Publications by authors named "Marco Das"

121 Publications

CIRSE Standards of Practice on Percutaneous Transhepatic Cholangiography, Biliary Drainage and Stenting.

Cardiovasc Intervent Radiol 2021 Jul 29. Epub 2021 Jul 29.

Interventional Radiology Unit, Department of Radiology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.

This CIRSE Standards of Practice document is aimed at interventional radiologists and provides best practices for performing percutaneous transhepatic cholangiography, biliary drainage and stenting. It has been developed by an expert writing group established by the CIRSE Standards of Practice Committee.
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http://dx.doi.org/10.1007/s00270-021-02903-4DOI Listing
July 2021

[Ankylosing hyperostosis of the spine (Forestier's disease) as rare cause of dysphagia with a severe complication of pleural empyema].

Z Gerontol Geriatr 2021 Aug 31;54(5):436-437. Epub 2021 May 31.

Diagnostische und interventionelle Radiologie, Campus Duisburg, Helios Klinikum Duisburg, Duisburg, Deutschland.

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http://dx.doi.org/10.1007/s00391-021-01904-9DOI Listing
August 2021

Does ATTRACT change our DVT management practice?

Authors:
Marco Das

Br J Radiol 2021 Apr 7;94(1120):20200939. Epub 2021 Jan 7.

Department of Diagnostic and Interventional Radiology, Helios Kliniken Duisburg, Germany Teaching Hospital of Heinrich-Heine University, Duesseldorf, Germany.

In 2017, the long awaited results of the ATTRACT trial were published in the leaving the scientific community with disappointment as the study did not show the expected results. Producing not the expected outcome is not uncommon in science - furthermore, it is important to disapprove common beliefs. But has the ATTRACT trial really the power to change our practice? Are the results correct in terms of evidence based on the methods used?
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http://dx.doi.org/10.1259/bjr.20200939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8010551PMC
April 2021

Retrospectively ECG-gated helical vs. non-ECG-synchronized high-pitch CTA of the aortic root for TAVI planning.

PLoS One 2020 12;15(5):e0232673. Epub 2020 May 12.

Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.

Background: Multidetector computed tomography (MDCT) plays a key role in patient assessment prior to transcatheter aortic valve implantation (TAVI). However, to date no consensus has been established on what is the optimal pre-procedural imaging protocol. Variability in pre-TAVI acquisition protocols may lead to discrepancies in aortic annulus measurements and may potentially influence prosthesis size selection.

Purpose: The current study evaluates the magnitude of differences in aortic annulus measurements using max-systolic, end-diastolic, and non-ECG-synchronized imaging, as well as the impact of method on prosthesis size selection.

Material And Methods: Fifty consecutive TAVI-candidates, who underwent retrospectively-ECG-gated CT angiography (CTA) of the aortic root, directly followed by non-ECG-synchronized high-pitch CT of the entire aorta, were retrospectively included. Aortic root dimensions were assessed at each 10% increment of the R-R interval (0-100%) and on the non-ECG-synchronized scan. Dimensional changes within the cardiac cycle were evaluated using a 1-way repeated ANOVA. Agreement in measurements between max-systole, end-diastole and non-ECG-synchronized scans was assessed with Bland-Altman analysis.

Results: Maximal dimensions of the aortic root structures and minimum annulus-coronary ostia distances were measured during systole. Max-systolic measurements were significantly and substantially larger than end-diastolic (p<0.001) and non-ECG-synchronized measurements (p<0.001). Due to these discrepancies, the three methods resulted in the same prosthesis size selection in only 48-62% of patients.

Conclusions: The systematic differences between max-systolic, end-diastolic and non-ECG-synchronized measurements for relevant aortic annular dimensions are both statistically significant and clinically relevant. Imaging strategy impacts prosthesis size selection in nearly half the TAVI-candidates. End-diastolic and non-ECG-synchronized imaging does not provide optimal information for prosthesis size selection. Systolic image acquisition is necessary for assessment of maximal annular dimensions and minimum annulus-coronary ostia distances.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0232673PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217477PMC
August 2020

Nitroglycerin as a radiosensitizer in non-small cell lung cancer: Results of a prospective imaging-based phase II trial.

Clin Transl Radiat Oncol 2020 Mar 13;21:49-55. Epub 2019 Dec 13.

The D-Lab & The M-Lab, Department of Precision Medicine, GROW - School for Oncology and Developmental Biology, Maastricht University, Maastricht, The Netherlands.

Background: Nitroglycerin is proposed as an agent to reduce tumour hypoxia by improving tumour perfusion. We investigated the potential of nitroglycerin as a radio-sensitizer in non-small cell lung cancer (NSCLC) and the potential of functional imaging for patient selection.

Material And Methods: Trial NCT01210378 is a single arm phase II trial, designed to detect 15% improvement in 2-year overall survival (primary endpoint) in stage IB-IV NSCLC patients treated with radical (chemo-) radiotherapy and a Transiderm-Nitro 5 patch during radiotherapy. Patients underwent dynamic contrast-enhanced CTs (DCE-CT) and HX4 (hypoxia) PET/CTs before and after nitroglycerin. Secondary endpoints were progression-free survival, toxicity and the prognostic value of tumour perfusion/hypoxia at baseline and after nitroglycerin.

Results: The trial stopped after a futility analysis after 42 patients. At median follow-up of 41 months, two-year and median OS were 58% (95% CI: 44-78%) and 38 months (95% CI: 22-54 months), respectively. Nitroglycerin could not reduce tumour hypoxia. DCE-CT parameters did not correlate with OS, whereas hypoxic tumours had a worse OS (p = 0.029). Changes in high-uptake fraction of HX4 and tumour blood flow were negatively correlated (r = -0.650, p = 0.022). The heterogeneity in treatment modalities and patient characteristics combined with a small sample size made further subgroup analysis of survival results impossible. Toxicity related to nitroglyerin was limited to headache (17%) and hypotension (2.4%).

Conclusion: Nitroglycerin did not improve OS of NSCLC patients treated with (chemo-)radiotherapy. A general ability of nitroglycerin to reduce hypoxia was not shown.
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http://dx.doi.org/10.1016/j.ctro.2019.12.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993056PMC
March 2020

Initial Imaging-Guided Strategy Versus Routine Care in Patients With Non-ST-Segment Elevation Myocardial Infarction.

J Am Coll Cardiol 2019 11;74(20):2466-2477

Department of Cardiology, Maastricht University Medical Center, Maastricht, the Netherlands; Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands; Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, the Netherlands. Electronic address:

Background: Patients with non-ST-segment elevation myocardial infarction and elevated high-sensitivity cardiac troponin levels often routinely undergo invasive coronary angiography (ICA), but many do not have obstructive coronary artery disease.

Objectives: This study investigated whether cardiovascular magnetic resonance imaging (CMR) or computed tomographic angiography (CTA) may serve as a safe gatekeeper for ICA.

Methods: This randomized controlled trial (NCT01559467) in 207 patients (age 64 years; 62% male patients) with acute chest pain, elevated high-sensitivity cardiac troponin T levels (>14 ng/l), and inconclusive electrocardiogram compared a CMR- or CTA-first strategy with a control strategy of routine clinical care. Follow-up ICA was recommended when initial CMR or CTA suggested myocardial ischemia, infarction, or obstructive coronary artery disease (≥70% stenosis). Primary efficacy and secondary safety endpoints were referral to ICA during hospitalization and 1-year outcomes (major adverse cardiac events and complications), respectively.

Results: The CMR- and CTA-first strategies reduced ICA compared with routine clinical care (87% [p = 0.001], 66% [p < 0.001], and 100%, respectively), with similar outcome (hazard ratio: CMR vs. routine, 0.78 [95% confidence interval: 0.37 to 1.61]; CTA vs. routine, 0.66 [95% confidence interval: 0.31 to 1.42]; and CMR vs. CTA, 1.19 [95% confidence interval: 0.53 to 2.66]). Obstructive coronary artery disease after ICA was found in 61% of patients in the routine clinical care arm, in 69% in the CMR-first arm (p = 0.308 vs. routine), and in 85% in the CTA-first arm (p = 0.006 vs. routine). In the non-CMR and non-CTA arms, follow-up CMR and CTA were performed in 67% and 13% of patients and led to a new diagnosis in 33% and 3%, respectively (p < 0.001).

Conclusions: A novel strategy of implementing CMR or CTA first in the diagnostic process in non-ST-segment elevation myocardial infarction is a safe gatekeeper for ICA.
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http://dx.doi.org/10.1016/j.jacc.2019.09.027DOI Listing
November 2019

Impact of iodine concentration and iodine delivery rate on contrast enhancement in coronary CT angiography: a randomized multicenter trial (CT-CON).

Eur Radiol 2019 Nov 23;29(11):6109-6118. Epub 2019 Apr 23.

Departments of Radiology and Cardiology, Erasmus University Medical Center, Rotterdam, The Netherlands.

Objective: To compare the effect of contrast medium iodine concentration on contrast enhancement, heart rate, and injection pressure when injected at a constant iodine delivery rate in coronary CT angiography (CTA).

Methods: One thousand twenty-four patients scheduled for coronary CTA were prospectively randomized to receive one of four contrast media: iopromide 300 mg I/ml, iohexol 350 mg I/ml, iopromide 370 mg I/ml, or iomeprol 400 mg I/ml. Contrast media were delivered at an equivalent iodine delivery rate of 2.0 g I/s. Intracoronary attenuation was measured and compared (per vessel and per segment). Heart rate before and after contrast media injection was documented. Injection pressure was recorded (n = 403) during contrast medium injection and compared between groups.

Results: Intracoronary attenuation values were similar for the different contrast groups. The mean attenuation over all segments ranged between 384 HU for 350 mg I/ml and 395 HU for 400 mg I/ml (p = 0.079). Dose-length product (p = 0.8424), signal-to-noise ratio (all p > 0.05), time to peak (p = 0.324), and changes in heart rate (p = 0.974) were comparable between groups. The peak pressures differed: 197.4 psi for 300 mg I/ml (viscosity 4.6 mPa s), 229.8 psi for 350 mg I/ml (10.4 mPa s), 216.1 psi for 370 mg I/ml (9.5 mPa s), and 243.7 psi for 400 mg I/ml (12.6 mPa s) (p < 0.0001).

Conclusion: Intravascular attenuation and changes in heart rate are independent of iodine concentration when contrast media are injected at the same iodine delivery rate. Differences in injection pressures are associated with the viscosity of the contrast media.

Key Points: • The contrast enhancement in coronary CT angiography is independent of the iodine concentration when contrast media are injected at body temperature (37 °C) with the same iodine delivery rate. • Iodine concentration does not influence the change in heart rate when contrast media are injected at identical iodine delivery rates. • For a fixed iodine delivery rate and contrast temperature, the viscosity of the contrast medium affects the injection pressure.
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http://dx.doi.org/10.1007/s00330-019-06196-7DOI Listing
November 2019

Quantification of epicardial adipose tissue in patients undergoing hybrid ablation for atrial fibrillation.

Eur J Cardiothorac Surg 2019 Jul;56(1):79-86

Department of Cardiology, Maastricht University Medical Center, Maastricht, Netherlands.

Objectives: Epicardial adipose tissue volume (EAT-V) has been linked to atrial fibrillation (AF) recurrences after catheter ablation. We retrospectively studied the association between atrial EAT-V and outcome after hybrid AF ablation (epicardial surgical and endocardial catheter ablation).

Methods: On preoperative cardiac computed tomography angiography scans, the left atrium and right atrium were manually delineated using the open source ImageJ. With custom-made automated software, the number of pixels in the regions of interest on each slice was calculated. On the basis of the Hounsfield units, pixel size and slice thickness, EAT-V was computed and normalized in relation to the body surface area (BSA) and the myocardial tissue volume.

Results: Eighty-five patients were included. Left atrial and right atrial EAT-V normalized to BSA were not significantly different between paroxysmal and persistent AF [0.84 (0.51-1.50) vs 0.81 (0.57-1.18), 1.74 (1.02-2.56) vs 1.55 (1.26-2.18), all P = 0.9], neither between the acute conduction block and no acute conduction block in the epicardial box lesion [0.92 (0.55-1.39) vs 0.72 (0.55-1.24), P = 0.5, right atrium not applicable], nor between the sinus rhythm and arrhythmia recurrence after 12 months [0.88 (0.55-1.48) vs 0.63 (0.47-1.10), 1.61 (1.11-2.50) vs 1.55 (1.20-2.20), all P > 0.1]. Left atrial EAT-V normalized to myocardial tissue volume was not different between the groups.

Conclusions: This study could neither confirm that EAT-V was predictive of recurrence of supraventricular arrhythmias in patients undergoing a hybrid AF ablation, nor that EAT-V was different between patients with paroxysmal AF and persistent and long-standing persistent AF. This suggests that EAT-V might not affect the outcome in surgical ablation procedures and therefore should not influence preoperative or intraoperative decision-making.
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http://dx.doi.org/10.1093/ejcts/ezy472DOI Listing
July 2019

Computed Tomography Pulmonary Angiography during Pregnancy: Radiation Dose of Commonly Used Protocols and the Effect of Scan Length Optimization.

Korean J Radiol 2019 02;20(2):313-322

Department of Radiology & Nuclear Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands.

Objective: To evaluate the radiation dose for pregnant women and fetuses undergoing commonly used computed tomography of the pulmonary arteries (CTPA) scan protocols and subsequently evaluate the simulated effect of an optimized scan length.

Materials And Methods: A total of 120 CTPA datasets were acquired using four distinctive scan protocols, with 30 patients per protocol. These datasets were mapped to Cristy phantoms in order to simulate pregnancy and to assess the effect of an effective radiation dose (in mSv) in the first, second, or third trimester of pregnancy, including a simulation of fetal dose in second and third trimesters. The investigated scan protocols involved a 64-slice helical scan at 120 kVp, a high-pitch dual source acquisition at 100 kVp, a dual-energy acquisition at 80/140 kVp, and an automated-kV-selection, high pitch helical scan at a reference kV of 100 kV. The effective dose for women and fetuses was simulated before and after scan length adaptation. The original images were interpreted before and after scan length adaptations to evaluate potentially missed diagnoses.

Results: Large inter-scanner and inter-protocol variations were found; application of the latest technology decreased the dose for non-pregnant women by 69% (7.0-2.2 mSv). Individual scan length optimization proved safe and effective, decreasing the fetal dose by 76-83%. Nineteen (16%) cases of pulmonary embolism were diagnosed and, after scan length optimization, none were missed.

Conclusion: Careful CTPA scan protocol selection and additional optimization of scan length may result in significant radiation dose reduction for a pregnant patient and her fetus, whilst maintaining diagnostic confidence.
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http://dx.doi.org/10.3348/kjr.2017.0779DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6342764PMC
February 2019

Guideline-Oriented Therapy of Lower Extremity Peripheral Artery Disease (PAD) - Current Data and Perspectives.

Rofo 2019 Apr 21;191(4):311-322. Epub 2019 Jan 21.

Radiology, Helios University Hospital Wuppertal, University Witten/Herdecke, Wuppertal, Germany.

Background:  Because of the demographic change, lower extremity peripheral artery disease (PAD) is becoming increasingly relevant with respect to health economics. PAD patients often suffer from multiple diseases. Consequently, therapy is commonly complex and requires an interdisciplinary approach. Because of rapid technical developments, interventional endovascular therapy regimens play an increasingly important role.

Method:  Review and literature search on the basis of the current German S3 guidelines on the therapy of PAD as well as international guidelines. In terms of state-of-the-art therapies, relevant current studies were considered.

Results:  Knowledge of existing guidelines and recommendations as well as new therapeutic approaches is essential for the adequate therapy of PAD patients. A close cooperation between the interventional radiologist and the vascular surgeon is the key to success. In addition to established conservative approaches and invasive bypass surgery, the endovascular approach has been a mainstay in the TASC A and B environment for years. It has recently shown promising results in advanced PAD conditions, such as TASC C and D. An endovascular-first strategy is defined in most guidelines.

Conclusion:  A primarily endovascular-first strategy has become the standard in the majority of even complex lesions of the lower extremity arterial system. Regarding the crural segment, a decrease in mortality compared to bypass surgery has been demonstrated. Further evidence can be expected from ongoing randomized multicenter trials.

Key Points:   · Adequate diagnostic examination is essential for the classification and strategy of therapy in PAD. · Therapeutic decisions are ideally made in an interdisciplinary conference. · Interventional therapy of intermittent claudication after exhaustion of conservative and medicamentous therapy. · Endovascular-first approach in supra- and infrainguinal lesions. · Additional evidence expected from future randomized trials.

Citation Format: · Kersting J, Kamper L, Das M et al. Guideline-Oriented Therapy of Lower Extremity Peripheral Artery Disease (PAD) - Current Data and Perspectives. Fortschr Röntgenstr 2019; 191: 311 - 322.
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http://dx.doi.org/10.1055/a-0690-9365DOI Listing
April 2019

Personalization of injection protocols to the individual patient's blood volume and automated tube voltage selection (ATVS) in coronary CTA.

PLoS One 2018 26;13(9):e0203682. Epub 2018 Sep 26.

Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands.

Purpose: The aim was to assess personalised contrast media (CM) protocols-based on patient's blood volume (BV) and automated tube voltage selection (ATVS)-in coronary computed tomography angiography (CCTA).

Methods: A total of 114 consecutive patients received an ECG-triggered or ECG-gated helical scan on a 3rd-generation dual-source CT with 70-120kV (ATVS) and 330mAsqual.ref. CM was adapted to BV, scan time (s) and kV. Image quality (IQ) was assessed in a 17-segment coronary model using attenuation values (HU), contrast-to-noise (CNR), signal-to-noise ratio (SNR) (objective IQ) and a Likert scale (subjective IQ: 1 = poor/2 = sufficient/3 = good/4 = excellent). ig.

Results: Patient distribution was: n = 60 for 70kV, n = 37 80kV and n = 17 90kV. Mean BV was 5.4±0.6L for men and 4.1±0.6L for women. Mean CM volume (300 mg I/mL) and flow rate were: 30.9±6.4mL and 3.3±0.5mL/s (70kV); 40.8±7.1mL and 4.5±0.6mL/s (80kV); 53.6±8.6mL and 5.7±0.6mL/s (90kV). Overall mean HU was >300HU in 98.2% (112/114) of patients. Overall mean attenuation was below 300HU in two scans (70kV) due to late scan timing. Of 1.661 segments, 95.4% was assessable. Mean CNR was 14±4(70kV), 13±3(80kV) and 14±4(90kV); mean SNR was 10±2(both 70kV+80kV) and 9±2(90kV). Objective IQ was comparable between kV settings, protocols and sex. Subjective IQ was diagnostic in all scans and excellent-sufficient in 95.4% of segments.

Conclusions: Personalisation of CCTA CM injection protocols to BV and ATVS is a promising technique to tailor CM administration to the individual patient, while maintaining diagnostic IQ.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0203682PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6157854PMC
March 2019

Aortic root evaluation prior to transcatheter aortic valve implantation-Correlation of manual and semi-automatic measurements.

PLoS One 2018 28;13(6):e0199732. Epub 2018 Jun 28.

Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.

Background: Pre-procedural TAVI planning requires highly sophisticated and time-consuming manual measurements performed by experienced readers. Semi-automatic software may assist with partial automation of assessment of multiple parameters. The aim of this study was to evaluate differences between manual and semi-automatic measurements in terms of agreement and time.

Methods: One hundred and twenty TAVI candidates referred for the retrospectively ECG-gated CTA (2nd and 3rd generation dual source CT) were evaluated. Fully manual and semi-automatic measurements of fourteen aortic root parameters were assessed in the 20% phase of the R-R interval. Reading time was compared using paired samples t-test. Inter-software agreement was calculated using the Intraclass correlation coefficient (ICC) in a 2-way mixed effects model. Differences between manual and semi-automatic measurements were evaluated using Bland-Altman analysis.

Results: The time needed for evaluation using semi-automatic assessment (3 min 24 s ± 1 min 7 s) was significantly lower (p<0.001) compared to a fully manual approach (6 min 31 sec ± 1 min 1 sec). Excellent inter-software agreement was found (ICC = 0.93 ± 0.0; range:0.90-0.95). The same prosthesis size from manual and semi-automatic measurements was selected in 92% of cases, when sizing was based on annular area. Prosthesis sizing based on annular short diameter and perimeter agreed in 99% and 96% cases, respectively.

Conclusion: Use of semi-automatic software in pre-TAVI evaluation results in comparable results in respect of measurements and selected valve prosthesis size, while necessary reading time is significantly lower.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0199732PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6023104PMC
December 2018

Do CTA measurements of annular diameter, perimeter and area result in different TAVI prosthesis sizes?

Int J Cardiovasc Imaging 2018 Nov 16;34(11):1819-1829. Epub 2018 Jun 16.

Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ, Maastricht, The Netherlands.

Incorrect prosthesis size has direct impact on patient outcome after transcatheter aortic valve implantation (TAVI) procedure. Currently, annular diameter, area or perimeter may be used for prosthesis size selection. The aim was to evaluate whether the use different annular dimensions would result in the selection of different prosthesis sizes, when assessed in the same TAVI-candidate during the same phase of a cardiac cycle. Fifty consecutive TAVI-candidates underwent retrospectively ECG-gated computed tomography angiography (CTA). Aortic root dimensions were assessed in the 20% phase of the R-R interval. Annular short diameter, perimeter and area were used to select the prosthesis size, based on the industry recommendations for a self-expandable (Medtronic CoreValve; MCV) and balloon-expandable (Edwards Sapien XT Valve; ESV) valve. Complete agreement on selected prosthesis size amongst all three annular dimensions was observed in 62% (31/50; ESV) and 30% (15/50; MCV). Short aortic annulus measurement resulted in a smaller prosthesis size in 20% (10/50; ESV) and in 60% of cases (30/50; MCV) compared to the size suggested by both annular perimeter and area. In 18% (9/50; ESV) and 10% of cases (5/50; MCV) a larger prosthesis would have been selected based on annular perimeter compared to annular diameter and area. Prosthesis size derived from area was always in agreement with at least one other parameter in all cases. Aortic annulus area appears to be the most robust parameter for TAVI-prosthesis size selection, regardless of the specific prosthesis size. Short aortic annulus diameter may underestimate the prosthesis size, while use of annular perimeter may lead to size overestimation in some cases.
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http://dx.doi.org/10.1007/s10554-018-1394-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6208923PMC
November 2018

Comparing dual energy CT and subtraction CT on a phantom: which one provides the best contrast in iodine maps for sub-centimetre details?

Eur Radiol 2018 Dec 28;28(12):5051-5059. Epub 2018 May 28.

Department of Radiology and Nuclear Medicine, Radboud University Medical Center, P.O. Box 9101 (route 766), 6500 HB, Nijmegen, The Netherlands.

Objectives: To compare contrast-to-noise ratios (CNRs) and iodine discrimination thresholds on iodine maps derived from dual energy CT (DECT) and subtraction CT (SCT).

Methods: A contrast-detail phantom experiment was performed with 2 to 15 mm diameter tubes containing water or iodinated contrast concentrations ranging from 0.5 mg/mL to 20 mg/mL. DECT scans were acquired at 100 kVp and at 140 kVp+Sn filtration. SCT scans were acquired at 100 kVp. Iodine maps were created by material decomposition (DECT) or by subtraction of water scans from iodine scans (SCT). Matched exposure levels varied from 8 to 15 mGy. Iodine discrimination thresholds (C) and response times were determined by eight observers.

Results: The adjusted mean CNR was 1.9 times higher for SCT than for DECT. Exposure level had no effect on CNR. All observers discriminated all details ≥10 mm at 12 and 15 mGy. For sub-centimetre details, the lowest calculated C was ≤ 0.50 mg/mL for SCT and 0.64 mg/mL for DECT. The smallest detail was discriminated at ≥4.4 mg/mL with SCT and at ≥7.4 mg/mL with DECT. Response times were lower for SCT than DECT.

Conclusions: SCT results in higher CNR and reduced iodine discrimination thresholds compared to DECT for sub-centimetre details.

Key Points: • Subtraction CT iodine maps exhibit higher CNR than dual-energy iodine maps • Lower iodine concentrations can be discriminated for sub-cm details with SCT • Response times are lower using SCT compared to dual-energy CT.
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http://dx.doi.org/10.1007/s00330-018-5496-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6223839PMC
December 2018

CT Angiography in the Lower Extremity Peripheral Artery Disease Feasibility of an Ultra-Low Volume Contrast Media Protocol.

Cardiovasc Intervent Radiol 2018 Nov 22;41(11):1751-1764. Epub 2018 May 22.

Department of Radiology and Nuclear Medicine, Maastricht University Medical Center+, P. Debyelaan 25, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.

Purpose: The ALARA principle is not only relevant for effective dose (ED) reduction, but also applicable for contrast media (CM) management. Therefore, the aim was to evaluate the feasibility of an ultra-low CM protocol in the assessment of peripheral artery disease (PAD).

Materials And Methods: Fifty PAD patients were scanned on third-generation dual-source computed tomography, from diaphragm to the forefoot, as follows: tube voltage: 70 kV, reference effective tube current: 90 mAs, collimation: 192 × 2 × 0.6 mm, with individualized acquisition timing. The protocol ED (mSv) was quantified with dedicated software. CM protocol consisted of 15 ml test bolus and 30 ml main bolus (300 mgI/ml) injected at 5 ml/s, followed by a 40 ml saline chaser at the same flow rate. Aorto-popliteal bolus transit time was used to calculate the overall acquisition time and delay. Objective (hounsfield units-HU; contrast-to-noise ratio-CNR) and subjective image quality (four-point Likert score) were assessed at different anatomical regions from the aorta down to the forefoot.

Results: Mean attenuation values were exceeding 250 HU from aorta down to the anterior tibial artery with CNR < 13. However, decline in attenuation was observed in more distal region with mean values of 165 and 199 HU, in left and right dorsalis pedis artery, respectively. Mode subjective image quality from the level of aorta down to the popliteal segment was excellent; below the knee mode score was good. The mean ED per protocol was 1.1 ± 0.5 mSv.

Conclusion: Use of an ultra-low CM volume protocol at 70 kV is feasible in the evaluation of PAD, resulting in good to excellent image quality with mean ED of 1.1 ± 0.5 mSv.

Level Of Evidence: Level 3, Local non-random sample.
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http://dx.doi.org/10.1007/s00270-018-1979-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6182764PMC
November 2018

The role of standard non-ECG gated chest CT in cardiac assessment: design and rationale of the (CaPaCT) study.

Eur Radiol Exp 2018 27;2(1). Epub 2018 Apr 27.

1Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, P. Debyelaan 25, PO Box 5800, 6202 AZ Maastricht, The Netherlands.

Modern high-performance computed tomography (CT) scanners with improved scan acquisition times now allow for routine assessment of cardiac pathologies on chest CTs, which can result in numerous incidental cardiac findings. The CaPaCT study, an observer blinded, single-centre study, aims to assess the visibility, management and possible clinical impact of incidental cardiac pathologies that are now becoming visible on standard chest CTs. A total of 217 consecutive patients referred for a chest CT on a high-performance third-generation dual-source CT scanner will be included. Tube voltage settings will be chosen via automated kV selection. Dedicated cardiac reconstructions will be added to the standard post-processing: 0.6-mm slice thickness, 0.4-mm increment and Bv36 kernel (iterative reconstruction/strength 3). Primary endpoints will be the presence and extent of coronary artery disease (CAD) assessed via a 17-segment model. These data will be collected and analysed by two experienced, blinded cardiac radiologists. Furthermore, information on aortic and mitral valve morphology/calcification and pericardial abnormalities will be collected. The CAD Reporting and Data System classification will subsequently be used to assess the management and possible clinical burden of any incidentally detected CAD. Additionally, objective and subjective image quality (attenuation, contrast-to-noise, signal-to-noise and 5-point Likert scale) of the obtained cardiac reconstructions will be assessed.
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http://dx.doi.org/10.1186/s41747-018-0039-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5920004PMC
April 2018

Implementation of Size-Dependent Local Diagnostic Reference Levels for CT Angiography.

AJR Am J Roentgenol 2018 May 23;210(5):W226-W233. Epub 2018 Mar 23.

1 Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.

Objective: Diagnostic reference levels (DRLs) are established for standard-sized patients; however, patient dose in CT depends on patient size. The purpose of this study was to introduce a method for setting size-dependent local diagnostic reference levels (LDRLs) and to evaluate these LDRLs in comparison with size-independent LDRLs and with respect to image quality.

Materials And Methods: One hundred eighty-four aortic CT angiography (CTA) examinations performed on either a second-generation or third-generation dual-source CT scanner were included; we refer to the second-generation dual-source CT scanner as "CT1" and the third-generation dual-source CT scanner as "CT2." The volume CT dose index (CTDI) and patient diameter (i.e., the water-equivalent diameter) were retrieved by dose-monitoring software. Size-dependent DRLs based on a linear regression of the CTDI versus patient size were set by scanner type. Size-independent DRLs were set by the 5th and 95th percentiles of the CTDI values. Objective image quality was assessed using the signal-to-noise ratio (SNR), and subjective image quality was assessed using a 4-point Likert scale.

Results: The CTDI depended on patient size and scanner type (R = 0.72 and 0.78, respectively; slope = 0.05 and 0.02 mGy/mm; p < 0.001). Of the outliers identified by size-independent DRLs, 30% (CT1) and 67% (CT2) were adequately dosed when considering patient size. Alternatively, 30% (CT1) and 70% (CT2) of the outliers found with size-dependent DRLs were not identified using size-independent DRLs. A negative correlation was found between SNR and CTDI (R = 0.36 for CT1 and 0.45 for CT2). However, all outliers had a subjective image quality score of sufficient or better.

Conclusion: We introduce a method for setting size-dependent LDRLs in CTA. Size-dependent LDRLs are relevant for assessing the appropriateness of the radiation dose for an individual patient on a specific CT scanner.
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http://dx.doi.org/10.2214/AJR.17.18566DOI Listing
May 2018

Response to Baur et al. (2017).

Am J Ind Med 2018 04;61(4):355-357

Institute for Occupational Medicine, RWTH Aachen University, Aachen, Germany.

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http://dx.doi.org/10.1002/ajim.22812DOI Listing
April 2018

Contrast agent concentration optimization in CTA using low tube voltage and dual-energy CT in multiple vendors: a phantom study.

Int J Cardiovasc Imaging 2018 Aug 8;34(8):1265-1275. Epub 2018 Mar 8.

Department of Radiology, University Medical Center Utrecht, Utrecht University, P. O. Box 85500, 3508 GA, Utrecht, The Netherlands.

We investigated the feasibility and extent to which iodine concentration can be reduced in computed tomography angiography imaging of the aorta and coronary arteries using low tube voltage and virtual monochromatic imaging of 3 major dual-energy CT (DECT) vendors. A circulation phantom was imaged with dual source CT (DSCT), gemstone spectral imaging (GSI) and dual-layer spectral detector CT (SDCT). For each scanner, a reference scan was acquired at 120 kVp using routine iodine concentration (300 mg I/ml). Subsequently, scans were acquired at lowest possible tube potential (70, 80, 80 kVp, respectively), and DECT-mode (80/150Sn, 80/140 and 120 kVp, respectively) in arterial phase after administration of iodine (300, 240, 180, 120, 60, 30 mg I/ml). Objective image quality was evaluated using attenuation, CNR and dose corrected CNR (DCCNR) measured in the aorta and left main coronary artery. Average DCCNR at reference was 227.0, 39.7 and 60.2 for DSCT, GSI and SDCT. Maximum iodine concentration reduction without loss of DCCNR was feasible down to 180 mg I/ml (40% reduced) for DSCT (DCCNR 467.1) and GSI (DCCNR 46.1) using conventional CT low kVp, and 120 mg I/ml (60% reduced) for SDCT (DCCNR 171.5) using DECT mode. Low kVp scanning and DECT allows for 40-60% iodine reduction without loss in image quality compared to reference. Optimal scan protocol and to which extent varies per vendor. Further patient studies are needed to extend and translate our findings to clinical practice.
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http://dx.doi.org/10.1007/s10554-018-1329-xDOI Listing
August 2018

Optimizing Pulmonary Embolism Computed Tomography in the Age of Individualized Medicine: A Prospective Clinical Study.

Invest Radiol 2018 05;53(5):306-312

Purpose: The aim of the study was to simultaneously optimize contrast media (CM) injection and scan parameters for the individual patient during computed tomography pulmonary angiography (CTPA).

Methods: In this study (NCT02611115), 235 consecutive patients suspected of having pulmonary embolism were prospectively enrolled. Automated kV selection software on a third-generation multidetector computed tomography adapted tube voltage to the individual patient, based on scout scans. The contrast injection protocol was adapted to both patient body weight and kV-setting selection via a predefined formula, based on previous research. Injection data were collected from a contrast media and radiation dose monitoring software. Attenuation was measured in Hounsfield units (HU) in the pulmonary trunk (PT); attenuation values 200 HU or greater were considered diagnostic. Subjective image quality was assessed by using a 4-point Likert scale at the level of the PT, lobar, segmental, and subsegmental arteries. Results between groups were reported as mean ± SD.

Results: Two hundred twenty-two patients (94%) were scanned at a kV setting below 100 kV: n = 108 for 70 kV, n = 82 for 80 kV, and n = 32 for 90 kV. Mean CM bolus volume (in milliliters) and total iodine load (in grams of iodine) for 70 to 90 kV were as follows: 24 ± 3 mL and 7 ± 1 g I, 29 ± 4 mL and 9 ± 2 g I, and 38 ± 4 mL and 11 ± 1 g I, respectively. Mean flow rates (in milliliters per second) and iodine delivery rates (in grams of iodine per second) were 3.0 ± 0.4 mL/s and 0.9 ± 0.1 g I/s (70 kV), 3.6 ± 0.4 mL/s and 1.0 ± 0.1 g I/s (80 kV), and 4.7 ± 0.5 mL/s and 1.3 ± 0.1 g I/s (90 kV). Mean radiation doses were 1.3 ± 0.3 mSv at 70 kV, 1.7 ± 0.4 mSv at 80 kV, and 2.2 ± 0.6 mSv at 90 kV. Mean vascular attenuation in the PT for each kV group was as follows: 397 ± 101 HU for 70 kV, 398 ± 96 HU for 80 kV, and 378 ± 100 HU for 90 kV, P = 0.59. Forty-six patients (21%) showed pulmonary embolism on the CTPA. One scan (90 kV) showed nondiagnostic segmental pulmonary arteries, and 5% of subsegmental arteries were of nondiagnostic image quality. All other segments were considered diagnostic-excellent subjective image quality.

Conclusions: Simultaneously optimizing both CM injections and kV settings to the individual patient in CTPA results in diagnostic attenuation with on average 24 to 38 mL of CM volume and a low radiation dose for most patients. This individualized protocol may help overcome attenuation-variation problems between patients and kV settings in CTPA.
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http://dx.doi.org/10.1097/RLI.0000000000000443DOI Listing
May 2018

Comprehensive Cardiac CT With Myocardial Perfusion Imaging Versus Functional Testing in Suspected Coronary Artery Disease: The Multicenter, Randomized CRESCENT-II Trial.

JACC Cardiovasc Imaging 2018 11 13;11(11):1625-1636. Epub 2017 Dec 13.

Department of Cardiology, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Radiology, Erasmus University Medical Center, Rotterdam, the Netherlands; Stanford Cardiovascular Institute, Stanford University, Palo Alto, California.

Objectives: This study sought to assess the effectiveness, efficiency, and safety of a tiered, comprehensive cardiac computed tomography (CT) protocol in comparison with functional testing.

Background: Although CT angiography accurately rules out coronary artery disease (CAD), incorporation of CT myocardial perfusion imaging as part of a tiered diagnostic approach could improve the clinical value and efficiency of cardiac CT in the diagnostic work-up of patients with angina pectoris.

Methods: Between July 2013 and November 2015, 268 patients (mean age 58 years; 49% female) with stable angina (mean pre-test probability 54%) were prospectively randomized between cardiac CT and standard guideline-directed functional testing (95% exercise electrocardiography). The tiered cardiac CT protocol included a calcium scan, followed by CT angiography if calcium was detected. Patients with ≥50% stenosis on CT angiography underwent CT myocardial perfusion imaging.

Results: By 6 months, the primary endpoint, the rate of invasive coronary angiograms without a European Society of Cardiology class I indication for revascularization, was lower in the CT group than in the functional testing group (2 of 130 [1.5%] vs. 10 of 138 [7.2%]; p = 0.035), whereas the proportion of invasive angiograms with a revascularization indication was higher (88% vs. 50%; p = 0.017). The median duration until the final diagnosis was 0 (0 of 0) days in the CT group and 0 (0 of 17) in the functional testing group (p < 0.001). Overall, 13% of patients randomized to CT required further testing, compared with 37% in the functional testing group (p < 0.001). The adverse event rate was similar (3% vs. 3%; p = 1.000), although the median cumulative radiation dose was higher for the CT group (3.1 mSv [interquartile range: 1.6 to 7.8] vs. 0 mSv [interquartile range: 0.0 to 7.1]; p < 0.001).

Conclusions: In patients with suspected stable CAD, a tiered cardiac CT protocol with dynamic perfusion imaging offers a fast and efficient alternative to functional testing. (Comprehensive Cardiac CT Versus Exercise Testing in Suspected Coronary Artery Disease 2 [CRESCENT2]; NCT02291484).
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http://dx.doi.org/10.1016/j.jcmg.2017.10.010DOI Listing
November 2018

Clustering of multi-parametric functional imaging to identify high-risk subvolumes in non-small cell lung cancer.

Radiother Oncol 2017 12 6;125(3):379-384. Epub 2017 Nov 6.

Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center, The Netherlands.

Background And Purpose: We aimed to identify tumour subregions with characteristic phenotypes based on pre-treatment multi-parametric functional imaging and correlate these subregions to treatment outcome. The subregions were created using imaging of metabolic activity (FDG-PET/CT), hypoxia (HX4-PET/CT) and tumour vasculature (DCE-CT).

Materials And Methods: 36 non-small cell lung cancer (NSCLC) patients underwent functional imaging prior to radical radiotherapy. Kinetic analysis was performed on DCE-CT scans to acquire blood flow (BF) and volume (BV) maps. HX4-PET/CT and DCE-CT scans were non-rigidly co-registered to the planning FDG-PET/CT. Two clustering steps were performed on multi-parametric images: first to segment each tumour into homogeneous subregions (i.e. supervoxels) and second to group the supervoxels of all tumours into phenotypic clusters. Patients were split based on the absolute or relative volume of supervoxels in each cluster; overall survival was compared using a log-rank test.

Results: Unsupervised clustering of supervoxels yielded four independent clusters. One cluster (high hypoxia, high FDG, intermediate BF/BV) related to a high-risk tumour type: patients assigned to this cluster had significantly worse survival compared to patients not in this cluster (p = 0.035).

Conclusions: We designed a subregional analysis for multi-parametric imaging in NSCLC, and showed the potential of subregion classification as a biomarker for prognosis. This methodology allows for a comprehensive data-driven analysis of multi-parametric functional images.
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http://dx.doi.org/10.1016/j.radonc.2017.09.041DOI Listing
December 2017

Influence of gray level discretization on radiomic feature stability for different CT scanners, tube currents and slice thicknesses: a comprehensive phantom study.

Acta Oncol 2017 Nov 8;56(11):1544-1553. Epub 2017 Sep 8.

a Department of Radiation Oncology (MAASTRO, the D-Lab), GROW-School for Oncology and Developmental Biology , Maastricht University Medical Centre , Maastricht , The Netherlands.

Background: Radiomic analyses of CT images provide prognostic information that can potentially be used for personalized treatment. However, heterogeneity of acquisition- and reconstruction protocols influences robustness of radiomic analyses. The aim of this study was to investigate the influence of different CT-scanners, slice thicknesses, exposures and gray-level discretization on radiomic feature values and their stability.

Material And Methods: A texture phantom with ten different inserts was scanned on nine different CT-scanners with varying tube currents. Scans were reconstructed with 1.5 mm or 3 mm slice thickness. Image pre-processing comprised gray-level discretization in ten different bin widths ranging from 5 to 50 HU and different resampling methods (i.e., linear, cubic and nearest neighbor interpolation to 1 × 1 × 3 mm voxels) were investigated. Subsequently, 114 textural radiomic features were extracted from a 2.1 cm sphere in the center of each insert. The influence of slice thickness, exposure and bin width on feature values was investigated. Feature stability was assessed by calculating the concordance correlation coefficient (CCC) in a test-retest setting and for different combinations of scanners, tube currents and slice thicknesses.

Results: Bin width influenced feature values, but this only had a marginal effect on the total number of stable features (CCC > 0.85) when comparing different scanners, slice thicknesses or exposures. Most radiomic features were affected by slice thickness, but this effect could be reduced by resampling the CT-images before feature extraction. Statistics feature 'energy' was the most dependent on slice thickness. No clear correlation between feature values and exposures was observed.

Conclusions: CT-scanner, slice thickness and bin width affected radiomic feature values, whereas no effect of exposure was observed. Optimization of gray-level discretization to potentially improve prognostic value can be performed without compromising feature stability. Resampling images prior to feature extraction decreases the variability of radiomic features.
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http://dx.doi.org/10.1080/0284186X.2017.1351624DOI Listing
November 2017

Predicting tumor hypoxia in non-small cell lung cancer by combining CT, FDG PET and dynamic contrast-enhanced CT.

Acta Oncol 2017 Nov 25;56(11):1591-1596. Epub 2017 Aug 25.

a Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology , Maastricht University Medical Center , Maastricht , The Netherlands.

Background: Most solid tumors contain inadequately oxygenated (i.e., hypoxic) regions, which tend to be more aggressive and treatment resistant. Hypoxia PET allows visualization of hypoxia and may enable treatment adaptation. However, hypoxia PET imaging is expensive, time-consuming and not widely available. We aimed to predict hypoxia levels in non-small cell lung cancer (NSCLC) using more easily available imaging modalities: FDG-PET/CT and dynamic contrast-enhanced CT (DCE-CT).

Material And Methods: For 34 NSCLC patients, included in two clinical trials, hypoxia HX4-PET/CT, planning FDG-PET/CT and DCE-CT scans were acquired before radiotherapy. Scans were non-rigidly registered to the planning CT. Tumor blood flow (BF) and blood volume (BV) were calculated by kinetic analysis of DCE-CT images. Within the gross tumor volume, independent clusters, i.e., supervoxels, were created based on FDG-PET/CT. For each supervoxel, tumor-to-background ratios (TBR) were calculated (median SUV/aorta SUV) for HX4-PET/CT and supervoxel features (median, SD, entropy) for the other modalities. Two random forest models (cross-validated: 10 folds, five repeats) were trained to predict the hypoxia TBR; one based on CT, FDG, BF and BV, and one with only CT and FDG features. Patients were split in a training (trial NCT01024829) and independent test set (trial NCT01210378). For each patient, predicted, and observed hypoxic volumes (HV) (TBR > 1.2) were compared.

Results: Fifteen patients (3291 supervoxels) were used for training and 19 patients (1502 supervoxels) for testing. The model with all features (RMSE training: 0.19 ± 0.01, test: 0.27) outperformed the model with only CT and FDG-PET features (RMSE training: 0.20 ± 0.01, test: 0.29). All tumors of the test set were correctly classified as normoxic or hypoxic (HV > 1 cm) by the best performing model.

Conclusions: We created a data-driven methodology to predict hypoxia levels and hypoxia spatial patterns using CT, FDG-PET and DCE-CT features in NSCLC. The model correctly classifies all tumors, and could therefore, aid tumor hypoxia classification and patient stratification.
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http://dx.doi.org/10.1080/0284186X.2017.1349332DOI Listing
November 2017

Erratum to "Lung function not affected by asbestos exposure in workers with normal Computed Tomography scan".

Am J Ind Med 2017 09;60(9):839

Institute for Occupational and Social Medicine, RWTH Aachen University, Aachen, Germany.

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http://dx.doi.org/10.1002/ajim.22754DOI Listing
September 2017

Validation of myocardial perfusion quantification by dynamic CT in an ex-vivo porcine heart model.

Int J Cardiovasc Imaging 2017 Nov 23;33(11):1821-1830. Epub 2017 May 23.

Center for Medical Imaging - North East Netherlands, University Medical Center Groningen, University of Groningen, Hanzeplein 1, P.O. Box EB44, 9713 GZ, Groningen, The Netherlands.

To test the accuracy of quantification of myocardial perfusion imaging (MPI) using computed tomography (CT) in ex-vivo porcine models. Five isolated porcine hearts were perfused according to Langendorff. Hearts were perfused using retrograde flow through the aorta and blood flow, blood pressure and heart rate were monitored throughout the experiment. An inflatable cuff was placed around the circumflex (Cx) artery to create stenosis grades which were monitored using a pressure wire, analysing perfusion at several fractional flow reserve values of 1.0, 0.7, 0.5, 0.3, and total occlusion. Second-generation dual-source CT was used to acquire dynamic MPI in shuttle mode with 350 mAs/rot at 100 kVp. CT MPI was performed using VPCT myocardium software, calculating myocardial blood flow (MBF, ml/100 ml/min) for segments perfused by Cx artery and non-Cx myocardial segments. Microspheres were successfully infused at three stenosis grades in three of the five hearts. Heart rate ranged from 75 to 134 beats per minute. Arterial blood flow ranged from 0.5 to 1.4 l min and blood pressure ranged from 54 to 107 mmHg. MBF was determined in 400 myocardial segments of which 115 were classified as 'Cx-territory'. MBF was significantly different between non-Cx and Cx segments at stenosis grades with an FFR ≤0.70 (Mann-Whitney U test, p < 0.05). MBF showed a moderate correlation with microsphere MBF for the three individual hearts (Pearson correlation 0.62-0.76, p < 0.01). CT MPI can be used to determine regional differences in myocardial perfusion parameters, based on severity of coronary stenosis. Significant differences in MBF could be measured between non-ischemic and ischemic segments.
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http://dx.doi.org/10.1007/s10554-017-1171-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5682851PMC
November 2017

Personalized Feedback on Staff Dose in Fluoroscopy-Guided Interventions: A New Era in Radiation Dose Monitoring.

Cardiovasc Intervent Radiol 2017 Nov 12;40(11):1756-1762. Epub 2017 May 12.

Department of Radiology, Maastricht University Medical Centre, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.

Purpose: Radiation safety and protection are a key component of fluoroscopy-guided interventions. We hypothesize that providing weekly personal dose feedback will increase radiation awareness and ultimately will lead to optimized behavior. Therefore, we designed and implemented a personalized feedback of procedure and personal doses for medical staff involved in fluoroscopy-guided interventions.

Materials And Methods: Medical staff (physicians and technicians, n = 27) involved in fluoroscopy-guided interventions were equipped with electronic personal dose meters (PDMs). Procedure dose data including the dose area product and effective doses from PDMs were prospectively monitored for each consecutive procedure over an 8-month period (n = 1082). A personalized feedback form was designed displaying for each staff individually the personal dose per procedure, as well as relative and cumulative doses. This study consisted of two phases: (1) 1-5th months: Staff did not receive feedback (n = 701) and (2) 6-8th months: Staff received weekly individual dose feedback (n = 381). An anonymous evaluation was performed on the feedback and occupational dose.

Results: Personalized feedback was scored valuable by 76% of the staff and increased radiation dose awareness for 71%. 57 and 52% reported an increased feeling of occupational safety and changing their behavior because of personalized feedback, respectively. For technicians, the normalized dose was significantly lower in the feedback phase compared to the prefeedback phase: [median (IQR) normalized dose (phase 1) 0.12 (0.04-0.50) µSv/Gy cm versus (phase 2) 0.08 (0.02-0.24) µSv/Gy cm, p = 0.002].

Conclusion: Personalized dose feedback increases radiation awareness and safety and can be provided to staff involved in fluoroscopy-guided interventions.
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http://dx.doi.org/10.1007/s00270-017-1690-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5651709PMC
November 2017

Lung function not affected by asbestos exposure in workers with normal Computed Tomography scan.

Am J Ind Med 2017 May 30;60(5):422-431. Epub 2017 Mar 30.

Institute for Occupational and Social Medicine, RWTH Aachen University, Aachen, Germany.

Background: It has been suggested that asbestos exposure affects lung function, even in the absence of asbestos-related pulmonary interstitial or pleural changes or emphysema.

Methods: We analyzed associations between well-known asbestos-related risk factors, such as individual cumulative asbestos exposure, and key lung function parameters in formerly asbestos-exposed power industry workers (N = 207) with normal CT scans. For this, we excluded participants with emphysema, fibrosis, pleural changes, or any combination of these.

Results: The lung function parameters of FVC, FEV1, DLCO/VA, and airway resistance were significantly associated with the burden of smoking, BMI and years since end of exposure (only DLCO/VA). However, they were not affected by factors directly related to amount (eg, cumulative exposure) or duration of asbestos exposure.

Conclusions: Our results confirm the well-known correlation between lung function, smoking habits, and BMI. However, we found no significant association between lung function and asbestos exposure.
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http://dx.doi.org/10.1002/ajim.22717DOI Listing
May 2017

Contrast Media Administration in Coronary Computed Tomography Angiography - A Systematic Review.

Rofo 2017 Apr 6;189(4):312-325. Epub 2017 Mar 6.

Maastricht University Medical Center, Maastricht University CARIM School for Cardiovascular Diseases, Maastricht, Netherlands.

 Various different injection parameters influence enhancement of the coronary arteries. There is no consensus in the literature regarding the optimal contrast media (CM) injection protocol. The aim of this study is to provide an update on the effect of different CM injection parameters on the coronary attenuation in coronary computed tomographic angiography (CCTA).  Studies published between January 2001 and May 2014 identified by Pubmed, Embase and MEDLINE were evaluated. Using predefined inclusion criteria and a data extraction form, the content of each eligible study was assessed. Initially, 2551 potential studies were identified. After applying our criteria, 36 studies were found to be eligible. Studies were systematically assessed for quality based on the validated Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-II checklist.  Extracted data proved to be heterogeneous and often incomplete. The injection protocol and outcome of the included publications were very diverse and results are difficult to compare. Based on the extracted data, it remains unclear which of the injection parameters is the most important determinant for adequate attenuation. It is likely that one parameter which combines multiple parameters (e. g. IDR) will be the most suitable determinant of coronary attenuation in CCTA protocols.  Research should be directed towards determining the influence of different injection parameters and defining individualized optimal IDRs tailored to patient-related factors (ideally in large randomized trials).   · This systematic review provides insight into decisive factors on coronary attenuation.. · Different and contradicting outcomes are reported on coronary attenuation in CCTA.. · One parameter combining multiple parameters (IDR) is likely decisive in coronary attenuation.. · Research should aim at defining individualized optimal IDRs tailored to individual factors.. · Future directions should be tailored towards the influence of different injection parameters.. · Mihl C, Maas M, Turek J et al. Contrast Media Administration in Coronary Computed Tomography Angiography - A Systematic Review. Fortschr Röntgenstr 2017; 189: 312 - 325.
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http://dx.doi.org/10.1055/s-0042-121609DOI Listing
April 2017
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