Comparison of A-mode and B-mode Ultrasound for Measurement of Subcutaneous Fat

Estimation of Validity of A-Mode Ultrasound for Measurements of Muscle Thickness and Muscle Quality

This study aimed to determine whether amplitude modulation (A-mode) ultrasound (US) provides accurate and reliable measurements comparable to those obtained using brightness modulation (B-mode) US under diverse conditions. Thirty healthy participants (15 women and 15 men) underwent measurements of subcutaneous fat thickness (SFT), muscle thickness (MT), and muscle quality (MQ) in the trapezius and biceps brachii muscles using both US modes before and after exercises designed to stimulate the respective muscles. Among the three key indices, the results demonstrated the high validity of the A-mode, with minimal mean differences (MDs) between the two devices less than 0.91 mm and intra-class correlation coefficients (ICCs) exceeding 0.95 for all measures. In addition, the correlation coefficients between the error scores and average scores for the trapezius and biceps brachii suggested no evidence of systematic error. The trapezius MT and MQ significantly increased, and the biceps brachii MT significantly increased after the exercises (p < 0.05). Notably, both the A- and B-modes exhibited the same trend in these post-exercise changes in the muscle. This study suggests that low-cost and low-resolution A-mode US provides measurements of SFT, MT, and MQ similar to the more expensive, high-resolution B-mode imaging. A-mode US is an affordable and portable alternative for muscle assessment.

Shear Wave Elastography for Assessment of Changes in Abdominal Soft Tissues after Lipoabdominoplasty

BACKGROUND

The changes in the elasticity of the abdominal skin, subcutaneous tissues and muscles after lipoabdominoplasty are still unknown. The aim of this study was to provide an objective assessment of tissue elasticity after lipoabdominoplasty using ultrasound elastography.

METHODS

A total of 21 female patients (31-41 years old) who underwent lipoabdominoplasty from Oct 2019 to Mar 2022 were included in this retrospective study. The elastography values of the skin, subcutaneous tissues and abdominal muscles were obtained with the ultrasound shear wave elasticity imaging system pre-operation (Pre) and 6 months post-operation (Post) at four different points.

RESULTS

Twenty-one female patients were included. The elasticity of the abdominal skin, subcutaneous tissues, rectus abdominis and external oblique abdominis significantly increased at 6 months post-operation. The improvements in abdominal soft tissue elasticity were not uniform across the examined points.

CONCLUSIONS

Significant changes in the elasticity of the abdominal skin, subcutaneous tissues and muscles were observed after lipoabdominoplasty. Ultrasound elastographic assessment was objective and feasible for evaluating the effect of lipoabdominoplasty on abdominal soft tissue.

LEVEL OF EVIDENCE III

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Methods to assess tooth gingival thickness and diagnose gingival phenotypes: A systematic review

OBJECTIVE

Measurement of the periodontal soft tissue dimension is crucial for clinical decision-making and aesthetic prognosis. However, the effectiveness of different measuring methods remains unclear. This systematic review aimed to explore the diagnostic accuracy of two non-invasive methods (namely CBCT and ultrasound) for gingival thickness measurement at different tooth positions.

MATERIALS AND METHODS

A systematic search was performed using PubMed (including Medline), PubMed Central, OVID, Cochrane Library, LILACS and OpenGrey. Studies focusing on comparisons between CBCT, ultrasound and direct transgingival probing were included. The means, SDs and correlation coefficients with 95% confidence intervals were extracted and analyzed using Review Manager and R software.

RESULTS

Twelve studies were selected. No significant difference was found between CBCT measurement and transgingival probing in the anterior and posterior dentition, and a moderate correlation was observed between these two methods (r = 0.41). A weak correlation was found between ultrasound measurement and transgingival probing (r = 0.32), and a slight but statistically significant difference was found when comparing ultrasonic devices and transgingival probing in the posterior area.

CONCLUSION

CBCT can be considered a relatively reliable method for gingival thickness measurement in both the anterior and posterior areas compared with direct probing. Ultrasonic devices provide limited accuracy in the posterior area but are relatively comparable with direct clinical assessments in the anterior area.

CLINICAL SIGNIFICANCE

Measurement location may affect the diagnostic accuracy and repeatability of gingival thickness measurements. Appropriate method selection in different clinical scenarios is crucial to aesthetic outcome prediction and decision-making.

Improvement in bladder volume reproducibility using A-mode portable ultrasound bladder scanner in moderate-hypofractionated volumetric modulated arc therapy for prostate cancer patients

Purpose

This study introduced an A‐mode portable ultrasound bladder scanner, the Lilium® α‐200 (here after Lilium; Lilium Otsuka, Kanagawa, Japan), for the treatment of prostate cancer patients with hypofractionated volumetric modulated arc therapy to improve the reproducibility of bladder volume (BV).

Materials and methods

Thirty patients were advised to maintain full BV prior to computed tomography (CT) simulation and daily treatment. Among these, the BV of 15 patients was measured using Lilium until a BV of 80% in the simulation was achieved (with the Lilium group). Daily cone‐beam CT (CBCT) was performed for treatment. The correlation between BV measured by CBCT and Lilium was assessed. The differences in the BV and dosimetric parameters of the bladder in the CBCT versus planning CT were compared between the groups with and without Lilium.

Results

There was a significantly strong relationship (r = 0.796, p < 0.05) between the BVs measured using CBCT and Lilium. The relative BV ratios to simulation CT < 0.5 and > 2 were observed in 10.3% and 12.7%, respectively, of treatment sessions without Lilium group, while these ratios were 1% and 2.8%, respectively, in the Lilium group. The mean absolute difference in the range of V_30Gy to V_40Gy without Lilium sessions was significantly larger (p < 0.05) than that in the Lilium group.

Conclusion

The use of the A‐mode portable ultrasound bladder scanner significantly improved the reproducibility of the BV, resulting in few variations in the dosimetric parameters for the bladder.

Ultrasound Measurements of Subcutaneous Fat Thickness Are Robust Against Hydration Changes

Ultrasound is an appealing tool to assess body composition, combining the portability of a field method with the accuracy of a laboratory method. However, unlike other body composition methods, the effect of hydration status on validity is unknown. This study evaluated the impact of acute hydration changes on ultrasound measurements of subcutaneous fat thickness and estimates of body fat percentage. In a crossover design, 11 adults (27.1 ± 10.5 years) completed dehydration and hyperhydration trials to alter body mass by approximately ±2%. Dehydration was achieved via humid heat (40 °C, 60% relative humidity) with exercise, whereas hyperhydration was via ingestion of lightly salted water. Ultrasound measurements were taken at 11 body sites before and after each treatment. Participants lost 1.56 ± 0.58 kg (-2.0 ± 0.6%) during the dehydration trial and gained 0.90 ± 0.21 kg (1.2 ± 0.2%) during the hyperhydration trial even after urination. The sum of fat thicknesses as measured by ultrasound differed by <0.90 mm across trials (p = .588), and ultrasound estimates of body fat percentage differed by <0.5% body fat. Ultrasound measures of subcutaneous adipose tissue were unaffected by acute changes in hydration status by extents beyond which are rare and overtly self-correcting, suggesting that this method provides reliable and robust body composition results even when subjects are not euhydrated.

Interrater reliability of novice examiners using A-mode ultrasound and skinfolds to measure subcutaneous body fat

Examiners with minimal training and skill are often called upon to make body composition assessments using field methods. This study compared the interrater reliability of novice examiners for the skinfold (SKF) and A-mode ultrasound (US) methods of body composition assessment. Undergraduate Kinesiology majors (48 males, 32 females) with minimal training took both SKF and US measurements at three sites (males: chest, abdomen, thigh; females: triceps, suprailiac, thigh). Interrater reliability was significantly better for US compared to SKF at the thigh (ICCUS = 0.975, ICCSKF = 0.912) and abdomen (ICCUS = 0.984, ICCSKF = 0.693) for men and suprailiac (ICCUS = 0.978, ICCSKF = 0.883) for women. Additionally, interrater reliability of the US method was superior to the SKF method for the estimate of male body fat percentage (ICCUS = 0.990, ICCSKF = 0.862). The 95% CI was generally narrower for the US method than the SKF method at each site. The interrater reliability of the US method was superior to or equal to the SKF method for measuring subcutaneous body fat when novice examiners took the measurements.