TY  - JOUR
A1  - Boecker, Henning
A1  - Kuwert, Torsten
A1  - Langen, Karl-J.
A1  - Lange, Herwig W.
A1  - Czech, Norbert
A1  - Ziemons, Karl
A1  - Herzog, Hans
A1  - Shikare, Shekar
A1  - Weindl, Anton
A1  - Feinendegen, Ludwig E.
T1  - SPECT with HMPAO compared to PET with FDG in Huntington disease
JF  - Journal of Computer Assisted Tomography
Y1  - 1994
SN  - 1532-3145
VL  - 18
IS  - 4
SP  - 542
EP  - 548
ER  - 
TY  - JOUR
A1  - Langen, Karl J.
A1  - Ziemons, Karl
A1  - Kiwit, Jürgen C. W.
A1  - Herzog, Hans
A1  - Kuwert, Torsten
A1  - Bock, Wolfgang
A1  - Stöcklin, Gerhard
A1  - Feinendegen, Ludwig E.
A1  - Müller-Gärtner, Hans-W.
T1  - 3-[123I]iodo-α-methyltyrosine and [methyl-11C]-L-methionine uptake in cerebral gliomas: a compara-tive study using SPECT and PET
JF  - Journal of Nuclear Medicine
Y1  - 1997
SN  - 0161-5505
VL  - 38
IS  - 4
SP  - 517
EP  - 522
ER  - 
TY  - JOUR
A1  - Weckesser, Matthias
A1  - Hufnagel, Andreas
A1  - Ziemons, Karl
A1  - Grießmeier, Martin
A1  - Sonnenberg, Frank
A1  - Hackländer, Thomas
A1  - Langen, Karl-J.
A1  - Holschbach, Markus
A1  - Elger, Christian E.
A1  - Müller-Gärtner, Hans-W.
T1  - Effect of partial volume correction on muscarinic cholinergic receptor imaging with single-photon emission tomography in patients with temporal lobe epilepsy
JF  - European Journal of Nuclear Medicine
N2  - Animal experiments and preliminary results in humans have indicated alterations of hippocampal muscarinic acetylcholine receptors (mAChR) in temporal lobe epilepsy. Patients with temporal lobe epilepsy often present with a reduction in hippocampal volume. The aim of this study was to investigate the influence of hippocampal atrophy on the quantification of mAChR with single photon emission tomography (SPET) in patients with temporal lobe epilepsy. Cerebral uptake of the muscarinic cholinergic antagonist [123I]4-iododexetimide (IDex) was investigated by SPET in patients suffering from temporal lobe epilepsy of unilateral (n=6) or predominantly unilateral (n=1) onset. Regions of interest were drawn on co-registered magnetic resonance images. Hippocampal volume was determined in these regions and was used to correct the SPET results for partial volume effects. A ratio of hippocampal IDex binding on the affected side to that on the unaffected side was used to detect changes in muscarinic cholinergic receptor density. Before partial volume correction a decrease in hippocampal IDex binding on the focus side was found in each patient. After partial volume no convincing differences remained. Our results indicate that the reduction in hippocampal IDex binding in patients with epilepsy is due to a decrease in hippocampal volume rather than to a decrease in receptor concentration.
Y1  - 1997
SN  - 1619-7089
VL  - 24
IS  - 9
SP  - 1156
EP  - 1161
ER  - 
TY  - JOUR
A1  - Schmidt, Daniela
A1  - Langen, Karl-J.
A1  - Herzog, Hans
A1  - Wirths, Jochen
A1  - Holschbach, Markus
A1  - Kiwit, Jürgen C. W.
A1  - Ziemons, Karl
A1  - Coenen, Heinz-H.
A1  - Müller-Gärtner, Hans-W.
T1  - Whole-body kinetics and dosimetry of L-3[123I]-iodo-α-methyltyrosine
JF  - European Journal of Nuclear Medicine
Y1  - 1997
SN  - 1619-7089
VL  - 24
IS  - 9
SP  - 1162
EP  - 1166
ER  - 
TY  - JOUR
A1  - Weckesser, Martin
A1  - Grießmeier, Martin
A1  - Schmidt, Daniela
A1  - Sonnenberg, Frank
A1  - Ziemons, Karl
A1  - Kemna, Lars
A1  - Holschbach, Marcus
A1  - Langen, Karl-J.
A1  - Müller-Gärtner, Hans-W.
T1  - Iodine-123 α-methyl tyrosine single-photon emission tomography of cerebral gliomas: standardised evaluation of tumour uptake and extent
JF  - European Journal of Nuclear Medicine
N2  - Single-photon emission tomography (SPET) with the amino acid analogue l-3-[123I]iodo-α-methyl tyrosine (IMT) is helpful in the diagnosis and monitoring of cerebral gliomas. Radiolabelled amino acids seem to reflect tumour infiltration more specifically than conventional methods like magnetic resonance imaging and computed tomography. Automatic tumour delineation based on maximal tumour uptake may cause an overestimation of mean tumour uptake and an underestimation of tumour extension in tumours with circumscribed peaks. The aim of this study was to develop a program for tumour delineation and calculation of mean tumour uptake which takes into account the mean background activity and is thus optimised to the problem of tumour definition in IMT SPET. Using the frequency distribution of pixel intensities of the tomograms a program was developed which automatically detects a reference brain region and draws an isocontour region around the tumour taking into account mean brain radioactivity. Tumour area and tumour/brain ratios were calculated. A three-compartment phantom was simulated to test the program. The program was applied to IMT SPET studies of 20 patients with cerebral gliomas and was compared to the results of manual analysis by three different investigators. Activity ratios and chamber extension of the phantom were correctly calculated by the automatic analysis. A method based on image maxima alone failed to determine chamber extension correctly. Manual region of interest analysis in patient studies resulted in a mean inter-observer standard deviation of 8.7%±6.1% (range 2.7%–25.0%). The mean value of the results of the manual analysis showed a significant correlation to the results of the automatic analysis (r = 0.91, P<0.0001 for the uptake ratio; r = 0.87, P<0.0001 for the tumour area). We conclude that the algorithm proposed simplifies the calculation of uptake ratios and may be used for observer-independent evaluation of IMT SPET studies. Three-dimensional tumour recognition and transfer to co-registered morphological images based on this program may be useful for the planning of surgical and radiation treatment.
Y1  - 1998
SN  - 1619-7089
VL  - 25
IS  - 2
SP  - 150
EP  - 156
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Chavan, U.
A1  - Lame, H.
A1  - Parl, C.
A1  - Müller-Veggian, Mattea
A1  - Ziemons, Karl
T1  - Treating the Gain Non-Uniformity of Multi Channel PMTs by Channel-Specific Trigger Levels
JF  - 2006 IEEE Nuclear Science Symposium Conference Record, Vol. 2.
Y1  - 2006
SN  - 1082-3654
SP  - 1301
EP  - 1304
CY  - San Diego, CA
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Beer, S.
A1  - Hombach, T.
A1  - Jahnke, S.
A1  - Khodaverdi, M.
A1  - Larue, H.
A1  - Minwuyelet, S.
A1  - Parl, C.
A1  - Roeb, G.
A1  - Schurr, U.
A1  - Ziemons, Karl
T1  - PlanTIS: A positron emission tomograph for imaging 11C transport in plants
JF  - 2007 IEEE Nuclear Science Symposium Conference Record, Vol. 6
N2  - Plant growth and transport processes are highly dynamic. They are characterized by plant-internal control processes and by strong interactions with the spatially and temporally varying environment. Analysis of structure- function relations of growth and transport in plants will strongly benefit from the development of non-invasive techniques. PlanTIS (Plant Tomographic Imaging System) is designed for non-destructive 3D-imaging of positron emitting radiotracers. It will permit functional analysis of the dynamics of carbon distribution in plants including bulky organs. It will be applicable for screening transport properties of plants to evaluate e.g. temperature adaptation of genetically modified plants. PlanTIS is a PET scanner dedicated to monitor the dynamics of the 11C distribution within a plant while or after assimilation of 11CO2. Front end electronics and data acquisition architecture of the scanner are based on the ClearPETTM system [1]. Four detector modules form one of two opposing detector blocks. Optionally, a hardware coincidence detection between the blocks can be applied. In general the scan duration is rather long (~ 1 hour) compared to the decay time of 11C (20 min). As a result the count rates can vary over a wide range and accurate dead time correction is necessary.
Y1  - 2008
SN  - 1082-3654
SP  - 4110
EP  - 4112
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Bruyndonckx, P.
A1  - Perez, J. M.
A1  - Pietrzyk, U.
A1  - Rato, P.
A1  - Tavernier, S.
T1  - Beyond ClearPET: Next Aims
JF  - 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro Symposium Proceedings ISBI 2008
N2  - The CRYSTAL CLEAR collaboration, in short CCC, is a consortium of 12 academic institutions, mainly from Europe, joining efforts in the area of developing instrumentation for nuclear medicine and medical imaging. In the framework of the CCC a high performance small animal PET system, called ClearPET, was developed by using new technologies in electronics and crystals in a phoswich arrangement combining two types of lutetium- based scintillator materials: LSO:Ce and LuYAP:Ce. Our next aim will be the development of hybrid image systems. Hybrid MR-PET imaging has many unique advantages for brain research. This has sparked a new research line within CCC for the development of novel MR-PET compatible technologies. MRI is not as sensitive as PET but PET has poorer spatial resolution than MRI. Two major advantages of PET are sensitivity and its ability to acquire metabolic information. To assess these innovations, the development of a 9.4T hybrid animal MR-PET scanner is proposed based on an existing 9.4T MR scanner that will be adapted to enable simultaneous acquisition of MR and PET data using cutting- edge technology for both MR and PET.
Y1  - 2008
SN  - 978-1-4244-2003-2
SP  - 1421
EP  - 1424
ER  - 
TY  - JOUR
A1  - Jahnke, Siegfried
A1  - Menzel, Marion I.
A1  - Dusschoten, Dagmar van
A1  - Roeb, Gerhard W.
A1  - Bühler, Jonas
A1  - Minwuyelet, Senay
A1  - Blümler, Peter
A1  - Temperton, Vicky M.
A1  - Hombach, Thomas
A1  - Streun, Matthias
A1  - Beer, Simone
A1  - Khodaverdi, Maryam
A1  - Ziemons, Karl
A1  - Coenen, Heinz H.
A1  - Schurr, Ulrich
T1  - Combined MRI–PET dissects dynamic changes in plant structures and functions
JF  - The Plant Journal
N2  - Unravelling the factors determining the allocation of carbon to various plant organs is one of the great challenges of modern plant biology. Studying allocation under close to natural conditions requires non-invasive methods, which are now becoming available for measuring plants on a par with those developed for humans. By combining magnetic resonance imaging (MRI) and positron emission tomography (PET), we investigated three contrasting root/shoot systems growing in sand or soil, with respect to their structures, transport routes and the translocation dynamics of recently fixed photoassimilates labelled with the short-lived radioactive carbon isotope 11C. Storage organs of sugar beet (Beta vulgaris) and radish plants (Raphanus sativus) were assessed using MRI, providing images of the internal structures of the organs with high spatial resolution, and while species-specific transport sectoralities, properties of assimilate allocation and unloading characteristics were measured using PET. Growth and carbon allocation within complex root systems were monitored in maize plants (Zea mays), and the results may be used to identify factors affecting root growth in natural substrates or in competition with roots of other plants. MRI–PET co-registration opens the door for non-invasive analysis of plant structures and transport processes that may change in response to genomic, developmental or environmental challenges. It is our aim to make the methods applicable for quantitative analyses of plant traits in phenotyping as well as in understanding the dynamics of key processes that are essential to plant performance.
Y1  - 2009
SN  - 1365-313X
VL  - 59
IS  - 4
SP  - 634
EP  - 644
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Wedrowski, M.
A1  - Bruyndonckx, P.
A1  - Tavernier, S.
A1  - Zhi, L.
A1  - Dang, J.
A1  - Mendes, P. R.
A1  - Perez, J. M.
A1  - Ziemons, Karl
T1  - Robustness of neural networks algorithm for gamma detection in monolithic block detector, positron emission tomography
JF  - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - The monolithic scintillator block approach for gamma detection in the Positron Emission Tomography (PET) avoids estimating Depth of Interaction (DOI), reduces dead zones in detector and diminishes costs of detector production. Neural Networks (NN) are very efficient to determine the entrance point of a gamma incident on a scintillator block. This paper presents results on the robustness of the spatial resolution as a function of the random fraction in the data, temperature and HV fluctuations. This is important when implementing the method in a real scanner. Measurements were done with two Hamamatsu S8550 APD arrays, glued on a 20 × 20 × 10 mm3 monolithic LSO crystal block.
Y1  - 2009
SN  - 1082-3654
SP  - 2625
EP  - 2628
ER  -