Ebook Essentials of abdomino-pelvic sonography: Part 2

Part 2 book “Essentials of abdomino-pelvic sonography” has contents: Basic terminology, obstetric doppler, carotid doppler, doppler in portal hypertension, renal doppler, peripheral vessel doppler, anterior abdominal wall, recent advances in sonography,… and other contents.

30 Pre-Conception Pre-Natal Diagnostic Techniques Act India first enacted PNDT act in 1994, later amended as pre-conception pre-natal diagnostic techniques (PCPNDT) act in 2003 An act with a provision for the prohibition of sex selection (before or after conception), and for regulation of prenatal diagnostic techniques preventing their misuse for sex determination leading to female feticide in India Rules: No person shall convey the sex of the fetus to the pregnant lady or her relatives by words, signs, or any other method Mandatory registration of all the machines and diagnostic laboratories by the appropriate authority Form F should be aptly filled and submitted to appropriate authorities by the 5th day of each following month All records should be maintained for minimum of 2 years period and made available for inspection by appropriate authorities USG machine should not be sold to anyone who is not registered under the act Certificate of registration shall be nontransferable In the event of change of ownership, new owner shall apply afresh for the grant of certificate of registration Certificate of registration shall be valid for a period of 5 years Sign board “Disclosure of sex is prohibited under law” shall be displayed in both English and local language in the room and hospital premises Form A—Application for registration/renewal of registration of a genetic counseling centre, genetic laboratory, and genetic clinic Form B—Certificate of registration Form C—Rejection of application for registration or renewal of registration Form D—Record to be maintained by the genetic counseling centre Form E—Record to be maintained by the genetic laboratory Form F—Record to be maintained by the genetic clinic/USG clinic/imaging centre (name, address, registration number, and full record of the pregnant lady) Form G—Form of consent for invasive techniques Form H—Maintenance of permanent record of application for grant or rejection of registration or renewal under the PNDT act SUGGESTED READINGS P W Callen, Ultrasonography in Obstetrics and Gynecolgy, 6th ed, Elsevier, Philadelphia, PA, 2016 C M Rumack, S Wilson, J W Charboneau, and D Levine, Diagnostic Ultrasound: 2-Volume Set, 4th ed., Elsevier Health-US, 2010 S M Penny, Examination Review for Ultrasound: Abdomen & Obstetrics and Gynaecology, Lippincott Williams & Wilkins, Philadelphia, PA, 2010 143 144 Pre-Conception Pre-Natal Diagnostic Techniques Act W Herring, Learning Radiology: Recognizing the Basics, Mosby Elsevier, Philadelphia, PA, 2007 A Adam, Grainger & Allison’s Diagnostic Radiology: 2-Volume Set, Elsevier Health-UK, 2014 D Sutton, Textbook of Radiology & Imaging: 2-Volume Set, Elsevier, New Delhi, India, 2009 S G Davies, Chapman & Nakielny’s Aids to Radiological Differential Diagnosis, Elsevier Health-UK, 2014 M Hofer, Ultrasound Teaching Manual: The Basics of Performing and Interpreting Ultrasound Scans, Thieme, Stuttgart, Germany, 2005 W E Brant, and C Helms, Fundamentals of Diagnostic Radiology: 4-Volume Set, Wolters Kluwer, Alphen aan den Rijn, the Netherlands, 2012 10 W Dahnert, Radiology Review Manual, Wolter Kluwer, Alphen aan den Rijn, the Netherlands, 2011 11 P E S Palmer, B Breyer, C A Brugueraa, H A Gharbi, B B Goldberg, F E H Tan, M W Wachira, and F S Weill, Manual of Diagnostic Ultrasound, World Health Organisation, Geneva, Switzerland, 1995 12 World Health Organization (WHO) and World Federation for Ultrasound in Medicine and Biology, Manual of Diagnostic Ultrasound, Volume and 2, 2013 PART IV Color Doppler 31 32 33 34 35 36 Basic Terminology Obstetric Doppler Carotid Doppler Doppler in Portal Hypertension Renal Doppler Peripheral Vessel Doppler 147 149 153 157 161 163 31 Basic Terminology INTRODUCTION Types Discovered by Christian Johann Doppler in 1842 Color Doppler (CD) is used for detection of blood flow in the vessels Continuous Wave (CW) Doppler—Sound wave is continuously transmitted from one piezoelectric crystal and received by separate transducer Can detect and record even very high-frequency shifts Depth resolution is not possible Pulse Wave (PW) Doppler—Sound wave is alternately transmitted and received using only one crystal Depth of echo source can be detected Intensity of PW Doppler is more than CW Doppler Spectral Doppler—Represented by a graph of flow with time Duplex imaging—B mode + PW Doppler Doppler shift—Change in frequency of sound waves when there is relative motion between the source and the reflector No relative motion of target toward or away from the transducer is detected at an angle of 90 degrees; therefore, no Doppler shift is detected Velocity = frequency × wavelength If an object moves away from the transducer, wavelength increases and frequency decreases (Figure 31.1) Rayleigh scattering—Occurs when a target is smaller in size than wavelength of incident sound beam No reflection returns to the transducer For example, scattering from moving RBCs in color Doppler studies Flow directed away from transducer is usually encoded Blue Flow directed toward the transducer is usually encoded Red (TRAB) Colors can also be changed ● ● Transducer Body surface fr fo Blood vessels θ V Figure 31.1 Illustrating color Doppler principle Faster velocities are displayed in brighter colors Generally, color in the upper half of the scale is s/o flow toward the transducer and color in the lower half of the scale is s/o flow away from the transducer Sample volume (SV) is a box positioned in the centre of the vessel lumen Depicts the area of movement being scanned Width of the SV should not be >two-thirds of the vessel diameter Doppler angle should be between 45 degrees and 60 degrees Spectral broadening represents chaotic movement of blood cells leading to flow disturbances and multiple velocities 147 148 Basic Terminology filling up the spectral window Very high Doppler gain settings and sampling close to the wall may lead to artifactual spectral broadening Wall filter—Device to suppress very slow flow near the baseline It eliminates the artifacts caused by low-frequency pulsation of the vessel wall Pulse repetition frequency (PRF)—Number of transmitted pulses per second High-flow velocity vessels require high PRF setting Slow flow (venous) velocity vessels require low PRF settings Inversely related to depth and frequency Aliasing Reverse wagon wheel effect of racing car is akin to aliasing Can be reduced by ● ● ● Increasing PRF Increasing Doppler angle Decreasing frequency shift (using a low-frequency Doppler transducer) Doppler audio signals and spectral waveform varies from vessel-to-vessel and are characteristic of each vessel Vessel waveform Central-type arteries (low-resistance vessels) have biphasic spectrum with forward flow during systole and diastole Peripheral-type arteries (high-resistance vessels) have triphasic spectrum usually with a sharp systolic peak, a short period of flow reversal in late systole, and near-zero flow in diastole (Figure 31.2) Velocity PSV Window Diastolic notch EDV Systole Diastole Time Figure 31.2 Illustrating triphasic spectral waveform of an artery 32 Obstetric Doppler One should try to avoid spectral power Doppler during the first trimester because of its certain bio effects INTRAUTERINE GROWTH RETARDATION Definition—Condition in which fetus is not able to achieve its inherent growth potential Fetal weight