Sentinel node detection with imaging probe.

A once-square-inch-field-of-view mini gamma camera, whose first prototype was built by us in 1998 and given the name imaging probe (IP), was initially employed in sentinel lymph node (SLN) detection. This is probably the best way of learning how to use it. In the present work IP was used for SLN localization by a medical team that, after having been trained by the group of nuclear physicians of "La Sapienza" University who designed and first used the detector, used IP at their own hospital to 1) acquire experience for future use during surgery (a cooperative project on IP-radioguided orthopedic surgery is ongoing) and 2) start multicenter trials with IP. The SLN was identified and localized with IP and a non-imaging probe, Neoprobe 2000, in six patients with breast cancer who underwent lymphoscintigraphy for SLN biopsy. The operators who used Neoprobe and IP were blinded to each other's findings and to the results obtained with the large-field-of-view Anger camera that was used for lymphoscintigraphy. The Anger camera, IP and Neoprobe detected seven SLNs in six patients. The mean detection time was 2 mins 6 s (standard deviation (SD) 26 s) with IP, and 2 mins 18 s (SD 47 s) with Neoprobe 2000. The SLN that was most difficult to find was detected in 2 mins 56 s with IP and 3 mins 45 s with Neoprobe. The operators' subjective impression of having detected the SLN was "absolutely sure" for 7/7 nodes with IP and "absolutely sure" for 5/7 nodes with Neoprobe.