Diagnostic imaging in head and neck pathology


Published on

Published in: Health & Medicine, Business

Diagnostic imaging in head and neck pathology

  2. 2. What is meant by “Diagnostic Imaging”??  Diagnostic imaging is the visualization of internal body organs, tissues, or cavities using specialized instruments and techniques for diagnostic purposes.
  3. 3. Classification of Medical Imaging Modalities:  X-Ray Imaging (Imaging techniques utilizing ionizing radiation).  Conventional Radiography.  Tomography.  Computed Tomography.  Cone Beam Computed Tomography  Magnetic Resonance Imaging  Ultrasound Imaging  Nuclear Imaging (Molecular imaging)
  4. 4. X-ray Imaging
  5. 5. History of X-ray 1. Discovery by: Wilhelm Conrad Roentgen………November 8, 1895 in Germany. First Noble prize in physics………..1901. 2. First radiograph was of the hand of Bertha, Roentgen’s wife.
  6. 6. 3. The first dental radiograph is attributed to Friedrich Otto Walkhoff.……January 14, 1896 in Germany. 4. The first intraoral radiograph by Dr. Edmund Kells with the help of Prof. Brown Ayres was made in the early spring of 1896 in the USA.
  7. 7. Conventional Radiography
  8. 8. • In conventional radiography, a stationary source and a planar detector are used to produce a 2D projection image of the patient. • The image has intensity proportional to the amount by which the X-rays are attenuated as they pass through the body.
  9. 9. Limitations of conventional radiography • The image resolution is not adequate. So specifying the exact nature of the tissues in the field of interest is difficult. •Conventional radiography provides no depth information, as the three dimensional (3D) body structure is projected onto a two-dimensional (2D) image and objects seen in the third dimension superimpose losing detail. Thus the need to develop tomographic images evolved.
  10. 10. Tomography
  11. 11.  Tomography is a specialized imaging technique where the two-dimensional image produced represents only a slice or a section of the three- dimensional object.  The third dimension (slice thickness) can be less than 1 mm.  Each tomograph (or slice) shows the tissues within that section sharply defined and in focus. Structures outside the section are blurred and out of focus.
  12. 12. Indications of Tomography:  Assessment of jaw height, thickness and texture before inserting implants.  • Postoperative evaluation of implants.  • Assessment of the size, position and extent of antral tumors.  • Evaluation of grossly comminuted facial fractures to determine all the fracture sites.  • Assessment of the extent of orbital blow-out fractures.  • As an additional investigation of the TMJ and condylar head.
  13. 13.  Conventional tomography has essentially been superseded in medical radiography by the development of computed tomography (CT). It is however still important in dentistry, forming the basis of dental panoramic tomography.
  14. 14. Dental Panoramic Tomography (Panoramic Radiography, Orthopantomography And Rotational Radiography)
  15. 15. In panoramic tomography, the section or focal plane is designed to be approximately horseshoe shaped; corresponding to the shape of the dental arches.
  16. 16.  Produces a single tomographic image of facial structures including both maxillary and mandibular arches and their supporting structures.  The radiation dose is relatively low; the dose is equivalent to about three to four perapical radiographs.  However, there is distortion and magnification of the final image.  Image quality is inferior to that of intraoral radiographs.
  17. 17. Computed Tomography
  18. 18. History of Computed tomography  The first computerized tomography scanner was introduced by Godfrey Houndsfield in 1972.  In 1979, Godfrey Houndsfield received the Nobel Prize in medicine.
  19. 19. Advantages of CT:  Provides an axial, coronal and sagittal view of the tissue. The image can be manipulated by the use of computer programs.  A three dimensional image of the object can be accurately constructed.  Provides a greater geometric and anatomical precision of the lesion.  The structures of the soft tissue both normal and pathological are clearly displayed.
  20. 20. Advantages cont.  Produces clearer images with high contrast resolution compared to the conventional radiography.  Image can be enhanced by the use of IV contrast media.  At present, CT scanners can obtain slices 0.5 mm thick. A neck examination from skull base to the mediastinum can be performed in less than 30 seconds.
  21. 21. Indications of CT in head and neck area: 1. Fracture lines as it provides the clearest definition of bone structure. 2. CT is the first choice for a survey of metastatic nodes in the neck. 3. Intracranial diseases, tumors and trauma. 4. Malignancies of the jaws to delineate the margins of tumor. 5. View TMJ. 6. Implants placement to assess the height of the jaws.
  22. 22. Axial CT image of hyperdense lymph node metastasis (arrow) of squamous cell carcinoma of the tongue base (bent arrow).
  23. 23. Skull base erosion (arrow) by nasopharyngeal carcinoma in a 40-year-old man with headache
  24. 24. Limitations of CT:  It is an expensive technique.  Very high density restorations as dental restorations produce severe artifacts on the CT scan.  High dose of radiation.  There is an inherent risk with the use of contrast media.
  25. 25. Cone Beam Computed Tomography (CBCT)
  26. 26.  CBCT is a technical advancement in CT imaging that uses cone beam geometry and a flat panel detector (FPD) to provide a relatively low-dose imaging with resolution acquired with a single gantry revolution (17).  The first (CBCT) system for dental use was developed in 1999.
  27. 27. Visualization of the full data volume by means of a shaded surface display with the threshold set to show hard tissues (bone and teeth) only The data attenuation values corresponding to the soft tissues were made partially transparent, allowing for visualization of the underlying skeleton and teeth.
  28. 28. Advantages of CBCT  It provides clear images of highly contrasted structures.  Accurate measurements can be derived from the reformatted data.  Reduced radiation exposure to the patient compared with medical CT. Imaging doses is approximately onetenth that of a diagnostic CT scan.  Reduced cost compared to CT.  Possibility of office-based compact CBCT scanner suitable for use in an office-based setting .  CBCT scanner can collect volume data by means of a single rotation taking 9-40 seconds.
  29. 29. Comparison of(a) sagittal conventional tomography (CVT) images, (b) helical CT (HCT) images and (c) limited cone beam CT (limited CBCT) images of the medial region of the mandibular condyle which showed erosive changes in the superficial soft tissue with anatomical observation. The findings of resorptive changes in bone cortex were obtained with HCT and limited CBCT images
  30. 30. Some applications of CBCT
  31. 31. Conventional sialogram Stafne’s bone cavity Conventional sialogram showing that some branch ducts arising superiorly from the hilum of the submandibular gland seemed to distribute in the cavity area
  32. 32. CBCT Sialography Stafne’s bone cavity 3D CBCT sialography shows the spatial relationship of submandibular gland and the bone cavity
  33. 33. Stenosis of stensen’s duct in sjogren syndrome Panoramic sialogram shows stenosis of the right Stensen’s duct. CBCT sialography with 3D reconstruction show stenosis with areas of strictures through the glandular ductules (arrows).
  34. 34. CBCT in Imaged-Guided Surgery Imaged guided surgery can delineate the tumor and related structures, thereby diminishing complications and allowing preservation of adjacent vital structures, while achieving complete tumor removal. A mobile C-arm platform. This is easier to manage when an intraoperative image is needed.
  35. 35. Limitation of CBCT:  Limited image quality in comparison with MSCT.  Less soft tissue visibility compared to MSCT. But despite these limitations the use of MSCT associated with much radiation in dentistry should be avoided in cases where the imaging ability of the CBCT technique is thought to be adequate for diagnosis and treatment planning.
  36. 36. Magnetic Resonance Imaging
  37. 37.  Magnetic resonance imaging (MRI) is an imaging modality that uses the response of biologic tissues to an applied and changing magnetic field to generate images.
  38. 38. Advantages of MRI  MRI provides good contrast between the different soft tissues of the body, which makes it especially useful in imaging the brain , muscles, the heart, and cancers compared with other medical imaging techniques such as CT or X-rays.  Unlike CT scans or traditional X-rays, MRI does not use ionizing radiation.  No harmful effects are known to occur during pregnancy. However, as a precaution, pregnant women should undergo MRI only when essential particularly during the first trimester of pregnancy.
  39. 39. Applications of MRI  The applications of MRI mostly rely on its ability to offer improved soft tissue contrast.
  40. 40. Perineural infiltration of cranial nerve VII by adenoid cystic carcinoma. Image shows vertical extension of the enhancing tumor (arrows) through the stylomastoid foramen
  41. 41. Disadvantages of MRI:  MRI frequently requires 30 to 45 minutes of scanning time, during which time the patient must remain motionless, a process difficult for sick patient to accomplish. Motion artifacts are more frequently encountered than with CT, although dental artifacts may be less problematic.  Unfortunately, MRI is one of the most expensive imaging modalities.
  42. 42. Contraindications of MRI:  Absolute contraindications to MRI include patients with cardiac pacemakers, cochlear implants, and ferromagnetic intracranial aneurysm clips.  Generally, ocular prostheses and ossicular implants are safe.
  43. 43. Ultrasound Imaging
  44. 44.  Ultrasound (US) images are 2D gray-scale images. They are based on the phenomenon of reflection of ultrasound waves.  The tissue that reflects a considerable amount of ultrasound is described as hyperechoic. While hypoechoic is the area that reflects less amount of ultrasound compared to the adjacent tissue. Anechoic is an area where there is no reflection of echoes.
  45. 45.  Bone surfaces demonstrate total reflection of ultrasound waves (hyperechoic) thus structures inside and beyond intact bone are not normally detectable by ultrasound.  Cystic structures in the other hand are fluid filled thus anechoic and the ultrasound waves pass through it with little or no attenuation.
  46. 46. Advantages of Ultrasonography  Ultrasound has no known harmful effects and no contraindications as it doesn’t use ionizing radiation.  It is relatively inexpensive compared with CT or MRI. It is the easiest to use and the least invasive.
  47. 47. Applications of Ultrasound Imaging  US is used for the detection of noninvasive and soft tissue-related diseases in oral and maxillofacial regions particularly it is clinically applied to evaluate salivary gland-related diseases, lymph node-related diseases, subcutaneous diseases, and tongue related diseases.  It is especially useful in the pediatric population, due to the relatively superficial nature of the neck structures.
  48. 48. US Guided FNA
  49. 49. Ultrasound image with the needle inserted into the mass
  50. 50. The specimen was diagnosed as Schwannoma
  51. 51. Intraoperative determination of tumor thickness and resection margin in tongue carcinomas using Ultrasonography
  52. 52. Ultrasonographic image of tumor shown as hypoechoic shadow (preoperative view)
  53. 53. Needle being introduced to indicate deep surgical margin clearance under ultrasonographic monitoring Ultrasonographic image of tumor with the needle positioned at 10 mm from the deepest invasive front of the tumor Red arrows showing the needle.
  54. 54. Resected fresh specimen Scanning of gelatin-embedded specimen from superior surface
  55. 55. Ultrasonographic scan of gelatinembedded specimen H & E stained section of region of interest
  56. 56. Diagnosis of Metastatic Lymph Nodes in Oral Cancer The metastatic lymph node (arrows) contacts the common carotid artery (white arrowheads) Magnification of the same area in a CT of the same patient
  57. 57. Demonstration of salivary gland stones •Ultrasound is a sensitive imaging modality in the detection of salivary stones are quoted accuracies of 90%. •About 20% of salivary stones are radio-lucent on radiography. With ultrasound it is possible to identify these stones and to identify their precise location.
  58. 58. Longitudinal section of a dilated submandibular duct (Wharton`s duct) A stone is located in the anterior portion of the duct
  59. 59. Longitudinal section of the pre-epiglottic space. A cystic lesion is seen caudal to the hyoid bone: Thyroglossal duct cyst.
  60. 60. Limitations of Ultrasound imaging:  They include inaccessibility of deep-seated lesions, its inability to penetrate bone or airfilled structures.  US provides a limited field of view, lack of easily identifiable anatomic landmarks, and operator dependence.  Less time is required for a CT of the neck to be done (2-3 min) compared to an US (30 min).
  61. 61. Color Doppler Ultrasonography  Doppler ultrasound assesses the distribution of vessels within the node.  It is suggested that as color Doppler ultrasound (CDUS) can differentiate between reactive and neoplastic lymph nodes.  Thus CDUS can eliminate the need of biopsy/FNAC in case of reactive lymph nodes. When the results of CDUS suggest malignancy US guided FNAB is then required to reach a final diagnosis.
  62. 62. A small ovoid node with hilar vascularity - Typical reactive lymph node is visualized
  63. 63. A rounded lymph node with multiple peripheral arteries is visualized in a squamous cell carcinoma lymph node metastasis
  64. 64. Nuclear Imaging
  65. 65.  Nuclear imaging is a method of producing images by detecting radiation from different parts of the body after a radioactive isotope (radionuclide) is administered.  The radionuclide undergoes radioactive decay, resulting in the emission of gamma rays. External detectors (gamma cameras) capture and form images from the radiation emitted.  The main difference between nuclear imaging and other radiologic tests is that nuclear imaging assesses how organs function, whereas other imaging methods assess anatomy.
  66. 66.  There are several techniques of diagnostic nuclear medicine such as:  Scintigraphy.  Positron emission tomography (PET).  Single Photon emission tomography (SPECT).
  67. 67. Scintigraphy
  68. 68.  In Scintigraphy the radioisotopes (here called radiopharmaceuticals) are taken internally, and the emitted radiation is captured by external detectors (gamma cameras) to form two dimensional images.
  69. 69. Applications of scintigraphy  Salivary scintigraphy: Detection of sialolithiasis With or Without Parenchymal Damage.
  70. 70. Sialolithiasis with functional obstruction of the right parotid gland without any parenchymal impairment
  71. 71. Sialolithiasis with functional obstruction of the right parotid gland with parenchymal impairment
  72. 72. Positron emission tomography (PET)
  73. 73.  PET is a tomography in which a computer- generated image of metabolic or physiologic activity within the body is produced through the detection of gamma rays that are emitted when introduced radionuclides decay and release positron.
  74. 74. Advantages of PET:  PET can image biochemical and biological processes that are fundamental to disease.  Since diseases are viewed not only in terms of structure but also as process, PET can routinely detect diseases even though normal results are provided by CT and MRI.
  75. 75. Application of PET  The main application of PET is in the field of oncology.  The most commonly used PET radiopharmaceutical in oncological applications is the glucose analogue 2-18F-fluoro-2-deoxy-D-glucose (FDG).  Glucose metabolism in growing neoplastic cells is enhanced and accounts for the increased uptake on FDG-PET studies.  To monitor treatment from a metabolic perspective.
  76. 76. PET in the diagnosis of Lymphoma A major problem concerns the systemic nature of lymphoma and its treatment, which is usually not surgery. Whole body PET has a significant impact on staging of lymphoma, since biopsy of all lesions is impossible.
  77. 77. Non-Hodgkin lymphoma, baseline study
  78. 78. Same patient after four courses of chemotherapy
  79. 79. Limitations of PET  Although the accuracy of PET is higher than MR and/or CT, there is lack of correct anatomical localization of the abnormal PET foci which is necessary for treatment. This can be overcome by the use of PET/CT.  PET is considered as an expensive imaging modality. However, whole body PET appear cost effective when compared to a more conventional approach with multiple CT or MR scans of specific body areas.
  80. 80. PET/CT
  81. 81.  PET/CT is a medical imaging technique using a device which combines in a single system both a PET scan and an x-ray CT, so that images acquired from both devices can be taken sequentially, in the same session from the patient and combined into a single superposed image.
  82. 82. Advantages of PET/CT  Increased sensitivity and specificity in evaluation of primary and recurrent malignancies.  The exact localization of a focal abnormality on PET. The superimposition onto an anatomically identifiable structure makes the image interpreter more confident and reduces interobserver variability.
  83. 83. Normal whole body PET/CT scan with FDG-18. The whole body PET/CT scan is commonly used in the detection, staging and follow-up of various cancers.
  84. 84. Abnormal whole body PET/CT scan with multiple metastases from a cancer. The whole body PET/CT scan has become an important tool in the evaluation of cancer.
  85. 85. Evaluating Carcinoma of Unknown Primary Subtle difference in uptake between right (arrow) and left tonsil on the PET/CT of patient with carcinoma of unknown primary—the right tonsil was subsequently identified as the primary site.
  86. 86. Choice of the appropriate imaging modality The choice of imaging modality varies depending on the location and nature of the disease process.  CT is fast and widely available and can be employed as the first and often the only imaging modality in the majority of the disease processes affecting the neck.  CT excels in demonstrating bone detail.  Radiation exposure from CT examination is substantial and should be taken into account particularly in young patients who require repeat examinations.
  87. 87.  MRI provides excellent soft tissue contrast and is the modality of choice in most aggressive processes.  Successful primary staging of most malignant lesions in the neck can be accomplished with CT or MRI and clinical examination.  The accuracy of PET increases when it is used in conjunction with CT.  PET/CT is superior in identifying distant metastases and postoperative follow-up.  Image interpretation should always be made in conjunction with clinical information.