Absolute quantification of myocardial uptake of 99mTc-DPD in patients with cardiac amyloidosis due to transthyretin deposits (ATTR).

PURPOSE: To determine the diagnostic contribution of the absolute quantification of the myocardial deposit of 99mTc-DPD in patients with cardiac amyloidosis due to transthyretin deposits (ATTR). MATERIALS AND METHODS: SPECT/CT was performed in 41 patients with positive scintigraphic results for ATTR cardiac amyloidosis. The patients were divided into two groups (Perugini grades 2 and 3) and the SUVmax at the level of the bone and both ventricles and the percentage of dose calculated in these areas were calculated. The Student's t-test was used to compare results and the area under the curve (AUC) was calculated to assess differential efficacy and establish discriminatory cut-off points between both groups of patients. RESULTS: Statistically significant differences were observed in all the study variables, with the exception of bone SUVmax. The differences with the greatest statistical power were observed in the variables SUVmaxRV and the percentage of dose in both ventricles (p < 0.001). The cut-off point obtained for the variable SUVmaxLV was 8.620 (sensitivity 87.9% and specificity 100%; AUC 0.966), while that of the variable SUVmaxRV was 6.195 (sensitivity 81.8% and specificity 100%; AUC 0.955). CONCLUSIONS: The absolute quantification of myocardial uptake of 99mTc-DPD in the SPECT/CT images of patients with suspected cardiac amyloidosis due to transthyretin deposits represents a new diagnostic tool that allows adequate classification of patients according to the Perugini visual grading scale.

Large cell neuroendocrine carcinoma of the lung with atypical evolution and a remarkable response to lutetium Lu 177 dotatate.

Large cell neuroendocrine carcinoma of the lung (LCNEC) is a high-grade, poorly differentiated tumor that typically does not express somatostatin receptors. Thus, it does not benefit from treatment with somatostatin analogs and peptide receptor radionuclide therapy (PRRT). The current study objective was to demonstrate that treatment with PRRT may be a valid option in neuroendocrine carcinomas with high expression of somatostatin receptors. This is a case report of a 58-year-old man who was diagnosed with LCNEC and received chemotherapy treatment with little benefit. Extensive hepatic and bone metastasis was detected on 111In-pentetreotide scintigraphy following high uptake of the radionuclide by the tumors. The patient benefitted from neuroendocrine treatment initially and from lutetium Lu 177 dotatate subsequently. A significant clinical and radiological response was observed, along with an improvement in quality of life. The use of PRRT is a valid alternative to chemotherapy in patients with LCNEC involving the expression of somatostin receptors.