Final Breast Sentinel Node Guideline PDF

Eur J Nucl Med Mol Imaging DOI 10.1007/s00259-013-2544-2 GUIDELINES The EANM and SNMMI practice guideline for lymphoscintigraphy and sentinel node localization in breast cancer Francesco Giammarile & Naomi Alazraki & John N. Aarsvold & Riccardo A. Audisio & Edwin Glass & Sandra F. Grant & Jolanta...

Eur J Nucl Med Mol Imaging DOI 10.1007/s00259-013-2544-2 GUIDELINES The EANM and SNMMI practice guideline for lymphoscintigraphy and sentinel node localization in breast cancer Francesco Giammarile & Naomi Alazraki & John N. Aarsvold & Riccardo A. Audisio & Edwin Glass & Sandra F. Grant & Jolanta Kunikowska & Marjut Leidenius & Valeria M. Moncayo & Roger F. Uren & Wim J. G. Oyen & Renato A. Valdés Olmos & Sergi Vidal Sicart Received: 8 August 2013 / Accepted: 13 August 2013 # EANM 2013 Abstract distinguished experts from the EANM Oncology Committee, Purpose The accurate harvesting of a sentinel node in breast the SNMMI and the European Society of Surgical Oncology cancer includes a sequence of procedures with components (ESSO). from different medical specialities, including nuclear medi- Conclusion The present guidelines for nuclear medicine cine, radiology, surgical oncology and pathology. The aim of practitioners offer assistance in optimizing the diagnostic this document is to provide general information about sentinel information from the SLN procedure. These guidelines lymph node detection in breast cancer patients. describe protocols currently used routinely, but do not Methods The Society of Nuclear Medicine and Molecular include all existing procedures. They should therefore Imaging (SNMMI) and the European Association of Nuclear not be taken as exclusive of other nuclear medicine Medicine (EANM) have written and approved these guide- modalities that can be used to obtain comparable re- lines to promote the use of nuclear medicine procedures with sults. It is important to remember that the resources and high quality. The final result has been discussed by facilities available for patient care may vary. F. Giammarile (*) V. M. Moncayo Médecine Nucléaire, Hospices Civils de Lyon and EA 3738, Nuclear Medicine Service, Emory University, Atlanta, GA, USA Université Claude Bernard Lyon 1, Lyon, France e-mail: [email protected] R. F. Uren University of Sydney, Sydney, NSW, Australia N. Alazraki : J. N. Aarsvold : S. F. Grant Nuclear Medicine Service Veterans Affairs Medical Center and R. F. Uren Department of Radiology and Imaging Sciences, Emory University, Nuclear Medicine and Diagnostic Ultrasound, RPAH Medical Atlanta, GA, USA Centre, Suite 206, Newtown, NSW, Australia W. J. G. Oyen R. A. Audisio Department of Nuclear Medicine, Radboud University Nijmegen St Helens Teaching Hospital, University of Liverpool, St Helens, UK Medical Centre, Nijmegen, The Netherlands E. Glass R. A. Valdés Olmos Nuclear Medicine, Medical Imaging Center of Southern California, Department of Nuclear Medicine, Netherlands Cancer Institute, Santa Monica, CA, USA Amsterdam, The Netherlands J. Kunikowska R. A. Valdés Olmos Nuclear Medicine Department, Medical University of Warsaw, Interventional Molecular Imaging, Leiden University Medical Warsaw, Poland Center, Leiden, The Netherlands M. Leidenius S. Vidal Sicart Breast Surgery Unit, Helsinki University Central Hospital, Helsinki, Nuclear Medicine Department, Hospital Clinic Barcelona, Finland Barcelona, Spain  Eur J Nucl Med Mol Imaging Keywords Sentinelnode. Breastcancer. Lymphoscintigraphy. Qualifications and Responsibilities of Personnel; Procedures in Blue dye. Gamma probe. Gamma camera Nuclear Medicine; Procedures in the Surgical Suite; Radiation Dosimetry; and Issues Requiring Further Clarification. The present guideline has been prepared for nuclear med- Preamble icine practitioners. The intent is to offer assistance in optimiz- ing the diagnostic information that can be obtained from The Society of Nuclear Medicine and Molecular Imaging sentinel lymph node (SLN) procedures. If specific recommen- (SNMMI) and the European Association of Nuclear Medicine dations given cannot be based on evidence from original (EANM) have written and approved guidelines to promote the scientific studies, referral is made to “general consensus” use of nuclear medicine procedures with high quality. These and similar expressions. The recommendations are designed guidelines are intended to assist practitioners in providing to assist in the referral, performance, interpretation, and appropriate nuclear medicine care for patients. They are not reporting of the SLN procedure. inflexible rules or requirements of practice and are not intended, nor should they be used, to establish a legal standard of care. For these reasons and those set forth below, the Goals SNMMI and EANM caution against the use of these guide- lines in litigation in which the clinical decisions of a practi- The aim of this document is to provide general information tioner are called into question. about SLN detection in breast cancer patients. This guideline The ultimate judgment regarding the propriety of any spe- describes protocols currently used routinely, but does not cific procedure or course of action must be made by medical include all existing procedures. It should therefore not be professionals taking into account the unique circumstances of taken as exclusive of other nuclear medicine modalities that each case. Thus, an approach that differs from the guidelines can be used to obtain comparable results. It is important to does not necessarily imply that the approach was below the remember that the resources and facilities available for patient standard of care. To the contrary, a conscientious practitioner care may vary. The present guideline for nuclear medicine may responsibly adopt a course of action different from that practitioners offers assistance in optimizing the diagnostic set forth in the guidelines when, in the reasonable judgment of information from the SLN procedure. The final result has the practitioner, such course of action is indicated by the been discussed by distinguished experts from the EANM condition of the patient, limitations of available resources, or Oncology Committee, the SNMMI, and the European Society advances in knowledge or technology subsequent to publica- of Surgical Oncology (ESSO). tion of the guidelines. The practice of medicine involves not only the science, but also the art of dealing with the prevention, diagnosis, allevia- tion, and treatment of disease. The variety and complexity of Background and definitions human conditions make it impossible at times to identify the most appropriate diagnosis or to predict with certainty a Breast cancer is the most frequent cancer diagnosed in women particular response to treatment. Therefore, it should be rec- worldwide. SLNs are the regional nodes that directly drain ognized that adherence to these guidelines will not assure an lymph from the primary tumour. Thus, SLNs are the first accurate diagnosis or a successful outcome. All that should be nodes to receive lymph-borne metastatic cells. After the expected is that the practitioner will follow a reasonable description by Morton et al. of a method for SLN biopsy in the course of action based on current knowledge, available re- management of melanoma patients two decades ago, SLN sources, and the needs of the patient to deliver effective and mapping and biopsy have been used in breast cancer. Since safe medical care. The sole purpose of these guidelines is to then, SLN mapping and biopsy have become routine tech- assist practitioners in achieving this objective. niques in breast cancer management, contributing to the de- velopment of less-invasive surgical procedures [4–12]. Accurate lymph node staging is essential for both progno- Introduction sis (of early-stage disease) and treatment (for regional control of disease) in patients with breast cancer. Lymphoscintigraphy The accurate harvesting of a sentinel node in breast cancer (LS) allows the surgeon to easily identify and biopsy a SLN. includes a sequence of procedures with components from No imaging modality is accurate enough to detect lymph node different medical specialities, including nuclear medicine, metastases when a primary breast cancer is at an early stage radiology, surgical oncology, and pathology. The topics cov- (I or II), but SLN biopsy is a highly reliable method for ered are presented under the headings: Goals; Background and screening axillary nodes and for identifying metastatic and Definitions; Common Clinical Indications and Precautions; micrometastatic disease in regional lymphatic nodes [12–14]. Eur J Nucl Med Mol Imaging Despite the widespread use of SLN biopsy for early-stage Common indications breast cancer, there is significant variation in performance characteristics reported for the procedure. Differences in study SLN localization and biopsy are now the “standard of care” volumes and in lymphatic mapping techniques are two of the for staging the axillary lymph nodes in breast cancer patients. factors contributing to variations in the proportions of suc- These procedures have replaced routine staging axillary cessful mappings. The ranges of rates for false-negative lymph node dissection (ALND) in patients with early-stage findings and for SLN identifications emphasize the variability biopsy-proven breast carcinoma without cytologically or his- of this procedure. Learning curves for this technical procedure tologically proven axillary lymph node metastases [17, 18]. also vary. Nevertheless, once a multidisciplinary team is ALND is a standard treatment for patients with axillary experienced with the procedure, reasonable levels of accuracy metastases identified on SLN procedures. ALND is also an are achieved, with identification rates of more than 95 % often-used option in the management of patients in whom a reported routinely. SLN is not identified intraoperatively, but what should be the standard care in such patients is unresolved. A treatment alternative in patients with metastatic axillary SLNs is axillary Common clinical indications and precautions radiotherapy. These two treatment options (ALND and radio- therapy) are being compared in the EORTC AMAROS trial Indications for a SLN procedure include, but are not limited (ongoing). A concern regarding these patients arises from to, those in the following discussion. Table 1 is a list of several data suggesting fewer than 40 % of those with positive axil- indications, together with recommendations as to whether a lary SLNs have non-sentinel nodes with metastases. SLN procedure is established standard care. Investigations to identify risk factors for non-sentinel node metastases have been conducted with the goal of identifying a Table 1 Recommendations regarding use of SLN biopsy subgroup in whom ALND could be omitted despite metastatic findings in axillary SLNs. The identified risk factors can be Clinical circumstance Use of SLN biopsy combined and normograms created to evaluate the risk of T1 or T2 tumour Established residual disease in the axilla [21–23]. Another concern regard- T3 or T4 tumour Controversial (see “T3 and T4 tumours”) ing these patients arises from data obtained in a recent ran- Multicentric or Controversial (see “Multifocal and domized study in which it was concluded ALND provides multifocal tumour multicentric tumours”) no advantage in SLN-positive patients with breast- Inflammatory breast cancer Not recommended conserving surgery and whole-breast radiotherapy [24, DCIS with mastectomy Established (see “Ductal carcinoma in situ”) 25]. However, patients with micrometastases were over- DCIS without mastectomy Controversial, except for DCIS with represented in this study, especially in the arm without suspected or proven microinvasion ALND. Also, the follow-up was too short to draw (see “Ductal carcinoma in situ”) definitive conclusions regarding survival. Nevertheless, re- Suspicious, palpable Controversial (see “Suspicious palpable sults suggest the majority of SLN-positive patients may axillary nodes nodes”) not benefit from ALND [26–28]. Older age Established Patients with negative axillary SLN biopsy by routine Obesity Established histopathological evaluation do not require ALND. The clin- Male breast cancer Established ical significance of isolated tumour cells detected by immu- Pregnancy Controversial (see “Precautions”) nohistochemistry is currently controversial. Neither the St Evaluation of internal Controversial (see “Evaluation of internal Gallen nor the American Society of Clinical Oncology mammary lymph nodes mammary and other extra-axillary nodes”) (ASCO) guidelines recommend ALND in patients with iso- Prior diagnostic or Controversial (see “Prior breast surgery excisional breast biopsy other than excisional biopsy”) lated tumour cells in their SLNs [30–32]. Prior axillary surgery Controversial (see “Prior axillary surgery”) Axillary SLN biopsy procedures are now preferred to Prior nononcological breast Controversial (see “Prior breast surgery ALND for routine axillary staging in early breast cancer [14, surgery other than excisional biopsy”) 30–34] in many if not most clinical scenarios, as detailed in After preoperative systemic Controversial (see “Neoadjuvant Table 1 and in guidelines of the ASCO. In these patients, therapy chemotherapy”) SLN biopsy has a positive node rate similar to that observed in Before preoperative Established patients who have axillary lymphadenectomy [14, 35]. SLN systemic therapy biopsy has significantly lower morbidity than axillary lymph- Controversial indications are those for which SLN biopsy is not univer- adenectomy , and it has nodal relapse rates at 5 years similar sally accepted or for which the evidence behind the practice is limited or to those of axillary lymphadenectomy. No significant entirely missing (see “Issues requiring further clarification”) differences in disease-free survival, overall survival, or local DCIS ductal carcinoma in situ control of disease have been seen with a negative SLN.  Eur J Nucl Med Mol Imaging Precautions the goal is axillary staging only, a superficial tracer injec- tion (periareolar, subareolar, subdermal, intradermal) may Pregnant patients be preferable to a deep injection (peritumoral, intratumoral) due to better visualization of axillary SLNs. Some Pregnancy is not a contraindication for radiotracer-based SLN centres prefer dual injections, superficial and deep. The biopsy [18, 38, 39]. Blue dye should only be included in SLN use of dual injections captures the advantages of both biopsy in a pregnant woman if there is clear medical need. The techniques and is associated with lower false-negative re- use of SLN mapping involving the limited doses of radio- sults. If one’s aim is to stage extra-axillary nodal tracers outlined in this guideline has been demonstrated to basins as well as the axilla, tumour-related deep injection expose a fetus to a negligible dose, particularly when activities is recommended. below 10 MBq are used. In the case of pregnancy or Preoperative radiotracer lymphoscintigraphic mapping lactation, LS and SLN biopsy are justified by the low risks of is highly recommended because of the potential added the procedure relative to the risks of axillary dissection. benefits in both improving accuracy and reducing mor- Nonetheless, admission of a pregnant woman to a nuclear bidity relative to the use of the hand-held gamma probe medicine department and potential psychological concerns alone. Preoperative imaging also serves as quality must be considered before allowing the procedure. control on the use of the appropriate tracer, failure of the injection, failure of the radiopharmaceutical, and Nursing mothers management of the appropriate breast and axilla—injec- tion of the proper side (L/R). Some surgeons do not use Nursing mothers should suspend breast feeding for 24 h after preoperative LS because in their environments doing so radiopharmaceutical administration. results in scheduling delays; others do not do so be- cause there is no evidence that LS is associated with a higher intraoperative success rate in the harvesting of axillary Qualifications and responsibilities of personnel SLNs [47, 48]. SLN studies should only be performed by surgeons and Patient preparation nuclear medicine specialists who have undergone specific training in such procedures. At this time, no defini- No special preparation is required of a patient prior to her or tion of required training has been validated for either his arrival in the nuclear medicine department. In all patients, surgeons or nuclear medicine specialists, although a re- recent (not older than 1 month) mammograms should be quirement of at least 30 procedures under guidance has available, as should all recent breast ultrasound images and been proposed for each surgeon intending to perform SLN magnetic resonance images. All available images should be biopsies [42–44]. reviewed by the nuclear medicine physician. In female pa- tients, pregnancy status and lactating status should be deter- mined so that appropriate steps are taken to keep the exposure Procedures in nuclear medicine to radiation of patients, fetuses, and infants (through milk) as low as reasonably possible. The procedure for SLN detection and localization may include In the nuclear medicine department, in preparation for a combination of radiopharmaceutical, coloured or fluorescent imaging, the patient should remove all clothing and jewellery dye, preoperative scintigraphic imaging, and intraoperative above the waist. gamma probe localization followed by surgical removal of In all patients, a physical examination of the breast should detected SLNs. be performed by the nuclear medicine physician before injec- Although there is consensus on some broad aspects of tion of the radiopharmaceutical. If localization wires are in SLN protocols in breast cancer, consensus does not exist place or if a patient has recently undergone an excisional on all details. Controversies exist with regard to the par- biopsy, such should be known by the nuclear medicine ticle size of the radiotracer, the optimal route for injection, practitioners. timing of scintigraphy and intraoperative detection, and It is strongly recommended that the nuclear medicine whether or not extra-axillary lymph nodes should be con- physician communicate with the surgeon prior to and sidered. The specific radiotracer and technique used are after the imaging procedures and that such communica- additionally guided by local availabilities, regulations, and tions be documented. The communication should take practices. place particularly if the final report is not available prior False-negative rates and axillary recurrence rates have to surgery. The surgeon should, at the time of surgery, proved to be similar regardless of the site of injection. If have access to all images. Eur J Nucl Med Mol Imaging Radiopharmaceuticals Studies have shown the success rate of identification of axillary SLNs is not significantly affected by the particle size Several 99mTc-based agents have been used for radioguided of the radiotracer [52–55]. Thus, the selection of radiotracer is SLN biopsy in breast cancer. Table 2 provides a summary of based more on local availability than on differences in SLN those most widely investigated, including colloid particles detection. In the US, 99mTc-sulphur colloid is the radiocolloid (antimony trisulphide—Australia and Canada; nanocolloid commonly used for SLN biopsy. Unfiltered 99mTc-sulphur albumin—Europe; sulphur colloid—USA) and a novel colloid comprises particles with a wide range of sizes (15– receptor-targeting small molecule. 5,000 nm, depending on the preparation method), with an The ideal radiotracer should show rapid transit to SLNs average size ranging from 305 to 340 nm. Filtered 99mTc- with prolonged retention in the nodes. In general, the drain- sulphur colloid is usually obtained using a 0.22-μm filter. age, distribution, and clearance of radioactive colloids by the The result is a suspension with colloid particles that are mostly lymphatic system may vary and are dependent on the size of between 100 nm and 220 nm. A small-particle colloid, 99mTc- the particles. Small particles are drained and cleared first; large nanocolloidal albumin (Nanocoll®), is the licensed and pre- particles are drained and cleared last and may be retained ferred agent in most of Europe; the size of its particles ranges longer at the injection site. There is general agreement that a from 5 to 100 nm. The colloid used most in Australia and radiocolloid should be a good compromise between fast lym- Canada is 99mTc-antimony trisulphide; the size of the particles phatic drainage and optimal retention in SLNs [30, 50]. Ide- most commonly used ranges from 3 to 30 nm. ally, the draining lymphatic collectors (channels) are visual- The tracer must be prepared and labelled with 99mTc- ized so that the SLN receiving tracer from a collector can be pertechnetate using the relevant manufacturer’s instructions. identified and distinguished from any second tier node that A labelling yield greater than 90–95 % must be confirmed may appear later. before the radiopharmaceutical is injected into a patient. Hy- The particle size also determines the timing of preoper- persensitivity reactions to radiopharmaceuticals are rare but ative scintigraphy and intraoperative detection of SLNs. have been reported. See the SNM Guideline on Radiophar- While smaller particles allow quick visualization of SLNs, maceuticals for general requirements. larger particles have slow transit in the lymphatic system An alternative to radiocolloids is the radiopharmaceutical 99m that tends to minimize visualization of non-sentinel second Tc-tilmanocept (Lymphoseek®), which was approved by tier nodes (lymph nodes downstream of SLNs). SLNs the US Food and Drug Administration (FDA) in 2013. are generally visualized within 1–2 h, and the patient Tilmanocept is mannosyl diethylene-triamine-pentaacetate should be in the operating theatre within 2–30 h of the (DTPA) dextran. Its molecular size is approximately 7 nm. injection of the colloid, depending on the facility’s schedule Its uptake mechanism in lymph nodes is not dependent on [2, 15, 17]. If surgery is scheduled for early morning, particle size as it is a macromolecule-targeting agent; it targets injection and imaging may be safely performed the after- dextran-mannose receptors on the surface of macrophages, noon prior to the surgery. including dendritic cells in lymph nodes. Dendritic cells efficiently present the mannose receptor-mediated uptake of Lymphoseek to T cell lymphocytes in lymph nodes. Table 2 Characteristics of 99mTc-based radiopharmaceuticals Agent Particle size (nm) Activities and volumes Maximum Mean Consensus on the activity to be administered in a SLN proce- dure has not been reached. The investigated and suggested Sulphur colloid 350–5,000 (see text) 100–220 (filtered) activities vary considerably. Activities as low as 3.7 MBq Antimony trisulphide 80 3–30 (0.1 mCi) and as high as 370 MBq (10 mCi) have Sulphide nanocolloid 80 10–50 been used. A total injected dose of 5 to 30 MBq is generally (Lymphoscint®) Nanocolloidal albumin 100 5–80 considered sufficient for surgery planned for the same day. (Nanocoll®) When injection is done the afternoon prior to surgery, up to Rhenium sulphide 500 50–200 150 MBq is considered sufficient. When using superficial nanocolloid (Nanocis®) (periareolar, subdermal, intradermal, or subareolar) injections, Tin colloid 800 30–250 large volumes of injectate may interfere with normal lymphat- Labelled dextran 800 10–400 ic flow; therefore, volumes of 0.05–0.5 mL are preferred. Hydroxyethyl starch 1,000 100–1,000 With peritumoral injections, larger volumes (e.g. 0.5–1.0 mL) Stannous phytate 1,200 200–400 are used. When injecting small volumes (e.g. 0.1 mL), the Tilmanocept About 7 About 7 (Lymphoseek®) (equivalence) (equivalence) syringe may contain a small amount (0.1 mL) of air to clear any dead space within the tip of the syringe and the needle.  Eur J Nucl Med Mol Imaging Radiolabelled colloid particles are suspended; thus, they The site of injection can be gently massaged after tracer may settle by gravity if left in a motionless syringe for more administration to improve drainage of the tracer. Massage can than a few minutes. A syringe with colloid should be gently also be employed if passage of activity from the injection site rotated immediately prior to administration of the colloid to is delayed at any time during the study [61, 62]. ensure good mixing of the radiolabelled particles. Col- loids should not be aggressively agitated. Imaging procedure Injection procedure Quality control The optimal injection technique has been the subject of lively Quality control should be routinely performed on the imaging debate. Widely used techniques include peritumoral, subder- system and image display used in SLN procedures [69, 70]. mal, periareolar, intradermal, and subareolar injections. All Quality control should be routinely performed on the gamma enable axillary SLNs to be identified accurately, and satisfac- probe used in the nuclear medicine department and the oper- tory SLN detection rates have been reported for all injection ating theatre for SLN procedures. The reader is referred to approaches. Results of multiple studies have confirmed that the SNM Guideline for General Imaging for additional infor- the method of injection does not significantly affect the iden- mation. tification of axillary SLNs [61–63]. One major advantage of superficial injections is that they Imaging protocol are easy to perform. A subdermal, periareolar, intradermal, or subareolar injection, however, is often more painful than a Imaging is recommended before any operation, as there is peritumoral injection. The addition of pH-balanced 1 % lido- patient variability in breast lymphatic drainage into the caine to the radiopharmaceutical often improves patient com- axilla and extra-axillary regions. Imaging is an efficient fort without compromising SLN identification. The use means of determining if there is uptake of activity in any of peritumoral injections requires careful investigation of a node, and it improves the likelihood of identifying all patient’s prior imaging and medical records, particularly if the relevant node beds and thus the likelihood of locating all tumour is nonpalpable. If available, ultrasound guidance to SLNs. assist with placement of peritumoral injections can be helpful. If a tumour is in the upper outer quadrant, the relatively Imaging system A single- or dual-head gamma-camera sys- intense activity at the injection site may make localization of tem with large field-of-view (FOV) detectors is generally used a less-intense nearby SLN difficult [65, 66]. to acquire planar emission and, if desired, single-photon com- Important advantages of deep injections are improved de- puted tomographic (SPECT) or SPECT/CT images. Low- tection of extra-axillary SLNs and the possibility of using a energy, high-resolution (LEHR) or low-energy ultra-high res- larger injection volume. When administering deep injections, olution (LEUHR) collimators should be used. The energy care should be exercised to avoid injection into the dead space window should be 15 % (±5 %) centred on the 140 keV of a seroma resulting from a previous excisional biopsy or into photopeak of 99mTc. a breast prosthesis. After almost 20 years of experience, it is generally accepted Patient positions Most commonly, at each acquisition time that both deep and superficial injection approaches are valid point at least two or three images are acquired: anterior, lateral, and that they are often complementary. The combination of and 45° anterior oblique. Anterior images are acquired with both injection techniques (deep and superficial) may even the patient lying supine on the bed of the imaging system. In improve SLN detection and decrease false-negative findings the operating room, the patient most often lies supine with her/. Although the majority of superficial lymph vessels of the his arm on the side with cancer, extended perpendicular to her/ breast drain to only one SLN, a recent anatomical study on his body. It is recommended the patient extend her/his arm as breast lymphatics showed there are alternative lymphatic for the anterior images. Lateral images are also acquired with drainage pathways to primary pathways. The authors also the patient lying supine, with her/his arm on the side with found that separate lymphatic networks exist in the ventral cancer (R/L) extended. and dorsal parts of the breast. These drain to the axilla and the For acquisition of the 45° anterior oblique images, the internal mammary node (IMN) chain, respectively, without patient (not the camera) should be rotated from supine to apparent connections. This observation correlates with 45°, the patient’s arm on the side with cancer should be findings of a clinical study in which drainage to the IMN chain positioned above the head, and the camera should be posi- and other lymph node stations outside the axilla was seen for tioned directly above the patient. Rotation of the patient places tumours no matter in which quadrant of the breast they were the breast with cancer dependent toward the patient’s midline. located. This reduces attenuation of uptake in axillary nodes and Eur J Nucl Med Mol Imaging reduces the potential for projection overlap of the uptakes at registered with anatomical data. For SPECT/CT acquisi- the injection site and in axillary nodes. tion, a patient is positioned only once—an advantage for For lateral views, the patient might be rotated 90° from patients who are difficult to position. SPECT/CT pro- supine so that she/he is lying on her/his side contralateral to vides three-dimensional images that generally have better the cancer. In this position, the patient’s involved breast is contrast and spatial resolution than planar images. dependent toward the patient’s midline, away from the SPECT/CT allows the possibility of correction for effects axilla to be assessed. If rotation of a patient for 45° anterior of attenuation and scatter. It provides relatively precise oblique imaging is not possible, the camera can be posi- localization of SLNs within an anatomical landscape, tioned to acquire the images. In this case, if possible, the thus providing a valuable road-map for surgery. breast should be held toward the midline to allow better Based on published reports, current indications for imaging of the axilla to be assessed. If any of the above SPECT/CT include nonvisualization of SLN on conven- imaging is not possible, useful images with the patient in tional planar imaging, patient obesity, and the presence of an upright position or in a prone position with breasts extra-axillary SLNs, or otherwise unusual difficult-to- dependent may be possible. characterize drainage (e.g. multiple sites of drainage, visualization of IMN chain, intramammary lymph node, Image acquisition nodes in the contralateral axilla, or previous breast sur- gery). SPECT/CT might also be performed if the con- Dynamic (flow) imaging ventional images are difficult to interpret (e.g. suspicion Although not often used in SLN procedures for breast of contamination or a SLN near the injection area) cancer, dynamic (flow) imaging can provide information [75–78]. useful for SLN localization. If dynamic imaging is to be SPECT acquisition for SLN detection should be performed, it should be started immediately after com- performed with a dual-detector SPECT system equipped pletion of all injections. with LEHR or LEUHR collimators. Acquisition parame- Planar (static) imaging ters should include a matrix size of 128×128 (4–5 mm Planar (static) imaging should be performed 15– pixels) and 120 or 128 projections over 360° with 20– 30 min, 1 h, and 2–4 h after injection, and as needed 25 s/projection. If SPECT reconstruction includes reso- thereafter up to 18–24 h. At least two, preferably all three, lution recovery, the number of projections or the time per of the following images should be acquired: anterior, 45° projection may be reduced as recommended by the ven- anterior oblique, and lateral. Each image acquisition is dor of the resolution recovery software. typically 3 to 5 min in duration. For a system with large Both low-dose CT (140 kVp, 2.5 mA) and conven- FOV detectors, it is recommended that the pixel size be tional CT (140 kVp, 30–150 mA) can provide useful approximately 2 mm and the matrix size be 256×256 anatomical detail that can be used for anatomical locali- with zoom 1 or, rarely, 128×128 with zoom 2. If a 2-mm zation and if desired, attenuation correction. pixel size is not feasible on a system, the smallest pixel Image storage size available should be used. All images obtained should be stored in a permanent Transmission imaging form according to national and other relevant regulations. The patient’s body contour should be delineated for positioning and referencing foci of activity. To accom- Skin marking plish this, a 57Co or 99mTc flood source can be appropri- ately positioned on the side of the body opposite the Surface marks that provide a means to triangulate SLNs camera or a 57Co or 99mTc “point” source can be used and a means to estimate their depths are desired by some to trace the body contour. surgeons. Imaging from at least two projections should be Because the amount of tracer uptake in a node does not performed. Surface locations should be marked on the skin correlate with the likelihood of it being the SLN, quanti- with a small spot of indelible ink, and the depth of the fication of tracer uptake in nodes is not necessary or node should be noted. When marking the skin in the helpful. In addition, removal of all axillary nodes with imaging process, an attempt should be made to position radioactivity leads to fewer false-negative SLN biopsies the patient as she/he would be positioned for surgery. If. Anatomical localization of tracer uptake is therefore more than one node is found in the same region, some sufficient. practitioners prefer to mark just the hottest node(s) and Optional/alternate imaging (SPECT or SPECT/CT) describe and display the other nodes on accompanying Conventional planar imaging does not give exact pre- reports and images. If SPECT/CT imaging is available, operative anatomical localizations of detected nodes. appropriate coregistered images should be made available SPECT/CT provides tomographic lymphoscintigrams at the time of surgery.  Eur J Nucl Med Mol Imaging Image processing should be performed after the patient is anaesthetized to avoid painful injection. If local anaesthesia is to be used, the local No particular processing procedures are needed for planar anaesthetic should be administered using a separate syringe images. Truncation of high activities (the injection sites) will (e.g. lidocaine) since the admixture of isosulfan blue with improve visualization of the SLN. A logarithmic scale to local anaesthetics in the same syringe results in immediate enhance low-count areas instead of a linear scale is preferable precipitation of 4–9 % drug complex. Five minutes of mas- for image display. Processing parameters should be carefully sage of the injection site enhances movement of the dye chosen so as to optimize image quality (see SNM Guideline through the lymphatics to the SLN. Within 5–15 min the for General Imaging ). SLNs are coloured. Washout is evident after approximately 45 min. Interpretation Multiple studies have established the validity of blue dyes as markers for SLNs. The study results include reasonably Early and delayed lymphoscintigraphic planar images high detection rates (ranging from 75 % to 95 %) , identify SLNs in the majority of patients. Major criteria although they are slightly lower than those achieved when to identify lymph nodes as SLNs are the time of ap- radiopharmaceuticals are used. In most cases, the same SLNs pearance and occasionally visualization of lymphatic are detected by the two methods. A notable disadvantage of channels (if dynamic imaging was performed). Usually, using blue dyes is that blue dyes are not helpful if extra- SLNs cannot be readily distinguished from second tier axillary nodes (IMN or supraclavicular nodes) are to be eval- lymph nodes. The SLN is not necessarily the hottest uated [80, 81]. Another disadvantage in patients who are node, although that is often the case. Separate lymphatic having breast-conserving surgery is the temporary blue channels that drain to different lymph nodes identify tattooing of the skin or areola when the dye is injected each of these as distinct SLNs, even though they may superficially. be located in the same anatomical region. When drain- It is important to be aware of contraindications for the use age to more than one anatomical region is seen, each of of blue dyes. Blue dyes may interfere with pulse oximetry these regions has at least one SLN. readings, so in certain patients they should be used with The report to the referring physician should describe the caution. Blue dye can induce anaphylactic reactions that re- orientations of the images acquired, the radiopharmaceutical, quire resuscitation in 0.5 to 1.0 % of patients. Hypersensitivity the method of administration, the dose and volume of activity to the product is the only contraindication. Blue dye should injected, the location of the SLNs on each image, and any not be used in pregnant women because of the risk of ana- source of error or inaccuracy of the procedure. The images and phylactic reaction. Blue dye should also not be used if there is report should be available by the time the patient arrives in the prior evidence of a patient having had an allergic reaction to surgical suite—in electronic form or as hard copy. If this is not this type of agent or of a patient having severe renal impair- possible, the critical information should be relayed directly to ment [79–85]. the surgeon. A close working relationship between the imaging department and the surgeon are critical for accurate dissemina- Radioguided surgery tion of information regarding numbers and locations of nodes. Detection probes must be able to detect SLNs from the skin surface as well as within exposed surgical cavities. Procedures in the surgical suite The first task requires that the sensitivity of the detector is sufficient to identify a weakly active SLN when attenuated Blue-dye node localization by up to 5 cm of soft tissue. Discriminating activity within a SLN also requires that the probe be well collimated for a Most breast cancer surgeons combine LS/probe information small angle view. It is thus advisable that the major component with information obtained using blue dye injected during of collimation be in the form of a detachable collimator of surgery. This combining of information is an excellent method suitable construction. This allows it to be removed when it is for decreasing false-negative findings and increasing sensitiv- not required, rendering the probe more compact and more ity [45, 62]. sensitive. The detector should be constructed to offer a Currently, the commonly used dyes are patent blue V, high level of shielding against radiation hitting the side of isosulfan blue, and methylene blue. Blue dye can be injected the probe assembly. The whole system should be designed around the primary tumour in a manner similar to that for and constructed to be suitable for intraoperative use. radiopharmaceutical injections, 10–20 min prior to surgery in The detector itself should be ergonomically designed for a volume of 2–5 mL. Care should be exercised to avoid easy manoeuvrability and constructed so as to be suitable injection into the dead space of a seroma. The injection for sterilization. Eur J Nucl Med Mol Imaging When used intraoperatively, a probe is placed in a sterile visualized, increasing false-negative results. To minimize bag so that it can be used in the sterile surgical field. A display false-negative results, the open axilla should be palpated and capable of providing clear instantaneous and cumulative suspicious lymph nodes harvested, even if these are neither counts is a major requirement. It is helpful if the instantaneous hot nor blue. In cases of nonvisualization or if the SLN is count-rate is fed to an audio signal that conveys count rate located outside the lower medial part of the axilla, palpation of information. Many commercial models are available with the typical SLN area is particularly important. discernible differences [69, 86]. In the European Union, it is Radioactive waste in the operating room (sponges, a requirement that all medical equipment have CE certifica- etc.) and in pathology should be collected according to tion. Medical devices marketed in the USA must be approved institutional radiation safety procedures. This waste will by the FDA. Neither body, however, enforces mandatory also be a biohazard and should be handled accordingly. compliance with the most widely recognized international Personnel not accustomed to dealing with radioactive electromedical safety standard IEC 60601. Thus, infor- materials should be educated as to their safe handling mation regarding compatibility with regional requirements and disposal. Appropriate education of surgical suite should be separately sought from the manufacturer of a device. personnel and pathologists will often be very valuable for Using the images and skin markings as guides, the probe the establishment of appropriate handling of radioactive ma- (placed over the regions of highest counts) can be used to terials, reassurance of concerned individuals and expedient select the optimum location for incision. The surgeon uses the processing of tissues. probe to guide dissection to the hot node(s) and places the probe in the surgical bed after node excision to confirm SLN nonvisualization removal of the hot node(s). In working with the probe, it is important to direct the probe away from activity at the injection The majority of patients with preoperative lymphoscintigraphic sites. Counts are recorded per unit time with the probe in the SLN nonvisualization will have at least one SLN detected operative field, over the node before excision (in vivo), and intraoperatively, either by gamma probe alone or by gamma after excision (ex vivo). A background tissue count is also probe combined with blue dye. While logistically difficult in recorded with the probe pointing away from the injection site, most centres, a second radiotracer injection, at perhaps a dif- nodal activity, or other physiological accumulations (e.g. liver). ferent injection site, may be useful to visualize previously The identified SLNs are removed by the surgeon. When a nonvisualized SLNs. hot node has been removed, the wound site should be checked In approximately 1 to 2 % of patients, SLNs will not be for remaining activity. Due to the limited spatial resolution of detected preoperatively or intraoperatively and the status of gamma cameras, nodes closer than about 15–20 mm may the axillary nodes cannot be determined. Old age, obesity, appear as one spot. Thus, after removal of one node, another tumour location other than the upper outer quadrant, and hot node may still be present. The current use of SPECT/CT nonvisualization of SLNs on preoperative LS may be associ- may reveal the presence of a cluster of lymph nodes on CT ated with failed SLN localization. The significance of images. The number of nodes to remove from any one basin preoperative scintigraphic nonvisualization is not yet known. will depend on the report from LS and local practice [88, 89]. Some studies have suggested that patients with unsuccessful Deeply located SLNs are difficult to detect because of axillary mapping may have an increased risk of positive attenuation and radioactivity at the injection site that may axillary involvement. There is no definitive consensus cause nearby SLNs to be hidden. This situation is observed on what to do if a SLN cannot be visualized. However, current mostly when tumours are in the superior outer quadrant and standards of care recommend ALND when intraoperative when tumours are located in inner quadrants and SLNs are in SLN identification is not achieved. the IMN. It is advisable to use smaller diameter probes (e.g. 10 mm diameter probes) in intercostal areas as they generally Multiple SLNs allow focal activity in limited surgical spaces to be localized more easily. The use of SPECT/CT images can help In principle, SLN biopsy requires the removal of all SLNs localize focal activity as can the use of intraoperative imaging receiving direct lymphatic drainage from the site of the with portable gamma cameras [91, 92]. primary tumour. In practice, this is not always achieved. Patients who have undergone previous breast surgery or The question remains as to how many SLNs should be received radiation may demonstrate nodes in locations not biopsied when multiple nodes are found. In patients with typically seen in patients without a history of prior surgery. multiple radiolabelled nodes, it is often difficult to distin- The lymphatic duct to the original SLN may be obstructed by guish between SLNs and second tier nodes. However, tumour growth or the original SLN may be entirely replaced removing more than five nodes from the axilla does not by disease. Consequently, lymphatic drainage may be either result in marked improvement in the sensitivity of axillary diverted to a non-sentinel node or no lymph nodes may be SLN biopsy [90–100].  Eur J Nucl Med Mol Imaging Histopathology 112–115, 118, 119] have been reported by several investiga- tors and are offered in relevant radiopharmaceutical package Before specimens are sent for histological examination, they inserts [120, 121]. Table 3 is a summary and interpretation of should be evaluated ex vivo using the probe to demonstrate much of the available data. that they are radioactive. This evaluation should be All of the published data indicate that exposures to patients performed on all nodal specimens and all tumour specimens. and professionals from SLN procedures are minimal. Low Histopathological assessment of SLNs is the “gold stan- patient effective dose and very low fetus/uterus equivalent dard” procedure for the subsequent surgical management of dose [39, 40, 101, 109, 110, 123] indicate exposure to radiation breast cancer patients. However, this gold standard is highly is not a contraindication for a SLN procedure in any patient, variable among centres. In many institutions, SLNs are including pregnant patients. However, prudence dictates that assessed intraoperatively using imprint cytology, frozen sec- care should be exhibited when conducting a SLN procedure on tioning, or both, and more thoroughly after the operation. The any patient. In patients who are breast feeding, nursing should sensitivity of the intraoperative diagnosis is variable and many be suspended for 24 h following radiopharmaceutical admin- facilities do not adopt it at all. Some molecular methods istration. Regarding professionals, the United States Nuclear have been used previously for SLN diagnosis, but have shown Regulatory Commission (NRC) has determined that the expo- a lack of reproducibility, require a longer time for the sures to pathologists from radioactive SLN specimens are too intraoperative assessment, and provide no means to study small to require regulation. The injection site absorbed the whole lymph node. A new molecular method has been dose can be significant (see able 3). There are no known developed recently. It is based on a one-step nucleic acid negative consequences of this. The site is often, but not always, amplification (OSNA) method. This procedure is in validation excised. The dose is very small relative to that received from studies in many centres; it is in routine use in others. postoperative radiation therapy. Because exposures in SLN procedures of all non-nuclear medicine personnel are low, none need be monitored routinely for radiation exposure. The Radiation dosimetry decision to badge personnel involved only with SLN proce- dures is at the discretion of individuals and local custom. Nuclear medicine, surgery, and pathology professionals are Absorbed doses and equivalent doses to several organs involved if a radiopharmaceutical is used in a SLN procedure. have been estimated and can be found in tables in a few Each involved practitioner and the patients receiving such publications and relevant package inserts [104, 106, 110, procedures are exposed to radiation. The exposures received 120, 121, 125]. The dose to a patient from a transmission by each, when doses standard for SLN procedures are admin- source will vary. One estimate of the dose from a transmission istered, are well below recommended limits for both public source is 0.003 mSv [106, 107]. The dose from a CT scan also and thus occupational exposures. varies. One estimate of the dose from the CT element of a Estimates of exposures to patients [101, 104–110], sur- SPECT/CT scan is 2.4 mSv. A low-dose CT scan with a geons [101, 105, 107, 111–117], and pathologists [101, 105, field of view limited to avoid radiosensitive tissues can help Table 3 Ranges of estimates of radiation exposures Radiation exposure Range of estimatesa × 18.5 MBq × 100 patients/yearb Public limitc Occupational limitc Injection site absorbed dose 1 to 50 mGy/MBq