LOINC/RSNA Radiology Playbook User Guide

1 Introduction

Welcome to the LOINC/RSNA Radiology Playbook User Guide. This work is the result of a multi-year collaboration between Regenstrief Institute and the Radiological Society of North America (RSNA), supported by the National Institute of Biomedical Imaging and Bioengineering (NIBIB). The participants have developed a model that combines and unifies the useful aspects of LOINC Radiology and the RSNA RadLex Playbook. Both of these terminology initiatives are designed to represent concepts of radiology orderables and results and their attributes.

Each term in the unified Playbook model has a name (a.k.a. description), and takes on a number of attributes. This guide is intended to describe the semantics, syntax, and proper usage of those attributes. Within the terminology, these attributes are used as building blocks to construct several types of standard names, including a fully specified name, long name, and short name.

A list of the Playbook attributes is shown below. Attributes are organized according to attribute groups, consisting of the major bullet headings below, and by more specific sub-attributes, shown in the minor bullets below and denoted by a dot after the attribute group, such as Pharmaceutical.Route.

  • Modality
    • Modality.Modality Type
    • Modality.Modality Subtype
  • Anatomic Location
    • Anatomic Location.Region Imaged
    • Anatomic Location.Imaging Focus
    • Anatomic Location.Laterality.Presence
    • Anatomic Location.Laterality
  • View
    • View.Aggregation
    • View.View Type
  • Timing
  • Maneuver
    • Maneuver.Maneuver Type
  • Pharmaceutical
    • Pharmaceutical.Substance Given
    • Pharmaceutical.Route
  • Reason for Exam
  • Guidance
    • Guidance for.Presence
    • Guidance for.Approach
    • Guidance for.Action
    • Guidance for.Object
  • Subject

The chapters that follow provide a guide to the usage of each of the above attributes.

1.1 Codes and workflows

Radiology procedure codes impact a variety of workflows in the health care enterprise, including ordering, scheduling, billing, protocol specification, image acquisition, and image interpretation, among others. In each case, the codes serve specific purposes in identifying imaging exams. While there is a great deal of overlap between these workflows, there are also important differences. For example, radiology billing is often concerned with a less detailed description of an imaging exam, while the radiology ordering process often involves more information about the requested study.

The Playbook work has been primarily focused on addressing the needs of the radiology ordering workflow. The semantic model described in this document is intended principally to characterize radiology “orderables.” This then raises the question of what constitutes an orderable exam, an issue which is complicated by several factors. First, different institutions may expose different levels of granularity at the point of radiology order entry. While one may consider “CT abdomen / pelvis with contrast” to be an appropriate option in an order entry system, another institution may wish to provide the choice “CT abdomen / pelvis with contrast, liver mass.” Second, in certain circumstances, what is actually done to satisfy an imaging request may not match the ordered procedure precisely. For example, image-guided interventions often entail procedural modifications at the time of the exam. In such cases, modified or additional orderables may be entered, even though these may not have been exposed in the clinical ordering interface. Third, some institutions have separate orderable codes for interpretations of studies performed at outside institutions ("interpretation only").

The model aims to allow for the type of variation described above, so as to broadly fulfill the needs of radiology ordering workflows at a variety of institutions. We discussed the concept of "interpretation only" and decided not to create a duplicate set of orderables for the interpretations of outside films. Instead, we created a single LOINC code, 86371-2 Study Interpretation of outside study, that can be used with the primary study code to report whether the study being interpreted was performed at an outside institution. Regarding the technical factors in image acquisition, related work at a more granular level is being done by the DICOM Standards Committee.1

2 Syntax

2.1 Operators

The model uses several logical operators (“.”, “+”, “>”, “&”, "^", "()", "&&") to express combinations of atoms.

2.1.1 "." (Dot)

Used to specify refinement of a given attribute or attribute component. For example, the dot operator may be used with the Imaging focus component of the Anatomic Location attribute to specify a more granular focus (e.g. Ribs.lower). For modality subtypes, it is used to indicate a certain type of imaging technique (e.g. “CT.angio”).

2.1.2 "+" (Plus)

Used to combine atoms, such as Anatomy atoms or View atoms, with AND semantics.

2.1.3 ">" (Greater than)

Used exclusively to separate the Region Imaged from the anatomic Imaging Focus.

2.1.4 "&" (Ampersand)

Used to separate Region imaged and Imaging focus pairs when more than one anatomic location across more than one region is imaged. May alternatively be used as a low-precedence AND, such as in the Timing attribute WO & W, which has a combined “before and after” notation.

2.1.5 "^" (Carat)

Used primarily to separate the Maneuver attribute from the View attribute.

2.1.6 "()" (Parentheses)

Used to indicate bindings between Maneuver and View values when more than one View.Aggregation and/or View.View Type exists and the maneuver(s) only applies to a subset of the View values.

2.1.7 "&&" (Double ampersand)

Used to indicate parallelism in cases where the relationships between values across multiple attributes needs to be specified. In earlier versions the "&" was used for parallelism, but since we started using "&" to separate Region imaged and Imaging focus pairs, we created a new delimiter for parallelism in order to distinguish the two concepts.

2.1.8 Precedence

Operator precedence, from greatest to least is as follows: “.”, “+”, “>”, “&”, "^", "()", "&&"

2.2 Parallelism

In selected circumstances, it is necessary to specify multiple values for two or more specific attributes or components. In such cases, the correspondences between values across attributes or components may be modeled by maintaining a consistent ordering of values. For example, a radiographic exam of the ribs often includes a radiograph of the chest. The specific views may include an AP view of the chest, and an oblique view of the ribs. Multiplicity of the Anatomic Location attribute as well as the View attribute is modeled using parallelism and the “&&” operator. That is, with Anatomic Location Chest && Ribs and View AP && Oblique the appropriate correspondence between Chest and AP as well as between Ribs and Oblique is maintained by virtue of the relative positions of the atoms (i.e., both Chest and AP are listed first in their respective attributes).

3 Modality

3.1 Definitions

Modality is used to represent the device used to acquire imaging information. Modalities consist predominantly of a subset of the two-letter DICOM modality codes. DICOM modality codes are listed in PS3.3, Section C.7.3.1.1.1 in the 2016 release of the DICOM standard.2 In addition, the Modality code {Imaging modality} is used to indicate image-guided procedures for which the specific type of imaging is not explicitly modeled.

A Modality subtype may be listed, separated by a “.”, to signify a particularly common or evocative configuration of the modality.

Note that when such Modality subtypes are specified, the given type of technique is included in a study, although this does not necessarily imply that the study consists exclusively of that subtype of imaging. For example, an exam with Modality and subtype US.doppler does not mean that only Doppler imaging was performed. On the other hand, XR.portable generally does indicate that only portable images were obtained.

3.2 Usage Notes

  1. Subtype angio: This Subtype is used for procedures designed to give angiographic images of the vessels (either blood or lymphatic vessels). This should not be used for US; Doppler should be used instead. Angio is not a synonym for contrast administration because some angiographic MR studies do not require intravenous contrast administration.
  2. Mammography tomosynthesis Subtype: This Subtype, also known as digital breast tomography (DBT), is a type of digital mammography that is distinct from the concept of full field digital. MG.tomosynthesis is used for 3-dimensional imaging, while typical digital mammography is 2-dimensional. Digital 2D mammograms may also be reconstructed into 3D images, but these would not be classified under MG.tomosynthesis.
  3. Obsolete mammography subtypes: We originally included MG.analog and MG.full field digital (FFD) in the list of allowed MG Subtypes to specify analog mammography and digital mammography, respectively, while MG without a Subtype signified a procedure that could be done with digital or analog equipment. However, given that over the past several years digital mammography has become standard practice, we recommend that moving forward, FFD does not need to be specified as a subtype of MG. Instead, **the generic MG** LOINC codes should be used for 2D mammography, which in most cases will be digital images but may also include analog images.
  4. CR (computed radiography) vs DX (digital radiography) vs RG (radiographic imaging/conventional film screen): XR will be adopted generically to signify orders for planar radiography. When the images are acquired, the imaging modality may wish to insert a more specific modality code in the DICOM files.
  5. Doppler Subtype vs DICOM modality codes DD (duplex Doppler) and CD (color flow Doppler): US.Doppler will be used as the attribute of the orderable procedure. When the images are acquired, the imaging modality may wish to insert a more specific modality code in the DICOM files.
  6. Portable indicates whether the device is movable or whether the patient will come to the radiology department for imaging.
  7. SPECT will be represented as a Modality subtype of the NM Modality (NM.SPECT) rather than using ST, the DICOM modality code for SPECT.
  8. Because there is no DICOM modality code for DEXA, DXA will be adopted as the Modality code.
  9. When an imaging study involves more than one imaging Modality, “+” is used to concatenate the two Modalities, such as PT+CT or NM.SPECT+CT. The Modality listed first corresponds to the departmental area where the device is typically located. E.g., PT+CT, not CT+PT
  10. For studies with two Modalities that have separate attributes and are performed consecutively (e.g., RF Upper GI with XR abdomen), “&&” is used in the harmonized model and in LOINC to separate the values of each attribute, including Modality, to maintain parallelism across attributes, e.g., XR && RF. However, note that in the Radiology Lexicon (RadLex) imaging modality hierarchy, such Modalities that are commonly performed consecutively are represented as a single entity under the combined modalities node using a "+", e.g., XR+RF.
  11. Precedence of operators is “.”, “+”, “&&” (the other delimiters are not used in the Modality attribute).
  12. The perfusion Modality subtype indicates the study is intended to measure tissue perfusion; if the study is designed to image the vessels, use the angio Modality subtype.
  13. 3D is an image processing step, and can be performed on images from a variety of modalities. Its use is discouraged. If adopted locally, it may be used as shown in Reason for Exam section.
  14. Modality {Imaging modality} is used to refer to image-guided procedures, where the particular type of imaging used is not specified in the orderable. For example, liver biopsies may be performed under ultrasound or CT guidance, although the particular modality used may be at the discretion of the operator. In such cases, {Imaging modality} indicates that the order is modality-agnostic.

3.3 Allowed Modality/Subtype Combinations

  • CT
    • CT.angio
    • CT.scanogram
    • CT.densitometry
    • CT.perfusion
    • CT.portable
  • DXA
    • DXA.densitometry
  • MG
    • MG.tomosynthesis
    • MG.stereotactic
  • MR
    • MR.angio
    • MR.functional
    • MR.spectroscopy
  • NM
    • NM.dosimetry
    • NM.SPECT
    • NM.SPECT+CT
  • PT
    • PT.perfusion
    • PT+CT
  • RF
    • RF.angio
    • RF.video
    • RF.portable
  • US
    • US.densitometry
    • US.Doppler
    • US.portable
  • XR
    • XR.tomography
    • XR.portable
  • {Imaging modality}

4 Anatomic Location

This chapter describes how anatomic terms are used to identify the body region and anatomic focus of imaging. It also specifies the syntax to be used when more than one anatomy term applies to a given exam code, and delineates how laterality should be specified when necessary.

4.1 Definitions

The Anatomic Location attribute specifies the body part or body region that is imaged and includes the sub-attributes, Region Imaged and Imaging Focus. The most specific anatomic structure should be specified. Multiple Anatomic Locations may be specified using the syntax specified below and should be specified only when necessary to distinguish the code from other codes. Anatomic Location terms are generally drawn from the RadLex anatomic hierarchy.

Region imaged is used in two ways. First, as a coarse-grained descriptor of the area imaged and a grouper for finding related imaging exams; or, it is used just as a grouper. For example, when an abdominal CT focuses on the liver, it images the abdomen as a whole and also would be a relevant comparison for other abdominal CT exams (e.g., renal CT), thus making abdomen a coarse-grained descriptor as well as a grouper. Similarly, a head CT focusing on the brain may also be a relevant comparison for other head CT exams (e.g., orbit CT), making it both a descriptor and grouper. Alternatively, for most studies with Upper extremity or Lower extremity as the Region imaged and a specific Imaging focus, such as Wrist or Knee, the Region imaged is a grouper only, because the entire extremity is typically not imaged.

Imaging focus is defined as a more fine-grained descriptor of the specific target structure of an imaging exam. In many areas, the focus should be a specific organ. For example, in the Region imaged Abdomen, the Imaging focus might be Liver, Pancreas, Adrenal gland, Kidney, etc. In other areas, the Imaging focus will simply be a more specific area within a given region. For example, in the Region imaged Upper extremity, the Imaging focus might be Shoulder, Upper arm, Elbow, Forearm, Wrist, Hand, etc.

Our goals are to populate both the Region imaged and Imaging focus sub-attributes for all terms, except where the Region Imaged is the focus of the study (see Section 4.2.1). We will also constrain Region Imaged to the following short list of regions:

  • Head
  • Neck
  • Chest
  • Breast
  • Abdomen
  • Pelvis
  • Extremity
  • Upper extremity
  • Lower extremity
  • Whole body (used when the Imaging focus exists throughout the body and is being imaged in its entirety, such as Bones or Bone marrow)
  • Unspecified (represented in LOINC as XXX, used when the Imaging focus exists in multiple parts of the body but only one specific instance is being imaged, such as a Blood vessel)

Pathologic entities may not serve as an anatomic location (e.g., renal tumor). If there is a need to specify a pathologic entity to distinguish to exam codes, the pathologic entity should be specified with the Reason for Exam attribute or Guidance for.Object sub-attribute.

4.2 Syntax and Modeling Principles

The syntax used to describe the Anatomic Location attribute is as follows:

<body region imaged> ">" <imaging focus>

For example, for an abdominal CT with a focus on the liver, the Anatomic Location would be specified as:

Abdomen>Liver

4.2.1 Specifying Region(s) imaged without an Imaging focus

If there is a single anatomic context associated with a code, it should be specified as <body region imaged> without an <imaging focus>, for example, for an abdominal CT, the _Anatomic Location_would be specified as:

Abdomen

When multiple regions are imaged without an imaging focus, such as CT of the head and neck, the two regions are separated by a "+":

Head+Neck

4.2.2 Imaging foci that cross body regions

Certain Imaging foci cross multiple body regions, such as Pharynx, which is included in both the Head and Neck Imaging regions. In this case, the regions will be separated by a “+” as follows:

Head+Neck>Pharynx

4.2.3 Specifying multiple Anatomic locations

When more than one Anatomic location is imaged, where each location has a different Region imaged and Imaging focus pair, they are separated by an “&” according to the syntax:

<body region imaged A> ">" <imaging focus A> "&" <body region imaged B> ">" <imaging focus B>

For example, a study of the chest and abdomen focused on the lung and liver would be specified as follows:

Chest>Lung & Abdomen>Liver

4.2.4 Broad region combined with a specific focus

In other situations, a specific Imaging focus in one Region imaged may be imaged at the same time as a different Region imaged without a focus. Consider an MRI examination of the face and neck. Face is an Imaging focus of the Region imaged Head. Neck is an additional Region imaged. In such situations, the lower precedence of the “&” compared to the “>” operator is used to combine these areas as follows:

Head>Face & Neck

4.2.5 Specifying terms without an anatomic location

In some cases, such as fluoroscopic guidance codes, a specific Anatomic Location may not be relevant, in which case we use the general unspecified Region imaged.

4.2.6 Parallelism

In rare instances, a complex study may require parallelism to model correctly. In this instance, a double ampersand is used to separate the elements of the study. For example, a study that consists of PA and lateral views of the chest plus 4 oblique views of the right ribs could be represented as with the following Anatomic location and Views.

 Chest && Chest>Ribs.Right           Views 2 PA+Lateral && Views 4 Right oblique

4.2.7 Operator precedence

The precedence of operators is ".", "+", ">", "&", "&&". For example:

Head+Neck > Pharynx

is equivalent to

(Head+Neck)> Pharynx

4.2.8 Region imaged as grouper +/- coarse-grained descriptor

The nature of the study should make it clear whether the Region imaged is functioning as both a coarse-grained descriptor of the area imaged and a grouper or as a grouper only. The following are additional guidelines to help users make that determination:

  1. In general, when the Region imaged is the Head, Neck, Chest, Abdomen or Pelvis, it is both a coarse-grained descriptor and a grouper;
  2. For spine studies, the Region imaged is typically a grouper only (this is an exception to rule #1). For example, a C-spine exam will have the Anatomic location specified as Neck>Spine.cervical, but typically the exam would focus on the spine and not include general imaging of the neck;
  3. When the Region imaged is Upper extremity or Lower extremity, it typically functions as a grouper only.

4.2.9 Laterality

Many exams require laterality to be specified in order to be performed. These exams will be signified with an Anatomic Location.Laterality.Presence attribute set to True. For terms with Laterality.Presence = True, the Laterality attribute must not be null. Valid values of the Laterality attribute are:

  • Left
  • Right
  • Bilateral
  • Unilateral
  • Unspecified

The recommended practice is to specify one of Left, Right, or Bilateral for Anatomic Location.Laterality whenever Anatomic Location.Laterality.Presence = True. If the Laterality.Presence attribute is False, the Laterality attribute must be null. Laterality applies to the most specific anatomic part associated with the exam code.

4.2.10 Subject

Some exams are relevant only to a Fetus or a Gestation. This distinction will be represented when necessary by the Subject attribute.

4.2.11 Ectopic Anatomy

Ectopic anatomy, such as a transplanted kidney, if needed to distinguish an exam code, should be specified as a Reason for Exam, not as an Anatomic Location. Anatomic Location corresponds to where the transplanted kidney is located, e.g., Pelvis.

4.2.12 Anatomic terminology in the extremities

In the upper extremity, the term Upper arm is preferred over the term “arm.” Even though these are technically equivalent, the redundancy of Upper arm provides for greater clarity. Upper arm is also preferred over “humerus” for this area, as the latter is bone-specific and could be construed as excluding soft tissues. Similarly, in the lower extremity, Lower leg is preferred over “leg,” “calf” and “tibia / fibula.”

4.2.13 Singular vs. Plural

The singular form of an anatomic structure is typically used, except in a few specific cases that primarily apply to vasculature, as noted below.

4.2.14 Singular vs. Plural in the context of Vasculature

For the set of vessels associated with a particular region, organ or a specific group of vessels, we use the plural "Vessels”, “Veins” and “Arteries” to mean “set of”, for example, Adrenal vessels or Cerebral arteries. One use case for such pre-coordination is angiography, for example, CT angiography of the renal vessels would have the following Anatomic Location:

Abdomen>Renal vessels

The plural form does not imply laterality, which is still specified using the Laterality attribute (see 4.2.9 - Laterality). For example, Abdomen>Renal vessels.right means the set of renal vessels supplying the right kidney.

Specific named vessels use the singular form, e.g., Femoral vein and Superior mesenteric artery.

When vessels in an extremity are imaged for a specific reason, such as varicose vein treatment, and there are different CPT codes for treatment of a single vessel and treatment of multiple vessels, we use the plural form to mean multiple and also created a singular form to represent treatment of a single vessel even though that vessel is not named, i.e., Extremity veins and Extremity vein.

5 View

This chapter describes the View attribute, which is used to indicate the orientation of the patient in the image. This may reflect a combination of patient position and x-ray beam direction, or may alternatively be captured in a named, or eponymous, View. While this most commonly refers to radiography (e.g. a lateral radiograph of the chest), it may also be used with other modalities (e.g. prone CT of the chest, or an RF.angio study of the abdominal aorta with runoff views). Attribute values such as Runoff and Perfusion indicate that these views are included in the study but do not imply that the study is limited to only these views. Portable is specified as part of the Modality attribute rather than the View.

In many instances, the View attribute will not be specified at all (e.g. MRI of the brain) in the Playbook model. However, note that in the LOINC model, the Component part of all radiology terms specifies the type of image acquired based on the modality: Views for XR, MG, and NM, and Multisection for MR, CT, US, NM.SPECT, PT, and XR.tomography.

5.1 Definitions

The View attribute includes optional sub-attributes, including Aggregation and View Type.

The Aggregation component is used to describe the extent of the imaging performed, whether in quantitative terms (e.g., 3 or more views) or subjective terms (e.g., Complete). The use of “Follow-up” as a value of the Aggregation attribute is replaced by the value Limited.

View Type is used to name specific views, such as Lateral or Prone. View Type is an indicator of the orientation of the patient in an image, often carrying an implication of passive positioning (i.e. positioning which is not unduly onerous for the patient). This may reflect a combination of patient position and imaging direction (e.g. x-ray beam direction), and may be captured in a named or eponymous term (e.g. Norgaard view). The positioning involved in view types is designed to permit visualization of specific anatomic targets or particular orientations (e.g. open mouth odontoid view, swimmer’s view). Note that this positioning is usually not passive in the strict sense (i.e. performed by someone else), but rather passive in the sense that it is neither onerous for the patient, nor intended as a challenge to the patient. We considered creating a separate attribute for patient position, however, given that relatively few terms would include this attribute, we decided to include it within the View Type.

5.2 Syntax

The syntax used to describe the View attribute is as follows:

<Aggregation> <View Type>

For example, for a cervical spine X-ray with AP and lateral views, the View would be specified as:

Views AP + lateral

5.2.1 Aggregation

As stated above, the Aggregation attribute is optional and, when included, specifies the extent of imaging performed in qualitative or quantitative terms. Qualitative descriptors include concepts such as Limited, Complete, and Multiple days. Quantitative aggregation values can specify a fixed number or range of views. The syntax for representing greater than or equal to and less than or equal to a specific number of views is "GE <#>" and "LE <#>, respectively. All of the following are examples of Aggregation:

Views multiple areas
Views 2 or 3
Views GE 5

When the number of views is specified for a bilateral exam, the number refers to the number of views per side (e.g., XR Knee Bilateral 2 Views specifies 2 views of each knee).

5.2.2 View Type

In studies that specify a View Type, one or more values can be specified, separated by a "+". For example:

View lateral
Views PA + lateral
Views PA + lateral + R-oblique + L-oblique

5.2.2.1 Eponymous View Types

Eponymous views imply patient position and beam direction, as well as anatomic focus. Anatomic focus will continue to be specified separately as described in the previous chapter, recognizing this redundancy.

5.2.2.2 Laterality in the view

Laterality may optionally be specified in certain views (e.g., “Lateral,” “Right lateral” or “Left lateral”). The laterality specified in this case indicates patient position relative to the beam, not the side of the patient being imaged, and is thus independent of the Anatomic Location.Laterality sub-attribute.

5.2.3 Specifying Aggregation and View Type

In many cases, both an Aggregation and one or more View Type values are specified. If the Aggregation value includes the specified View Types, the two values will not be separated by a delimiter. However, if the View Types are in addition to the number of views specified in the Aggregation value, the two values are separated by a "+".

For example, 2 views including an oblique view is represented as:

Views 2 oblique

And 2 views and an additional oblique view is given by:

Views 2 + oblique

5.2.4 Parallelism

Sometimes, parallelism is required to show which attributes are associated with which views. As described earlier, the double ampersand ("&&") is used to show parallelism. For example, an exam that includes a PA view of the chest and at least three rib views would be modeled with the following View and Anatomic location attributes:

Views GE 3 && View PA          Chest>Ribs && Chest

That is, the atoms Chest>Ribs and Views GE 3 form one group, and Chest and View PA another group. Note that this parallelism relies on a consistent ordering of atoms to maintain proper groupings.

6 Timing

The Timing/Existence attribute may be used in conjunction with both the Maneuver and Pharmaceutical attributes. This attribute specifies the existence of a Maneuver or a Pharmaceutical, or, in some cases, the existence of one Maneuver (or Pharmaceutical) and the absence of another, for example, views of the thoracolumbar spine without and with lateral bending.

The Timing/Existence attribute can be either simultaneous:

WO
W

A combined “before and after” notation that denotes separate sets of images:

WO & W

Or describing an image taken at a specified time after administration of the pharmaceutical:

48H post

7 Maneuver

7.1 Definitions

Maneuvers relate to a challenge presented to a patient, often with the goal of elucidating or testing some dynamic aspect of anatomy or physiology. Maneuvers often carry an implication of patient exertion (e.g. Valsalva maneuver), although some maneuvers do not involve patient exertion (e.g. pharmacologic cardiac stress). Timing/Existence specifies the existence of that Maneuver, or, in some cases, the existence of one Maneuver and the absence of another. For example, flexion and extension views of the cervical spine are used to detect instability as indicated by changes in spinal alignment. Similarly, views of the thoracolumbar spine without and with lateral bending may be done to evaluate scoliosis. Inspiratory and expiratory maneuvers as part of chest imaging may be used to evaluate the lungs. Maneuvers may occur in pairs (e.g. Flexion and Extension). As above, these factors distinguish maneuvers from patient actions used purely to gain a desired perspective. For example, the cross-table lateral radiograph of the hip requires the patient to be lying supine with the contralateral leg bent and raised, though the purpose of this is to obtain a lateral angle on the hip rather than to test stability or dynamic change. In such cases, the patient position is embodied in the named View Type (e.g. Danelius Miller) as described in the View definitions section, rather than with a maneuver.

In general, Maneuver values, when included, are specified together with a Timing attribute value, such as W or WO, similar to Pharmaceuticals as defined in the next chapter. If no maneuver is specified, it is assumed that the patient is at rest.

7.2 Syntax

Maneuvers are separated from the View attribute by "^" (a carat or a "hat"). By default, the specified Maneuver(s) applies to all of the Aggregation and View Types preceding the carat, and vice versa. For example, in the first example below, W standing applies to the Lateral View, and in the second, to both the AP and Lateral Views. In the third, Standing and Flexion both apply to the PA View:

View lateral^W standing
View AP+lateral^W standing
Views PA^W standing+W flexion

7.2.1 Maneuvers that only apply to a subset of the Aggregation and/or View Types

In some cases, a given Maneuver or set of Maneuvers will only apply to some of the Aggregation or View Types that are specified. In such cases, parentheses are used to indicate which Aggregation or View Type(s) the Maneuver is related to. For example, a study that includes 2 views plus one or more unspecified views with standing is given by:

(Views 2) + (views^W standing)

A more complicated example is a study that has two sets of Maneuvers, each of which is related to a different View Type:

(Views AP^W R-bending + W L-bending) + (view lateral^W flexion + W extension)

8 Pharmaceutical

8.1 Definitions

The Pharmaceutical attribute specifies the presence or absence of chemical agents relevant to the imaging procedure. We use this attribute to specify administered contrast agents, radiopharmaceuticals, medications, or other clinically important agents and challenges during the imaging procedure.

8.2 Syntax

The syntax used to describe the Pharmaceutical attribute specifies several optional components:

<timing/existence><substance given><route>

Only the components required for specifying the pharmaceutical at a clinically important level are included in the attribute value.

8.3 Examples

Using this syntax, a common contrast specification of without then with IV contrast would be denoted:

WO & W contrast IV

In other cases, the time delay is a key component:

48H post contrast PO

8.4 Specifying more than one pharmaceutical

The syntax above can also be used to specify more than one pharmaceutical that may be influence the imaged physiology. For example, a nuclear medicine cardiac stress test may involve administration of a radiopharmaceutical and a stress agent such as Adenosine, Dobutamine, or Regadenoson. The attribute value list will contain only single pharmaceuticals. We specify multiple instances of the Pharmaceutical attribute by combining them with “+”:

W adenosine + W radionuclide IV
W dipyridamole + W Tc-99m Sestamibi

8.5 Usage Notes

Some pharmaceuticals will be more fully specified than others. For example, some may specify the specific substance:

W Tc-99m Sestamibi IV

whereas others name a more generic class:

W radionuclide IV
W anesthesia

8.5.1 Preference for Generic Names

We use the generic name of a pharmaceutical, not the brand name, e.g., Tc-99m Sestamibi, not Cardiolite. We will usually include the brand or trade names as synonyms. In rare cases, we use the brand name when a generic form does not exist (e.g., Theraspheres).

8.5.2 Route

Where possible, we denote the Route of administration by abbreviations for medication routes (Table 6 of the LOINC Users’ Guide). An oral route of administration would be denoted by PO, an intravenous route by IV.

8.5.3 Intra versus Via

When describing administration of contrast into specific spaces for which abbreviations do not exist, the space is spelled out in full, and preceded by intra or via according to these guidelines.

  • We use intra when the contrast injected goes directly into an anatomic space, and this space is what is visualized in the study. For example:
W contrast intra lymphatic
  • We use via when the contrast injected goes through a device or anatomic space into the separate anatomic space being visualized. For example:
W contrast via catheter
W contrast via urethra

8.5.4 Existence versus Absence

The Existence component of the pharmaceutical attribute allows specification of whether or not the imaging occurs in the presence of the agent where existence is denoted W, WO, or WO & W. The existence of WO & W denotes separate images, without and with the pharmaceutical.

8.5.5 Relationship to View.Maneuver sub-attribute

Like the physical maneuvers described in the section on the View attribute, pharmaceutical agents are also intended to test a dynamic aspect of the anatomy, with similarities in how these are modeled. In some cases, an exam may use one or the other that are intended to produce a similar anatomic response (e.g., W exercise or W adenosine). Where needed, they can also be used together as different attributes of the overall term model. For example, in defecography, both a maneuver and contrast are specified:

W contrast PR & during defecation

8.6 Issues

  • [Decision: YES] LOINC to change order (WO then W) pattern
  • [Decision: NO] Should the existence convention be changed to the more redundant but more clear full expression:
WO contrast IV & W contrast IV
  • [Decision: NO] Should the combination pharmaceuticals be items in the attribute value list?
  • Is there a more up to date specification of Routes? Not really. FHIR uses this same table. Some were added in 2.3.1
  • [Decision: YES] Should we remove the amount sub-attribute?
  • Intra articular -> IS (Intrasynovial)
  • We will use quotes for keeping together separate words within an attribute. We’ll look for naming conventions to eliminate the need for this. We will convert WO & W to WO&W.
  • Include the Modifiers from Views:
    • Deprecate usage of “1 phase” in LOINC (it is implied unless stated as 3 phase)
    • 3 Phase
    • 30M post
    • 45M post
    • Delayed
    • Runoff

9 Reason For Exam

9.1 Definitions

Reason for exam is used to describe a clinical indication or a purpose for the study. This may refer to a patient diagnosis, a clinical indication, a clinical status (e.g., Post op), an intended measurement, altered anatomy (e.g., Endograft), or some other indicator of the purpose of the exam (e.g. Screening).

The terms Diagnostic and Screening are used as values of the Reason for exam attribute, and these are potentially confusing for two reasons. First, diagnostic is often thought of as complementary to screening, in which case the terms refer to the patient’s clinical status (i.e., asymptomatic patients undergo screening exams, whereas symptomatic patients undergo diagnostic exams). However, diagnostic is also frequently used in the context of mammography, in which case it is an indicator of the views to be obtained (specifically, that additional non-standard views may be performed), not an indicator of the patient’s symptom status. In both cases, diagnostic refers to an exam being performed for the purpose of further work-up. Here we have chosen to model these terms as part of the Reason for exam semantics, rather than the View semantics.

Second, the question of screening and diagnostic exams “for what” may be another source of confusion. Here, we take the position that the answer is typically understood: Screening mammography screens for breast cancer; screening colonography screens for colon cancer. Further, note that the use of the terms Diagnosticand Screening is intended to be limited to those exams where these are needed to distinguish from some other type of study.

We also use the Reason for exam attribute to distinguish studies that are primarily done in the pediatric domain. For example, the codes for bilateral hip ultrasound and cranial ultrasound both have the Reason for exam specified as For pediatrics.

We do not create separate codes with pediatrics as the Reason for exam in cases where the same study is commonly done in both the adult and pediatric population. For example, “Head CT” will be used for both pediatric and adult studies.

Also note that 3D post processing is included here as a value of the Reason for exam attribute. This refers to image rendering done after image acquisition. Some facilities bill for such renderings, which may be used for surgical planning or other purposes. As a result, these renderings (at least sometimes) constitute an end-product of the exam, and we have thereby chosen to model such processing as a reason for performing the exam. While 3D post processing may also be used simply as a diagnostic tool in image interpretation (and thus not technically a reason for performing the study), we have elected to simply model any description of 3D post processing here.

9.2 Examples

Example Example <Reason(s)>
XR Eye Foreign body
MG Breast Diagnostic
MG Breast Diagnostic + Call back
US Pregnancy + Less than 14 weeks
US Multiple gestation + Greater than 14 weeks
NM Stomach Liquid gastric emptying
CT Heart Calcium score

9.3 Notes

  1. 10/17/14: Values removed - “mass,” “obstruction,” “patency,” “pre op”
  2. 10/17/14: Values added – “intra op,” “endograft”
  3. 10/17/14: “Twin pregnancy” replaced with “multiple gestation.”
  4. “Call back” is only to be used in relation to mammography.

10 Guidance

10.1 Definitions

The Guidance attribute is used to describe image-guided interventions. Such procedures may range from the very general (e.g., “CT guided needle placement”) to the very specific (e.g., “fluoroscopy guided lumbar vertebroplasty, with bone biopsy, additional level”).

We recommend using these image-guided intervention terms to represent both the imaging part of the procedure and the intervention itself, so for example, the term for "CT guided needle placement" would be used to order and report both the CT guidance as well as the placement of the needle. If there are use cases for which separate codes are necessary for each of the two aspects, we will determine how best to model those individual concepts, but until we receive feedback from users about such use cases, we will continue to recommend using a single code for both the imaging and the action.

Imaging guidance for procedures is modeled with three sub-attributes:

<Approach>    <Action>    <Object>

Approach refers to the primary route of access used, such as Percutaneous, Transcatheter, or Transhepatic. Action indicates the intervention performed, such as Biopsy, Aspiration, or Ablation. Object is used to specify the target of the action, such as Mass, Abscess or Cyst. For complex procedures, operators may be used to combine instances of the Guidance attribute.

Specific definitions for certain actions and interventions:

  • Aspiration: withdrawal of fluid with a device that is removed at the end of the procedure
  • Drainage: withdrawal of fluid with a device that is left in place at the end of the procedure
  • Thoracentesis: drainage of fluid with placement of chest tube
  • Arthrocentesis: aspiration of fluid from a joint space (this does not include aspiration of soft tissue surrounding the joint)

10.2 Usage Notes

10.2.1 Guidance for.Presence

Image-guided intervention codes are signified with a Guidance for.Presence attribute value of Guidance. This attribute is primarily used as an indicator that one or more of the Guidance for.Approach, Guidance for.Action, and Guidance for.Object attributes will be valued.

10.2.2 Guidance for.Approach

The Approach sub-attribute will generally be included in the formal code specification. For some procedures like fluid aspiration or biopsy, the percutaneous route is the “default” and often assumed route. Local procedure names will often not include the word “percutaneous” in the name. For purposes of modeling, we will include Percutaneous in the attribute specification. But, to avoid extraneous “clutter”, the display name for the pre-coordinated term will only include the approach if we have two variants, one with percutaneous and one with some other route.

In some cases, “percutaneous” may be part of the overall route used for a procedure (e.g., “percutaneous transhepatic”). In such cases, the primary, or most evocative, route will be used (e.g., Transhepatic).

10.2.3 Guidance for.Action

The Action sub-attribute will generally be required to adequately specify an image-guided procedure. Examples include: Placement of; Replacement/Exchange of; Removal of; Repositioning of; Retrieval of; Infusion of; Injection of; Localization of; Check of.

For the Actions biopsy and aspiration, in most cases the type of device used (e.g., needle, fine needle, core needle) does not need to be specified in the procedure name. Therefore, for most terms that include the biopsy or aspiration Actions, we will not include information about the device. In those select cases where a particular type of device is used for a specific purpose, however, we will include the device-specific information in this sub-attribute. For example, percutaneous aspiration of fluid using a fine needle is performed in order to obtain a specimen for cytologic examination, so for this context we will make terms that have aspiration.fine needle as the Action.

10.2.3.1 Aspiration and Drainage

We have adopted the American College of Radiology and American Medical Association's definitions of aspiration and drainage as described above. Based on those definitions, any term that specifies drainage will also specify placement of a drainage catheter and vice versa, as follows:

Guidance for drainage + placement of drainage catheter

Terms that specify chest tube placement are not required to also specify drainage because chest tube placement can be done without draining fluid, such as for patients with a pneumothorax.

10.2.3.2 Injection and Nerve block

For terms that specify a nerve or set of nerves as the Anatomic focus, such as Peripheral nerve or Celiac plexus, the Action should be Nerve block. For those that have a more generic focus such as Spine.lumbar, then Injection may be used.

10.2.4 Guidance for.Object

The Object sub-attribute specifies the target of the Action and can represent a variety of concepts, including a device that is being manipulated, a biological substance, or a pathologic lesion. Examples include: Drainage catheter, Nephrostomy tube, CSF, Calculus, Abscess.

Note that the Object sub-attribute is optional. Some procedures will specify an Action as well as an Object, while others may only specify an Action. For example:

Guidance for aspiration
Guidance for aspiration of CSF

Beginning with LOINC version 2.66, the LOINC/Radlex Committee agreed upon a constrained list of values for the Object associated with the Aspiration and Drainage Actions in order to prevent an explosion of terms for very similar concepts that are sometimes difficult to distinguish. This list contains the concepts listed below. Requests for new, more specific values will be considered by the Committee on a case-by-case basis.

  • Fluid
  • Abscess
  • Hematoma
  • Cyst
  • CSF
  • Amniotic fluid
  • Urine

The Committee also decided that Drainage catheter will be the preferred Object for the Placement Action, but specific named catheters such as Chest tube and Nephrostomy tube will also be allowed.

10.2.4.1 Relationship between Anatomic Location and Guidance for.Object

For most procedures, the body region or organ of interest is specified outside of the Guidance attribute, using the Anatomic Location attribute. On the other hand, when there is a specific site of pathology targeted by an intervention, this is modeled using the Guidance for.Object sub-attribute. The expectation is that when normal anatomic specifiers such as Liver or Abdomen are used, these are modeled using Anatomic Location. When a site of disease such as Mass or Abscess is described, this is modeled using Guidance for.Object.

In some cases, neither Anatomic Location nor Guidance for.Object will be specified (e.g., “US guided fine needle aspiration”).

10.2.5 Modality attribute

The Guidance attribute will generally be used in conjunction with the Modality attribute. Recall that the modality code {Imaging modality} is used for image-guided procedures where the particular imaging modality is not specified (e.g., “image guided liver biopsy”).

10.2.6 Specifying more than one procedure

Although uncommon, the syntax above can also be used to specify more than one procedure by repeating the triplet of sub-attributes (remember, only the Action sub-attribute is required).

As defined in the Syntax section (2.1), use of “+” to join two procedures means logical conjunction (i.e., both procedures were done).

For example:

Guidance for cholangioscopy+removal of calculus

10.3 Examples

Example <Anatomic Loc> <Approach> <Action> <Object>
CT Liver Percutaneous Biopsy
CT Liver Percutaneous Biopsy Mass
US Percutaneous Placement Non-tunneled CVC
US Pleural space Percutaneous Drainage
US Thyroid Percutaneous Aspiration Fluid
{Imaging modality} Percutaneous Placement Drain
{Imaging modality} Percutaneous Drainage Abscess
{Imaging modality} Gallbladder Transhepatic Placement Drain
{Imaging modality} Percutaneous Biopsy
{Imaging modality} Percutaneous Exchange Gastrojejunal tube

11 Subject

11.1 Definitions

The Subject attribute is intended for use when there is a need to distinguish between the patient associated with an imaging study, and the target of the study. This situation may occur for pregnant patients undergoing prenatal imaging exams. The potential for multiple gestation further motivates the need for the Subject attribute, as an exam may be targeted at a particular one of multiple fetuses. The Subject attribute may also be used in cases of surgical specimens, such as specimen radiographs at lumpectomy.

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