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BACKGROUND: Lack of standardization in CT protocol choice contributes to radiation dose variation. PURPOSE: To create a framework to assess radiation doses within broad CT categories defined according to body region and clinical imaging indication and to cluster indications according to the dose required for sufficient image quality. MATERIALS AND METHODS: This was a retrospective study using Digital Imaging and Communications in Medicine metadata. CT examinations in adults from January 1, 2016 to December 31, 2019 from the University of California San Francisco International CT Dose Registry were grouped into 19 categories according to body region and required radiation dose levels. Five body regions had a single dose range (ie, extremities, neck, thoracolumbar spine, combined chest and abdomen, and combined thoracolumbar spine). Five additional regions were subdivided according to dose. Head, chest, cardiac, and abdomen each had low, routine, and high dose categories; combined head and neck had routine and high dose categories. For each category, the median and 75th percentile (ie, diagnostic reference level [DRL]) were determined for dose-length product, and the variation in dose within categories versus across categories was calculated and compared using an analysis of variance. Relative median and DRL (95% CI) doses comparing high dose versus low dose categories were calculated. RESULTS: Among 4.5 million examinations, the median and DRL doses varied approximately 10 times between categories compared with between indications within categories. For head, chest, abdomen, and cardiac (3 266 546 examinations [72%]), the relative median doses were higher in examinations assigned to the high dose categories than in examinations assigned to the low dose categories, suggesting the assignment of indications to the broad categories is valid (head, 3.4-fold higher [95% CI: 3.4, 3.5]; chest, 9.6 [95% CI: 9.3, 10.0]; abdomen, 2.4 [95% CI: 2.4, 2.5]; and cardiac, 18.1 [95% CI: 17.7, 18.6]). Results were similar for DRL doses (all P < .001). CONCLUSION: Broad categories based on image quality requirements are a suitable framework for simplifying radiation dose assessment, according to expected variation between and within categories. © RSNA, 2021 See also the editorial by Mahesh in this issue.

This multidisciplinary consensus update aligns prior Society of Radiologists in Ultrasound (SRU) guidelines on simple adnexal cysts with recent large studies showing exceptionally low risk of cancer associated with simple adnexal cysts. Most small simple cysts do not require follow-up. For larger simple cysts or less well-characterized cysts, follow-up or second opinion US help to ensure that solid elements are not missed and are also useful for assessing growth of benign tumors. In postmenopausal women, reporting of simple cysts greater than 1 cm should be done to document their presence in the medical record, but such findings are common and follow-up is recommended only for simple cysts greater than 3-5 cm, with the higher 5-cm threshold reserved for simple cysts with excellent imaging characterization and documentation. For simple cysts in premenopausal women, these thresholds are 3 cm for reporting and greater than 5-7 cm for follow-up imaging. If a cyst is at least 10%-15% smaller at any time, then further follow-up is unnecessary. Stable simple cysts at initial follow-up may benefit from a follow-up at 2 years due to measurement variability that could mask growth. Simple cysts that grow are likely cystadenomas. If a previously suspected simple cyst demonstrates papillary projections or solid areas at follow-up, then the cyst should be described by using standardized terminology. These updated SRU consensus recommendations apply to asymptomatic patients and to those whose symptoms are not clearly attributable to the cyst. These recommendations can reassure physicians and patients regarding the benign nature of simple adnexal cysts after a diagnostic-quality US examination that allows for confident diagnosis of a simple cyst. Patients will benefit from less costly follow-up, less anxiety related to these simple cysts, and less surgery for benign lesions.

Purpose To determine if ultrasonographic (US) findings, including Doppler US findings, are associated with subsequent pancreas transplant failure. Materials and Methods A cohort of adult patients who underwent pancreas transplantation at a tertiary institution over the course of 10 years (from 2003 to 2012) was retrospectively evaluated for failure, which was defined as return to insulin therapy or surgical graft removal. The institutional review board provided a waiver of informed consent. All US images obtained within the 1st postoperative year were reviewed for three findings: arterial flow (presence or absence of intraparenchymal forward diastole flow), splenic vein thrombus, and edema. These findings were correlated with pancreas graft failure within 1-year after surgery by using Cox proportional hazards models and hazard ratios. Results A total of 228 transplants were included (mean patient age, 41.6 years; range, 19-57 years; 122 men, 106 women). Absent or reversed arterial diastolic flow was identified in nine of 20 failed transplants (sensitivity, 45%; 95% confidence interval [CI]: 23, 68) and in 15 of 208 transplants that survived (specificity, 93% [193 of 208]; 95% CI: 89, 96). The Cox proportional hazard ratio was 6.2 (95% CI: 3.1, 12.4). Splenic vein thrombus was identified in 10 of 20 failed transplants (sensitivity, 50%; 95% CI: 27, 73) and in 25 of 208 transplants that survived (specificity, 88% [183 of 208]; 95% CI: 83, 92). The Cox proportional hazard ratio was 4.2 (95% CI: 2.4, 7.4). Edema had the lowest specificity (Cox proportional hazard ratio, 2.0; 95% CI: 1.3, 2.9). In the multivariate analysis, only absent or reversed arterial diastolic flow remained significantly associated with transplant failure (adjusted hazard ratio, 3.6; 95% CI: 1.0, 12.8; P = .045). Conclusion Absent or reversed diastolic arterial Doppler flow has a stronger association with transplant failure than does splenic vein thrombus or edema. (©) RSNA, 2016.

PurposeTo summarize data on computed tomographic (CT) radiation doses collected from consecutive CT examinations performed at 12 facilities that can contribute to the creation of reference levels.Materials and methodsThe study was approved by the institutional review boards of the collaborating institutions and was compliant with HIPAA. Radiation dose metrics were prospectively and electronically collected from 199 656 consecutive CT examinations in 83 181 adults and 3871 consecutive CT examinations in 2609 children at the five University of California medical centers during 2013. The median volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose, along with the interquartile range (IQR), were calculated separately for adults and children and stratified according to anatomic region. Distributions for DLP and effective dose are reported for single-phase examinations, multiphase examinations, and all examinations.ResultsFor adults, the median CTDIvol was 50 mGy (IQR, 37-62 mGy) for the head, 12 mGy (IQR, 7-17 mGy) for the chest, and 12 mGy (IQR, 8-17 mGy) for the abdomen. The median DLPs for single-phase, multiphase, and all examinations, respectively, were as follows: head, 880 mGy · cm (IQR, 640-1120 mGy · cm), 1550 mGy · cm (IQR, 1150-2130 mGy · cm), and 960 mGy · cm (IQR, 690-1300 mGy · cm); chest, 420 mGy · cm (IQR, 260-610 mGy · cm), 880 mGy · cm (IQR, 570-1430 mGy · cm), and 550 mGy · cm (IQR 320-830 mGy · cm); and abdomen, 580 mGy · cm (IQR, 360-860 mGy · cm), 1220 mGy · cm (IQR, 850-1790 mGy · cm), and 960 mGy · cm (IQR, 600-1460 mGy · cm). Median effective doses for single-phase, multiphase, and all examinations, respectively, were as follows: head, 2 mSv (IQR, 1-3 mSv), 4 mSv (IQR, 3-8 mSv), and 2 mSv (IQR, 2-3 mSv); chest, 9 mSv (IQR, 5-13 mSv), 18 mSv (IQR, 12-29 mSv), and 11 mSv (IQR, 6-18 mSv); and abdomen, 10 mSv (IQR, 6-16 mSv), 22 mSv (IQR, 15-32 mSv), and 17 mSv (IQR, 11-26 mSv). In general, values for children were approximately 50% those for adults in the head and 25% those for adults in the chest and abdomen.ConclusionThese summary dose data provide a starting point for institutional evaluation of CT radiation doses.

To describe the timeliness of follow-up care in community-based settings among women who receive a recommendation for immediate follow-up during the screening mammography process and how follow-up timeliness varies according to facility and facility-level characteristics.This was an institutional review board-approved and HIPAA-compliant study. Screening mammograms obtained from 1996 to 2007 in women 40-80 years old in the Breast Cancer Surveillance Consortium were examined. Inclusion criteria were a recommendation for immediate follow-up at screening, or subsequent imaging, and observed follow-up within 180 days of the recommendation. Recommendations for additional imaging (AI) and biopsy or surgical consultation (BSC) were analyzed separately. The distribution of time to follow-up care was estimated by using the Kaplan-Meier estimator.Data were available on 214,897 AI recommendations from 118 facilities and 35,622 BSC recommendations from 101 facilities. The median time to subsequent follow-up care after recommendation was 14 days for AI and 16 days for BSC. Approximately 90% of AI follow-up and 81% of BSC follow-up occurred within 30 days. Facilities with higher recall rates tended to have longer AI follow-up times (P.001). Over the study period, BSC follow-up rates at 15 and 30 days improved (P.001). Follow-up times varied substantially across facilities. Timely follow-up was associated with larger volumes of the recommended procedures but not notably associated with facility type nor observed facility-level characteristics.Most patients with follow-up returned within 3 weeks of the recommendation.

To determine whether magnetic resonance (MR) imaging and MR spectroscopic imaging findings can improve predictions made with the Kattan nomogram for radiation therapy.The institutional review board approved this retrospective HIPAA-compliant study. Ninety-nine men who underwent endorectal MR and MR spectroscopy before external-beam radiation therapy for prostate cancer (January 1998 to June 2007) were included. Linear predictors were calculated with input variables from the study sample and the Kattan original coefficients. The linear predictor is a single weighted value that combines information of all predictor variables in a model, where the weight of each value is its association with the outcome. Two radiologists independently reviewed all MR images to determine extent of disease; a third independent reader resolved discrepancies. Biochemical failure was defined as a serum prostate-specific antigen level of 2 ng/mL (2 μg/L) or more above nadir. Cox proportional hazard models were used to determine the probabilities of treatment failure (biochemical failure) in 5 years. One model included only the Kattan nomogram data; the other also incorporated imaging findings. The discrimination performance of all models was determined with receiver operating characteristics (ROC) curve analyses. These analyses were followed by an assessment of net risk reclassification.The areas under the ROC curve for the Kattan nomogram and the model incorporating MR imaging findings were 61.1% (95% confidence interval: 58.1%, 64.0%) and 78.0% (95% confidence interval: 75.7%, 80.4%), respectively. Comparison of performance showed that the model with imaging findings performed significantly better than did the model with clinical variables alone (P.001). Overall, the addition of imaging findings led to an improvement in risk classification of about 28%, ranging from approximately a minimum of 16% to a maximum of 39%, depending on the risk change considered important.MR imaging data improve the prediction of biochemical failure with the Kattan nomogram after external-beam radiation therapy for prostate cancer. The number needed to image to improve the prediction of biochemical failure in one patient ranged from three to six.

Purpose: To evaluate the risk of cancer (positive predictive value [PPV]) associated with specific findings (mass, calcifications, architectural distortion, asymmetry) in mammographic examinations with abnormal results, to determine the distribution of these findings in examinations in which the patients received a diagnosis of cancer and examinations in which the patients did not, and to analyze PPV variation according to radiologist and patient factors. Materials and Methods: HIPAA-compliant institutional review board approval was obtained. PPV of mammographic findings was evaluated in a prospective cohort of 10 262 women who underwent 10 641 screening or diagnostic mammographic examinations with abnormal results between January 1998 and December 2002 in the San Francisco Mammography Registry. The cohort was linked with the Surveillance Epidemiology and End Results program to determine cancer status among these women. PPVs were calculated for each finding and were stratified according to patient characteristics, cancer type, and radiologist reader. Results: Cases of breast cancer (n = 1552) were identified (invasive, n = 1287; ductal carcinoma in situ, n = 270); in five, both kinds of breast cancer were recorded. Overall, of the number of interpretations, masses were most frequently noted in 56%, followed by calcifications in 29%, asymmetry in 12%, and architectural distortion in 4%. Masses, calcifications, architectural distortion, and developing asymmetry demonstrated similar PPVs in screening examinations (9.7%, 12.7%, 10.2%, and 7.4%, respectively), whereas one-view-only and focal asymmetry demonstrated lower PPVs (3.6% and 3.7%, respectively) and were a frequent reason for an abnormal result (42%). Overall, one (5%) in 20 invasive cancers was identified with asymmetry, one (6%) in 16 invasive cancers was identified with architectural distortion, one (21%) in five invasive cancers was identified with calcifications, and two (68%) in three invasive cancers were identified with a mass. Conclusion: Five percent of invasive cancers were identified with asymmetry, and asymmetry is more weakly associated with cancer in screening examinations than are mass, calcifications, and architectural distortion. © RSNA, 2009

Purpose: To retrospectively identify target recall rates for screening mammography on the basis of how sensitivity shifts with recall rate. Materials and Methods: The study group included 1 872 687 subsequent and 171 104 first screening mammograms from 1996 to 2001 from 172 and 139 facilities, respectively, in six sites of the Breast Cancer Surveillance Consortium. Institutional review board (IRB) approval was obtained from each site. Informed consent requirements of the IRBs were followed. The study was HIPAA compliant. Recall rate was defined as the percentage of screening studies for which further work-up was recommended by the radiologist. Sensitivity was defined as the proportion of cancers that were detected at screening mammography. Piecewise linear regression was used to model sensitivity as a function of recall rate. This model allows detection of critical recall rates in which significant changes (shifts) occurred in the rates that sensitivity increased with increasing recall rate. Rates were in...

To evaluate a range of performance parameters pertinent to the comprehensive auditing of diagnostic mammography examinations, and to derive performance benchmarks therefrom, by pooling data collected from large numbers of patients and radiologists that are likely to be representative of mammography practice in the United States.Institutional review board approval was met, informed consent was not required, and this study was Health Insurance Portability and Accountability Act compliant. Six mammography registries contributed data to the Breast Cancer Surveillance Consortium (BCSC), providing patient demographic and clinical information, mammogram interpretation data, and biopsy results from defined population-based catchment areas. The study involved 151 mammography facilities and 646 interpreting radiologists. The study population included women 18 years of age or older who underwent at least one diagnostic mammography examination between 1996 and 2001. Collected data were used to derive mean performance parameter values, including abnormal interpretation rate, positive predictive value (for abnormal interpretation, biopsy recommended, and biopsy performed), cancer diagnosis rate, invasive cancer size, and the percentages of minimal cancers, axillary node-negative invasive cancers, and stage 0 and I cancers. Additional benchmarks were derived for these performance parameters, including 10th, 25th, 50th (median), 75th, and 90th percentile values.The study involved 332,926 diagnostic mammography examinations. Mean performance parameter values were abnormal interpretation rate, 8.0%; positive predictive value for abnormal interpretation, 31.4%; positive predictive value for biopsy recommended, 31.5%; positive predictive value for biopsy performed, 39.5%; cancer diagnosis rate, 25.3 per 1000 examinations; invasive cancer size, 20.2 mm; percentage of minimal cancers, 42.0%; percentage of axillary node-negative invasive cancers, 73.6%; and percentage of stage 0 and I cancers, 62.4%.The presented BCSC outcomes data and performance benchmarks may be used by mammography facilities and individual radiologists to evaluate their own performance for diagnostic mammography as determined by means of periodic comprehensive audits.

To compare cancer yield for screening examinations with recommendation for short-interval follow-up after diagnostic imaging work-up versus after screening mammography only.From January 1996 to December 1999, Breast Imaging Reporting and Data System assessments and recommendations were collected prospectively for 1,171,792 screening examinations in 758,015 women aged 40-89 years at seven mammography registries in Breast Cancer Surveillance Consortium. Registries obtained waiver of signed consent or collected signed consent in accordance with institutional review boards at each location. Diagnosis of invasive cancer or ductal carcinoma in situ within 24 months of screening examination and tumor stage and size for invasive cancer were determined through linkage to pathology database or tumor registry. chi2 test was used to determine significant differences between groups.Overall, 5.2% of first and 1.7% of subsequent screens included recommendation for short-interval follow-up, which was similar to likelihood of recommendation for diagnostic evaluation (first screens, 4.6%; subsequent, 2.6%). Most recommendations for short-interval follow-up were based on screening mammography alone (86.2% of first screens, 77.5% of subsequent). Yield of cancer for screening examinations with probably benign finding (PBF) and recommendation for short-interval follow-up based on screening mammography alone tended to be lower than in those with PBF and recommendation for short-interval follow-up after additional work-up (first screens: 0.54% vs 0.96%, P=.10; subsequent: 1.50% vs 1.73%, P=.26). Proportion of stage II and higher disease tended to be higher for examinations with PBF and recommendation for short-interval follow-up based on screening mammography alone compared with those recommended for short-interval follow-up after additional work-up (first screens: 34.7% vs 24.4%, P=.43; subsequent: 27.5% vs 19.2%, P=.13).Many first screening examinations include recommendation for short-interval follow-up based on screening mammography alone. Cancer yield for these examinations is low and is lower than that with diagnostic work-up prior to short-interval follow-up recommendation. Absence of diagnostic work-up prior to short-interval follow-up recommendation may result in periodic surveillance of a high proportion of benign lesions.

To determine whether fetal growth measured at serial ultrasonographic (US) examinations can predict neonatal morbidity, independent of whether gestational age is known.Women (n = 321) who had singleton pregnancies and underwent two or more second- or third-trimester obstetric US examinations were included in a retrospective cohort analysis. Inadequate fetal growth was defined as growth at or below the 10th percentile. The relative risk of each poor outcome was calculated for fetuses with inadequate growth, compared with the risk for fetuses with normal growth.Inadequate fetal growth was associated with 3.9 times the risk of a birth weight less than 2,500 g, 17.7 times the risk of a birth weight less than the 3rd percentile for gestational age, 2.3 times the risk of preterm birth, 2.6 times the risk of a long newborn hospital stay, and 3.6 times the risk of neonatal intensive care unit admission. After adjusting for confounding variables, including fetal weight, fetal growth remained a significant predictor of small birth size and poor outcomes. Inadequate growth predicted the risk of poor outcomes, even when gestational age was unknown. When inadequate growth was used to identify fetuses at risk, 21%-67% of neonates who were small at birth or had poor outcomes were identified at false-positive rates of only 5%-9%. For all outcomes, inadequate growth enabled identification of more fetuses with poor birth outcomes than low estimated fetal weight.Morbidity is significantly increased among fetuses who demonstrate less than expected growth. Growth between two US examinations can be used to estimate the risk of neonatal morbidity, even when gestational age is unknown.

To investigate the clinical outcome in patients with a diagnosis of appendicitis at computed tomography (CT) in whom treatment is deemed unnecessary after clinical evaluation.After institutional review board approval, 2283 patients (856 men, 1427 women; mean age, 46 years; age range, 18-99 years) who underwent CT because they were suspected of having appendicitis between 2002 and 2007 were retrospectively identified. CT reports were reviewed, and the likelihood of appendicitis was assigned a score on a five-point scale: score 1, definitely absent; score 2, nonvisualized appendix with no secondary signs of inflammation; score 3, equivocal; score 4, probable; and score 5, definitely present. Diagnosis of appendicitis at CT was considered a false-positive result if the CT report was classified as probable or definite appendicitis but the patient was not treated within 4 days. Cases with false-positive results were reviewed by two readers blinded to patient outcome, supporting clinical data, and prospective scan interpretation, and a grade was assigned by using the same scale. Medical records were reviewed to determine outcomes. Descriptional statistics were used.Overall, 516 (23%) of 2283 patients had CT findings of probable or definite appendicitis. Thirteen (3%) of 516 patients did not receive immediate treatment for appendicitis. Of these, five (38%; 95% confidence interval: 18%, 65%) underwent later appendectomy with proved appendicitis after a mean interval of 118 days (range, 5-443 days). Seven (54%) of 13 patients never developed appendicitis across a mean follow-up of 583 days (range, 14-1460 days). One (8%) of 13 had a normal appendix at eventual surgery.Five of 13 patients with CT findings of appendicitis and reassuring clinical evaluation results in whom immediate treatment was deferred ultimately returned with appendicitis. In patients with CT results positive for appendicitis and benign or atypical clinical findings, a diagnosis of chronic or recurrent appendicitis may be considered.

To retrospectively identify target recall rates for screening mammography on the basis of how sensitivity shifts with recall rate.The study group included 1 872 687 subsequent and 171 104 first screening mammograms from 1996 to 2001 from 172 and 139 facilities, respectively, in six sites of the Breast Cancer Surveillance Consortium. Institutional review board (IRB) approval was obtained from each site. Informed consent requirements of the IRBs were followed. The study was HIPAA compliant. Recall rate was defined as the percentage of screening studies for which further work-up was recommended by the radiologist. Sensitivity was defined as the proportion of cancers that were detected at screening mammography. Piecewise linear regression was used to model sensitivity as a function of recall rate. This model allows detection of critical recall rates in which significant changes (shifts) occurred in the rates that sensitivity increased with increasing recall rate. Rates were interpreted as number of additional work-ups per additional cancer detected (AW/ACD) or, in other words, the estimated number of additional women needed to be recalled at a given rate to detect one additional cancer.For first mammograms, a single shift in the estimated AW/ACD rate occurred at a recall rate of 10.0%, with the rate jumping dramatically from 35 to 172. For subsequent mammograms, four shifts were identified. At a recall rate of 6.7%, the estimated AW/ACD increased from 80 to 132, which rendered it the highest desirable target recall rate. At a recall rate of 12.3%, the estimated AW/ACD was 304, which suggests little benefit for any higher recall rate.Recall rates of 10.0% for first and 6.7% for subsequent mammograms are recommended targets on the basis of their AW/ACD rates (less than 100).

Dual x-ray absorptiometry (DXA) was used to quantify breast density with a phantom and with cadaveric breasts. With DXA, percentage of fat correlated with percentage of glandular density of the phantom (r > 0.998) and with density at mammography (r(adjusted) = 0.83). DXA precision (SD) was 0.5% without and 1.1% with breast repositioning. DXA devices can be used to accurately and precisely estimate breast tissue density.