Sentinel lymph node: established and new areas of use

Repeat injection following sentinel node nonvisualization on lymphoscintigraphy images can decrease axillary dissection rate in breast cancer patients

AIM

Sentinel node biopsy is considered the standard of care in early-stage breast cancer patients. In the current study, we evaluated the effect of radiotracer reinjection in the case of sentinel node nonvisualization on preoperative lymphoscintigraphy.

MATERIALS AND METHODS

Between March 2017 and March 2020, 1850 early-stage breast cancer patients were referred for sentinel node mapping. All patients received a single injected activity of Tc-99m Phytate intradermally in the periareolar area of the index lesion using an insulin syringe. Lymphoscintigraphy images of the patients were done 1-2 h postinjection. Between March 2017 and September 2017, sentinel node nonvisualization was reported to the surgeon, and for the rest of the study period, the patients received another injected activity of the radiotracer, and immediately, other lymphoscintigraphy images were taken (with the same parameters).

RESULTS

A total of 255 patients entered our study. Fifty-five patients were in group I without any reinjection. The remainder of the patients were in group II. In 155 out of 200 patients of group II, a sentinel node could be visualized following reinjection of the radiotracer. The detection rate was 15 out of 45 and 15 out of 55 in group I and patients without sentinel node visualization even after reinjection, respectively. Axilla was involved in 5 out of 40 (12.5%) patients in group I with intraoperative sentinel node mapping failure. On the other hand, axilla was involved in 27 out of 30 (90%) group II patients with sentinel node nonvisualization.

CONCLUSION

Reinjection of the tracer in cases of no sentinel node visualization in lymphoscintigraphy for breast cancer increases the detection rate of sentinel nodes, and therefore a high number of unnecessary axillary lymph node dissections can be avoided.

Investigating the role of SPECT/CT in dynamic sentinel lymph node biopsy for penile cancers

Purpose

Currently, most centres use 2-D planar lymphoscintigraphy when performing dynamic sentinel lymph node biopsy in penile cancer patients with clinically impalpable inguinal nodes. This study aimed to investigate the role of SPECT/CT following 2-D planar lymphoscintigraphy (dynamic and static) in the detection and localization of sentinel lymph nodes in the groin.

Methods

A qualitative (visual) review was performed on planar followed by SPECT/CT lymphoscintigraphy in 115 consecutive patients (age 28–86 years) who underwent injection of ^99mTc-nanocolloid followed by immediate acquisition of dynamic (20 min) and early static scans (5 min) initially and further delayed static (5 min) images at 120 min followed by SPECT/CT imaging. The lymph nodes detected in each groin on planar lymphoscintigraphy and SPECT/CT were compared.

Results

A total of 440 and 467 nodes were identified on planar scintigraphy and SPECT/CT, respectively. Overall, SPECT/CT confirmed the findings of planar imaging in 28/115 cases (24%). In the remaining 87 cases (76%), gross discrepancies were observed between planar and SPECT/CT images. SPECT/CT identified 17 instances of skin contamination (16 patients, 13%) and 36 instances of in-transit lymphatic tract activity (24 patients, 20%) that had been interpreted as tracer-avid lymph nodes on planar imaging. In addition, SPECT/CT identified 53 tracer-avid nodes in 48 patients (42%) that were not visualized on planar imaging and led to reclassification of the drainage basins (pelvic/inguinal) of 27 tracer-avid nodes.

Conclusions

The addition of SPECT/CT improved the rate of detection of true tracer-avid lymph nodes and delineated their precise (3-D) anatomic localization in drainage basins.