Is the portable gamma camera "Crystal Cam" equal to the conventional gamma camera for the detection of SLNs of malignant melanoma

Objectives The lymphatic metastasis of malignant melanoma (MM) is clarified by a planar γ-camera for identification of the sentinel lymph nodes (SLNs). This study examines whether a portable hand gamma camera "CrystalCam" (Crystal Photonics, Berlin) is equal to the conventional γ-camera in terms of the detection of SLNs without loss of diagnostic quality. The advantages are evident in the mobile availability and measurement speedof the hand-held camera.

Methods 38 patients with MM received 40-100 MBq ^99mTc-Nanocoll as an intradermal peritumoral injection. With the γ-camera (128x128) a dynamic, followed by a static record were made. The accumulating lymph nodes (LN) representing the first stations in the lymph were marked with an invisible UV marker on the skin to ensure blinding before the CrystalCam measurement was carried out (16x16, LEHS collimator, 3s, 20-60 min pi). Only then the marks were made visible with the aid of UV light. SPECT/CT served as reference gold standard for the detection of SLNs. Additional marks with a radiopaque Sticker for the CT were provided in the neck and in the groin region (Beekley Spot®). The statistics was done with SPSS 19.0 and BIAS 10:12

Results In SPECT/CT a total of 116 LN with nuclide uptake were detected. 60 were detected by the γ-camera, 63 by the CrystalCam, concordant 111. This corresponds to a concordance rate of 95.7%. This results in a chance-corrected agreement rate, expressed as Cohen's kappa coefficient, of κ = 0.914 (95% confidence interval). Both methods were able to map the SLNs, but weaknesses for bothe cameras were identified in the detection of LNs that were in close proximity to the sites of injection

Conclusions The CrystalCam and conventional γ-camera correspond in a high degree in their results (κ = 0.914; p <0.001). The CrystalCam can be used without loss of quality with time saving and local flexibility