Detection of Sentinel Node in Breast Cancer: Pilot Study with the Imaging Probe

Abstract

The commonly used gamma probes are easy to use but also give rough information when employed in radioisotope-guided surgery. When images are required for exact localization, a gamma camera as well as a probe have to be used. Position-sensitive photomultipliers have contemporaneously allowed high-resolution scintigraphy and miniaturization of gamma cameras. We have assembled a miniature gamma camera with a 1-square-inch field of view and an intrinsic resolution of about 1 mm. When the minicamera is collimated with a large-holed, highly sensitive collimator, it acquires a spatial resolution of 3 mm. This prototype has been tested in the detection of difficult-to-image breast cancer sentinel nodes. Five nodes that had not been found with the usual technique of an Anger camera plus conventional probe were checked with the miniature camera that we named imaging probe: it actually is small enough to be used as a probe and large enough to give an image. One of the five nodes was found and imaged. It was small, disease-free, close to the tumor and probably hidden by the Compton halo around the peritumoral injection site. Our pilot study shows that the imaging probe, although still a prototype, has certain advantages over conventional methods when lymph node localization is required during surgery.

High-Resolution, Hand-Held Camera for Sentinel-Node Detection

“…Some researchers, we among them, have shown the importance of HR intraoperative imaging. 13,[18][19][20][33][34][35][40][41][42][46][47][48]50 Present data show higher sensitivity of HR intraoperative imaging, when compared with current methods. The false finding of a second SN at ALS was only an occasional observation, rarely reported by others, 51 observed: We can suppose that HR shows also higher specificity, at least in comparison with Anger camera LS.…”

“…[27][28][29][34][35][36][37][38][39][40][41] Physical and technical characteristics have already been described elsewhere in detail. [30][31][32][33]43 Briefly, IP-824 is a portable HR camera especially designed for radioguided surgery.…”

“…These gamma cameras became portable by optimizing electronics: our first 1-in 2 field-of-view (FOV) portable camera, that we called the imaging probe (IP), has been used to detect mammary SNs since 1999. [33][34][35][36] IP benefited from further improvements on collimators, external shielding, once more electronics, 37,38 becoming suitable for several purposes, including small animal imaging. 38,39 All the prototypes of IP showed results on radioguided surgery and SN biopsy [40][41][42][43][44][45][46][47][48] owing to the evolution of this detector that was based on medical requirements.…”

Usefulness of a solid-state gamma camera for sentinel node identification in patients with breast cancer

“…Scopinaro et al [17] developed a one-square-inch field-of-view mini-gamma camera named an imaging probe. They tested it in the detection of five sentinel nodes that were difficult to identify using the Anger camera and gamma probe, and identified one of them using the imaging probe.…”

New imaging probe with crystals integrated in the collimator's square holes

“…On the contrary, a dedicated gamma ray imager [4][5][6][7], which can be easily transferred to operation theatre, can rapidly image the sentinel node and drive the biopsy. Whereas, sentinel node biopsy is just an example.…”