Intraoperative radioguidance with a portable gamma camera: a novel technique for laparoscopic sentinel node localisation in urological malignancies.

PURPOSE: Our aim was to assess the feasibility of intraoperative radioguidance with a portable gamma camera during laparoscopic sentinel node (SN) procedures in urological malignancies. METHODS: We evaluated the use of the intraoperative portable gamma camera in 20 patients: 16 patients with prostate carcinoma (PCC), 2 patients with renal cell carcinoma (RC) and 2 patients with testicular cancer (TC). Intra/peritumoural injection of (99m)Tc-nanocolloid ((99m)Tc) was followed by planar lymphoscintigraphy, SPECT/CT and marking of SN levels. Before laparoscopy a (125)I seed was fixed on the laparoscopic gamma probe as a pointer of SN seeking. The portable gamma camera was set to display the (99m)Tc signal for SN localisation and the (125)I signal for SN seeking. Matching of these signals on screen indicated exact SN localisation, and consequently this SN was removed. RESULTS: The mean injected dose was 218 MBq in PCC, 228 MBq in RC and 88 MBq in TC. Pelvic SN were visualised in all PCC patients, with uncommonly located SN in seven patients. SN metastases were found in seven patients (one in a uncommonly located SN). Both RC patients and TC patients had para-aortic SN, which were all tumour free. A total of 59 SN were removed. The portable gamma camera enabled real-time SN display/identification in 18 patients (90%). CONCLUSION: The use of a portable gamma camera in combination with a laparoscopic gamma probe incorporates intraoperative real-time imaging with improved SN identification in urological malignancies. This procedure might also be useful for SN identification of other deep draining malignancies.

Enhancement of 131I-MIBG uptake in carcinoid tumours by administration of unlabelled MIBG.

Iodine-131 metaiodobenzylguanidine (131I-MIBG) has been used with success for the palliation of symptomatic, metastatic carcinoid tumours. However, only 70% of cases are MIBG-avid and tumour uptake is not always sufficient for therapy. At The Netherlands Cancer Institute 34 carcinoid patients with no or insufficient uptake were treated with escalating doses of unlabelled ('cold') MIBG. No objective remissions were recorded, but a palliative effect (i.e. subjective disappearance of symptoms and/or reduction of medication by more than 50%) was observed in 60% of cases (mean duration 4.5 months). In 24 of the patients undergoing therapy with 'cold' MIBG, total body scintigraphy using 37 MBq 131I-MIBG was performed before and after infusion of 'cold' MIBG. The biodistribution of 131I-MIBG and its tumour to non-tumour ratios were compared. After 'cold' MIBG the 131I-MIBG uptake in the salivary glands was suppressed in all patients, myocardial uptake in 21, and uptake in normal liver tissue in 14. Pulmonary uptake was increased in 13 patients. More importantly, the tumour to non-tumour (T/NT) ratios improved in 17 of the 24 cases (by 7.8-111.4% at 24 h). Of the initial six patients demonstrating a significant increase in the T/NT ratio, five have subsequently received combined treatment of 7.4 GBq 131I-MIBG following the administration of 'cold' MIBG (both by 4 h intravenous infusion), resulting in a good palliative response in four of them. These patients had previously been excluded from therapy with 131I-MIBG only. It is concluded that the administration of unlabelled MIBG may not only provide palliation to patients with carcinoid tumours, but may also alter the biodistribution of MIBG, enabling 131I-MIBG therapy to be used in cases not qualifying for this treatment due to insufficient tumour uptake.