Nematodes

Radiographic terminologies and basic principals

RADIOGRAPHIC TERMINOLOGY AND BASIC PRINCIPLES TO STUDY A RADIOGRAPH

The following points should always be kept in mind before interpreting a radiograph:

                                                                                                                                   

1.      Proper procedures should be adopted before taking a radiograph. Separate precautions and preparations should be performed before taking a radiograph of a certain system or organ. For example, the best image of the thorax is gained during the inspiratory phase of the respiration. This provides the greatest air to tissue ratio, minimum blurring from respiratory motion, and best long scale of contrast to demonstrate the fine vascular marking of the lungs.

2.      Basic terminology described later should be used for the interpretation of each radiograph e.g. radiopaque, radiolucent etc.

3.      It is important to examine each system, cavity, or organ minimum of two views, if possible. It is best to take the dorsoventral (D/V) view and right or left lateral views.

4.      While examining the lung radiograph, it should be kept in mind, the lung the tissue is an important site of metastasis for cancerous cells e.g. osteosarcoma, renal cell carcinoma, transitional cell carcinoma, or urinary the bladder, lymphosarcoma, adenocarcinoma of mammary tissue, etc. The availability of other diagnostic tests e.g., blood work, tissue cytology, etc., can aid the diagnosis of pulmonary neoplasia.

5.      All animals should have a thorough clinical examination prior to the radiographic examination and the results of both can be compared to reach a conclusion.

6.      Interpretation pitfalls

a.       Lack of anatomical knowledge causing false-positive or false-negative determination of an abnormality

b.      Distraction by an obvious lesion

c.       Tunnel vision i.e., failure to look beyond the pre-conceived diagnosis or pre-radiograph bias.

TERMS USED FOR INTERPRETATION OF A RADIOGRAPH

1.      Radiographic Density: when trying to describe the degree of whiteness or blackness of a shadow/region seen on the radiograph it is really to prefer to use the words radiopaque or radiolucent.

a.       Radiopaque: used to describe a degree of whiteness seen on the radiographic image. Objects are radiopaque because they absorb some of the X-ray beams.

b.      Radiolucent: used to describe a degree of blackness seen on the radiographic image.  Objects are radiolucent because they do not absorb very much of the X-ray beam.

c.       Sclerotic: a term used to describe increased radiopacity. It is almost exclusively used with reference to the bone. It implies that there has been the production of new bone to make its tissue density greater.

d.      Lytic/Lysis: the term used to describe a decreased radiopacity or increased radiolucency specifically with reference to bones. This implies an active, often aggressive type of bone destruction. These terms are often modified by adding words that describe the distribution or uniformity of the lytic process and lytic region:

                                                        i.      Focal/Localized: only in one region or one bone

                                                        ii.      Multifocal: in more than one region or bone

                                                        iii.      Uniform: evenly distributed

                                                        iv.      Irregular: meaning non-uniform

                                                        v.      Punctate: size term meaning small and spotty; marked with points of punctures

                                                    vi.      Permeative: numerous small uniformly sized holes

                                                   vii.      Moth-eaten: multiple, medium to small non-uniform sized holes that are often confluent

                                                   viii.      Geographic: single fairly large-sized hole, having a distinct margin

e.       Cavitary: the term used to describe a lesion that is radiolucent in the center and radiodense on the perimeter. Typically it is used to describe a lesion in the lung in which case the center is usually filled with air and the perimeter is soft tissue.

f.        Homogeneous:  it implies a uniform change or an equal change in opacity throughout the region.

g.      Heterogeneous: implies a non-uniform or unequal change in opacity throughout the region affected.

h.      Stippled: appearing as small dots.

2.      Size: when possible measured size should be given. When the actual measurement is not done an estimate should be made. The following terms are also used to reflect size:

a.    Punctate: already discussed

b.    Moth-eaten: already discussed

c.     Miliary: the term used to indicate a very small but uniform size. These are 1-3 mm in diameter. Mostly used to describe very small, distinct, multiple soft tissue shadows seen in the lung parenchyma.

3.      Shape: geometric shape description should be given, whenever possible i.e. circular, spherical, round, ovoid, rectangular, triangular, linear, etc. Additional terms frequently used are as under:

a.     Nodular: round small to medium-sized mass. Multi-nodular can be used in the case of many nodules.

b.    Amorphous: having no definite form or shape. Often used with respect to the new bone formation or mineralization in a soft tissue area.

c.     Fusiform: spindle-shaped, means enlarged in the center and tapering to thin points at both ends.

d.    Truncated: having the ends cut squarely off.

e.     Plicate: folded or extensively pleated e.g. appearance of bowel in case of the presence of a linear foreign body.

4.      Margin/Contour: usually used to describe the surface or perimeter of a shadow e.g. smooth, irregular, interrupted, bumpy, brush-like, distinct, indistinct, etc. Additional terms used are as under:

a.     Lamellar (Lamellated): means a thin layer. Mostly used in describing periosteal new bone formation. These will typically be alternating streaks of quite opaque and not so opaque layers. It resembles the layers or rings seen in a cut onion.

b.    Spiculated: sharp needle-like body.

c.     Tortuous: full of turns. Used in the description of abnormal pulmonary vessels. This means the opposite of the straight course seen with normal vessels.

d.    Border Effacement: loss of visible margin or an organ because there is no contrast surrounding the area.

5.      Distribution: to describe completely how many areas or how much of an organ is involved in the abnormality. In the case of bone, w should be specific as to what region of the bone is involved i.e. epiphysis, apophysis, metaphysis, or diaphysis. Also indicate the proximal vs distal. In the case of soft organs specifically state the region e.g. left or right kidney, is the lesion in the cranial or caudal pole, etc. The following are some terms used for the lesion distribution:

a.     Monostotic: affecting a single bone

b.    Polyostotic: affecting many bones

c.     Diffuse: spread widely through a tissue

d.    Disseminated: scattered, distributed over a large area

e.     Generalized: affecting many parts or all parts of an organ

f.      Unilateral: affecting only one side

g.    Bilateral: affecting both sides

h.    Bilaterally Symmetrical: affecting both sides equally

i.       Focal: isolated to one area or region

j.       Multifocal: multiple areas of involvement

k.    Circumferential: going all the way around a structure

l.       Mural: within the wall.

m. Intraluminal: within the lumen of a tube

6.      Position: the position of a the lesion must be as specifically stated as possible using correct anatomical terms e.g. cranial, caudal, rostral, dorsal, palmar, right, left, proximal, distal, dorsal, ventral, axial, abaxial, etc. With reference to the skeleton following terms could be used:

a.       Malalignment: improperly or abnormally aligned.

b.      Luxation/Dislocation: displacement of a part

c.       Subluxation: improper dislocation

7.       Number: always count the correct number of structures or components or organs present e.g. we should be sure there are 13 thoracic vertebrae in the dog or cat or two kidneys in the animal. If any abnormality is seen it must be indicated.