F18-FET PET in pediatric brain tumors: integrative analysis of image derived parameters and clinico-pathological data.

BACKGROUND: F18-FET PET has an established diagnostic role in adult brain gliomas. In this study we analyzed image derived static and dynamic parameters with available conventional MRI, histological, clinical and follow-up data in assessment of pediatric brain tumor patients at different stages of the disease. METHODS: Forty-four pediatric patients with median age 7 years, diagnosed with brain tumors and underwent forty-seven 18F-FET PET scans either initially (20 scans) or post-therapy (27 scans) were enrolled. Standardized analysis of summed FET PET images early from 10-20 min and late from 30-40 min post-injection were used for static (mean and maximum tumor to brain ratio [TBR] and biological tumor volume [BTV]) parameters evaluation as well as the time activity curve [TAC]. RESULTS: Nineteen out of 20 initially assessed patients had pathologically and/or clinico-radiologically proven neoplastic lesions and one patient had pathologically proven abscess. Receiver operator curve (ROC) marked early TBR max 2.95, early TBR mean 1.76, late TBR max 2.5 and late TBR mean 1.74 as discriminator points with diagnostic accuracy reaching 90% when TBR max was combined with dynamic parameters. Significant association was found between initial FET scans, early and late BTV and event free survival (EFS) (P value=0.042 and 0.005 respectively). In post-therapy assessment, the diagnostic accuracy of conventional MRI was 81.48% when used alone and 96.30% when combined with F18-FET PET scan findings. A cutoff point of 3.2 cm3 for late BTV, in post-therapy scans, was successfully marked as a predictor for therapy response (P value 0.042) and was significantly associated with EFS (P value 0.002). In FET-avid / MRI non-enhancing lesions, early TBR max was able to detect highly malignant processes (high-grade tumors in initial scans and residue/recurrence in post-therapy scans) with 80% sensitivity and 100% specificity when cutoff value of 2.25 was used (P value=0.024). In patients with FET-avid brainstem lesions, whether enhancing or non-enhancing in MRI scans, 81.8% were associated with high risk diagnoses and 68.2% of them were associated with poor therapy outcome. The degree of FET uptake matched tumor-grading, but did not show significant association with OS or EFS (P value>0.05). CONCLUSIONS: F18-FET PET seems to be an evolving pediatric neuro-imaging technique with valuable diagnostic and prognostic information at initial and post-therapy evaluation.

Watch and See Strategy in Selected Neuroblastoma Case Scenarios: Success and Limitations.

Neuroblastoma (NBL) in infants has the potential to regress/mature spontaneously. The literature showed some cases, subjected to initial observation, with reasonable outcome. Deferring/avoiding active treatment was investigated in selected favorable NBL cases. Patients enrolled on the watch and see strategy (W&S) had small primary tumor, localized stages 1 to 2, uncomplicated stage 4s, or stage 3. Tissue biopsy was not mandatory for infants below 6 months with localized mass. On progression, active intervention was indicated according to disease stage and risk after biological characterization. In total, 32 patients were enrolled on W&S strategy; male/female:2.6/1. Twelve had stages 1 to 2, 16 had stage 4s, and 4 were stage 3. Primary adrenal site was reported in 85% patients, and 65% patients had small mass (≤5 cm). Five-year overall and event-free survival were 100% and 80.9±7%, respectively, with a 43-month median follow-up duration. Spontaneous total/near total resolution of mass occurred in 50% patients. Median time to regression was 1.7 months, and 20.7 months until resolution. Only 19% patients witnessed progression; median time to progression was 4.8 months. W&S is a reasonable approach for localized and uncomplicated stages 3 and 4S NBL. Extended tumor size is a newly investigated entity in the present study. All progressive cases were safely rescued with 100% survival outcome.

Bilateral adrenal neuroblastoma: peculiar pattern of a rare pediatric presentation.

BACKGROUND: Bilateral suprarenal neuroblastoma (BSN) is a rare presentation. Few previously published literature showed BSN patients to have favorable pattern and prognosis. This study aim was to evaluate clinical and biological features in relation to outcome of Egyptian patients with BSN. METHODS: Included patients were diagnosed from 2007 to 2017, retrospectively. Tissue biopsy, imaging and bone marrow were evaluated at presentation. Clinical, demographic, biological variables and risk group were determined and analyzed in relation to overall (OS) and event-free-survival (EFS). RESULTS: BSN patients (n = 33) represented 2% of hospital patients with neuroblastoma during the 10-year study period, 17 were males and 16 were females. Twenty-four patients (72.7%) were infants, and 9 patients (27.3%) were above 1 year of age (range: 1 month to 3 years). Metachronous disease was present in only one patient. Amplified MYCN was found in 10 patients. Initially, most patients (n = 25) had distant metastasis, 6 had stage 3 versus 2 stage 2. Fifteen were high risk (HR), 15 intermediate (IR), 1 low risk (LR) and 2 were undetermined due to inadequate tissue biopsy. Three-year OS for HR and IR patients were 40.5% and 83.9% versus 23.2% and 56.6% EFS; respectively. CONCLUSION: BSN treatment is similar to unilateral disease. A more conservative surgical approach with adrenal tissue preservation on less extensive side should be considered. Biological variables and extent of disease are amongst the most important prognostic determinants. Future studies are warranted to further address the biologic profiling of BSN and highlight prognostic significance of size difference between both adrenal sides.

Prognostic value of initial [ 18 F]FDG PET/computed tomography volumetric and texture analysis-based parameters in patients with head and neck squamous cell carcinoma.

AIM OF WORK: To determine the predictive value of initial [ 18 F]FDG PET/computed tomography (CT) volumetric and radiomics-derived analyses in patients with head and neck squamous cell carcinoma (HNSCC). METHODS: Forty-six adult patients had pathologically proven HNSCC and underwent pretherapy [ 18 F]FDG PET/CT were enrolled. Semi-quantitative PET-derived volumetric [(maximum standardized uptake value (SUVmax) and mean SUV (SUVmean), total lesion glycolysis (TLG) and metabolic tumor volume (MTV)] and radiomics analyses using LIFEx 6.73.3 software were performed. RESULTS: In the current study group, the receiver operating characteristic curve marked a cutoff point of 21.105 for primary MTV with area under the curve (AUC) of 0.727, sensitivity of 62.5%, and specificity of 86.8% ( P value 0.041) to distinguish responders from non-responders, while no statistically significant primary SUVmean or max or primary TLG cut off points could be determined. It also marked the cutoff point for survival prediction of 10.845 for primary MTV with AUC 0.728, sensitivity of 80%, and specificity of 77.8% ( P value 0.026). A test of the synergistic performance of PET-derived volumetric and textural features significant parameters was conducted in an attempt to develop the most accurate and stable prediction model. Therefore, multivariate logistic regression analysis was performed to detect independent predictors of mortality. With a high specificity of 97.1% and an overall accuracy of 89.1%, the combination of primary tumor MTV and the textural feature gray-level co-occurrence matrix correlation provided the most accurate prediction of mortality ( P value < 0.001). CONCLUSION: Textural feature indices are a noninvasive method for capturing intra-tumoral heterogeneity. In our study, a PET-derived prediction model was successfully generated with high specificity and accuracy.

Prediction of pathological response using 18F FDG PET/CT derived metabolic parameters in locally advanced breast cancer patients.

AIM OF WORK: This study aims to assess the value of flurodeoxyglucose (FDG)-PET derived metabolic parameters for prediction of pathologic response in LABC postneoadjuvant therapy. METHODS: Totally 47 patients with LABC underwent initial and postneoadjuvant therapy PET scans. ΔSUVmax%, ΔTLG% and ΔMTV% were calculated. Post-therapy histopathologic therapeutic response was assessed. RESULTS: In total 91.5% of patients had invasive duct carcinoma and the remaining (8.5%) had invasive lobular carcinoma. Postneoadjuvant PET/CT was able to detect 91.7% of patients with pathologically proven complete response in primary tumor, 69% of those with Pathologic partial response and 88.3% of those with pathological no response (P value <0.001). However, 40 out of the 47 patients had regional nodal metastases. PET/CT was able to predict 57.1% of the patients with pathologically nonresponding nodal deposits and 93.9% of those revealed pathologic therapeutic effect (P value <0.001). Receiver operating characteristic curve (ROC) curve marked Δ1ry SUVmax of 26.25% (P value 0.003), Δ1ry TLG of 48.5% (P value 0.018). PET and pathological response correlated well with ΔSUVmax%, and Δ1ry TLG% correlated well with PET, pathologic response and expression of HER II receptors (P value <0.001, 0.003 and 0.037 respectively). ROC curve marked ΔLN SUVmax% of 80.15% (P value 0.012), ΔLN TLG% of 86.6% (P value 0.002), whereas for ΔLN MTV% cut off point of 55% (P value 0.003). ΔSUVmax%, ΔTLG % and ΔMTV% for regional nodal metastases, were significantly correlated with PET (P values <0.001, <0.001 and 0.003, respectively) and pathologic (P values 0.018, 0.001 and 0.002, respectively) response. CONCLUSION: FDG-PET is a useful tool for monitoring the neoadjuvant therapeutic effect for primary and regional nodes in patients with LABC.

Value of diffusion MRI versus [18F]FDG PET/CT in detection of cervical nodal metastases in differentiated thyroid cancer patients.

BACKGROUND: In differentiated thyroid cancer (DTC) patients, cervical nodal metastasis is a negative prognostic factor. Preoperative imaging plays an important role in treatment planning for nodal metastasis and recurrence. The aim of the study is to compare the diagnostic performance of the diffusion-weighted magnetic resonance imaging (DW-MRI) and the F-18 flurodeoxyglucose positron emission computed tomography ([18F]FDG PET/CT) in detection of cervical nodal deposits in DTC patients. MATERAL AND METHODS: The study was conducted on 30 patients, each performed both modalities just before the surgery. The gold standard was the pathological specimens with post-operative clinico-radiological follow-up, to assess the diagnostic performance of each modality. RESULTS: Based on pathological and post-operative clinico-radiological follow up data. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy were 84%, 80%, 50%, 95% and 83% for PET/CT compared to 84%, 60%, 42.8%, 91.3% and 80% for DW-MRI. On comparing the diagnostic performance of combined DW-MRI and PET/CT to each modality alone, the sensitivity and NPV were improved to 96% and 80% respectively. CONCLUSIONS: [18F]FDG PET/CT study is a valuable diagnostic modality for the assessment of cervical nodal deposits in DTC patients, surpassing DW-MRI. Combined PET/CT and DW-MRI techniques seemed to have synergistic performance, mainly in terms of sensitivity and NPV, for detection of nodal metastases.

FET PET Radiomics for Differentiating Pseudoprogression from Early Tumor Progression in Glioma Patients Post-Chemoradiation.

Currently, a reliable diagnostic test for differentiating pseudoprogression from early tumor progression is lacking. We explored the potential of O-(2-[18F]fluoroethyl)-L-tyrosine (FET) positron emission tomography (PET) radiomics for this clinically important task. Thirty-four patients (isocitrate dehydrogenase (IDH)-wildtype glioblastoma, 94%) with progressive magnetic resonance imaging (MRI) changes according to the Response Assessment in Neuro-Oncology (RANO) criteria within the first 12 weeks after completing temozolomide chemoradiation underwent a dynamic FET PET scan. Static and dynamic FET PET parameters were calculated. For radiomics analysis, the number of datasets was increased to 102 using data augmentation. After randomly assigning patients to a training and test dataset, 944 features were calculated on unfiltered and filtered images. The number of features for model generation was limited to four to avoid data overfitting. Eighteen patients were diagnosed with early tumor progression, and 16 patients had pseudoprogression. The FET PET radiomics model correctly diagnosed pseudoprogression in all test cohort patients (sensitivity, 100%; negative predictive value, 100%). In contrast, the diagnostic performance of the best FET PET parameter (TBRmax) was lower (sensitivity, 81%; negative predictive value, 80%). The results suggest that FET PET radiomics helps diagnose patients with pseudoprogression with a high diagnostic performance. Given the clinical significance, further studies are warranted.

Predictive Value of FDG PET/CT Versus Bone Marrow Biopsy in Pediatric Lymphoma.

PURPOSE: The aim of this study was to explore the positive predictive value and negative predictive value of FDG PET/CT. The prognostic impact of tumor burden of bone marrow infiltrates was diagnosed by FDG PET/CT at initial presentation. METHODS: This retrospective study enrolled 140 pediatric patients with pathologically proven lymphoma (113 Hodgkin disease and 27 Non-Hodgkin lymphoma). All patients had pretherapy FDG PET/CT. Bone marrow biopsy (BMB), clinical, radiological, and follow-up data were also collected. The skeleton was divided into 8 segments, and a 5-point scoring system was used for assessment of BM infiltration burden. RESULTS: Among the 140 lymphoma patients, FDG PET/CT revealed positive BM involvement in 41 patients; 2 of them were false-positive with negative BMB and regional MRI results. Positive predictive value was 95.1% for PET/CT compared with 100% with BMB. All patients diagnosed with positive BMI by BMB were detected by FDG PET/CT. On the contrary, BMB missed 25 patients (17.9%) with statistically significant difference. Negative predictive value was 100% for PET/CT compared with 80.2% for BMB (P < 0.05). FDG PET/CT upstaged 17.9% of the enrolled patients. Bone marrow involvement based on the 5-point scoring system was assessed. No significant difference was demonstrated in therapy outcome between patient with focal BMI (score 2) and extensive BMI (score 5; P = 0.06). CONCLUSIONS: FDG PET/CT has optimum negative predictive value compared with BMB in detection of bone marrow infiltrations in pediatric lymphoma with upstaging cases missed with BMB. Prognostic impact of BMI based on the 5-point scoring system reveals that the main influence is presence or absence of BMI rather than its tumor burden.

Diagnostic value of F-18 FDG PET/CT for local and distant disease relapse surveillance in surgically treated RCC patients: Can it aid in establishing consensus follow up strategy?

BACKGROUND: Aim of the study was to evaluate the diagnostic performance of FDG PET-CT for the detection of local and distant disease relapse in surgically treated patients with renal cell carcinoma (RCC). MATERIAL AND METHODS: This retrospective study includes 96 patients underwent FDG PET-CT scanning in the post-surgical follow up within the first 6-12 months referred to nuclear medicine department, to perform PET/CT study. Each patient underwent FDG PET-CT with low dose CT, followed immediately by full dose Ce-CT. Sites of the relapse were categorized into local and distant recurrence. Distant recurrence sites were divided into lymph nodes, lung, bone, and other soft tissue sites. The final diagnosis of disease status was made on subsequent follow up by conventional imaging (CT/MRI), FDG PET-CT, or histopathology whenever possible. RESULTS: Local and/or distant disease relapse was confirmed in 69 (71.9%) patients and the rest 28.1% were free. Regarding local recurrence FDG PET-CT showed specificity of 100% compared to 98.6% with Ce-CT (p > 0.05) and higher sensitivity noted with Ce-CT (100%) compared to 96% with FDG PET-CT. For global distant sites of metastases Ce-CT revealed high sensitivity and NPV of 93.3% & 96.9% respectively yet lower specificity (93.96%) and PPV (87.5%) was seen with Ce-CT compared to 99.6% and 99.1% with FDG PET-CT respectively. The higher Ce-CT sensitivity was attributed to its ability to detected 100% of cases of lung metastases compared to 80.6% with FDG PET-CT (P-value < 0.05). CONCLUSION: FDG PET-CT appears to be a very efficient tool in post-surgical surveillance of patients with RCC with notable ability to probe even uncommon sites of distant recurrence.