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MRI vs US for shoulder imaging
S20
Ultrasound in Medicine & Biology
Despite technical challenges, point-of-care bowel ultrasound has the added ability to measure bowel wall thickness, provide real-time evaluation of bowel peristalsis, perfusion, detection of free abdominal fluid; in addition to detection of pneumatosis intestinalis, portal venous gas and pneumoperitoneum like plain abdominal radiographs. This provides a more complete understanding of bowel state. Specific color doppler bowel wall arterial flow patterns have been described in necrotising enterocolitis, as “zebra”, “Y” and the “ring” patterns corresponding to inflamed viable bowel. Bowel ultrasound is more sensitive than abdominal radiography in the detection of pneumotosis intestinalis in early stages of necrotising enterocolitis. As the disease progresses, the visualization of thinned bowel wall with lack of bowel wall perfusion on ultrasound implies nonviable bowel with impending perforation. Detection of this bowel state early is valuable in the clinical management as pneumoperitoneum suggesting bowel perforation on plain abdominal radiograph is a late sign. Rarer diagnoses with acute neonatal surgical conditions can also be assessed with the use of bowel ultrasound such as malrotation. With widening of knowledge and appropriate training in ultrasound techniques, neonatologists will be able to enhance their diagnostic acumen by performing point-of-care bowel ultrasound in addition to plain radiography for a broad array of diseased bowel states in neonates.
SESSION 3H: HISTORY, MYSTERY & THE PRESENT From coloured stars to colour flow imaging or when is ‘Doppler’ not Doppler? David H. Evans Department of Cardiovascular Sciences, University of Leicester, United Kingdom In 1842 Christian Doppler wrote a paper entitled ‘On the Coloured Light of the Double Stars’ in which he sort to explain why some stars appear bluish and some reddish. His theory was that when a star is approaching an observer the wavelength of its light will be shorter and the star thus appears to be blue, whilst when a star is receding from an observer the wavelengths of its light will be longer and it would appear to be red. Doppler was actually wrong on a number of counts as to the explanation for the colour of stars (as will be explained during the talk) although his theory was correct. It is therefore perhaps slightly ironic that Doppler’s theory is now widely used in astronomy to measure the speed with which stars are receding from the earth. Doppler’s theory was challenged by the young Dutch scientist Christophorus Buys-Ballot, who believed that Doppler’s theory could not explain the colours of double stars and set out to prove experimentally, using sound rather that light, that the Doppler effect did not exist. He carried out a number of experiments involving horn players travelling on the Amsterdam-Utrecht railway line, but instead of disproving the Doppler effect, showed that Doppler’s theory was correct. The possibility of using the Doppler effect for measuring blood flow was introduced by Shigeo Satomura and colleagues in a number of papers published between 1955 and 1960, and a major advance took place around 1969 when Peter Wells, Pierre Peronneau, and Donald Baker independently described Pulsed ‘Doppler’ units which enabled blood flow signals from specific ranges to be acquired. Further important advances took place around 1982 when Kasai and Namekawa introduced real-time blood flow imaging. Curiously enough, however, whilst continuous wave Doppler units rely on the Doppler shift on the back-scattered ultrasound to measure blood flow velocity, instruments which use pulsed waves do not (and could not for reasons that will once again be explained during the talk) measure the Doppler shift on individual pulses, but rather measure the relative phase-shifts of returning signals with respect to a master oscillator in each inter-pulse interval. Fortunately for most practical purposes the resulting signal is equivalent to a Doppler shift signal.
Volume 45, Number S1, 2019 In summary, this talk will explain why the apparent colour of stars could not be due to the Doppler effect, and why pulsed ‘Doppler’ devices cannot detect Doppler frequency shifts.
Addition of reliability measurement index to point shear wave elastography: Prospective validation via diagnostic performance and reproducibility Hyo-Jin Kang, Jae Young Lee, Ljin Joo, Joon Koo Han Seoul National University Hospital, Jongno, Seoul, South Korea Introduction: To investigate the clinical value of the reliability measurement index (RMI), which is here newly added to point shear wave elastography (pSWE) in assessing liver stiffness. Methods: Forty-nine patients were prospectively enrolled in this IRB approval study and underwent both pSWE providing RMI (range, 0.0_1.0) and transient elastography (TE) prior to hepatic surgery. Liver stiffness (LS) measurements were repeated until 10 LS values with RMI_0.7 were obtained by each of two radiologists. Interclass correlation coefficients (ICCs) between the median of the first two to nine measurements (as determined by RMI values of _0.0 [LS-RMI 0.0], _0.4 [LS-RMI 0.4] and _0.7 [LS-RMI 0.7]) and that of a consecutive 10 measurements (LS-REF) were obtained. Minimum number of measurements to attain ICC_0.95 and high interobserver agreement (ICC_0.90) were determined for each RMI cutoffs. Diagnostic performance of reduced number of LS measurement for identifying liver fibrosis and correlation coefficients between LS measurements and the TE, METAVIR and necroinflammatory activity were calculated. Results: Upon comparison with LS-REF, a minimum of seven LSRMI 0.0, five LS-RMI 0.4, and three LS-RMI 0.7 measurements were required to obtain ICC_0.95 with a high interobserver agreement (ICC_0.90). Diagnostic performance for differentiating liver fibrosis did not differ (all Ps>0.05) using these reduced number of LS measurements. Significant correlations were found between the medians of these reduced number of LS measurements and TE (all Ps<0.001) and METAVIR (all Ps<0.001) scores. Conclusion: RMI helped to improve reliability and reduce the number of LS measurements while maintaining the diagnostic performance of pSWE. SESSION 5A: MSK & RHEUMATOLOGY MRI vs US for shoulder imaging Sebastian Fung Radiologist, St Vincent’s Clinic Medical Imaging and Mater Imaging, Sydney, NSW, Australia Imaging of common shoulder pathology is often performed with either ultrasound or MRI. In this presentation, we will explore the relative strengths and weaknesses of each imaging modality via various typical clinical vignettes, and discuss the appropriateness of ultrasound and MRI in these everyday scenarios. Imaging the post operative cuff Simran Singh Radiologist, I-Med Radiology, Melbourne, VIC, Australia Imaging of the post-operative cuff can be a very challenging task given the variable appearance of the rotator cuff following surgery. Ultrasound is an important tool for assessment particularly given the dynamic nature of the modality. This presentation will focus on techniques to accurately assess the post-operative cuff, normal post-surgical appearances and complications of surgery.
Ultrasound in Medicine & Biology
Despite technical challenges, point-of-care bowel ultrasound has the added ability to measure bowel wall thickness, provide real-time evaluation of bowel peristalsis, perfusion, detection of free abdominal fluid; in addition to detection of pneumatosis intestinalis, portal venous gas and pneumoperitoneum like plain abdominal radiographs. This provides a more complete understanding of bowel state. Specific color doppler bowel wall arterial flow patterns have been described in necrotising enterocolitis, as “zebra”, “Y” and the “ring” patterns corresponding to inflamed viable bowel. Bowel ultrasound is more sensitive than abdominal radiography in the detection of pneumotosis intestinalis in early stages of necrotising enterocolitis. As the disease progresses, the visualization of thinned bowel wall with lack of bowel wall perfusion on ultrasound implies nonviable bowel with impending perforation. Detection of this bowel state early is valuable in the clinical management as pneumoperitoneum suggesting bowel perforation on plain abdominal radiograph is a late sign. Rarer diagnoses with acute neonatal surgical conditions can also be assessed with the use of bowel ultrasound such as malrotation. With widening of knowledge and appropriate training in ultrasound techniques, neonatologists will be able to enhance their diagnostic acumen by performing point-of-care bowel ultrasound in addition to plain radiography for a broad array of diseased bowel states in neonates.
SESSION 3H: HISTORY, MYSTERY & THE PRESENT From coloured stars to colour flow imaging or when is ‘Doppler’ not Doppler? David H. Evans Department of Cardiovascular Sciences, University of Leicester, United Kingdom In 1842 Christian Doppler wrote a paper entitled ‘On the Coloured Light of the Double Stars’ in which he sort to explain why some stars appear bluish and some reddish. His theory was that when a star is approaching an observer the wavelength of its light will be shorter and the star thus appears to be blue, whilst when a star is receding from an observer the wavelengths of its light will be longer and it would appear to be red. Doppler was actually wrong on a number of counts as to the explanation for the colour of stars (as will be explained during the talk) although his theory was correct. It is therefore perhaps slightly ironic that Doppler’s theory is now widely used in astronomy to measure the speed with which stars are receding from the earth. Doppler’s theory was challenged by the young Dutch scientist Christophorus Buys-Ballot, who believed that Doppler’s theory could not explain the colours of double stars and set out to prove experimentally, using sound rather that light, that the Doppler effect did not exist. He carried out a number of experiments involving horn players travelling on the Amsterdam-Utrecht railway line, but instead of disproving the Doppler effect, showed that Doppler’s theory was correct. The possibility of using the Doppler effect for measuring blood flow was introduced by Shigeo Satomura and colleagues in a number of papers published between 1955 and 1960, and a major advance took place around 1969 when Peter Wells, Pierre Peronneau, and Donald Baker independently described Pulsed ‘Doppler’ units which enabled blood flow signals from specific ranges to be acquired. Further important advances took place around 1982 when Kasai and Namekawa introduced real-time blood flow imaging. Curiously enough, however, whilst continuous wave Doppler units rely on the Doppler shift on the back-scattered ultrasound to measure blood flow velocity, instruments which use pulsed waves do not (and could not for reasons that will once again be explained during the talk) measure the Doppler shift on individual pulses, but rather measure the relative phase-shifts of returning signals with respect to a master oscillator in each inter-pulse interval. Fortunately for most practical purposes the resulting signal is equivalent to a Doppler shift signal.
Volume 45, Number S1, 2019 In summary, this talk will explain why the apparent colour of stars could not be due to the Doppler effect, and why pulsed ‘Doppler’ devices cannot detect Doppler frequency shifts.
Addition of reliability measurement index to point shear wave elastography: Prospective validation via diagnostic performance and reproducibility Hyo-Jin Kang, Jae Young Lee, Ljin Joo, Joon Koo Han Seoul National University Hospital, Jongno, Seoul, South Korea Introduction: To investigate the clinical value of the reliability measurement index (RMI), which is here newly added to point shear wave elastography (pSWE) in assessing liver stiffness. Methods: Forty-nine patients were prospectively enrolled in this IRB approval study and underwent both pSWE providing RMI (range, 0.0_1.0) and transient elastography (TE) prior to hepatic surgery. Liver stiffness (LS) measurements were repeated until 10 LS values with RMI_0.7 were obtained by each of two radiologists. Interclass correlation coefficients (ICCs) between the median of the first two to nine measurements (as determined by RMI values of _0.0 [LS-RMI 0.0], _0.4 [LS-RMI 0.4] and _0.7 [LS-RMI 0.7]) and that of a consecutive 10 measurements (LS-REF) were obtained. Minimum number of measurements to attain ICC_0.95 and high interobserver agreement (ICC_0.90) were determined for each RMI cutoffs. Diagnostic performance of reduced number of LS measurement for identifying liver fibrosis and correlation coefficients between LS measurements and the TE, METAVIR and necroinflammatory activity were calculated. Results: Upon comparison with LS-REF, a minimum of seven LSRMI 0.0, five LS-RMI 0.4, and three LS-RMI 0.7 measurements were required to obtain ICC_0.95 with a high interobserver agreement (ICC_0.90). Diagnostic performance for differentiating liver fibrosis did not differ (all Ps>0.05) using these reduced number of LS measurements. Significant correlations were found between the medians of these reduced number of LS measurements and TE (all Ps<0.001) and METAVIR (all Ps<0.001) scores. Conclusion: RMI helped to improve reliability and reduce the number of LS measurements while maintaining the diagnostic performance of pSWE. SESSION 5A: MSK & RHEUMATOLOGY MRI vs US for shoulder imaging Sebastian Fung Radiologist, St Vincent’s Clinic Medical Imaging and Mater Imaging, Sydney, NSW, Australia Imaging of common shoulder pathology is often performed with either ultrasound or MRI. In this presentation, we will explore the relative strengths and weaknesses of each imaging modality via various typical clinical vignettes, and discuss the appropriateness of ultrasound and MRI in these everyday scenarios. Imaging the post operative cuff Simran Singh Radiologist, I-Med Radiology, Melbourne, VIC, Australia Imaging of the post-operative cuff can be a very challenging task given the variable appearance of the rotator cuff following surgery. Ultrasound is an important tool for assessment particularly given the dynamic nature of the modality. This presentation will focus on techniques to accurately assess the post-operative cuff, normal post-surgical appearances and complications of surgery.