Abdominal Imaging
Original Research
Comparison of Super-Resolution US and Contrast Material–enhanced US in Detection of the Spoke Wheel Sign in Patients with Focal Nodular Hyperplasia.
Kang TW, Jeong WK, Kim Y-Y, et al.
Radiology. 2021;298(1):82-90.
doi:10.1148/radiol.2020200885.
- Background: The diagnosis of focal nodular hyperplasia (FNH) by US usually requires use of contrast material, although the effect of using the super-resolution US technique in diagnosing FNH is not known.
- Question: Can super-resolution US detect the spoke wheel sign in patients with FNH?
- Inclusion: Patients diagnosed with FNH between May 2016 and March 2019 in a prospective trial were included.
- Design: This is a secondary analysis of patients with FNH who underwent both super-resolution US and contrast-enhanced US with perfluorobutane microbubbles. Two radiologists used a four-point scale to score their confidence in the presence of the spoke wheel sign based on super-resolution US and contrast-enhanced US findings. Interobserver agreement was analyzed using the intraclass correlation coefficient.
- Results: 62 patients with FNH were included, and most of the patients showed the spoke wheel sign on both super-resolution US and contrast-enhanced US (63% and 71%, respectively). There was no significant difference in the confidence score for the spoke wheel sign between the two techniques. The interobserver agreement of super-resolution US was higher than that of contrast-enhanced US for the spoke wheel sign (0.82 vs 0.58).
- Conclusion: Super-resolution US provided a similar rate of detection of the spoke wheel sign in patients with FNH compared to contrast-enhanced US. In clinical practice, this can reduce the need for contrast agents.
Review
O-RADS Ultrasound: A User’s Guide, From the AJR Special Series on Radiology Reporting and Data Systems.
Strachowski LM, Jha P, Chawla TP, et al.
American Journal of Roentgenology. 2020.
doi:10.2214/ajr.20.25064.
- Overview: This article reviews the Ovarian/Adnexal Reporting and Data System (O-RADS) lexicon utilized with US and MRI. Since most ovarian or adnexal lesions are first detected on US, O-RADS US serves as the primary assessment tool. Reporting relevant imaging features allows for risk stratification of these lesions in order to optimally guide patient management. The ACR color-coded risk stratification scorecard and O-RADS US calculator are available to expedite O-RADS categorization and management determination.
Original Research
Contrast-enhanced ultrasonography to evaluate risk factors for short-term and long-term outcomes after liver transplantation: A pilot prospective study.
Zheng B-W, Zhang H-J, Gu S-J, et al.
European Journal of Radiology.
2021;135:109475.
doi:10.1016/j.ejrad.2020.109475.
- Background: Liver transplantations can be categorized by donation after brain death (DBD), cardiac death (DCD), and brain death pursued by circulatory death (DBCD). With the increase in deceased donors, US can serve as an imaging modality to monitor donor liver perfusion in the intensive care unit (ICU).
- Question: Can contrast-enhanced US help identify donor livers at risk of developing short-term primary graft dysfunction (PGD) and arterial and biliary complications within 1 year?
- Inclusion: DBD and DCD donors were identified prior to surgical procurement from February 2016 and June 2018. DBD and DCD donors underwent US/contrast-enhanced US exam within 24 hours of surgical procurement, and the whole liver transplant should be received by the corresponding recipient.
- Design: This prospective study evaluated the US and contrast-enhanced US images of each donor liver. Two radiologists who were blinded to all clinical information analyzed the images independently. Potential risk factors for PGD and complications at 1 year were collected.
- Results: In the short-term, 20 out of 52 eligible donor livers (38.5%) developed PGD. Decreased enhancement of donor livers on contrast-enhanced US is associated with PGD. For long-term complications, 16 out of 48 donor livers (33.3%) developed arterial or biliary complications within 1 year; there were no independent factors associated with these complications.
- Conclusion: Decrease in enhancement of donor livers on contrast-enhanced US before transplant is an independent risk factor for poor short-term outcomes of liver transplantation.
Original Research
Microcystic pattern and shadowing are independent predictors of ovarian borderline tumors and cystadenofibromas in ultrasound.
Zheng X, Lyu G, Gan Y, et al.
European Radiology. 2020;31(1):45-54.
doi:10.1007/s00330-020-07113-z.
- Background: US features of borderline tumors (BoTs) and cystadenofibromas (CAFs) are complex and often overlap with malignancy. Distinguishing these tumors from malignant tumors on US can help guide surgical management.
- Question: What are the differentiating US characteristics of BoTs and CAFs?
- Inclusion: Patients who have at least one primary epithelial tumor in the adnexa between July 2015 and July 2019 were included.
- Design: This retrospective study reviewed preoperative US findings in patients with at least one primary epithelial tumor in the adnexa. Multinomial logistic regression after univariate analysis was done on various US features.
- Results: A total of 650 patients were included in this study. Of these, 110 had CAF, 128 had BoT, 239 had cystadenoma (CAD), and 162 had cystadenocarcinoma (CAC). 59.1% of CAFs exhibited acoustic shadow, which was significantly more than CADs, BoTs, and CACs. 53.1% of BoTs demonstrated microcystic pattern (MCP), which was significantly more than CADs, CACs, and CAFs. Logistic regression analysis showed that shadowing is an independent predictor of CAFs, while MCP is an independent predictor of BoTs.
- Conclusion: Acoustic shadows and MCP were independent predictors of CAFs and BoTs, respectively.
Original Research
The utility of an under-distended gallbladder on ultrasound in ruling out acute cholecystitis.
Shaish H, Ma HY, Ahmed FS.
Abdominal Radiology. 2021.
doi:10.1007/s00261-020-02902-y.
- Background: US is commonly used to evaluate patients with suspected acute cholecystitis, although the sensitivity and specificity rates can be suboptimal even when combined with local and systemic signs of inflammation on physical exam and laboratory tests. US stands to gain improved sensitivity as a screening test.
- Question: Is there a sensitive cutoff in gallbladder dimensions to exclude acute cholecystitis?
- Inclusion: Patients who had abdominal US for right upper quadrant pain from January 2019 to April 2019 were included.
- Design: This is a retrospective study reviewing 456 patients with abdominal US for right upper quadrant pain. Review of patients’ sonographic findings, clinical data, and pathology from subsequent cholecystectomy or post-1 month follow-up with symptom resolution was completed. Univariable and multivariable logistic regression analyses were conducted to establish association of gallbladder dimensions and other sonographic and clinical variables with acute cholecystitis.
- Results: 319 patients with acute, chronic, and no cholecystitis were included. Gallbladder width of below 2.2 cm demonstrated no cases of acute cholecystitis, resulting in 100% sensitivity.
- Conclusion: Gallbladder underdistension with width less than 2.2 cm can serve as a sensitive sign to exclude acute cholecystitis.
Original Research
Placental thickness correlates with placenta accreta spectrum (PAS) disorder in women with placenta previa.
Li Y, Choi HH, Goldstein R, Poder L, Jha P.
Abdominal Radiology. 2021.
doi:10.1007/s00261-020-02894-9.
- Background: There is significant interobserver variability in diagnosing placenta accreta spectrum (PAS) disorder. PAS is associated with placenta previa, and there is significant overlap in their imaging features. It is important to distinguish the two as it can impact clinical management.
- Question: What is the association of placental thickness in women with placenta previa with the risk for PAS disorders?
- Inclusion: US reports performed closest to mid-gestation were included over a 3 year duration.
- Design: This is a retrospective study reviewing US reports performed closest to mid-gestation. Three measurements were obtained at the thickest portion of the placenta on longitudinal transabdominal images. Statistical analysis was done using unpaired T-tests and a receiver operating curve (ROC).
- Results: 65 patients with placenta previa were included. The average placental thickness was 4.3 cm for the PAS group and 3.0 cm for the non-PAS group. A threshold of 4.5 cm showed a 50% sensitivity and 96% specificity for PAS.
- Conclusion: Increased placental thickness at the lower uterine segment is associated with PAS disorder. This can be used to stratify patients at low risk vs high risk for PAS disorders.
Pediatric Imaging
Original Research
Liver Fat Quantification by Ultrasound in Children: A Prospective Study.
D’hondt A, Rubesova E, Xie H, Shamdasani V, Barth RA.
American Journal of Roentgenology. 2021.
doi:10.2214/ajr.20.24874.
- Background: Nonalcoholic fatty liver disease (NAFLD) commonly causes chronic liver disease in children and is increasing in prevalence with obesity. Noninvasive imaging methods for diagnosing and quantifying liver fat can help guide management.
- Question: Can quantitative US techniques, including acoustic attenuation, computerized hepatorenal index (HRI), Nakagami parameter, and shear wave elastography (SWE)-based metrics, provide liver steatosis quantification?
- Inclusion: Patients less than 18 years old who underwent abdominal MRI between November 2018 and July 2019 were enrolled. Patients also had targeted US evaluation of the liver.
- Design: This is a prospective study of children who obtained abdominal MRI and targeted US evaluation of the liver. US data was processed to compute the acoustic attenuation coefficient, HRI, Nakagami parameter, and SWE parameters. US parameters were compared to MRI proton density fat fraction (PDFF), a reference standard.
- Results: A total of 48 patients were enrolled, of which 21% had steatosis. For attenuation coefficient, a threshold of 0.54 dB/cm/MHz had 80% sensitivity and 82% specificity for steatosis, and a threshold of 0.60 dB/cm/MHz had 80% sensitivity and 98% specificity for moderate steatosis. For HRI, a threshold of 1.48 had 90% sensitivity and 76% specificity for steasosis, and a threshold of 2.11 had 100% sensitivity and 100% specificity for moderate steatosis. Neither SWE nor Nakagami parameters were strongly correlated with MRI PDFF.
- Conclusion: HRI and attenuation coefficient can accurately detect and quantify liver fat, which is essential for the management of NAFLD in children.
Review
Ultrasound Evaluation of Pediatric Slow-Flow Vascular Malformations: Practical Diagnostic Reporting to Guide Interventional Management.
Reis J, Koo KSH, Monroe EJ, et al.
American Journal of Roentgenology. 2020:1-13.
doi:10.2214/ajr.20.23338.
- Overview: This article reviews the key ultrasound features of pediatric slow-flow vascular malformations, which are subdivided into capillary, venous, and lymphatic. Discussion of their lesion size, malformation location, morphology and their mimics is included. Accurate descriptions of these lesions can aid in preprocedural planning and clinical management.
