Home Feasibility of Respiratory-gated High-pitch Spiral CT
Post
Cancel

Feasibility of Respiratory-gated High-pitch Spiral CT

Posted Mar 31, 2016 Updated Apr 10, 2023
By Michael M. Lell MD , Michael Scharf MD , Achim Eller MD , Wolfgang Wuest MD , Thomas Allmendinger PhD , Florian Fuchs MD , Stephan Achenbach MD , Michael Uder MD , Matthias S. May MD
7 min read

Rationale and Objectives

This study aimed to develop and implement a respiratory-gated setup for dual-source computed tomography (CT) at high pitch to examine patients in a reproducible inspiratory phase.

Materials and Methods

Twenty-one patients underwent free-breathing respiratory-gated chest CT using a high-pitch scan mode no more than 6 months after inspiratory breath-held nongated CT, which serves as reference. Scan parameters were as follows: pitch = 3.4, 128 × 0.6 mm collimation, 0.28 s gantry rotation time, and 150 ref.mAs per tube at 120 kV. The examinations were triggered using the tidal wave provided by a respiratory-gating system as input signal. Image quality was assessed focusing on artifacts and delineation of the anatomical and pathological structures. Lung volumes were measured on both free-breathing and reference examinations.

Results

All examinations were performed without complications. Image quality was high with both protocols. Significantly less motion artifacts were recorded with the high-pitch mode compared to the reference ( P = 0.02). Most of the artifacts were located in the peripheral parts of the lower lobes for the study group and in the central part of the left lower lobe for the reference. Average total lung volume was 4.5 ± 1.5 L in respiratory-gated examinations and 5.8 ± 0.9 L in examinations with breath-hold in inspiration.

Conclusions

High-pitch chest CT scanning during free breathing minimizes motion artifacts, improving image quality in patients with limited breath-holding abilities. To assure scanning in an inspiratory phase, data acquisition should be triggered with a respiratory-gating system.

Introduction

Computed tomography (CT) has an important role to play in thoracic imaging . Isotropic imaging of the chest is possible with modern multislice spiral CT systems in less than 10 s, a breath-hold time that can be managed by the majority of patients. As a consequence of the shorter scan times, respiratory motion artifacts decreased and image quality improved significantly. Shorter CT rotation times also enabled higher temporal resolution and significantly reduced cardiac motion artifacts, which are not only known to alter the image quality near the heart, but also responsible for pulsation artifacts around the aorta and central pulmonary vessels .

However, there is a group of patients that cannot comply with breathing commands, for example ventilated patients, sedated patients, mentally impaired patients, or pediatric patients. Hence, image quality is commonly degraded from motion artifacts in these patient groups.

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Materials and Methods

Study Population

Get Radiology Tree app to read full this article<

CT Technique

Get Radiology Tree app to read full this article<

Figure 1, Experimental setting: Tidal wave signal, recorded by a load cell, was used as input signal to trigger the examination. (Color version of figure is available online).

Figure 2, Respiratory gating: Respiratory-gating curve ( gray curve ), as measured by the load cell, correlates well with the spirometric tidal volume ( black curve ). Evaluation of the preceding excursions during respiration ( shaded green ) determines the trigger point ( red dot ) needed for an examination ( shaded yellow ) in an inspiratory phase >80% of the tidal range. By this calculation, the table acceleration ( shaded blue ) can be started in advance of the image acquisition. A deep inspiration was performed at t = 20 s in this patient. (Color version of figure is available online.)

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Control Group and Image Evaluation

Get Radiology Tree app to read full this article<

Figure 3, Anatomical regions defined for the evaluation of image quality: LC, lingula central; LP, lingula peripheral; LUC, left upper lobe central; LUP, left upper lobe peripheral; MC, middle lobe central; MP, middle lobe peripheral; LLC, left lower lobe central; RLC, right lower lobe central; LLP, left lower lobe peripheral; RLP, right lower lobe peripheral; RUC, right upper lobe central; RUP, right upper lobe peripheral. (Color version of figure is available online).

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Estimation of Radiation Dose

Get Radiology Tree app to read full this article<

Statistical Analysis

Get Radiology Tree app to read full this article<

Results

Get Radiology Tree app to read full this article<

Conventional CT

Get Radiology Tree app to read full this article<

Figure 4, Male patient, age 68 years, body mass index (BMI) 22 kg/m 2 , staging and follow-up for melanoma: Image quality and delineation of the pathological findings was rated poor in the conventional mode because of the inability to breath-hold during the whole examination ( a ) and excellent with high-pitch mode and respiratory gating ( b ).

TABLE 1

Pathological Findings

Respiratory Gating Conventional Nodules 15 16 Consolidations 7 6 Masses 3 3 Interstitial lung disease 2 2 Ground glass opacities 7 9 Atelectasis 2 0

TABLE 2

Rating of Motion Artifacts in the Defined Anatomical Regions

Conventional 1 2 3 4 Excellent Good Moderate Poor RUC 17 4 — — RUP 18 3 — — MC 15 3 3 — MP 17 2 2 — RLC 14 5 2 — RLP 19 1 1 — LUC 16 5 — — LUP 18 3 — — LC 13 6 2 — LP 17 3 1 — LLC 5 12 4 — LLP 17 3 1 —

Respiratory Gating 1 2 3 4 Excellent Good Moderate Poor RUC 19 2 — — RUP 14 6 1 — MC 21 — — — MP 17 4 — — RLC 19 2 — — RLP 12 9 — — LUC 20 1 — — LUP 14 6 1 — LC 20 1 — — LP 15 6 — — LLC 17 4 — — LLP 11 9 1 —

LC, lingula central; LP, lingula peripheral; LUC, left upper lobe central; LUP, left upper lobe peripheral; MC, middle lobe central; MP, middle lobe peripheral; RLC, left lower lobe central; RLC, right lower lobe central; RLP, left lower lobe peripheral; RLP, right lower lobe peripheral; RUC, right upper lobe central; RUP, right upper lobe peripheral.

Get Radiology Tree app to read full this article<

High-pitch CT

Get Radiology Tree app to read full this article<

Figure 5, Female patient, age 55 years, body mass index (BMI) 30 kg/m 2 , follow-up staging for rectal cancer: Most artifacts with the conventional mode are in the central regions, like in this case adjacent to the border of the heart ( a , white arrows ). An additional slight cardiac pulsation artifact can be seen in the lung tissue along the left atrioventricular groove ( asterisk ). With the high-pitch mode, (HPM) motion artifacts, like blurred vessels and compacted lung tissue in this case, were mainly recorded in the peripheral, subpleural regions ( b , white arrows ).

Get Radiology Tree app to read full this article<

Discussion

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Figure 6, Male patient, age 69 years, body mass index (BMI) 32 kg/m 2 , follow-up examination for asbestosis. ( a ) Motion artifacts are predominantly located in the central areas of the lungs ( white arrows ) with the conventional mode. ( b ) High-pitch mode (HPM) and respiratory gating reduces both the respiratory motion artifacts and the cardiac pulsation artifacts ( asterisk ) in this patient.

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Acknowledgments

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

Get Radiology Tree app to read full this article<

References

  • 1. Mohammed T.L., Chowdhry A., Reddy G.P., et. al.: ACR Appropriateness Criteria® screening for pulmonary metastases. J Thorac Imaging 2011; 26: pp. W1-W3.

  • 2. Heitkamp D.E., Mohammed T.L., Kirsch J., et. al.: ACR appropriateness criteria(®)acute respiratory illness in immunocompromised patients. J Am Coll Radiol 2012; 9: pp. 164-169.

  • 3. Lurz M., Lell M.M., Wuest W., et. al.: Automated tube voltage selection in thoracoabdominal computed tomography at high pitch using a third-generation dual-source scanner: image quality and radiation dose performance. Invest Radiol 2015; 50: pp. 352-360.

  • 4. Petersilka M., Bruder H., Krauss B., et. al.: Technical principles of dual source CT. Eur J Radiol 2008; 68: pp. 362-368.

  • 5. Achenbach S., Marwan M., Ropers D., et. al.: Coronary computed tomography angiography with a consistent dose below 1 mSv using prospectively electrocardiogram-triggered high-pitch spiral acquisition. Eur Heart J 2010; 31: pp. 340-346.

  • 6. Lell M., Marwan M., Schepis T., et. al.: Prospectively ECG-triggered high-pitch spiral acquisition for coronary CT angiography using dual source CT: technique and initial experience. Eur Radiol 2009; 19: pp. 2576-2583.

  • 7. Lell M., Hinkmann F., Anders K., et. al.: High-pitch electrocardiogram-triggered computed tomography of the chest: initial results. Invest Radiol 2009; 44: pp. 728-733.

  • 8. Tacelli N., Remy-Jardin M., Flohr T., et. al.: Dual-source chest CT angiography with high temporal resolution and high pitch modes: evaluation of image quality in 140 patients. Eur Radiol 2010; 20: pp. 1188-1196.

  • 9. Baumueller S., Alkadhi H., Stolzmann P., et. al.: Computed tomography of the lung in the high-pitch mode: is breath holding still required?. Invest Radiol 2011; 46: pp. 240-245.

  • 10. Lell M.M., May M., Deak P., et. al.: High-pitch spiral computed tomography: effect on image quality and radiation dose in pediatric chest computed tomography. Invest Radiol 2011; 46: pp. 116-123.

  • 11. Mortimer A.M., Singh R.K., Hughes J., et. al.: Use of expiratory CT pulmonary angiography to reduce inspiration and breath-hold associated artefact: contrast dynamics and implications for scan protocol. Clin Radiol 2011; 66: pp. 1159-1166.

  • 12. Shrimpton P.C., Hillier M.C., Lewis M.A., et. al.: National survey of doses from CT in the UK: 2003. Br J Radiol 2006; 79: pp. 968-980.

  • 13. Landis J.R., Koch G.G.: The measurement of observer agreement for categorical data. Biometrics 1977; 33: pp. 159-174.

  • 14. Hausleiter J., Bischoff B., Hein F., et. al.: Feasibility of dual-source cardiac CT angiography with high-pitch scan protocols. J Cardiovasc Comput Tomogr 2009; 3: pp. 236-242.

  • 15. Leschka S., Stolzmann P., Desbiolles L., et. al.: Diagnostic accuracy of high-pitch dual-source CT for the assessment of coronary stenoses: first experience. Eur Radiol 2009; 19: pp. 2896-2903.

  • 16. Amacker N.A., Mader C., Alkadhi H., et. al.: Routine chest and abdominal high-pitch CT: an alternative low dose protocol with preserved image quality. Eur J Radiol 2012; 81: pp. e392-e397.

  • 17. Achenbach S., Marwan M., Schepis T., et. al.: High-pitch spiral acquisition: a new scan mode for coronary CT angiography. J Cardiovasc Comput Tomogr 2009; 3: pp. 117-121.

  • 18. Bischoff B., Meinel F.G., Del Prete A., et. al.: High-pitch coronary CT angiography in dual-source CT during free breathing vs. breath holding in patients with low heart rates. Eur J Radiol 2013; 82: pp. 2217-2221.

Academic Radiology, Volume 23, Issue 4
Journals General Radiology
This post is licensed under CC BY 4.0 by the author.
Recently Updated
Contents