Principles-of-Radiographic-Interpretation.pdf

ORAL DIAGNOSIS AND DENTAL RADIOLOGY-I Principles of Differential diagnosis and Radiographic Interpretation Assoc. Prof. Büşra Yılmaz School of Dental Medicine Department of Oral and Maxillofacial Radiology [email protected] OUTLINE 1. ESSENTIAL REQUIREMENTS FOR INTERPRETATIONS 2. ANALYTIC/...

ORAL DIAGNOSIS AND DENTAL RADIOLOGY-I Principles of Differential diagnosis and Radiographic Interpretation Assoc. Prof. Büşra Yılmaz School of Dental Medicine Department of Oral and Maxillofacial Radiology [email protected] OUTLINE 1. ESSENTIAL REQUIREMENTS FOR INTERPRETATIONS 2. ANALYTIC/SYSTEMATIC STRATEGY OF INTERPRETATION 3. WRITING A DIAGNOSTIC IMAGING REPORT  Optimum viewing conditions  Understanding the nature and limitations of the black, white and grey radiographic image  Detailed knowledge of the range of radiographic appearances of normal anatomical structures  Detailed knowledge of the radiographic appearances of the pathological conditions affecting the head and neck Digital images should be viewed on bright, high-resolution monitors in subdued lighting  Critical assessment of individual image quality  A systematic approach to viewing the entire radiograph and to viewing and describing specific lesions  Access to previous images for comparison Digital images should be viewed on bright, high-resolution monitors in subdued lighting A systematic approach to viewing radiographs is necessary to ensure that no relevant information is missed. Description of a lesion should include its;  Site or anatomical position  Size  Shape  Outline/edge or periphery  Relative radiodensity and internal structure  Effect on adjacent surrounding structures  Time present, if known. Systematic Approach Step 1: Localize Abnormality 1. Anatomic Position (epicenter) Identification of the geometric center or epicenter of a lesion may assist in determining the cell or tissue types contained within the abnormality in question. Coronal to a tooth, the lesion probably is likely to be odontogenic in origin Anatomic Position (epicenter) • If the epicenter is located superior to the inferior alveolar canal (IAC), the likelihood is greater that it is of odontogenic origin Panoramic image revealing an ameloblastoma within the body of the left mandible. The inferior alveolar nerve canal has been displaced inferiorly to the inferior cortex (arrows), indicating that the lesion started superior to the canal. Anatomic Position (epicenter) If the epicenter is located inferior to the IAC, it is unlikely to be odontogenic in origin; rather, it is more likely to have arisen from nonodontogenic cell sources. Cropped panoramic image displaying a lesion (a submandibular salivary gland or Stafne defect) located inferior to the inferior alveolar canal and thus unlikely to be of odontogenic origin. Anatomic Position (epicenter) If the epicenter is located within the IAC, the lesion is likely neural or vascular in nature Lateral oblique image of the mandible revealing a lesion within the inferior alveolar canal. The smooth fusiform expansion of the canal indicates a neural lesion. Anatomic Position (epicenter) If the epicenter is within the maxillary antrum, the lesion is not of odontogenic origin, as opposed to a lesion that has displaced the antral floor from the alveolar process of the maxilla The lack of a peripheral cortex (arrows) on this retention pseudocyst indicates that it originated in the sinus and not in the alveolar process. Therefore it is unlikely to be of odontogenic origin. Thus some conditions have a predilection for certain areas whilst others develop in one site only. For example, radicular dental cysts develop at the apices of non-vital teeth. The site or anatomical position of a lesion may therefore provide the initial clue as to its identity. 2. Localized or Generalized If an abnormal appearance affects all the osseous structures of the maxillofacial region uniformly, generalized disease processes, such as metabolic or endocrine abnormalities of bone, should be considered. Panoramic radiograph shows groundglass appearance and loss or thinning of lamina dura around all the teeth with secondary hyperparathyroidism related to renal disease 3. Single or Multiple Cropped panoramic image revealing several small punched-out lesions of multiple myeloma (a few are indicated by arrows) involving the body and ramus of the mandible. Step 2: Assess the Periphery and Shape of the Abnormality Periphery- Is the periphery well or poorly defined?  The outline or periphery of lesions is described conventionally as being well defined or poorly/ill defined  If an imaginary pencil can be used to reproducibly and confidently trace the border of the lesion, the border is likely well defined. In contrast, it is difficult to exactly and reproducibly delineate a poorly defined periphery.  The clinician should not become overly concerned if some areas are poorly defined; this may be due to the shape of the lesion or direction of the x-ray beam at that particular location.  A well-defined lesion is one in which most of the periphery is well defined. Well-defined outlines, which may also be: Ill defined outlines, which may: Punched-out, i.e. showing no peripheral bone reaction Blend in with normal anatomy and show a gradual change between trabecular patterns Corticated, i.e. having a thick or thin surrounding radiopaque (white) cortex Show signs of invasion and appear ragged or moth-eaten. Sclerotic, i.e. having a non-uniform radiopaque boundary Encapsulated, i.e. surrounded by a radiolucent (black) line which may be complete or partial Well-Defined Borders Punched-out border A punched-out border is one that has a sharp and very narrow zone of transition; there is no bone reaction immediately adjacent to the abnormality. The term punched out points to something similar to punching a hole in a piece of film or paper with a hole punch. The border of the resulting hole is well defined and the adjacent bone has a normal appearance up to the edge of the hole. This type of border is sometimes seen in multiple myeloma Well-Defined Borders Corticated border A corticated border is one that displays a thin, uniform, radiopaque line of bone at the periphery of a lesion. This is commonly seen with cysts and benign neoplasms or tumors Well-Defined Borders Sclerotic border A sclerotic border is one that shows a wider, more diffuse zone of transition between the lesion and the normal surrounding bone. The radiopaque border represents reactive bone that is usually not uniform in width. This border may be seen in periapical osseous dysplasia and may indicate the ability of the lesion to stimulate the production of surrounding bone Well-Defined Borders Encapsulated  A centrally located radiopaque lesion may be surrounded by a radiolucent rim of variable width.  Histologically, the radiolucent rim represents nonmineralized connective tissue and is sometimes referred to as a “soft tissue capsule.” Periapical image revealing a radiopaque mass associated with the root of the first premolar. The prominent radiolucent periphery (arrows) is characteristic of a connective tissue capsule of this cementoblastoma. Thin, radiolucent periphery indicates a connective tissue capsule positioned between the internal radiopaque structure of this odontoma and the radiopaque outer cortical boundary (arrows) Poorly/ill Defined Borders Blending border Invasive border Poorly/ill Defined Borders Blending border  A poorly defined border is one that is difficult to resolve.  The zone of transition is often gradual and wide between the adjacent normal bone trabeculae and the abnormal-appearing trabeculae of the lesion.  The focus of this observation is on the trabeculae rather than the radiolucent marrow spaces.  Examples of conditions with this type of margin are sclerosing osteitis and fibrous dysplasia. Periapical image shows a gradual transition from the dense trabeculae of sclerosing osteitis (short arrow) to the normal trabecular pattern near the crest of the alveolar process (long arrow). This is an example of a poorly defined blending border. Poorly/ill Defined Borders An invasive border is one in which there are few or no trabeculae between the periphery of the lesion and the normal bone. Furthermore, the zone of transition is typically wide. Invasive borders are usually associated with rapid growth and can be seen with malignant lesions. Periapical (A) and occlusal (B) images reveal a squamous cell carcinoma in the anterior maxilla. The invasive margin extends beyond the lateral incisor (arrow), and the radiolucent region with no apparent trabeculae represents bone destruction behind this margin Shape Shape of the lesion is described using one or more of the following terms: ● Unilocular ● Multilocular ● Round ● Oval ● Scalloped or undulating ● Irregular Scalloping describes a series of contiguous arcs or semicircles that may develop around the roots of teeth or within adjacent bone or bone cortices. This shape may be seen in cysts (e.g., odontogenic keratocyst), cyst-like lesions (e.g., simple bone cysts), and some benign neoplasms. Cropped panoramic image of an odontogenic keratocyst displaying a scalloped border, especially around the apex of the associated teeth (arrows) Step 3: Assess the Internal Structure 1. Radiolucent -Total radiolucency is characteristic of a lesion where the normal bone has been completely resorbed. This is commonly seen in cysts. 2. Radiopaque -Total radiopacity implies that the lesion is filled with some sort of mineralized matrix; this is observed in osteomas. Step 3: Assess the Internal Structure Orange peel– or ground glass– like appearances Trabeculae are usually greater in number, shorter, and randomly oriented Internal Septation Septations represent striations of bone found within a lesion that appear to divide the lesion into two or more compartments. The term multilocular is used to describe the resultant compartments. Septa that are curved and coarse may be seen in ameloblastoma, giving rise to an internal pattern that is multilocular or “soap bubble” in appearance. Step 4: Assess the Effects of the Lesion on Adjacent Structures Teeth, Lamina Dura, and Periodontal Ligament Space ● Resorption, which is a feature of longstanding, benign but locally aggressive lesions, chronic inflammatory lesions, and malignancy ● Displacement ● Delayed eruption ● Disrupted development, resulting in abnormal shape and/or density ● Loss of associated lamina dura ● Increase in the width of the periodontal ligament space ● Alteration in the size of the pulp chamber ● Hypercementosis Step 4: Assess the Effects of the Lesion on Adjacent Structures Surrounding bone ● Expansion: – Buccal – Lingual – In other directions ● Destruction ● Increased density ● Subperiosteal new bone formation ● An increase in the normal width of the inferior dental canal ● Irregular bone remodelling, resulting in an abnormal shape or unusual overall bone pattern. Expansion sclerosis Step 4: Assess the Effects of the Lesion on Adjacent Structures ● Displacement or involvement of surrounding structures – Cortex of the inferior dental canal – Mental foramen – Lower border cortex of the mandible – Floor of the antrum – Floor of the nasal cavity – Orbits (A) and (B) Periapical images revealing a lymphoma that has invaded the mandible. There is irregular widening of the periodontal ligament spaces (arrows)  Exudate from an inflammatory lesion can stimulate the periosteum to lay down new bone.  When this process occurs more than once, an onionskin type of pattern can be seen. Panoramic image of osteomyelitis revealing at least two layers of new bone (arrows) produced by the periosteum at the inferior aspect of the mandible.  This pattern is most commonly seen in inflammatory lesions and more rarely in tumors such as leukemia and Langerhans cell histiocytosis. Other examples of patterns of reactive periosteal bone formation include a spiculated new bone formed at right angles to the surface cortex, which is seen with metastatic lesions of the prostate gland or in a radiating pattern of spiculated bone seen in osteosarcoma or a hemangioma. Specimen image of a resected mandible with an osteosarcoma. Note the fine linear spicules of bone at the superior margin of the alveolar process (arrows). Step 5: Formulate an Interpretation Decision 1: Normal or Abnormal The clinician should determine whether the structure of interest is a variation of normal or represents an abnormality. This is a crucial decision because variations of normal do not require treatment or further investigation. Step 5: Formulate an Interpretation Decision 2: Developmental or Acquired If the area of interest is abnormal, the next step is to decide whether the radiographic characteristics indicate that the region of interest represents a developmental abnormality or an acquired change. Decision 3: Disease Classification The categories may include cysts, benign tumors, malignant tumors, inflammatory lesions, bone dysplasias (fibro-osseous lesions), vascular abnormalities, metabolic diseases, or physical changes such as fractures. Decision 4: Ways to Proceed After analyzing the images, the clinician must decide in what way to proceed. This decision may require further imaging, treatment, biopsy, or observation of the abnormality (watchful waiting). Writing a Diagnostic Imaging Report 1. General Patient Information patient's name, age, sex, and medical registration number. Also, the name of the referring clinician (if applicable) and the date of the report are also included. 2. Imaging Procedure This section summarizes the imaging procedures provided along with the date of the examination. 3. Clinical Information The clinical information should be brief and should summarize the information pertaining to the abnormality in question. For example, “Clinicial examination revealed a mass in the floor of mouth, possibly a ranula. The patient has a history of lymphoma.” 4. Findings Detailed list of observations made from the diagnostic images. This section does not include a radiologic interpretation. 5. Interpretation When possible, the clinician should endeavor to provide a definitive interpretation of the abnormality that has been imaged. When this is not possible, a short list of abnormalities or a differential interpretation (listed in order of likelihood) is acceptable. This list should not, however, be exhaustive; ideally it should be limited to diseases within one or perhaps two disease categories at most. In some situations, advice regarding additional studies, when required, and treatment may be included. Last, the name and signature of the clinician composing the report is included. References Stuart C. White, M J Pharoah. White and Pharoah’s Oral Radiology: Principles and Interpretation. 8th Edition. Elsevier; 2019. ISBN: 9780323543835 Lisa J. Koenig Dania Tamimi C Petrikowski Susanne E. Perschbacher. Diagnostic Imaging: Oral and Maxillofacial. 2nd Edition. Elsevier; 2017. ISBN: 9780323477826 Eric Whaites and Nicholas Drage. Essentials of dental radiography and radiology. 5th edition. Elsevier; 2013. eBook ISBN 9780702051685