Evidence of 18F-FCH Uptake in Human T98G Glioblastoma Cells

AIM

Tumor and chemo/radiotherapy-damaged brain tissues are hardly distinguishable by conventional morphological imaging. (18)F-FCH was compared against (18)F-FDG in the T98G glioblastoma cell line with regard to their radiopharmaceutical uptake, in order to test its diagnostic power on brain tumor lesions.

MATERIALS AND METHODS

Equimolar amounts of (18)F-FCH and (18)F-FDG were added to human glioblastoma T98G cells and human dermal fibroblasts for 20, 40, 60, 90 and 120 min of incubation. Radiopharmaceutical uptake was expressed as a percentage of the administered dose. Cold choline was used for binding competition experiments.

RESULTS

In T98G cells (18)F-FCH was taken-up in higher amounts than 18F-FDG after 60 min. In fibroblasts, uptake was lower than 1% for both radiopharmaceuticals. Cold choline reduced the uptake of FCH to 1% similarly to fibroblasts.

CONCLUSION

Our results prove the efficacy of (18)F-FCH as a promising tracer, better than (18)F-FDG in establishing the tumor-to-background ratio in brain tumors.

(18)F-Fluorodeoxyglucose positron emission tomography/computed tomography in patients with Kikuchi-Fujimoto disease: a nine-case series in China

This study observed the image characteristics and clinico-imaging relationships of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the patients with Kikuchi-Fujimoto disease (KFD). Nine consecutive patients with histologically proven KFD who underwent (18)F-FDG PET/CT were recruited. The (18)F-FDG uptakes of bone marrow (BM), spleen and lymph nodes (LNs) were systematically evaluated and maximum standardized uptake values (SUVmax) were measured. The number, locations and size factors of LNs were also assessed. The correlations were calculated between (18)F-FDG uptake and laboratory data and size factors of LNs, and the findings of LNs were compared between subgroups with different clinical features. (18)F-FDG uptakes were positive in the BM (SUVmax, 3.2 ± 1.2), spleen (SUVmax, 2.8 ± 0.7) and 122 affected LNs (SUVmax, 4.2 ± 2.2) for all patients. The affected LNs presented a systemically (region, 4 ± 1), multiple (number, 14 ± 5) and small-sized (long axis diameter, 11.4 ± 2.7 mm; short axis diameter, 8.0 ± 2.1 mm; area, 81.1 ± 44.6 mm(2)) pattern. The SUVmax of BM correlated to neutrophil count, and the SUVmax of affected LNs correlated to size factors and was lower in patients with long imaging interval and positive anti-nuclear antibody (ANA) (P < 0.05). We conclude that (18)F-FDG PET/CT can be characterized by the generalized distribution of relatively small-sized LNs and involvement of BM and spleen with high (18)F-FDG avidity in patients with KFD. The imaging interval, neutrophil count and ANA level should be synthetically considered during imaging evaluation.

Venous thrombosis of sarcoidosis as an unusual incidental finding on 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Sarcoidosis is defined as a multisystem granulomatous disorder of unknown cause. Venous thrombosis (VT) in the sarcoidosis is rare. The routine use of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has resulted in clinicians detecting many incidental findings, which have proven to be clinically significant such as thrombosis. Here, we present a case with VT of sarcoidosis in the inferior vena cava and portal vein as an unusual incidental finding on 18F-FDG PET/CT.

18F-fluorodeoxyglucose positron emission tomography/computed tomography for primary thyroid langerhans histiocytosis: A case report and literature review

Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disease, with an incidence rate of 4.0-5.4/1 million individuals. LCH encompasses a spectrum of disorders with diverse clinical presentations ranging from a single organ to multiple organ involvement. LCH rarely involves the thyroid gland. We presented a case with LCH of thyroid gland. The patient had painless progressive neck enlargement and then diabetes insipidus. Ultrasonic scan and magnetic resonance imaging scan revealed nodular goiter and pituitary stalk enlargement, respectively. Histopathological analysis revealed features of histiocytoid cells. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) was performed in order to rule out the presence of whole body infiltration. 18F-FDG PET/CT also demonstrated increased uptake in the thickening pituitary stalk and maxillofacial skin lesion, in addition to the bilateral thyroid nodules, CT showed the left lung nodule and the skull destruction without 18F-FDG uptake. This report emphasizes the role of 18F-FDG PET/CT in multiple organs involvement of patients with LCH.

Adult granulosa cell tumor presenting with massive ascites, elevated CA-125 level, and low (18)F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography

Adult granulosa cell tumors (AGCTs) presenting with massive ascites and elevated serum CA-125 levels have rarely been described in the literature. An ovarian mass, massive ascites, and elevated serum CA-125 levels in postmenopausal women generally suggest a malignant ovarian tumor, particularly advanced epithelial ovarian cancer. AGCT has low ¹⁸F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography due to its low metabolic activity. In the present report, we describe a case of an AGCT with massive ascites, elevated serum CA-125 level, and low ¹⁸F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography.

Association Between (18)F-FDG Avidity and the BRAF Mutation in Papillary Thyroid Carcinoma

PURPOSE

The BRAF mutation, a potential prognostic factor in papillary thyroid carcinoma (PTC), is associated with a high expression of the glucose transporter gene. We investigated which clinicopathologic factors, including BRAF mutation status, influence (18)F-fluoro-2-deoxyglucose ((18)F-FDG) avidity.

METHODS

We retrospectively reviewed 55 patients who underwent BRAF analysis from biopsy-confirmed PTC and (18)F-FDG positron emission tomography/computed tomography within 6 months before undergoing thyroid surgery from September 2008 to August 2014. Tumors were considered to be (18)F-FDG avid if the uptake was greater than that of the liver. (18)F-FDG uptake of PTCs was also analyzed semiquantitatively using SUVmax. The association between (18)F-FDG avidity and clinicopathologic variables (age, tumor size, perithyroidal extension, cervical lymph node status, and BRAF mutation status) was investigated.

RESULTS

Twenty-nine (52.7 %) of 55 patients had (18)F-FDG-avid PTCs. PTCs with the BRAF mutation showed higher (18)F-FDG avidity (24/38, 63.2 %) than those without (5/17, 29.4 %). The BRAF mutation (p = 0.025) and tumor size (p = 0.003) were significantly associated with (18)F-FDG avidity in univariate analysis, and the BRAF mutation status remained significant after adjusting for tumor size in multivariate analysis (p = 0.015). In the subgroup of tumor size ≥ 1 cm, the BRAF mutation was the only factor significantly associated with (18)F-FDG avidity (p = 0.021). The mean SUVmax of PTCs with the BRAF mutation was significantly higher than that of those without (4.89 ± 6.12 vs. 1.96 ± 1.10, p = 0.039).

CONCLUSIONS

The BRAF mutation must be one of the most important factors influencing (18)F-FDG avidity in PTCs, especially in those with a tumor size ≥ 1 cm.

18F-FLT PET/CT in the Evaluation of Pheochromocytomas and Paragangliomas: A Pilot Study

(18)F-FDG PET/CT has been proven to be a highly sensitive method for pheochromocytomas/paragangliomas (PHEOs/PGLs) associated with succinate dehydrogenase (SDH) mutations. This finding has been attributed to altered tumor cell metabolism resulting from these mutations and does not provide additional prognostic information to genotype. Therefore, identification of new biomarkers for aggressiveness is needed. A high Ki-67 index was proposed to be an additional prognostic factor. This pilot study aimed to evaluate 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) PET/CT, a PET proliferation tracer, as a potential imaging agent in a series of 12 PHEO/PGL patients with different genetic backgrounds, to compare (18)F-FLT uptake with (18)F-FDG PET/CT, and to evaluate classic factors of aggressiveness.

METHODS

Twelve patients (7 metastatic and 5 nonmetastatic) were prospectively evaluated with (18)F-FDG and (18)F-FLT and followed for at least 2 y after the initial imaging work-up. Uptake was assessed at a lesion level, visually and quantitatively by maximum standardized uptake values (SUVmax) for both tracers. (18)F-FLT uptake was compared with risk factors known to be linked with a poor prognosis in PGLs (SDHB-mutated status, lesion size, dopaminergic phenotype) and with (18)F-FDG uptake.

RESULTS

In 12 patients, 77 lesions were assessed. All lesions had low (18)F-FLT uptake (median SUVmax, 2.25; range, 0.7-4.5). There was no apparent superiority of (18)F-FLT uptake in progressive lesions, and most of the lesions showed a mismatch, with high (18)F-FDG uptake (median SUVmax, 10.8; range, 1.1-79.0) contrasting with low (18)F-FLT uptake.

CONCLUSION

This study suggests that PHEOs/PGLs-even those that progress-do not exhibit intense (18)F-FLT uptake. It provides the first in vivo demonstration that proliferation may not be a major determinant of (18)F-FDG uptake in these tumors. These findings provide new insight into the biologic behavior of PGL and suggest that antiproliferative agents may be suboptimal for treatment of these tumors.

Relationship Between 18F-FDG Uptake on PET and Recurrence Patterns After Curative Surgical Resection in Patients with Advanced Gastric Cancer

This study evaluated the predictive value of 18F-FDG PET for distant metastasis-free survival and peritoneal recurrence-free survival as well as recurrence-free survival and overall survival after curative surgical resection in patients with advanced gastric cancer (AGC).

METHODS

Two hundred seventy-nine patients with AGC who underwent preoperative 18F-FDG PET and subsequent curative surgical resection were included. The tumor-to-normal liver uptake ratio (TLR) of cancer lesions was measured, and the prognostic significance of TLR and tumor factors for distant metastasis-free survival, peritoneal recurrence-free survival, recurrence-free survival, and overall survival was assessed.

RESULTS

The 5-y recurrence-free survival, peritoneal recurrence-free survival, distant metastasis-free survival, and overall survival rates were 46.9%, 68.5%, 76.0%, and 58.1%, respectively. Depth of tumor invasion, lymph node metastasis, lymphovascular invasion, and TLR were independent prognostic factors for both recurrence-free survival and overall survival (P<0.05). For distant metastasis-free survival, lymphovascular invasion and TLR were independent risk factors (P<0.05). In patients with a TLR of 2.0 or less, the 5-y distant metastasis-free survival rate was 95.5%; in patients with a TLR greater than 2.0, the 5-y distant metastasis-free survival rate was 68.8%. For peritoneal recurrence-free survival, TLR showed no statistical significance (P=0.7) whereas pT stage, lymph node metastasis, Lauren classification, and Bormann type were independent prognostic factors (P<0.05).

CONCLUSION

18F-FDG uptake of AGC is an independent prognostic factor for distant metastasis-free survival, recurrence-free survival, and overall survival. The possibility of distant metastasis during follow-up should be considered in patients with high 18F-FDG uptake.

Clinical significance of incidental FDG uptake in the prostate gland detected by PET/CT

The value of FDG-positron emission tomography/computed tomography (PET/CT) for detecting prostate cancer is unknown. We aimed to investigate the clinical value of incidental prostate FDG uptake on PET/CT scans. We reviewed 6128 male patients who underwent FDG-PET/CT scans and selected cases that reported hypermetabolic lesion in the prostate. The patients who have prior history of prostate carcinoma or prostate surgery were excluded from the study. We have analyzed the correlation between PET/CT findings and serum prostate-specific antigen (PSA) levels, imaging (USG), urological examinations and biopsy. Incidental 18F-FDG uptake of the prostate gland was observed in 79 patients (1.3%). While sixteen of them were excluded due to inadequate clinical data, the remaining 63 patients were included for further analysis. The patients were divided into two groups; 8 patients (12.7%) in the malignant group and 55 patients (87.3%) in the benign group. The SUVmax values were not significantly different between the two groups. In 6 (75%) patients with prostate cancer, FDG uptake was observed focally in the peripheral zone of the prostate glands. There was no significant correlation between the SUVmax and the PSA levels. Incidental 18F-FDG uptake in the prostate gland is a rare condition, but a substantial portion of it is associated with the cancer. Benign and malignant lesions of the prostate gland in FDG-PET/CT imaging could not be reliably distinguished. The peripheral focally FDG uptake of prostate glands should be further examined with the clinical and labaratory evaluations.

In vivo18F-fluorodeoxyglucose-positron emission tomography/computed tomography imaging of pancreatic tumors in a transgenic rat model carrying the human KRASG12V oncogene

A novel KRAS-mediated transgenic rat model has previously been demonstrated, in which animals develop multiple pancreatic ductal adenocarcinoma (PDAC) that is histologically similar to human PDAC within two weeks. Positron emission tomography (PET)/computed tomography (CT) is commonly used for the diagnosis and staging of PDAC in humans, and can be adopted for optimal use in animal experiments. The aim of the present study was to evaluate the carcinogenic process in a rat pancreatic carcinoma model using small-animal multimodality imaging systems. The utility of fluorodeoxyglucose (FDG)-PET/CT in detecting the location and size of PDAC during tumor development in the present transgenic rat model was assessed. A small animal multimodality PET/CT system and contrast-enhanced CT (CECT) system were used for the imaging analysis of KRAS^G12V male transgenic rats (n=6), which developed pancreatic tumors following the administration of an injection of Cre recombinase (Cre)-carrying adenovirus. Laparotomies performed at six weeks post-treatment revealed that all three (100%) Cre-expressing rats developed pancreatic tumors that were <2 mm in diameter, none of which were detected by ¹⁸F-FDG PET/CT or CECT. At eight weeks post-treatment, the pancreatic tumors were heterogeneously visualized by ¹⁸F-FDG-PET/CT and CECT in two of the three rats. Furthermore, the autopsies confirmed that all three rats had developed pancreatic tumors. These novel findings provide evidence that the FDG-PET/CT imaging system is a valuable tool for the evaluation of the carcinogenic process, and one which may aid in treatment and preventive methods for pancreatic tumors in mammalian models. A limitation associated with the early detection of PDACs warrants further investigation.

A novel phantom technique for evaluating the performance of PET auto-segmentation methods in delineating heterogeneous and irregular lesions

BACKGROUND

Positron Emission Tomography (PET)-based automatic segmentation (PET-AS) methods can improve tumour delineation for radiotherapy treatment planning, particularly for Head and Neck (H&N) cancer. Thorough validation of PET-AS on relevant data is currently needed. Printed subresolution sandwich (SS) phantoms allow modelling heterogeneous and irregular tracer uptake, while providing reference uptake data. This work aimed to demonstrate the usefulness of the printed SS phantom technique in recreating complex realistic H&N radiotracer uptake for evaluating several PET-AS methods.

METHODS

Ten SS phantoms were built from printouts representing 2mm-spaced slices of modelled H&N uptake, printed using black ink mixed with 18F-fluorodeoxyglucose, and stacked between 2mm thick plastic sheets. Spherical lesions were modelled for two contrasted uptake levels, and irregular and spheroidal tumours were modelled for homogeneous, and heterogeneous uptake including necrotic patterns. The PET scans acquired were segmented with ten custom PET-AS methods: adaptive iterative thresholding (AT), region growing, clustering applied to 2 to 8 clusters, and watershed transform-based segmentation. The difference between the resulting contours and the ground truth from the image template was evaluated using the Dice Similarity Coefficient (DSC), Sensitivity and Positive Predictive value.

RESULTS

Realistic H&N images were obtained within 90 min of preparation. The sensitivity of binary PET-AS and clustering using small numbers of clusters dropped for highly heterogeneous spheres. The accuracy of PET-AS methods dropped between 4% and 68% for irregular lesions compared to spheres of the same volume. For each geometry and uptake modelled with the SS phantoms, we report the number of clusters resulting in optimal segmentation. Radioisotope distributions representing necrotic uptakes proved most challenging for most methods. Two PET-AS methods did not include the necrotic region in the segmented volume.

CONCLUSIONS

Printed SS phantoms allowed identifying advantages and drawbacks of the different methods, determining the most robust PET-AS for the segmentation of heterogeneities and complex geometries, and quantifying differences across methods in the delineation of necrotic lesions. The printed SS phantom technique provides key advantages in the development and evaluation of PET segmentation methods and has a future in the field of radioisotope imaging.

Assessment of cell proliferation in renal cell carcinoma using dual-phase 18F-fluorodeoxyglucose PET/CT

The present study aimed to examine the association between ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake and cell proliferation markers; in addition, the correlation between ¹⁸F-FDG uptake and biological characteristic in patients with renal cell carcinoma (RCC) was investigated using dual-phase ¹⁸F-FDG-positron emission tomography/computed tomography (PET/CT). Dual-phase ¹⁸F-FDG PET/CT was performed on 31 RCC patients and the maximum standardized uptake values at 1 h (SUV1) and 2 h (SUV2) as well as the retention index (RI; %) in the primary tumors were calculated. Monoclonal antibodies for Ki-67, minichromosome maintenance 2 (MCM2) and topoisomerase II α (topo II α) were used to assess the expression levels of their respective proteins in excised tumor tissue using immunohistochemistry. The results demonstrated that RI and SUV2 in patients with Stage I/II + grade 1 (G1) RCC were significantly decreased compared with all patients with other stages/grades (RI, P=0.0065; SUV2, P=0.043); in addition, significantly increased uptake and RI were detected in patients with metastases compared with patients without metastases (SUV1, P=0.029; SUV2, P=0.0003; RI, P<0.001). All proliferation markers significantly correlated with RI (Ki-67, r=0.501, P=0.004; MCM2, r=0.359, P=0.047; topo II α, r=0.402, P=0.024), while SUV1 and SUV2 correlated with Ki-67 only. In conclusion, the results of the present study demonstrated that dual-phase ¹⁸F-FDG-PET/CT was more useful for predicting cell proliferation in RCC compared with single-phase imaging alone. However, follow-ups are required in order to determine whether dual-phase ¹⁸F-FDG-PET/CT provides independent prognostic information.

The role of 18F-FDG accumulation and arterial enhancement as biomarkers in the assessment of typing, grading and staging of hepatocellular carcinoma using 18F-FDG-PET/CT with integrated dual-phase CT angiography

AIM

The purpose of the present study was to evaluate the possibility of detection, staging and differentiation assessment of hepatocellular carcinoma (HCC) using a combination of dual-phase computed tomography (CT)-angiography in the arterial and portal phase with positron emission tomography (PET) imaging using (18)F-fluorodeoxyglucose ((18)FDG).

PATIENTS AND METHODS

From a set of 10,000 patients who underwent (18)FDG-PET/CT, we examined a total of 65 patients (52 males, 13 females; mean age=61.7 years, ranging from 35-82 years) with HCC. The imaging included CT data acquisition after intravenous application of iodinated contrast material in arterial and portal phases, allowed to obtain data in CT angiography quality. Histological diagnosis of the resection sample (21), biopsy (37) or necropsy (7), including the evaluation of the hepatocytary origin of the tumor and the grade of its differentiation, was determined in all patients.

RESULTS

The most sensitive sign in the detection of HCC was the alternative presence of hypervascularity or hyperaccumulation of (18)F FDG that reached 93.8%. The high level of (18)F-FDG accumulation showed sensitivity of 84.1% and specificity of 75.0% for distinguishing between well- and poorly differentiated HCC.

CONCLUSION

The combination of the dual-phase CT angiography with (18)FDG PET helps in the assessment of staging and differentiation of HCC and has an important role in treatment decision-making.

18FDG SUV in the primary tumor and lymph node metastases is not predictive for development of distant metastases in high risk head and neck cancer patients

BACKGROUND

Pretreatment screening on distant metastases is particularly useful in head and neck squamous cell carcinoma (HNSCC) patients with high risk factors.

METHODS

In a retrospective study of 88 patients with previously identified clinical high risk factors the predictive value of standardized uptake value (SUV) of 18F-fluorodeoxyglucose (FDG) in the primary tumor and in the lymph node metastases for the development of distant metastases was examined. Different SUVs corrected for plasma glucose levels and body mass index were calculated and analysed in different patient groups: all patients (n=88), patients with a follow up >6months (n=73), not previously treated patients (n=51) and not previously treated patients with a follow up >6months (n=40).

RESULTS

Twenty-four of the 88 (27%) high risk HNSCC patients were diagnosed with distant metastases during screening and follow up. No correlation was found between different SUVs of the primary tumor and lymph nodes metastases and the development of distant metastases.

CONCLUSION

SUVs of primary tumor and lymph node on FDG-PET are not predictive for distant metastases in a (selected) group of patients with already high risk factors for distant metastases.

The reverse Warburg effect and 18F-FDG uptake in non-small cell lung cancer A549 in mice: a pilot study

The purpose of this study was to observe the effect of fasting and feeding on (18)F-FDG uptake in a mouse model of human non-small cell lung cancer.

METHODS

In in vivo studies, (18)F-FDG small-animal PET scans were acquired in 5 mice bearing non-small cell lung cancer A549 xenografts on each flank with continuous feeding and after overnight fasting to observe the changes in intratumoral distribution of (18)F-FDG and tumor (18)F-FDG standardized uptake value (SUV). In ex vivo studies, intratumoral spatial (18)F-FDG distribution assessed by autoradiography was compared with the tumor microenvironment (including hypoxia by pimonidazole and stroma by hematoxylin and eosin stain). Five overnight-fasted mice and 5 fed mice with A549 tumors were observed.

RESULTS

Small-animal PET scans were obtained in fed animals on day 1 and in the same animals after overnight fasting; the lapse was approximately 14 h. Blood glucose concentration after overnight fasting was not different from fed mice (P = 0.42), but body weight loss was significant after overnight fasting (P = 0.001). Intratumoral distribution of (18)F-FDG was highly heterogeneous in all tumors examined, and change in spatial intratumoral distribution of (18)F-FDG between 2 sets of PET images from the same mouse was remarkably different in all mice. Tumor (18)F-FDG mean SUV and maximum SUV were not significantly different between fed and fasted animals (all P > 0.05, n = 10). Only tumor mean SUV weakly correlated with blood glucose concentration (R(2) = 0.17, P = 0.03). In ex vivo studies, in fasted mice, there was spatial colocalization between high levels of (18)F-FDG uptake and pimonidazole-binding hypoxic cancer cells; in contrast, pimonidazole-negative normoxic cancer cells and noncancerous stroma were associated with low (18)F-FDG uptake. However, high (18)F-FDG uptake was frequently observed in noncancerous stroma of tumors but rarely in viable cancer cells of the tumors in fed animals.

CONCLUSION

Host dietary status may play a key role in intratumoral distribution of (18)F-FDG. In the fed animals, (18)F-FDG accumulated predominantly in noncancerous stroma in the tumors, that is, reverse Warburg effect. In contrast, in fasted status, (18)F-FDG uptake was found in hypoxic cancer cells component (Pasteur effect). Our findings may provide a better understanding of competing cancer glucose metabolism hypotheses: the Warburg effect, reverse Warburg effect, and Pasteur effect.

(18)F-fluorodeoxyglucose positron emission tomography/computed tomography in infected polycystic kidney disease

A positron emission tomography/computed tomography (PET/CT) study using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) was performed in a 54-year-old female with polycystic kidney disease, fever, and abdominal discomfort. Cyst's infection was suspected, but CT and U/S findings were not specific to accurately depict pyocysts and guide surgical treatment. In PET/CT, both kidneys are enlarged with multiple cysts and little remaining parenchyma. There is intense focal or ring-shaped FDG uptake in cysts in the upper and lower poles of the left kidney indicative of active infection. There is also increased FDG uptake in para-aortic lymph nodes bilaterally. Hepatic and right renal cysts do not present increased FDG uptake. As this case illustrates, FDG PET/CT can be helpful for the precise localization of cyst infections in patients with polycystic kidney disease considered for surgical treatment.

Relations Between Pathological Markers and Radioiodine Scan and (18)F-FDG PET/CT Findings in Papillary Thyroid Cancer Patients With Recurrent Cervical Nodal Metastases

PURPOSE

The aim of this study was to investigate relationships between the immunohistochemical results and radioiodine scan and (18)F-FDG PET findings in papillary thyroid cancer (PTC) patients with recurrent cervical nodal metastases.

METHODS

A total of 46 PTC patients who had undergone a radioiodine scan and/or (18)F-FDG PET/CT and a subsequent operation on recurrent cervical lymph nodes were enrolled. Twenty-seven patients underwent (18)F-FDG PET/CT, 8 underwent radioiodine scans, and 11 underwent both scans. In all surgical specimens, the immunoexpressions of thyroglobulin (Tg), sodium-iodide symporter (NIS), glucose transporter 1 (Glut-1), and somatostatin receptor 1 and 2A (SSTR1 and SSTR2A) were assessed, and associations between these expressions and radioiodine scan and (18)F-FDG PET findings were evaluated.

RESULTS

Of the 38 patients who underwent (18)F-FDG PET/CT, all patients with weak Tg expression had positive (18)F-FDG uptake, while only 45 % of the patients with moderate or strong Tg expression showed positive uptake (p = 0.01). The proportion of patients with positive (18)F-FDG uptake increased as the degree of Glut-1 expression with luminal accentuation increased. Of the 19 patients who underwent a radioiodine scan, the proportion with positive radioiodine uptake was greater among patients with strong NIS and SSTR2A expression than among patients expressing these markers at weak levels (p = 0.04 for all). All three patients with weak Tg expression were negative for radioiodine uptake.

CONCLUSION

The (18)F-FDG uptakes of recurrent cervical nodes are related to strong Glut-1 expression with luminal accentuation and weak Tg expression, whereas radioiodine uptake is related to the strong expressions of NIS and SSTR2A.

Contrast-enhanced (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in immunoglobulin G4-related retroperitoneal fibrosis

Immunoglobulin G4 (IgG4)-related disease encompasses a wide variety of immune disorders previously thought be distinct. IgG4-related retroperitoneal fibrosis is one such entity. Metabolic imaging with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) can be useful in the management of IgG4-related retroperitoneal fibrosis. We here discuss the case of 63-year-old male with IgG4-related retroperitoneal fibrosis and the role, ¹⁸F-FDG PET/CT played in his management.

Lymphadenopathy by Scrub Typhus Mimicking Metastasis on FDG PET/CT in a Patient with a History of Breast Cancer

We report the case of a 60-year-old woman with left-sided breast cancer who showed lymphadenopathy mimicking metastatic lesions. She underwent surveillance (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) after treatment. PET/CT demonstrated multiple lymphadenopathies with increased FDG uptake, most notably in the right axilla. She had an eschar on the right axillary area, and her serologic test was positive for anti-Orientia tsutsugamushi IgM antibody. Ten months after the treatment, follow-up FDG PET/CT and ultrasonography showed improvement in generalized lymphadenopathy.

Post-nephrectomy foreign-body granuloma in the retroperitoneum mimicking lymph node metastasis of renal cell cancer

Recently, iatrogenic foreign-body granuloma has been increasingly reported. The asymptomatic presentation and confusing appearance of granuloma can lead to misdiagnosis of a secondary malignancy, especially for a patient with a corresponding past medical history. Sometimes, surgical treatment is unavoidable, and the diagnosis relies upon the pathologic result. Herein, we report an unusual case of a 43-year-old man who underwent a nephrectomy for renal cell carcinoma (clear cell type) 5 years ago. A secondary granuloma was identified behind the inferior vena cava in the retroperitoneum 6 months after the surgery, but the radiologists had failed to identify it throughout the 4 years of routine examination. Later on, the lesion was identified by positron emission tomography, which classified it as a highly 18F-fluorodeoxyglucose-avid lesion. Considering no visible foreign-bodies identified on images, the lesion was arguably diagnosed as a lymph node metastasis of renal cancer. Finally, it was confirmed as a foreign-body granuloma encasing surgical suture and adipose tissue by the pathological analysis.

Consistent abnormalities in metabolic network activity in idiopathic rapid eye movement sleep behaviour disorder

Rapid eye movement sleep behaviour disorder has been evaluated using Parkinson's disease-related metabolic network. It is unknown whether this disorder is itself associated with a unique metabolic network. 18F-fluorodeoxyglucose positron emission tomography was performed in 21 patients (age 65.0±5.6 years) with idiopathic rapid eye movement sleep behaviour disorder and 21 age/gender-matched healthy control subjects (age 62.5±7.5 years) to identify a disease-related pattern and examine its evolution in 21 hemi-parkinsonian patients (age 62.6±5.0 years) and 16 moderate parkinsonian patients (age 56.9±12.2 years). We identified a rapid eye movement sleep behaviour disorder-related metabolic network characterized by increased activity in pons, thalamus, medial frontal and sensorimotor areas, hippocampus, supramarginal and inferior temporal gyri, and posterior cerebellum, with decreased activity in occipital and superior temporal regions. Compared to the healthy control subjects, network expressions were elevated (P<0.0001) in the patients with this disorder and in the parkinsonian cohorts but decreased with disease progression. Parkinson's disease-related network activity was also elevated (P<0.0001) in the patients with rapid eye movement sleep behaviour disorder but lower than in the hemi-parkinsonian cohort. Abnormal metabolic networks may provide markers of idiopathic rapid eye movement sleep behaviour disorder to identify those at higher risk to develop neurodegenerative parkinsonism.

Comparison of the diagnostic performance of 18F-fluorothymidine versus 18F-fluorodeoxyglucose positron emission tomography on pulmonary lesions: A meta analysis

A pulmonary lesion is an extremely common and clinically challenging disorder worldwide, and an accurate diagnosis of lung cancer is crucial for early treatment and management. The aim of the present study was to perform a comprehensive meta analysis to compare the diagnostic performance of ¹⁸F-fluorothymidine (¹⁸F-FLT) positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET in evaluating patients with pulmonary lesions. Relevant studies were identified using the PubMed, EMBASE and Cochrane library databases. The pooled estimated sensitivity, specificity, positive-likelihood ratio, negative-likelihood ratio, and diagnostic odds ratio (DOR) for ¹⁸F-FLT PET versus ¹⁸F-FDG PET were calculated as the main outcome measures. Summary receiver operating characteristic curves were also constructed by Meta-Disk 1.4 software using a Mose's constant of linear model. The meta analysis showed that ¹⁸F-FLT PET had a higher specificity (0.70; 95% CI, 0.61-0.77), but lower sensitivity (0.81; 95% CI, 0.74-0.87) compared to ¹⁸F-FDG PET (0.50; 95% CI, 0.41-0.58 for specificity; 0.92; 95% CI 0.86-0.95 for sensitivity). For DOR, ¹⁸F-FLT PET (12.58; 95% CI, 6.81-23.24) was higher compared to ¹⁸F-FDG PET (10.72; 95% CI, 5.51-20.87). The area under the curve was 0.8592 and 0.9240 for ¹⁸F-FLT PET and ¹⁸F-FDG PET, respectively (Z=0.976, P>0.05). In conclusion, ¹⁸F-FLT PET and ¹⁸F-FDG PET had good diagnostic performance for the overall assessment of pulmonary lesions, and ¹⁸F-FLT PET had a higher specificity compared to ¹⁸F-FDG PET, but was less sensitive than ¹⁸F-FDG PET. Therefore, ¹⁸F-FLT and ¹⁸F-FDG together could add diagnostic confidence for pulmonary lesions.

Imaging appearance of a singular metastatic adenoid cystic carcinoma of the right kidney: A case report and literature review

Renal metastasis of a submandibular gland adenoid cystic carcinoma is clinically rare when it presents with an atypical imaging appearance of singular renal metastases. Whole-body positron emission tomography (PET)/computed tomography (CT) can determine whether the singular renal mass is benign or malignant and identify metastases in other parts of the body, particularly in uncommon sites. In the present case, the patient developed a rare partial metastasis to the right kidney three years after undergoing a surgery for submandibular gland adenoid cystic carcinoma. Based on the present case, whole-body PET/CT examination could provide an important basis for making treatment plans for singular renal metastases.

The Anatomical Biological Value on Pretreatment (18)F-fluorodeoxyglucose Positron Emission Tomography Computed Tomography Predicts Response and Survival in Locally Advanced Head and Neck Cancer

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) has become increasingly relevant in the staging of head and neck cancers, but its prognostic value is controversial. The objective of this study was to evaluate different PET/CT parameters for their ability to predict response to therapy and survival in patients treated for head and neck cancer. A total of 28 consecutive patients with a variety of newly diagnosed head and neck cancers underwent PET/CT scanning at our institution before initiating definitive radiation therapy. All underwent a posttreatment PET/CT to gauge tumor response. Pretreatment PET/CT parameters calculated include the standardized uptake value (SUV) and the anatomical biological value (ABV), which is the product of SUV and greatest tumor diameter. Maximum and mean values were studied for both SUV and ABV, and correlated with response rate and survival. The mean pretreatment tumor ABV_max decreased from 35.5 to 7.9 (P = 0.0001). Of the parameters tested, only pretreatment ABV_max was significantly different among those patients with a complete response (CR) and incomplete response (22.8 vs. 65, respectively, P = 0.021). This difference was maximized at a cut-off ABV_max of 30 and those patients with ABV_max < 30 were significantly more likely to have a CR compared to those with ABV_max of ≥ 30 (93.8% vs. 50%, respectively, P = 0.023). The 5-year overall survival was 80% compared to 36%, respectively, (P = 0.028). Multivariate analysis confirmed that ABV_max was an independent prognostic factor. Our data supports the use of PET/CT, and specifically ABV_max, as a prognostic factor in head and neck cancer. Patients who have an ABV_max ≥ 30 were more likely to have a poor outcome with chemoradiation alone, and a more aggressive trimodality approach may be indicated in these patients.