Incidental Finding of Lipomatous Hypertrophy of the Interatrial Septum during 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography for Cervical Cancer

Lipomatous hypertrophy of the interatrial septum is a benign but less recognized pathology of the heart caused by benign fatty infiltration of the interatrial septum which most often spares the fossa ovalis. We share images of the incidentally detected fluorodeoxyglucose (FDG) uptake in the interatrial septum during the restaging of 18F-FDG positron emission tomography/computed tomography scan of cervical cancer.

Iodine-125 interstitial brachytherapy reduces tumor growth via Warburg effect inhibition in non-small cell lung cancer A549 ×enografts

Iodine-125 interstitial brachytherapy (125I-IBT) is an alternative and effective treatment option for unresectable non-small cell lung cancer (NSCLC), and the Warburg effect is a determinant of tumor growth. The present study aimed to explore the influence of 125I-IBT on tumor growth and the Warburg effect, and the potential mechanisms underlying NSCLC progression. Mice with A549 cell xenografts were evenly divided into a control group without 125I-IBT, and three treatment groups receiving 125I-IBT with 20, 40 and 60 Gy. Tumor volume (TV), maximum standardized uptake value (SUVmax) determined by 18F-fluorodeoxyglucose (18F-FDG) micro-positron emission tomography/computed tomography and mean optical density (MOD) of mammalian target of rapamycin (mTOR), c-Myc, hypoxia inducible factor-1α (HIF-1α) and glucose transporter 1 (GLUT1) staining were compared among groups. Tumor inhibition rate (TIR), 18F-FDG uptake attenuation rate (FUAR) and expression suppression rate (ESR) were also calculated on day 14 and 28. The results demonstrated that the mean TV in the 60 and 40 Gy groups was smaller compared with the control TVs since days 14 and 16, respectively. The mean SUVmax value of the 60 Gy group at day 14, and all treatment group SUVmax values at day 28 were lower compared with the controls. In addition, the MOD of mTOR and GLUT1 was lower in the 60 Gy group, compared with the other groups, and c-Myc and HIF-1α values were lower in the 40 and 60 Gy groups, compared with the control and 20 Gy group (P<0.05). SUVmax positively correlated to TV (day 14, r=0.711; day 28, r=0.586) and the MOD of c-Myc and GLUT1 (r=0.621 and 0.546, respectively; P<0.01). Furthermore, dose dependent increases were observed for TIR, FUAR and ESR. In conclusion, 125I-IBT reduced tumor growth by inhibiting the Warburg effect, which may have resulted from downregulation of mTOR, c-Myc, HIF-1α and GLUT1 expression, particularly c-Myc and GLUT1, in NSCLC A549 ×enografts.

Preoperative Nodal 18F-FDG Avidity Rather than Primary Tumor Avidity Determines the Prognosis of Patients with Advanced Gastric Cancer

Purpose

This study investigated whether the metabolic avidity of primary tumors and/or metastatic lymph nodes (LNs) measured by ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) was related to survival after surgery in patients with advanced gastric cancer (AGC).

Materials and Methods

One hundred sixty-eight patients with AGC who underwent preoperative ¹⁸F-FDG PET/CT and curative resection were included. The ¹⁸F-FDG avidity of the primary gastric tumor and LNs was determined quantitatively and qualitatively. The diagnostic performance of ¹⁸F-FDG PET/CT was calculated, and the prognostic significance of ¹⁸F-FDG avidity for recurrence-free survival (RFS) and overall survival (OS) was assessed.

Results

In all, 51 (30.4%) patients experienced recurrence, and 32 (19.0%) died during follow-up (median follow-up duration, 35 months; range, 3-81 months); 119 (70.8%) and 33 (19.6%) patients showed ¹⁸F-FDG-avid primary tumors and LNs, respectively. ¹⁸F-FDG PET/CT showed high sensitivity (73.8%) for the detection of advanced pathologic T (pT ≥3) stage and high specificity (92.2%) for the detection of advanced pN (≥2) stage. ¹⁸F-FDG avidity of LNs was significantly associated with RFS (P=0.012), whereas that of primary tumors did not show significance (P=0.532). Univariate and multivariate analyses revealed that ¹⁸F-FDG avidity of LNs was an independent prognostic factor for RFS (hazard ratio=2.068; P=0.029).

Conclusions

¹⁸F-FDG avidity of LNs is an independent prognostic factor for predicting RFS. Preoperative ¹⁸F-FDG PET/CT can be used to determine the risk and prognosis of patients with AGC after curative resection.

A combined study of 18F-FDG PET-CT and fMRI for assessing resting cerebral function in patients with major depressive disorder

The present study investigated changes in the regional cerebral metabolic rates of glucose uptake (rCMRglc) using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) and regional homogeneity (ReHo), together with resting-state blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI), in patients with major depressive disorder (MDD). In total, 18 patients with untreated MDD and 17 healthy control subjects underwent ¹⁸F-FDG PET and BOLD-fMRI scanning. The MDD patients' cerebral changes, measured as rCMRglc and ReHo values, were mapped and statistically analyzed. Compared with the control group, the patients with MDD had a decreased rCMRglc in the bilateral superior, middle and inferior frontal gyrus, in the bilateral superior and middle temporal gyrus, in the bilateral anterior cingulate cortex, in the bilateral putamen and caudate, and in the left pallidum, but an increased rCMRglc in the bilateral hippocampus and left thalamus. The ReHo values in the patient group were decreased in the bilateral superior and middle frontal gyrus, left pallidum, bilateral putamen and left anterior cingulate cortex, but increased in the right hippocampus and thalamus. No statistically significant differences were identified between decreased metabolism and ReHo brain regions of MDD patients (χ²=9.16; P=0.90) and between increased metabolism and ReHo brain regions (χ²=3.96; P=0.27), when comparing activated brain regions of PET and MRI. The standardized uptake values (SUV) of the bilateral superior, middle and inferior frontal gyrus, bilateral superior and middle temporal gyrus, bilateral putamen, the left caudate and pallidum, the left anterior cingulate cortex, and the bilateral hippocampus and thalamus were correlated with the ReHo (r=0.51–0.83; P<0.05). However, no correlation was detected between the SUV and ReHo in the right caudate and anterior cingulate cortex (r=0.41 and 0.37, respectively; P>0.05). Taken together, these results demonstrated that patients with MDD displayed characteristic patterns regarding changes of brain glucose uptake and ReHo in the resting state. Furthermore, ¹⁸F-FDG PET may be a more sensitive technique compared with BOLD-fMRI for the identification of brain lesions in patients with MDD.

Is 18F-FDG PET/CT useful for the differential diagnosis of solitary pulmonary nodules in patients with idiopathic pulmonary fibrosis?

OBJECTIVE

Idiopathic pulmonary fibrosis (IPF) is associated with an increased incidence of lung cancer, but patients with IPF often have poor pulmonary function and are vulnerable to pneumothorax and so using an invasive procedure to diagnose a single nodule detected on chest CT risks a critical adverse outcome. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is recognized to be useful for differentiating between benign and malignant solitary pulmonary nodules (SPN) in patients without IPF, but its diagnostic accuracy has not been investigated in patients with IPF. In this study, therefore, we investigated whether ¹⁸F-FDG PET/CT is useful for the differential diagnosis of SPNs in patients with IPF.

METHODS

From the IPF patient cohort of our institution, we retrospectively reviewed 55 patients (54 men, 1 woman; age 67.8 ± 7.6 years) with an SPN sized 8-30 mm (mean 18.5 ± 5.7 mm) who underwent chest CT followed by ¹⁸F-FDG PET/CT between April 2004 and March 2016. The ¹⁸F-FDG uptake of the SPN was analyzed visually and semiquantitatively, and these determinations were compared with the final diagnosis obtained by pathology (n = 52) or imaging follow-up (n = 3).

RESULTS

The final diagnoses showed that 41 (75%) of the SPNs were malignant (21 squamous cell carcinomas, 9 adenocarcinomas, 5 small-cell carcinomas, 4 mixed-type carcinomas, 1 large-cell neuroendocrine carcinoma, and 1 sarcoid carcinoma) and 14 (25%) were benign. The determination of malignant SPNs by visual analysis of the PET/CT images had a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 98, 86, 95, and 92%, respectively. The semiquantitative analysis using a maximum standardized uptake value of 2.0 as the cut-off had a sensitivity, specificity, PPV, and NPV of 95, 93, 98, and 87%, respectively.

CONCLUSIONS

¹⁸F-FDG PET/CT is useful for differentiating benign and malignant SPNs in patients with IPF, as it is for patients without IPF.

Rare Involvement of Thyroid Cartilage and Thyroid Gland by Multiple Myeloma on 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Multiple myeloma commonly involves the skeleton. Extraosseous disease is sometimes noticed involving various organs. We present a very unusual site of myeloma involvement in the thyroid gland and thyroid cartilage.

Bladder Leiomyoma: A Rare Differential and a Potential Pitfall in the Evaluation for a Bladder Mass in 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography

¹⁸F-Fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸FDG PET/CT) has shown an increasing role in the evaluation of urinary bladder cancer, though benign pathological processes of the urinary bladder can also result in increased FDG uptake. Leiomyomas of urinary bladder are benign mesenchymal neoplasms and a very rare bladder tumor comprising <0.5% of all bladder tumors. Here, we present the low-grade ¹⁸FDG uptake in urinary bladder leiomyoma on PET/CT done for the clinical suspicion of bladder cancer, which can be a rare differential for bladder carcinoma.

18F-fluorodeoxyglucose imaging of primary malignant pericardial mesothelioma with concurrent pericardial and pleural effusions and bone metastasis: A case report

Primary malignant pericardial mesothelioma (PMPM) is an aggressive tumor that originates from the mesothelial cells of the pericardium. PMPM with extensive atrial infiltration and bone metastasis is extremely rare. The diagnosis and staging of PMPM based on anatomical imaging may be difficult when concurrent pericardial and pleural effusions are present. A 28-year-old man presented with progressive chest pain. Concurrent pericardial and pleural effusions were identified on computed tomography. On echocardiography, mild thickening and adhesions of the pericardium with the right ventricle and atrium were observed. ¹⁸F-fluorodeoxyglucose (FDG) metabolism imaging revealed increased accumulation in the pericardium and adjacent right atrium. Ring-shaped radioactivity aggregation and bone destruction in the sacrum were demonstrated on ¹⁸F-FDG and ^99mTc-methyl diphosphonate imaging. The diagnosis of PMPM was subsequently confirmed by pathology. The patient survived for >1.5 years with comprehensive treatment.

Risk-related 18F-FDG PET/CT and new diagnostic strategies in patients with solitary pulmonary nodule: the ITALIAN multicenter trial

PURPOSE

Diagnosis of solitary pulmonary nodule (SPN) is an important public health issue and ¹⁸F-FDG PET/CT has proven to be more effective than CT alone. Pre-test risk stratification and clinical presentation of SPN could affect the diagnostic strategy. A relevant issue is whether thoracic segmental (s)-PET/CT could be implemented in patients with SPN. This retrospective multicenter study compared the results of FDG whole-body (wb)-PET/CT to those of s-PET/CT.

METHODS

¹⁸F-FDG PET/CT of 502 patients, stratified for pre-test cancer risk, were retrospectively analyzed. The thoracic part of wb-PET/CT, considered s-PET/CT, was compared to wb-PET/CT. Clinical and PET/CT variables were investigated for SPN characterization as well as for identification of patients in whom s-PET/CT could be performed. Histopathology or follow-up data were used as a reference.

RESULTS

In the study population, 36% had malignant, 35% benign, and 29% indeterminate SPN. ¹⁸F-FDG uptake indicative of thoracic and extra-thoracic lesions was detectable in 13% and 3% of the patients. All patients with extra-thoracic metastases (n = 13) had thoracic lymph node involvement and highest ¹⁸F-FDG uptake at level of SPN (negative predictive value 100%). Compared to wb-PET/CT, s-PET/CT could save about 2/3 of ¹⁸F-FDG dose, radiation exposure or scan-time, without affecting the clinical impact of PET/CT.

CONCLUSION

Pre-test probability of malignancy can guide the diagnostic strategy of ¹⁸FDG-PET/CT in patients with SPN. In subjects with low-intermediate pretest probability s-PET/CT imaging might be planned in advance, while in those at high risk and with thoracic lymph node involvement a wb-PET/CT is necessary.

Diagnostic value of using 18F-FDG PET and PET/CT in immunocompetent patients with primary central nervous system lymphoma: A systematic review and meta-analysis

BACKGROUND

18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and PET/CT have become two of the most powerful tools for malignant lymphoma exploration, but their diagnostic role in primary central nervous system lymphoma (PCNSL) is still disputed. The purpose of our study is to identify the usefulness of 18F-FDG PET and PET/CT for detecting PCNSL.

RESULTS

A total of 129 patients, obtained from eight eligible studies, were included for this systematic review and meta-analysis. The performance of 18F-FDG PET and PET/CT for diagnosing PCNSL were as follows: the pooled sensitivity was 0.88 (95% CI: 0.80-0.94), specificity was 0.86 (95% CI: 0.73-0.94), positive likelihood ratio (PLR) was 3.99 (95% CI: 2.31-6.90), negative likelihood ratio (NLR) was 0.11 (95% CI: 0.04-0.32), and diagnostic odds ratio (DOR) was 33.40 (95% CI: 10.40-107.3). In addition, the area under the curve (AUC) and Q index were 0.9192 and 0.8525, respectively.

MATERIALS AND METHODS

PubMed/MEDLINE, Embase and Cochrane Library were systematically searched for potential publications (last updated on July 16th, 2016). Reference lists of included articles were also checked. Original articles that reported data on patients who were suspected of having PCNSL were considered suitable for inclusion. The sensitivities and specificities of 18F-FDG PET and PET/CT in each study were evaluated. The Stata software and Meta-Disc software were employed in the process of data analysis.

CONCLUSIONS

18F-FDG PET and PET/CT showed considerable accuracy in identifying PCNSL in immunocompetent patients and could be a valuable radiological diagnostic tool for PCNSL.

Trails on 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Leading to Diagnosis of Testicular Adrenal Rest Tumor

Testicular adrenal rest tumors (TARTs) are secondary to hypertrophy of adrenal rest cells in the rete testis in settings of hypersecretion of androgens. We present a case of congenital adrenal hyperplasia with TART with clues to the diagnosis on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT). To the best of our knowledge, this is the first reported case on the role of ¹⁸F-FDG PET/CT in TART.

The Role of 18F-FDG PET/CT and PET/MRI in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a difficult disease to treat and continues to portend a poor prognosis, as most patients are unresectable at diagnosis. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with CT (PET/CT) has been a cornerstone in oncological imaging of different cancers; however, the role of PET/CT in PDAC is continually evolving and currently not well established. Studies have shown the potential of PET/CT in guiding the management of patients with PDAC, with possible added benefit over anatomic imaging with CT or MRI in certain scenarios. PET/CT may be useful in diagnosis, initial staging, treatment response assessment, differentiation of recurrent tumor from post-treatment fibrosis, and radiotherapy planning. Additionally, PET/CT may be a cost-effective modality due to upstaging of patients originally deemed as surgical candidates. Recently, the advent of simultaneous PET/MRI represents an exciting advancement in hybrid functional imaging with potential applications in the imaging of PDAC. The advantages of PET/MRI include simultaneous acquisition to improve registration of fusion images, lower radiation dose, superior soft tissue contrast, and availability of multiparametric imaging. Studies are underway to evaluate the utility of PET/MRI in PDAC, including in initial staging and treatment response assessment and to determine the subgroup of patients that will benefit from PET/MRI. Further studies are warranted in both PET/CR and PET/MRI to better understand the role of these modalities in PDAC.

Relationship between collateral circulation and myocardial viability of 18F-FDG PET/CT subtended by chronic total occluded coronary arteries

OBJECTIVE

To analyze the relationship between the collateral flow of coronary chronic total occlusion (CTO) and myocardial viability detected by ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging.

METHODS

A prospective analysis of 104 patients diagnosed by coronary angiography. All patients underwent resting myocardial perfusion imaging and PET/CT within 1 week. The collateral circulation was graded with Rentrop classification as no or poor collateral circulation in 16 CTO vessels, moderate collateral circulation in 34 CTO vessels, and good collateral circulation in 69 CTO vessels. Myocardial viability was determined with myocardial perfusion imaging and PET. The patterns were interpreted as mismatch, match and normal perfusion and ¹⁸F-FDG uptake.

RESULTS

There was no significant correlation between the severity and extent of perfusion defect, myocardial viability and collateral circulation grade. The myocardial viability was normal in mild and moderate hypokinetic regions and decreased in severe hypokinetic and akinesis-dyskinesis regions. The presence of collateral circulation was a sensitive (89%) but not a specific (31%) sign of myocardial viability.

CONCLUSIONS

In patients with CTO, collateral circulation does not seem to be an effective way for predicting myocardial viability. Further analysis of PET patterns of viable myocardium is needed to guide further revascularization and predict functional improvement and survival benefit.

Prognostic value of pre- and post-transplantation 18F-fluorodeoxyglucose positron emission tomography results in non-Hodgkin lymphoma patients receiving autologous stem cell transplantation

Objective

High-dose chemotherapy (HDC) followed by autologous stem cell transplantation (ASCT) is the standard of care in the upfront or relapsed/refractory setting in some patients with non-Hodgkin lymphoma (NHL). However, a proportion of patients do not respond to ASCT. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been widely used for staging, response evaluation, and prognosis prediction. Here, we investigated the prognostic role of PET/CT in NHL patients before and after ASCT.

Methods

A retrospective study was conducted at Peking University Cancer Hospital. All NHL patients who underwent ASCT between March 2010 and July 2016 were identified. Patients who had PET/CT scan before and after ASCT were included. Deauville criteria (5-point scale) were used to interpret PET scans. Univariate and multivariate survival analyses were performed using Cox regression. The predictive value of PET scanning was estimated by comparing the area under the receiver operating characteristic (ROC) curve.

Results

In total, 79 patients were enrolled in this study. In univariate analysis, pre- and post-ASCT PET result was identified as prognostic factors for 3-year progression-free survival (PFS) and overall survival (OS). Patients with negative pre-ASCT PET result demonstrated significantly better PFS (84.2% vs. 54.2%) and OS (89.2% vs. 63.6%) than patients with positive pre-ASCT PET result. PFS (91.6% vs. 25.3%) and OS (96.5% vs. 36.8%) were also significantly different between patients with negative and positive post-ASCT PET result. Multivariate analysis also showed a significant association between survival and post-ASCT PET result. ROC analysis revealed that the predictive value of post-ASCT PET result was superior to that of pre-ASCT PET result alone. Combined pre- and post-ASCT PET result is better for predicting outcomes in patients with NHL receiving transplantation. Deauville criteria score >3 was identified as the best cutoff value for post-ASCT PET.

Conclusions

Post-ASCT PET result was more important than pre-ASCT PET result in predicting outcomes for NHL patients who underwent ASCT. The prognostic significance can be improved when combining pre-ASCT PET result with post-ASCT PET result. Deauville criteria can be used for interpreting PET scans in this scenario.

18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Imaging of Inferior Vena Cava Tumor Thrombus Extending into the Right Atrium in a Patient with Cholangiocarcinoma Treated with 90Y-Microspheres

We present a case of a 42-year-old male patient affected by unresectable, chemorefractory cholangiocarcinoma, with prior placement of biliary stent. Because of the absence of extrahepatic metastases, he was submitted to liver-direct therapy with ⁹⁰Y-microspheres. ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) performed before the procedure showed intense tracer uptake in the hepatic lesion and along the biliary stent. The patient underwent radioembolization with ⁹⁰Y-resin spheres (1.1 GBq). ¹⁸F-FDG PET-CT, acquired 6 weeks after the procedure, showed no response of the hepatic lesion and the appearance of an area of markedly increased uptake extending through the inferior vena cava into the right atrium, confirmed as extensive tumor thrombus at the enhanced multislice CT subsequently performed. ¹⁸F-FDG PET-CT proved to be a useful imaging tool not only for the evaluation of metabolic response but also for the early detection of extrahepatic progression after 90Y-radioembolization.

18F-fluorodeoxyglucose uptake predicts MET expression in lung adenocarcinoma

Objective

MET is a member of the receptor tyrosine kinases. Several MET-targeting inhibitors and antagonistic antibodies have shown promising data in clinical trials of lung adenocarcinoma. Finding noninvasive diagnostic tools to estimate the status of MET is helpful in clinical practice. ¹⁸F-fluorodeoxyglucose positron emission tomography/computerized tomography (¹⁸F-FDG PET/CT) has been used routinely for the diagnosis and staging of tumors. However, the relationship between MET expression and ¹⁸F-FDG uptake has not been investigated yet. This study aimed to determine the correlation of MET expression with ¹⁸F-FDG uptake on PET-CT scan and whether or not ¹⁸F-FDG PET/CT can be used to predict the MET status of lung adenocarcinoma patients.

Patients and methods

Fifty-seven lung adenocarcinoma patients were analyzed in our study. Maximum standardized uptake value (SUV_max) was calculated in all PET/CT images. The expression levels of MET and two important glycolysis-related markers, glucose transporter 1 (GLUT1) and pyruvate kinase M2, were analyzed by immunohistochemistry of tissues. Spearman rank correlation was used to analyze the association between MET expression and SUV_max. In vitro MET knockdown in lung adenocarcinoma cells was used to examine the role of MET in tumor metabolism. The effect of MET on GLUT1 expression was investigated using Western blot assay and quantitative polymerase chain reaction.

Results

SUV_max was positively correlated with the expression levels of MET (r=0.458; P<0.001) and GLUT1 (r=0.551; P<0.001). SUV_max was significantly higher in patients with positive MET expression than in those with negative MET expression (9.92±6.62 vs 4.60±3.00; P=0.002). MET knockdown in lung adenocarcinoma cells led to a significant decrease in GLUT1 expression and ¹⁸F-FDG uptake.

Conclusion

MET could increase ¹⁸F-FDG uptake by upregulating GLUT1 expression. ¹⁸F-FDG PET/CT could be used to predict the MET status of lung adenocarcinoma patients and to supply valuable information to guide targeted therapy.

Application of positron emission tomography-computed tomography in the diagnosis of pulmonary ground-glass nodules

The aim of the present study was to investigate the value of positron emission tomography-computed tomography (PET-CT) using ¹⁸F-fluorodeoxyglucose in the clinical diagnosis of pulmonary ground-glass nodule. In total, 54 patients with pulmonary GGN that were identified by PET-CT examination were selected and confirmed by pathology and clinical diagnosis in hospital between April 2014 and April 2015. The association between PET-CT findings and pathology, and the value of PET-CT were then evaluated. In the 54 patients, solitary pulmonary GGN with a nodule diameter of between 0.6 and 2.0 cm were detected. Amongst them, the PET-CT examination of 42 patients revealed hyper metabolic nodules, and were all mixed GGN type nodules with a diameter >1 cm. The PET-CT examination of the remaining 12 patients demonstrated no evidence of metabolic abnormalities and the nodules in these patients were pure or mixed GGN with a diameter <1 cm (except 2 cases with a diameter ≥1 cm). Furthermore, the diagnoses for all patients were pathologically confirmed by CT-guided needle biopsy or thoracoscopic surgical resection. Amongst them, there were 41 cases of lung adenocarcinoma, 4 cases of fungal infection, 7 cases of inflammation and 2 cases of adenomatoid hyperplasia. Additionally, PET-CT has a lower detection rate for smaller GGN exhibits no clear advantage for pure GGN, but has a higher detection rate for larger GGN. In conclusion, to a certain extent, PET-CT makes up for the shortcomings of traditional imaging and has some clinical value for the diagnosis of GGN.

Diagnostic and Prognostic Significance of Methionine Uptake and Methionine Positron Emission Tomography Imaging in Gliomas

The present most common image diagnostic tracer in clinical practice for glioma is ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for brain tumors diagnosis and prognosis. PET is a promising molecular imaging technique, which provides real-time information on the metabolic behavior of the tracer. The diffusive nature of glioblastoma (GBM) and heterogeneity often make the radiographic detection by FDG-PET inaccurate, and there is no gold standard. FDG-PET often leads to several controversies in making clinical decisions due to their uptake by normal surrounding tissues, and pose a challenge in delineating treatment-induced necrosis, edema, inflammation, and pseudoprogression. Thus, it is imperative to find new criteria independent of conventional morphological diagnosis to demarcate normal and tumor tissues. We have provided proof of concept studies for ¹¹C methionine-PET (MET-PET) imaging of gliomas, along with prognostic and diagnostic significance. MET-PET is not widely used in the United States, though clinical trials from Japan and Germany suggesting the diagnostic ability of MET-PET imaging are superior to FDG-PET imaging for brain tumors. A major impediment is the availability of the onsite cyclotron and isotopic carbon chemistry facilities. In this article, we have provided the scientific rationale and advantages of the use of MET-PET as GBM tracers. We extend our discussion on the expected pitfalls of using MET-PET and ways to overcome them by incorporating a translational component of profiling gene status in the methionine metabolic pathway. This translational correlative component to the MET-PET clinical trials can lead to a better understanding of the existing controversies and can enhance our knowledge for future randomization of GBM patients based on their tumor gene signatures to achieve better prognosis and treatment outcome.

Current Methods to Define Metabolic Tumor Volume in Positron Emission Tomography: Which One is Better?

Numerous methods to segment tumors using ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) have been introduced. Metabolic tumor volume (MTV) refers to the metabolically active volume of the tumor segmented using FDG PET, and has been shown to be useful in predicting patient outcome and in assessing treatment response. Also, tumor segmentation using FDG PET has useful applications in radiotherapy treatment planning. Despite extensive research on MTV showing promising results, MTV is not used in standard clinical practice yet, mainly because there is no consensus on the optimal method to segment tumors in FDG PET images. In this review, we discuss currently available methods to measure MTV using FDG PET, and assess the advantages and disadvantages of the methods.

Primary malignant lymphoma of the talus: A case report and review of the literature

Malignant lymphoma commonly occurs in adults, with a peak incidence between the seventh and ninth decades of life. Although malignant lymphoma usually occurs in the lymph nodes, it rarely occurs primarily in the bone. We herein describe an extremely rare case of primary malignant lymphoma of the talus in a 74-year-old man. Although plain radiographs showed no abnormality, gadolinium-enhanced magnetic resonance imaging (MRI) revealed a well-circumscribed intra- and extraosseous tumor of the talus. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/MRI revealed a marked increase of FDG uptake in the right ankle and the right inguinal lymph nodes. As the tumor was diagnosed as diffuse large B-cell lymphoma by core needle biopsy, combination therapy with chemo- and radiotherapy was initiated. The patient achieved complete remission, with no sign of recurrence at 8 months after initial chemoradiotherapy. Since primary malignant lymphoma of the bone is chemo- and radiosensitive and has a good prognosis, accurate staging by radiological investigation as well as correct pathological diagnosis by biopsy are required for optimal treatment.

Usefulness of esophagogastroduodenoscopy and 18F-fluorodeoxyglucose positron-emission tomography in detecting synchronous multiple primary cancers with oral cancer

PURPOSE

The purpose of this study is to compare the value of screening for synchronous multiple primary cancers in other organs by esophagogastroduodenoscopy (EGD) or ¹⁸F-fluorodeoxyglucose positron-emission tomography (PET-CT) in patients newly diagnosed with oral cancer.

METHODS

We retrospectively examined consecutive Japanese patients who were diagnosed with oral squamous cell carcinoma (OSCC) and were screened for synchronous multiple primary cancers in other organs by EGD and/or PET-CT between January 2010 and December 2015 at our institution. The study included 190 patients (106 males and 84 females) from 36 to 93 years of age (median age 68.8 years). The patients were screened by EGD, PET-CT, or both before beginning treatment for OSCC.

RESULTS

Of 190 Japanese patients with OSCC, 15 had multiple primary cancers: 13 patients had double cancer and two had triple cancers. The sites of the 17 multiple primary cancers were gastric (6), esophageal (4), and lung (3), and ovarian, colon, liver, and thyroid (1 each). All of the gastric and esophageal cancers were found by EGD and were not detected by PET-CT. For three patients, the detection of multiple cancers affected the treatment modality or order of treatment selected for the OSCC. In two cases, the oral cancer and multiple primary cancer(s) in another organ were resected simultaneously by joint surgical teams.

CONCLUSIONS

PET-CT for oral cancer patients is an effective supporting diagnostic tool. However, the ability of PET-CT has some limitations. Especially for early detection of the upper gastrointestinal cancers, it is necessary to be supplemented by EGD.

The high matrix acquisition technique for imaging of atherosclerotic plaque inflammation in fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography with time-of-flight: Phantom study

BACKGROUND

Motion artifact and partial volume effect caused underestimation of coronary plaque inflammation. This study evaluated the high matrix acquisition technique using time-of-flight (TOF) positron emission tomography/computed tomography for imaging of atherosclerotic plaque inflammation with fluorine-18 fluorodeoxyglucose in small and moving phantoms.

METHODS AND RESULTS

All images were reconstructed using a conventional algorithm without TOF (4 × 4 × 4 mm3 voxel size) and a high matrix algorithm with TOF (2 × 2 × 2 mm3 voxel size). Microsphere phantoms of 10, 7.9, 6.2, 5.0, and 4.0 mm diameters were acquired in 3-dimensional list-mode for 30 minutes. A heart phantom mimicking cardiac motion consisted of a hot spot simulating a plaque (φ 4 mm, φ 2 mm) on the outside of the left ventricle. In the microsphere and heart phantom study, visual discrimination, maximum activity, and target-to-background ratio using the high matrix algorithm with TOF were better than those using the conventional algorithm without TOF.

CONCLUSION

The high matrix algorithm with TOF improves detection of small targets in phantoms.

Malignancy rate of focal thyroid incidentaloma detected by FDG PET-CT: results of a prospective cohort study

OBJECTIVE

To evaluate the malignancy rate of focal thyroid incidentaloma (fTI) in a population of patients undergoing a 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) for a non-thyroid purpose.

DESIGN

We conducted a prospective cohort study from January 2013 to November 2014. All consecutive patients referred for a FDG PET-CT were prospectively screened. Patients with known neoplastic thyroid disease were excluded from the analysis. All patients presenting one or more fTI and who accepted to benefit from a complementary thyroid ultrasonography (US) were included and managed according to the French endocrine society consensus. Prevalence of fTI in our population and malignancy rate was assessed.

RESULTS

During the inclusion period, 10,171 patients were referred for a FDG PET-CT in our center. Fifty-three patients presenting a known thyroid disease were excluded. Among the remaining 10,118 patients, 127 (1.3%) with 131 fTI were individualized. US could not be performed in 37 patients. The remaining 90 patients (92 fTI) were explored by US ± fine-needle aspiration biopsy (FNAB). US results demonstrated a nodule aspect in 80 cases of which 60 benefited from FNAB. Nineteen of 92 fTI underwent surgery with 10 malignant lesions among the 60 patients performing both US and FNAB.

CONCLUSION

The prevalence of fTI discovered on FDG PET-CT in our population was 1.3% with 10 malignant lesions among the 60 patients performing both US and FNAB.

Functional assessment of prefrontal lobes in patients with major depression disorder using a dual-mode technique of 3D-arterial spin labeling and 18F-fluorodeoxyglucose positron emission tomography/computed tomography

The aim of this study was to explore the functions of cerebral blood perfusion and glucose metabolism in the prefrontal lobe of patients with major depression disorder (MDD), and to analyze the correlations between these functional changes and depressive symptoms. 3D-arterial spin labeling (ASL) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) were successfully performed in 17 patients with MDD and 16 healthy controls in a resting state. The depressive symptoms of the patients were classified into seven factors and scored with the Hamilton Depression Rating Scale. Regional cerebral blood flow (CBF) values and standardized uptake values (SUV) of ¹⁸F-FDG in the whole brain were respectively compared between the patients and healthy controls using a two-sample t-test, and the correlations between the CBF and SUV in the prefrontal cerebral regions with the patients' Hamilton scores were evaluated using Pearson correlation analysis. Decreased regional CBF was indicated in the bilateral middle and the right superior frontal gyri, and decreased regional SUV was indicated in the bilateral superior, middle and inferior frontal gyri in the MDD patients compared with the controls. Positive correlations were observed between CBF values and aggregate Hamilton scores in the left middle and right middle frontal gyri of the patients. Positive correlations were also observed between SUVs and aggregate Hamilton scores in the left middle and right middle frontal gyri. ¹⁸F-FDG PET/CT was indicated to be more sensitive than 3D-ASL in identifying the functional abnormalities in the prefrontal lobe. Decreased CBF and SUV in the prefrontal lobe were closely correlated with Hamilton score. The left middle frontal gyrus may be a key functional region in MDD.

[Comparison of early response to combined chemotherapy gemcitabine-cisplatin in non-small cell lung cancer animal model between using 18F-fluorodeoxyglucose and 18F-fluorothymidine]

Non-small cell lung cancer (NSCLC) accounts for more than 80% of lung cancer. Nowadays, gemcitabine and cisplatin in combination have been adopted as the first-line chemotherapy for patients with NSCLC. This study aimed to monitor early response to combined chemotherapy of gemcitabine plus cisplatin in a mouse model of NSCLC by using ¹⁸F-fluorodeoxyglucose and ¹⁸F-fluorothymidine small animal positron emission tomography (PET). Lewis lung carcinoma-bearing C57BL/6 mice were treated with gemcitabine-cisplatin or saline. Small animal PET with ¹⁸F-FDG and ¹⁸F-FLT was performed before (baseline) and after treatment (on Day 3), respectively. Imaging results were confirmed by histopathological studies (hematoxylin and eosin staining, Ki67 staining). Compared to the results in the control group, gemcitabine-cisplatin in the treated group significantly inhibited tumor growth ( P<0.05). In the treated group, the maximum standardized uptake value (SUVmax) of ¹⁸F-FLT decreased significantly from 0.59±0.05 (baseline) to 0.28±0.05 (Day 3) ( P<0.05). There was no significant difference between baseline (4.35±0.46) and that on Day 3 (4.02±0.47) on ¹⁸F-FDG SUVmax ( P>0.05). The proliferation of tumor assessed by Ki67 staining decreased significantly after treatment of one dose of gemicitabine-cisplatin ( P<0.05). The staining of HE showed an increase in necrotic and inflam- matory cells after the treatment. This study demonstrated that the uptake of ¹⁸F-FLT reduced more rapidly and signi-ficantly than that of ¹⁸F-FDG and was less disturbed by the increase of inflammatory cells after chemotherapy.