[(111)In]Pentetreotide SPECT scintigraphy in neuroendocrine tumors: variability of reconstructing parameters related to patient characteristics and each body part.

AIM: Multi-headvariable-geometry gammacamera, allow us to carry out multi-dimensional scintigraphic single photon emission computed tomography (SPECT) studies, with the possibility of creating coronal, axial, sagittal, three-dimensional images like the last generation of multi-slice RMI or multislice CT scan. The aim of this paper is to weigh up the reconstruction parameters to apply in [(0111)In]Pentetreotide scintigraphy for evaluating neuroendocrine tumors and try to standardize them. METHODS: We have studied a group of 93 patients suffering from neuroendocrine tumors. Examination was carried out after administration of [111In] Pentetreotide with whole body and static acquisitions after 4 and 24 h, followed by SPECT acquisitions of head, thorax and abdomen after 24 h. RESULTS: The results obtained show that the Filtered Back Projection using Butterworth filter can produce images of greater resolution than the iterative reconstruction method. Moreover, the reconstruction parameters are easily standardizable for head and thorax while for the abdomen the choice of these parameters is more difficult. CONCLUSIONS: Our data show that filtered back projection with Butterworth filter is the best procedure to carry out a SPECT examination with [111In] Pentetreotide.

Accurate planning of minimally invasive surgery of parathyroid adenomas by means of [(99m)Tc]MIBI SPECT.

AIM: The aim of the study was to evaluate the clinical role or [(99m)Tc]MIBI SPECT in selecting primary hyperparathyroid (PHPT) patients for minimally invasive radioguided surgery (MIRS). METHODS: One hundred and forty-one consecutive PHPT patients were studied by a single-session [(99m)Tc]Percethnetate/[(99m)Tc]MIBI subtraction scintigraphy, followed by [(99m)Tc]MIBI SPECT in order to localize hyperfunctioning parathyroid adenoma (PA) and plan the surgical approach. RESULTS: A solitary PA was depicted at preoperative scintigraphy in 135 of 141 patients (95.7%), two or more PA in 5 patients, and was negative in 6 patients (4.3%). In 27 patients, the PA was located deep in the paraesophageal/paratracheal space. One hundred and twenty-four patients (in 18 of them the PA was located deeply in the neck) underwent successful MIRS using the low 37 MBq (1 mCi) [(99m)Tc]MIBI dose protocol. Intraoperative quick parathyroid hormone (QPTH) assay demonstrated a fall >50% in respect to the baseline value in all patients, confirming successful parathyroidectomy. After a follow-up of 6 to 37 months (median 18 months), no case of persistent/recurrent PHPT was recorded. When comparing the parathyroid to background (P/B) ratio measured at planar and SPECT preoperative scintigraphy with that measured intraoperatively with the gamma probe, a significant linear correlation was found between the SPECT and intraoperative gamma probe measurements (r = 0.91; P <0.01) while no correlation was found with planar scintigraphic data. CONCLUSIONS: Our data suggest that the P/B ratio calculated by means of [(99m)Tc]MIBI SPECT is more accurate in predicting the intraoperative measurements with the intraoperative gamma probe. Thus, a preoperative [(99m)Tc]MIBI SPECT acquisition should be recommended for a better selection of PHPT patients to offer MIRS.