Nerve Sheath Tumors in Neurofibromatosis Type 1: Assessment of Whole-Body Metabolic Tumor Burden Using F-18-FDG PET/CT

Purpose

To determine the metabolically active whole-body tumor volume (WB-MTV) on F-18-fluorodeoxyglucose positron emission tomography/computed tomography (F-18-FDG PET/CT) in individuals with neurofibromatosis type 1 (NF1) using a three-dimensional (3D) segmentation and computerized volumetry technique, and to compare PET WB-MTV between patients with benign and malignant peripheral nerve sheath tumors (PNSTs).

Patients and Methods

Thirty-six NF1 patients (18 patients with malignant PNSTs and 18 age- and sex-matched controls with benign PNSTs) were examined by F-18-FDG PET/CT. WB-MTV, whole-body total lesion glycolysis (WB-TLG) and a set of semi-quantitative imaging-based parameters were analyzed both on a per-patient and a per-lesion basis.

Results

On a per-lesion basis, malignant PNSTs demonstrated both a significantly higher MTV and TLG than benign PNSTs (p < 0.0001). On a per-patient basis, WB-MTV and WB-TLG were significantly higher in patients with malignant PNSTs compared to patients with benign PNSTs (p < 0.001). ROC analysis showed that MTV and TLG could be used to differentiate between benign and malignant tumors.

Conclusions

WB-MTV and WB-TLG may identify malignant change and may have the potential to provide a basis for investigating molecular biomarkers that correlate with metabolically active disease manifestations. Further evaluation will determine the potential clinical impact of these PET-based parameters in NF1.     

The utility of 18F-FDG PET/CT in brain tumours diagnosis

BackgroundThe purpose of the study was to discuss whether 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) study protocol should include brain imaging.Materials and methodsAnalysis of international societies recommendations compared with the original data obtained in over 1000 consecutive torso and brain ¹⁸F-FDG PET/CT studies collected in 2010.ResultsAccording to the international societies recommendations, the ¹⁸F-FDG should not be the radiotracer of choice considering the brain region PET/CT study. However, it can be performed as an additional brain imaging tool. Based on at least a 3-year follow-up, we detected 8 cases of suspicious brain findings and no primary lesion among over 1000 consecutive torso and brain 18F-FDG PET/CT scans performed in 2010. However, in 5 out of 8 patients, the brain lesion was the only metastasis detected, affecting further therapy.ConclusionsThe ¹⁸F-FDG PET/CT study may help detect malignant brain lesions and, therefore, including brain region imaging into the study protocol should be considered.     

Giant peritoneal loose body diagnosis by 18F-FDG PET/CT: A case report

An ¹⁸F-FDG PET/CT scan performed in a 70-year-old patient for characterization of a pulmonary nodule revealed a very rare image of a giant loose peritoneal body in this asymptomatic patient. A review of literature is presented. The knowledge of the characteristics of this typical lesion is important to avoid further invasive explorations.     

Diagnostic Accuracy of PET/CT-Guided Percutaneous Biopsies for Malignant Peripheral Nerve Sheath Tumors in Neurofibromatosis Type 1 Patients

Background

Malignant peripheral nerve sheath tumors (MPNST) are one of the most frequent causes of death in patients with neurofibromatosis type 1 (NF1). Early detection is crucial because complete surgical resection is the only curative treatment. It has been previously reported that an ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) image with a T/L (Tumor/Liver) SUV_max ratio > 1.5 provides a high negative predictive value; however, it is not specific enough to make a NF1-related MPNST diagnosis. A formal proof of malignant transformation from a histological analysis is necessary before surgical excision because the procedure can cause mutilation. The objective of the present work was to investigate the effectiveness of and complications associated with PET/CT-guided percutaneous biopsies for an NF1-related MPNST diagnosis.

Methods

PET/CT-guided percutaneous biopsy procedures performed on 26 NF1 patients with a clinical suspicion of MPNST and a suspect lesion from a PET/CT scan (T/L SUV_max ratio > 1.5) were retrospectively evaluated. The localization of the suspected malignant site was determined using PET/CT. A stereotactic (ultrasonic and CT control) core biopsy technique was used with a local anesthesia.

Results

The first PET/CT-guided percutaneous biopsies enabled a pathological diagnosis for all of the patients (no "inconclusive " results were obtained), and no secondary procedures were needed. Among the 26 patients, the histopathological results from the biopsy were malignant in 17 cases and benign (BPNST with atypical cells) in nine cases. No complications from the diagnostic procedure were observed. A surgical resection was performed in 18 patients (seven benign and 11 malignant biopsies), removing the fine needle biopsy scar. In addition, six locally advanced/metastatic MPNST were treated with chemo/radiotherapy, and two BPNST had no progression after a follow-up of 14 and 39 months, respectively. The PET/CT-guided percutaneous biopsy gave 25 accurate diagnoses and one false negative (BPNST with atypical cells on the biopsy and MPNST on the operated tumor), resulting in a diagnostic accuracy rate of 96%. This false negative case may be explained by the high heterogeneity of the tumor: benign areas were contiguous with the malignant ones and associated with inflammation.

Conclusions

PET/CT-guided percutaneous biopsies are an effective and relatively non-traumatic procedure for diagnosis of NF1-related MPNST. It is the most reliable approach for early detection of MPNST.     

Comparison of 68GA-FAPI-04 PET/CT and 18F-FDG PET/CT in detection of metastatic bone disease in various cancers

ObjectiveOur aim in this retrospective study was to compare the diagnostic accuracy of ⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT in detecting bone metastases of various cancers and to evaluate the potential usefulness of ⁶⁸Ga-FAPI-04 PET/CT in detecting metastatic bone disease.Material and methodOur retrospective study included 44 patients diagnosed with bone metastases due to various cancers between January 2021 and February 2022. All patients underwent ⁶⁸Ga-FAPI-04 PET/CT and ¹⁸F-FDG PET/CT imaging within 14 days. In the semi-quantitative analysis of the skeletal system, all regions with higher uptake than background activity were considered pathological. SUVmax and Metastasis-to-background ratio (TBR) values were calculated from metastatic sites.ResultsA total of 827 bone metastases were detected in our study. The diagnostic accuracies of FAPI PET/CT and ¹⁸F-FDG PET/CT were 91.8% and 81.5%, respectively (P < 0.001). When all bone metastases were compared, the SUVmax of ⁶⁸Ga-FAPI-04 PET/CT was statistically significantly higher than that of ¹⁸F-FDG PET/CT (median 6.15 vs. 5.2; P < 0.001). When FDG and FAPI SUVmax values were compared according to metastasis types, FAPI SUVmax and TBR values in osteolytic, medullary and mixed type bone metastases were found to be statistically significantly higher than FDG (P-values: < 0.001, < 0.001, < 0.001, respectively). There was no statistically significant difference between FDG and FAPI SUVmax values in osteoblastic bone metastases (P = 0.26).ConclusionIt has been shown that ⁶⁸Ga-FAPI-04 PET/CT is superior to ¹⁸F-FDG PET/CT in detecting metastatic bone disease and may have more clinical impact on disease management.     

Ovarian Fibroma Mimicking Malignant Tumor on F-18 FDG PET/CT

Benign ovarian tumors like fibroma rarely shows mild or moderate F-18 FDG uptake. FDG-avid adnexial lesions in postmenopausal women should be as considered primarily malignant. A 69 years old female who had diagnosis with both colon adenocarcinoma and lung carcinoma, was referred to F-18 FDG PET/CT imaging for follow up. A mass lesion showing moderate F-18 FDG uptake at right adnexial region was detected. She was operated after gynaecological evaluation. Her histopathology examination was reported as ovarian fibroma.     

The Usefulness of Standardized Uptake Value in Differentiation between Benign and Malignant Thyroid Lesions Detected Incidentally in 18F-FDG PET/CT Examination

Introduction

In the last decade, (18)F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET and PET/CT) has become one of the major diagnostic tools used in oncology. A significant number of patients who undergo this procedure, due to non-thyroidal reasons, present incidental uptake of (¹⁸F-FDG) in the thyroid. The aim of the study was to compare the SUV_max (standardized uptake value) of thyroid focal lesions, which were incidentally found on PET/CT, in relation to the results of thyroid fine-needle aspiration biopsy (FNAB) and/or histopathological evaluation.

Materials and Methods

Patients referred for PET/CT examination, due to non-thyroidal illness, presented focal ¹⁸F-FDG uptake in the thyroid and were advised to undergo ultrasonography (US), hormonal evaluation, FNAB and/or total thyroidectomy at our institution.

Results

6614 PET/CT examinations performed in 5520 patients were analyzed. Of the 122 patients with focal thyroid ¹⁸F-FDG activity, 82 patients (67.2%) underwent further thyroid evaluation using FNAB. Benign lesions were diagnosed in 46 patients, malignant - in 19 patients (confirmed by post-surgical histopathology), while 17 patients had inconclusive results of cytological assessment. Mean SUV_max of benign lesions was 3.2±2.8 (median = 2.4), while the mean SUV_max value for malignant lesions was 7.1±8.2 (median = 3.5). The risk of malignancy was 16.7% for lesions with a SUV_max under 3, 43.8% for lesions with a SUV_max between 3 and 6, and 54.6% for lesions with a SUV_max over 6. In the group of malignant lesions, a positive correlation between the lesion’s diameter and SUV_max was observed (p = 0.03, r = 0.57).

Conclusions

Subjects with incidental focal uptake of ¹⁸F-FDG in thyroid are at a high risk of thyroid malignancy. A high value of SUV_max further increases the risk of malignancy, indicating the necessity for further cytological or histological evaluation. However, as SUV_max correlated with the diameter of malignant lesions, small lesions with focal uptake of ¹⁸F-FDG should be interpreted cautiously.     

Normal SUV Values Measured from NaF18- PET/CT Bone Scan Studies

Objectives

Cancer and metabolic bone diseases can alter the SUV. SUV values have never been measured from healthy skeletons in NaF18-PET/CT bone scans. The primary aim of this study was to measure the SUV values from normal skeletons in NaF18-PET/CT bone scans.

Methods

A retrospective study was carried out involving NaF18- PET/CT bone scans that were done at our institution between January 2010 to May 2012. Our excluding criteria was patients with abnormal real function and patients with past history of cancer and metabolic bone diseases including but not limited to osteoporosis, osteopenia and Paget’s disease. Eleven studies met all the criteria.

Results

The average normal SUV_max values from 11 patients were: cervical vertebrae 6.84 (range 4.38–8.64), thoracic vertebrae 7.36 (range 6.99–7.66), lumbar vertebrae 7.27 (range 7.04–7.72), femoral head 2.22 (range 1.1–4.3), humeral head 1.82 (range 1.2–2.9), mid sternum 5.51 (range 2.6–8.1), parietal bone 1.71 (range 1.3–2.4).

Conclusion

According to our study, various skeletal sites have different normal SUV values. SUV values can be different between the normal bones and bones with tumor or metabolic bone disease. SUV can be used to quantify NaF-18 PET/CT studies. If the SUV values of the normal skeleton are known, they can be used in the characterization of bone lesions and in the assessment of treatment response to bone diseases.     

Preoperative Prediction of Cervical Lymph Node Metastasis Using Primary Tumor SUVmax on 18F-FDG PET/CT in Patients with Papillary Thyroid Carcinoma

Objectives

The aim of the current study was to evaluate the value of preoperative ¹⁸F-FDG (FDG) PET/CT in predicting cervical lymph node (LN) metastasis in patients with papillary thyroid carcinoma (PTC).

Methods

One hundred and ninety-three newly diagnosed PTC patients (M: F = 25:168, age = 46.8 ± 12.2) who had undergone pretreatment FDG PET/CT and had neck node dissection were included in this study. The FDG avidity of the primary tumor and the SUVmax of the primary tumor (pSUVmax) were analyzed for prediction of LN metastasis. Detectability by ultrasonography (US) and FDG PET/CT for cervical LN metastasis were also assessed and compared with the pSUVmax.

Results

The FDG avidity of the primary tumor was identified in 118 patients (FDG avid group: 61.0%, M: F = 16:102, age 47.0 ± 12.7 years) and pSUVmax ranged from 1.3 to 35.6 (median 4.6) in the FDG avid group. The tumor size in the FDG avid group was bigger and there was a higher incidence of LN metastasis compared to the FDG non-avid group (0.93 vs. 0.59 cm, p <0.001 and 49.2 vs. 33.3%, p <0.05). In the FDG avid group, patients with LN metastasis had higher pSUVmax than patients without LN metastasis (8.7 ± 8.3 vs. 5.7 ± 5.1, p <0.001). The incidence of central LN metastasis in patients with a pSUVmax >4.6 was 54%; however, the detectability of central LN metastasis by US and FDG PET/CT were 10.3% and 3.6%, respectively.

Conclusion

A high FDG avidity of the primary tumor was related to LN metastasis in PTC patients. Therefore, patients with a high pSUVmax should be cautiously assessed for LN metastasis and might need a more comprehensive surgical approach.     

Clinical value of (18)F-FDG PET/CT in postoperative monitoring for patients with colorectal carcinoma

Objective: To evaluate the clinical value of ¹⁸F-FDG PET/CT in postoperative monitoring for patients with colorectal carcinoma. Methods: 66 postoperative patients with colorectal carcinoma underwent whole-body FDG PET/CT. The final histopathological and formal clinical follow-up findings were used as gold standard to determine the sensitivity and specificity of FDG PET/CT and enhanced CT of the same periods. Results: The sensitivity and specificity of FDG PET/CT in detecting recurrence are 96.30%, 94.87% (while enhanced CT are 70.37% and 87.18% respectively). The sensitivity and specificity in detecting metastasis are 95.35%, 82.61% (enhanced CT are 61.90%, 75.00%). SUVmax was significantly higher in malignant lesions [range 4.16–22.00, mean ± standard deviation (x ± s) 8.06 ± 4.30] than in benign ones (range1.18–6.25, x ± s 2.82 ± 1.02). Conclusion: At present, whole-body ¹⁸F-FDG PET/CT is an advanced diagnostic imaging technique in detecting loco-regional recurrence and metastasis in postoperative patients with colorectal carcinoma for its higher sensitivity and specificity.     

18F-FDG PET/CT 在宫颈癌诊断及分期中的临床价值

目的:探讨氟代脱氧葡萄糖(~(18)F-FDG)正电子发射断层显像/X线计算机体层成像仪(PET/CT)检查在局灶早期宫颈癌中的临床应用价值。方法:53例病理确诊为早期宫颈癌的患者行全身~(18)F-FDG PET/CT检查,并在检查结束10日内行广泛性全子宫切除术+双附件切除术+盆腔淋巴结清扫术,计算~(18)F-FDG PET/CT诊断宫颈原发部位肿瘤及盆腔淋巴结转移的敏感度,特异度与准确度。结果:~(18)F-FDG PET/CT检查诊断的宫颈原发部位肿瘤的敏感度为79.25%,特异度为86.79%,准确度为84.9%;以病人为单位诊断盆腔淋巴结转移的准确度为85.71%,特异度为97.87%;以淋巴结为单位诊断盆腔淋巴结转移的准确度为84.61%,特异度为99.00%。结论:PET/CT显像对宫颈癌诊断,分期诊断及盆腔淋巴结转移的检出具有重要临床意义。     

基于18F-FDG PET/CT参数评价不同EGFR基因状态晚期肺腺癌患者放化疗疗效预测价值

为评价18F-FDG PET/CT参数对不同表皮生长因子受体(epithelial growth factor receptor, EGFR)基因状态晚期肺腺癌患者同步放化疗的疗效预测价值,本研究选择2016年1月至2018年2月我院初诊的100例晚期肺腺癌患者,比较不同EGFR基因状态下晚期肺腺癌患者同步放化疗治疗的临床疗效,并对18F-FDG PET/CT显像中原发病灶的各项代谢参数,代谢肿瘤体积(MTV)、最大标准摄取值(SUVmax)、平均标准摄取值(SUVmean)和总肿瘤糖酵解(TLG)值,以预测不同EGFR基因状态晚期肺腺癌患者同步放化疗效果的受试者工作特征曲线(receiveroperatingcharacteristiccurve,ROC曲线),并进行分析。结果显示,SUVmax预测不考虑EGFR基因状态的晚期肺腺癌患者放化疗疗效的截断值为9.50 (AUC=0.715,敏感度=79.7%,特异性=61%,p=0.031),SUVmax预测EGFR野生型的晚期肺腺癌患者放化疗疗效的截断值为9.50 (敏感度=82.4%,特异性=64.3%, p=0.014)。MTV预测EGFR 19号及21号外显子突变的晚期肺腺癌患者放化疗疗效的截断值分别为93.50(敏感度=63.6%,特异性=92.3%, p=0.021),77.00 (敏感度=83.3%,特异性=69.2%, p=0.041)。综上所述,对于EGFR基因状态不明的肺腺癌患者,SUVmax值可较好的预测放化疗效果,尤其是对于EGFR野生型患者;当EGFR19号及21号外显子突变时,MTV值预测结果优于SUVmax值。     

Prognostic Value of 18F-FDG PET/CT in Surgical Non-Small Cell Lung Cancer: A Meta-Analysis

Background

The identification of surgical non-small cell lung cancer (NSCLC) patients with poor prognosis is a priority in clinical oncology because of their high 5-year mortality. This meta-analysis explored the prognostic value of maximal standardized uptake value (SUV_max), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) on disease-free survival (DFS) and overall survival (OS) in surgical NSCLC patients.

Materials and Methods

MEDLINE, EMBASE and Cochrane Libraries were systematically searched until August 1, 2015. Prospective or retrospective studies that evaluated the prognostic roles of preoperative 18F-FDG PET/CT with complete DFS and OS data in surgical NSCLC patients were included. The impact of SUV_max, MTV or TLG on survival was measured using hazard ratios (HR). Sub-group analyses were performed based on disease stage, pathological classification, surgery only and cut-off values.

Results

Thirty-six studies comprised of 5807 patients were included. The combined HRs for DFS were 2.74 (95%CI 2.33–3.24, unadjusted) and 2.43 (95%CI: 1.76–3.36, adjusted) for SUV_max, 2.27 (95%CI 1.77–2.90, unadjusted) and 2.49 (95%CI 1.23–5.04, adjusted) for MTV, and 2.46 (95%CI 1.91–3.17, unadjusted) and 2.97 (95%CI 1.68–5.28, adjusted) for TLG. The pooled HRs for OS were 2.54 (95%CI 1.86–3.49, unadjusted) and 1.52 (95%CI 1.16–2.00, adjusted) for SUV_max, 2.07 (95%CI 1.16–3.69, unadjusted) and 1.91 (95%CI 1.13–3.22, adjusted) for MTV, and 2.47 (95%CI 1.38–4.43, unadjusted) and 1.94 (95%CI 1.12–3.33, adjusted) for TLG. Begg’s test detected publication bias, the trim and fill procedure was performed, and similar HRs were obtained. The prognostic role of SUV_max, MTV and TLG remained similar in the sub-group analyses.

Conclusions

High values of SUV_max, MTV and TLG predicted a higher risk of recurrence or death in patients with surgical NSCLC. We suggest the use of FDG PET/CT to select patients who are at high risk of disease recurrence or death and may benefit from aggressive treatments.     

Increased Arterial PET/CT 18F-Fluorodeoxyglucose Uptake in Obese and Overweight Patients

ObjectivesWe aimed to investigate the association between BMI and early atherosclerotic activity in cancer patients. We also compared the inflammatory and macroscopic calcification processes of atherosclerosis in the aortic segments and large arteries by ¹⁸F-FDG PET/CT of between normal and high BMI patients.MethodsWe conducted a retrospective review of cancer patients presented to our institution within the period between February and May 2018. Patients were classified according to their BMI into two groups: normal BMI group and high BMI group. Data of average SUVmax and SUVmean for four segments of the aorta, common iliac arteries, and femoral arteries were estimated and compared between both groups. Moreover, the macroscopic calcification on CT images for each vascular section was also reported.ResultsNinety-eight patients were classified into two groups: normal BMI group (n = 52; 53.1%), and high BMI group (n = 46; 46.9%). Average SUVmax was significantly higher in obese participants in all arterial segments (P < 0.05). However, the SUVmean was significantly higher in obese patients in only three arterial segments aortic arch, left femoral artery and descending thoracic aorta (P < 0.05).Moreover, the differences between the two study groups in terms of the frequency of macroscopic calcifications were not statistically significant for all vascular segments. BMI positively correlated with SUVmax and SUVmean of the vascular segments (r value from 0,219 to 0,575/p value between 0,023 and 0,0001).ConclusionsFluorine-18-FDG PET/CT imaging revealed that patients with high BMI have more accelerated atherosclerotic inflammatory process in their major vessels compared to their age-matched controls with normal BMI. Future studies should assess the associated between these findings and the cardiovascular events in the long term.     

18F-FDG PET/CT in lymphomas: assessment difficulties due to illness characteristics, and comparison with literature data

Fluor-18-deoxy-glucose (18F-FDG or FDG) positron emission tomography - computer tomography (PET/CT) has recently become integrated into the clinical routine of patients with lymphoma in Hungary. The basic condition of risk-adapted treatment of these patients is the exact staging and early objective evaluation of the effectiveness of therapy. Between 1 May 2007 and 31 October 2010, 1862 18F-FDG PET/CT examinations were conducted for lymphoma patients at the PET/CT Center in Debrecen. This is more than 15% of the total examined patient population, and this rate shows a slight increase with each year. Based on the experience obtained from lymphoma patients by routine metabolic PET/CT scans we analyzed the difficulties of the evaluation in different time frames of patients' management. It is well known that FDG uptake of lymphomas depends on multiple factors. Although most histological subtypes are associated with uptake of FDG, the intensity of the tracer uptake is different. Different intensity of FDG uptake of the same type of lymphoma following therapeutic procedures might cause difficulties in the evaluation of the scans ensuring that primary staging by PET/CT is highly required for precise measurement and reliable comparison of data. Extranodal involvement was detected in ~40% of the patients with variable rate of prevalence. Extranodal involvement is associated with great diversity and in most cases it is not characteristic of the illness and might appear in different forms and in any organs. Additionally, because accompanying disease may produce false positive results, detailed clinical data and precise case history is highly required.     

No diagnostic impact of routinely use of respiratory gating to characterize lung nodules with 18F-FDG PET/CT

Purpose

To evaluate diagnostic impact of routinely use of respiratory gated (RG) ¹⁸FDG PET/CT to distinguish benign and malignant lung nodules.

Different Prognostic Values of Plasma Epstein-Barr Virus DNA and Maximal Standardized Uptake Value of 18F-FDG PET/CT for Nasopharyngeal Carcinoma Patients with Recurrence

Purpose

To evaluate and compare the prognostic value of Epstein-Barr virus (EBV) DNA and maximal standard uptake values (SUV_max ) of ¹⁸F-fluoro-2-deoxy-D-glucose positron emission tomography (¹⁸F-FDG-PET) in subgroups of nasopharyngeal carcinoma (NPC) patients with locoregional or distant recurrence.

Patients and Methods

A total of 194 patients with recurrent NPC (locoregional recurrence: 107, distant recurrence: 87) were enrolled. Patients took evidence of recurrence performed with ¹⁸F-FDG-PET and an EBV DNA test before salvage treatment. Clinical parameters, the status of EBV DNA and the value of SUV_max were used for survival analysis using the Kaplan-Meier method and the Cox proportional hazards regression model.

Results

In the subgroup of patients with locoregional recurrence, patients with SUV_max<8.65 had significantly better overall survival (OS) (P=0.005) compared with the patients with SUV_max ≥8.65. However, both elevated EBV DNA load (≥21,100 copies/ml) and distant SUV_max (≥13.55) were significantly associated with worse OS compared with the patients with EBV DNA <21,100 copies/ml or distant SUV_max <13.55 for the subgroup with distant recurrence (P=0.015 and P=0.006, respectively). The predictive ability of EBV DNA was superior to that of SUV_max (P=0.062). Multivariate analysis showed that SUV_max was only an independent prognostic factor for OS in patients with locoregional recurrence (P=0.042), whereas EBV DNA independently predicted OS for the patients with distant recurrence (P=0.007). For those patients with undetectable EBV DNA, SUV_max<8.65 was still an independent favorable prognostic factor (P=0.038).

Conclusions

SUV_max is a useful biomarker for predicting OS in nasopharyngeal carcinoma patients with locoregional recurrence or with undetectable EBV DNA. Both distant SUV_max and EBV DNA appear to be independent predictors of OS in patients with distant recurrence; however, the predictive ability of EBV DNA was superior to that of SUV_max.     

Radiobiological risks in terms of effective dose and organ dose from 18F-FDG whole-body PET/CT procedures

IntroductionIntegrated Positron Emission Tomography (PET) with Computerized tomography (CT) (PET/CT) are widely used to diagnose, stage and track human diseases during whole body scanning. Multi-modality imaging is an interesting area of research that aims at acquiring united morphological-functional image information for accurate diagnosing and staging of the disease. However, PET/CT procedure accompanied with high radiation dose from CT and administered radioactivity. The aim of the present study was to estimate the patients’ dose from ¹⁸F-fluorodeoxyglucose imaging (18F-FDG) hybrid PET/CT whole body scan.Materials and methodsRADAR (Radiation Dose Assessment Resource) software was used to estimate the effective dose for 156 patients (110 (70.5%)) males and 46 (39.5%) female) examined using Discovery PET/CT 710, GE Medical Systems installed at Kuwait Cancer Control Center (KCCC).ResultsThe effective dose results presented in this PET/CT study ranged from (1.56–9.94 mSv). The effective dose was calculated to be 3.88 mSv in females and 3.71 mSv in males. The overall breast (female), lung, liver, kidney and thyroid were 7.4, 7.2, 5.2, 4, 3 and 2.9, respectively.For females, the body mass index (BMI) was 28.49 kg/m² and for males it was 26.50 kg/m² which showed overweight values for both genders. Conclusions: The findings indicate that the effective dose of 18F-FDG in both male and female patients was not substantially different. The study suggested that the risk–benefit proportions of any ¹⁸F-FDG whole body PET/CT scan should be clarified and carefully weighed. Patient’s doses are lower compared with previous studies.     

Functional Imaging of Brown Fat in Mice with 18F-FDG micro-PET/CT

Brown adipose tissue (BAT) differs from white adipose tissue (WAT) by its discrete location and a brown-red color due to rich vascularization and high density of mitochondria. BAT plays a major role in energy expenditure and non-shivering thermogenesis in newborn mammals as well as the adults ¹. BAT-mediated thermogenesis is highly regulated by the sympathetic nervous system, predominantly via β adrenergic receptor ^{2, 3}. Recent studies have shown that BAT activities in human adults are negatively correlated with body mass index (BMI) and other diabetic parameters ^4-6. BAT has thus been proposed as a potential target for anti-obesity/anti-diabetes therapy focusing on modulation of energy balance ^6-8. While several cold challenge-based positron emission tomography (PET) methods are established for detecting human BAT ^9-13, there is essentially no standardized protocol for imaging and quantification of BAT in small animal models such as mice. Here we describe a robust PET/CT imaging method for functional assessment of BAT in mice. Briefly, adult C57BL/6J mice were cold treated under fasting conditions for a duration of 4 hours before they received one dose of ¹⁸F-Fluorodeoxyglucose (FDG). The mice were remained in the cold for one additional hour post FDG injection, and then scanned with a small animal-dedicated micro-PET/CT system. The acquired PET images were co-registered with the CT images for anatomical references and analyzed for FDG uptake in the interscapular BAT area to present BAT activity. This standardized cold-treatment and imaging protocol has been validated through testing BAT activities during pharmacological interventions, for example, the suppressed BAT activation by the treatment of β-adrenoceptor antagonist propranolol ^{14, 15}, or the enhanced BAT activation by β3 agonist BRL37344 ¹⁶. The method described here can be applied to screen for drugs/compounds that modulate BAT activity, or to identify genes/pathways that are involved in BAT development and regulation in various preclinical and basic studies.