Non-contrast-enhanced MR angiography using time-spin labelling inversion pulse technique for detecting crossing renal vessels in children with symptomatic ureteropelvic junction obstruction: comparison with surgical findings.

OBJECTIVES: Investigate the feasibility and evaluate the accuracy of non-contrast-enhanced MR angiography (NC-MRA) using time-spin labelling inversion pulse (time-SLIP)to identify crossing renal vessels (CRVs) in children requiring surgical treatment of ureteropelvic junction (UPJ) obstructionand compare to laparoscopic findings. MATERIALS AND METHODS: Nineteen children ranging from 6 to 16 years of age underwent NC-MRA using the time-SLIP technique before surgery. Two independent readers analysed the MRA images. Number of renal arteries and presence or absence of CRVs were identified and compared with surgicalfindings. Image quality was assessed, as well as the presence of CRVs and measurement of renal pelvis diameter. Intra and inter-reader agreement was calculated using Cohen's kappa coefficient and Bland-Altman plots. RESULTS: The overall image quality was fair or good in 88% of cases. NC-MRA demonstrated CRVs at the level of the obstruction in 10 children and no CRV in 9 children. All were confirmed intra-operatively except in one of the nine children. Sensitivity, specificity, NPV, PPV for predicting CRVs were 92%, 100%, 100% and 87.5%, respectively, for both readers. CONCLUSION: NC-MRA is a good alternative to contrast-enhanced MRA and CT scanning for identifying CRVs in children with symptomatic UPJ. KEY POINTS: • Time-SLIP technique offers acceptable imaging quality for identifying crossing renal vessel. • Time-SLIP technique is easy to apply to the renal MRA examination. • Time-SLIP technique is an alternative to contrast-enhanced MRA and CT scanning.

Measurement of inter- and intra-observer variability in the routine clinical interpretation of brain 18-FDG PET-CT.

OBJECTIVE: To objectify and quantify inter- and intra-observer variability of brain 18-FDG PET-CT interpretation in the context of cognitive and functional impairment amongst the elderly. METHODS: 25 patients underwent brain 18-FDG PET-CT for investigation of dementia/MCI and frail elderly patients. Three observers interpreted studies in two forms: standardised datasets reconstructed by an outside observer and individualised reconstructions. Observers graded regional 18-FDG uptake in 11 brain areas and gave overall impressions on studies as pathological/normal. One observer repeated this process following a 3-month interval. The Kappa statistic was used to calculate inter- and intra-observer agreement on grading of regional 18-FDG uptake and overall impressions of studies as pathological/normal. RESULTS: Moderate inter-observer agreement was observed across standardised and individualised dataset reconstructions when 11 regional brain areas were compared cumulatively and overall impressions on studies were given as pathological vs normal. Higher levels of inter-observer agreement were found when comparing high versus low grading of regional uptake and when reporting standardised reconstructions. Intra-observer agreement between standardised vs individualised dataset reconstructions were moderate-to-fair across 11 brain regions cumulatively. Temporal intra-observer agreement of individualised dataset reconstructions comparing normal vs pathological opinions showed strong agreement (κ = 0.884 [95 % CI 0.662; 1.000)]. CONCLUSION: Despite a strong agreement in final diagnosis, this study demonstrates a moderate inter- and substantial intra-observer reproducibility in reporting brain 18-FDG PET-CT. Such results suggest that the visual analysis approach is different between nuclear physicians but leads to the same final diagnosis.

A false-positive finding in therapeutic evaluation: hypermetabolic axillary lymph node in a lymphoma patient following FDG extravasation.

We report a case of a false-positive finding in FDG PET/CT following radiotracer extravasation. A 15-year-old male patient was referred for therapeutic evaluation status post-chemotherapy for a lymphoblastic lymphoma. FDG PET/CT showed discordant findings with a marked decrease in a liver/hepatic hilum uptake, disappearance of a subcutaneous left supraclavicular uptake, and appearance of intense right axillary nodal uptake. Extravasation in the right superior limb was noted. Comparison with the previous scan showed that the axillary nodes were present, measured less than 1 cm in their short axis, had not increased in size, and had a fatty hilum. We concluded that FDG uptake was caused by a migration in lymphatic vessels.