Variability of lesion detectability and standardized uptake value according to the acquisition procedure and reconstruction among five PET scanners

OBJECTIVE: The objective of this study was to assess differences in the semiquantitative values of 18F-fluorodeoxyglucose (18F-FDG) uptake among different positron emission tomographic (PET) systems. METHODS: A phantom study was performed to compare standardized uptake value (SUV) in five PET scanners including a dedicated PET scanner and four PET/computed tomography (CT) scanners. Radioactivity simulating the SUV of 2.5 was filled in the hot spheres (8 mm, 11 mm, 14 mm, 18 mm, 22 mm, and 27 mm) that were set in the cylindrical phantom with the background SUV of 1.0. Data acquisition and reconstruction were performed according to routine and standardized conditions. The standardized condition was as follows: CT acquisition (120 kVp, 50 mA) and PET acquisition (2-min acquisition with a slice thickness of 2 mm); reconstruction was performed by ordered subsets expectation maximization + Fourier rebinning. Detectability of hot spheres and SUV was compared between routine condition and standardized condition with five PET scanners. RESULTS: On routine condition, two cameras could detect a 14-mm sphere clearly. On the other hand, the visualization of hot spheres by the standardized condition was remarkably variable. Semiquantitative evaluation revealed that a maximum of 45.7% error was recognized with the 27-mm sphere by the routine condition, although the standardized condition could reduce the error to 22.6%. CONCLUSIONS: Detectability depends not only on the PET machine but also on the imaging protocol. The results indicate that SUV is variable with PET machines under routine conditions of data acquisition and reconstruction. Standardization of the reconditions can reduce variability and maximum difference in the SUV by half.     

Breast cancer with low FDG uptake: characterization by means of dual-time point FDG-PET/CT

Background

Malignant breast lesions usually are differentiated by FDG-PET with a semiquantitative FDG standardized uptake value (SUV) of 2.5. However, the frequency of breast cancer with an SUV of less than or equal to 2.5 is noteworthy, and often present diagnostic challenges. This study was undertaken to evaluate the accuracy of dual-time point FDG-PET/CT with FDG standardized uptake value (SUV) calculation in the characterization of such breast tumors.

Methods

Forty-nine female patients with newly diagnosed breast cancer were found to have primary breast cancer with minimally increased FDG uptake and met the criteria for inclusion in this study by having borderline levels of increased FDG uptake (SUVmax less than or equal to 2.5) in the initial FDG-PET/CT images. Consequently, they underwent further delayed phase FDG-PET/CT scan for better evaluation of the disease.

Results

Of the 49 cancer lesions; the majority were found to have rising or unvarying dual-time changes in SUVmax (75.5%). The median value of SUVmax increases by 25% between the early and delayed scan. The means ± S.D. of the SUVmax1, the SUVmax2, and the ΔSUVmax% were 1.2 ± 0.6%, 1.3 ± 0.9%, and 5.1 ± 22.4%, respectively. The receiver-operating-characteristic (ROC) analysis proved that the highest accuracy for characterization of malignant breast lesions was obtained when a ΔSUVmax% cut-off value 0.0% was used as criteria for malignant FDG uptake-change over time with sensitivity 75.5%, and false-positive rate 20.4%.

Conclusion

These results suggested that dual-time FDG-PET/CT imaging with standardized uptake value (SUV) estimation can improve the accuracy of the test in the evaluation of breast cancer with low FDG uptake.     

Clinicopathological and prognostic relevance of uptake level using 18F-fluorodeoxyglucose positron emission tomography/computed tomography fusion imaging (18F-FDG PET/CT) in primary breast cancer

Objective: Using integrated ¹⁸F-fluorodeoxyglucose positron emission tomography/computedtomography fusion imaging (¹⁸F-FDG PET/CT), the clinical significanceof ¹⁸F-FDG uptake was evaluated in patients with primary breastcancer. Methods: Clinicopathological correlation with the level of maximum standardizeduptake values (SUV) 60 min obtained from preoperative ¹⁸F-FDGPET/CT were examined in 152 patients with primary breast cancer.The prognostic impact of the level of SUV was explored usingsimulated prognosis derived from computed program Adjuvant!in 136 (89%) patients with invasive ductal carcinoma (IDC). Results: High SUV level was significantly correlated with tumor invasivesize (2 cm) (P <0.0001), higher score of nuclear grade (P<0.0001), nuclear atypia (P <0.0001) and mitosis counts(P <0.0001), negative hormone receptor status (P = 0.001),high score of c-erbB-2 expression (P = 0.006), lymph node metastasis(P = 0.002), and IDC in comparison with invasive lobular carcinoma(P = 0.004). Multivariate analyses showed tumor invasive size,nuclear grade and estrogen receptor negativity were significantlycorrelated with SUV in primary breast cancer (P <0.0001,<0.0001,and <0.012, respectively), and nuclear grade was significantlycorrelated with SUV in tumors of invasive size 2 cm or less(P <0.0001). Tumors with high SUV (cutoff value 4.0) showedhigher relapse and mortality rate compared to those with lowSUV (P <0.0001). Conclusions: High uptake of ¹⁸F-FDG would be predictive of poor prognosisin patients with primary breast cancer, and aggressive featuresof cancer cells in patients with early breast cancer. ¹⁸F-FDGPET/CT could be a useful tool to pretherapeutically predictbiological characteristics and baseline risk of breast cancer.     

肺腺癌PET/CT代谢指标与免疫细胞标志物表达水平的相关性

目的：分析肺腺癌18F-FDG PET/CT代谢指标与免疫细胞标志物表达水平的相关性，探讨其在肺腺癌治疗及判断预后中的作用。方法：回顾性分析2008 年4 月至2014 年8 月在天津医科大学肿瘤医院收治并接受PET/CT检查的85 例肺腺癌患者的临床资料，应用免疫组织化学法检测癌组织中CD3、CD8、CD68、CD163、CD11c、Foxp3、PD-1 和PD-L1 的表达水平，采用Pearson相关性检验PET/CT各指标[肿瘤原发灶最大摄取标准值（SUVmax）、标准摄取值峰值（SUVpeak）和平均标准摄取值（SUVmean）]与CD68+肿瘤相关巨噬细胞（CD68+TAM）和肿瘤代谢指标[肿瘤代谢体积（MTV）、糖酵解总量（TLG）]的相关性，Kaplan-Meier 法分析肿瘤代谢与免疫指标和患者生存的相关性。结果：SUVmax、SUVpeak和SUVmean与CD68+ TAM的表达水平在肺腺癌患者中呈负相关（r=-0.253、-0.265、-0.263，均P<0.05)，与PD-1+TIL表达水平呈正相关（r=0.427、0.402、0.395，均P<0.01）。MTV、TLG与Foxp3+Treg、PD-1+TIL 表达水平呈正相关（r=0.313、0.307、0.29、0.407，均P<0.01）。Kaplan-Meier 法生存分析发现，SUVmax、SUVmean、CD11c+DC、PD-L1+细胞和TLG水平与患者预后（PFS或OS）显著相关（均P<0.05）。结论：肿瘤原发灶代谢状态与肿瘤浸润免疫细胞标志物表达显著相关，该两项中的部分指标与患者预后显著相关，提示18F-FDG PET/CT检测指标反映的肿瘤代谢和微环境免疫状态对肺腺癌患者预后判断及免疫治疗具有重要的参考价值。     

Standardized Uptake Value Atlas: Characterization of Physiological 2-Deoxy-2-[<Superscript>18</Superscript>F]fluoro-<Emphasis Type="SmallCaps">d</Emphasis>-glucose Uptake in Normal Tissues

Purpose The purpose of this study was to map the distribution of 2-deoxy-2-[¹⁸F]fluoro-d-glucose (FDG) uptake in organs of patients with no known abnormalities in those tissues. Procedures We measured maximum and mean standardized uptake values (SUV) from FDG-positron emission tomography (PET)/computed tomography (CT) obtained from 98 patients (48 males and 50 females). Results Significant uptake (mean SUV_mean > 2.5) was visualized in the cerebellum (8.0 ± 2.2), soft palate (2.92 ± 0.86), palatine tonsils (3.45 ± 1.4), lingual tonsils (3.08 ± 1.05), sublingual glands (3.3 ± 1.5), and testes (2.57 ± 0.56). Negative correlation for FDG uptake versus age was observed for the palatine tonsils, sublingual glands, and lungs (P < 0.001). Conclusion Better understanding of physiological uptake throughout the body is valuable for improved interpretive accuracy and should be useful for future semi-automated comparisons to a normal SUV database.     

18F–Sodium Fluoride Uptake in Abdominal Aortic Aneurysms: The SoFIA3 Study

Background

Fluorine-18–sodium fluoride (¹⁸F-NaF) uptake is a marker of active vascular calcification associated with high-risk atherosclerotic plaque.

Dual-time-point (18)F-FDG-PET/CT imaging in the assessment of suspected malignancy

Introduction (purpose of the study): The objective of this study was to assess whether dual‐time‐point ¹⁸F‐fluoro‐2‐deoxyglucose (¹⁸F‐FDG)‐PET/CT imaging improved the evaluation of suspected malignancy and if there was any resulting change in management. Methods: A total of 53 patients with suspected malignancy were investigated by performing two static acquisitions started at mean times t = 64 and t = 155 min after the tracer injection. The total number of malignant lesions was 133 and the total number of benign lesions was 61. Visual and semiquantitative analysis was performed on both the early and delayed images. Results: Overall, there was a significant improvement (P < 0.001) in the sensitivity of delayed imaging (94%) compared with early imaging (77%) in detecting malignant lesions, without a reduction in specificity. In 10 patients, 13 malignant lesions were undetected on early imaging alone but detected on delayed imaging. In seven patients, 10 malignant lesions were incorrectly classified as ‘likely benign’ on early imaging but correctly reported as ‘likely malignant’ on delayed imaging. Management was altered in 2 out of 17 patients. Overall, delayed imaging altered management in 2 out of 53 studied patients. Dual‐time‐point ¹⁸FDG‐PET/CT imaging was useful in differentiating malignant from benign intra‐abdominal lesions but did not improve the evaluation of pulmonary lesions. Conclusions: ¹⁸F‐FDG‐PET/CT imaging should be performed as late as reasonably possible after tracer administration in order to increase tumour‐to‐background contrast and thereby improve the sensitivity of demonstrating additional sites of disease. Dual‐time‐point ¹⁸FDG‐PET/CT may be of benefit in the evaluation of intra‐abdominal lesions but does not improve the overall evaluation of pulmonary lesions.