Phantom study investigating the repeatability of radiomic features with alteration of image acquisition parameters in magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging (MRI) has many different alterable parameters that affect how an image appears. This is relevant in radiomics which produces quantitative features through analysis of medical images. One significant acknowledged limitation of radiomics is repeatability. This phantom study aims to further investigate the repeatability of radiomic features (RaF), within MRI, across a range of different echo (TE) and repetition times (TR). METHODS: A phantom was scanned 10 times under identical conditions on a 3T scanner using head coil over 4 months. The TE ranged from 80 to 110 ms while the TR from 3000 to 5000 ms. Radiomics analysis was performed on the same segmented section of the phantom across all TE and TR combinations. Intraclass Correlation Coefficient (ICC) was calculated across the different TE and TR ranges to investigate the repeatability of RaF. RESULTS: Of 1596 features calculated, 187 features had ICC >0.9 across the range of TE, while 82 features had an ICC >0.9 across a range of TR. 664 had ICC >0.75 across the range of TEs, with 541 across the range of TR values. There was an overlap of 51 features with ICC >0.9. CONCLUSION: Repeatability of RaF in MRI is dependent on imaging parameters and careful consideration of these, in combination with variable selection, is required when applying radiomics to MRI.

Investigation of the Inter- and Intrascanner Reproducibility and Repeatability of Radiomics Features in T1-Weighted Brain MRI.

BACKGROUND: Radiomics is the high throughput analysis of medical images using computer algorithms, which specifically assess textural features. It has increasingly been proposed as a tool for the development of imaging biomarkers. However, an important acknowledged limitation of radiomics is the lack of reproducibility of features produced. PURPOSE: To assess reproducibility and repeatability of radiomics variables in brain MRI through a multivisit, multicenter study. STUDY TYPE: Retrospective. POPULATION: Fourteen individuals visiting three institutions twice, 10 males with the mean age of 36.3 years and age range 25-51. FIELD STRENGTH: 3D T1W inversion recovery on three 1.5-T General Electric scanners. ASSESSMENT: Radiomics analysis by a consultant radiologist performed on the T1W images of the whole brain on all visits. All possible radiomics features were generated. STATISTICAL TEST: Concordance correlation coefficient (CCC) and dynamic range (DR) for all variables were calculated to assess the test-retest repeatability. Intraclass correlation coefficients (ICCs) were calculated to investigate the reproducibility of features across centers. RESULTS: Of 1596 features generated, 57 from center 1, 15 from center 2, and 22 from center 3 had a CCC > 0.9 and DR > 0.9. Eight variables had CCC > 0.9 and DR > 0.9 in all centers. Forty-one variables had an ICC of >0.9. No variables had CCC > 0.9, DR > 0.9, and ICC > 0.9. DATA CONCLUSION: Repeatability and reproducibility of variables is a significant limitation of radiomics analysis in 3DT1W brain MRI. Careful selection of radiomic features is required. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY STAGE: 2.

Clinically significant findings in patients with focal incidental colorectal abnormalities on positron emission tomography-CT scans.

INTRODUCTION: The aim of this study was to determine the clinical significance of focal incidentally detected colorectal abnormalities on 18 F- Fluoro-2-Deoxy-D-Glucose (FDG) PET-CT scans. METHODS: Retrospective audit of PET-CT scans performed at our institution between 2009 and 2014. Demographic and clinical details were retrieved from electronic patient records. An advanced adenoma was defined as: ≥1 cm in size, tubullo-villous histology, or displaying high grade dysplasia. A high-risk lesion (HRL) was defined as an advanced adenoma or colorectal cancer (CRC). RESULTS: Of the 1911 PET-CT eligible scans, focal incidental colorectal FDG uptake was detected in 99 (5.2%) patients. Colonoscopy was undertaken in 43 (43.4%) patients and 45 FDG-avid sites were evaluated. The commonest site of abnormal FDG uptake was the rectosigmoid region, with 34 (75.6%) of the 45 foci being located in this area. Overall, 23 (53.5%) of these patients had clinically significant pathology. Of the 45 focal PET-CT abnormalities evaluated, 17 (37.8%) were adenomas, of which 11 (24.4%) were advanced adenomas, and six (13.3%) were cancers, with a total of 17 (37.8%) HRLs. Five of the six patients with CRC underwent surgical resection, whilst one had endoscopic resection. The overall survival for the entire cohort was 18 months (range 1-72 months) with those that underwent colonoscopy having higher overall survival compared to those that did not (38 vs. 13.5 months). CONCLUSION: Incidental colorectal abnormalities on PET-CT scans are often clinically significant. However, careful selection for colonoscopy is important due to the poor survival in these patients related to the underlying primary malignancy.

Assessment of sarcopenia and changes in body composition after neoadjuvant chemotherapy and associations with clinical outcomes in oesophageal cancer.

OBJECTIVES: Sarcopenia and changes in body composition following neoadjuvant chemotherapy (NAC) may affect clinical outcome. We assessed the associations between CT body composition changes following NAC and outcomes in oesophageal cancer. METHODS: A total of 35 patients who received NAC followed by oesophagectomy, and underwent CT assessment pre- and post-NAC were included. Fat mass (FM), fat-free mass (FFM), subcutaneous fat to muscle ratio (FMR) and visceral to subcutaneous adipose tissue ratio (VA/SA) were derived from CT. Changes in FM, FFM, FMR, VA/SA and sarcopenia were correlated to chemotherapy dose reductions, postoperative complications, length of hospital stay (LOS), circumferential resection margin (CRM), pathological chemotherapy response, disease-free survival (DFS) and overall survival (OS). RESULTS: Nine (26 %) patients were sarcopenic before NAC and this increased to 15 (43 %) after NAC. Average weight loss was 3.7 % ± 6.4 (SD) in comparison to FM index (-1.2 ± 4.2), FFM index (-4.6 ± 6.8), FMR (-1.2 ± 24.3) and VA/SA (-62.3 ± 12.7). Changes in FM index (p = 0.022), FMR (p = 0.028), VA/SA (p = 0.024) and weight (p = 0.007) were significant univariable factors for CRM status. There was no significant association between changes in body composition and survival. CONCLUSIONS: Loss of FM, differential loss of VA/SA and skeletal muscle were associated with risk of CRM positivity. KEY POINTS: • Changes in CT body composition occur after neoadjuvant chemotherapy in oesophageal cancer. • Sarcopenia was more prevalent after neoadjuvant chemotherapy. • Fat mass, fat-free mass and weight decreased after neoadjuvant chemotherapy. • Changes in body composition were associated with CRM positivity. • Changes in body composition did not affect perioperative complications and survival.