Deep Learning for Pneumothorax Detection on Chest Radiograph: A Diagnostic Test Accuracy Systematic Review and Meta Analysis.

BACKGROUND: Pneumothorax is a common acute presentation in healthcare settings. A chest radiograph (CXR) is often necessary to make the diagnosis, and minimizing the time between presentation and diagnosis is critical to deliver optimal treatment. Deep learning (DL) algorithms have been developed to rapidly identify pathologic findings on various imaging modalities. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate the overall performance of studies utilizing DL algorithms to detect pneumothorax on CXR. METHODS: A study protocol was created and registered a priori (PROSPERO CRD42023391375). The search strategy included studies published up until January 10, 2023. Inclusion criteria were studies that used adult patients, utilized computer-aided detection of pneumothorax on CXR, dataset was evaluated by a qualified physician, and sufficient data was present to create a 2 × 2 contingency table. Risk of bias was assessed using the QUADAS-2 tool. Bivariate random effects meta-analyses and meta-regression modeling were performed. RESULTS: Twenty-three studies were selected, including 34 011 patients and 34 075 CXRs. The pooled sensitivity and specificity were 87% (95% confidence interval, 81%, 92%) and 95% (95% confidence interval, 92%, 97%), respectively. The study design, use of an institutional/public data set and risk of bias had no significant effect on the sensitivity and specificity of pneumothorax detection. CONCLUSIONS: The relatively high sensitivity and specificity of pneumothorax detection by deep-learning showcases the vast potential for implementation in clinical settings to both augment the workflow of radiologists and assist in more rapid diagnoses and subsequent patient treatment.

Percentage of Pancreatic Cysts on MRI With a Pancreatic Carcinoma: Systematic Review and Meta-Analysis.

BACKGROUND: Pancreatic cystic lesions (PCLs) are frequent on MRI and are thought to be associated with pancreatic adenocarcinoma (PDAC) necessitating long-term surveillance based on older studies suffering from selection bias. PURPOSE: To establish the percentage of patients with PCLs on MRI with a present or future PDAC. STUDY TYPE: Systematic review, meta-analysis. POPULATION: Adults with PCLs on MRI and a present or future diagnosis of PDAC were eligible. MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Scopus were searched to April 2022 (PROSPERO:CRD42022320502). Studies limited to PCLs not requiring surveillance, <100 patients, or those with a history/genetic risk of PDAC were excluded. FIELD STRENGTH/SEQUENCE: ≥1.5 T with ≥1 T2-weighted sequence. ASSESSMENT: Two investigators extracted data, with discrepancies resolved by a third. QUADAS-2 assessed bias. PDAC was diagnosed using a composite reference standard. STATISTICAL TESTS: A meta-analysis of proportions was performed at the patient-level with 95% confidence intervals (95% CI). RESULTS: Eight studies with 1289 patients contributed to the percentage of patients with a present diagnosis of PDAC, and 10 studies with 3422 patients to the percentage with a future diagnosis. Of patients with PCLs on MRI, 14.8% (95% CI 2.4-34.9) had a PDAC at initial MRI, which decreased to 6.0% (2.2-11.3) for studies at low risk of bias. For patients without PDAC on initial MRI, 2.0% (1.1-3.2) developed PDAC during surveillance, similar for low risk of bias studies at 1.9% (0.7-3.6), with no clear trend of increased PDAC for longer surveillance durations. For patients without worrisome features or high-risk stigmata, 0.9% (0.1-2.2) developed PDAC during surveillance. Of 10, eight studies had a median surveillance ≥3 years (range 3-157 months). Sources of bias included retrospectively limiting PCLs to those with histopathology and inconsistent surveillance protocols. DATA CONCLUSION: A low percentage of patients with PCLs on MRI develop PDAC while on surveillance. The first MRI revealing a PCL should be scrutinized for PDAC. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

Use of Enteric Contrast Material for Abdominopelvic CT in Penetrating Traumatic Injury in Adults: Comparison of Diagnostic Accuracy Systematic Review and Meta-Analysis.

BACKGROUND. Scarce evidence exists on the diagnostic benefit of enteric contrast administration for abdominopelvic CT performed in the setting of penetrating trauma. OBJECTIVE. The purpose of this systematic review and meta-analysis is to compare the diagnostic accuracy of CT using enteric contrast material with that of CT not using enteric contrast material in penetrating traumatic abdominopelvic injury in adults. EVIDENCE ACQUISITION. A protocol was registered a priori (PROSPERO CRD42019139613). MEDLINE and EMBASE databases were searched until June 25, 2019. Studies were included that evaluated the diagnostic accuracy of abdominopelvic CT either with or without enteric (oral and/or rectal) contrast material in patients presenting with penetrating traumatic injury. Relevant study data metrics and risk of bias were assessed. Bivariate random-effects meta-analyses and meta-regression modeling were performed to assess and compare diagnostic accuracies. EVIDENCE SYNTHESIS. From an initial sample of 829 studies, 12 studies were included that reported on 1287 patients with penetrating injury (389 with confirmed bowel, mesenteric, or other abdominopelvic organ injury). The enteric contrast material group (seven studies; 506 patients; 124 patients with confirmed penetrating injury) showed a sensitivity of 83.8% (95% CI, 73.7-90.5%) and specificity of 93.8% (95% CI, 83.6-97.8%). The group without enteric contrast administration (six studies; 781 patients; 265 patients with confirmed penetrating injury) showed a sensitivity of 93.0% (95% CI, 86.8-96.4%) and a specificity of 90.3% (95% CI, 81.4-95.2%). No statistically significant difference was identified for sensitivity (p = .07) or specificity (p = .37) between the groups with and without enteric contrast material according to meta-regression. Nine of 12 studies showed risk of bias in at least one QUADAS-2 domain (most frequently limited reporting of blinding of radiologists or lack of blinding of radiologists, insufficient clinical follow-up for the reference standard, and limited reporting of sampling methods). CONCLUSION. The use of enteric contrast material for CT does not provide a significant diagnostic benefit for penetrating traumatic injury. CLINICAL IMPACT. Eliminating enteric contrast administration for CT in penetrating traumatic injury can prevent delays in imaging and surgery and reduce cost.

MRI LI-RADS Version 2018: Impact of and Reduction in Ancillary Features.

OBJECTIVE. The purpose of this study is to determine the impact of LI-RADS ancillary features on MRI and to ascertain whether the number of ancillary features can be reduced without compromising LI-RADS accuracy. MATERIALS AND METHODS. A total of 222 liver observations in 81 consecutive patients were identified on MRI between August 2013 and December 2018. The presence or absence of major and ancillary features was used to determine the LI-RADS category for LR-1 to LR-5 observations. Final diagnosis was established on the basis of pathologic findings or one of several composite clinical reference standards. Diagnostic accuracy was compared with and without ancillary features by use of the z test of proportions. Decision tree analysis and machine learning-based feature pruning were used to identify noncontributory ancillary features for LI-RADS categorization. Interobserver agreement with and without ancillary features was measured using the Krippendorff alpha coefficient, and comparisons were made using bootstrapping. A p < .05 was considered statistically significant. RESULTS. Application of ancillary features resulted in a change in the LI-RADS category of seven hepatocellular carcinomas (HCCs), with the category of six of seven (86%) HCCs upgraded; 51 benign observations also had a change in LI-RADS category, with the category of 33 (65%) of these observations downgraded. When ancillary features were applied, the percentage of HCCs in each LI-RADS category did not differ significantly compared with major features alone (p = .06-.49). Decision tree analysis and the machine learning model identified five ancillary features as noncontributory: corona enhancement, nodule-in-nodule, mosaic architecture, blood products in mass, and fat in a mass, more than in adjacent liver. Interobserver agreement was high with and without application of ancillary features; however, it was significantly higher without ancillary features (p < .001). CONCLUSION. Although ancillary features are an important component of LI-RADS, their impact may be small. Several ancillary features likely can be removed from LI-RADS without compromising diagnostic performance.

Etiology of Burnout in Canadian Radiologists and Trainees.

PURPOSE: There is worsening of burnout symptoms experienced by radiologists and trainees. We explored potential factors that exacerbate burnout symptoms observed in the Canadian radiological community and currently available protective factors as next steps for establishing viable solutions for burnout. METHODS: An 11-question electronic survey was distributed to Canadian radiologists and trainees through the Canadian Association of Radiologists (CAR). Approval from a local ethics board and the CAR were obtained. The survey contained demographics-related questions as well as questions based on common risk factors for burnout. Qualitative and quantitative analyses were performed. RESULTS: The survey was distributed to 2200 CAR members, and a response rate of 23.3% was achieved. Most radiologists experienced frequent unexpected high workload with no statistically significant difference by the type of practice. Trainees experienced a statistically significantly (P < .0001) higher frequency of on-call shifts compared to staff radiologists. A statistically significant difference (P < .0001) was observed for perceived threats to career longevity dependent on length of career. Although support mechanisms for radiology were perceived as available, survey commentary suggested inefficiency in their usage and lack of prioritization, which was a trend observed across all types of practice. CONCLUSIONS: While there is awareness for radiology needs, changes are required at the workplace level to reduce burnout symptoms at their source. Communication between radiologists and hospital administration, as well as among radiology group members, is key to prioritize radiology needs in our imaging-driven era of health care.

Digital breast tomosynthesis for breast cancer detection: a diagnostic test accuracy systematic review and meta-analysis.

OBJECTIVES: No consensus exists on digital breast tomosynthesis (DBT) utilization for breast cancer detection. We performed a diagnostic test accuracy systematic review and meta-analysis comparing DBT, combined DBT and digital mammography (DM), and DM alone for breast cancer detection in average-risk women. METHODS: MEDLINE and EMBASE were searched until September 2018. Comparative design studies reporting on the diagnostic accuracy of DBT and/or DM for breast cancer detection were included. Demographic, methodologic, and diagnostic accuracy data were extracted. Risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool. Accuracy metrics were pooled using bivariate random-effects meta-analysis. The impact of multiple covariates was assessed using meta-regression. PROSPERO ID: CRD 42018111287. RESULTS: Thirty-eight studies reporting on 488,099 patients (13,923 with breast cancer) were included. Eleven studies were at low risk of bias. DBT alone, combined DBT and DM, and DM alone demonstrated sensitivities of 88% (95% confidence interval [CI] 83-92), 88% (CI 83-92), and 79% (CI 75-82), as well as specificities of 84% (CI 76-89), 81% (CI 73-88), and 79% (CI 71-85), respectively. The greater sensitivities of DBT alone and combined DBT and DM compared to DM alone were preserved in the combined meta-regression models accounting for other covariates (p = 0.003-0.006). No significant difference in diagnostic accuracy between DBT alone and combined DBT and DM was identified (p = 0.175-0.581). CONCLUSIONS: DBT is more sensitive than DM, while the addition of DM to DBT provides no additional diagnostic benefit. Consideration of these findings in breast cancer imaging guidelines is recommended. KEY POINTS: • Digital breast tomosynthesis with or without additional digital mammography is more sensitive in detecting breast cancer than digital mammography alone in women at average risk for breast cancer. • The addition of digital mammography to digital breast tomosynthesis provides no additional diagnostic benefit in detecting breast cancer compared to digital breast tomosynthesis alone. • The specificity of digital breast tomosynthesis with or without additional digital mammography is no different than digital mammography alone in the detection of breast cancer.

Predictors of Citation Rate for Original Research Studies in the Canadian Association of Radiologists Journal.

OBJECTIVE: This study is aimed to identify predictors of citation rate of original research published in the Canadian Association of Radiologists Journal (CARJ). METHODS: A search of MEDLINE was conducted from January 1, 2000-June 30, 2013 to identify all studies published in the CARJ. Original research studies were included. Reviews, pictorial essays, guidelines, case studies, case series, and original studies with a sample size <10 were excluded. Variables assessed for association with citation rate included number of authors, study design, sample size, multi-institutional study, multi-national study, study type, presence of statistically significant result, presence of funding, and number of references. Statistical analysis was completed using linear regression and Pearson correlation coefficients (r). RESULTS: A total of 714 studies were published in CARJ, of which 181 were original research publications that were cited a total of 1517 times. Twelve original research studies were uncited, while the most-cited one was cited 58 times. Sample size (r = 0.177, P = .017) and number of references (r = 0.164, P = .028) demonstrated statistically significant weak positive correlations with citation rate. Number of authors, study design, setting, statistically significant results, and funding were not associated with citation rate. CONCLUSION: Only a very small number of original research studies published at the CARJ remained uncited 5 or more years after the publication. Sample size and number of references were identified as significant, but weak predictors of citation rate in CARJ.

Prevalence of Burnout Among Canadian Radiologists and Radiology Trainees.

PURPOSE: Physician burnout is on the rise compared to the average population, and radiology burnout rates are ranked high compared to other specialties. We aim to assess radiologist and radiology trainee burnout in Canada. METHODS: A survey using the abbreviated 7-item Maslach Burnout Inventory that characterizes burnout symptoms into personal accomplishment, emotional exhaustion, and depersonalization was sent to all eligible members of the Canadian Association of Radiologists in January 2018. The anonymous survey was hosted on SurveyMonkey for 1 month. A reminder e-mail was sent halfway through the survey period. RESULTS: Overall, 262 of 1401 invited radiology trainees and radiologists completed the survey (response rate 18.7%). With regards to personal accomplishment, we observed that (1) burnout in this domain improved with increased years worked and (2) milder symptoms were observed in community radiologists compared with their academic counterparts. In comparison with other studies of radiologist burnout, we found mild burnout symptoms in personal accomplishment, but severe symptoms in the burnout domains of both emotional exhaustion and depersonalization. CONCLUSIONS: Canadian radiologists and radiology trainees reported above average burnout symptoms with regard to both emotional exhaustion and depersonalization. Future research directions include exploring etiologies of burnout and implementation of treatment strategies based on these identified problem areas.

Pulmonary Imaging Biomarkers of Gas Trapping and Emphysema in COPD: (3)He MR Imaging and CT Parametric Response Maps.

PURPOSE: To directly compare magnetic resonance (MR) imaging and computed tomography (CT) parametric response map (PRM) measurements of gas trapping and emphysema in ex-smokers both with and without chronic obstructive pulmonary disease (COPD). MATERIALS AND METHODS: Participants provided written informed consent to a protocol that was approved by a local research ethics board and Health Canada and was compliant with the HIPAA (Institutional Review Board Reg. #00000940). The prospectively planned study was performed from March 2014 to December 2014 and included 58 ex-smokers (mean age, 73 years ± 9) with (n = 32; mean age, 74 years ± 7) and without (n = 26; mean age, 70 years ± 11) COPD. MR imaging (at functional residual capacity plus 1 L), CT (at full inspiration and expiration), and spirometry or plethysmography were performed during a 2-hour visit to generate ventilation defect percent (VDP), apparent diffusion coefficient (ADC), and PRM gas trapping and emphysema measurements. The relationships between pulmonary function and imaging measurements were determined with analysis of variance (ANOVA), Holm-Bonferroni corrected Pearson correlations, multivariate regression modeling, and the spatial overlap coefficient (SOC). RESULTS: VDP, ADC, and PRM gas trapping and emphysema (ANOVA, P < .001) measurements were significantly different in healthy ex-smokers than they were in ex-smokers with COPD. In all ex-smokers, VDP was correlated with PRM gas trapping (r = 0.58, P < .001) and with PRM emphysema (r = 0.68, P < .001). VDP was also significantly correlated with PRM in ex-smokers with COPD (gas trapping: r = 0.47 and P = .03; emphysema: r = 0.62 and P < .001) but not in healthy ex-smokers. In a multivariate model that predicted PRM gas trapping, the forced expiratory volume in 1 second normalized to the forced vital capacity (standardized coefficients [ßS] = -0.69, P = .001) and airway wall area percent (ßS = -0.22, P = .02) were significant predictors. PRM emphysema was predicted by the diffusing capacity for carbon monoxide (ßS = -0.29, P = .03) and VDP (ßS = 0.41, P = .001). Helium 3 ADC values were significantly elevated in PRM gas-trapping regions (P < .001). The spatial relationship for ventilation defects was significantly greater with PRM gas trapping than with PRM emphysema in patients with mild (for gas trapping, SOC = 36% ± 28; for emphysema, SOC = 1% ± 2; P = .001) and moderate (for gas trapping, SOC = 34% ± 28; for emphysema, SOC = 7% ± 15; P = .006) COPD. For severe COPD, the spatial relationship for ventilation defects with PRM emphysema (SOC = 64% ± 30) was significantly greater than that for PRM gas trapping (SOC = 36% ± 18; P = .01). CONCLUSION: In all ex-smokers, ADC values were significantly elevated in regions of PRM gas trapping, and VDP was quantitatively and spatially related to both PRM gas trapping and PRM emphysema. In patients with mild to moderate COPD, VDP was related to PRM gas trapping, whereas in patients with severe COPD, VDP correlated with both PRM gas trapping and PRM emphysema.

Performance of Digital Breast Tomosynthesis, Synthetic Mammography, and Digital Mammography in Breast Cancer Screening: A Systematic Review and Meta-Analysis.

BACKGROUND: Our objective was to perform a systematic review and meta-analysis comparing the breast cancer detection rate (CDR), invasive CDR, recall rate, and positive predictive value 1 (PPV1) of digital mammography (DM) alone, combined digital breast tomosynthesis (DBT) and DM, combined DBT and synthetic 2-dimensional mammography (S2D), and DBT alone. METHODS: MEDLINE and Embase were searched until April 2020 to identify comparative design studies reporting on patients undergoing routine breast cancer screening. Random effects model proportional meta-analyses estimated CDR, invasive CDR, recall rate, and PPV1. Meta-regression modeling was used to compare imaging modalities. All statistical tests were 2-sided. RESULTS: Forty-two studies reporting on 2 606 296 patients (13 003 breast cancer cases) were included. CDR was highest in combined DBT and DM (6.36 per 1000 screened, 95% confidence interval [CI] = 5.62 to 7.14, P < .001), and combined DBT and S2D (7.40 per 1000 screened, 95% CI = 6.49 to 8.37, P < .001) compared with DM alone (4.68 per 1000 screened, 95% CI = 4.28 to 5.11). Invasive CDR was highest in combined DBT and DM (4.53 per 1000 screened, 95% CI = 3.97 to 5.12, P = .003) and combined DBT and S2D (5.68 per 1000 screened, 95% CI = 4.43 to 7.09, P < .001) compared with DM alone (3.42 per 1000 screened, 95% CI = 3.02 to 3.83). Recall rate was lowest in combined DBT and S2D (42.3 per 1000 screened, 95% CI = 37.4 to 60.4, P<.001). PPV1 was highest in combined DBT and DM (10.0%, 95% CI = 8.0% to 12.0%, P = .004), and combined DBT and S2D (16.0%, 95% CI = 10.0% to 23.0%, P < .001), whereas no difference was detected for DBT alone (7.0%, 95% CI = 6.0% to 8.0%, P = .75) compared with DM alone (7.0%, 95.0% CI = 5.0% to 8.0%). CONCLUSIONS: Our findings provide evidence on key performance metrics for DM, DBT alone, combined DBT and DM, and combined DBT and S2D, which may inform optimal application of these modalities for breast cancer screening.

Factors Affecting Response Rates in Medical Imaging Survey Studies.

RATIONALE AND OBJECTIVE: To review response rates published in medical imaging journals, and to analyze potential factors which contributed to a low response rate. MATERIALS AND METHODS: A literature search was performed in MEDLINE and Embase to identify and assess published medical imaging survey studies. Variables assessed were response rate, incentives such as reminders and remuneration, and rationales provided for a potential low response rate. Statistical significance was calculated using unpaired t tests, ANOVA, Mann-Whitney, and Kruskal-Wallis tests. RESULTS: Three hundred and fifty-six unique surveys were included for analysis. The mean survey response rate in the current age of predominately electronic surveys was 45%. Factors which statistically significantly demonstrated a difference in response rate were survey location (European countries: 52%, Canada: 47%, United States: 42%; p < 0.05), survey topic (musculoskeletal: 69%, nuclear medicine: 64%, and education: 47%; p < 0.05), survey delivery method (telephone: 76%, email: 41%; p < 0.0001), and survey question type (short answer: 62%, multiple choice: 43%; p < 0.01). Statistically significant linear correlations were observed between the response rate compared to the number of reminders sent (r = 0.27; p < 0.01) and the number of participants (r = -0.26; p < 0.0001). CONCLUSION: The survey response rate serves as a surrogate marker for nonresponse bias. Survey response controlled for intrinsic nonadjustable characteristics offer achievable research goals. Adjustable factors to low response, including survey delivery method, question type, and number of reminders demonstrated statistical difference in response rate, and can be utilized by researchers to prospectively minimize nonresponse bias.

Beyond Universal Health Care: Barriers to Breast Cancer Screening Participation in Canada.

PURPOSE: Despite well-established preventive screening guidelines for breast cancer, screening rates do not meet targets in both the United States and Canada. Although access to preventive care is an important factor toward participation, breast cancer screening rates in Canada vary despite a universal health care system. The objective of this study is to understand features within the Canadian population that potentiate screening disparities through a systematic review of the literature. METHODS: A search of MEDLINE and Embase was performed to identify relevant studies published from 2005 onward. Titles and abstracts were screened, followed by full-text screening. Inclusion criteria were defined as studies reporting on disparities in image-based screening for breast cancer. RESULTS: Three hundred twenty-four studies were retrieved, from which 29 studies were selected on the basis of the predetermined inclusion criteria. Population groups identified at risk for low image-based screening participation included those of low socioeconomic status, individuals with comorbidities, new immigrants and refugees, those in remote geographic locations, individuals with intellectual or developmental disabilities, and ethnocultural minorities. Barriers to image-based screening can be improved by targeting measures specific to these at-risk groups at the individual, organization, and policy levels. CONCLUSIONS: Multiple at-risk population groups exist for preventive cancer screening within a universal health care system. By understanding specific characteristics within these vulnerable populations, effective intervention strategies can be established to improve breast cancer preventive care.

Breast Cancer Screening in High-Risk Patients during Pregnancy and Breastfeeding: A Systematic Review of the Literature.

There are currently no clear guidelines for high-risk breast cancer screening during the pregnancy and breastfeeding periods. The objective of this systematic review (SR) was to assess the available evidence pertaining to breast cancer screening recommendations in this population with the aim of supporting future guidelines. We performed a SR of the literature using the electronic databases MEDLINE and Embase. Predetermined inclusion and exclusion criteria were used during the abstract screening and full-text data extraction phases. We retrieved 2,274 abstracts after removal of duplicates, from which 16 studies were included based on predetermined eligibility criteria. Most of the studies found were narrative reviews and expert opinions. Clinical breast exam (CBE) was recommended by 12 studies during pregnancy and by 6 studies in the breastfeeding period. Mammography was recommended in the breastfeeding period by 2 studies. Magnetic resonance imaging was recommended in the breastfeeding period by 2 studies. Ultrasound was considered not appropriate for screening in this population. The information extracted from this SR is based primarily on expert opinion and anecdotal evidence, which explains the lack of standardized guidelines for high-risk breast cancer screening in this population. However, expert opinion may be a surrogate outcome for high-risk breast cancer screening recommendations in this subset of patients, and as such, may justify the clinical management to be tailored accordingly. This SR summarizes the evidence pertaining to high-risk breast cancer screening during pregnancy and breastfeeding, which could serve as a catalyst for future research on the topic.

Second-order Texture Measurements of (3)He Ventilation MRI: Proof-of-concept Evaluation of Asthma Bronchodilator Response.

RATIONALE AND OBJECTIVES: (3)He magnetic resonance imaging (MRI) can be used to quantify functional responses to asthma therapy and provocation. Ventilation imaging offers quantitative information beyond ventilation defects that have not yet been exploited. Therefore, our objective was to evaluate hyperpolarized (3)He MRI ventilation defect percent (VDP) and compare this and pulmonary function measurements to ventilation image texture features and their changes post-bronchodilator administration in patients with asthma. MATERIALS AND METHODS: Volunteers with a diagnosis of asthma provided written informed consent to an ethics board-approved protocol and underwent pulmonary function tests and MRI before and after salbutamol inhalation. MR images were analyzed using VDP, and their texture was evaluated via gray-level run-length matrices. These texture classifiers were compared to VDP in responders to bronchodilation based on VDP (VDP responders) and forced expiratory volume in 1 s (FEV1) (FEV1 responders). RESULTS: In total, 47 patients with asthma (18 males 39 ± 13 years, FEV1 = 79 ± 21%) reported significantly improved FEV1, FEV1/forced vital capacity (FVC), residual volume (RV)/total lung capacity (TLC) (all P = .0001) and VDP (P = .01) post-salbutamol. Post-salbutamol, VDP responders and nonresponders to salbutamol were significantly different for coarse-texture features including long-run emphasis (LRE) and long-run, low gray-level emphasis (LRLGE, both P < .05) and for FEV1 responders to salbutamol, there was significantly different long-run, high gray-level emphasis (LRHGE, P = .04). There were significant relationships for VDP with LRE (R = .50, P = .0003), LRLGE (R = .34, P = .02), and LRHGE (R = .56, P = .0001). Receiver operating characteristic curves showed VDP with the strongest performance (AUC = .92), followed by coarse-texture classifier LRHGE (AUC = .83), FEV1 (AUC = .80), LRE (AUC = .66), FVC (AUC = .58), and LRLGE (AUC = .42). CONCLUSIONS: In patients with asthma, differences in ventilation patchiness post-salbutamol can be quantified using coarse-texture classifiers that are significantly different in bronchodilator responders.