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

Purpose

Using integrated PET/CT, we evaluated the prognostic relevance of preoperative pelvic lymph node (LN) ¹⁸F-FDG uptake in endometrioid endometrial cancer.

Methods

We retrospectively reviewed patients with pathologically proven endometrial cancer who underwent preoperative ¹⁸F-FDG PET/CT scans to evaluate the prognostic significance of PET/CT parameters and other clinicopathological variables. We used Cox proportional hazards regression to examine the relationship between recurrence and the maximum standardized uptake value (SUV_max) in pelvic LNs (SUV_LN) on FDG PET/CT.

Results

Clinical data, treatment modalities and results were reviewed in 70 eligible patients. The median postsurgical follow-up was 29 months (range 6 to 95 months). Receiver-operating characteristic analysis identified the significant SUV_LN cut-off value as 15. The SUV_LN correlated with FIGO stage (P?<?0.001), LN metastasis (P?<?0.001), lymphovascular space invasion (P?<?0.001), SUV_tumour (P?=?0.001), metastatic LN size (P?=?0.004), primary tumour size (P?=?0.012), tumour grade (P?=?0.015) and depth of tumour invasion (P?=?0.035). Regression analysis showed a statistically significant association between recurrence and SUV_LN (P?=?0.002). Recurrence differed significantly (P?<?0.001) between patients with SUV_LN >15 and those with SUV_LN ≤15.

Conclusion

Preoperative pelvic LN FDG uptake exhibited a strong significant association with recurrence of endometrioid endometrial cancer.     

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.     

Suppression of myocardial 18F-FDG uptake with a preparatory “Atkins-style” low-carbohydrate diet

Objectives

Physiological myocardial uptake of 18F-FDG during positron emission tomography can mask adjacent abnormal uptake in mediastinal malignancy and inflammatory cardiac diseases. Myocardial uptake is unpredictable and variable. This study evaluates the impact of a low-carbohydrate diet in reducing myocardial FDG uptake.

Method

Patients attending for clinically indicated oncological FDG PET were asked to have an “Atkins-style” low-carbohydrate diet (less than 3 g) the day before examination and an overnight fast. A total of 120 patients following low-carbohydrate diet plus overnight fast were compared with 120 patients prepared by overnight fast alone. Patients having an Atkins-style diet also completed a diet compliance questionnaire. SUV_max and SUV_mean for myocardium, blood pool and liver were measured in both groups.

Results

Myocardial SUV_max fell from 3.53?±?2.91 in controls to 1.77?±?0.91 in the diet-compliant group. 98 % of diet-compliant patients had a myocardial SUV_max less than 3.6 compared with 67 % of controls. Liver and blood pool SUV_max rose from 2.68?±?0.49 and 1.82?±?0.30 in the control group to 3.14?±?0.57 and 2.06?±?0.30.

Conclusion

An Atkins-style diet the day before PET, together with an overnight fast, effectively suppresses myocardial FDG uptake.

Key Points

? Low-carbohydrate diet (LCD) the day before PET suppresses myocardial FDG uptake. ? LCD before PET increases liver and blood pool SUV _max and SUV _mean . ? Suppression of myocardial uptake may improve PET imaging of thoracic disease. ? Suppression of myocardial uptake may help imaging cardiac inflammatory disease with PET.     

Incidental pituitary uptake on whole-body 18F-FDG PET/CT: a multicentre study

Purpose

The purpose of this study was to determine the incidence of incidental pituitary uptake on whole-body ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and to investigate its clinical significance.

Methods

The files of 40,967 patients who underwent whole-body FDG PET/CT were retrospectively reviewed. Quantification of pituitary metabolic activity was obtained by using the maximum standardized uptake value (SUV_max). Hormone assays and pituitary MRIs were performed to assess pituitary lesions.

Results

Focally increased pituitary FDG uptake on PET/CT was found in 30 of 40,967 patients, accounting for an incidence of 0.073%. The mean SUV_max of 30 patients was 8.9?±?6.6 (range: 3.2–32.6). Histological diagnosis was obtained in three patients and included two growth hormone-secreting adenomas and one non-functioning adenoma. Hormone assays were performed on serum samples from 11 patients, 2 of whom were shown to have hypersecretion of pituitary hormone. MRI was performed on 19 patients. Abnormal MRI findings suggesting a pituitary mass were found in 18 of 19 cases (94.7%). The mean SUV_max calculated without correction for partial volume effect for macroadenomas was significantly higher than the SUV_max for microadenomas (11.5?±?8.4 vs 4.8?±?1.3; p?<?0.05). There were no cases diagnosed with metastasis to the pituitary gland during clinical follow-up.

Conclusion

Incidental pituitary FDG uptake was a very rare finding. Cases with incidental pituitary FDG uptake were diagnosed primarily with clinically non-functioning adenomas, and there were also a few functioning adenomas. Further evaluations, including hormone assays and pituitary MRI, are warranted when pituitary uptake is found on FDG PET/CT.     

Anatomical and functional volume concordance between FDG PET,and T2 and diffusion-weighted MRI for cervical cancer: a hybrid PET/MR study

Purpose

To evaluate the concordance among ¹⁸F-FDG PET imaging, MR T2-weighted (T2-W) imaging and apparent diffusion coefficient (ADC) maps with diffusion-weighted (DW) imaging in cervical cancer using hybrid whole-body PET/MR.

Methods

This study prospectively included 35 patients with cervical cancer who underwent pretreatment ¹⁸F-FDG PET/MR imaging. ¹⁸F-FDG PET and MR images were fused using standard software. The percent of the maximum standardized uptake values (SUV_max) was used to contour tumours on PET images, and volumes were calculated automatically. Tumour volumes measured on T2-W and DW images were calculated with standard techniques of tumour area multiplied by the slice profile. Parametric statistics were used for data analysis.

Results

FDG PET tumour volumes calculated using SUV_max (14.30?±?4.70) and T2-W imaging volume (33.81?±?27.32 cm³) were similar (P?>?0.05) at 35 % and 40 % of SUV_max (32.91?±?18.90 cm³ and 27.56?±?17.19 cm³ respectively) and significantly correlated (P?<?0.001; r?=?0.735 and 0.766). The mean DW volume was 30.48?±?22.41 cm³. DW volumes were not significantly different from FDG PET volumes at either 35 % SUV_max or 40 % SUV_max or from T2-W imaging volumes (P?>?0.05). PET subvolumes with increasing SUV_max cut-off percentage showed an inverse change in mean ADC values on DW imaging (P?<?0.001, ANOVA).

Conclusion

Hybrid PET/MR showed strong volume concordance between FDG PET, and T2-W and DW imaging in cervical cancer. Cut-off at 35 % or 40 % of SUV_max is recommended for ¹⁸F-FDG PET/MR SUV-based tumour volume estimation. The linear tumour subvolume concordance between FDG PET and DW imaging demonstrates individual regional concordance of metabolic activity and cell density.     

Metabolic parameters using 18F-FDG PET/CT correlate with occult lymph node metastasis in squamous cell lung carcinoma

Purpose

The aim of this study was to investigate predictability of occult lymph node metastasis (OLM) using metabolic parameters on pretreatment ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/CT in squamous cell non-small cell lung carcinoma (SC-NSCLC) patients who were clinically node negative (cN0) before surgery.

Methods

A total of 63 cN0 SC-NSCLC patients (M/F = 61/2, mean age 64.1?±?8.0) who underwent curative surgery with lymph node dissection were enrolled in this study. Metabolic tumor volume (MTV) of the primary tumor was obtained with a standardized uptake value (SUV) threshold of 2.5. Total lesion glycolysis (TLG) was calculated by multiplication of the MTV and its SUV_mean. Metabolic parameters (SUV_max, MTV, and TLG) and clinicopathological factors were analyzed for OLM.

Results

Of 63 patients, 12 (19.0 %) had OLM. Significantly higher SUV_max, MTV, TLG, and pathological tumor size were observed in patients with OLM. The optimal cutoff values for prediction of OLM determined using a receiver-operating characteristic (ROC) curve were 8.8 for SUV_max, 18.9 cm³ for MTV, 88.4 for TLG, and 2.8 cm for pathological tumor size. Univariate analysis showed correlation of SUV_max, MTV, and TLG with the rate of OLM. In multivariate analyses, high SUV_max and MTV showed an association with an increased risk of OLM, after adjusting for age, sex, pathological tumor size, T stage, and location.

Conclusion

Metabolic parameters on pretreatment ¹⁸F-FDG PET/CT were significant predictors for OLM in cN0 SC-NSCLC patients. Surgical planning can be tailored based on the parameters in order to reduce the risk of hidden residual lymph node metastases in patients.     

Functional imaging of lung cancer using dual energy CT: how does iodine related attenuation correlate with standardized uptake value of 18FDG-PET-CT?

Objectives

To investigate the correlation between maximum standardized uptake value (SUV_max) of ¹⁸FDG PET-CT and iodine-related attenuation (IRA) of dual energy CT (DECT) of primary tumours and ¹⁸FDG PET-CT positive thoracic lymph nodes (LN) in patients with lung cancer.

Methods

37 patients with lung cancer (27 NSCLC, 10 SCLC, 86 ¹⁸FDG PET-CT positive thoracic LN) who underwent both ¹⁸FDG PET-CT and DECT were analyzed. The mean study interval between ¹⁸FDG PET-CT and DECT was ??21?days in 17 patients. The mean and maximum IRA of DECT as well as of virtual unenhanced and virtual 120?kV images of DECT was analyzed and correlated to the SUV_max of ¹⁸FDG PET-CT in all tumours and ¹⁸FDG PET-CT positive thoracic lymph nodes. Further subgroup analysis was performed for histological subtypes in all groups.

Results

A moderate correlation was found between SUV_max and maximum IRA in all tumours (n?=?37;r?=?0.507;p?=?0.025) whereas only weak or no correlation were found between SUV_max and all other DECT measurements. A strong correlation was found in patients with study intervals ??21?days (n?=?17; r?=?0.768;p?=?0.017). Analysis of histological subtypes of lung cancer showed a strong correlation between SUV_max and maximum IRA in the analysis of all patients with NSCLC (r?=?0.785;p?=?0.001) and in patients with NSCLC and study intervals ??21?days (r?=?0.876;p?=?0.024). Thoracic LN showed moderate correlation between SUV_max and maximum IRA in patients with study intervals ??21?days (r?=?0.654; p?=?0.010) whereas a weak correlation was found between SUV_max and maximum IRA in patients with study intervals >21?days (r?=?0.299; p?=?0.035).

Conclusions

DECT could serve as a valuable functional imaging test for patients with NSCLC as the IRA of DECT correlates with SUV_max of ¹⁸FDG PET-CT.     

Predictive value of early and late residual 18F-fluorodeoxyglucose and 18F-fluorothymidine uptake using different SUV measurements in patients with non-small-cell lung cancer treated with erlotinib

Purpose

To evaluate the predictive value of early and late residual ¹⁸F-fluorodeoxyglucose (FDG) and ¹⁸F-fluorothymidine (FLT) uptake using different SUV measurements in PET in patients with advanced non-small-cell lung cancer (NSCLC) treated with erlotinib.

Methods

We retrospectively reviewed data from 30 patients with untreated stage IV NSCLC who had undergone a combined FDG PET and FLT PET scan at 1?week (early) and 6?weeks (late) after the start of erlotinib treatment. Early and late residual FDG and FLT uptake were measured in up to five lesions per scan with different quantitative standardized uptake values (SUV_max, SUV_2Dpeak, SUV_3Dpeak, SUV₅₀, SUV_A50, SUV_A41) and compared with short-term outcome (progression vs. nonprogression after 6?weeks of erlotinib treatment). Receiver-operating characteristics (ROC) curve analysis was used to determine the optimal cut-off value for detecting nonprogression after 6?weeks. Kaplan-Meier analysis and the log-rank test were used to evaluate the association between residual uptake and progression-free survival (PFS).

Results

Nonprogression after 6?weeks was associated with a significantly lower early and late residual FDG uptake, measured with different quantitative parameters. In contrast, nonprogression after 6?weeks was not associated with early and late residual FLT uptake. Furthermore, patients with a lower early residual FDG uptake measured in terms of SUV_max and SUV_2Dpeak had a significantly prolonged PFS (282?days vs. 118?days; p?=?0.022) than patients with higher values. Similarly, lower late residual FDG uptake and early residual FLT uptake measured in terms of SUV_3Dpeak, SUV_A50 and SUV_A41, and late FLT uptake measured in terms of SUV_3Dpeak and SUV_A50 was associated with an improved PFS.

Conclusion

Early and late residual FDG uptake, measured using different quantitative SUV parameters, are predictive factors for short-term outcome in patients with advanced NSCLC treated with erlotinib. Additionally, low residual FDG and FLT uptake early and late in the course of erlotinib treatment is associated with improved PFS.     

Lesion-based detection of early chemosensitivity using serial static FDG PET/CT in metastatic colorectal cancer

Purpose

Medical oncology needs early identification of patients that are not responding to systemic therapy. ¹⁸F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) performed before and early during treatment has been proposed for this purpose. However, the best way to assess the change in FDG uptake between two scans has not been identified. We studied cutoff thresholds to identify responding tumours as a function of the method used to measure tumour uptake.

Methods

The study included 28 metastatic colorectal cancer (mCRC) patients who underwent 2 FDG PET/CT scans (baseline and at day 14 of the first course of polychemotherapy). For 78 tumour lesions, 4 standardized uptake value (SUV) indices were measured: maximum SUV (SUV_max) and mean SUV in a region obtained using an isocontour (SUV_40?%), with each of these SUV normalized either by the patient body weight (BW) or body surface area (BSA). The per cent change and absolute change in tumour uptake between the baseline and the early PET scans were measured based on these four indices. These changes were correlated to the RECIST 1.0-based response using contrast-enhanced CT at baseline and at 6–8?weeks on treatment.

Results

The 78 tumours were classified as non-responding (NRL, n?=?58) and responding lesions (RL, n?=?20). Receiver-operating characteristic (ROC) curves characterizing the performance in NRL/RL classification using early FDG PET uptake had areas under the curve between 0.75 and 0.84, without significant difference between the indices. The cutoff threshold in FDG uptake per cent change to get a 95?% sensitivity of RL detection depended on the way uptake was measured: ?14?% (specificity of 53?%) and ?22?% (specificity of 64?%) for SUV_max and SUV_40?%, respectively. Thresholds expressed as absolute SUV decrease instead of per cent change were less sensitive to the SUV definition: an SUV decline by 1.2 yielded a sensitivity of RL detection of 95?% for SUV_max and SUV_40?%. For a given cutoff threshold, the sensitivity was the same whatever the normalization (by BSA or BW).

Conclusion

A 14?% drop of tumour FDG SUV_max, 22?% drop of SUV_40?% or 1.2 drop of SUV_max or SUV_mean after one single course of polychemotherapy predicts objective response in mCRC lesions with a high sensitivity, potentially allowing the early identification of non-responding patients.     

18F-FDG uptake in breast cancer correlates with immunohistochemically defined subtypes

Objectives

To determine whether a correlation exists between maximum standardized uptake value (SUV_max) on ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) and the subtypes of breast cancer.

Methods

This retrospective study involved 548 patients (mean age 51.6 years, range 21–81 years) with 552 index breast cancers (mean size 2.57 cm, range 1.0–14.5 cm). The correlation between ¹⁸F-FDG uptake in PET/CT, expressed as SUV_max, and immunohistochemically defined subtypes (luminal A, luminal B, human epidermal growth factor receptor 2 (HER2) positive and triple negative) was analyzed.

Results

The mean SUV_max value of the 552 tumours was 6.07?±?4.63 (range 0.9–32.8). The subtypes of the 552 tumours were 334 (60 %) luminal A, 66 (12 %) luminal B, 60 (11 %) HER2 positive and 92 (17 %) triple negative, for which the mean SUV_max values were 4.69?±?3.45, 6.51?±?4.18, 7.44?±?4.73 and 9.83?±?6.03, respectively. In a multivariate regression analysis, triple-negative and HER2-positive tumours had 1.67-fold (P?<?0.001) and 1.27-fold (P?=?0.009) higher SUV_max values, respectively, than luminal A tumours after adjustment for invasive tumour size, lymph node involvement status and histologic grade.

Conclusion

FDG uptake was independently associated with subtypes of invasive breast cancer. Triple-negative and HER2-positive breast cancers showed higher SUV_max values than luminal A tumours.

Key Points

? ¹⁸ F-FDG PET demonstrates increased tissue glucose metabolism, a hallmark of cancers. ? Immunohistochemically defined subtypes appear significantly associated with FDG uptake (expressed as SUV _max ). ? Triple-negative tumours had 1.67-fold higher SUV _max values than luminal A tumours. ? HER2-positive tumours had 1.27-fold higher SUV _max values than luminal A tumours.     

Association of primary tumour FDG uptake with clinical, histopathological and molecular characteristics in breast cancer patients scheduled for neoadjuvant chemotherapy

Purpose

The aim of this study was to evaluate the association of primary tumour ¹⁸F-fluorodeoxyglucose (FDG) uptake with clinical, histopathological and molecular characteristics of breast cancer patients scheduled for neoadjuvant chemotherapy. Second, we wished to establish for which patients pretreatment positron emission tomography (PET)/CT could safely be omitted because of low FDG uptake.

Methods

PET/CT was performed in 214 primary stage II or III breast cancer patients in the prone position with hanging breasts. Tumour FDG uptake was qualitatively evaluated to determine the possibility of response monitoring with PET/CT and was quantitatively assessed using maximum standardized uptake values (SUV_max). FDG uptake was compared with age, TNM stage, histology, hormone and human epidermal growth factor receptor 2 status, grade, Ki-67 and molecular subtype in univariable and multivariable analyses.

Results

In 203 tumours (95?%) FDG uptake was considered sufficient for response monitoring. No subgroup of patients with consistently low tumour FDG uptake could be identified. In a univariable analysis, SUV_max was significantly higher in patients with distant metastases at staging examination, non-lobular carcinomas, tumours with negative hormone receptors, triple negative tumours, grade 3 tumours, and in tumours with a high proliferation index (Ki-67 expression). After multiple linear regression analysis, triple negative and grade 3 tumours were significantly associated with a higher SUV_max.

Conclusion

Primary tumour FDG uptake in breast cancer patients scheduled for neoadjuvant chemotherapy is significantly higher in tumours with prognostically unfavourable characteristics. Based on tumour characteristics associated with low tumour FDG uptake, this study was unable to identify a subgroup of patients unlikely to benefit from pretreatment PET/CT.     

Assessment of aortitis by semiquantitative analysis of 180-min 18F-FDG PET/CT acquisition images

Purpose

The aim of this study was to evaluate the contribution of semiquantitative analysis of 180-min ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT images for the assessment of aortitis in cases of suspected large vessel vasculitis (LVV) and to establish a threshold index for application in the clinical setting.

Methods

This prospective study included 43 patients (mean age 67.5?±?12.9?years) with suspicion of LVV (25 with a final diagnosis of aortitis). ¹⁸F-FDG PET/CT scan was acquired 180 min after injection of 7 MBq/kg of ¹⁸F-FDG. A semiquantitative analysis was performed calculating the aortic wall maximum standardized uptake value (SUV_max) (T), the lumen SUV_max (B) and the target to background ratio (TBR). These results were also compared with those obtained in a control population.

Results

The mean aortic wall SUV_max was 2.00?±?0.62 for patients with aortitis and 1.45?±?0.31 for patients without aortitis (p?p?max (0.997 vs 0.871). The highest sensitivity and specificity was obtained for a TBR of 1.34 (sensitivity 100 %, specificity 94.4 %).

Conclusion

Semiquantitative analysis of PET/CT images acquired 180 min after ¹⁸F-FDG injection and the TBR index of 1.34 show very high accuracy and, therefore, are strongly recommended for the diagnosis of aortitis in the clinical setting.     

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.     

Correlation of breast cancer subtypes,based on estrogen receptor,progesterone receptor,and HER2, with functional imaging parameters from 68Ga-RGD PET/CT and 18F-FDG PET/CT

Purpose

Imaging biomarkers from functional imaging modalities were assessed as potential surrogate markers of disease status. Specifically, in this prospective study, we investigated the relationships between functional imaging parameters and histological prognostic factors and breast cancer subtypes.

Methods

In total, 43 patients with large or locally advanced invasive ductal carcinoma (IDC) were analyzed (47.6?±?7.5 years old). ⁶⁸Ga-Labeled arginine-glycine-aspartic acid (RGD) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) were performed. The maximum and average standardized uptake values (SUV_max and SUV_avg) from RGD PET/CT and SUV_max and SUV_avg from FDG PET/CT were the imaging parameters used. For histological prognostic factors, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression was identified using immunohistochemistry (IHC) or fluorescent in situ hybridization (FISH). Four breast cancer subtypes, based on ER/PR and HER2 expression (ER/PR+,Her2?, ER/PR+,Her2+, ER/PR?,Her2+, and ER/PR?,Her2?), were considered.

Results

Quantitative FDG PET parameters were significantly higher in the ER-negative group (15.88?±?8.73 vs 10.48?±?6.01, p?=?0.02 for SUV_max; 9.40?±?5.19 vs 5.92?±?4.09, p?=?0.02 for SUV_avg) and the PR-negative group (8.37?±?4.94 vs 4.79?±?3.93, p?=?0.03 for SUV_avg). Quantitative RGD PET parameters were significantly higher in the HER2-positive group (2.42?±?0.59 vs 2.90?±?0.75, p?=?0.04 for SUV_max; 1.60?±?0.38 vs 1.95?±?0.53, p?=?0.04 for SUV_avg) and showed a significant positive correlation with the HER2/CEP17 ratio (r?=?0.38, p?=?0.03 for SUV_max and r?=?0.46, p?<?0.01 for SUV_avg). FDG PET parameters showed significantly higher values in the ER/PR?,Her2? subgroup versus the ER/PR+,Her2? or ER/PR+,Her2+ subgroups, while RGD PET parameters showed significantly lower values in the ER/PR?,Her2? subgroup versus the other subgroups. There was no correlation between FDG and RGD PET parameters in the overall group. Only the ER/PR?,Her2? subgroup showed a significant positive correlation between FDG and RGD PET parameters (r?=?0.59, p?=?0.03 for SUV_max).

Conclusion

⁶⁸Ga-RGD and ¹⁸F-FDG PET/CT are promising functional imaging modalities for predicting biomarkers and molecular phenotypes in breast cancer patients.     

The impact of systemic chemotherapy on testicular FDG activity in young men with Hodgkin’s lymphoma

Purpose

Based on prior reports suggesting a positive correlation between fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET)/CT and total sperm count and concentration, we sought to identify changes in testicular FDG uptake over the course of chemotherapy in young men with Hodgkin’s lymphoma.

Methods

Fifty-two patients with a mean age of 24.2 years (range 15.5–44.4) at diagnosis monitored with FDG PET/CT to assess treatment response for Hodgkin’s lymphoma were selected for this retrospective analysis under an Institutional Review Board waiver. Of the patients, 26 were treated with a chemotherapy regimen known to cause prolonged and sometimes permanent azoospermia (BEACOPP—bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisolone) and 26 with a regimen known to have a much milder effect on gonadal function (ABVD—doxorubicin, bleomycin, vincristine, and dacarbazine). Each patient underwent one FDG PET/CT before treatment and at least one FDG PET/CT after start of chemotherapy. In all examinations, FDG activity was measured in the testes with different quantification metrics: maximum standardized uptake value (SUV_max), SUV_mean, functional volume (FV) and total testicular glycolysis (TTG), and blood pool activity determined (SUV_mean).

Results

Testicular FDG uptake (SUV_max) was significantly associated with blood pool activity (p?<?0.001). Furthermore, testicular FDG uptake metrics incorporating volume (e.g., FV and TTG) were associated with age. There was no significant change in SUV_max, SUV_mean, FV, and TTG from the PET/CT at baseline to the PET/CTs over the course of chemotherapy either for patients treated with BEACOPP or for patients treated with ABVD.

Conclusion

For patients undergoing chemotherapy for Hodgkin’s lymphoma, there is a significant association between testicular FDG uptake and blood pool activity, but no significant changes in FDG uptake over the course of chemotherapy. Therefore, FDG uptake may not be a feasible surrogate marker for fertility monitoring in patients with Hodgkin’s lymphoma undergoing chemotherapy.     

PET/MRI in head and neck cancer: initial experience

Purpose

To evaluate the feasibility of PET/MRI (positron emission tomography/magnetic resonance imaging) with FDG (¹⁸F-fluorodeoxyglucose) for initial staging of head and neck cancer.

Methods

The study group comprised 20 patients (16 men, 4 women) aged between 52 and 81?years (median 64?years) with histologically proven squamous cell carcinoma of the head and neck region. The patients underwent a PET scan on a conventional scanner and a subsequent PET/MRI examination on a whole-body hybrid system. FDG was administered intravenously prior to the conventional PET scan (267?C395?MBq FDG, 348?MBq on average). The maximum standardized uptake values (SUV_max) of the tumour and of both cerebellar hemispheres were determined for both PET datasets. The numbers of lymph nodes with increased FDG uptake were compared between the two PET datasets.

Results

No MRI-induced artefacts where observed in the PET images. The tumour was detected by PET/MRI in 17 of the 20 patients, by PET in 16 and by MRI in 14. The PET/MRI examination yielded significantly higher SUV_max than the conventional PET scanner for both the tumour (p?<?0.0001) and the cerebellum (p?=?0.0009). The number of lymph nodes with increased FDG uptake detected using the PET dataset from the PET/MRI system was significantly higher the number detected by the stand-alone PET system (64 vs. 39, p?=?0.001).

Conclusion

The current study demonstrated that PET/MRI of the whole head and neck region is feasible with a whole-body PET/MRI system without impairment of PET or MR image quality.     

Predictive value of pre-therapy 18F-FDG PET/CT for the outcome of 18F-FDG PET-guided radiotherapy in patients with head and neck cancer

Purpose

The aim of this study was to evaluate the predictive role of pre-therapy fluorodeoxyglucose (FDG) uptake parameters of primary tumour in head and neck cancer (HNC) patients undergoing intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) on FDG-positive volume—positron emission tomography (PET) gross tumour volume (PET-GTV).

Methods

This retrospective study included 19 patients (15 men and 4 women, mean age 59.2 years, range 23–81 years) diagnosed with HNC between 2005 and 2011. Of 19 patients, 15 (79 %) had stage III–IV. All patients underwent FDG PET/CT before treatment. Metabolic indexes of primary tumour, including metabolic tumour volume (MTV), maximum and mean standardized uptake value (SUV_max, SUV_mean) and total lesion glycolysis (TLG) were considered. Partial volume effect correction (PVC) was performed for SUV_mean and TLG estimation. Correlations between PET/CT parameters and 2-year disease-free survival (DFS), local recurrence-free survival (LRFS) and distant metastasis-free survival (DMFS) were assessed. Median patient follow-up was 19.2 months (range 4–24 months).

Results

MTV, TLG and PVC-TLG predicting patients’ outcome with respect to all the considered local and distant disease control endpoints (LRFS, DMFS and DFS) were 32.4 cc, 469.8 g and 547.3 g, respectively. SUV_mean and PVC-SUV_mean cut-off values predictive of LRFS and DFS were 10.8 and 13.3, respectively. PVC was able to compensate errors up to 25 % in the primary HNC tumour uptake. Moreover, PVC enhanced the statistical significance of the results.

Conclusion

FDG PET/CT uptake parameters are predictors of patients’ outcome and can potentially identify patients with higher risk of treatment failure that could benefit from more aggressive approaches. Application of PVC is recommended for accurate measurement of PET parameters.     

Application of Quantitative Indexes of FDG PET to Treatment Response Evaluation in Indolent Lymphoma

Purpose

Although ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a standard imaging modality for response evaluation in FDG-avid lymphoma, there is a controversy using FDG PET in indolent lymphoma. The purpose of this study was to investigate the effectiveness of quantitative indexes on FDG PET in response evaluation of the indolent lymphoma.

Methods

Fifty-seven indolent lymphoma patients who completed chemotherapy were retrospectively enrolled. FDG PET/computed tomography (CT) scans were performed at baseline, interim, and end of treatment (EOT). Response was determined by Lugano classification, and progression-free survival (PFS) by follow-up data. Maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured in the single hottest lesion (target A) or five hottest lesions (target B). Their efficacies regarding response evaluation and PFS prediction were evaluated.

Results

On EOT PET, SUV_max, and MTV of both targets were well associated with visual analysis. Changes between initial and EOT PET were not significantly different between CR and non-CR groups. On interim PET, SUV_max, and %ΔSUV_max in both targets were significantly different between CR and non-CR groups. For prediction of PFS, most tested indexes were significant on EOT and interim PET, with SUV_max being the most significant prognostic factor.

Conclusion

Quantitative indexes of FDG PET are well associated with Lugano classification in indolent lymphoma. SUV_max measured in the single hottest lesion can be effective in response evaluation and prognosis prediction on interim and EOT PET.

     

Dual-time-point [18F]-FDG PET/CT in the diagnostic evaluation of suspicious breast lesions

Purpose

The authors sought to evaluate whether the reacquisition of images 3 h after administration of radiotracer improves the sensitivity of fluorine-18 fluorodeoxyglucose positron emission tomography computed tomography ([¹⁸F]-FDG PET/CT) in patients with suspicious breast lesions.

Materials and methods

Forty-eight patients with 59 breast lesions underwent an [¹⁸F]-FDG PET/CT study in the prone position with a dual-time-point acquisition performed in the early phase 1 h after FDG administration (PET-1) and in the delayed phase 3 h after FDG administration (PET-2). Both examinations were evaluated qualitatively and semiquantitatively with calculation of the mean percentage variation of the standard uptake values (Δ% SUV_max) between PET-1 and PET-2. All lesions with an SUV_max ≥2.5 at PET-1 or a reduction in SUV between PET-1 and PET-2 were considered benign. The definitive histopathological diagnosis was available for all patients included in the study.

Results

The dual-time-point acquisition of [¹⁸F]-FDG PET/CT displayed an accuracy of 85% for lesions with an SUV_max ≥2.5 and/or positive Δ% SUV_max, with sensitivity and specificity values of 81% and 100% compared with 69%, 63% (both p<0.001) and 100% (p=n.s.), respectively, for the single-time-point acquisition. Malignant lesions showed an increase in FDG uptake between PET-1 and PET-2, with a Δ% SUV_max of 10±7 (p<0.04). In contrast, benign lesions showed a decrease in SUV between PET-1 and PET-2, with aΔ% SUV_max of ?21±7 (p<0.001).

Conclusions

The delayed repeat acquisition of PET images improves the accuracy of [¹⁸F]-FDG PET/CT in patients with suspicious breast lesions with respect to the single-time-point acquisition. In addition, malignant breast lesions displayed an increase in FDG uptake over time, whereas benign lesions showed a reduction. These variations in FDG uptake between PET-1 and PET-2 are a reliable parameter that can be used for differentiating between benign and malignant breast lesions.     

The distribution of FDG at PET examinations constitutes a relative mechanism: significant effects at activity quantification in patients with a high muscular uptake

Purpose

At ¹⁸F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) examinations a high tracer uptake of the skeletal muscles is sometimes encountered which can lead to reduced uptake in pathological lesions. This was evaluated in retrospect in patients being recalled for a repeat examination after reducing the muscular uptake.

Methods

Ten patients with increased muscular tracer uptake were examined with FDG PET/CT on two occasions with a mean of 6?days. All patients showed at least one pathological lesion with increased tracer uptake. The muscular uptake was reduced at the second examination by informing the patient to refrain from physical activity together with pretreatment with diazepam. The maximum standardized uptake value (SUV_max) of the pathological lesion and SUV_mean of certain skeletal muscles, liver, spleen, lungs, blood and certain bone marrow portions were calculated.

Results

In all patients, the muscular uptake was reduced to a normal level at visual evaluation as well as at comparison of SUVs with 25 consecutive clinical patients exhibiting a normal FDG distribution (p?<?0.001). The mean lesion SUV_max increased from 2.4 to 3.7 (54?%) between the examinations (p?<?0.05). All reference tissues/organs showed a significant increase of SUV at the second examination. Relating lesion SUV_max to the activity of any of the reference tissues/organs there was no significant difference between the studies.

Conclusion

The distribution of FDG constitutes a relative mechanism. This must be especially considered at longitudinal examinations in the same patient at therapy evaluations. In examinations with a somehow distorted general distribution of the activity, it may be more relevant to relate the lesion activity to a reference tissue/organ than relying on SUV assessments.