[Correlation of hematologic parameters with bone marrow and spleen uptake in FDG PET]

Don't overlook spleen glucose metabolism on [18F]-FDG PET/CT for cancer drug discovery and development

Fluorine-18-fluorodeoxyglucose ([18F]-FDG) positron emission tomography/computed tomography (PET/CT) is a useful tool that assesses glucose metabolism in tumor cells to help guide management of cancer patients. However, the clinical relevance of glucose metabolism in healthy tissues, including hematopoietic tissues such as the spleen, has been potentially overlooked. Recent studies suggested that spleen glucose metabolism could improve the management of different cancers. Overall, the current literature includes 1,157 patients, with a wide range of tumor types. The prognostic and/or predictive value of spleen metabolism have been demonstrated in a broad spectrum of therapies including surgery and systemic cancer therapies. Most of these studies showed that high spleen glucose metabolism at baseline is associated with a poor outcome while treatment-induce change in spleen glucose metabolism is a multi-faceted surrogate of cancer-related inflammation, which correlates with immunosuppressive tumor microenvironment as well as with immune activation. In this systematic review, we seek to unravel the prognostic/predictive significance of spleen glucose metabolism on [18F]-FDG PET/CT and discuss how it could potentially guide cancer patient management in the future.

Prognostic significance of bone marrow and spleen 18F-FDG uptake in patients with colorectal cancer

Serum inflammatory markers are used in the prognostication of colorectal cancer (CRC); however, the corresponding role of positron emission tomography (PET)-derived inflammatory markers remains unclear. This study aimed to investigate the prognostic value of ¹⁸F-fluorodeoxyglucose (FDG) uptake in the bone marrow and spleen of patients with CRC and evaluate the relationship between FDG uptake estimates in these organs and serum inflammatory markers. In total, 411 patients who underwent preoperative FDG PET/computed tomography (CT) within 1 month of surgery were enrolled. The mean standardized uptake values of the bone marrow and spleen were normalized to the value of the liver, thereby generating bone marrow-to-liver uptake ratio (BLR) and spleen-to-liver uptake ratio (SLR) estimates. The value of BLR and SLR in predicting overall survival (OS) was assessed using the Cox proportional hazards model. The correlation between BLR or SLR and neutrophil-to-lymphocyte ratio (NLR) was evaluated. The predictive accuracy of BLR alone and in combination with SLR was compared using the integrated area under the receiver operating characteristic curves (iAUC). In the univariate analysis, BLR (> 1.06) and SLR (> 0.93) were significant predictors of OS. In the multivariate analysis, BLR was an independent predictor of OS (hazard ratio = 5.279; p < 0.001). Both BLR and SLR were correlated with NLR (p < 0.001). A combination of BLR and SLR was better than BLR alone at CRC prognostication (iAUC, 0.561 vs. 0.542). FDG uptake estimates in the bone marrow and spleen may be useful imaging-derived biomarkers of systemic inflammation, supporting CRC prognostication.

Bone Marrow and Tumor Radiomics at 18F-FDG PET/CT: Impact on Outcome Prediction in Non-Small Cell Lung Cancer

Background Primary tumor maximum standardized uptake value is a prognostic marker for non-small cell lung cancer. In the setting of malignancy, bone marrow activity from fluorine 18-fluorodeoxyglucose (FDG) PET may be informative for clinical risk stratification. Purpose To determine whether integrating FDG PET radiomic features of the primary tumor, tumor penumbra, and bone marrow identifies lung cancer disease-free survival more accurately than clinical features alone. Materials and Methods Patients were retrospectively analyzed from two distinct cohorts collected between 2008 and 2016. Each tumor, its surrounding penumbra, and bone marrow from the L3-L5 vertebral bodies was contoured on pretreatment FDG PET/CT images. There were 156 bone marrow and 512 tumor and penumbra radiomic features computed from the PET series. Randomized sparse Cox regression by least absolute shrinkage and selection operator identified features that predicted disease-free survival in the training cohort. Cox proportional hazards models were built and locked in the training cohort, then evaluated in an independent cohort for temporal validation. Results There were 227 patients analyzed; 136 for training (mean age, 69 years ± 9 [standard deviation]; 101 men) and 91 for temporal validation (mean age, 72 years ± 10; 91 men). The top clinical model included stage; adding tumor region features alone improved outcome prediction (log likelihood, -158 vs -152; P = .007). Adding bone marrow features continued to improve performance (log likelihood, -158 vs -145; P = .001). The top model integrated stage, two bone marrow texture features, one tumor with penumbra texture feature, and two penumbra texture features (concordance, 0.78; 95% confidence interval: 0.70, 0.85; P < .001). This fully integrated model was a predictor of poor outcome in the independent cohort (concordance, 0.72; 95% confidence interval: 0.64, 0.80; P < .001) and a binary score stratified patients into high and low risk of poor outcome (P < .001). Conclusion A model that includes pretreatment fluorine 18-fluorodeoxyglucose PET texture features from the primary tumor, tumor penumbra, and bone marrow predicts disease-free survival of patients with non-small cell lung cancer more accurately than clinical features alone. © RSNA, 2019 Online supplemental material is available for this article.

Diffuse splenic FDG uptake is predictive of clinical outcomes in patients with rectal cancer

This study aimed to investigate the correlations between diffuse splenic Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) uptake on positron emission tomography/computed tomography (PET/CT) and inflammatory markers and to evaluate the prognostic significance of splenic FDG uptake in rectal cancer patients who underwent curative surgery. We retrospectively analyzed the data from 161 patients who underwent splenic FDG PET/CT staging and subsequent curative surgical resection of rectal cancer between July 2006 and September 2014. The spleen-to-liver uptake ratio (S/L ratio) was calculated by dividing the spleen SUV_mean by liver SUV_mean. We found significant positive correlations between the S/L ratio and neutrophil-to-lymphocyte ratio (P = 0.013) and platelet-to-lymphocyte ratio (P = 0.007). In a Kaplan–Meier analysis, patients with S/L ratio ≤0.815 had a significantly higher recurrence-free survival rate than those with S/L ratio >0.815 (P = 0.028). Also, patients with S/L ratio ≤0.731 had a significantly higher overall survival rate than those with S/L ratio >0.731 (P = 0.036). In multivariate analysis, higher S/L ratio, as well as male, poor differentiation, higher TNM stage, perineural invasion, and larger tumor size, was independently predictive of cancer recurrence (>0.815 vs ≤0.815, hazard ratio [HR]: 2.04, P = 0.046). With regard to OS, S/L ratio was also an independent prognostic factor for death during follow-up (>0.731 vs ≤0.731, HR: 3.81, P = 0.017). Our results show significant correlations between S/L ratio on PET/CT and systemic inflammatory markers. Further, S/L ratio was an independent prognostic factor for predicting recurrence and death in patient with rectal cancer after curative surgery.

Prognostic Value of Fluorine-18 Fluorodeoxyglucose Uptake of Bone Marrow on Positron Emission Tomography/Computed Tomography for Prediction of Disease Progression in Cervical Cancer

OBJECTIVE

This study aimed to evaluate the prognostic value of fluorine-18 fluorodeoxyglucose (FDG) uptake of bone marrow (BM) on positron emission tomography (PET)/computed tomography in patients with uterine cervical cancer.

METHODS

One hundred forty-five patients with cervical cancer who underwent staging FDG PET/computed tomography and subsequent surgical resection or chemoradiotherapy were retrospectively enrolled in the study. Mean BM FDG uptake (BM standardized uptake value [SUV]) and BM-to-liver uptake ratio of FDG uptake (BLR) were measured. Relationships of BM SUV and BLR with hematologic and inflammatory markers were evaluated. Prognostic values of PET parameters for predicting disease progression-free survival and distant recurrence-free survival (DRFS) were assessed with a Cox proportional hazards regression model.

RESULTS

Bone marrow SUV and BLR were significantly correlated with white blood cell count and neutrophil-to-lymphocyte ratio. In the multivariate Cox regression analysis, International Federation of Gynecology and Obstetrics stage (P = 0.048), neutrophil-to-lymphocyte ratio (P = 0.028), platelet-to-lymphocyte ratio (PLR; P = 0.004), maximum SUV of cervical cancer (P = 0.030), and BLR (P = 0.031) were significantly associated with progression-free survival, whereas lymph node metastasis (P = 0.041), PLR (P = 0.002), and BLR (P = 0.025) were significantly associated with DRFS. In a patient subgroup with chemoradiotherapy, BLR (P = 0.044) was still an independent prognostic factor for predicting DRFS in multivariate analysis along with PLR (P = 0.004).

CONCLUSIONS

In patients with cervical cancer, BLR is associated with an increased risk of disease progression and distant recurrence.

Prognostic significance of retention index of bone marrow on dual-phase 18F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with diffuse large B-cell lymphoma

The purpose of this study was to determine the prognostic significance of F-18 fluorodeoxyglucose (FDG) uptake on a dual-phase positron emission tomography/computed tomography (PET/CT), focusing on the increment in maximal standardized uptake value (SUVinc) of tumor and bone marrow (BM) between initial and delayed phase images and retention index (RI) of tumor and BM, in patients with diffuse large B-cell lymphoma (DLBCL).From September 2009 to January 2013, 70 patients (37 males and 33 females, aged 60.6 ± 17.5 years) with DLBCL who had undergone dual-phase FDG PET/CT scans for pretreatment staging were enrolled. The patients subsequently received combination chemotherapy with rituximab. The dual-phase SUV, including SUVinc of tumor (SUVinc-t), RI of tumor (RI-t), SUVinc of BM, and RI of BM were measured. The clinical observation period was from September 2009 to December 2014. Both univariate and multivariate analyses were then used to assess the prognostic significance of SUVinc, RI, international prognostic index (IPI), gender, age, clinical stage, and laboratory tests.The median follow-up time was 35.5 months. The 3-year overall survival (OS) for patients with low/high SUVinc-t (cut-off 2.0) and for patients with low/high RI-t (cut-off 20) were 87.5%/ 62.1% (P = .08) and 83.3%/ 62.7% (P = .14), respectively. The 3-year OS for patients with SUVinc-i < 0.35 and for those with SUVinc-i ≥ 0.35 were 73.2% and 53.3%, respectively (P = .10). The 3-year OS for patients with RI-i < 45 and for those with RI-i ≥ 45 were 72.7% and 37.5%, respectively (P = .02). Subsequently, the Cox multivariate forward proportional hazards model revealed that a higher RI-i (hazard ratio: 4.49; 95% confidence interval: 1.64-12.32; P = .0035) and IPI were independent prognostic factors affecting OS.For patients with DLBCL, an elevated RI-i (≥45) was a predictor for shorter OS, independent of IPI score. It added to the value of pretreatment dual-phase FDG PET/CT scans.

The role of 18F-fluorodeoxyglucose positron emission tomography in the assessment of disease activity of adult-onset Still's disease

BACKGROUND/AIMS

18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) has been suggested as a reliable imaging technique for monitoring of disease activity in patients with adult-onset Still's disease (AOSD). Therefore, we investigated the clinical significance of 18F-FDG PET/CT in Korean AOSD patients.

METHODS

Thirteen AOSD patients were included in the study. The PET/CT images were evaluated with visual and semiquantitative method using standardized uptake values (SUVs).

RESULTS

The presence of increased 18F-FDG uptake was noted in 90% of clinically active AOSD patients. 18F-FDG uptake was located in the lymph node, spleen, and bone marrow. Visual grade and SUV intensity of lymph node was significantly correlated with the systemic score of AOSD. Visual grade of spleen was significantly correlated with the systemic score, erythrocyte sedimentation rate (ESR), and ferritin. Additionally, visual grade and SUV intensity of bone marrow was significantly correlated with the systemic score, ESR, leukocyte, and neutrophil.

CONCLUSIONS

Visual grade and SUV intensity of lymph node, spleen, and bone marrow on 18F-FDG PET/CT scan showed significant correlations with known disease activity markers. The data suggest that 18F-FDG PET/CT scan may be a useful imaging technique for evaluation of disease activity in AOSD patients.

Diffusely Increased Splenic Fluorodeoxyglucose Uptake in Lung Cancer Patients

OBJECTIVES

This study aimed to investigate the association of diffuse splenic F-18 fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT) with tumor maximum standardized uptake value (SUVmax), presence of distant metastases, and hematological and inflammatory parameters.

MATERIAL AND METHODS

Initial FDG PET/CT of 15 lung cancer patients with diffuse splenic FDG uptake were retrospectively analyzed (Group 1). Twelve patients who recently underwent FDG PET/CT for histopathologically proven lung cancer were enrolled as the control group (Group 2). All 27 patients had hematological data, including C-reactive protein (CRP) level, within 5 days before or after PET/CT. To determine SUVmax, the region of interests included the tumor, liver, spleen, and iliac crest. The possible associations between the spleen/liver (S/L) and bone marrow/liver (BM/L) ratios and tumor SUVmax, presence of metastasis, and hematological parameters were evaluated.

RESULTS

The S/L ratio and hemoglobin (Hb) levels were different between the two groups (p=0.000 and 0.05, respectively). The number of patients with anemia were significantly higher in Group 1 than in Group 2 (p=0.02). Although mean Hb levels were different between the two groups, there was no correlation between Hb levels and S/L ratios. There was no significant difference between the two groups with respect to the numbers of patients who had an accompanying infection site. Only CRP levels were correlated with S/L ratios in Group 1 among various other parameters (r=0.559, p=0.05).

CONCLUSION

Our results suggested that inflammation degree correlated with increased splenic FDG uptake in lung cancer patients and was enhanced by anemia. Systemic inflammation and anemia could be important causes of diffusely increased splenic FDG accumulation on PET/CT examinations of lung cancer patients.

The role of 18F-fluorodeoxyglucose uptake of bone marrow on PET/CT in predicting clinical outcomes in non-small cell lung cancer patients treated with chemoradiotherapy

OBJECTIVES

This study aimed to assess the relationship between bone marrow (BM) FDG uptake on PET/CT and serum inflammatory markers and to evaluate the prognostic value of BM FDG uptake for predicting clinical outcomes in non-small cell lung cancer (NSCLC) patients.

METHODS

One hundred and six NSCLC patients who underwent FDG PET/CT for staging work-up and received chemoradiotherapy were enrolled. Mean BM FDG uptake (BM SUV) and BM-to-liver uptake ratio (BLR) were measured, along with volumetric parameters of PET/CT. The relationship of BM SUV and BLR with hematologic parameters and serum inflammatory markers was evaluated. Prognostic values of BM SUV and BLR for predicting progression-free survival (PFS) and overall survival (OS) were assessed.

RESULTS

BM SUV and BLR were significantly correlated with white blood cell count and C-reactive protein level. On univariate analysis, BLR was a significant prognostic factor for both PFS and OS. On multivariate analysis, TNM stage and BLR were independent prognostic factors for PFS, and only TNM stage was an independent prognostic factor for OS.

CONCLUSIONS

In NSCLC patients, FDG uptake of BM reflects the systemic inflammatory response and can be used as a biomarker to identify patients with poor prognosis.

KEY POINTS

• Bone marrow FDG uptake is correlated with serum inflammatory markers. • Bone marrow FDG uptake is an independent prognostic factor for progression-free survival. • Bone marrow FDG uptake can provide information on predicting lung cancer progression.

Malaria masquerading as relapse of Hodgkin's lymphoma on contrast enhanced (18)F-fluorodeoxyglucose positron emission tomography/computed tomography: A diagnostic dilemma

(18)Flurodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) is nowadays routinely used in management of lymphoma patients. We here present a case of Hodgkin's lymphoma which showed (18)F-FDG avid splenomegaly on PET/CT done for clinically suspected relapse. Further evaluation by peripheral smear examination revealed malaria. The patient was then started on anti-malarial medications and follow-up PET/CT revealed resolution of hypermetabolic splenomegaly. This report highlights that in endemic regions malaria can cause (18)F-FDG avid splenomegaly and might mimic relapse of lymphoma.

Current role of FDG PET/CT in lymphoma

The management approach in Hodgkin's (HL) and high-grade non-Hodgkin's lymphomas (NHL) has shifted towards reducing the toxicity and long-term adverse effects associated with treatment while maintaining favorable outcomes in low-risk patients. The success of an individualized treatment strategy depends largely on accurate diagnostic tests both at staging and during therapy. In this regard, positron emission tomography (PET) using fluorodeoxyglucose (FDG) with computed tomography (CT) has proved effective as a metabolic imaging tool with compelling evidence supporting its superiority over conventional modalities, particularly in staging and early evaluation of response. Eventually, this modality was integrated into the routine staging and restaging algorithm of lymphomas. This review will summarize the data on the proven and potential utility of PET/CT imaging for staging, response assessment, and restaging, describing current limitations of this imaging modality.

State-of-the-Art Research on "Lymphomas: Role of Molecular Imaging for Staging, Prognostic Evaluation, and Treatment Response"

Lymphomas are heterogeneous but potentially curable group of neoplasms. Treatment of lymphomas has rapidly evolved overtime with significant improvement in the cure rate and reductions in treatment-related toxicities. Despite excellent results, treatment programs are continued to be developed to achieve better curative and safety profiles. In these patients individualized therapy schemes can be devised based on a well-defined risk categorization. The therapy efficacy can be increased early during therapy in non-responding patients with escalated therapy protocols or with the addition of radiation therapy, particularly, in advanced-stage or unfavorable risk patients. The increasing availability of positron emission tomography using 18F-fluorodeoxyglucose, particularly fused with computed tomography (FDG-PET/CT) has lead to the integration of this modality into the routine staging and restaging for lymphoma with convincing evidence that it is a more accurate imaging modality compared with conventional imaging techniques. FDG-PET/CT is also is a promising surrogate for tumor chemosensitivity early during therapy. This review will summarize published data on the utility of FDG-PET/CT imaging in the staging, restaging, and predicting therapy response in patients with lymphoma.

¹⁸F-FDG uptake by spleen helps rapidly predict the dose level after total body irradiation in a Tibetan minipig model

OBJECTIVES

To investigate whether (18)F- FDG uptake can be applied in dosimetry to facilitate the rapid and accurate evaluation of individual radiation doses after a nuclear accident.

METHODS

Forty-eight Tibetan minipigs were randomised into a control group (n = 3) and treatment groups (n = 45). (18)F-FDG combined positron-emission tomography and computed tomography (PET/CT) were carried out before total body irradiation (TBI) and at 6, 24 and 72 h after receiving TBI doses ranging from 1 to 11 Gy. Spleen tissues and blood samples were also collected for histological examination, apoptosis and blood analysis.

RESULTS

Mean standardised uptake values (SUVs) of the spleen showed significant differences between the experimental and the control groups. Spleen SUV at 6 h post-irradiation showed significant correlation with radiation dose; Spearman's correlation coefficient was 0.97 (P < 0.01). Histological observations showed that damage to the splenic lymphocyte became more severe with an increase in the radiation dose. Moreover, apoptosis was one of the major routes of splenic lymphocyte death, which was also confirmed by flow cytometry analysis.

CONCLUSIONS

In the Tibetan minipig model, radiation doses have a close relationship with the (18)F-FDG uptake of the spleen. This finding suggests that (18)F-FDG PET/CT may be useful for the rapid detection of individual radiation doses.