Interobserver and intraobserver variations in sonographic measurement of thyroid volume in children

Interpreting Pediatric Laryngeal Ultrasonography: A Training Protocol for Novice Examiners

OBJECTIVE

Laryngeal ultrasonography (LUS) is a noninvasive alternative to nasal endoscopy for diagnosing vocal fold pathologies in the pediatric population. Inducing less discomfort and physiological impact, LUS is more well tolerated by young patients. Despite its advantages, interpreting ultrasound images is highly subjective, potentially undermining diagnostic accuracy. To address the limitation, this research aims to evaluate the effect of training on novice examiners' LUS interpretation proficiency and, secondly, whether examiners' interpretation confidence increases after receiving the training.

METHOD

Thirty-eight novice examiners were randomly assigned to the experimental and control group where the former received training. A stimulus-response-feedback-stimulus paradigm was employed in the training. Qualitatively, the presence of vocal fold lesions and vocal fold motion impairment was examined. Quantitatively, the left and right vocal fold-arytenoid angles were measured.

RESULTS

Results showed that training significantly improved diagnostic accuracy in qualitative measurements. Quantitatively, statistically significant effects were found posttraining with enhanced intrarater agreement and reduced interrater variability. A substantial increase in interpretation confidence was observed following training.

CONCLUSIONS

In conclusion, there is an overall significant training effect on novice examiners' proficiency in LUS image interpretation. For future directions, it is recommended to investigate the training effect on the proficiency from ultrasound image acquisition to interpretation.

Technical Validation of Ultrasound Assessment of the Thyroid Gland in Cattle

Little is known about thyroid diseases in ruminants, probably due to the lack of diagnosis techniques developed in this species. However, thyroid ultrasound (TU) is widely used in human and in companion animal's medicine. It is a cheap and non-invasive examination, which allows for the identification of thyroid structures or diffuse diseases. The aim of this study was to evaluate the accuracy of TU in five calves and five cows through inter- and intra-observer repeatability. The size of the thyroid gland was measured from three views: left sagittal, right sagittal and transverse; nine measurements per view. The intra-observer coefficient was calculated for each observer. For the inter-observer, the first observer was a board-certified imagist (European College of Veterinary Diagnostic Imaging diplomate), the second was a board-certified specialist in bovine and herd management (European College of Bovine Health Managementdiplomate) and the third was an in-trained veterinarian for the TU. They each scanned the thyroid gland successively, following the same method. The intra-observer variabilities for observers 1, 2 and 3 were 8.22%, 5.53%, 5.38%, and 7.18%, 8.65% and 6.36%, respectively, for calves and cows. The inter-observer variability for calves was 10.4% and for cows, 11.8%. This study confirms the feasibility of repeatable intra- and inter-observer TU-estimated measurements in cattle.

Ultrasound imaging in thyroid nodule diagnosis, therapy, and follow-up: Current status and future trends

Ultrasound, the primary imaging modality in thyroid nodule management, suffers from drawbacks including: high inter- and intra-observer variability, limited field-of-view and limited functional imaging. Developments in ultrasound technologies are taking place to overcome these limitations, including three-dimensional-Doppler, -elastography, -nodule characteristics-extraction, and novel machine-learning algorithms. For thyroid ablative treatments and biopsies, perioperative use of three-dimensional ultrasound opens a new field of research. This review provides an overview of the current and future applications of ultrasound, and discusses the potential of new developments and trends that may improve the diagnosis, therapy, and follow-up of thyroid nodules.

Matrix 3D ultrasound-assisted thyroid nodule volume estimation and radiofrequency ablation: a phantom study

Background

Two-dimensional (2D) ultrasound is well established for thyroid nodule assessment and treatment guidance. However, it is hampered by a limited field of view and observer variability that may lead to inaccurate nodule classification and treatment. To cope with these limitations, we investigated the use of real-time three-dimensional (3D) ultrasound to improve the accuracy of volume estimation and needle placement during radiofrequency ablation. We assess a new 3D matrix transducer for nodule volume estimation and image-guided radiofrequency ablation.

Methods

Thirty thyroid nodule phantoms with thermochromic dye underwent volume estimation and ablation guided by a 2D linear and 3D mechanically-swept array and a 3D matrix transducer.

Results

The 3D matrix nodule volume estimations had a lower median difference with the ground truth (0.4 mL) compared to the standard 2D approach (2.2 mL, p < 0.001) and mechanically swept 3D transducer (2.0 mL, p = 0.016). The 3D matrix-guided ablation resulted in a similar nodule ablation coverage when compared to 2D-guidance (76.7% versus 80.8%, p = 0.542). The 3D mechanically swept transducer performed worse (60.1%, p = 0.015). However, 3D matrix and 2D guidance ablations lead to a larger ablated volume outside the nodule than 3D mechanically swept (5.1 mL, 4.2 mL (p = 0.274), 0.5 mL (p < 0.001), respectively). The 3D matrix and mechanically swept approaches were faster with 80 and 72.5 s/mL ablated than 2D with 105.5 s/mL ablated.

Conclusions

The 3D matrix transducer estimates volumes more accurately and can facilitate accurate needle placement while reducing procedure time.

A review of sonographic thyroid volume and iodine sufficiency in children: An Australian perspective

Sonographic measurement of the thyroid gland volume is a safe and reliable method for epidemiologic studies in iodine deficiency disorders. Several factors such as age, sex and anthropometric characteristics are known to be the determinants of thyroid gland size but the most widely studied is the effect of insufficient iodine intake. Low iodine intake induces enlargement of the thyroid gland known as goitre. The assessment of urinary iodine concentration alone is not reliable as it can vary daily within individuals. Urinary iodine concentration in conjunction with sonographic thyroid gland measurements is a widely used method of thyroid gland assessment. Establishment of normative thyroid volume is essential for the assessment of iodine deficiency disorders, and studies have been conducted in several countries. These studies have shown that thyroid gland volumes are likely population-specific even in iodine-sufficient countries limiting the effectiveness of international reference ranges. Based on currently available data of sonographic thyroid gland volume measurements and how they vary across populations of school children, this review argues for the establishment of population-specific reference ranges in regions such as Australia, which are now considered iodine-sufficient.

Intraobserver and Interobserver Variability in Ultrasound Measurements of Thyroid Nodules

OBJECTIVES

The purpose of this study was to assess the intraobserver and interobserver variability in ultrasound (US) measurements of thyroid nodules.

METHODS

We performed a prospective study of the US examinations of 73 patients with 122 thyroid nodules greater than 5 mm in size. Ultrasound measurements in 4 dimensions (anteroposterior, transverse, longitudinal, and maximum diameters) and measurement of the estimated volume (using the ellipsoid formula) of each thyroid nodule were performed twice by 2 independent radiologists (A and B, with 10 years and 6 months of experience, respectively). The intraobserver and interobserver variability in measurements of thyroid nodules was assessed by a Bland-Altman analysis of agreement. The absolute values for intraobserver and interobserver variability were compared by a paired t test.

RESULTS

The 95% intraobserver and interobserver limits of agreement for the anteroposterior, transverse, longitudinal, and maximum diameters and estimated volume of thyroid nodules were ±18.2%, ± 14.3%, and ±21.0%; ± 17.2%%, ± 17.3%, and 18.2%; ± 14.6%, ± 15.5%, and ±22.3%; ± 13.8%, ± 15.5%, and ±19.6%; and ±30.2%, ± 27.7%, and ±44.1%, respectively. The absolute values for intraobserver variability were lower than those for interobserver variability for all measurements.

CONCLUSIONS

There was considerable intraobserver and interobserver variability in US measurement of thyroid nodules, which must be taken into account during follow-up US examinations of patients with thyroid nodules.

3D ultrasound DICOM data of the thyroid gland

Purpose: It has recently become possible to generate and archive three-dimensional ultrasound (3D-US) volume data with the DICOM standard Enhanced Ultrasound Volume Storage (EUVS). The objective of this study was to examine the application of the EUVS standard based on the example of thyroid ultrasound. Patients, methods: 32 patients, who were referred for thyroid diagnosis, were given a 3D-US examination of the thyroid gland (GE Voluson E8, convex 3D probe RAB4–8-D). The 3D data sets were exported to EUVS. Necessary additions to DICOM entries and transformation into an established DICOM standard were carried out. The visual assessment and volume measurements were performed by two experts on nuclear medicine using standard software in our hospital. Results: In 24/32 (75%) of the patients, the whole organ was successfully recorded in a single 3D scan; in 8/32 (25%), only part of organ could be covered. In all cases, 3D-US data could be exported and archived. After supplementing the DICOM entry Patient Orientation and transformation into the DICOM PET format, 3D-US data could be displayed in the correct orientation and size at any viewing workstation and any web browser-based PACS viewer. Afterwards, 3D processing such as multiplanar reformation, volumetric measurements and image fusion with data of other cross sectional modalities could be performed. The intraclass correlation of the volume measurements was 0,94 and the interobserver variability was 5.7%. Conclusion: EUVS allows the generation, distribution and archiving of 3D-US data of the thyroid, facilitates a second reading by another physician and creates conditions for advanced 3D processing using routine software

Time efficient 124I-PET volumetry in benign thyroid disorders by automatic isocontour procedures: mathematic adjustment using manual contoured measurements in low-dose CT

BACKGROUND

Benign thyroid diseases are widely common in western societies. However, the volumetry of the thyroid gland, especially when enlarged or abnormally formed, proves to be a challenge in clinical routine. The aim of this study was to develop a simple and rapid threshold-based isocontour extraction method for thyroid volumetry from (124)I-PET/CT data in patients scheduled for radioactive iodine therapy.

METHODS

PET/CT data from 45 patients were analysed 30 h after 1 MBq (124)I administration. Anatomical reference volume was calculated using manually contoured data from low-dose CT images of the neck (MC). In addition, we applied an automatic isocontour extraction method (IC0.2/1.0), with two different threshold values (0.2 and 1.0 kBq/ml), for volumetry of the PET data-set. IC0.2/1.0 shape data that showed significant variation from MC data were excluded. Subsequently, a mathematical correlation using a model of linear regression with multiple variables and step-wise elimination (mIC0.2/1.0), between IC0.2/1.0 and MC, was established.

RESULTS

Data from 41 patients (IC0.2), and 32 patients (IC1.0) were analysed. The mathematically calculated volume, mIC, showed a median deviation from the reference (MC), of ±9 % (1-54 %) for mIC0.2 and of ±8.2 % (1-50 %) for mIC1.0 CONCLUSION: Contour extraction with both, mIC1.0 and mIC0.2 gave rapid and reliable results. However, mIC0.2 can be applied to significantly more patients (>90 %) and is, therefore, deemed to be more suitable for clinical routine, keeping in mind the potential advantages of using (124)I-PET/CT for the preparation of patients scheduled for radioactive iodine therapy.

Multimodal evaluation of 2-D and 3-D ultrasound, computed tomography and magnetic resonance imaging in measurements of the thyroid volume using universally applicable cross-sectional imaging software: a phantom study

A precise estimate of thyroid volume is necessary for making adequate therapeutic decisions and planning, as well as for monitoring therapy response. The goal of this study was to compare the precision of different volumetry methods. Thyroid-shaped phantoms were subjected to volumetry via 2-D and 3-D ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). The 3-D US scans were performed using sensor navigation and mechanical sweeping methods. Volumetry calculation ensued with the conventional ellipsoid model and the manual tracing method. The study confirmed the superiority of manual tracing with CT and MRI volumetry of the thyroid, but extended this knowledge also to the superiority of the 3-D US method, regardless of whether sensor navigation or mechanical sweeping is used. A novel aspect was successful use of the same universally applicable cross-imaging software for all modalities.

3D ultrasonography is as accurate as low-dose CT in thyroid volumetry

AIM

The purpose of this study was to compare thyroid volumetry by three-dimensional mechanically swept ultrasonography (3DmsUS) and low-dose computed tomography (ldCT).

PATIENTS, METHODS

30 subjects referred for radioiodine therapy of benign thyroid diseases were subjected to 3DmsUS and ldCT. A prerequisite of 3DmsUS analyses was that the scans had to capture the entire thyroid, excluding therefore cases with a very large volume or retrosternal portions. The 3DmsUS data were transformed into a DICOM format, and volumetry calculations were performed via a multimodal workstation equipped with standard software for cross-sectional imaging. Volume was calculated applying both the ellipsoid model and a manually tracing method. Statistical analyses included 95% confidence intervals (CI) of the means and limits of agreement according to Bland and Altman, the latter including 95% of all expected values.

RESULTS

Volumetric measurements by 3DmsUS and ldCT resulted in very high, significant correlation coefficients, r = 0.997 using the ellipsoid model and r = 0.993 with the manually tracing method. The mean relative differences of the two imaging modalities proved very small (-1.2±4.0% [95% CI -2.62; 0.28] using the ellipsoid model; -1.1±5.2% [95% CI -2.93; 0.80] using the manually tracing method) and the limits of agreement sufficiently narrow (-9.1% to 6.8%; -11.3% to 9.2%, respectively).

CONCLUSION

For moderately enlarged thyroids, volumetry with 3DmsUS proved comparable to that of ldCT, irrespective of whether the ellipsoid model or the manually tracing method was applied. Thus, 3DmsUS qualifies as a potential alternative to ldCT, provided that the organ is completely accessible. The use of a standard workstation for cross-sectional imaging with routine software did not prove problematic.

Use of spiral computed tomography volumetry for determining the operative approach in patients with Graves' disease

BACKGROUND

The purposes of the present study were to assess (1) the correlation between the weight of the postoperative thyroid specimen and the spiral computed tomography (CT) volumetry results of the thyroid gland in patients with Graves' disease, and (2) the utility of CT volumetry for determining the operative approach.

METHODS

From 2009 to 2010, a total of 56 patients with Graves' disease underwent total or subtotal thyroidectomy. An enhanced spiral CT was taken in all patients prior to the operation. From 2.5 mm-thick slices of the thyroid gland, the surface area was calculated to measure the volume of the thyroid gland. The glandular volume was compared to the weight of the postoperative thyroid specimen.

RESULTS

A total of 42 and 14 patients underwent total and subtotal thyroidectomy, respectively. The mean weight of the postoperative thyroid specimen was 43.9 ± 33.4 g, and the mean volume obtained by CT volumetry was 44.2 ± 32.8 mL. A good correlation was observed between the weight of the postoperative thyroid specimen and the volume calculated by CT (r = 0.98, p < 0.001). When 100 mL was set as the higher cut-off value of the thyroid volume for minimally invasive thyroid surgery, the estimated blood loss showed a significant difference between the >100 mL and the ≤100 mL groups (608.3 ± 540.8 vs. 119.7 ± 110.4 mL; p = 0.036).

CONCLUSIONS

Spiral CT volumetry may be used to measure the thyroid volume reliably in patients with Graves' disease. For cases in which surgery is indicated in patients with Graves' disease, CT volumetry provides useful information from which to determine the operative approach. One hundred milliliter or less of thyroid volume in CT volumetry is recommended to perform minimally invasive thyroid surgery.

Relative effect potency estimates of dioxin-like activity for dioxins, furans, and dioxin-like PCBs in adults based on two thyroid outcomes

BACKGROUND

Toxic equivalency factors (TEFs) are an important component in the risk assessment of dioxin-like human exposures. At present, this concept is based mainly on in vivo animal experiments using oral dosage. Consequently, the current human TEFs derived from mammalian experiments are applicable only for exposure situations in which oral ingestion occurs. Nevertheless, these "intake" TEFs are commonly-but incorrectly-used by regulatory authorities to calculate "systemic" toxic equivalents (TEQs) based on human blood and tissue concentrations, which are used as biomarkers for either exposure or effect.

OBJECTIVES

We sought to determine relative effect potencies (REPs) for systemic human concentrations of dioxin-like mixture components using thyroid volume or serum free thyroxine (FT4) concentration as the outcomes of interest.

METHODS

We used a benchmark concentration and a regression-based approach to compare the strength of association between each dioxin-like compound and the thyroid end points in 320 adults residing in an organochlorine-polluted area of eastern Slovakia.

RESULTS

REPs calculated from thyroid volume and FT4 were similar. The regression coefficient (β)-derived REP data from thyroid volume and FT4 level were correlated with the World Health Organization (WHO) TEF values (Spearman r = 0.69, p = 0.01 and r = 0.62, p = 0.03, respectively). The calculated REPs were mostly within the minimum and maximum values for in vivo REPs derived by other investigators.

CONCLUSIONS

Our REPs calculated from thyroid end points realistically reflect human exposure scenarios because they are based on chronic, low-dose human exposures and on biomarkers reflecting body burden. Compared with previous results, our REPs suggest higher sensitivity to the effects of dioxin-like compounds.

The role of the resistive index in Hashimoto's thyroiditis: a sonographic pilot study in children

OBJECTIVE

The role of Doppler ultrasonography in the diagnosis of diffuse thyroid diseases is not well established. In particular, Doppler ultrasonography findings in children with Hashimoto's thyroiditis are very limited. We examined gray-scale and Doppler ultrasound findings in Hashimoto's thyroiditis in children in an attempt to understand the feasibility of future prospective controlled studies.

MATERIALS AND METHODS

Twenty-one children with newly diagnosed Hashimoto's thyroiditis were recruited in the study. The patients were euthyroid or had subclinical hypothyroidism at the time of the ultrasonography examination. According to the color Doppler scale developed by Schulz et al., thyroid glands were classified into four patterns based on visual scoring and the mean resistive index (RI), which was calculated via measurements from both lobes, and these results were compared with gray-scale findings.

RESULTS

The mean RI value, calculated as the mean of the RI values of both lobes obtained from each patient, was found to be 0.57 ± 0.05 (range 0.48-0.67) cm/sn. The distribution of thyroid classifications was as follows: Pattern 0, n = 7; Pattern I, n = 6; Pattern II, n = 4; and Pattern III ("thyroid inferno"), n = 4. The mean RI values in patients with normal or near-normal gray-scale findings (n = 10) and patients with more substantial gray-scale changes (n = 11) were not significantly different and were lower than the values in normal children previously presented in the literature.

CONCLUSION

The results indicated that the RI may be more sensitive than other ultrasound parameters for the diagnosis of Hashimoto's thyroiditis.

Data quality and practical challenges of thyroid volume assessment by ultrasound under field conditions - observer errors may affect prevalence estimates of goitre

Background

The ultrasonographic estimation of thyroid size has been advocated as being more precise than palpation to diagnose goitre. However, ultrasound also requires technical proficiency. This study was conducted among Saharawi refugees, where goitre is highly prevalent. The objectives were to assess the overall data quality of ultrasound measurements of thyroid volume (Tvol), including the intra- and inter-observer agreement, under field conditions, and to describe some of the practical challenges encountered.

Methods

In 2007 a cross-sectional study of 419 children (6-14 years old) and 405 women (15-45 years old) was performed on a population of Saharawi refugees with prevalent goitre, who reside in the Algerian desert. Tvol was measured by two trained fieldworkers using portable ultrasound equipment (examiner 1 measured 406 individuals, and examiner 2, 418 individuals). Intra- and inter-observer agreement was estimated in 12 children selected from the study population but not part of the main study. In the main study, an observer error was found in one examiner whose ultrasound images were corrected by linear regression after printing and remeasuring a sample of 272 images.

Results

The intra-observer agreement in Tvol was higher in examiner 1, with an intraclass correlation coefficient (ICC) of 0.97 (95% CI: 0.91, 0.99) compared to 0.86 (95% CI: 0.60, 0.96) in examiner 2. The ICC for inter-observer agreement in Tvol was 0.38 (95% CI: -0.20, 0.77). Linear regression coefficients indicated a significant scaling bias in the original measurements of the AP and ML diameter and a systematic underestimation of Tvol (a product of AP, ML, CC and a constant). The agreement between re-measured and original Tvol measured by ICC (95% CI) was 0.76 (0.71, 0.81). The agreement between re-measured and corrected Tvol measured by ICC (95% CI) was 0.97 (0.96, 0.97).

Conclusions

An important challenge when using ultrasound to assess thyroid volume under field conditions is to recruit and train qualified personnel to perform the measurements. Methodological studies are important to assess data quality and can facilitate statistical corrections and improved estimates.

Thyroid volumetric quantification: comparative evaluation between conventional and volumetric ultrasonography

OBJECTIVE

Thyroid volume quantification is an important parameter for radiotherapy dosing in cases of major thyroid diseases such as thyroiditis and carcinoma. In clinical practice, this calculation is performed by means of ultrasonography on the basis of an ellipsoid formula obtained from the 3 axes. The aim of our study was to compare the accuracy of volume calculation between B-mode ultrasonography and volumetric ultrasonography (VUS).

METHODS

Between April and May 2007, 27 consecutive patients selected for thyroidectomy were prospectively evaluated. One expert ultrasound operator calculated each thyroid volume with standard B-mode ultrasonography on the basis of the 3 axes of each lobe, and then the patients were analyzed with an offline workstation equipped with volumetric probes (VUS). On the offline workstation, 2 separate blinded operators (VUS1 and VUS2) calculated the thyroid volume with virtual organ computer-aided analysis. Data acquired were then compared with pathologic anatomy (PA).

RESULTS

The mean time for B-mode analysis was 6 minutes, whereas VUS analysis needed a mean time of 16.5 minutes. Interobserver variability between the median VUS1 and VUS2 measurements was 0.36 mL (interquartile range [IQR], -0.79 to 0.37 mL; P < .156). The median variability between B-mode ultrasonography and PA was -9.6 mL (IQR, -16.7 to 1.5 mL; P < .001), and that between VUS and PA was -2.87 mL (IQR, -11.97 to 9.51 mL; P = .019). The overall performance of B-mode ultrasonography in comparison with PA was -29.1% (IQR, -47.5% to -5.9%), and that of VUS in comparison with PA was -6.3% (IQR, -26.3 to 13.7%; P < .001).

CONCLUSIONS

Volumetric ultrasonography is a valid tool that compares better with PA than does B-mode ultrasonography.

Interobserver and Intraobserver Variability in the Sonographic Measurement of the Size of the Thyroid Gland by Extended Field-of-View Sonography

Significant intra- and interobserver variation has been reported for estimating the dimensions and the volume of the thyroid gland by conventional sonography in adults. This study aimed to assess the role of extended field-of-view (EFOV) sonography for evaluating the size of the thyroid gland. The mediolateral, anteroposterior, and craniocaudal diameters of both thyroid lobes as well as total thyroid volumes of 30 female patients with the clinical diagnosis of goiter were measured three times by three radiologists with the EFOV sonography technique. Based on these findings, the correlation between the measurements of different operators and different measurements of the same operator was investigated. The interobserver variations for craniocaudal diameters of the right and left thyroid lobes were 3.3% ± 1.9% (mean ± SD) and 2.8% ± 1.3% (mean ± SD), respectively ( P = .012), which were lower than the variations calculated for transverse and mediolateral diameters. The interobserver variation for the calculation of the total glandular volume was 6.3% ± 3.8% (mean ± SD). The intraobserver variations for the three radiologists assessing the total thyroid volume were 4.9% ± 3.0%, 4.2% ± 2.4%, and 4.5% ± 1.7% (all mean ± SD), respectively ( P = .521). EFOV sonography should be considered as an alternative technique for the dimension measurements of the thyroid gland, particularly in cases with goiter.

A novel thyroid phantom for ultrasound volumetry: determination of intraobserver and interobserver variability

A novel thyroid ultrasound phantom with tissue-equivalent characteristics was designed consisting of two lobes with three lesions each. One set of lesions is manufactured with a -5 dB echo difference to the surrounding tissue, the other with -10 dB. This phantom was used as a standardized measuring object for reproducibility of two-dimensional and three-dimensional ultrasound volumetry and for an interobserver and intraobserver variability study. For the variability study, nine experienced physicians scanned all specimen three times. Each time the volumes were calculated using the ellipsoid method. A three-dimensional ultrasound scan of each specimen was performed to evaluate all volumes by multiplanar volume approximation. The results of these volume data were compared to the known true volumes. The interobserver variability ranged from -13.4% to 11.9% (median, 0.7%); the intraobserver variability from -9.1% to 16.4% (median, 3.6%). The systematic error as calculated from the total mean of all specimens is 0.5% for the interobserver variability and 4.1% for the intraobserver variability. The phantom can be used for training purposes, to improve the skills of the examining physicians by simulating real thyroid morphology, to provide a standardized reference object for long-term quality control of conventional ultrasound scanners, and the determination of the accuracy and reproducibility of volumetry using three-dimensional ultrasound systems.

Interobserver variation for ultrasound determination of thyroid nodule volumes

Thyroid ultrasound is used in the routine clinical assessment and the follow-up of thyroid disorders. The follow- up of patients with thyroid nodules is mostly based on thyroid nodule volume determinations performed by different observers. However, for the judgment of treatment effects there is uncertainty about the interobserver variation of thyroid nodule volume measurements by ultrasound because there are no prospective blinded studies available comparing the interobserver variation in thyroid nodule volume measurement. The aim of our study was therefore to determine the variation of thyroid nodule volume determinations for different observers. We conducted a prospective blinded trial. Our study population consisted of 42 probands (8 men, 34 women) with an uniform distribution of thyroid nodule sizes (25 uninodular and 17 multinodular thyroid glands). We compared the results of 3 ultrasonographers with certified experience in thyroid ultrasound. The interobserver variation for the determination of thyroid nodule volume (n = 38) was 48.96% for the ellipsoid method and 48.64% for the planimetric method. The interobserver variation for determining thyroid volume (n = 40) was 23.69% for the ellipsoid method and 17.82% for the planimetric method. A regression analysis revealed that the probability for the identification of the same nodule in nodular thyroids by all sonographers is 90%, if the nodule is at least 15mm in greatest diameter. Future investigations should not describe changes in nodule volume less than 50% as therapy effects because only volume changes of at least 49% or more can be interpreted as nodule shrinkage or growth. Reporting of nodule volume modification 50% or more and lack of information for ultrasound procedures introduce a bias in studies evaluating the effects of nodule treatments. The clinical interpretation of a shrinking/growing thyroid nodule based on volume determinations by ultrasound is not well established because it is difficult to reproduce a two-dimensional image plane for follow-up studies.

Interobserver and intraobserver variability in the assessment of pulmonary nodule size on CT using film and computer display methods

RATIONALE AND OBJECTIVES

A critical element in determining biologic behavior of pulmonary nodules is volume and temporal volume change. We evaluate variability in nodule volume among readers and measuring methods.

MATERIALS AND METHODS

55 small (<2 cm) lung nodules were measured in long- and short-axis dimensions independently by 4 radiologists, using 3 methods: 1) hard copy, 2) GE Advantage Windows workstation (GE Healthcare, Milwaukee, WI), 3) Siemens IMACS workstation (Siemens Medical Systems, Iselan, NJ). Nodule margin was recorded as smooth, lobulated, or spiculated. Volume was calculated from diameter measurements. Variability in nodule volume was evaluated within each reader, between readers, and across measurement tools.

RESULTS

Mean nodule short-axis diameter was 5.3 mm; mean long-axis diameter 7.2 mm. There was statistically significant variation among readers and measurement method for nodule volume. Volume was significantly larger using hard-copy measurements (51.9%-54.1% variation; P < .0001) than either workstation, and not different between workstations. There was greater intraobserver variability in volume using the hard-copy method, and no difference between workstation methods. Volumes based on measurements from one reader were consistently lower than those from other readers (P = < .001, .003, and .02); volume was consistently larger for another reader (P < .0001, .03, and .12). Reader agreement for nodule margin was good to excellent.

CONCLUSION

Considerable interobserver and intraobserver variability in measuring nodules exists using hard-copy and computer tools. Since a small change in diameter indicates a much larger change in volume, this may be significant when using early repeat CT to follow small pulmonary nodules. Computer-aided diagnostic tools that reproducibly measure nodule volume are strongly needed.

Three-dimensional ultrasound measurement of thyroid volume in asymptomatic male Chinese

This study was undertaken to determine the accuracy and reliability of volume measurements using 3-D ultrasound (US). Variation of thyroid gland volume with age in asymptomatic Chinese men was also investigated. Volumetric measurements of the phantoms and thyroid glands were performed with a commercially available US machine in conjunction with the 3-D SonoScan Pro workstation. Ten tissue phantoms with volumes of 1.5 to 6.5 mL were measured with 3-D US. A water displacement method was used to measure the actual volume of the phantoms. The measured volumes were compared to the actual volumes. Volumes were measured by four operators to investigate interobserver variation. Thyroid US examinations were performed in 38 asymptomatic male Chinese subjects ages 21 to 72 years. The subjects were categorized into four age groups. In each subject, the volume of the left and right lobes and the isthmus of the thyroid gland were measured with 3-D US, and any variation with age was evaluated. Results showed that the actual volume of the tissue phantoms was highly correlated with the volume measured by the four operators (r = 0.9912 to 0.9977, p < 0.05). Interobserver variation in the volumetric measurements of the tissue phantoms was not significant (ICC = 0.9861). The range of thyroid volume of the subjects was 8.81 to 17.25 mL (mean 12.78 +/- SD 2.483), and there was no significant difference in thyroid volume between subjects of different age groups (p > 0.05). 3-D US is an accurate and reliable method by which to measure thyroid volume.

Determinants of Thyroid Volume in Schoolchildren: Fat-Free Mass Versus Body Fat Mass—A Cross-Sectional Study

OBJECTIVE

To investigate the relationship between thyroid volume and body composition in schoolchildren 11 to 15 years of age.

METHODS

We conducted a cross-sectional study of 126 girls and 86 boys who were living in an urban area and receiving iodine supplementation. The medical history was reviewed. Weight, height, body fat, fat-free mass, and total body water were measured by using a tetrapolar bioelectrical impedance analyzer. Body mass index and body surface area were calculated. Iodine excretion was measured in a morning urine sample by spectrophotometry. Thyroid volume was measured with use of an ultrasound scanner. Thyroid-stimulating hormone was measured from capillary blood samples with use of a neonatal human thyrotropin kit.

RESULTS

All study participants were euthyroid. No study participant had urinary iodine excretion of less than 10 mg/L, and two thirds of the study group had iodine excretion of more than 100 mg/dL. Mean thyroid volume increased from 5.35 +/- 1.11 mL in boys at age 11 years to 8.52 +/- 3.32 mL in boys at age 15 years and from 5.95 +/- 1.70 mL to 7.53 +/- 1.92 mL in girls of corresponding ages. In both sexes, thyroid volume correlated better with height (r = 0.33 in girls and 0.50 in boys), weight (r = 0.35 and 0.43, respectively), and body surface area (r = 0.38 and 0.50, respectively) than with body mass index (r = 0.26 and 0.16, respectively). Thyroid volume showed a significant correlation with fat-free mass (r = 0.39 in girls and 0.49 in boys) and no significant correlation with body fat in both girls and boys.

CONCLUSION

Thyroid volume is dependent on body size and therefore on growth variables. It depends on fat-free mass as a relatively precise measure of body size and is not related to the fat mass.

Accuracy of three-dimensional ultrasound for thyroid volume measurement in children and adolescents

The aim of this study was to estimate accuracy, intraobserver variability, and repeatability of thyroid volume measurement by ultrasound using conventional two-dimensional ellipsoid model (2D US) and manual planimetry of three-dimensional images (3D US). The sonographic images of 47 children with thyroid nodular pathology who were referred for thyroid surgery in Belarus were evaluated prospectively. Two-dimensional images were acquired using the ultrasound scanner with 7.5-MHz linear probe. Three-dimensional data sets were created using three-dimensional system, FreeScan. For each patient thyroid volume was measured three times using both two- and three-dimensional methods. Results of volume estimation were then compared to the volume of thyroid gland determined after surgery. Standardized difference between thyroid volume estimated by ultrasound and surgery (mean +/- standard deviation (SD), %) for 3D and 2D US methods was 1.8 +/- 5.2% and 3.2 +/- 15.3%, respectively. The 3D US has lower intraobserver variability (3.4%) and higher repeatability (96.5%) than 2D US with 14.4% variability and 84.8% repeatability (p < 0.001). In conclusion, three-dimensional sonography allows accurate measurement of thyroid volume with low intraobserver variability and high repeatability.

Technical observations on the assessment of thyroid volume by palpation and ultrasonography

OBJECTIVE

The diagnosis of increased thyroid volume, in field studies of goiter prevalence, has been based on inspection and palpation of the thyroid. Because clinical examination, compared with ultrasonography, has a low positive predictive value for the presence of a goiter, it overestimates goiter prevalence. It also has the problem of marked interobserver variability. This led to the use of ultrasonographic scanners in field studies. The problem with the latter is the cost and skill required for the complicated linear measures and their translation to lobe volume and then thyroid volume. We studied patients to determine whether this complicated assessment could be simplified.

METHODS

We studied palpation in 31 patients with thyroid disease in whom individual ultrasonographic linear dimensions were also obtained in their 62 thyroid lobes to determine their relationship to thyroid lobe volume.

RESULTS

Palpation revealed poor discrimination of smaller thyroid sizes as determined by ultrasonography. Stepwise linear regression (backward selection) revealed that of the 3 thyroid dimensions, only the lateromedial dimension of the thyroid lobe had a significant correlation to lobe volume, accounting for 82.5% of the variability in lobe volume. The lobe volume (in milliliters) is given by the lobe lateromedial dimension (in centimeters) multiplied by 13 minus a constant of 15.

CONCLUSIONS

A simple linear ultrasonographic measurement of the thyroid lateromedial dimension, which can be done with little training, is as good as more complicated measures of thyroid volume estimation by ultrasonography and is an ideal method for identifying goiters in field surveys.

Reducing inter-observer variation in thyroid volume calculation using a new formula and technique

OBJECTIVE

Ultrasound (US) measurement of thyroid volume is used in diagnosis and follow-up of patients with thyroid disease. We assessed a new formula and technique for thyroid volume calculation, based on an automatically continuous trace transverse surface area (aTSA) calculation, to ascertain where this technique could reduce inter-observer variation.

METHODS

Three observers with a different level of US expertise, using a 12-5 MHz linear transducer, examined 25 volunteers. Inter-observer variations were calculated for diameter measurements and for the thyroid lobe volume calculations using the single factor ANOVA method.

RESULTS

Using the new technique and formula, no statistically significant differences existed, in contradistinction to using the classical formula for an ellipsoid (P=0.02).

CONCLUSION

When thyroid volume measurements are required, we recommend using a new method of thyroid volume calculation based on the use of an automatically calculated continuous trace aTSA measurement to avoid significant inter-observer variation in calculation of thyroid lobe volumes.

Basic anatomical and physiological data for use in radiological protection: reference values. A report of age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. ICRP Publication 89

This report presents detailed information on age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. These reference values provide needed input to prospective dosimetry calculations for radiation protection purposes for both workers and members of the general public. The purpose of this report is to consolidate and unify in one publication, important new information on reference anatomical and physiological values that has become available since Publication 23 was published by the ICRP in 1975. There are two aspects of this work. The first is to revise and extend the information in Publication 23 as appropriate. The second is to provide additional information on individual variation among grossly normal individuals resulting from differences in age, gender, race, or other factors. This publication collects, unifies, and expands the updated ICRP reference values for the purpose of providing a comprehensive and consistent set of age- and gender-specific reference values for anatomical and physiological features of the human body pertinent to radiation dosimetry. The reference values given in this report are based on: (a) anatomical and physiological information not published before by the ICRP; (b) recent ICRP publications containing reference value information; and (c) information in Publication 23 that is still considered valid and appropriate for radiation protection purposes. Moving from the past emphasis on 'Reference Man', the new report presents a series of reference values for both male and female subjects of six different ages: newborn, 1 year, 5 years, 10 years, 15 years, and adult. In selecting reference values, the Commission has used data on Western Europeans and North Americans because these populations have been well studied with respect to antomy, body composition, and physiology. When appropriate, comparisons are made between the chosen reference values and data from several Asian populations. The first section of the report provides summary tables of all the anatomical and physiological parameters given as reference values in this publication. These results give a comprehensive view of reference values for an individual as influenced by age and gender. The second section describes characteristics of dosimetric importance for the embryo and fetus. Information is provided on the development of the total body and the timing of appearance and development of the various organ systems. Reference values are provided on the mass of the total body and selected organs and tissues, as well as a number of physiological parameters. The third section deals with reference values of important anatomical and physiological characteristics of reference individuals from birth to adulthood. This section begins with details on the growth and composition of the total body in males and females. It then describes and quantifies anatomical and physiological characteristics of various organ systems and changes in these characteristics during growth, maturity, and pregnancy. Reference values are specified for characteristics of dosimetric importance. The final section gives a brief summary of the elemental composition of individuals. Focusing on the elements of dosimetric importance, information is presented on the body content of 13 elements: calcium, carbon, chloride, hydrogen, iodine, iron, magnesium, nitrogen, oxygen, potassium, sodium, sulphur, and phosphorus.