Efficacy of Gamma Camera Used Intraoperatively for ID of Sentinel Lymph Nodes w/ Lymphoscintigraphy

Efficacy of a Novel, High-Sensitivity, Portable, Hand-Held Gamma Camera Used Intraoperatively for Identification of Sentinel Lymph Nodes With Lymphoscintigraphy

This study evaluates the ability of a prototype intraoperative handheld gamma camera (pIHGC) to image (detect) sentinel lymph nodes (SLNs) in melanoma and breast cancer during surgical excision, as compared to standard of care intraoperative gamma probes (GP). The unit of study in this trial was SNLs rather individual participants. Each device was assessed for relative node detection sensitivity (S) of those SLNs.

Lymphoscintigraphy is an accepted and commonly-performed procedure used for staging of certain cancers, especially melanoma and breast cancer. It involves injecting a small amount of radioactivity under the skin in order to identify lymph nodes which should be biopsied (ie, the "sentinel lymph node, SLN") to determine if cancer has spread. The study objective was to evaluate the potential benefit of a new, camera-based technology (prototype device) which allows actual images to be obtained intra-operatively in the identification of sentinel nodes. Each device was assessed for relative node detection sensitivity (S), defined as the proportion of sentinel lymph nodes (SLNs) that were identified with each instrument, with the proportion determined as the number of true positives (TP) divided by the total evaluated (N).

The unit of study in this trial was sentinel lymph nodes (SLNs) rather individual participants. with the comparison conducted by evaluation of each SLN with the prototype intraoperative handheld gamma camera (pIHGC) and standard of care intraoperative gamma probes (GP).

The prototype intraoperative handheld gamma camera (pIHGC) consists of a parallel-hole lead collimator coupled to a pixilated sodium iodide-thallium [NaI(Tl)] scintillation crystal array, itself coupled to a flat panel, multi-anode Hamamatsu H8500 position-sensitive photomultiplier tube. The collimator is 5x5 cm2 large in area and 1.5 cm thick, with 1.3 mm hexagonal holes and 0.2 mm septa. The 1.7 mm pitch crystal array is composed of 29x29 individual crystals, each 1.5x1.5x6 mm3 in size.

Lymphoscintigraphy involves injection of 0.4 to 1.0 mCi of radioactive Tc99M sulfur colloid around at the tumor site.

Relative node detection sensitivity (S) was defined as the proportion of sentinel lymph nodes (SLNs) that were identified with each instrument, with the proportion determined as the number of true positives (TP) divided by the total evaluated (N). The outcome result is expressed as the percentage for each device with 95% confidence intervals.

INCLUSION CRITERIA Malignancy for which sentinel node biopsy with lymphoscintigraphy are indicated as part of the standard of care for tumor staging Age 18 or greater. Healthy enough for surgery Able to understand and willing to sign a written informed consent document. EXCLUSION CRITERIA No exclusion requirements due to co-morbid disease or intercurrent illness. Documented allergy to colloid. Lymphoscintigraphy presents excessive high risk, eg, a consideration if pregnant or lactating

Olcott P, Pratx G, Johnson D, Mittra E, Niederkohr R, Levin CS. Clinical evaluation of a novel intraoperative handheld gamma camera for sentinel lymph node biopsy. Phys Med. 2014 May;30(3):340-5. doi: 10.1016/j.ejmp.2013.10.005. Epub 2013 Nov 14.