Sonja Kinner

Although the radiation dose impact of planning scans prior to the actual computed tomography (CT) scan has been addressed in previous studies, their systematic assessment across paediatric age groups and their relevance for establishing local diagnostic reference levels (DRLs) have not been thoroughly investigated and are not currently included in guideline recommendations. To investigate the influence of radiation dose from topogram, pre-monitoring, and monitoring scans by age on total radiation exposure and whether their doses need to be considered in DRLs and to establish local DRLs for these scan components. 102 chest CT scans with contrast material monitoring from 101 children (median age 12 years, interquartile range (IQR) 7–16 years) and 4498 chest CT scans from 4476 adults (⩾18 years) between January 2021 and May 2023 were retrospectively analysed. Paediatric scans were grouped into 5 age groups and compared with adult scans. The dose-length product (DLP) of topogram, pre-monitoring, and monitoring scans were evaluated and their effect on total radiation dose was analysed. Local DRLs were established for 5 different age groups. Radiation dose proportions of planning scans to total DLP in chest CT increased with decreasing age group (mainly p < 0.05), with the monitoring scan having the greatest impact. The median topogram proportion increased from 0.3% (⩾18 years) to 1.6% (<1 year), the pre-monitoring proportion from 0.5% (⩾18 years) to 3.5% (<1 year), and the monitoring proportion from 2.2% (⩾18 years) to 26.9% (<1 year). In children under 10 years, monitoring scans in chest CT have a large impact on radiation dose, contributing a median of 13%–27% of the total radiation dose compared to adults (median: 2.2%). Therefore, these planning scans should be monitored and included in radiation dose optimization efforts such as DRLs.

Signal increase on T1-weighted magnetic resonance imaging (MRI) in the dentate nucleus has been reported in adults after multiple injections of gadolinium-based contrast agents. Linear contrast agents are more prone to cause this increase. Studies in children are still rare and focus mostly on the analysis of one single agent.

BACKGROUND AND PURPOSE: Intrinsic T1-hyperintense signal has recently been reported in the deep gray nuclei on brain MR imaging after multiple doses of gadolinium-based contrast agents. Most reports have included adult patients and excluded those undergoing radiation or chemotherapy. We investigated whether T1 shortening is also observed in children and tried to determine whether radiochemotherapy is a risk factor for this phenomenon. MATERIALS AND METHODS: In this single-center retrospective study, we reviewed clinical charts and images of all patients 18 years of age or younger with ≥4 gadobenate dimeglumine–enhanced MRIs for 6 years. Seventy-six children (mean age, 9.3 years; 60 unconfounded by treatment, 16 with radiochemotherapy) met the selection criteria (>4 MR imaging examinations; mean, 8). T1 signal intensity ratios for the dentate to pons and globus pallidus to thalamus were calculated and correlated with number of injections, time interval, and therapy. RESULTS: Among the 60 children without radiochemotherapy, only 2 had elevated T1 signal intensity ratios (n = 20 and 16 injections). Twelve of the 16 children with radiochemotherapy showed elevated signal intensity ratios. Statistical analysis demonstrated a significant signal intensity ratio change for the number of injections (P < .001) and amount of gadolinium (P = .008), but not for the interscan time interval (P = .35). There was a significant difference in the average signal intensity ratio change between those with and without radiochemotherapy (P < .001). Chart review revealed no new neurologic deficits in any patients, related to their underlying conditions and prior surgeries. CONCLUSIONS: Compared with published adult series, children show a similar pattern of T1 hyperintense signal changes of the dentate and globus pallidus after multiple gadobenate dimeglumine injections. The T1 signal changes in children may have a later onset but are accelerated by radiochemotherapy.

OBJECTIVE. Appendicitis is frequently diagnosed in the emergency department, most commonly using CT. The purpose of this study was to compare the diagnostic accuracy of contrast-enhanced MRI with t...

Objectives Biliary complications after liver transplantation (LT) are common. This study aimed to ascertain the value of gadoxetic acid-enhanced T1-weighted (T1w) magnetic resonance cholangiography (MRC) to evaluate anastomotic strictures (AS), non-anastomotic strictures (NAS) and biliary casts (BC). Methods Sixty liver-transplanted patients with suspicion of biliary complications and T2w-MRCP and T1w-MRC followed by endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (PTC) were analysed. Two readers reviewed the MRCs and rated image quality (IQ) and likelihood for AS/NAS/BC on Likert scales. Sensitivity, specificity and predictive values were calculated, ROC curve analysis performed, and inter-reader variability assessed. The subjective added value of T1w-MRC was rated. Results IQ was high for all sequences without significant differences (2.83–2.88). In 39 patients ERCP/PTC detected a complication. Sensitivity and specificity for AS were 64–96 using T2w-MRCP, increasing to 79–100 using all sequences. Use of all sequences increased the sensitivity of detecting NAS/BC from 72–92% to 88–100% and 67–89% to 72–94%, respectively. Kappa values were substantial (0.45–0.62). T1w-MRC was found to be helpful in 75–83.3%. Conclusions Combining T1w-MRC and T2w-MRCP increased sensitivity and specificity and diagnostic confidence in patients after LT with suspected biliary complications. T1w-MRC is a valuable tool for evaluating post-transplant biliary complications. Key Points • T1w-MRC is a valuable tool for evaluating post-transplant biliary complications. • Adding T1w-MRC to T2w-MRC increases diagnostic confidence for detection of biliary complications. • A combination of T1w-MRC and T2w-MRCP leads to the best results.

OBJECTIVE. The purpose of this article is to describe our approach to contrast-enhanced abdominal MRI in patients with nontraumatic abdominal pain and suspected appendicitis. We aim to share our experience on the advantages, pearls, and pitfalls of MRI in this clinical setting, in comparison with CT and ultrasound. CONCLUSION. We present some typical cases of appendicitis and alternative diagnoses in patients presenting with acute nontraumatic abdominal pain.