18F-FDG PET与MRI联合检测颈动脉易损斑块的应用前景

颈动脉粥样硬化斑块的破裂是导致脑卒中发生的主要原因.利用18F-FDG PET联合MRI的方法可以同时提供斑块代谢、形态及成分方面的信息,大大提高诊断的灵敏度和特异性.     

18F-FDG PET与MRI联合检测颈动脉易损斑块的应用前景

颈动脉粥样硬化斑块的破裂是导致脑卒中发生的主要原因.利用18F-FDG PET联合MRI的方法可以同时提供斑块代谢、形态及成分方面的信息,大大提高诊断的灵敏度和特异性.     

Reproducibility of standardized uptake value measurements determined by 18F-FDG PET in malignant tumors

18F-FDG PET is increasingly being used to monitor the early response of malignant tumors to chemotherapy. Understanding the reproducibility of standardized uptake values (SUVs) is an important prerequisite in estimating what constitutes a significant change. METHODS: Twenty-six patients were studied on 2 separate occasions (mean interval +/- SD, 3 +/- 2 d; range, 1-5 d). A static PET/CT scan was performed 94 +/- 9 min after the intravenous injection of 383 +/- 15 MBq of 18F-FDG. Mean and maximum SUVs (SUVmean and SUVmax, respectively) were determined for regions of interest drawn around the tumor on the first study and for the same regions of interest transferred to the second study. RESULTS: SUVmean in tumors ranged from 1.49 to 17.48 and SUVmax ranged from 2.99 to 24.09. The correlation between SUVmean determined on the 2 separate visits was 0.99; the mean difference between the 2 measurements was 0.01 +/- 0.27 SUV. The 95% confidence limits for the measurements were +/-0.53. For SUVmax, the mean difference was -0.05 +/- 1.14 SUV. CONCLUSION: Our study demonstrates that repeated measurements of SUVmean performed a few days apart are highly reproducible. A decrease of 0.5 in the SUV is statistically significant.     

Glucose-normalized standardized uptake value from (18)F-FDG PET in classifying lymphomas.

Our objective was to derive the best glucose sensitivity factor (g-value) and the most discriminating standardized uptake value (SUV) normalized to glucose for classifying indolent and aggressive lymphomas. METHODS: The maximum SUV obtained from (18)F-FDG PET over the area of biopsy in 102 patients was normalized by serum glucose ([Glc]) to a standard of 100 mg/dL. Discriminant analysis was performed by using each SUV(100) (SUV x {100/[Glc]}(g), calculated using various g-values ranging from -3.0 to 0, one at a time) as a variable against the lymphoma grades, and plotting the percentage of correct classifications against g (g-plot) to search for the best g-value in normalizing SUV(100) for classifying grades. To address the influence of the extreme glucose conditions, we repeated the same analyses in 12 patients with [Glc] < or = 70 mg/dL or [Glc] > or = 110 mg/dL. RESULTS: SUV(100) correctly classified lymphoma grades ranging from 62% to 73% (P < 0.0005), depending on the g-value, with a maximum at a g-value of -0.5. For the subgroup with extreme glucose values, the g-plot also revealed higher and more optimal discrimination at a g-value of -0.5 (92%) than at a g-value of 0 (83%) (P = 0.03). The discrimination deteriorated at g < -1 in both analyses. The box plot for all cases using a g-value of -0.5 showed little overlap in classifying lymphoma grades. For a visually selected threshold SUV(100) of 7.25, the sensitivity, specificity, and accuracy of identifying aggressive grades were 82%, 79%, and 81%, respectively. CONCLUSION: The results suggest that metabolic discrimination between lymphoma grades using a glucose-normalized SUV from (18)F-FDG PET is improved by introducing g-value as an extra degree of freedom.     

^18F-FDG符合线路显像最大标准摄取值在胃癌评估中的价值

目的研究^18F—FDG符合线路显像SUVmax在胃癌评估中的意义。方法回顾性分析92例胃部疾病患者[男60例,女32例,平均年龄65（32～85）岁;其中胃癌78例]。78例胃癌中,残胃癌3例、原发性胃癌75例（Eis期4例、T1期13例、T2期9例、T3期33例、T4期11例,5例未手术）;高分化腺癌22例,中分化腺癌15例,低分化腺癌28例。采用ROI技术分析图像并计算SUVmax,分别用视觉法与SUVmax分析^18F—FDG符合线路显像资料,并以组织病理学或活组织检查结果为标准计算两者检验效能。使用ROC曲线分析评价SUVmax;采用Pearson相关分析评估SUVmax与病灶大小的关系,Wilcoxon秩和检验分析SUVmax在进展期胃癌和早期胃癌的差异,Kruskal—Wallis检验分析SUVmax与不同分化程度腺癌的关系。结果^18F—FDG符合线路显像视觉法与SUVmax诊断胃癌的灵敏度均为64．1％（50／78）,特异性均为64．3％（9／14）,准确性均为64．1％（59／92）。SUVmax ROCAUC为0．695,最佳临界值为0．700;SUVmax与病灶最大径呈正相关（r=0．489,P〈0．001）,Tis-1期病灶SUVmax（0．676±1．288）与L～4期SUVmax（3．851±3．764）差异有统计学意义（Z=-3．754,P〈0．001）,而高、中、低分化腺癌间SUVmax（分别为2．805±4．008,3．447±2．365,3．413±3．737）差异无统计学意义（X2=2．459,P〉0．05）。结论在^18F-FDG符合线路显像评估胃癌中,SUVmax较视觉法提供了更多的信息,但其与胃癌T分期、组织学类型、分化程度等的关系需进一步研究。     

Glucose corrected standardized uptake value (SUVgluc) in the evaluation of brain lesions with 18F-FDG PET

Purpose

To retrospectively assess the utility of ¹⁸F fluorodeoxyglucose (FDG) positron emission tomography (PET) images of standardized uptake values corrected for blood glucose (SUV_gluc), and to compare this to various quantitative methods to identify the presence or absence of high grade malignancy.

Methods

A retrospective review in 42 patients, found 81 central nervous system (CNS) lesions. Fifty one were malignant and 30 were benign or post treatment changes based on pathology (n?=?32) and on clinical outcome (n?=?49). Dynamic FDG PET scans were processed to generate parametric images of SUV_gluc, SUV, glucose metabolic rate (GMR), and lesion to cerebellum ratios (SUV_Rc), and contralateral white matter ratios (SUV_Rw). The SUV_gluc was calculated from $ {{{\mathrm{SU}{{\mathrm{V}}_{\max }}*\mathrm{BG}}} \left/ {{\left[ {100\,\mathrm{mg}/\mathrm{dl}} \right]}} \right.} $ , where SUV_max is the maximum SUV and BG is the blood glucose level (mg/dL).

Results

Using a malignant threshold for SUV_gluc of 4.5 and GMR of 13.0 μmole/min/100 g, the accuracies were similar for the SUV_gluc (80 %) and GMR (81 %) and were higher than the conventional SUV_max (73 %). The area under the receiver operating characteristic (ROC) curve for the SUV_gluc (0.8661) was better than that for the SUV_max (0.7955) (p?<?0.02) and was similar to those of the GMR (0.8694), SUV_Rc (0.8278), and SUV_Rw (0.8559).

Conclusion

These results suggest that the SUV_gluc may assist in the interpretation of FDG PET brain images in patients with CNS lesions. The SUV_gluc method avoids the complexity of kinetic modeling and the definition of a reference region.     

Accuracy of PET for diagnosis of solid pulmonary lesions with 18F-FDG uptake below the standardized uptake value of 2.5.

Benign and malignant pulmonary lesions usually are differentiated by 18F-FDG PET with a semiquantitative 18F-FDG standardized uptake value (SUV) of 2.5. However, the frequency of malignancies with an SUV of <2.5 is significant, and pulmonary nodules with low 18F-FDG uptake often present diagnostic challenges. METHODS: Among 360 consecutive patients who underwent 18F-FDG PET to evaluate pulmonary nodules found on CT, we retrospectively analyzed 43 who had solid pulmonary lesions (excluding lesions with ground-glass opacity, infiltration, or benign calcification) with an SUV of <2.5. The uptake of 18F-FDG was graded by a visual method (absent, faint, moderate, or intense) and 2 semiquantitative methods (SUV and contrast ratio [CR]). Final classification was based on histopathologic findings or at least 6 mo of clinical follow-up. RESULTS: We found 16 malignant (diameter, 8-32 mm) and 27 benign (7-36 mm) lesions. When faint visual uptake was the cutoff for positive 18F-FDG PET results, the receiver-operating-characteristic (ROC) analysis correctly identified all 16 malignancies and yielded false-positive results for 10 of 27 benign lesions. Sensitivity was 100%, specificity was 63%, and the positive and negative predictive values were 62% and 100%, respectively. When an SUV of 1.59 was the cutoff for positive 18F-FDG PET results, the ROC analysis revealed 81% sensitivity, 85% specificity, and positive and negative predictive values of 77% and 89%, respectively. At a cutoff for positive 18F-FDG PET results of a CR of 0.29, the ROC analysis revealed 75% sensitivity, 82% specificity, and positive and negative predictive values of 71% and 85%, respectively. The areas under the curve in ROC analyses did not differ significantly among the 3 analyses (visual, 0.84; SUV, 0.81; and CR, 0.82). Analyses of intra- and interobserver variabilities indicated that visual and SUV analyses were quite reproducible, whereas CR analysis was poorly reproducible. CONCLUSION: These results suggested that for solid pulmonary lesions with low 18F-FDG uptake, semiquantitative approaches do not improve the accuracy of 18F-FDG PET over that obtained with visual analysis. Pulmonary lesions with visually absent uptake indicate that the probability of malignancies is very low. In contrast, the probability of malignancy in any visually evident lesion is about 60%.     

Within-patient variability of (18)F-FDG: standardized uptake values in normal tissues.

The aim of this study was to evaluate the test-retest variability of standardized uptake values (SUVs) in normal tissues and the impact of various methods for measuring the SUV. METHODS: SUVs were determined in 70 cancer-free patients (40 female and 30 male) on 2 occasions an average of 271 d apart. Mean values for body weight and height, blood glucose level, injected dose, and uptake period did not change between the 2 groups of studies. Four regions of interest (ROIs) were placed-on the liver, lung, mediastinum, and trapezius muscle. Mean and maximum SUVs normalized for body weight were obtained, and normalizations were then applied for lean body mass (LBM), LBM and blood glucose level, body surface area (BSA), and BSA and blood glucose level. RESULTS: In the lungs and muscle, metabolic activity within the ROIs was significantly different in the 2 studies, no matter which method was used for the SUVs. The differences ranged from 0.02 to 0.1 for SUV normalized for body weight and SUV normalized for LBM and from 0.001 to 0.002 for SUV normalized for BSA. In the liver, results were similar for all SUVs, except for maximum SUV corrected for LBM and maximum SUV corrected for LBM and blood glucose level. The metabolic activity measured in the mediastinum was also comparable in the 2 studies, regardless of the type of SUV. When investigating whether any normalization method for SUVs reduces variability and improves test-retest concordance, we found no significant superiority for any. The best intraclass correlation coefficients were obtained with the SUV normalized for body weight, in both the liver and the mediastinum, but the coefficients of variation were similar for all 3 mean SUVs that were not corrected for glucose level (range, 10.8%-13.4%). However, normalizing for blood glucose level increased the variability and decreased the level of concordance between studies. CONCLUSION: The SUVs measured in normal liver and mediastinum in cancer-free patients are stable over time, no matter which normalization is used. Correcting for blood glucose level increases the variability of the values and should therefore be avoided. Normalizing for BSA or LBM does not improve the reproducibility of the measurements.     

The increment in standardized uptake value determined using dual-phase 18F-FDG PET is a promising prognostic factor in non-small-cell lung cancer

Purpose

We aimed to determine whether the increment in the maximal standardized uptake value (SUVmax) of the primary lung tumour between the initial and delayed imaging by dual-phase ¹⁸F-FDG PET has prognostic value in patients with non-small-cell lung cancer (NSCLC).

Methods

We reviewed the records of patients with NSCLC who underwent pretreatment dual-phase ¹⁸F-FDG PET/CT scans acquired at 1 h and 2 h after injection. The SUVmax increment (SUVinc) of the primary lung tumour was the 2-h SUVmax minus the 1-h SUVmax. Univariate and multivariate analyses were used to assess the prognostic significance of SUVinc, retention index, whole-body total metabolic tumour volume, whole-body total lesion glycolysis (TLGwb), 1-h SUVmax, 2-h SUVmax, gender, age, performance status, histological subtype, T stage, N stage and clinical stage.

Results

The records of 187 consecutive patients were reviewed. The median follow-up time was 3.9 years. The estimated median progression-free survival (PFS) and overall survival (OS) were 1.3 years and 4.4 years, respectively. An SUVinc cut-off value of >1 had the best discriminative yield for PFS. The 3-year PFS and OS were 61.6 % and 87.8 % in patients with SUVinc ≤1 versus 21.1 % and 46.2 % in patients with SUVinc >1 (all P?<?0.01). Using the forward stepwise multivariate Cox proportional hazards model, SUVinc, TLGwb, and clinical stage were significant factors for PFS (all P?<?0.01). A subgroup analysis of 117 patients treated with surgery showed that SUVinc (P?=?0.02) and clinical stage (P?<?0.01) were significant prognostic factors for PFS. Furthermore, in stage I patients treated with surgery alone, SUVinc was the only significant prognostic factor (HR 28.07; 95 % CI 2.42 – 326.41).

Conclusion

SUVinc determined from dual-phase ¹⁸F-FDG PET is a promising prognostic factor for NSCLC. It adds to the value of dual-phase ¹⁸F-FDG PET.     

18F-FDG PET/CT检查中腹腔积液SUV对不明原因腹腔积液的辅助诊断价值

目的 分析良恶性腹腔积液患者18 F-FDG PET/CT显像特点,探讨腹腔积液SUV对不明原因腹腔积液的辅助诊断价值.方法 回顾性分析首次18 F-FDG PET/CT检查前病因不明、但随访诊断明确的腹腔积液患者55例,其中男24例,女31例,年龄23～82(平均54.8)岁;良性腹腔积液19例,恶性腹腔积液36例.测定良恶性腹腔积液的SUV,并计算其与正常肝脏SUV的比值(T/NT).比较PET/CT肿瘤定位诊断、腹腔积液代谢判定及细胞学检查三者的诊断效能.采用两样本t检验、x2检验或确切概率法分析数据.结果 恶性腹腔积液患者18F-FDG PET/CT显像示腹腔积液代谢升高,MIP图像呈肝脾“淹没征”.恶性腹腔积液的SUVmax及SUVmax.分别为1.78±0.65和1.37±0.38,良性腹腔积液的相应值分别为1.11 ±0.36和0.72±0.22,前者明显高于后者(t=4.13、6.82,均P＜0.05).恶性腹腔积液的T/NT值明显高于良性腹腔积液(基于SUVmax的T/NT值:0.64±0.20与0.48±0.12,t=3.27;基于SUVmean.的T/NT值:0.68±0.17与0.38±0.10,t=7.21,均P＜0.05).根据腹腔积液代谢诊断恶性腹腔积液的灵敏度、特异性及准确性分别为75.0％(27/36)、94.7％(18/19)和81.8％(45/55),其灵敏度及准确性明显高于腹腔积液细胞学检查[44.4％(16/36)与63.6％(35/55);X2=6.98和4.58,均P＜0.05],其特异性明显高于PET/CT肿瘤定位诊断[63.2％ (12/19)X2=5.70,P＜0.05].结论 腹腔积液代谢升高对恶性腹腔积液的辅助诊断具有重要价值,18 F-FDG PET/CT阅片分析应密切结合腹腔积液SUV及与肝脏的T/NT值,以进一步提高对不明原因腹腔积液的良恶性鉴别诊断效率.     

Effects of coverage extent and slice skipping on mean and maximum arterial 18F-FDG uptake ratios in patients with carotid plaque

Purpose

To investigate the effects of variable measurement methods on mean and maximum SUV ratios of ¹⁸F-FDG uptake in carotid arteries.

Methods

¹⁸F-FDG PET/CT images of 74 subjects with carotid plaque were analyzed for mean and maximum target-to-background ratio (TBR) of uptake. Agreement was analyzed between TBR scores obtained using different vessel coverage and slice skipping.

Results

Mean TBR was increased by extending coverage from common carotid artery (CCA; 1.25) to carotid artery (CA; 1.33) and inclusion of ascending aorta (CA/AA; 1.34). Maximum TBR was increased from 1.47 to 1.54 and 1.61 by respective extensions. Both mean and maximum TBR were closely correlated between vessels. ICC and Kappa statistics revealed near perfect agreement between TBR obtained using every 2 or 3 segments and that without sipping. Bland?CAltman plots showed bias by slice skipping to remain small, particularly for mean TBR. Finally, high correlations were displayed between mean and maximum TBR.

Conclusions

Analysis of mean and maximum arterial ¹⁸F-FDG uptake in patients with carotid plaque is likely to benefit from extending coverage to segments above and below the CCA. The extra burden of measurement, in turn, can be lightened by skipping up to every 2 of 3 slices without compromising accuracy of results.     

Prognostic value of lymph node-to-primary tumor standardized uptake value ratio in endometrioid endometrial carcinoma

Purpose

To determine whether the relative metabolic activity of pelvic or para-aortic LN compared with that of primary tumor measured by preoperative [¹⁸F]FDG PET/CT scan has prognostic value in patients with endometrioid endometrial carcinoma.

Methods

We retrospectively reviewed patients with endometrioid endometrial carcinoma who underwent preoperative [¹⁸F]FDG PET/CT scans. Prognostic values of PET/CT-derived metabolic variables such as maximum standardized uptake value (SUV) of the primary endometrial carcinoma (SUV_Tumor) and LN (SUV_LN), and the LN-to-endometrial carcinoma SUV ratio (SUV_LN / SUV_Tumor) were assessed.

Results

Clinico-pathological data, imaging data, and treatment results were reviewed for 107 eligible patients. Median post-surgical follow-up was 23 months (range, 6–60), and 7 (6.5%) patients experienced recurrence. Regression analysis showed that SUV_LN / SUV_Tumor (P < 0.001), SUV_LN (P = 0.003), International Federation of Gynecology and Obstetrics (FIGO) stage (P = 0.006), and tumor grade (P = 0.011) were risk factors of recurrence. Multivariate regression analysis revealed that FIGO stage (P = 0.034) was the independent risk factor of recurrence. SUV_LN / SUV_Tumor showed significant correlation with FIGO stage (P < 0.001), LN metastasis (P < 0.001), lymphovascular space invasion (P < 0.001), recurrence (P = 0.001), tumor grade (P < 0.001), and deep myometrial invasion of tumor (P = 0.022). Patient groups categorized by SUV_LN / SUV_Tumor showed significant difference in progression-free survival (Log-rank test, P = 0.001).

Conclusions

Preoperative SUV_LN / SUV_Tumor measured by [¹⁸F]FDG PET/CT was significantly associated with recurrence, and may become a novel prognostic factor in patients with endometrioid endometrial carcinoma.

     

The clinical value of 18F-FDG detection with a dual-head coincidence camera: a review

Positron emission tomography (PET) has evolved into a technique that can accurately determine the distribution of positron-emitting radionuclides. The addition of a coincidence detection mode to a standard dual-head detector system has resulted in the option of single-photon and annihilation coincidence detection. This new device for imaging fluorine-18 2-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) accumulation in neoplasms became commercially available in 1994. Besides conventional low-energy imaging in the collimated single-photon mode, it offers a relatively inexpensive opportunity to perform uncollimated PET by switching to the coincidence acquisition mode. This review summarises the clinical value of ¹⁸F-FDG detection with a dual-head coincidence camera in oncology. The results are compared with the overall results obtained using dedicated PET scanners. With respect to head and neck tumours, ¹⁸F-FDG coincidence mode gamma camera imaging (CGI) yields results that are in agreement with those obtained with dedicated PET scanners. With regard to other malignancies, such as lung cancer, lymphoma and brain tumours, data in the literature are too scarce to draw any definite conclusions. In general, the results of ¹⁸F-FDG CGI in tumours >15 mm seem to be comparable to those obtained with dedicated PET scanners, whereas in tumours <15 mm, the relative sensitivity of ¹⁸F-FDG CGI is approximately 80%. Using attenuation correction, the diagnostic yield of ¹⁸F-FDG CGI may increase. However, further clinical investigation is required to definitely establish its value in staging primary disease, therapy monitoring and assessment of tumour recurrence in clinical oncology.     

18F-FDG uptake on PET in primary mediastinal non-thymic neoplasm: a clinicopathological study

Background

The usefulness of 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron emission tomography (PET) has been investigated in thymic epithelial tumors. However, little is known about PET imaging of ¹⁸F-FDG in primary non-thymic mediastinal neoplasms. The aim of this study is to explore the clinicopathological significance of ¹⁸F-FDG PET in primary mediastinal (non-thymic) neoplasms.

Methods

Twenty-one patients with mediastinal neoplasms who underwent ¹⁸F-FDG PET before treatment were included in this study. Tumor sections were stained by immunohistochemistry for glucose transporter 1 (Glut1); glucose transporter 3 (Glut3); hypoxia-inducible factor-1 alpha (HIF-1α); hexokinase I; vascular endothelial growth factor (VEGF); microvessels (CD34); epidermal growth factor receptor (EGFR); Akt/mTOR signaling pathway (p-Akt and p-mTOR); cell cycle control (p53).

Results

Seventeen of 21 patients were imaged on PET system using ¹⁸F-FDG, but 4 patients with a histology of cyst showed nothing abnormal in PET scans. The histology of the resected tumors was as follows: 6 schwannoma, 3 teratoma, 4 cyst, 3 sarcoma, 1 undifferentiated carcinoma, 1 seminoma, 1 mediastinal goiter, 1 ganglioneuroma, and 1 Hodgkin lymphoma. ¹⁸F-FDG uptake was significantly correlated with Glut1, HIF-1α, EGFR, p-Akt and p-S6K. These biomarkers were highly expressed in schwannoma, teratoma and high grade malignancies, whereas all patients with cyst and ganglioneuroma had no positive expression of these biomarkers. High uptake of ¹⁸F-FDG was significant associated with Glut1, VEGF, EGFR, p-Akt, p-S6K and tumor maximal size.

Conclusion

The amount of ¹⁸F-FDG uptake in primary mediastinal non-thymic neoplasms is determined by the presence of glucose metabolism (Glut1), hypoxia (HIF-1α) and upstream components of HIF-1α (EGFR, p-Akt and p-S6K).