The evaluation of hypermetabolic mediastinal-hilar lymph nodes determined by PET/CT in pulmonary and extrapulmonary malignancies: correlation with EBUS-TBNA.

BACKGROUND/AIM: We aimed to define the optimal SUV(max) cut-off value in determination of mediastinal-hilar lymph node metastasis, by comparing positive PET/CT results with the results of endobronchial ultrasound guided transbronchial needle aspiration biopsy (EBUS-TBNA). MATERIALS AND METHODS: Thirty-one patients with malignancy whose PET/CT imaging revealed a hypermetabolic mediastinal and/or hilar lymph node and who had undergone EBUS-TBNA were evaluated retrospectively. Histopathology was regarded as the gold standard. The diagnostic role of PET/CT in mediastinal/hilar lymph node metastasis was investigated and compared with the results of contrast-enhanced CT. RESULTS: When a SUV(max) value of 2.5 was used, the sensitivity, positive predictive value (PPV), and diagnostic accuracy of the PET/CT were 100%, 65.4%, and 65.4% respectively. In the ROC analysis, the SUV(max) cut-off value with the highest diagnostic accuracy (75%) was calculated as 6.3, and when this value was considered, the sensitivity, specificity, PPV, negative predictive value, and diagnostic accuracy of the PET/CT were determined as 70.6%, 83.3%, 88.9%, 60%, and 75% respectively (AUC: 0.779). The sensitivity, PPV, and diagnostic accuracy of the thorax CT were calculated as 91.1%, 72%, and 71.1%, respectively. CONCLUSION: When determining mediastinal-hilar lymph node metastasis via PET/CT, although a SUV(max) cut-off value of 6.3 increases specificity and diagnostic accuracy, we think that a SUV(max) cut-off value of 2.5 and above give more optimal results in routine practice.

Predictors and Diagnostic Significance of the Adenosine Related Side Effects on Myocardial Perfusion SPECT/CT Imaging.

OBJECTIVE: The aim of this study was to investigate the relationship between patient characteristics and adenosine-related side-effects during stress myocard perfusion imaging (MPI). The effect of presence of adenosine-related side-effects on the diagnostic value of MPI with integrated SPECT/CT system for coronary artery disease (CAD), was also assessed in this study. METHODS: Total of 281 patients (109 M, 172 F; mean age:62.6±10) who underwent standard adenosine stress protocol for MPI, were included in this study. All symptoms during adenosine infusion were scored according to the severity and duration. For the estimation of diagnostic value of adenosine MPI with integrated SPECT/CT system, coronary angiography (CAG) or clinical follow-up were used as gold standard. RESULTS: Total of 173 patients (61.6%) experienced adenosine-related side-effects (group 1); flushing, dyspnea, and chest pain were the most common. Other 108 patients completed pharmacologic stress (PS) test without any side-effects (group 2). Test tolerability were similar in the patients with cardiovascular or airway disease to others, however dyspnea were observed significantly more common in patients with mild airway disease. Body mass index (BMI) ≥30 kg/m2 and age ≤45 years were independent predictors of side-effects. The diagnostic value of MPI was similar in both groups. Sensitivity of adenosine MPI SPECT/CT was calculated to be 86%, specificity was 94% and diagnostic accuracy was 92% for diagnosis of CAD. CONCLUSION: Adenosine MPI is a feasible and well tolerated method in patients who are not suitable for exercise stress test as well as patients with cardiopulmonary disease. However age ≤45 years and BMI ≥30 kg/m2 are the positive predictors of adenosine-related side-effects, the diagnostic value of adenosine MPI SPECT/CT is not affected by the presence of adenosine related side-effects.

Hot-clot artifacts in the lung parenchyma on F-18 fluorodeoxyglucose positron emission tomography/CT due to faulty injection techniques: two case reports.

F-18-fluorodeoxyglucose (FDG) positron emission tomography/CT is an important whole-body imaging tool in the oncology and widely utilized to stage and restage various malignancies. The findings of significant focal accumulation of FDG in the lung parenchyma in the absence of corresponding CT abnormalities are related to the lung microembolism and known as hot-clot artifacts. Herein we present two cases with focal FDG uptake in the lung parenchyma with no structural lesions on the CT scan and discuss the possible mechanisms.

Predictive role of nontumoral sodium iodide symporter activity and preoperative thyroid characteristics in remission process of thyroid cancer patients.

OBJECTIVE: The target of radioiodine ablation therapy (RIAT) after complete tumor removal is the nontumoral remnant tissue. We aimed to evaluate sodium iodide symporter (NIS) expression in nontumoral thyroid tissue in differentiated thyroid cancer (DTC) patients who have complete but delayed structural response (DSR) to RIAT after surgery. Preoperative thyroid characteristics such as volume and nontumoral histology were also investigated for both DSR and its control group as potential predictors of insufficient NIS activity in this study. METHODS: Total of 600 patients with postoperative remnant thyroid tissue and who were in remission after RIAT spontaneously, were included in the study. Patients with positive diagnostic whole body scan (DxWBS) with thyroid bed uptake and stimulated serum Tg level <2 ng/mL at first year visit after initial therapy were defined as DSR group. Immunohistochemical staining of NIS protein was performed on the nontumoral tissue sections from surgery and semi quantified in terms of density and intensity. DSR and its control group were also compared in terms of NIS expression, radioiodine (RAI) uptake on post-therapy scan and preoperative thyroid characteristics. RESULTS: When compared with the control group, the density and intensity of NIS expression as well as the intensity of RAI uptake were significantly lower in DSR group (p = 0.001). There were also significant differences between groups regarding preoperative thyroid characteristics; i.e. preoperative thyroid volumes were significantly higher and the presence of concurrent benign thyroid disease was significantly more common in DSR group (p = 0.035, p = 0.001). Hashimoto thyroiditis was 8.59 times higher (95% CI; 2.31-31.96) and multinodular goiter was 7.50 times higher (95% CI; 1.88-29.91) among DSR group when compared with the control group. CONCLUSIONS: Our findings suggest that insufficient NIS activity in nontumoral thyroid tissue associates with DSR in DTC patients who have postoperative remnant tissue. Preoperative thyroid characteristics such as volume and concomitant benign thyroid disease may have an important role in predicting the complete response time to RIAT in these patients.

Additional Value of SPECT/CT to Tc-99m MAG3 Renal Scintigraphy in the Diagnosis of a Patient with Ureteroileal Fistula.

UNLABELLED: We performed Tc-99m MAG3 dynamic renal scintigraphy followed by a SPECT/CT imaging to a 38-yr-old woman who had a fistula in the lower urinary tract after a gynecological operation for diagnostic purposes. After scintigraphy, CT and fusion images were evaluated, it was observed that the activity in the right lower quadrant was actually in the ileal lumen. When early and late SPECT/CT images were compared, it was seen that the activity was moving distally with intestinal peristaltism. The reason for diagnostic imaging of the fistulas is not only to show the existence of the fistula but also locate it anatomically before the surgery. SPECT systems integrated with CT scanning provide functional and anatomical imaging at the same session. Dynamic renal scintigraphy and abdominal SPECT/CT, is a safe diagnostic procedure in visualization of urinary tract fistulas with advantages of the low cost, low radiation exposure and easier tolerability compared to double contrast imaging. CONFLICT OF INTEREST: None declared.