title: Comparative study of linear and curvilinear ultrasound probes to assess quadriceps rectus femoris muscle mass in healthy subjects and in patients with chronic respiratory disease.
abstract: BACKGROUND
  Ultrasound measurements of rectus femoris cross-sectional area (RFCSA) are clinically useful measurements in chronic obstructive pulmonary disease (COPD) and critically ill patients. Technical considerations as to the type of probe used, which affects image resolution, have limited widespread clinical application. We hypothesised that measurement of RFCSA would be similar with linear and curvilinear probes.
  
  
  METHODS
  Four studies were performed to compare the use of the curvilinear probe in measuring RFCSA. Study 1 investigated agreement of RFCSA measurements using linear and curvilinear probes in healthy subjects, and in patients with chronic respiratory disease. Study 2 investigated the intra-rater and inter-rater agreement using the curvilinear probe. Study 3 investigated the agreement of RFCSA measured from whole and spliced images using the linear probe. Study 4 investigated the applicability of ultrasound in measuring RFCSA during the acute and recovery phases of an exacerbation of COPD.
  
  
  RESULTS
  Study 1 showed demonstrated no difference in the measurement of RFCSA using the curvilinear and linear probes (308±104 mm(2) vs 320±117 mm(2), p=0.80; intraclass correlation coefficient (ICC)>0.97). Study 2 demonstrated high intra-rater and inter-rater reliability of RFCSA measurement with ICC>0.95 for both. Study 3 showed that the spliced image from the linear probe was similar to the whole image RFCSA (308±103.5 vs 263±147 mm(2), p=0.34; ICC>0.98). Study 4 confirmed the clinical acceptability of using the curvilinear probe during an exacerbation of COPD. There were relationships observed between admission RFCSA and body mass index (r=+0.65, p=0.018), and between RFCSA at admission and physical activity levels at 4 weeks post-hospital discharge (r=+0.75, p=0.006).
  
  
  CONCLUSIONS
  These studies have demonstrated that clinicians can employ whole and spliced images from the linear probe or use images from the curvilinear probe, to measure RFCSA. This will extend the clinical applicability of ultrasound in the measurement of muscle mass in all patient groups.
authors.affiliation: Lane Fox Clinical Respiratory Physiology Research Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK; Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Mandal
authors.affiliation: Lane Fox Clinical Respiratory Physiology Research Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK; Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: E
authors.initials: E
authors.lastname: Suh
authors.affiliation: Lane Fox Clinical Respiratory Physiology Research Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK; Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Thompson
authors.affiliation: Lane Fox Clinical Respiratory Physiology Research Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK; Division of Asthma, Allergy and Lung Biology, King's College London, London, UK; Guy's and St Thomas' NHS Foundation Trust and King's College London, National Institute of Health Research Comprehensive Biomedical Research Centre, London, UK.
authors.forename: B
authors.initials: B
authors.lastname: Connolly
authors.affiliation: Lane Fox Clinical Respiratory Physiology Research Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK; Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Ramsay
authors.affiliation: Lane Fox Clinical Respiratory Physiology Research Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust , London , UK.
authors.forename: R
authors.initials: R
authors.lastname: Harding
authors.affiliation: Division of Respiratory and Critical Care Medicine , University Medicine Cluster, National University Health Systems , Singapore.
authors.forename: Z
authors.initials: Z
authors.lastname: Puthucheary
authors.affiliation: Guy's and St Thomas' NHS Foundation Trust and King's College London, National Institute of Health Research Comprehensive Biomedical Research Centre , London , UK.
authors.forename: J
authors.initials: J
authors.lastname: Moxham
authors.affiliation: Lane Fox Clinical Respiratory Physiology Research Centre, St Thomas' Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK; Division of Asthma, Allergy and Lung Biology, King's College London, London, UK; Guy's and St Thomas' NHS Foundation Trust and King's College London, National Institute of Health Research Comprehensive Biomedical Research Centre, London, UK.
authors.forename: N
authors.initials: N
authors.lastname: Hart
keywords: COPD Exacerbations; Imaging/CT MRI etc; Respiratory Muscles
references.citation: Am J Respir Crit Care Med. 2015 Oct 1;192(7):810-6
references.pmid: 26068143
references.citation: BMJ. 2014 Jul 08;349:g4315
references.pmid: 25004917
references.citation: Clin Biomech (Bristol, Avon). 2004 May;19(4):337-42
references.pmid: 15109752
references.citation: Reprod Health. 2008 Oct 15;5:5
references.pmid: 18922175
references.citation: Respir Res. 2012 Dec 28;13:119
references.pmid: 23273255
references.citation: Eur Respir J. 1997 Jan;10 (1):59-64
references.pmid: 9032493
references.citation: J Med Eng Technol. 2008 Nov-Dec;32(6):498-504
references.pmid: 19005964
references.citation: Thorax. 2008 Aug;63(8):683-9
references.pmid: 18487318
references.citation: Eur Respir J. 2015 Oct;46(4):988-1000
references.pmid: 26022965
references.citation: Eur Respir J. 2013 Nov;42(5):1205-15
references.pmid: 23397303
references.citation: Clin Rehabil. 2012 Oct;26(10 ):934-44
references.pmid: 22324054
references.citation: Crit Care Med. 2015 Apr;43(4):897-905
references.pmid: 25559437
references.citation: Man Ther. 2012 Apr;17 (2):187-91
references.pmid: 21813312
references.citation: Thorax. 2009 May;64(5):418-23
references.pmid: 19158125
references.citation: Physiother Res Int. 1996;1(2):112-26
references.pmid: 9238728
references.citation: Ultrasound Med Biol. 2009 Nov;35(11):1803-11
references.pmid: 19699027
references.citation: JAMA. 2013 Oct 16;310(15):1591-600
references.pmid: 24108501
references.citation: Eur Respir J. 2012 Nov;40(5):1115-22
references.pmid: 22362854
references.citation: BMJ. 2014 Jul 08;349:g4370
references.pmid: 25005041
references.citation: Crit Care. 2009;13(5):R161
references.pmid: 19814793
references.citation: Ultrasound Med Biol. 2013 May;39(5):791-6
references.pmid: 23465140
references.citation: J Rehabil Res Dev. 2014;51(7):1155-64
references.pmid: 25437305
references.citation: Eur J Appl Physiol. 2004 Jan;91(1):116-8
references.pmid: 14639480
references.citation: PLoS One. 2012;7(6):e39198
references.pmid: 22745715