172 results on '"Platzek, I."'
Search Results
2. Overestimation of grey matter atrophy in glioblastoma patients following radio(chemo)therapy
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Gommlich, A., Raschke, F., Petr, J., Seidlitz, A., Jentsch, C., Platzek, I., van den Hoff, J., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Krause, M., and Troost, E. G. C.
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- 2022
- Full Text
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3. MRI-guided active surveillance in patients with ISUP 1 prostate cancer – A multi-institutional validation of the discrimination of the PRECISE Score
- Author
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Sushentsev, N., primary, Wiesenfarth, M., additional, Dixius, M., additional, Kastner, C., additional, Borkowetz, A., additional, Platzek, I., additional, Thomas, C., additional, Kesch, C., additional, Umutlu, L., additional, Reis, H., additional, Rau, T., additional, Lenders, L., additional, Spahn, M., additional, Boschheidgen, M., additional, Antoch, G., additional, Albers, P., additional, Barrett, T., additional, Schimmöller, L., additional, Hadaschik, B., additional, and Radtke, J.P., additional
- Published
- 2024
- Full Text
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4. Radiomics for residual tumour detection and prognosis in newly diagnosed glioblastoma based on postoperative [11C] methionine PET and T1c‑w MRI
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Shahzadi, I., Seidlitz, A., Beuthien‑Baumann, B., Zwanenburg, A., Platzek, I., Kotzerke, J., Baumann, M., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., (0000-0002-7017-3738) Löck, S., Shahzadi, I., Seidlitz, A., Beuthien‑Baumann, B., Zwanenburg, A., Platzek, I., Kotzerke, J., Baumann, M., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., and (0000-0002-7017-3738) Löck, S.
- Abstract
Personalized treatment strategies based on non‑invasive biomarkers have potential to improve patient management in patients with newly diagnosed glioblastoma (GBM). The residual tumour burden after surgery in GBM patients is a prognostic imaging biomarker. However, in clinical patient management, its assessment is a manual and time‑consuming process that is at risk of inter‑rater variability. Furthermore, the prediction of patient outcome prior to radiotherapy may identify patient subgroups that could benefit from escalated radiotherapy doses. Therefore, in this study, we investigate the capabilities of traditional radiomics and 3D convolutional neural networks for automatic detection of the residual tumour status and to prognosticate time‑to‑recurrence (TTR) and overall survival (OS) in GBM using postoperative [11C] methionine positron emission tomography (MET‑PET) and gadolinium‑enhanced T1‑w magnetic resonance imaging (MRI). On the independent test data, the 3D‑DenseNet model based on MET‑PET achieved the best performance for residual tumour detection, while the logistic regression model with conventional radiomics features performed best for T1c‑w MRI (AUC: MET‑PET 0.95, T1c‑w MRI 0.78). For the prognosis of TTR and OS, the 3D‑DenseNet model based on MET‑PET integrated with age and MGMT status achieved the best performance (Concordance‑Index: TTR 0.68, OS 0.65). In conclusion, we showed that both deep‑ learning and conventional radiomics have potential value for supporting image‑based assessment and prognosis in GBM. After prospective validation, these models may be considered for treatment personalization.
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- 2024
5. Comparison of sequential and high-pitch-spiral coronary CT-angiography: image quality and radiation exposure
- Author
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Seppelt, D., Kolb, C., Kühn, J. P., Speiser, U., Radosa, C. G., Hoberück, S., Hoffmann, R. T., and Platzek, I.
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- 2019
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6. Clinical Relevance of Computed Tomography Pulmonary Venography
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Braun, S.D., Platzek, I., Danowski, D., Zöphel, K., Weise, M., Kolditz, M., Katzke, S., Strasser, R.H., Höffken, G., and Halank, M.
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- 2016
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7. Reduction of intrafraction pancreas motion using an abdominal corset compatible with proton therapy and MRI
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(0000-0002-5771-5213) Schneider, S., (0000-0002-8107-1649) Stefanowicz, S., Jentsch, C., (0000-0003-4043-7066) Lohaus, F., Thiele, J., Haak, D., (0000-0001-6814-1131) Valentini, C., (0000-0002-5933-8108) Platzek, I., (0000-0001-9550-9050) Troost, E. G. C., (0000-0002-5821-3135) Hoffmann, A. L., (0000-0002-5771-5213) Schneider, S., (0000-0002-8107-1649) Stefanowicz, S., Jentsch, C., (0000-0003-4043-7066) Lohaus, F., Thiele, J., Haak, D., (0000-0001-6814-1131) Valentini, C., (0000-0002-5933-8108) Platzek, I., (0000-0001-9550-9050) Troost, E. G. C., and (0000-0002-5821-3135) Hoffmann, A. L.
- Abstract
Background and Purpose: Motion mitigation is of crucial importance in particle therapy (PT) of patients with abdominal tumors to ensure high-precision irradiation. Magnetic resonance imaging (MRI) is an excellent modality for target volume delineation and motion estimation of mobile soft-tissue tumors. Thus, the aims of this study were to develop an MRI- and PT-compatible abdominal compression device, to investigate its effect on pancreas motion reduction, and to evaluate patient tolerability and acceptance. Materials and Methods: In a prospective clinical study, 16 patients with abdominal tumors received an individualized polyethylene-based abdominal corset. Pancreas motion was analyzed using time- and phase resolved MRI scans (orthogonal 2D-cine and 4D MRI) with and without compression by the corset. The pancreas was manually segmented in each MRI data set and the population-averaged center-of-mass motion in inferior-superior (IS), anterior-posterior (AP) and left-right (LR) directions was determined. A questionnaire was developed to investigate the level of patient acceptance of the corset, which the patients completed after acquisition of the planning computed tomography (CT) and MRI scans. Results: The corset was found to reduce pancreas motion predominantly in IS direction by on average 47 % - 51 % as found in the 2D-cine and 4D MRI data, respectively, while motion in the AP and LR direction was not significantly reduced. Most patients reported no discomfort when wearing the corset. Conclusion: An MRI- and PT-compatible individualized abdominal corset was presented, which substantially reduced breathing-induced pancreas motion and can be safely applied with no additional discomfort for the patients. The corset has been successfully integrated into our in-house clinical workflow for PT of tumors of the upper abdomen.
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- 2023
8. Serum miRNAs unterstützen die Entscheidungsfindung bezüglich einer Prostatastanzbiopsie speziell bei Patienten mit niedrigen PI-RADS scores
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Keck, B, Borkowetz, A, Poellmann, J, Jansen, T, Fischer, M, Fuessel, S, Kahlmeyer, A, Wirth, M, Huber, J, Cavallaro, A, Hammon, M, Platzek, I, Hartmann, A, Baretton, G, Kunath, F, Sikic, D, Taubert, H, Wullich, B, Erdmann, K, Wach, S, Keck, B, Borkowetz, A, Poellmann, J, Jansen, T, Fischer, M, Fuessel, S, Kahlmeyer, A, Wirth, M, Huber, J, Cavallaro, A, Hammon, M, Platzek, I, Hartmann, A, Baretton, G, Kunath, F, Sikic, D, Taubert, H, Wullich, B, Erdmann, K, and Wach, S
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- 2022
9. Time- and dose-dependent volume decreases in subcortical grey matter structures of glioma patients after radio(chemo)therapy
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(0000-0002-1054-9609) Raschke, F., Witzmann, K., Seidlitz, A., Wesemann, T., Jentsch, C., Platzek, I., Hoff, J., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Linn, J., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., (0000-0002-1054-9609) Raschke, F., Witzmann, K., Seidlitz, A., Wesemann, T., Jentsch, C., Platzek, I., Hoff, J., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Linn, J., (0000-0003-1776-9556) Krause, M., and (0000-0001-9550-9050) Troost, E. G. C.
- Abstract
Background and purpose: Radiotherapy (RT) is an adjuvant treatment option for glioma patients. Side effects include tissue atrophy, which might be a contributing factor to neurocognitive decline after treatment. The goal of this study was to determine potential atrophy of the hippocampus, amygdala, thalamus, putamen, pallidum and caudate nucleus in glioma patients having undergone magnetic resonance imaging (MRI) before and after RT. Materials and methods: Subcortical volumes were measured using T1-weighted MRI from patients before RT (N = 91) and from longitudinal follow-ups acquired in three-monthly intervals (N = 349). The volumes were normalized to the baseline values, while excluding structures touching the clinical target volume (CTV) or abnormal tissue seen on FLAIR imaging. A multivariate linear effects model was used to determine if time after RT and mean RT dose delivered to the corresponding structures were significant predictors of tissue atrophy. Results: The hippocampus, amygdala, thalamus, putamen, and pallidum showed significant atrophy after RT as function of both time after RT and mean RT dose delivered to the corresponding structure. Only the caudate showed no dose or time dependant atrophy. Conversely, the hippocampus was the structure with the highest atrophy rate of 5.2 % after one year and assuming a mean dose of 30 Gy. Conclusion: The hippocampus showed the highest atrophy rates followed by the thalamus and the amygdala. The subcortical structures here found to decrease in volume indicative of radiosensitivity should be the focus of future studies investigating the relationship between neurocognitive decline and RT. © 2022 The Authors
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- 2022
10. Prostatakarzinom: Diagnostik
- Author
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Wirth, M., primary, Fröhner, M., additional, Platzek, I., additional, Laniado, M., additional, and Kotzerke, J., additional
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- 2015
- Full Text
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11. Reduced diffusion in white matter after radiotherapy with photons and protons
- Author
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Dünger, L., primary, Seidlitz, A., additional, Jentsch, C., additional, Platzek, I., additional, Kotzerke, J., additional, Beuthien-Baumann, B., additional, Baumann, M., additional, Krause, M., additional, Troost, E.G.C., additional, and Raschke, F., additional
- Published
- 2021
- Full Text
- View/download PDF
12. Reduction of respiratory pancreas motion using an MRI and proton therapy compatible abdominal corset
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Schneider, S., Stefanowicz, S., Jentsch, C., Lohaus, F., Valentini, C., Platzek, I., Troost, E. G. C., and Hoffmann, A. L.
- Subjects
abdominal compression ,time resolved MRI ,MR guided radiation therapy ,4D MRI - Abstract
Objectives: An MRI- and particle therapy compatible patient-individualized abdominal corset was developed and its efficacy to reduce respiratory-induced pancreas motion was evaluated by orthogonal 2D-cine and 4D-MRI. Patients & Methods: Nine patients (6 female; average age 72.9±9.6 years) with tumors of the pancreas (7), gallbladder (1), or liver (1) provided written informed consent to be scanned on a 3T MRI scanner (Philips Healthcare) by means of orthogonal 2D-cine and 4D-MRI, without and with a patient-individualized abdominal corset, respectively. A polyethylene (PE) abdominal corset (ORD Dresden GmbH) was customized based on an optical 3D-surface scan (Artec Eva®). For MR imaging the patients were positioned supine on a flat tabletop using an anterior coil holder to avoid compression of the chest wall. For 2D-cine MRI, coronal and sagittal slices were selected to image the pancreatic head. The 4D-MRI dataset was reconstructed by retrospectively resorting a multi-slice 2D acquisition into 10 respiratory phases. Pancreas motion was determined as center-of-mass displacement in three orthogonal directions (inferior-superior (IS), anterior-posterior (AP), left-right (LR)). Results and Conclusion: MRI revealed predominant motion in IS direction, which was reduced by 42% (p
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- 2021
13. Reduced white matter diffusion in glioblastoma patients after radiotherapy with photons and protons
- Author
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Dünger, L., Raschke, F., Seidlitz, A., Jentsch, C., Platzek, I., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Krause, M., and Troost, E. G. C.
- Abstract
Introduction: Radio(chemo)therapy is standard in the (adjuvant) treatment of glioblastoma. Inevitably, brain tissue surrounding the tumor bed or residual tumor is also irradiated, which may lead to acute and late side-effects. Diffusion-weighted imaging (DWI) with magnetic resonance imaging (MRI) has been shown to be a sensitive method to detect early changes in the cerebral white matter after radiation. The aim of this work was to assess possible changes in the mean diffusivity (MD) of the white matter after radio(chemo)therapy using DWI and to compare these effects between patients treated with proton and photon irradiation. Patients & methods: 70 patients diagnosed with glioblastoma underwent adjuvant radio(chemo)therapy with protons (n=20) or photons (n=50). MRI follow-up examinations were performed at three-monthly intervals and were evaluated until 33 months after the end of therapy. For all time points, MD maps were calculated and normal appearing white matter was segmented in T1-weighted MR images. Relative white matter MD changes between baseline and all follow-up visits were calculated in different dose regions. Results: We observed a significant decrease of MD (mean -4,0%, range -0,8 ¬– -7,9%, p
- Published
- 2021
14. Reduzierung von respirationsbedingter Pankreasbewegung mittels eines MRT- und Partikeltherapie-kompatiblen abdominellen Korsetts
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Schneider, S., Stefanowicz, S., Jentsch, C., Lohaus, F., Valentini, C., Platzek, I., Troost, E., and Hoffmann, A.
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intrafraktionelle Bewegung ,MRT geführte Partikeltherapie ,Pankreaskarzinom - Abstract
Fragestellung: Die intrafraktionelle Bewegung von abdominellen Tumoren erfordert entsprechend große Sicherheitssäume in der Radioonkologie und führt zu einer erhöhten Strahlenbelastung des umliegenden gesunden Gewebes. Für die geplante Magnetresonanztomographie (MRT)-geführte Partikeltherapie (PT) von Pankreaskarzinomen wurde ein innovatives, patientenspezifisches abdominelles Korsett zur Reduktion der atmungsbedingten Pankreasbewegung entwickelt, welches die hohen Materialansprüche der MRT sowie der PT erfüllt. Das Maß an Bewegungsreduktion durch das Korsetts und dessen Verträglichkeit wurde in einer Patientenstudie untersucht. Methodik: Vorbereitend wurden drei abdominelle Korsetts unterschiedlicher Beschaffenheit und Patientenindividualität in ihrer Anwendbarkeit für die MRT-geführte PT bei abdominellen Tumoren untersucht. Das Modell, das die höchste Reproduzierbarkeit in der PT bei Oberbauchtumoren ermöglichte und so eine konformale Strahlentherapie ermöglichte, wurde in einer durch die lokale Ethikkommissioin gebilligte Patientenstudie getestet. Für 12 Patienten (neun weiblich, Alter 71.6±8.6 Jahre) mit Tumoren des Oberbauchs wurde ein Polyethylene-Korsett individuell hergestellt. An einem 3T MRT Scanner wurden von den Patienten sowohl mit Korsett als direkt darauffolgend auch ohne Korsett unter freier Atmung zeitauflösende Bildsequenzen (orthogonale 2D-cine MRT und retrospektiv rekonstruierte 4D-MRT) akquiriert. Das Pankreas wurde in allen Bildern manuell konturiert und die Bewegung des Massenschwerpunktes zwischen maximaler Inspiration und Exspiration in 3D analysiert. Basierend auf einem detaillierten Erhebungsbogen wurde die Verträglichkeit des Korsetts in klinischer Anwendung untersucht. Ergebnis: Durch Applikation des Korsetts wurde bei hoher Patientenverträglichkeit eine Reduktion der Pankreasbewegung vorwiegend in der Hauptrichtung der Atmung (inferior-superior) um 49% (p
- Published
- 2021
15. Dose dependent cerebellar atrophy in glioma patients after radio(chemo)therapy
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(0000-0002-1054-9609) Raschke, F., Seidlitz, A., Wesemann, T., Löck, S., Jentsch, C., Platzek, I., (0000-0002-3201-6002) Petr, J., (0000-0003-4039-4780) Hoff, J., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Linn, J., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., (0000-0002-1054-9609) Raschke, F., Seidlitz, A., Wesemann, T., Löck, S., Jentsch, C., Platzek, I., (0000-0002-3201-6002) Petr, J., (0000-0003-4039-4780) Hoff, J., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Linn, J., (0000-0003-1776-9556) Krause, M., and (0000-0001-9550-9050) Troost, E. G. C.
- Abstract
Background and purpose: Radiotherapy is a standard treatment option for high-grade gliomas. Cognitive impairment is a side effect associated with radiotherapy particularly in long-term survivors. Recent findings suggest involvement of the cerebellum in cognitive function. The goal of this study was therefore to investigate dose dependent cerebellar atrophy using prospective, longitudinal MR data from adult glioma patients who received radiotherapy. Materials and methods: Cerebellar volumes were measured using T1-weighted MR images from 91 glioma patients before radiotherapy and every three months thereafter. We calculated the average cerebellar volume change per year per Gy, based on the mean cerebellar dose, using linear regression analysis. Subsequently, patient age was investigated as a confounding factor using multiple linear regression analysis. The impact of chemotherapy was assessed separately in a subgroup of patients receiving a cerebellar dose ≤ 1 Gy. Cerebellar mean dose and cerebellar volume changes were compared between patients treated with proton (N = 38) and photon therapy (N = 52). Results: Cerebellar volume decreased 2.4 % per 10 Gy per year (p < 0.001). The cerebellar volume loss was progressive over time without signs of recovery within the observational period of two years. Neither patient age (p = 0.27) nor chemotherapy (p = 0.43) had a significant impact on cerebellar atrophy. Compared to patients treated with photons, the cerebellar dose was significantly lower in patients treated with proton therapy (p < 0.001, r = 0.62) which also translated to a significantly lower cerebellar volume reduction per year (p = 0.016, r = 0.25). Conclusion: Cerebellar volume decreased significantly and irreversibly after radiotherapy as function of time and dose. Further work is now needed to correlate these results with cognitive function and motor performance.
- Published
- 2021
16. Final Results of the Prospective Biomarker Trial PETra: [11C]-MET-Accumulation in Postoperative PET/MRI Predicts Outcome after Radiochemotherapy in Glioblastoma
- Author
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Seidlitz, A., Beuthien-Baumann, B., Löck, S., Jentsch, C., Platzek, I., Zöphel, K., Linge, A., Kotzerke, J., (0000-0002-3201-6002) Petr, J., Hoff, J., Steinbach, J., Krex, D., Schmitz-Schackert, G., Falk, M., Baumann, M., (0000-0003-1776-9556) Krause, M., Seidlitz, A., Beuthien-Baumann, B., Löck, S., Jentsch, C., Platzek, I., Zöphel, K., Linge, A., Kotzerke, J., (0000-0002-3201-6002) Petr, J., Hoff, J., Steinbach, J., Krex, D., Schmitz-Schackert, G., Falk, M., Baumann, M., and (0000-0003-1776-9556) Krause, M.
- Abstract
Purpose: This prospective trial investigates the association of time to recurrence (TTR) in glioblastoma with [11C]methionine (MET) tracer uptake before postoperative radiochemotherapy (RCT) aiming to guide radiotherapy boost regions. Experimental Design: Between 2013 and 2016, 102 patients with glioblastoma were recruited. RCT was performed with concurrent and adjuvant temozolomide to a total dose of 60 Gy. Tumor residues in postresection PET and MRI were together defined as gross tumor volumes for radiotherapy treatment planning. [11C]methionine (MET)-PET/MRI was performed before RCT and at each follow-up. Results: The primary hypothesis of a longer TTR for patients without increased tracer accumulation in postoperative MET-PET was confirmed in 89 patients. With 18.9 months (95% confidence interval, 9.3–28.5 months), median TTR was significantly (P < 0.001) longer for patients without (n = 29, 32.6%) as compared with 6.3 months (3.6–8.9) for patients with MET accumulation (n = 60, 67.4%) in pre-RCT PET. Although MRI often did not detect all PET-positive regions, an unfavorable impact of residual tumor in postsurgical MRI (n = 38, 42.7%) on TTR was observed [4.6 (4.2–5.1) vs. 15.5 months (6.0–24.9), P < 0.001]. Significant multivariable predictors for TTR were MRI positivity, PET-positive volume, and O6-methylguanine DNA methyltransferase (MGMT) hypermethylation. Conclusions: Postsurgical amino acid PET has prognostic value for TTR after RCT in glioblastoma. Because of the added value of the metabolic beyond the pure structural information, it should complement MRI in radiotherapy planning if available with reasonable effort, at least in the context of maximal therapy. Furthermore, the spatial correlation of regions of recurrence with PET-positive volumes could provide a bioimaging basis for further trials, for example, testing local radiation dose escalation.
- Published
- 2021
17. Reduced diffusion in white matter after radiotherapy with photons and protons
- Author
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Dünger, L., Seidlitz, A., Jentsch, C., Platzek, I., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., (0000-0002-1054-9609) Raschke, F., Dünger, L., Seidlitz, A., Jentsch, C., Platzek, I., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., and (0000-0002-1054-9609) Raschke, F.
- Abstract
Background and purpose Radio(chemo)therapy is standard in the adjuvant treatment of glioblastoma. Inevitably, brain tissue surrounding the target volume is also irradiated, potentially causing acute and late side-effects. Diffusion imaging has been shown to be a sensitive method to detect early changes in the cerebral white matter (WM) after radiation. The aim of this work was to assess possible changes in the mean diffusivity (MD) of WM after radio(chemo)therapy using Diffusion-weighted imaging (DWI) and to compare these effects between patients treated with proton and photon irradiation. Materials and methods 70 patients with glioblastoma underwent adjuvant radio(chemo)therapy with protons (n = 20) or photons (n = 50) at the University Hospital Dresden. MRI follow-ups were performed at three-monthly intervals and in this study were evaluated until 33 months after the end of therapy. Relative white matter MD changes between baseline and all follow-up visits were calculated in different dose regions. Results We observed a significant decrease of MD (p < 0.05) in WM regions receiving more than 20 Gy. MD reduction was progressive with dose and time after radio(chemo)therapy (maximum: −7.9 ± 1.2% after 24 months, ≥50 Gy). In patients treated with photons, significant reductions of MD in the entire WM (p < 0.05) were seen at all time points. Conversely, in proton patients, whole brain MD did not change significantly. Conclusions Irradiation leads to measurable MD reduction in white matter, progressing with both increasing dose and time. Treatment with protons reduces this effect most likely due to a lower total dose in the surrounding white matter. Further investigations are needed to assess whether those MD changes correlate with known radiation induced side-effects.
- Published
- 2021
18. Overestimation of grey matter atrophy in glioblastoma patients following radio(chemo)therapy
- Author
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Gommlich, A., primary, Raschke, F., additional, Petr, J., additional, Seidlitz, A., additional, Jentsch, C., additional, Platzek, I., additional, van den Hoff, J., additional, Kotzerke, J., additional, Beuthien-Baumann, B., additional, Baumann, M., additional, Krause, M., additional, and Troost, E. G. C., additional
- Published
- 2021
- Full Text
- View/download PDF
19. Cerebellar volume reduction after photon or proton radio(chemo)therapy of glioblastoma patients
- Author
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Raschke, F., Seidlitz, A., Platzek, I., Beuthien-Baumann, B., Hoff, J., Krex, D., Kotzerke, J., Jentsch, C., Baumann, M., Krause, M., and Troost, E. G. C.
- Subjects
cerebellum ,atrophy ,irradiation ,proton therapy ,normal tissue ,radiotherapy ,photon therapy - Abstract
Purpose or Objective: Radio(chemo)therapy is part of the standard treatment of high-grade glioma patients and has been associated with cerebral atrophy [1,2]. Preclinical work also suggests radiation induced atrophy of the cerebellum [3,4]. Investigating cerebellar atrophy in patients treated with radiation is a further step in understanding radiation-induced deficits in both motor function and cognition. The aim of this study was to investigate cerebellar volume changes in a cohort of glioblastoma patients treated with photon or proton radio(chemo)therapy. Material and Methods: Data was acquired on a 3T Philips Ingenuity TF PET/MRI scanner (Philips Healthcare, Best, The Netherlands) as part of a prospective, longitudinal study investigating the effect of 11C-methionine PET/MR for tailoring the treatment of patients with glioblastoma (NCT01873469). In total, 71 patients with cerebral GBM (21 treated with proton therapy) had a baseline MR and at least one follow-up MRI, obtained in 3 monthly intervals after irradiation, available, including 3D T1-weighted (T1w) imaging (1×1×1 mm3) before and after intravenous injection of contrast agent (CE). Patients were treated with a total dose of 60 Gy(RBE=1.1) delivered in 2Gy fractions. On average 3.6 follow-ups were available covering a time period of 413 days ± 432 days (mean ± SD). The cerebellum was cut out from each MRI by warping [5] the MNI152 brain atlas and a corresponding cerebellar mask to each brain extracted T1w MRI. Sigmoid and transverse sinuses mimicking cerebellar tissue were removed using the CE T1w MRI. The cerebellum was segmented into grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF) [6]. Its volume was calculated as the sum of all GM and WM probabilities and normalized to the baseline value for each patient. The mean relative cerebellar volume change per year was estimated for each patient with a linear regression. The resulting rate of volume change per year was plotted against the mean dose delivered to the cerebellum across all patients, and the rate of volume change per year per dose was subsequently estimated using a linear regression. Results: Figure 1 illustrates segmentation of the cerebellum. Mean cerebellar dose for patients treated with protons and photons was 1.7Gy ± 2.1Gy and 5.7Gy ± 4.6Gy, respectively. The linear model estimated a cerebellar volume loss of approx. 1.8% per 10Gy per year (p
- Published
- 2020
20. Cerebellar volume reduction after photon or proton radio(chemo)therapy of glioblastoma patients
- Author
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(0000-0002-1054-9609) Raschke, F., Seidlitz, A., Platzek, I., Beuthien-Baumann, B., Hoff, J., Krex, D., Kotzerke, J., Jentsch, C., Baumann, M., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., (0000-0002-1054-9609) Raschke, F., Seidlitz, A., Platzek, I., Beuthien-Baumann, B., Hoff, J., Krex, D., Kotzerke, J., Jentsch, C., Baumann, M., (0000-0003-1776-9556) Krause, M., and (0000-0001-9550-9050) Troost, E. G. C.
- Abstract
Purpose or Objective: Radio(chemo)therapy is part of the standard treatment of high-grade glioma patients and has been associated with cerebral atrophy [1,2]. Preclinical work also suggests radiation induced atrophy of the cerebellum [3,4]. Investigating cerebellar atrophy in patients treated with radiation is a further step in understanding radiation-induced deficits in both motor function and cognition. The aim of this study was to investigate cerebellar volume changes in a cohort of glioblastoma patients treated with photon or proton radio(chemo)therapy. Material and Methods: Data was acquired on a 3T Philips Ingenuity TF PET/MRI scanner (Philips Healthcare, Best, The Netherlands) as part of a prospective, longitudinal study investigating the effect of 11C-methionine PET/MR for tailoring the treatment of patients with glioblastoma (NCT01873469). In total, 71 patients with cerebral GBM (21 treated with proton therapy) had a baseline MR and at least one follow-up MRI, obtained in 3 monthly intervals after irradiation, available, including 3D T1-weighted (T1w) imaging (1×1×1 mm3) before and after intravenous injection of contrast agent (CE). Patients were treated with a total dose of 60 Gy(RBE=1.1) delivered in 2Gy fractions. On average 3.6 follow-ups were available covering a time period of 413 days ± 432 days (mean ± SD). The cerebellum was cut out from each MRI by warping [5] the MNI152 brain atlas and a corresponding cerebellar mask to each brain extracted T1w MRI. Sigmoid and transverse sinuses mimicking cerebellar tissue were removed using the CE T1w MRI. The cerebellum was segmented into grey matter (GM), white matter (WM) and cerebrospinal fluid (CSF) [6]. Its volume was calculated as the sum of all GM and WM probabilities and normalized to the baseline value for each patient. The mean relative cerebellar volume change per year was estimated for each patient with a linear regression. The resulting rate of volume change per year was plotted against the mean d
- Published
- 2020
21. Dose dependent cerebellar atrophy in glioma patients after radio(chemo)therapy
- Author
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(0000-0002-1054-9609) Raschke, F., Seidlitz, A., Wesemann, T., Löck, S., Jentsch, C., Platzek, I., (0000-0002-3201-6002) Petr, J., (0000-0003-4039-4780) Hoff, J., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Linn, J., (0000-0003-1776-9556) Krause, M., (0000-0001-9550-9050) Troost, E. G. C., (0000-0002-1054-9609) Raschke, F., Seidlitz, A., Wesemann, T., Löck, S., Jentsch, C., Platzek, I., (0000-0002-3201-6002) Petr, J., (0000-0003-4039-4780) Hoff, J., Kotzerke, J., Beuthien-Baumann, B., Baumann, M., Linn, J., (0000-0003-1776-9556) Krause, M., and (0000-0001-9550-9050) Troost, E. G. C.
- Abstract
Background and purpose: Radiotherapy is a standard treatment option for high-grade gliomas. Cognitive impairment is a side effect associated with radiotherapy particularly in long-term survivors. Recent findings suggest involvement of the cerebellum in cognitive function. The goal of this study was therefore to investigate dose dependent cerebellar atrophy using prospective, longitudinal MR data from adult glioma patients who received radiotherapy. Materials and methods: Cerebellar volumes were measured using T1-weighted MR images from 91 glioma patients before radiotherapy and every three months thereafter. We calculated the average cerebellar volume change per year per Gy, based on the mean cerebellar dose, using linear regression analysis. Subsequently, patient age was investigated as a confounding factor using multiple linear regression analysis. The impact of chemotherapy was assessed separately in a subgroup of patients receiving a cerebellar dose ≤ 1 Gy. Cerebellar mean dose and cerebellar volume changes were compared between patients treated with proton (N = 38) and photon therapy (N = 52). Results: Cerebellar volume decreased 2.4 % per 10 Gy per year (p < 0.001). The cerebellar volume loss was progressive over time without signs of recovery within the observational period of two years. Neither patient age (p = 0.27) nor chemotherapy (p = 0.43) had a significant impact on cerebellar atrophy. Compared to patients treated with photons, the cerebellar dose was significantly lower in patients treated with proton therapy (p < 0.001, r = 0.62) which also translated to a significantly lower cerebellar volume reduction per year (p = 0.016, r = 0.25). Conclusion: Cerebellar volume decreased significantly and irreversibly after radiotherapy as function of time and dose. Further work is now needed to correlate these results with cognitive function and motor performance.
- Published
- 2020
22. T-Staging and Target Volume Definition by Imaging in Head and Neck Tumors
- Author
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Platzek, I., Agolli, L., Beuthien-Baumann, B., (0000-0001-9550-9050) Troost, E. G. C., Platzek, I., Agolli, L., Beuthien-Baumann, B., and (0000-0001-9550-9050) Troost, E. G. C.
- Abstract
Anatomical and functional imaging by means of computed tomography, magnetic resonance imaging, and positron emission tomography are, besides a thorough physical examination, of utmost importance for accurate staging of primary tumors in the head and neck region. This chapter deals with the particular advan-tages and disadvantages of those imaging techniques and gives practical guidance on how to employ these in radiation treatment planning.
- Published
- 2020
23. OC-0691: Cerebellar volume reduction after photon or proton radio(chemo)therapy of glioblastoma patients
- Author
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RaschkE, F., primary, Seidlitz, A., additional, Platzek, I., additional, Beuthien-Baumann, B., additional, Van den Hoff, J., additional, Krex, D., additional, Kotzerke, J., additional, Jentsch, C., additional, Baumann, M., additional, Krause, M., additional, and Troost, E., additional
- Published
- 2020
- Full Text
- View/download PDF
24. Übersetzung von Vorhersagemodellen in Entscheidungsempfehlungen für klinische Entscheidungsträger
- Author
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Wach, S, Kahlmeyer, A, Borkowetz, A, Füssel, S, Cavallaro, A, Hammon, M, Platzek, I, Hartmann, A, Baretton, G, Taubert, H, Wullich, B, Keck, B, Wach, S, Kahlmeyer, A, Borkowetz, A, Füssel, S, Cavallaro, A, Hammon, M, Platzek, I, Hartmann, A, Baretton, G, Taubert, H, Wullich, B, and Keck, B
- Published
- 2019
25. FDG-PET/MRI in patients with pelvic recurrence of rectal cancer: first clinical experiences
- Author
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Plodeck, V., Rahbari, N., Weitz, J., Radosa, C., Laniado, M., Hoffmann, R., Zoephel, K., Beuthien-Baumann, B., Kotzerke, J., (0000-0003-4039-4780) Hoff, J., Platzek, I., Plodeck, V., Rahbari, N., Weitz, J., Radosa, C., Laniado, M., Hoffmann, R., Zoephel, K., Beuthien-Baumann, B., Kotzerke, J., (0000-0003-4039-4780) Hoff, J., and Platzek, I.
- Abstract
Objectives To determine the value of 18F-FDG-PET/MRI in the diagnosis and management of patients with pelvic recurrence of rectal cancer. Methods Forty-four patients (16 women, 28 men) with a history of rectal cancer who received FDG-PET/MRI between June 2011 and February 2017 at our institution were retrospectively enrolled. Three patients received two FDG-PET/MRIs; thus a total of 47 examinations were included. Pelvic recurrence was confirmed either with histology (n = 27) or imaging follow-up (n = 17) (> 4 months). Two readers (one radiologist, one nuclear medicine physician) interpreted the images in consensus. Pelvic lesions were assessed regarding FDG uptake and morphology. Sensitivity, specificity, positive and negative predictive values as well as accuracy of PET/MRI in detecting recurrence were determined. Results In 47 FDG-PET/MRIs 30 suspicious pelvic lesions were identified, 29 of which were malignant. Two patients underwent resection and had histologically proven pelvic recurrence without showing suspicious findings on FDG-PET/MRI. Changes in management due to FDG-PET/MRI findings had been implemented in eight patients. Eighty per cent (16/20) of resected patients had histologically negative resection margins (R0), one patient had uncertain resection margins. Sensitivity of FDG-PET/MRI in detecting recurrence was 94%, specificity 94%, positive/negative predictive value and accuracy were 97%, 90% and 94%, respectively. Conclusions FDG-PET/MRI is a valuable tool in the diagnosis and staging of pelvic recurrence in patients with rectal cancer.
- Published
- 2019
26. Independent validation of tumour volume, cancer stem cell markers and hypoxia-associated gene expressions for HNSCC after primary radiochemotherapy
- Author
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Linge, A., Schmidt, S., Baumann, M., Krenn, C., Bandurska-Luque, A., Platzek, I., Neubeck, V. C., Appold, S., Nowak, A., Gudziol, V., Buchholz, F., Baretton, B. B., Lohaus, F., Löck, S., (0000-0003-1776-9556) Krause, M., Linge, A., Schmidt, S., Baumann, M., Krenn, C., Bandurska-Luque, A., Platzek, I., Neubeck, V. C., Appold, S., Nowak, A., Gudziol, V., Buchholz, F., Baretton, B. B., Lohaus, F., Löck, S., and (0000-0003-1776-9556) Krause, M.
- Abstract
Objective: To independently validate the impact of tumour volume, p16 status, cancer stem cell (CSC) marker expression and hypoxia-associated gene signatures as potential prognostic biomarkers for patients with locally advanced head and neck squamous cell carcinoma (HNSCC), who underwent primary radiotherapy or radiochemotherapy (RCTx). These markers have previously been reported in a study of the German Cancer Consortium Radiation Oncology Group (DKTK-ROG) (Linge et al., 2016). Materials and methods: In this retrospective monocentric study, 92 patients with locally advanced HNSCC were included. Univariable and multivariable logistic regressions and Cox models presented in the study of the DKTK-ROG were validated using the area under the curve (AUC) and the concordance index (ci), respectively. The primary endpoint of this study was loco-regional tumour control (LRC) after primary RCTx. Results: Although both cohorts significantly differed in the proportion of the tumour subsites, the parameters tumour volume, p16 status and N stage could be validated regarding LRC and overall survival (OS) using multivariable Cox regression (LRC ci: 0.59, OS ci: 0.63). These models were slightly improved by combination with the putative CSC marker CD44 (LRC ci: 0.61, OS ci: 0.69). The logistic regression model for 2-year LRC based on tumour volume, p16 status and CD44 protein was validated with an AUC of 0.64. The patient stratification based on hypoxia-associated gene signatures status was similar to the original study but without significant differences in LRC and OS. Conclusions: In this validation study, the inclusion of the putative CSC marker CD44 slightly improved the prognostic performance of the baseline parameters tumour volume, p16 status and N stage. No improvement was observed when including expressions of the hypoxia-associated gene signatures. Prospective validation on a larger cohort is warranted to assess the clinical relevance of these markers.
- Published
- 2019
27. Dual-time-point 64Cu-PSMA-617-PET/CT in patients suffering from prostate cancer
- Author
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Hoberück, S., Wunderlich, G., Michler, E., Hölscher, T., Walther, M., Seppelt, D., Platzek, I., Zöphel, K., Kotzerke, J., Hoberück, S., Wunderlich, G., Michler, E., Hölscher, T., Walther, M., Seppelt, D., Platzek, I., Zöphel, K., and Kotzerke, J.
- Abstract
Regardless of its high positron energy, 68Ga-labeled PSMA ligands have become standard of care in metabolic prostate cancer imaging. 64Cu, a radionuclide with a much longer half-life (12.7 h), is available for PSMA labeling allowing imaging much later than 68Ga. In this study, the diagnostic performance of 64Cu-labeled PSMA was compared between early and late scans. Sixteen men (median age: 70 y) with prostate cancer in different stages underwent 64Cu-PSMA-617-PET/CT 2 and 22 hours post tracer injection. Pathologic and physiologic uptakes were analyzed for both points of time. Pathologic tracer accumulations occurred in 12 patients. Five patients presented with pathologic uptake in 17 different lymph nodes, two patients showed pathologic bone uptake in nine lesions, and seven patients had pathologic PSMA uptake in eight prostatic lesions. Physiologic uptake of the renal parenchyma, urine bladder, and salivary glands decreased over time, while the physiologic uptake of liver and bowel increased. In the present study, 64Cu-PSMA-617-PET demonstrated to be feasible for imaging prostate cancer for both the primary tumor site and metastases. Later imaging showed no additional, clinically relevant benefit compared with the early scans. At least the investigated time points we chose did not vindicate the additional expenditure.
- Published
- 2019
28. Late-delayed perfusion decrease following radiochemotherapy in glioblastoma patients
- Author
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Petr, J., Mutsaerts, H. J. M. M., Platzek, I., Keil, V. C., Hofheinz, F., Asllani, I., Seidlitz, A., Petrova, M., Troost, E. G. C., Krause, M., and Hoff, J.
- Abstract
Temozolomide-based radiochemotherapy (RCT) is a treatment standard for glioblastoma patients. However, RCT is associated with risks of neurocognitive decline. Perfusion is a possible early marker of tissue damage and has been shown to correlate with cognitive changes in many diseases. Perfusion decrease at 3 to 6 months after RT was recently reported in glioblastoma patients. However, it remains unclear whether the decrease is reversible and thus possibly a precursor of the late-delayed cognitive changes. In this study, we have measured perfusion changes up to 18 months following RCT. No further progress of perfusion deficits was found indicating that the early perfusion decrease is predictive of late perfusion decrease and might thus be connected with cognitive decline.
- Published
- 2018
29. [11C]-Methionine-PET/MRI is superior to MRI alone for detecting residual tumor burden in glioblastoma multiforme undergoing radical radiochemotherapy – analysis of a prospective trial
- Author
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Beuthien-Baumann, B., Seidlitz, A., Platzek, I., Petr, J., Kotzerke, J., Jentsch, C., Löck, S., Zessin, J., Krex, D., Zöphel, K., Schackert, G., Hoff, J., Baumann, M., and Krause, M.
- Subjects
Positronen-Emissions-Tomographie ,[11C]Methionin ,Glioblastoma - Abstract
kein Abstrakt vorhanden
- Published
- 2018
30. Vergleich von Ga-68-PSMA und Ga-68-RM2 bei Patienten mit Prostatakarzinom
- Author
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Hoberück, S, additional, Michler, E, additional, Platzek, I, additional, Wunderlich, G, additional, Zöphel, K, additional, and Kotzerke, J, additional
- Published
- 2019
- Full Text
- View/download PDF
31. OC-0594: Postoperative [11C]MET-PET predicts radiochemotherapy outcome in glioblastoma: a prospective trial
- Author
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Krause, M., Seidlitz, A., Löck, S., Jentsch, C., Platzek, I., Zöphel, K., Petr, J., Hoff, J., Steinbach, J., Krex, D., Schackert, G., Falk, M., Baumann, M., Beuthien-Baumann, B., Krause, M., Seidlitz, A., Löck, S., Jentsch, C., Platzek, I., Zöphel, K., Petr, J., Hoff, J., Steinbach, J., Krex, D., Schackert, G., Falk, M., Baumann, M., and Beuthien-Baumann, B.
- Abstract
Despite combined modality treatment involving surgery and adjuvant radiotherapy, a relevant percentage of chordoma and chondrosarcoma patients develop a local recurrence. In a previous study, we identified optic apparatus and/or brainstem compression, histology and GTV volume as prognostic factors for the risk of local failure. The present study aims to analyze patterns of recurrence and correlate local control with a detailed dosimetric analysis.
- Published
- 2018
32. Photon vs. proton radiochemotherapy: effects on brain tissue volume and perfusion
- Author
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Petr, J., Platzek, I., Hofheinz, F., Mutsaerts, H., Asllani, I., Osch, M., Seidlitz, A., Krukowski, P., Gommlich, A., Beuthien-Baumann, B., Jentsch, C., Maus, J., Troost, E., Baumann, M., Krause, M., Hoff, J., Petr, J., Platzek, I., Hofheinz, F., Mutsaerts, H., Asllani, I., Osch, M., Seidlitz, A., Krukowski, P., Gommlich, A., Beuthien-Baumann, B., Jentsch, C., Maus, J., Troost, E., Baumann, M., Krause, M., and Hoff, J.
- Abstract
Background and Purpose: To compare the structural and hemodynamic changes of healthy brain tissue in the cerebral hemisphere contralateral to the tumor following photon and proton radiochemotherapy. Materials and Methods: Sixty-seven patients (54.9±14.0 years) diagnosed with glioblastoma multiforme undergoing adjuvant photon (n=47) or proton (n=19) radiochemotherapy with temozolomide after tumor resection underwent T1-weighted and arterial spin labeling MRI. Changes in volume and perfusion before and 3 to 6 months after were compared between therapies. Results: A decrease in gray matter (GM) (-2.2%, P<0.001) and white matter (WM) (-1.2%, P<0.001) volume was observed in photon-therapy patients compared to the pre-radiotherapy baseline. In contrast, for the protontherapy group, no significant differences in GM (0.3%, P=0.64) or WM (-0.4%, P=0.58) volume were observed. GM volume decreased with 0.9% per 10 Gy dose increase (P<0.001) and differed between the radiation modalities (P<0.001). Perfusion decreased in photon-therapy patients (-10.1%, P=0.002), whereas the decrease in proton-therapy patients, while comparable in magnitude, did not reach statistical significance (-9.1%, P=0.12). There was no correlation between perfusion decrease and either dose (P=0.64) or radiation modality (P=0.94). Conclusion: Our results show that the tissue volume decrease depends on radiation dose delivered to the healthy hemisphere and differs between treatment modalities. In contrast, the decrease in perfusion was comparable for both irradiation modalities. We conclude that proton therapy may reduce brain-volume loss when compared to photon therapy.
- Published
- 2018
33. Perfusion decrease during radiochemotherapy is not fully explained by volumetric gray matter changes
- Author
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Petr, J., Mutsaerts, H., Hofheinz, F., Asllani, I., Osch, M., Platzek, I., Seidlitz, A., Krause, M., and Hoff, J.
- Subjects
atrophy ,ASL ,cardiovascular system ,glioblastoma ,radiochemotherapy ,partial volume ,sense organs ,skin and connective tissue diseases ,perfusion ,circulatory and respiratory physiology - Abstract
Radiochemotherapy in brain-tumor patients was shown to cause gray matter (GM) volume and cerebral blood flow (CBF) changes. The interaction of these two effects, however, remains unclear. Here, we investigated GM volume and ASL CBF changes and their interaction in the healthy hemisphere of 38 glioblastoma patients undergoing radiochemotherapy with Temozolomide. We found a statistically significant CBF decrease with dependence on the RT-dose. PV-corrected results indicated that, while to a certain extent the apparent CBF decrease measured by ASL is caused by GM atrophy, there still remain significant CBF changes that cannot be explained by structural changes alone.
- Published
- 2017
34. Added utility of quantitative diffusion imaging in PSMA-PET-MRI for classification of small pelvic lymph nodes
- Author
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Apolle, R., Platzek, I., Borkowetz, A., Hölscher, T., Kotzerke, J., and Miederer, M.
- Published
- 2024
- Full Text
- View/download PDF
35. OC-0594: Postoperative [11C]MET-PET predicts radiochemotherapy outcome in glioblastoma: a prospective trial
- Author
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Krause, M., primary, Seidlitz, A., additional, Löck, S., additional, Jentsch, C., additional, Platzek, I., additional, Zöphel, K., additional, Petr, J., additional, Van den hoff, J., additional, Steinbach, J., additional, Krex, D., additional, Schackert, G., additional, Falk, M., additional, Baumann, M., additional, and Beuthien-Baumann, B., additional
- Published
- 2018
- Full Text
- View/download PDF
36. Prediction of significant prostate cancer in patients with previously negative prostate biopsy undergoing MRI/ultrasound-fusion biopsy in combination with systematic biopsy
- Author
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Borkowetz, A., primary, Renner, T., additional, Schlumberger, G., additional, Platzek, I., additional, Toma, M., additional, Froehner, M., additional, Zastrow, S., additional, and Wirth, M., additional
- Published
- 2018
- Full Text
- View/download PDF
37. Brain volume loss in glioblastoma patients following photon and proton radiochemotherapy
- Author
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Petr, J., Hofheinz, F., Gommlich, A., Raschke, F., Troost, E., Beuthien-Baumann, B., Seidlitz, A., Platzek, I., Baumann, M., Krause, M., Hoff, J., Petr, J., Hofheinz, F., Gommlich, A., Raschke, F., Troost, E., Beuthien-Baumann, B., Seidlitz, A., Platzek, I., Baumann, M., Krause, M., and Hoff, J.
- Abstract
Gray matter (GM) atrophy in healthy brain tissue following radiochemotherapy was shown in brain-tumor patients in several studies. Here, we aimed to study GM and white matter (WM) changes in glioblastoma patients undergoing photon (n=43) and proton (n=12) radiochemotherapy. In photon-therapy patients, a statistically significant decrease of both GM (~2%) and WM (1.3-2.3%) volume was found with a positive influence of the RT-dose on the GM volume loss. In proton-therapy patients, no significant changes in GM and WM volumes were observed after therapy. This indicates that the proton-therapy has the potential to reduce structural GM changes in healthy tissue.
- Published
- 2017
38. Perfusion decrease in healthy tissue following radiochemotherapy in glioblastoma patients
- Author
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Petr, J., Platzek, I., Seidlitz, A., Hofheinz, F., Maus, J., Beuthien-Baumann, B., Krause, M., and Hoff, J.
- Abstract
Ziel/Aim: Decrease of perfusion as a side-effect of radio-chemotherapy was observed in several organs (1). However, the relation between the decrease and the radiation dose was not yet extensively studied. Non-invasive measurement of perfusion is now possible with a native MRI sequence called arterial spin labeling (ASL) (2) which offers a semi-quantitative alternative to [O-15]H2O PET measurement. The ASL measurement was used to study the regional perfusion changes in healthy tissue of glioblastoma patients undergoing radiochemotherapy. Methodik/Methods: Twenty-five patients (age 55.0±14.2 years) with glioblastoma multiforme were scanned in two (n=25) or three (n=13) sessions with interval 4.8 and 8.1 months from the first session, respectively. The ASL scan was co-registered with the treatment-planning CT and the dose plan. Perfusion changes between sessions were calculated in the hemisphere contralateral to the tumor. The perfusion changes were evaluated also in regions created by categorizing the individual dose maps into 10 Gy steps. Ergebnisse/Results: The relative perfusion decrease between the first two sessions was not significant (-2.4% and -7.5%) for the low dose regions 0 and 20 Gy. For the high-dose regions, the change was statistically significant and a decrease of -13.3% (20-30 Gy), -18.0% (30-40 Gy), -16.2% (40-50 Gy), and -16.8% (50-60 Gy) was observed. No further decrease of perfusion was observed on the third session. The mean regional changes were between -1.4% and 3.0% and the results were not statistically significant for any dose. Schlussfolgerungen/Conclusions: Global decrease of perfusion was observed in healthy tissue 3 months after the radiochemotherapy. The decrease was correlated with the dose received. No further decrease of perfusion was observed 6 months after the therapy.
- Published
- 2016
39. Klinische Bedeutung der CT Pulmonalis-Venografie
- Author
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Braun, S, additional, Platzek, I, additional, Danowski, D, additional, Zöphel, K, additional, Weise, M, additional, Kolditz, M, additional, Katzke, S, additional, Strasser, R, additional, Höffken, G, additional, and Halank, M, additional
- Published
- 2017
- Full Text
- View/download PDF
40. Correction of quantification errors in pelvic and spinal lesions caused by ignoring higher photon attenuation of bone in [18F]NaF PET/MR
- Author
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Schramm, G., Maus, J., Hofheinz, F., Petr, J., Lougovski, A., Beuthien-Baumann, B., Oehme, L., Platzek, I., and Hoff, J.
- Subjects
PET/MRI ,attenuation correction ,quantification - Abstract
Purpose: MR-based attenuation correction (MRAC) in routine clinical whole-body positron emission tomography and magnetic resonance imaging (PET/MRI) is based on tissue type segmentation. Due to lack of MR signal in cortical bone and the varying signal of spongeous bone, standard whole-body segmentation-based MRAC ignores the higher attenuation of bone compared to the one of soft tissue (MRACnobone). The authors aim to quantify and reduce the bias introduced by MRACnobone in the standard uptake value (SUV) of spinal and pelvic lesions in 20 PET/MRI examinations with [18F]NaF. Methods: The authors reconstructed 20 PET/MR [18F]NaF patient data sets acquired with a Philips Ingenuity TF PET/MRI. The PET raw data were reconstructed with two different attenuation images. First, the authors used the vendor-provided MRAC algorithm that ignores the higher attenuation of bone to reconstruct PETnobone. Second, the authors used a threshold-based algorithm developed in their group to automatically segment bone structures in the [18F]NaF PET images. Subsequently, an attenuation coefficient of 0.11 cm−1 was assigned to the segmented bone regions in the MRI-based attenuation image (MRACbone) which was used to reconstruct PETbone. The automatic bone segmentation algorithm was validated in six PET/CT [18F]NaF examinations. Relative SUVmean and SUVmax differences between PETbone and PETnobone of 8 pelvic and 41 spinal lesions, and of other regions such as lung, liver, and bladder, were calculated. By varying the assigned bone attenuation coefficient from 0.11 to 0.13 cm−1, the authors investigated its influence on the reconstructed SUVs of the lesions. Results: The comparison of [18F]NaF-based and CT-based bone segmentation in the six PET/CT patients showed a Dice similarity of 0.7 with a true positive rate of 0.72 and a false discovery rate of 0.33. The [18F]NaF-based bone segmentation worked well in the pelvis and spine. However, it showed artifacts in the skull and in the extremities. The analysis of the 20 [18F]NaF PET/MRI examinations revealed relative SUVmax differences between PETnobone and PETbone of (−8.8% ± 2.7%, p = 0.01) and (−8.1% ± 1.9%, p = 2.4×10−8) in pelvic and spinal lesions, respectively. A maximum SUVmax underestimation of −13.7% was found in lesion in the third cervical spine. The averaged SUVmean differences in volumes of interests in lung, liver, and bladder were below 3%. The average SUVmax differences in pelvic and spinal lesions increased from −9% to −18% and −8% to −17%, respectively, when increasing the assigned bone attenuation coefficient from 0.11 to 0.13 cm−1. Conclusions: The developed automatic [18F]NaF PET-based bone segmentation allows to include higher bone attenuation in whole-body MRAC and thus improves quantification accuracy for pelvic and spinal lesions in [18F]NaF PET/MRI examinations. In nonbone structures (e.g., lung, liver, and bladder), MRACnobone yields clinically acceptable accuracy.
- Published
- 2015
41. Test-retest variability of quantitative MRI perfusion measurements with ASL underclinical conditions
- Author
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Petr, J., Schramm, G., Platzek, I., Hofheinz, F., and Hoff, J.
- Abstract
Ziel/Aim: While [O-15]H2O PET is still considered the gold-standard for brain perfusion measurement, a native MRI sequence called arterial spin labeling (ASL) which offers a semi-quantitative alternative becomes increasingly relevant in the clinical setting and might be especially relevant for applications in combined PET/MR systems. For ASL, an accuracy and repeatability comparable to that of PET has been reported. A serious limitation of the respective studies is the fact that mainly young healthy subjects were used. Also, time and subject comfort were sacrificed to reach high repeatability. Our aim was to test the repeatability of ASL under realistic clinical conditions on elderly cancer patients. Methodik/Methods: Fifteen patients (age 55.5±12.8 years) with glioblastoma were scanned in two or more sessions (in total 21 sessions, 125±37 days apart). We used a pseudo-continuous ASL sequence with background suppression and 2D multi-slice readout, labeling time/delay 1525/1650 ms, voxel size 2.75x2.75x6.6mm3, and standard CBF quantification (1). Mean CBF was assessed for regions corresponding to anterior cerebral artery (ACA), posterior CA, middle CA, and vertebral artery, respectively, on the contralateral side from the tumor. Repeatability index and mean relative CBF difference was assed for the two sessions for all regions. Ergebnisse/Results: The whole-brain mean CBF was 33.0±4.9 mL/min/100 g (45.5±6.1 mL/min/100 g in gray matter). The repeatability index was 30.4%, 34.3%, 29.7%, 31.5% and 36.8% in whole brain, ACA, MCA, PCA and VA regions, respectively. The mean relative difference between sessions for whole brain was 18.9% (range 0.4-63.0%, median 17.1%). Schlussfolgerungen/Conclusions: The repeatability index is close to the values measured by Heijtel (2) in healthy volunteers (27.6% for PET, 25.1% for ASL). A slight decrease in repeatability in elderly patients is to be expected. The mean gray matter perfusion is slightly lower than in (2) (48.5±5.6 in PET, 50.8±6.5 mL/min/100 g for ASL) which might be attributed to the known decline of CBF in elderly subjects. Our results thus show that pCASL measurements yield stable CBF values even under clinical conditions. Literatur/References: (1) Alsop, et al. Magnetic Resonance in Medicine. 2014. (2) Heijtel, et al. NeuroImage, 92:182-92(2014).
- Published
- 2015
42. Stability of MR Brain Perfusion Measurement Using Arterial Spin Labeling
- Author
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Petr, J., Hofheinz, F., Platzek, I., Schramm, G., and Hoff, J.
- Subjects
otorhinolaryngologic diseases - Abstract
Reproducibility of ASL perfusion measurements.
- Published
- 2015
43. Evaluation of in vivo quantification accuracy of the Ingenuity-TF PET/MR
- Author
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Maus, J., Schramm, G., Hofheinz, F., Oehme, L., Lougovski, A., Petr, J., Platzek, I., Beuthien-Baumann, B., Steinbach, J., Kotzerke, J., and Hoff, J.
- Subjects
PET/MR ,in vivo ,quantitative evaluation ,quantification accuracy ,truncation compensation - Abstract
Purpose: The quantitative accuracy of standardized uptake values (SUVs) and tracer kinetic uptake parameters in patient investigations strongly depends on accurate determination of regional activity concentrations in positron emission tomography (PET) data. This determination rests on the assumption that the given scanner calibration is valid in vivo. In a previous study, we introduced a method to test this assumption. This method allows to identify discrepancies in quantitative accuracy in vivo by comparison of activity concentrations of urine samples measured in a well-counter with activity concentrations extracted from PET images of the bladder. In the present study, we have applied this method to the Philips Ingenuity-TF PET/MR since at the present stage, absolute quantitative accuracy of combined PET/MR systems is still under investigation. Methods: Twenty one clinical whole-body F18-FDG scans were included in this study. The bladder region was imaged as the last bed position and urine samples were collected afterward. PET images were reconstructed including MR-based attenuation correction with and without truncation compensation and 3D regions-of-interest (ROIs) of the bladder were delineated by three observers. To exclude partial volume effects, ROIs were concentrically shrunk by 8–10 mm. Then, activity concentrations were determined in the PET images for the bladder and for the urine by measuring the samples in a calibrated well-counter. In addition, linearity measurements of SUV vs singles rate and measurements of the stability of the coincidence rate of “true” events of the PET/MR system were performed over a period of 4 months. Results: The measured in vivo activity concentrations were significantly lower in PET/MR than in the well-counter with a ratio of the former to the latter of 0.756±0.060 (mean ± std. dev.), a range of 0.604–0.858, and a P value of 3.9·10−14. While the stability measurements of the coincidence rate of “true” events showed no relevant deviation over time, the linearity scans revealed a systematic error of 8%–11% (avg. 9%) for the range of singles rates present in the bladder scans. After correcting for this systematic bias caused by shortcomings of the manufacturers calibration procedure, the PET to well-counter ratio increased to 0.832±0.064 (0.668–0.941), P = 1.1·10−10. After compensating for truncation of the upper extremities in the MR-based attenuation maps, the ratio further improved to 0.871±0.069 (0.693–0.992), P = 3.9·10−8. Conclusions: Our results show that the Philips PET/MR underestimates activity concentrations in the bladder by 17%, which is 7 percentage points (pp.) larger than in the previously investigated PET and PET/CT systems. We attribute this increased underestimation to remaining limitations of the MRbased attenuation correction. Our results suggest that only a 2 pp. larger underestimation of activity concentrations compared to PET/CT can be observed if compensation of attenuation truncation of the upper extremities is applied. Thus, quantification accuracy of the Philips Ingenuity-TF PET/MR can be considered acceptable for clinical purposes given the ±10% error margin in the EANM guidelines. The comparison of PET images from the bladder region with urine samples has proven a useful method. It might be interesting for evaluation and comparison of the in vivo quantitative accuracy of PET, PET/CT, and especially PET/MR systems from different manufacturers or in multicenter trials.
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- 2015
44. Versorgung von Parkinson-Patienten in neurologischen Schwerpunktpraxen in Berlin (NeuroPa-Studie)
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Ehret, R, Balzer-Geldsetzer, M, Reese, J.P, Dodel, I, Becker, E, Christopher, A, Friedrich, H, Kraemer, S, Lüer, W, Müngersdorf, M, Puzich, R, Schultes-Platzek, I, Siefjediers, V, Tiel-Wilck, K, and Dodel, R
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- 2024
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45. Inanspruchnahme medizinischer Leistungen und Versorgungsmuster von Parkinson-Patienten in neurologischen Schwerpunktpraxen in Berlin (NeuroPa-Studie)
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Reese, JP, Balzer-Geldsetzer, M, Dodel, R, Becker, E, Christopher, A, Friedrich, H, Kraemer, S, Lüer, W, Müngersdorf, M, Puzich, R, Rohr, A, Schultes-Platzek, I, Siefjediers, V, Tiel-Wilck, K, and Ehret, R
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- 2024
- Full Text
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46. Bandscheibendegeneration nach Skolioseoperation
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Hentschel, S, Seifert, J, Platzek, I, Thielemann, F, Bernstein, P, Hentschel, S, Seifert, J, Platzek, I, Thielemann, F, and Bernstein, P
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- 2016
47. Early and late effects of radiochemotherapy on cerebral blood flow in glioblastoma patients measured with non-invasive perfusion MRI
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Petr, J., Platzek, I., Seidlitz, A., Mutsaerts, H. J. M. M., Hofheinz, F., Schramm, G., Maus, J., Beuthien-Baumann, B., Krause, M., Hoff, J., Petr, J., Platzek, I., Seidlitz, A., Mutsaerts, H. J. M. M., Hofheinz, F., Schramm, G., Maus, J., Beuthien-Baumann, B., Krause, M., and Hoff, J.
- Abstract
Background and purpose: To provide a systematic measure of changes of brain perfusion in healthy tissue following a fractionated radiotherapy of brain tumors. Materials and methods: Perfusion was assessed before and after radiochemotherapy using arterial spin labeling in a group of 24 patients (mean age 54.3±14.1 years) with glioblastoma multiforme. Mean relative perfusion change in gray matter in the hemisphere contralateral to the tumor was obtained for the whole hemisphere and also for six regions created by thresholding the individual dose maps at 10 Gy steps. Results: A significant decrease of perfusion of -9.8 ± 20.9% (p = 0.032) compared to the pre-treatment baseline was observed 3 months after the end of radiotherapy. The decrease was more pronounced for high-dose regions above 50 Gy (-16.8 ± 21.0%, p = 0.0014) than for low-dose regions below 10 Gy (-2.3 ± 20.0%, p = 0.54). No further significant decrease compared to the post-treatment baseline was observed 6 months (-0.4 ± 18.4%, p = 0.94) and 9 months (2.0 ± 15.4%, p = 0.74) after the end of radiotherapy. Conclusions: Perfusion decreased significantly during the course of radiochemotherapy. The decrease was higher in regions receiving a higher dose of radiation. This suggests that the perfusion decrease is at least partly caused by radiotherapy. Our results suggest that the detrimental effects of radiochemotherapy on perfusion occur early rather than later.
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- 2016
48. 779 Comparison of MRI/ultrasound-fusion-biopsy to systematic prostate biopsy in prediction of final histopathology in prostatectomy specimen
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Borkowetz, A., primary, Platzek, I., additional, Toma, M., additional, Renner, T., additional, Fröhner, M., additional, Zastrow, S., additional, and Wirth, M., additional
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- 2016
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49. 503 Evaluation of PI-RADS classification in prediction of tumor-aggressiveness in targeted biopsy
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Borkowetz, A., primary, Platzek, I., additional, Toma, M., additional, Renner, T., additional, Fröhner, M., additional, Koch, R., additional, Zastrow, S., additional, and Wirth, M., additional
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- 2016
- Full Text
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50. Evaluation of the influence of truncation artifacts using in-vivo based quantification accuracy methods in combined PET/MRI
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Maus, J., Schramm, G., Hofheinz, F., Oehme, L., Lougovski, A., Petr, J., Platzek, I., Beuthien-Baumann, B., Steinbach, J., Kotzerke, J., Hoff, J., Maus, J., Schramm, G., Hofheinz, F., Oehme, L., Lougovski, A., Petr, J., Platzek, I., Beuthien-Baumann, B., Steinbach, J., Kotzerke, J., and Hoff, J.
- Abstract
Aim: Quantitative accuracy of standardized uptake values (SUV) and tracer kinetic uptake parameters in patient investigations requires determination of regional activity concentrations in PET data. This determination rests on the assumption that the scanner calibration is valid in-vivo. In a recent study we introduced a method to test this assumption. For 3 different PET and PET/CT systems the activity concentration of urine samples measured in a well-counter were compared to those derived from PET images of the bladder. The study demonstrated a low but systematic underestimation of 7-12% of PET relative to a cross-calibrated well-counter for 56 subjects. In the present study we have applied this method to the Philips Ingenuity-TF PET/MR to evalute the impact of MR-based truncation artifcats on the overall quantitative accuracy of this system. Methods: 21 clinical whole-body F18-FDG scans were included in this study. The bladder region was imaged as the last bed position and urine samples were collected afterwards. PET images were reconstructed including MR-based attenuation correction with and without truncation compensation and 3D region-of-interests (ROI) of the bladder were delineated by 3 observers. Activity concentrations were determined in the PET images for the bladder as well as for the urine by measuring the samples in a well-counter. Results: The in-vivo activity concentrations of the bladder were significantly lower in PET/MR than in the well-counter with a ratio of the former to the latter of 0.756?0.060 (mean?std.dev.) and a range of [0.604-0.858]. Linearity scans revealed a systematic error of 8-11 % (avg. 9 %). After correcting for this systematic bias caused by shortcomings of the manufacturer?s calibration procedure the PET to well-counter ratio increased to 0.832?0.064 [0.668-0.941]. After applying compensation for truncation of the upper extremities in the MR-based attenuation maps the ratio further increased to 0.871?0.069 [0.693-0.992]. Conclus
- Published
- 2015
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