OBJECTIVE: Radiography is still used worldwide for detection of sacroiliitis in juvenile spondyloarthritis (SpA), despite low sensitivity and reliability. We aimed to define unequivocal evidence of sacroiliitis on pelvic radiography in skeletally immature youth for use in classification criteria when MRI is unavailable.

METHODS: Subjects were a retrospective cohort of juvenile spondyloarthritis (SpA) patients with a radiograph and MRI as part of a diagnostic evaluation for axial disease. Six musculoskeletal imaging experts underwent an iterative consensus process to define "unequivocal sacroiliitis" on radiography in skeletally immature youth. Radiographs were graded using the modified New York (mNY) criteria and the unequivocal sacroiliitis criteria. Interrater agreement was assessed with Fleiss' kappa statistic. Specificity, area under receiver operator characteristic (AUROC), and sensitivity of the two measures were tested using 2 MRI reference standards.

RESULTS: 112 subjects, median age 14.9 years were included. Fleiss' kappa was fair for the mNY [0.51 (95% CI: 0.39-0.64)] and unequivocal sacroiliitis criteria [0.55 (95% CI: 0.43-0.66)]. The unequivocal sacroiliitis criteria achieved >90% specificity using both MRI reference standards. Sensitivity (59.26/57.14 vs 44.83/43.33) and AUROC (0.76/0.76 versus 0.71/0.71) were higher, for both reference standards, for the unequivocal sacroiliitis in youth definition than the mNY criteria, respectively.

CONCLUSION: We propose the first consensus-derived definition of unequivocal sacroiliitis by radiography in skeletally immature youth. This definition achieved excellent specificity and had higher AUROC and sensitivity than the mNY criteria using both MRI reference standards. This definition has applicability to juvenile SpA axial disease classification imaging criterion when MRI is unavailable.

<p><strong>BACKGROUND: </strong>The objective of this work was to describe magnetic resonance imaging (MRI) changes over time in inflammatory and structural lesions at the sacroiliac joint (SIJ) in children with spondyloarthritis (SpA) exposed and unexposed to tumor necrosis factor inhibitor (TNFi).</p>

<p><strong>METHODS: </strong>This was a retrospective, multicenter study of SpA patients with suspected or confirmed sacroiliitis who underwent at ≥2 pelvic MRI scans. Images were reviewed independently by 3 radiologists and scored for inflammatory and structural changes using the Spondyloarthritis Research Consortium of Canada (SPARCC) SIJ inflammation score (SIS) and structural score (SSS). Longitudinal, quantitative changes in patient MRI scans were measured using descriptive statistics and stratified by TNFi exposure. We used an average treatment effects (ATE) regression model to explore the average effect of TNFi exposure over time on inflammatory and structural lesions, adjusting for baseline lesion scores.</p>

<p><strong>RESULTS: </strong>Forty-six subjects were evaluated using the SIS (n&nbsp;= 45) and SSS (n&nbsp;= 18). Median age at baseline imaging was 13.6 years, 63% were male and 71% were white. Twenty-three subjects (50%) were TNFi exposed between MRI studies. The median change in SIS in TNFi exposed and unexposed subjects with a baseline SIS ≥0 was - 20.7 and - 14.3, respectively (p&nbsp;= 0.09). Eleven (85%) TNFi exposed and 8 (89%) unexposed subjects with a baseline SIS ≥0 met the SIS minimal clinically important difference (MCID; ≥2.5). Using the ATE model adjusted for baseline SIS, the average effect of TNFi on SIS in patients with a baseline SIS ≥2 was - 14.5 (p&nbsp;&lt; 0.01). Unadjusted erosion change score was significantly worse in TNFi unexposed versus exposed subjects (p&nbsp;= 0.03) but in the ATE model the effect of TNFi was not significant.</p>

<p><strong>CONCLUSION: </strong>This study quantitatively describes how lesions in the SIJs on MRI change over time in patients exposed to TNFi versus unexposed. Follow-up imaging in TNFi exposed patients showed greater improvement than the unexposed group by most metrics, some of which reached statistical significance. Surprisingly, a majority of TNFi unexposed children with a baseline SIS≥2 met the SIS MCID. Additional studies assessing the short and long-term effects of TNFi on inflammatory and structural changes in juvenile SpA are needed.</p>

<p><strong>OBJECTIVE: </strong>To assess the feasibility of T2 mapping for evaluating pediatric SIJ cartilage at 3 Tesla (T) magnetic resonance imaging (MRI).</p>

<p><strong>METHODS: </strong>Healthy control subjects and adolescents with sacroiliitis underwent a 3T MRI dedicated pelvic protocol that included a T2 mapping sequence consisting of multislice, multiecho acquisition. Healthy control subjects were prospectively recruited from our primary care practices as part of a larger imaging study, whereas adolescents with sacroiliitis were recruited specifically for this study. Regions of interest (ROIs) were hand-drawn by a senior pediatric radiologist twice and a radiology fellow twice to calibrate and test reliability using the intraclass correlation coefficient (ICC). T2 relaxation time between control subjects and cases was compared using univariate linear regression. We tested the association of T2 relaxation time in adolescents with sacroiliitis with patient-reported outcomes and the Spondyloarthritis Research Consortium of Canada sacroiliac joint (SIJ) inflammation and structural scores using Pearson correlation coefficients.</p>

<p><strong>RESULTS: </strong>Fourteen subjects were evaluable (six control subjects: median age 13.7 years [interquartile range (IQR): 12.2-15.5], 67% male patients; eight cases: median age 17.4 years [IQR: 12.5-20], 88% male patients]. Acquisition time for T2 mapping sequences was approximately 6 minutes, and segmenting the ROI for each SIJ took approximately 3 minutes. The intrarater and inter-rater ICCs were 0.67 and 0.46, respectively, indicating good to fair reliability. There was a trend, albeit statistically insignificant, in longer median T2 relaxation time in cases (43.04 ms; IQR: 41.25-49.76 ms) versus healthy control subjects (40.0 ms; IQR: 38.9-48.6 ms). Although not statistically significant, cases with longer T2 relaxation time tended to occur with poorer patient-reported outcomes. Correlations with the SIJ inflammation and structural lesion scores were weak.</p>

<p><strong>CONCLUSION: </strong>T2 mapping of the SIJ cartilage in children was feasible and reliable. Larger controlled and longitudinal assessments are needed to assess the validity and utility of these measurements for routine clinical practice and trials.</p>

<p><strong>OBJECTIVE: </strong>To evaluate changes in the utilization of computed tomography angiography (CTA) for evaluating suspected pulmonary embolism (PE) and the positive rate of ancillary for those studies negative for PE in the last 13&nbsp;years.</p>

<p><strong>MATERIALS AND METHODS: </strong>A retrospective review of patient&nbsp;≤&nbsp;20&nbsp;years of age who underwent a chest CT angiography to rule out PE was performed in a 13-year-period. CT angiographies were grouped into three categories: Positive for PE, negative for PE and positive for ancillary findings, and negative for any pathology. From the exams with ancillary findings, we examined how many of these had a chest radiograph perform within 24&nbsp;h prior to the CTA and how many of them had an impression stating the same conclusion as the CTA.</p>

<p><strong>RESULTS: </strong>307 chest CT angiographies for suspected PE were included. 50 (16%) were reported as positive for PE and 91 (30%) were negative for PE but positive for ancillary findings. The most frequent ancillary findings were pneumonia (n = 26) and pleural effusion (n = 11). Out of 91, 73 patients had a previous chest radiograph and 28 of them reported a similar diagnosis than the CTA. The number of CT angiographies indicated for PE increased by 3.2 studies per year. The rate of CT angiographies positive for ancillary findings (slope = 1.5) and positive for PE (slope = 0.3) remained similar throughout the same period.</p>

<p><strong>CONCLUSIONS: </strong>CTA orders for PE have been increasing without any increased detection of PE or ancillary findings in children.</p>

<p><strong>Background</strong> MRI performed at 3.0 T offers greater signal-to-noise ratio and better spatial resolution than does MRI performed at 1.5 T; however, for fetal MRI, there are concerns about the potential for greater radiofrequency energy administered to the fetus at 3.0-T MRI. <strong>Purpose</strong> To compare the specific absorption rate (SAR) and specific energy dose (SED) of fetal MRI at 1.5 and 3.0 T. <strong>Materials and Methods</strong> In this retrospective study, all fetal MRI examinations performed with 1.5- and 3.0-T scanners at one institution between July 2012 and October 2016 were evaluated. Two-dimensional (2D) and three-dimensional (3D) steady-state free precession (SSFP), single-shot fast spin-echo, 2D and 3D T1-weighted spoiled gradient-echo (SPGR), and echo-planar imaging sequences were performed. SAR, SED, accumulated SED, and acquisition time were retrieved from the Digital Imaging and Communications in Medicine header. Data are presented as mean ± standard deviation. Two one-sided tests with equivalence bounds of 0.5 (Cohen effect size) were performed, with statistical equivalence considered at &lt; .05. <strong>Results</strong> A total of 2952 pregnant women were evaluated. Mean maternal age was 30 years ± 6 (age range, 12-49 years), mean gestational age was 24 weeks ± 6 (range, 17-40 weeks). A total of 3247 fetal MRI scans were included, with 2784 (86%) obtained at 1.5 T and 463 (14%) obtained at 3.0 T. In total, 93 764 sequences were performed, with 81 535 (87%) performed at 1.5 T and 12 229 (13%) performed at 3.0 T. When comparing 1.5- with 3.0-T MRI sequences, mean SAR (1.09 W/kg ± 0.69 vs 1.14 W/kg ± 0.61), mean SED (33 J/kg ± 27 vs 38 J/kg ± 26), and mean accumulated SED (965 J/kg ± 408 vs 996 J/kg ± 366, &lt; .001) were equivalent. <strong>Conclusion</strong> Fetal 1.5- and 3.0-T MRI examinations were found to have equivalent energy metrics in most cases. The 3.0-T sequences, such as two-dimensional T1-weighted spoiled gradient-echo and three-dimensional steady-state free precession, may require modification to keep the energy delivered to the patient as low as possible. © RSNA, 2020</p>

<p><strong>BACKGROUND: </strong>The SPARCC sacroiliac joint inflammation (SIS) and structural (SSS) scores are reliable measures to quantify abnormalities in the pediatric sacroiliac joint. We aimed to evaluate the utility of online calibration modules for the SIS and SSS and the reliability of their component change scores.</p>

<p><strong>METHODS: </strong>Change score reliability of 6 raters was assessed by overall and pairwise intraclass correlation coefficients (ICCs) before and after the use of real-time iterative calibration (RETIC) modules for both the SIS and SSS comprised of 20 adult cases. Acceptable ICC for change scores was &gt; 0.7 for SIS and &gt; 0.5 for all SSS components. Sensitivity to change was assessed by the standardized response mean (SRM).</p>

<p><strong>RESULTS: </strong>In scoring exercise 1, the SIS had acceptable reliability with a change score ICC of 0.80 and sclerosis was the only SSS lesion that met the acceptability threshold with a change score ICC of 0.52. After RETIC calibration, the SIS overall (ICC = 0.83) and mean pairwise (ICC = 0.83) change scores remained reliable with a large SRM (0.90). All SSS components except sclerosis met the overall and mean pairwise change score ICC acceptability thresholds-backfill: overall = 0.54, mean pairwise = 0.50; fat metaplasia: overall = 0.65, mean pairwise = 0.57; erosion: overall = 0.60, mean pairwise = 0.58; and ankylosis: overall = 0.96, mean pairwise = 0.96. The SSS RETIC module augmented the number of SSS components surpassing the acceptability threshold from 1 to 4. Sensitivity to change, as measured by the SRM, was large for erosion (0.96), moderate for backfill (0.55) and sclerosis (0.70), and small for fat metaplasia (0.36) and ankylosis (0.28).</p>

<p><strong>CONCLUSION: </strong>RETIC modules improved the overall reliability of SPARCC SIS and SSS change scores for previously calibrated raters. SIS recalibration was not as helpful to the most experienced raters who achieved high levels of agreement before recalibration. The SPARCC SIS and all SSS components except sclerosis are reliable measures to quantify change over time in children. A pediatric-specific RETIC tool should be developed to enhance the calibration of readers.</p>