Whole-body magnetic resonance imaging: Incidental findings in paediatric and adult populations.

PURPOSE: To determine the prevalence and characterise the significance of incidental findings on whole-body MRI in paediatric and adult populations. METHODS: A retrospective, single-institution study over a period of 8 years. The study population comprised 325 paediatric (0-18 yrs) patients and 148 adults (19-40 yrs) referred to a specialist musculoskeletal oncology centre, who underwent whole-body MRI for a range of pathological indications. Incidental findings were recorded according to pathology (musculoskeletal or non-musculoskeletal), site and clinical relevance. RESULTS: Eighty-seven of 325 (26.8 %) paediatric patients and 51 of 148 (35.8 %) adults had incidental findings detected on whole-body MRI. The most common site was the musculoskeletal system, and within this location the lower limbs. Eighty-nine percent of incidental findings in paediatric patients and 79 % of incidental findings in adults were classified as being of either minor or no clinical significance. CONCLUSION: Incidental findings are common in paediatric and adult patients undergoing whole-body MRI, and are most frequently found in the lower limbs. The overwhelming majority are of minor clinical significance.

Effect of PET Image Reconstruction Techniques on Unexpected Aorta Uptake

Objectives: To determine if unexpected aorta uptake seen in some patients is influenced by popular modern reconstruction algorithms using semi-quantitative and qualitative analysis. Methods: Twenty-five consecutive patients without suspected vascular disease were selected for 18F-FDG positron emission tomography/ computed tomography (PET/CT) scanning and images of the aorta were created using iterative reconstruction (IT), IT + time of flight (TOF), IT + TOF + point spread function correction (referred collectively as UHD) with and without metal artefact reduction (MAR) algorithms. An experienced radiologist created aorta and blood pool (BP) regions of interests then copied these to all reconstructions for accurate positioning before recording target aorta standardized-uptake-values (SUVmax) and background BP SUVmean. Furthermore, target-to-background ratio (TBRmax) was defined by aorta SUVmax-to-BP SUVmean ratio for more analysis. Results: For aorta SUVmax with IT, IT + TOF, UHD, UHD + MAR reconstructions the mean ± standard deviation recorded were 2.15±0.43, 2.25±0.51, 2.25±0.45 and 2.09±0.4, respectively. Values for BP SUVmean were 1.61±0.31, 1.58±0.28, 1.58±0.28 and 1.47±0.25, respectively. Likewise, for TBRmax these were 1.35±0.19, 1.43±0.21, 1.43±0.19, 1.43±0.18, respectively. ANOVA analysis revealed no significant differences for aorta SUVmax (F(0.86) p=0.46), BP SUVmean (F(1.22) p=0.31) or TBRmax (F(0.99) p=0.4). However, the qualitative visual analysis revealed significant differences between IT + TOF with UHD (p=0.02) or UHD + MAR (p=0.02). Conclusion: Reconstruction algorithm effect on aorta SUVmax or BP SUVmean or TBRmax was not statistically significant. However, qualitative visual analysis showed significant differences between IT + TOF as compared with UHD or UHD + MAR reconstructions. Harmonization of techniques with a larger patient cohort is recommended in future clinical trials.