Radiographic interpretation

RADIOGRAPHIC INTERPRETATION

Guided by:Dr Vela DesaiDr Beena VarmaDr Neelkanth PatilDr Rajeev Sharma

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Radiograph

Photographic image Radiosensitive surface Radiation – X rays/ Gamma rays Radiogram/shadowgram/roentgenogram

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Role of radiographs

Clinical examination phase Diagnosis( confirm/exclude) Treatment planning During treatment Follow up Blind screening tool-justify Limitations-replace clinical examination Need for further investigation

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Radiographs in Diagnosis

Diagnostic imaging is an integral part of the diagnostic process in clinical dentistry.

Radiographs are often obtained as part of a complete examination. Appropriate radiographic interpretation is

used along with clinical information and other tests to formulate a differential diagnosis


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Uses of radiographs

Loss of tooth structure Caries(occlusal/proximal) Non carious(attrition,fracture) Periodontal diseases Endodontic diseases Impacted teeth Trauma Other bone pathologies Implants

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Technique Radiography Interpretation Radiology Interpretation: Step by step analytical process that

provides an exact idea of the clinical problem and helps to achieve the final diagnosis of any particular lesion.

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Interpretation

Three steps: Visualization Perception Integration of information Other diagnostic tools-vitality/mobility Pulp tester

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Clinical examination

Type of radiograph

Number of radiographs

Aids in interpretation

Quality assurance Inadequate

quality Inadequate

number Extraoral

radiology Biopsy/treatment-

aids in site selection

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FULL MOUTH INTRAORAL RADIOGRAPHS-IOPA & BITEWING

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Ideal radiograph: Visual : density & contrast Geometric : sharpness/detail,

resolution/definition, magnification, distortion

Anatomical accuracy of radiographic images

Adequate coverage of anatomical region of interest.

NEVER INTERPRET A FAULTY RADIOGRAPH

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Viewing Conditions

This should be done in a quiet, darkened room At least two good, evenly-lit viewing boxes are

required A bright light illuminator is required for

relatively over-exposed areas Mounted in holder Appropriate size of viewbox to accommodate

film Magnifying glass-detailed examination of small

regions

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A radiograph is a two dimensional image of a three dimensional object.

Clark’s rule: The most distant object from the cone(lingual) moves towards the direction of the cone

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Three-dimensional concept

The radiographic image is simply a Two-dimensional shadowgram of the

patient The third dimension must be reconstructed

mentally, preferably from two radiographic projections made at right angles (orthogonal projections) to each other

Oblique projections may be required to assess anatomically complicated areas

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Contrast perception:

Ability to distinguish b/w two areas of radiographic image of diff densities-Weber’s law

Minimum perceptible difference in gray level is proportional to the brightness level to which the subject is adapted.

All areas on a radiograph represented as: Black Grey White

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MACH BAND EFFECT

Illusion consists of light or dark stripes that are perceived next to the boundary between two regions of an image that have different lightness gradients

Spatial high-boost filtering performed by the human visual system on the luminance channel of the image captured by the retina.

Mach bands are independent of orientation.

This occurs when two circles of uniform brightness are placed side by side, separated by a sharp edge. Just along the edge one colour looks darker than it really is, while the other looks lighter.

11/04/202316 MACH BAND EFFECT

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False-positive radiological diagnosis of dental caries

Manifest adjacent to metal restorations or appliances, between enamel and dentin

Misdiagnosis of horizontal root fractures because of the differing radiographic intensities of tooth and bone.

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RADIOLUSCENT-the capability of a substance with a relatively small atomic number to let a large amount of x-rays pass through it, thus producing darkened images on x-ray films.

RADIOOPACITY-the capability of a substance to hinder or completely stop the passage of x-rays, display as white/light areas on an exposed x-ray film.

RADIOOPAQUE

RADIOLUSCENT

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Properties

Atomic number The higher the atomic number, the more

radiopaque the tissue/object: Physical opacity

Air, fluid and soft tissue have approximately the same atomic number, but the specific gravity of air is only 0.001, whereas that of fluid and soft tissue is 1

Therefore air will appear black on a radiograph, compared with fluid and soft tissue, which appear more grey


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Thickness The thicker the tissue/object, the greater

the attenuation of X-Rays and the more white the image .

When two tissues/objects are superimposed, the composite shadow formed by these will appear more opaque than either of the two separate tissues

Bone(14;1.8)

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Image analysis

Identify normal anatomic landmarks Knowledge of normal v/s abnormal Attention to all regions on the film

systematically Three circuits

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First visual circuit: intraoral images Periapical before bitewing images Right maxilla to left; left mandible to

right One anatomic structure at a time Eg: posterior maxilla-maxillary

sinus,tuberosity,zygomatic process Normal anatomy bones, canals, foraminaCheck for symmetry

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Use a systematic process

Go back to the first quadrant and look at the trabecular pattern. Is it:

Normal Symmetrical when compared to the

contralateral side Sparse Dense In the direction of anatomical stress Altered

11/04/202324 TRABECULAR PATTERN

Step ladder Fish net

Granular


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Second visual circuit

Examination of bone: Height of alveolar bone Crest relative to teeth Loss of height-more than 1.5 mm-

periodontal disease Cortication Lamina dura + PDL space + tooth roots Carcinoma-erosion of alveolar crest+ ill

defined borders.

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Third visual circuit

Examination of dentition & associated structures

Number, Sequence, appearance, root structure

Crowns –defective enamel, caries Intreproximal areas & restorations Pulp chambers-size, content Bone-radioluscent/radioopaque lesions

Restoration

Proximal caries

Pulp

Dentin


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Check individual teeth

Enamel, [amelogenesis imperfecta, mulberry molar, etc.]

The dentin, [dens invaginatus or evaginatus, denticles etc.] T

Pulp chamber [dentinogenesis imperfecta, odontogenesis

imperfecta, odontodysplasia, taurodontism, individual

obliteration of nerve canals, etc.]

Apical area [root resorption, lucencies or opacities]

periodontal ligament space [widened in early osteosarcoma

(localized), scleroderma ( generalized) [ absent in

hyperparathyroidism]

Amount of bone support.

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Routine assessment of radiographs

Ensure that the radiograph is the one of the patient being examined, check the date, opd/no.

Ensure two orthogonal projections are available. The radiographic views are named according to the

direction the primary beam enters and leaves the tissue and the body part being examined

The position of the patient during exposure should be known, and left/right markers should be identified

The radiograph should be of high technical quality with respect to positioning, centring, collimation, exposure and development, and should be free from artefacts.


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Every shadow visible must be evaluated to determine whether it is: A feature of normal anatomy A composite structure formed by

superimposition of structures An artefact produced by inaccurate

positioning A pathologic lesion: must be ruled out first

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Interpretation is an orderly process

Normal variation

Abnormal

Developmental abnormalities

Acquired abnormalities

Cyst Benign neoplasia

Vascular analomy

MetabolicInflammatorylesion

Malignant neoplasia

Bone dysplasia

Trauma


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Why describe the lesion?

The radiographic description can give us indications of:

Tissue of origin Biological behavior Prognosis Treatment concerns Diagnosis or a Differential Diagnosis


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Describing the Lesion

1. Size2. Shape3. Location4. Density5. Borders6. Internal Architecture7. Effect on adjacent structures

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Aunty Minnie Approach

Aunt Minny represents an abnormality which looks like one that the evaluator has seen before, or been told about.

It would be difficult to recognise new findings using this approach

Cousin Harry represents an abnormality which the evaluator has not seen for a long time, but would like to see

Uncle Fred represents an abnormality which is often present


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One only sees on a radiograph what

one already knows

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Size

Measure the lesion with a ruler. If you

must estimate, use surrounding structures as guide

Measure in two dimensions, width and height in mm or cm

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Shape

Odontogenic keratocyst

Regular shapes like Round, Triangular, Rhomboid etc.

Irregular shape like circular, fluid filled(hydraulic)-cyst

Scalloped-multilocular app.

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Scalloped/Multilocular-Ameloblastoma

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Location

Is the lesion localized or generalized? Unilateral or bilateral(submandibular fossa), fibrous dysplasia Where is the lesion in relation to other

structures and anatomic landmarks? Use terms such as: Mesial, Distal Inferior, Superior Posterior, Anterior

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Soft tissues or jaws:

Epicentre-coronal to tooth-odontogenic epithelium

Epicenter of the lesion is above the mandibular canal->odontogenic in origin

Epicentre->below IAC->non odontogenic(likely) Cartilaginous lesions, osteochondromas -

>condyles If the epicenter of the lesion is in the sinus, not

odontogenic in origin-alveolar process of maxilla

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Density

Is the lesion Radiopaque, Radiolucent, or Mixed Density

Remember that opacity is relative to the adjacent structures.

If the lesion is of mixed density, describe the appearance

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Radioluscent to radioopaque structures

Air,fat,gas Fluid Soft tissue Bone marrow Trabecular bone Cortical bone Enamel Metal


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Internal architecture

Is the lesion uniform? Internal structures such as septae or

loculations Septae –residual bone-long strands/walls Loculations are individual compartments(2) Soap bubble app- OKC Giant cell granuloma-wispy, granular Odontogenic myxoma-straight, thin Tooth-like elements-cementum

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Fibrous dysplasia

More in number Shorter Aligned in response to stress Randomly oriented Ground glass/orange peel app


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Calcified lymph nodes-tuberculosis

Inflammatory lesion-new bone formation-thick trabeculae-more radioopaque

Dystrophic calcifications-damaged soft tissue masses- calcified lymph nodes-cauliflower like masses

Ewing’s sarcoma-onion skin app

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Borders

Well or poorly demarcated Punched out-sharp- (no bony reaction)- multiple myeloma Corticated-uniform-periphery- (thin opaque border) cyst Sclerotic (wide, uneven opaque border) Periapical cemental dysplasia

Radioluscent(periphery)+ corticated Odontoma, cementoblastoma


Periapical cemento osseous dysplasia

Residual cyst

Well defined borders


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Ill defined borders

Gradual transition-normal app bone & abnormal app trabaculae- sclerosing osteitis

Invasive border-bone destruction-malignancy


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Jaw – examine the lesion in the jaw:

· Site – location, extent, solitary, multi-focal or generalised

· Size and shape – measure and describe. This may require one or more views.

· Symmetry – examine contralateral site. Bilateral symmetry is suggestive of a normal variant

· Border – sclerosis, resorption, lack of continuity· Contents – lucent or opaque. Homogenous or

varying density· Association with other structures. Teeth

displaced or resorbing


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Effect on adjacent structures Lesions behaviour & impact on

surrounding structures-identification of disease

Inflammatory disease-bone resorption/formation.

A Space Occupying lesion creates its own space by displacing other structures, such as teeth, maxillary sinus, inferior alveolar canal, etc.


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Epicentre above crown of teeth-follicular cysts-teeth apically

Lesion-ramus of mandible-cherubism-anterior direction

Papilla of developing tooth-lymphoma Widening of PDL, broken lamina dura-

periapical/periodontal abscess Root resoption-periodontitis, trauma, tumors Reactive bone-periphery of lesion-benign

slow growth


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Inferior alveolar canal Superior displacement-fibrous dysplasia Widening of IAN-cortical boundary intact-

benign vascular/neural lesion Irregular widening with cortical

destruction, complete length of canal-malignant neoplasm

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Outer cortical bone/periosteal reactions

Slow growing-new bone-expanding lesion-outer cortical bone maintained

Rapidly growing-periosteum does not respond-missing cortical plate

Exudate from inflammatory lesion-lift periosteum off surface of the surface of cortical bone-periosteum lay down new bone.

Onion skin app-leukaemia, langerhan’s cell histiocytosis

Spiculated new bone-osteogenic sarcoma


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Formulation of radiographic interpretation

Organised fashion Single observation Diagnosis

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Decision 1: Normal V/S Abnormal Decision2: Developmental V/S Acquired Decision 3: Classification Decision 4: Ways To Proceed


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Decision 1: Normal V/S Abnormal

Structure of interest Variation of normal/represents

abnormality


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Decision 2: Developmental V/S Acquired

Area of interest: abnormal Radiographic characterstics: location,

periphery, shape, internal structure, effect on surrounding structures

Indicates developmental/acquired-external root resorption


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Decision 3: Classification

Abnormality Appropriate category Treatment plan


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Decision 4: Ways To Proceed

Analyse images Further imaging like CT, MRI Biopsy Treatment


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SOFT TISSUE.

The examination of the radiographic appearance of soft tissue is all too often overlooked.

This is particularly true on panoramic radiographs.

If the clinical examination determines that soft tissue requires radiographic examination, kVp be reduced when the patient is exposed. Soft tissue structures in the maxillofacial region are often tongue, soft palate, tip and ala of the nose

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Correct terminology

One examines a radiograph and NOT an X-ray. Bear in

mind that an X-ray can not be seen. An X-ray is a

photon / beam of energy.

One does not see infection at the apex of a tooth. What one

does see is the well / poorly demarcated

radiolucency/opacity, x mm by y mms in size at the

apex of tooth number X.

For the same reason one does not speak about a PAP in

radiology.


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Periodontal bone loss is not periodontitis per se.

Stay away from brand names. We do not have a

panorex machine here. Use the word

PANORAMIC radiograph or PAN.

In radiologic terminology, a PA is a postero-

anterior view.


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EXISTING DIAGNOSTIC RADIOGRAPHS

An effective way to reduce unnecessary radiation to the patient is to avoid retaking [recent] radiographs that already exist. It is the clinician's responsibility to obtain these records from earlier health providers where possible.


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The diagnostic process is far from infallible. In any diagnostic procedure there are four possible outcomes:-

1. True positive: The disease is present and correctly identified.

2. False positive: The disease was absent but something on the radiograph convinced the clinician that it was present.

3. True negative: No disease present and correctly determined.

4. False negative: Disease is present but not detected. Occurs much too often

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RADIOGRAPHIC RECORDS The value of radiographs as a part of the integral

records of a patient cannot be overstated. Good radiograph is difficult to match with written

records and the radiograph is more indisputable than a written statement in a court of law provided the name of the patient is indicated as well as the date.

However, this is not a call to expose the patient to ionizing radiation merely for the sake of documentation.

One may not retake radiographs for the sake of improving one's grades. Radiographs legally must be kept for at least 5 years; some authorities state 7 years.


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DOCUMENTATION

Clear medico-legal requirement for documentation of interpretation.

Signed and dated radiographic report must be written with patient's record.

Clinically useful in treatment planning and case presentation.


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Radiographic report

Patient & general information Imaging procedure Clinical information Findings Radiographic interpretation


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RADIOGRAPHIC PRESCRIPTION

Licensed dentist may prescribe radiographs

Examination appropriate radiographic views

Maximum amount of information

Minimum amount of ionizing radiation.

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References

White and pharoah,principles and interpretation.IV edition,pg281-296

W&P. Ch.14. Oral and Maxillofacial Imaging. Farman and NortjeNeill Serman.2000

Dr. Parish P. Sedghizadeh. Radiographic pathology of the head and neck.

Brocklebank L, Dental Radiology, Oxford University Press 1997.

Deforge DH and Colmery BH, An Atlas of Dental Radiology, Iowa State University Press 2000

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THANK YOU

...when you have eliminated the impossible, whatever remains, however improbable, must be the

truth.Sir Arthur Conan Doyle, (Sherlock Holmes)British mystery author & physician (1859 -

1930)

Health & Medicine

Radiographic interpretation