Society of Nuclear Medicine Procedure Guideline for Lymphoscintigraphy and the Use of Intraoperative Gamma Probe for Sentinel Lymph Node Localization in Melanoma of Intermediate Thickness version 1.0, approved June 15, 2002 Authors: Naomi Alazraki, MD (Emory University School of Medicine, Veterans Affairs Medical Center, Atlanta, GA); Ed- win C. Glass, MD (Wadsworth Veterans Affairs Medical Center, Los Angeles, CA); Frank Castronovo, PhD (Harvard Medical School, Brigham and Women’s Hospital, Boston, MA); Renato A. Valdés Olmos, MD (Netherlands Cancer Insti- tute, Amsterdam, The Netherlands); and Donald Podoloff, MD (MD Anderson Cancer Center, Houston, TX). I. Purpose to make a smaller incision directly over the node, based on the image and probe counts. The purpose of this guideline is to assist nuclear Lymphoscintigraphy images readily demon- medicine practitioners in recommending, perform- strate the unpredictability of lymphatic drainage ing, interpreting, and reporting the results of (1) patterns. Sentinel lymph node biopsy, after iden- lymphoscintigraphy for identifying sentinel lymph tification by lymphoscintigraphy and excision us- nodes for excisional biopsy in patients with ing the intraoperative gamma probe and/or blue melanoma and (2) the use of the intraoperative dye technique, is frequently performed in pa- gamma probe in the operating room. tients without either clinically apparent metas- tases or early intermediate-stage melanoma II. Background Information and Definitions (Clark level <4; Breslow thickness 0.76–4 mm) be- A. This guideline is written specifically for lym- cause of its significant diagnostic and prognostic phoscintigraphy in patients with primary in f o r m a t i o n . melanomas that originate in the skin. Staging of B. Definitions these tumors is based on tumor thickness (Bres- 1. Lymphoscintigraphy: Imaging pathways of low measurement) and level of skin invasion lymphatic flow and lymph nodes after injec- (Clark’s level), both of which are determined by tion of a radiopharmaceutical that is absorbed the pathologist from a biopsy sample. Ample by the lymphatics. data correlate patient survival with Breslow and 2. Sentinel lymph node: The first lymph node in Clark measurements. a lymph node bed to receive lymphatic In the past, elective lymph node dissection drainage from a tumor. Often drainage to (ELND) of the lymphatic bed believed most more than 1 lymph node group and sentinel likely to drain the primary tumor site (based on node is identified. Sappey’s classic anatomic description of cuta- 3. Blue dye technique: Intraoperative injection neous lymphatic flow) was used as part of the (usually peritumoral) of isosulfan blue dye for staging procedure for melanoma. ELND has the purpose of staining lymphatic vessels and been a controversial staging procedure for pa- sentinel lymph nodes so that they can be iden- tients with intermediate (I and II) stage tified visually during surgery for excisional melanoma, because approximately 80% have tu- biopsy. mor-negative lymph nodes and therefore do not 4. Gamma-detecting intraoperative probe: need ELND, a procedure associated with signifi- Small, hand-held radiation-detecting device cant morbidity and cost. The sentinel lymph that uses auditory signals and meter read-outs node excisional biopsy procedure, in contrast, is of counts detected. The intraoperative gamma simpler and not associated with significant mor- probe can be used effectively by the surgeon bidity, provides accurate information about lym- and nuclear medicine physician as a guide to phatic drainage patterns, and allows the surgeon find the radiolabeled sentinel lymph node(s). 136 · LYMPHOSCINTIGRAPHY III. Common Indications 1. Radiotracer injections a. Approximately 0.1mL containing at least A. Sentinel node localization and excision using ra- 3.7 MBq (100 µCi) Tc-99m sulfur colloid, dionuclide methods are performed in the care of filtered (0.22µ millipore filter), is adminis- patients with: tered as 4–8 peritumoral intradermal injec- 1. Intermediate stage primary melanoma (Bres- tions (fewer than 4 may be performed if ap- low 0.76 mm–4.0 mm). propriate) within 1 cm from the melanoma 2. No clinical evidence of nodal involvement. or the excisional biopsy site at which the 3. No clinical evidence of distant tumor spread. melanoma was located. B. Exclusions may include patients with: b. Injections should surround the lesion or 1. Extensive previous surgery in the region of biopsy site to best sample lymphatic the primary tumor site or targeted lymph drainage in all directions. An exception node bed. may be in primary cutaneous melanoma in 2. Patients with known metastases. the head or neck, in which lymphatic drainage is often caudad. Injections infe- IV. Procedure rior to those lesions may be omitted to avoid masking a sentinel node in close A. Patient Preparation proximity to the primary lesion. There are no dietary or medication restrictions c. The injection should be performed by an au- for the procedure. Patients should follow preop- thorized user physician or his/her designee. erative restrictions if the procedure is performed on the same day as scheduled surgery. d. The high pressure of the intradermal bleb B. Information Pertinent to Performing the Proce- can result in leakage of some of the ra- dure dioactivity on needle removal. Care should The patient usually has had a previous biopsy be taken to avoid radioactive contamina- that showed cutaneous malignancy and the tion, which can be confused with lymph pathological classification of the tumor (Breslow, node “uptake.” thickness of the tumor, and/or Clark, skin-layer e. Gentle finger massage should be consid- penetration of the tumor, which are prognostic). ered at each injection site to promote up- Recent extensive surgical excision of the primary take of the tracer into lymphatic channels lesion can be the cause of a rare unsuccessful and lymphatic flow. study because of surgical disruption of lym- f. The injection site should be covered with a phatic vessel integrity. bandaid or cotton ball to prevent leakage C. Precautions of tracer through the needle puncture site. If surgery is to be performed using the intraop- 2. Dosimetry erative gamma probe to assist in finding the sen- In the dosimetry tables included here, the lo- tinel node, the tracer must be injected approxi- cal radiation dose has been ignored and the mately 0.5–3 h before surgery. If surgery is effective dose has been calculated assuming further delayed (by 6 or more h), another image that 20% of the administered activity has been before surgery is advisable to define further mi- absorbed systemically (Kaplan, 1985). The gration of tracer to additional nodes, if any. reasons for ignoring the local radiation dose D. Radiopharmaceuticals are that: No radiopharmaceuticals have been specifically a. Deterministic effects (e.g., local skin necro- approved by the U.S. Food and Drug Adminis- sis) are not a concern for Tc-99m–labeled tration for lymphoscintigraphy in the United radiopharmaceuticals. States. Tc-99m sulfur colloid is used in the b. The estimated local radiation dose varies United States in a filtered (usually 0.22-mm fil- greatly, depending on the assumptions tration) or unfiltered form. Smaller particles are used (Castronovo 1994; ICRP, 60). generally recommended as more frequent visu- c. The local radiation dose contributes little to alization of lymphatic channels is achieved with the effective dose. A 50-rem dose averaged the filtered formulation. over 10 cm2 skin is comparable with an ef- There is worldwide variation in radiopharma- fective dose of 1.7 mrems (Baum, 2001). ceuticals used for lymphoscintigraphy. Tc-99m d. Melanoma is very uncommon in children antimony trisulfide colloid (particle size, 0.015–0.3 but lymphoscintigraphy is occasionally µm) and Tc-99m nanocolloid (particle size, performed in children to determine the 0.05–0.8 µm) are used in Australia and Europe. cause of extremity swelling. SOCIETY OF NUCLEAR MEDICINE PROCEDURE GUIDELINES MANUAL JUNE 2002 · 137 Radiation Dosimetry for Adults Radiopharmaceutical Administered Activity Organ Receiving the Effective Dose2 La r g e s t Radiation Dose1 mSv/MBq MB q mGy/MBq (rem/mCi) (m C i ) (r a d / m C i ) Tc-99m small 15 – 35 0.015 0.0019 or large colloids1 Intradermal Spleen (0.5-1.0) (0.057) (0.0071) 1 ICRP 53, pp. 180 and 182. 2 ICRP 80. Note: values in this table are only 20% of the values found in ICRP 80 because of the assumption that only 20% of the administered activity is absorbed systemically. E. Image Acquisition node(s) in frontal and lateral views, and/or in 1. Acquisition parameters the patient’s position as it would be on the op- Sequential or continuous imaging begins im- erating room table. Skin marking can be per- mediately after completion of injections and formed using the probe in nuclear medicine, if continues for 30–60 minutes. Continuous available, or using a radioactive marker imaging may include dynamic imaging at 30 source. For trunk lesions, images must in- seconds per frame for 2–30 minutes and/or clude both axillary and both inguinal regions. sequential static images every 5 minutes for Some unusual locations for sentinel nodes in- up to 1 hour or until the sentinel lymph node clude periscapular, costal, and umbilical re- is identified. For trunk lesions, images of both gions. The lateral view is essential, especially axillary and inguinal regions should be ob- for distinguishing periscapular from axillary tained. Lateral or oblique views are often nodes. For head and neck lesions, images helpful to uncover multiple nodes that overlie should include the entire head and neck in an- one another on a single projection. The pa- terior, posterior and/or oblique projections tient’s body contour may be defined on the (whichever places the primary tumor and image in relation to the injection site, lymph sentinel node(s) closest to the camera face), drainage, and sentinel node(s) by transmis- and the lateral view.