Medicină nucleară — Limfoscintigrafie ginecologică (MCB)

Updated Gynecologic Cancer Lymphoscintigraphy 9/8/2024 ●Indications  To localize sentinel lymph nodes in the setting of early stage cervical cancer, stage 1 and 2 high-risk endometrial cancer,
vulvar squamous cell carcinoma <4 cm, vaginal cancer (investigational) and low-risk ovarian cancer (investigational). ●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: Cervical/endometrial lesions: The Radiologist will inject radionuclide around the 12, 3, 6 and 9 o'clock positions of the cervix. Vulvar lesions: The Radiologist will inject radionuclide intradermally around the 12, 3, 6 and 9 o'clock positions of the lesion.
 ●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 ◦Static - 3-5 mins/image ◦SPECT - 64 stops, 25 secs/stop Matrix Size - 256 x 256 (static), 128 x 128 (SPECT) Zoom - none Patient Positioning - supine ●Images/Views: Static Images ◦A Co-57 sheet flood source should be placed under the patient to outline his/her anatomy. ◦ Obtain anterior and lateral images of the abdomen and pelvis at 30 mins, 60 mins and 120 mins after radionuclide administration. ◦Place shielding over the injection sites to decrease scatter artifact. 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.  Contraindications to sentinel lymph node biopsy in gynecologic cancers include suspected extrauterine involvement, pathologic pelvic or para-aortic lymph nodes on imaging and a previous history of surgery or radiotherapy to nodal areas under study. Locoregional nodal invasion is the most important prognostic factor in cervical cancer. Cervical cancer spreads to lymph nodes in the following order: obturator, external iliac, common iliac and para-aortic. 80% of nodal metastases are ipsilateral when vulvar cancers are unilateral. Inguinofemoral lymphadenectomy in vulvar cancers is only performed when there is sentinel lymph node involvement. 55% of vaginal cancers drain to bilateral lymph nodes (most frequently inguinal nodes). 64% of ovarian cancers drain to bilateral lymph nodes. Nonvisualization of sentinel nodes occurs in 1-3% of vulvar cancers.

Nonvisualization of sentinel nodes occurs in 10-15% of cervical and endometrial cancers.