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ABSTRACT: INTRODUCTION: We developed four prototype sheath-turning auxiliary devices (STADs) and evaluated them in an in vitro study setup designed to enable the change of catheter direction in endovascular interventions. METHODS: Four different prototypes, A through D, of STADs were designed and created by modifying commercially available dilators and catheters. All STADs work with different anchor-like tips to ensure fixation inside the vessel at the puncture site. The STAD is loaded into the introducer sheath, retracted with the introducer sheath, and turned at the puncture site. The STADs were tested in an in vitro vascular study setup using bovine veins. Success rates and procedure times were calculated, and the handling, reliability, and overall performance were evaluated. The maximum soft tissue thickness (STTmax) applicable was tested using bovine vessels with 7-mm thickness surrounded by a soft tissue phantom consisting of chicken breast. A retrospective cross-sectional observation in 108 patients from our center was performed to provide mean STTmax at the common femoral artery in patients for comparison. RESULTS: The success rate ranged between 75% for prototype D and 90% for prototypes A and C. The procedure time averaged 60 seconds (range, 25-165 seconds). The mean handling was rated 2.4 (good) for prototype A, 2.0 (good) for prototype B, 2.6 (satisfactory) for prototype C, and 3.5 (poor) for prototype D. Mean reliability was rated 3.4 (satisfactory) for prototype A, 2.0 (good) for prototype B, 1.6 (good) for prototype C, and 2.4 (good) for prototype D. Mean overall performance was rated 2.0 (good) for prototype C, 2.6 (satisfactory) for prototype B, 3.3 (poor) for prototype D, and 3.4 (poor) for prototype A. In the cross-sectional patient observation, the mean STTmax was 3.3 cm (range, 0,5-13 cm) with a 95% confidence interval of the distribution including an STTmax of up to 8 cm. The STTmax was ≤5 cm in 100 of 108 patients (93%). The applicable STTmax for prototype A was 1 cm (8 of 10 successful cases), 3 cm for prototype B (9 of 10 successful cases), 5 cm for prototype C (8 of 10 successful cases), and 3 cm for prototype D (7 of 10 successful cases). CONCLUSIONS: All four STAD prototypes offered the ability of turning the sheaths at the puncture site in an in vitro vascular study setup. In the future, this concept may allow routine clinical performance of turning maneuvers at the groin vascular access site.
Journal of vascular surgery: official publication, the Society for Vascular Surgery [and] International Society for Cardiovascular Surgery, North American Chapter 01/2013; · 3.52 Impact Factor
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Grzegorz Bauman,
Ulf Lützen,
Mathias Ullrich,
Thomas Gaass,
Julien Dinkel,
Gunnar Elke,
Patrick Meybohm,
Inéz Frerichs, Beata Hoffmann,
Jan Borggrefe,
Hans-Christian Knuth,
Jasper Schupp,
Hermann Prüm,
Monika Eichinger,
Michael Puderbach,
Jürgen Biederer,
Christian Hintze
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ABSTRACT: To compare unenhanced lung ventilation-weighted (VW) and perfusion-weighted (QW) imaging based on Fourier decomposition (FD) magnetic resonance (MR) imaging with the clinical reference standard single photon emission computed tomography (SPECT)/computed tomography (CT) in an animal experiment.
The study was approved by the local animal care committee. Lung ventilation and perfusion was assessed in seven anesthetized pigs by using a 1.5-T MR imager and SPECT/CT. For time-resolved FD MR imaging, sets of lung images were acquired by using an untriggered two-dimensional balanced steady-state free precession sequence (repetition time, 1.9 msec; echo time, 0.8 msec; acquisition time per image, 118 msec; acquisition rate, 3.33 images per second; flip angle, 75°; section thickness, 12 mm; matrix, 128 × 128). Breathing displacement was corrected with nonrigid image registration. Parenchymal signal intensity was analyzed pixelwise with FD to separate periodic changes of proton density induced by respiration and periodic changes of blood flow. Spectral lines representing respiratory and cardiac frequencies were integrated to calculate VW and QW images. Ventilation and perfusion SPECT was performed after inhalation of dispersed technetium 99m ((99m)Tc) and injection of (99m)Tc-labeled macroaggregated albumin. FD MR imaging and SPECT data were independently analyzed by two physicians in consensus. A regional statistical analysis of homogeneity and pathologic signal changes was performed.
Images acquired in healthy animals by using FD MR imaging and SPECT showed a homogeneous distribution of VW and QW imaging and pulmonary ventilation and perfusion, respectively. The gravitation-dependent signal distribution of ventilation and perfusion in all animals was similarly observed at FD MR imaging and SPECT. Incidental ventilation and perfusion defects were identically visualized by using both modalities.
This animal experiment demonstrated qualitative agreement in the assessment of regional lung ventilation and perfusion between contrast media-free and radiation-free FD MR imaging and conventional SPECT/CT.
Radiology 05/2011; 260(2):551-9. · 5.73 Impact Factor
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ABSTRACT: Iodine enhancement is a marker for malignancy in pulmonary nodules. The purpose of this in vitro study was to assess whether dual energy computed tomography (DECT) can be used to detect iodine and to distinguish iodine from disperse calcifications in artificial pulmonary nodules.
Small, medium, and large artificial nodules (n=54), with increasing concentrations of iodine or calcium corresponding to an increase in Hounsfield Units (HU) of 15, 30, 45, and 90 at 120 kV, were scanned in a chest phantom with DECT at 80 and 140 kV. Attenuation values of each nodule were measured using semi-automated volumetric analysis. The mean DE ratio with 95% confidence intervals (CI) was calculated for each nodule.
The mean maximum diameter of the 18 small nodules was 12 mm (standard deviation: 0.4), 16 mm (0.4) for the 18 medium nodules, and 30 mm (1.1) for the 18 large nodules. There was no overlap of 95% CI of DE ratios of iodine and calcium in nodules≥16 mm. In nodules<16 mm, there was an overlap of DE ratios in low contrast lesions.
DECT can distinguish iodine from calcium in artificial nodules≥16 mm in vitro. In smaller lesions, a clear differentiation is not possible.
European journal of radiology 11/2010; 80(3):e516-9. · 2.65 Impact Factor
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Juergen Biederer,
Julien Dinkel,
Gregor Remmert,
Siri Jetter,
Simeon Nill,
Torsten Moser,
Rolf Bendl,
Carsten Thierfelder,
Michael Fabel,
Uwe Oelfke,
Michael Bock,
Christian Plathow,
Hendrik Bolte,
Thomas Welzel, Beata Hoffmann,
Günter Hartmann,
Wolfgang Schlegel,
Jürgen Debus,
Martin Heller,
Hans-Ulrich Kauczor
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ABSTRACT: Four-dimensional (4D) imaging is a key to motion-adapted radiotherapy of lung tumors. We evaluated in a ventilated ex vivo system how size and displacement of artificial pulmonary nodules are reproduced with helical 4D-CT, 4D-MRI, and linac-integrated cone beam CT (CBCT).
Four porcine lungs with 18 agarose nodules (mean diameters 1.3-1.9 cm), were ventilated inside a chest phantom at 8/min and subject to 4D-CT (collimation 24 x 1.2 mm, pitch 0.1, slice/increment 24 x 10(2)/1.5/0.8 mm, pitch 0.1, temporal resolution 0.5 s), 4D-MRI (echo-shared dynamic three-dimensional-flash; repetition/echo time 2.13/0.72 ms, voxel size 2.7 x 2.7 x 4.0 mm, temporal resolution 1.4 s) and linac-integrated 4D-CBCT (720 projections, 3-min rotation, temporal resolution approximately 1 s). Static CT without respiration served as control. Three observers recorded lesion size (RECIST-diameters x/y/z) and axial displacement. Interobserver- and interphase-variation coefficients (IO/IP VC) of measurements indicated reproducibility.
Mean x/y/z lesion diameters in cm were equal on static and dynamic CT (1.88/1.87; 1.30/1.39; 1.71/1.73; p > 0.05), but appeared larger on MRI and CBCT (2.06/1.95 [p < 0.05 vs. CT]; 1.47/1.28 [MRI vs. CT/CBCT p < 0.05]; 1.86/1.83 [CT vs. CBCT p < 0.05]). Interobserver-VC for lesion sizes were 2.54-4.47% (CT), 2.29-4.48% (4D-CT); 5.44-6.22% (MRI) and 4.86-6.97% (CBCT). Interphase-VC for lesion sizes ranged from 2.28% (4D-CT) to 10.0% (CBCT). Mean displacement in cm decreased from static CT (1.65) to 4D-CT (1.40), CBCT (1.23) and MRI (1.16).
Lesion sizes are exactly reproduced with 4D-CT but overestimated on 4D-MRI and CBCT with a larger variability due to limited temporal and spatial resolution. All 4D-modalities underestimate lesion displacement.
International journal of radiation oncology, biology, physics 03/2009; 73(3):919-26. · 4.59 Impact Factor
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ABSTRACT: Motion-adapted radiotherapy with gated irradiation or tracking of tumor positions requires dedicated imaging techniques such as four-dimensional (4D) helical computed tomography (CT) for patient selection and treatment planning. The objective was to evaluate the reproducibility of spatial information for small objects on respiratory-gated 4D helical CT using computer-assisted volumetry of lung nodules in a ventilated ex vivo system.
Five porcine lungs were inflated inside a chest phantom and prepared with 55 artificial nodules (mean diameter, 8.4 mm +/- 1.8). The lungs were respirated by a flexible diaphragm and scanned with 40-row detector CT (collimation, 24 x 1.2 mm; pitch, 0.1; rotation time, 1 s; slice thickness, 1.5 mm; increment, 0.8 mm). The 4D-CT scans acquired during respiration (eight per minute) and reconstructed at 0-100% inspiration and equivalent static scans were scored for motion-related artifacts (0 or absent to 3 or relevant). The reproducibility of nodule volumetry (three readers) was assessed using the variation coefficient (VC).
The mean volumes from the static and dynamic inspiratory scans were equal (364.9 and 360.8 mm3, respectively, p = 0.24). The static and dynamic end-expiratory volumes were slightly greater (371.9 and 369.7 mm3, respectively, p = 0.019). The VC for volumetry (static) was 3.1%, with no significant difference between 20 apical and 20 caudal nodules (2.6% and 3.5%, p = 0.25). In dynamic scans, the VC was greater (3.9%, p = 0.004; apical and caudal, 2.6% and 4.9%; p = 0.004), with a significant difference between static and dynamic in the 20 caudal nodules (3.5% and 4.9%, p = 0.015). This was consistent with greater motion-related artifacts and image noise at the diaphragm (p <0.05). The VC for interobserver variability was 0.6%.
Residual motion-related artifacts had only minimal influence on volumetry of small solid lesions. This indicates a high reproducibility of spatial information for small objects in low pitch helical 4D-CT reconstructions.
International Journal of Radiation OncologyBiologyPhysics 12/2007; 69(5):1642-9. · 4.11 Impact Factor
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ABSTRACT: To analyse the image quality of retrospectively gated helical CT using controlled respiratory motion of porcine lung explants.
Five porcine lungs were examined inside a chest phantom. A silicone membrane was rhythmically inflated and deflated to simulate diaphragmatic respiration. Dynamic images (regular respiration at 8/min) and static scans (w/o respiration) at 0/25/50/75 and 100% of maximum inspiration were acquired with a 40-row detector CT scanner (rotation time 1s, pitch 0.1). Image quality on multi-planar reformations was evaluated by two observers. Partial projection artifacts, stepladder-artifacts and noise were compared for upper, middle and lower parts of the lung and different respiratory phases (scores 0-3 for absent, minimal, moderate and diagnostically relevant artifacts).
Partial projection effects were limited to dynamic scans (mean score 1.33). Stepladder artifacts predominated in dynamic series compared to static series (mean score 0.55 versus 0.1; p<0.001). Image noise was not related to lung motion (mean scores 0.68-0.81). All artifacts predominated close to the diaphragm compared to the upper and middle parts of the lung (p<0.001 to p=0.02, respectively). Partial projection and stepladder artifacts were less in end-inspiration and end-expiration than within the respiration (p<0.001 and p=0.17, respectively). Diagnostically relevant artifacts were noted 9 times (9/9 close to diaphragm, 7/9 partial-projection).
Even in ideal realistic conditions, helical 4D-CT produced tolerable artifacts which could be overcome by radiologists.
Radiotherapy and Oncology 11/2007; 85(2):215-22. · 5.58 Impact Factor
