scholarly journals Implementation of free breathing respiratory amplitude‐gated treatments

2021 ◽  
Author(s):  
Susannah V. Hickling ◽  
Andrew J. Veres ◽  
Douglas J. Moseley ◽  
Michael P. Grams
Keyword(s):  
Free Breathing

Comparison of breath-hold and free-breathing quantitative pulmonary perfusion MRI

Pneumologie ◽  
2012 ◽  
Vol 66 (06) ◽  
Author(s):  
D Maxien ◽  
M Ingrisch ◽  
F Meinel ◽  
S Thieme ◽  
MF Reiser ◽  
...  
Keyword(s):  
Free Breathing ◽  
Perfusion Mri ◽  
Breath Hold ◽  
Pulmonary Perfusion

scholarly journals Imaging coronary plaques using 3D motion-compensated [18F]NaF PET/MR

2021 ◽  
Author(s):  
Johannes Mayer ◽  
Thomas-Heinrich Wurster ◽  
Tobias Schaeffter ◽  
Ulf Landmesser ◽  
Andreas Morguet ◽  
...  
Keyword(s):  
Attenuation Correction ◽  
Free Breathing ◽  
Cardiac Motion ◽  
Water Fraction ◽  
3 Dimensional ◽  
Background Ratio ◽  
Motion Models ◽  
Physiological Motion ◽  
Atherosclerosis Imaging ◽  
Novel Applications

Abstract Background Cardiac PET has recently found novel applications in coronary atherosclerosis imaging using [18F]NaF as a radiotracer, highlighting vulnerable plaques. However, the resulting uptakes are relatively small, and cardiac motion and respiration-induced movement of the heart can impair the reconstructed images due to motion blurring and attenuation correction mismatches. This study aimed to apply an MR-based motion compensation framework to [18F]NaF data yielding high-resolution motion-compensated PET and MR images. Methods Free-breathing 3-dimensional Dixon MR data were acquired, retrospectively binned into multiple respiratory and cardiac motion states, and split into fat and water fraction using a model-based reconstruction framework. From the dynamic MR reconstructions, both a non-rigid cardiorespiratory motion model and a motion-resolved attenuation map were generated and applied to the PET data to improve image quality. The approach was tested in 10 patients and focal tracer hotspots were evaluated concerning their target-to-background ratio, contrast-to-background ratio, and their diameter. Results MR-based motion models were successfully applied to compensate for physiological motion in both PET and MR. Target-to-background ratios of identified plaques improved by 7 ± 7%, contrast-to-background ratios by 26 ± 38%, and the plaque diameter decreased by −22 ± 18%. MR-based dynamic attenuation correction strongly reduced attenuation correction artefacts and was not affected by stent-related signal voids in the underlying MR reconstructions. Conclusions The MR-based motion correction framework presented here can improve the target-to-background, contrast-to-background, and width of focal tracer hotspots in the coronary system. The dynamic attenuation correction could effectively mitigate the risk of attenuation correction artefacts in the coronaries at the lung-soft tissue boundary. In combination, this could enable a more reproducible and reliable plaque localisation.

scholarly journals Deep-inspirational breath-hold (DIBH) technique in left-sided breast cancer: various aspects of clinical utility

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Szilvia Gaál ◽  
Zsuzsanna Kahán ◽  
Viktor Paczona ◽  
Renáta Kószó ◽  
Rita Drencsényi ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Side Effects ◽  
Clinical Utility ◽  
Prospective Trial ◽  
Conformal Radiotherapy ◽  
Free Breathing ◽  
Left Breast ◽  
Breath Hold ◽  
Ipsilateral Lung ◽  
Breast Cancer Radiotherapy

Abstract Background Studying the clinical utility of deep-inspirational breath-hold (DIBH) in left breast cancer radiotherapy (RT) was aimed at focusing on dosimetry and feasibility aspects. Methods In this prospective trial all enrolled patients went through planning CT in supine position under both DIBH and free breathing (FB); in whole breast irradiation (WBI) cases prone CT was also taken. In 3-dimensional conformal radiotherapy (3DCRT) plans heart, left anterior descending coronary artery (LAD), ipsilateral lung and contralateral breast doses were analyzed. The acceptance of DIBH technique as reported by the patients and the staff was analyzed; post-RT side-effects including radiation lung changes (visual scores and lung density measurements) were collected. Results Among 130 enrolled patients 26 were not suitable for the technique while in 16, heart or LAD dose constraints were not met in the DIBH plans. Among 54 and 34 patients receiving WBI and postmastectomy/nodal RT, respectively with DIBH, mean heart dose (MHD) was reduced to < 50%, the heart V25 Gy to < 20%, the LAD mean dose to < 40% and the LAD maximum dose to about 50% as compared to that under FB; the magnitude of benefit was related to the relative increase of the ipsilateral lung volume at DIBH. Nevertheless, heart and LAD dose differences (DIBH vs. FB) individually varied. Among the WBI cases at least one heart/LAD dose parameter was more favorable in the prone or in the supine FB plan in 15 and 4 cases, respectively; differences were numerically small. All DIBH patients completed the RT, inter-fraction repositioning accuracy and radiation side-effects were similar to that of other breast RT techniques. Both the patients and radiographers were satisfied with the technique. Conclusions DIBH is an excellent heart sparing technique in breast RT, but about one-third of the patients do not benefit from that otherwise laborious procedure or benefit less than from an alternative method. Trial registration: retrospectively registered under ISRCTN14360721 (February 12, 2021)

scholarly journals Senkung des intrakraniellen Drucks durch Senkung des zentralvenösen Drucks: Bewertung möglicher Gegenmaßnahmen zum Raumfahrt-assoziierten neuro-okulären Syndrom

2021 ◽  
pp. 1-2
Author(s):  
Sebastian Siebelmann
Keyword(s):  
Intracranial Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Free Breathing ◽  
Optic Disc Edema ◽  
Threshold Device ◽  
Inspiratory Resistance ◽  
Minimal Reduction ◽  
Clinical Conditions ◽  
Impedance Threshold Device

Spaceflight-associated neuro-ocular syndrome (SANS) involves unilateral or bilateral optic disc edema, widening of the optic nerve sheath, and posterior globe flattening. Owing to posterior globe flattening, it is hypothesized that microgravity causes a disproportionate change in intracranial pressure (ICP) relative to intraocular pressure. Countermeasures capable of reducing ICP include thigh cuffs and breathing against inspiratory resistance. Owing to the coupling of central venous pressure (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32 ± 13 yr) who were previously implanted with Ommaya reservoirs for treatment of unrelated clinical conditions, ICP was measured invasively through these ports. Subjects were healthy at the time of testing. CVP was measured invasively by a peripherally inserted central catheter. Participants breathed through an impedance threshold device (ITD, −7 cmH<sub>2</sub>O) to generate negative intrathoracic pressure for 5 min, and subsequently, wore bilateral thigh cuffs inflated to 30 mmHg for 2 min. Breathing through an ITD reduced both CVP (6 ± 2 vs. 3 ± 1 mmHg; <i>P</i> = 0.02) and ICP (16 ± 3 vs. 12 ± 1 mmHg; <i>P</i> = 0.04) compared to baseline, a result that was not observed during the free breathing condition (CVP, 6 ± 2 vs. 6 ± 2 mmHg, <i>P</i> = 0.87; ICP, 15 ± 3 vs. 15 ± 4 mmHg, <i>P</i> = 0.68). Inflation of the thigh cuffs to 30 mmHg caused no meaningful reduction in CVP in all four individuals (5 ± 4 vs. 5 ± 4 mmHg; <i>P</i> = 0.1), coincident with minimal reduction in ICP (15 ± 3 vs. 14 ± 4 mmHg; <i>P =</i>0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.

The effect of microvascular obstruction on the myocardial microstructure: a diffusion tensor imaging study

2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
A Das ◽  
K Kelly ◽  
M Aldred ◽  
I Teh ◽  
CK Stoeck ◽  
...  
Keyword(s):  
Microvascular Obstruction ◽  
Diffusion Tensor ◽  
Spin Echo ◽  
Mean Diffusivity ◽  
Imaging Study ◽  
Free Breathing ◽  
Helix Angle ◽  
Acquisition Time ◽  
Heart Research

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Heart Research UK Background Diffusion tensor cardiac magnetic resonance (DT-CMR) imaging allows for characterising myocardial microstructure in-vivo using mean diffusivity (MD), fractional anisotropy (FA), secondary eigenvector angle (E2A) and helix angle (HA) maps. Following myocardial infarction (MI), alterations in MD, FA and HA proportions have previously been reported. E2A depicts the contractile state of myocardial sheetlets, however the behaviour of E2A in infarct segments, and all DTI markers in areas of microvascular obstruction (MVO) is also not fully understood.  Purpose We performed spin echo DTI in patients following ST-elevation MI (STEMI) in order to investigate acute changes in DTI parameters in remote and infarct segments both with and without MVO. Method Twenty STEMI patients (16 men, 4 women, mean age 59) had acute (5 ± 2d) 3T CMR scans. CMR protocol included: second order motion compensated (M012) free-breathing spin echo DTI (3 slices, 18 diffusion directions at b-values 100s/mm2[3], 200s/mm2[3] and 500s/mm2[12], reconstructed resolution was 1.66x1.66x8mm); cine and late gadolinium enhancement (LGE) imaging. Average MD, FA, E2A HA parameters were calculated on a  16 AHA segmental level. HA maps were described by dividing values into left-handed HA (LHM, -90° &lt; HA &lt; -30°), circumferential HA (CM, -30° &lt; HA &lt; 30°), and right-handed HA (RHM, 30° &lt; HA &lt; 90°) and reported as relative proportions. Segments were defined as infarct (positive for LGE) and remote (opposite to the infarct).  Results DTI acquisition was successful in all patients (acquisition time 13 ± 5mins). Ten patients had evidence of MVO on LGE images. MD was significantly higher in infarct regions in comparison to remote; MVO-ve infarct segments had significantly higher MD than MVO + ve infarct segments (MD remote= 1.46 ± 0.12x10-3mm2/s, MD MVO + ve = 1.59 ± 0.12x10-3mm2/s, MD MVO-ve  = 1.75 ± 0.12x10-3mm2/s, ANOVA p &lt; 0.01). FA was reduced in infarct segments in comparison to remote; MVO-ve infarct segments had significantly lower FA than MVO + ve infarct segments (FAremote= 0.37 ± 0.02, FA MVO + ve = 0.31 ± 0.02 x 10-3mm2/s, MD MVO-ve =0.25 ± 0.02, ANOVA p &lt; 0.01). E2A values were significantly lower in infarct segments compared to remote; MVO + ve infarct segments had significantly lower values than MVO-ve. (E2A remote= 57.4 ± 5.2°, E2A MVO-ve = 46.8 ± 2.5°, E2A MVO + ve = 36.8 ± 3.1°, ANOVA p &lt; 0.001). RHM% (corresponding to subendocardium) was significantly lower in infarct segments compared to remote; MVO + ve infarct segments had significantly lower RHM% than MVO-ve. (RHM remote= 37 ± 3%, RHM RHM MVO-ve= 28 ± 7%, MVO + ve= 8 ± 5%, ANOVA p &lt; 0.001). Conclusion The presence of MVO results in a decrease in MD and increase in FA in comparison to surrounding infarct segments. However, the reduction in E2A and right-handed myocytes on HA in infarct segments is further exacerbated by the presence of MVO. Further study is required to investigate the underlying mechanisms for such alterations in signal intensity. Abstract Figure. A case of transmural septal MI with MVO

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