Purpose To explore the potential parameters from 18F-FDG PET/CT that might be associated with the epidermal growth factor receptor (EGFR) gene mutation status in lung adenocarcinoma (ADC) patients. Methods Data of the test cohort of 191 patients and the validation cohort of 55 patients with newly diagnosed ADC were retrospectively reviewed. All patients underwent 18F-FDG PET/CT scans and EGFR mutation tests prior to treatment. The metabolic parameters obtained from 18F-FDG PET/CT combining with clinical characteristics were analyzed by using univariate and multivariate logistic regression analyses. Then two cohorts were enrolled to validate the predictive model by area under the receiver-operating characteristic curve (AUC), respectively. Results EGFR mutation-positive was seen of 33.0% (63/191) and 32.7% (18/55) in two cohorts, respectively. In univariate analysis, female, nonsmokers, metabolic parameters of primary tumor [mean standardized uptake value, metabolic tumor volume (pMTV), and total lesion glycolysis], non-necrosis of primary tumor, and serum tumor markers [carbohydrate antigen 19-9, squamous cell carcinoma antigen, and precursor of gastrin releasing peptide (proGRP)] were significantly relevant with EGFR mutation. In multivariate analysis with adjustment of age and TNM stage, pMTV (<8.13 cm3), proGRP (≥38.44 pg/ml) and women were independent significant predictors for EGFR mutation. The AUC for the predictive value of these factors was 0.739 [95% confidence interval (CI) 0.665–0.813] in the cohort of 191 patients and 0.716 (95% CI 0.567–0.865) in the cohort of 55 patients, respectively. Conclusion Low pMTV (<8.13 cm3) was an independent predictor and could be integrated with women and high proGRP (≥38.44 pg/ml) to enhance the discriminability on the EGFR mutation status in ADC patients.

A 26-year-old woman was incidentally discovered to have bilateral renal tumors on ultrasound, and percutaneous biopsy of the right kidney lesion proved eosinophilic solid and cystic renal cell carcinoma. 18 F-FDG PET/CT demonstrated hyperdense or isodense lesions on CT without FDG uptake, whereas 99m Tc-MIBI SPECT/CT fusion images showed tumors with increased 99m Tc-MIBI uptake. This case indicates that the 99m Tc-MIBI SPECT/CT is a potential method for the differentiation of renal tumor with eosinophilic features from other renal tumor histology.

A 41-year-old man with 1-year history of hypertension was discovered to have a right adrenal mass on abdominal ultrasound. Contrast CT was performed to discriminate malignant from benign tumor, which revealed tumors of right adrenal gland and prostate. 18 F-FDG PET/CT scan was performed for lesion characterization, and ruling out any distant metastasis. PET/CT scan showed high uptake in the right adrenal and prostatic lesions, which were surgically approved as adrenocortical carcinoma and primary prostatic synovial sarcoma.