Lean body mass-based standardized uptake value,derived from a predictive equation,might be misleading in PET studies

The standardized uptake value (SUV) has gained recognition in recent years as a semiquantitative evaluation parameter in positron emission tomography (PET) studies. However, there is as yet no consensus on the way in which this index should be determined. One of the confusing factors is the normalisation procedure. Among the proposed anthropometric parameters for normalisation is lean body mass (LBM); LBM has been determined by using a predictive equation in most if not all of the studies. In the present study, we assessed the degree of agreement of various LBM predictive equations with a reference method. Secondly, we evaluated the impact of predicted LBM values on a hypothetical value of 2.5 SUV, normalised to LBM (SUV(LBM)), by using various equations. The study population consisted of 153 women, aged 32.3+/-11.8 years (mean+/-SD), with a height of 1.61+/-0.06 m, a weight of 71.1+/-17.5 kg, a body surface area of 1.77+/-0.22 m(2) and a body mass index of 27.6+/-6.9 kg/m(2). LBM (44.2+/-6.6 kg) was measured by a dual-energy X-ray absorptiometry (DEXA) method. A total of nine equations from the literature were evaluated, four of them from recent PET studies. Although there was significant correlation between predicted and measured LBM values, 95% limits of agreement determined by the Bland and Altman method showed a wide range of variation in predicted LBM values as compared with DEXA, no matter which predictive equation was used. Moreover, only one predictive equation was not statistically different in the comparison of means (DEXA and predicted LBM values). It was also shown that the predictive equations used in this study yield a wide range of SUV(LBM) values from 1.78 to 5.16 (29% less or 107% more) for an SUV of 2.5. In conclusion, this study suggests that estimation of LBM by use of a predictive equation may cause substantial error for an individual, and that if LBM is chosen for the SUV normalisation procedure, it should be measured, not predicted.     

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.     

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.     

Accuracy of standardized uptake value measured by simultaneous emission and transmission scanning in PET oncology.

We assessed the accuracy of the standardized uptake value (SUV) measured by simultaneous emission and transmission scanning in cancer patients using FDG positron emission tomography (PET). Conventional, independent emission (E)/transmission (T) scans and simultaneous E/T scans were conducted consecutively in 30 patients who underwent FDG PET examinations. The SUVs of 35 mass lesions and 34 selected normal tissues were derived from the independent E/T scan and simultaneous E/T scan. Experimental studies using a cylindrical phantom were also conducted to evaluate the accuracy and reproducibility of the SUV derived from a simultaneous E/T scan. The SUVs of 18F solution in the phantom were estimated to be approximately 1, with high reproducibility in the range of total counts observed in the clinical examinations. There were no significant differences in the SUVs in 35 tumours derived from simultaneous E/T scans and those derived from independent scans, and there was a strong positive correlation between the two (r = 0.99, P < 0.01). There were also no significant differences in the SUVs in 34 normal tissue regions derived from simultaneous E/T scans and those derived from independent scans. In conclusion, simultaneous E/T scanning with FDG in patients with malignant tumours is a valid method, since the SUV derived from the simultaneous scan is accurate and reproducible.     

FDG PET of primary benign and malignant bone tumors: standardized uptake value in 52 lesions

PURPOSE: To evaluate the standardized uptake value (SUV) of 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) at positron emission tomography (PET) in the differentiation of benign from malignant bone lesions. MATERIALS AND METHODS: Fifty-two (19 malignant, 33 benign) primary bone lesions were examined with FDG PET prior to tissue diagnosis. The SUVs were calculated and compared between benign and malignant lesions and among histologic subgroups that included more than four cases. RESULTS: There was a statistically significant difference in SUV between benign (2.18 +/- 1.52 [SD]) and malignant (4.34 +/- 3.19) lesions in total (P =.002). However, giant cell tumors (n = 5; SUV, 4.64 +/- 1.05) showed significantly higher SUV than chondrosarcomas (n = 7; SUV, 2.23 +/- 0.74) (P =.036, adjusted for multiple comparisons) and had no statistically significant difference in SUV compared with osteosarcomas (n = 6; SUV, 3.07 +/- 0.96) (P =.171). There was no statistically significant difference in SUV between fibrous dysplasias (n = 6; SUV, 2.05 +/- 0.98) and osteosarcoma (P =.127) or chondrosarcomas (P =.667). Although the number of cases was small, three chondroblastomas, one sarcoidosis, and one Langerhans cell histiocytosis showed levels of FDG accumulation as high as that of osteosarcomas. CONCLUSION: Radiologists should be aware of the high accumulation of FDG in some benign bone lesions, especially histiocytic or giant cell-containing lesions. Consideration of histologic subtypes should be included in analysis of SUV at FDG PET of primary bone tumors.     

Usefulness of standardized uptake value normalized by individual CT-based lean body mass in application of PET response criteria in solid tumors (PERCIST)

Our aim in this study was to verify the usefulness of the standardized uptake value (SUV) normalized by individual CT-based lean body mass (LBM_CT) in application of PET response criteria in solid tumors (PERCIST).We retrospectively investigated 14 patients (4 male and 10 female) with malignant lymphoma who were undergoing chemotherapy. ¹⁸F-FDG PET/CT examinations were performed before and after chemotherapy. The LBM_CT was calculated by estimation of fat weight from CT data (from skull base to pelvis). The mean ± standard deviation (SD) and the Bland–Altman plot were used for comparison among body weight, LBM_CT, and LBM derived from a predictive equation (LBM_PE). Indices for FDG uptake in the liver were: SUV, SUV based on LBM_PE (SUL_PE), and SUV based on LBM_CT (SUL_CT). Overall differences between the uptake values were analyzed by one-way ANOVA. If the ANOVA showed significance, differences between uptake values were investigated further by use of the Tukey–Kramer test. The mean values of body weight, LBM_PE, and LBM_CT were: 55.4 ± 14.9 (39.0–112.0), 43.0 ± 10.5 (31.3–75.2), and 35.3 ± 9.8 (23.4–75.8) kg, respectively. There was a wide dispersion between LBM_PE and LBM_CT (differences, 7.6 ± 3.6 kg; 95 % CI, 6.42–8.85). LBM_PE was higher than LBM_CT in all the cases except in Case 11. The mean uptake values significantly differed among SUV, SUL_PE, and SUL_CT (F = 68.3, p < 0.05). Whereas SUL_PE deviated from PERCIST criteria in seven patients, SUL_CT satisfied the criteria except in one case. These results suggest that liver SUL_CT is useful for application of PERCIST.     

FDG PET/CT对肝细胞癌早期动态血流和延迟标准化摄取值的测定

目的前瞻性研究18F-FDG PET/CT早期动态血流指标是否有助于发现肝细胞癌(HCC),分析有或无血管浸润的HCC特征,评价HCC在FDG PET/CT中血流与代谢的关系。材料与方法本研究经伦理委员会批准,所有病人均签署     

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.     

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.     

The use of standardized uptake values for assessing FDG uptake with PET in oncology: a clinical perspective

Among clinicians who use positron emission tomography (PET), the standardized uptake value (SUV) is a popular semi-quantitative value that can be easily assessed whenever a PET study is performed under physiological and pathological conditions. It provides an index of regional tracer uptake normalized to the administered dose of tracer. The simplicity of SUV assessment contrasts with the complexity of full quantitative procedures requiring blood sampling and possibly dynamic scanning, which limits patient throughput and significantly increases the workload of a PET centre. Two main clinical conditions/variables affect the significance and usefulness of the SUV: the type and stage of the disease being assessed. Diagnosis, prognosis and therapy monitoring represent the possible uses of SUV. In the above clinical conditions an SUV may provide information about the single lesion in which it is assessed, but the utility of such information depends largely on its integration with all the available clinical and instrumental data.     

Preoperative PET/CT FDG standardized uptake value of pelvic lymph nodes as a significant prognostic factor in patients with uterine cervical cancer

Purpose

Using integrated PET/CT, we evaluated the prognostic relevance in uterine cervical cancer of preoperative pelvic lymph node (LN) [¹⁸F]FDG uptake.

Methods

Patients with FIGO stage IB to IIA uterine cervical cancer were imaged with FDG PET/CT before radical surgery. We used Cox proportional hazards regression to examine the relationship between recurrence and the FDG maximum standardized uptake value (SUV_max) in the pelvic LN (SUV_LN) on PET/CT.

Results

Clinical data, treatment modalities, and results in 130 eligible patients were reviewed. The median postsurgical follow-up was 34 months (range 6 to 109 months). Receiver operating characteristic analysis identified SUV_LN 2.36 as the most significant cut-off value for predicting recurrence. SUV_LN was correlated with SUV_tumour (P?=?0.002), primary tumour size (P?=?0.004), and parametrial invasion (P?=?0.013). Univariate analyses showed significant associations between recurrence and SUV_LN (P?=?0.001), SUV_tumour (P?=?0.007), pelvic LN metastasis (P?=?0.002), parametrial invasion (P?<?0.001), primary tumour size (P?=?0.007), suspected LN metastasis on MRI (P?=?0.024), and FIGO stage (P?=?0.026). Multivariate analysis identified SUV_LN (P?=?0.013, hazard ratio, HR, 4.447, 95 % confidence interval, CI, 1.379 – 14.343) and parametrial invasion (P?=?0.013, HR 6.728, 95 % CI 1.497 – 30.235) as independent risk factors for recurrence. Patients with SUV_LN ≥2.36 and SUV_LN <2.36 differed significantly in terms of recurrence (HR 15.20, P?<?0.001).

Conclusion

Preoperative pelvic LN FDG uptake showed a strong significant association with uterine cervical cancer recurrence.     

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.     

Ratio of standardized uptake value on PET helps predict response and outcome after chemotherapy in advanced non-small cell lung cancer

Background  

The maximum standardized uptake value (SUV_max) on ¹⁸F-fluorodeoxyglucose-positron emission tomography (¹⁸F-FDG PET) within the primary tumor may predict outcome in patients with surgically resected non-small cell lung cancer (NSCLC). However, it remains uncertain whether the SUV_max of the primary tumor predicts outcome after chemotherapy in advanced NSCLC. Thus, we evaluated the ratio of SUV_max of the metastatic tumor to the primary tumor (M/P ratio) to determine whether it could be a useful marker in predicting response and outcome after chemotherapy in advanced NSCLC.