Walter Heindel - Academia.edu (original) (raw)

Papers by Walter Heindel

PET-CT Hybrid Imaging, 2010

Scientific Reports

Our aim is to define the capabilities of radiomics and machine learning in predicting pseudoprogr... more Our aim is to define the capabilities of radiomics and machine learning in predicting pseudoprogression development from pre-treatment MR images in a patient cohort diagnosed with high grade gliomas. In this retrospective analysis, we analysed 131 patients with high grade gliomas. Segmentation of the contrast enhancing parts of the tumor before administration of radio-chemotherapy was semi-automatically performed using the 3D Slicer open-source software platform (version 4.10) on T1 post contrast MR images. Imaging data was split into training data, test data and an independent validation sample at random. We extracted a total of 107 radiomic features by hand-delineated regions of interest (ROI). Feature selection and model construction were performed using Generalized Boosted Regression Models (GBM). 131 patients were included, of which 64 patients had a histopathologically proven progressive disease and 67 were diagnosed with mixed or pure pseudoprogression after initial treatment...

Scientific Reports

Oncology Letters, 2018

Truncated tissue factor (tTF)-NGR consists of the extracellular domain of the human TF and the bi... more Truncated tissue factor (tTF)-NGR consists of the extracellular domain of the human TF and the binding motif NGR. tTF-NGR activates blood coagulation within the tumour vasculature following binding to CD13, and is overexpressed in the endothelial cells of tumour vessels, resulting in tumour vessel infarction and subsequent retardation/regression of tumour growth. The aim of the present study was to investigate gadofosveset-based real-time dynamic contrastenhanced magnetic resonance imaging (DCE-MRI) in evaluating the initial therapeutic effects of the anti-vascular tTF-NGR approach. DCE-MRI (3.0 T) was performed in human U87-glioblastoma tumour-bearing nude mice. During a dynamic T1w GE-sequence, a gadolinium-based blood pool contrast agent (gadofosveset) was injected via a tail vein catheter. Following the maximum contrast intensity inside the tumour being obtained, tTF-NGR was injected (controls received NaCl) and the contrast behaviour of the tumour was monitored by ROI analysis. The slope difference of signal intensities between controls and the tTF-NGR group was investigated, as well as the differences between the average area under the curve (AUC) of the two groups. The association between intensity, group (control vs. tTF-NGR group) and time was analysed by fitting a linear mixed model. Following the injection of tTF-NGR, the signal intensity inside the tumours exhibited a statistically significantly stronger average slope decrease compared with the signal intensity of the tumours in the NaCl group. Furthermore, the initial average AUC values of mice treated with tTF-NGR were 5.7% lower than the average AUC of the control animals (P<0.05). Gadofosveset-enhanced MRI enables the visualization of the initial tumour response to anti-vascular treatment in real-time. Considering the clinical application of tTF-NGR, this method may provide a simple alternative parameter for monitoring the tumour response to vascular disrupting agents and certain vascular targeting agents in humans.

BMJ Open, 2018

Digital breast tomosynthesis plus synthesised images versus standard full-field digital mammograp... more Digital breast tomosynthesis plus synthesised images versus standard full-field digital mammography in populationbased screening (TOSYMA): protocol of a randomised controlled trial.

JAMA Neurology, 2019

IMPORTANCE Randomized clinical trials have shown the efficacy of thrombectomy of large intracrani... more IMPORTANCE Randomized clinical trials have shown the efficacy of thrombectomy of large intracranial vessel occlusions in adults; however, any association of therapy with clinical outcomes in children is unknown. OBJECTIVE To evaluate the use of endovascular recanalization in pediatric patients with arterial ischemic stroke. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study, conducted from January 1, 2000, to December 31, 2018, analyzed the databases from 27 stroke centers in Europe and the United States. Included were all pediatric patients (<18 years) with ischemic stroke who underwent endovascular recanalization. Median follow-up time was 16 months. EXPOSURES Endovascular recanalization. MAIN OUTCOMES AND MEASURES The decrease of the Pediatric National Institutes of Health Stroke Scale (PedNIHSS) score from admission to day 7 was the primary outcome (score range: 0 [no deficit] to 34 [maximum deficit]). Secondary clinical outcomes included the modified Rankin scale (mRS) (score range: 0 [no deficit] to 6 [death]) at 6 and 24 months and rate of complications. RESULTS Seventy-three children from 27 participating stroke centers were included. Median age was 11.3 years (interquartile range [IQR], 7.0-15.0); 37 patients (51%) were boys, and 36 patients (49%) were girls. Sixty-three children (86%) received treatment for anterior circulation occlusion and 10 patients (14%) received treatment for posterior circulation occlusion; 16 patients (22%) received concomitant intravenous thrombolysis. Neurologic outcome improved from a median PedNIHSS score of 14.0 (IQR, 9.2-20.0) at admission to 4.0 (IQR, 2.0-7.3) at day 7. Median mRS score was 1.0 (IQR, 0-1.6) at 6 months and 1.0 (IQR, 0-1.0) at 24 months. One patient (1%) developed a postinterventional bleeding complication and 4 patients (5%) developed transient peri-interventional vasospasm. The proportion of symptomatic intracerebral hemorrhage events in the HERMES meta-analysis of trials with adults was 2.79 (95% CI, 0.42-6.66) and in Save ChildS was 1.37 (95% CI, 0.03-7.40). CONCLUSIONS AND RELEVANCE The results of this study suggest that the safety profile of thrombectomy in childhood stroke does not differ from the safety profile in randomized clinical trials for adults; most of the treated children had favorable neurologic outcomes. This study may support clinicians' practice of off-label thrombectomy in childhood stroke in the absence of high-level evidence.

PLOS ONE, 2019

Objective To compare the efficacy and safety as well as associated image quality of catheter-dire... more Objective To compare the efficacy and safety as well as associated image quality of catheter-directed CT angiography (CCTA) with a low dose of iodine contrast agent compared to intravenous CTA in patients undergoing endovascular aortic aneurysm repair (EVAR). Methods Retrospective data analysis of 92 patients undergoing EVAR between January 2009 and December 2017 was performed. Patients were divided in two groups; those receiving CTA (n = 59) after intravenous contrast agent application and those receiving CCTA (n = 33) via an intraarterial catheter placed in the descending aorta. Demographic and cardiovascular risk factors as well as renal function parameters before, immediately after and 6-60 months after EVAR were evaluated. As primary endpoint, changes in serum creatinine levels in the two groups were evaluated. Secondary endpoints encompassed complications associated with intraarterial catheter placement. Objective (signal-to-noise ratios) and subjective image quality (5-point Likert scale) were compared. Results Amount of contrast medium was significantly lower in CCTA compared to i.v. CTA (23 ± 7 ml vs. 119 ± 15 ml, p<0.0001). Patients undergoing catheter-directed CTA had higher baseline creatinine values compared to the group with intravenous iodine application (1.9 ± 0.6 mg/dl vs. 1.3 ± 0.5 mg/dl; p<0.0001). Follow-up serum creatinine levels however did not show significant alterations between the two groups (1.9 ± 0.4 mg/dl vs. 1.3 ± 0.5 mg/dl). No major complications were detected in the CCTA group. Signal-to-noise ratio (SNR) was comparable between i.v. CTA and CCTA (8.5 ± 4.6 vs. 7.7 ± 4.0; p = 0.37) and subjective image similarly revealed no differences with a good interobserver agreement (ICC = 0.647).

Translational psychiatry, 2012

A compelling association has been observed between cardiovascular disease (CVD) and depression, s... more A compelling association has been observed between cardiovascular disease (CVD) and depression, suggesting individuals with depression to be at significantly higher risk for CVD and CVD-related mortality. Systemic immune activation, hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, arterial stiffness and endothelial dysfunction have been frequently implicated in this relationship. Although a differential epidemiological association between CVD and depression subtypes is evident, it has not been determined if this indicates subtype specific biological mechanisms. A comprehensive systematic literature search was conducted using PubMed and PsycINFO databases yielding 147 articles for this review. A complex pattern of systemic immune activation, endothelial dysfunction and HPA axis hyperactivity is suggestive of the biological relationship between CVD and depression subtypes. The findings of this review suggest that diagnostic subtypes rather than a unifying model of depression s...

Einheit in Vielfalt, 2019

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2018

Purpose Assessment of age group-dependent detection rates of invasive breast cancers among partic... more Purpose Assessment of age group-dependent detection rates of invasive breast cancers among participants in mammography screening including the interval, classified into immunohistochemical subtypes indicating the intrinsic tumor aggressiveness. Materials und Methods The target population comprises women aged 50 – 69 years. All invasive breast cancers diagnosed in one screening (sc) unit during the implementation phase 1/2006 – 12/2010 or identified by the cancer registry during the biennial interval (iv) were categorized based on hormonal-receptor status (HR) and Her2-expression (Her2) into the following subtypes: a) HR+ Her2-, b) HR+ Her2 +, c) HR– Her2 + or d) HR– Her2– (triple-negative); Her2 + and triple-negative types were defined as aggressive. The calculated detection rates (DR, ‰) were based on 53 375 sc-examinations and for the interval on 52 887 sc-negative examinations. Results The DRs of all subtypes were higher in screening versus the interval: (a) 4.95 ‰ (n = 264) vs. ...

EJNMMI Research, 2017

Background: While 68 Ga-PSMA PET-MRI might be superior to PET-CT with regard to soft tissue asses... more Background: While 68 Ga-PSMA PET-MRI might be superior to PET-CT with regard to soft tissue assessment in prostate cancer evaluation, it is also known to potentially introduce additional PET image artefacts. Therefore, the impact of PET acquisition duration and attenuation data on artefact occurrence, lesion detectability, and quantification was investigated. To this end, whole-body PET list mode data from 12 patients with prostate cancer were acquired 1 h after injection of 2 MBq/kg [ 68 Ga]HBED-CC-PSMA on a hybrid PET-MRI system. List mode data were further transformed into data sets representing 300, 180, 90, and 30 s acquisition duration per bed position. Standard attenuation and scatter corrections were performed based on MRI-derived attenuation maps, complemented by emission-based attenuation data in areas not covered by MRI. A total of 288 image data sets were reconstructed with varying acquisition durations for emission and attenuation data with and without scatter and prompt gamma correction, and further analysed regarding image quality and diagnostic performance. Results: Decreased PET acquisition durations resulted in a significantly increased incidence of halo artefacts around kidneys and bladder, decreased lesion detectability and lower SUV as well as markedly lower arm attenuation values: Halo artefacts were present in 5 out of 12 cases at 300-s duration, in 6 at 180 s, in 10 at 90 s, and in 11 cases at 30 s. Using attenuation data of the 300 s scans restored artefact occurrence to the original 300-s level. Prompt gamma correction only led to small improvements in terms of artefact occurrence and size. Of the 141 detected lesions in the 300-s images one lesion was not detected at 180 s, 28 at 90 s, and 64 at 30 s. Using the 300-s attenuation map decreased non-detectability of lesions to zero at 180 s, 9 at 90 s, and 52 at 30 s. Attenuation maps at 90 and 30 s demonstrated markedly lower mean arm attenuation values (0.002 cm-1) than those at 300 s (0.084 cm-1), and 180 s (0.062 cm-1). Conclusions: Short acquisition durations of less than 3 minutes per bed position result in unacceptable image artefacts and decreased diagnostic performance in current whole-body 68 Ga-PSMA PET-MRI and should be avoided. Increased image noise and imperfections in generated attenuation maps were identified as a paramount cause for image degradation.

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2016

Background Coronary artery anomalies encompass a clinically and anatomically variable spectrum in... more Background Coronary artery anomalies encompass a clinically and anatomically variable spectrum including physiological variants and pathophysiologically relevant anomalies. The majority of the variants has no hemodynamic relevance and is often detected accidentally. The recognition of the rare and relevant anomalies that cause either relevant shunt volumes leading to myocardial ischemia or ventricular tachyarrhythmias with the risk of sudden cardiac death is of major importance.

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2015

Ziel: Die Abnahme fortgeschrittener Brustkrebsstadien ist der relevanteste Surrogatparameter eine... more Ziel: Die Abnahme fortgeschrittener Brustkrebsstadien ist der relevanteste Surrogatparameter eines Früherkennungsprogramms. Er stellt den letzten Parameter der kausalen Kaskade dar mit einem zu erwartenden Effekt auf die Brustkrebs-spezifische Mortalität. Um die Effektivität des populationsbezogenen Mammografie-Screenings zu bewerten, wurden die 2-Jahresinzidenzraten fortgeschrittener Brustkrebsstadien nach initialer und erster Folgerunden-Teilnahme analysiert. Material und Methoden: Die Studie schließt 19 563 initiale und 18 034 erste Folgeuntersuchungen einer digitalen Screening-Einheit ein (2008-2010). Die Brustkrebsstadien, diagnostiziert im Programm oder im nachfolgenden zweijährigen Intervall (2-Jahresinzidenz), wurden durch das epidemiologische Krebsregister erhoben. Raten aller und kombinierter UICC-Stadien 2, 3 und 4 (fortgeschrittene Stadien) wurden für eine 2-Jahresperiode analysiert. Die Proportionen wurden auf Signifikanz durch den chi-Quadrat-Test getestet (p < 0,001). Ergebnisse: Die 2-Jahresinzidenzrate aller Stadien lag bei Frauen der Folgerunde im Vergleich zur Erstrunde signifikant niedriger (0,85 vs. 1,29 pro 100 Frauen (%); p < 0,0001). Im Folgerunden-Screening wurde eine signifikant niedrigere 2-Jahresinzidenz fortgeschrittener Stadien im Vergleich zum Erstrunden-Screening beobachtet (0,26 % vs. 0,48 %; p = 0,0007); bei Frauen von 50 bis 59 Jahren war der Inzidenzunterschied geringer (0,21 % vs. 0,35 %; p = 0,07) als bei Frauen von 60 bis 69 Jahren (0,31 % vs. 0,70 %; p = 0,0008). Schlussfolgerung: Im Übergang von der Prävalenzzur Inzidenzphase des Mammografie-Screenings ist eine Programmwirksamkeit anhand einer niedrigeren 2-Jahresinzidenz fortgeschrittener Brustkrebserkrankungen unter Folgerunden-im Vergleich zu Erstrunden-Teilnehmerinnen, insbesondere zwischen 60 und 69 Jahren, zu verzeichnen.

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2015

To prove the tissue-protecting effect of mechanical recanalization, we assessed the CT perfusion-... more To prove the tissue-protecting effect of mechanical recanalization, we assessed the CT perfusion-based tissue outcome ("TO") and correlated this imaging parameter with the 3-month clinical outcome ("CO"). Materials and Methods: 159 patients with large intracranial artery occlusions revealing mechanical recanalization were investigated by CCT, CT angiography (CTA) and CT perfusion (CTP) upon admission. For the final infarct volume, native CCT was repeated after 24 h. The "TO" ("percentage mismatch loss" = %ML) was defined as the difference between initial penumbral tissue on CTP and final infarct volume on follow-up CCT. We monitored the three-month modified Rankin Scale (mRS), age, bleeding occurrence, time to recanalization, TICI score and collateralization grade, infarct growth and final infarct volume. Spearman's correlation and nominal regression analysis were used to evaluate the impact of these parameters on mRS. Results: Significant correlations were found for % ML and mRS (c = 0.48, p < 0.001), for final infarct volume and mRS (c = 0.52, p < 0.001), for TICI score and mRS (c =-0.35, p < 0.001), for initial infarct core and mRS (c = 0.14, p = 0.039) as well as for age and mRS (c = 0.37, p < 0.001). According to the regression analysis, %ML predicted the classification of mRS correctly in 38.5 % of cases. The subclasses mRS 1 and 6 could be predicted by % ML with 86.4 % and 60.9 % reliability, respectively. No correlations were found for time to recanalization and mRS, for collateralization grade and mRS, and for post-interventional bleeding and mRS. Conclusion: Better than the TICI score, CT-based TO predicts the clinical success of mechanical recanalization, showing that not recanalization, but reperfusion should be regarded as a surrogate parameter for stroke therapy. This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

Translational psychiatry, 2012

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2014

Ziel: Multizentrischer Vergleich von manuellen ein-/bi-dimensionalen Messungen und semi-automatis... more Ziel: Multizentrischer Vergleich von manuellen ein-/bi-dimensionalen Messungen und semi-automatischen ein-/bi-dimensionalen und volumetrischen Messungen zur Beurteilung des Therapieansprechens beim Malignen Lymphopm in CT-Verlaufskontrollen. Material und Methoden: MSCT-Datensätze von Patienten mit Malignem Lymphom wurden vor (baseline) und nach zwei Zyklen Chemotherapie (follow-up) in fünf Universitätsradiologien ausgewertet. Der Langachsen-(LAD), der Kurzachsendurchmesser (SAD) und die bi-dimensionale WHO-Fläche von 307 Target-Lymphknoten wurden manuell und semi-automatisch unter Verwendung einer dedizierten Software bestimmt. Die Lymphknotenvolumetrie wurde lediglich semiautomatisch bestimmt. Das Therapieansprechen wurde anhand Lymphom-adaptierter RECIST-Kriterien beurteilt. Ergebnisse: Auf der Basis des einzelnen Lymphknotens wiesen semi-automatisch bestimmte mehrdimensionale Parameter einen höheren Anteil in der korrekten Beurteilung des Therapieansprechens als die die manuell oder semi-automatisch bestimmten eindimensionalen Parameter auf. Fehlklassifikationen wurden um bis 9,6 % reduziert. Zusätzlich war im Vergleich zu den manuellen Messungen der Einfluss auf die Beurteilung des Therapieansprechens in den einzelnen Studienzentren bei Anwendung semi-automatischer Messungen geringer. Schlussfolgerung: Die semi-automatische Volumetrie und die bi-dimensionale WHO-Messung reduzieren die Anzahl von Fehlklassifikationen in der Beurteilung des Therapieansprechens bei Patienten mit Malignem Lymphom signifikant um 9,6 % in einem Multicenterumfeld im Vergleich zu linearen Parametern. Semi-automatische Software-Tools können dazu beitragen, Fehlklassifikationen manueller Messungen zu reduzieren

Radiology, 2010

Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies... more Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.

American Journal of Roentgenology, 2002

OBJECTIVE. The purpose of our study was to assess the safety and dialysability of gadobutrol, a n... more OBJECTIVE. The purpose of our study was to assess the safety and dialysability of gadobutrol, a new, electrically neutral, and highly concentrated MR contrast agent, in patients who require hemodialysis. SUBJECTS AND METHODS. Eleven patients with end-stage renal failure who required ongoing hemodialysis were enrolled in our prospective study. Gadobutrol (1 mol/L) was injected IV at randomly assigned doses of either 0.1 or 0.3 mmol of gadolinium per kilogram of body weight for contrast-enhanced MR imaging. Hematology, clinical chemistry, and vital signs were closely monitored at baseline and during an observation period of 120 hr after the IV injection of gadobutrol. To calculate the dialysability, blood samples were drawn before and after each of three hemodialysis sessions. Additional arterial and venous blood sampling was performed during the first hemodialysis session after 30 and 90 min. RESULTS. No gadobutrol-related changes in hematology, clinical chemistry, or vital signs were detected at either dose level during the observation period. The mean and the standard deviation for the eliminated fraction of gadobutrol was 68.2% ± 12.7% after a 3-hr hemodialysis session using a 1.2 m 2 low-flux polysulfone membrane. After three consecutive hemodialysis sessions, the total amount of gadobutrol eliminated increased to 98.0% ± 1.8%. The mean clearance rates of gadobutrol were 126.1 ± 17.8 mL/min and 126.6 ± 24.5 mL/min at 30 and 90 min, respectively. CONCLUSION. Gadobutrol is effectively removed by three hemodialysis sessions using a low-flux polysulfone membrane. Our study documents initial evidence that gadobutrol can be used safely in hemodialysis patients.

PET-CT Hybrid Imaging, 2010

Scientific Reports

Oncology Letters, 2018

BMJ Open, 2018

JAMA Neurology, 2019

PLOS ONE, 2019

Translational psychiatry, 2012

Einheit in Vielfalt, 2019

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2018

EJNMMI Research, 2017

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2016

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2015

Translational psychiatry, 2012

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2014

Radiology, 2010

American Journal of Roentgenology, 2002