1、raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication Magnetic resonance equipment for medical imaging Part 2: Classification criteria for pulse sequences BS EN 62464-2:2011National foreword This British Standard is the UK implem
2、entation of EN 62464-2:2011. It is identical to IEC 62464-2:2010. The UK participation in its preparation was entrusted by Technical Committee CH/62, Electrical Equipment in Medical Practice, to Subcommittee CH/62/2, Diagnostic imaging equipment. A list of organizations represented on this committee
3、 can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 69735 7 ICS 11.040.55 Compliance with a British Standard cannot confer immunity from legal
4、 obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2011. Amendments issued since publication Amd. No. Date Text affected BRITISH STANDARD BS EN 62464-2:2011 EUROPEAN STANDARD EN 62464-2 NORME EUROPENNE EUROPISCHE NORM Febr
5、uary 2011 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2011 CENELEC - All rights of exploitation in any form and by any means res
6、erved worldwide for CENELEC members. Ref. No. EN 62464-2:2011 E ICS 11.040.55 English version Magnetic resonance equipment for medical imaging - Part 2: Classification criteria for pulse sequences (IEC 62464-2:2010) Appareils rsonance magntique utiliss pour limagerie mdicale - Partie 2: Critres de c
7、lassification pour les squences dimpulsions (CEI 62464-2:2010) Magnetresonanzgerte fr die medizinische Bildgebung - Teil 2: Klassifizierungskriterien fr Pulssequenzen (IEC 62464-2:2010) This European Standard was approved by CENELEC on 2011-02-01. CENELEC members are bound to comply with the CEN/CEN
8、ELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any
9、CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versi
10、ons. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal,
11、 Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 62464-2:2011EN 62464-2:2011 - 2 - Foreword The text of document 62B/807/FDIS, future edition 1 of IEC 62464-2, prepared by SC 62B, Diagnostic imaging equipment, of IEC TC 62, Electrical equipment in medical practi
12、ce, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62464-2 on 2011-02-01. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all s
13、uch patent rights. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2011-11-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 20
14、14-02-01 In this standard, the following print types are used: Requirements and definitions: roman type. Test specifications: italic type. Informative material appearing outside of tables, such as notes, examples and references: in smaller type. Normative text of tables is also in a smaller type. TE
15、RMS DEFINED IN CLAUSE 3 OF THE GENERAL STANDARD, IN THIS PARTICULAR STANDARD OR AS NOTED: SMALL CAPITALS. The verbal forms used in this standard conform to usage described in Annex H of the ISO/IEC Directives, Part 2. For the purposes of this standard, the auxiliary verb: “shall” means that complian
16、ce with a requirement or a test is mandatory for compliance with this standard; “should” means that compliance with a requirement or a test is recommended but is not mandatory for compliance with this standard; “may” is used to describe a permissible way to achieve compliance with a requirement or t
17、est. Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 62464-2:2010 was approved by CENELEC as a European Standard without any modification. _ BS EN 62464-2:2011 - 3 - EN 62464-2:2011 Annex ZA (normative) Normative references to international publica
18、tions with their corresponding European publications The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) appli
19、es. NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 60601-2-33 2010 Medical electrical equipment - Part 2-33: Particular requirements for the basic safety and essential performance
20、 of magnetic resonance equipment for medical diagnosis EN 60601-2-33 + corr. October 2010 2010 IEC/TR 60788 2004 Medical electrical equipment - Glossary of defined terms - - BS EN 62464-2:2011 2 62464-2 IEC:2010 CONTENTS INTRODUCTION 5 1 Scop e 6 2 Normative references 6 3 Terms and definitions 6 4
21、PULSE SEQUENCE classification . 7 4.1 Gene ra l . 7 4.2 PULSE SEQUENCE type . 7 4.2.1 Genera l 7 4.2.2 Notation . 8 4.3 Magnetisation modification 8 4.3.1 Genera l 8 4.3.2 Notation . 8 4.4 Dimensionality . 10 4.4.1 General 10 4.4.2 Notation . 10 4.5 Echo number . 10 4.5.1 General 10 4.5.2 Notation .
22、 10 Annex A (informative) Examples of use of the PULSE SEQUENCE classification . 11 Bibliography . 12 Index of defined terms used in this standard . 13 Table 1 Magnetisation modification techniques . 9 Table A.1 MANUFACTURER-specific classification examples . 11 BS EN 62464-2:201162464-2 IEC:2010 5
23、INTRODUCTION Presently the MANUFACTURERS of MR EQUIPMENT use names for PULSE SEQUENCES which are adopted from the literature (e.g. SPIN-ECHO) or are defined by the MANUFACTURER (e.g. FISP: fast imaging with steady state precession). In the absence of a classification standard for PULSE SEQUENCES, th
24、e MANUFACTURER-specific terminology complicates comparison of PULSE SEQUENCES. The DICOM standard allows the inclusion of PULSE SEQUENCE information with digital MAGNETIC RESONANCE (MR) images. This information helps with the interpretation of images. However, the DICOM standard allows MANUFACTURER-
25、specific terminology. This International Standard specifies a concise MANUFACTURER-independent classification scheme for MR imaging PULSE SEQUENCES. In terms of MR imaging, the PULSE SEQUENCE is a chronology of RF-pulses, switching of gradient fields and data acquisition with the intention to create
26、 one or more images. As the exact chronology determines the image contrast, image artefacts and other properties of the image, it is necessary to define a consistent and accurate PULSE SEQUENCE classification. The proposed PULSE SEQUENCE classification notation could be implemented as a new DICOM ta
27、g in addition to the existing MANUFACTURER-specific PULSE SEQUENCE name. This would facilitate end users access to this information. Implementation as a new tag would ensure backward compatibility. BS EN 62464-2:2011 6 62464-2 IEC:2010 MAGNETIC RESONANCE EQUIPMENT FOR MEDICAL IMAGING Part 2 Classifi
28、cation criteria for pulse sequences 1 Scope This International Standard specifies the description of PULSE SEQUENCES of MAGNETIC RESONANCE imaging. NOTE The classification in this standard is suitable for: tender texts; image annotation; protocol definition; technical publications. This Internationa
29、l Standard does not apply to MAGNETIC RESONANCE spectroscopy. The classification does not focus on image contrast (T1, T2, proton density), as this is defined by PULSE SEQUENCE parameters (e.g. repetition time, echo time) and is not a property of the PULSE SEQUENCE alone. The PULSE SEQUENCE classifi
30、cation does not specify the K-SPACE acquisition scheme, reconstruction algorithm or post-processing. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the lat
31、est edition of the referenced document (including any amendments) applies. IEC 60601-2-33:2010, Medical electrical equipment Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis IEC 60788:2004, Medical electrical equi
32、pment Glossary of defined terms 3 Terms and definitions For the purposes of this document, the terms and definitions given in IEC 60601-2-33:2010, IEC 60788:2004 and the following apply. 3 . 1 pulse sequence chronology of radiofrequency-pulses, switching of magnetic field gradients, and data acquisi
33、tion for the generation of one or more MAGNETIC RESONANCE images NOTE The terms “imaging sequence” or “sequence” are sometimes used as synonyms for PULSE SEQUENCE. 3 . 2 transverse magnetisation magnetisation component perpendicular to the direction of the static magnetic field 3 . 3 longitudinal ma
34、gnetisation magnetisation component parallel to the direction of the static magnetic field BS EN 62464-2:201162464-2 IEC:2010 7 3 . 4 k-space mathematical space in which the Fourier transform of the image data is represented NOTE This is partially or totally filled with the sampled measurement data.
35、 3 . 5 spin-echo SE refocused TRANSVERSE MAGNETISATION arising at time T after an excitation RF pulse and an additional RF-pulse at time T/2 NOTE The excitation pulse is typically a 90 RF pulse, and the additional refocusing pulse is typically a 180 RF pulse. SEs can be refocused using a sequence of
36、 additional RF pulses. 3 . 6 gradient-echo GR refocused TRANSVERSE MAGNETISATION after a RF pulse using re-phasing magnetic field gradients 4 P ULSE SEQUENCE classification 4.1 General In an imaging PULSE SEQUENCE the LONGITUDINAL MAGNETISATION is partially or totally converted into TRANSVERSE MAGNE
37、TISATION via a radio-frequency (RF) excitation pulse. The TRANSVERSE MAGNETISATION is precessing with the Larmor frequency. The precessing TRANSVERSE MAGNETISATION induces the MR signal. For spatial encoding the precessing TRANSVERSE MAGNETISATION is phase-encoded with the help of gradients prior to
38、 the data acquisition, and frequency encoding is utilised during the data acquisition. The acquired signal is then stored in a so-called K-SPACE line of the raw data matrix. The K-SPACE can be two- (2D) or three-(3D)-dimensional. There are several algorithms that allow reconstructing images from inc
39、omplete K-SPACE data sets (half or partial Fourier, parallel imaging techniques) for the PULSE SEQUENCE classification these techniques are not considered. PULSE SEQUENCES are categorised according to the following classifiers: a) magnetisation modification (optional): modification(s) of the LONGITU
40、DINAL MAGNETISATION or TRANSVERSE MAGNETISATION; b) PULSE SEQUENCE type: SPIN-ECHO or GRADIENT-ECHO with the number repetitions (or shots) and the number of K-SPACE lines per RF excitation; c) dimensionality of data acquisition: 2D or 3D; d) echo number (optional): number of different echoes that ar
41、e used to calculate separate images. These classifiers are used in the following notation (without spaces): 4 . 2 P ULSE SEQUENCE type 4.2.1 General PULSE SEQUENCES create MR images whose signal behaviour is primarily determined by either a SPIN-ECHO (SE) or a GRADIENT-ECHO (GR). The PULSE SEQUENCE
42、type is defined at the centre BS EN 62464-2:2011 8 62464-2 IEC:2010 of the 2D or 3D K-SPACE: If the K-SPACE centre is acquired with a SPIN-ECHO, then the PULSE SEQUENCE is classified as a SPIN-ECHO PULSE SEQUENCE in this International Standard. If the centre of K-SPACE is not acquired with a SPIN-EC
43、HO, then the PULSE SEQUENCE is classified as a GRADIENT-ECHO PULSE SEQUENCE in this International Standard. A more precise classification the PULSE SEQUENCE type is achieved by providing information about the other K-SPACE lines. Therefore, the number of SPIN-ECHOES and GRADIENT-ECHOES per RF excita
44、tion are given. Some image characteristics are sensitive to whether K-SPACE is totally acquired after a single RF excitation (single shot) or whether multiple RF excitations are required (multi-shot), so the number of RF excitations (shots) is also given. 4.2.2 Notation For a SPIN-ECHO PULSE SEQUENC
45、E the following notation is used: : (SE_ GR_)_ For a GRADIENT-ECHO PULSE SEQUENCE the following notation is used: : (GR_ SE_)_ Here, and denote the number of SPIN-ECHOES and GRADIENT-ECHOES, respectively. The values of and can be either integer numbers or formulas of the variables N and M using the
46、signs “+”, “-“, “/”, and “x”. Here, N describes the total number of K-SPACE lines, and M is the number of K-SPACE lines per excitation. The part “GR_“ or “SE_“ is omitted, if is zero. denotes the number of required RF excitations and is given either as an integer number or a formula of the variables
47、 N and M using the signs “+”, “-“, “/”, and “x”. NOTE The sum of and is typically known as the echo train length, and is often written as the number of shots. 4.3 Magnetisation modification 4.3.1 General Optionally, the imaging characteristics of a PULSE SEQUENCE can be changed by adding gradients a
48、nd RF pulses or by replacing parts of the PULSE SEQUENCE. These added pulses and gradients are used to prepare the magnetisation. Different magnetisation modifications can be combined. The magnetisation modification is either acting primarily on the LONGITUDINAL MAGNETISATION or the TRANSVERSE MAGNE
49、TISATION, or is done during RF excitation. For classification of the magnetisation modification, all parts of the PULSE SEQUENCES that have an additional influence on the image characteristics and that are not included in the classification of the PULSE SEQUENCE type are listed. 4.3.2 Notation The magnetisation modification is written as a series of symbols as given in Table 1: : . If no magnetisation modification is used, this classifier is omitted. BS EN 6
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