Assessment Of Echogenicity Research Articles

Dermatological ultrasound in assessing skin aging.

Ultrasonography (US) has emerged as a pivotal tool in Dermatology since its inaugural use in 1979. Its evolution encompasses technological advancements, higher frequencies, and diverse applications in clinical, surgical, and research aspects. The discussion centers on its crucial role in assessing skin aging through various parameters such as skin thickness, subepidermal low echogenicity band (SLEB) characterization, and echogenicity assessment. This analysis can help guide interventions in a more personalized manner for each patient and assess the effectiveness of cosmetics and procedures. Despite its widespread utility, challenges persist, including discrepancies in research outcomes, operator dependence, inability to detect minute lesions, and measurement variations throughout the day. Combining US with complementary methodologies is advocated for a better understanding of skin aging in vivo. The cost-effectiveness and non-invasiveness of the US emphasize its promising future in dermatology, but ongoing research remains imperative to enhance its accuracy and expand its applications.

TH-131. Quantitative muscle echogenicity assessment using thresholding methods in Charcot-Marie Tooth disease

TH-131. Quantitative muscle echogenicity assessment using thresholding methods in Charcot-Marie Tooth disease

Ultrasound imaging of quadriceps muscle in patients with knee osteoarthritis: The test-retest and inter-rater reliability and concurrent validity of echo intensity measurement

BackgroundEcho intensity(EI) on ultrasonography images of skeletal muscle reflects muscle composition. ObjectivesThe primary aim of the study was to investigate the inter-rater and test-retest reliability of EI using grayscale histogram analysis of the cross-sectional area of quadriceps femoris(QF) muscle in patients with knee osteoarthritis(KOA). The secondary aim of the study was to determine the concurrent validity of the Free Hand Tool(FHT) when compared to Rectangular Marquee Tool(RMT) for calculating the region of interest(ROI) in ImageJ. MethodsThis study included thirty patients with KOA. Echogenicity of the QF muscle were performed by two different raters. The reliability analysis was applied using intraclass correlation coefficient(ICC), standard error of measurement(SEM) and coefficient of variation(CV). Spearman rank correlation coefficients were calculated for assessing concurrent validity of the FHT to RMT. The Bland–Altman plots was used to show disagreement between tools. Wilcoxon signed-rank test was used for differences in assessments between test/retest sessions, raters, tools. ResultsThe inter-rater and test-retest reliability of the EI using FHT and RMT was found to be excellent (ICCFHT = 0.91–0.95, 0.98–0.99, ICCRMT = 0.91–0.98, 0.91–0.99,respectively). Bland–Altman analysis demonstrated a slight bias when region ROI calculations were collected from RMT or FHT (bias ranging from 2.75 to−2.40 a. u). There were no significant differences between test/retest sessions, raters and tools(p > 0.05). Spearman correlation coefficient showed excellent correlation between tools used for echogenicity assessment of QF muscle(p < 0.001). ConclusionEI assessment using ultrasonography in the QF muscle showed excellent reliability. Evaluating muscle echogenicity using both FHT and RMT appears to be reliable and validity for monitoring muscle changes due to KOA.

Quantitative assessment of muscle echogenicity in Charcot-Marie-Tooth disease type 1A by automatic thresholding methods

ObjectiveTo investigate the utility of automatic thresholding methods for quantitative muscle echogenicity assessment as a marker of disease severity in Charcot-Marie-Tooth disease type 1A (CMT1A). MethodsMuscle ultrasound was performed in 15 CMT1A patients and 7 healthy controls. Muscle echogenicity of six limb muscles in each subject was assessed by 16 automatic thresholding methods and conventional grey-scale analysis. Echogenicity of each method in CMT1A patients was compared with that in controls. A correlation between the echogenicity and CMT neuropathy score (CMTNS) was also analysed in CMT1A patients. ResultsSignificant differences in mean echogenicity of the 6 muscles between CMT1A patients and controls were found both in grey-scale analysis (p < 0.01) and 11 of the 16 automatic thresholding methods (p < 0.05 in each method). In CMT1A patients, mean echogenicity of the 6 muscles was positively correlated with CMTNS in 8 of the 16 automatic thresholding methods, but not in grey-scale analysis. ConclusionAutomatic thresholding methods can be used to detect the difference in muscle echogenicity between CMT1A patients and controls. Echogenicity parameters correlate with the disease severity. SignificanceQuantitative muscle echogenicity assessment by automatic thresholding methods shows potential as a surrogate marker of disease progression in CMT1A.

Classifying median nerves in carpal tunnel syndrome: Ultrasound image analysis

Rationale and objectivesCarpal tunnel syndrome(CTS)refers to a common median nerve pathology, which is related to an increased pressure in the fibrous/bone canal of the wrist. Ultrasound gained popularity recently as a useful tool for the accurate and repetitive diagnosis of carpal tunnel syndrome. The present study aimed to develop an objective, repetitive technique for assessing median nerves based on carpal tunnel ultrasoundtextureanalysis. Material and methodsSixty ultrasound images, including 30 images of swollen “symptomatic” median nerves and 30 normal “asymptomatic” median nerves, were used in this study. Narrow age group of patients were selected. They were recruited after positive nerve conduction study and with present clinical symptoms reviled on basis of interview and written questionnaire. Meticulous nerve area and echogenicity assessment were conducted in line with existing recommendations. ResultsUsing the feature-selection tool MaZda, an exhaustive search of the data space was conducted, and four texture features were found for which the classification was the most accurate. Images were classified using a support vector machine with a five-fold cross-verification in MATLAB. Evoked outcomes showed a 79% correct classification rate. ConclusionComputer analysis of the image echogenicity of the median nerve presented confidence levels comparable to trusted evaluation techniques. Further, it is a promising tool for assessing the nerve’s status in CTS as approach of the CTS assessment free from subjectivity of examiner. The developed method enables nerve classification based on echogenicity that reflects the nerve composition changes not only subjective nerve area assessment.

Assessment of union in fractures: Role of Serum Alkaline Phosphatase and Ultrasonography

IntroductionFracture union is a fundamental goal in orthopaedics. There is variability in assessment and lack of consensus on reliability of various methods to evaluate progress of union. The purpose of this study was to study the temporal association of non-conventional methods i.e. Serum Alkaline Phosphatase (ALP) and Ultrasound (USG) in assessment of fracture healing with reference to plain radiographs (X-ray). MethodologyThis was a prospective observational cohort study of 161 adult patients with surgically treated long bone diaphyseal fractures. Plain radiographs, ALP and USG evaluation was done every 6 weekly for 6 months. USG evaluation included assessment of echogenicity and Doppler measurement of Vascular Resistance Index (RI) of callus. Fractures were considered united when X-ray showed bridging callus. ALP and USG changes over the follow-up period were analysed based on the final outcome of fractures. Results and conclusion151 patients showed signs of fracture union at final follow-up. ALP which peaked at 6 weeks in all cases always remained within the laboratory reference range in cases progressing to union; whereas in cases of non-union the levels recorded higher. ALP value was the earliest positive predictor showing progress towards union. Beyond 12 weeks, Hyperechogenicity on Gray scale USG and serial measurement of RI on Doppler USG were found to better confirm progress in fracture union than X-rays. Combined evaluations of ALP and USG appear as promising investigations in assessment of the progress in fracture union.

Assessment of Echogenicity of Thyroid Nodules.

Assessment of Echogenicity of Thyroid Nodules.

Grayscale histogram analysis to study the echogenicity and echotexture of the walls of the common carotid arteries of horses and mules

ABSTRACT: Visual inspection of ultrasound examination for assessment of echogenicity and echotexture of blood vessel tissues is a technique routinely used in medical practice in humans. However, simple visual inspection can lead to poor quality diagnoses and errors. The use of grayscale histogram (GSH) analysis has proved to be an efficient technique to quantify the region of interest, allowing minimization of image interpretation errors. This study aimed to evaluate and compare the echogenicity and echotexture of the walls of the common carotid arteries of healthy female horses and mules using the GSH technique and correlate them with age, body mass, and vessel diameters. B-mode ultrasound examinations were performed in the left and right common carotid arteries in three regions (cranial, middle, and caudal) in 11 horses and 11 healthy mules. The GSH of the animals showed heterogeneous walls, but did not differentiate statistically between female horses and mules. The Mean variable of the middle right, middle left and caudal right sides showed differences, more significant in the mules. On the middle right side, the Min variable was different, higher in the mules. On the middle and caudal left side, the variables Max and Mode showed higher values in the mules. For the mules, the age factor presented negative correlation with the Mean, Mode,, Mode(Count), and Mode(Count)/Count(%) variables, and the body mass factor presented negative correlation with the Mode, Mean and Max variables. For the female horses, the body mass factor showed positive correlation with the Mean and Mode variables. Echogenicity of the carotid artery walls differed between female horses and mules, whereas echotexture was heterogeneous and statistically similar among the animals. The age and body mass factors inversely influenced the echogenicity of the mules, but were not significant in the female horses, in which only the body mass factor positively influenced echogenicity.

Fetal pancreatic hyperechogenicity may be an early ultrasonographic sign of gestational diabetes mellitus

Aim: To determine whether fetal pancreatic echogenicity assessment is associated with gestational diabetes mellitus (GDM).Methods: A prospective cross-sectional study was conducted in a cohort of 160 pregnant women with uncomplicated singleton pregnancies. Fetal ultrasonography was performed between 24 and 28 weeks of gestation for conventional fetal biometry. Based on their pancreatic sonogram results, subjects were divided into two groups, that is, hyperechogenic pancreas group and iso-moderate echogenic pancreas group. Birth characteristics (mode of delivery) and fetal outcomes (gestational age at birth, fetal gender, birth length and weight, Apgar for 1. Versus 5. Minutes) were recorded and the relationship between pancreatic hyperechogenicity and the presence of GDM was assessed.Results: Sixty-six cases with hyperechogenic pancreas (group 1) and 70 cases with iso-moderate echogenic pancreas (group 2) were included to the study. There were no significant differences in maternal demographic and obstetric features between the groups. Fetal birth weight and length were significantly higher in the hyperechogenic pancreas group (p < .0001, p = .013; respectively). Hyperechogenic pancreas was significantly and positively associated with GDM risk. Hyperechogenic pancreas was significantly and positively associated with an increased GDM risk by 29.8 times compared to grade 1 isoechogenic group (p < .0001).Conclusion: An accurate prediction model for GDM among pregnant women via hyperechogenic pancreas may be created. Fetal hyperechogenic pancreas may be used as a complementary biomarker for the detection of pregnant women suspected of GDM.

Effects of selenium in patients with Graves’ disease treated with antithyroid drugs

Несмотря на противоречивые результаты недавно проведенных исследований селена (Se) при болезни Грейвса (БГ), адъювантная роль микроэлемента при данном заболевании продолжает исследоваться.&#x0D; Целью данной работы являлось изучение эффектов селенметионина в составе консервативной терапии БГ.&#x0D; Методы. В исследование были включены 28 пациенток в возрасте от 19 до 52 лет с впервые выявленной БГ легкого или среднетяжелого течения, которым планировалось проведение тиреостатической терапии в течение 12 мес. Пациентки были рандомизированы в две группы терапии: 1) тиреостатическая терапия + Se (200 мкг); 2) тиреостатическая терапия. Исходно и каждые 3 мес наблюдения оценивались показатели: ТТГ, св.Т4, св.Т3, АТ-ТПО и АТ-рТТГ, также проводилось УЗИ щитовидной железы (ЩЖ), оценивались объем и эхогенностьпаренхимы ЩЖ. Период наблюдения составил 18 мес (12 мес терапии, 6 мес наблюдения после отмены тиреостатической терапии, Se отменялся после 15 мес наблюдения).&#x0D; Результаты. В нашем исследовании не получено статистически значимых отличий между группами терапии БГ по скорости достижения эутиреоза, динамике показателей АТ-рТТГ и АТ-ТПО в течение всего периода наблюдения, частоте развития рецидива заболевания в течение 6 мес после отмены терапии.&#x0D; Выводы. Согласно данным нашего исследования, применение Se в фармакологических дозах (200 мкг в сутки) в рамках комплексной терапии БГ в течение 12 мес не приводило к статистически значимому эффекту в отношении клинических исходов БГ, а также не сопровождалось положительным “аутоиммунным” эффектом.

Quantitative assessment of nerve echogenicity as an additional tool for evaluation of common fibular neuropathy

ObjectiveQuantitative assessment of nerve echogenicity using the MaxEntropy, RenyiEntropy and Yen methods has shown promise in the assessment of ulnar neuropathy at the elbow. The purpose of this study was to determine the clinical usefulness of quantitative echogenicity measurement when using these three automatic thresholding methods in the evaluation of patients with common fibular (CF) neuropathy. MethodsHigh-resolution ultrasonography (HRUS) images of the CF nerve from 45 patients with CF neuropathy were compared to 42 healthy controls. ResultsWith all three methods patients with CF neuropathy had significantly higher mean hypoechoic fraction than healthy controls at the level of the fibular head (FH): MaxEntropy 87.4% versus 71.9% (p<0.001), RenyiEntropy 84.7% versus 68% (p<0.001) and Yen 87.6% versus 68.2% (p<0.001). Patients with CF neuropathy could be differentiated from healthy controls at a hypoechoic fraction cut-off point of 82% (MaxEntropy), 80% (RenyiEntropy) and 80% (Yen) with a sensitivity of 82%, 82% and 84% respectively, and a specificity of 93%, 95% and 83% respectively. Similar results were found for sonographic measurements above the FH. ConclusionQuantitative assessment of nerve echogenicity using the MaxEntropy, RenyiEntropy and Yen methods can be used to distinguish between patients with CF neuropathy and healthy controls with high sensitivity and specificity. SignificanceThese three proven automatic thresholding methods can be used to assess nerve echogenicity in future studies. Quantitative echogenicity assessment with HRUS shows promise for the future as a potential diagnostic tool in daily clinical practice.

Quantitative assessment of nerve echogenicity: Comparison of methods for evaluating nerve echogenicity in ulnar neuropathy at the elbow

ObjectiveThe objective is to evaluate different methods to assess nerve echogenicity in a quantitative way by comparing a group of patients with ulnar neuropathy at the elbow (UNE) and a healthy control group, subsequently selecting the best tests for quantitative assessment of nerve echogenicity. MethodsWe included 56 patients with UNE and 37 healthy controls. High-resolution ultrasonography images of the ulnar nerve at the level of the medial epicondyle were saved in JPEG, TIFF or DICOM format, with a 19pixels/mm resolution. Hypoechoic fraction was calculated by using 1 manual and 16 automatic thresholding methods. ResultsA significant difference in mean hypoechoic fraction between patients and controls was found using the following automatic thresholding methods: MaxEntropy 82% versus 74% (p<0.001), RenyiEntropy 80% versus 69% (p<0.001), Shanbhag 76% versus 68% (p=0.002), Triangle 45% versus 58% (p=0.036) and Yen 79% versus 67% (p<0.001). Of these five tests a significant correlation between hypoechoic fraction and the cross-sectional area was found for: MaxEntropy 0.542 (p<0.001), RenyiEntropy 0.558 (p<0.001), Shanbhag 0.219 (p=0.035) and Yen 0.513 (p<0.001). The manual thresholding method did not detect a significant difference in hypoechoic fraction between patients and controls, and inter-rater agreement in hypoechoic fraction for manual thresholding was poor. ConclusionQuantitative nerve echogenicity assessment can be successfully used to distinguish between a group of patients with UNE and a healthy control group, preferably by using the MaxEntropy, RenyiEntropy or Yen methods. SignificanceAutomatic thresholding techniques using the MaxEntropy, RenyiEntropy or Yen methods are the best quantitative tests, and these quantitative measures can probably be used in further studies evaluating echogenicity in mono- and polyneuropathies.

Utility of the Assessment of Echogenicity in the Identification of Symptomatic Carotid Artery Atheroma Plaques in Ischemic Stroke Patients

Background and Purpose: Echogenicity of atheroma carotid plaques is related to a higher risk of stroke. Clinical and subjective ultrasound criteria are used to identify symptomatic plaques, but the standardized grayscale median (GSM) value may be an objective tool for this diagnosis. Our aim was to analyze the utility of assessing the echogenicity of atheroma carotid plaques in the identification of symptomatic plaques. Methods: Observational prospective study with inclusion of acute noncardioembolic anterior cerebral circulation ischemic stroke patients. Only patients with bilateral atheroma plaques were included. Echogenicity of plaques was measured by a digital and standardized grayscale system in carotid ultrasound B-mode (longitudinal projection) conducted within the first week after admission. Results: Sixty-six patients were included and 132 plaques were examined. Symptomatic atheroma plaques were less echogenic than asymptomatic ones (GSM 20.0 vs. 29.0; p = 0.002). A ROC curve analysis showed the predictive value of GSM with an AUC of 0.707 (95% CI 0.592–0.823; p = 0.002) and pointed to a value of 24.4 as the optimal cut-off level to identify a plaque as symptomatic (74% sensitivity; 67% specificity). This GSM cut-off point remained significantly associated with a high probability of symptomatic plaque even after the inclusion of the degree of carotid stenosis (either >70% or >50%) in the multivariate logistic regression models. Conclusions: The assessment of echogenicity of atheroma carotid plaques by the GSM value combined with clinical characteristics and stenosis degree may be useful in the identification of symptomatic plaques.

Percentage White: A New Feature for Ultrasound Classification of Plaque Echogenicity in Carotid Artery Atherosclerosis

Atherosclerotic stenotic and nonstenotic plaques of the carotid artery with low echogenicity have been shown to be associated with cardiovascular disease. The aim was to develop a new method for semiautomated ultrasound image analysis to classify nonstenotic carotid plaques, evaluate cases with multiple plaques and examine the association between a new image analysis feature of echogenicity and predictors of cardiovascular disease. The new image analysis feature, percentage white (PW), represents the fraction of bright structures inside a plaque and is integrated in an objective semiautomated method to evaluate echogenicity (SAMEE) in carotid plaques. PW was constructed to take into account overall echogenicity of the image as well as noise surrounding the plaque. Consecutive ultrasound examinations of carotid plaques from a population-based screening of 64-year-old women with varying risk for cardiovascular disease were selected for the present project; 92 far-wall and 47 near-wall plaques were used as a training dataset to develop the SAMEE algorithm with visual classification according to Gray-Weale as reference; 273 plaques were used to validate the method. All plaques were included in an analysis relating predictors of cardiovascular to average PW in all plaques, PW in the biggest plaque and to the plaque with lowest PW in each subject, respectively. In the training dataset the intermethodological variability between SAMEE and visual classification showed a κ of 0.78 and a sensitivity and specificity of 96% and 81%, respectively. In the validation set, SAMEE and visual classification showed a κ of 0.77, a sensitivity of 96% and a specificity of 80%. The reproducibility of PW was high, evidenced by r = 0.96 and CV = 9.85% at repeated examinations. Average PW values were associated with several predictors of cardiovascular risk: lipoprotein (a), HbA1c, blood glucose, apolipoproteinB/apolipoproteinA-I; and associated negatively with the levels of adiponectin and apolipoprotein A-I. In conclusion, PW integrated within a SAMEE is a new feature for assessment of echogenicity in carotid plaques and shows excellent reproducibility and agreement with visual assessment. (E-mail: ulrica.prahl@wlab.gu.se).

Brachial artery hyperemic blood flow velocities are related to carotid atherosclerosis

Cardiovascular (CV) risk relates to the blood flow velocity pattern in the brachial artery during hyperemia, especially to the hyperaemic systolic to diastolic mean blood flow velocity (SDFV) ratio. Here, we investigated the relations between SDFV in the brachial artery and different characteristics of carotid atherosclerosis. Data were collected from 1016 70-year-olds participating in the Prospective Investigation of Uppsala Seniors study. Doppler recordings of blood flow velocity during hyperemia were analysed in the brachial artery. In the carotid artery, intima-media thickness (IMT) was recorded together with an assessment of echogenicity by the Grey scale median (GSM) method in both overt plaques and in the intima-media complex (IM-GSM). The SDFV ratio was related to the number of carotid arteries affected by plaque (P = 0.018) and inversely to plaque echogenicity (P = 0.0003). The SDFV ratio was also related to IMT (P = 0.0022) and inversely to IM-GSM (P = 0.0001). These relations were statistically significant also after adjusting for major CV risk factors, individually as well as summarised as the Framingham risk score. Our results indicate that the hyperemic systolic to diastolic blood flow velocity ratio in the brachial artery is related to atherosclerosis in the carotid artery.

In vitro characterization of liposomes and Optison by acoustic scattering at 3.5 MHz

Objective: To assess the potential of immunoliposomes as an ultrasound contrast agent relative to albumen-stabilized microbubbles, a quantitative assessment of echogenicity was performed. Methods: Liposomes are stabilized phospholipid vesicles, which can encapsulate both gas and fluid. With antibody conjugation, this new formulation of immunoliposomes can be targeted to atheroma and other pathologic components, and thus they are being developed as novel diagnostic ultrasound echo contrast agents to enhance imaging of atherosclerosis. The diameter of the liposomes ranges from 0.25 to 5.0 microns. To measure the backscattering coefficient of liposome suspensions of varying concentrations, the backscattered power at 3.5 MHz was compared to that reflected from a planar air-water interface. The backscattering coefficient was also estimated theoretically as a function of air volume fraction by modeling the encapsulated air as a free air bubble and assuming single bubble scattering. Results: For most of the concentrations of liposomes used (on the order 108/ml), the backscattering coefficient equals or exceeds that of Optison (Mallinckrodt, Inc.) at the human clinical dose concentration (104/ml). The backscattering coefficient at 3.5 MHz appears to be a linear function of liposome concentration, suggesting that single bubble acoustic scattering theory holds. Conclusions: This detection technique shows promise as a sensitive method for determining whether the immunoliposomes are left intact or if they are destroyed during imaging, thus helping to explore their potential as a vehicle for targeted drug delivery.

The subjective assessment of echogenic fetal bowel.

To assess the subjective interpretation of the echogenicity of fetal bowel compared to bone from antenatal ultrasound images taken during examinations conducted between 17 and 22 weeks of gestation. Eighty-seven women attending for their antenatal scan were selected in a random prospective manner over a 9-month period. Images of the fetal bowel were taken and evaluated by 10 sonographers, one consultant obstetrician and one consultant radiologist. Images from a further 13 fetuses, in which the subjective assessment of echogenic bowel was made, were also included. All ultrasound images were acquired on a dedicated ultrasound scanner, with a standard transducer, thermal paper printer and single operator using standardized equipment settings and reproducible image sections. Questionnaires with 100 sets of images of fetal bowel were distributed to the participants. Performance was assessed by means of percentage agreement and levels of chance corrected agreement (Kappa). The subjective assessment of fetal bowel echogenicity is very variable. Intra- and inter-observer variation discrepancies in the assessment of bowel echogenicity compared to bone were demonstrated between the sonographers. Good agreement was identified between the consultants with good to almost perfect intra-observer agreement. Overall, only moderate agreement was observed between the sonographers and the consultants. The lack of agreement demonstrated between sonographers when evaluating the echogenicity of fetal bowel should be addressed if this ultrasound marker is to be incorporated into routine fetal screening programs.

Computed sonography: requiem to echogenicity assessment?

We studied the influence of changes in gain settings, log compression, persistence, preprocessing, and postprocessing on image density in the fetal liver model. Each parameter was studied while the others were held constant. The image density was objectively measured by electrooptical transmission densitometry using a transparent film output. Neither the persistence nor the preprocessing levels significantly changed image density. Postprocessing of sonographic images produced significant differences (p < 0.02) in mean image density of most of the various postprocessing curves and is a serious confounder of tissue echogenicity assessment. The data reconfirmed that there is a linear relationship (r = -0.94 to -0.997) between image density and gain setting. However, each log compression setting significantly changed (p < 0.0000001) this relationship, obviating possible image density calibration. Our data suggest that manipulation of image parameters by computed sonographic technology obviates accurate echogenicity assessment.

The relation between different system gain settings and the accuracy of densitometric assessment of echogenicity.

Two mathematical transformations of the measured density of a sonographic image of the fetal liver were used in 19 patients at nine different system gain settings (G) (optimal G number [dB] and optimal G number +/- 2, +/- 4, +/- 8, +/- 12). A significant correlation was found between the film-corrected density (Dcor) and gain interval from the optimal gain (Dcor = 1.39-0.052 [G interval], R = -0.81, P < 0.00001, 95% confidence limits = -0.052 +/- 0.052). After standardization of the values to the arbitrary G number of 49 (Dcor 49), a gain-independent convergence of the values was found. In 79% of the 19 cases the accuracy of the method was very high, as estimated from a small coefficient of variation. No significant difference was found in comparing the mean standardized densities derived from paired measurements (i.e., optimal G number +/- 2, +/- 4, +/- 8, and +/- 12). The data support background assumptions for the quantitative assessment or echogenicity by transmission densitometry and provide highly confident accuracy estimates.

Quantitative assessment of sonographic image echogenicity by transmission densitometry: fetal liver model

A mathematical method is proposed to compare density values of different sonographs of the same tissue. Two transformations were needed: (1) calibration of the gray scale according to the maximal range of scanning for a given tissue, and (2) comparison of the effect of two time-compensated gains on the difference in density and standardizing this effect to an arbitrary gain. To verify these relationships, 12 fetal livers were scanned at 38 weeks' gestation, at three different gains corresponding to the optimal gain and to the minimal and maximal gains that allowed a clear image to be obtained. After the mathematical transformations, the initially completely different densities were nearly identical (t-test: P = 0.9998; Wilcoxon test: P > 0.5; Pearson's R = 0.8933). This method permits an accurate quantitative assessment of the echogenicity of any parenchymatous organ.