@article{BreunMonoranuKessleretal.2019,
  author    = {Breun, Maria and Monoranu, Camelia M. and Kessler, Almuth F. and Matthies, Cordula and L{\"o}hr, Mario and Hagemann, Carsten and Schirbel, Andreas and Rowe, Steven P. and Pomper, Martin G. and Buck, Andreas K. and Wester, Hans-J{\"u}rgen and Ernestus, Ralf-Ingo and Lapa, Constantin},
  title     = {[\(^{68}\)Ga]-Pentixafor PET/CT for CXCR4-mediated imaging of vestibular schwannomas},
  series = {Frontiers in Oncology},
  volume    = {9},
  journal   = {Frontiers in Oncology},
  number    = {503},
  doi       = {10.3389/fonc.2019.00503},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201863},
  year      = {2019},
  abstract  = {We have recently demonstrated CXCR4 overexpression in vestibular schwannomas (VS). This study investigated the feasibility of CXCR4-directed positron emission tomography/computed tomography (PET/CT) imaging of VS using the radiolabeled chemokine ligand [\(^{68}\)Ga]Pentixafor. Methods: 4 patients with 6 primarily diagnosed or pre-treated/observed VS were enrolled. All subjects underwent [\(^{68}\)Ga]Pentixafor PET/CT prior to surgical resection. Images were analyzed visually and semi-quantitatively for CXCR4 expression including calculation of tumor-to-background ratios (TBR). Immunohistochemistry served as standard of reference in three patients. Results: [\(^{68}\)Ga]Pentixafor PET/CT was visually positive in all cases. SUV\(_{mean}\) and SUV\(_{max}\) were 3.0 ± 0.3 and 3.8 ± 0.4 and TBR\(_{mean}\) and TBR\(_{max}\) were 4.0 ± 1.4 and 5.0 ± 1.7, respectively. Histological analysis confirmed CXCR4 expression in tumors. Conclusion: Non-invasive imaging of CXCR4 expression using [\(^{68}\)Ga]Pentixafor PET/CT of VS is feasible and could prove useful for in vivo assessment of CXCR4 expression.},
  language  = {en}
}
@article{WernerDerlinLapaetal.2020,
  author    = {Werner, Rudolf A. and Derlin, Thorsten and Lapa, Constantin and Sheikbahaei, Sara and Higuchi, Takahiro and Giesel, Frederik L. and Behr, Spencer and Drzezga, Alexander and Kimura, Hiroyuki and Buck, Andreas K. and Bengel, Frank M. and Pomper, Martin G. and Gorin, Michael A. and Rowe, Steven P.},
  title     = {\(^{18}\)F-labeled, PSMA-targeted radiotracers: leveraging the advantages of radiofluorination for prostate cancer molecular imaging},
  series = {Theranostics},
  volume    = {10},
  journal   = {Theranostics},
  number    = {1},
  issn      = {1838-7640},
  doi       = {10.7150/thno.37894},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202559},
  pages     = {1-16},
  year      = {2020},
  abstract  = {Prostate-specific membrane antigen (PSMA)-targeted PET imaging for prostate cancer with \(^{68}\)Ga-labeled compounds has rapidly become adopted as part of routine clinical care in many parts of the world. However, recent years have witnessed the start of a shift from \(^{68}\)Ga- to \(^{18}\)F-labeled PSMA-targeted compounds. The latter imaging agents have several key advantages, which may lay the groundwork for an even more widespread adoption into the clinic. First, facilitated delivery from distant suppliers expands the availability of PET radiopharmaceuticals in smaller hospitals operating a PET center but lacking the patient volume to justify an onsite \(^{68}\)Ge/\(^{68}\)Ga generator. Thus, such an approach meets the increasing demand for PSMA-targeted PET imaging in areas with lower population density and may even lead to cost-savings compared to in-house production. Moreover, \(^{18}\)F-labeled radiotracers have a higher positron yield and lower positron energy, which in turn decreases image noise, improves contrast resolution, and maximizes the likelihood of detecting subtle lesions. In addition, the longer half-life of 110 min allows for improved delayed imaging protocols and flexibility in study design, which may further increase diagnostic accuracy. Moreover, such compounds can be distributed to sites which are not allowed to produce radiotracers on-site due to regulatory issues or to centers without access to a cyclotron. In light of these advantageous characteristics, \(^{18}\)F-labeled PSMA-targeted PET radiotracers may play an important role in both optimizing this transformative imaging modality and making it widely available. We have aimed to provide a concise overview of emerging \(^{18}\)F-labeled PSMA-targeted radiotracers undergoing active clinical development. Given the wide array of available radiotracers, comparative studies are needed to firmly establish the role of the available \(^{18}\)F-labeled compounds in the field of molecular PCa imaging, preferably in different clinical scenarios.},
  language  = {en}
}
@article{NoseNogamiKoshinoetal.2021,
  author    = {Nose, Naoko and Nogami, Suguru and Koshino, Kazuhiro and Chen, Xinyu and Werner, Rudolf A. and Kashima, Soki and Rowe, Steven P. and Lapa, Constantin and Fukuchi, Kazuki and Higuchi, Takahiro},
  title     = {[18F]FDG-labelled stem cell PET imaging in different route of administrations and multiple animal species},
  series = {Scientific Reports},
  volume    = {11},
  journal   = {Scientific Reports},
  number    = {1},
  doi       = {10.1038/s41598-021-90383-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260590},
  year      = {2021},
  abstract  = {Stem cell therapy holds great promise for tissue regeneration and cancer treatment, although its efficacy is still inconclusive and requires further understanding and optimization of the procedures. Non-invasive cell tracking can provide an important opportunity to monitor in vivo cell distribution in living subjects. Here, using a combination of positron emission tomography (PET) and in vitro 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) direct cell labelling, the feasibility of engrafted stem cell monitoring was tested in multiple animal species. Human mesenchymal stem cells (MSCs) were incubated with phosphate-buffered saline containing [18F]FDG for in vitro cell radiolabelling. The pre-labelled MSCs were administrated via peripheral vein in a mouse (n=1), rats (n=4), rabbits (n=4) and non-human primates (n=3), via carotid artery in rats (n=4) and non-human primates (n=3), and via intra-myocardial injection in rats (n=5). PET imaging was started 10 min after cell administration using a dedicated small animal PET system for a mouse and rats. A clinical PET system was used for the imaging of rabbits and non-human primates. After MSC administration via peripheral vein, PET imaging revealed intense radiotracer signal from the lung in all tested animal species including mouse, rat, rabbit, and non-human primate, suggesting administrated MSCs were trapped in the lung tissue. Furthermore, the distribution of the PET signal significantly differed based on the route of cell administration. Administration via carotid artery showed the highest activity in the head, and intra-myocardial injection increased signal from the heart. In vitro [18F]FDG MSC pre-labelling for PET imaging is feasible and allows non-invasive visualization of initial cell distribution after different routes of cell administration in multiple animal models. Those results highlight the potential use of that imaging approach for the understanding and optimization of stem cell therapy in translational research.},
  language  = {en}
}
@article{LapaGarciaVellosoLueckerathetal.2017,
  author    = {Lapa, Constantin and Garcia-Velloso, Maria J. and L{\"u}ckerath, Katharina and Samnick, Samuel and Schreder, Martin and Otero, Paula Rodriguez and Schmid, Jan-Stefan and Herrmann, Ken and Knop, Stefan and Buck, Andreas K. and Einsele, Hermann and San-Miguel, Jesus and Kort{\"u}m, Klaus Martin},
  title     = {\(^{11}\)C-methionine-PET in multiple myeloma: a combined study from two different institutions},
  series = {Theranostics},
  volume    = {7},
  journal   = {Theranostics},
  number    = {11},
  doi       = {10.7150/thno.20491},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172038},
  pages     = {2956-2964},
  year      = {2017},
  abstract  = {\(^{11}\)C-methionine (MET) has recently emerged as an accurate marker of tumor burden and disease activity in patients with multiple myeloma (MM). This dual-center study aimed at further corroboration of the superiority of MET as positron emission tomography (PET) tracer for staging and re-staging MM, as compared to \(^{18}\)F-2`-deoxy-2`-fluoro-D-glucose (FDG). 78 patients with a history of solitary plasmacytoma (n=4), smoldering MM (SMM, n=5), and symptomatic MM (n=69) underwent both MET- and FDG-PET/computed tomography (CT) at the University Centers of W{\"u}rzburg, Germany and Navarra, Spain. Scans were compared on a patient and on a lesion basis. Inter-reader agreement was also evaluated. In 2 patients, tumor biopsies for verification of discordant imaging results were available. MET-PET detected focal lesions (FL) in 59/78 subjects (75.6\%), whereas FDG-PET/CT showed lesions in only 47 patients (60.3\%; p<0.01), accordingly disease activity would have been missed in 12 patients. Directed biopsies of discordant results confirmed MET-PET/CT results in both cases. MET depicted more FL in 44 patients (56.4\%; p<0.01), whereas in two patients (2/78), FDG proved superior. In the remainder (41.0\%, 32/78), both tracers yielded comparable results. Inter-reader agreement for MET was higher than for FDG (κ = 0.82 vs κ = 0.72). This study demonstrates higher sensitivity of MET in comparison to standard FDG to detect intra- and extramedullary MM including histologic evidence of FDG-negative, viable disease exclusively detectable by MET-PET/CT. MET holds the potential to replace FDG as functional imaging standard for staging and re-staging of MM.},
  language  = {en}
}
@article{WernerMarcusSheikhbahaeietal.2018,
  author    = {Werner, Rudolf A. and Marcus, Charles and Sheikhbahaei, Sara and Solnes, Lilja B. and Leal, Jeffrey P. and Du, Yong and Rowe, Steven P. and Higuchi, Takahiro and Buck, Andreas K. and Lapa, Constantin and Javadi, Mehrbod S.},
  title     = {Visual and Semiquantitative Accuracy in Clinical Baseline 123I-Ioflupane SPECT/CT Imaging},
  series = {Clinical Nuclear Medicine},
  volume    = {44},
  journal   = {Clinical Nuclear Medicine},
  number    = {1},
  issn      = {1536-0229},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-168181},
  year      = {2018},
  abstract  = {PURPOSE: We aimed to (a) elucidate the concordance of visual assessment of an initial I-ioflupane scan by a human interpreter with comparison to results using a fully automatic semiquantitative method and (b) to assess the accuracy compared to follow-up (f/u) diagnosis established by movement disorder specialists. METHODS: An initial I-ioflupane scan was performed in 382 patients with clinically uncertain Parkinsonian syndrome. An experienced reader performed a visual evaluation of all scans independently. The findings of the visual read were compared with semiquantitative evaluation. In addition, available f/u clinical diagnosis (serving as a reference standard) was compared with results of the human read and the software. RESULTS: When comparing the semiquantitative method with the visual assessment, discordance could be found in 25 (6.5\%) of 382 of the cases for the experienced reader (ĸ = 0.868). The human observer indicated region of interest misalignment as the main reason for discordance. With neurology f/u serving as reference, the results of the reader revealed a slightly higher accuracy rate (87.7\%, ĸ = 0.75) compared to semiquantification (86.2\%, ĸ = 0.719, P < 0.001, respectively). No significant difference in the diagnostic performance of the visual read versus software-based assessment was found. CONCLUSIONS: In comparison with a fully automatic semiquantitative method in I-ioflupane interpretation, human assessment obtained an almost perfect agreement rate. However, compared to clinical established diagnosis serving as a reference, visual read seemed to be slightly more accurate as a solely software-based quantitative assessment.},
  subject      = {SPECT},
  language  = {en}
}
@article{ZhouDierksKertelsetal.2020,
  author    = {Zhou, Xiang and Dierks, Alexander and Kertels, Olivia and Samnick, Samuel and Kircher, Malte and Buck, Andreas K. and Haertle, Larissa and Knorz, Sebastian and B{\"o}ckle, David and Scheller, Lukas and Messerschmidt, Janin and Barakat, Mohammad and Truger, Marietta and Haferlach, Claudia and Einsele, Hermann and Rasche, Leo and Kort{\"u}m, K. Martin and Lapa, Constantin},
  title     = {The link between cytogenetics/genomics and imaging patterns of relapse and progression in patients with relapsed/refractory multiple myeloma: a pilot study utilizing 18F-FDG PET/CT},
  series = {Cancers},
  volume    = {12},
  journal   = {Cancers},
  number    = {9},
  issn      = {2072-6694},
  doi       = {10.3390/cancers12092399},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-211157},
  year      = {2020},
  abstract  = {Utilizing 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT), we performed this pilot study to evaluate the link between cytogenetic/genomic markers and imaging patterns in relapsed/refractory (RR) multiple myeloma (MM). We retrospectively analyzed data of 24 patients with RRMM who were treated at our institution between November 2018 and February 2020. At the last relapse/progression, patients had been treated with a median of three (range 1-10) lines of therapy. Six (25\%) patients showed FDG avid extramedullary disease without adjacency to bone. We observed significantly higher maximum standardized uptake values (SUV\(_{max}\)) in patients harboring del(17p) compared with those without del(17p) (p = 0.025). Moreover, a high SUV\(_{max}\) of >15 indicated significantly shortened progression-free survival (PFS) (p = 0.01) and overall survival (OS) (p = 0.0002). One female patient exhibited biallelic TP53 alteration, i.e., deletion and mutation, in whom an extremely high SUV\(_{max}\) of 37.88 was observed. In summary, this pilot study suggested a link between del(17p)/TP53 alteration and high SUV\(_{max}\) on 18F-FDG PET/CT in RRMM patients. Further investigations are highly warranted at this point.},
  language  = {en}
}
@article{LapaKircherHaenscheidetal.2018,
  author    = {Lapa, Constantin and Kircher, Malte and H{\"a}nscheid, Heribert and Schirbel, Andreas and Grigoleit, G{\"o}tz Ulrich and Klinker, Erdwine and B{\"o}ck, Markus and Samnick, Samuel and Pelzer, Theo and Buck, Andreas K},
  title     = {Peptide receptor radionuclide therapy as a new tool in treatment-refractory sarcoidosis - initial experience in two patients},
  series = {Theranostics},
  volume    = {8},
  journal   = {Theranostics},
  number    = {3},
  doi       = {10.7150/thno.22161},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158983},
  pages     = {644-649},
  year      = {2018},
  abstract  = {Sarcoidosis is a multisystem granulomatous disorder of unknown etiology that can involve virtually all organ systems. Whereas most patients present without symptoms, progressive and disabling organ failure can occur in up to 10\% of subjects. Somatostatin receptor (SSTR)-directed peptide receptor radionuclide therapy (PRRT) has recently received market authorization for treatment of SSTR-positive neuroendocrine tumors. Methods: We describe the first case series comprising two patients with refractory multi-organ involvement of sarcoidosis who received 4 cycles of PRRT. Results: PRRT was well-tolerated without any acute adverse effects. No relevant toxicities could be recorded during follow-up. Therapy resulted in partial response accompanied by a pronounced reduction in pain (patient \#1) and stable disease regarding morphology as well as disease activity (patient \#2), respectively. Conclusion: Peptide receptor radionuclide therapy in sarcoidosis is feasible and might be a new valuable tool in patients with otherwise treatment-refractory disease. Given the long experience with and good tolerability of PRRT, further evaluation of this new treatment option for otherwise treatment-refractory sarcoidosis in larger patient cohorts is warranted.},
  language  = {en}
}
@unpublished{NoseWernerUedaetal.2018,
  author    = {Nose, Naoko and Werner, Rudolf A. and Ueda, Yuichiro and G{\"u}nther, Katharina and Lapa, Constantin and Javadi, Mehrbod S. and Fukushima, Kazuhito and Edenhofer, Frank and Higuchi, Takahiro},
  title     = {Metabolic substrate shift in human induced pluripotent stem cells during cardiac differentiation: Functional assessment using in vitro radionuclide uptake assay},
  series = {International Journal of Cardiology},
  journal   = {International Journal of Cardiology},
  issn      = {0167-5273},
  doi       = {10.1016/j.ijcard.2018.06.089},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-163320},
  year      = {2018},
  abstract  = {Background: Recent developments in cellular reprogramming technology enable the production of virtually unlimited numbers of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). Although hiPSC-CM share various characteristic hallmarks with endogenous cardiomyocytes, it remains a question as to what extent metabolic characteristics are equivalent to mature mammalian cardiomyocytes. Here we set out to functionally characterize the metabolic status of hiPSC-CM in vitro by employing a radionuclide tracer uptake assay. Material and Methods: Cardiac differentiation of hiPSC was induced using a combination of well-orchestrated extrinsic stimuli such as WNT activation (by CHIR99021) and BMP signalling followed by WNT inhibition and lactate based cardiomyocyte enrichment. For characterization of metabolic substrates, dual tracer uptake studies were performed with \(^{18}\)F-2-fluoro-2-deoxy-D-glucose (\(^{18}\)F-FDG) and \(^{125}\)I-β-methyl-iodophenyl-pentadecanoic acid (\(^{125}\)I-BMIPP) as transport markers of glucose and fatty acids, respectively. Results: After cardiac differentiation of hiPSC, in vitro tracer uptake assays confirmed metabolic substrate shift from glucose to fatty acids that was comparable to those observed in native isolated human cardiomyocytes. Immunostaining further confirmed expression of fatty acid transport and binding proteins on hiPSC-CM. Conclusions: During in vitro cardiac maturation, we observed a metabolic shift to fatty acids, which are known as a main energy source of mammalian hearts, suggesting hi-PSC-CM as a potential functional phenotype to investigate alteration of cardiac metabolism in cardiac diseases. Results also highlight the use of available clinical nuclear medicine tracers as functional assays in stem cell research for improved generation of autologous differentiated cells for numerous biomedical applications.},
  subject      = {Stammzelle},
  language  = {en}
}
@article{HoffmannJanssenKannoetal.2020,
  author    = {Hoffmann, Jan V. and Janssen, Jan P. and Kanno, Takayuki and Shibutani, Takayuki and Onoguchi, Masahisa and Lapa, Constantin and Grunz, Jan-Peter and Buck, Andreas K. and Higuchi, Takahiro},
  title     = {Performance evaluation of fifth-generation ultra-high-resolution SPECT system with two stationary detectors and multi-pinhole imaging},
  series = {EJNMMI Physics},
  volume    = {7},
  journal   = {EJNMMI Physics},
  doi       = {10.1186/s40658-020-00335-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230361},
  year      = {2020},
  abstract  = {Background Small-animal single-photon emission computed tomography (SPECT) systems with multi-pinhole collimation and large stationary detectors have advantages compared to systems with moving small detectors. These systems benefit from less labour-intensive maintenance and quality control as fewer prone parts are moving, higher accuracy for focused scans and maintaining high resolution with increased sensitivity due to focused pinholes on the field of view. This study aims to investigate the performance of a novel ultra-high-resolution scanner with two-detector configuration (U-SPECT5-E) and to compare its image quality to a conventional micro-SPECT system with three stationary detectors (U-SPECT\(^+\)). Methods The new U-SPECT5-E with two stationary detectors was used for acquiring data with \(^{99m}\)Tc-filled point source, hot-rod and uniformity phantoms to analyse sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR). Three dedicated multi-pinhole mouse collimators with 75 pinholes each and 0.25-, 0.60- and 1.00-mm pinholes for extra ultra-high resolution (XUHR-M), general-purpose (GP-M) and ultra-high sensitivity (UHS-M) imaging were examined. For CNR analysis, four different activity ranges representing low- and high-count settings were investigated for all three collimators. The experiments for the performance assessment were repeated with the same GP-M collimator in the three-detector U-SPECT\(^+\) for comparison. Results Peak sensitivity was 237 cps/MBq (XUHR-M), 847 cps/MBq (GP-M), 2054 cps/MBq (UHS-M) for U-SPECT5-E and 1710 cps/MBq (GP-M) for U-SPECT\(^+\). In the visually analysed sections of the reconstructed mini Derenzo phantoms, rods as small as 0.35 mm (XUHR-M), 0.50 mm (GP-M) for the two-detector as well as the three-detector SPECT and 0.75 mm (UHS-M) were resolved. Uniformity for maximum resolution recorded 40.7\% (XUHR-M), 29.1\% (GP-M, U-SPECT5-E), 16.3\% (GP-M, U-SPECT\(^+\)) and 23.0\% (UHS-M), respectively. UHS-M reached highest CNR values for low-count images; for rods smaller than 0.45 mm, acceptable CNR was only achieved by XUHR-M. GP-M was superior for imaging rods sized from 0.60 to 1.50 mm for intermediate activity concentrations. U-SPECT5-E and U-SPECT+ both provided comparable CNR. Conclusions While uniformity and sensitivity are negatively affected by the absence of a third detector, the investigated U-SPECT5-E system with two stationary detectors delivers excellent spatial resolution and CNR comparable to the performance of an established three-detector-setup.},
  language  = {en}
}
@article{JanssenHoffmannKannoetal.2020,
  author    = {Janssen, Jan P. and Hoffmann, Jan V. and Kanno, Takayuki and Nose, Naoko and Grunz, Jan-Peter and Onoguchi, Masahisa and Chen, Xinyu and Lapa, Constantin and Buck, Andreas K. and Higuchi, Takahiro},
  title     = {Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging},
  series = {Scientific Reports},
  volume    = {10},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-020-75696-0},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230616},
  year      = {2020},
  abstract  = {We aimed to investigate the image quality of the U-SPECT5/CT E-Class a micro single-photon emission computed tomography (SPECT) system with two large stationary detectors for visualization of rat hearts and bones using clinically available \(^{99m}\)Tc-labelled tracers. Sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR) of the small-animal SPECT scanner were investigated in phantom studies using an ultra-high-resolution rat and mouse multi-pinhole collimator (UHR-RM). Point source, hot-rod, and uniform phantoms with \(^{99m}\)Tc-solution were scanned for high-count performance assessment and count levels equal to animal scans, respectively. Reconstruction was performed using the similarity-regulated ordered-subsets expectation maximization (SROSEM) algorithm with Gaussian smoothing. Rats were injected with similar to 100 MBq [\(^{99m}\)TcTc-MIBI or similar to 150 MBq [\(^{99m}\)Tc]Tc-HMDP and received multi-frame micro-SPECT imaging after tracer distribution. Animal scans were reconstructed for three different acquisition times and post-processed with different sized Gaussian filters. Following reconstruction, CNR was calculated and image quality evaluated by three independent readers on a five-point scale from 1="very poor" to 5="very good". Point source sensitivity was 567 cps/MBq and radioactive rods as small as 1.2 mm were resolved with the UHR-RM collimator. Collimator-dependent uniformity was 55.5\%. Phantom CNR improved with increasing rod size, filter size and activity concentration. Left ventricle and bone structures were successfully visualized in rat experiments. Image quality was strongly affected by the extent of post-filtering, whereas scan time did not have substantial influence on visual assessment. Good image quality was achieved for resolution range greater than 1.8 mm in bone and 2.8 mm in heart. The recently introduced small animal SPECT system with two stationary detectors and UHR-RM collimator is capable to provide excellent image quality in heart and bone scans in a rat using standardized reconstruction parameters and appropriate post-filtering. However, there are still challenges in achieving maximum system resolution in the sub-millimeter range with in vivo settings under limited injection dose and acquisition time.},
  language  = {en}
}
@article{WernerHaenscheidLealetal.2018,
  author    = {Werner, Rudolf and H{\"a}nscheid, Heribert and Leal, Jeffrey P. and Javadi, Mehrbod S. and Higuchi, Takahiro and Lodge, Martin A. and Buck, Andreas K. and Pomper, Martin G. and Lapa, Constantin and Rowe, Steven P.},
  title     = {Impact of Tumor Burden on Quantitative [\(^{68}\)Ga]DOTATOC Biodistribution},
  series = {Molecular Imaging and Biology},
  journal   = {Molecular Imaging and Biology},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170280},
  pages     = {1-9},
  year      = {2018},
  abstract  = {Purpose: As has been previously reported, the somatostatin receptor (SSTR) imaging agent [\(^{68}\)Ga]-labeled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe(1)-Tyr(3)-octreotate ([\(^{68}\)Ga]DOTATATE) demonstrates lower uptake in normal organs in patients with a high neuroendocrine tumor (NET) burden. Given the higher SSTR affinity of [\(^{68}\)Ga]DOTATATE, we aimed to quantitatively investigate the biodistribution of [\(^{68}\)Ga]-labeled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe(1)-Tyr(3)-octreotide ([68Ga]DOTATOC) to determine a potential correlation between uptake in normal organs and NET burden. Procedures: Of the 44 included patients, 36/44 (82\%) patients demonstrated suspicious radiotracer uptake on [\(^{68}\)Ga]DOTATOC positron emission tomography (PET)/x-ray computed tomography (CT). Volumes of Interest (VOIs) were defined for tumor lesions and normal organs (spleen, liver, kidneys, adrenals). Mean body weight corrected standardized uptake value (SUV\(_{mean}\)) for normal organs was assessed and was used to calculate the corresponding mean specific activity uptake (Upt: fraction of injected activity per kg of tissue). For the entire tumor burden, SUV\(_{mean}\), maximum standardized uptake value (SUV\(_{max}\)), and the total mass (TBM) was calculated and the decay corrected tumor fractional uptake (TBU) was assessed. A Spearman's rank correlation coefficient was used to determine the correlations between normal organ uptake and tumor burden. Results: The median SUV\(_{mean}\) was 18.7 for the spleen (kidneys, 9.2; adrenals, 6.8; liver, 5.6). For tumor burden, the median values were SUV\(_{mean}\) 6.9, SUV\(_{max}\) 35.5, TBM 42.6g, and TBU 1.2\%. With increasing volume of distribution, represented by lean body mass and body surface area (BSA), Upt decreased in kidneys, liver, and adrenal glands and SUV\(_{mean}\) increased in the spleen. Correlation improved only for both kidneys and adrenals when the influence of the tumor uptake on the activity available for organ uptake was taken into account by the factor 1/(1-TBU). TBU was neither predictive for SUV\(_{mean}\) nor for Upt in any of the organs. The distribution of organ Upt vs. BSA/(1-TBU) were not different for patients with minor TBU (<3\%) vs. higher TBU (>7\%), indicating that the correlations observed in the present study are explainable by the body size effect. High tumor mass and uptake mitigated against G1 NET. Conclusions: There is no significant impact on normal organ biodistribution with increasing tumor burden on [\(^{68}\)Ga]DOTATOC PET/CT. Potential implications include increased normal organ dose with [\(^{177}\)Lu-DOTA]\(^0\)-D-Phe\(^1\)-Tyr\(^3\)-Octreotide and decreased absolute lesion detection with [\(^{68}\)Ga]DOTATOC in high NET burden.},
  subject      = {Positronen-Emissions-Tomografie},
  language  = {en}
}
@article{ChenWernerKoshinoetal.2022,
  author    = {Chen, Xinyu and Werner, Rudolf A. and Koshino, Kazuhiro and Nose, Naoko and M{\"u}hlig, Saskia and Rowe, Steven P. and Pomper, Martin G. and Lapa, Constantin and Decker, Michael and Higuchi, Takahiro},
  title     = {Molecular Imaging-Derived Biomarker of Cardiac Nerve Integrity - Introducing High NET Affinity PET Probe \(^{18}\)F-AF78},
  series = {Theranostics},
  volume    = {12},
  journal   = {Theranostics},
  number    = {9},
  doi       = {10.7150/thno.63205},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300685},
  pages     = {4446 -- 4458},
  year      = {2022},
  abstract  = {Background: Radiolabeled agents that are substrates for the norepinephrine transporter (NET) can be used to quantify cardiac sympathetic nervous conditions and have been demonstrated to identify high-risk congestive heart failure (HF) patients prone to arrhythmic events. We aimed to fully characterize the kinetic profile of the novel \(^{18}\)F-labeled NET probe AF78 for PET imaging of the cardiac sympathetic nervous system (SNS) among various species. Methods: \(^{18}\)F-AF78 was compared to norepinephrine (NE) and established SNS radiotracers by employing in vitro cell assays, followed by an in vivo PET imaging approach with healthy rats, rabbits and nonhuman primates (NHPs). Additionally, chase protocols were performed in NHPs with NET inhibitor desipramine (DMI) and the NE releasing stimulator tyramine (TYR) to investigate retention kinetics in cardiac SNS. Results: Relative to other SNS radiotracers, 18F-AF78 showed higher transport affinity via NET in a cell-based competitive uptake assay (IC\(^{50}\) 0.42 ± 0.14 µM), almost identical to that of NE (IC\(^{50}\), 0.50 ± 0.16 µM, n.s.). In rabbits and NHPs, initial cardiac uptake was significantly reduced by NET inhibition. Furthermore, cardiac tracer retention was not affected by a DMI chase protocol but was markedly reduced by intermittent TYR chase, thereby suggesting that \(^{18}\)F-AF78 is stored and can be released via the synaptic vesicular turnover process. Computational modeling hypothesized the formation of a T-shaped π-π stacking at the binding site, suggesting a rationale for the high affinity of \(^{18}\)F-AF78. Conclusion: \(^{18}\)F-AF78 demonstrated high in vitro NET affinity and advantageous in vivo radiotracer kinetics across various species, indicating that \(^{18}\)F-AF78 is an SNS imaging agent with strong potential to guide specific interventions in cardiovascular medicine.},
  language  = {en}
}
@article{WernerOrdonezSanchezBautistaetal.2019,
  author    = {Werner, Rudolf A. and Ordonez, Alvaro A. and Sanchez-Bautista, Julian and Marcus, Charles and Lapa, Constantin and Rowe, Steven P. and Pomper, Martin G. and Leal, Jeffrey P. and Lodge, Martin A. and Javadi, Mehrbod S. and Jain, Sanjay K. and Higuchi, Takahiro},
  title     = {Novel functional renal PET imaging with 18F-FDS in human subjects},
  series = {Clinical Nuclear Medicine},
  volume    = {44},
  journal   = {Clinical Nuclear Medicine},
  number    = {5},
  issn      = {0363-9762},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-174634},
  pages     = {410-411},
  year      = {2019},
  abstract  = {The novel PET probe 2-deoxy-2-18F-fluoro-D-sorbitol (18F-FDS) has demonstrated favorable renal kinetics in animals. We aimed to elucidate its imaging properties in two human volunteers. 18F-FDS was produced by a simple one-step reduction from 18F-FDG. On dynamic renal PET, the cortex was delineated and activity gradually transited in the parenchyma, followed by radiotracer excretion. No adverse effects were reported. Given the higher spatiotemporal resolution of PET relative to conventional scintigraphy, 18F-FDS PET offers a more thorough evaluation of human renal kinetics. Due to its simple production from 18F-FDG, 18F-FDS is virtually available at any PET facility with radiochemistry infrastructure.},
  subject      = {Positronen-Emissions-Tomografie},
  language  = {en}
}
@article{WernerWakabayashiChenetal.2019,
  author    = {Werner, Rudolf A. and Wakabayashi, Hiroshi and Chen, Xinyu and Hayakawa, Nobuyuki and Lapa, Constantin and Rowe, Steven P. and Javadi, Mehrbod S. and Robinson, Simon and Higuchi, Takahiro},
  title     = {Ventricular distribution pattern of the novel sympathetic nerve PET radiotracer \(^{18}\)F-LMI1195 in Rabbit Hearts},
  series = {Scientific Reports},
  volume    = {9},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-019-53596-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202707},
  pages     = {17026},
  year      = {2019},
  abstract  = {We aimed to determine a detailed regional ventricular distribution pattern of the novel cardiac nerve PET radiotracer \(^{18}\)F-LMI1195 in healthy rabbits. Ex-vivo high resolution autoradiographic imaging was conducted to identify accurate ventricular distribution of \(^{18}\)F-LMI1195. In healthy rabbits, \(^{18}\)F-LMI1195 was administered followed by the reference perfusion marker \(^{201}\)Tl for a dual-radiotracer analysis. After 20 min of \(^{18}\)F-LMI1195 distribution time, the rabbits were euthanized, the hearts were extracted, frozen, and cut into 20-μm short axis slices. Subsequently, the short axis sections were exposed to a phosphor imaging plate to determine \(^{18}\)F-LMI1195 distribution (exposure for 3 h). After complete \(^{18}\)F decay, sections were re-exposed to determine 201Tl distribution (exposure for 7 days). For quantitative analysis, segmental regions of Interest (ROIs) were divided into four left ventricular (LV) and a right ventricular (RV) segment on mid-ventricular short axis sections. Subendocardial, mid-portion, and subepicardial ROIs were placed on the LV lateral wall. \(^{18}\)F-LMI1195 distribution was almost homogeneous throughout the LV wall without any significant differences in all four LV ROIs (anterior, posterior, septal and lateral wall, 99 ± 2, 94 ± 5, 94 ± 4 and 97 ± 3\%LV, respectively, n.s.). Subepicardial \(^{201}\)Tl uptake was significantly lower compared to the subendocardial portion (subendocardial, mid-portion, and subepicardial activity: 90 ± 3, 96 ± 2 and *80 ± 5\%LV, respectively, *p < 0.01 vs. mid-portion). This was in contradistinction to the transmural wall profile of \(^{18}\)F-LMI1195 (90 ± 4, 96 ± 5 and 84 ± 4\%LV, n.s.). A slight but significant discrepant transmural radiotracer distribution pattern of \(^{201}\)Tl in comparison to \(^{18}\)F-LMI1195 may be a reflection of physiological sympathetic innervation and perfusion in rabbit hearts.},
  language  = {en}
}
@article{WernerHabachaLuetjeetal.2022,
  author    = {Werner, Rudolf A. and Habacha, Bil{\^e}l and L{\"u}tje, Susanne and Bundschuh, Lena and Higuchi, Takahiro and Hartrampf, Philipp and Serfling, Sebastian E. and Derlin, Thorsten and Lapa, Constantin and Buck, Andreas K. and Essler, Markus and Pienta, Kenneth J. and Eisenberger, Mario A. and Markowski, Mark C. and Shinehouse, Laura and AbdAllah, Rehab and Salavati, Ali and Lodge, Martin A. and Pomper, Martin G. and Gorin, Michael A. and Bundschuh, Ralph A. and Rowe, Steven P.},
  title     = {High SUVs Have More Robust Repeatability in Patients with Metastatic Prostate Cancer: Results from a Prospective Test-Retest Cohort Imaged with \(^{18}\)F-DCFPyL},
  series = {Molecular Imaging},
  volume    = {2022},
  journal   = {Molecular Imaging},
  doi       = {10.1155/2022/7056983},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300748},
  year      = {2022},
  abstract  = {No abstract available.},
  language  = {en}
}
@article{ChenKudoLapaetal.2020,
  author    = {Chen, Xinyu and Kudo, Takashi and Lapa, Constantin and Buck, Andreas and Higuchi, Takahiro},
  title     = {Recent advances in radiotracers targeting norepinephrine transporter: structural development and radiolabeling improvements},
  series = {Journal of Neural Transmission},
  volume    = {127},
  journal   = {Journal of Neural Transmission},
  doi       = {10.1007/s00702-020-02180-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-241148},
  pages     = {851-873},
  year      = {2020},
  abstract  = {The norepinephrine transporter (NET) is a major target for the evaluation of the cardiac sympathetic nerve system in patients with heart failure and Parkinson's disease. It is also used in the therapeutic applications against certain types of neuroendocrine tumors, as exemplified by the clinically used \(^{123/131}\)I-MIBG as theranostic single-photon emission computed tomography (SPECT) agent. With the development of more advanced positron emission tomography (PET) technology, more radiotracers targeting NET have been reported, with superior temporal and spatial resolutions, along with the possibility of functional and kinetic analysis. More recently, fluorine-18-labelled NET tracers have drawn increasing attentions from researchers, due to their longer radiological half-life relative to carbon-11 (110 min vs. 20 min), reduced dependence on on-site cyclotrons, and flexibility in the design of novel tracer structures. In the heart, certain NET tracers provide integral diagnostic information on sympathetic innervation and the nerve status. In the central nervous system, such radiotracers can reveal NET distribution and density in pathological conditions. Most radiotracers targeting cardiac NET-function for the cardiac application consistent of derivatives of either norepinephrine or MIBG with its benzylguanidine core structure, e.g. \(^{11}\)C-HED and \(^{18}\)F-LMI1195. In contrast, all NET tracers used in central nervous system applications are derived from clinically used antidepressants. Lastly, possible applications of NET as selective tracers over organic cation transporters (OCTs) in the kidneys and other organs controlled by sympathetic nervous system will also be discussed.},
  language  = {en}
}
@article{HartrampfLapaSerflingetal.2021,
  author    = {Hartrampf, Philipp E. and Lapa, Constantin and Serfling, Sebastian E. and Buck, Andreas K. and Seitz, Anna Katharina and Meyer, Philipp T. and Ruf, Juri and Michalski, Kerstin},
  title     = {Development of Discordant Hypermetabolic Prostate Cancer Lesions in the Course of [\(^{177}\)Lu]PSMA Radioligand Therapy and Their Possible Influence on Patient Outcome},
  series = {Cancers},
  volume    = {13},
  journal   = {Cancers},
  number    = {17},
  issn      = {2072-6694},
  doi       = {10.3390/cancers13174270},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-245168},
  year      = {2021},
  abstract  = {Simple Summary Discordant FDG-positive but PSMA-negative (FDG+/PSMA-) metastases constitute a negative prognostic marker of overall survival in patients undergoing PSMA radioligand therapy (RLT). The aim of this analysis was to investigate the prognostic implications of new FDG+/PSMA- lesions, which occur during or after PSMA RLT. In a retrospective bicentric analysis of 32 patients undergoing PSMA RLT and follow-up dual tracer staging with PSMA and FDG PET/CT, FDG+/PSMA- lesions occurred in a limited number of patients. However, the presence of FDG+/PSMA- lesions appears not to have a significant impact on the OS, but further studies are needed to establish the clinical relevance of such lesions. Abstract Introduction: Positron emission tomography/computer tomography (PET/CT) targeting the prostate-specific membrane antigen (PSMA) is crucial for the assessment of adequate PSMA expression in patients with metastatic castration-resistant prostate cancer (mCRPC) prior to PSMA radioligand therapy (PSMA RLT). Moreover, initial dual tracer staging using combined PSMA and [\(^{18}\)F]fluorodeoxyglucose (FDG) PET/CT provides relevant information, since discordant FDG-positive but PSMA-negative (FDG+/PSMA-) lesions constitute a negative prognostic marker of overall survival (OS) after PSMA RLT. However, little is known about the prognostic implications of dual tracer imaging for restaging at follow-up. The aim of this analysis was to investigate the prognostic implications of new FDG+/PSMA- lesions during or after PSMA RLT. Methods: This bicentric analysis included 32 patients with mCRPC who underwent both FDG and PSMA PET/CT imaging after two or four cycles of PSMA RLT. Patients with FDG+/PSMA- lesions prior to PSMA RLT were not considered. The presence of FDG+/PSMA- lesions was assessed with follow-up dual tracer imaging of patients after two or four cycles of PSMA RLT. Patients with at least one new FDG+/PSMA- lesion were compared to patients without any FDG+/PSMA- lesions at the respective time points. A log-rank analysis was used to assess the difference in OS between subgroups. Results: After two cycles of PSMA RLT, four of 32 patients (13\%) had FDG+/PSMA- metastases. No significant difference in OS was observed (p = 0.807), as compared to patients without FDG+/PSMA- lesions. Follow-up dual tracer imaging after the 4th cycle of PSMA RLT was available in 18 patients. Of these, four patients presented with FDG+/PSMA- findings (n = 2 already after two cycles). After the fourth cycle of PSMA RLT, no significant difference in OS was observed between patients with and without FDG+/PSMA- lesions (p = 0.442). Conclusion: This study shows that FDG+/PSMA- lesions develop in a limited number of patients undergoing PSMA RLT. Further studies are needed to establish the clinical relevance of such lesions.},
  language  = {en}
}
@article{ToyamaWernerRuizBedoyaetal.2021,
  author    = {Toyama, Yoshitaka and Werner, Rudolf A. and Ruiz-Bedoya, Camilo A. and Ordonez, Alvaro A. and Takase, Kei and Lapa, Constantin and Jain, Sanjay K. and Pomper, Martin G. and Rowe, Steven P. and Higuchi, Takahiro},
  title     = {Current and future perspectives on functional molecular imaging in nephro-urology: theranostics on the horizon},
  series = {Theranostics},
  volume    = {11},
  journal   = {Theranostics},
  number    = {12},
  doi       = {10.7150/thno.58682},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260090},
  pages     = {6105-6119},
  year      = {2021},
  abstract  = {In recent years, a paradigm shift from single-photon-emitting radionuclide radiotracers toward positron-emission tomography (PET) radiotracers has occurred in nuclear oncology. Although PET-based molecular imaging of the kidneys is still in its infancy, such a trend has emerged in the field of functional renal radionuclide imaging. Potentially allowing for precise and thorough evaluation of renal radiotracer urodynamics, PET radionuclide imaging has numerous advantages including precise anatomical co-registration with CT images and dynamic three-dimensional imaging capability. In addition, relative to scintigraphic approaches, PET can allow for significantly reduced scan time enabling high-throughput in a busy PET practice and further reduces radiation exposure, which may have a clinical impact in pediatric populations. In recent years, multiple renal PET radiotracers labeled with C-11, Ga-68, and F-18 have been utilized in clinical studies. Beyond providing a precise non-invasive read-out of renal function, such radiotracers may also be used to assess renal inflammation. This manuscript will provide an overview of renal molecular PET imaging and will highlight the transformation of conventional scintigraphy of the kidneys toward novel, high-resolution PET imaging for assessing renal function. In addition, future applications will be introduced, e.g. by transferring the concept of molecular image-guided diagnostics and therapy (theranostics) to the field of nephrology.},
  language  = {en}
}
@article{MatsusakaWernerAriasLozaetal.2022,
  author    = {Matsusaka, Yohji and Werner, Rudolf A. and Arias-Loza, Paula and Nose, Naoko and Sasaki, Takanori and Chen, Xinyu and Lapa, Constantin and Higuchi, Takahiro},
  title     = {Performance Evaluation of a Preclinical SPECT Scanner with a Collimator Designed for Medium-Sized Animals},
  series = {Molecular Imaging},
  volume    = {2022},
  journal   = {Molecular Imaging},
  doi       = {10.1155/2022/9810097},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300713},
  year      = {2022},
  abstract  = {Background. Equipped with two stationary detectors, a large bore collimator for medium-sized animals has been recently introduced for dedicated preclinical single-photon emission computed tomography (SPECT) imaging. We aimed to evaluate the basic performance of the system using phantoms and healthy rabbits. Methods. A general-purpose medium-sized animal (GP-MSA) collimator with 135 mm bore diameter and thirty-three holes of 2.5 mm diameter was installed on an ultrahigh-resolution scanner equipped with two large stationary detectors (U-SPECT5-E/CT). The sensitivity and uniformity were investigated using a point source and a cylinder phantom containing 99mTc-pertechnetate, respectively. Uniformity (in \%) was derived using volumes of interest (VOIs) on images of the cylinder phantom and calculated as , with lower values of \% indicating superior performance. The spatial resolution and contrast-to-noise ratios (CNRs) were evaluated with images of a hot-rod Derenzo phantom using different activity concentrations. Feasibility of in vivo SPECT imaging was finally confirmed by rabbit imaging with the most commonly used clinical myocardial perfusion SPECT agent [99mTc]Tc-sestamibi (dynamic acquisition with a scan time of 5 min). Results. In the performance evaluation, a sensitivity of 790 cps/MBq, a spatial resolution with the hot-rod phantom of 2.5 mm, and a uniformity of 39.2\% were achieved. The CNRs of the rod size 2.5 mm were 1.37, 1.24, 1.20, and 0.85 for activity concentration of 29.2, 1.0, 0.5, and 0.1 MBq/mL, respectively. Dynamic SPECT imaging in rabbits allowed to visualize most of the thorax and to generate time-activity curves of the left myocardial wall and ventricular cavity. Conclusion. Preclinical U-SPECT5-E/CT equipped with a large bore collimator demonstrated adequate sensitivity and resolution for in vivo rabbit imaging. Along with its unique features of SPECT molecular functional imaging is a superior collimator technology that is applicable to medium-sized animal models and thus may promote translational research for diagnostic purposes and development of novel therapeutics.},
  language  = {en}
}
@article{DaViaSolimandoGaritanoTrojaolaetal.2019,
  author    = {Da Vi{\`a}, Matteo Claudio and Solimando, Antonio Giovanni and Garitano-Trojaola, Andoni and Barrio, Santiago and Munawar, Umair and Strifler, Susanne and Haertle, Larissa and Rhodes, Nadine and Vogt, Cornelia and Lapa, Constantin and Beilhack, Andreas and Rasche, Leo and Einsele, Hermann and Kort{\"u}m, K. Martin},
  title     = {CIC Mutation as a Molecular Mechanism of Acquired Resistance to Combined BRAF-MEK Inhibition in Extramedullary Multiple Myeloma with Central Nervous System Involvement},
  series = {The Oncologist},
  volume    = {25},
  journal   = {The Oncologist},
  number    = {2},
  doi       = {10.1634/theoncologist.2019-0356},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219549},
  pages     = {112-118},
  year      = {2019},
  abstract  = {Combined MEK-BRAF inhibition is a well-established treatment strategy in BRAF-mutated cancer, most prominently in malignant melanoma with durable responses being achieved through this targeted therapy. However, a subset of patients face primary unresponsiveness despite presence of the activating mutation at position V600E, and others acquire resistance under treatment. Underlying resistance mechanisms are largely unknown, and diagnostic tests to predict tumor response to BRAF-MEK inhibitor treatment are unavailable. Multiple myeloma represents the second most common hematologic malignancy, and point mutations in BRAF are detectable in about 10\% of patients. Targeted inhibition has been successfully applied, with mixed responses observed in a substantial subset of patients mirroring the widespread spatial heterogeneity in this genomically complex disease. Central nervous system (CNS) involvement is an extremely rare, extramedullary form of multiple myeloma that can be diagnosed in less than 1\% of patients. It is considered an ultimate high-risk feature, associated with unfavorable cytogenetics, and, even with intense treatment applied, survival is short, reaching less than 12 months in most cases. Here we not only describe the first patient with an extramedullary CNS relapse responding to targeted dabrafenib and trametinib treatment, we furthermore provide evidence that a point mutation within the capicua transcriptional repressor (CIC) gene mediated the acquired resistance in this patient.},
  language  = {en}
}