Publications by authors named "Philipp Schindler"

35 Publications

Intraosseous contrast administration for emergency stroke CT.

Neuroradiology 2021 Jan 18. Epub 2021 Jan 18.

Clinic for Radiology, University Hospital Muenster, Muenster, Germany.

Computed tomography (CT) imaging in acute stroke is an established and fairly widespread approach, but there is no data on applicability of intraosseous (IO) contrast administration in the case of failed intravenous (IV) cannula placement. Here, we present the first case of IO contrast administration for CT imaging in suspected acute stroke providing a dedicated CT examination protocol and analysis of achieved image quality as well as a review of available literature.
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http://dx.doi.org/10.1007/s00234-021-02642-wDOI Listing
January 2021

Entangling logical qubits with lattice surgery.

Nature 2021 01 13;589(7841):220-224. Epub 2021 Jan 13.

Institute for Experimental Physics, University of Innsbruck, Innsbruck, Austria.

The development of quantum computing architectures from early designs and current noisy devices to fully fledged quantum computers hinges on achieving fault tolerance using quantum error correction. However, these correction capabilities come with an overhead for performing the necessary fault-tolerant logical operations on logical qubits (qubits that are encoded in ensembles of physical qubits and protected by error-correction codes). One of the most resource-efficient ways to implement logical operations is lattice surgery, where groups of physical qubits, arranged on lattices, can be merged and split to realize entangling gates and teleport logical information. Here we report the experimental realization of lattice surgery between two qubits protected via a topological error-correction code in a ten-qubit ion-trap quantum information processor. In this system, we can carry out the necessary quantum non-demolition measurements through a series of local and entangling gates, as well as measurements on auxiliary qubits. In particular, we demonstrate entanglement between two logical qubits and we implement logical state teleportation between them. The demonstration of these operations-fundamental building blocks for quantum computation-through lattice surgery represents a step towards the efficient realization of fault-tolerant quantum computation.
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http://dx.doi.org/10.1038/s41586-020-03079-6DOI Listing
January 2021

Portal and hepatic vein embolization prior to major hepatectomy.

Z Gastroenterol 2021 Jan 11;59(1):35-42. Epub 2021 Jan 11.

Department for General, Visceral and Transplantation Surgery, University Hospital Muenster, Muenster, Germany.

Purpose:  To analyze safety and effectiveness of simultaneous portal and hepatic vein embolization (PHVE) or sequential hepatic vein embolization (HVE) compared to portal vein embolization (PVE) for future remnant liver (FRL) hypertrophy prior to major hepatic surgery.

Methods:  Patients undergoing PVE, PHVE or HVE at our tertiary care center between 2018 and 2020 were retrospectively included. FRLV, standardized FRLV (sFRLV) and sFRLV growth rate per day were assessed via volumetry, as well as laboratory parameters.

Results:  36 patients (f = 15, m = 21; median 64.5 y) were included, 16 patients received PHVE and 20 patients PVE, of which 4 received sequential HVE. Significant increase of FRLV was achieved with both PVE and PHVE compared to baseline (p < 0.0001). sFRLV growth rate did not significantly differ following PHVE (2.2 ± 1.2 %/d) or PVE (2.2 ± 1.7 %/d, p = 0.94). Left portal vein thrombosis (LPVT) was observed after PHVE in 6 patients and in 1 patient after PVE. Sequential HVE showed a considerably high growth rate of 1.42 ± 0.45 %/d after PVE.

Conclusion:  PHVE effectively induces FRL hypertrophy but yields comparable sFRLV to PVE. Sequential HVE further induces hypertrophy after insufficient growth due to PVE. Considering a potentially higher rate of LPVT after PHVE, PVE might be preferred in patients with moderate baseline sFRLV, with optional sequential HVE in non-sufficient responders.
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http://dx.doi.org/10.1055/a-1330-9450DOI Listing
January 2021

Evaluation of impact of elective invasive examinations in patients with transjugular intrahepatic portosystemic shunt in the long-term follow up.

Z Gastroenterol 2021 Jan 11;59(1):24-34. Epub 2021 Jan 11.

Medical Clinic B, Department of Gastroenterology, Hepatology, Endocrinology, Clinical Infectiology, University Hospital Muenster, Muenster, Germany.

Introduction:  In the management of patients with decompensated liver cirrhosis, transjugular intrahepatic portosystemic shunt (TIPS) insertion is well-established but common recommendations in the follow up management are inconsistent. Doppler sonography is commonly used for detection for TIPS dysfunction whilst data on the impact of elective invasive examinations are scarce.

Aim:  The aim of this retrospective analysis is to evaluate potential benefits of elective invasive examinations in the follow up management of patients after TIPS insertion METHODS:  Data of all patients receiving TIPS at the university hospitals of Muenster and Bonn between 2013 and 2018 (n = 534) were collected. The impact of performance of elective invasive examinations at 12 months after TIPS insertion on the occurrence of liver related events (LREs) and frequency of TIPS revisions within 24 months after TIPS insertion was analyzed.

Results:  No significant differences were found concerning occurrence of liver related events after 24 months depending on whether an elective invasive examination was performed. Occurrence of hepatic encephalopathy, relapse of initial indication for TIPS, as well as death or liver transplantation all did not differ. These findings were verified by a subgroup analysis including only patients who did not experience a LRE or TIPS revision within the first 12 months after TIPS procedure.

Conclusion:  The analyzed data suggest no evidence for a beneficial impact due to implementation of an elective invasive examination program after TIPS insertion. Invasive examinations should remain reserved to patients with suspected TIPS dysfunction.
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http://dx.doi.org/10.1055/a-1330-9867DOI Listing
January 2021

Shunt-Induced Hepatic Encephalopathy in TIPS: Current Approaches and Clinical Challenges.

J Clin Med 2020 Nov 23;9(11). Epub 2020 Nov 23.

Institute of Clinical Radiology, University Hospital Muenster, D-48149 Muenster, Germany.

Transjugular intrahepatic portosystemic shunt (TIPS) is an established treatment tool in decompensated liver cirrhosis that has been shown to prolong transplant-free survival. Hepatic encephalopathy (HE) is a frequent complication of decompensated cirrhosis, eventually induced and/or aggravated by TIPS, that remains a clinical challenge especially in these patients. Therefore, patient selection for TIPS requires careful assessment of risk factors for HE. TIPS procedural parameters regarding stent size and invasive portosystemic pressure gradient measurements thereby have an important role. Endovascular shunt modification, in combination with a conservative medical approach, often results in a significant reduction of symptoms. This review summarizes HE molecular mechanisms and pathophysiology as well as diagnostic and therapeutic approaches targeting shunt-induced HE.
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http://dx.doi.org/10.3390/jcm9113784DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7700586PMC
November 2020

Analysis of failed therapy evaluations in radioembolization of primary and secondary liver cancers.

J Cancer Res Clin Oncol 2021 May 6;147(5):1537-1545. Epub 2020 Nov 6.

Institute of Clinical Radiology, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149, Munster, Germany.

Purpose: To analyze patients' characteristics and reasons for not performing planned transarterial radioembolization (TARE) in liver cancer after Tc-labeled macroaggregated albumin (Tc-MAA) evaluation.

Methods: In this retrospective single-center cohort, all patients undergoing Tc-MAA evaluation prior to planned TARE for primary or secondary liver cancer between 2009 and 2018 were analyzed. Patients were assigned to either "TARE" or "no TARE" group. Patients' characteristics, arising reasons for not performing the planned TARE treatment as well as predictive factors for occurrence of these causes were analyzed.

Results: 436 patients [male = 248, female = 188, median age 62 (23-88) years] with Tc-MAA evaluation prior to planned TARE of primary or secondary liver cancer were included in this study. 148 patients (33.9%) did not receive planned TARE. Patients with a hepatic tumor burden > 50%, no liver cirrhosis, no previous therapies and a higher bilirubin were significantly more frequent in "no TARE" compared to "TARE" group. Main reasons for not performing TARE were extrahepatic tracer accumulation (n = 70, 40.5%), non-target accumulation of Tc-MAA (n = 27, 15.6%) or a hepatopulmonary shunt fraction of more than 20% (n = 23, 13.3%). Independent preprocedural parameters for not performing planned TARE were elevated bilirubin (p = 0.021) and creatinine (p = 0.018) and lower MELD score (p = 0.031).

Conclusion: A substantial number of patients are precluded from TARE following Tc-MAA evaluation, which is, therefore, implicitly needed to determine contraindications to TARE and should not be refrained from in pretreatment process. However, a preceding careful patient selection is needed especially in patients with high hepatic tumor burden and alteration in lab parameters.
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http://dx.doi.org/10.1007/s00432-020-03443-zDOI Listing
May 2021

Repeated radioembolization in advanced liver cancer.

Ann Transl Med 2020 Sep;8(17):1055

Institute of Clinical Radiology, University Hospital Muenster, Muenster, Germany.

Background: To evaluate safety and clinical outcome of repeated transarterial Y (yttrium) radioembolization (TARE) in primary and metastatic liver cancer.

Methods: Between 2009 and 2018, n=288 patients underwent TARE for treatment of malignant liver disease in a tertiary care hospital. This retrospective single center study analyzed the safety and outcome of patients (n=11/288) undergoing repeated resin microsphere TARE. Included patients suffered from hepatocellular carcinoma (n=3), colorectal cancer (n=2), breast cancer (n=2), intrahepatic cholangiocarcinoma (n=3), and neuroendocrine carcinoma (n=1). All patients had shown either partial response (n=9) or stable disease (n=2) after first TARE. Lab parameters, response assessed by the Response Evaluation Criteria in Solid Tumors (mRECIST/RECIST) at 3 months and overall survival was analyzed. Additionally, patients with repeated TARE were compared to a matched control group (n=56) with single TARE therapy. Kaplan Meier analysis was performed to analyze survival.

Results: Patients after repeated TARE showed similar increase in lab parameters as compared to their first TARE. No case of radioembolization induced liver disease was observed. While n=5/11 patients showed a partial response and n=4/11 patients a stable disease after repeated TARE, only n=2/11 patients suffered from progressive disease. Median overall survival was 20.9±11.9 months for the repeated TARE group while it was 5.9±16.2 months for the control group.

Conclusions: Repeated Y TARE is safe and can be of benefit for patients yielding a comparable degree of local disease control compared to patients with singular TARE.
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http://dx.doi.org/10.21037/atm-20-2658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575953PMC
September 2020

EFFICACY OF 90Y-RADIOEMBOLIZATION IN METASTATIC COLORECTAL CANCER DEPENDING ON THE PRIMARY TUMOR SIDE.

Dig Dis 2020 Nov 3. Epub 2020 Nov 3.

Metastatic colorectal cancer (mCRC) is associated with different molecular biology, clinical characteristics and outcome depending on the primary tumor localization. We aimed to evaluate the effectiveness of 90Y-radioembolization (RE) for therapy of colorectal liver metastases depending on the primary tumor side. We performed a retrospective analysis of n=73 patients with mCRC and RE in our university liver center between 2009 and 2018. Patients were stratified according to the primary tumor side (left vs. right hemicolon), treatment response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST) at follow-up after 3 months. Kaplan-Meier analysis was performed to analyze survival followed by Cox regression to determine independent prognostic factors for survival. Prior to RE all patients had received systemic therapy, with either stable or progressive disease, but no partial or complete response. In n=22/73 (30.1%) patients the primary tumor side was in the right colon, in n=51/73 (69.9%) patients in the left colon. Hepatic tumor burden was ≤25% in n=36/73 (49.3%) patients and >25% in n=37/73 (50.7%) patients. At 3 months, n=21 (33.8%) patients showed treatment response [n=2 (3.2%) complete response, n=19 (30.6%) partial response], n=13 (21.0%) stable disease, and n=28 (45.2%) progressive disease after RE. The median survival in case of primary tumor side in the left colon was significantly higher than for primary tumors in the right colon (8.7 vs. 6.0 months, p=0.033). The median survival for a hepatic tumor burden ≤25% was significantly higher compared with >25% (13.9 vs. 4.3 months, p<0.001). The median overall survival was 6.1 months. The median survival after RE in hepatic-metastatic CRC depends on the primary tumor side and the pre-procedural hepatic tumor burden.
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http://dx.doi.org/10.1159/000512744DOI Listing
November 2020

Value Improvement by Assessing IR Care via Time-Driven Activity-Based Costing.

J Vasc Interv Radiol 2021 02 31;32(2):262-269. Epub 2020 Oct 31.

Institute of Clinical Radiology, University Hospital Muenster, Muenster, Germany; Klinik und Poliklinik für Radiologie, Klinikum der Universität München, Munich, Germany.

Purpose: To evaluate time-driven activity-based costing (TDABC) in interventional radiology for image-guided vascular malformation treatment as an example.

Materials And Methods: Retrospective analysis was performed on consecutive vascular malformation treatment cycles [67 venous malformations (VMs) and 11 arteriovenous malformations (AVMs)] in a university hospital in 2018. All activities were integrated with a process map, and spent resources were assigned accordingly. TDABC uses 2 parameters: (i) practical capacity cost rate, calculated as 80% of theoretical capacity, and (ii) time consumption of each resource determined by interviews (23 items). Thereby, the total costs were calculated. Treatment cycles were modified according to identified resource waste and TDABC-guided negotiations with health insurance.

Results: Total personnel time required was higher for AVM (1,191 min) than for VM (637 min) treatment. The interventional procedure comprised the major part (46%) of personnel time required in AVM, whereas it comprised 19% in VM treatment. Materials represented the major cost type in AVM (75%) and VM (45%) treatments. TDABC-based treatment process modification led to a decrease in personnel time need of 16% and 30% and a cost reduction of 5.5% and 15.7% for AVM and VM treatments, respectively. TDABC-guided cost reduction and TDABC-informed negotiations improved profit from -56% to +40% and from +41% to +69% for AVM and VM treatments, respectively.

Conclusions: TDABC facilitated the precise costing of interventional radiologic treatment cycles and optimized internal processes, cost reduction, and revenues. Hence, TDABC is a promising tool to determine the denominator of interventional radiology's value.
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http://dx.doi.org/10.1016/j.jvir.2020.09.017DOI Listing
February 2021

CT-Guided Percutaneous Drainage of Pneumoperitoneum Presenting as Acute Abdomen.

J Vasc Interv Radiol 2021 02 28;32(2):271-276. Epub 2020 Oct 28.

Institute of Clinical Radiology, University Hospital Muenster, Muenster, Germany.

Purpose: To evaluate the feasibility and effectiveness of computed tomography (CT)-guided percutaneous drainage (PD) in patients with iatrogenic pneumoperitoneum presenting as acute abdomen.

Materials And Methods: In this retrospective, single-center cohort study, 16 consecutive patients (9 males, 7 females; median age, 67.5 [51-85] years) undergoing PD for managing acute abdomen caused by iatrogenic pneumoperitoneum between 2013 and 2019 were analyzed. Inclusion criteria were clinical signs of acute abdomen that was unresponsive to conservative management and pneumoperitoneum due to an iatrogenic cause after PD, observed using CT imaging. Volumetry of pneumoperitoneum was performed using computer-aided image segmentation. To evaluate the clinical outcome, the paired t-test was performed to analyze the course of pain intensity on the numerical pain rating scale (NPRS, 0-10). Patient records were reviewed to determine PD-related adverse events and median drain duration.

Results: The median pneumoperitoneum volume was 891.1 (127.7-3,677.0) mL. All PD procedures were successfully performed, with symptom relief and immediate abdominal decompression (mean segmental volume reduction, 79.8% ± 13.5). Acute abdomen symptoms were resolved, with significant improvement in pain intensity between the day of the PD procedure and the first day after the procdure (mean NPRS scores, 3.3 ± 1.9 vs 0.8 ± 1.0; P < .001). The median drain duration was 2 (1-3) days. No PD-associated adverse events were observed. After PD, 14 patients required only conservative management, whereas 2 patients with anastomotic leakage required additional surgery as they showed signs of persisting sepsis and generalized peritonitis.

Conclusions: PD is a safe and suitable procedure for the management of symptoms in patients with iatrogenic pneumoperitoneum presenting as acute abdomen.
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http://dx.doi.org/10.1016/j.jvir.2020.09.018DOI Listing
February 2021

Experimental deterministic correction of qubit loss.

Nature 2020 09 9;585(7824):207-210. Epub 2020 Sep 9.

Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria.

The successful operation of quantum computers relies on protecting qubits from decoherence and noise, which-if uncorrected-will lead to erroneous results. Because these errors accumulate during an algorithm, correcting them is a key requirement for large-scale and fault-tolerant quantum information processors. Besides computational errors, which can be addressed by quantum error correction, the carrier of the information can also be completely lost or the information can leak out of the computational space. It is expected that such loss errors will occur at rates that are comparable to those of computational errors. Here we experimentally implement a full cycle of qubit loss detection and correction on a minimal instance of a topological surface code in a trapped-ion quantum processor. The key technique used for this correction is a quantum non-demolition measurement performed via an ancillary qubit, which acts as a minimally invasive probe that detects absent qubits while imparting the smallest quantum mechanically possible disturbance to the remaining qubits. Upon detecting qubit loss, a recovery procedure is triggered in real time that maps the logical information onto a new encoding on the remaining qubits. Although the current demonstration is performed in a trapped-ion quantum processor, the protocol is applicable to other quantum computing architectures and error correcting codes, including leading two- and three-dimensional topological codes. These deterministic methods provide a complete toolbox for the correction of qubit loss that, together with techniques that mitigate computational errors, constitute the building blocks of complete and scalable quantum error correction.
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http://dx.doi.org/10.1038/s41586-020-2667-0DOI Listing
September 2020

Surgical management of submacular hemorrhage due to n-AMD: a comparison of three surgical methods.

Int J Retina Vitreous 2020 2;6:27. Epub 2020 Jul 2.

Department of Ophthalmology, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.

Background: To compare and assess the efficacy of three surgical methods for the treatment of acute submacular hemorrhage (ASH): pneumatic displacement with C2F6, in combination with intravitreal injection of bevacizumab and rtPA, pars plana vitrectomy (PPV) with intravitreal injection of gas (C2F6), bevacizumab and subretinal injection of recombinant tissue plasminogen activator (rtPA), pars plana vitrectomy (PPV) with intravitreal injection of gas (C2F6), bevacizumab and intravitreal injection of recombinant tissue plasminogen activator (rtPA).

Methods: The study included 85 patients with ASH. In the group without PPV (A), patients were treated with intravitreal injection of C2F6, bevacizumab and rtPA. In the second and third group, patients underwent a PPV, intravitreal injection of bevacizumab, pneumatic displacement with C2F6 and a subretinal (B) or intravitreal (C) injection of recombinant tissue plasminogen activator (rt PA).

Results: In group A, mean BCVA increased from preop logMAR 1.41 to 1.05, in group B from 1.46 to 1.28 and in group C from 1.63 to 1.33. In group A, CFT changed from 764 ± 340 μm at time point 0 to 246 ± 153 μm at time point 1, in group B from 987 ± 441 μm to 294 ± 166 μm and in group C from 642 ± 322 μm to 418 ± 364 μm. Patients had an average of 5 injections after surgery.

Conclusion: Our study demonstrates that the three methods are equally effective in improving the morphology and the BCVA of patients with ASH.
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http://dx.doi.org/10.1186/s40942-020-00228-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7331168PMC
July 2020

TIPS Modification in the Management of Shunt-Induced Hepatic Encephalopathy: Analysis of Predictive Factors and Outcome with Shunt Modification.

J Clin Med 2020 Feb 19;9(2). Epub 2020 Feb 19.

Institute of Clinical Radiology, University Hospital Muenster, D-48149 Muenster, Germany.

Purpose: To evaluate predictive parameters for the development of Hepatic Encephalopathy (HE) after Transjugular Intrahepatic Portosystemic Shunt (TIPS) placement and for success of shunt modification in the management of shunt-induced HE.

Methods: A retrospective analysis of all patients with TIPS ( = 344) has been performed since 2011 in our university liver center. = 45 patients with HE after TIPS were compared to = 48 patients without HE after TIPS (case-control-matching). Of = 45 patients with TIPS-induced HE, = 20 patients received a reduction stent ( = 18) or TIPS occlusion ( = 2) and were differentiated into responders (improvement by at least one HE grade according to the West Haven classification) and non-responders (no improvement).

Results: Older patient age, increased serum creatinine and elevated International Normalized Ratio (INR) immediately after TIPS placement were independent predictors for the development of HE. In 11/20 patients (responders, 55%) undergoing shunt modification, the HE grade was improved compared with nine non-responders (45%), with no relevant recurrence of refractory ascites or variceal bleeding. A high HE grade after TIPS insertion was the only positive predictor of treatment response ( = 0.019). A total of 10/11 responders (91%) survived the 6 months follow-up after modification but only 6/9 non-responders (67%) survived.

Discussion: Older patient age as well as an increased serum creatinine and INR after TIPS are potential predictors for the development of HE. TIPS reduction for the treatment of TIPS-induced HE is safe, with particular benefit for patients with pronounced HE.
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http://dx.doi.org/10.3390/jcm9020567DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7073830PMC
February 2020

Characterizing large-scale quantum computers via cycle benchmarking.

Nat Commun 2019 11 25;10(1):5347. Epub 2019 Nov 25.

Institute for Experimental Physics, University of Innsbruck, 6020, Innsbruck, Austria.

Quantum computers promise to solve certain problems more efficiently than their digital counterparts. A major challenge towards practically useful quantum computing is characterizing and reducing the various errors that accumulate during an algorithm running on large-scale processors. Current characterization techniques are unable to adequately account for the exponentially large set of potential errors, including cross-talk and other correlated noise sources. Here we develop cycle benchmarking, a rigorous and practically scalable protocol for characterizing local and global errors across multi-qubit quantum processors. We experimentally demonstrate its practicality by quantifying such errors in non-entangling and entangling operations on an ion-trap quantum computer with up to 10 qubits, and total process fidelities for multi-qubit entangling gates ranging from [Formula: see text] for 2 qubits to [Formula: see text] for 10 qubits. Furthermore, cycle benchmarking data validates that the error rate per single-qubit gate and per two-qubit coupling does not increase with increasing system size.
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http://dx.doi.org/10.1038/s41467-019-13068-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6877623PMC
November 2019

Cardiac CT in the Preoperative Diagnostics of Neonates with Congenital Heart Disease: Radiation Dose Optimization by Omitting Test Bolus or Bolus Tracking.

Acad Radiol 2020 05 20;27(5):e102-e108. Epub 2019 Aug 20.

Institute of Clinical Radiology, University Hospital Muenster, Albert-Schweitzer-Campus 1, D-48149 Muenster, Germany.

Rationale And Objectives: Congenital heart diseases (CHD) belong to the leading causes of infant mortality worldwide. Prognostic improvements result from multimodal therapy strategies leading to an increased demand for noninvasive imaging. The aim of the study was to further optimize cardiac CT radiation dose by omitting the test bolus or bolus tracking scan, which can have a relevant share of radiation exposure, especially in neonates.

Materials And Methods: This retrospective study included 25 neonates with CHD who received a CT angiography (CTA) from 2009 to 2018. The examinations were performed as a high-pitch CTA (pitch 3.4, 80 kV) with manual contrast administration (1.5 ml/kg body weight) and fixed scan delay depending on the respective heart defect. Diagnosis, adverse events, radiation dose parameters, objective (contrast-to-noise ratio) and subjective (4-point Likert scale) image quality as well as diagnostic accuracy compared to intraoperative findings was assessed.

Results: All examinations were diagnostically evaluable without adverse events. The median CT dose index volume (CTDI) was 0.50 mGy (range, 0.15-0.94), the median dose-length product was 8 mGy × cm (range, 3-17). The estimation of the effective dose by Monte Carlo simulation revealed lower median dose levels 0.66 mSv (range, 0.25-1.40 mSv) than previously published in comparable groups. All examinations achieved a very good mean image quality score of 1.2 ± 0.4 with only minimal image noise and mean contrast-to-noise ratio of 16.1 ± 7.0. Diagnostic accuracy was 100 % as cardiac anatomy revealed no new diagnoses or significant differences in the subsequent cardiac surgery.

Conclusion: Cardiac high-pitch CTA of neonates with CHD can be performed safely and dose-reducing without additional test bolus or bolus tracking scan. With very good image quality, it provides a detailed insight into the cardiac anatomy and thus enables a differentiated, noninvasive therapy planning.
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http://dx.doi.org/10.1016/j.acra.2019.07.019DOI Listing
May 2020

Intraosseous contrast administration for emergency computed tomography: A case-control study.

PLoS One 2019 31;14(5):e0217629. Epub 2019 May 31.

Institute of Clinical Radiology, University Hospital Muenster, Muenster, Germany.

Objective: The aim of the study was to evaluate the feasibility of intraosseous (i.o.) contrast media injection (CMI) for emergency computed tomography (CT) of severe trauma and the associated image quality compared to intravenous (i.v.) CMI.

Materials And Methods: The authors retrospectively analysed objective (contrast-to-noise ratio (CNR)) and subjective (4-point Likert scale) image quality of CTs after i.o. (n = 4, mean age (y) 57.0±11.0) versus i.v. (n = 20, mean age (y) 58.8±4.4) CMI. All patients underwent a native head CT scan, a cerebral CT angiography (CTA) and CTA of the supra-aortic vasculature as well as a chest and abdominal CT scan in the venous phase; one patient with an i.o. access additionally received a CTA of the lower limbs. Electronic patient records have been reviewed to determine i.o. access related complications.

Results: Both groups were consistent in age, heart rate, scan parameters including the flow rate of the contrast agent, resulting in comparable radiation dose levels. The image noise and CNR had no significant difference between the two groups. Scoring the delineation of the main vessels after i.o. CMI showed no significant difference to the i.v. group. There were no CT or i.o. access related complications observed.

Conclusion: The i.o. access is a safe and suitable alternative for emergency CMI in CT. Using established protocols good to very good image quality can be achieved, comparable to i.v. CMI. We show for the first time, that i.o. CMI is also feasible for CTA imaging of the head and neck region as well as of pelvic and leg vessels.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217629PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6544258PMC
January 2020

Expression of microRNAs in the ascites of patients with peritoneal carcinomatosis and peritonitis.

Cancer Cytopathol 2018 05 23;126(5):353-363. Epub 2018 Jan 23.

Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Germany.

Background: Peritoneal carcinomatosis (PCA) has a prognostic role in patients with gastrointestinal cancers. The differential diagnosis may be challenging due to the low sensitivity of cytology. Although microRNAs (miRNAs) have been a focus of various specimens and diseases, to the best of the authors' knowledge only limited knowledge exists regarding ascites. Herein, the authors systematically evaluated preanalytical factors and the potential of miRNAs as biomarkers of ascites.

Methods: The authors prospectively analyzed samples from patients with PCA, spontaneous bacterial peritonitis (SBP), and portal hypertension (no SBP/PCA). Various preanalytical factors such as extraction kits, sample storage, stability, and processing were systematically evaluated. MiRNA expression profiling using TaqMan Low Density Array and quantitative reverse transcriptase-polymerase chain reaction were used to evaluate miRNA expression.

Results: All selected miRNAs were found to be reliably detectable in ascites samples. Ascites miRNAs were well preserved from degradation with required short-term and long-term stability. MiRNA expression profiling in patients with PCA compared with those with no SBP/PCA revealed miR-21, miR-186, miR-222, and miR-483-5p to be upregulated and miR-26b to be downregulated. MiRNA expression validation analysis confirmed higher expression levels of miR-21 and miR-186 in patients with PCA compared with those with no SBP/PCA, whereas miR-223 was significantly upregulated in patients with SBP. A simple proportion score between miR-21 and miR-223 allowed the authors to discriminate between the patients with PCA and those with SBP with an area under the curve of 0.982 (95% confidence interval, 0.943-1.022).

Conclusions: The data from the current study provide novel evidence of the differential expression of miRNAs in ascites from patients with PCA and SBP, which may offer an additional miRNA-based molecular approach for the differential diagnosis of PCA. Cancer Cytopathol 2018;126:353-63. © 2018 American Cancer Society.
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http://dx.doi.org/10.1002/cncy.21966DOI Listing
May 2018

An experimental approach aiming the production of a gas mixture composed of hydrogen and methane from biomass as natural gas substitute in industrial applications.

Bioresour Technol 2017 Aug 11;237:39-46. Epub 2017 Mar 11.

TU Wien, Institute of Chemical, Environmental and Biological Engineering, Getreidemarkt 9, 1060 Wien, Austria.

This work presents an experimental approach aiming the production of a gas mixture composed of H and CH, which should serve as natural gas substitute in industrial applications. Therefore, a lab-scale process chain employing a water gas shift unit, scrubbing units, and a pressure swing adsorption unit was operated with tar-rich product gas extracted from a commercial dual fluidized bed biomass steam gasification plant. A gas mixture with a volumetric fraction of about 80% H and 19% CH and with minor fractions of CO and CO was produced by employing carbon molecular sieve as adsorbent. Moreover, the produced gas mixture had a lower heating value of about 15.5MJ·m and a lower Wobbe index of about 43.4MJ·m, which is similar to the typical Wobbe index of natural gas.
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http://dx.doi.org/10.1016/j.biortech.2017.03.040DOI Listing
August 2017

Real-time dynamics of lattice gauge theories with a few-qubit quantum computer.

Nature 2016 06;534(7608):516-9

Institute for Experimental Physics, University of Innsbruck, 6020 Innsbruck, Austria.

Gauge theories are fundamental to our understanding of interactions between the elementary constituents of matter as mediated by gauge bosons. However, computing the real-time dynamics in gauge theories is a notorious challenge for classical computational methods. This has recently stimulated theoretical effort, using Feynman's idea of a quantum simulator, to devise schemes for simulating such theories on engineered quantum-mechanical devices, with the difficulty that gauge invariance and the associated local conservation laws (Gauss laws) need to be implemented. Here we report the experimental demonstration of a digital quantum simulation of a lattice gauge theory, by realizing (1 + 1)-dimensional quantum electrodynamics (the Schwinger model) on a few-qubit trapped-ion quantum computer. We are interested in the real-time evolution of the Schwinger mechanism, describing the instability of the bare vacuum due to quantum fluctuations, which manifests itself in the spontaneous creation of electron-positron pairs. To make efficient use of our quantum resources, we map the original problem to a spin model by eliminating the gauge fields in favour of exotic long-range interactions, which can be directly and efficiently implemented on an ion trap architecture. We explore the Schwinger mechanism of particle-antiparticle generation by monitoring the mass production and the vacuum persistence amplitude. Moreover, we track the real-time evolution of entanglement in the system, which illustrates how particle creation and entanglement generation are directly related. Our work represents a first step towards quantum simulation of high-energy theories using atomic physics experiments-the long-term intention is to extend this approach to real-time quantum simulations of non-Abelian lattice gauge theories.
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http://dx.doi.org/10.1038/nature18318DOI Listing
June 2016

Realization of a scalable Shor algorithm.

Science 2016 Mar;351(6277):1068-70

Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria. Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Otto-Hittmair-Platz 1, A-6020 Innsbruck, Austria.

Certain algorithms for quantum computers are able to outperform their classical counterparts. In 1994, Peter Shor came up with a quantum algorithm that calculates the prime factors of a large number vastly more efficiently than a classical computer. For general scalability of such algorithms, hardware, quantum error correction, and the algorithmic realization itself need to be extensible. Here we present the realization of a scalable Shor algorithm, as proposed by Kitaev. We factor the number 15 by effectively employing and controlling seven qubits and four "cache qubits" and by implementing generalized arithmetic operations, known as modular multipliers. This algorithm has been realized scalably within an ion-trap quantum computer and returns the correct factors with a confidence level exceeding 99%.
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http://dx.doi.org/10.1126/science.aad9480DOI Listing
March 2016

Lifetime development of behavioural phenotype in the house mouse (Mus musculus).

Front Zool 2015 24;12 Suppl 1:S17. Epub 2015 Aug 24.

Behavioral Biology, University of Osnabrueck, Barbarastrasse 11, 49076 Osnabrueck, Germany.

With each trajectory taken during the ontogeny of an individual, the number of optional behavioural phenotypes that can be expressed across its life span is reduced. The initial range of phenotypic plasticity is largely determined by the genetic material/composition of the gametes whereas interacting with the given environment shapes individuals to adapt to/cope with specific demands. In mammalian species, the phenotype is shaped as the foetus grows, depending on the environment in the uterus, which in turn depends on the outer environment the mother experiences during pregnancy. After birth, a complex interaction between innate constitution and environmental conditions shapes individual lifetime trajectories, bringing about a wide range of diversity among individual subjects. In laboratory mice inbreeding has been systematically induced in order to reduce the genetic variability between experimental subjects. In addition, within most laboratories conducting behavioural phenotyping with mice, breeding and housing conditions are highly standardised. Despite such standardisation efforts a considerable amount of variability persists in the behaviour of mice. There is good evidence that phenotypic variation is not merely random but might involve individual specific behavioural patterns consistent over time. In order to understand the mechanisms and the possible adaptive value of the maintenance of individuality we review the emergence of behavioural phenotypes over the course of the life of (laboratory) mice. We present a literature review summarizing developmental stages of behavioural development of mice along with three illustrative case studies. We conclude that the accumulation of environmental differences and experiences lead to a "mouse individuality" that becomes increasingly stable over the lifetime.
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http://dx.doi.org/10.1186/1742-9994-12-S1-S17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4722345PMC
February 2016

Stacked modulation formats enabling highest-sensitivity optical free-space links.

Opt Express 2015 Aug;23(17):21942-57

A new modulation scheme with a sensitivity of 2.3 photons per bit at a bit-error ratio (BER) of 10(-3) is discussed theoretically and demonstrated experimentally. We achieve a limiting sensitivity of 2.3 photons per bit (3.7 dB photons per bit) by stacking the modulation formats 64PPM, 4FSK and polarization-switched (PS) QPSK. This modulation stack encodes 11 bit per symbol (PPM: 6 bit, FSK: 2 bit, PS-PQSK: 3 bit). We also replaced 4FSK by 2ODFM (2-channel multiplex) for comparison. With 64PPM-2OFDM-PS-QPSK a total of 12 bit are encoded (PPM: 6 bit, 2 OFDM channels with PS-QPSK: 2 × 3 bit). Both modulation stacks show a similar limiting sensitivity and are probably the highest sensitivities so far reported for a BER of 10(-3), Our theoretical considerations are supported by simulations and experiments.
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http://dx.doi.org/10.1364/OE.23.021942DOI Listing
August 2015

Flexible terabit/s Nyquist-WDM super-channels using a gain-switched comb source.

Opt Express 2015 Jan;23(2):724-38

Terabit/s super-channels are likely to become the standard for next-generation optical networks and optical interconnects. A particularly promising approach exploits optical frequency combs for super-channel generation. We show that injection locking of a gain-switched laser diode can be used to generate frequency combs that are particularly well suited for terabit/s super-channel transmission. This approach stands out due to its extraordinary stability and flexibility in tuning both center wavelength and line spacing. We perform a series of transmission experiments using different comb line spacings and modulation formats. Using 9 comb lines and 16QAM signaling, an aggregate line rate (net data rate) of 1.296 Tbit/s (1.109 Tbit/s) is achieved for transmission over 150 km of standard single mode fiber (SSMF) using a spectral bandwidth of 166.5 GHz, which corresponds to a (net) spectral efficiency of 7.8 bit/s/Hz (6.7 bit/s/Hz). The line rate (net data rate) can be boosted to 2.112 Tbit/s (1.867 Tbit/s) for transmission over 300 km of SSMF by using a bandwidth of 300 GHz and QPSK modulation on the weaker carriers. For the reported net data rates and spectral efficiencies, we assume a variable overhead of either 7% or 20% for forward- error correction depending on the individual sub-channel quality after fiber transmission.
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http://dx.doi.org/10.1364/OE.23.000724DOI Listing
January 2015

Optimally coherent Kerr combs generated with crystalline whispering gallery mode resonators for ultrahigh capacity fiber communications.

Phys Rev Lett 2015 Mar 2;114(9):093902. Epub 2015 Mar 2.

FEMTO-ST Institute (CNRS UMR6174), Optics Department, 15B Avenue des Montboucons, 25030 Besançon cedex, France.

Optical Kerr frequency combs are known to be effective coherent multiwavelength sources for ultrahigh capacity fiber communications. These combs are the frequency-domain counterparts of a wide variety of spatiotemporal dissipative structures, such as cavity solitons, chaos, or Turing patterns (rolls). In this Letter, we demonstrate that Turing patterns, which correspond to the so-called primary combs in the spectral domain, are optimally coherent in the sense that for the same pump power they provide the most robust carriers for coherent data transmission in fiber communications using advanced modulation formats. Our model is based on a stochastic Lugiato-Lefever equation which accounts for laser pump frequency jitter and amplified spontaneous emission noise induced by the erbium-doped fiber amplifier. Using crystalline whispering-gallery-mode resonators with quality factor Q∼10^{9} for the comb generation, we show that when the noise is accounted for, the coherence of a primary comb is significantly higher than the coherence of their solitonic or chaotic counterparts for the same pump power. In order to confirm this theoretical finding, we perform an optical fiber transmission experiment using advanced modulation formats, and we show that the coherence of the primary comb is high enough to enable data transmission of up to 144  Gbit/s per comb line, the highest value achieved with a Kerr comb so far. This performance evidences that compact crystalline photonic systems have the potential to play a key role in a new generation of coherent fiber communication networks, alongside fully integrated systems.
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http://dx.doi.org/10.1103/PhysRevLett.114.093902DOI Listing
March 2015

Complementary symbiont contributions to plant decomposition in a fungus-farming termite.

Proc Natl Acad Sci U S A 2014 Oct 22;111(40):14500-5. Epub 2014 Sep 22.

Centre for Social Evolution, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark; China National Genebank, BGI-Shenzen, Shenzhen 518083, China;

Termites normally rely on gut symbionts to decompose organic matter but the Macrotermitinae domesticated Termitomyces fungi to produce their own food. This transition was accompanied by a shift in the composition of the gut microbiota, but the complementary roles of these bacteria in the symbiosis have remained enigmatic. We obtained high-quality annotated draft genomes of the termite Macrotermes natalensis, its Termitomyces symbiont, and gut metagenomes from workers, soldiers, and a queen. We show that members from 111 of the 128 known glycoside hydrolase families are represented in the symbiosis, that Termitomyces has the genomic capacity to handle complex carbohydrates, and that worker gut microbes primarily contribute enzymes for final digestion of oligosaccharides. This apparent division of labor is consistent with the Macrotermes gut microbes being most important during the second passage of comb material through the termite gut, after a first gut passage where the crude plant substrate is inoculated with Termitomyces asexual spores so that initial fungal growth and polysaccharide decomposition can proceed with high efficiency. Complex conversion of biomass in termite mounds thus appears to be mainly accomplished by complementary cooperation between a domesticated fungal monoculture and a specialized bacterial community. In sharp contrast, the gut microbiota of the queen had highly reduced plant decomposition potential, suggesting that mature reproductives digest fungal material provided by workers rather than plant substrate.
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http://dx.doi.org/10.1073/pnas.1319718111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4209977PMC
October 2014

Coherent terabit communications with microresonator Kerr frequency combs.

Nat Photonics 2014 May;8(5):375-380

Institute of Photonics and Quantum Electronics (IPQ) and Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany.

Optical frequency combs have the potential to revolutionize terabit communications. Generation of Kerr combs in nonlinear microresonators represents a particularly promising option enabling line spacings of tens of GHz. However, such combs may exhibit strong phase noise, which has made high-speed data transmission impossible up to now. Here we demonstrate that systematic adjustment of pump conditions for low phase noise enables coherent data transmission with advanced modulation formats that pose stringent requirements on the spectral purity of the comb. In a first experiment, we encode a data stream of 392 Gbit/s on a Kerr comb using quadrature phase shift keying (QPSK) and 16-state quadrature amplitude modulation (16QAM). A second experiment demonstrates feedback-stabilization of the comb and transmission of a 1.44 Tbit/s data stream over up to 300 km. The results show that Kerr combs meet the highly demanding requirements of coherent communications and thus offer an attractive solution towards chip-scale terabit/s transceivers.
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http://dx.doi.org/10.1038/nphoton.2014.57DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4028627PMC
May 2014

Four-in-one interferometer for coherent and self-coherent detection.

Opt Express 2013 Jun;21(11):13293-304

Institutes IPQ and IMT, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.

A compact micro-optical interferometer is presented that combines two optical 90° hybrids or, alternatively, four delay interferometers into one interferometer structure sharing one tunable delay line. The interferometer can function as a frontend of either a coherent receiver or of a self-coherent receiver by adjusting the waveplates and the delay line. We built a prototype on a LIGA bench. We characterized the device and demonstrated its functionality by successful reception of a 112 Gbit/s signal.
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http://dx.doi.org/10.1364/OE.21.013293DOI Listing
June 2013

Silicon-organic hybrid (SOH) IQ modulator using the linear electro-optic effect for transmitting 16QAM at 112 Gbit/s.

Opt Express 2013 Jun;21(11):13219-27

Karlsruhe Institute of Technology (KIT), Institutes IPQ and IMT, Karlsruhe, Germany.

Advanced modulation formats call for suitable IQ modulators. Using the silicon-on-insulator (SOI) platform we exploit the linear electro-optic effect by functionalizing a photonic integrated circuit with an organic χ(2)-nonlinear cladding. We demonstrate that this silicon-organic hybrid (SOH) technology allows the fabrication of IQ modulators for generating 16QAM signals with data rates up to 112 Gbit/s. To the best of our knowledge, this is the highest single-polarization data rate achieved so far with a silicon-integrated modulator. We found an energy consumption of 640 fJ/bit.
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http://dx.doi.org/10.1364/OE.21.013219DOI Listing
June 2013

Certifying systematic errors in quantum experiments.

Phys Rev Lett 2013 May 30;110(18):180401. Epub 2013 Apr 30.

Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Walter-Flex-Straße 3, D-57068 Siegen, Germany.

When experimental errors are ignored in an experiment, the subsequent analysis of its results becomes questionable. We develop tests to detect systematic errors in quantum experiments where only a finite amount of data is recorded and apply these tests to tomographic data taken in an ion trap experiment. We put particular emphasis on quantum state tomography and present three detection methods: the first two employ linear inequalities while the third is based on the generalized likelihood ratio.
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http://dx.doi.org/10.1103/PhysRevLett.110.180401DOI Listing
May 2013

Experimental characterization of quantum dynamics through many-body interactions.

Phys Rev Lett 2013 Feb 5;110(6):060403. Epub 2013 Feb 5.

Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.

We report on the implementation of a quantum process tomography technique known as direct characterization of quantum dynamics applied on coherent and incoherent single-qubit processes in a system of trapped (40)Ca(+) ions. Using quantum correlations with an ancilla qubit, direct characterization of quantum dynamics reduces substantially the number of experimental configurations required for a full quantum process tomography and all diagonal elements of the process matrix can be estimated with a single setting. With this technique, the system's relaxation times T(1) and T(2) were measured with a single experimental configuration. We further show the first, complete characterization of single-qubit processes using a single generalized measurement realized through multibody correlations with three ancilla qubits.
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http://dx.doi.org/10.1103/PhysRevLett.110.060403DOI Listing
February 2013