant reduction of the CSF signal without losing the high gray-to-white matter contrast of T(2)-weighted sequences. In the quantitative analysis, the contrast ratios of the HIRE images were lower compared with the FLAIR images due to a relatively high background and CSF signal. After administration of contrast media, HIRE images presented a significant signal increase in enhancing lesions, which subsequently increased the contrast and contrast-to-noise ratios. In the qualitative analysis, both readers found all tumors clearly delineated on HIRE imaging. Compared with T(2)-weighted FSE, the tumor delineation with HIRE was better in nine patients, equal in four patients, and less in one patient. Compared with the FLAIR images, HIRE was rated superior in three patients, equal in nine patients, and inferior in another three patients. Delineation of the enhancing tumor parts was possible with HIRE in all patients. HIRE images had significantly fewer image artifacts than FLAIR images due to reduced inflow effects. The T(2)-based HIRE sequence presented is an alternative to the T(1)-based FLAIR sequence, with the advantage of better gray-to-white matter contrast and shorter measurement time. Due to the subtraction technique, signal intensities from tissues with relaxation times in the range T(2 WM) < < T(2) < T(2 CSF) are also gradually affected, corresponding to their T(2) values. With respect to this unwanted effect, an improvement in HIRE imaging will be possible by using a self-weighted subtraction algorithm. In a forthcoming study this concept will first be tested on appropriate phantom fluids.

Adult↗

PubMed2000

Contrast optimization of fluid-attenuated inversion-recovery (FLAIR) MR imaging in patients with high CSF blood or protein content.

After surgical resection of a brain tumor or infection of the cerebrospinal fluid (CSF), elevated levels of blood by-products or protein contaminations are seen in the patient's CSF spaces. In fast fluid-attenuated inversion-recovery (FLAIR) imaging CSF signal is nulled by an appropriate choice of the inversion recovery time TI to improve the contrast between tissue structures adjacent to CSF-filled volumes. With contaminated CSF, however, the longitudinal relaxation time T(1) may change significantly, which results in an incomplete suppression in the FLAIR images, if standard inversion times are used. In this work, a fast single-voxel T(1) measurement pulse sequence with integrated T(1) calculation that allows determination the optimal TI value in 15 sec is presented. The method was tested in five patients after surgical resection of a brain tumor, where FLAIR MRI with and without contrast agent was performed to identify remaining tumor fragments at the margin of the resection cavity.

Brain Neoplasms↗

PubMed2000

[Improved tumor contrast and delineation in the stereotactic radiotherapy planning of cerebral gliomas and metastases with contrast media-supported FLAIR imaging].

BACKGROUND: FLAIR MR imaging has shown to be a valuable imaging modality in pathologic lesions of the brain including intra-axial brain tumors. The aim of the study was to assess the value of a FLAIR technique in the planning process of stereotactic radiotherapy in patients with cerebral gliomas and metastases. PATIENTS AND METHODS: Thirty-five patients with cerebral gliomas and 12 patients with a total of 39 cerebral metastases were examined by T2/PD-weighted fast spin-echo, fast FLAIR prior and after contrast and contrast enhanced T1-weighted spin-echo using identical slice parameters. The images were evaluated by using quantitative and qualitative criteria. Quantitative criteria were tumor-to-background and tumor-to-cerebrospinal fluid contrast and contrast-to-noise. The qualitative evaluation was performed as a multireader analysis concerning lesion detection, lesion delineation and image artifacts. RESULTS: In the qualitative evaluation (Table 3 and 6), all readers found the fast FLAIR images to be superior to fast spin-echo in the exact delineation of cerebral tumors (p < 0.001) and the delineation of enhancing and non enhancing tumor parts. Fast FLAIR was superior in the delineation of cortically located and small lesions but was limited in lesions adjacent to the ventricles. Fast FLAIR provided a significantly better tumor-to-CSF contrast and tumor-to-CSF contrast-to-noise (p < 0.001) (Tables 1, 2a, 2b, 4, 5). The tumor-to-background contrast and tumor-to-background contrast-to-noise of the fast FLAIR images were lower than that of T2-weighted spin-echo images but were significantly increased after the application of contrast media. FLAIR images had more image artifacts, but the image interpretation was not influenced. CONCLUSIONS: FLAIR MR imaging was found to be a valuable sequence in the planning protocol of stereotactic radiotherapy. The concurrent presentation of enhancing and non enhancing tumor tissue on contrast enhanced fast FLAIR imaging enables to use a single imaging sequence in the treatment protocol. This enables to load a reduced image amount into the radiotherapy planning software, is therefore time saving and reduces potential errors.

Adolescent↗

PubMed2000

[Functional magnetic resonance tomography in neuroradiology].

The assessment of cerebral functions has long been the domain of positron-emission tomography and single photon emission computed tomography. The use of rapid imaging sequences and contrast agents enables physiological and pathophysiological cerebral processes to be assessed and monitored by magnetic resonance imaging. Both T1- and T2-weighted contrast-enhanced fast imaging sequences can be used to assess tissue perfusion, vascularity, and microcirculation by applying models developed in nuclear medicine. The diffusion of water molecules and hemodynamic aspects of the macrovasculature can also be monitored. Functional magnetic resonance (MR) imaging enables the visualization of neuronal function and activity, and MR spectroscopy makes possible the metabolic mapping of lesions and surrounding tissue. The advantages of MR techniques includes their low invasiveness, multiplanar imaging ability, and lack of radiation. This contribution discusses the clinical use of functional MR imaging methods and their role in neuroradiological diseases. Measuring perfusion and diffusion allows detailed insight into the pathophysiology of cerebral ischemia and is already being used routinely in acute ischemic stroke. Dynamic MR angiography enables the hemodynamic assessment of vascular malformations. In CNS neoplasms these imaging techniques can improve lesion characterization and the selecting, planning, and monitoring of therapy. Functional MR imaging techniques have also revolutionized the study of psychiatric illness; however, their clinical utility here is still limited. Initial results in patients with dementia and schizophrenia have provided insight into the pathophysiological changes of these diseases.

Brain↗

PubMed2000

[Quantitative recording of renal function with magnetic resonance tomography].

AIM: To show the potential of various methods in magnetic resonance imaging for the evaluation of renal function. MATERIAL AND METHODS: A combined assessment of renal morphology, renal hemodynamics and function is proposed. Various techniques are explained, including multiphasic 3D gadolinium MR angiography, MR phase-contrast flow measurements, quantitative perfusion measurements with intravascular contrast agents, and MR renography and MR urography. The use of these techniques is demonstrated for renovascular diseases. RESULTS: The combined use of these techniques allows renal artery stenosis to be accurately detected and evaluation of renal blood flow, perfusion, glomerular filtration rate, and renal excretion. Based on true quantitative parameters, the hemodynamic and functional significance of the stenosis can be assessed. Renovascular diseases can be differentiated from renoparenchymal disease. CONCLUSION: For the assessment of renal function, functional magnetic resonance imaging techniques are an important alternative to nuclear medicine. The predictive value regarding the effect of revascularization is currently under investigation.

Contrast Media↗

PubMed2000

[HIRE (high intensity reduction). New cerebrospinal fluid suppressed T2-weighted imaging sequence].

PURPOSE: The HIRE sequence utilizes the very long T2 value of CSF to suppress its high signal contribution in T2-weighted imaging by an image subtraction technique. METHODS: To assess the diagnostic potential of a new dark fluid sequence HIRE (High Intensity REduction) in the diagnostic work-up, 20 patients with histologically confirmed cerebral gliomas were examined with T2-weighted FSE, T1-weighted SE, fast FLAIR and HIRE using identical scan parameters. In patients with enhancing lesions fast FLAIR and HIRE were added to the contrast-enhanced T1-weighted SE images. Images were analyzed in a qualitative and quantitative evaluation. In the qualitative lesion analysis, lesion delineation and differentiation between enhancing and non enhancing tumor tissue were by two readers. For the quantitative analysis lesion-to-background and lesion-to-CSF contrast and contrast to noise ratios were determined in an region of interest analysis. RESULTS: HIRE achieved a significant reduction of the CSF signal without loosing the high gray-to-white matter contrast of T2 weighted sequences. In the quantitative analysis, the contrast ratios of the HIRE were lower compared to the FLAIR images due to a relative high background and CSF signal. After the application of contrast media HIRE images revealed a significant signal increase in enhancing lesions, which subsequently increased the contrast and contrast-to-noise ratios. In the qualitative analysis, both readers found all tumors clearly delineated on HIRE imaging. Compared to T2-weighted FSE the tumor delineation with HIRE was better in nine patients, equal in four patients and less in one patient. Compared to the FLAIR images HIRE was rated superior in three patients, equal in nine patients and inferior in another three patients. Delineation of the enhancing tumor parts was possible with HIRE in all patients. HIRE images present significant less image artifacts than FLAIR images due to reduced inflow effects. CONCLUSIONS: The presented T2 based HIRE sequence is an alternative to the T1 based FLAIR sequence with the advantage of a better gray to white matter contrast and shorter measurement time. Due to the subtraction technique signal intensities from tissues with T2 relaxation times in the range between white matter and CSF are also partially affected depending on their T2 values. With respect to this undesired effect, an improvement in HIRE imaging will be expected by a self-weighted subtraction algorithm.

Artifacts↗

PubMed2000

Disappearance of tumor contrast on contrast-enhanced FLAIR imaging of cerebral gliomas.

Contrast-enhanced fluid-attentuated inversion recovery (FLAIR) magnetic resonance (MR) imaging has shown to be a valuable diagnostic modality in the assessment of cerebral gliomas. In this study we report of a potential pitfall regarding the delineation of enhancing tumor parts on contrast enhanced FLAIR imaging. In a limited number of patients, the administration of gadolinium obscures the area of contrast enhancement on contrast enhanced FLAIR images. Therefore the delineation of the macroscopic tumor parts, which are of great importance for the treatment planning is substantially worsened.

Adult↗

PubMed2000

Percutaneous vascular intervention based on gadolinium-enhanced MR angiography.

PURPOSE: To determine if gadolinium-enhanced magnetic resonance angiography (Gd-MRA) could be used to reliably plan percutaneous vascular procedures. PATIENTS AND METHODS: Over the course of 13 months, 31 patients underwent attempted percutaneous intervention solely on the basis of a preceding Gd-MRA study. A total of 49 arterial segments were targeted (28 extremities, 21 visceral). Five segments in four patients were not treated (less impressive disease severity on conventional catheter angiography [CA] in four segments, diffuse intrarenal atherosclerosis in one segment). Interventions attempted were percutaneous transluminal angioplasty (n = 10), angioplasty with stent placement (n = 29), and thrombolysis (n = 3). Interventions were successful in all segments, except two because of the inability to cross an occlusion. RESULTS: Good to strong correlation was noted between Gd-MRA and CA regarding stenosis severity and length and the presence of poststenotic dilatation. MRA underestimated the complexity of stenosis. Subjective quality and preintervention confidence were excellent in the majority of MRA studies and satisfactory in the rest. The overall value in "procedural planning" was judged high in 40 segments, satisfactory in five segments, and poor in four segments. The procedural planning and positive predictive values of MRA were significantly lower for visceral arteries compared to iliac and peripheral arteries. CONCLUSION: In most cases, Gd-MRA reliably yielded the anatomic and diagnostic information necessary to plan percutaneous vascular interventions noninvasively and without iodinated contrast. In the authors' practice, Gd-MRA is becoming a key imaging modality in the workup of patients in whom percutaneous intervention is anticipated.

Adult↗

PubMed2000

[Cerebrospinal fluid protein tau levels in the differential diagnosis of Alzheimer's disease].

Tau protein concentration in cerebrospinal fluid was determined in 55 patients with Alzheimer's disease (AD), 18 patients with vascular dementia (VD), 19 patients with dementia caused by other disorders and 14 patients with major depression. Significantly (p < 0.05) elevated protein tau concentrations were found in AD patients (564.5 +/- 275.5 pg/ml) compared to all other patient groups (VD: 406.5 +/- 263.9 pg/ml; other dementia: 275.0 +/- 135.4 pg/ml; depression: 212.9 +/- 115.6 pg/ml). However, tau levels in AD patients covered a broad range (163.2 pg/ml-1200 pg/ml). AD patients with tau levels below the 25%-percentile of the distribution (among them a high percentage of patients with presenile onset) showed tau levels similar to those of the patients with late life depression. No significant correlations between tau levels and clinical variables such as severity of dementia, age, age of onset, duration of illness, and cerebral changes as assessed by volumetric magnetic resonance imaging could be demonstrated. Similarly, we could not find an influence of either APO-E genotype or psychotropic medication on the tau levels in AD patients. In accordance with other studies our results confirm elevated tau levels in AD compared to elderly not demented control subjects. Comparing groups, this finding applies as well with respect to VD and other dementing disorders. However, elevated tau levels cannot be detected in a subgroup of AD patients. This finding needs to be further investigated in future studies.

Aged↗

PubMed2000

Arteriovenous malformations: assessment of gliotic and ischemic changes with fluid-attenuated inversion-recovery MRI.

RATIONALE AND OBJECTIVES: To evaluate the diagnostic potential of fluid-attenuated inversion-recovery (FLAIR) MRI in the assessment of patients with cerebral arteriovenous malformations (AVMs) and to correlate the MR findings with clinical symptoms, in particular, perilesional gliosis and ischemic changes. METHODS: Forty-five patients with cerebral AVMs were examined with FLAIR and conventional T1- and T2-weighted MRI by using identical slice parameters. Images were assessed in a two-reader study for detection and delineation of gliotic and ischemic tissue. Also, the extent of the flow void phenomenon and image artifacts were evaluated. RESULTS: FLAIR MRI was rated superior to the conventional T2-weighted fast spin-echo imaging in the assessment of intralesional and perilesional gliosis. The superior delineation was a result of the suppression of cerebrospinal fluid, mild T1 weighting, and the more pronounced flow void phenomenon. There was no significant correlation between the extent of gliosis and the clinical symptoms. However, larger AVMs had more extensive signal changes. CONCLUSIONS: FLAIR is a valuable MRI technique to assess gliotic and ischemic changes in or close to cerebral AVMs. Because gliotic and ischemic changes are common findings and are known to be associated with epilepsy, in the assessment of these patients FLAIR is clinically useful and may guide decisions about treatment-for instance, the extent of surgical resection of the potential epileptogenic focus.

Adult↗

PubMed2000

Effects of three different doses of a bolus injection of gadodiamide: assessment of regional cerebral blood volume maps in a blinded reader study.

BACKGROUND AND PURPOSE: Reconstruction of first-pass bolus information to derive regional cerebral blood volume (rCBV) maps is commonly performed in many centers; however, various protocols with different doses of paramagnetic contrast injections have been reported. We evaluated the dose dependency of rCBV maps in a brain tumor population by using three different doses of gadodiamide injection to evaluate their diagnostic accuracy in blinded reader sessions. METHODS: Eighty-three patients with intraaxial brain tumors (72 gliomas) were studied at three centers and randomized to receive a bolus injection of 0.1, 0.2, or 0.3 mmol/kg per body weight of gadodiamide. rCBV maps were generated from T2*-weighted gradient-echo echoplanar sequences at 1.5 T. Data processing was performed according to the indicator dilution theory. RESULTS: The mean contrast-to-noise ratio (CNR) was significantly different between gadodiamide doses of 0.1 and 0.2 mmol/kg (CNR = 8.7 and 15.7) and between 0.1 and 0.3 mmol/kg (CNR = 17.7). No significant difference was found between doses of 0.2 and 0.3 mmol/kg. Sensitivity for the differentiation of benign and malignant brain tumors was 80%, 95%, and 91%, and specificity was 45%, 54%, and 43% by blinded readings at 0.1, 0.2, and 0.3 mmol/ kg, respectively, as compared with histologic findings. Nonblinded readings had a sensitivity of 83%, 100%, and 90% and a specificity of 82%, 100%, and 73% at 0.1, 0.2, and 0.3 mmol/kg, respectively. CONCLUSION: A dose of 0.2 mmol/kg of gadodiamide is recommended for reconstruction of rCBV maps if data are acquired with the T2*-weighted protocol described.

Blood Volume↗

PubMed1999

Treatment of cerebral Langerhans cell histiocytosis.

Cerebral Langerhans cell histiocytosis (LCH) is a rare granulomatous disorder which may be primary or secondary or solitary or multiple. Brain structures outside the hypothalamic-pituitary axis are only scarcely involved, even in multisystem varieties. Since there are neither controlled therapeutic trials nor systematic analyses of hitherto reported cases, optimal treatment strategies are not known. To evaluate the effect of different treatment modalities, we analyzed previous reports of extrahypothalamic LCH back to 1980 in which the diagnosis was made on the basis of examination of cerebral tissues. Thirty-five histologically examined cases were identified, including 10 patients presenting with multiple cerebral lesions. Adding one own case followed up for 10 years, 16 patients had cerebral involvement secondary to multisystem LCH, while another 20 patients had primary cerebral LCH. The peak incidence was far beyond the pediatric range for both primary and secondary cerebral LCH. Localized lesions can be treated successfully by surgery or radiation following biopsy. Chemotherapy may be an additional option. Multiple lesions can tentatively be controlled by chemotherapy and, possibly, radiation. The ultimate outcome is determined by whether or not recurrencies or de-novo lesions will appear and the course of the systemic disease. Studies addressing the effects of therapy in cerebral LCH are urgently needed.

Adolescent↗