Precise Localization of Sentinel Lymph Nodes and Estimation of Their Depth Using a Prototype Intraoperative Mini  -Camera in Patients with Breast Cancer

Abstract

The aim of this study was to evaluate the ability of a prototype intraoperative mini g-camera, the CarolIReS, with a 50 · 50 mm field of view, to precisely localize sentinel lymph nodes (SLNs) and to determine their depth in a series of patients with infiltrative breast cancer requiring SLN excision. Methods: With the use of phantoms, the broadness of the signal of an acquired projection was shown to linearly depend on its distance from the collimator. A preclinical ex vivo study of 25 excised SLNs demonstrated that SLN size did not influence depth estimation. The minimum activity threshold for successful use of the proposed method was determined. After a preoperative radioisotope injection and lymphoscintigraphy, the SLN was localized in a series of 11 patients using both the mini g-camera and a g-probe. During surgery, a ruler was used to measure the depth of all SLNs before their excision. Results: Using the measured linear dependence of image broadness, we found that the expected SLN anatomic depth was compatible with its measured depth during surgery. Conclusion: This study showed that the mini g-camera efficiently estimated the location of SLNs in 3 dimensions.Key Words: breast cancer; lymphoscintigraphy; intraoperative gamma-camera; sentinel lymph node; CarolIReS Mostt ypes of lymphophile cancers require assessment of regional lymph nodes for staging the tumor, determining prognosis, and devising therapeutic strategies. Complete lymph node dissections are frequently associated with significant morbidity. Combining diagnostic advantages with decreased morbidity (1,2), the sentinel lymph node (SLN) procedure represents one of the most recent advances in surgical oncology. It consists of the identification and removal of SLNs, which are lymph nodes that receive lymphatic drainage directly from the primary tumor. The SLN procedure is now a widely accepted method of lymph node staging for selected cases of invasive breast cancer (3,4) and cutaneous melanoma (5). The concept is also being evaluated in numerous other types of cancer, including pelvic gynecologic (vulval, cervical, and endometrial) (6-9), prostate (10), colon (11), gastric (12) and thyroid (13) cancer. In all cases, successful adaptation of the SLN procedure implies that the operator has a high identification rate and a low false-negative rate. For SLN identification, in addition to the peroperative injection of a blue dye, a 99m Tc-radiomarked colloidal solution is generally injected the day before or the day of the surgery and 2 planar scintigraphic images are taken in a nuclear medicine department. In a recent metaanalysis (14) including 69 trials and 8,059 patients with low-risk breast cancer, the proportion of patients with successfully mapped SLNs ranged from 41% to 100%, with more than 50% of the studies reporting a rate under 90%. The false-negative rate ranged from 0% to 29%, averaging 7.3% overall. Significant inverse correlations were observed between the false-negative rate and the proportion of patients with successfully mapped SLN...

A Portable γ-Camera for Intraoperative Detection of Sentinel Nodes in the Head and Neck Region

“…Kopelman et al achieved exact intraoperative localization of sentinel nodes with a portable g-camera in 9 pigs (7), whereas Mathelin et al were able to localize sentinel nodes with a portable g-camera in 11 breast cancer patients (12). Mathelin et al could also successfully estimate the depth of the nodes preoperatively with this camera (12). Scopinaro et al demonstrated that more nodes were removed when the hand-held g-camera was used intraoperatively in addition to the g-probe in breast cancer patients, and operation time was significantly shorter (13).…”

“…Few authors have reported on their first experience with intraoperative localization of lymph nodes using these cameras (7,8,(10)(11)(12)(13)(14). Motomura et al showed that lymphoscintigraphy of sentinel nodes in breast cancer can reliably be reproduced in the operating room using a solid-state g-camera (11).…”

Portable gamma cameras: the real value of an additional view in the operating theatre

“…During the last decade some PGCs have become available for clinical practice, and can be used in open surgery or with laparoscopy, providing information that can be combined with that coming from conventional or laparoscopic gamma probes. Some of these PGCs are not designed specifically for radioguided surgery (Dilon 6800 gamma camera, a model optimized to perform breast-specific gamma imaging, or Cardiotom 3D mobile gamma camera, optimized to perform myocardial perfusion scintigraphy), but other models are focused on sentinel node (SN) procedures [2][3][4].In this issue of the journal, Vidal-Sicart et al[5] report on the use of the Sentinella S102 (Oncovision) camera, which is a compact scintillation camera with a 50×50× 4 mm 3 CsI crystal optically coupled through a light guide to a flat panel type position-sensitive photomultiplier tube. This model is connected to a computer via USB, which processes the output signals and provides energy to the detector system.…”

“…During the last decade some PGCs have become available for clinical practice, and can be used in open surgery or with laparoscopy, providing information that can be combined with that coming from conventional or laparoscopic gamma probes. Some of these PGCs are not designed specifically for radioguided surgery (Dilon 6800 gamma camera, a model optimized to perform breast-specific gamma imaging, or Cardiotom 3D mobile gamma camera, optimized to perform myocardial perfusion scintigraphy), but other models are focused on sentinel node (SN) procedures [2][3][4].…”

Added Value of Intraoperative Real-Time Imaging in Searches for Difficult-to-Locate Sentinel Nodes

“…Using the anatomic landmarks of SPECT/CT images, the portable device can be oriented to surgical targets in the operating room. Moreover, the possibility of obtaining a real-time image can be helpful to the surgeon, resulting in more reliable and, probably, briefer surgery, especially when the sentinel node is in a difficult anatomic area or near the radiotracer injection point (18)(19)(20).…”