Faculty Bibliography

OBJECTIVE:To characterize the use and impact of radiation dose reduction techniques in actual practice for routine abdomen CT. METHODS:We retrospectively analyzed consecutive routine abdomen CT scans in adults from a large dose registry, contributed by 95 hospitals and imaging facilities. Grouping exams into deciles by, first, patient size, and second, size-adjusted dose length product (DLP), we summarized dose and technical parameters and estimated which parameters contributed most to between-protocols dose variation. Lastly, we modeled the total population dose if all protocols with mean size-adjusted DLP above 433 or 645 mGy-cm were reduced to these thresholds. RESULTS:2.9-fold, and phase 2.5-fold for patients in the highest versus lowest size-adjusted DLP decile. There was virtually no change in kV (kilovolt). Automatic exposure control was widely used to modulate mAs, whereas kV modulation was rare. Phase was the strongest driver of between-protocols variation. Broad adoption of optimized protocols could result in total population dose reductions of 18.6-40%. CONCLUSION/CONCLUSIONS:There are large variations in radiation doses for routine abdomen CT unrelated to patient size. Modification of kV and single-phase scanning could result in substantial dose reduction. CLINICAL RELEVANCE/CONCLUSIONS:Radiation dose-optimization techniques for routine abdomen CT are routinely under-utilized leading to higher doses than needed. Greater modification of technical parameters and number of phases could result in substantial reduction in radiation exposure to patients. KEY POINTS/CONCLUSIONS:• Based on an analysis of 748,846 routine abdomen CT scans in adults, radiation doses varied tremendously across patients of the same size and optimization techniques were routinely under-utilized. • The difference in observed dose was due to variation in technical parameters and phase count. Automatic exposure control was commonly used to modify effective mAs, whereas kV was rarely adjusted for patient size. Routine abdomen CT should be performed using a single phase, yet multi-phase was common. • kV modulation by patient size and restriction to a single phase for routine abdomen indications could result in substantial reduction in radiation doses using well-established dose optimization approaches.

The CT supply room is a critical resource in the imaging workflow. However, the supply room for the two CT scanners at our cancer center, one of which is used for our busy interventional service, was disorganized, and the time spent searching for the appropriate equipment could potentially lead to delays in service and contribute to patient safety risks. The purpose of this project was to reduce the time to find supplies and to increase the satisfaction of CT technologists and medical providers by reorganizing and clearly labeling supplies using "lean" principles. A multidisciplinary team was assembled to reorganize the CT storage using lean 5S methodology (sort, set in order, shine, standardize, and sustain). Baseline and postintervention analysis of the impact of supply reorganization and labeling was performed using three methods: (a) the time recorded for a supply retrieval scavenger hunt, (b) a spaghetti diagram of participant movement during the scavenger hunt, and (c) satisfaction surveys of radiologists and staff. Seven radiology residents participated in the timed supply retrieval scavenger hunt before and after the intervention. Spaghetti diagrams demonstrated a reduction in redundant foot traffic for supply retrieval after the intervention. There was a 61.7% decrease in the average time to retrieve the 10 items in the scavenger hunt (P < .01). Satisfaction surveys after the intervention had statistically significant positive responses compared with those before the intervention. ^©RSNA, 2024.

Background Accurate and precise methods to predict growth remain lacking. Diffusion tensor imaging (DTI) depicts the columnar structure of the physis and metaphyseal spongiosa and provides measures of tract volume and length that may help predict growth. Purpose To validate physeal DTI metrics as predictors of height velocity (1-year height gain from time of MRI examination) and total height gain (height gain from time of MRI examination until growth stops) and compare the prediction accuracy with bone age-based models. Materials and Methods Femoral DTI studies (b values = 0 and 600 sec/mm²; directions = 20) of healthy children who underwent MRI of the knee between February 2012 and December 2016 were retrospectively analyzed. Children with height measured at MRI and either 1 year later (height velocity) or after growth cessation (total height gain, mean = 34 months from MRI) were included. Physeal DTI tract volume and length were correlated with height velocity and total height gain. Multilinear regression was used to assess the potential of DTI metrics in the prediction of both parameters. Bland-Altman plots were used to compare root mean square error (RMSE) and bias in height prediction using DTI versus bone age methods. Results Eighty-nine children (mean age, 13 years ± 3 [SD]; 47 boys) had height velocity measured, and 70 (mean age, 14 years ± 1; 36 girls) had total height gain measured. Tract volumes correlated with height velocity (r

Purpose or Case Report: To assess variability in diffusion tensor imaging of the physis and metaphysis (DTI-P/M) of the distal femur between scanners, observers, tractography software, and resolution. Methods & Materials: We prospectively obtained DTI-P/M (20 directions, b values of 0 and 600 sec/mm2) in 11 healthy subjects (5 males, 6 females) ages 10-15 (mean 12.54) and quantified tract volume, tract length, and number of tracts in the distal femoral physis. Each subject was imaged in both GE and Siemens 3T units, and the sequence was performed twice in each session with voxel sizes of 2x2x3mm or 1x1x2mm and gap sizes of 0mm and 0.6 mm (22 studies). We compared interobserver variability (with two observers) using hand-drawn regions of interest in the distal femur physis between two tractography software, Trackvis (FACT algorithm) and DSI Studio (Euler algorithm), both with a 40o angular threshold. For DSI Studio, we set the tracking threshold to 0.1, length range to 0-200mm, and seed termination to 1000000. We compared tract number, length, and volume and fractional anisotropy, between the 22 studies using Spearman's correlation and Bland-Altman (BA) plots.
Result(s): Correlation between Siemens and GE was significant between Siemens with 2x2x3mm voxel size and 0.6mm gap with GE 1x1x2mm voxel size and 0mm gap (rho = 0.93, p<10^- 15). Bland-Altman plots normalizing for voxel size between Siemens and GE showed no bias in inter-scanner variability (bias -5.76, BA limits of agreement (LOA) -24.31 and 12.78), nor was there significant intrascanner variability between consecutive runs of either Siemens (bias 0.565, BA LOA -10.31 and 9.18) or GE (bias 0.309, BA LOA -2.08 and 2.69). The 95% confidence intervals for the inter-scan (Mean=1.109, 95%-CI [- 0.84 3.06]) and intra-scan (Mean=0.3, 95%-CI [-0.31 0.91]) both included zero confirming no significant bias between scanners (p<0.05). Trackvis, the current standard for DTI-P/M, had high interobserver agreement (rho = 0.95) whereas DSI Studio showed poor interobserver agreement (rho = 0.29).
Conclusion(s): DTI-P/M shows high GE and Siemens inter- and intra-scanner reproducibility and low variability. Trackvis has low interobserver variability for tractography generation

OB JECTIVES/UNASSIGNED:The European Society of Radiology identified 10 common indications for computed tomography (CT) as part of the European Study on Clinical Diagnostic Reference Levels (DRLs, EUCLID), to help standardize radiation doses. The objective of this study is to generate DRLs and median doses for these indications using data from the UCSF CT International Dose Registry. METHODS:) and dose-length product (DLP) were assessed for each EUCLID category (chronic sinusitis, stroke, cervical spine trauma, coronary calcium scoring, lung cancer, pulmonary embolism, coronary CT angiography, hepatocellular carcinoma (HCC), colic/abdominal pain, appendicitis), and US radiation doses were compared with European. RESULTS:The number of CT scans within EUCLID categories ranged from 8,933 (HCC) to over 1.2 million (stroke). There was greater variation in dose between categories than within categories (p < .001), and doses were significantly different between categories within anatomic areas. DRLs and median doses were assessed for all categories. DRLs were higher in the US for 9 of the 10 indications (except chronic sinusitis) than in Europe but with a significantly higher sample size in the US. CONCLUSIONS:and DLP for EUCLID clinical indications from diverse organizations were established and can contribute to dose optimization. These values were usually significantly higher in the US than in Europe. KEY POINTS/CONCLUSIONS:• Registry data were used to create benchmarks for 10 common indications for CT identified by the European Society of Radiology. • Observed US radiation doses were higher than European for 9 of 10 indications (except chronic sinusitis). • The presented diagnostic reference levels and median doses highlight potentially unnecessary variation in radiation dose.

OBJECTIVE:To examine the trends in CT utilization in the emergency department (ED) for different racial and ethnic groups, factors that may affect utilization, and the effects of increased insurance coverage since passage of the Affordable Care Act in 2010. MATERIALS AND METHODS/METHODS:Data from the National Hospital Ambulatory Medical Care Survey (NHAMCS) for the years 2009-2018 were used for the analysis. The NHAMCS is a cross-sectional survey which has random and systematical samples of more than 200,000 visits to over 250 hospital EDs in the USA. Patient demographic characteristics, source of payment/insurance, clinical presentation, and disposition from the ED were recorded. Descriptive statistics and multivariate logistic regression were performed. RESULTS:Between 2009 and 2018, the rate of uninsured patients in the ED decreased from 18.1% to as low as 9.9%, but this was not associated with a decrease in the disparity in CT utilization between non-Hispanic Black and non-Hispanic White patients. CT use rate increased 38% over the study period. Factors strongly associated with CT utilization include age, source of payment, triage category, disposition from the ED, and residence. After controlling for these factors, non-Hispanic White patients were 21% more likely to undergo CT than non-Hispanic Black patients, though no disparity was seen for Hispanic or Asian/other groups. CONCLUSION/CONCLUSIONS:Despite increased insurance coverage over the sample period, racial disparities between non-Hispanic Black and non-Hispanic White patients persist in CT utilization, though no disparity was seen for Hispanic or Asian/other patients. The source of this disparity remains unclear and is likely multifactorial.

RATIONALE AND OBJECTIVES/OBJECTIVE:The novel coronavirus (COVID-19) pandemic has presented many logistical challenges, including unprecedented shortages of personal protective equipment (PPE). A technique of obtaining portable chest radiographs (pCXR) through glass doors or windows to minimize technologist-patient contact and conserve PPE has gained popularity, but remains incompletely evaluated in the literature. Our goal was to quickly implement this technique and evaluate image quality and radiation dose. MATERIALS AND METHODS/METHODS:An infographic and video were developed to educate nurses and technologists on the through-glass pCXR technique. Imaging parameters were optimized using a phantom and scatter radiation was measured. Three reviewers independently evaluated 100 conventionally obtained and 100 through-glass pCXRs from March 13, 2020 to April 30, 2020 on patients with suspected COVID-19, using criteria for positioning and sharpness/contrast on a 1 (confident criteria not met) to 5 (confident criteria met) scale. Imaging parameters, including deviation index (DI) were recorded for all radiographs. RESULTS:The through-glass method was rapidly adopted and conserved one isolation gown per interaction. Although there was a statistically significant difference in the positioning (P value 0.018) and sharpness/contrast (P value 0.016), the difference in mean ratings was small: 4.82 vs 4.65 for positioning and 4.67 vs 4.50 (conventional vs modified) for sharpness/contrast. Scatter radiation was measured using a thorax phantom and found to be acceptable for the patient and nearby personnel. Standard deviation was higher for the DI for the through-glass technique (2.8) compared to the conventional technique (1.8), although the means were similar. CONCLUSION/CONCLUSIONS:The through-glass technique was quickly implemented, producing diagnostic quality chest radiographs while conserving PPE and reducing risks to radiology staff. There was more variability with imaging technique and DI using the through-glass technique, likely due to technologist uncertainty regarding technical modifications. Further work to reduce this variation is necessary to optimize quality and dose.

PURPOSE/OBJECTIVE:Assess feasibility of ultrashort echo time (UTE) T2* cartilage mapping in sacroiliac (SI) joints. METHODS:Prospective magnetic resonance imagings with UTE T2* cartilage maps obtained on 20 SI joints in 10 subjects. Each joint was segmented into thirds by 2 radiologists. The UTE T2* maps were analyzed; reliability and differences in UTE T2* values between radiologists were assessed. RESULTS:Mean UTE T2* value was 10.44 ± 0.60 ms. No difference between right/left SI joints (median, 10.52 vs 10.45 ms; P = 0.940), men/women (median, 10.34 vs. 10.57 ms; P = 0.174), or different anatomic regions (median range 10.55-10.69 ms; P = 0.805). Intraclass correlation coefficients were 0.94 to 0.99 (intraobserver) and 0.91 to 0.96 (interobserver). Mean bias ± standard deviation on Bland-Altman was -0.137 ± 0.196 ms (limits of agreement -0.521 and 0.247) without proportional bias (β = 0.148, P = 0.534). CONCLUSIONS:The UTE T2* cartilage mapping in the SI joints is feasible with high reader reliability.

OBJECTIVE:To assess the readability of patient-targeted online information on musculoskeletal radiology procedures. METHODS:Eleven common musculoskeletal radiology procedures were queried in three online search engines (Google, Yahoo!, Bing). All unique patient-targeted websites were identified (n = 384) from the first three pages of search results. The reading grade level of each website was calculated using 6 separate validated metrics for readability assessment. Analysis of word and sentence complexity was also performed. Results were compared between academic vs. non-academic websites and between websites found on different pages of the search results. Statistics were performed using a t test. RESULTS:The mean reading grade level across all procedures was 10th-14th grade. Webpages for nerve block were written at a higher reading grade level on non-academic websites (p = 0.025). There was no difference in reading grade levels between academic and non-academic sources for all other procedures. There was no difference in reading grade levels between websites found on the first page of search results compared with the second and third pages. Across all websites, 16-22% of the words used had 3+ syllables and 31-43% of the words used had 6+ characters (complex words); 13-24% of the sentences used had 22+ words (complex sentences). CONCLUSION/CONCLUSIONS:Patient-targeted online information on musculoskeletal radiology procedures are written at the 10th-14th grade reading level, which is well beyond the AMA and NIH recommendation. Readability can be lowered by decreasing text complexity through limitation of high-syllable words and reduction in word and sentence length.