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Biomedical subjects

A Scherer

Publications and source records attributed to A Scherer.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Dynamic contrast-enhanced MRI for evaluating bone marrow microcirculation in malignant hematological diseases before and after thalidomide therapy].

PURPOSE: The aim of the study was to measure microcirculation parameters by dynamic contrast-enhanced MRI (d-MRI) and to evaluate the anti-angiogentic effects during treatment with thalidomide in different hematologic malignancies. METHODS: In 20 healthy normal persons, 20 patients with myelodysplastic syndromes (MDS), 10 patients with multiple myeloma (MM) and 10 with myelofibrosis (MF) a fast gradient echo sequence (Turbo fast low angle shot 2D) with a pump controlled bolus infusion of gadolinium-DTPA was performed before and in 18 of these after beginning (average of 4.3 months) of a thalidomide therapy. Two pharmacokinetic parameters--the amplitude and exchange-rate-constant--were calculated and a statistical comparison of these values between healthy persons and patients as well as a correlation with the clinical course was executed. RESULTS: Compared with the normal controls the patients showed a higher amplitude (normal persons 14.4 +/- 5.2, MDS 24.8 +/- 8.1, MF 35.9 +/- 4.3, MM 23.4 +/- 3.6) and exchange-rate-constant (normal persons 0.124 +/- 0.042, MDS 0.136 +/- 0.036, MF 0.144 +/- 0.068, MM 0.131 +/- 0.034). In the d-MRI-follow-up examinations a significant (p < 0.005) reduction of the amplitude and exchange rate constant values was evident in 14 of 18 patients undergoing a thalidomide therapy. Clinically all of these patients showed a therapy responding with complete or partial diseases remission. CONCLUSIONS: In patients with hematologic malignancies significantly higher d-MRI-microcirculation parameters of the lumbar spine can be demonstrated than in normal persons. During anti-angiogenetic treatment with thalidomide a decrease of these values was observed in case of a responding to therapy.

Adult↗
PubMed2002

[Sensitivity and significance of nuclear magnetic tomography findings of finger joints in rheumatoid arthritis].

Evaluation of the sensitivity and value of magnetic resonance imaging (MRI) findings and miniarthroscopic investigations (mini-/needle-arthroscopy = MA) of metacarpophalangeal (MCP) joints in patients with rheumatoid arthritis (RA). 30 patients with RA (21 female, 9 male), disease duration 2 months to 22 years and mean disease activity score (DAS) of 3.90 (range: 2.00-7.67) were examined by MRI of the hand (MCP region) and following MA of the MCP-II joints. MRI parameters for arthritis (synovial enhancement, synovial extension, cortical alterations, joint gap width) and corresponding macroscopic items (synovial extension, synovial hyperemia and vascularity, cortical alterations) by MA, scored semiquantitatively for synovitis (graduated from 0-III degree), were correlated. Additionally, normal radiographs of the hands were performed and compared with MRI findings concerning the detection of bony lesions. Evaluation of the 30 MRI and MA examination revealed highly significant correlations (p < 0.0001) for the parameters of synovial extension (MRI/MA), cortical alterations (MRI/MA) and synovial enhancement (MRI) compared to synovial hyperemia and vascularity (MA). We found significant correlations for parameters of activity and chronicity of RA pathology as assessed by MRI and MA. The detection rate of cortical lesions by MRI was two and a half times higher than by X-ray. MRI findings of MCP-II joints compared to those of MCP III-V showed that the MCP-II joint was more strongly involved.

Adult↗
PubMed2002

[Dynamic MRI of the lumbar spine for the evaluation of microcirculation during anti-angiogenetic therapy in patients with myelodysplastic syndromes].

PURPOSE: Evaluation of MRI perfusion parameters of the lumbar spine in patients with myelodysplastic syndromes (MDS) to determine the vascularisation and anti-angiogenetic effects of thalidomide therapy. MATERIAL AND METHODS: In 20 healthy normal persons and 28 MDS patients a dynamic contrast-enhanced MRI (d-MRI) of the lumbar spine was performed. After the initial d-MRI-investigation 24 of the 28 MDS patients received an anti-angiogenetic therapy with thalidomide. With an average of 4.2 months after the beginning of therapy a d-MRI-follow-up examination in 9 of these patients was performed. The amplitude and exchange-rate constant were calculated and a statistical comparison of these values between healthy persons and MDS patients as well as a correlation with the clinical course was executed. RESULTS: Compared with the normal controls the MDS patients showed a higher amplitude (normal persons: 14.4 +/- 5.2, MDS: 24.8 +/- 8.1) and exchange-rate constant (normal persons: 0.124 +/- 0.042, MDS: 0.136 +/- 0.036). In 7 of 9 MDS patients undergoing thalidomide therapy a reduction of the amplitude and exchange rate constant values was evident in the d-MRI follow-up examinations. Clinically these patients showed a therapy response with complete or partial disease remission. CONCLUSIONS: In MDS patients significantly higher d-MRI parameters can be demonstrated than in normal persons. Under anti-angiogenetic treatment these values decrease in case of a response to therapy. Thus, d-MRI seems suitable for the evaluation of anti-angiogenetic therapy effects.

Adult↗
PubMed2002

[Does dynamic contrast-enhanced MRI enable recognition of development of vertebral fractures in multiple myeloma?].

PURPOSE: To compare the value of MRI sequences with dynamic MRI measurements (d-MRT) for the assessment of risk of lumbar vertebral fractures in patients with multiple myeloma. MATERIAL AND METHODS: In 10 patients with multiple myeloma a sagittal T 1 -, T 2 -weighted spin-echo and an inversion-recovery sequence were performed. For dynamic measurements a fast gradient-echo sequence (turbo fast low angle shot 2 D) with machine-controlled Gd-DTPA administration was used. The presence of bone marrow abnormalities was determined and additionally the value of the highest signal increase (amplitude Alpha) was calculated for each of the 50 vertebral bodies. The subsequent development of vertebral fractures was assessed by MRI at a mean time interval of 6.2 months after the initial d-MRI. The pattern of marrow involvement and the amplitudes of the vertebral bodies that collapsed in the observation period were statistically compared with those of the vertebral bodies that did not collapse. RESULTS: During the follow-up period newly or progressive fractures occurred in 6 of 10 patients (7 of 50 vertebral bodies). The degree of pathological signal changes that preceded fractures was not significantly different (p > 0.05) from that of the other contemporary lesions identified in vertebral bodies that did not collapse in follow-up. In contrast, the amplitude of vertebrae that collapsed (A: 33.1 +/- 8.2) was significantly higher (p < 0.0001) than the amplitude of vertebrae that did not collapse (A: 16.7 +/- 4.2). The amplitude was a reliable predictor of vertebrae that collapsed in all cases. CONCLUSION: In contrast to the analysis of marrow lesions detected with non-dynamic MRI, this study suggests that the perfusion-parameter amplitude in dynamic contrast-enhanced MRI is a potentially relevant value to predict the risk of vertebral fractures in patients with multiple myeloma.

Adult↗
PubMed2001

Crystal structure of a dynamin GTPase domain in both nucleotide-free and GDP-bound forms.

Dynamins form a family of multidomain GTPases involved in endocytosis, vesicle trafficking and maintenance of mitochondrial morphology. In contrast to the classical switch GTPases, a force-generating function has been suggested for dynamins. Here we report the 2.3 A crystal structure of the nucleotide-free and GDP-bound GTPase domain of Dictyostelium discoideum dynamin A. The GTPase domain is the most highly conserved region among dynamins. The globular structure contains the G-protein core fold, which is extended from a six-stranded beta-sheet to an eight-stranded one by a 55 amino acid insertion. This topologically unique insertion distinguishes dynamins from other subfamilies of GTP-binding proteins. An additional N-terminal helix interacts with the C-terminal helix of the GTPase domain, forming a hydrophobic groove, which could be occupied by C-terminal parts of dynamin not present in our construct. The lack of major conformational changes between the nucleotide-free and the GDP-bound state suggests that mechanochemical rearrangements in dynamin occur during GTP binding, GTP hydrolysis or phosphate release and are not linked to loss of GDP.

Binding Sites↗
PubMed2001

Volumetric analysis of the pre-frontal regions: findings in aging and schizophrenia.

Frontal lobe dysfunction is thought to be involved in schizophrenia and age-associated cognitive decline. Frontal lobe volume changes have been investigated in these conditions using MRI, but results have been inconsistent. Few volumetric MRI protocols exist that divide the pre-frontal cortex into its sub-regions. In the present article, we describe a new method, which allows assessment of the superior, middle and inferior frontal gyrus, as well as the orbitofrontal and cingulate regions. The method uses multiple planes to help guide the anatomical decisions and combines this with a geometric approach utilizing readily apparent anatomical landmarks. Using this protocol, the frontal lobe volumes in young healthy subjects were contrasted with those of young schizophrenic patients and elderly healthy subjects (nine male subjects per group). The results showed that the method could be reproduced with high reliability (r(icc)> or =0.88-0.99). Schizophrenic as well as old subjects had specific significant reductions in the superior frontal gyrus and orbitofrontal regions compared with the young group. However, old and schizophrenic subjects did not differ from each another. No volume differences were observed in the other three regions assessed. Whether or not these volume reductions reflect a common pathological process remains to be investigated in future studies.

Adult↗
PubMed2001

Magnetic resonance imaging and miniarthroscopy of metacarpophalangeal joints: sensitive detection of morphologic changes in rheumatoid arthritis.

OBJECTIVE: To evaluate and characterize magnetic resonance imaging (MRI) findings in the metacarpophalangeal (MCP) joints of rheumatoid arthritis (RA) patients macroscopically, using miniarthroscopy (MA; needle arthroscopy). METHODS: The second MCP joint of the dominant hand of 22 RA patients (13 with various RA activities/stages; 9 with early RA [< or = 1.5 years' duration]) was examined by MRI followed by MA. Findings were evaluated by standardized semiquantitative measures of synovial and bony pathologic changes of the MCP joint, and were compared with the clinical and conventional radiologic findings. RESULTS: Erosions and pre-erosions were detected in 17 of 22 patients by MRI; 2 of the other 5 patients (all early RA) displayed bony changes on MA. All 10 joints with pre-erosions on MRI (grade I bony alterations on MRI) exhibited significant cartilaginous and bony pathology on MA. Synovial membrane pathology was detected in all but 1 patient by MRI and in all patients by MA, although findings of plain radiography were normal in 6 of the 22 patients and another 9 patients had a Larsen score of 1. Semiquantitative analysis of synovial findings of MRI revealed gadolinium diethylenetriaminepentaacetic acid enhancement as a significant marker of macroscopically varied synovial vascularity and hyperemia, both of which strongly correlated with clinical activity (as measured by the Disease Activity Score). The extent of synovitis/synovial proliferation shown by MA and MRI were significantly correlated with each other, but not with any other activity or damage parameter analyzed. CONCLUSION: In RA, both MRI and MA findings support early detection and staging of synovial changes. Ongoing longitudinal studies are aimed at evaluating the value of synovial proliferation as visualized by both methods.

Adult↗
PubMed2001

Proton MR spectroscopy of the lumbar spine in patients with glycogen storage disease type Ib.

Glycogen storage disease type Ib is an autosomal recessive inherited metabolic disorder resulting from deficiency of the microsomal glucose-6-phosphatase enzyme system. Six patients (three of which were treated with granulocyte colony stimulating factor) suffering from this disease were examined using image guided localized proton magnetic resonance (MR) spectroscopy. The relative signal intensities of water and lipid protons of the lumbar spine were determined. Comparison was made with iliac crest biopsies in the glycogen storage disease type Ib patients and localized proton MR spectroscopic values of the lumbar spine obtained by thirteen healthy volunteers. The data demonstrate for the first time that hypercellularity and myeloid hyperplasia in subjects with glycogen storage disease type Ib due to functionally impaired leucocytes results in a strongly increased water proton signal with a very low or absent lipid signal in localized proton MR spectroscopy. Upon granulocyte colony stimulating factor treatment, the water proton signal in the lumbar spine is not further augmented.

Adolescent↗
PubMed2001

Imaging diagnosis of retroperitoneal ganglioneuroma in childhood.

PURPOSE: To demonstrate the typical appearance of retroperitoneal ganglioneuromas on CT and MRI. MATERIALS AND METHODS: Retrospective analysis of diagnostic imaging (five CT scans, three MRI scans) in five children aged 3-15 years with the histological diagnosis of ganglioneuroma. RESULTS: The scans showed large (maximum 11 cm diameter), round or oval tumours with sharply defined margins. Intraspinal tumour involvement occurred in two cases. Comparing CTwith MRI, MRI was more accurate in defining the intraspinal involvement. The ganglioneuromas were hypodense on unenhanced CT and showed moderate enhancement with administration of contrast medium. In three patients, CT demonstrated tumour calcification with a disseminated speckled pattern. On T1-weighted MRI the tumours were homogeneous and hypointense, showing marked enhancement after gadolinium administration. On T2-weighted scans the tumours were hyperintense. CONCLUSION: At the time of diagnosis, retroperitoneal ganglioneuromas are generally large tumours that can be shown well by CT and MRI. The appearance on CT more readily suggests the diagnosis, but MRI is superior for documenting local or intraspinal tumour extension and lacks radiation load.

Adolescent↗
PubMed2001

Magnetic resonance imaging of bone marrow changes in Gaucher disease during enzyme replacement therapy: first German long-term results.

OBJECTIVE: Since 1991, enzyme replacement therapy (ERT) has been available for patients with Gaucher disease in Germany. The aim of this study was to analyse the MR pattern of bone marrow involvement and response to ERT in Gaucher disease type I. PATIENTS AND DESIGN: Thirty patients with Gaucher disease type I had MRI examinations prior to initiation of ERT with alglucerase/imiglucerase and during follow-up. Median MR follow-up and duration of ERT were 36 months. Coronal T1- and T2-weighted spin-echo images of the lower extremities were obtained to evaluate changes in the appearance of yellow marrow. MR images were categorized as having either a homogeneous (type A) or non-homogeneous patchy (type B) appearance of bone involvement and response to ERT was assessed by two radiologists. RESULTS: Overall, 19 of 30 patients (63%) showed an increased signal intensity on T1- and T2-weighted images after 36 months of ERT, consistent with partial reconversion of fatty marrow during treatment. Focal bone lesions surrounded by a low signal intensity (SI) rim did not respond to ERT, suggesting bone infarcts. Of the 11 patients with bone infarcts (low SI rim lesion), 82% had the non-homogeneous type B pattern (P=0.0021). In 86% of patients with splenectomy, bone infarcts were seen (P<0.05). CONCLUSIONS: MRI using T1- and T2-weighted spin-echo sequences is a valuable, non-invasive method for monitoring bone marrow response in patients receiving ERT. A non-homogeneous patchy signal intensity of bone marrow involvement correlates with the presence of bone infarcts (P=0.0021).

Adult↗
PubMed2001

[Signal changes of the bone marrow in MRI under long-term treatment with granulocyte colony-stimulating factors].

PURPOSE: Recurrent infections in patients with glycogen storage disease (GSD) type Ib resulting from an associated neutropenia are frequently treated with granulocyte colony-stimulating factors (G-CSF). The aim of this study was to evaluate the changes occurring in bone marrow by magnetic resonance imaging (MRI) in these patients. MATERIAL AND METHODS: The distal femoral and tibial bones of six patients with GSD Ib were evaluated by MRI. Four of these patients were treated with G-CSF for at least 3.9 to a maximum of 8.2 years (mean 5.8 years). The imaging sequences encompassed spin-echo as well as short-time inversion recovery sequences. 4 of the 6 patients had bone marrow aspirations. RESULTS: The patients who had undergone therapy with G-CSF showed a marked increase in signal strength in STIR sequences which encompassed the entire medullar cavity. In T1-weighted images these areas were hypointense. Biopsies obtained from these patients showed a bone marrow hypercellularity. The patients without G-CSF therapy showed the same signal intensity changes but with a more discrete and localized pattern in the metaphyseal cavities. CONCLUSION: In subjects with GSD Ib, an increased myelopoetic activity of the bone marrow which is intensified under long-term treatment with G-CSF can be demonstrated by MRI.

Adolescent↗
PubMed2001

[MRI of the cerebellopontine angle in patients with cleidocranial dysostosis].

PURPOSE: Cleidocranial dysostosis (CCD) is an autosomal dominant bone disorder in which deafness is common secondary to malformation of the middle ear structures. The study aimed at MRI evaluation of the cerebellopontine angle in 7 patients with a history of CCD--two generation spanned relatives. MATERIAL AND METHODS: Cranial MRI in 7 patients with CCD (4 women/3 men aged between 8 and 46 years) was performed. In two patients hearing disorders were present. The examinations encompassed multi-planar spinecho sequences of the cerebellopontine angle in 3-mm slice thickness before and after administration of contrast medium. RESULTS: The clinically most conspicuous female patient (hearing loss, ataxia, headache) showed a strongly contrast-enhancing tumor in MRI that was histologically proved to be an acoustic schwannoma. Concerning the other family members, no pathological findings were noted except for non-pneumatized mastoids. CONCLUSION: The first report of a patient with CCD and an acoustic schwannoma shows that in case of hearing loss in these patients also a retrocochlear cause must be considered.

Adolescent↗
PubMed2001

[MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages].

UNLABELLED: MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages. PURPOSE: Evaluation of MRI findings in the metacarpophalangeal (MCP) joints in patients with early (eRA) and chronical rheumatoid arthritis (cRA). MATERIAL AND METHODS: In 22 RA patients (9 with disease duration </= 1.5 years = eRA) the dominant hands were examined by MRI in coronal T(2) weighted turbo-spin-echo (TSE). T(1) weighted spin-echo (SE) sequences before and after injection of Gd-DTPA and fat-suppressed short tau inversion recovery (STIR) sequences, followed by miniarthroscopy (MA) of the MCP II joint after an interval of 24 hours. MRI and MA findings were assessed using standardised semiquantitative items of synovial and bony pathologies and a statistical comparison between eRA and cRA patients was performed. RESULTS: In MRI synovial proliferation was detected in 13/13 cRA and 8/9 eRA patients. It was statistically not significant; the degree of synovial proliferation was however lower in the eRA group. All eRA patients with synovial changes showed enhancement after administration of contrast medium, a marker which correlated with the clinical activity. In 2/13 cRA patients no uptake of contrast medium was evident. Bony erosions and strongly narrowing joint space correlated with disease duration and were documented significantly rarer in the eRA patients (1/9, 2/9) than in the cRA patients (9/13, 10/13). CONCLUSION: In RA patients, MRI of the metacarpophalangeal joints can detect specific pathological changes which are observed significantly more often in either early or chronic stages and which are associated with disease activity and duration.

Adult↗
PubMed2001

[Gaucher disease: MR evaluation of bone marrow features during treatment with enzyme replacement].

PURPOSE: Enzyme replacement therapy (ERT) arrests and reverses the hematological and visceral symptoms of adult Gaucher disease, the most frequent lysosomal storage disorder. There are only a few studies available evaluating bone disease during ERT. The aim of this study was to investigate the features of bone marrow (bm) by magnetic resonance imaging (MRI) in these patients during ERT. MATERIALS AND METHODS: MRI was performed prospectively in thirty adult type I Gaucher patients before and during ERT with a mean follow-up of 3 years. Spin-echo sequences (T(1)/T(2)) of the lower extremities were obtained and the reconversion (response) or lack of reconversion (non-response) to fatty marrow during treatment was analyzed. The morphological features of bm involvement, a homogeneous or non-homogeneous distribution of bm changes and focal bone lesions surrounded by a rim of reduced signal intensity (SI), were analyzed. RESULTS: Infiltration of bm by Gaucher cells is characterized by a reduction of SI on both T(1)- and T(2)-weighted sequences. Bone marrow responses were seen in 19 patients (63 %) during treatment. Focal bone lesions, surrounded by a rim of reduced SI, did not respond to ERT and correlated with a non-homogenous distribution of bone involvement and splenectomy. CONCLUSION: In adult patients with type I Gaucher disease receiving ERT, treatment effects on bone disease can be demonstrated by MRI using Spin-echo sequences due to the partial reconversion of fat marrow. A non-homogeneous type of signal appearance and a status post splenectomy correlate with the presence of bone infarcts.

Adult↗
PubMed2001

MR imaging of bone marrow in glycogen storage disease type IB in children and young adults.

OBJECTIVE: Patients with glycogen storage disease type IB have neutropenia and neutrophil dysfunction that predispose them to frequent infections, for which they are given granulocyte colony--stimulating factor. Because neutropenia is a consequence of defects in myeloid maturation, the bone marrow aspirations show hypercellularity due to myeloid hyperplasia. This study evaluated MR imaging of bone marrow in glycogen storage disease type IB with and without granulocyte colony-stimulating factor. CONCLUSION: As confirmed by the histologic results in bone marrow aspirations, abnormal findings on MR images of bone marrow in patients with glycogen storage disease type IB indicate an increased myelopoietic activity, which is augmented by treatment with granulocyte colony-stimulating factor.

Adolescent↗