Recent advances in ultrasound technology

[Ultrasound diagnostics of the liver : Principles and important pathologies]

Diffuse changes in the liver parenchyma, focal lesions and blood flow in hepatic vessels can be assessed using ultrasound. Screening by ultrasound can be used to detect hepatocellular carcinomas as possible malignant sequelae of liver cirrhosis. As metastases are far more frequent than primary malignant liver tumors, secondary malignant neoplasms should be taken into consideration as a differential diagnosis in the presence of focal liver lesions. This particularly concerns patients with a known metastatic disease. Benign focal liver lesions are often incidentally discovered in women of childbearing age. Cysts, hemangiomas and focal nodular hyperplasia mostly show typical morphological features in ultrasound and do not require further follow-up; however, with hepatic adenomas, regular follow-up is recommended due to the risk of bleeding and/or malignant transformation.

Efficacy of ultrasound shear wave elastography in the diagnosis of salivary gland tumors

PURPOSE

Diagnostic accuracy of fine-needle aspiration cytology (FNAC) as the ability to discriminate between the target condition and health in the evaluation of salivary gland tumors is not perfected yet and false-negative results are possible. The purpose of the present study was to measure and compare the diagnostic accuracy of FNAC performed with conventional B-mode ultrasound and ultrasound with shear wave elastography (SWE) FNAC navigation.

METHODS

The investigators implemented a single-blind randomized study (sealed envelope method). The study population was composed of all patients presenting for evaluation and management of suspected benign or malignant tumors of the major salivary glands between July 2013 and December 2020. The involvement of SWE navigation was the primary predictor variable affecting FNA targeting. The method involved analysis of redistribution of SWE values within the affected gland expressed in kilopascals (kPa) and the four-point ES1 (soft tissue) to ES4 (stiff) scoring. The primary outcome variable was the success in obtaining diagnostic tissue resulting in a histologically confirmed FNAC diagnosis and coded as yes/no. Age and sex of the patients and topographical locations of lesions were covariates. Descriptive and bivariate statistics were computed and the P value was set at .05.

RESULTS

The sample included 132 subjects (male/female 59/73; mean age 54 ± 11 years; 144 tumors). SWE + Group (n = 66) consisted of patients presurgically diagnosed with salivary tumors SWE-guided FNAC and SWE- Group (n = 66) was diagnosed with tumors by conventional ultrasound-(B-mode)-guided FNAC. The SWE-guided FNAC statistically significantly reduced the incidence of false-negative results (n = 0; P = .001) and nondiagnostic cases (n = 3 SWE FNAC vs n = 7 B-mode US FNAC; P = .04). For SWE + Group, the FNAC diagnosis was confirmed by postsurgical histology in 95.5% with 91.0% sensitivity (confidence interval [CI] 0.62 to 0.97) and 84.4% specificity (CI 0.58 to 0.96). For SWE- Group, 81.8% confirmation was obtained (P = .05) with 82.3% sensitivity (CI 0.54 to 0.90) and 74.0% specificity.

CONCLUSION

SWE can increase success in obtaining diagnostic tissue when used for FNAC navigation purposes. We suggest combining both SWE and standard B-mode US methods when the FNAC procedure is performed.

Fully Automated 3-D Ultrasound Segmentation of the Placenta, Amniotic Fluid, and Fetus for Early Pregnancy Assessment

Volumetric placental measurement using 3-D ultrasound has proven clinical utility in predicting adverse pregnancy outcomes. However, this metric cannot currently be employed as part of a screening test due to a lack of robust and real-time segmentation tools. We present a multiclass (MC) convolutional neural network (CNN) developed to segment the placenta, amniotic fluid, and fetus. The ground-truth data set consisted of 2093 labeled placental volumes augmented by 300 volumes with placenta, amniotic fluid, and fetus annotated. A two-pathway, hybrid (HB) model using transfer learning, a modified loss function, and exponential average weighting was developed and demonstrated the best performance for placental segmentation (PS), achieving a Dice similarity coefficient (DSC) of 0.84- and 0.38-mm average Hausdorff distances (HDAV). The use of a dual-pathway architecture improved the PS by 0.03 DSC and reduced HDAV by 0.27 mm compared with a naïve MC model. The incorporation of exponential weighting produced a further small improvement in DSC by 0.01 and a reduction of HDAV by 0.44 mm. Per volume inference using the FCNN took 7-8 s. This method should enable clinically relevant morphometric measurements (such as volume and total surface area) to be automatically generated for the placenta, amniotic fluid, and fetus. The ready availability of such metrics makes a population-based screening test for adverse pregnancy outcomes possible.

Comparison of Transabdominal and Transrectal Ultrasound for Sizing of the Prostate

OBJECTIVE

To compare the accuracy of prostate sizing between pelvic abdominal (PUS) and transrectal (TRUS) ultrasound in a large, diverse cohort of men at our institution. Prostate volume plays a vital role in all types of prostate disease. American Urological Association guidelines (2018) for surgical management of benign prostatic hyperplasia now include consideration of prostate volume measurement prior to surgical intervention. Ultrasound is a quick and radiation-free imaging modality.

METHODS

We performed a single-center, retrospective study of 299 patients with prostate sizing between January 1, 2012 and August 31, 2017. Prostate volume was derived from ellipsoid volume calculation using dimensions measured on ultrasound. PUS and TRUS were compared by calculating the Pearson correlation coefficient and intraclass correlation coefficient, and agreement between modalities assessed using the Bland Altman analysis. This analysis was done for the whole sample population as well as for specific groupings according to body mass index, prostate size, and time between exams.

RESULTS

A total of 236 patients had PUS followed by TRUS and met study inclusion criteria. Median age was 63, median prostate specific antigen value prior to PUS was 7.6 ng/mL, and only 20% were white. Mean volume differences between the two modalities for the data (vol_PUS - vol_TRUS) were (-0.3 ± 1.1) cm³. Bland-Altman analysis showed agreement between PUS and TRUS only for prostates ≤ 30 cm³.

CONCLUSION

For prostates less than 30 cc, we found that PUS is interchangeable with TRUS in estimating prostate volume. However, for larger prostates where size may alter surgical management, we would recommend TRUS or cross-sectional imaging.

A review of the Fukushima nuclear reactor accident: radiation effects on the thyroid and strategies for prevention

PURPOSE OF REVIEW

This is a summary of the nuclear accident at the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Stations (FDNPS) on 11 March 2011 to be used as a review of the radiation effects to the thyroid and strategies of prevention.

RECENT FINDINGS

The amount of radioiodine released to the environment following the Fukushima accident was 120 Peta Becquerel, which is approximately one-tenth of that in the Chernobyl accident. Residents near the FDNPS were evacuated within a few days and foodstuffs were controlled within 1 or 2 weeks. Therefore, thyroid radiation doses were less than 100 mSv (intervention levels for stable iodine administration) in the majority of children, including less than 1 year olds, living in the evacuation areas. Because the incidence of childhood thyroid cancer increased in those residing near the site following the Chernobyl accident, thyroid screening of all children (0-18 years old) in the Fukushima Prefecture was started. To date, screening of more than 280 000 children has resulted in the diagnosis of thyroid cancer in 90 children (approximate incidence, 313 per million). Thus, although the dose of radiation was much lower, the incidence of thyroid cancer appears to be much higher than that following the Chernobyl accident.

SUMMARY

A comparison of the thyroidal consequences following the Fukushima and Chernobyl nuclear reactor accidents is discussed. We also summarize the recent increased incidence in thyroid cancer in the Fukushima area following the accident in relation to increased thyroid ultrasound screening and the use of advanced ultrasound techniques.

VIDEO ABSTRACT

http://links.lww.com/COE/A8.

Thyroid ultrasound findings in children from three Japanese prefectures: Aomori, Yamanashi and Nagasaki

Due to the likelihood of physical and mental health impacts following the unprecedented accident at the Fukushima Dai-ichi Nuclear Power Plant, the Fukushima prefectural government decided to conduct the Fukushima Health Management Survey to assist in the long-term health management of residents. This included thyroid ultrasound examination for all children in Fukushima. For appropriate evaluation of ultrasound screening of the thyroid, it is important to understand its reference data of thyroid findings in children in general. In order to analyze the frequencies of specific thyroid findings, we conducted ultrasound screening of the thyroid by the same procedures as used in Fukushima in 4,365 children, aged 3 to 18 years, from three Japanese prefectures. Overall, thyroid cysts were identified in 56.88% and thyroid nodules in 1.65% of the participants. Thyroid cysts and nodules with a maximum diameter of more than 5 mm were identified in 4.58% and 1.01%, respectively, and age-adjusted prevalences were 3.82% and 0.99%, respectively. Although the prevalence of cysts and nodules varied among the examination areas, no significant differences were observed among the three examination areas in the prevalence of cysts and nodules with a maximum diameter of more than 5 mm. Also, the prevalence of thyroid cysts and nodules, especially those with a maximum diameter of more than 5 mm, significantly increased with age, and showed a female predominance. We also identified ectopic thymus (1.95%), diffuse goiter (1.40%), ultimobranchial body (0.73%), lymph node swelling (0.21%) and thyroid agenesis (0.05%). This is the first ultrasound description of the age-adjusted prevalence of thyroid cysts and nodules, or of the prevalence of abnormalities other than cysts and nodules, such as ectopic thymus, in relation to age, in the general Japanese child population. We contend that this can provide relevant information for the Fukushima Health Management Survey and future population studies.

Ultrasound for the anesthesiologists: present and future

Ultrasound is a safe, portable, relatively inexpensive, and easily accessible imaging modality, making it a useful diagnostic and monitoring tool in medicine. Anesthesiologists encounter a variety of emergent situations and may benefit from the application of such a rapid and accurate diagnostic tool in their routine practice. This paper reviews current and potential applications of ultrasound in anesthesiology in order to encourage anesthesiologists to learn and use this useful tool as an adjunct to physical examination. Ultrasound-guided peripheral nerve blockade and vascular access represent the most popular ultrasound applications in anesthesiology. Ultrasound has recently started to substitute for CT scans and fluoroscopy in many pain treatment procedures. Although the application of airway ultrasound is still limited, it has a promising future. Lung ultrasound is a well-established field in point-of-care medicine, and it could have a great impact if utilized in our ORs, as it may help in rapid and accurate diagnosis in many emergent situations. Optic nerve sheath diameter (ONSD) measurement and transcranial color coded duplex (TCCD) are relatively new neuroimaging modalities, which assess intracranial pressure and cerebral blood flow. Gastric ultrasound can be used for assessment of gastric content and diagnosis of full stomach. Focused transthoracic (TTE) and transesophageal (TEE) echocardiography facilitate the assessment of left and right ventricular function, cardiac valve abnormalities, and volume status as well as guiding cardiac resuscitation. Thus, there are multiple potential areas where ultrasound can play a significant role in guiding otherwise blind and invasive interventions, diagnosing critical conditions, and assessing for possible anatomic variations that may lead to plan modification. We suggest that ultrasound training should be part of any anesthesiology training program curriculum.

Contrast-enhanced ultrasonography (CEUS) in canine liver examination

Ultrasonography is a noninvasive diagnostic tool used to image size, shape, parenchyma and vascularization of various body organs. Unfortunately, the ultrasonographic image is characterized by a low contrast due to similar acoustic properties of the soft tissue. The Doppler mode provides information about blood flow, but is incapable of imaging small vessels and capillaries because of their low blood flow velocity (1 mm/s). However, a possibility to increase the effectiveness of ultrasonographic diagnostics exists, thanks to intravenous ultrasound contrast agents (UCAs) consisted of gas microbubbles. The purpose of this review paper is to characterize specific imaging techniques necessary to conduct a contrast-enhanced liver examination and indications for CEUS as an alternative diagnostic method.