Orientation to Scanning

Diane M. Kawamura

OBJECTIVES

Identify anatomic definitions for directional terms, anatomic position, and anatomic planes.
Demonstrate the sonography examination to include patient position, transducer orientation, image presentation, and image labeling.
Define the terms used to describe image quality.
Describe the echo patterns demonstrating how normal and pathologic conditions can be defined using image quality definitions.
List and recognize the sonography criteria for cystic, solid, and complex conditions.
Describe the appropriate patient preparation for a sonography evaluation.
State what should and what should not be included in the sonographer’s documentation of the sonography examination.
Calculate sensitivity, specificity, and accuracy using the four outcomes of true positive, false positive, true negative, and/or false negative.

GLOSSARY

anechoic describes the portion of an image that appears echo-free

echogenic describes an organ or tissue that is capable of producing echoes by reflecting the acoustic beam

echopenic describes a structure that is less echogenic or has few internal echoes

heterogeneous describes tissue or organ structures that have several different echo characteristics

homogeneous refers to imaged echoes of equal intensity

hyperechoic describes image echoes brighter than surrounding tissues or brighter than is normal for that tissue or organ

hypoechoic describes portions of an image that are not as bright as surrounding tissues or are less bright than normal

isoechoic describes structures of equal echo density

This chapter focuses on the sonography examination of the abdomen and superficial structures. It was written to assist sonographers in acquiring, using, and understanding the sonographic imaging terminology used in the remainder of this textbook. Accurate and precise terminology allows effective communication among professionals.

The textbook is divided into five sections: introduction to sonography, abdominal sonography, superficial structure sonography, neonatal and pediatric sonography, and special study sonography.

ANATOMIC DEFINITIONS

The profession adopted standard nomenclature from the anatomists’ terminology to communicate anatomic direction. Table 2-1 and Figure 2-1 illustrate how these simple terms help avoid confusion and provide specific information. A person in the conventional anatomic position stands erect, with feet together, the arms by the sides, and the palms and face directed forward, facing the observer. When sonographers use directional terms or describe regions or anatomic planes, it is assumed that the body is in the anatomic position.

There are three standard anatomic planes (sections), which are imaginary flat surfaces passing through a body in the standard anatomic position. The sagittal plane and coronal plane follow the long axis of the body and the transverse plane follows the short axis of the body¹ (Fig. 2-2).

The word sagittal literally means “flight of an arrow” and refers to the plane that courses vertically through the body and separates it into right and left portions. The plane that divides the body into equal right and left halves is referred to as the median sagittal or midsagittal plane. Any vertical plane on either side of the midsagittal plane is a parasagittal plane (para means “alongside of”). In most sonography cases, the term sagittal usually implies a parasagittal plane unless the term is specified as median sagittal or midsagittal. The coronal plane courses vertically through the body from right to left or left to right, and it divides the body into anterior and posterior portions. The transverse plane passes through the body from anterior to posterior and divides the body into superior and inferior portions and courses parallel to the surface of the ground.

TABLE 2-1 Directional Terms

Term	Definition	Example
Superior (cranial)	Toward the head, closer to the head, the upper portion of the body, the upper part of a structure, or a structure higher than another structure	The left adrenal gland is superior to the left kidney.
Inferior (caudal)	Toward the feet, away from the head, the lower portion of the body, toward the lower part of a structure, or a structure lower than another structure	The lower pole of each kidney is inferior to the upper pole.
Anterior (ventral)	Toward the front or at the front of the body or a structure in front of another structure	The main portal vein is anterior to the inferior vena cava.
Posterior (dorsal)	Toward the back or the back of the body or a structure behind another structure	The main portal vein is posterior to the common hepatic artery.
Medial	Toward the middle or midline of the body or the middle of a structure	The middle vein is medial to the right hepatic vein.
Lateral	Away from the middle or the midline of the body or pertaining to the side	The right kidney is lateral to the inferior vena cava.
Ipsilateral	Located on the same side of the body or affecting the same side of the body	The gallbladder and right kidney are ipsilateral.
Contralateral	Located on the opposite side of the body or affecting the opposite side of the body	The pancreatic tail and pancreatic head are contralateral.
Proximal	Closer to the attachment of an extremity to the trunk or the origin of a body part	The abdominal aorta is proximal to the bifurcation of the iliac arteries.
Distal	Farther from the attachment of an extremity to the trunk or the origin of a body part	The iliac arteries are distal to the abdominal aorta.
Superficial	Toward or on the body surface or external	The thyroid and breast are considered superficial structures.
Deep	Away from the body surface or internal	The peritoneal organs and great vessels are deep structures.

SCANNING DEFINITIONS

Patient Position

Positional terms refer to the patient’s position relative to the surrounding space. For sonographic examinations, the patient position is described relative to the scanning table or bed (Table 2-2 and Fig. 2-3). In clinical practice, patients are scanned in a recumbent, semierect (reverse Trendelenburg or Fowler), or sitting position. On occasion, patients may be placed in other positions, such as the Trendelenburg (head lowered) or standing position, to obtain unobscured images of the area of interest. Sonographers frequently convey information on patient position and transducer placement simultaneously. This terminology most likely was adopted from radiography, where it describes the path of the X-ray beam through the patient’s body (projection), which results in a radiographic image (view). There is no evidence in the literature that this nomenclature has been adopted as a professional standard for sonographic imaging. Describing sonograms using the terms projection or view should be avoided. It is more accurate to describe the sonography image by stating the anatomic plane visualized, owing to the

transducer’s orientation (i.e., transverse). A more specific description of the image would include both the anatomic plane and the patient position (i.e., transverse, oblique).

FIGURE 2-1 Directional terms. The drawing depicts a body in the anatomic position (standing erect, arms by the side, face and palms directed forward) with the directional terms. The directional terms correlate with the terms in Table 2-1.

FIGURE 2-2 Anatomic planes. The standard anatomic position is used to depict the three imaginary anatomic flat surface planes. Both the sagittal and coronal planes pass through the long axis and the transverse plane passes through the short axis. (Reprinted with permission from Stephenson SR, Dmitrieva J. Obstetrics and Gynecology. 4th ed. Wolters Kluwer; 2018.)

TABLE 2-2 Patient Positions

Term	Description
Decubitus or Recumbent	The act of lying down. The adjective before the word describes the most dependent body surface.
Supine or dorsal	Lying on the back
Prone or ventral	Lying face down
RLD	Lying on the right side
LLD	Lying on the left side
Oblique	Named for the body side closest to the scanning table.
RPO	Lying on the right posterior surface, the left posterior surface is elevated
LPO	Lying on the left posterior surface, the right posterior surface is elevated
RAO	Lying on the right anterior surface, the left anterior surface is elevated
LAO	Lying on the left anterior surface, the right anterior surface is elevated
LAO, left anterior oblique; LLD, left lateral decubitus; LPO, left posterior oblique; RAO, right anterior oblique; RLD, right lateral decubitus; RPO, right posterior oblique.

FIGURE 2-3 Patient positions. The various patient positions depicted in the illustration correlate with the descriptions in Table 2-2. LAO, left anterior oblique; LPO, left posterior oblique; RAO, right anterior oblique; RPO, right posterior oblique.

Transducer Orientation

The transducer’s orientation as viewed on the monitor is the path of the insonating sound beam and the path of the returning echoes. Transducers are manufactured with an indicator (notch, groove, light) that is displayed on the monitor as a dot, arrow, letter of the manufacturer’s insignia, or other delineation. Scanning plane is the term used to describe the transducer’s orientation to the anatomic plane or to a specific organ or structure. The sonographic image is a representation of sectional anatomy. The term plane combined with the adjectives sagittal, parasagittal, coronal, and transverse describes the section of anatomy represented on the image (e.g., transverse plane).

Because many organs and structures lie oblique to the imaginary body surface planes, sonographers must identify sectional anatomy accurately to utilize a specific organ and structure orientation for scanning surfaces. The sonography imaging equipment provides a lot of flexibility to rock, slide, and angle the transducer to obtain sectional images of organs oriented obliquely in the body. For example, to obtain the long axis of an organ, such as the kidney, the transducer is placed obliquely and is angled off of the standard anatomic positions: sagittal, parasagittal, coronal, or transverse plane. Sonographers frequently use the terms sagittal or parasagittal to mean longitudinal in depicting the anatomy in a long-axis section. Although some images in this text are labeled sagittal or parasagittal, they are, in fact, longitudinal planes because the image is organ specific. For
organ imaging, transverse planes are perpendicular to the long axis of the organ, and longitudinal and coronal planes are referenced to a surface. All three planes are based on the patient position and the scanning surface (Fig. 2-4A-C).

Image Presentation

When describing image presentation on the display monitor, the body, organ, or structure plane terminology, coupled with transducer placement, provides a very descriptive portrayal of the sectional anatomy being depicted. Current flexible, freehand scanning techniques may lack automatic labeling of the scanning plane. With the freehand scanning technique, quantitative labeling may be limited, which means reduced image reproducibility from one sonographer to another. Sonographers can usually select from a wide array of protocols for image annotation or employ postprocessing annotation. This is extremely important when the image of an isolated area does not provide other anatomic structures for a reference location. To ensure consistent practice, sonographers must correctly label all sonograms. With today’s equipment, standard presentation and labeling are easily achieved along with additional labeling of specific structures and added comments.

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