Quantification of Kidney Fibrosis Using Ultrasonic Shear Wave Elastography
Experimental Study With a Rabbit Model
Objectives—The purpose of this study was to evaluate the feasibility of ultrasonic shear wave elastography for quantification of renal fibrosis in an experimental rabbit model.
Methods—Thirty-eight kidneys of 19 rabbits were studied and categorized into 3 groups: group I, ureter obstruction (n = 9); group II, renal vein occlusion (n = 10); and group III, normal control (n = 19). Before surgery, we measured stiffness at the renal cortex using shear wave elastography and evaluated the sonographic findings, including size, echogenicity, and resistive index. We repeated the same sonographic examinations weekly until the fourth week. The degree of histologically quantified fibrosis and the measured stiffness values were statistically compared.
Results—There was no significant difference in the mean stiffness values for the renal cortex in the 3 groups before surgery (8.95 kPa in group I, 9.06 kPa in group II, and 9.74 kPa in group III; P > .05). However, the mean stiffness in each group on the last sonographic examination was significantly different (10.91 kPa in group I, 13.92 kPa in group II, and 9.77 kPa in group III; P = .003). Pathologically, the degree of fibrosis was also significantly different (3.62% in group I, 11.70% in group II, and 0.70% in group III; P< .001). The fibrosis degree and stiffness were positively correlated (ρ = 0.568; P = 0.01).
Conclusions—Tissue stiffness measured by ultrasonic shear wave elastography was positively correlated with histopathologic renal fibrosis. Ultrasonic shear wave elastography may be used as a noninvasive tool for predicting renal fibrosis.
Value of Sonographic Bidirectional Arterial Flow Combined With Elastography for Diagnosis of Breast Imaging Reporting and Data System Category 4 Breast Masses
Objectives—The purpose of this study was to evaluate the role of bidirectional arterial flow combined with ultrasound elastography for differentiation of American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) category 4 masses.
Methods—A total of 116 BI-RADS category 4 breast masses were evaluated with color Doppler sonography, spectral analysis, and elastography. The sensitivity, specificity, accuracy, positive and negative predictive values, and receiver operator characteristic curve were used to estimate the diagnostic performance for each modality and the combination method.
Results—The combination method had the best sensitivity (81.1%) but less specificity (94.9%) and the best accuracy (90.5%). The discriminating power of the combined method (area under the curve [AUC], 0.880; 95% confidence interval [CI], 80.0%–96.0%) was significantly higher than that of bidirectional arterial flow (AUC, 0.818; 95% CI, 72.0%–91.6%; P< .01) and elastography (AUC, 0.765; 95% CI, 65.9%–87.0%; P< .01).
Conclusions—Bidirectional arterial flow evaluation, when combined with elastography, could potentially improve diagnostic accuracy for BI-RADS category 4 breast masses.
Differences in Liver Fibrosis Between Patients With Chronic Hepatitis B and C
Evaluation by Acoustic Radiation Force Impulse Measurements at 2 Locations
Objectives—The purpose of this study was to evaluate liver fibrosis by acoustic radiation force impulse (ARFI) measurements at 2 locations in patients with chronic hepatitis B and C.
Methods—A total of 204 consecutive patients (146 male and 58 female) with chronic hepatitis B (n = 121) and C (n = 83) who underwent liver biopsy were enrolled. All patients received ARFI measurements at 2 locations in the right intercostal space on the same day as biopsy.
Results—There was no difference in median ARFI values between detection locations. However, a significant difference was found for low and high values between locations (median ± SD, 1.38 ± 0.43 versus 1.56 ± 0.55 m/s; P < .001). By receiver operating characteristic (ROC) curve analysis for a METAVIR fibrosis score of F4 (cirrhosis), the lower value of 2 measurements had the highest area under the ROC curve (0.750), followed by the mean value (0.744) and the higher value (0.730). Patients with hepatitis C had a higher area under the ROC curve than patients with hepatitis B (0.824 versus 0.707) for predicting liver cirrhosis. By logistic regression analysis, ARFI was the best modality for predicting liver cirrhosis in hepatitis C, and conventional sonography was the best modality in hepatitis B (P < .001). The ARFI value in patients with hepatitis B was significantly influenced by liver inflammation (P = .019).
Conclusions—Acoustic radiation force impulse imaging is the modality of choice for predicting liver cirrhosis in chronic hepatitis C, whereas conventional sonography is still the modality of choice in chronic hepatitis B.
Implementation and Assessment of a Curriculum for Bedside Ultrasound Training
Objectives—This study assessed a curriculum for bedside ultrasound (US) and compared outcomes from 2 common training pathways.
Methods—The program consisted of e-learning paired with expert-led hands-on training administered to pulmonary/critical care and cardiology fellows with no prior formal training in bedside US. This “simulation-based learner” group completed a survey of attitudes and confidence before and after training, and knowledge and skills were assessed after training. The surveys and scores of the simulation-based learners were compared to the scores of “experts,” who were US-trained emergency physicians, and “apprentice learners,” who were intensivist physicians informally trained in bedside US on the job during fellowships.
Results—There was a significant difference in the self-reported level of prior training between the groups (simulation-based learners, 2.8; apprentice learners, 3.7; experts, 4.1, on a scale of 1–5 [P= .02]) but no difference in the interest level or perceived importance of bedside US. The study curriculum was successful, as shown by scores that exceeded the comparison groups in the cardiac and pulmonary courses (cardiac: simulation-based learners, 80%; apprentice learners, 73%; experts, 62% [P= .001]; pulmonary: 84%, 75%, and 72%, respectively [P =.02]). The simulation-based learners gained confidence in skills, whereas the comparison groups lost confidence after testing (P < .005); however, the simulation-based learners gained confidence in US subject areas that were not taught (abdomen [P <.002] and miscellaneous [P =.005]).
Conclusions—The simulation-based learner curriculum resulted in comparable or greater knowledge and confidence in each area of US versus the comparison groups. Findings of overgeneralization of confidence highlight the importance of quality assurance and supervision in bedside US training programs.
Impact of Accreditation Training for Residents on Sonographic Quality in Gynecologic Emergencies
Objectives—To assess the impact of an educational intervention based on an original accreditation training program on the quality of emergency sonography performed by obstetrics and gynecology (Ob/Gyn) residents.
Methods—We conducted a prospective before-after study on residents who performed bedside standardized sonographic examinations as first-line investigations in patients seen at our gynecologic emergency department. In both periods, the residents followed a 1-hour class taught by a board-certified Ob/Gyn sonography expert (opinion leader) and received a written standardized imaging protocol. An accreditation training process was implemented for the new residents at the beginning of the second period: 5 complete sonographic examinations were required for each resident, and facilitated feedback from the opinion leader was performed using a dedicated sonographic quality score. During both periods, all consecutive sonograms were collected and stored. The primary outcome was the sonographic quality score. A mixed model for repeated measures was used to compare scores in both periods from 20 consecutive sonographic examinations performed by 5 residents who were different in each period.
Results—The mixed model analysis showed an increase in quality scores in the post–accreditation training compared to the pre–accreditation training period (estimated coefficient ± SD, 4.13 ± 0.51; t = 8.16). The sonographic examination order also had a significant effect in both periods (estimated coefficient ± SD, 0.11 ± 0.03; t = 3.99).
Conclusions—An accreditation training process including facilitated feedback from a local opinion leader improved the quality of sonographic examinations performed by Ob/Gyn residents in women presenting to a gynecologic emergency department.