Prin Principl ciples es of Radiographic Radiographi Radio graphic c Principles Interpretation Pro Pr of . H ossam K an di dil l Ora Or al and M axi l l of aci al Rad Radi ol ogy Caii r o U ni ver si ty Ca Chapter 15 (Pages 281-296)
Objective of this topic
To provide step by step, analytic process that can be applied to the interpretation of diagnostic images. However, reading this topic will not immediately give the ability to interpret radiographic films correctly; rather, it will equip the reader with a systematic method of image analysis. Proficiency comes only with practice
Acquiring Appropriate Appropriate Diagnostic Images * Quality of the diagnostic image
Elongated
Length of a root canal
Density and contrast osteoporosis in an overexposed images can not be seen
Acquiring Appropriate Appropriate Diagnostic Images (Cont.)
Number and type of available images:
- Caution should be exercised in attempting to make an interpretation based on a single film, especially if the only film is a panoramic view. - Periapical and bitwing films often can be supplemented.
Acquiring Appropriate Diagnostic Images (Cont.)
Viewing conditions
- Ambient (Surrounding) light in the viewing room should be reduced. - Films should be mounted in a film holder. - Light from viewing box should be equally distributed. - An intense light is used for dark areas. - Magnifying lens for detailed examination.
Image Analysis Systematic Radiographic Examination
Intra-Oral Images:
- It is most important for the practitioner to develop a particular method and to use it regularly. Examine radiographs.
periapical
before
bitewing
- Starting in the right maxilla to the left and then dropping down in the left mandible to the right.
Systematic Radiographic Examination (Cont.) 1- Concentrate on one anatomic structure at a time. * Examine the bone, identify all anatomic landmarks for the region. eg, maxillary sinus, tuberosity and zygomatic bone for maxillary posterior area. Compare both sides. * Density and size of the trabecular bone.
Systematic Radiographic Examination (Cont.) 2- Next, Make a second circuit through all the images examining, - Hight of the alveolar process .( Active or past periodontal disease, any areas of erosion of the alveolar crest and thickness of the ovelying mucosa- Carcinomas-) - Examine the trabecular pattern of the alveolar process.
Systematic Radiographic Examination (Cont.) 3- Finally, make a third visual circuit, examining the dentition and associated structures. - Count the teeth. - Examine the crown for normal development of the enamel for caries, especially interproximal below the contact area. - Recurrent caries. - Examine the pulp chamber for size and contents. - Roots for shape and form. - width of the PDL. - The lamina dura. N.B. The most common abnormalities found in the bone are radiolucent or radiopaque lesions at the apices of teeth.
Systematic Radiographic Examination (Cont.)
Extra-Oral Radiographs: The most commonly used EO radiographs are panoramic, cephalometric and temporomandibular views.
The same general principles of thorough, systematic coverage should be used
Systematic Radiographic Examination(Cont.)
When an intraosseous lesion is identified, the following five steps should be used to analyze the lesion as fully as possible. Localize the abnormality. Assess the periphery and shape. Analyze the internal structure. Analyze the effects of the lesion on surrounding structures. Formulate a radiographic interpretation.
Analysis of intraosseous lesions
Two basic approaches can be used:
1- Picture matching “Aunt Minnie”: Trying to match the radiographic image with a mental picture or with an image in a textbook. 2- A step by step analysis of all the radiographic characteristics of the abnormality and production of a radiographic interpretation based on these findings. Preferred method .
Aunt Minnie
Periapical Cemental Dysplasia(PCDs) PCD left after extraction (Not applied)
Step 1- Localize the Abnormality
Localized or Generalized.
Position in the Jaws.
Single or Multifocal.
Size.
Localized or Generalized
Try to describe the anatomic location and limits of the abnormality. - Some lesions are localized to a specific region. - It may be unilateral or bilateral
Fibrous dysplasia
May be it is a normal anatomy, submandibular gland fossa or it can be a disease like paget’s disease of bone
Cherubism
Bilateral, manifesting in both the left and right mandibular rami
Localized or Generalized (Cont.)
Generalized: If an abnormal appearance affects all the osseous structures of the maxillofacial region, generalized conditions such as metabolic or endocrine abnormalities of bone are considered.
Position in the Jaws
Is the abnormality in soft tissue or is it contained within the jaws? When the lesion is in the bone, the point of origin or the epicenter can be estimated. The point of origin may indicate the tissue types that compose the abnormality.
Position in the Jaws (Cont.)
Examples: - The epicenter is coronal to a tooth or above the inferior alveolar canal(IAC) Odontogenic in origin - The epicenter is below the IAC it is unlikely to be odontogenic in origin. - Originates with the IAC the tissue of origin probably is neural or vascular in nature - If the epicenter is within the maxillary antrum the lesion is non-odontogenic in origin
Epicenter is coronal
Epicenter is below the IAC
Epicenter is above the IAC
Epicenter within the sinus Epicenter within the IAC
Position in the Jaws (Cont.) Particular lesions tend to be found in specific locations - The epicenters of central giant cell granulomas commonly are located anterior to the first molars in the mandible and anterior to the cuspid in the maxilla. - Peripaical cemental dysplasia (PCD) occurs in the periapical region of lower anterior teeth.
Single or Multifocal
Multifocal (the list is short)
- PCDs - Odontogenic Keratocysts (OKCs) - Metastaic lesions. - Multiple myeloma. - Leukemic infiltrates.
Size
There are very few size restrictions for a particulate lesion. But the size may aid in DD. A dentigerous cyst is often larger than a hyperplastic follicle.
Step 2- Assess the Periphery and Shape
Periphery of the lesion: Well-defined
Is one in which most of the periphery is well defined
Ill-defined Difficult to draw an exact delineation around the periphery
Periphery of the lesion: Subcategories
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-
-
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Well Defined Borders Punched out border: A sharp boundary in which no bone reaction is apperant immediately adjacent to the abnormality. eg Multiple myeloma. A Corticated margin: Thin fairly uniform radiopaque line of reactive bone at the periphery of a lesion.eg cysts A Sclerotic margin: Wide radiopaque border of reactive bone that usually not uniform in width.eg PCDs A RO lesion may have a soft tissue capsule which is indicated by the presence of radiolucent line at the periphery.eg Odontomas
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-
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Ill Defined Borders A blending border is illdefined because of the gradual transition between normal – appearing bone trabeculae and the abnormal-appearing trabeculae of the lesion. eg. Sclerosing osteitis and fibrous dysplasia. An invasive border usually is associated with rapid growth.eg. Malignant lesions Enlargement of the marrow spaces at the periphery eg. Malignant
Examples (Well-defined)
Punched out border.
Sclerotic Margin
Corticated Margin
Radiolucent Periphery
Examples (Ill-Defined)
Sclerosing osteitis
Invasive Margin (SCC of Ant Maxilla)
Enlargement of small marrow spaces
Step 2- Assess the Periphery and Shape (Con.)
Shape: The lesion may have a particular shape or it may be irregular.
- A circular or fluid filled shape is a characteristic of a cyst. - A scalloped shape (reflects the mechanism of growth). May be seen in cysts (OKCs), cyst like lesions (simple bone cyst) and some tumors.
Shape
Inflated Baloon (Circular)
Scalloped (OKCs)
Step 3- Analyze the Internal Structure
Classified into one of three basic categories: - Totally Radiolucent. (Common in cysts) - Totally Radiopaque. (Common in osteomas) - Mixed Radiolcent and Radiopaque
Is seen as the presence of calcified structures against a radiolucent background. eg. Bone, enamel (examine the shape, size and pattern of this calcified structures).
List of the most RL to the most RO material seen in plain radiographs Air, fat and gas Fluid Soft tissue Bone marrow Trabecular bone Cortical bone and dentine Enamel Metal N.B. A large amount of cortical bone may be as radiopaque as enamel.
List of a few possible internal structures in mixed density lesions
Abnormal Bone
Differ in number, length, width and orientation of the trabeculae. e.g.: Fibrous dysplasia Greater in number, shorter and not aligned in response to applied stress to the bone but are randomly oriented giving the pattern described as orange peel or ground-glass appearance
List of a few possible internal structures in mixed density lesions (Cont.)
Septa: Represent residual bone that has been organized into long strands or walls.
Multilocular: If these septa divide the internal structure into at least two compartments, the term multilocular is used
Unilocular: No septa inside the lesion
List of a few possible internal structures in mixed density lesions (Cont.)
The length, width and orientation of the septa can be assessed. Curved, coarse septa (Soap bubble appaearance) e.g. Ameloblastoma and OKC Tennis racket and granuular
appaearance can be seen in
odontogenic myxoma with sharp angles septa
Smaller locules, honey comb term is used
List of a few possible internal structures in mixed density lesions (Cont.) Dystrophic Calcification: Occurs in damaged soft tissue. e.g. - Calcified lymph nodes (cauliflower-like masses in the soft tissue) - Chronically inflamed cysts Cementum: Homogeneous, dense, amorphous structure, oval or round in shape. Tooth Structure: Identified by the organization into enamel, dentin, and pulp chamber
Step 4 - Effect on adjacent structures
The following structure are to be checked: The teeth: there may be evidence of
Resorption
Displacement
Disrupted development
Delayed eruption
hypercementosis
Effect on adjacent structures Surrounding bone: There may be evidence of:
•
Expansion: buccal, lingual, other
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Effect on adjacent structures Surrounding bone: There may be evidence of: •Expansion: buccal, lingual, other
•
Effect on adjacent structures Surrounding bone: There may be evidence of: •Expansion: buccal, lingual, other
•
Effect on adjacent structures
Surrounding bone:
There may be evidence of:
Displacement of: inferior dental canal, mental foramen, antra, lower border of the mandible, nasal cavity and orbits.
Effect on adjacent structures
Surrounding bone:
There may be evidence of:
Ragged destruction Alteration of normal trabecular pattern.
Effect on adjacent structures
Surrounding bone:
There may be evidence of:
Subperiosteal new bone formation. Giving the appearnce of onion-skin pattern (mostly in inflammatory lesion as osteomyelitis and rarely in some malignant lesions as leukemia. Some periosteal reactions are very specific (New bone formed at right angles to the outer cortical plate, e.g. Metastatic lesions of prostate) or ( Radiating pattern, e.g. osteogenic sarcoma)
Importance of recognition of the effect on adjacent structures
Ab tend to grow and infiltrate in all directions. Keratocyst tend to grow and infiltrate through the cancellous bone along the body of the mandible and produce little expansion. The more dangerous the lesion, the more damaging and destructive its effect.
Step 5- Formulate a Radiographic Interpretation
Decision 1- Normal Versus Abnormal.
Decision 2- Developmental Versus Acquired.
Decision 3- Classification.
Decision 4- Ways to Proceed.
