Recent advances in ENT- FRMI contact endoscopy, PET scan and immmunotherapy

A brief slides discussing the recent advances in the field of ENT
1. FMRI
2. Contact endoscopy
3. PET scan
4. Immunotherapy

1. Recent advances in ENT -Part 1 Moderator: Dr. Babu AR Presenter: Dr.Sreenivas Kamath

2. Functional MRI PET scan Contact endoscopy Gene Therapy

3. Functional MRI Why is it called functional ? -imaging modalities that are able to pick up Physiological functions. FMRI mainly has focused so far in brain imaging- thus it helps to identify the physiological changes accompanying the brain activity Why F-MRI ? It has the highest spatial resolution among all the other functional brain imaging.

4. Principle of imaging using MRI T1- Based on relaxation time T2- spin spin difference. Functional MRI – perfusion FMRI BOLD- blood oxygen dependent FMRI Neuronal-hemodynamic coupling theory

5. Perfusion functional MRI Most direct approach Measures local increase in perfusion following any neuronal activity The study could be enhanced using MRI contrast Spin tagging – extremely challenging – Non invasive

6. A- BOLD MRI B- Spin tagged MRI sequence – less senstitive than BOLD

7. BOLD FMRI Most widely used FMRI technique Signalling technique in T2* mode Generated with differences in local ‘magnetic susceptibility’, an index of the extent to which an applied magnetic field is distorted as it interacts with a material , as blood oxygenation changes.

8. When bound to oxygen, haemoglobin is diamagnetic, while deoxygenated haemoglobin is paramagnetic. Diamagnetic- Magnetic flux is reduced. Paramagnetic- there is increase magnetic flux. So a ratio of Oxy to deoxy is studied during the imaging process.

9. Study designs in the BOLD FMRI BLOCK design This design uses relatively long, alternating periods (e.g. 30 s), during each of which a discrete cognitive state is maintained. In the simplest form, there may only be two such states, a ‘ rest’ and an ‘active’ state.

10. SINGLE EVENT design Data are acquired while discrete stimuli or responses are given. Powerful approach- considerable flexibility for study of responses to individual or periodically presented stimuli, but it demands relative longer acquisition times than the block design.

11. What is the role of functional MRI in ENT Imaging the normal auditory system The specialized auditory processing streams in the human brain implied by these differences are analogous to the ‘what’ and ‘where’ segregation of auditory information processing, suggesting common modes of information organization . Neural plasticity- assessed using FMRI in candidates of cochlear implant Effect of centrally acting drugs

12. Heschl’s Gyri (transverse temporal gyri)

13. FMRI has been used in cases of unilateral tinnitus which has showed that there is reduced resting state functional connectivity score in the auditory cortex between the left and right lobes as compared to normal individuals. Patients in the study had left side tinnitus- increased functional connectivity score was noted in the left amygdala and in the dorsomedial prefrontal cortex. Ji-young Kim, Yee- hyuk Kim, Sangheun Lee, Jee-Hye Seo , Hi- Jin Song, Jin Ho Cho & Yongmin Chang (2012) Alteration of functional connectivity in tinnitus brain revealed by resting-state fMRI?: A pilot study, International Journal of Audiology,51:5, 413-417, DOI:  10.3109/14992027.2011.652677

14. Another study done in cases of unilateral tinnitus patients- it was found that “ The response to sound in the inferior colliculus was elevated in tinnitus patients compared with controls without tinnitus”. C.P. Lanting , E. De Kleine , H. Bartels & P. Van Dijk  (2008) Functional imaging of unilateral tinnitus using fMRI,  Acta Oto- Laryngologica , 128:4, 415-421, DOI:  10.1080/00016480701793743

15. PET scan This functional imaging technique relies on a radioactive molecule (radiotracer) that decays with positron emission. Identifying pathology based on altered tissue metabolism. Intravenous radiotracers are injected  they get trapped within the pathological cells these radiotracers are unstable and decay by emitting Positrons these positrons collide with near by tissue emit Gamma radiations picked up by the radiosensors .

16. Quantitative Test- The absolute quantification not done Semi-quantitative method used Standardised Uptake Value- SUV The PET scan lacks the anatomical details which can be overcome using CT/MRI along with the PET scan.

17. What is FDG PET scans? 2-[18F] fluoro-2-deoxy-Dglucose ( FDG ) Radiotracer Majority of the studies use FDG- analogue of glucose Cancer cells have more avidity to glucose than normal cells

18. Neck Lymph node status Good sensitivity and specificity But as per literature PET scan positive alone is not an indication of neck dissection But along with other investigations A malignancy with high risk of nodal metastasis with PET scan Positive- requires neck dissection A malignancy with low risk of nodal metastasis with PET scan negative- No need for neck dissection .

19. Detection of synchronous maliganacy Upto 15% incidence Detect the whole body Since the incidence of synchronous primary is low- PET scan is not routinely adviced .

20. Occult primary

21. Other radiomarkers Is there a requirement of other radiomarkers ? Uptake by normal tissues- less specific 18F-FLT- flurothymidylate for DNA synthesis seems to have promising specificity 11C MET- 11C methionine 18F-fluoroazomycin-arabinofluranoside 18F- FAZA are the newer radiotracers under research

22. Contact Endoscopy Contact endoscopy was first described by Desormeaux in 1865, who managed to obtain a direct view of the bladder mucosa Andrea et al in 1995 showed its use in diagnosis laryngeal pathology Contact endoscopy allows in vivo and in situ observation of the mucosal blood vessels and superficial cells of the epithelium which have been previously stained with methylene blue

23. Concept in doing Contact endoscopy Detect disease in its subclinical stage All cells migrate towards the surface- thus pathological changes will be seen on the surface epithelium. The surgeon is able to assess the microscopic structure of the entire mucosa, allowing a more complete interpretation of the disease process.

24. Can be done in a wake patient in OPD as well in anaesthetized patient in the theatre. Currently 2 endoscopes are available for evaluation of upper airway (7215 AA and 7215 BA, Karl Storz , Tuttlingen , Germany ). 60 or 150 x magnification

25. Procedure of CE The endoscope is gently placed over the suspicious site and viewed using 60X and 150X magnification Vascular patterns are studied 1% methylene blue soaked cotton pledgets are placed over the mucosa for 5 mins Then again visualised for surface epithelia

26. Vascular patterns Minimal branching. No coiling or micro haemorrhages. Lay out is parallel. Flow of RBCs inside the vessels is brisk

27. Tuft of blood vessels – seen in lichen planus

28. Numerous dilated blood vessels – Erythroplakia

29. Blood vessels in malignant lesion showed coiling , micro haemorrhages and increased tortuosity of vessels. Flow of RBCs inside the vessels was sluggish

30. Contact endoscopy in Larynx Performed under GA Normal appearance Squamous epithelium present only on the edges of vocal cord margins and hypopharynx Rest of the larynx is lined by ciliated columnar epithelium (respiratory epithelium)

31. Abnormalities in Larynx Substitution of ciliated columnar epithelium by squamous epithelium. CHRONIC LARYNGITIS- homogeneous ciliated cells with larger nucleus- immature cells due to faster cell turnover in inflammation. More blood vessels with normal pattern. KERATOSIS- keratinisation is seen. LEUKOPLAKIA- heterogeneous population of cells, with nuclear atypia, hyperkeratosis, dysplasia

32. In CARCINOMA, cell morphology is very variable with extreme heterogeneity of nuclear size, shape and staining characteristics . The nuclear : cytoplasmic ratio also changes from cell to cell. Nuclear inclusion bodies, prominent nucleoli and mitoses may be seen

33. Contact endoscopy in nasal cavity Squamous epithelium is present in the anterior most portion of inferior turbinate, septum, nasal vestibule. Rest of the nasal cavity is lined by ciliated columnar epithelium. The duct orifices of glands are most prominent at the anterior end of the turbinates .

34. Abnormalities in the nasal cavity In CRS- Squamous epithelium covers most of the inferior and middle turbinates and anterior septum. The nuclei of these cells look larger than normal. Over production of mucus and faster clearance of stain. Increase glands and more ostias are seen. In ALLERGIC RHINITIS Mucus production is increased. Papillae of glands are larger U shaped vascular axis in papillae noted.

35. Contact endoscopy in Nasopharynx Done to follow up cases of treated nasopharyngeal malignancy. In NPC- Fragile- bleeds on touch Nuclear atypia, heterochromasia

36. Contact endoscopy in oral cavity and oropharynx Oral mucosa varies from site to site . NON KERATINISED-Mucosa of the lip, the alveoli , cheek, floor of the mouth, ventral surface of the tongue and soft palate. KERATINISED- mucosa covering the hard palate and gingiva, occlusal zone of cheek mucosa.

37. GENE THERAPY Genome influences all aspects of human life Genes are functional unit of genome Today, some 63 human clinical trials of gene therapy exist. The treatment aims to replace or repair the defective gene causing a given disease or to provide a new or altered function in a cell.

38. Mainly focused on three groups of disease process Infectious disease trial- HIV Monogenetic disease- Cystic Fibrosis, Hemophilia B Polygenetic disease- Rheumatoid arthritis, Cancers.

39. Gene therapy in ENT Cystic fibrosis Head and Neck malignancy

40. Cystic fibrosis Autosomal recessive disease. Median survival age is 31 yrs Mutation of long arm of Chromosome number 7- codes for cystic fibrosis transmembrane conductance regulator (CFTR ). cAMP dependant Chloride transporter- results in abnormal salt and water transport across epithelia.

41. Gene transfer Process Two models under trial 1. The Nasal model 2. The lung model – lung complications over pre-existing lung compromise

42. Nasal model is preferred over the lung model Less risk of adverse events Accessible for vector administration Follow-up using bioelectricity measurement has been researched upon. INVIVO studies ? Not very helpful cause similar disease state is not present in animal models

43. VECTOR for gene transfer Most trials used- Adenovirus It has affinity to respiratory epithelium Recombinant viruses are produced by replacing the DNA sequence responsible for replication with CFTR cDNA . The viruses are thus replication-deficient, but still remain sufficiently active to transport genetic material into the target cell.

44. Zabner et al- nasal model- not effective Crystal et al- applied both nasal and lung model- patient had immunohistochemical uptake of gene ¼ patient developed pulmonary toxicity due to adenovirus. Hay et al- escalating dose- better uptake in nasal model Zabner et al- logarithmical application- better uptake, but found signs of immune reaction on repeated vector administration.

45. Other vectors Serotypes 5 and 6 of the adeno-associated virus ( AAV) Lentivirus Naked DNA in plasmid form or ballistic gene delivery, the so-called gene gun. Liposomes bind to DNA, spontaneously forming complexes that have high affinity for plasma cell membranes.

46. Gene Therapy in Head and neck malignancy Advances in Surgical, Medical and radiational field has increased survival rate of head and neck malignancy But yet the survival rate of advance squamous cell carcinoma is not improved

47. Delivery of GENE is difficult in H&N scenario Why ? Targeting – ideally only cells which require the gene would be affected. Binding and internalization – once a gene reaches the cells it must bind and become internalized Cellular trafficking to the nucleus – most methods of internalization require the gene to escape from endosomal degradation and traffic through the cell to the nucleus Nuclear expression – once in the nucleus the quantity of gene expression and stability of expression for a given strategy also need to be determined

48. Strategies of gene therapy in H and N

49. FDG in Skull Base Osteomyelitis In diagnosed case of SBO , PET scans are more effective imaging modality to see the extent and disease process.

50. FDG PET scan indications in Head and neck As per AJCC, only in thyroid cases and CNS tumors PET scan mainly indicated along with the other imaging modality in Pretreatment assessment, and post treatment followup .

51. Thank You