Background Intestinal 18F-FDG Uptake Is Related to Serum Lipid Profile and Obesity in Breast Cancer Patients

Synthesis and biological evaluation of a 68Ga-labeled glucose derivative PET probe [68Ga]Ga-NOTA-SDG

PURPOSE

Currently, 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) has been widely used in clinical diagnostics for tumors. However, its application is hindered by several limitations, including low tumor specificity, the need for accelerator production of 18F, and complex synthesis procedures. In this study, a 68Ga-labeled glucose derivative PET molecular probe, [68Ga]Ga-NOTA-SDG, was designed to overcome these issues with the advantages of 68Ga-labeled radiotracers.

METHODS

The radiolabeling precursor NOTA-SDG was designed to conjugate the targeting group D-glucose and the chelator NOTA with a propargylglycine linker. [68Ga]Ga-NOTA-SDG was obtained by incubation of 68Ga3+ and the precursor NOTA-SDG at 37 °C for 15 min. The in vitro stability of [68Ga]Ga-NOTA-SDG in PBS and mouse serum was studied using high-performance liquid chromatography with a radioactivity detector. The uptake mechanism of [68Ga]Ga-NOTA-SDG entry into U87 and A549 cells was investigated by co-incubation the radiotracer with different doses of D-glucose and insulin. PET imaging studies in mice bearing various tumors were performed to evaluate the in vivo tumor diagnostic capability of [68Ga]Ga-NOTA-SDG.

RESULTS

[68Ga]Ga-NOTA-SDG was obtained rapidly within 15 min with radiochemical yield (RCY) of ≥98 % and radiochemical purity (RCP) of ≥99 %. The probe exhibited high stability in mouse serum and PBS over a period of 2 h. Cellular uptake studies demonstrated that the entry of [68Ga]Ga-NOTA-SDG into tumor cells was mediated by glucose transporters, although the mechanism differs from that of D-glucose. PET imaging results indicated that [68Ga]Ga-NOTA-SDG showed high uptake in a variety of tumors (U87, A549, PC3 and A375), enabling clear visualization of the tumors. Moreover, it had lower uptake in non-target tissues compared with [18F]FDG.

CONCLUSIONS

[68Ga]Ga-NOTA-SDG has the potential to serve as a broad-spectrum PET imaging agent for clinical tumor diagnosis.

The Relationship among Bowel [18]F-FDG PET Uptake, Pathological Complete Response, and Eating Habits in Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy

Recently, the impact of patients’ eating habits on both breast cancer (BC) management and inflammation have been proven. Here, we investigated whether inflammatory habits could correlate with baseline bowel [18]F-fluorodeoxyglucose (FDG) uptake and the latter, in turn, with pathological Complete Response (pCR) to neoadjuvant chemotherapy (NAC). We included stage I−III BC undergoing standard NAC at IRCCS Humanitas Research Hospital, Italy. Patients fulfilled a survey concerning eating/lifestyle behaviors and performed a staging [18]F-FDG positrone emission tomography/computed tomography (PET/CT). In the absence of data on the effects of individual foods, we aggregated drink and food intake for their known inflammatory properties. Data were recorded for 82 women (median age, 48). We found positive correlations between colon mean standardized uptake value (SUVmean) and pro-inflammatory drinks (alcohol and spirits; r = +0.33, p < 0.01) and foods (red and cured meats; r = +0.25, p = 0.04), and a significant negative correlation between rectum SUVmean and anti-inflammatory foods (fruits and vegetables; r = −0.23, p = 0.04). Furthermore, colon SUVmean was significantly lower in patients with pCR compared to non pCR (p = 0.02). Our study showed, for the first time, that patients’ eating habits affected bowel [18]F-FDG uptake and that colon SUVmean correlated with pCR, suggesting that PET scan could be an instrument for identifying patients presenting unhealthy behaviors.

Effect of Diet on Physiologic Bowel 18F-FDG Uptake

Intestinal ¹⁸F-FDG uptake is variable in whole-body PET/CT. In cancer patients, particularly those suspected of relapse or metastasis, ¹⁸F-FDG absorption might interfere with scan interpretation. This study evaluated the effect of diet on intestinal ¹⁸F-FDG absorption. Methods: In total, 214 patients referring for oncologic ¹⁸F-FDG PET/CT participated. They were randomly divided into 2 groups and asked to follow either a routine diet (RD) or a low-carbohydrate, high-fat diet (LCHFD) for 24 h before the study. The small bowel and different parts of the colon (the cecum; the ascending, transverse, and descending segments; and the hepatic and splenic flexures) were evaluated and visually interpreted by nuclear medicine experts. Bowel uptake was graded through comparison with that in the liver as absent, mild, moderate, or severe. Results: Significantly higher ¹⁸F-FDG uptake in the descending colon (P = 0.001) and small intestine (P = 0.01) was observed in the RD group than in the LCHFD group. After patients with bowel cancer were omitted from the statistical analysis, no significant differences in the final results were seen. Conclusion: An LCHFD for 24 h before ¹⁸F-FDG PET imaging resulted in lower ¹⁸F-FDG uptake in the descending colon and small bowel than did an RD, assisting the interpreting physician by reducing the intestinal activity interference for more accurate diagnostic interpretation.

The role of cardiac magnetic resonance imaging in the detection and monitoring of cardiotoxicity in patients with breast cancer after treatment: a comprehensive review

The use of chemotherapy medicines for breast cancer (BC) has been associated with an increased risk of cardiotoxicity. In recent years, there have been growing interests regarding the application of cardiovascular magnetic resonance (CMR) imaging, a safe and noninvasive modality, with the potential to identify subtle morphological and functional changes in the myocardium. In this investigation, we aimed to review the performance of various CMR methods in diagnosing cardiotoxicity in BC, induced by chemotherapy or radiotherapy. For this purpose, we reviewed the literature available in PubMed, MEDLINE, Cochrane, Google Scholar, and Scopus databases. Our literature review showed that CMR is a valuable modality for identifying and predicting subclinical cardiotoxicity induced by chemotherapy. The novel T1, T2, and extracellular volume mapping techniques may provide critical information about cardiotoxicity, in addition to other CMR features such as functional and structural changes. However, further research is needed to verify the exact role of these methods in identifying cardiotoxicity and patient management. Since multiple studies have reported the improvement of left ventricular performance following the termination of chemotherapy regimens, CMR remains an essential imaging tool for the prediction of cardiotoxicity and, consequently, decreases the mortality rate of BC due to heart failure.

Physiologic intestinal 18F-FDG uptake is associated with alteration of gut microbiota and proinflammatory cytokine levels in breast cancer

The clinical significance of physiologic Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) intestinal uptake (IU) based on the predicted link with gut microbiota dysbiosis and inflammatory cytokine production was investigated in a cohort of breast cancer patients. A total of 114 patients were visually classified into the lower or higher IU group. The maximum and mean standardized uptake values of total bowel (TB SUV_max and TB SUV_mean) were measured. The gut microbial abundance of the Citrobacter genus of the Enterobacteriaceae family showed a significant positive correlation with TB SUV_max and TB SUV_mean (q = 0.021 and q = 0.010). The unclassified Ruminococcaceae showed a significant negative correlation with TB SUV_max (q = 0.010). The level of tumor necrosis factor alpha (TNF-α) was significantly increased in the high IU group (p = 0.017). The TNF-α levels showed a significant positive correlation with TB SUV_max (rho = 0.220 and p = 0.018) and TB SUV_mean (rho = 0.250 and p = 0.007). Therefore, our findings suggest that the physiologic intestinal uptake may reflect subclinical inflammation and differences in the composition of the gut microbiome in breast cancer patients.

Gut microbiota and physiologic bowel 18F-FDG uptake

Background

We investigated the association between physiologic bowel FDG uptake and gut microbiota. FDG uptake in the normal large and small intestine is widely variable both in distribution and intensity. The etiology of physiologic bowel ¹⁸F-FDG activity remains unknown.

Results

We included 63 healthy male subjects. After overnight fasting, blood samples and ¹⁸F-FDG PET/CT scans were taken. Fecal samples were collected, and gut microbiota were analyzed by 16S rRNA gene-pyrosequencing. The physiologic bowel FDG uptake was classified into three groups by visual assessment and measured using the maximum and mean standardized uptake value. We used the total bowel to liver uptake ratio (TBR_max and TBR_mean). There was no significant difference in age, BMI, or lipid profiles between groups. To identify specific microbial taxa associated with the bowel FDG uptake while accounting for age and BMI, we performed a generalized linear model. At the genus level, the group with focal or intense FDG uptake in the intestine was associated with low abundance of unclassified Clostridiales. The group with intestinal FDG uptake lower than the liver was associated with high abundance of Klebsiella. TBR_max and TBR_mean were negatively associated with abundance of unclassified Enterobacteriaceae.

Conclusion

We cautiously speculate that physiologic bowel FDG activity might be caused by an increase in intestinal permeability and may reflect an impaired barrier function in the intestine.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-017-0318-8) contains supplementary material, which is available to authorized users.

Glucose metabolism of visceral adipose tissue measured by 18F-FDG PET/CT is related to the presence of colonic adenoma

This study investigated the relationships between the area and metabolic activity of adipose tissue and the presence of colorectal adenoma (CRA). Our institutional review board approved the study and waived informed consent. A total of 212 subjects who underwent fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and colonoscopy for routine health check-ups were enrolled. The volumetric parameters of areas of visceral (VATav), subcutaneous (SATav), and total adipose tissue (TATav) and calculated visceral-to-subcutaneous adipose tissue ratio (VSR) and visceral-to-total adipose tissue ratio (VAR) were considered. Metabolic parameters of standardized uptake value (SUV) of visceral (vcSUVmax, vcSUVmean), subcutaneous (scSUVmax, scSUVmean), and calculated visceral-to-subcutaneous adipose tissue ratio (VSRmax, VSRmean) were considered. Anthropometric data of height, weight, body mass index (BMI), waist circumference (WC), body fat mass (BFM), skeletal muscle mass (SMM), and diverse laboratory data were also considered as variables. Sixty-six subjects were placed in the CRA group and 146 subjects in the non-CRA group. The presence of CRA was significantly correlated with older age (P  =  .001), male sex (P  =  .041), higher BMI (P  =  .004), higher WC (P  =  .001), higher BFM (P  =  .024), higher VATav (P < .001), higher TATav (P  =  .004), higher VSR (P < .001), higher VAR (P < .001), lower vcSUVmax (P  =  .002), lower vcSUVmean (P < .001), and lower VSRmean (P  =  .002). On multiple regression analysis, vcSUVmax and vcSUVmean were independently associated with the presence of CRA (P  =  .009 and P  =  .045). Lower glucose metabolism of visceral adipose tissue was related to the presence of CRA. Our findings identify the value of visceral metabolic dysfunction as a potential surrogate marker of elevated risk for CRA.

Background Colonic 18F-Fluoro-2-Deoxy-D-Glucose Uptake on Positron Emission Tomography Is Associated with the Presence of Colorectal Adenoma

¹⁸F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) scan is used to evaluate various kinds of tumors. While most studies on PET findings of the colon focus on the colonic uptake pattern, studies regarding background colonic uptake on PET scan are rare. The purpose of this study was to identify the association between the background colonic uptake and the presence of colorectal adenoma (CRA), which is a frequent precancerous lesion. We retrospectively reviewed the medical records of 241 patients with gynecologic malignancy who had received PET or PET/computed tomography (CT) scan and colonoscopy at the same period as a baseline evaluation. Background colonic ¹⁸F-FDG uptake was visually graded and the maximal standardized uptake values (SUV_max) of 7 different bowel segments were averaged. In univariate analysis, older age at diagnosis (≥ 50 years, p = 0.034), overweight (BMI ≥ 23 kg/m², p = 0.010), hypercholesterolemia (≥ 200 mg/dL, p = 0.027), and high grade background colonic uptake (p = 0.009) were positively associated with the prevalence of CRA. By multiple logistic regression, high grade background colonic uptake was independently predictive of CRA (odds ratio = 2.25, p = 0.021). The proportion of CRA patients significantly increased as background colonic uptake grade increased from 1 to 4 (trend p = 0.015). Out of the 138 patients who underwent PET/CT, the proportion of CRA patients in the group with high SUV_max (> 2.25) was significantly higher than in the low SUV_max group (27.5% vs. 11.6%, p = 0.031). In conclusion, high grade of background colonic ¹⁸F-FDG uptake is significantly associated with the prevalence of CRA.