A threshold method to improve standardized uptake value reproducibility

3'-[18F]fluoro-3'-deoxythymidine ([18F]FLT) Positron Emission Tomography as an In Vivo Biomarker of inhibition of CDK 4/6-Rb pathway by Palbociclib in a patient derived bladder tumor

Background

Several new generation CDK4/6 inhibitors have been developed and approved for breast cancer therapy in combination with endocrine therapeutics. Application of these inhibitors either alone or in combination in other solid tumors has been proposed, but no imaging biomarkers of response have been reported in non-breast cancer animal models. The purpose of this study was to evaluate 3'-[¹⁸F]fluoro-3'-deoxythymidine ([¹⁸F]FLT) Positron Emission Tomography (PET) as in vivo biomarker of response to palbociclib in a non-breast cancer model.

Methods

Twenty-four NSG mice bearing patient derived xenografts (PDX) of a well-characterized bladder tumor were randomized into 4 treatment groups: vehicle (n = 6); palbociclib (n = 6); temozolomide (n = 6); and palbociclib plus temozolomide (n = 6) and treated with two cycles of therapy or vehicle. Tumor uptake of [¹⁸F]FLT was determined by micro-PET/CT at baseline, 3 days, and 9 days post initiation of therapy. Following the second cycle of therapy, the mice were maintained until their tumors reached a size requiring humane termination.

Results

[¹⁸F]FLT uptake decreased significantly in the palbociclib and combination arms (p = 0.0423 and 0.0106 respectively at day 3 and 0.0012 and 0.0031 at day 9) with stable tumor volume. In the temozolomide arm [¹⁸F]FLT uptake increased with day 9 uptake significantly different than baseline (p = 0.0418) and progressive tumor growth was observed during the treatment phase. All groups exhibited progressive disease after day 22, 10 days following cessation of therapy.

Conclusion

Significant decreases in [¹⁸F]FLT uptake as early as three days post initiation of therapy with palbociclib, alone or in combination with temozolomide, in this bladder cancer model correlates with an absence of tumor growth during therapy that persists until day 18 for the palbociclib group and day 22 for the combination group (6 days and 10 days) following cessation of therapy. These results support early modulation of [¹⁸F]FLT as an in vivo biomarker predictive of palbociclib therapy response in a non-breast cancer model.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03580-8.

Combination of 18F-FDG PET/CT and convex probe endobronchial ultrasound elastography for intrathoracic malignant and benign lymph nodes prediction

Background

Positron emission tomography–computed tomography (PET/CT) and convex probe endobronchial ultrasound (CP-EBUS) elastography are important diagnostic methods in predicting intrathoracic lymph nodes (LNs) metastasis, but a joint analysis of the two examinations is still lacking. This study aimed to compare the diagnostic efficiency of the two methods and explore whether the combination can improve the diagnostic efficiency in differentiating intrathoracic benign LNs from malignant LNs.

Materials and Methods

LNs examined by EBUS-guided transbronchial needle aspiration (EBUS-TBNA) and PET/CT from March 2018 to June 2019 in Shanghai Chest Hospital were retrospectively analyzed as the model group. Four PET/CT parameters, namely, maximal standardized uptake value mean standardized uptake value (SUVmean), SUVmean, metabolic tumor volume (MTV), and tumor lesion glycolysis (TLG); four quantitative elastography indicators (stiff area ratio, mean hue value, RGB, and mean gray value); and the elastography grading score of targeted LNs were analyzed. A prediction model was constructed subsequently and the dataset from July to November 2019 was used to validate the diagnostic capability of the model.

Results

A total of 154 LNs from 135 patients and 53 LNs from 47 patients were enrolled in the model and validation groups, respectively. Mean hue value and grading score were independent malignancy predictors of elastography, as well as SUVmax and TLG of PET/CT. In model and validation groups, the combination of PET/CT and elastography demonstrated sensitivity, specificity, positive and negative predictive values, and accuracy for malignant LNs diagnosis of 85.87%, 88.71%, 91.86%, 80.88%, and 87.01%, and 94.44%, 76.47%, 89.47%, 86.67%, and 88.68%, respectively. Moreover, elastography had better diagnostic accuracies than PET/CT in both model and validation groups (85.71% vs. 79.22%, 86.79% vs. 75.47%).

Conclusion

EBUS elastography demonstrated better efficiency than PET/CT and the combination of the two methods had the best diagnostic efficacy in differentiating intrathoracic benign from malignant LNs, which may be helpful for clinical application.

Intrapatient variability of 18F-FDG uptake in normal tissues

Objectives

To investigate the effect of serum glucose level and other confounding factors on the variability of maximum standardized uptake value (SUVmax) in normal tissues within the same patient on two separate occasions and to suggest an ideal reference tissue.

Materials and Methods

We retrospectively reviewed 334 18F-FDG PET/CT scans of 167 cancer patients including 38 diabetics. All patients had two studies, on average 152 ± 68 days apart. Ten matched volumes of interest were drawn on the brain, right tonsil, blood pool, heart, lung, liver, spleen, bone marrow, fat, and iliopsoas muscle opposite third lumber vertebra away from any pathological 18F-FDG uptake to calculate SUVmax.

Results

SUVmax of the lungs and heart were significantly different in the two studies (P = 0.003 and P = 0.024 respectively). Only the brain uptake showed a significant moderate negative correlation with the level of blood glucose in diabetic patients (r = −0.537, P = 0.001) in the first study, while the SUVmax of other tissues showed negligible or weak correlation with the level of blood glucose in both studies.

The liver showed significant moderate positive correlation with body mass index (BMI) in both studies (r = .416, P = <0.001 versus r = 0.453, P = <0.001, respectively), and blood pool activity showed significant moderate positive correlation with BMI in the first study only (r = 0.414, P = <0.001). The liver and blood pool activities showed significant moderate negative correlation with 18F-FDG uptake time in first study only (r = −0.405, P-value = <0.001; and r = −0.409, P-value = <0.001, respectively).

In the multivariate analysis, the liver showed a consistent effect of the injected 18F-FDG dose and uptake duration on its SUVmax on the two occasions. In comparison, spleen and muscle showed consistent effect only of the injected dose on the two occasions.

Conclusion

The liver, muscle, and splenic activities showed satisfactory test/retest stability and can be used as reference activities. The spleen and muscle appear to be more optimal reference than the liver, as it is only associated with the injected dose of 18F-FDG.

The clinical consequences of functional adrenal uptake in the absence of cross-sectional mass on FDG-PET/CT in oncology patients

PURPOSE

Oncology patients undergoing positron emission tomography/computed tomography (PET/CT) occasionally show discrete adrenal [18F]-fluorodeoxyglucose (FDG) uptake without an associated nodule on CT, leaving the clinician uncertain about the need to proceed with biopsy or surgical referral. This study aimed to identify the prevalence of this radiological finding and to evaluate the effectiveness of FDG uptake values in risk stratification for adrenal metastasis.

METHODS

From 2014 to 2015, oncology patients who underwent FDG-PET/CT and demonstrated elevated FDG uptake in the adrenal gland without discrete nodularity on cross-sectional imaging were included in a retrospective cohort analysis. Clinical records and FDG-PET/CT scans were reviewed for clinicopathological data, follow-up data, SUVmax (highest SUV of either adrenal gland), and SUVratio (SUVmax/background liver uptake). A receiver operating characteristic analysis was conducted to evaluate the associations between SUV values and the progression to adrenal metastasis.

RESULTS

Of 3040 oncology patients who underwent FDG-PET/CT scans, 92 (3.0%) showed elevated adrenal uptake without associated mass. From the final study cohort of 66 patients with comprehensive follow-up data, 5 patients (7.6%) developed evidence of adrenal metastasis. At SUVmax < 3.25 (AUC = 0.757) and SUVratio < 1.27 (AUC = 0.907), 34.8% and 60.6% of patients could be excluded with 100% negative predictive value, respectively.

CONCLUSIONS

Thresholds of SUVmax and SUVratio identified a significant proportion of patients who did not develop adrenal metastasis. In oncology patients who demonstrate increased adrenal FDG uptake without a discrete lesion on FDG-PET/CT, quantitative uptake values may be useful in selecting those not at risk of developing adrenal metastatic disease.

Is SUV Corrected for Lean Body Mass Superior to SUV of Body Weight in 68Ga-PSMA PET/CT?

Objectives:

This study aimed to investigate the relationship between the standard uptake value (SUV) of body weight and SUV corrected for lean body mass (SUL) parameters obtained from the prostate gland in gallium-68 (⁶⁸Ga)-prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET/CT) with Gleason grade (GG) groups, D’Amico risk groups, and presence of metastases.

Methods:

Patients with prostate adenocarcinoma who underwent ⁶⁸Ga-PSMA PET/CT for staging at our center between February 2017 and October 2018 were evaluated retrospectively. Maximum SUV (SUV_max), SUV_peak, SUL_max, SUL_peak, SUV_mean, and SUL_mean values of the prostate tumor were obtained. The difference in these values between GG groups (≥3, <3) and D’Amico risk (low-moderate/high) groups was evaluated with the Mann-Whitney U test. The area under the curve values of SUV and SUL parameters were compared. In addition, SUV_mean and SUL_mean values were obtained from the right liver lobe, and their correlation with body weight was evaluated.

Results:

A total of 79 patients were included in the study. Significant differences were found in the prostate SUV_max, SUL_max, SUV_peak, SUL_peak, SUV_mean, and SUL_mean values between the GG (≥3 and <3) groups and between D’Amico risk (low-moderate and high) groups. However, no significant difference was found in the discriminative power of any SUV or SUL parameter when compared with each other. A significant difference in any SUV and SUL parameters was found in patients with and without metastasis. Neither liver SUV_mean value nor SUL_mean value correlated with the body weight.

Conclusion:

The superiority of SUL values obtained from ⁶⁸Ga-PSMA PET to SUV was not determined in our study. SUV parameters can also be used for quantitative analysis in ⁶⁸Ga-PSMA PET.

Accuracy Assessment of SUV Measurements in SPECT/CT: A Phantom Study

Advances in iterative image reconstruction enable absolute quantification of SPECT/CT studies by incorporating compensations for collimator-detector response, attenuation, and scatter. This study aimed to assess the quantitative accuracy of SPECT/CT based on different levels of ^99mTc activity (low/high) using different SUV metrics (SUV_mean, SUV_max, SUV_{0.6 max}, and SUV_{0.75 max} [the average values that include pixels greater than 60% and 75% of the SUV_max in the volume of interest, respectively]). Methods: A Jaszczak phantom equipped with 6 fillable spheres was set up with low and high activity ratios of 1:4 and 1:10 (background-to-sphere) on background activities of 10 and 60 kBq/mL, respectively. The fixed-size volume of interest based on the diameter of each sphere was drawn on SPECT images using various metrics for SUV quantification purposes. Results: The convergence of activity concentration was dependent on the number of iterations and application of postfiltering. For the background-to-sphere ratio of 1:10 with a low background activity concentration, the SUV_mean metric showed an underestimation of about 38% from the actual SUV, and SUV_max exhibited an overestimation of about 24% for the largest sphere diameter. Meanwhile, bias reductions of as much as -6% and -7% for SUV_{0.6 max} and SUV_{0.75 max}, respectively, were observed. SUV_max gave a more accurate reading than the others, although points that exceeded the actual value were detected. At 1:4 and 1:10 background activity of 10 kBq/mL, a low activity concentration attained a value close to the actual ratio. Use of 2 iterations and 10 subsets without postfiltering gave the most accurate values for reconstruction and the best image overall. Conclusion: SUV_max is the best metric in a high- or low-contrast-ratio phantom with at least 2 iterations, 10 subsets, and no postfiltering.

The prognostic value of tumor/lymph node standardized uptake value max ratio and correlation with hematologic parameters in stage III nonsmall cell lung cancer

Stage III non-small cell lung cancer (NSCLC) is a highly heterogeneous subtype of lung cancer. There are still no widely accepted prognostic parameters for stage III NSCLC. In this study, we evaluated the prognostic value of the standardized uptake value (SUV) max ratio of primary tumor to lymph node (T/N SUV max) and its correlation with various hematological parameters.Patient data were reviewed from the hospital database retrospectively. The T/N SUV max ratio was calculated by dividing the SUV max of the primary tumor by the maximal SUV max of the lymph node. The cut-off value for T/N SUV max ratio was determined by receiver operating characteristic analysis. Survival analysis was performed by Kaplan-Meier method with the Long-rank test. P value < .05 was considered statistically significant.A total of 52 patients were included in this study. The optimal cut-off value for T/N SUV max was 1.96 (area under the curve: 0.74; 72.7% sensitivity and 73.7% specificity). Patients with T/N SUV max ≤1.96 were defined as high risk patients and those with >1.96 were defined as low risk patients. The median event (recurrence or progression) free survival was 24.3 months (95% confidence interval: 12.0-36.6) for low risk patients, and 9.2 months (95% confidence interval: 6.1-12.4) for high risk patients (P = .0015). There was an inverse correlation between T/N SUV max and hemoglobin concentration and mean corpuscular volume (rho: -0.349, P = .011; rho: -0.312, P = .025, respectively).Low risk patients had a more favorable prognosis compared to high risk patients. We demonstrated that T/N SUV max can be of prognostic value in stage III NSCLC. T/N SUV max correlated only with hemoglobin and mean corpuscular volume.

Predictions of Pathological Features and Recurrence Based on FDG-PET Findings of Esophageal Squamous Cell Carcinoma after Trimodal Therapy

BACKGROUND

The degree of metabolic activity in tumor cells can be determined by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET). Associations between FDG uptake by primary tumors of locally advanced esophageal squamous cell carcinoma (ESCC) under trimodal therapy and the pathological features of such tumors have not been fully investigated.

PATIENTS AND METHODS

We evaluated relationships between the maximal standardized uptake (SUVmax) in primary tumors on preoperative PET images and pathological features as well as cancer recurrence in 143 patients with ESCC who underwent neoadjuvant chemoradiotherapy (NCRT) followed by surgery.

RESULTS

The post-SUVmax significantly differed after NCRT for ypT and ypN status, lymphatic invasion (LI), venous invasion (VI), and recurrence. Furthermore, the %ΔSUVmax (rate of decrease between before and after NCRT) for LI, VI, and recurrence significantly differed. Univariate and multivariate analyses selected post-SUVmax and %ΔSUVmax as independent preoperative predictors of recurrence-free survival [hazard ratio (HR) 1.46; 95% confidence interval (CI) 1.24-1.72 and HR 0.97; 95% CI 0.96-0.99, respectively; p < 0.001 for both]. Recurrence-free and overall survival were significantly stratified according to optimal SUVmax cutoffs for predicting recurrence (post- and %ΔSUVmax: 2.8 and 70, respectively).

CONCLUSIONS

The post- and %ΔSUVmax of primary tumors were significantly associated with the pathological features and recurrence of ESCC under trimodal therapy. Therefore, FDG-PET can preoperatively predict the degree of aggressive tumor behavior in ESCC under trimodal therapy.

Interobserver reproducibility of tumor uptake quantification with 89Zr-immuno-PET: a multicenter analysis

PURPOSE

In-vivo quantification of tumor uptake of 89-zirconium (⁸⁹Zr)-labelled monoclonal antibodies (mAbs) with PET provides a potential tool in strategies to optimize tumor targeting and therapeutic efficacy. A specific challenge for ⁸⁹Zr-immuno-PET is low tumor contrast. This is expected to result in interobserver variation in tumor delineation. Therefore, the aim of this study was to determine interobserver reproducibility of tumor uptake measures by tumor delineation on ⁸⁹Zr-immuno-PET scans.

METHODS

Data were obtained from previously published clinical studies performed with ⁸⁹Zr-rituximab, ⁸⁹Zr-cetuximab and ⁸⁹Zr-trastuzumab. Tumor lesions on ⁸⁹Zr-immuno-PET were identified as focal uptake exceeding local background by a nuclear medicine physician. Three observers independently manually delineated volumes of interest (VOI). Maximum, peak and mean standardized uptake values (SUV_max, SUV_peak and SUV_mean) were used to quantify tumor uptake. Interobserver variability was expressed as the coefficient of variation (CoV). The performance of semi-automatic VOI delineation using 50% of background-corrected AC_peak was described.

RESULTS

In total, 103 VOI were delineated (3-6 days post injection (D3-D6)). Tumor uptake (median, interquartile range) was 9.2 (5.2-12.6), 6.9 (4.0-9.6) and 5.5 (3.3-7.8) for SUV_max, SUV_peak and SUV_mean. Interobserver variability was 0% (0-12), 0% (0-2) and 7% (5-14), respectively (n = 103). The success rate of the semi-automatic method was 45%. Inclusion of background was the main reason for failure of semi-automatic VOI.

CONCLUSIONS

This study shows that interobserver reproducibility of tumor uptake quantification on ⁸⁹Zr-immuno-PET was excellent for SUV_max and SUV_peak using a standardized manual procedure for tumor segmentation. Semi-automatic delineation was not robust due to limited tumor contrast.

Metabolic positron emission tomography parameters predict failure patterns in early non-small-cell lung cancer treated with stereotactic body radiation therapy: a single institution experience

Objective

The prognostic value of metabolic parameters using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) has not been established for early non-small cell lung cancer (NSCLC). Accordingly, the authors investigated the prognostic value of metabolic parameters in terms of failure patterns in patients with early NSCLC who underwent stereotactic body radiation therapy (SBRT).

Methods

Data from 35 patients with Stage I NSCLC who underwent SBRT using CyberKnife and received pretreatment FDG PET/CT between 2008 and 2016 were retrospectively reviewed. Maximum standardized uptake value (SUVmax), metabolic tumor volume, and total lesion glycolysis were measured. The significance of these parameters with regard to failure patterns was assessed.

Results

The median follow-up was 23 months for all patients and 34 months for living patients. Ten patients experienced recurrence: three local failures, five regional failures (RF), and eight distant failures (DF). Three-year local, regional and distant control rates were 96.7%, 86.4% and 71.1%, respectively. High SUVmax (<9 vs. ≥9) was an independent predictive factor associated with increased RF (P = 0.027) and DF (P = 0.008). Furthermore, SUVmax was indicative of both progression-free (P = 0.015) and overall (P = 0.034) survival.

Conclusions

High SUVmax was a significant metabolic parameter associated with increased RF and DF in patients with early NSCLC who received SBRT, having a high propensity for dissemination. These results suggest that adjuvant treatment in conjunction with SBRT may be considered in patients with early NSCLC and high SUVmax.

Utility of SUVmax on 18 F-FDG PET in detecting cervical nodal metastases

Background

The presence of cervical lymph node metastasis is an important prognostic factor for patients with head and neck squamous cell carcinomas (HNSCC). Accurate assessment of lymph node metastasis in these patients is essential for appropriate prognostic and management purposes. Here, we evaluated the effectiveness of the maximum standardized uptake value (SUV_max) on positron emission tomography (PET) in assessing lymph node metastasis in HNSCC prior to surgery.

Methods

A retrospective review of 74 patients with HNSCC who underwent PET/CT prior to neck dissection were examined. Pre-operative PET/CT scans were reviewed by two experienced nuclear medicine physicians and SUV_max of the largest node in each nodal basin documented. These were compared with the histology results of the neck dissection.

Results

A total of 359 nodal basins including 86 basins with metastatic nodes were evaluated. A nodal SUV_max ≥3.16 yielded a sensitivity of 74.4 % and specificity of 84.9 % in detecting metastatic nodes. The nodal SUV_max/Liver SUV_max ratio was found on receiver operating characteristic (ROC) to be effective in detecting metastatic nodes with an area under ROC curve of 0.90. A nodal SUV_max/Liver SUV_max ratio ≥0.90 yielded a sensitivity of 74.1 % and specificity of 93.4 %. By comparison, visual inspection yielded sensitivities of 66.3 and 61.6 % in observers 1 and 2 respectively. The corresponding specificities were 77.7 and 86.5 %.

Conclusions

Nodal SUV_max and nodal SUV_max/liver SUV_max are both useful in the pre-operative detection of metastatic nodes with the latter being superior to visual inspection. The ratio is likely to be more useful as it corrects for inter-scanner variability.

Ability of Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography to Predict Outcomes of Neoadjuvant Chemoradiotherapy Followed by Surgical Treatment for Esophageal Squamous Cell Carcinoma

BACKGROUND

Responses of esophageal cancer to neoadjuvant therapy and patient prognosis are difficult to predict preoperatively. This study aimed to determine the ability of fluorine-18 fluorodeoxyglucose ((18)FDG) positron emission tomography (FDG-PET) to predict outcomes of trimodal therapy on esophageal squamous cell carcinoma (ESCC).

METHODS

The responses of 111 patients with ESCC were monitored using FDG-PET before and after neoadjuvant chemoradiotherapy (nCRT) followed by surgical treatment. Associations between the maximum standardized uptake value (SUVmax) and pathologic responses (PRs) and prognosis were analyzed.

RESULTS

Responses were significantly associated with SUVmax after nCRT (post-SUVmax) and with the rate of decreases in the SUVmax (%ΔSUVmax) of the primary tumor. The optimal cutoffs for post-SUVmax and %ΔSUVmax determined from receiver operating characteristic (ROC) curves were 2.7 (area under the curve [AUC], 0.68; 95% confidence interval [CI], 0.58-0.78; p = 0.001) and 75 (AUC, 0.64; 95% CI, 0.54-0.75; p = 0.01) for predicting a pathologic complete response (pCR) and 3.7 (AUC, 0.76; 95% CI, 0.63-0.89; p < 0.001) and 70 (AUC, 0.65; 95% CI, 0.52-0.78; p = 0.02) for predicting a good response according to Japan Esophageal Society response criteria. These values reliably separated patients into groups with and without pCR and with and without a good response. Multivariate analysis showed that %ΔSUVmax (≤70 and >70) was an independent prognostic factor for disease-specific survival (hazard ratio [HR], 0.45; 95% CI, 0.21-0.98; p = 0.04).

CONCLUSIONS

SUVmax is a valuable preoperative predictor of tumor response and survival among patients who undergo trimodal therapy for ESCC.

The Relationship Between Estrogen Receptor, Progesterone Receptor and Human Epidermal Growth Factor Receptor 2 Expression of Breast Cancer and the Retention Index in Dual Phase (18)F-FDG PET/CT

PURPOSE

This study investigates the correlation of retention index (RI) using the dual phase FDG PET/CT scan with the breast cancer biomarkers.

METHODS

A total of 55 patients with breast cancer underwent dual phase FDG PET/CT scans (60 and 120 min after FDG injection) before treatment. SUVmax and SUVmean of the primary breast tumors were measured, then the percent change of SUVmax and SUVmean between the two scans were calculated, and denoted as RImax and RImean, respectively. After the surgical resection of the breast tumor, the status of biomarkers (ER, PR, and HER-2) was evaluated in the postsurgical specimen.

RESULTS

RImean was significantly higher in ER (-) (median, 16.2; IQR, 10.8-21.0) or HER-2 (+) (median, 16.1; IQR, 10.7-21.6) tumors than in ER (+) tumors (median, 9.9; IQR, 5.5-15.3) or HER-2 (-) tumors (median, 10.5; IQR, 5.5-16.1). However, there were no significant differences of SUVmax or RImax according to the ER or HER-2 status. There were no significant differences of any PET parameters between PR (+) and PR (-) tumors. Based off ROC curve analyses, RImean predicted the ER (+) tumors (AUC, 0.699; p = 0.006), and HER-2 (+) tumors (AUC, 0.674; p = 0.022), but not the PR (+) tumors. However, neither SUVmax nor RImax predicted ER (+), PR (+), or HER-2 (+) tumors.

CONCLUSIONS

Retention index of SUVmean can reflect the ER and HER-2 status of breast cancers. Higher retention index of SUVmean might associate with lower ER expression and higher HER-2 expression.

Association between [18F]-fluoro-2-deoxyglucose uptake and expressions of hypoxia-induced factor 1α and glucose transporter 1 in non-small cell lung cancer

OBJECTIVE

High maximum standardized uptake values on [(18)F]-fluoro-2-deoxyglucose positron emission tomography are associated with inferior survival in non-small cell lung cancer. Here, we investigated the biological mechanisms underlying [(18)F]-fluoro-2-deoxyglucose uptake in non-small cell lung cancer.

METHODS

This study included 133 patients with non-small cell lung cancer (109 with adenocarcinoma and 24 with squamous cell carcinoma). The patients underwent tumour resection, at the latest, 4 weeks after [(18)F]-fluoro-2-deoxyglucose positron emission tomography. The maximum standardized uptake values for primary lesions were calculated based on [(18)F]-fluoro-2-deoxyglucose uptake. The expression of hypoxia-inducible factor 1α and glucose transporter 1 was evaluated on immunostained tumour sections using six-point grading scales.

RESULTS

Maximum standardized uptake values and the expression of hypoxia-inducible factor 1α and glucose transporter 1 were significantly higher in squamous cell carcinoma than in adenocarcinoma (P < 0.001, P = 0.034 and P < 0.001, respectively). In adenocarcinoma, but not squamous cell carcinoma, maximum standardized uptake values, hypoxia-inducible factor 1α and glucose transporter 1 correlated with various clinicopathological factors relating to malignancy, and maximum standardized uptake values and glucose transporter 1 were associated with disease-free survival (P < 0.001 and P = 0.029) and overall survival (P < 0.001 and P = 0.033, respectively). Patients with high expression of hypoxia-inducible factor 1α tended to exhibit shorter disease-free survival and overall survival than those with low expression, but the differences were not significant (P = 0.32 and P = 0.15, respectively). And then in adenocarcinoma, hypoxia-inducible factor 1α and glucose transporter 1, glucose transporter 1 and maximum standardized uptake values, and hypoxia-inducible factor 1α and maximum standardized uptake values were significantly correlated (P < 0.001 for all), suggesting that hypoxia-inducible factor 1α-induced glucose transporter 1 might influence maximum standardized uptake values on [(18)F]-fluoro-2-deoxyglucose positron emission tomography.

CONCLUSIONS

In lung adenocarcinoma, but not squamous cell carcinoma, hypoxia-inducible factor 1α and glucose transporter 1 expressions indicate tumour aggressiveness pathologically and might explain high [(18)F]-fluoro-2-deoxyglucose uptake on positron emission tomography and correlate with poor prognosis.

Two-time-point FDG PET/CT: liver SULmean repeatability

OBJECTIVE. The purpose of this study was to evaluate the repeatability of liver mean standardized uptake value normalized to lean body mass (SULmean) in the same patients at different time points within the right lobe of the liver at (18)F-FDG PET/CT, in a clinical setting. MATERIALS AND METHODS. Two PET/CT studies performed on two different dates from each of 130 patients who had normal livers according to structural imaging were included in this reader study. The mean (± SD) length of time between the studies was 235 ± 192 days. SULmean was measured with a 30-mm diameter spherical volume of interest (VOI) placed within the right lobe of the liver (above, below, and at the level of the main portal vein) by two expert readers. ANOVA, intraclass correlation coefficient (ICC), and Bland-Altman analysis were performed. RESULTS. The ICC for the first and second set of studies varied between 0.487 and 0.535 for reader 1 and between 0.472 and 0.545 for reader 2. The mean percentage variation for SULmean between the two time scans for the VOIs placed above, below, and at the level of the main portal vein were 3.55% ± 23.19%, 4.65% ± 23.87%, and 4.30% ± 23.03%, respectively, for reader 1 and 4.49% ± 23.23%, 4.33% ± 23.74%, and 4.48% ± 23.01%, respectively, for reader 2. Using 95% CI, the reference range for intrapatient variations between the studies in liver SULmean was -0.5 to 0.60. CONCLUSION. There is only fair repeatability of liver SULmean measured between two time points in the same patient in a clinical setting. Scan-to-scan intrapatient variation in absolute liver SULmean was -0.5 to 0.60.

The applications of corrected standardized uptake values in the diagnosis of peripheral lung lesions

Fluorine 18-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) imaging has been widely used to diagnose many types of tumors. However, many factors can affect the accuracy of standardized uptake values (SUVs). In this study, we aimed to explore the applications of corrected SUVs in the diagnosis of peripheral solitary pulmonary lesions.A retrospective study was undertaken in 69 patients with peripheral solitary pulmonary lesions. Whole-body PET/CT was acquired approximately 60 min after F-FDG injection. The lesions were found to be malignant in 57 cases and benign in 12 cases. Of the 69 cases, 68 were correctly diagnosed, and only 1 was misdiagnosed by the corrected SUVs. The diagnostic accuracy rate was 98.5%. The sensitivity, specificity, positive predictive value, and negative predictive value of the corrected SUV were 100%, 91.7%, 98.3%, and 100%, respectively.F-FDG PET/CT with corrected SUVs is of great value for improving diagnostic accuracy in peripheral lung lesions.

Role of FDG-PET/CT in prediction of underestimation of invasive breast cancer in cases of ductal carcinoma in situ diagnosed at needle biopsy

BACKGROUND

The aim of this study was to evaluate the significance of FDG-PET/CT for predicting the underestimation of invasive breast cancer in cases of DCIS at needle biopsy.

PATIENTS AND METHODS

Of 83 consecutive cases with diagnoses of DCIS at primary needle biopsy who underwent curative surgery between 2010 and 2013, the association between the SUVmax on FDG-PET/CT before excision and the underestimation of invasive breast cancer was examined.

RESULTS

There were 29 (34.9%) cases diagnosed to have invasive breast cancer at excision. Receiver operating characteristics curve analysis showed the cutoff value of the SUVmax to predict underestimation of invasive breast cancer was 1.6. The rates of underestimation were 61.5% for patients with a tumor of SUVmax > 1.6 and 11.4% for patients with a tumor of SUVmax ≤ 1.6 (P < .001). A high value of SUVmax was significantly associated with symptomatic presentation (P < .001), palpability (P < .001), mass formation (P = .013), high Breast Imaging Reporting and Data System category (P = .011), and core needle biopsy (P = .007). In multivariate analysis, high SUVmax was only a significant predictive factor of underestimation of invasive breast cancer (hazard ratio, 11.7; 95% confidence interval, 3.70-37.0; P < .001).

CONCLUSION

SUVmax on FDG-PET/CT is useful for predicting the underestimation of invasive breast cancer in cases of DCIS at needle biopsy.

A partial volume effect correction tailored for 18F-FDG-PET oncological studies

We have developed, optimized, and validated a method for partial volume effect (PVE) correction of oncological lesions in positron emission tomography (PET) clinical studies, based on recovery coefficients (RC) and on PET measurements of lesion-to-background ratio (L/B_m) and of lesion metabolic volume. An operator-independent technique, based on an optimised threshold of the maximum lesion uptake, allows to define an isocontour around the lesion on PET images in order to measure both lesion radioactivity uptake and lesion metabolic volume. RC are experimentally derived from PET measurements of hot spheres in hot background, miming oncological lesions. RC were obtained as a function of PET measured sphere-to-background ratio and PET measured sphere metabolic volume, both resulting from the threshold-isocontour technique. PVE correction of lesions of a diameter ranging from 10 mm to 40 mm and for measured L/B_m from 2 to 30 was performed using measured RC curves tailored at answering the need to quantify a large variety of real oncological lesions by means of PET. Validation of the PVE correction method resulted to be accurate (>89%) in clinical realistic conditions for lesion diameter > 1 cm, recovering >76% of radioactivity for lesion diameter < 1 cm. Results from patient studies showed that the proposed PVE correction method is suitable and feasible and has an impact on a clinical environment.

Role of FDG-PET/CT in evaluating surgical outcomes of operable breast cancer--usefulness for malignant grade of triple-negative breast cancer

BACKGROUND

The aim of this study was to evaluate the significance of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for speculating the malignant level and prognostic value of operable breast cancers.

METHODS

Of 578 consecutive patients with primary invasive breast cancer who underwent curative surgery between 2005 and 2010, 311 patients (53.8%) who received FDG-PET/CT before initial therapy were examined.

RESULTS

Receiver operating characteristics (ROC) curve analysis showed the cutoff value of the maximum standardized uptake value (SUVmax) to predict cancer recurrence was 3.8 in all patients and 8.6 in patients with the triple-negative subtype, respectively. In all patients, 3-year DFS rates were 98.8% for patients with a tumor of SUVmax ≤ 3.8 and 91.6% for patients with a tumor of SUVmax > 3.8 (p < 0.001). High value of SUVmax was significantly associated with large tumor size (p < 0.001), lymph node metastasis (p = 0.040), high nuclear grade (p < 0.001), lymphovascular invasion (p = 0.032), negative hormone receptor status (p < 0.001), and positive HER2 status (p = 0.014). Based on the results of multivariate Cox analysis in all patients, high SUVmax (p = 0.001) and negative hormone receptor status (p = 0.005) were significantly associated with poor prognosis. In patients with triple-negative subtype, 3-year DFS rates were 90.9% for patients with a tumor of SUVmax ≤ 8.6 and 42.9% for patients with a tumor of SUVmax > 8.6 (p = 0.002), and high SUVmax was the only significant independent prognostic factor (p = 0.047).

CONCLUSION

FDG-PET/CT is useful for predicting malignant behavior and prognosis in patients with operable breast cancer, especially the triple-negative subtype.

Primary tumor PET/CT [¹⁸F]FDG uptake is an independent predictive factor for regional lymph node metastasis in patients with non-small cell lung cancer

Aim: To investigate the correlation between [¹⁸F]fluorodeoxyglucose (FDG) uptake in a primary tumor and pathologic N stages, and to further analyze the possible risk factors contributing to the regional lymph node metastasis. Patients and methods: Eighty patients with non-small cell lung cancer (NSCLC) who underwent positron emission tomography/computed tomography were enrolled in the study. The FDG uptake in the primary tumor was compared for the different N staging groups and further correlation was performed. The degree of FDG uptake in the primary tumor and other possible variables related to the incidence of lymph node metastasis were examined by univariate and logistic multivariate analysis. FDG uptake was quantitated using the maximum standardized uptake value (SUV_max). Results: Statistically significant differences were found in the SUV_max of the primary tumors among different N staging groups (F = 4.124, P = 0.023), and the correlation between them was also statistically significant (r = 0.438, P = 0.000). Univariate analysis showed that blood tumor markers, primary tumor size, histologic grade, and SUV_max of the primary tumor were significantly associated with lymph node involvement. Logistic multivariate analysis showed that blood tumor makers and SUV_max of primary tumor might be considered as significant predictive factors for lymph node metastasis in patients with NSCLC. Conclusion: Our results show that there is a significant relationship between the SUV_max of the primary tumor and the pathologic N stage of NSCLC. FDG uptake by the primary tumor may be an independent predictor of regional lymph node metastasis in patients with NSCLC.

Importance of quantification for the analysis of PET data in oncology: review of current methods and trends for the future

In oncology, positron emission tomography (PET) is an important tool for tumour diagnosis and staging, assessment of response to treatment and evaluation of the pharmacokinetic properties and efficacy of new drugs. Despite its quantitative potential, however, in daily clinical practice PET is used almost exclusively with 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) and, in addition, [(18)F]FDG data are normally assessed visually or using simple indices as the standardised uptake value (SUV). After explaining why more sophisticated quantification methods can be useful in oncology, the paper reviews the approaches that are commonly used and those available but not routinely employed. Particular emphasis is addressed to the SUV, for its importance in clinical practice. Issues specific to PET quantification in oncology and related examples are then discussed. Finally, some ideas for the development of new quantitative methods for analysing PET data in oncology and for the application of approaches already existing but not commonly employed are presented.

Use of 18F-FDG PET/CT as a predictive biomarker of outcome in patients with head-and-neck non-squamous cell carcinoma

OBJECTIVE

The purpose of this article is to establish whether pretreatment (18)F-FDG uptake predicts disease-free survival (DFS) and overall survival in patients with head-and-neck non-squamous cell carcinoma (SCC).

MATERIALS AND METHODS

Eighteen patients (six women and 12 men; mean [± SD] age at diagnosis, 57.89 ± 13.54 years) with head-and-neck non-SCC were included. Tumor FDG uptake was measured by the maximum standardized uptake value (SUV(max)) and was corrected for background liver FDG uptake to derive the corrected SUV(max). Receiver operating characteristic analyses were used to predict the optimal corrected SUV(max) cutoffs for respective outcomes of DFS (i.e., absence of recurrence) and death.

RESULTS

The mean corrected SUV(max) of the 18 head-and-neck tumors was 5.63 ± 3.94 (range, 1.14-14.29). The optimal corrected SUV(max) cutoff for predicting DFS and overall survival was 5.79. DFS and overall survival were significantly higher among patients with corrected SUV(max) < 6 than among patients with corrected SUV(max) ≥ 6. The mean DFS for patients with corrected SUV(max) < 6 was 25.7 ± 11.14 months, and the mean DFS for patients with corrected SUV(max) ≥ 6 was 7.88 ± 7.1 months (p < 0.018). Among patients with corrected SUV(max) < 6, none died, and the mean length of follow-up for this group was 35.2 ± 9.96 months. All of the patients who died had corrected SUV(max) ≥ 6, and the overall survival for this group was 13.28 ± 12.89 months (p < 0.001).

CONCLUSION

FDG uptake, as measured by corrected SUV(max), may be a predictive imaging biomarker for DFS and overall survival in patients with head-and-neck non-SCC.

Difference in prognostic significance of maximum standardized uptake value on [18F]-fluoro-2-deoxyglucose positron emission tomography between adenocarcinoma and squamous cell carcinoma of the lung

OBJECTIVE

This study evaluates the prognostic significance of [18F]-fluoro-2-deoxyglucose positron emission tomography/computed tomography findings according to histological subtypes in patients with completely resected non-small cell lung cancer.

METHODS

We examined 176 consecutive patients who had undergone preoperative [18F]-fluoro-2-deoxyglucose-positron emission tomography/computed tomography imaging and curative surgical resection for adenocarcinoma (n = 132) or squamous cell carcinoma (n = 44). Maximum standardized uptake values for the primary lesions in all patients were calculated as the [18F]-fluoro-2-deoxyglucose uptake and the surgical results were analyzed.

RESULTS

The median values of maximum standardized uptake value for the primary tumors were 2.60 in patients with adenocarcinoma and 6.95 in patients with squamous cell carcinoma (P< 0.001). Analyses of receiver operating characteristic curves identified an optimal maximum standardized uptake value cutoff value to predict recurrence of 3.7 for adenocarcinoma, whereas such an indicator could not be identified for squamous cell carcinoma. Although 2-year disease-free survival rates were 70.2% for maximum standardized uptake value ≤6.95 and 59.3% for maximum standardized uptake value >6.95 (P = 0.83) among patients with squamous cell carcinoma, 2-year disease-free survival rates were 93.9% for maximum standardized uptake value ≤3.7 and 52.4% for maximum standardized uptake value >3.7 (P < 0.0001) among those with adenocarcinoma, and notably, 100 and 57.2%, respectively, in patients with Stage I adenocarcinoma (P < 0.0001). On the basis of the multivariate Cox analyses of patients with adenocarcinoma, maximum standardized uptake value (P = 0.008) was a significantly independent factor for disease-free survival as well as nodal metastasis (P = 0.001).

CONCLUSIONS

Maximum standardized uptake value of the primary tumor was a powerful prognostic determinant for patients with adenocarcinoma, but not with squamous cell carcinoma of the lung.

Positron emission tomography 18F-fluorodeoxyglucose uptake and prognosis in patients with surgically treated, stage I non-small cell lung cancer: a systematic review

BACKGROUND

18F-fluorodeoxyglucose (FDG) uptake holds potential as a noninvasive biomarker in patients with non-small cell lung cancer (NSCLC). We aimed to investigate the association between tumor FDG uptake and survival in patients with surgically resected, stage I NSCLC.

METHODS

We used systematic methods to identify studies for inclusion, assess methodological quality, and abstract relevant data about study design and results.

RESULTS

Our literature search identified 1578 citations, of which nine retrospective, cross-sectional studies met eligibility criteria. In all studies, higher degrees of FDG uptake in the primary tumor were associated with worse overall or disease free survival after 2 to 5 years of follow-up, but these differences were statistically significant in only five studies. Across studies, the median overall or disease free survival was 70% for patients with higher FDG uptake compared with 88% for patients with lower FDG uptake. In three studies that performed multivariable analysis, the adjusted hazard of death or recurrence was 1.9 to 8.6 times greater in patients with higher FDG uptake.

CONCLUSION

Current evidence suggests that increasing tumor FDG uptake is associated with worse survival in patients with stage I NSCLC. FDG uptake has the potential to be used as a biomarker for identifying stage I patients who are at increased risk of death or recurrence and therefore could identify candidates for participation in future trials of adjuvant therapy.

The variation of prognostic significance of Maximum Standardized Uptake Value of [18F]-fluoro-2-deoxy-glucose positron emission tomography in different histological subtypes and pathological stages of surgically resected Non-Small Cell Lung Carcinoma

Even if the prognostic role of SUVmax of 18-FDG-PET has been largely investigated, many issues regarding its relationship with pathologic staging and histological subtypes still remain controversial. This retrospective study investigated the prognostic significance of SUVmax in 119 completely resected, pathologically proven NSCLC. The SUVmax values resulted significantly related to histological subtypes (p<0.001), histological grading (p<0.001), and pathologic stage (p<0.001). The optimal cut-off value of SUVmax to predict prognosis in the whole series was 6.7 (p=0.029). 2-Year disease-specific survival (DSS) was 91% for SUVmax < or =6.7 and 55% for SUVmax >6.7 (p<0.001). SUVmax still remain a significant predictor of survival in Stage IB (2-year DSS of 100% for SUVmax < or =6.7; 51% for SUVmax >6.7, p=0.016). The optimal cut-off values of SUVmax to predict prognosis were 5 for adenocarcinoma (p=0.027) and 10.7 for other non-adenocarcinoma NSCLC subtypes (p=0.010). These histologic-specific cut-offs resulted significantly related to survival when stratified for stage: 2-year DSS for Stage IB adenocarcinoma were 100% for SUV< or =5 and 40% for SUVmax >5 (p=0.051); 2-year DSS for Stage IB non-adenocarcinoma were 83% for SUVmax < or =10.7 and 26% for SUVmax >10.7 (p=0.018). Adenocarcinomas showed significantly lower survival results respect to other NSCLC for intermediate SUVmax level (range 5.5-11.3) (p=0.021). High SUVmax resulted an independent negative prognostic factor at multivariate analysis (HR of 15.7, 95% CI of 2.50-98.44, p=0.003). In conclusion, SUVmax represents a significant prognostic factor in surgically resected NSCLC but a great variability between different histological subtypes, even when adjusted for stage, is present and could be considered when planning future trials on prognostic role of FDG uptake.

18F-Fluorodeoxyglucose positron emission tomography for the diagnosis of adrenocortical tumors: a prospective study in 77 operated patients

CONTEXT

Most adrenal incidentalomas are nonfunctioning adrenocortical adenomas (ACAs). Adrenocortical carcinomas (ACCs) are rare but should be recognized at an early stage.

OBJECTIVE

The objective of the study was to evaluate the usefulness of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) to predict malignancy in patients without a previous history of cancer.

DESIGN

This was a prospective, multicenter study from 2001 to 2006.

SETTING

The study was conducted at a network of seven university hospitals in Paris.

PATIENTS

Seventy-seven patients were included. All underwent surgery because of hypersecretory and/or growing benign lesions (n = 18), obvious ACCs (n = 21), or radiologically indeterminate lesions (n = 38).

MAIN OUTCOME MEASURE

The degree of (18)F-FDG PET uptake [maximum standardized uptake value (maxSUV)] was related to the pathological findings serving as a reference, and its diagnostic value was compared with that of computerized tomography (CT) scan.

RESULTS

Pathology eventually diagnosed 43 ACAs, 22 ACCs, and 12 nonadrenocortical lesions. Using a cutoff value above 1.45 for adrenal to liver maxSUV ratio, the sensitivity and specificity to distinguish ACAs from ACCs were, respectively, 1.00 (95% confidence interval 0.85-1.00) and 0.88 (95% confidence interval 0.75-0.96). Among the 38 indeterminate lesions at CT scan, we could analyze a subgroup of 16 adrenocortical tumors with high unenhanced density (>10 HU) and an inappropriate washout: (18)F-FDG PET correctly predicted the benignity in 13 of 15 ACAs.

CONCLUSIONS

In a multidisciplinary team approach, (18)F-FDG PET helps to manage suspicious CT scan lesions. An adrenal to liver maxSUV ratio less than 1.45 is highly predictive of a benign lesion.

FLT-PET imaging of radiation responses in murine tumors

BACKGROUND

3'-[F-18]fluoro-3'-deoxythymidine (FLT) traces thymidine phosphorylation catalyzed by thymidine kinase during cell proliferation. Knowing the rate of cell proliferation during cancer treatment, such as radiation therapy, would be valuable in assessing whether tumor recurrence is likely and might indicate the need for additional treatments. However, the relationship between FLT kinetics and the effects of radiation is not well-understood. Nor has the method for optimal quantification of FLT uptake within the irradiated tumor microenvironment been extensively examined.

MATERIALS AND METHODS

We performed dynamic FLT-positron emission tomography (PET) studies (60 min) on 22 mice implanted subcutaneously with syngeneic mammary MCaK tumors bilaterally in the shoulder area. A day before the FLT-PET imaging, the tumor on the right side was irradiated with a single dose (0, 2.5, 5, 10, or 20 Gy) or with fractionated exposures (4x2.5 Gy given in 12 h intervals). Standardized uptake value (SUVs) of FLT on tumors at 10 and 60 min post injection were calculated; model fitting was used to estimate the kinetic parameters. Significant radiation-induced changes were shown by comparing the irradiated tumor with the control tumor in the same animal and by comparing it to nonirradiated mice. The effect of radiation on MCaK cell cycle parameters and FLT uptake was also examined in vitro.

RESULTS

In vivo FLT kinetics were sensitive to radiation doses of 5 Gy and higher (administered 1 day earlier), as judged by SUV semiquantitative measures and by modeling. Single irradiation with 10 Gy had greater impact on SUVs and kinetic parameters than fractionated exposures. Overall, the uptake constant Ki appeared to be the best marker for these radiation effects. FLT uptake by irradiated cells in vitro at various doses gave similar findings, and the in vitro FLT uptake correlated well with Ki. Radiation-induced G2/M arrest appeared to influence FLT uptake, and this was more pronounced after single than fractionated doses.

CONCLUSION

The kinetics of FLT uptake into murine mammary tumors was altered 1 day after radiation treatment. The dose-dependent response correlated well with in vitro FLT cellular uptake. Parameters (e.g., Ki) derived from FLT kinetics are expected to be useful for assessing the efficacy of irradiation treatment of tumors.

Treatment monitoring by 18F-FDG PET/CT in patients with sarcomas: interobserver variability of quantitative parameters in treatment-induced changes in histopathologically responding and nonresponding tumors

Measurements of tumor glucose use by (18)F-FDG PET need to be standardized within and across institutions. Various parameters are used for measuring changes in tumor glucose metabolic activity with (18)F-FDG PET in response to cancer treatments. However, it is unknown which of these provide the lowest variability between observers. Knowledge of the interobserver variability of quantitative parameters is important in sarcomas as these tumors are frequently large and demonstrate heterogeneous (18)F-FDG uptake.

METHODS

A total of 33 patients (16 men, 17 women; mean age, 47 +/- 18 y) with high-grade sarcomas underwent (18)F-FDG PET/CT scans before and after neoadjuvant chemotherapy. Two independent investigators measured the following parameters on the pretreatment and posttreatment scans: maximum standardized uptake value (SUVmax), peak SUV (SUVpeak), mean SUV (SUVmean), SUVmean in an automatically defined volume (SUVauto), and tumor-to-background ratio (TBR). The variability of the different parameters was compared by concordance correlation coefficient (CCC), variability effect coefficient, and Bland-Altman plots.

RESULTS

Baseline SUVmax, SUVpeak, SUVmean, SUVauto, and TBR averaged 10.36, 7.78, 4.13, and 6.22 g/mL and 14.67, respectively. They decreased to 5.36, 3.80, 1.79, and 3.25 g/mL and 6.62, respectively, after treatment. SUVmax, SUVpeak, and SUVauto measurements and their changes were reproducible (CCC > or = 0.98). However, SUVauto poorly differentiated between responding and nonresponding tumors. The high intratumoral heterogeneity of (18)F-FDG resulted in frequent failure of the thresholding algorithm, which necessitated manual corrections that in turn resulted in a higher interobserver variability of SUVmean (CCCs for follow-up and change were 0.96 and 0.91, respectively; P < 0.005). TBRs also showed a significantly higher variability than did SUVpeak (CCCs for follow-up and change were 0.94 and 0.86, respectively; P < 0.005).

CONCLUSION

SUVmax and SUVpeak provided the most robust measurements of tumor glucose metabolism in sarcomas. Delineation of the whole-tumor volume by semiautomatic thresholding did not decrease the variability of SUV measurements. TBRs were significantly more observer-dependent than were absolute SUVs. These findings should be considered for standardization of clinical (18)F-FDG PET/CT trials.

Integrated FDG-PET/CT does not make invasive staging of the intrathoracic lymph nodes in non-small cell lung cancer redundant: a prospective study

BACKGROUND

Staging of non-small cell lung cancer (NSCLC) is important for determining choice of treatment and prognosis. The accuracy of FDG-PET scans for staging of lymph nodes is too low to replace invasive nodal staging. It is unknown whether the accuracy of integrated FDG-PET/CT scanning makes invasive staging redundant.

METHODS

In a prospective study, the mediastinal and/or hilar lymph nodes in patients with proven NSCLC were investigated with integrated FDG-PET/CT scanning. Pathological confirmation of all suspect lymph nodes was obtained to calculate the accuracy of the fusion images. In addition, the use of the standardised uptake value (SUV) in the staging of intrathoracic lymph nodes was analysed.

RESULTS

105 intrathoracic lymph node stations from 52 patients with NSCLC were characterised. The prevalence of malignancy in the lymph nodes was 36%. The sensitivity of the integrated FDG-PET/CT scan to detect malignant lymph nodes was 84% and its specificity was 85% (positive likelihood ratio 5.64, negative likelihood ratio 0.19). SUV(max), SUV(mean) and the SUV(max)/SUV(liver) ratio were all significantly higher in malignant than in benign lymph nodes. The area under the receiver operating curve did not differ between these three quantitative variables, but the highest accuracy was found with the SUV(max)/SUV(liver) ratio. At a cut-off value of 1.5 for the SUV(max)/SUV(liver )ratio, the sensitivity and specificity to detect malignant lymph node invasion were 82% and 93%, respectively.

CONCLUSION

The accuracy of integrated FDG-PET/CT scanning is too low to replace invasive intrathoracic lymph node staging in patients with NSCLC. The visual interpretation of the fusion images of the integrated FDG-PET/CT scan can be replaced by the quantitative variable SUV(max)/SUV(liver) without loss of accuracy for intrathoracic lymph node staging.

Associations among bronchioloalveolar carcinoma components, positron emission tomographic and computed tomographic findings, and malignant behavior in small lung adenocarcinomas

OBJECTIVE

The aggressiveness of small adenocarcinomas has not been fully evaluated using integrated positron emission tomography/computed tomography. We investigated malignant aggressiveness according to positron emission tomography/computed tomography, high-resolution computed tomographic findings, and the proportions of pathologically defined bronchioloalveolar carcinomas in cT1N0M0 lung adenocarcinoma.

METHODS

Sixty consecutive patients with cT1N0M0 lung adenocarcinomas of 3 cm or less in diameter underwent fluorodeoxyglucose-positron emission tomograph/computed tomography, and high-resolution computed tomography, followed by complete tumor resection. Correlations between the proportion of bronchioloalveolar carcinoma and maximum standardized uptake value on positron emission tomographic scan/computed tomographic scan, ground-glass opacity, and tumor shadow disappearance rate were investigated and the findings were compared with clinicopathologic features.

RESULTS

Lymphatic and vascular invasion occurred in 18 (30%) and 13 (22%) patients, respectively, whereas hilar or mediastinal lymph nodes occurred in 8 patients (13%). Maximum standardized uptake value generally seemed the most valuable predictor of lymphatic invasion, vascular invasion, and nodal metastasis compared with ground-glass opacity, tumor shadow disappearance rate, and bronchioloalveolar carcinoma ratios. Although the association was significant between the bronchioloalveolar carcinoma ratio versus maximum standardized uptake value, ground-glass opacity ratio, and tumor shadow disappearance rate (all P < .0001), maximum standardized uptake value (R2 = 0.245) was less correlated with the bronchioloalveolar carcinoma ratio than was the ground-glass opacity ratio (R2 = 0.554) and tumor shadow disappearance rate (R2 = 0.671).

CONCLUSIONS

The malignant behavior of small adenocarcinomas with a lower maximum standardized uptake value and a greater proportion of ground-glass opacity, tumor shadow disappearance rate, and bronchioloalveolar carcinoma was less aggressive. Maximum standardized uptake value was a more powerful clinical predictor of biologic tumor performance, independent of pathologic bronchioloalveolar carcinoma proportion. Preoperative assessment of maximum standardized uptake value on positron emission tomographic/computed tomographic findings, in addition to the ground-glass opacity ratio and tumor shadow disappearance rate on high-resolution computed tomographic scans, might be useful to guide treatment strategies for small adenocarcinomas.

Ratio of the maximum standardized uptake value on FDG-PET of the mediastinal (N2) lymph nodes to the primary tumor may be a universal predictor of nodal malignancy in patients with nonsmall-cell lung cancer

BACKGROUND

The maximum standardized uptake value (maxSUV) on F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) scan of mediastinal (N2) lymph nodes may predict pathology in patients with nonsmall-cell lung cancer. However, the maxSUV varies among PET scanners. Thus, we evaluated the ratio of the maxSUV of the lymph node to the primary tumor at different centers to determine whether it was a universal predictor of lymph node malignancy.

METHODS

This is a retrospective review of a prospective database. Patients with nonsmall-cell lung cancer, a dedicated FDG-PET with the maxSUV of the primary lung tumor and FDG-avid mediastinal (N2) nodes reported (before therapy), and who underwent lymph node removal were eligible.

RESULTS

There were 239 patients with 335 FDG-PET-positive N2 nodes at 14 different PET centers. The median ratio of the maxSUV of the lymph node to the maxSUV of the primary tumor of the pathologically proven malignant nodes was 0.58 (range, 0.32 to 1.61). Benign nodes had a median ratio of 0.40 (range, 0.21 to 1.10, p = 0.02). The median value was similar for all centers except one. Receiver operating characteristics analysis determined the optimal value of the ratio that maximized sensitivity to be 0.56 or greater (+LR 6.6, sensitivity 94%, specificity 72%).

CONCLUSIONS

The ratio of the maxSUV of the mediastinal (N2) lymph node to the maxSUV of the primary tumor in patients with nonsmall-cell lung cancer predicts mediastinal nodal pathology across different PET centers. When the ratio is 0.56 or greater, there is a 94% chance that the node is malignant. The ratio may take into account the different techniques used at different centers.

[F-18]-Fluoro-2-deoxy-D: -glucose positron emission tomography as a tool for early detection of immunotherapy response in a murine B cell lymphoma model

[F-18]-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is a non-invasive imaging technique which has recently been validated for the assessment of therapy response in patients with aggressive non-Hodgkin's lymphoma. Our objective was to determine its value for the evaluation of immunotherapy efficacy in immunocompetent Balb/c mice injected with the A20 syngeneic B lymphoma cell line. The high level of in vitro FDG uptake by A20 cells validated the model for further imaging studies. When injected intravenously, the tumour developed as nodular lesions mostly in liver and spleen, thus mimicking the natural course of an aggressive human lymphoma. FDG-PET provided three-dimensional images of tumour extension including non-palpable lesions, in good correlation with ex vivo macroscopic examination. When mice were pre-immunized with an A20 cell lysate in adjuvant before tumour challenge, their significantly longer survival, compared to control mice, were associated with a lower incidence of lymphoma visualized by PET at different time points. Estimation of tumour growth and metabolism using the calculated tumour volumes and maximum standardized uptake values, respectively, also demonstrated delayed lymphoma development and lower activity in the vaccinated mice. Thus, FDG-PET is a sensitive tool relevant for early detection and follow-up of internal tumours, allowing discrimination between treated and non-treated small animal cohorts without invasive intervention.

PET/CT imaging in response evaluation of patients with small cell lung cancer

There is an increasing amount of evidence on the usability of PET in response evaluation of non-small cell lung cancer. However, data on SCLC is scarce and mainly retrospective. This prospective study assesses the use of PET (positron emission tomography) and PET/CT in response evaluation of patients with small cell lung cancer (SCLC).

METHODS

Assignment of early and final response was compared between PET, PET/CT, and CT in 20 patients with SCLC. Final response as assigned by CT (RECIST) served as reference.

RESULTS

At response evaluation after one cycle of chemotherapy major disagreement (responder versus non-responder) between PET and CT in predicting final response was seen in 1 of 12 patients. At final response evaluation major disagreement between PET, PET/CT and CT was seen in 2 of 19 patients (11%). All measurements of FDG-uptake were significantly correlated to size and changes in size as measured by CT. A significant difference in relative change in tumour FDG-uptake and volume was found between responding and non-responding patients. No significant difference was found between a visual and semi-quantitative analysis of PET.

CONCLUSION

Response evaluation of SCLC by PET/CT is feasible, but it is uncertain whether it adds further information to evaluation by RECIST, thus further studies and standardization of methods are needed.

Maximum standardized uptake values on positron emission tomography of esophageal cancer predicts stage, tumor biology, and survival

BACKGROUND

The stage of esophageal cancer is currently determined by the anatomic TNM classification system as opposed to information about tumor biology.

METHODS

A retrospective review was made of a prospective electronic database. Patients had esophageal cancer, dedicated positron emission tomography (PET) using F-18-fluorodeoxyglucose (FDG-PET) and maximum standardized uptake value (maxSUV) measured. Biopsies were obtained from suspicious nodal and systemic locations, and when indicated, resection with complete lymphadenectomy was performed.

RESULTS

There were 89 patients (53 men). The median maxSUV for patients with high grade dysplasia, stage I, IIa, IIb, III, and IVa esophageal cancer was 1.7, 2.9, 8.9, 7.7, 9.5, and 12, respectively. Multivariate analysis showed patients with a high maxSUV were more likely to have poorly differentiated tumors (risk ratio 1.89, p = 0.032) and advanced stage (risk ratio 2.6, p < 0.001). The maxSUV correlated better (r(2) = 0.85) than the current TNM staging system for survival (r(2) = 0.68). Receiving operator characteristics curve demonstrated a maxSUV of 6.6 to be the optimal cut-off point. The 4-year survival of patients with a maxSUV of 6.6 or less was 89%, whereas it was only 31% for those patients with values greater than 6.6 (p < 0.001).

CONCLUSIONS

The maxSUV of an esophageal cancer on dedicated FDG-PET scan is an independent predictor of stage, tumor characteristics, and survival. It predicts survival better than the current TNM staging system. This information may help guide treatment strategies.

The maximum standardized uptake values on positron emission tomography of a non-small cell lung cancer predict stage, recurrence, and survival

OBJECTIVE

We sought to assess whether the standard uptake value of a pulmonary nodule is an independent predictor of biologic aggressiveness.

METHODS

This is a retrospective review of a prospective database of patients with non-small cell lung cancer. Patients had dedicated positron emission tomography scanning with F-18 fluorodeoxyglucose, with the maximum standard uptake value measured. All suspicious nodal and systemic locations on computed tomographic and positron emission tomographic scanning underwent biopsy, and when indicated, resection with complete lymphadenectomy was performed.

RESULTS

There were 315 patients. Multivariate analysis showed patients with a high maximum standard uptake value (>/=10) were more likely to have poorly differentiated tumors (risk ratio, 1.5; P = .005) and advanced stage (risk ratio, 1.9; P = .010) and were less likely to have their disease completely resected (risk ratio, 3.7; P = .004). Maximum standard uptake value was the best predictor of disease-free survival (hazard ratio, 2.5; P = .039) and survival (hazard ratio, 2.8; P = .001). Stage-specific analysis showed that patients with stage IB and stage II disease with a maximum standard uptake value of greater than the median for their respective stages had a lower disease-free survival at 4 years ( P = .005 and .044). The actual 4-year survival for patients with stage Ib non-small cell lung cancer was 80% versus 66% ( P = .048), for stage II disease it was 64% versus 32% ( P = .028), and for stage IIIa disease it was 64% versus 16% ( P = .012) for the low and high maximum standard uptake value groups, respectively.

CONCLUSIONS

The maximum standard uptake value of a non-small cell lung cancer nodule on dedicated positron emission tomography is an independent predictor of stage and tumor characteristics. It is a more powerful independent predictor than the TNM stage for recurrence and survival for patients with early-stage resected cancer. This information might help guide treatment strategies.

Quantification in clinical fluorodeoxyglucose positron emission tomography

Positron emission tomography (PET) is increasingly used clinically to provide functional information on disease processes, especially in oncology using the glucose analogue 2-[18F]fluoro-2-deoxy-D-glucose (F-FDG). In the clinical setting it has become standard practice to use simplified imaging protocols compared to the often complex methods developed for research using PET. This is partly due to scarcity of resources but also for reasons of patient comfort and compliance, and not least expense and patient throughput. Fortunately the resulting loss in information can be justified to some extent on the grounds that in clinical PET it is usually relative rather than absolute metabolic rates that are of interest. Nonetheless, there remain unresolved questions of how best to perform quantification in clinical PET.

Effects of ROI definition and reconstruction method on quantitative outcome and applicability in a response monitoring trial

PURPOSE

Quantitative measurement of tracer uptake in a tumour can be influenced by a number of factors, including the method of defining regions of interest (ROIs) and the reconstruction parameters used. The main purpose of this study was to determine the effects of different ROI methods on quantitative outcome, using two reconstruction methods and the standard uptake value (SUV) as a simple quantitative measure of FDG uptake.

METHODS

Four commonly used methods of ROI definition (manual placement, fixed dimensions, threshold based and maximum pixel value) were used to calculate SUV (SUV([MAN]), SUV15 mm, SUV50, SUV75 and SUVmax, respectively) and to generate "metabolic" tumour volumes. Test-retest reproducibility of SUVs and of "metabolic" tumour volumes and the applicability of ROI methods during chemotherapy were assessed. In addition, SUVs calculated on ordered subsets expectation maximisation (OSEM) and filtered back-projection (FBP) images were compared.

RESULTS

ROI definition had a direct effect on quantitative outcome. On average, SUV[MAN), SUV15 mm, SUV50 and SUV75, were respectively 48%, 27%, 34% and 15% lower than SUVmax when calculated on OSEM images. No statistically significant differences were found between SUVs calculated on OSEM and FBP reconstructed images. Highest reproducibility was found for SUV15 mm and SUV[MAN] (ICC 0.95 and 0.94, respectively) and for "metabolic" volumes measured with the manual and 50% threshold ROIs (ICC 0.99 for both). Manual, 75% threshold and maximum pixel ROIs could be used throughout therapy, regardless of changes in tumour uptake or geometry. SUVs showed the same trend in relative change in FDG uptake after chemotherapy, irrespective of the ROI method used.

CONCLUSION

The method of ROI definition has a direct influence on quantitative outcome. In terms of simplicity, user-independence, reproducibility and general applicability the threshold-based and fixed dimension methods are the best ROI methods. Threshold methods are in addition relatively independent of changes in size and geometry, however, and may therefore be more suitable for response monitoring purposes.

Narrow time-window dual-point 18F-FDG PET for the diagnosis of thoracic malignancy

Dual time-point imaging has been proposed as a means of improving the accuracy of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) for the diagnosis of malignant pulmonary nodules. The purpose of this study was to evaluate a dual time-point protocol that has a narrow time window between its initial and its delayed imaging sessions. All patients examined during a 16-month time period, either for the diagnosis of a radiographically indeterminate thoracic lesion or for the staging of non-small-cell carcinoma, were included in the study provided that they completed the dual-point protocol and had either biopsy evidence of malignancy, biopsy evidence of a benign condition involving the thoracic lesion of concern, or clinical and radiographic follow-up consistent with the absence of malignancy. The entire study population was further divided into a central subpopulation, whose index lesions were adjacent to or within the hilum or mediastinum, and a peripheral subpopulation, whose index lesions were non-central. The maximum standardized uptake value (SUV) was measured for each lesion, and various body surface areas (BSAs) and glucose corrections on the SUV were compared using discriminant analysis. BSA corrected SUVs for the initial (iSUV) and the delayed (dSUV) imaging sessions, along with their absolute difference (deltaSUV) and fractional difference (fSUV) were also compared using discriminant analysis and receiver operating characteristic (ROC) analysis. The study population consisted of 132 patients, of whom 81 had malignancy and 51 were classified as having a benign condition. Thirty-three index lesions were central and 99 were peripheral; 109 had visible uptake and 23 had such low uptake that they were not visible above background. The mean time (+/-SD) between initial and delayed imaging for the visible lesions was 31.1+/-9.4 min. With respect to the entire study population, the BSA replacement for body weight gave the best performance among the various SUV corrections examined. In addition, the BSA corrected delayed SUV (dSUV) gave a performance superior to either initial SUV (iSUV), absolute difference in SUV (deltaSUV) and fractional difference in SUV (fSUV) alone. Performance gains achieved by BSA correction and by dSUV appeared to derive primarily from the central subpopulation, thereby indicating that central lesions tend to behave differently to peripheral ones. For the central subpopulation, ROC analysis also demonstrated improved detection of malignancy from dual-point imaging. The best performance was achieved when the BSA corrected dSUV was at least 2.4, or when the fSUV showed at least a 5% increase from initial to delayed imaging. With the optimal combined dSUV/fSUV strategy, the area under the ROC curve was 0.99, as opposed to 0.96 for dSUV alone, or 0.93 for iSUV alone. The ability of 18F-FDG PET to discriminate between benign and malignant conditions of the central thorax can be improved by correcting the SUV for BSA and by increasing the 'incubation time' between 18F-FDG injection and imaging, or by performing narrow time-window dual-point imaging.

Can FDG-PET reduce the need for mediastinoscopy in potentially resectable nonsmall cell lung cancer?

BACKGROUND

Few fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) nonsmall cell lung cancer (NSCLC) trials have had sufficient patients to adequately evaluate PET for mediastinal staging. We question whether once PET is performed, is mediastinoscopy necessary?

METHODS

We performed a 5-year retrospective analysis of operable patients with known or suspicious NSCLC. Standard PET techniques were used. Inclusion criteria were (1) surgical mediastinal nodal sampling by mediastinoscopy within 31 days of the PET and (2) definitive diagnosis.

RESULTS

There were 237 patients who met the evaluation criteria; ninety-nine patients with NSCLC and 138 with suspicious lesions (137 men and 100 women; aged 20 to 88 years). The PETs were performed from 0 to 29 days before mediastinoscopy (median, 7 days). The standardized uptake value for the primary lesion was 0 to 24.6 (7.9+/-5.0). Nine primary lesions had no FDG uptake (1 benign, 8 NSCLCs). Seventy-one patients (31%) had mediastinal PET positive disease, and 44 patients (19%) had histologic positive mediastinal disease; N2 41 patients (17%) and N3 9 patients (4%). In 6 patients (3%), the initial frozen sections were negative, but PET positivity encouraged further biopsies that were positive for cancer. The PET sensitivity was 82%, specificity 82%, accuracy 82%, negative predictive value 95%, and positive predictive value was 51%. All primary lesions with a standardized uptake value less than 2.5 and a negative mediastinal PET were negative histologically (n = 29). Logistic regression analysis resulted in 100% specificity for PET in this group.

CONCLUSIONS

In NSCLC PET may reduce the necessity for mediastinoscopy when the primary lesion standardized uptake value is less than 2.5 and the mediastinum is PET negative. Accepting this approach in our patient population, the need for mediastinoscopy would have been reduced by 12%.

Evaluation of various corrections to the standardized uptake value for diagnosis of pulmonary malignancy

OBJECTIVE

Standard uptake values (SUVs) are widely used for quantifying the uptake of 18F-fluorodeoxyglucose (18F-FDG) in tumours. The objective of this study was to evaluate the accuracy of SUVs for malignancy in lung nodules/masses and to analyse the effects of tumour size, blood glucose levels and different body weight corrections on SUV.

METHODS

One hundred and twenty-seven patients with suspicious lung lesions imaged with 18F-FDG positron emission tomography (PET) were studied retrospectively. Pathology results were used to establish lesion diagnosis in all cases. SUVs based on maximum pixel values were obtained by placing regions of interest around the focus of abnormal 18F-FDG uptake in the lungs. The SUVs were calculated using the following normalizations: body weight (BW), lean body weight (LBW), scaled body surface area (BSA), blood glucose level (Glu) and tumour size (Tsize). Receivers operating characteristic (ROC) curves were generated to compare the accuracy of different methods of SUV calculation.

RESULTS

The areas under the ROC curves for SUV(BW), SUV(BW+Glu), SUV(LBW), SUV(LBW+Glu), SUV(BSA), SUV(BSA+Glu) and SUV(BW+Tsize) were 0.915, 0.912, 0.911, 0.912, 0.916, 0.909 and 0.864, respectively.

CONCLUSION

The accuracy of SUV analysis for malignancy in lung nodules/masses is not improved by correction for blood glucose or tumour size or by normalizing for body surface area or lean body weight instead of body weight.