Radiological anatomy of lymph node

Classification of neck node levels
CONSENSUS GUIDELINES

1. RADIOLOGICAL ANATOMY OF LYMPH NODE

2. Classification of neck node levels Robbins Classification: In 1991 the AAO-HNS classified neck lymph nodes into levels, based on surgical neck dissection This classification distinguishes six levels: IA, submental lymph nodes IB, submandibular lymph nodes II, upper jugular lymph nodes III, middle jugular lymph nodes IV, lower jugular lymph nodes V, posterior triangle lymph nodes VI, anterior compartment lymph nodes

3. Limitations of using Robbins classification for lymph node delineation in RT considers only those lymph nodes that are removed during neck dissections. lymph nodes not commonly removed, such as retropharyngeal, parotid, buccal, and occipital nodes, are not included. L.n boundaries based on surgical procedures are not always easily identifiable on CT scans Moreover, in radiotherapy the neck is immobilized without rotation of the head, while in surgery the position of the neck can be rotated which changes some of the boundaries

4. L.N classification based on Anatomico-radiological Boundaries With the introduction of CT and MRI need was felt to transfer the anatomical boundaries of lymph node stations as described by surgeons onto CT scans several atlases of cross-sectional radiological anatomy of lymph nodes developed Som (1998) Nowak and Levendag (Rotterdam) (1999) Gregoire (Brussels) (2000) RTOG

5. Changes From Surgical Classification Of Nodes

6. DRAWBACK IN THE ANATOMICO-RADIOLOGICAL CLASSIFICATION All guidelines presented some differences in terms of boundaries and sizes; consequently, the need was felt to unify terminology and recommendations for contouring. The main differences between concerned the definition of the cranial edge of levels II and V, the posterior edge of levels II, III, IV, and V, and the caudal edge of level VI.

7. CONSENSUS GUIDELINES At the end of 2003, the group published its “consensus guidelines” which have been endorsed by the major European and American scientific societies (RTOG, EORTC, GOERTEC, NCIC, and DAHANCA) In 2003, a consensus guidelines for node negative patients In 2006, these guidelines extended to include node positive and post-operative neck Although it appears that these recommendations are well accepted they are also associated with some shortcomings

8. Shortcomings of previous consensus guideline not all the neck node areas described in the TNM atlas were included especially lower and posterior neck , face, the scalp & base of skull description of the anatomic boundaries of some of these was not sufficiently accurate guidelines for the node-positive neck,& ECE was arbitrary and imprecise in terms of extension into normal structures to generate CTV Illustrations of the nodal levels were not available in DICOM consequently limiting the easy use of the atlas Hence a task force was formed to review and update the previously published guidelines on nodal level delineation

9. Radiological Anatomy

10. Enlarged sub mental lymph node Bounded by 2 ant. Belly of digastric

11. Bounded by ant. & post Belly of digastric Ant belly digastric Post belly digastric Mandible

12. Crania l border: caudal C1 Cauda l border: caudal edge of hyoid

13. Cranial border: caudal edge of hyoid Caudal border: caudal edge of cricoid

14. Caudal border: 2cm cranial to cranial edge of sternoclavicular joint Cranial border: caudal edge of cricoid

15. Cranial border: cranial edge of hyoid

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