ABSTRACT
BACKGROUND: An accurate measurement of the target volume is of primary importance in theragnostics of hyperthyroidism. OBJECTIVE: Our purpose was to evaluate the accuracy of a threshold-based isocontour extraction procedure for thyroid tissue volumetry from SPECT-CT. METHODS: Cylindrical vials with a fixed volume of 99mTcO4 at different activities were inserted into a neck phantom in two different thickness settings. Images were acquired by orienting the phantom in different positions, i.e., 40 planar images and 40 SPECT-CT. The fixed values of the isocontouring threshold for SPECT and SPECT-CT were calculated by means of linear and spline regression models. Mean, Median, Standard Deviation, Standard Error, Mean Absolute Percentage Error and Root Mean-Square Error were computed. Any difference between the planar method, SPECT and SPECT-CT and the effective volume was evaluated by means of ANOVA and posthoc tests. Moreover, planar and SPECT-CT acquisitions were performed in 8 patients with hyperthyroidism, considering relevant percentage differences greater than > 20% from the CT gold standard. RESULTS: Concerning phantom studies, the planar method shows higher values of each parameter than the other two methods. SPECT-CT shows lower variability. However, no significant differences were observed between SPECT and SPECT-CT measurements. In patients, relevant differences were found in 7 out of 9 lesions with the planar method, in 6 lesions with SPECT, but in only one with SPECT-CT. CONCLUSION: Our study confirms the superiority of SPECT in volume measurement if compared with the planar method. A more accurate measurement can be obtained from SPECT-CT.
Subject(s)
Hyperthyroidism , Sodium Pertechnetate Tc 99m , Humans , Hyperthyroidism/diagnostic imaging , Radiopharmaceuticals/pharmacology , Tomography, Emission-Computed, Single-Photon/methods , Tomography, X-Ray Computed/methodsABSTRACT
PURPOSE: Oropharynx squamous cell carcinoma (OPSCC) is a subtype of head and neck squamous cell carcinoma (HNSCC) arising from the base of the tongue, lingual tonsils, tonsils, oropharynx or pharynx. The majority of HPV-positive OPSCCs has a good prognosis, but a fraction of them has a poor prognosis, similar to HPV-negative OPSCCs. An in-depth understanding of the molecular mechanisms underlying OPSCC is mandatory for the identification of novel prognostic biomarkers and/or novel therapeutic targets. METHODS: 14 HPV-positive and 15 HPV-negative OPSCCs with 5-year follow-up information were subjected to gene expression profiling and, subsequently, compared to three extensive published OPSCC cohorts to define robust biomarkers for HPV-negative lesions. Validation of Aldo-keto-reductases 1C3 (AKR1C3) by qRT-PCR was carried out on an independent cohort (n = 111) of OPSCC cases. In addition, OPSCC cell lines Fadu and Cal-27 were treated with Cisplatin and/or specific AKR1C3 inhibitors to assess their (combined) therapeutic effects. RESULTS: Gene set enrichment analysis (GSEA) on the four datasets revealed that the genes down-regulated in HPV-negative samples were mainly involved in immune system, whereas those up-regulated mainly in glutathione derivative biosynthetic and xenobiotic metabolic processes. A panel of 30 robust HPV-associated transcripts was identified, with AKR1C3 as top-overexpressed transcript in HPV-negative samples. AKR1C3 expression in 111 independent OPSCC cases positively correlated with a worse survival, both in the entire cohort and in HPV-positive samples. Pretreatment with a selective AKR1C3 inhibitor potentiated the effect of Cisplatin in OPSCC cells exhibiting higher basal AKR1C3 expression levels. CONCLUSIONS: We identified AKR1C3 as a potential prognostic biomarker in OPSCC and as a potential drug target whose inhibition can potentiate the effect of Cisplatin.
Subject(s)
Aldo-Keto Reductase Family 1 Member C3/metabolism , Biomarkers, Tumor/metabolism , Oropharyngeal Neoplasms/metabolism , Aged , Aged, 80 and over , Aldo-Keto Reductase Family 1 Member C3/genetics , Biomarkers, Tumor/genetics , Carcinoma, Squamous Cell/genetics , Carcinoma, Squamous Cell/metabolism , Carcinoma, Squamous Cell/pathology , Carcinoma, Squamous Cell/virology , Cell Line, Tumor , Cell Proliferation/genetics , Cell Survival/drug effects , Cisplatin/pharmacology , Down-Regulation/genetics , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Gene Ontology , Gene Regulatory Networks , Humans , Male , Middle Aged , Oropharyngeal Neoplasms/genetics , Oropharyngeal Neoplasms/pathology , Oropharyngeal Neoplasms/virology , Papillomavirus Infections/complications , Prognosis , Up-Regulation/geneticsABSTRACT
To analyze the inter-observer variability and the potential impact of (18)F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) imaging for target volume delineation in preoperative radiotherapy of rectal cancer. Gross tumor volume (GTV) and clinical target volume (CTV) in 2 cases of rectal cancer were contoured by 10 radiation oncologists, 5 on CT and 5 on PET/CT images. Resulting volumes were analyzed by coefficient of variation (CV) and concordance index (CI). Mean GTV was 120 cc +/- 20.4 cc in case A and 119 cc +/- 35.7 cc in case B. Mean CTV was 723 cc +/- 147.5 cc in case A and 739 cc +/- 195.6 cc in case B. CV was lower and CI was similar or higher across the observers contouring GTV on PET/CT. CTV variability was less influenced by the use of PET/CT. PET/CT may allow reducing inter-observer variability in GTV delineation.
