Radiation dose estimates for interstitial radiocolloid lymphoscintigraphy

Short-term and long-term outcomes of indocyanine green for sentinel lymph node biopsy in early-stage breast cancer

Background

Indocyanine green (ICG) is becoming a frequently used sentinel lymph node (SLN) tracer of breast cancer in China. However, there is still a lack of data on its safety. We reported the clinical outcome of ICG as a tracer of SLN over a median 67-month follow-up period to evaluate its feasibility in clinically node-negative patients with breast cancer.

Methods

A total of 194 consecutive patients underwent sentinel lymph node biopsy (SLNB) with ICG, radioisotopes (RI) and methylene blue (MB), or with ICG and MB. The SLN mapping data by each tracer was recorded, and safety outcomes were analyzed through follow-up.

Results

With the triad mapping (N = 44), the identification rate of SLN by ICG was 95.5%, slightly higher than that of MB (86.4%) and comparable with RI (95.5%) and combined methods (95.5%, 100%) (p = 0.068). Analysis of all candidates (N = 194) demonstrated that the identification rate of SLN by ICG or by ICG and MB was 99%, significantly higher than that by MB (92.8%) (p < 0.0001). No tracer-related allergic reaction and permanent skin staining of ICG were observed. Local disease progression was reported in 2 of the 194 patients at the ipsilateral axilla. After remedial axillary lymph node dissection, no disease progression was detected at follow-up.

Conclusions

ICG as an SLN tracer is more accurate than MB and comparable to the combined methods and has good clinical safety. ICG can be considered a useful supplement or suitable alternative to traditional tracers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02719-7.

Meta-analysis Comparing Fluorescence Imaging with Radioisotope and Blue Dye-Guided Sentinel Node Identification for Breast Cancer Surgery

INTRODUCTION

Conventional methods for axillary sentinel lymph node biopsy (SLNB) are fraught with complications such as allergic reactions, skin tattooing, radiation, and limitations on infrastructure. A novel technique has been developed for lymphatic mapping utilizing fluorescence imaging. This meta-analysis aims to compare the gold standard blue dye and radioisotope (BD-RI) technique with fluorescence-guided SLNB using indocyanine green (ICG).

METHODS

This study was registered with PROSPERO (CRD42019129224). The MEDLINE, EMBASE, Scopus, and Web of Science databases were searched using the Medical Subject Heading (MESH) terms 'Surgery' AND 'Lymph node' AND 'Near infrared fluorescence' AND 'Indocyanine green'. Studies containing raw data on the sentinel node identification rate in breast cancer surgery were included. A heterogeneity test (using Cochran's Q) determined the use of fixed- or random-effects models for pooled odds ratios (OR).

RESULTS

Overall, 1748 studies were screened, of which 10 met the inclusion criteria for meta-analysis. ICG was equivalent to radioisotope (RI) at sentinel node identification (OR 2.58, 95% confidence interval [CI] 0.35-19.08, p < 0.05) but superior to blue dye (BD) (OR 9.07, 95% CI 6.73-12.23, p < 0.05). Furthermore, ICG was superior to the gold standard BD-RI technique (OR 4.22, 95% CI 2.17-8.20, p < 0.001).

CONCLUSION

Fluorescence imaging for axillary sentinel node identification with ICG is equivalent to the single technique using RI, and superior to the dual technique (RI-BD) and single technique with BD. Hospitals using RI and/or BD could consider changing their practice to ICG given the comparable efficacy and improved safety profile, as well as the lesser burden on hospital infrastructure.

EANM practice guidelines for lymphoscintigraphy and sentinel lymph node biopsy in melanoma

PURPOSE

Sentinel lymph node biopsy is an essential staging tool in patients with clinically localized melanoma. The harvesting of a sentinel lymph node entails a sequence of procedures with participation of specialists in nuclear medicine, radiology, surgery and pathology. The aim of this document is to provide guidelines for nuclear medicine physicians performing lymphoscintigraphy for sentinel lymph node detection in patients with melanoma.

METHODS

These practice guidelines were written and have been approved by the European Association of Nuclear Medicine (EANM) to promote high-quality lymphoscintigraphy. The final result has been discussed by distinguished experts from the EANM Oncology Committee, national nuclear medicine societies, the European Society of Surgical Oncology (ESSO) and the European Association for Research and Treatment of Cancer (EORTC) melanoma group. The document has been endorsed by the Society of Nuclear Medicine and Molecular Imaging (SNMMI).

CONCLUSION

The present practice guidelines will help nuclear medicine practitioners play their essential role in providing high-quality lymphatic mapping for the care of melanoma patients.

EANM-EORTC general recommendations for sentinel node diagnostics in melanoma

The accurate diagnosis of a sentinel node in melanoma includes a sequence of procedures from different medical specialities (nuclear medicine, surgery, oncology, and pathology). The items covered are presented in 11 sections and a reference list: (1) definition of a sentinel node, (2) clinical indications, (3) radiopharmaceuticals and activity injected, (4) dosimetry, (5) injection technique, (6) image acquisition and interpretation, (7) report and display, (8) use of dye, (9) gamma probe detection, (10) surgical techniques in sentinel node biopsy, and (11) pathological evaluation of melanoma-draining sentinel lymph nodes. If specific recommendations given cannot be based on evidence from original, scientific studies, referral is given to "general consensus" and similar expressions. The recommendations are designed to assist in the practice of referral to, performance, interpretation and reporting of all steps of the sentinel node procedure in the hope of setting state-of-the-art standards for good-quality evaluation of possible spread to the lymphatic system in intermediate-to-high risk melanoma without clinical signs of dissemination.

Sentinel node biopsy: an in depth appraisal

Sentinel node biopsy (SNB) in primary breast cancer has been taken-up widely to avoid the morbidity attributable to axillary node clearance (ANC). Currently many issues surrounding SNB are undecided. This review summarises why some form of axillary surgery is required and presents data on all aspects of SNB including methodology, clinical results and problems that may delay the introduction of SNB as best practice for all patients with primary breast cancer. There is no long or medium term data relating to the consequences of replacing ANC with SNB, but the mechanisms and probable magnitude of both beneficial and detrimental effects are estimated. A low level of false negative results are inherent to the technique but it is demonstrated that SNB is likely to have an only marginal (0.6%) effect on survival that would be undetectable by clinical trials. Patient sub-groups particularly likely to benefit from SNB are identified.

How iliopelvic lymphoscintigraphy can affect the definition of planning target volume in radiation therapy of pelvic and testicular tumors

PURPOSE

External beam radiation therapy (EBRT) of most intrapelvic and testicular tumors has been generally performed with large fields encompassing both the primary disease and lymphatic drainage. This study was carried out to map the pelvic and periaortic lymphatics by means of iliopelvic lymphoscintigraphy (IPL) in preparation for radiotherapy planning.

METHODS AND MATERIALS

Between January 2000 and October 2001, 70 patients scheduled for EBRT (61 operated on, 52 females, 18 males, mean age 61, range, 24-80), affected with uterine (43), rectal (11), testicular (8), anal (4), penile (2), and vulvar (2) cancers were enrolled in the study. IPL was performed by injection of 99mtechnetium-nanocolloids in the bipedal (70 cases) or bipedal plus perianal (20 cases) sites. The sensitivity of IPL in mapping the lymphatic anatomy was evaluated first. Then three radiation oncologists scored the modifications induced by IPL on the planning target volume (PTV) which had been previously delineated only on the basis of bony landmarks. The original fields were classified "inadequate" if they failed to match the new PTV by more than 1 cm.

RESULTS

IPL sensitivity in showing the inguinal, external iliac, common, and periaortic lymphatics was 100%, 90%, 80%, and 70% in anterior-posterior (A-P) projections, and 100%, 80%, 70%, and 60% in lateral projections respectively. For the presacral and hypogastric ones the sensitivity was 40%. When compared with bony landmarks, IPL changed the delineation of PTV in 24 of 70 A-P P-A fields (34%) and 22 of 58 (38%) lateral fields. Furthermore, 8/12 (67%) lymphadenectomies resulted in being incomplete. No IPL-related toxicity was observed.

CONCLUSION

IPL is a safe, inexpensive (cost: 100 Euros), and effective method to map the lymphatic chains. In the A-P scintigrams these structures were detected in 85% (70-100%) of the patients referred for total pelvis irradiation, and this figure could be higher in subjects not operated on. IPL can also give a reliable evaluation of the lymphadenectomies in order to schedule the proper treatments after surgery. Finally, IPL may change the conventional PTV for pelvic irradiation in about 36% (34-38%) of the cases; therefore, the fields should be tailored more around the lymphatic landmarks than the bony landmarks.

The lymphatic drainage of the human ovary in vivo investigated by isotopic lymphography before and after the menopause

The authors report 14 lymphoscintigraphies of the ovary, 8 before and 6 after the menopause. Injection of colloid labeled with technetium 99 m with elective lymphatic absorption was made into the mesovarium under laparoscopic control. Frontal and lateral images of the lymphatic drainage were made with a gamma camera 4-6 h after injection. Even in this short preliminary series, the premenopausal women showed major local and regional lymphatic circulation with drainage to the lumbo-aortic and pelvic nodes. After the menopause the lymphatic flow decreased and drainage was essentially by the aorto-lumbar nodes.

An easy method for diagnosis of lymphedema

Lymphoscintigraphy has been very useful in determination of lymphatic abnormalities. However, the radioactive isotopes used have been investigational and difficult obtain. The purpose of this study was to examine patients with extremity edema by lymphoscintigraphy using a radioactive colloid readily available in our nuclear pharmacy, Technetium 99m sulfur minicolloid. Forty limbs in 20 patients were evaluated using Technetium 99m sulfur minicolloid lymphoscintigraphy. All patients had lower extremity edema initially attributed to a venous or lymphatic etiology. There were 12 patients with normal bilateral studies. Seven patients exhibited unilateral obstruction to lymphatic flow, and one had unilateral enhanced flow of lymph. Those with normal studies included five patients with nonspecific edema, four with varicosities, and one patient each with acute deep vein thrombosis, chylous ascites, and excision of the greater saphenous vein for arterial bypass grafting. Five patients with obstructed patterns had previous arterial bypass procedures, one had trauma to the extremity, and one had lymphedema tarda. The one enhanced lymphoscintigraphic pattern was seen in a patient with acute cellulitis. All patients had Doppler venous examinations and other studies included strain gauge phlethysmography, venograms, computed tomography, magnetic resonance imaging, and ultrasound. As with other scintigraphic imaging agents used to study lymphatic flow, Technetium 99m provides clinically useful information in evaluating the swollen extremity noninvasively.

Dosimetric consequences of interstitial extravasation following i.v. administration of a radiopharmaceutical

The worst case radiation dose to tissue due to inadvertent intravenous injection of a radiopharmaceutical was estimated for the most commonly utilised radioisotopes. The probability of radiation injury induction was examined for the various radionuclides considering the maximal specific activity values encountered in diagnostic practice. A possible approach to the management of incidents involving extravasal activity deposition is discussed.

Abdominal lymphoscintigraphy: an effective substitute for lymphography?

Abdominal lymphoscintigraphy is a quick, easy, cheap and relatively non-invasive technique. In our study it appeared to be as accurate as lymphography, giving a positive correlation in 25 out of 32 patients (78%). In 11% of cases the lymphoscintigram detected an abnormality of lymph node function before macroscopic morphological change was seen in the lymphogram, indicating that in some instances lymphoscintigraphy is more sensitive than lymphography. The reason for this is unknown, although possible mechanisms are discussed and these are the subject of current further study. We believe this to be the first report of lymphoscintigraphy being more sensitive than lymphography for detecting lymph node disease.

Distribution of radiolabeled multilamellar liposomes injected intralymphatically and subcutaneously

The distribution of negatively charged multilamellar vesicles (MLV) composed of dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol administered subcutaneously (s.c.) and intralymphatically (i.l.) was studied in rats and dogs. In rats, the drainage of 99mTc-MLV from the s.c. space was slow, with 35% of the activity still remaining at the site of injection after 48 h and minimal systemic distribution (less than 5% at any time point). In the dog, 99mTc-MLV and 111In-MLV injected s.c. on the dorsal surface of a hindpaw were drained both by the lymphatic system and the systemic circulation; at 24 and 72 h, significant activity still remained at the site of injection. Lymphatic uptake was almost limited to the popliteal nodes and was enhanced by dividing the dose in several s.c. injections. Liver and kidney uptake was also observed, most likely as a result of direct liposome absorption into the systemic circulation. The i.l. administration (via left hindpaw) of 99mTc-MLV to a dog resulted in an immediate uptake in the abdominal and mediastinal lymph nodes, and in the liver and spleen. Compared with small unilamellar vesicles, MLV injected s.c. can provide a slower and more prolonged delivery of drugs to the regional lymph nodes.