Ultrasound-Derived Fat Fraction for Hepatic Steatosis Assessment: Prospective Study of Agreement With MRI PDFF and Sources of Variability in a Heterogeneous Population.

BACKGROUND. Metabolic dysfunction-associated steatotic liver disease is a growing global public health concern. Quantitative ultrasound measurements, such as ultrasound-derived fat fraction (UDFF), could provide noninvasive, cost-effective, and portable steatosis evaluation. OBJECTIVE. The purpose of this article was to evaluate utility of UDFF for steatosis assessment using proton density fat fraction (PDFF) as reference in patients undergoing liver MRI for heterogeneous indications and to assess UDFF variability. METHODS. This prospective study included a primary analysis of 187 patients (mean age, 53.8 years; 112 men, 75 women) who underwent 3-T liver MRI for any clinical indication from December 2020 to July 2021. Patients underwent investigational PDFF measurement, including determination of PDFFwhole-liver (mean PDFF of entire liver), and PDFFvoxel (PDFF in single voxel within right lobe, measured by MR spectroscopy), as well as investigational ultrasound with UDFF calculation (mean of five inter-costal measurements) within 1 hour after MRI. In a subanalysis, 21 of these patients underwent additional UDFF measurements 1, 3, and 5 hours after meal consumption. The study also included repeatability and reproducibility analysis of 30 patients (mean age, 26.3 years; 10 men, 20 women) who underwent clinical abdominal ultrasound between November 2022 and January 2023; in these patients, three operators sequentially performed UDFF measurements. RESULTS. In primary analysis, UDFF and PDFFwhole-liver measurements showed intra-class correlation coefficient (ICC) of 0.79. In Bland-Altman analysis, UDFF and PDFFvoxel measurements showed mean difference of 1.5% (95% CI, 0.6-2.4%), with 95% limits of agreement from -11.0% to 14.0%. UDFF measurements exhibited AUC for detecting PDFFvoxel at historic thresholds of 6.5% and greater, 17.4% and greater, and 22.1% and greater of 0.90, 0.95, and 0.95, respectively. In subanalysis, mean UDFF was not significantly different across time points with respect to meal consumption (p = .21). In repeatability and reproducibility analysis, ICC for intraoperator repeatability ranged from 0.98 to 0.99 and for interoperator reproducibility from 0.90 to 0.96. Visual assessment of patient-level data plots indicated increasing variability of mean UDFF measurements across operators and of intercostal measurements within individual patients with increasing steatosis. CONCLUSION. UDFF showed robust agreement with PDFF, diagnostic performance for steatosis grades, and intraoperator repeatability and interoperator reproducibility. Nonetheless, UDFF exhibited bias toward slightly larger values versus PDFF; intraoperator and interoperator variation increased with increasing steatosis. CLINICAL IMPACT. UDFF shows promise for steatosis assessment across diverse populations, although continued optimization remains warranted.

US Quantification of Liver Fat: Past, Present, and Future.

Fatty liver disease has a high and increasing prevalence worldwide, is associated with adverse cardiovascular events and higher long-term medical costs, and may lead to liver-related morbidity and mortality. There is an urgent need for accurate, reproducible, accessible, and noninvasive techniques appropriate for detecting and quantifying liver fat in the general population and for monitoring treatment response in at-risk patients. CT may play a potential role in opportunistic screening, and MRI proton-density fat fraction provides high accuracy for liver fat quantification; however, these imaging modalities may not be suited for widespread screening and surveillance, given the high global prevalence. US, a safe and widely available modality, is well positioned as a screening and surveillance tool. Although well-established qualitative signs of liver fat perform well in moderate and severe steatosis, these signs are less reliable for grading mild steatosis and are likely unreliable for detecting subtle changes over time. New and emerging quantitative biomarkers of liver fat, such as those based on standardized measurements of attenuation, backscatter, and speed of sound, hold promise. Evolving techniques such as multiparametric modeling, radiofrequency envelope analysis, and artificial intelligence-based tools are also on the horizon. The authors discuss the societal impact of fatty liver disease, summarize the current state of liver fat quantification with CT and MRI, and describe past, currently available, and potential future US-based techniques for evaluating liver fat. For each US-based technique, they describe the concept, measurement method, advantages, and limitations. © RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

The radiological approach to the carpal tunnel release - An anatomical pilot study.

Different techniques are available for carpal tunnel release such as classical surgical operations or minimally invasive procedures. A minimally invasive approach and the relevant regional anatomy are reported in this pilot study which was conducted with bodies from a body donation program. The method described here uses a hook knife to cut through the transverse carpal ligament or flexor retinaculum under ultrasound guidance. The results are documented by means of magnetic resonance and ultrasound imaging as well as by anatomical dissection.

Artifacts in Contrast-Enhanced Ultrasound during Follow-up after Endovascular Aortic Repair: Impact on Endoleak Detection in Comparison with Computed Tomography Angiography.

The study described here systematically analyzed how specific artifacts in contrast-enhanced ultrasound (CEUS) can affect the detection of endoleaks during follow-up after endovascular aortic repair (EVAR). Patients undergoing EVAR of atherosclerotic or mycotic abdominal aortic aneurysms using various standard and branched stent-graft material for visceral and iliac preservation were enrolled over 5 y and followed up with computed tomography angiography (CTA) and CEUS simultaneously. CEUS artifacts were frequently identified after EVAR procedures (59% of examinations) and were caused mainly by contrast agent, different prosthesis or embolization material and postinterventional changes in the aneurysm sac. This article describes how to identify important artifacts and how to avoid false-negative or false-positive interpretations of endoleaks. Despite artifacts, CEUS had higher sensitivity for endoleak detection after EVAR than CTA. CEUS was superior to CTA in the identification of late endoleaks type II and in follow-up examinations after embolization procedures, where beam-hardening artifacts limited CTA.

Segmental Testicular Infarction: Case Series and Literature Review of a Rare Diagnosis in Men with Acute Testicular Pain.

The incidence of segmental testicular infarction (STI) is very low. Such a disorder most often affects young men. The most common symptom is sudden testicular pain. We report 6 cases of men diagnosed with STI. Clinical examination, blood test, urine analysis, and ultrasound examination with colour Doppler were performed. Furthermore, tissue sonoelastography or MRI was performed in selected patients. All men underwent surgical exploration. In all but one man, the affected testis was preserved. Although STI is a rare condition, it should be taken into account if testicular pain prior to suspicious ultrasound imaging occurs. To be aware of this benign testicular pathology and its clinical and imaging features is important to avoid unnecessary orchiectomies in young patients.

Automated oscillometric blood pressure and pulse-wave acquisition for evaluation of vascular stiffness in atherosclerosis.

OBJECTIVE: Evaluation of diagnostic accuracy of an oscillometry-based device (VascAssist) combining fully automated ankle-brachial index (ABI) and pulse-wave velocity (PWV) assessment for detection of peripheral arterial disease (PAD). SUBJECTS AND METHODS: 110 consecutive subjects including symptomatic PAD patients (n = 41) and healthy PAD-free participants (n = 69) were recruited. All subjects underwent standard manual Doppler-based ABI (sABI) and oscillometry-based automated ABI (aABI) measurements (VascAssist). Oscillometry by the VascAssist included central and peripheral PWV assessment. Additionally, arterial stiffness (AS) was evaluated by flow-mediated vasodilation (FMD) of the brachial artery in all patients. All symptomatic PAD patients underwent catheter angiography for endovascular intervention and post-interventional acquisition of sABI, aABI, PWV and FMD. RESULTS: Sensitivity, specificity, PPV and NPV of aABI for detecting PAD was 73%, 100%, 100%, and 86% as compared to 80%, 96%, 92%, and 89% for sABI. Pearson-correlation for diabetics was r = 0.81; (P < .001) and for non-diabetics r = 0.77; (P < .001). Bland-Altman-analysis revealed a difference (95% CI) for diabetics of 0.09 (-0.22-0.4] and non-diabetics 0.022 [-0.25-0.295]. Weak correlation exists for FMD/AS analysis (pre-interventional R = 0.386, P = .043; post-interventional R = -0.06; P = .76) and significant increase of pre-/post-interventional PWV analysis (P < .001). CONCLUSION: Combined automatic ABI and PWV acquisition with the VascAssist device showed excellent diagnostic accuracy for detection of PAD. Compared to FMD, AS analysis may serve as an investigator-independent (screening) tool for determination of functional vascular damage in atherosclerosis.

Low-dose MDCT for surveillance of patients with severe homogeneous emphysema after bronchoscopic airway bypass.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of low-dose MDCT for radiologic monitoring of patients who have undergone placement of bronchial stents for airway bypass. SUBJECTS AND METHODS: In a prospective study, seven patients underwent MDCT according to a low-dose protocol (40 mAs, 120 kVp) before and after stent placement. The positions of the stents in the segmental bronchi were analyzed and compared with the bronchoscopic findings, which were reference standard. Patency versus lack of patency of stents was classified with five levels of confidence, and a definitive diagnosis was assigned to each stent. Prediction of stent dislodgment, follow-up findings, and complications occurring during the observation period were recorded. Consensus reading was performed by two radiologists. Statistical analysis was conducted by receiver operating characteristic analysis or four-field table. RESULTS: Seven patients underwent implantation of 37 stents (mean, 5 +/- 2 [SD] stents per patient; range, 2-8 stents). The area under the curve for differentiating patent from occluded stents was 0.995 with resulting sensitivity and specificity of 86.5% and 98.1%. The correct diagnosis of patency was established with MDCT for all but one stent (sensitivity, 94.7%; specificity, 100%). Sensitivity and specificity for prediction of dislodgment were 80% and 91%. Five stents were not identified during inspection bronchoscopy but were found in a regular position at MDCT. Three instances of minor bleeding and one of pneumothorax resolved spontaneously. The mean effective dose of the scan was 1.3 +/- 0.6 mSv. CONCLUSION: Low-dose MDCT is feasible for radiologic monitoring after airway bypass procedure.

Contrast enhanced harmonic ultrasound for differentiating breast tumors - first results.

PURPOSE: To investigate the extent to which indeterminate lesions of the breast can be differentiated in the early and late phase after bolus injection of the ultrasound contrast medium Optison. MATERIALS AND METHODS: Fifty female patients (mean age: 49 years) with a altogether 53 preoperatively impalpable indeterminate breast tumors, 20 fibroadenomas and 33 carcinomas, were examined by B-mode imaging and contrast medium-enhanced ultrasound with power Doppler (three patients had multifocal carcinomas). The tumors had a diameter of 5-15 mm (mean diameter: 9 mm). Histological confirmation was performed in all lesions by vacuum biopsies and/or surgical preparation. All examinations were performed with a multifrequency linear array probe (5-10 MHz, Logiq9 and Logiq 7, GE). Power Doppler (PD) and B-mode imaging as well as tissue harmonic imaging (THI) were employed. A bolus of 0.5 ml Optison was injected intravenously and spreading of the contrast enhancement and washout in the tumors were followed for at least 20 minutes. A low mechanical index was chosen to avoid early destruction of the microbubbles. Maximum tumor size was measured and tumors vessels were evaluated in digital cine ultrasound sequences. RESULTS: Without CM administration, 14 of 19 tumor lesions smaller than 10 mm could be distinguished better from the surrounding tissue with THI compared to fundamental B-mode imaging. Both benign (17/20) and malignant (30/33) tumors exhibited increased tumor marginal vessels or intratumoral vessels in the early phase after CM injection. A diffuse contrast medium accumulation was observed in the late phase (8-18 min, mean: 12 min) in 30 of 33 malignant tumors, but in none of the benign tumors. The diagnostic confirmation for this late enhancement was there with 90% for the malignant tumors. CONCLUSION: After intravenous bolus administration of Optison, breast carcinomas appear to have a prolonged diffuse enhancement of central tumor vasularity in the late phase compared to an earlier marginal vascularity of fibroadenomas.

Vascularization and perfusion of hepatocellular carcinoma: assessment with contrast-enhanced ultrasound using perflutren protein-type A microspheres.

PURPOSE: To assess the vascularization and the perfusion within hepatocellular carcinoma (HCC) including treatment-related changes with contrast-enhanced (CE) ultrasound (US). MATERIALS AND METHODS: Twenty-six biopsy-verified HCC lesions (size between 2.5-8 cm, median 3.8 cm) in 20 patients were examined with unenhanced and CE vascular US techniques immediately before selective angiography for transarterial chemoembolization (TACE) as well as immediately after TACE using all of the following modalities: color-coded Doppler sonography (CCDS), power Doppler imaging (PDI), CE pulse inversion harmonic imaging with PDI (PIHI+PDI), and CE coded harmonic angiography (CHA). In CE US studies, perflutren protein-type A microspheres were administered as contrast agent in a single 0.5 ml i.v. bolus diluted in 20 ml 0.9% NaCl. Selective arteriograms and CE computed tomographies were taken for reference purposes. The Wilcoxon test was used for statistical analysis. RESULTS: Intratumoral vessels could be visualized before TACE in 11/26 lesions (42%) with CCDS; in 15/26 (58%) with PDI; in 23/26 (88%) with CE CHA; in 26/26 (100%) with CE PIHI+PDI. Following TACE, the sensitivities were calculated as follows: CCDS 33%; PDI 55%; CE CHA 77%; and CE PIHI+PDI 100%. The corresponding negative predictive values were 74% for CCDS; 81% for PDI; 89% for CE CHA and 100% for CE PIHI+PDI. During the capillary phase, contrast enhancement could be observed in the CHA mode only. CONCLUSION: CE US by means of PIHI+PDI and CHA enables reliable visualization of residual tumor following TACE equivalent to that which is attained with angiography and Contrast Harmonic Imaging with Power Doppler, if perflutren microspheres are used as contrast agent in a single low-dose bolus.