How to Determine the Patient’s Head and Neck Posture during Computed Tomography Scanning?

Hu, Xiaoying; Xu, Jintao; Fang, Dong

doi:10.1164/rccm.201805-0977le

Cited by 2 publications

(2 citation statements)

References 4 publications

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“…Errors in this research might occur in any of the following 4 steps of the overall process: a) CBCT scan, b) the model reorientation, c) the voxel-based superimposition, and d) landmark registration. CBCT scans, typically, are commonly taken with different head position [ 17 ], which may lead to inter-observer difference during scan approximation. Therefore, it is preferable to standardize the head position at the time of the scan.…”

Section: Discussionmentioning

confidence: 99%

Reliability and reproducibility of CBCT assessment of mandibular changes before and after treatment for Class III growing patients – an easy and quick way for evaluation

Hu,

Cheung,

Zhang

et al. 2023

BMC Pediatr

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The objective of this study was to evaluate intraobserver reliability and inter-observer reproducibility of a 3-dimensional (3D) assessment method for mandibular changes of growing patients after orthodontic treatment for Class III malocclusion.Methods Cone-beam computed tomography (CBCT) scans were performed before and after orthodontic treatment for 27 patients. During the scan, the patient was positioned such that his/her mandibular plane was parallel to floor. Three observers independently worked on the DICOM data, reconstructed the pre- and post-treatment 3D models in software, selected the stable anatomical structures (basal bone area from the lingual surface of the symphysis to the distal aspect of the first molars) to guide the automated superimposition process. Then, each observer registered 14 anatomical landmarks on the virtual models, for three times after suitable interval, to generate 3 sets of coordinates; the mean was taken as the coordinates for that particular landmark. The intraobserver reliability and inter-observer reproducibility of the method were analyzed.Results The ICCs was > 0.90 for 25 (92.6%) of the intraobserver assessments. The precision of the measurement method was < 0.3 mm in 24 (88.9%) cases. The interobserver reproducibility errors were < 0.3 mm in 21 of the 27 cases.Conclusions The intraobserver reliability and inter-observer reproducibility of 3D assessment of mandibular changes using the virtual models were excellent.

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Section: Discussionmentioning

confidence: 99%

Reliability and reproducibility of CBCT assessment of mandibular changes before and after treatment for Class III growing patients – an easy and quick way for evaluation

Hu,

Cheung,

Zhang

et al. 2023

BMC Pediatr

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“…In addition to the standard lung function testing in the upright sitting posture as part of their clinical management, participants were asked to perform three MBW tests in the upright and supine body posture, in that sequence, and with the subject remaining in the same body posture in between MBW. The supine MBW tests were performed with a headrest comparable to the one used during CT scanning (15), and 1-L targeting was done by coaching from the lung function technician. The technician then accompanied the patient to the CT scanner to guide breathing pattern during the CT scans via the intercom, ensuring that total lung capacity was reached for the TLC image and that the subject exhaled normally for the FRC image (12).…”

Section: Methodsmentioning

confidence: 99%

Ventilation heterogeneity in smokers: role of unequal lung expansion and peripheral lung structure

Verbanck

Polfliet

Schuermans

et al. 2020

Journal of Applied Physiology

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Smoking-induced ventilation heterogeneity measured at the mouth via established washout indices (lung clearance index LCI and alveolar mixing efficiency AME) potentially results from unequal expansion, which can be quantified by CT, and structural changes down to the lung periphery, characterized by CT parametric response mapping indices (PRMfSAD,PRMEmph). By combining CT imaging and N2 washout tests in smokers, we specifically examined the roles of unequal lung expansion and of peripheral structure. We first extracted 3D maps of local lung expansion from registered inspiratory/expiratory CT images in 50 smokers (GOLD 0-IV) to compute for each smoker, the theoretical N2 washout concentration curve solely attributable to unequal local expansion. By a head-on comparison with washout N2 concentrations measured at the mouth in the same smokers supine, we observed that (a) LCI increased from 4.8+0.2(SD) to 6.6+0.8(SD) due to unequal lung expansion alone, and further increased to 9.0+1.5(SD) independent of local expansion, (b) AME decreased (from 100% by definition) to 95+2(SD)% due to unequal expansion alone, and further decreased to 75+7(SD)% independent of local expansion. In a multiple regression between the washout indices and CT derived PRMfSAD and PRMEmph, LCI was related to PRMfSAD (r=+0.58; P<0.001) while AME was related to both PRMfSAD (rpartial=-0.44; P=0.002) and PRMEmph (rpartial=-0.31;P=0.033), in line with AME being dominated by alterations in peripheral structure. We conclude that smokers showing an increased LCI without corresponding AME decrease are predominantly affected by unequal lung expansion, whereas an AME decrease with a commensurate LCI increase indicates a smoking-induced alteration of peripheral structure.

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How to Determine the Patient’s Head and Neck Posture during Computed Tomography Scanning?

Cited by 2 publications

References 4 publications

Reliability and reproducibility of CBCT assessment of mandibular changes before and after treatment for Class III growing patients – an easy and quick way for evaluation

Reliability and reproducibility of CBCT assessment of mandibular changes before and after treatment for Class III growing patients – an easy and quick way for evaluation

Ventilation heterogeneity in smokers: role of unequal lung expansion and peripheral lung structure

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