First In-Human Clinical Study of a Mobile Gamma Camera for Pre-Operative Imaging of Melanoma
Abstract
Purpose
Sentinel lymph node biopsy (SLNB) in melanoma utilizes preoperative lymphoscintigraphy +/- SPECT/CT for accurate identification of draining lymph nodes for surgical planning. However, SPECT/CT imaging is time consuming and is often located in different departments and/or buildings than the operating suites. The purpose of this study is to determine feasibility of the Lymphocam, a new mobile gamma camera, to provide accurate and fast imaging of the lymphatic drainage just outside or even within the operating room.
Methods
The Lymphocam was first calibrated for imaging 99mTc using NEMA 2024 measurement protocols. Next, it was used for pre-operative imaging for SLNB planning. A prospective 20 patient feasibility clinical trial was designed and performed to compare its ability to image lymphatic drainage against that of standard SPECT/CT imaging for melanoma SLNB procedures.
Results
From the NEMA characterization and calibration the Lymphocam was found to have a maximum field of view of 10 cm x 10 cm, a 5 mm spatial resolution, a sensitivity of 2.4 kilo counts per second per milliCurie (kCPS/mCi), and a maximum measurable count rate of 24 kCPS. For in-patient imaging, the LymphoCam showed reliable identification of radiotracer drainage within lymphatic vessels and sentinel lymph nodes. Whereas lymphoscintigraphy and SPECT/CT required 60 - 100 minutes to complete, the Lymphocam imaged drainage and location of lymph nodes within 10 (±3) minutes from the time of radiotracer injection.
Conclusion
The Lymphocam technology provides an alternative approach to identifying sentinel lymph node drainage for pre-operative melanoma SLNB planning. This current experience shows the possibility of an intra-operative approach to radiotracer imaging for SLNB planning. Further patient imaging and refinements to the use of the camera, as well as its utility in clinical practice are currently under investigation.