Predictive and prognostic value of metabolic tumour volume and total lesion glycolysis in solid tumours

Prognostic value of metabolic tumour volume and total lesion glycolysis measured by 18F-fluorodeoxyglucose positron emission tomography/computed tomography in small cell lung cancer: A systematic review and meta-analysis

The aim of this study was to evaluate the prognostic value of metabolic tumour volume (MTV) and total lesion glycolysis (TLG) for small cell lung cancer (SCLC). MEDLINE, EMBASE and Cochrane Library databases were systematically searched. The pooled hazard ratio (HR) was used to measure the influence of MTV and TLG on survival. The subgroup analysis according to VALSG stage and the measured extent of MTV was performed. Patients with high MTV values experienced a significantly poorer prognosis with a HR of 2.42 (95% CI 1.46-4.03) for overall survival (OS) and a HR of 2.78 (95% CI 1.39-5.53) for progression-free survival (PFS) from the random effect model, and the pooled HR from the fixed effect model was 2.10 (95% CI 1.77-2.50) for OS and 2.27 (95% CI 1.83-2.81) for PFS. Patients with high TLG experienced a poorer prognosis with a HR of 1.61 (95% CI: 1.24-2.07) for OS from the random effect model, and the pooled HR from the fixed effect model was 1.64 (95% CI 1.37-1.96). Heterogeneity among studies was high for MTV in both OS and PFS meta-analyses (I²  = 87% and 88% respectively). After removing one outlier study the heterogeneity was substantially reduced (I²  = 0%) and the pooled HR for the effect of MTV on OS was 1.80 (1.51-2.16, P < 0.00001), and on PFS it was 1.86 (1.49-2.33, P < 0.00001), using either the fixed or random effects model. High MTV is associated with a significantly poorer prognosis OS and PFS, and high TLG is associated with a significantly poorer prognosis regarding OS for SCLC.

The value of different 18F-FDG PET/CT baseline parameters in risk stratification of stage I surgical NSCLC patients

OBJECTIVE

Administration of postoperative chemotherapy to patients with completely resected stage I NSCLC is still a matter of debate. The aim of the present study was to evaluate the value of different baseline ¹⁸F-FDG PET parameters in identifying surgical stage I NSCLC patients who are at high risk of recurrence, and thus are indicated for further postoperative treatment.

METHODS

This is a retrospective study, which included 49 patients (28 males, 21 females) with the median age of 69 years (range 28-84), who had pathologically proven stage I NSCLC. All patients underwent ¹⁸F-FDG PET/CT at baseline followed by complete surgical resection of the tumor (R0). Baseline SUV_max, MTV and TLG were measured. Patients' follow-up records were retrospectively reviewed, and DFS (disease-free survival) was assessed. For each parameter, the most accurate cut-off value for the prediction of recurrence was calculated using the ROC curve analysis and the Youden index. DFS was evaluated for patients above and below the calculated cut-off value using the Kaplan-Meier method and the difference in survival between the two groups was estimated using the log-rank test.

RESULTS

Median observation time of the patients after surgery was 28.7 months (range 3.5-58.8 months). 9 patients developed recurrence. The calculated cut-off values for SUV_max, MTV and TLG were 6, 6.6 and 33.6, respectively. Using these cut-offs, the observed sensitivity for SUV_max, MTV and TLG for prediction of recurrence was 100%, 89% and 89%, respectively, while the observed specificity was 43%, 73% and 65%, respectively. The difference in survival between patients below and above the cut-off value was statistically significant in all three studied parameters. The highest AUC was observed for MTV (AUC = 0.825, p = 0.003), followed by TLG (AUC = 0.789, p = 0.007), and lastly SUV_max (AUC = 0.719, p = 0.041). ROC curve analysis showed that volumetric parameters had better predictive performance than SUV_max as regards recurrence.

CONCLUSION

PET-derived parameters at baseline were predictive of recurrence in stage I surgical NSCLC patients. Moreover, the metabolic volume of the tumor was the most significant parameter for this purpose among the studied indices.

Novel Quantitative PET Techniques for Clinical Decision Support in Oncology

Quantitative image analysis has deep roots in the usage of positron emission tomography (PET) in clinical and research settings to address a wide variety of diseases. It has been extensively employed to assess molecular and physiological biomarkers in vivo in healthy and disease states, in oncology, cardiology, neurology, and psychiatry. Quantitative PET allows relating the time-varying activity concentration in tissues/organs of interest and the basic functional parameters governing the biological processes being studied. Yet, quantitative PET is challenged by a number of degrading physical factors related to the physics of PET imaging, the limitations of the instrumentation used, and the physiological status of the patient. Moreover, there is no consensus on the most reliable and robust image-derived PET metric(s) that can be used with confidence in clinical oncology owing to the discrepancies between the conclusions reported in the literature. There is also increasing interest in the use of artificial intelligence based techniques, particularly machine learning and deep learning techniques in a variety of applications to extract quantitative features (radiomics) from PET including image segmentation and outcome prediction in clinical oncology. These novel techniques are revolutionizing clinical practice and are now offering unique capabilities to the clinical molecular imaging community and biomedical researchers at large. In this report, we summarize recent developments and future tendencies in quantitative PET imaging and present example applications in clinical decision support to illustrate its potential in the context of clinical oncology.

Prognostic value of SUR in patients with trimodality treatment of locally advanced esophageal carcinoma

The prognosis of patients with esophageal carcinoma remains dismal despite ongoing efforts to improve treatment options. For locally advanced tumors, several randomized trials have shown the benefit of neoadjuvant chemoradiation followed by surgery compared to surgery alone. The aim of this exploratory study was to evaluate the prognostic value of different baseline positron emission tomography (PET) parameters and their potentially additional prognostic impact at the end of neoadjuvant radiochemotherapy. Furthermore, the standard uptake ratio (SUR) as a new parameter for quantification of tumor metabolism was compared to the conventional PET parameters metabolic active volume (MTV), total lesion glycolysis (TLG), and standardized uptake value (SUV) taking into account known basic parameters. Methods:18F-FDG-PET/CT was performed in 76 consecutive patients ((60±10) years, 71 males) with newly diagnosed esophageal cancer before and during the last week of neoadjuvant radiochemotherapy. MTV of the primary tumor was delineated with an adaptive threshold method. The blood SUV was determined by manually delineating the aorta in the low dose CT. SUR values were computed as scan time corrected ratio of tumor SUVmax and mean blood SUV. Univariate Cox regression and Kaplan-Meier analysis with respect to locoregional control (LRC), freedom from distant metastases (FFDM), and overall survival (OS) was performed. Additionally, independence of PET parameters from standard clinical factors was analyzed with multivariate Cox regression. Results: In multivariate analysis two parameters showed a significant correlation with all endpoints: restaging MTV and restaging SUR. Furthermore, restaging TLG was prognostic for LCR and FFDM. For all endpoints the largest effect size was found for restaging SUR. The only basic factors remaining significant in multivariate analyses were histology for OS and FFDM and age for LRC. Conclusion: PET provides independent prognostic information for OS, LRC, and FFDM in addition to standard clinical parameters in this patient cohort. Our results suggest that the prognostic value of tracer uptake can be improved when characterized by SUR rather than by SUV. Overall, our investigation revealed a higher prognostic value of restaging parameters compared to baseline PET; therapy-adjustments would still be possible at this point of time. Further investigations are required to confirm these hypothesis-generating results.

[Surgery after upfront radiochemotherapy for locally advanced esophageal cancer: To do or not to do?]

The treatment of locally advanced esophageal cancer is still evolving. Surgery was considered as the backbone of the therapeutic management for a long time. Nowadays, chemoradiation has taken a major place in the neoadjuvant setting or as an exclusive treatment. Although some patients benefit from esophagectomy after chemoradiotherapy, a large subset of patients has no benefit and morbi-mortality rates are increased with a trimodality strategy. Patients who will have a local failure are at high risk of distant metastases in the follow-up. A third group of patients will have persistent locoregional disease after chemoradiotherapy and may benefit from surgery, but only a minority of patients with locally advanced disease are eligible. The impact of surgery after upfront chemoradiotherapy on survival and the quality of life of patients with locally advanced squamous cell esophageal cancer remain uncertain. An active surveillance strategy after chemoradiation or salvage esophagectomy for a locally residual disease might improve the prognosis of these patients. An optimized bimodality such as chemoradiotherapy delivering at least 50Gy is still standard and salvage surgery for local persistent disease or a local failure must be discussed in the framework of a multidisciplinary group for selected patients only.

The assessment of correlation and prognosis among 18F-FDG uptake parameters, Glut1, pStat1 and pStat3 in surgically resected non-small cell lung cancer patients

Introduction

To assess the correlation among ¹⁸F-FDG uptake, Glut1, pStat1 and pStat3, and to investigate the relationship between the prognosis and ¹⁸F-FDG uptake and these molecular markers in surgically resected non-small cell lung cancer (NSCLC) patients.

Results

Knockdown of Glut1 led to a significant increase in pStat1 expression. Glut1 expression positively correlated with the SUVmax, SUVmean, and TLG significantly (P<0.001). pStat3 expression negatively correlated with all PET parameters significantly (P<0.001). pStat1 had positive weak correlations with the SUVmax and SUVmean. All PET parameters and Glut1 were significantly associated with DFS (P<0.05). TLG, MTV, Glut1 and pStat1 were significantly associated with OS (P<0.05).

Conclusion

pStat3 and Glut1 may be associated with ¹⁸F-FDG uptake mechanism. TLG, MTV, and Glut1 may be independent prognostic factors.

Methods

The SUVmax, SUVmean, MTV and TLG of primary lesions were calculated in 140 patients. The expressions of Glut1 and Stat pathway proteins in NSCLC cell lines were examined by immune blots. Excised tumor tissue was analyzed by immunohistochemistry. OS and DFS were evaluated by the Kaplan-Meier method. The difference in survival between subgroups was analyzed by log-rank test. The prognostic significance of clinicopathological, molecular and PET parameters was assessed by Cox proportional hazard regression analysis.

Precision diagnostics of Ewing's sarcoma by liquid biopsy: circulating EWS-FLI1 fusion transcripts

Background:

Limited information is available on the applicative value of liquid biopsy (LB) in rare tumors, including Ewing’s sarcoma (ES). The accepted precision diagnostics standards would greatly benefit from a non-invasive LB test monitoring pathognomonic gene rearrangements in the bloodstream.

Methods:

Tissue and blood samples were collected from six and four ES patients, respectively. Plasma was cleared by two successive rounds of centrifugation and stored frozen until RNA extraction by the QIAmp CNA kit. RNA was retro-transcribed and subjected to real-time quantitative polymerase chain reaction (RT-qPCR) and digital polymerase chain reaction (dPCR). Reactions were set up using two custom primer sets identifying types 1 and 2 EWS-FLI1 fusion transcripts.

Results:

The two prevalent types of EWS-FLI1 rearrangements could be identified using only two sets of polymerase chain reaction primers, regardless of patient-specific EWS-FLI1 DNA breakpoints. RT-qPCR and dPCR discriminated the two variants in five tumor tissue RNAs and in four circulating tumor RNAs (ctRNAs). Of note, EWS-FLI1 molecular diagnosis was possible using blood samples even when tumor tissue was not available. ctRNA levels correlated (p < 0.05) with volume-based positron emission tomography (PET) parameters (metabolic tumor volume and total lesion glycolysis), and allowed the fine tracking of disease course after surgery, during adjuvant as well as neoadjuvant chemotherapy, and at follow up in one patient.

Conclusions:

To our knowledge, this is one of the few single-marker LB assays in solid tumors specifically designed to detect rearranged RNAs in blood, and the first study describing EWS circulating tumor RNAs in ES patients. Altogether, our results support the idea that LB may have a considerable impact on ES patient monitoring and management.

Use of baseline 18F-FDG PET scan to identify initial sub-volumes with local failure after concomitant radio-chemotherapy in head and neck cancer

Introduction

Head and neck squamous cell carcinoma (HNSCC) treated by radio-chemotherapy have a significant local recurrence rate. It has been previously suggested that 18F-FDG PET could identify the high uptake areas that can be potential targets for dose boosting. The purpose of this study was to compare the location of initial hypermetabolic regions on baseline scans with the metabolic relapse sites after radio-chemotherapy in HNSCC.

Results

The initial functional tumor volume was significantly higher for patients with proven local recurrence or residual disease (23.5 cc vs. 8.9 cc; p = 0.0005). The overlap between baseline and follow-up sub-volumes were moderate with an overlap fraction ranging from 0.52 to 0.39 between R40 and I30 to I60.

Conclusion

In our study the overlap between baseline and post-therapeutic metabolic tumor sub-volumes was only moderate. These results need to be investigated in a larger cohort acquired with a more standardized patient repositioning protocol for sequential PET imaging.

Methods

Pre and post treatment PET/CT scans of ninety four HNSCC patients treated with radio-chemotherapy were retrospectively reviewed. Follow-up 18F-FDG PET/CT images were registered to baseline scans using a rigid body transformation. Seven metabolic tumor sub-volumes were obtained on the baseline scans using a fixed percentage of SUV_max (I30, I40, I50, I60, I70, I80, and I90) and were subsequently compared with two post-treatment sub-volumes (R40, R90) in 38 cases of local recurrence or residual metabolic disease. Overlap fraction, Dice and Jaccard indices, common volume/baseline volume and common volume/recurrent volume were used to determine the overlap of the different estimated sub-volumes.

The prognostic value of volume-based parameters using 18F-FDG PET/CT in gastric cancer according to HER2 status

BACKGROUND

We aimed to find the clinical value of metastatic tumor burden evaluated with F18-FDG PET/CT in gastric cancer patients, considering the human epidermal growth factor receptor 2 (HER2) status.

METHODS

We retrospectively reviewed 124 patients with locally advanced or metastatic gastric cancer at Yonsei Cancer Center between January 2006 and December 2014 who had undergone baseline FDG PET/CT before first-line chemotherapy. We measured the maximum standardized uptake value from the primary tumor (SUV_max) and whole-body (WB) PET/CT parameters, including WB SUV_max, WB SUV_mean, WB metabolic tumor volume (WB MTV), and WB total lesion glycolysis (WB TLG), in all metabolically active metastatic lesions (SUV threshold ≥2.5 or 40% isocontour for ≤2.5), and we determined their association with patient survival outcomes.

RESULTS

SUV_max was higher in HER2-positive gastric cancers (median 12.1, range 3.4-34.6) compared to HER-2 negative (7.4, 1.6-39.1, P < 0.001). Among all patients, WB TLG > 600, which is indicative of a high metastatic tumor burden, showed worse progression-free survival (PFS) [hazard ratio (HR), 2.003; 95% CI, 1.300-3.086; P = 0.002] and overall survival (OS) (HR, 3.001; 95% CI, 1.950-4.618; P < 0.001) than did WB TLG ≤ 600. Among HER2-positive gastric cancer patients treated with trastuzumab, higher metabolic tumor burden predicted worse OS, but not PFS.

CONCLUSIONS

HER2-positive gastric cancers had higher SUV_max compared to HER2-negative gastric cancers. In both HER2-negative patients and -positive patients receiving trastuzumab, FDG PET/CT volume-based parameters may have a role in further stratifying the prognosis of stage IV gastric cancer.

Diagnostic Value of Volume-Based Fluorine-18-Fluorodeoxyglucose PET/CT Parameters for Characterizing Thyroid Incidentaloma

Objective

To assess clinical value of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for differentiation of malignant from benign focal thyroid incidentaloma.

Materials and Methods

This retrospective study included 99 patients with focal thyroid incidentaloma of 5216 non-thyroid cancer patients that had undergone PET/CT. PET/CT semi-quantitative parameters, volume-based functional parameters, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of thyroid incidentaloma were assessed. Receiver-operating characteristic (ROC) analysis was conducted and areas under the curve (AUC) were compared by Hanley and McNeil test to evaluate usefulness of maximum standardized uptake value (SUVmax), MTV and TLG, as markers for differentiating malignant from benign thyroid incidentalomas.

Results

Of 99 thyroid incidentalomas, 64 (64.6%) were malignant and 35 (35.4%) were benign. Malignant thyroid incidentalomas were larger (1.8 cm vs. 1.3 cm, p = 0.006), and had higher SUVmax (11.3 vs. 4.8, p < 0.001), MTV (all p < 0.001) and TLG (all p < 0.001) than benign. TLG 4.0 had the highest performance for differentiation of malignant from benign thyroid incidentaloma in all semi-quantitative parameters with AUC 0.895 by ROC curve analysis. AUC (TLG 4.0) was significantly larger than AUC (SUVmean), AUC (MTV 2.5), AUC (MTV 3.0), AUC (MTV 3.5), AUC (TLG 2.5), and AUC (TLG 3.0), respectively (all, p < 0.05). There was no statistical difference between AUC (TLG 4.0) and AUC (SUVmax) (p > 0.05). A threshold TLG 4.0 of 2.475 had 81.3% sensitivity and 94.3% specificity for identifying malignant thyroid incidentalomas.

Conclusion

Volume-based PET/CT parameters could potentially have clinical value in differential diagnosis of thyroid incidentaloma along with SUVmax.

Monitoring tumor response to the vascular disrupting agent CKD-516 in a rabbit VX2 intramuscular tumor model using PET/MRI: Simultaneous evaluation of vascular and metabolic parameters

OBJECTIVES

To determine whether the CKD-516 produces a significant change in vascular and metabolic parameters in PET/MRI.

MATERIALS AND METHODS

With institutional Animal Care and Use Committee approval, 18 VX2 carcinoma tumors implanted in bilateral back muscles of 9 rabbits were evaluated. Serial PET/MRI were performed before, 4 hours after and 1-week after vascular disrupting agent, CKD-516 at a dose of 0.7 mg/kg (treated group, n = 10) or saline (control group, n = 8) administration. PET/MRI-derived parameters and their interval changes were compared between the treated and control group by using the linear mixed model. Each parameter within each group was also compared by using the linear mixed model.

RESULTS

Changes of the volume transfer coefficient (Ktrans) and the initial area under the gadolinium concentration-time curve until 60 seconds (iAUC) in the treated group were significantly larger compared with those in the control group at 4-hour follow-up (mean, -39.91% vs. -6.04%, P = 0.018; and -49.71% vs. +6.23%, P = 0.013). Change of metabolic tumor volume (MTV) in the treated group was significantly smaller compared with that in the control group at 1-week follow-up (mean, +118.34% vs. +208.87%, P = 0.044). Serial measurements in the treated group revealed that Ktrans and iAUC decreased at 4-hour follow-up (P < 0.001) and partially recovered at 1-week follow-up (P = 0.001 and 0.024, respectively). MTV increased at a 4-hour follow-up (P = 0.038) and further increased at a 1-week follow-up (P < 0.001), while total lesion glycolysis (TLG) did not show a significant difference between the time points. SUVmax and SUVmean did not show significant interval changes between time points (P > 0.05).

CONCLUSIONS

PET/MRI is able to monitor the changes of vascular and metabolic parameters at different time points simultaneously, and confirmed that vascular changes precede the metabolic changes by VDA, CKD-516.

Prognostic value of tumor volume in patients with head and neck squamous cell carcinoma treated with primary surgery

BACKGROUND

Tumor volume in head and neck squamous cell carcinoma (HNSCC) was mainly measured in nonsurgically treated patients. We analyzed the influence of tumor volume on complete response (CR), overall survival (OS), and clear surgical margins also in primarily surgically treated patients.

METHODS

In contrast-enhanced CTs, the tumor volumes of patients with incident HNSCC were measured.

RESULTS

The tumor volumes of 259 patients were measured, of which 125 patients (48%) underwent primary surgery and 102 patients (84%) had clear margins. The tumor volume was not an independent factor for CR at the primary tumor site. Risk of death increased by 1.4% per mL of tumor volume (95% confidence interval [CI] 0.8%-2.0%; P < .001). The OS was better in patients treated with primary surgery, if the tumor volume was ≤12 mL (P < .001). Risk of involved margins increased by 4.5% per mL of tumor volume (95% CI 0.9%-8.3%; P = .003). The predicted probability of clear margins was ≥80% in tumor volumes ≤ 16 mL.

CONCLUSION

The tumor volume had an impact on CR, OS, and clear margins. The tumor volume may also aid in selecting HNSCC treatment.

Prognostic significance of interim 18 F-fluorodeoxyglucose positron emission tomography-computed tomography volumetric parameters in metastatic or recurrent gastric cancer

AIM

To evaluate the prognostic role of interim analysis of 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) volumetric parameters in patients with recurrent or metastatic advanced gastric cancer (AGC) treated with fluoropyrimidine-based palliative chemotherapy.

METHODS

Forty-four patients who underwent baseline and interim PET/CT scanning during palliative chemotherapy were analyzed retrospectively. Initial and change of metabolic parameters (MP) - metabolic tumor volume (MTV), tumor lesion glycolysis (TLG) and maximum and mean standardized uptake values (SUV) were measured with PET/CT. Metabolic change was measured by ∆MP (%)  =  (MP_interim  - MP_initial )/MP _initial   ×  100. Independent t-test was employed to compare values of initial, interim and change of metabolic parameters between each response group. Log-rank test was employed for univariate analysis, and multivariate analysis was performed using the Cox proportional hazards regression model to determine independently significant prognostic factors.

RESULTS

Reduced percentage values of maximum and mean SUV on interim PET/CT and initial values of volumetric parameters (MTV and TLG) were significant predicting factors to response to fluoropyrimidine-based palliative chemotherapy. The decreased percentage values of metabolic parameters as well as maximum and mean SUV with receiver operating characteristic (ROC) curve determined cut-off points were significant prognostic factors for overall survival and progression-free survival in univariate and multivariate analyses.

CONCLUSION

Measurement of metabolic decrease of volumetric parameters by interim PET/CT analysis is useful to determine the prognosis of patients with recurrent or metastatic AGC.

Circulating androgen receptor combined with 18F-fluorocholine PET/CT metabolic activity and outcome to androgen receptor signalling-directed therapies in castration-resistant prostate cancer

The association between choline uptake and androgen receptor (AR) expression is suggested by the upregulation of choline kinase-alpha in prostate cancer. Recently, detection of AR aberration in cell-free DNA as well as early 18F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT) were associated with outcome in metastatic castration-resistant prostate cancer (mCRPC) patients treated with abiraterone and enzalutamide. We aimed to make a direct comparison between circulating AR copy number (CN) and choline uptake at FCH-PET/CT. We analysed 80 mCRPC patients progressing after docetaxel treated with abiraterone (n = 47) or enzalutamide (n = 33). We analysed AR CN from plasma samples using digital PCR and Taqman CN assays and total lesion activity (TLA) and metabolic tumor volume (MTV) on FCH-PET/CT at baseline. A meaningful correlation was showed among AR gain and TLA/MTV compared to AR non-gained cases (P = 0.001 and P = 0.004, respectively), independently from type of treatment. Multivariate analysis revealed that AR CN and only TLA were associated with both shorter PFS (P < 0.0009 and P = 0.026, respectively) and OS (P < 0.031 and P = 0.039, respectively). AR gain appeared significantly correlated with choline uptake represented mainly by TLA. Further prospective studies are warranted to better address this pathway of AR-signalling and to identify multiplex biomarker strategies including plasma AR and FCH-PET/CT in mCRPC patients.

Verification of the tumor volume delineation method using a fixed threshold of peak standardized uptake value

We aimed to determine the difference in tumor volume associated with the reconstruction model in positron-emission tomography (PET). To reduce the influence of the reconstruction model, we suggested a method to measure the tumor volume using the relative threshold method with a fixed threshold based on peak standardized uptake value (SUV_peak). The efficacy of our method was verified using ¹⁸F-2-fluoro-2-deoxy-D-glucose PET/computed tomography images of 20 patients with lung cancer. The tumor volume was determined using the relative threshold method with a fixed threshold based on the SUV_peak. The PET data were reconstructed using the ordered-subset expectation maximization (OSEM) model, the OSEM + time-of-flight (TOF) model, and the OSEM + TOF + point-spread function (PSF) model. The volume differences associated with the reconstruction algorithm (%VD) were compared. For comparison, the tumor volume was measured using the relative threshold method based on the maximum SUV (SUV_max). For the OSEM and TOF models, the mean %VD values were -0.06 ± 8.07 and -2.04 ± 4.23% for the fixed 40% threshold according to the SUV_max and the SUV_peak, respectively. The effect of our method in this case seemed to be minor. For the OSEM and PSF models, the mean %VD values were -20.41 ± 14.47 and -13.87 ± 6.59% for the fixed 40% threshold according to the SUV_max and SUV_peak, respectively. Our new method enabled the measurement of tumor volume with a fixed threshold and reduced the influence of the changes in tumor volume associated with the reconstruction model.

The role of F-18 FDG PET/CT in evaluating the impact of HIV infection on tumor burden and therapy outcome in patients with Hodgkin lymphoma

BACKGROUND

To evaluate the impact of HIV infection on tumor burden and therapy outcome following treatment with chemotherapy in patients with Hodgkin lymphoma.

METHODS

A total of 136 patients with classical Hodgkin lymphoma were studied (mean age ± SD = 32.31 ± 1.39 years, male = 86, female = 50). Advanced disease (stage III and IV) was present in 64% of patients. HIV infection was present in 57 patients while 79 patients were HIV-negative. Baseline F-18 FDG PET/CT was obtained in all patients. SUVmax, MTV and TLG were determined on the baseline scan to evaluate for tumor burden. All patients completed a standard regimen of adriamycin, bleomycin, vinblastine and dacarbazine (ABVD). After a median period of 8 weeks (range = 6 to 17 weeks), a repeat F-18 FDG PET/CT scan was obtained to evaluate response to therapy using Deauville 5-point scoring system.

RESULTS

The HIV-positive and HIV-negative groups were similar with regards to age and disease stage. The groups were heterogeneous with respect to gender (p = 0.029). The SUVmax, MTV and TLG of lesions were not significant different between the two groups. Complete response was seen in 72.8% of the study population. Presence of HIV infection was associated with higher rate of treatment failure with 40.4% of the HIV-positive patients having treatment failure while only 17.7% of the HIV-negative patients had treatment failure (p = 0.0034). HIV infection was a significant predictor of response to chemotherapy. Effects of SUVmax, MTV, TLG and Ann Arbor stage of the disease were not statistically significant as predictors of therapy outcome. In a multiple logistic regression, presence of HIV infection still remained an independent predictor of therapy outcome in the presence of other factors such as SUVmax, MTV, TLG and the Ann Arbor stage of the disease.

CONCLUSIONS

HIV infection is not associated with a higher tumor burden in patients with Hodgkin lymphoma. HIV infection is, however, a strong predictor of poor therapy outcome in patients treated with standard regimen of ABVD.

A pilot study of the diagnostic and prognostic values of FLT-PET/CT for pancreatic cancer: comparison with FDG-PET/CT

PURPOSE

The purpose of the study was to examine the diagnostic and prognostic values of ¹⁸F-fluorothymidine (FLT)-PET/CT for pancreatic cancer by comparing with ¹⁸F-fluorodeoxyglucose (FDG)-PET/CT.

METHODS

Fifteen patients with newly diagnosed pancreatic cancer underwent both FLT and FDG-PET/CT scans before treatment. The sensitivity, specificity, and accuracy in detecting nodal and distant metastases were compared between both scans using McNemar exact or χ ² test. Progression-free survival (PFS) and overall survival (OS) were calculated by Kaplan-Meier method. Prognostic significance was assessed by Cox proportional hazards analysis.

RESULTS

Both scans visualized all primary cancers. The sensitivity, specificity, and accuracy per patient basis for detecting nodal metastasis were equal and 63.6% (7/11), 100% (4/4), and 73.3% (11/15) for both scans, and for detecting distant metastasis were 100% (6/6), 88.9% (8/9), and 93.3% (14/15) for FDG-PET/CT, and 50.0% (3/6), 100% (9/9), and 80.0% (12/15) for FLT-PET/CT, respectively, without significant difference in each of them between both scans (p > 0.05). However, of 4 patients with multiple liver metastases, FDG-PET/CT was positive in all, but FLT-PET/CT was negative in three patients. At univariate analysis, only FLT-SUV_max correlated with PFS (hazard ratio, 1.306, p = 0.048), and FDG total lesion glycolysis (TLG), FLT-SUV_max, and FLT-total lesion proliferation (TLP) correlated with OS (p = 0.021, p = 0.005, and p = 0.022, respectively). At bivariate analysis, FLT-SUV_max was superior to FDG-TLG or FLT-TLP for prediction of OS [HR (adjusted for FDG-TLG), 1.491, p = 0.034, HR (adjusted for FLT-TLP), 1.542, p = 0.023].

CONCLUSION

FLT-PET/CT may have a potential equivalent to FDG-PET/CT for detecting primary and metastatic cancers except liver metastasis. FLT-SUV_max can provide the most significant prognostic information.

Predictive value of initial FDG-PET features for treatment response and survival in esophageal cancer patients treated with chemo-radiation therapy using a random forest classifier

Purpose

In oncology, texture features extracted from positron emission tomography with 18-fluorodeoxyglucose images (FDG-PET) are of increasing interest for predictive and prognostic studies, leading to several tens of features per tumor. To select the best features, the use of a random forest (RF) classifier was investigated.

Methods

Sixty-five patients with an esophageal cancer treated with a combined chemo-radiation therapy were retrospectively included. All patients underwent a pretreatment whole-body FDG-PET. The patients were followed for 3 years after the end of the treatment. The response assessment was performed 1 month after the end of the therapy. Patients were classified as complete responders and non-complete responders. Sixty-one features were extracted from medical records and PET images. First, Spearman’s analysis was performed to eliminate correlated features. Then, the best predictive and prognostic subsets of features were selected using a RF algorithm. These results were compared to those obtained by a Mann-Whitney U test (predictive study) and a univariate Kaplan-Meier analysis (prognostic study).

Results

Among the 61 initial features, 28 were not correlated. From these 28 features, the best subset of complementary features found using the RF classifier to predict response was composed of 2 features: metabolic tumor volume (MTV) and homogeneity from the co-occurrence matrix. The corresponding predictive value (AUC = 0.836 ± 0.105, Se = 82 ± 9%, Sp = 91 ± 12%) was higher than the best predictive results found using the Mann-Whitney test: busyness from the gray level difference matrix (P < 0.0001, AUC = 0.810, Se = 66%, Sp = 88%). The best prognostic subset found using RF was composed of 3 features: MTV and 2 clinical features (WHO status and nutritional risk index) (AUC = 0.822 ± 0.059, Se = 79 ± 9%, Sp = 95 ± 6%), while no feature was significantly prognostic according to the Kaplan-Meier analysis.

Conclusions

The RF classifier can improve predictive and prognostic values compared to the Mann-Whitney U test and the univariate Kaplan-Meier survival analysis when applied to several tens of features in a limited patient database.

Correlation between fluorodeoxyglucose hotspots on pretreatment positron emission tomography/CT and preferential sites of local relapse after chemoradiotherapy for head and neck squamous cell carcinoma

BACKGROUND

The potential benefits of ¹⁸ F-fluoro-2-deoxy-D-glucose-positron emission tomography/CT (FDG-PET/CT) imaging for radiotherapy (RT) treatment planning of head and neck squamous cell carcinoma (HNSCC) are increasingly being recognized. It has been suggested that intratumoral subvolumes with high FDG avidity ("hotspots") are potential targets for selected dose escalation. The purposes of this study were to demonstrate that pre-RT FDG-PET/CT can identify intratumoral sites at increased risk of local relapse after RT and to determine an optimal threshold to delineate smaller RT target volumes that would facilitate RT dose escalation without impaired tolerance.

METHODS

Seventy-two consecutive patients with locally advanced HNSCC treated by RT ± chemotherapy were included in this study. All patients underwent FDG-PET/CT at initial staging (PET_A ) and during systematic follow-up (PET_R ). FDG-PET/CT was coregistered on the initial CT scan with a rigid method. Various subvolumes (A_X ; × = 30%, 40%, 50%, 60%, 70%, 80%, and 90% standardized uptake value maximum [SUVmax] thresholds) within the primary tumor and in the subsequent local relapse (R_X ; × = 40% and 70% SUVmax thresholds) were compared together (Dice, Jaccard, overlap fraction, common volume/baseline volume, and common volume/recurrent volume).

RESULTS

Nineteen patients (26%) had local relapses. Using a 40% SUVmax threshold, the initial metabolic tumor volume was significantly higher in patients with local relapses than in controlled patients (10.4 ± 8.6 vs 5.1 ± 4.9 cc; p = .002) as well as total lesion glycolysis (117.9 ± 88.6 vs 60.6 ± 80.4; p = .013). For both methods, the overlap index among A₃₀ , A₄₀ , and A₅₀ subvolumes on PET_A and the whole metabolic volume of recurrence R₄₀ and R₇₀ on PET_R showed a moderate agreement (0.52 to 0.43).

CONCLUSION

Our study does not find high overlap index values between the initial tumor and recurrence subvolumes, probably because of a suboptimal coregistration. Our results also confirm that metabolic tumor volume and total lesion glycolysis are independently correlated with recurrence-free survival in patients with HNSCC. Further larger prospective studies with FDG-PET/CT performed in the same RT position and with a validated elastic registration method are needed. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1155-1165, 2017.

Total lesion glycolysis (TLG) as an imaging biomarker in metastatic colorectal cancer patients treated with regorafenib

PURPOSE

This study was performed to evaluate whether fluorine-18 fluorodeoxyglucose positron-emission tomography/computed tomography (FDG PET/CT) could predict treatment outcome of regorafenib in metastatic colorectal cancer (mCRC).

METHODS

Previously treated refractory mCRC patients were enrolled into a prospective biomarker study of regorafenib. For this sub-study, the results of FDG PET/CT scans at baseline and after two cycles of treatment were analyzed. Various metabolic parameters obtained from PET images were analyzed in relation to treatment outcome.

RESULTS

A total of 40 patients were evaluable for PET image analysis. Among various PET parameters, total lesion glycolysis (TLG) measured in the same target lesions for RECIST 1.1 analysis were the most significant in predicting prognosis, with the lowest p-value observed in TLG calculated using the margin threshold of 40 % (TLG_{40 %}). Further analysis using TLG_{40 %} showed significantly longer overall survival (OS) in patients with lower baseline TLG_{40 %} (<151.8) (p = 0.003, median 14.2 vs. 9.1 months in <151.8 and ≥151.8, respectively). Patients showing higher decrease in TLG_{40 %} after treatment showed significantly longer progression-free survival (PFS) (p = 0.001, median 8.0 vs. 2.4 months in %ΔTLG_{40 %} < -9.6 % and ≥ -9.6 %, respectively) and OS (p = 0.002, median 16.4 vs. 9.1 months in %ΔTLG_{40 %} < -9.6 % and ≥ -9.6 %, respectively). The same cutoff could discriminate patients with longer survival among the patients who were under the stable disease category according to RECIST 1.1 (median PFS 8.4 vs. 6.8 months, p = 0.020; median OS 18.3 vs. 11.5 months, p = 0.049).

CONCLUSION

Measurement of TLG can predict treatment outcome of regorafenib in mCRC.

Intratumoral heterogeneity of 18F-FLT uptake predicts proliferation and survival in patients with newly diagnosed gliomas

BACKGROUND

The nucleoside analog 3'-deoxy-3'-¹⁸F-fluorothymidine (FLT) has been investigated for evaluating tumor proliferating activity in brain tumors. We evaluated FLT uptake heterogeneity using textural features from the histogram analysis in patients with newly diagnosed gliomas and examined correlation of the results with proliferative activity and patient prognosis, in comparison with the conventional PET parameters.

METHODS

FLT PET was investigated in 37 patients with newly diagnosed gliomas. The conventional parameters [tumor-to-contralateral normal brain tissue (T/N) ratio and metabolic tumor volume (MTV)] and textural parameters (standard deviation, skewness, kurtosis, entropy, and uniformity) were derived from FLT PET images. Linear regression analysis was used to compare PET parameters and the proliferative activity as indicated by the Ki-67 index. The associations between parameters and overall survival (OS) were tested by Cox regression analysis.

RESULTS

Median OS was 662 days. For the conventional parameters, linear regression analysis indicated a significant correlation between T/N ratio and Ki-67 index (p = 0.02) and MTV and Ki-67 index (p = 0.02). Among textural parameters, linear regression analysis indicated a significant correlation for kurtosis (p = 0.003), entropy (p < 0.001), and uniformity (p < 0.001) as compared to Ki-67 index, exceeding those of the conventional parameters. The results of univariate analysis suggested that skewness and kurtosis were associated with OS (p = 0.03 and 0.02, respectively). Mean survival for patients with skewness values less than 0.65 was 1462 days, compared with 917 days for those with values greater than 0.65 (p = 0.02). Mean survival for patients with kurtosis values less than 6.16 was 1616 days, compared with 882 days for those with values greater than 6.16 (p = 0.006).

CONCLUSIONS

Based on the results of this preliminary study in a small patient population, textural features reflecting heterogeneity on FLT PET images seem to be useful for the assessment of proliferation and for the potential prediction of survival in newly diagnosed gliomas.

The Diagnostic Value of the Correlation between Serum Anti-p53 Antibody and Positron Emission Tomography Parameters in Lung Cancer

OBJECTIVE

Mutations in the p53 gene are the most commonly observed genetic abnormalities in malignancies. The purpose of this study was to assess the diagnostic value of serum anti-p53 antibody (Ab) along with the correlation between serum anti-p53 Ab level and quantitative positron emission tomography (PET) parameters such as maximum standardized uptake value (SUVmax), SUVave, metabolic tumor volume, total lesion glycolysis (TLG) and tumor size.

METHODS

Serum anti-p53 Ab level was studied in three groups. Patients who underwent 18F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) imaging for staging of previously diagnosed lung cancer constituted the first group, while patients who underwent 18F-FDG PET/CT imaging for evaluation of suspicious pulmonary nodules detected on thorax CT and did not show pathologic FDG accumulation (NAPN=pulmonary nodule with non avid-FDG) were enrolled in the second group. The third group consisted of healthy volunteers.

RESULTS

Twenty-eight patients with lung cancer (median age: 62.5, range: 39-77years), 28 patients with NAPN (median age: 65, range: 33-79 years), and 24 healthy volunteers (median age: 62, range: 44-74 years) were enrolled in the study. The serum anti-p53 Ab level was low in healthy volunteers while it was higher in both lung cancer patients and NAPN patients (p<0.05). When serum anti-p53 Ab level and PET parameters were evaluated, there was no significant correlation between serum anti-p53 Ab level and SUVmax, SUVave, TLG, tumor volume and tumor size of patients with lung cancer (p>0.05). Besides, there was no significant difference between serum anti-p53 Ab level and lesion size of NAPN patients (p>0.05).

CONCLUSION

It was determined that serum anti-p53 Ab levels are not significantly correlated with PET parameters, and that serum anti-p53 Ab levels increase in any benign or malignant lung parenchyma pathology as compared to healthy volunteers. These results indicate that this Ab cannot be used as a predictor of malignancy in a lung lesion.

Consistency of metabolic tumor volume of non-small-cell lung cancer primary tumor measured using 18F-FDG PET/CT at two different tracer uptake times

OBJECTIVES

The objective of this study was to test the hypothesis that the metabolic tumor volume (MTV) of primary non-small-cell lung cancer is not sensitive to differences in F-fluorodeoxyglucose (F-FDG) uptake time, and to compare this consistency of MTV measurements with that of standardized uptake value (SUV) and total lesion glycolysis (TLG).

METHODS

Under Institutional Review Board approval, 134 consecutive patients with histologically proven non-small-cell lung cancer underwent F-FDG PET/computed tomography scanning at about 1 h (early) and 2 h (delayed) after intravenous injection of F-FDG. MTV, SUV, and TLG of the primary tumor were all measured. Student's t-test and Wilcoxon's signed-rank test for paired data were used to compare MTV, SUV, and TLG between the two scans. The intraclass correlation coefficient (ICC) was used to assess agreement in PET parameters between the two scans and between the measurements made by two observers.

RESULTS

MTV was not significantly different (P=0.17) between the two scans. However, SUVmax, SUVmean, SUVpeak, and TLG increased significantly from the early to the delayed scans (P<0.0001 for all). The median percentage change between the two scans in MTV (1.65%) was smaller than in SUVmax (11.76%), SUVmean(10.57%), SUVpeak(13.51%), and TLG (14.34%); the ICC of MTV (0.996) was greater than that of SUVmax (0.933), SUVmean (0.952), SUVpeak (0.928), and TLG (0.982). Interobserver agreement between the two radiologists was excellent for MTV, SUV, and TLG on both scans (ICC: 0.934-0.999).

CONCLUSION

MTV is not sensitive to common clinical variations in F-FDG uptake time, its consistency is greater than that of SUVmax, SUVmean, SUVpeak, and TLG, and it has excellent interobserver agreement.

Application of novel quantitative techniques for fluorodeoxyglucose positron emission tomography/computed tomography in patients with non-small-cell lung cancer

AIM

Flurodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is routinely used in non-small-cell lung cancer. This study aims to assess the prognostic value of quantitative FDG-PET/CT parameters including standard uptake value (SUV), metabolic tumor volume (MTV) and total lesional glycolysis (TLG) in non-small-cell lung cancer.

METHODS

A retrospective review of 92 nonsurgical patients with pathologically confirmed stage I-III non-small-cell lung cancers treated with radical dose radiotherapy (≥50 Gy) was conducted. Metabolically active tumor regions on FDG-PET/CT scans were contoured manually. SUV, MTV and TLG were calculated for primary, nodal and whole-body disease. Univariate and multivariate (adjusting for age, sex, disease stage and primary tumor size in centimeters) Cox regression modeling were performed to assess the association between these parameters and both overall and progression-free survival (PFS).

RESULTS

On univariate analysis, overall survival (OS) was significantly associated with primary MTV (P = 0.03), whole-body MTV (P = 0.02), whole-body maximum SUV (P = 0.05) and whole-body TLG (P = 0.03). PFS was significantly associated with primary MTV (P = 0.01), primary TLG (P = 0.04), whole-body MTV (P < 0.01) and whole-body TLG (P = 0.01). On multivariate analysis, OS was significantly associated with whole-body MTV (P = 0.05). PFS was significantly associated with whole-body MTV (P = 0.02) and whole-body TLG (P = 0.05).

CONCLUSIONS

Whole-body MTV was significantly associated with overall and PFS, and whole-body TLG was significantly associated with PFS on multivariate analysis. These two parameters may be significant prognostic factors independent of other factors such as stage. SUV was not significantly associated with survival on multivariate analysis.

Reproducibility and uptake time dependency of volume-based parameters on FDG-PET for lung cancer

Background

Volume-based parameters, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), on F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) are useful for predicting treatment response in nonsmall cell lung cancer (NSCLC). We aimed to examine intra- and inter-operator reproducibility to measure the MTV and TLG, and to estimate their dependency on the uptake time.

Methods

Fifty NSCLC patients underwent preoperative FDG-PET. After an injection of FDG, the whole body was scanned twice: at the early phase (61.4 ± 2.8 min) and delayed phase (117.7 ± 1.6 min). Two operators independently defined the tumor boundary using three different delineation methods: (1) the absolute SUV threshold method (MTV_p and TLG_p; p = 2.0, 2.5, 3.0, 3.5), (2) the fixed% SUVmax threshold method (MTV_q% and TLG_q%; q = 35, 40, 45), and (3) the adaptive region-growing method (MTV_ARG and TLG_ARG). Parameters were compared between operators and between phases.

Results

Both the intra- and inter-operator reproducibility were high for all parameters using any method (intra-class correlation > 0.99 each). MTV_3.0 and MTV_3.5 resulted in a significant increase from the early to delayed phase (P < 0.05 for both), whereas MTV_2.0 and MTV_2.5 neither increased nor decreased (P = n.s.). All of the MTV_q% values significantly decreased over time (P < 0.01), whereas MTV_ARG and TLG with any delineation method increased significantly (P < 0.05).

Conclusions

High reproducibility of MTV and TLG was obtained by all of the methods used. MTV_2.0 and MTV_2.5 were the least sensitive to uptake time, and may be good alternatives when we compare images acquired with different uptake times, although applying constant uptake time is important for volume measurement.

Measuring total liver function on sulfur colloid SPECT/CT for improved risk stratification and outcome prediction of hepatocellular carcinoma patients

Background

Assessment of liver function is critical in hepatocellular carcinoma (HCC) patient management. We evaluated parameters of [^99mTc] sulfur colloid (SC) SPECT/CT liver uptake for association with clinical measures of liver function and outcome in HCC patients.

Methods

Thirty patients with HCC and variable Child-Turcotte-Pugh scores (CTP A5-C10) underwent [^99mTc]SC SPECT/CT scans for radiotherapy planning. Gross tumor volume (GTV), anatomic liver volume (ALV), and spleen were contoured on CT. SC SPECT image parameters include threshold-based functional liver volumes (FLV) relative to ALV, mean liver-to-spleen uptake ratio (L/S_mean), and total liver function (TLF) ratio derived from the product of FLV and L/S_mean. Optimal SC uptake thresholds were determined by ROC analysis for maximizing CTP classification accuracy. Image metrics were tested for rank correlation to composite scores and clinical liver function parameters. Image parameters of liver function were tested for association to overall survival with Cox proportional hazard regression.

Results

Optimized thresholds on SC SPECT were 58 % of maximum uptake for FLV, 38 % for L/S_mean, and 58 % for TLF. TLF produced the highest CTP classification accuracy (AUC = 0.93) at threshold of 0.35 (sensitivity = 0.88, specificity = 0.86). Higher TLF was associated with lower CTP score: TLF_A = 0.6 (0.4–0.8) versus TLF_B = 0.2 (0.1–0.3), p < 10⁻⁴. TLF was rank correlated to albumin and bilirubin (|R| > 0.63). Only TLF >0.30 was independently associated with overall survival when adjusting for CTP class (HR = 0.12, 95 % CI = 0.02–0.58, p = 0.008).

Conclusions

SC SPECT/CT liver uptake correlated with differential liver function. TLF was associated with improved overall survival and may aid in personalized oncologic management of HCC patients.

Prognostic Value of Volumetric Parameters Measured by Pretreatment 18F FDG PET/CT in Patients With Cutaneous Malignant Melanoma

PURPOSE OF THE REPORT

This study was performed to evaluate the prognostic relevance of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured using F FDG PET/CT in patients with primary cutaneous malignant melanoma (CMM).

MATERIALS AND METHODS

We conducted a retrospective review (July 2005 to November 2010) of 41 patients with a histological diagnosis of CMM who underwent pretreatment F FDG PET/CT. PET parameters (maximum standardized uptake value [SUVmax], MTV, and TLG) of the primary tumor were measured. Clinical variables such as age, sex, clinical stage, location and thickness of the primary lesion, and existence of ulceration were also assessed. Univariate and multivariate analyses for disease-free survival (DFS) and melanoma-specific survival (MSS) were performed using the Kaplan-Meier method and Cox proportional hazards models.

RESULTS

SUVmax and TLG were found to be significantly higher in patients with recurrence than in patients without recurrence (3.98 ± 2.91 vs 1.89 ± 1.35, P = 0.0145; 9.16 ± 8.44 vs 3.72 ± 3.64, P = 0.0249). SUVmax and TLG were also found to be significantly higher in nonsurvivors than in survivors (4.21 ± 3.06 vs 2.00 ± 1.46, P = 0.0260; 10.53 ± 8.83 vs 3.67 ± 3.44, P = 0.0170). The optimal cutoff values for DFS determined using a time-dependent receiver operating characteristic (ROC) curve were 1.8 for SUVmax, 6.07 cm for MTV, and 4.046 for TLG. Sixteen (39%) of the 41 patients experienced recurrence during the follow-up period. In univariate analysis, age (P = 0.0382), male sex (P = 0.0187), ulceration of the primary lesion (P = 0.0001), stage ≥ III (P = 0.0011), SUVmax greater than 1.8 (P = 0.0006), MTV greater than 6.07 cm (P = 0.0136), and TLG greater than 4.046 (P = 0.0010) affected DFS, whereas the other variables (location of the primary lesion and thickness of primary lesion) did not. After adjustment for the effects of the clinical parameters (age, sex, clinical stage, and existence of ulceration), SUVmax, MTV, and TLG were all significant predictors of DFS, and the best predictive factor was SUVmax. Thirteen (32%) of the 41 patients died because of CMM during the follow-up period. The optimal cutoff values for MSS determined using a time-dependent ROC curve were 2.2 for SUVmax, 4.02 cm for MTV, and 4.352 for TLG. In univariate analysis, ulceration of the primary lesion (P = 0.0005), SUVmax greater than 2.2 (P = 0.0001), MTV greater than 4.02 cm (P = 0.0071), and TLG greater than 4.352 (P = 0.0001) affected MSS, whereas the other variables (age, sex, clinical stage, primary lesion site, and thickness of the primary lesion) did not. After adjustment for the effect of the clinical parameter (existence of ulceration), MTV and TLG were significant predictors of MSS, and the best predictive factor of MSS was TLG.

CONCLUSIONS

Pretreatment MTV and TLG may be useful in stratifying the likelihood of recurrence and melanoma-specific death, and TLG was found to be the best predictive marker for predicting melanoma-specific death.

Prediction of Central Nervous System Relapse of Diffuse Large B-Cell Lymphoma Using Pretherapeutic [18F]2-Fluoro-2-Deoxyglucose (FDG) Positron Emission Tomography/Computed Tomography

Central nervous system (CNS) relapse of diffuse large B-cell lymphoma (DLBCL) is a rare complication, but has a poor prognosis with unknown pathophysiology. Recent trials of CNS prophylaxis have shown to be ineffective, despite patient's selection using several known clinical risk factors. In this study, the authors evaluated the value of pretreatment [F]2-Fluoro-2-deoxyglucose positron emission tomography in predicting CNS relapse in DLBCL patients.The authors analyzed 180 pathologically confirmed DLBCL patients, retrospectively. Patients underwent [F]2-Fluoro-2-deoxyglucose positron emission tomography/computed tomography before first line rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone therapy. Clinical characteristics were evaluated and total lesion glycolysis (TLG) with a threshold margin of 50% was calculated.Among age, sex, Ann Arbor stage, International Prognostic Index, revised International Prognostic Index, high serum lactate dehydrogenase level, presence of B symptoms, bulky disease (≥10 cm), extranodal lesion involvement, bone marrow involvement, high metabolic tumor volume ( >450 mL), and high TLG50 (>2000), the high TLG50 was the only significant prognostic factor for predicting CNS relapse in a multivariate analysis (P = 0.04). Kaplan-Meir survival analysis between high TLG50 (>2000) and low TLG50 (≤2000) groups revealed significantly different mean progression free survival (PFS) of 1317.2 ± 134.3 days and 1968.6 ± 18.3 days, respectively (P < 0.001).High TLG50 on [F]2-Fluoro-2-deoxyglucose positron emission tomography/computed tomography is the most significant predictor of CNS relapse in un-treated DLBCL patients.

Does a novel penalized likelihood reconstruction of 18F-FDG PET-CT improve signal-to-background in colorectal liver metastases?

PURPOSE

Iterative reconstruction algorithms are widely used to reconstruct positron emission tomography computerised tomography (PET/CT) data. Lesion detection in the liver by 18F-fluorodeoxyglucose PET/CT (18F-FDG-PET/CT) is hindered by 18F-FDG uptake in background liver parenchyma. The aim of this study was to compare semi-quantitative parameters of histologically-proven colorectal liver metastases detected by 18F-FDG-PET/CT using data based on a Bayesian penalised likelihood (BPL) reconstruction, with data based on a conventional time-of-flight (ToF) ordered subsets expectation maximisation (OSEM) reconstruction.

METHODS

A BPL reconstruction algorithm was used to retrospectively reconstruct sinogram PET data. This data was compared with OSEM reconstructions. A volume of interest was placed within normal background liver parenchyma. Lesions were segmented using automated thresholding. Lesion maximum standardised uptake value (SUVmax), standard deviation of background liver parenchyma SUV, signal-to-background ratio (SBR), and signal-to-noise ratio (SNR) were collated. Data was analysed using paired Student's t-tests and the Pearson correlation.

RESULTS

Forty-two liver metastases from twenty-four patients were included in the analysis. The average lesion SUVmax increased from 8.8 to 11.6 (p<0.001) after application of the BPL algorithm, with no significant difference in background noise. SBR increased from 4.0 to 4.9 (p<0.001) and SNR increased from 10.6 to 13.1 (p<0.001) using BPL. There was a statistically significant negative correlation between lesion size and the percentage increase in lesion SUVmax (p=0.03).

CONCLUSIONS

This BPL reconstruction algorithm improved SNR and SBR for colorectal liver metastases detected by 18F-FDG-PET/CT, increasing the lesion SUVmax without increasing background liver SUV or image noise. This may improve the detection of FDG-avid focal liver lesions and the diagnostic performance of clinical 18F-FDG-PET/CT in this setting, with the largest impact for small foci.

Tumor thrombus: ancillary findings on FDG PET/CT in an oncologic population

PURPOSE

Thrombosis in cancer may manifest itself as venous thromboembolic disease or tumor thrombosis (TT). We present our experience with incidentally detected TT on FDG PET/CT in 21 oncologic patients.

PATIENTS AND METHODS

We retrospectively reviewed all FDG PET/CT examinations during a 5-year period at the Army Hospital Research and Referral in New Delhi, India, and included all oncology cases with FDG-avid thrombosis in the report. The diagnosis of TT was based on FDG-avid solid masses inside the vessels in patients with known malignancy. The SUVmax was calculated.

RESULTS

Twenty-one patients were included; the most common malignancies were renal cell carcinoma (n=6), hepatocellular carcinoma (n=3), and lung cancer (n=3). Indication for the scan was initial staging (n=15) and suspected recurrence (n=6). Several vessels were affected, the most common was the inferior vena cava (n=14), but most other major branches of the venous vasculature was represented, and some patients had thrombi in several vessels. FDG uptake was linear in 7 patients, linear with a dilated vessel in 6 patients, and focal in 7 patients. The mean SUVmax of the primary tumors was 10.3 (range, 2.6-31.2; median, 6.9), and the mean SUVmax of the thrombi was 7.85 (range, 1.7-23.2; median, 6.1). All but 2 patients had additional FDG-avid foci besides the thrombus.

CONCLUSIONS

This study supports results from other smaller studies regarding the usefulness of FDG PET/CT in TT and corroborates the hypothesis that the SUVmax and the patterns of FDG uptake can be helpful for differentiating BT from TT in oncological patients.

Utility of baseline 18FDG-PET/CT functional parameters in defining prognosis of primary mediastinal (thymic) large B-cell lymphoma

18FDG PET/CT is a very important staging tool for patients with PMBCL. Metabolic activity defined by TLG on the baseline PET scan is a powerful predictor of PMBCL outcome.

High metabolic tumor volume and total lesion glycolysis are associated with lateral lymph node metastasis in patients with incidentally detected thyroid carcinoma

OBJECTIVE

The objective of this study was to investigate whether total lesion glycolysis (TLG) and metabolic tumor volume (MTV) measured by ¹⁸F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) could predict the aggressiveness and lymph node metastasis (LNM) in patients with incidentally detected differentiated thyroid carcinoma.

METHODS

A total 358 patients with focal FDG-avid thyroid incidentaloma during cancer evaluation were enrolled. Among 235 patients in whom fine-needle aspiration biopsy was performed, 51 patients underwent total thyroidectomy with LN dissection. We analyzed the relationship between volume-based parameters and clinicopathologic characteristics.

RESULTS

The mean age and tumor size were 57.1 ± 11.3 years and 1.15 ± 0.81 cm, respectively. The prevalence of malignancy was 21.7 % (51/235). When SUV(max) > 5.91, MTV2.5 > 2.05 cm³, and TLG2.5 > 9.09 were used as cutoff points, sensitivity, specificity, and area under curve (AUC) for prediction of lateral LNM were 77.9, 69.1 %, 0.716 (P = 0.047), 77.8, 88.1 %, 0.839 (P < 0.001), 77.8, 85.1 %, and 0.815 (P = 0.002), respectively. However, MTV and TLG had no value in prediction of central LNM, extrathyroidal extension, and multifocality. On comparison ROC curve analysis, the MTV and TLG showed the statistical differences for the prediction of lateral LNM compared with SUV(max) (all P's < 0.05).

CONCLUSIONS

This study has shown for the first time that volume-based PET functional parameters had a significant value for the prediction of lateral LNM in incidentally detected PTC. These results suggest that higher MTV and TLG can be potential new risk factors for preoperative risk stratification. The usefulness of TLG and MTV in preoperative risk stratification in patients with PTC needs to be confirmed in further large studies.

Change in volume parameters induced by neoadjuvant chemotherapy provide accurate prediction of overall survival after resection in patients with oesophageal cancer

OBJECTIVES

To assess the prognostic value of volumetric parameters measured with CT and PET/CT in patients with neoadjuvant chemotherapy (NACT) and resection for oesophageal cancer (EC).

METHODS

Patients with locally advanced EC, who were treated with NACT and resection, were retrospectively analysed. Data from CT volumetry and (18) F-FDG PET/CT (maximum standardized uptake [SUVmax], metabolic tumour volume [MTV], and total lesion glycolysis [TLG]) were recorded before and after NACT. The impact of volumetric parameter changes induced by NACT (MTVRATIO, TLGRATIO, etc.) on overall survival (OS) was assessed using a Cox proportional hazards model.

RESULTS

Eighty-four patients were assessed using CT volumetry; of those, 50 also had PET/CT before and after NACT. Low post-treatment CT volume and thickness, MTV, TLG, and SUVmax were all associated with longer OS (p < 0.05), as were CTthicknessRATIO, MTVRATIO, TLGRATIO, and SUVmaxRATIO (p < 0.05). In the multivariate analysis, only MTVRATIO (Hazard ratio, HR 2.52 [95% Confidence interval, CI 1.33-4.78], p = 0.005), TLGRATIO (HR 3.89 [95%CI 1.46-10.34], p = 0.006), and surgical margin status (p < 0.05), were independent predictors of OS.

CONCLUSIONS

MTVRATIO and TLGRATIO are independent prognostic factors for survival in patients after NACT and resection for EC.

KEY POINTS

• Change in PET parameters shows close correlation to survival in oesophageal cancer. • Association with OS is independent of changes in SUVmax and CT volume. • Metabolic parameters after NACT correlate with pathologic response and nodal status. • Metabolic parameters may be better suited than SUVmax for response assessment.

Prognostic value and clinical correlations of 18-fluorodeoxyglucose metabolism quantifiers in gastric cancer

AIM: To investigate the correlations of pre-treatment positron emission tomography-computer tomography (PET-CT) metabolic quantifiers with clinical data of unstratified gastric cancer (GC) patients.

METHODS: Forty PET-CT scans utilising 18-fluorodeoxyglucose in patients who received no prior treatment were analysed. Analysis involved measurements of maximum and mean standardised uptake volumes (SUV), coefficient of variation (COV), metabolic tumour volumes and total lesion glycolysis of different thresholds above which the tumor volumes were identified. The threshold values were: SUV absolute value of 2.5, 30% of SUVmax, 40% of SUVmax, and liver uptake-based (marked _2.5, ₃₀, ₄₀ and _liv, respectively). Clinical variables such as age, sex, clinical stage, performance index, weight loss, tumor histological type and grade, and CEA and CA19.9 levels were included in survival analysis. Patients received various treatment modalities appropriate to their disease stage and the outcome was defined by time to metastasis (TTM) and overall survival (OS). Clinical and metabolic parameters were evaluated by analysis of variance, receiver operating characteristics, univariate Kaplan-Meier, and multivariate Cox models. P < 0.05 was considered statistically significant.

RESULTS: Significant differences were observed between initially disseminated and non-disseminated patients in mean SUV (6.05 vs 4.13, P = 0.008), TLG_2.5 (802 cm³vs 226 cm³; P = 0.031), and TLG₃₀ (436 cm³vs 247 cm³, P = 0.018). Higher COV was associated with poor tumour differentiation (0.47 for G3 vs 0.28 for G1 and G2; P = 0.03). MTV_2.5 was positively correlated to patient weight loss (< 5%, 5%-10% and > 10%: 40.4 cm³vs 123.6 cm³vs 181.8 cm³, respectively, P = 0.003). In multivariate Cox analysis, TLG₃₀ was prognostic for OS (HR = 1.001, 95%CI: 1.0009-1.0017; P = 0.047) for the whole group of patients. In the same model yet only including patients without initial disease dissemination TLG₃₀ (HR = 1.009, 95%CI: 1.003-1.014; P = 0.004) and MTV_2.5 (HR = 1.02, 95%CI: 1.002-1.036; P = 0.025) were prognostic for OS; for TTM TLG₃₀ was the only significant prognostic variable (HR = 1.006, 95%CI: 1.001-1.012; P = 0.02).

CONCLUSION: PET-CT in GC may represent a valuable diagnostic and prognostic tool that requires further evaluation in highly standardised environments such as randomised clinical trials.

Joint tumor growth prediction and tumor segmentation on therapeutic follow-up PET images

Tumor response to treatment varies among patients. Patient-specific prediction of tumor evolution based on medical images during the treatment can help to build and adapt patient's treatment planning in a non-invasive way. Personalized tumor growth modeling allows patient-specific prediction by estimating model parameters based on individual's images. The model parameters are often estimated by optimizing a cost function constructed based on the tumor delineations. In this paper, we propose a joint framework for tumor growth prediction and tumor segmentation in the context of patient's therapeutic follow ups. Throughout the treatment, a series of sequential positron emission tomography (PET) images are acquired for tumor response monitoring. We propose to take into account the predicted information, which is used in combination with the random walks (RW) algorithm, to develop an automatic tumor segmentation method on PET images. Moreover, we propose an iterative scheme of RW, making the segmentation more performant. Furthermore, the obtained segmentation is applied to the process of model parameter estimation so as to get the model based prediction of tumor evolution. We evaluate our methods on 7 lung tumor patients, totaling 29 PET exams, under radiotherapy by comparing the obtained tumor prediction and tumor segmentation with manual tumor delineation by expert. Our system produces promising results when compared to the state-of-the-art methods.

A new PET/CT volumetric prognostic index for non-small cell lung cancer

OBJECTIVES

Whole-body metabolic tumor volume (MTVWB) has been shown of prognostic value for non-small cell lung cancer (NSCLC) beyond that of TNM stage, age, gender, performance status, and treatment selection. The current TNM staging system does not incorporate tumor volumetric information. We propose a new PET/CT volumetric prognostic (PVP) index that combines the prognostic value of MTVWB and TNM stage.

MATERIALS AND METHODS

Based on 328 consecutive NSCLC patients with a baseline PET/CT scan before treatment, from which MTVWB was measured semi-automatically, we estimated hazard ratios (HRs) for ln(MTVWB) and TNM stage from a Cox proportional hazard regression model that consisted of only ln(MTVWB) and TNM stage as prognostic variables of overall survival. We used the regression coefficients, which gave rise to the HRs, as weights to formulate the PET/CT volumetric prognostic (PVP) index. We also compared the prognostic value of the PVP index against that of TNM stage alone and ln(MTVWB) alone with univariate and multivariate survival analyses and C-statistics.

RESULTS

Univariate analysis C-statistic for the PVP index (C=0.71) was statistically significantly greater than those for TNM stage alone (C=0.67, p<0.01) and for ln(MTVWB) alone (C=0.69, p=0.033). Multivariate analyses showed that the PVP index yielded significantly greater discriminatory power (C=0.74) than similar models based on either TNM stage (C=0.72, p<0.01) or ln(MTVWB) (C=0.73, p<0.01). Lower values of the PVP index were associated with significantly better overall survival (adjusted HR=2.70, 95%CI [2.16, 3.37]).

CONCLUSION

The PVP index provides a practical means for clinicians to combine the prognostic value of MTVWB and TNM stage and offers significantly better prognostic accuracy for overall survival of NSCLC patients than the current TNM staging system or metabolic tumor burden alone.

State-Of-The-Art and Recent Advances in Quantification for Therapeutic Follow-Up in Oncology Using PET

¹⁸F-fluoro-2-deoxyglucose (¹⁸F-FDG) positron emission tomography (PET) is an important tool in oncology. Its use has greatly progressed from initial diagnosis to staging and patient monitoring. The information derived from ¹⁸F-FDG-PET allowed the development of a wide range of PET quantitative analysis techniques ranging from simple semi-quantitative methods like the standardized uptake value (SUV) to “high order metrics” that require a segmentation step and additional image processing. In this review, these methods are discussed, focusing particularly on the available methodologies that can be used in clinical trials as well as their current applications in international consensus for PET interpretation in lymphoma and solid tumors.

Heterogeneity in [18F]fluorodeoxyglucose positron emission tomography/computed tomography of non-small cell lung carcinoma and its relationship to metabolic parameters and pathologic staging

To investigate the relationships between tumor heterogeneity, assessed by texture analysis of [18F]fluorodeoxyglucose-positron emission tomography (FDG-PET) images, metabolic parameters, and pathologic staging in patients with non-small cell lung carcinoma (NSCLC). A retrospective analysis of 38 patients with histologically confirmed NSCLC who underwent staging FDG-PET/computed tomography was performed. Tumor images were segmented using a standardized uptake value (SUV) cutoff of 2.5. Five textural features, related to the heterogeneity of gray-level distribution, were computed (energy, entropy, contrast, homogeneity, and correlation). Additionally, metabolic parameters such as SUVmax, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG), as well as pathologic staging, histologic subtype, and tumor diameter, were obtained. Finally, a correlation analysis was carried out. Of 38 tumors, 63.2% were epidermoid and 36.8% were adenocarcinomas. The mean ± standard deviation values of MTV and TLG were 30.47 ± 25.17 mL and 197.81 ± 251.11 g, respectively. There was a positive relationship of all metabolic parameters (SUVmax, SUVmean, MTV, and TLG) with entropy, correlation, and homogeneity and a negative relationship with energy and contrast. The T component of the pathologic TNM staging (pT) was similarly correlated with these textural parameters. Textural features associated with tumor heterogeneity were shown to be related to global metabolic parameters and pathologic staging.