Incidental Uptake of 68Ga-DOTATATE Gastrointestinal Stromal Tumor of Duodenum.

ABSTRACT: A 56-year-old man underwent 68Ga-DOTATATE PET/CT with suspicion of a pancreatic neuroendocrine tumor. However, in this imaging, a mass with 68Ga-DOTATATE uptake was observed not in pancreas but in the duodenojejunal junction. Abdominal tomography confirmed that the heterogeneously enhanced mass was originated from duodenum. The patient was operated, and the histopathology result was evaluated as low-risk gastrointestinal stromal tumor. Although there was low or no specific binding to gastrointestinal stromal tumor cells for all 68Ga-labeled DOTA peptides, uptake of 68Ga-DOTATATE was observed incidentally in this case.

Evaluation of metabolic changes in FDG PET/CT imaging after mRNA-based COVID-19 vaccination.

BACKGROUND: It isimportant to evaluate the vaccine-related metabolic changes on FDG PET/CT to avoid confusing results. We here aimed to assess the frequency and intensity of regional and systemic metabolic PET/CT changes of patients who received the mRNAbased COVID-19 vaccine (BNT162b2-Pfizer/BioNTech) and to analyze possible factors affecting these changes. METHODS: Among the patients who underwent FDG PET/CT for any indication in our department between July 2021 and December 2021, 129 volunteer patients with a history of COVID-19 vaccination were included in this prospective observational study. Bilateral axillary lymph nodes, ipsilateral deltoid muscle, bone marrow, spleen, thyroid, and liver FDG uptakes were evaluated visually and semiquantitatively for each examination. RESULTS: The frequencies of positive axillary lymph nodes after vaccination were 40%, 44.4%, 32.6%, and 44.7% in all, 1st dose, 2nd dose, and heterologous vaccination regimens groups, respectively. Maximum standardized uptake values of spleen, liver, and bone marrow were statistically high in patients with positive axillary lymph nodes than with negative ones (p < 0.05). Positive deltoid muscle uptake and diffusely increased thyroid uptake findings were observed in 10 and 8 patients, respectively. The median time interval between vaccination and imaging was 9.5 days for patients with positive axillary lymph nodes and 17 days for patients with negative nodes. In our study group, only 8 patients had a positive documented history of COVID-19 infection. DISCUSSION: Regional and systemic metabolic changes were occasionally found on FDG PET/CT imaging in patients who received the mRNA-based COVID-19 vaccine. To avoid these timely decreasing changes, we recommend managing the ideal timing of imaging or vaccination and taking a careful history.

Urinary Reflux Into the Prostate Gland and Seminal Vesicles: A Potential Pitfall in 18F-FDG and 68Ga-PSMA PET/CT.

A 64-year-old man with lung cancer underwent F-FDG PET/CT for restaging, which demonstrated intense F-FDG uptake in the right lobe of prostate gland and seminal vesicles, indicating a potential prostate cancer. In Ga-PSMA PET/CT, intense uptake in the right lobe of prostate gland and seminal vesicles was also observed but decreased in postmictional delayed images. Magnetic resonance imaging showed high signal intensity of urine in the same areas of uptakes. F-FDG and Ga-PSMA PET/CT findings in the prostate gland and seminal vesicles were considered to be a result of urinary reflux possibly because of the patient's previous transurethral resection.

Pulmonary 18F-FDG microembolism detected on only delayed image in a PET/CT study.

Focal 18F-FDG pulmonary uptake on PET without corresponding abnormality on CT is an incidental and rare finding. This artifact is associated with iatrogenic FDG microembolus as a result of vascular endothelium damage during injection. We present a pulmonary FDG microembolus in a patient evaluated for suspicion of gallbladder cancer not in early (standard 1-hour imaging after FDG injection) but in delayed image. To our knowledge, this is the first case that describes the possibility of FDG microembolism on only delayed image in a PET/CT study.

Correlation of Cystatin-C and radionuclidic measurement method of glomerular filtration rate in patients with lung cancer receiving cisplatin treatment.

OBJECTIVE: Cisplatin is a chemotherapeutic agent which affects renal functions adversely. The best indicator of renal functions is glomerular filtration rate (GFR) measurement. Cystatin-C appears to be a good alternative to existing methods of measuring GFR. However, it is controversial whether Cystatin-C demonstrates GFR correctly for patients receiving chemotherapy. This study aimed to investigate the correlation between GFR values calculated by Cystatin-C based formulas, radionuclidic method (multiple blood sampling) and blood Cystatin-C values in patients with lung cancer, receiving cisplatin treatment in both pre-treatment and post-treatment periods. MATERIALS AND METHODS: Thirty-six patients with lung cancer who were going to receive cisplatin treatment were included in this study. However, the evaluation was performed with 20 patients since 16 of them could not complete the treatment. Blood Cystatin-C values, GFR values calculated via Cystatin-C based formulas, and radionuclidic method were investigated before and after the cisplatin treatment. RESULTS: After treatment significant decreases were detected in GFR values, obtained via radionuclidic measuring method. However, there was no significant difference in Cystatin-C values between pre-treatment and post-treatment periods. Also GFR values obtained by Cystatin-C based formulas were not significantly different in pre-treatment and post-treatment periods. There were meaningful correlations between radionuclidic method and Cystatin-C values and Cystatin-C based formulas before treatment. However, all correlations disappeared after the treatment. CONCLUSION: GFR values, calculated by Cystatin-C may not be reliable in following renal functions in patients receiving chemotherapy. When reliable monitoring of the renal functions is necessary radionuclidic method may be preferred in these patients.

Excision of ectopic mediastinal parathyroid adenoma via parasternal videomediastinoscopy.

Mediastinum is one of the place in which ectopic parathyroid adenomas can be located.Here, an ectopic mediastinal parathyroid adenoma, which was excised via parasternal videomediastinoscopy was presented. The patient with chronic renal insufficiency had increased calcium levels persistence after the surgery for cervical parathyroid adenoma.Radiologic and scintigraphic examinations revealed a focal intense nodule in anterior mediastinum. Parasternal videomediastinoscopy was performed via parasternal incision through the second intercostal space. Ex-vivo specimen radioactivity measurements and frozen examination confirmed parathyroid adenoma. Calcium levels were decreased dramatically after the operation. Parasternal videomediastinoscopy could be an alternative surgical way in anterior mediastinal small masses such as ectopic parathyroid adenoma. It is the first case in which parasternal videomediastinoscopy was used for excision of mediastinal parathyroid adenoma.

Reduced heart rate response to dipyridamole in patients undergoing myocardial perfusion SPECT.

OBJECTIVE: A mild decrease in blood pressure and increase in heart rate (HR) are considered normal hemodynamic responses to dipyridamole. In this study, we tried to investigate HR response to dipyridamole and its predictors in patients undergoing gated myocardial perfusion single photon emission computed tomography (SPECT). METHODS: 201 consecutive patients undergoing dipyridamole stress Tc99m-MIBI or Tl-201 gated myocardial perfusion SPECT were prospectively enrolled. Dipyridamole was infused over 4 min and radiopharmaceutical was injected 3 min after the end of infusion. A reduced heart rate response to dipyridamole considered if the HR ratio (peak HR/rest HR) was 1.20 or less. Stress (sLVEF), rest (rLVEF) left ventricular ejection fractions, stress and rest motion (SMS, RMS) and thickening scores (STS, RTS) were derived automatically by QGS. Summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) for myocardial perfusion were calculated. Patients were grouped according to HR response and groups were compared. A logistic regression analysis was used to determine independent predictors of reduced HR response. RESULTS: Reduced HR response was found in 78 % of patients. Patients with abnormal HR response were more frequently had a history of diabetes mellitus, chronic renal failure, and had lower high-density lipoprotein (HDL) levels. Peak HR, SSS, SRS, sLVEF and rLVEF were lower; rest HR, RTS, and the number of patients with ≤ 45 % sLVEF and rLVEF were higher in reduced HR response group (all p < 0.05). There was no difference between groups by means of gender, rest and peak systolic or diastolic tension, SDS, SMS, STS, RMS, history of hypertension, peripheral arterial disease, metabolic syndrome, coronary interventions, digoxin, calcium channel blocker or beta blocker usage. Multivariable logistic regression analysis demonstrated that the independent predictors of reduced HR response were HDL, rest HR and SSS. When HDL was removed from the model, chronic renal failure also emerged as an independent predictor. CONCLUSION: Reduced HR response to dipyridamole is associated with ventricular dysfunction, cardiac autonomic neuropathy. Low HDL levels also seem to be related with reduced HR response.