Additional file 1: of Impact of time-of-flight PET on quantification accuracy and lesion detection in simultaneous 18F-choline PET/MRI for prostate cancer

Table S1. Results of image quality rating. (DOCX 12 kb

Relation between R_DW and R_BMI and clinical NECR measured in patients (NECR_P).

<p>Relation between R_DW and R_BMI and clinical NECR measured in patients (NECR_P).</p

Evaluation and transfer steps from activities in PET/CT (1) to theoretically (2,3) achievable reduction in injected activity in TOF-PET/MR (4) and clinically realistically activities in TOF-PET/MR (5—blue arrow).

<p>Evaluation and transfer steps from activities in PET/CT (1) to theoretically (2,3) achievable reduction in injected activity in TOF-PET/MR (4) and clinically realistically activities in TOF-PET/MR (5—blue arrow).</p

The NEMA phantom curve of the TOF-PET/CT (continuous) and TOF-PET/MR (dashed), provided by its manufacturer.

<p>See enlarged image of the clinically relevant area (black box) in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128842#pone.0128842.g004" target="_blank">Fig 4</a>.</p

50-year-old female with ulnocarpal impaction syndrome.

<p>Relative overlength of the distal articular surface of the ulna on plain radiograph with localized geographic cystic-sclerotic changes in the medial proximal pole of the lunate and overprojection of TFCC calcification (a), focally increased radiotracer uptake in the carpal region on bone scan (b, arrow), subcortical cyst with rim sclerosis at the proximal ulnar pol of the lunate bone on CT (c, arrow), subcortical cyst displaying tracer accumulation on SPECT/CT fusion image (d, arrow), several subchondral cysts with adjacent alterations of bone marrow signal in the proximal ulnar pol of the lunate bone in PDw SPIR (e, arrow) and T1w image (f, arrow) on MRI. </p

Kappa of interobserver agreement in detection of the relevant lesion.

<p>The error bars delineate the 95% confidence interval. </p

44-year-old female with osteomalacia of the lunate bone.

<p>Relative shortness of the distal articular surface of the ulna on plain radiograph (a), focally increased radiotracer uptake in the carpal region on bone scan (b), slightly hyperdense and coarse trabecular structure of the lunate bone on CT (c), tracer accumulation throughout the lunate bone on SPECT/CT fusion image (d), altered signal of lunate bone marrow in PDw SPIR (e) and T1w image (f) on MRI. Besides, there is also focal tracer accumulation in the ulnar-sided base of the 2^nd metacarpal (d) indicating a “carpal boss”, which was not in the main clinical focus at that time. </p

Influence of inter-observer delineation variability on radiomics stability in different tumor sites

<p><b>Background:</b> Radiomics is a promising methodology for quantitative analysis and description of radiological images using advanced mathematics and statistics. Tumor delineation, which is still often done manually, is an essential step in radiomics, however, inter-observer variability is a well-known uncertainty in radiation oncology. This study investigated the impact of inter-observer variability (IOV) in manual tumor delineation on the reliability of radiomic features (RF).</p> <p><b>Methods:</b> Three different tumor types (head and neck squamous cell carcinoma (HNSCC), malignant pleural mesothelioma (MPM) and non-small cell lung cancer (NSCLC)) were included. For each site, eleven individual tumors were contoured on CT scans by three experienced radiation oncologists. Dice coefficients (DC) were calculated for quantification of delineation variability. RF were calculated with an in-house developed software implementation, which comprises 1404 features: shape (<i>n</i> = 18), histogram (<i>n</i> = 17), texture (<i>n</i> = 137) and wavelet (<i>n</i> = 1232). The IOV of RF was studied using the intraclass correlation coefficient (ICC). An ICC >0.8 indicates a good reproducibility. For the stable RF, an average linkage hierarchical clustering was performed to identify classes of uncorrelated features.</p> <p><b>Results:</b> Median DC was high for NSCLC (0.86, range 0.57–0.90) and HNSCC (0.72, 0.21–0.89), whereas it was low for MPM (0.26, 0–0.9) indicating substantial IOV. Stability rate of RF correlated with DC and depended on tumor site, showing a high stability in NSCLC (90% of total parameters), acceptable stability in HNSCC (59% of total parameters) and low stability in MPM (36% of total parameters). Shape features showed the weakest stability across all tumor types. Hierarchical clustering revealed 14 groups of correlated and stable features for NSCLC and 6 groups for both HNSCC and MPM.</p> <p><b>Conclusion:</b> Inter-observer delineation variability has a relevant influence on radiomics analysis and is strongly influenced by tumor type. This leads to a reduced number of suitable imaging features.</p