Correlation of FDG PET/CT Findings with Long-Term Growth and Clinical Course of Abdominal Aortic Aneurysm

Purpose

Herein, we report characteristics of ¹⁸F–fluorodeoxyglucose (FDG) uptake in abdominal aortic aneurysms (AAAs) during a long-term follow-up. In addition, we investigated the association between FDG uptake and the physician decision to perform an intervention.

Methods

We performed a retrospective review of 42 patients with AAAs who underwent FDG positron emission tomography (PET)/computed tomography (CT). The size of the AAA was measured in serial CT or PET/CT images. The long-term growth rate of AAAs was calculated by linear regression of the size change. Maximal SUV of the AAA (SUV_AAA) and mean SUV of the blood pool (SUV_Blood) were measured in PET/CT fusion images. To assess the FDG uptake of AAAs, the target-to-background ratio (TBR) was defined as the ratio of SUV_AAA to SUV_Blood. We compared FDG uptake of AAAs with the long-term growth rate of AAAs and clinical data.

Results

TBR was not significantly different between patients with and without significant growth (1.55 ± 0.20 vs. 1.57 ± 0.14; P = 0.5599). However, in patients with significant growth, TBR exhibited a significant positive correlation with the growth rate (r ²  = 0.2601, P = 0.0306). TBR also exhibited a significant difference between patients with and without intervention (P = 0.0228).

Conclusion

FDG uptake of AAA is associated with long-term growth of AAAs in a specified group that exhibits growth. FDG PET/CT may only be effective in predicting the long-term growth of AAAs in specific subgroups of patients. It is also suggested that FDG PET is potentially related to the clinical conditions of AAA patients who need surgical or interventional treatment.

     

Evaluating the Predictive Ability of Initial Staging F-18 FDG PET/CT for the Prognosis of Non-Hodgkin Malignant Lymphoma Patients Who Underwent Stem Cell Transplantation

Objectives

This study aimed to determine the value of clinical prognostic factors and semiquantitative metabolic parameters from initial staging fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) in non-Hodgkin lymphoma (NHL) patients treated with stem cell transplantation (SCT).

Methods

A total of 39 malignant lymphoma patients who underwent initial staging F-18 FDG PET/CT were enrolled in this study. SUVmax, MTV_wb, and TLG_wb were measured during the initial staging PET/CT. Receiver operating characteristic curve (ROC) analysis was adopted to dichotomize continuous variables. Log-rank test and Cox proportional hazard regression analysis were used to evaluate disease-free survival (DFS) rate.

Results

Among the 39 patients with malignant lymphoma, 17 (43.6%) had a relapse. For several clinical factors such as age, ECOG performance score, AMC/ALC score, stages, and revised International Prognostic Index score, differences between the two dichotomized groups were statistically insignificant. In univariate analysis, DFS estimates were 71.0 ± 7.8 months and 18.0 ± 5.9 months in high-SUVmax and low-SUVmax group, respectively (P < 0.01). For MTV_wb, DFS estimates were 46.6 ± 12.4 months and 69.1 ± 8.5 months in high-MTV_wb and low-MTV_wb group, respectively (P = 0.12). For TLG_wb, DFS estimates were 65.3 ± 7.5 months and 13.7 ± 8.6 months in high-TLG_wb and low-TLG_wb group, respectively (P = 0.02). In Cox proportional hazard regression analysis, only MTV_wb showed statistical significance (HR 3.01, 95% CI 1.04–8.74, P = 0.04).

Conclusion

In NHL patients treated with SCT, the MTV_wb of initial staging F-18 FDG PET/CT was an independent prognostic factor.

     

Metformin discontinuation less than 72 h is suboptimal for F-18 FDG PET/CT interpretation of the bowel

Objective

Metformin-induced [F-18] fluorodeoxyglucose (FDG) bowel uptake can hinder positron emission tomography/computed tomography (PET/CT) evaluation of the bowel. This study aimed to investigate the segmental bowel uptake of FDG according to metformin discontinuation times up to 72 h.

Methods

We retrospectively divided 240 diabetic patients into four groups: metformin discontinuation <24 h (group A; n = 86), 24–48 h (group B; n = 40), 48–72 h (group C; n = 12), and no metformin (control group; n = 102). Segmental FDG bowel uptakes were measured visually (four-point scale) and semi-quantitatively (maximum standardized uptake value).

Results

Compared with the control group, FDG uptake increased significantly from the ileum to the rectosigmoid colon in group A, from the transverse to the rectosigmoid colon in group B, and from the descending colon to the rectosigmoid colon in group C in both visual and semi-quantitative analyses.

Conclusions

Metformin discontinuation for <72 h is likely suboptimal for PET/CT image interpretation, especially with respect to the distal segments of the colon.

     

Malignancy rate of biopsied suspicious bone lesions identified on FDG PET/CT

Purpose

To determine the malignancy rate of bone lesions identified on FDG PET/CT in patients who have undergone CT-guided biopsy because of the suspicion of malignancy.

Methods

This single-centre retrospective study spanned eight consecutive years and included all patients who underwent both FDG PET/CT and CT-guided bone biopsy because of the suspicion of malignancy. The positive predictive value (PPV) for malignancy was calculated, and different patient and imaging characteristics were compared between malignant and benign bone lesions.

Results

Of 102 included patients with bone lesions that all showed FDG uptake exceeding mediastinal uptake, bone biopsy showed a malignant lesion in 91 patients, yielding a PPV for malignancy of 89.2 % (95 % CI 81.7 – 93.9 %). In the 94 patients with bone lesions that showed FDG uptake exceeding liver uptake, bone biopsy showed a malignant lesion in 83 patients, yielding a PPV for malignancy of 88.3 % (95 % CI 80.1 – 93.5 %). Higher age, bone marrow replacement of the lesion seen on CT, expansion of the lesion seen on CT, and presence of multifocal lesions on FDG PET/CT were significantly more frequent in patients with malignant lesions than in those with benign bone lesions (P?=?0.044, P?=?0.009, P?=?0.015, and P?=?0.019, respectively). Furthermore, there was a trend towards a higher incidence of cortical destruction (P?=?0.056) and surrounding soft tissue mass (P?=?0.063) in patients with malignant bone lesions.

Conclusion

The PPV for malignancy of suspicious bone lesions identified on FDG PET/CT is not sufficiently high to justify changes in patient management without histopathological confirmation. Nevertheless, ancillary patient and imaging characteristics may increase the likelihood of a malignant bone lesion.

     

Diagnostic accuracy of FDG PET/CT for clinical evaluation at the end of treatment of HL and NHL: a comparison of the Deauville Criteria (DC) and the International Harmonization Project Criteria (IHPC)

Purpose

To evaluate the accuracy and prognostic value of FDG PET/CT for response assessment after treatment in patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) when using the Deauville Criteria (DC) and the International Harmonization Project Criteria (IHPC).

Methods

This retrospective study included 101 patients (35 HL, 66 NHL) who underwent early restaging FDG PET/CT after treatment. Scans were evaluated using the IHPC and DC. Two thresholds of positivity for the DC were used: a score of at least 3 (DC3, i.e. scores 3?–?5) and a score of at least 4 (DC4, i.e. a score of 4 or 5). Accuracy was assessed using conventional diagnostic procedures, multidisciplinary team case notes, further PET/CT scans and/or follow-up. Progression-free survival and overall survival were computed using the Kaplan-Meier method. The Cox proportional hazards model was used to identify predictors of outcome.

Results

Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FDG PET/CT for early restaging were, respectively, 92 %, 87 %, 74 %, 92 % and 86 % using DC4, 97 %, 76 %, 64 %, 98 % and 84 % using DC3, and 97 %, 67 %, 57 %, 98 % and 76 % using the IHPC. FDG PET/CT positivity was associated with a worse cumulative survival rate over a 2-year period when using DC4 in comparison with the IHPC (20 % vs. 49 %; p?<?0.05) and DC3 (47 %; p?<?0.05). Cox regression analysis showed different risks of progression in patients positive on FDG PET/CT using the IHPC, DC3 and DC4 (hazard ratios 1.57, 0.7 and 3.2, respectively).

Conclusion

FDG PET/CT using DC4 showed higher diagnostic accuracy for HL and NHL than FDG PET/CT using either the IHPC or DC3, indicating its value in predicting clinical outcome after treatment.

     

Recurrent renal cell carcinoma: clinical and prognostic value of FDG PET/CT

Purpose

The purpose of our study was 1) to evaluate the diagnostic performance of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT), 2) to assess the impact of FDG PET/CT on treatment decision-making, and 3) to estimate the prognostic value of FDG PET/CT in the restaging process among patients with renal cell carcinoma (RCC).

Methods

From the FDG PET/CT databases of San Raffaele Hospital in Milan, Italy, and the Veneto Institute of Oncology in Padua, Italy, we selected 104 patients with a certain diagnosis of RCC after surgery, and for whom at least 24 months of post-surgical FDG PET/CT, clinical, and instrumental follow-up data was available. The sensitivity and specificity of FDG PET/CT were assessed by histology and/or other imaging as standard of reference. Progression-free survival (PFS) and overall survival (OS) were computed using the Kaplan–Meier method. Univariate and multivariate Cox proportional hazards models were used to identify predictors of outcome.

Results

FDG PET/CT resulted in a positive diagnosis in 58 patients and a negative diagnosis in 46 patients. Sensitivity and specificity were 74 % and 80 %, respectively. FDG PET/CT findings influenced therapeutic management in 45/104 cases (43 %). After a median follow-up period of 37 months (± standard deviation 12.9), 51 (49 %) patients had recurrence of disease, and 26 (25 %) had died. In analysis of OS, positive versus negative FDG PET/CT was associated with worse cumulative survival rates over a 5-year period (19 % vs. 69 %, respectively; p <0.05). Similarly, a positive FDG PET/CT correlated with a lower 3-year PFS rate. In addition, univariate and multivariate analysis revealed that a positive scan, alone or in combination with disease stage III–IV or nuclear grading 3–4, was associated with high risk of progression (multivariate analysis = hazard ratios [HRs] of 4.01, 3.7, and 2.8, respectively; all p?<?0.05).

Conclusions

FDG PET/CT is a valuable tool both in treatment decision-making and for predicting survival and progression in patients affected by RCC.

     

Dual-time-point FDG PET/CT imaging in prosthetic heart valve endocarditis

Purpose

FDG PET/CT has been of increasing interest in the diagnostic workup of prosthetic heart valve endocarditis (PVE). Some reports advocate later imaging time points to improve the diagnostic accuracy for PVE. In this study, we compared standard and late FDG PET/CT images in patients with a clinical suspicion of PVE.

Materials and Methods

Fourteen scans in 13 patients referred for FDG PET/CT for suspicion of PVE performed at standard (60 min post injection) and late (150 min post injection) time points were scored based on visual interpretation and semi-quantitatively with SUVmax and target-to-background ratio (TBR, defined as [SUVmax valve/SUVmean blood pool]). Final diagnosis was based on surgical findings in all cases of infection (n = 6) and unremarkable follow-up in all others (n = 8).

Results

Late images were more prone to false positive interpretation for both visual and semi-quantitative analyses. Visual analysis of the standard images yielded 1 false negative and 1 false positive result. On the late images, no scans were false negative but 5 scans were false positive.

Conclusion

Late FDG PET/CT imaging for PVE seems prone to false positive results. Therefore, late imaging should be interpreted with caution.

     

High FDG uptake on PET is associated with negative cell-to-cell adhesion molecule E-cadherin expression in lung adenocarcinoma

Objectives

E-cadherin is a main cell-to-cell adhesion molecule. A negative expression of E-cadherin correlates with distant metastasis in lung cancer. Recently, it was reported that there is an association between FDG uptake on PET and epithelial-mesenchymal transition (EMT) in non-small cell lung cancer. Downregulation of E-cadherin is one of the best markers of EMT. The purpose of this study was to compare E-cadherin expression with FDG uptake on PET, cell differentiation, aggressiveness and post-operative recurrence in patients with lung adenocarcinoma, and to investigate whether FDG uptake on PET is associated with E-cadherin expression.

Methods

We retrospectively reviewed 40 lung adenocarcinoma patients who underwent thoracotomy and FDG PET before thoracotomy. These patients were evaluated FDG PET metrics such as standardized uptake value (SUV), the immunohistochemical expression of E-cadherin in surgical specimens, clinicopathological features, including tumor size, pathologic stage, cell differentiation, aggressiveness and post-operative recurrence.

Results

High FDG uptake correlated with negative E-cadherin expression (P = 0.043). SUV_max was higher in a negative E-cadherin expression lung adenocarcinoma than in a positive E-cadherin expression lung adenocarcinoma (P = 0.033). Patients with moderately poorly differentiated adenocarcinoma had frequent negative E-cadherin expression or high FDG uptake (P = 0.004, P = 0.0001, respectively). Patients with aggressive adenocarcinoma had frequent negative E-cadherin expression or high FDG uptake (P = 0.004, P = 0.001, respectively). Kaplan–Meier analysis revealed that negative E-cadherin expression or high FDG uptake were strongly correlated with shortened disease-free survival (P = 0.0153, P = 0.0001, respectively).

Conclusion

High FDG uptake on PET was associated with negative E-cadherin expression in patients with lung adenocarcinoma. Both high FDG uptake and negative E-cadherin expression were strongly correlated with poor differentiation, aggressiveness, and post-operative recurrence. These findings may cause the association between high FDG uptake and negative E-cadherin expression.

     

[18F]FDG PET/CT-based response assessment of stage IV non-small cell lung cancer treated with paclitaxel-carboplatin-bevacizumab with or without nitroglycerin patches

Purpose

Nitroglycerin (NTG) is a vasodilating drug, which increases tumor blood flow and consequently decreases hypoxia. Therefore, changes in [18F] fluorodeoxyglucose positron emission tomography ([18F]FDG PET) uptake pattern may occur. In this analysis, we investigated the feasibility of [18F]FDG PET for response assessment to paclitaxel-carboplatin-bevacizumab (PCB) treatment with and without NTG patches. And we compared the [18F]FDG PET response assessment to RECIST response assessment and survival.

Methods

A total of 223 stage IV non-small cell lung cancer (NSCLC) patients were included in a phase II study (NCT01171170) randomizing between PCB treatment with or without NTG patches. For 60 participating patients, a baseline and a second [18F]FDG PET/computed tomography (CT) scan, performed between day 22 and 24 after the start of treatment, were available. Tumor response was defined as a 30 % decrease in CT and PET parameters, and was compared to RECIST response at week 6. The predictive value of these assessments for progression free survival (PFS) and overall survival (OS) was assessed with and without NTG.

Results

A 30 % decrease in SUVpeak assessment identified more patients as responders compared to a 30 % decrease in CT diameter assessment (73 % vs. 18 %), however, this was not correlated to OS (SUVpeak30 p?=?0.833; CTdiameter30 p?=?0.557). Changes in PET parameters between the baseline and the second scan were not significantly different for the NTG group compared to the control group (p value range 0.159–0.634). The CT-based (part of the [18F]FDG PET/CT) parameters showed a significant difference between the baseline and the second scan for the NTG group compared to the control group (CT diameter decrease of 7?±?23 % vs. 19?±?14 %, p?=?0.016, respectively).

Conclusions

The decrease in tumoral FDG uptake in advanced NSCLC patients treated with chemotherapy with and without NTG did not differ between both treatment arms. Early PET-based response assessment showed more tumor responders than CT-based response assessment (part of the [18F]FDG PET/CT); this was not correlated to survival. This might be due to timing of the [18F]FDG PET shortly after the bevacizumab infusion.

     

Prognostic Value of Pre- and Post-Treatment FDG PET/CT Parameters in Small Cell Lung Cancer Patients

Purpose

To evaluate the prognostic value of PET parameters obtained from pre- and post-treatment FDG PET/CT examinations in patients with SCLC.

Methods

Fifty-nine patients with initially diagnosed SCLC from 2009 to 2014 were included and had chemotherapy and/or concurrent chemoradiotherapy. FDG PET/CT examinations were performed before (PET1) and after (PET2) treatment to evaluate treatment response. A region of interest was placed over the primary lesion and metastatic lymph nodes within the thoracic cavity. PET parameters including change from PET1 to PET2 (Δ in %) were acquired: SUVmax, SUVpeak, MTV2.5, TLG, ΔSUVmax, ΔSUVpeak, ΔMTV and ΔTLG. Patient characteristics including staging, age, sex, LDH and response evaluation by RECIST were surveyed. Statistical analysis was done using Kaplan-Meier method and Cox regression analysis with respect to OS and PFS.

Results

The median follow-up was 9.6 months (2.5–80.5 months). 27 patients were LD and 32 were ED. Forty-six patients (78.0%) had died, and median OS was 8.6 months; 51 patients (86%) showed disease progression, and median PFS was 2.5 months. On univariate analysis, patients with ED, high interval change (ΔSUVmax and ΔSUVpeak) and low PET2 parameters showed longer OS and PFS. Multivariate analyses demonstrated that ΔSUVpeak (HR 2.6, P = 0.002) was an independent prognostic factors for OS, and MTV2.5 of PET2 (HR 2.8, P = 0.001), disease stage (HR 2.7, P = 0.003) and RECIST (HR 2.0, P = 0.023) were independent prognostic factors for PFS.

Conclusions

Metabolic and volumetric PET parameters obtained from pre- and post-treatment FDG PET/CT examinations in patients with SCLC have significant prognostic information.

     

<Superscript>18</Superscript>F-FDG and <Superscript>18</Superscript>F-FLT PET/CT imaging in the characterization of mediastinal lymph nodes

Purpose

There is currently no single modality for accurate characterization of enlarged mediastinal lymph nodes into benign or malignant. Recently ¹⁸F-fluorothymidine (FLT) has been used as a proliferation marker. In this prospective study, we examined the role of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and ¹⁸F-FLT PET/CT in categorizing mediastinal lymph nodes as benign or malignant.

Materials and methods

A total of 70 consecutive patients with mediastinal lymphadenopathy detected on computed tomography (CT) or chest radiograph underwent whole body ¹⁸F-FLT PET/CT and ¹⁸F-FDG PET/CT (within 1 week of each other). Lymph nodal tracer uptake was determined by calculation of standardized uptake value (SUV) with both the tracers. Results of PET/CT were compared with histopathology of the lymph nodes.

Results

Histopathology results showed thirty-seven patients with sarcoidosis, seven patients with tuberculosis, nine patients with non-small cell lung cancer, five patients with Hodgkin’s lymphoma and twelve patients with non-Hodgkin’s lymphoma. The mean FDG SUV_max of sarcoidosis, tuberculosis, Hodgkin’s and non-Hodgkin’s lymphoma was 12.7, 13.4, 8.2, and 8.8, respectively, and the mean FLT SUV_max was 6.0, 5.4, 4.4, and 3.8, respectively. It was not possible to characterize mediastinal lymphadenopathy as benign or malignant solely based on FDG SUV_max values (p > 0.05) or FLT SUV_max values (p > 0.05). There was no significant difference in FDG uptake (p > 0.9) or FLT uptake (p > 0.9) between sarcoidosis and tuberculosis. In lung cancer patients, the FDG SUV_max and FLT SUV_max of those lymph nodes with tumor infiltration on biopsy was 6.7 and 3.9, respectively, and those without nodal infiltration was 6.4 and 3.7, respectively, and both the tracers were not able to characterize the nodal status as malignant or benign (p > 0.05).

Conclusion

Though ¹⁸F-FLT PET/CT and ¹⁸F-FDG PET/CT reflect different aspects of biology, i.e., proliferation and metabolism, respectively, neither tracer could provide satisfactory categorization of benign and malignant lymph nodes. The results of this study clearly suggest that differentiation of mediastinal nodes into benign and malignant solely based on SUV_max values cannot be relied upon, especially in settings where tuberculosis and sarcoidosis are common.

     

Three days of high-dose glucocorticoid treatment attenuates large-vessel 18F-FDG uptake in large-vessel giant cell arteritis but with a limited impact on diagnostic accuracy

Purpose

To evaluate the in-treatment diagnostic accuracy of FDG PET/CT in large-vessel giant cell arteritis (LV-GCA) by serial scans before and after a short course of high-dose glucocorticoid treatment.

Methods

Twenty-four glucocorticoid-naïve patients with new-onset PET/CT verified LV-GCA (pre-treatment baseline PET) were prospectively included. Excluded were patients with a previous history of GCA or polymyalgia rheumatica, LV-GCA-mimicking conditions and patients on immunosuppressive therapy. All patients were treated with 60 mg of oral prednisolone daily and assigned for in-treatment FDG PET/CT after either 3 (PET3) or 10 days (PET10). Two experienced nuclear medicine physicians, blinded to patients’ clinical data, reviewed the FDG PET/CT images. A visual semi-quantitative approach was used. Segmental and homogenous FDG uptake in the wall of the aorta and/or supra-aortic branches with higher uptake intensity than liver was considered consistent with vasculitis. Inter-reader reliability was evaluated.

Results

Although glucocorticoid treatment attenuated FDG uptake in large vessels, LV-GCA was accurately diagnosed in 10/10 patients after 3 days of treatment, but only in 5/14 patients after 10 days of treatment (p?<?0.001). Interrater reliability was substantial (agreement 87%, Cohen’s weighted kappa 0.70). No correlation between CRP and FDG uptake was found.

Conclusions

Within 3 days of high-dose glucocorticoid treatment, FDG PET/CT can diagnose LV-GCA with high sensitivity. This window of opportunity ensures that prompt glucocorticoid treatment can be initiated to avoid debilitating GCA complications with a limited effect on diagnostic accuracy. After 10 days of treatment, FDG PET/CT sensitivity decreases significantly.

     

Post-treatment positron emission tomography-computed tomography is highly predictive of outcome in Plasmablastic lymphoma

Purpose

Plasmablastic lymphoma (PBL) is a rare variant of diffuse large B cell lymphomas (DLBCL) clinically characterized by a poorer prognostic. Few clinical and imaging data are available and derived from pooled case reports and small series. The aim of the study was to evaluate the FDG avidity at baseline and the utility of 18-Fluorodeoxyglucose (FDG) positron-emission-tomography/computed-tomography (PET/CT) for staging and response assessment.

Methods

Patients with newly diagnosed PBL seen at Lymphoma Study Association centers during the period 2005–2015 were included if they underwent a PET/CT at staging and at the end of treatment (eotPET) and had received an anthracycline-based first line therapy. EotPET scans were analyzed using the 5-point-scale visual analysis in accordance with Lugano criteria. Patients were classified in complete metabolic response (CMR) or no-CMR including partial metabolic response (PMR), stable disease (SD) and progression disease (PD). EotPET results were assessed for the ability to predict event free survival (EFS) and overall survival (OS).

Results

Thirty-five PBL patients fulfilled the inclusion criteria. The median follow-up was 34 months (2.8–120 months). FDG avidity was found in all patients at diagnosis. Most patients (80%) achieved CMR, and 20% were no-CMR including 9% PMR, 6% SD, and 6% PD. A CMR after first line chemotherapy predicted higher EFS (p?<?0.0001) and OS (p?=?0.0006).

Conclusions

This study confirmed the FDG avidity of PBL subtype and the usefulness of PET/CT scanning in restaging an aggressive lymphoma at the completion of chemotherapy. EotPET can predict outcomes following treatment in patients with PBL.

     

Comparison of FDG-PET/CT and contrast-enhanced CT for monitoring therapy response in patients with metastatic breast cancer

Purpose

The aim of this study was to compare fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and contrast-enhanced computed tomography (CE-CT) for the prediction of progression-free survival (PFS) and disease-specific survival (DSS) in patients with stage IV breast cancer undergoing systemic therapy.

Methods

Sixty-five patients with metastatic breast cancer treated with first- or second-line systemic therapy in prospective clinical trials were included. Response to treatment was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 for CE-CT and by PET Response Criteria in Solid Tumors (PERCIST), respectively.

Results

All responders by RECIST (n = 22) were also responders by PERCIST, but 40% (17/43) of non-responders by RECIST were responders by PERCIST. Responses according to RECIST and PERCIST both correlated with PFS, but PERCIST showed a significantly higher predictive accuracy (concordance index for PFS: 0.70 vs. 0.60). One-year PFS for responders vs. non-responders by RECIST was 59% vs. 27%, compared to 63% vs. 0% by PERCIST. Four-year DSS of responders and non-responders by RECIST was 50% and 38%, respectively (p = 0.2, concordance index: 0.55) as compared to 58% vs. 18% for PERCIST (p < 0.001, concordance index: 0.65). Response on PET/CT was also a significantly better predictor for DSS than disease control on CE-CT.

Conclusions

In patients with metastatic breast cancer, tumor response on PET/CT appears to be a superior predictor of PFS and DSS than response on CE-CT. Monitoring tumor response by PET/CT may increase the power of clinical trials using tumor response as an endpoint, and may improve patient management in clinical routine.

     

Diagnostic and prognostic value of baseline FDG PET/CT skeletal textural features in diffuse large B cell lymphoma

Purpose

Our purpose was to evaluate the diagnostic and prognostic value of skeletal textural features (TFs) on baseline FDG PET in diffuse large B cell lymphoma (DLBCL) patients.

Methods

Eighty-two patients with DLBCL who underwent a bone marrow biopsy (BMB) and a PET scan between December 2008 and December 2015 were included. Two readers blinded to the BMB results visually assessed PET images for bone marrow involvement (BMI) in consensus, and a third observer drew a volume of interest (VOI) encompassing the axial skeleton and the pelvis, which was used to assess skeletal TFs. ROC analysis was used to determine the best TF able to diagnose BMI among four first-order, six second-order and 11 third-order metrics, which was then compared for diagnosis and prognosis in disease-free patients (BMB?/PET-) versus patients considered to have BMI (BMB+/PET-, BMB?/PET+, and BMB+/PET+).

Results

Twenty-two out of 82 patients (26.8%) had BMI: 13 BMB?/PET+, eight BMB+/PET+ and one BMB+/PET-. Among the nine BMB+ patients, one had discordant BMI identified by both visual and TF PET assessment. ROC analysis showed that SkewnessH, a first-order metric, was the best parameter for identifying BMI with sensitivity and specificity of 81.8% and 81.7%, respectively. SkewnessH demonstrated better discriminative power over BMB and PET visual analysis for patient stratification: hazard ratios (HR), 3.78 (P?=?0.02) versus 2.81 (P?=?0.06) for overall survival (OS) and HR, 3.17 (P?=?0.03) versus 1.26 (P?=?0.70) for progression-free survival (PFS). In multivariate analysis accounting for IPI score, bulky status, haemoglobin and SkewnessH, the only independent predictor of OS was the IPI score, while the only independent predictor of PFS was SkewnessH.

Conclusion

The better discriminative power of skeletal heterogeneity for risk stratification compared to BMB and PET visual analysis in the overall population, and more specifically in BMB?/PET- patients, suggests that it can be useful to identify diagnostically overlooked BMI.

     

Recurrent bladder carcinoma: clinical and prognostic role of 18 F-FDG PET/CT

Aim

A small number of studies evaluated the detection rate of lesions from bladder carcinoma (BC) of 18 F-FDG PET/CT in the restaging process. However, the prognostic role of FDG PET/CT still remains unclear. The aim of the present study was to evaluate the accuracy, the effect upon treatment decision, and the prognostic value of FDG PET/CT in patients with suspected recurrent BC.

Materials and Methods

Forty-one patients affected by BC underwent FDG PET/CT for restaging purpose. The diagnostic accuracy of visually interpreted FDG PET/CT was assessed compared to histology (n?=?8), other diagnostic imaging modalities (contrast-enhanced CT in 38/41 patients and MRI in 15/41) and clinical follow-up (n?=?41). Semiquantitative PET values (SUVmax, SUVmean, SUL, MTV, TLG) were calculated using a graph-based method. Progression-free survival (PFS) and overall survival (OS) were assessed by using Kaplan-Meier curves. The risk of progression (hazard ratio, HR) was computed by Cox regression analysis by considering all the available variables.

Results

PET was considered positive in 21 of 41 patients. Of these, recurrent BC was confirmed in 20 (95 %). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDG PET/CT were 87 %, 94 %, 95 %, 85 %, 90 %. AUC was 0.9 (95 %IC 0.8-1). Bayesian positive and negative likelihood ratios were 14.5 and 0.13, respectively. FDG PET/CT findings modified the therapeutic approach in 16 patients (modified therapy in 10 PET-positive patients, watch-and-wait in six PET-negative patients). PFS was significantly longer in patients with negative scan vs. those with pathological findings (85 % vs. 24 %, p?<?0.05; HR?=?12.4; p?=?0.001). Moreover, an unremarkable study was associated with a longer OS (88 % vs. 47 % after 2 years and 87 % vs. 25 % after 3 years, respectively, p?<?0.05). Standardized uptake value (SUV)max?>?6 and total lesion glycolysis (TLG)?>?8.5 were recognized as the most accurate thresholds to predict PFS (2-year PFS 62 % for SUVmax?<?6 vs. 15 % for SUVmax?>?6, p?=?0.018; 2-year PFS 66 % for TLG?<?8.5 vs. 18 % for TLG?>?8.5, p?=?0.09).

Conclusion

A very good diagnostic performance for FDG PET/CT was confirmed in patients with suspected recurrent BC. FDG PET/CT allowed for a change in treatment decision in about 40 % of cases and showed an important prognostic value in assessing PFS and OS.

     

<Superscript>11</Superscript>C-methylaminoisobutyric acid (MeAIB) PET for evaluation of prostate cancer: compared with <Superscript>18</Superscript>F-fluorodeoxyglucose PET

Objective

α-N-methyl-¹¹C-methylaminoisobutyric acid (¹¹C-MeAIB) is a selective substrate of system A amino acid transport, and known to accumulate in malignant lesions. The aim of this study was to evaluate the utility of MeAIB PET for the assessment of prostate cancer, compared with FDG PET.

Methods

Thirty-four men (age range 57–77 years) with prostate cancer were prospectively enrolled, and underwent MeAIB PET and FDG PET between January 2011 and January 2013. MeAIB PET and FDG PET were performed at 20 and 50 min post-injection, respectively. SUVmax of the prostate was calculated, and visual analysis was conducted for MeAIB and FDG PET studies. MRI images were visually evaluated if available. All patients received total prostatectomy subsequently, and imaging findings were compared with pathological results, including T stage, Gleason score, and tumor size. The patient-based and lesion-based sensitivity and specificity were calculated according to pathological significant cancer.

Results

Mean value of SUVmax of ¹¹C-MeAIB PET and ¹⁸F-FDG PET in prostate cancer were 3.18 (±1.90, range; 1.55–9.57) and 3.88 (±2.85, range; 2.04–14.47). MeAIB PET and FDG PET were positive by visual analysis in 47.1 % (16/34) and 44.1 % (15/34) of the patients. MRI was positive in 51.5 % (17/33). Pathological stage and Gleason score were as follows: Stage 2 (n = 23), 3 (n = 8), and 4 (n = 3); Gleason score 6 (n = 13), 7 (n = 16), 8 (n = 3), and 9 (n = 2). The sensitivities tended to be higher according to higher pathological T stage or Gleason sum score for both MeAIB and FDG PET studies. Visual analysis of both MeAIB PET and FDG PET had significant correlation with extraprostatic extension (p < 0.05). MeAIB PET and FDG PET had complementary results by visual analysis in the assessment of prostate cancer. The patient-based sensitivity of MeAIB PET, FDG PET, and MRI were 51.6, 48.4, and 56.7 %, respectively. The patient-based specificity of these modalities was 100 % for each modality.

Conclusions

MeAIB PET has better diagnostic results than FDG PET for the assessment of significant prostate cancer, and these PET studies showed complementary results. MRI has even better diagnostic results than ¹¹C-MeAIB PET. MeAIB accumulates in prostate cancer, which indicates that the system A amino acid transport pathway is activated in prostate cancer.

     

The response of FDG uptake to immunosuppressive treatment on FDG PET/CT imaging for cardiac sarcoidosis

Background

Immunosuppression is used to treat cardiac sarcoidosis, despite limited data. FDG PET/CT is used for detecting cardiac inflammation in patients with CS, yet there is variability in interpretation of FDG PET/CT. Our aim was to compare quantitative and qualitative interpretation of FDG PET/CT for CS in defining the FDG response to immunosuppression.

Methods and Results

Patients with CS (N = 43 total studies from 17 patients) had serial FDG PET/CT studies before/after immunosuppression. FDG uptake was analyzed qualitatively (visually; FDG-positive segments) and quantitatively (SUVmax; cardiac metabolic volume and activity (CMV, CMA); volume above SUV thresholds 2.7 and 4.1 g/mL). Complete resolution of FDG uptake was common using CMA (10/17), CMV (10/17), but a 2.7 g/mL SUV threshold (13/17) and SUVmax (14/17) were more likely to define partial responses. In six patients imaged after a reduction in immunosuppression, 4/6 had a rebound quantitative FDG uptake.

Conclusions

Quantitative interpretation of FDG PET/CT in CS can detect changes in FDG uptake in response to immunosuppression. Further studies are needed to see if quantitative changes in FDG uptake are associated with improved outcomes.

     

Prognostic value of metabolic indices and bone marrow uptake pattern on preoperative 18F–FDG PET/CT in pediatric patients with neuroblastoma

Purpose

To evaluate the prognostic value of metabolic parameters and bone marrow uptake (BMU) patterns on pretherapeutic 18-F-fluorodeoxyglucose (18F–FDG) positron emission tomography/computed tomography (PET/CT) in pediatric patients with neuroblastoma (NB).

Patients and methods

Forty-seven pediatric patients with newly diagnosed neuroblastoma who underwent 18F–FDG PET/CT were retrospectively reviewed. Clinicopathological factors and metabolic parameters including maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG) and bone marrow uptake patterns on PET/CT were compared to predict recurrence-free survival (RFS) and overall survival (OS) by univariate and multivariate analysis.

Results

During the follow-up period, 27 (57.4%) patients experienced recurrence. MTV (P = 0.001), TLG (P = 0.004) and BMU patterns (P = 0.025) remained significant predictive factors for tumor recurrence, along with tumor size, histology, stage, lactate dehydrogenase (LDH) and other distant metastasis (except bone metastasis). Univariate analysis showed that histology, stage, tumor size (>37.25 cm), other distant metastasis, MTV (>88.10cm³) and TLG (>1045.2 g) and BMU patterns correlated with both RFS and OS (P < 0.05). On multivariate analysis, TLG remained the only independent prognostic factor for RFS (P = 0.016) and OS (P = 0.012), and BMU patterns and MTV were statistically significant for OS (P = 0.024 and P = 0.038, respectively).

Conclusion

Pretherapeutic 18F-FDG PET/CT can provide reliable prognostic information for neuroblastoma pediatric patients, and patients with high MTV, TLG and focal bone marrow (unifocal and multifocal) uptake on PET/CT may have inferior outcomes during subsequent treatment.

     

Incremental diagnostic utility of gastric distension FDG PET/CT

Purpose

To assess the diagnostic utility of gastric distension (GD) FDG PET/CT in both patients with known gastric malignancy and those not known to have gastric malignancy but with incidental focal FDG uptake in the stomach.

Methods

This retrospective analysis included 88 patients who underwent FDG PET/CT following GD with hyoscine N-butylbromide (Buscopan®) and water ingestion as part of routine clinical evaluation between 2004 and 2014. FDG PET/CT scans before and after GD were reported blinded to the patient clinical details in 49 patients undergoing pretreatment staging of gastric malignancy and 39 patients who underwent GD following incidental suspicious gastric uptake. The PET findings were validated by a composite clinical standard.

Results

In the 49 patients undergoing pretreatment staging of gastric malignancy, GD improved PET detection of the primary tumour (from 80 % to 90 %). PET evaluation of tumour extent was concordant with endoscopic/surgical reports in 31 % (interpreter 1) and 45 % (interpreter 2) using pre-GD images and 73 % and 76 % using GD images. Interobserver agreement also improved with GD (κ?=?0.29 to 0.69). Metabolic and morphological quantitative analysis demonstrated a major impact of GD in normal gastric wall but no significant effect in tumour, except a minor increase in SUV related to a delayed acquisition time. The tumour to normal stomach SUVmax ratio increased from 3.8?±?2.9 to 9.2?±?8.6 (mean?±?SD) with GD (p?<?0.0001), facilitating detection and improved assessment of the primary tumour. In 25 (64 %) of the 39 patients with incidental suspicious gastric uptake, acquisition after GD correctly excluded a malignant process. In 10 (71 %) of the remaining 14 patients with persistent suspicious FDG uptake despite GD, malignancy was confirmed and in 3 (21 %) an active but benign pathology was diagnosed.

Conclusion

GD is a simple way to improve local staging with FDG PET in patients with gastric malignancy. In the setting of incidental suspicious gastric uptake, GD is also an effective tool for ruling out malignancy and leads to the avoidance of unnecessary endoscopy.