Prognostic value of lymph node-to-primary tumor standardized uptake value ratio in endometrioid endometrial carcinoma

Purpose

To determine whether the relative metabolic activity of pelvic or para-aortic LN compared with that of primary tumor measured by preoperative [¹⁸F]FDG PET/CT scan has prognostic value in patients with endometrioid endometrial carcinoma.

Methods

We retrospectively reviewed patients with endometrioid endometrial carcinoma who underwent preoperative [¹⁸F]FDG PET/CT scans. Prognostic values of PET/CT-derived metabolic variables such as maximum standardized uptake value (SUV) of the primary endometrial carcinoma (SUV_Tumor) and LN (SUV_LN), and the LN-to-endometrial carcinoma SUV ratio (SUV_LN / SUV_Tumor) were assessed.

Results

Clinico-pathological data, imaging data, and treatment results were reviewed for 107 eligible patients. Median post-surgical follow-up was 23 months (range, 6–60), and 7 (6.5%) patients experienced recurrence. Regression analysis showed that SUV_LN / SUV_Tumor (P < 0.001), SUV_LN (P = 0.003), International Federation of Gynecology and Obstetrics (FIGO) stage (P = 0.006), and tumor grade (P = 0.011) were risk factors of recurrence. Multivariate regression analysis revealed that FIGO stage (P = 0.034) was the independent risk factor of recurrence. SUV_LN / SUV_Tumor showed significant correlation with FIGO stage (P < 0.001), LN metastasis (P < 0.001), lymphovascular space invasion (P < 0.001), recurrence (P = 0.001), tumor grade (P < 0.001), and deep myometrial invasion of tumor (P = 0.022). Patient groups categorized by SUV_LN / SUV_Tumor showed significant difference in progression-free survival (Log-rank test, P = 0.001).

Conclusions

Preoperative SUV_LN / SUV_Tumor measured by [¹⁸F]FDG PET/CT was significantly associated with recurrence, and may become a novel prognostic factor in patients with endometrioid endometrial carcinoma.

     

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.

     

Refining prognosis in patients with hepatocellular carcinoma through incorporation of metabolic imaging biomarkers

Purpose

¹⁸F-fluorodeoxyglucose positron emission tomopraphy/computed tomography (FDGPET/CT) has been proven to be useful for imaging many types of cancer; however, its role is not well defined in hepatocellular carcinoma (HCC). We assessed the prognostic value of metabolic imaging biomarkers as established by baseline pretreatment FDG PET/CT in patients with HCC.

Methods

We retrospectively analyzed the records of patients with HCC who underwent FDG PET/CT before initial treatment from May 2013 through May 2014. Four PET/CT parameters were measured: maximum standardized uptake value (SUV_max), total lesion glycolysis (TLG), metabolic tumor volume (MTV), and tumor-to-normal-liver SUV ratio (TNR). Optimal cut-off values for the PET/CT parameters to stratify patients in terms of overall survival (OS) were determined. Multivariate analysis was performed to determine whether the PET/CT parameters could add to the prognostic value of the Cancer of the Liver Italian Program (CLIP) scoring system and the Barcelona-Clinic Liver Cancer (BCLC) staging system.

Results

The analysis included 56 patients. Univariate analysis of the association between OS and continuous variables, including the PET/CT parameters SUV_max, TLG, tumor size, total bilirubin level, and alkaline phosphatase level were significant predictors of OS. SUV_max ≥ 11.7, TLG ≥ 1,341, MTV ≥ 230 mL, and TNR ≥ 4.8 were identified as cut-off values. Multivariate analysis revealed that SUV_max ≥ 11.7 and TNR ≥ 4.8 were independent factors predicting a poor prognosis in both the CLIP scoring system and the BCLC staging system, as was TLG in the BCLC staging system.

Conclusion

Pretreatment FDG PET/CT in patients with HCC can add to the prognostic value of standard clinical measures. Incorporation of imaging biomarkers derived from FDG PET/CT into HCC staging systems should be considered.

     

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

Purpose

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

Methods

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

Results

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

Conclusion

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

     

Prognostic value of volumetric FDG PET/CT parameters in patients with oral tongue squamous cell carcinoma who were treated by superselective intra-arterial chemoradiotherapy

Purpose

This study aimed to evaluate the predictive and prognostic value of FDG PET/CT-based volumetric parameters in patients with oral tongue squamous cell carcinoma (OTSCC) treated by superselective intra-arterial chemoradiotherapy (IA-CRT).

Methods

We conducted a retrospective study including 33 patients with biopsy-proven OTSCC between May 2007 and February 2016. All of the patients were treated by IA-CRT. Pretreatment SUV_max and metabolic tumor volume (MTV) of the primary tumor were measured. The SUV thresholds of 2.5 and 5.0 were used. Progression-free survival (PFS) and overall survival (OS) were chosen as endpoints to evaluate prognosis. Univariate and multivariate analyses were performed to assess the potential independent effect of FDG PET/CT parameters.

Results

The median follow-up for surviving patients was 40.7 months (range 6.0–107.5 months). In univariate and multivariate analyses, SUV_max and MTV (5.0) were independent prognostic factors for PFS. In univariate analysis, SUV_max failed to predict OS. MTV (5.0) was a significant prognostic factor for OS, but multivariate analysis failed to show statistical independence because it could not exclude the possibility of an artifact due to N stage.

Conclusions

FDG PET/CT-based volumetric parameters may be significant prognostic markers for survival of patients with OTSCC who are treated by IA-CRT.

     

The prognostic value of <Superscript>18</Superscript>F–FDG PET/CT prior to liver transplantation for nonresectable colorectal liver metastases

Purpose

The main objective of this study was to evaluate the prognostic value of volumetric and metabolic information derivied from F-18 fluorodeoxyglucose positron emission tomography (¹⁸F–FDG PET) in combination with computed tomography (CT) prior to liver transplantation (LT) in patients with nonresectable colorectal liver metastases (CLM). Due to scarcity of liver grafts, prognostic information enabling selection of candidates who will gain the highest survival after LT is of vital importance. ¹⁸F–FDG PET/CT was a part of the preoperative study protocol. Patients without evidence of extrahepatic malignant disease on ¹⁸F–FDG PET/CT who also fulfilled all the other inclusion criteria underwent LT.

Methods

The preoperative ¹⁸F–FDG PET/CT examinations of all patients included in the SECA (secondary cancer) study were retrospectively assessed. Maximum, mean and peak standardized uptake values (SUV_max, SUV_mean and SUV_peak), tumor to background (T/B) ratio, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were measured and calculated for all liver metastases. Total MTV and TLG were calculated for each patient. Cut-off values were determined for each of these parameters by using receiver operating characteristic (ROC) analysis dividing the patients into two groups. One, three and five-year overall survival (OS) and disease free survival (DFS) for patients over and under the cut-off value were compared by using the Kaplan–Meier method and log rank test.

Results

Twenty-three patients underwent LT in the SECA study. Total MTV and TLG under the cut-off values were significantly correlated to improved OS at three and five years (p = 0.027 and 0.026) and DFS (p = 0.01). One, three and five-year OS and DFS were not significantly related to SUV_max, SUV_mean, SUV_peak or T/B-ratio.

Conclusion

Total MTV and TLG from ¹⁸F FDG PET/CT prior to LT for nonresectable CLM were significantly correlated to improved three and five-year OS and DFS and can potentially improve the patient selection for LT.

     

Increased evidence for the prognostic value of FDG uptake on late-treatment PET in non-tumour-affected oesophagus in irradiated patients with oesophageal carcinoma

Purpose

¹⁸F-FDG uptake in irradiated non-tumour-affected oesophagus (NTO) on restaging PET is a potential surrogate for the measurement of radiation-induced inflammation. Radiation-induced inflammation itself has been shown to be of high prognostic relevance in patients undergoing preoperative radiochemotherapy (RCT) for locally advanced oesophageal cancer. We assessed the prognostic relevance of FDG uptake in the NTO in an independent cohort of patients treated with definitive RCT.

Methods

This retrospective evaluation included 72 patients with oesophageal squamous cell carcinoma treated with definitive RCT with curative intent. All patients underwent pretreatment and restaging FDG PET after receiving a radiation dose of 40–50 Gy. Standardized uptake values (SUV_max/SUV_mean), metabolic tumour volume (MTV) and relative changes from pretreatment to restaging PET (?SUV_max/?SUV_mean) were determined within the tumour and NTO. Univariate Cox regression with respect to overall survival (OS), local control (LC), distant metastases (DM) and treatment failure (TF) was performed. Independence of parameters was tested by multivariate Cox regression.

Results

?SUV_max NTO and MTV were prognostic factors for all investigated clinical endpoints (OS, LC, DM, TF). Inclusion of clinical and PET tumour parameters in multivariate analysis showed that ?SUV_max NTO was an independent prognostic factor. Furthermore, multivariate analysis of ?SUV_max NTO using previously published cut-off values from preoperatively treated patients revealed that ?SUV_max NTO was independent prognostic factor for OS (HR?=?1.88, p =?0.038), TF (HR?=?2.11, p =?0.048) and DM (HR?=?3.02, p =?0.047).

Conclusion

NTO-related tracer uptake during the course of treatment in patients with oesophageal carcinoma was shown to be of high prognostic relevance. Thus, metabolically activity of NTO measured in terms of ?SUV_max NTO is a potential candidate for future treatment individualization (i.e. organ preservation).

     

<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.

     

Dual-time-point <Superscript>18</Superscript>F-FDG PET/CT in the diagnosis of solitary pulmonary lesions in a region with endemic granulomatous diseases

Objective

Granulomatous diseases (GDs) can be metabolically active and indistinguishable from lung cancer on ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) imaging. Evaluation of solitary pulmonary lesions remains a diagnostic challenge in regions with endemic GD. This study sought to determine the efficacy of dual-time-point (DTP) ¹⁸F-FDG PET/computed tomography (CT) imaging in diagnosing solitary pulmonary lesions from such regions.

Methods

A total of 50 patients with solitary pulmonary nodules or masses with confirmed histopathological diagnoses underwent DTP ¹⁸F-FDG PET/CT imaging at 1 and 3 h after tracer injection. The maximum standardized uptake value (SUV_max) on early and delayed scans (SUV_1h and SUV_3h, respectively) and retention index (RI) were calculated for each pulmonary lesion. Receiver operating characteristic analysis was performed to evaluate the discriminating validity of the parameters.

Results

There were 37 malignant and 13 benign solitary pulmonary lesions. Eight of the 13 (62 %) benign lesions were GDs. The sensitivity/specificity/accuracy of SUV_1h, SUV_3h and RI were 84/69/80 %, 84/85/84 %, and 81/54/74 %, respectively. SUV_3h had the best diagnostic performance, especially regarding specificity. The values of SUV_1h and SUV_3h were significantly different between malignant lesions and GD, while the RI values of malignant lesions and GD were both high (18.6 ± 19.5 and 18.7 ± 15.3 %, respectively; P = not significant).

Conclusion

SUV_3h appeared to improve the diagnostic specificity of ¹⁸F-FDG PET/CT in evaluating solitary pulmonary lesions from regions with endemic GD.

     

Increased FDG uptake on late-treatment PET in non-tumour-affected oesophagus is prognostic for pathological complete response and disease recurrence in patients undergoing neoadjuvant radiochemotherapy

Purpose

Early side effects including oesophagitis are potential prognostic factors in patients undergoing radiochemotherapy (RCT) for locally advanced oesophageal cancer (LAEC). We assessed the prognostic value of ¹⁸F-fluorodeoxyglucose (FDG) uptake within irradiated non-tumour-affected oesophagus (NTO) during restaging positron emission tomography (PET) as a surrogate for inflammation/oesophagitis.

Methods

This retrospective evaluation included 64 patients with LAEC who had completed neoadjuvant RCT and had successful oncological resection. All patients underwent FDG PET/CT before and after RCT. In the restaging PET scan maximum and mean standardized uptake values (SUV_max, SUV_mean) were determined in the tumour and NTO. Univariate Cox regression with respect to overall survival, local control, distant metastases and treatment failure was performed. Independence of clinically relevant parameters was tested in a multivariate Cox regression analysis.

Results

Increased FDG uptake, measured in terms of SUV_mean in NTO during restaging was significantly associated with complete pathological remission (p = 0.002) and did not show a high correlation with FDG response of the tumour (rho < 0.3). In the univariate analysis, increased SUV_max and SUV_mean in NTO was associated with improved overall survival (p = 0.011, p = 0.004), better local control (p = 0.051, p = 0.044), a lower rate of treatment failure (p < 0.001 for both) and development of distant metastases (p = 0.012, p = 0.001). In the multivariate analysis, SUV_max and SUV_mean in NTO remained a significant prognostic factor for treatment failure (p < 0.001, p = 0.004) and distant metastases (p = 0.040, p = 0.011).

Conclusions

FDG uptake in irradiated normal tissues measured on restaging PET has significant prognostic value in patients undergoing neoadjuvant RCT for LAEC. This effect may potentially be of use in treatment personalization.

     

The role of FDG PET/CT in therapy control of aortic graft infection

Purpose

¹⁸F-FDG PET/CT (PET/CT) is a useful tool for the diagnosis of aortic graft infection (AGI), but has rarely been used to influence therapeutic decisions during follow-up. We aimed to study the role of PET/CT in the long-term monitoring of patients.

Methods

Participants of the prospective Vascular Graft Infection Cohort Study (VASGRA) were included if they had microbiologically proven AGI. We quantified the metabolic activity in PET/CT by using maximum standardized uptake value (SUV_max) and further classified it as being focal or diffuse. Multivariable linear regression models were fit using generalized estimating equations to investigate factors associated with SUV_max over time.

Results

Sixty-eight participants with AGI contributed to 266 PET/CTs including 36 examinations performed after stop of antimicrobial therapy. Higher C-reactive protein (CRP) (adjusted coefficient per log₁₀ mg/L 0.05 [95% C.I. 0.02–0.08]) was associated with higher SUV_max. CRP, metabolic and clinical findings informed the decision to either start (medians of SUV_max 7.1 and CRP 31.5 mg/L; 100% focal uptake), escalate (SUV_max 9.5; CRP 31.5; 100% focal uptake), continue (SUV_max 6.0; CRP 9.95 mg/L; 90% focal uptake), or stop (SUV_max 4.3; CRP 3.5 mg/L; 61% focal uptake) antibiotic treatment. Of note, decisions to escalate or continue antibiotic treatment were taken despite normal CRP values in 12.5 and 35.7% of PET/CTs, respectively.

Conclusions

Consecutive PET/CTs could influence the clinical decision-making in patients with AGI in the near future. More studies on the use of PET/CT in case of aortic graft infection may offer the potential for individualized treatment approaches.

CLINICALTRIALS.GOV IDENTIFIER

NCT01821664.

     

Predictive value of <Superscript>18</Superscript>F-FDG PET/CT in adults with T-cell lymphoblastic lymphoma: post hoc analysis of results from the GRAALL-LYSA LLO3 trial

Purpose

We examined whether FDG PET can be used to predict outcome in patients with lymphoblastic lymphoma (LL).

Methods

This was a retrospective post hoc analysis of data from the GRAAL-LYSA LL03 trial, in which the treatment of LL using an adapted paediatric-like acute lymphoblastic leukaemia protocol was evaluated. PET data acquired at baseline and after induction were analysed. Maximum standardized uptake values (SUV_max), total metabolic tumour volume and total lesion glycolysis were measured at baseline. The relative changes in SUV_max from baseline (ΔSUV_max) and the Deauville score were determined after induction.

Results

The population analysed comprised 36 patients with T-type LL. SUV_max using a cut-off value of ≤8.76 vs. >8.76 was predictive of 3-year event-free survival (31.6% vs. 80.4%; p = 0.013) and overall survival (35.0% vs. 83.7%; p = 0.028). ΔSUV_max using a cut-off value of ≤80% vs. >80% tended also to be predictive of 3-year event-free survival (40.0% vs. 76.0%; p = 0.054) and overall survival (49.2% vs. 85.6%; p = 0.085). Total metabolic tumour volume, baseline total lesion glycolysis and response according to the Deauville score were not predictive of outcome.

Conclusions

A low initial SUV_max was predictive of worse outcomes in our series of patients with T-type LL. Although relatively few patients were included, the study also suggested that ΔSUV_max may be useful for predicting therapeutic efficacy.

     

[<Superscript>18</Superscript>F]FPRGD<Subscript>2</Subscript> PET/CT imaging of integrin α<Subscript>v</Subscript>β<Subscript>3</Subscript> levels in patients with locally advanced rectal carcinoma

Purpose

Our primary objective was to determine if [¹⁸F]FPRGD₂ PET/CT performed at baseline and/or after chemoradiotherapy (CRT) could predict tumour regression grade (TRG) in locally advanced rectal cancer (LARC). Secondary objectives were to compare baseline [¹⁸F]FPRGD₂ and [¹⁸F]FDG uptake, to evaluate the correlation between posttreatment [¹⁸F]FPRGD₂ uptake and tumour microvessel density (MVD) and to determine if [¹⁸F]FPRGD₂ and FDG PET/CT could predict disease-free survival.

Methods

Baseline [¹⁸F]FPRGD₂ and FDG PET/CT were performed in 32 consecutive patients (23 men, 9 women; mean age 63?±?8 years) with LARC before starting any therapy. A posttreatment [¹⁸F]FPRGD₂ PET/CT scan was performed in 24 patients after the end of CRT (median interval 7 weeks, range 3 – 15 weeks) and before surgery (median interval 4 days, range 1 – 15 days).

Results

All LARC showed uptake of both [¹⁸F]FPRGD₂ (SUV_max 5.4?±?1.5, range 2.7 – 9) and FDG (SUV_max 16.5?±?8, range 7.1 – 36.5). There was a moderate positive correlation between [¹⁸F]FPRGD₂ and FDG SUV_max (Pearson’s r?=?0.49, p?=?0.0026). There was a moderate negative correlation between baseline [¹⁸F]FPRGD₂ SUV_max and the TRG (Spearman’s r?=??0.37, p?=?0.037), and a [¹⁸F]FPRGD₂ SUV_max of >5.6 identified all patients with a complete response (TRG 0; AUC 0.84, 95 % CI 0.68 - 1, p?=?0.029). In the 24 patients who underwent a posttreatment [¹⁸F]FPRGD₂ PET/CT scan the response index, calculated as [(SUV_max1 ? SUV_max2)/SUV_max1] × 100 %, was not associated with TRG. Post-treatment [¹⁸F]FPRGD₂ uptake was not correlated with tumour MVD. Neither [¹⁸F]FPRGD₂ nor FDG uptake predicted disease-free survival.

Conclusion

Baseline [¹⁸F]FPRGD₂ uptake was correlated with the pathological response in patients with LARC treated with CRT. However, the specificity was too low to consider its clinical routine use.

     

Comparison of Bayesian penalized likelihood reconstruction versus OS-EM for characterization of small pulmonary nodules in oncologic PET/CT

Objective

To determine whether the recently introduced Bayesian penalized likelihood PET reconstruction (Q.Clear) increases the visual conspicuity and SUV_max of small pulmonary nodules near the PET resolution limit, relative to ordered subset expectation maximization (OS-EM).

Methods

In this institutional review board-approved and HIPAA-compliant study, 29 FDG PET/CT scans performed on a five-ring GE Discovery IQ were retrospectively selected for pulmonary nodules described in the radiologist’s report as “too small to characterize”, or small lung nodules in patients at high risk for lung cancer. Thirty-two pulmonary nodules were assessed, with mean CT diameter of 8 mm (range 2–18). PET images were reconstructed with OS-EM and Q.Clear with noise penalty strength β values of 150, 250, and 350. Lesion visual conspicuity was scored by three readers on a 3-point scale, and lesion SUV_max and background liver and blood pool SUV_mean and SUV_stdev were recorded. Comparison was made by linear mixed model with modified Bonferroni post hoc testing; significance cutoff was p < 0.05.

Results

Q.Clear improved lesion visual conspicuity compared to OS-EM at β = 150 (p < 0.01), but not 250 or 350. Lesion SUV_max was increased compared to OS-EM at β = 150 and 250 (p < 0.01), but not 350.

Conclusion

In a cohort of small pulmonary nodules with size near an 8 mm PET full-width half maximum, Q.Clear significantly increased lesion visual conspicuity and SUV_max compared to our standard non- time-of-flight OS-EM reconstruction, but only with low noise penalization. Q.Clear with β = 150 may be advantageous when evaluation of small pulmonary nodules is of primary concern.

     

SUV navigator enables rapid [<Superscript>18</Superscript>F]-FDG PET/CT image interpretation compared with 2D ROI and 3D VOI evaluations

Purpose

Positron emission tomography (PET) and the maximum standardized uptake value (SUV_max) is a useful technique for assessing malignant tumors. Measurements of SUV_max in multiple lesions per patient frequently require many time-consuming procedures. To address this issue, we designed a novel interface named SUV Navigator (SUVnavi), and the purpose of this study was to investigate its utility.

Materials and methods

We measured SUV_max in 661 lesions from 100 patients with malignant tumors. Diagnoses and SUV_max measurements were made with SUVnavi, 2D, and 3D measurements. SUV measurement accuracy in each method were also evaluated.

Results

The average reduction in time with SUVnavi versus 2D was 53.8% and 3D was 37.5%; time required with SUVnavi was significantly shorter than with 2D and 3D (P < 0.001 and P < 0.001, respectively). The time reduction and lesion number had a positive correlation (P < 0.001 and P < 0.001, respectively). SUV_max agreed with precise SUV_max in all lesions measured with SUVnavi and 3D but in only 466 of 661 lesions (70.5%) measured with 2D.

Conclusion

SUVnavi may be useful for rapid [¹⁸F]-fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]-FDG PET/CT) image interpretation without reducing the accuracy of SUV_max measurement.

     

[<Superscript>18</Superscript>F]FDG PET accurately differentiates infected and non-infected non-unions after fracture fixation

Purpose

Complete fracture healing is crucial for good patient outcomes. A major complication in the treatment of fractures is non-union. The pathogenesis of non-unions is not always clear, although implant-associated infections play a significant role, especially after surgical treatment of open fractures. We aimed to evaluate the value of [¹⁸F]FDG PET in suspected infections of non-union fractures.

Methods

We retrospectively evaluated 35 consecutive patients seen between 2000 and 2015 with suspected infection of non-union fractures, treated at a level I trauma center. The patients underwent either [¹⁸F]FDG PET/CT (N?=?24), [¹⁸F]FDG PET (N?=?11) plus additional CT (N?=?8), or conventional X-ray (N?=?3). Imaging findings were correlated with final diagnosis based on intraoperative culture or follow-up.

Results

In 13 of 35 patients (37 %), infection was proven by either positive intraoperative tissue culture (N?=?12) or positive follow-up (N?=?1). [¹⁸F]FDG PET revealed 11 true-positive, 19 true-negative, three false-positive, and two false-negative results, indicating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 85 %, 86 %, 79 %, 90 %, and 86 %, respectively. The SUV_max was 6.4?±?2.7 in the clinically infected group and 3.0?±?1.7 in the clinically non-infected group (p <0.01). The SUV_ratio was 5.3?±?3.3 in the clinically infected group and 2.6?±?1.5 in the clinically non-infected group (p <0.01).

Conclusion

[¹⁸F]FDG PET differentiates infected from non-infected non-unions with high accuracy in patients with suspected infections of non-union fractures, for whom other clinical findings were inconclusive for a local infection. [¹⁸F]FDG PET should be considered for therapeutic management of non-unions.

     

Prognostic value of preoperative intratumoral FDG uptake heterogeneity in patients with epithelial ovarian cancer

Objectives

To investigate the prognostic value of intratumoral FDG uptake heterogeneity (IFH) derived from PET/CT in patients with epithelial ovarian cancer (EOC).

Methods

We retrospectively reviewed patients with pathologically proven epithelial ovarian cancer who underwent preoperative ¹⁸F-FDG PET/CT scans. PET/CT parameters such as maximum and average standardized uptake values (SUV_max and SUV_avg), sum of all metabolic tumour volume (MTV), cumulative total lesion glycolysis (TLG) and IFH were assessed. Regression analyses were used to identify clinicopathological and imaging variables associated with disease-free survival (DFS).

Results

Clinicopathological data were reviewed for 61 eligible patients. The median duration of DFS was 13 months (range, 6–26 months), and 18 (29.5 %) patients experienced recurrence. High IFH values were associated with tumour recurrence (P?=?0.005, hazard ratio 4.504, 95 % CI 1.572–12.902). The Kaplan-Meier survival graphs showed that DFS significantly differed in groups categorized based on IFH (P?=?0.002, log-rank test). Moreover, there were significant differences in DFS (P?=?0.009) and IFH (P?=?0.040) between patients with and without recurrence.

Conclusions

Preoperative IFH measured by ¹⁸F-FDG PET/CT was significantly associated with EOC recurrence. FDG-based heterogeneity could be a useful and potential predicator of EOC recurrence before treatment.

Key Points

? Preoperative IFH was significantly associated with recurrence of EOC ? Disease-free survival significantly differed in groups categorized by IFH ? FDG-based heterogeneity could be a potential predicator of EOC recurrence before treatment

     

Metabolic activity by <Superscript>18</Superscript>F–FDG-PET/CT is predictive of early response after nivolumab in previously treated NSCLC

Background

Nivolumab, an anti-programmed death-1 (PD-1) antibody, is administered in patients with previously treated non-small cell lung cancer. However, little is known about the established biomarker predicting the efficacy of nivolumab. Here, we conducted a preliminary study to investigate whether ¹⁸F–FDG-PET/CT could predict the therapeutic response of nivolumab at the early phase.

Methods

Twenty-four patients were enrolled in this study. ¹⁸F–FDG-PET/CT was carried out before and 1 month after nivolumab therapy. SUV_max, metabolic tumour volume (MTV), and total lesion glycolysis (TLG) were calculated. Immunohistochemical analysis of PD-L1 expression and tumour-infiltrating lymphocytes was conducted.

Results

Among all patients, a partial metabolic response to nivolumab was observed in 29% on SUV_max, 25% on MTV, and 33% on TLG, whereas seven (29%) patients achieved a partial response (PR) based on RECIST v1.1. The predictive probability of PR (100% vs. 29%, p = 0.021) and progressive disease (100% vs. 22.2%, p = 0.002) at 1 month after nivolumab initiation was significantly higher in ¹⁸F–FDG on PET/CT than in CT scans. Multivariate analysis confirmed that ¹⁸F–FDG uptake after administration of nivolumab was an independent prognostic factor. PD-L1 expression and nivolumab plasma concentration could not precisely predict the early therapeutic efficacy of nivolumab.

Conclusion

Metabolic response by ¹⁸F–FDG was effective in predicting efficacy and survival at 1 month after nivolumab treatment.

     

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.

     

Role of <Superscript>18</Superscript>F-FDG PET/CT in patients affected by Langerhans cell histiocytosis

Purpose

Langerhans cell histiocytosis (LCH) is a rare hematological disorder for which the utility of¹⁸F-FDG PET/CT is unclear. Our aim was to explore the metabolic features of LCH and the possible role of¹⁸F-FDG PET/CT in LCH evaluation.

Materials and methods

We found 17 patients with histologically proven LCH who underwent 17¹⁸F-FDG PET/CT scans for staging and 42 scans for restaging/follow-up purposes. PET/CT results were compared with those obtained from other conventional imaging modalities (bone scintigraphy, plain radiogram, computed tomography, magnetic resonance).

Results

¹⁸F-FDG PET/CT was positive in 15/17 patients, and it detected 36/37 lesions; all bone and extraskeletal lesions, except for a cecal lesion, were¹⁸F-FDG-avid. Only 1/4 of the patients with lung LCH had hypermetabolic lesions. The average SUV_max of the FDG-avid lesions was 7.3 ± 6.7, the average lesion-to-liver SUV_max ratio was 3.4 ± 2.5, and the average lesion-to-blood pool SUV_max ratio was 4 ± 3.2. In comparison to other imaging methods,¹⁸F-FDG PET/CT detected additional lesions or was able to evaluate treatment response earlier in 33/74 cases; it was confirmatory in 38/74 and detected fewer lesions in 3/74 (all three with lung LCH).

Conclusions

¹⁸F-FDG PET/CT seems to be useful for evaluating LCH when compared to conventional imaging, except in pulmonary cases. It can be used both for staging and restaging purposes.