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Biomedical subjects

U Büll

Publications and source records attributed to U Büll.

At least 37 records · Page 2Linked to original sources
PubMed1999

[The multimodal integration, correlation and fusion of morphology and function: the methods and initial clinical applications].

Besides the pure visual diagnosis of morphology in comparison with function, digital multimodal image analysis is steadily gaining in importance. Digital image processing is used in integration, correlation and fusion of topographically identical image data. After defining these terms and describing the acquisition techniques and influence parameters, this article reviews the methods of multimodal image processing, with emphasis on correlation methods. It also gives a short description of special methods in nuclear medicine. The clinical part briefly reviews the clinical use as well as the progress achieved and the benefits expected for diagnostic applications.

Diagnostic Imaging↗
PubMed1999

[Aspects of cerebral connnectivity in schizophrenia. A comparative CBF study on treated schizophrenics before and after medication].

INTRODUCTION: The hypothesis of prefrontal-temporolimbic disconnectivity, considered to be relevant to the pathogenesis of schizophrenia, has been tested in 29 drug-naive schizophrenic patients, comparing the active with the remitted state. METHOD: A pre-post-treatment design was applied to 29 drug-naive schizophrenic inpatients, 18 male, mean age 32 years, 11 female, mean age 32 years, mean duration of illness 29 months. Psychopathological symptoms were assessed using PANSS, regional cerebral blood (rCBF) was measured by HMPAO-SPECT. RCBF values were calculated for 21 regions of interest after normalization to cerebellum, and plotted by Euklidean diagrams using the ordinal, nonmetric, multidimensional scaling method. These diagrams represent similarity correlations visualized as spatial distances. High correlation levels as indicated by small Euklidean distances have been interpreted as functional connectivity. RESULTS: In active schizophrenia, functional disconnectivity was observed between prefrontal and temporal cortex. After remission, connectivity was improved between temporolimbic and frontal cortex. CONCLUSION: Comparing active with remitted schizophrenia, a frontotemporal disconnectivity appears. Temporolimbic as well as frontolimbic connections restitute parallel to psychopathological improvement.

Adolescent↗
PubMed1999

F-18-FDG positron imaging in oncological patients: gamma camera coincidence detection versus dedicated PET.

AIM: Of the present study was to investigate the feasibility of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients with a dual head gamma camera modified for coincidence detection (MCD). METHODS: Phantom studies were done to determine lesion detection at various lesion-to-background ratios, system sensitivity and spatial resolution. Thirty-two patients with suspected or known malignant disease were first studied with a dedicated full-ring PET system (DPET) applying measured attenuation correction and subsequently with an MCD system without attenuation correction. MCD images were first interpreted without knowledge of the DPET findings. In a second reading, MCD and DPET were evaluated simultaneously. RESULTS: The phantom studies revealed a comparable spatial resolution for DPET and MCD (5.9 x 6.3 x 4.2 mm vs. 5.9 x 6.5 x 6.0 mm). System sensitivity of MCD was less compared to DPET (91 cps/Bq/ml/cmFOV vs. 231 cps/Bq/ml/cmFOV). At a lesion-to-background ratio of 4:1, DPET depicted a minimal phantom lesion of 1.0 cm in diameter, MCD a minimal lesion of 1.6 cm. With DPET, a total of 91 lesions in 27 patients were classified as malignant. MCD without knowledge of DPET results revealed increased FDG uptake in all patients with positive DPET findings. MCD detected 72 out of 91 DPET lesions (79.1%). With knowledge of the DPET findings, 11 additional lesions were detected (+12%). MCD missed lesions in six patients with relevance for staging in two patients. All lesions with a diameter above 18 mm were detected. CONCLUSION: MCD FDG imaging yielded results comparable to dedicated PET in most patients. However, a considerable number of small lesions clearly detectable with DPET were not detected by MCD alone. Therefore, MCD cannot yet replace dedicated PET in all oncological FDG studies. Further technical refinement of this new method is needed to improve image quality (e.g. attenuation correction).

Adult↗
PubMed1999

[Quantification of repositioning errors in PET studies through superimposition of emission and transmission scans. Comparison between acquisition with and without repositioning].

AIM: The purpose of this study was to quantify positioning discrepancies between emission (E) and transmission (T) scan using image fusion. A direct comparison of one-step and two-step acquisitions was performed where all studies were analyzed in respect to artifacts caused by inaccurate positioning. In addition, phantom measurements were conducted to estimate the consequences of repositioning errors on standardized uptake value calculations (SUV). METHODS: 40 patients were examined by two-step whole-body scans using PET and 15 patients were subject to one-step examinations in the head/neck area. Repositioning between the scans was achieved by a laser matrix positioning system in combination with external body markings. After reconstruction and image fusion of the scans, the positioning discrepancies were measured as the distances between the outer boundaries of E and T in four different body regions. Additional evaluations of the SUV by increasing E-T dislocation were performed using a Jaszczak phantom containing hollow spheres. RESULTS: For the two-step acquisitions, the mean spatial deviations along the three orthogonal axes x, y, and z were between 8.9 mm and 13.8 mm, whereas for the one-step examinations mean values between 3.5 mm and 4.3 mm were determined (level of significance in each direction p < 0.0001). Artifacts were found in 47.5% of the whole body scans, but in none of the head/neck studies. The development of image artifacts was simulated by phantom studies. In contrast, the deviations of the computed SUV caused by increasing positioning discrepancies were minimal because of the minimal differences between the attenuation coefficients of the media involved. CONCLUSION: The presented data show that an artifactfree reconstruction of attenuation-corrected studies requires a precise positioning of the patient. One-step examination protocols without repositioning are advantageous due to the significantly lower positioning discrepancies. The additional reconstruction of nonattenuation-corrected studies has proven to be useful in discovering image artifacts and is therefore recommended.

Artifacts↗
PubMed1999

[Bone scintigraphy and rhenium radioisotope management in the course of metastatic prostatic cancer].

A 78-year-old patient with prostate cancer and osseous metastases had a pain symptomatic. In the Urology he was treated with antiandrogenes. The outcome of the bone scintigraphy showed a super bone scan with normalization after antiandrogene-therapy which seemed to be a sign of remission, before he showed a progressive form with multiple osseous metastases. Pain could not be treated with non steroidal antiphlogistics and opiates, so the indication for treatment with Rhenium-186-HEDP was given in this case.

Aged↗
PubMed1999

Diagnostic evaluation of malignant head and neck cancer by F-18-FDG PET compared to CT/MRI.

AIM: Evaluation of F-18-FDG PET in comparison to CT/MRI as diagnostic tool in primary and recurrent head and neck cancer. METHODS: 78 F-18-FDG PET studies were performed in 71 patients with known or suspected primary (n = 48) or recurrent (n = 30) head and neck cancer and compared to CT (n = 75) or MRI investigations (n = 3) concerning detection of the primary or recurrent tumor and detection of regional lymph node metastases in the ipsilateral and contralateral neck sides. Glucose uptake (SUV) of PET findings was correlated to tumor location, grading and dignity of the lesion. RESULTS: Sensitivity and specificity for PET in detection of primary tumors were 87%* and 67%, respectively (CT/MRI 67%* and 44%) (*p < 0.05), in detection of local recurrence 86% and 75%, respectively (CT/MRI 57% and 92%), in detection of necks affected by lymph node metastases 80% and 92%, respectively (CT/MRI 80% and 84%). Laryngeal, buccal (cheek) and salivary gland tumors had significant lower glucose uptake (SUV) when compared to tumors of the hypopharynx (p < 0.05). G1-tumors (mean SUV 4.26) had significant (p < 0.05) lower glucose uptake when compared to G2- and G3-tumors (mean SUV 7.73 and 8.19, respectively). Mean SUV of malignant PET findings (7.88) was significant (p < 0.05) higher than mean SUV of benign PET findings (5.70). However, a SUV threshold to improve diagnostic accuracy could not be defined. CONCLUSIONS: F-18-FDG PET is significantly more accurate than CT/MRI for detection of head and neck cancer. Both methods are valuable for detection of cervical lymph node metastases. Glucose uptake shows correlation to histological grading. A quantitative SUV analysis does not improve diagnostic accuracy.

Female↗
PubMed1999

[Clinical value of FDG PET for therapy monitoring of malignant lymphoma--results of a retrospective study in 72 patients].

AIM: Of the present retrospective study was to validate the clinical value of FDG-PET for therapy control of malignant lymphoma. METHOD: 72 patients (41 non-Hodgkin lymphomas, 29 Hodgkin's disease, 2 unclassified) received static FDG-PET scans of initially involved regions (n = 53) or of the entire neck and trunk (n = 19) after therapy. CT imaging (n = 70) and serum LDH measurement (n = 64) were also performed. Results were validated either by biopsy (n = 7) or by clinical follow-up (n = 65). The predictive value of PET was analysed in relation to different prognostic factors (stage, recurrence status, number of prior therapy regimen). RESULTS: PET obtained a sensitivity of 88%, a specificity of 83% and an overall accuracy of 85% for detection of residual disease. The values for CT were 84%, 31% resp. 54%, and for serum LDH 50%, 92% and 73%. The predictive value of PET was related to the prevalence of residual disease. PET predicted complete remission in more than 90% of patients with moderate risk (stage I-III, no relapse, no more than two different therapy regimens). In high risk patients, however, the negative predictive value of PET was 50-67%. CONCLUSION: FDG-PET is more accurate than CT imaging and LDH measurement for therapy monitoring of malignant lymphoma. Therapy success can be reliably predicted in patients with moderate risk.

Adolescent↗
PubMed1999

[Radioiodine therapy in veterinary medicine: treatment of hyperthyroidism in a cat].

A nine-year-old cat with symptoms of a distinct hyperthyroidism was presented at the University Hospital of the RWTH Aachen. The clinical symptoms as well as the diagnostic procedures performed at the hospital confirmed the diagnosis. After five weeks of thyreostatic medication a regular metabolism of the thyroid gland was established, followed by a radioiodine therapy with 70.3 MBq 131-iodine. Subsequently, the cat was hospitalized for two days before it could be released in good condition. Six weeks after treatment the former drastically reduced weight of the cat recovered to near normal. Even though the chemical analysis detected a discrete hyperthyroidism, clinical symptoms were no longer prominent. Three months after treatment, the final examination showed a regular metabolism of the thyroid gland without a specific thyroidal medication. The presented case illustrates that radioiodine therapy is a safe and efficient treatment of thyroidal dysfunctions in veterinary medicine.

Animals↗
PubMed1998

[Clinical value of positron emission tomography in neuromedicine. Position paper on results of an interdisciplinary consensus conference].

To date, positron emission tomography (PET) is the most powerful method for the in-vivo investigation of human brain metabolism. Besides extensive application of this technology in the neurosciences, PET is also being increasingly used as a clinical tool. However, despite its acceptance in clinical practice a major obstacle is its high costs. The present article reviews the literature on the clinical use of PET in neurology, neurosurgery, and psychiatry in order to substantiate the clinical indications for PET in these specialties as established by an interdisciplinary conference.

Brain Diseases↗
PubMed1998

[Determination of factors affecting the therapeutic outcome of radioiodine therapy in patients with Graves' disease].

AIM: Of this study was to determine whether success of radioiodine therapy (RIT) in Graves' disease depends on thyroid volume, function, thyroideal receptor antibodies (TRAK), thyreostasis, therapeutic dosage, 131I uptake, or effective half-life. METHOD: 78 patients received an average of 626 +/- 251 MBq of iodine-131 orally for thyroid ablation. 60 were assessed for successful therapy 3 months after RIT. RESULTS: In patients showing hyperthyreosis or a TRAK value > 11 U/l at the beginning of RIT, a significantly lower therapeutic dosage and effective iodine half-life were found than in non-hyperthyreotic patients or patients with TRAK < or = 11 U/l. Patients with a thyroid volume < or = 25 ml showed a significantly lower 131I uptake, but a significantly higher relative uptake (131I uptake/ volume) than patients with a thyroid volume > 25 ml. All failures were treated thyreostatically during RIT and showed a significantly lower therapeutic iodine dosage and relative uptake, as well as a significantly higher thyroid volume than patients with a successful therapy. RIT caused a thyroid volume reduction of 44%, with therapy failures showing a significantly lower volume reduction. Patients who received a therapeutic dosage of < or = 250 Gy showed significantly worse results than did those who had received > 250 Gy. Only one case of therapy failure received a dosage > 250 Gy, while 50% of failures received dosages > 200 Gy but < 250 Gy. Multivariate analyses (MANOVA, factor analyses) showed thyreostasis as the decisive negative factor for a successful course of therapy. CONCLUSIONS: Since most treatment failures occurred in patients under thyreostatic medication we recommend raising the target dosage to 250 Gy for these cases.

Administration, Oral↗
PubMed1998

[Attenuation corrected myocardial PET after application of 18FDG: effect on the determination of regional myocardial uptake values].

AIM: Post injection transmission measurement (PIT) can be performed using rotating 68Ge/68Ga linesources. This study estimates attenuation coefficients, count densities and relative regional uptake values of PIT corrected cardiac PET (E-PIT) compared to routinely pre-injection transmission measurement (RT). METHODS: A thorax-phantom with homogeneously filled myocardium or with simulated defects and six patients with advanced coronary artery disease were studied using ECAT Exact tomograph (Siemens CTI) equipped with three rotating linesources. Transmission was performed twice (PIT, RT), attenuation coefficients and emission data were analysed, the latter without attenuation correction (E-UK), corrected with PIT (E-PIT) and with RT (E-RT) (count density, standard and relative uptake values). RESULTS: Both in phantom and patient studies attenuation coefficients differed significantly between PIT and RT. Comparing E-PIT and E-RT, regional uptake values were different only in phantom simulation with myocardial radioactivity concentrations higher than 10 kBq x ml-1. The image contrast between defects and remaining myocardium in the phantom studies or the standard and relative uptake values in patient studies did not vary significantly. CONCLUSION: Under clinical conditions a post injection transmission measurement does not influence the accuracy of regional myocardial uptake values relevantly.

Biological Transport↗
PubMed1998

[Investigations on the effect of "ecstasy" on cerebral glucose metabolism: an 18-FDG PET study].

PURPOSE: The aim of the present study was to determine the acute effects of the "Ecstasy" analogue MDE (3, 4-methylendioxyethamphetamine) on the cerebral glucose metabolism (rMRGlu) of healthy volunteers. METHOD: In a randomised double-blind trial, 16 healthy volunteers without a history of drug abuse were examined with 18-FDG PET 110-120 minutes after oral administration of 2 mg/kg MDE (n = 8) or placebo (n = 8). Beginning two minutes prior to radiotracer injection, a constant cognitive stimulation was maintained for 32 minutes using a word repetition paradigm in order to ensure constant and comparable mental conditions during cerebral 18-FDG uptake. Individual brain anatomy was represented using T1-weighted 3D flash MRI, followed by manual regionalisation into 108 regions-of-interest and PFT/MRI overlay. Absolute quantification of rMRGlu and comparison of glucose metabolism under MDE versus placebo were performed using Mann-Whitney U-test. RESULTS: Absolute global MRGlu was not significantly changed under MDE versus placebo (MDE: 41.8 +/- 11.1 mumol/min/100 g, placebo: 50.1 +/- 18.1 mumol/min/100 g, p = 0.298). The normalised regional metabolic data showed a significantly decreased rMRGlu in the bilateral frontal cortex: left frontal posterior (-7.1%, p < 0.05) and right prefrontal superior (-4.6%, p < 0.05). On the other hand, rMRGlu was significantly increased in the bilateral cerebellum (right: +10.1%, p < 0.05; left +7.6%, p < 0.05) and in the right putamen (+6.2%, p < 0.05). CONCLUSIONS: The present study revealed acute neurometabolic changes under the "Ecstasy" analogon MDE indicating a fronto-striato-cerebellar dysbalance with parallels to other psychotropic substances and various endogenous psychoses respectively.

Administration, Oral↗
PubMed1997

[A method for combined scatter and attenuation correction without transmission measurement for myocardial SPECT with 99m-Tc binding].

AIM: A new strategy is introduced for a double-head gamma-camera to calculate and to correct for attenuation distribution from count rates of backscattered radiation of 99mTc in the human thorax/myocardium setting. The intention was to gain segmented and calibrated images of distribution employing the structures of lungs and other tissues, so that attenuation may be subsequently corrected by the method of Chang METHODS: Acquisition was done simultaneously in three energy window for 99mTc to receive both emitted and scattered radiation. The acquire projections were used to calculate the attenuation distribution and to execute a scatter correction by the method of Ogawa et. al. By measuring phantoms and evaluating a set of patient studies, quality for both of the approaches towards attenuated distribution and the quality of attenuation correction was tested and an optimal setting for parameters involved was selected. RESULTS: The procedure adequately approaches the correction for both emitted and scattered radiation in SPECT, as experienced in phantom and patient studies. Clinical usefulness was preliminary documented in selected cases. In normal perfusion, distribution was more homogeneous. Perfusion defects appeared more definitive. Problems occurred in high adjacent non-target activity (e.g., in the gallbladder) and with low count rate statistics. CONCLUSION: Myocardial 99mTc MIBI SPECT may be effectively corrected for both attenuation a scatter without an additional transmission device.

Heart↗
PubMed1997

[18F-fluorodeoxyglucose PET in ovarian carcinoma: methodology and preliminary results].

AIM: Of the present study was to evaluate 18FDG PET as a diagnostic tool in primary and recurrent ovarian cancer. METHODS: PET of the abdomen and the pelvis was performed in 26 patients suspected for primary (n = 17) or recurrent (n = 9) ovarian cancer with an ECAT 953/15 scanner 45 min after intravenous administration of 245 MBq 18F-FDG (mean). PET findings were validated by surgery, histology and/or cytology. RESULTS: Ovarian malignancies or recurrent ovarian cancer were demonstrated by PET in 16 out of 19 cases. Malignancy was excluded in six out of seven cases. False negative findings were obtained in two cases of low malignant potential tumors (LMP) and in one case of low grade serous/mucinous ovarian cystadenocarcinoma. PET yielded one false positive result in a case of salpingoophoritis. Quantitative analysis revealed a mean SUV of 6.8 +/- 2.3 in primary ovarian carcinoma vs. 2.6 +/- 1.2 in benign masses (p < 0.05). CONCLUSION: These preliminary data show 18FDG PET to be useful in diagnosis of recurrent ovarian cancer. PET is of limited use in differentiating LMP from benign tumors and ovarian cancer from inflammatory processes. Concerning this differentiation, quantitative analysis does not improve diagnostic accuracy.

Adult↗
PubMed1997

[Comparison of findings with 18-FDG PET and CT in pretherapeutic staging of malignant lymphoma].

AIM: Comparison of diagnostic efficiency of FDG-PET and CT regarding localisation, histology, size and FDG-uptake of a lesion. METHODS: CT- and FDG-PET studies of 27 patients with histologically confirmed malignant lymphoma as primary disease or relapse were evaluated retrospectively. In CT lesions with a diameter (DCT) > 15 mm were regarded as positive. Focal accumulations of FDG, not explained by physiological metabolism, found by visual interpretation in iterative reconstructed PET-scans, were quantified for diameter (DPET) and corrected standardized uptake value (SUV), corrected for partial-volume-effect. Lesions were classified depending on histology and lesion quality (lymph nodes, bulks, extranodal lesions). RESULTS: CT detected 78 lesions in 26 patients, all confirmed by FDG-PET. PET localized 18 additional lesions (+23%); in high grade NHL +25%. Both methods were equally efficient in cervical lymph nodes and lung lesions, in all other regions of lymphatic nodules and in case of liver and spleen lesions PET localized more lesions. SUV was significantly higher in high-grade NHL (19.0) than in low-grade NHL and Hodgkin's disease (10.6 resp. 11.1). DCT and DPET correlated significantly (r = 0.75). CONCLUSION: Diagnostic efficiency of FDG-PET is equivalent or superior to CT in staging of malignant lymphoma before therapy. Qualitative interpretation seems sufficient for staging, quantitative analysis may add information about malignancy grade in NHL.

Fluorodeoxyglucose F18↗