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Necrotising enterocolitis and point of care neonatal abdominal USS
Abstracts The sophistication of echocardiographic techniques continues to evolve but the wise physician will be cognizant of other noninvasive imaging modalities in an effort to further optimize patient management.
SESSION 3C: VASCULAR Dual frequency contrast ultrasound angiography F. Stuart Foster,1 Christine E.M. Demore,1 Emmanuel Cherin,1 Isabel Newsome,3 Claudia Carnevale,2 Paul A. Dayton3 1 Sunnybrook Research Institute and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, 2 Fuji Film Visual Sonics Inc, Toronto, ON, Canada,, 3 Joint Graduate Department of Biomedical Engineering, University of North Carolina and North Carolina State University, NC, USA Acoustic angiography is a contrast imaging approach in which the superharmonics associated with low frequency excitation of microbubbles are received and processed over a broad bandwidth at a much higher frequency. As demonstrated by Dayton and colleagues, this technique facilitates the visualization of the microvasculature with a resolution typical of micro computed tomography and with superior contrast-to tissue-ratios than conventional nonlinear processing. To date dual frequency contrast imaging has been performed with a 2- 4 MHz annulus coaligned with 25-30MHz single element focused transducer operated by a Vevo770 (Visualsonics) scanner. This technology has limitations (mechanical scanning, single focus, limited focal depth) which hinder its clinical use but which could be alleviated using dualfrequency arrays (DFA). In this presentation we first describe the performance and applications of mechanical acoustic angiography and early results from the development of dual frequency array devices for acoustic angiography. The logical extension to array based designs is then explored. We built prototype dual frequency devices in both a vertical and horizonal topology. The horizonal topography consisted of a central 256 element high frequency array (HF, 20 MHz) flanked by two single element low frequency transducers(LF, 2 MHz) that extended for the length of the HF array. The vertical topography consisted of a 32-element LF transmitter array positioned behind a 256-element HF receiver array. Both arrays were built from piezoelectric composites. The HF backing material, between the two piezoelectric layers in the vertical design is weakly and highly attenuating at 2 MHz and 20 MHz, respectively. Two matching layers on the LF array and 4 matching layers on the HF array were used to improve transmission throughout the whole array structure. An elevation lens was added to focus the receive component at around 9 mm. Impedance and hydrophone measurements were performed to evaluate both configurations. Examples of super harmonic contrast imaging for each of the above configurations will be shown for phantom studies and preliminary in vivo images of animal models will be presented.
SESSION 3E: GYNAECOLOGY What are IOTA easy descriptors and simple rules: How to use them Wouter Froyman Consultant Gynaecologist, University Hospitals Leuven, Leuven, Belgium Many adnexal lesions (e.g. dermoid cysts, endometriomas) share typical characteristics which make them easy to identify ‘at a glance’, without needing to apply diagnostic rules or perform risk calculations. Based on this knowledge, the IOTA group proposed four Easy
S19
Descriptors describing typical features of common benign lesions, and two Easy Descriptors suggestive of malignancy. Lesions that cannot be classified using the Easy Descriptors, can be assessed using other methods such as the Simple Rules. The Simple Rules are based on 5 ultrasound features suggesting a benign lesion (Bfeatures) and 5 features that suggest a malignant lesion (M-features). If at least one of the B-features is present without any M-feature, the lesion is classified as benign. Vice versa, if at least one M-feature is present without any B-feature, the lesion is classified as malignant. If both B and M-features are present, or no features are present, the lesion is not classifiable. The IOTA Simple Rules have become very popular because they are easy to use, and do not require a computer for calculation. In 2011, The Royal College of Obstetricians and Gynaecologists (RCOG) incorporated the Simple Rules in the Green-top Guideline on how to manage premenopausal women with adnexal masses. This was followed in 2016 by the American College of Obstetrician and Gynecologists (ACOG) integrating the Simple Rules into their clinical guideline on the evaluation and management of adnexal masses. In 2017, the Simple Rules were considered as the main diagnostic strategy for the assessment of adnexal masses in a first international consensus report.
SESSION 3G: GENERAL NEONATAL Posterior fossa and cerebellar haemorrhages. Imaging technique and long term outcome Adam Hoellering Neonatologist, Queensland Health, Brisbane, QLD, Australia This presentation gives an approach to image acquisition for the structures of the posterior cranial fossa. There will be an overview of the common structural abnormalities and a focus on cerebellar haemorrhages and infarction. Attention will be paid to the importance of the detection of these lesions and the growing body of evidence regarding their impact on long term neurodevelopmental outcomes.
Necrotising enterocolitis and point of care neonatal abdominal USS Archana Priyadarshi Neonatal Clinician and PHD Student, Westmead Hospital, Westmead, NSW, Australia Neonatal intensive care has seen dramatic improvements over last four decades in rates of survival for most preterm newborns. Limits of survival were generally regarded 27 weeks gestation in the 80’s, are now 23 weeks gestation. These micro-premies are much smaller (500 to 800 grams birth weight) and are now increasingly managed with nasal continuous positive airway pressure as respiratory support. Acute abdominal emergencies are common in these infants and can be difficult to distinguish from dysmotile intestinal function in early stages. Preterm infants treated with nasal continuous positive airway pressure often have distended abdomens with feed intolerance requiring evaluation for potentially life-threatening conditions such as necrotising enterocolitis. Plain abdominal radiography is the gold standard modality for diagnosis, monitoring and guiding management in clinically suspected diseased neonatal bowel states. Timely access of expert surgical opinion poses frequent dilemmas of transporting a critically ill preterm infant to a surgical facility. There is compelling evidence demonstrating diagnostic bowel ultrasound findings in necrotising enterocolitis by trained medical ultrasonographers. There is a growing interest in utility of performing bowel ultrasound amongst point-of-care neonatal clinicians.
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.
SESSION 3C: VASCULAR Dual frequency contrast ultrasound angiography F. Stuart Foster,1 Christine E.M. Demore,1 Emmanuel Cherin,1 Isabel Newsome,3 Claudia Carnevale,2 Paul A. Dayton3 1 Sunnybrook Research Institute and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, 2 Fuji Film Visual Sonics Inc, Toronto, ON, Canada,, 3 Joint Graduate Department of Biomedical Engineering, University of North Carolina and North Carolina State University, NC, USA Acoustic angiography is a contrast imaging approach in which the superharmonics associated with low frequency excitation of microbubbles are received and processed over a broad bandwidth at a much higher frequency. As demonstrated by Dayton and colleagues, this technique facilitates the visualization of the microvasculature with a resolution typical of micro computed tomography and with superior contrast-to tissue-ratios than conventional nonlinear processing. To date dual frequency contrast imaging has been performed with a 2- 4 MHz annulus coaligned with 25-30MHz single element focused transducer operated by a Vevo770 (Visualsonics) scanner. This technology has limitations (mechanical scanning, single focus, limited focal depth) which hinder its clinical use but which could be alleviated using dualfrequency arrays (DFA). In this presentation we first describe the performance and applications of mechanical acoustic angiography and early results from the development of dual frequency array devices for acoustic angiography. The logical extension to array based designs is then explored. We built prototype dual frequency devices in both a vertical and horizonal topology. The horizonal topography consisted of a central 256 element high frequency array (HF, 20 MHz) flanked by two single element low frequency transducers(LF, 2 MHz) that extended for the length of the HF array. The vertical topography consisted of a 32-element LF transmitter array positioned behind a 256-element HF receiver array. Both arrays were built from piezoelectric composites. The HF backing material, between the two piezoelectric layers in the vertical design is weakly and highly attenuating at 2 MHz and 20 MHz, respectively. Two matching layers on the LF array and 4 matching layers on the HF array were used to improve transmission throughout the whole array structure. An elevation lens was added to focus the receive component at around 9 mm. Impedance and hydrophone measurements were performed to evaluate both configurations. Examples of super harmonic contrast imaging for each of the above configurations will be shown for phantom studies and preliminary in vivo images of animal models will be presented.
SESSION 3E: GYNAECOLOGY What are IOTA easy descriptors and simple rules: How to use them Wouter Froyman Consultant Gynaecologist, University Hospitals Leuven, Leuven, Belgium Many adnexal lesions (e.g. dermoid cysts, endometriomas) share typical characteristics which make them easy to identify ‘at a glance’, without needing to apply diagnostic rules or perform risk calculations. Based on this knowledge, the IOTA group proposed four Easy
S19
Descriptors describing typical features of common benign lesions, and two Easy Descriptors suggestive of malignancy. Lesions that cannot be classified using the Easy Descriptors, can be assessed using other methods such as the Simple Rules. The Simple Rules are based on 5 ultrasound features suggesting a benign lesion (Bfeatures) and 5 features that suggest a malignant lesion (M-features). If at least one of the B-features is present without any M-feature, the lesion is classified as benign. Vice versa, if at least one M-feature is present without any B-feature, the lesion is classified as malignant. If both B and M-features are present, or no features are present, the lesion is not classifiable. The IOTA Simple Rules have become very popular because they are easy to use, and do not require a computer for calculation. In 2011, The Royal College of Obstetricians and Gynaecologists (RCOG) incorporated the Simple Rules in the Green-top Guideline on how to manage premenopausal women with adnexal masses. This was followed in 2016 by the American College of Obstetrician and Gynecologists (ACOG) integrating the Simple Rules into their clinical guideline on the evaluation and management of adnexal masses. In 2017, the Simple Rules were considered as the main diagnostic strategy for the assessment of adnexal masses in a first international consensus report.
SESSION 3G: GENERAL NEONATAL Posterior fossa and cerebellar haemorrhages. Imaging technique and long term outcome Adam Hoellering Neonatologist, Queensland Health, Brisbane, QLD, Australia This presentation gives an approach to image acquisition for the structures of the posterior cranial fossa. There will be an overview of the common structural abnormalities and a focus on cerebellar haemorrhages and infarction. Attention will be paid to the importance of the detection of these lesions and the growing body of evidence regarding their impact on long term neurodevelopmental outcomes.
Necrotising enterocolitis and point of care neonatal abdominal USS Archana Priyadarshi Neonatal Clinician and PHD Student, Westmead Hospital, Westmead, NSW, Australia Neonatal intensive care has seen dramatic improvements over last four decades in rates of survival for most preterm newborns. Limits of survival were generally regarded 27 weeks gestation in the 80’s, are now 23 weeks gestation. These micro-premies are much smaller (500 to 800 grams birth weight) and are now increasingly managed with nasal continuous positive airway pressure as respiratory support. Acute abdominal emergencies are common in these infants and can be difficult to distinguish from dysmotile intestinal function in early stages. Preterm infants treated with nasal continuous positive airway pressure often have distended abdomens with feed intolerance requiring evaluation for potentially life-threatening conditions such as necrotising enterocolitis. Plain abdominal radiography is the gold standard modality for diagnosis, monitoring and guiding management in clinically suspected diseased neonatal bowel states. Timely access of expert surgical opinion poses frequent dilemmas of transporting a critically ill preterm infant to a surgical facility. There is compelling evidence demonstrating diagnostic bowel ultrasound findings in necrotising enterocolitis by trained medical ultrasonographers. There is a growing interest in utility of performing bowel ultrasound amongst point-of-care neonatal clinicians.
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.