M Voth

Publications of M Voth

• Biological dosimetry after radiosynoviorthesis with rhenium-186 sulphide and erbium-169 citrate.

  Authors: R Klett, A Schnurbus-Duhs, G Mödder, E Schmid, M Voth

  Nuklearmedizin. Nuclear medicine. 09/2011; 50(1):17-25.

  Radiosynoviorthesis (RSO) with the nuclides rhenium-186 sulphide (186Re) and erbium-169 citrate (169Er) is an established concept for the treatment of persistent synovitis of medium and small sizedRadiosynoviorthesis (RSO) with the nuclides rhenium-186 sulphide (186Re) and erbium-169 citrate (169Er) is an established concept for the treatment of persistent synovitis of medium and small sized joints. The aim of the present studies was to investigate the biological radiation effect based on analysing chromosome aberrations. Patients, methods: Immediately before and 17 to 19 days (186Re) or 45 to 50 (169Er) days after RSO with 186Re or 169Er colloid and subsequent immobilisation of the treated joint, blood samples of a total of 23 patients were collected. The yield of dicentric chromosomes in lymphocytes was determined exclusively in metaphases of the first cell cycle in vitro. In addition, for 186Re the activity leakage was measured three days after RSO by whole-body scintigraphy. Results: No statistically significant increase in the number of dicentric chromosomes (40 and 88 before and 59 and 105 after treatment with 186Re and 169Er, respectively) in a total of 47017 cells analysed from 46 blood samples could be found as a result of RSO. For 186Re an activity leakage of 3.9%±7% with a maximum of 23.4% corresponding to an effective dose of 2.8±4.5 mSv , respectively 13.8 mSv, was determined. Also in the case of the maximum leakage no significant increase of dicentric chromosomes were detected. Conclusions: No significant biological radiation effect can be detected after RSO with 186Re and 169Er, also in cases of high leakage. Therefore, RSO can be classified as a save therapeutic procedure without a relevant radiation risk.

• Dependence of renal blood flow on renal artery stenosis measured using CT angiography.

  Authors: L Lüdemann, B Nafz, F Elsner, C Grosse-Siestrup, M Meissler, P Persson, M Gutberlet, P Lengsfeld, M Voth

  RöFo : Fortschritte auf dem Gebiete der Röntgenstrahlen und der Nuklearmedizin. 03/2011; 183(3):267-73.

  The present study investigates the suitability of computed tomography angiography (CTA) depicting the degree of renal artery stenosis for estimating renal blood flow (RBF) in a kidney. WeThe present study investigates the suitability of computed tomography angiography (CTA) depicting the degree of renal artery stenosis for estimating renal blood flow (RBF) in a kidney. We investigated renal artery stenosis assessment by CTA in eight adult female hybrid pigs with an ultrasound probe implanted at the renal vein for RBF measurement. An inflatable metal-free cuff was placed around the renal artery to control the RBF. The RBF was then reduced in four steps. For each reduced RBF value and baseline RBF, CTA with a reconstructed slice thickness of 0.625 mm was performed in the arterial phase following injection of 80 ml of nonionic intravenous contrast medium. The radius of the stenotic and non-stenotic renal artery segment was measured in the reconstructed images. A significant linear correlation (p < 0.0001) was found between the relative apparent stenosis (calculated as the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment) and RBF. The linear regression yielded a slope of 0.57 and a y-axis of 24.1 %. A significant linear correlation (p < 0.0001) was also found between the relative true stenosis (the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment at baseline) and the RBF. The linear regression yielded a slope of 0.67 and a y-axis of 13.8 %. The results show that the relative stenosis apparent on CTA differs from the true degree of renal artery stenosis. Nevertheless, the degree of renal artery stenosis determined by CTA provides a reliable estimate of the resulting RBF reduction.

• Contrast-enhanced magnetic resonance angiography (MRA): evaluation of three different contrast agents at two different doses (0.05 and 0.1 mmol/kg) in pigs at 1.5 Tesla.

  Authors: M Voth, Henrik J Michaely, C Schwenke, B Vos, H Pietsch

  European radiology. 02/2011; 21(2):337-44.

  To compare the image quality of contrast-enhanced magnetic resonance angiography (CE-MRA) of the supra-aortic vessels at 0.05 mmol/kg bw and 0.1 mmol/kg bw, between gadobutrol, Gd-DTPA and Gd-BOPTATo compare the image quality of contrast-enhanced magnetic resonance angiography (CE-MRA) of the supra-aortic vessels at 0.05 mmol/kg bw and 0.1 mmol/kg bw, between gadobutrol, Gd-DTPA and Gd-BOPTA quantitatively and qualitatively a total of eight pigs were evaluated intraindividually at 1.5 T. Each pig was examined using 0.1 mmol/kg gadobutrol, Gd-DTPA and Gd-BOPTA on day one and 0.05 mmol/kg on day two. MRA datasets for the carotid artery and the infraorbital artery were qualitatively assessed regarding overall image quality on an ordinal four-point scale (4-excellent, 1-non-diagnostic). The signal-to noise-ratio (SNR) was measured. The qualitative assessment of the carotid artery showed a higher median image quality for the 0.1 mmol dose than for the 0.05 mmol dose for all three compounds. No difference was found for the infraorbital artery. Mean SNR of Gd-BOPTA, Gd-DTPA, gadobutrol at 0.05 mmol/kg were 36.0 ± 13.4/37.9 ± 16.3/43.7 ± 0.4 and at 0.1 mmol/kg they were 50.1 ± 12.4/46.6 ± 6.5 / 54.6 ± 10.2. Gd-BOPTA 0.05 revealed a significantly lower SNR than all other agents at normal dose. Full-dose gadolinium MRA results in higher image quality and significantly higher SNR compared with the half dose. Gadobutrol and Gd-BOPTA have similar enhancement properties at full dose but at half dose, gadobutrol appears superior.

• "Number needed to read"--how to facilitate clinical trials in MR-angiography.

  Authors: M Voth, U I Attenberger, A Luckscheiter, S Haneder, T Henzler, S O Schoenberg, C Schwenke, H J Michaely

  European radiology. 10/2010; 21(5):1034-42.

  To evaluate the effect of the number of readers on the statistical results in peripheral MRA. 40 patients with peripheral arterial occlusive disease were included as a sample dataset in this study,To evaluate the effect of the number of readers on the statistical results in peripheral MRA. 40 patients with peripheral arterial occlusive disease were included as a sample dataset in this study, randomly separated into two matched groups with n = 20 patients (group 1--gadobutrol, group 2--gadoterate meglumine) who underwent a continuous table movement MRA of the peripheral vessels at 3 T. Image quality (IQ) of 17 vessel segments was evaluated by 5 independent readers. The effect of the number of readers on significance and statistical power was statistically analyzed. Image quality in group 1 (gadobutrol) ranks significantly higher compared to group 2 (gadoterade meglumine) with a diagnostic IQ in 97% vs. 78% (p < 0.0001). For the diagnostic/non-diagnostic IQ assessment significance was reached with one reader 1/5 times (20%), with two readers in 4/10 (40%), with three readers in 6/10 (60%), with four readers in 4/5 (80%), with five readers in 1/1 (100%). Power considerations showed considerable gain when increasing the number of readers. Increasing the number of readers in a diagnostic MRA-study can be used to achieve a higher power or to decrease the number of subjects included with maintained statistical validity.

• The influence of tube voltage and phantom size in computed tomography on the dose-response relationship of dicentrics in human blood samples.

  Authors: G Jost, P Lengsfeld, M Voth, E Schmid, H Pietsch

  Physics in medicine and biology. 06/2010; 55(11):3237-48.

  The aim of this study was to investigate the dose response relationship of dicentrics in human lymphocytes after CT scans at tube voltages of 80 and 140 kV. Blood samples from a healthy donor placedThe aim of this study was to investigate the dose response relationship of dicentrics in human lymphocytes after CT scans at tube voltages of 80 and 140 kV. Blood samples from a healthy donor placed in tissue equivalent abdomen phantoms of standard, pediatric and adipose sizes were exposed at dose levels up to 0.1 Gy using a 64-slice CT scanner. It was found that both the tube voltage and the phantom size significantly influenced the CT scan-induced linear dose-response relationship of dicentrics in human lymphocytes. Using the same phantom (standard abdomen), 80 kV CT x-rays were biologically more effective than 140 kV CT x-rays. However, it could also be determined that the applied phantom size had much more influence on the biological effectiveness. Obviously, the increasing slopes of the CT scan-induced dose response relationships of dicentrics in human lymphocytes obtained in a pediatric, a standard and an adipose abdomen have been induced by scattering effects of photons, which strongly increase with increasing phantom size.

• The influence of x-ray contrast agents in computed tomography on the induction of dicentrics and gamma-H2AX foci in lymphocytes of human blood samples.

  Authors: G Jost, S Golfier, H Pietsch, P Lengsfeld, M Voth, T Schmid, F Eckardt-Schupp, E Schmid

  Physics in medicine and biology. 09/2009; 54(20):6029-6039.

  The aim of this study was to investigate and quantify two biomarkers for radiation exposure (dicentrics and gamma-H2AX foci) in human lymphocytes after CT scans in the presence of an iodinatedThe aim of this study was to investigate and quantify two biomarkers for radiation exposure (dicentrics and gamma-H2AX foci) in human lymphocytes after CT scans in the presence of an iodinated contrast agent. Blood samples from a healthy donor were exposed to CT scans in the absence or presence of iotrolan 300 at iodine concentrations of 5 or 50 mg ml(-1) blood. The samples were exposed to 0.025, 0.05, 0.1 and 1 Gy in a tissue equivalent body phantom. Chromosome aberration scoring and automated microscopic analysis of gamma-H2AX foci were performed in parts of the same samples. The theoretical physical dose enhancement factor (DEF) was calculated on the basis of the mass energy-absorption coefficients of iodine and blood and the photon energy spectrum of the CT tube. No significant differences in the yields of dicentrics and gamma-H2AX foci were observed in the absence or presence of 5 mg iodine ml(-1) blood up to 0.1 Gy, whereas at 1 Gy the yields were elevated for both biomarkers. At an iodine concentration of 50 mg ml(-1) serving as a positive control, a biological DEF of 9.5 +/- 1.4 and 2.3 +/- 0.5 was determined for dicentrics and gamma-H2AX foci, respectively. A physical DEF of 1.56 and 6.30 was calculated for 5 and 50 mg iodine ml(-1), respectively. Thus, it can be concluded that in the diagnostic dose range (radiation and contrast dose), no relevant biological dose-enhancing effect could be detected, whereas a clear biological dose-enhancing effect could be found for a contrast dose well outside the diagnostic CT range for the complete radiation dose range with both methods.

• Radiosynoviorthesis of medium-sized joints with rhenium-186-sulphide colloid: a review of the literature.

  Authors: R Klett, U Lange, H Haas, M Voth, J Pinkert

  Rheumatology (Oxford, England). 11/2007; 46(10):1531-7.

  Hypertrophy and inflammation of the synovium with various underlying pathologies - such as rheumatoid arthritis, osteoarthritis, haemophilia and spondyloarthropathy - can be treated successfully byHypertrophy and inflammation of the synovium with various underlying pathologies - such as rheumatoid arthritis, osteoarthritis, haemophilia and spondyloarthropathy - can be treated successfully by radiosynoviorthesis (RSO). For medium-sized joints (shoulder, elbow, wrist, hip and ankle), the radionuclide of choice is rhenium-186. We review the evidence for the efficacy of this local, relatively non-invasive therapy and evaluate its benefits and risks. We conclude good evidence of rhenium-186 RSO in rheumatoid arthritis and haemophilic arthropathy. In the remaining pathologies, up to now, the therapeutic efficacy has not been confirmed by today's most stringent criteria for clinical studies. The available data support rhenium-186 RSO as a suitable second-line treatment for patients in whom other therapies (including locally injected corticoids) have failed, as long as proper attention is paid to correct administration - including post-treatment immobilization and the co-administration of corticoids.

• Therapeutic status of radiosynoviorthesis of the knee with yttrium [90Y] colloid in rheumatoid arthritis and related indications.

  Authors: W U Kampen, M Voth, J Pinkert, A Krause

  Rheumatology (Oxford, England). 02/2007; 46(1):16-24.

  Radiosynoviorthesis (RSO) with an yttrium-90 colloid offers a local and minimally invasive therapy for treating inflammatory hypertrophy of the synovial membrane of the knee that has arisen fromRadiosynoviorthesis (RSO) with an yttrium-90 colloid offers a local and minimally invasive therapy for treating inflammatory hypertrophy of the synovial membrane of the knee that has arisen from numerous kinds of disorder: these include rheumatoid arthritis (RA), osteoarthritis (OA), spondyloarthropathy, villonodular synovitis and others. There is substantial evidence that this treatment is efficacious and that, in view of the benefits that it offers, its tolerability and safety are very good. Administration should be restricted to patients in whom other therapies (including locally injected corticoids) have failed, and proper attention must be paid to correct administration, including post-treatment immobilization and the co-administration of corticoids, to minimize the risk of leakage and of efflux through the puncture channel.

• The effect of the beta-emitting yttrium-90 citrate on the dose-response of dicentric chromosomes in human lymphocytes: a basis for biological dosimetry after radiosynoviorthesis.

  Authors: E Schmid, H-J Selbach, M Voth, J Pinkert, F J Gildehaus, R Klett, M Haney

  Radiation and environmental biophysics. 08/2006; 45(2):93-8.

  The production of dicentric chromosomes in human lymphocytes by beta-particles of yttrium-90 (Y-90) was studied in vitro to provide a basis of biological dosimetry after radiosynoviorthesis (RSO) ofThe production of dicentric chromosomes in human lymphocytes by beta-particles of yttrium-90 (Y-90) was studied in vitro to provide a basis of biological dosimetry after radiosynoviorthesis (RSO) of persistent synovitis by intra-articular administration of yttrium-90 citrate colloid. Since the injected colloid may leak into the lymphatic drainage exposing other parts of the body to radiation, the measurement of biological damage induced by beta-particles of Y-90 is important for the assessment of radiation risk to the patients. A linear dose-response relationship (alpha = 0.0229 +/- 0.0028 dicentric chromosomes per cell per gray) was found over the dose range of 0.2176-2.176 Gy. The absorbed doses were calculated for exposure of blood samples to Y-90 activities from 40 to 400 kBq using both Monte Carlo simulation and an analytical model. The maximum low-dose RBE, the RBE(M) which is equivalent to the ratio of the alpha coefficients of the dose-response curves, is well in line with published results obtained earlier for irradiation of blood of the same donor with heavily filtered 220 kV X-rays (3.35 mm copper), but half of the RBE(M) relative to weakly filtered 220 kV X-rays. Therefore, it can be concluded that for estimating an absorbed dose during RSO by the technique of biological dosimetry, in vitro and in vivo data for the same radiation quality are necessary.

• Biological dosimetry after yttrium-90 citrate colloid radiosynoviorthesis.

  Authors: M Voth, R Klett, P Lengsfeld, G Stephan, E Schmid

  Nuklearmedizin. Nuclear medicine. 02/2006; 45(5):223-8.

  Radiosynoviorthesis (RSO) with the ss-particle-emitting nuclide yttrium-90 is an established concept for the treatment of persistent synovitis of the knee joint. The AIM of this study was toRadiosynoviorthesis (RSO) with the ss-particle-emitting nuclide yttrium-90 is an established concept for the treatment of persistent synovitis of the knee joint. The AIM of this study was to investigate the biological radiation effect on the basis of a characteristic radiation parameter. PATIENTS, METHODS: After RSO procedures with yttrium-90 citrate colloid and subsequent immobilisation of the knee, blood specimens of 10 patients were collected immediately before RSO and 11 to 13 days after the intervention. The yield of dicentric chromosomes in the lymphocytes was determined exclusively in metaphases of the first cell cycle in vitro. In addition, activity leakage was measured by wholebody bremsstrahlung-scintigraphy. RESULTS: No statistically significant increase in the number of dicentric chromosomes (26 before treatment and 34 after treatment) in 20 192 cells analyzed from the 20 blood samples could be found as a result of RSO. However, the analysis of at least 1000 cells per blood sample demonstrates a tendency for a biological radiation effect in the blood of patients on the basis of this characteristic radiation parameter. Two of the 10 RSO patients had undergone a second RSO using yttrium-90 citrate, whereby one patient displayed activity transport out of the knee joint, amounting to 6 MBq. Only for him a radiation effect (about 130 mGy per single RSO) could be calculated by biological dosimetry. CONCLUSION: Since in general, based on the analysis of dicentric chromosomes in at least 1000 lymphocytes per individual, detection limits for groups of persons after long-term exposures to low-LET radiation of 50-100 mGy are possible, we assume that RSO with yttrium-90 should be associated with a low whole-body radiation exposure.