LYMPHOSCINTIGRAPHY

1. LYMPHOSCINTIGRAPHY Sentinel node localization in Melanoma Frank P. Dawry

2. Definition and Information • Sentinel node is the first lymph node bed to receive lymphatic drainage from a tumor • Useful in staging of primary melanomas that originate in the skin • Used only on patients with intact primary lesions or on patients who have had only excisional biopsies • Lymphatic drainage pattern is identified eliminating the need for extensive lymph node dissection with it’s associated morbidity and cost • 80% of patients with intermediate (I and II) stage melanoma have tumor-negative lymph nodes

3. Injection

4. Majority of lymph nodes are anteriorly located

5. Procedure • Patient preparation – no dietary or medication restrictions • Patients should follow pre-operative instructions if surgery the same day • Precautions – if surgery is to be performed using an interoperative gamma probe, tracer must be injected within 3 hours of the surgery

6. Benefits of SLN Imaging

7. Benefits of SLN Imaging - continued

8. Radiopharmaceuticals • Tc-99m Sulfur Colloid • Filtered – 0.22 mm filtration • Advantage in mapping the entire lymphatic drainage basin • Disadvantage in progressing past the sentinel node • Unfiltered – mixed particle sizes • up to 2.0 mm particle size • Advantage in remaining in the sentinel lymph node(s) • Disadvantage in not being able to map the lymphatic drainage basin • Antimony sulfur colloid • Not available in this country • Tc-99m HSA • Improved image quality over Sulfur Colloid but reduced sentinel node retention

9. Radiotracer Injection • 0.1 ml volume in tuberculin syringe x 4 • 100 uCi in each of 4 syringes • Intradermal injection • Body and Extremities • Inject at 12, 3, 6 and 9 o’clock location surrounding the lesion • Head and Neck • Inject syringes superior to lesion in reference to the whole body • Performed by an authorized user or delegate

10. Intradermal • Injection is made directly under the epidermis similar to a tuberculin skin test

11. Precautions • Pre-injection of 1.0% lidocaine hydrochloride before study to minimize injection pain • Injections performed under semi-sterile conditions – site prepared with 70% alcohol or betadyne • Use absorbent pad with small opening to prevent skin splash contamination • Cover injection site with gauze to prevent leakage contamination

12. Imaging protocol • LFOV camera • LEHR collimator • Cobalt sheet source for transmission imaging • Point source outlining as an alternative • Views • Axillary and inguinal regions imaged for lesions on the trunk • Anterior and/or Posterior – depending on lesion location • Lateral and obliques views helpful to uncover multiple nodes overlying one another • Skin marking • Triangulation in order to determine 3-D location of sentinel node • Patient may be marked using the patient’s position as it would be in the operating room

13. Acquisition parameters • Sequential or continuous imaging beginning immediately following completion of injections for 30-60 minutes or until sentinel node is identified • Continuous dynamic imaging at 30 seconds/frame • Sequential static imaging every 5 minutes/frame

14. Final Report • In addition to routinely reported items (radiopharmaceutical, dose, injection method, etc.) • Location(s) of sentinel lymph node(s) • Presence of lymph channels if visualized on images • An image should be available, with landmark locations, to the surgery team at time of surgery

15. Static imaging

16. Static imaging

17. Breast

18. Interoperative probe Sentinel node has at least 10x background counts

19. Surgery The 'hot' node(s) is(are) confirmed by the hand held gamma probe and then excised an ex-vivo count of radioactivity is obtained using the gamma probe