PSMA PET/CT quick procedure guide.

The application of PET/CT with radiopharmaceuticals targeting PSMA is significantly transforming the diagnostic and therapeutic strategies of patients with prostate cancer. In Spain, the availability and access to positron-emitting radiopharmaceuticals targeting Prostate-Specific Membrane Antigen (PSMA) have significantly changed in recent months. These changes are affecting their use in diagnostic procedures. As a result, its use within diagnostic protocols for patients with prostate cancer is undergoing significant modifications. In this collective and cooperative document, the authors have selected the most robust evidence accumulated to date to generate a clinical guide to achieve appropriate use of this technology. A format that presents the most frequent clinical situations and the patient profiles in which PSMA PET/CT plays a significant role or will do so in the immediate future has been chosen. It should be taken into account that regulatory restrictions mediate the current indications for its use in Spain, as well as its current cost and the production capacity of radiopharmaceuticals. The guideline presents a review of the established methodology for optimized imaging with each of the radiopharmaceutical variants targeting PSMA and recommendations for structured and accurate reporting of metabolic findings in combination with CT.

Utility of low dose (18)F-FDG PET-CT in patients with suspected colorectal carcinoma recurrence in conventional diagnostic methods.

OBJECTIVE: To evaluate the efficacy of (18)F-FDG PET-CT in the diagnosis of recurrence of colorectal cancer (CRC) in patients with elevated values of carcinoembryonic antigen (CEA) and/or signs of recurrence in the multidetector CT (MDCT), and to demonstrate that good results can be obtained applying the ALARA principles. MATERIAL AND METHODS: A retrospective study of 54 patients with suspected CRC, who underwent an (18)F-FDG PET-CT, administering a mean dose of 222 MBq (6 mCi) of (18)F-FDG, from 07/2007 to 01/2011 was carried out. Seven patients were excluded, thus studying 47 (27 males, 20 females, mean age 63 years). Recurrence was confirmed by histopathology study in 14 cases and by clinical evolution in 33. The patients were divided into 4 groups. A: patients with elevation of CEA and suspected recurrence in the MDCT. B: elevation of CEA, without suspicious lesions in the MDCT. C: normal levels of CEA and positive MDCT. D: normal levels of CEA and uncertain MDCT. RESULTS: We found sensitivity, specificity, PPV, NPV and overall accuracy of 91%, 69%, 89%, 75% and 85% respectively. For group A, we found 100% sensitivity, in group B, 75% sensitivity with 100% specificity%, for C, sensitivity was 89% with 71% specificity. Finally, in group D, sensitivity was 100% and specificity 60%, respectively. CONCLUSION: Applying a low dose, the (18)F-FDG PET-CT has high diagnostic performance in patients with suspicion of CRC, approaching in a higher grade the ALARA criteria.

[Lung hot spot as pitfall in PET-CT interpretation: focal lung uptake of 18F-fluorodeoxyglucose]. / Foco pulmonar facticio con (18)F-FDG: posible error en la interpretación de la PET-CT.

(18)F-FDG PET-CT has become an essential tool in oncology patient management. The normal distribution of the FDG and the possible artifacts (pitfalls), including those from CT-based attenuation correction, have already been described in several reviews. However, only a few cases of FDG focal lung uptake have been reported recently. We present two cases of oncology patients during a routine follow-up with this type of pitfall, without morphological correlation in the CT scan. We repeated the study in one of them, which made it possible to verify normalization of the hyperuptake, orienting us towards a possible pitfall.