Материал: part17

K Ultrasound Staged Protocol Data​

Management (Informative)​

K.1 Purpose of this Annex​

The purpose of this annex is to enhance consistency and interoperability among creators and consumers of Ultrasound images​ within Staged Protocol Exams. An ultrasound "Staged Protocol Exam" is an exam that acquires a set of images under specified​ conditions during time intervals called "Stages". An example of such an exam is a cardiac stress-echo Staged Protocol.​

This informative annex describes the use of ultrasound Staged Protocol Attributes within the following DICOM Services: Ultrasound​ Image, Ultrasound Multi-frame Image, and Key Object Selection Storage, Modality Worklist, and Modality Performed Procedure Step​ Services.​

K.2 Prerequisites For Support​

The support of ultrasound Staged Protocol Data Management requires support for the Ultrasound Image SOP Class or Ultrasound​ Multi-frame Image SOP Class as appropriate for the nature of the Protocol. By supporting some optional Elements of these SOP​ Classes, Staged-Protocols can be managed. Support of Key Object Selection allows control of the order of View and Stage present-​ ation. Support of Modality Worklist Management and Modality Performed Procedure Step allow control over specific workflow use​ cases as described in this Annex.​

K.3 Definition of a Staged Protocol Exam​

A "Staged Protocol Exam" acquires images in two or more distinct time intervals called "Stages" with a consistent set of images called​ "Views" acquired during each Stage of the exam. A View is of a particular cross section of the anatomy acquired with a specific ultra-​ sound transducer position and orientation. During the acquisition of a Staged Protocol Exam, the modality may also acquire non-​ Protocol images at one or more Protocol Stages.​

Acommonreal-worldexampleofanultrasoundStagedProtocolexamisacardiacstress-echoultrasoundexam.Imagesareacquired​ in distinct time intervals (Stages) of different levels of stress and Views as shown in Figure K.3-1. Typically, stress is induced by​ meansofpatientexerciseormedication.TypicalStagesforsuchanexamarebaseline,mid-stress,peak-stress,andrecovery.During​ the baseline Stage the patient is at rest, prior to inducing stress through medication or exercise. At mid-stress Stage the heart is under​ a moderate level of stress. During peak-stress Stage the patient's heart experiences maximum stress appropriate for the patient's​ condition. Finally, during the recovery Stage, the heart recovers because the source of stress is absent.​

At each Stage an equivalent set of Views is acquired. Examples of typical Views are parasternal long axis and parasternal short axis.​ Examination of wall motion between the corresponding Views of different Stages may reveal ischemia of one or more regions ("seg-​ ments") of the myocardium. Figure K.3-1 illustrates the typical results of a cardiac stress-echo ultrasound exam.​

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Extra-Protocol

Images

Figure K.3-1. Cardiac Stress-Echo Staged Protocol US Exam​

K.4 Attributes Used in Staged Protocol Exams​

The DICOM Standard includes a number of Attributes of significance to Staged Protocol Exams. This Annex explains how scheduling​ and acquisition systems may use these Attributes to convey Staged Protocol related information.​

TableK.4-1listsalltheAttributesrelevanttoconveyStagedProtocolrelatedinformation(seePS3.3fordetailsabouttheseAttributes).​

Table K.4-1. Attributes That Convey Staged Protocol Related Information​

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a.​Recommended if the Modality conforms as an SCU to the Modality Worklist SOP Class and Modality Performed Procedure Step​

b.​Sequence may have one or more Items​

K.5 Guidelines​

This annex provides guidelines for implementation of the following aspects of Staged Protocol exams:​

•​Identification of a Staged Protocol exam.​

•​Identification of Stages and Views within a Staged Protocol exam.​

•​Identification of extra-Protocol images within a Staged Protocol exam.​

•​Acquisition of multiple images of a View during a Stage, and identification of the preferred image for that Stage.​

•​Workflow management of Staged Protocol images.​

K.5.1 Staged Protocol Exam Identification​

TheAttributesNumberofStages(0008,2124)andNumberofViewsinStage(0008,212A)areeachType2Cwiththecondition"Required​ if this image was acquired in a Staged Protocol." These two Attributes will be present with values in image SOP Instances if the exam​ meets the definition of a Staged Protocol Exam stated in Section K.3. This includes both the Protocol View images as well as any​ extra-Protocol images acquired during the Protocol Stages.​

The Attributes Protocol Name (0018,1030) and Performed Protocol Code Sequence (0040,0260) identify the Protocol of a Staged​ Protocol Exam, but the mere presence of one or both of these Attributes does not in itself identify the acquisition as a Staged Protocol​ Exam.IfbothProtocolNameandPerformedProtocolCodeSequenceAttributesarepresent,theProtocolNamevaluetakesprecedence​ over the Performed Protocol Code Sequence Code Meaning value as a display label for the Protocol, since the Protocol Name would​ convey the institutional preference better than the standardized code meaning.​

K.5.2 Stage and View Identification​

Display devices usually include capabilities that aid in the organization and presentation of images acquired as part of the Staged​ Protocol. These capabilities allow a clinician to display images of a given View acquired during different Stages of the Protocol side​ by side for comparison. A View is a particular combination of the transducer position and orientation at the time of image acquisition.​ ImagesareacquiredatthesameViewindifferentProtocolStagesforthepurposeofcomparison.Forthesefeaturestoworkproperly,​ the display device must be able to determine the Stage and View of each image in an unambiguous fashion.​

There are three possible mechanisms for conveying Stage and View identification in the image SOP Instances:​

•​"Numbers" (Stage Number (0008,2122) and View Number (0008,2128) ), which number Stages and Views, starting with one.​

•​"Names"(StageName(0008,2120)andViewName(0008,2127)),whichspecifytextualnamesforeachStageandView,respectively.​

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•​"Code sequences" (Stage Code Sequence (0040,000A) for Stage identification, and View Code Sequence (0054,0220) for View​ identification), which give identification "codes" to the Stage and View respectively.​

The use of code sequences to identify Stage and View, using Context Group values specified in PS3.16 (e.g., CID 12002 “Ultrasound​ Protocol Stage Types” and CID 12226 “Echocardiography Image View”), allows a display application with knowledge of the code se-​ mantics to render a display in accordance with clinical domain uses and user preferences (e.g., populating each quadrant of an​ echocardiographic display with the user desired stage and view). The IHE Echocardiography Workflow Profile requires such use of​ code sequences for stress-echo studies.​

Table K.5-1 provides an example of the Staged Protocol relevant Attributes in images acquired during a typical cardiac stress-echo​ ultrasound exam.​

Table K.5-1. Staged Protocol Image Attributes Example​

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K.5.3 Extra-protocol Image Identification​

At any Stage of a Staged Protocol exam, the operator may acquire images that are not part of the Protocol. These images are so-​ called "extra-Protocol images". Information regarding the performed Protocol is still included because such images are acquired in​ thesameProcedureStepastheProtocolimages.TheStagenumberandoptionallyotherStageidentificationAttributes(StageName​ and/or Stage Code Sequence) should still be conveyed in extra-Protocol images. However, the View number should be omitted to​ signify that the image is not one of the standard Views in the Protocol. Other View identifying information, such as name or code se-​ quences, may indicate the image location.​

Table K.5-2. Comparison Of Protocol And Extra-Protocol Image Attributes Example​

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