Role of a portable gamma-camera with optical view for margins assessment of pulmonary nodules resected by radioguided surgery.

PURPOSE: Radioguided occult lesion localization (ROLL) of pulmonary nodules is an alternative to hook-wire. Both required of a histological margin assessment. The activity emerging from the radiotracer allows to obtain an intraoperative scintigraphic image of the surgical specimen by a portable gamma-camera (PGC) fitted with an optical view, which provides information about the localization of the nodule in relation to the margins. The aim of this study was to evaluate the intraoperative use of a PGC for margin assessment of pulmonary nodules. METHODS: ROLL technique was used in 38 nodules (36 pulmonary, 1 chest wall, and 1 pleural nodules). A PGC intraoperative image of the surgical specimen was obtained in 32. Scintigraphic results were compared to the histological assessment. Other factors, such as nodule size, distance from the pleural surface, or distance covered by the needle, were considered as possible factors for non-centered lesions. RESULTS: PGC images showed that the lesion was in contact with the margins in 8/32 cases and centered in 24. In all cases in which the lesion was considered as centered by the PGC, the margins were free of involvement (NPV 100%), although the PPV is low. CONCLUSIONS: The use of a PGC for margin assessment after pulmonary nodule resection is feasible and provides a high NPV in our series. In addition, the short intraoperative time required for its use makes the PGC a useful tool for providing supplementary information to histopathologic results. Further studies from different surgical teams are required for an external validation.

The scintigraphic index spleen/liver at 30 minutes predicts the success of splenectomy in persistent and chronic primary immune thrombocytopenia.

UNLABELLED: Splenectomy is considered the second-line of treatment in patients with chronic primary immune thrombocytopenia (ITP) in whom glucocorticoids have failed. Some patients do not respond to splenectomy or they have postoperative complications. Based on our previous experience using kinetic and scintigraphic parameters, we did a retrospective study with the aim of comparing all these parameters as a means of predicting the success of splenectomy in persistent and chronic primary ITP. Forty-one consecutive patients with chronic primary ITP refractory to prednisone, who had been splenectomized, were included in the study. The response to splenectomy was assessed by evaluating bleeding and platelet counts before and at different times after surgery. A complete platelet kinetic study was performed before the splenectomy using autologous (111) In-labeled platelets. The scintigraphic parameters measured included different indices between spleen/heart, liver/hearth, and spleen/liver. Thirty-six patients gave a complete response after splenectomy and five patients did not respond. A statistically significant difference between both groups was found with initial platelet recovery and with some scintigraphic indices which also showed a variable prediction value for the success of splenectomy. Among these indices, the spleen/liver at 30 minutes demonstrated a predictive value with a 100% of sensitivity and a 100% of specificity. CONCLUSION: some platelet kinetic parameters and scintigraphic indices, in particular the spleen/liver at 30 minutes, were useful to predict the outcome of splenectomy in persistent and chronic primary ITP and, therefore, they should be taken into account when deciding whether or not to perform a splenectomy.

Performance Characteristics of the Whole-Body Discovery IQ PET/CT System.

The aim of this study was to assess the physical performance of a new PET/CT system, the Discovery IQ with 5-ring detector blocks. Methods: Performance was measured using the National Electrical Manufacturers Association NU2-2012 methodology. Image quality was extended by accounting for different acquisition parameters (lesion-to-background ratios [8:1, 4:1, and 2:1] and acquisition times) and reconstruction algorithms (VUE-point HD [VPHD], VPHD with point-spread-function modeling [VPHD-S], and Q.Clear). Tomographic reconstruction was also assessed using a Jaszczak phantom. Additionally, 30 patient lesions were analyzed to account for differences in lesion volume and SUV quantification between reconstruction algorithms. Results: Spatial resolution ranged from 4.2 mm at 1 cm to 8.5 mm at 20 cm. Sensitivity measured at the center and at 10 cm was 22.8 and 20.4 kps/kBq, respectively. The noise-equivalent counting rate peak was 124 kcps at 9.1 kBq/cm3 The scatter fraction was 36.2%. The accuracy of correction for count losses and randoms was 3.9%. In the image quality test, contrast recovery for VPHD, VPHD-S, and Q.Clear ranged from 18%, 18%, and 13%, respectively (hot contrast; 10-mm sphere diameter; ratio, 2:1), to 68%, 67%, and 81%, respectively (cold contrast; 37-mm sphere diameter; ratio, 8:1). Background variability ranged from 3.4%, 3.0%, and 2.1%, respectively (ratio, 2:1), to 5.5%, 4.8%, and 3.7%, respectively (ratio, 8:1). On Q.Clear reconstruction, the decrease in the penalty term (ß) increased the contrast recovery coefficients and background variability. With the Jaszczak phantom, image quality increased overall when a reconstruction algorithm modeling the point-spread function was used, and use of Q.Clear increased the signal-to-noise ratio. Lesions analyzed using VPHD-S and Q.Clear had an SUVmean of 6.5 ± 3 and 7 ± 3, respectively (P < 0.01), and an SUVmax of 11 ± 4.8 and 12 ± 4, respectively (P < 0.01). No significant difference in mean lesion volume was found between algorithms. Conclusion: Among the various Discovery bismuth germanium oxide-based PET/CT scanners, the IQ with 5-ring detector blocks has the highest overall performance, with improved sensitivity and counting rate performance. Q.Clear reconstruction improves the PET image quality, with higher recovery coefficients and lower background variability.