The relationship between positron emission tomography-computed tomography imaging and histopathological features of thyroid incidentalomas detected during follow-up for primary malignancy

Aim of the Study: While the rate of thyroid incidentaloma detected on positron emission tomography (PET) was reported as 4%, the malignancy rate was 14%–50%. We evaluated the thyroid nodules which were detected by PET-computerized tomography (CT) in cancer patients and analyzed the pathological results of those thyroid nodules diagnosed by fine needle aspiration biopsy (FNAB) and their correlation with the maximum standardized uptake (SUVmax) value and PET imaging features. Materials and Methods: FNAB were performed for 40 thyroid incidentalomas. We analyzed the relationship between the histopathological findings and radiological features by Pearson's correlations and Chi-square-Fisher's exact tests to evaluate the factors associated with SUVmax. Results: The median SUVmax values were 5.4 for thyroid nodules. Totally, 14 malignancies were detected by FNAB (35%).The sensitivity and specificity of SUVmax value for diagnosis of malignancy were 87.5% and 52%, respectively. Positive and negative predictive values were 36.8% and 92.8%. The most common malignant and benign pathologies were classic variant papillary carcinoma and benign colloidal nodule. The median SUVmax was the higher in colon cancer thyroid metastasis and oncocytic neoplasia (SUVmax 14.5 and 13.6, respectively). Histopathological type was not related with nodule size but positively associated with categorical SUVmax(r = 0.318, P = 0.04) and negatively correlated with both the density of the thyroid nodule in PET-CT (r = −0.0042, P = 0.01) and density of nodule in ultrasound (USG) (r = −0.305, P = 0.05). Margin of the thyroid nodule in USG (P = 0.007) and internal component of the nodule in PET (P = 0.03) were found to be important factors to differentiate benign or malignant lesion. Conclusion: If the thyroid nodule is detected with flouro-2-deoxy-D-glucose uptake, to differentiate benign nodule from malignant, cytological examination is noteworthy to diagnose the more aggressive type of thyroid nodule and also thyroid metastasis from primary cancer

Outcome in Patients with Fever of Unknown Origin whose ¹⁸Fluoro-Deoxyglucose Positron Emission Tomography/Computerized Tomography Finding is Non-Diagnostic

Prognosis has not been known for patients with fever of unknown origin (FUO) whose ¹⁸fluoro-deoxyglucose (¹⁸F-FDG) positron emission tomography/computerized tomography (PET/CT) finding is non-diagnostic. A total of eight patients with FUO that underwent ¹⁸F-FDG PET/CT were retrospectively identified January 2016 - June 2017 in a tertiary hospital in Korea. Of these, two patients were diagnosed with microscopic polyangitis and Kikuchi's disease and one patient was transferred to another hospital. Of five patients whose diagnoses were not confirmed, four patients received non-steroidal anti-inflammatory drug and/or low dose steroid and symptoms disappeared. Our study suggests that outcome of patients with FUO whose ¹⁸F-FDG PET/CT finding is non-diagnostic would be favorable.

Outcome in Patients with Fever of Unknown Origin whose ¹⁸Fluoro-Deoxyglucose Positron Emission Tomography/Computerized Tomography Finding is Non-Diagnostic

Prognosis has not been known for patients with fever of unknown origin (FUO) whose ¹⁸fluoro-deoxyglucose (¹⁸F-FDG) positron emission tomography/computerized tomography (PET/CT) finding is non-diagnostic. A total of eight patients with FUO that underwent ¹⁸F-FDG PET/CT were retrospectively identified January 2016 - June 2017 in a tertiary hospital in Korea. Of these, two patients were diagnosed with microscopic polyangitis and Kikuchi's disease and one patient was transferred to another hospital. Of five patients whose diagnoses were not confirmed, four patients received non-steroidal anti-inflammatory drug and/or low dose steroid and symptoms disappeared. Our study suggests that outcome of patients with FUO whose ¹⁸F-FDG PET/CT finding is non-diagnostic would be favorable.

Thymic epithelial tumors: Can fluorodeoxyglucose positron emission tomography help in predicting histologic type and stage.

OBJECTIVES: To study the utility of fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting (1) the World Health Organization (WHO) histologic type and differentiating low‑risk from high‑risk types. (2) Tumor stage and differentiate early from advanced stage disease. MATERIALS AND METHODS: Patients with thymic epithelial neoplasia who underwent a pretreatment FDG‑PET study were included. Tumor maximum standardized uptake value (SUVmax) was correlated with the WHO histologic type and also with the Masaoka‑Koga (MK) staging system. Patients with WHO Type A, AB, and B1 were classified as low risk and those with B2 and B3 as high risk. Thymic carcinomas belonged to Type C. Patients with MK Stage I and II disease were grouped as early stage and those with Stage III and IV as an advanced stage. Differences in SUVmax between the various groups were calculated. RESULTS: The SUVmax of thymic carcinomas was significantly higher as compared to low‑risk (P = 0.001) and high‑risk groups (P = 0.007). The SUVmax of high‑risk group was also significantly higher than the low‑risk group (P = 0.002). SUVmax cutoff of 6.5 was able to differentiate thymic carcinomas from thymomas with 100% sensitivity and 87.2% specificity. The SUVmax in patients with advanced stage disease showed a higher trend compared to those with early stage, but the difference was not significant (P = 0.167). CONCLUSION: PET can differentiate thymic carcinomas from rest of the thymoma subtypes by the virtue of their higher FDG uptake. It can also provide valuable information in differentiating high‑risk from low‑risk thymomas and in predicting disease stage.

Tuberculous Scar Tumour Detected by Dual Tracer Positron Emission-Computerised Tomography in a Tuberculous Endemic Area

Tuberculous scar tumour is difficult to diagnose as it does not present with any respiratory symptoms and has a negative chest X-ray. This is a case report on the use of dual tracer 11C-acetate and 18F-fluorodeoxyglucose (18FDG) whole body positron emission tomography-computerised tomography (PET-CT) for detection of tuberculous scar tumour. A 44-year-old Chinese female was incidentally found to have a raised serum Ca 19.9. Magnetic resonance imaging of the whole abdomen, upper endoscopy, and colonoscopy were all unremarkable. A low-dose computed tomography (CT) of the thorax showed bilateral upper lobe fibrosis. Bronchoalveolar lavage for culture and cytology was negative. A dual tracer 11C-acetate and 18FDG whole body PET-CT showed that the left upper lobe fibrosis was hypermetabolic in nature. It was more avid for 11C-acetate than for 18FDG. The left upper lobe lesion was subsequently confirmed on open lung biopsy to be a moderately differentiated adenocarcinoma. Therefore, in a tuberculous endemic region, dual tracer whole body PET-CT with 11C-acetate and 18FDG may have a role in the early detection of tuberculous scar tumour in the lung.

Usefulness of Positron Emission Tomography-Computerized Tomography Uptake according to Early Gastric Cancer Gross Morphology

BACKGROUND/AIMS: The role of 18F-fluorodeoxyglucose (18F-FDG) PET-CT for early gastric cancer (EGC) was undetermined due to its low sensitivity. The aim of this study was to assess the usefulness of 18F-FDG PET-CT according to endoscopic classification of EGC. MATERIALS AND METHODS: We retrospectively reviewed 206 patients who had undergone PET-CT due to gastric cancer from June 2009 to June 2012. Among those patients, 120 including 65 patients who underwent gastrectomy were analyzed. RESULTS: According to endoscopic gross morphology, 50 (41.7%) patients were classified as EGC and 70 (58.3%) patients were classified as advanced gastric cancer (AGC). Compared with the EGC group, the AGC group showed significantly higher rate of positive 18F-FDG uptake of primary lesions (98.6% vs. 28.0%, P<0.001) and lymph nodes (50.0% vs. 6.0%, P<0.001), and higher standardized uptake value max of primary lesions (7.65+/-3.51 vs. 4.82+/-2.18, P=0.012). Among 65 patients who underwent gastrectomy, PET-CT positive lesions were found in patients with tumor size greater than 3 cm (86.4% vs. 9.5%, P<0.001), lesions detected by stomach CT (90.9% vs. 9.5%, P<0.001) and PET-CT lymph node positive lesions (4.8% vs. 31.8%, P=0.025). Among 31 patients with EGC, elevated types (type I and IIa) showed no difference of positive 18F-FDG uptake compared with flat or depressed types (IIb, IIc, and III) (55.6% vs. 31.8%, P=0.253). CONCLUSIONS: 18F-FDG PET-CT has positive detection rate for EGC greater than 3 cm and there was no differences of 18F-FDG PET-CT uptake rates between elevated types and flat or depressed types of EGC.

Value of ~(18)Fluorodexyglucose PET/CT for gastric carcinoma / 医学研究生学报

Objective: To investigate the value of positron emission tomography/computerized tomography(PET/CT) with fluorine-18-labeled fluorodeoxyglucose(18FDG) for gastric carcinoma.Methods: Thirty-two patients(25 males,7 females,aged 31-82 years) suspected of gastric carcinoma underwent whole-body PET/CT after taking in 600 ml of water to distend the gastral cavity.The maximal standard uptake value(SUVmax) of the region of interest(ROI) in PET and the maximum width of the gastric wall in CT were analyzed.Pathological specimens were obtained from all the patients during surgery or gastroscopy.Results: 18FDG PET/CT found gastric carcinoma in 24 of the patients.The rates of positive and negative prediction and the accuracy of PET/CT in the diagnosis of the disease were 92.3%,100% and 93.8%.SUVmax was positively correlated with the maximum width of the gastric wall,but they exhibited no statistically significant differences between the patients with involved lymph nodes and those without.Based on the PET/CT findings,the 24 gastric carcinoma patients were clinically classified as follows: 9 in stage Ⅰ,1 in stage Ⅰ-Ⅱ,3 in stage Ⅱ,1 in stage Ⅲ and 10 in stage Ⅳ.Conclusion: 18FDG PET/CT is highly valuable for gastric carcinoma in its diagnosis,the evaluation of its biological behavior and determination of its treatment strategies.