☢️ Limfoscintigrafie Cutanată pentru Ganglionul Santinelă în Melanom Malign

Updated Skin Lymphoscintigraphy 9/8/2024 ●Indications To localize sentinel lymph nodes in the setting of melanoma, Merkel cell carcinoma and squamous cell carcinoma. ●Radiopharmaceutical: Day of surgery - 500 microCi Tc-99m Lymphoseek (tilmanocept) divided into 4 syringes (each containing 0.1 mL fluid) Afternoon before surgery = 2 mCi Tc-99m Lymphoseek (tilmanocept) divided into 4 syringes (each containing 0.1 mL fluid) ●Method of Administration:  The Radiologist will inject radionuclide intradermally around the 12, 3, 6 and 9 o'clock positions within 1 cm of skin lesion.
The injection sites will then be massaged for a few minutes to stimulate lymphatic flow. ●Patient Preparation: No specific preparation prior to radionuclide administration. ●Conflicting Examinations/Medications: No Nuclear Medicine exams within the previous 24 hrs. ●Pregnancy/Lactation: Pregnancy status does not need to be assessed due to short t1/2, low administered activity and extremely low radiation risks. Breast feeding mothers should discard breast milk for 24 hrs following Tc-99m Lymphoseek / sulfur colloid administration. ●Imaging Technique: Collimator - LEHR or LEAP Photopeak - 140 keV 20% window for Tc-99m Image Preset Counts ◦Dynamic - 60 secs/image for 20 mins (20 images) ◦Static - 3-5 mins/image ◦SPECT - 64 stops, 25 secs/stop Matrix Size - 128×128 (dynamic), 256 x 256 (static), 128 x 128 (SPECT) Zoom - none ●Images/Views: Dynamic Images (Only if Requested) ◦Begin imaging immediately after radionuclide administration. Image for 20 mins. ◦ Obtain anterior images of the area around the injection sites with the patient supine or prone depending of the location of the skin lesion. ◦For hand/forearm lesions follow any lymphatic channels superiorly to identify any epitrochlear nodes. ◦For feet/foreleg lesions follow any lymphatic channels superiorly to identify any popliteal nodes. Static Images (Always Obtained) ◦A Co-57 sheet flood source should be placed under the patient to outline his/her anatomy. ◦Place shielding over the injection sites to decrease scatter artifact. ◦Image the patient supine with his/her arms by the sides for neck images and overhead for other images. ◦Begin imaging 15-30 mins after radionuclide administration. ◦Head and neck lesions ✓Obtain anterior and lateral images of the face and neck until lymph nodes are visualized. ◦Trunk lesions ✓ Obtain anterior images of the cervical, supraclavicular, axillary & pelvic regions. Image all these areas even if nodes are visualized elsewhere (sentinel nodes can be located in multiple locations in a patient). ✓Add 45° anterior oblique and lateral images if nodes are visualized in either axilla. ✓Add lateral images if nodes are visualized in the neck.

◦Arm lesions ✓Obtain anterior images of the axilla, supraclavicular and neck regions. ✓Add elbow images for hand/forearm lesions. ✓Add 45° anterior oblique and lateral images if nodes are visualized in either axilla. ✓Add lateral images if nodes are visualized in the neck. ◦Leg lesions ✓Obtain anterior images of the pelvis/groin. ✓Add knee images for feet/foreleg lesions. SPECT Images - can be obtained as requested by the Radiologist or Surgeon. Have the Radiologist / Radiologist Assistant mark any node(s) with a permanent marker if the exam is ordered with imaging. ●Notes: Lymphoseek targets dextran-mannose receptors on the surface of macrophages / dendritic cells in lymph nodes.  The first lymph node to appear is the sentinel lymph node and is often the hottest node and is usually the node closest to the injection site.  Sentinel lymph nodes may also be present between the primary lesion and the nodal basin (so-called in-transit or interval sentinel lymph nodes).  A skin cancer may drain directly to multiple lymph nodes in one or more nodal basins (e.g. chest lesions draining to both the axilla and the groin). Second-echelon nodes may be misinterpreted as sentinel lymph nodes if dynamic or early static imaging is not obtained. Patients with thick melanoma have a risk of lymph node metastases >40 %. Patients with thin melanoma have a risk of lymph node metastases <5 %.  Causes of sentinel lymph node nonvisualization include existing nodal disease, previously performed wide local excision of the skin lesion and prior surgery/trauma to the expected nodal basin.