The use of three-dimensional ultrasound for thyroid volumetry

Inter-observer variation in two-dimensional and three-dimensional ultrasound measurement of papillary thyroid microcarcinoma

BACKGROUNDS

The reliable ultrasound (US) measurements of papillary thyroid microcarcinoma (PTMC) are very important during active surveillance. This prospective study was design to investigate the inter-observer reliability and agreement of two- dimensional ultrasound(2DUS) and three-dimensional ultrasound(3DUS) in the measurement of maximum diameter and volume for PTMC.

METHODS

This prospective study included 51 consecutive patients with solitary PTMC confirmed by biopsy. Two independent observers performed measurements of each tumor using a standardized measurement protocol. The maximum diameter was the largest one of the three diameters measured on the largest transverse and longitudinal 2DUS images. 2DUS volume was calculated using ellipsoid formula method. The virtual organ computer aided analysis(VOCAL) was used to determine 3DUS volume. The inter-observer reliability was assessed using intraclass correlation coefficient(ICC) with 95% confidence intervals(CIs). Bland-Altman analysis was used to evaluate agreement, and expressed as a bias with 95% limits of agreement(LOA).

RESULTS

The maximum diameter was 0.78 ± 0.14 cm. Volume measured by 3DUS was significantly smaller than that by 2DUS(0.163 ± 0.074 cm3 vs. 0.175 ± 0.078 cm3, P = 0.005). The ICCs of inter-observer reliability of maximum diameter, 2DUS volume and 3DUS volume was 0.922(0.864-0.955), 0.928(0.874-0.959), and 0.974(0.955-0.985), respectively. The ICCs of 2DUS and 3DUS volume was 0.955(0.909-0.976). The inter-observer agreement of maximum diameter, 2DUS volume and 3DUS volume was 1.096(0.7322 to 1.459), 1.008(0.5802-1.435), and 1.011(0.7576-1.265), respectively. The inter-observer agreement of 2DUS and 3DUS volume was 1.096(0.7322 to 1.459).

CONCLUSION

Maximum diameter had the lowest degree of observer variation among all the measurements. Volume measured by 3DUS had lower variability and higher repeatability than that by 2DUS, which might be helpful to provide more reliable estimates of tumor size for PTMC.

The EANM guideline on radioiodine therapy of benign thyroid disease

This document provides the new EANM guideline on radioiodine therapy of benign thyroid disease. Its aim is to guide nuclear medicine physicians, endocrinologists, and practitioners in the selection of patients for radioiodine therapy. Its recommendations on patients' preparation, empiric and dosimetric therapeutic approaches, applied radioiodine activity, radiation protection requirements, and patients follow-up after administration of radioiodine therapy are extensively discussed.

Optimization of Thyroid Volume Determination by Stitched 3D-Ultrasound Data Sets in Patients with Structural Thyroid Disease

Ultrasound (US) is the most important imaging method for the assessment of structural disorders of the thyroid. A precise volume determination is relevant for therapy planning and outcome monitoring. However, the accuracy of 2D-US is limited, especially in cases of organ enlargements and deformations. Software-based "stitching" of separately acquired 3D-US data revealed precise volume determination in thyroid phantoms. The purpose of this study is to investigate the feasibility and accuracy of 3D-US stitching in patients with structural thyroid disease. A total of 31 patients from the clinical routine were involved, receiving conventional 2D-US (conUS), sensor-navigated 3D-US (3DsnUS), mechanically-swept 3D-US (3DmsUS), and I-124-PET/CT as reference standard. Regarding 3DsnUS and 3DmsUS, separately acquired 3D-US images (per thyroid lobe) were merged to one comprehensive data set. Subsequently, anatomical correctness of the stitching process was analysed via secondary image fusion with the I-124-PET images. Volumetric determinations were conducted by the ellipsoid model (EM) on conUS and CT, and manually drawn segmental contouring (MC) on 3DsnUS, 3DmsUS, CT, and I-124-PET/CT. Mean volume of the thyroid glands was 44.1 ± 25.8 mL (I-124-PET-MC = reference). Highly significant correlations (all p < 0.0001) were observed for conUS-EM (r = 0.892), 3DsnUS-MC (r = 0.988), 3DmsUS-MC (r = 0.978), CT-EM (0.956), and CT-MC (0.986), respectively. The mean volume differences (standard deviations, limits of agreement) in comparison with the reference were -10.50 mL (±11.56 mL, -33.62 to 12.24), -3.74 mL (±3.74 mL, -11.39 to 3.78), and 0.62 mL (±4.79 mL, -8.78 to 10.01) for conUS-EM, 3DsnUS-MC, and 3DmsUS-MC, respectively. Stitched 3D-US data sets of the thyroid enable accurate volumetric determination even in enlarged and deformed organs. The main limitation of high time expenditure may be overcome by artificial intelligence approaches.

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.

Tracked 3D ultrasound and deep neural network-based thyroid segmentation reduce interobserver variability in thyroid volumetry

Thyroid volumetry is crucial in the diagnosis, treatment, and monitoring of thyroid diseases. However, conventional thyroid volumetry with 2D ultrasound is highly operator-dependent. This study compares 2D and tracked 3D ultrasound with an automatic thyroid segmentation based on a deep neural network regarding inter- and intraobserver variability, time, and accuracy. Volume reference was MRI. 28 healthy volunteers (24—50 a) were scanned with 2D and 3D ultrasound (and by MRI) by three physicians (MD 1, 2, 3) with different experience levels (6, 4, and 1 a). In the 2D scans, the thyroid lobe volumes were calculated with the ellipsoid formula. A convolutional deep neural network (CNN) automatically segmented the 3D thyroid lobes. 26, 6, and 6 random lobe scans were used for training, validation, and testing, respectively. On MRI (T1 VIBE sequence) the thyroid was manually segmented by an experienced MD. MRI thyroid volumes ranged from 2.8 to 16.7ml (mean 7.4, SD 3.05). The CNN was trained to obtain an average Dice score of 0.94. The interobserver variability comparing two MDs showed mean differences for 2D and 3D respectively of 0.58 to 0.52ml (MD1 vs. 2), −1.33 to −0.17ml (MD1 vs. 3) and −1.89 to −0.70ml (MD2 vs. 3). Paired samples t-tests showed significant differences for 2D (p = .140, p = .002 and p = .002) and none for 3D (p = .176, p = .722 and p = .057). Intraobsever variability was similar for 2D and 3D ultrasound. Comparison of ultrasound volumes and MRI volumes showed a significant difference for the 2D volumetry of all MDs (p = .002, p = .009, p <.001), and no significant difference for 3D ultrasound (p = .292, p = .686, p = 0.091). Acquisition time was significantly shorter for 3D ultrasound. Tracked 3D ultrasound combined with a CNN segmentation significantly reduces interobserver variability in thyroid volumetry and increases the accuracy of the measurements with shorter acquisition times.

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.

Variation in thyroid volumes due to differences in the measured length or area of the cross-sectional plane: A validation study of the ellipsoid approximation method using CT images

PURPOSE

This study examined the variation in the thyroid volume determined by the ellipsoid approximation method due to differences in the measured length or area of the cross-sectional plane of CT images.

METHODS

Forty-five patients with Graves' disease were included in this retrospective study. We designated the three-dimensional thyroid volumes extracted manually (V_CT ) as the reference data and calculated five approximate volumes for comparison: (a) the mean volume of 8100 different thyroid volumes depending on the diameter of the cross-sectional plane at the midpoint of the major axis, (V_{ellipsoid,mean} ); (b) the volume using the maximum diameter and its orthogonal diameter, (V_{ellipsoid,maxlength} ); (c) the maximum (V_{ellipsoid,maxvolume} ); (d) minimum (V_{ellipsoid,minvolume} ) of the 8100 thyroid volumes; and (e) the volume determined with an equivalent circle diameter, (V_{ellipsoid,Heywood} ).

RESULTS

Thyroid volumes obtained via the ellipsoid approximation method varied depending on the diameter of the cross-sectional plane and included a mean error of approximately 20%, while the concordance correlation coefficient (CCC) differed for each approximate volume. Among these volumes, V_{ellipsoid,mean} and V_{ellipsoid,Heywood} were in good agreement with V_CT , according to single regression analyses and the resultant CCC values, with mean errors of 0.1% and 10.4%, respectively.

CONCLUSION

While V_{ellipsoid,Heywood} approximated thyroid volumes with vastly reduced errors, we recommend utilizing three-dimensional thyroid volumetry if measurement accuracy is required.

Hormonal Outcomes Following Hemithyroidectomy

OBJECTIVE

To assess hormonal outcomes and thyroid hormone (TH) replacement after hemithyroidectomy (HT).

STUDY DESIGN

Retrospective chart review.

SETTING

Quaternary care hospital system.

METHODS

A retrospective analysis was performed on patients who had an HT at Cleveland Clinic between 2000 and 2010 with outcomes assessed up to 5 years post-HT. Patients with overt hypothyroidism (OH; thyroid-stimulating hormone [TSH] >10 mIU/L, TSH >4.2 mIU/L on thyroid hormone [TH]), subclinical hypothyroidism (SH; TSH >4.2-10 mIU/L, no TH), or euthyroidism (EU; TSH 0.4-4.2 mIU/L, no TH) were compared. Patients with SH who returned to EU were compared to those who continued to have SH. For immediate start on TH, a receiver operating characteristic analysis was performed to determine dosage of TH above which suppression of TSH <0.4 mIU/L was predicted.

RESULTS

We identified 335 patients (average age 51 years, 78% female, median follow-up of 50 months). Of the 210 not immediately started on TH, 32.4% were OH, 13.3% were SH, and 54.3% were EU. EU patients were younger (48 years), had more remaining gland, were less likely to have lymphocytic infiltrate, and had a lower preoperative TSH (1.2 mIU/L). In the SH group, 58.3% of patients normalized their TSH. With immediate TH start, 45% developed suppressed TSH. Those on LT4 >1.05 mcg/kg/d were more likely to suppress (sensitivity 89%).

CONCLUSION

Most patients post-HT will remain EU, and immediate start of TH may lead to TSH suppression. Those with SH may ultimately normalize TSH. These findings together suggest that observation may be a better option than TH replacement after HT.

Automated Segmentation of Thyroid Nodule, Gland, and Cystic Components From Ultrasound Images Using Deep Learning

Sonographic features associated with margins, shape, size, and volume of thyroid nodules are used to assess their risk of malignancy. Automatically segmenting nodules from normal thyroid gland would enable an automated estimation of these features. A novel multi-output convolutional neural network algorithm with dilated convolutional layers is presented to segment thyroid nodules, cystic components inside the nodules, and normal thyroid gland from clinical ultrasound B-mode scans. A prospective study was conducted, collecting data from 234 patients undergoing a thyroid ultrasound exam before biopsy. The training and validation sets encompassed 188 patients total; the testing set consisted of 48 patients. The algorithm effectively segmented thyroid anatomy into nodules, normal gland, and cystic components. The algorithm achieved a mean Dice coefficient of 0.76, a mean true positive fraction of 0.90, and a mean false positive fraction of 1.61×10-6. The values are on par with a conventional seeded algorithm. The proposed algorithm eliminates the need for a seed in the segmentation process, thus automatically detecting and segmenting the thyroid nodules and cystic components. The detection rate for thyroid nodules and cystic components was 82% and 44%, respectively. The inference time per image, per fold was 107ms. The mean error in volume estimation of thyroid nodules for five select cases was 7.47%. The algorithm can be used for detection, segmentation, size estimation, volume estimation, and generating thyroid maps for thyroid nodules. The algorithm has applications in point of care, mobile health monitoring, improving workflow, reducing localization time, and assisting sonographers with limited expertise.

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

Freehand 3-D Ultrasound Imaging: A Systematic Review

Two-dimensional ultrasound (US) imaging has been successfully used in clinical applications as a low-cost, portable and non-invasive image modality for more than three decades. Recent advances in computer science and technology illustrate the promise of the 3-D US modality as a medical imaging technique that is comparable to other prevalent modalities and that overcomes certain drawbacks of 2-D US. This systematic review covers freehand 3-D US imaging between 1970 and 2017, highlighting the current trends in research fields, the research methods, the main limitations, the leading researchers, standard assessment criteria and clinical applications. Freehand 3-D US systems are more prevalent in the academic environment, whereas in clinical applications and industrial research, most studies have focused on 3-D US transducers and improvement of hardware performance. This topic is still an interesting active area for researchers, and there remain many unsolved problems to be addressed.

Prevalence of thyroid disorders in elderly people in Germany. A screening study in a country with endemic goitre

AIM

In a screening study on people of working age the prevalence of morphological thyroid disorders was 33.1 %. It is not known precisely whether this further increases after retirement. The present study aimed to establish whether the increase in the prevalence of morphological and functional thyroid disorders continues beyond working age in elderly citizens.

METHODS

223 participants were recruited in an institute for geriatric rehabilitative medicine. All patients were screened by thyroid ultrasound, measurement of serum levels of thyroid hormones and thyroid related autoantibodies as well as measurement of urinary iodine excretion.

RESULTS

The median thyroid volume was 17 ml (range 4-41 ml) in men and 16 ml (range 0.4-73 ml) in women. 27/59 (46 %) of the men (median age [range]: 77 [58-87] years) and 85/139 (61 %) of the women (median age [range]: 77 [52-97] years), or a total of 112/198 (57 %) residents, showed morphological thyroid abnormalities. There was no clear increase with age. 85 % of the participants without a history of thyroid treatment were euthyroid. 12 % showed a subclinical hyperthyroidism whereas 1 % showed a biochemically manifest hyperthyroidism. 2 % were biochemically hypothyroid. Tg-antibodies was elevated in 10 (5 %) and TPO-antibodies in 18 (9 %) of the patients. Median iodine excretion was 129 µg/l. 41.5 % of the patients showed iodine excretion values below 100 µg/l whereas only 7 % of the patients showed a severe iodine deficiency with an excretion below 50 µg/l.

CONCLUSION

Compared to a previously described population of working age, the prevalence of morphological thyroid disorders does not further increase above the age of 65; thyroid function abnormalities in this iodine sufficient screening population were relatively rare.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS, AMERICAN COLLEGE OF ENDOCRINOLOGY, AND ASSOCIAZIONE MEDICI ENDOCRINOLOGI MEDICAL GUIDELINES FOR CLINICAL PRACTICE FOR THE DIAGNOSIS AND MANAGEMENT OF THYROID NODULES--2016 UPDATE

Thyroid nodules are detected in up to 50 to 60% of healthy subjects. Most nodules do not cause clinically significant symptoms, and as a result, the main challenge in their management is to rule out malignancy, with ultrasonography (US) and fine-needle aspiration (FNA) biopsy serving as diagnostic cornerstones. The key issues discussed in these guidelines are as follows: (1) US-based categorization of the malignancy risk and indications for US-guided FNA (henceforth, FNA), (2) cytologic classification of FNA samples, (3) the roles of immunocytochemistry and molecular testing applied to thyroid FNA, (4) therapeutic options, and (5) follow-up strategy. Thyroid nodule management during pregnancy and in children are also addressed. On the basis of US features, thyroid nodules may be categorized into 3 groups: low-, intermediate-and high-malignancy risk. FNA should be considered for nodules ≤10 mm diameter only when suspicious US signs are present, while nodules ≤5 mm should be monitored rather than biopsied. A classification scheme of 5 categories (nondiagnostic, benign, indeterminate, suspicious for malignancy, or malignant) is recommended for the cytologic report. Indeterminate lesions are further subdivided into 2 subclasses to more accurately stratify the risk of malignancy. At present, no single cytochemical or genetic marker can definitely rule out malignancy in indeterminate nodules. Nevertheless, these tools should be considered together with clinical data, US signs, elastographic pattern, or results of other imaging techniques to improve the management of these lesions. Most thyroid nodules do not require any treatment, and levothyroxine (LT4) suppressive therapy is not recommended. Percutaneous ethanol injection (PEI) should be the first-line treatment option for relapsing, benign cystic lesions, while US-guided thermal ablation treatments may be considered for solid or mixed symptomatic benign thyroid nodules. Surgery remains the treatment of choice for malignant or suspicious nodules. The present document updates previous guidelines released in 2006 and 2010 by the American Association of Clinical Endocrinologists (AACE), American College of Endocrinology (ACE) and Associazione Medici Endocrinologi (AME).

Off-site evaluation of three-dimensional ultrasound for the diagnosis of thyroid nodules: comparison with two-dimensional ultrasound

OBJECTIVES

We compared the diagnostic performance of off-site evaluation between prospectively obtained 3D and 2D ultrasound for thyroid nodules.

METHODS

3D and 2D ultrasonographies were preoperatively obtained from 85 consecutive patients (mean age, 51 years; age range, 28-83 years) who were referred for a total thyroidectomy. Three radiologists independently evaluated 3D and 2D images of 91 pathologically confirmed thyroid nodules (30 benign and 61 malignant nodules) for nodule characterization. Diagnostic performance, interobserver agreement and time for scanning were compared between 3D and 2D.

RESULTS

3D had significantly higher sensitivities than 2D for predicting malignancy (78.7 % vs. 61.2 %, P < 0.01) and extrathyroidal extension (66.7 % vs. 46.4 %, P = 0.03) in malignancy. In terms of specificities, there were no statistically significant differences between 2D and 3D for predicting malignancy (78.4 % vs. 74.8 %, P = 1.00) and extrathyroidal extension (63.6 % vs. 57.6 %, P = 0.46). With respect to interobserver agreement, 3D showed moderate agreement (κ = 0.53) for predicting extrathyroidal extension in malignancy compared with 2D ultrasound, which showed fair agreement (κ = 0.37). 3D saved time (30 ± 56.52 s) for scanning compared with 2D.

CONCLUSION

For off-site evaluation, 3D US is more useful for diagnosis of thyroid nodules than 2D US.

KEY POINTS

• 3D had higher sensitivity than 2D for predicting malignancy and extrathyroidal extension. • 3D showed better agreement for predicting extrathyroidal extension in malignancy than 2D. • 3D thyroid ultrasound saved time for scanning compared with 2D. • For off-site evaluation of thyroid nodules, 3D is more useful than 2D.

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.

Editorial review: pediatric 3D ultrasound

Three-dimensional ultrasound is an established diagnostic imaging technique in many specialties. However, in neonates, infants and children three-dimensional ultrasound still is underutilized, partially due to time constraints for post-processing and restricted availability, of devices as well as dedicated pediatric transducers. Also reimbursement issues still need to be addressed. This editorial review presents more or less established pediatric three-dimensional ultrasound applications with proven diagnostic benefit as well as potential future applications of three-dimensional/four-dimensional ultrasound in infants and children, aiming at enhancing research and promoting practical use of three-dimensional ultrasound in relevant pediatric conditions. Particularly, applications in neonatal neurosonography, ultrasound of the urogenital tract as well as some other small part and miscellaneous queries are highlighted. Additional other potential and future indications are discussed briefly, also mentioning restrictions and potential future developments. In summary, three-dimensional ultrasound holds some potential to widen sonographic diagnostic capabilities throughout childhood and hopefully will be increasingly investigated and introduced into clinical practice provided respective equipment and pediatric three-dimensional/four-dimensional ultrasound transducers become available.

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.

EANM Dosimetry Committee series on standard operational procedures for pre-therapeutic dosimetry II. Dosimetry prior to radioiodine therapy of benign thyroid diseases

The EANM Dosimetry Committee Series "Standard Operational Procedures for Pre-Therapeutic Dosimetry" (SOP) provides advice to scientists and clinicians on how to perform patient-specific absorbed dose assessments. This particular SOP describes how to tailor the therapeutic activity to be administered for radioiodine therapy of benign thyroid diseases such as Graves' disease or hyperthyroidism. Pretherapeutic dosimetry is based on the assessment of the individual (131)I kinetics in the target tissue after the administration of a tracer activity. The present SOP makes proposals on the equipment to be used and guides the user through the measurements. Time schedules for the measurement of the fractional (131)I uptake in the diseased tissue are recommended and it is shown how to calculate from these datasets the therapeutic activity necessary to administer a predefined target dose in the subsequent therapy. Potential sources of error are pointed out and the inherent uncertainties of the procedures depending on the number of measurements are discussed. The theoretical background and the derivation of the listed equations from compartment models of the iodine kinetics are explained in a supplementary file published online only.

Correlação entre volume tireoidiano determinado pelo método de ultrassonografia versus cintilografia e sua implicação em cálculos dosimétricos na terapia com radioiodo na doença de Graves

INTRODUÇÃO: A doença de Graves (DG) é a causa mais comum de hipertireoidismo e, entre as abordagens terapêuticas mais utilizadas para o tratamento do hipertireoidismo por doença de Graves, encontram-se a cirurgia, o uso de drogas antitireoidianas e a radioiodoterapia. No cálculo dosimétrico para determinação da dose de radioiodo a ser utilizada, é possível empregar a ultrassonografia e a cintilografia para avaliar o volume tireoidiano. OBJETIVO: O presente estudo visa correlacionar essas metodologias com ênfase no volume obtido e nas implicações dosimétricas. SUJEITOS E MÉTODOS: Foram incluídos no estudo 103 pacientes com diagnóstico de DG encaminhados para radioiodoterapia. Esses foram submetidos à ultrassonografia da tireoide e à cintilografia tireoidiana, com cálculo de volume pela cintilografia baseado na fórmula de Allen. RESULTADOS E CONCLUSÕES: Observou-se boa correlação entre os dois métodos, porém com massa estimada pela cintilografia sistematicamente maior que a estimada pela ultrassonografia, o que pode acarretar em menor estimativa de dose absorvida quando utilizado o método cintilográfico.

Local reference ranges of thyroid volume in sudanese normal subjects using ultrasound

This study aimed to establish a local reference of thyroid volume in Sudanese normal subjects using ultrasound. A total of 103 healthy subjects were studied, 28 (27.18%) females and 75 (72.82%) males. Thyroid volume was estimated using ellipsoid formula. The mean age and range of the subjects was 21.8 (19–29) years; the mean body mass index (BMI) was 22.3 (16.46–26.07) kg/m². The overall mean volume ± SD volume of the thyroid gland for both lobes in all the patients studied was 6.44 ± 2.44 mL. The mean volume for both lobes in females and males were 5.78 ± 1.96 mL and 6.69 ± 2.56 mL, respectively. The males' thyroid volume was greater than the females'. The mean volume of the right and left lobes of the thyroid gland in males and females were 3.38 ± 1.37 mL and 3.09 ± 1.24 mL, respectively. The right thyroid lobe volume was greater than the left. The values obtained in this study were lower than those reported from previous studies.

Potential role of 3DUS in infants and children

The objective of this review is to discuss basic technical aspects as well as potential pediatric applications of three-dimensional ultrasound (3DUS). Different 3DUS-techniques are already commercially available. Most commonly, a transducer-integrated motor drives a scan-head to acquire a volumetric dataset, which is then reconstructed and viewed using various post-processing techniques. It has been proved feasible to apply 3DUS with pediatric transducers in typical pediatric investigations. Based on our own experiences and on review of the literature, 3DUS can be successfully used in infants and children for brain, spine, cardiac, urinary tract (particularly assessment of hydronephrosis, and virtual cystoscopy), and female genital (e.g., for assessment of uterine malformations) US, and for various other applications, particularly in small parts. Power Doppler data can be integrated, allowing 3DUS-angiography. Thus, 3DUS promises to become a useful adjunct for imaging children, particularly as it enhances ultrasound by offering additional, previously inaccessible planes, rendering options and surface assessments. 3DUS should be increasingly exploited, thus hopefully helping reduce the need for more invasive or burdening (e.g., ionizing radiation) investigations in children.

Advantages and disadvantages of 3D ultrasound of thyroid nodules including thin slice volume rendering

BACKGROUND

The purpose of this study was to assess the advantages and disadvantages of 3D gray-scale and power Doppler ultrasound, including thin slice volume rendering (TSVR), applied for evaluation of thyroid nodules.

METHODS

The retrospective evaluation by two observers of volumes of 71 thyroid nodules (55 benign, 16 cancers) was performed using a new TSVR technique. Dedicated 4D ultrasound scanner with an automatic 6-12 MHz 4D probe was used. Statistical analysis was performed with Stata v. 8.2.

RESULTS

Multiple logistic regression analysis demonstrated that independent risk factors of thyroid cancers identified by 3D ultrasound include: (a) ill-defined borders of the nodule on MPR presentation, (b) a lobulated shape of the nodule in the c-plane and (c) a density of central vessels in the nodule within the minimal or maximal ranges. Combination of features provided sensitivity 100% and specificity 60-69% for thyroid cancer.Calcification/microcalcification-like echogenic foci on 3D ultrasound proved not to be a risk factor of thyroid cancer.Storage of the 3D data of the whole nodules enabled subsequent evaluation of new parameters and with new rendering algorithms.

CONCLUSIONS

Our results indicate that 3D ultrasound is a practical and reproducible method for the evaluation of thyroid nodules. 3D ultrasound stores volumes comprising the whole lesion or organ. Future detailed evaluations of the data are possible, looking for features that were not fully appreciated at the time of collection or applying new algorithms for volume rendering in order to gain important information. Three-dimensional ultrasound data could be included in thyroid cancer databases. Further multicenter large scale studies are warranted.

Sonographic differentiation of asymptomatic diffuse thyroid disease from normal thyroid: a prospective study

BACKGROUND AND PURPOSE

There is no useful guide or study related to the differentiation of asymptomatic diffuse thyroid disease from normal thyroid by using thyroid US. This study was prospectively designed to evaluate the efficacy of the use of real-time thyroid sonography as performed by an experienced radiologist for the identification of asymptomatic DTD.

MATERIALS AND METHODS

From January 2008 to December 2008, 2267 patients underwent thyroid sonography in our hospital by 1 radiologist. Each patient's thyroid was prospectively classified as being in 1 of 4 of the following diagnostic categories on the basis of the sonographic features as determined with the use of real-time sonography: suggestive for DTD, suspicious for DTD, indeterminate, and no evidence of DTD. We calculated the diagnostic efficacy of the sonographic classifications compared with the pathology results.

RESULTS

Sonographic classifications for DTD in 340 patients who underwent thyroid surgery because of thyroid malignancy or other causes included the following: suggestive for DTD (n = 32), suspicious for DTD (n = 39), indeterminate (n = 18), and no evidence of DTD (n = 251). On the pathology, HT (n = 33), chronic lymphocytic thyroiditis (n = 27), diffuse hyperplasia (n = 2), and NTP (n = 278) were identified. There were true-positive cases (n = 50), true-negative cases (n = 244), false-positive cases (n = 21), and false-negative cases (n = 7). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for a diagnosis of asymptomatic DTD were 87.7%, 92.1%, 70.4%, 97.2%and 91.3%, respectively.

CONCLUSIONS

The present sonographic classification based on real-time sonography of the thyroid is a useful tool for differentiating asymptomatic DTD from normal thyroid.

The reproducibility of the virtual organ computer-aided analysis program for evaluating 3-dimensional power Doppler ultrasonography of diffuse thyroid disorders

AIM

The aim of this study was to evaluate the intra- observer and inter-observer reproducibility of 3-dimensional (3D) power Doppler ultrasonography with the virtual organ computer-aided analysis (VOCAL) program for measuring thyroid volume and vascular indices in patients with diffuse thyroid disorders.

MATERIALS AND METHODS

Patients with diffuse goiters were examined by 3D ultrasonography from August 2005 to July 2006. The parameters for vascular assessment included the vascularization index (VI), flow index (FI), vascularization-flow index (VFI), and thyroid size, and were obtained using the VOCAL program. This program used plane A and a 30 degrees rotational step. Intra-observer and inter-observer repeatability are presented as intra-class correlation coefficient (intra-CC) and inter-class correlation coefficient (inter-CC), with values >0.70 being acceptable.

RESULTS

Sixty-three patients in total were enrolled for this study, including 19 patients with simple goiter and 44 patients with autoimmune thyroid disease (AITD) (23 Graves' disease, 21 Hashimoto's thyroiditis). Thyroid volume and 3 vascular indices showed excellent reproducibility in the AITD group (intra- CC>0.9373 and inter-CC>0.8763) and its subgroups. The VI had excellent consistent reproducibility in the simple goiter group (intra-CC>0.8987 and inter-CC>0.8881), but the other parameters did not.

CONCLUSIONS

Based on this study, 3D power Doppler ultrasonography with the VOCAL program is a reliable tool for evaluating diffuse thyroid disorders due to an autoimmune process. The VI is the most reliable parameter.

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.

Three-dimensional ultrasonography-based virtual cystoscopy of the pediatric urinary bladder: a preliminary report on feasibility and potential value

OBJECTIVE

The purpose of this study was to validate the feasibility and potential of 3-dimensional ultrasonography (3DUS)-based virtual cystoscopy in the pediatric urinary bladder.

METHODS

Twenty patients (age range, newborn-14 years) underwent urinary tract ultrasonography and 3DUS of the urinary bladder. From this data set, virtual cystoscopy was reconstructed for visualization of the inner bladder surface. Three-dimensional ultrasonography was compared with 2-dimensional ultrasonographic (2DUS) findings, voiding cystourethrography (VCUG) results, and reports from cystoscopy or surgery when available.

RESULTS

Three-dimensional ultrasonography was feasible in all patients. Data quality was sufficient for virtual cystoscopy without major motion artifacts. The 3DUS results matched all other findings; particularly, 3DUS superiorly visualized the ureteral ostium and the bladder neck configuration; in 5 patients, 3DUS depicted pathologically shaped ostia not detected by 2DUS. This correlated with the presence of vesicoureteral reflux on VCUG. Performing virtual cystoscopy added 1 minute to the investigation time (range, 0.5-2 minutes) and 3 minutes for postprocessing and viewing (range, 2-5 minutes).

CONCLUSIONS

Three-dimensional ultrasonography-based virtual cystoscopy is feasible in the pediatric urinary bladder without sedation. It reveals surface information not accessible by 2DUS, improving detection of pathologic conditions such as atypically shaped ureteral ostia. Three-dimensional ultrasonography-based cystoscopy may become a valuable adjunct to 2DUS of the pediatric urinary tract, improving selection criteria for further imaging such as VCUG, and potentially may help reduce the need for endoscopic cystoscopy. However, these preliminary results still have to be confirmed in prospective studies with larger patient numbers.

A mathematical formula to estimate in vivo thyroid volume from two-dimensional ultrasonography

BACKGROUND

The determination of thyroid volume (TV) is required for the management of thyroid diseases. Since two-dimensional ultrasonography (2D-US) has become the accepted method for the assessment of TV (2D-US-TV), we verified whether it accurately assesses postsurgical measured TV (PS-TV).

METHODS

In 92 patients who underwent total thyroidectomy by conventional cervicotomy, 2D-US-TV obtained by the ellipsoid volume formula was compared to PS-TV, determined by the Archimedes' principle.

RESULTS

Mean 2D-US-TV (23.9 +/- 14.8 mL) was significantly lower than mean PS-TV (33.4 +/- 20.1 mL). Underestimation was observed in 77% of cases, and it was related to gland multinodularity and/or nodular involvement of the isthmus, while 2D-US-TV matched the PS-TV in the remaining 21 cases (23%). A mathematical formula, to estimate PS-TV from US-TV, was derived using a linear model (Calculated-TV = [1.24 x 2D-US-TV]+ 3.66). Calculated-TV (mean value 33.4 +/- 18.3 mL) significantly (p < 0.01) increased from 21 (23%) to 31 (34%) of the cases that matched PS-TV. In addition, it significantly (p < 0.01) decreased from 77% to 27% the percentage of cases where PS-TV was underestimated as well as the range of the disagreement from 245% to 92%.

CONCLUSIONS

This study shows that 2D-US does not provide an accurate estimation of TV and suggests that it can be improved by a mathematical model different from the ellipsoid model. If confirmed in prospective studies, this may contribute to a more appropriate management of thyroid diseases.

Quantification of thyroid volume using 3-D ultrasound imaging

Ultrasound (US) is among the most popular diagnostic techniques today. It is non-invasive, fast, comparably cheap, and does not require ionizing radiation. US is commonly used to examine the size, and structure of the thyroid gland. In clinical routine, thyroid imaging is usually performed by means of 2-D US. Conventional approaches for measuring the volume of the thyroid gland or its nodules may therefore be inaccurate due to the lack of 3-D information. This work reports a semi-automatic segmentation approach for the classification, and analysis of the thyroid gland based on 3-D US data. The images are scanned in 3-D, pre-processed, and segmented. Several pre-processing methods, and an extension of a commonly used geodesic active contour level set formulation are discussed in detail. The results obtained by this approach are compared to manual interactive segmentations by a medical expert in five representative patients. Our work proposes a novel framework for the volumetric quantification of thyroid gland lobes, which may also be expanded to other parenchymatous organs.

Optimized radioiodine therapy for Graves?? disease: Two MIRD-based models for the computation of patient-specific therapeutic 131I activity

AIM

(131)I therapy is increasingly used for Graves' hyperthyroidism. Debate remains about the best method for calculating the activity to administer, as well as about the potential benefit of such computed activity. Several arguments plead, nevertheless, in favour of a personalized computation, such as inter-individual variations of thyroid volume and biokinetics.

METHODS

A MIRD-based dosimetric approach, with an additional extension that takes into account the variation of thyroid mass during the treatment, has been developed. This approach includes the benefits of a personalized determination of biokinetics. Results were compared with those of six methods widely used in routine practice. Forty-one patients were enrolled (34 women, seven men; mean age +/-SD: 48.11 +/- 6.4 years). (131)I uptakes were measured at 4, 24 and 96 h (36.2 +/- 14.6%, 42.8 +/- 9.7% and 27.6 +/- 6.8%, respectively), following administration of the tracer. The kinetics of iodine in the thyroid were evaluated using a two-compartment model (effective half-life of 5.1 +/- 1.6 days). Computations of activities to deliver the doses prescribed by the physician were done with the eight formalisms.

RESULTS

There was no statistical difference between results of the two MIRD-based formalisms (227 +/- 148 MBq and 213 +/- 124 MBq), which were also not significantly different from those obtained with the majority of the other methods (from 128 +/- 95 MBq to 275 +/- 223 MBq). However, a large intra-individual difference up to a factor of 2 between two given methods was found.

CONCLUSION

The formalism developed appears to be a good compromise between all the common formalisms already used in many institutions. Furthermore, it allows the exposures of target volumes and non-target volumes to be planned individually and practical individual radiation protection recommendations to be implemented.

Measuring thyroid gland volume: should we change the correction factor?

OBJECTIVE

In the assessment of thyroid volume with sonography (formula of an ellipsoid), a correction factor is used. Whereas previously 0.524 was used, the World Health Organization has recently changed (after the first review) this correction factor to 0.479. We compare volume measurement of the thyroid using different correction factors to automated volume measurement using MDCT, and we define an optimal correction factor in thyroid volume assessment.

CONCLUSION

Acceptable correction factors are situated in the range of 0.494-0.554. We propose a correction factor of 0.529 when using the ellipsoid formula.

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.

Gray-scale three-dimensional sonography of thyroid nodules: feasibility of the method and preliminary studies

The aim of the study was differential evaluation of new and classical sonographic features of benign thyroid nodules and thyroid cancer with three-dimensional gray-scale sonography and evaluation of the effectiveness of the thin-slice surface rendered images in comparison with multiplanar reformation (MPR) presentation. Fifty-four thyroid nodules were interactively evaluated with thin-slice smooth surface rendering: shape in the c-plane (parallel to the probe) and evaluation of echogenicity, margins and calcification/microcalcification-like echogenic foci in the a-plane (plane of the probe). Evaluation of the level of agreement in readers' interpretation and between sonographic techniques was performed using the kappa statistic. Surface rendering permitted visualization of the shape of the nodule in the c-plane in all cases, in contrast to only up to 48% of cases in MPR evaluation. Lobulated nodule shape in the c-plane was 82-100% sensitive and 47-53% specific in diagnosis of carcinoma. Surface rendered images showed more calcification/microcalcification-like echogenic foci than MPR ones. The level of agreement between the observers in the evaluation of features of thyroid nodules and the agreement between features of thyroid nodules on MPR and surface-rendered images showed at least moderate reproducibility (kappa>or=0.41). Three-dimensional thin-slice surface rendering sonography appears to be a feasible and effective method for thyroid nodule evaluation.

Hydronephrotic kidney: pediatric three-dimensional US for relative renal size assessment--initial experience

PURPOSE

To prospectively evaluate accuracy of three-dimensional (3D) ultrasonography (US) for assessment of relative renal size in infants and children with hydronephrosis.

MATERIALS AND METHODS

Informed consent was obtained from parents and also from children who were older than 8 years. Study was approved by ethics committee. Two-dimensional (2D) US, 3D US, and scintigraphy were performed in 40 patients with hydronephrosis (age range, neonate to 16 years; seven girls, 33 boys) without acute renal disease. Twenty patients also underwent magnetic resonance (MR) urography. US and MR urography were performed by one experienced pediatric radiologist; 3D US and MR urographic volume calculations were performed by specifically trained radiologists. Three-dimensional US was performed with integrated 3D volume probes or external system based on electromagnetic positioning devices. At 2D US, kidney volume was calculated with application of ellipsoid equation. At MR urography and 3D US, real renal parenchymal volume was calculated with subtraction of dilated collecting system. Split renal function was assessed with static renal scintigraphy. Three-dimensional US results were graded with respect to image quality and compared with results of 2D US, scintigraphy, and MR urography by using mean difference percentage and standard deviation of the difference. All investigations were performed with blinding. Inter- and intraobserver variability were calculated with coefficient of variation.

RESULTS

In 76 of 80 kidneys, 3D US image of diagnostic quality was obtained. Three-dimensional US volume measurements compared well with MR urographic measurements (mean difference, -2.5% +/- 7.8 [standard deviation] vs 25.8% +/- 32.2 for 2D US) and with scintigraphically assessed split renal function (mean difference, 1.2% +/- 9.2 vs 15.9% +/- 43.8 for 2D US). Intra- and interobserver variability were +/-6.4% and +/-9.9%, respectively.

CONCLUSION

Initial experience with renal 3D US indicates that it is an accurate method for assessment of renal parenchymal volume and relative renal size, provided there is no acute renal disease.

Diagnosis of Thyroid Cancer in Children: Value of Gray-Scale and Power Doppler US

PURPOSE

To prospectively analyze the accuracy of various diagnostic criteria for cancer in solid thyroid nodules in children on the basis of gray-scale and power Doppler ultrasonographic (US) findings.

MATERIALS AND METHODS

The study protocol was approved by the institutional review board, and patient's parents gave full informed consent. One hundred three consecutive pediatric patients with solid thyroid nodules were included in the study. Thirty-five patients had thyroid cancer (mean age, 14.6 years +/- 2.6 [standard deviation]; range, 10-18 years), and 68 patients had benign thyroid nodules (mean age, 14.2 years +/- 2.9; range 9-18 years). Three-dimensional US was used to determine the volume of thyroid gland and thyroid nodules. Results of nodule cytologic and histologic examination and long-term clinical and US follow-up were used as a proof of final diagnosis. The following US characteristics were evaluated: location, echogenicity, echotexture, outline, presence of a halo, microcalcifications, and type of vascularization. Multivariate logistic regression analysis was used to evaluate the accuracy of US criteria for thyroid cancer in lesions with diameter of 15 mm and smaller and lesions with diameter larger than 15 mm. Qualitative variables were compared by using the chi(2) test and quantitative variables were compared by using the Student t test. Significance was defined at P < .05.

RESULTS

In thyroid nodules with diameter of 15 mm and smaller, the most reliable diagnostic criteria for malignancy were an irregular outline (sensitivity, 69.6%; specificity, 86.4%; P < .001), subcapsular location (sensitivity, 65.2%; specificity, 86.4%; P < .001), and increased intranodular vascularization (sensitivity, 69.6%; specificity, 87.9%; P < .01). For thyroid nodules larger than 15 mm in diameter, the accuracy of US diagnosis was much lower than that for smaller nodules. The only reliable criterion for cancer in this group was hypoechogenicity (sensitivity, 60.0%; specificity, 84.0%; P < .01).

CONCLUSION

Study findings indicate that US is most helpful in diagnosis of thyroid malignancy in thyroid nodules with diameter of 15 mm and smaller, with detection of irregular tumor outline, subcapsular location, and increased intranodular vascularization.

Prevalence of thyroid disorders in the working population of Germany: ultrasonography screening in 96,278 unselected employees

Germany continues to be iodine deficient despite considerable improvement in the past years. To assess the current prevalence of diffuse and/or nodular thyroid disorders, a cross-sectional observational study in a nonrandom sample of the working population was carried out throughout Germany in 2001 and 2002. A total of 96,278 employees 18-65 years of age from 214 companies or other private or public institutions voluntarily underwent ultrasonographic examinations by 230 experienced investigators. To compare the prevalence of different abnormal findings in relation to age and gender, descriptive statistics and the Kruskal-Wallis test were used. Data from volunteers with previous thyroid treatment (13.0% of total sample) were not included in the analysis. Abnormal findings (goiter and/or nodules > 0.5 cm) were observed in 33.1% (men, 32.0%; women, 34.2%) of the examined patient population, an enlarged thyroid without nodules in 9.7% (men, 11.9%; women, 7.6%), nodules only without enlargement of the thyroid in 14.3% (men, 11.5%; women, 17.0%), and nodular goiter in 9.1% (men, 8.6%; women, 9.6%). Nodules (with or without goiter) between 0.5 and up to 1.0 cm were found in 10.0%, and nodules above 1.0 cm in 11.9% of the population. Rates of abnormal findings increased with age in both genders. Goiter was more common in men, nodules in women. In light of these findings, the prevalence of thyroid disorders in Germany continues to be high. Although the study may slightly overestimate the prevalence, about one third of the working population is affected and remains unaware of this condition. These results emphasize the importance of effective sonographic screening to detect early thyroid abnomalities in order to initiate preventive and therapeutic measures to prevent the onset or progression of disease and its sequels.

Three-Dimensional Ultrasound in Small Parts

For longer than 40 years, ultrasound (US) has been a widely used imaging tool in medical practice, which has proved helpful for the diagnosis and staging of diseases. Although three-dimensional ultrasound (3D) US has been available for more than 10 years, it was only through the development of the most recent computer technologies and its adaptation to ultrasound systems, that 3D US has become able to achieve the high level of sensitivity and performance necessary to be considered seriously in clinical practice. 3D US is rapidly turning into a technology with an ever-increasing range of applications in numerous fields because, among other reasons, it helps overcome some of the key limitations related to two-dimensional imaging. 3D US can be used in ultrasonography for small parts, among other medical areas. The assessment of the testicle, parotid, thyroid and parathyroid glands is properly achieved. The multiplanar presentation and niche mode are quite useful to determine the extension--inside or outside the organs-, of nodules, cysts or tumors. The volume measurement is better assessed with 3D US and given this, we can perform studies that follow growth in order to decide medical or surgical treatment. The VOCAL makes it possible to obtain a proper after-treatment follow-up of focal disorders in these small organs. Neovascularization is clearly viewed with 3D US and probably can suggest malignant origin of a neoplasm. 3D US offers a more comprehensive image of anatomical structures and pathological conditions and also permits to observe the exact spatial relationships. We are aware more studies are needed to demonstrate specificity and sensibility of 3D US in particular clinical conditions, not only in small parts but also is some other non-Ob/Gyn applications.

Three-dimensional ultrasonography for volume measurement of thyroid nodules in children

OBJECTIVE

The aim of this study was to compare the accuracy of thyroid nodule volume measurements performed by 2- and 3-dimensional ultrasonography and to evaluate the dependence of volume measurement results on nodule size and echographic characteristics.

METHODS

Results of multiple 2- and 3-dimensional ultrasonographic volume measurements of thyroid nodules in 102 children with different variants of thyroid nodular disease were reviewed retrospectively. The standardized difference, within-observer variability, and repeatability were estimated for both 2- and 3-dimensional ultrasonography. The mean age of the patients +/- SD in the examined group was 14.9 +/- 2.8 years; the mean volume of thyroid nodules was 0.78 +/- 0.13 mL.

RESULTS

The SD of the normalized difference for 3-dimensional ultrasonography (2.8%) showed the clear superiority of its accuracy over 2-dimensional ultrasonography (15.9%; F test, P < .01). Intraobserver variability and repeatability for both examined methods had significant dependence on the nodule outline. For 2-dimensional ultrasonography, the intraobserver variability increased from 14.0% in nodules with a regular outline to 24.5% in those with an irregular outline (P < .001), and for 3-dimensional ultrasonography, it increased from 5.1% to 9.3% (P < .001). Intraobserver repeatability dropped from 85.4% in regular nodules to 74.6% in irregular nodules (P < .001) for 2-dimensional ultrasonography and from 94.7% to 90.4% (P < .001) for 3-dimensional ultrasonography.

CONCLUSIONS

Volume measurements by 3-dimensional ultrasonography are more accurate, showing lower intraobserver variability and higher repeatability, than those made by 2-dimensional ultrasonography with less dependence on nodule size and echographic characteristics.

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.

Comparison of methods for thyroid volume estimation in patients with Graves' disease

Individualised dosage models are frequently applied for radioiodine therapy in patients with Graves' hyperthyroidism, especially in Europe. In these dosage schemes the thyroid volume is an important parameter. Thyroid volume determinations are usually made with ultrasonography or with thyroid scintigraphy, although the accuracy of planar scintigraphy for this purpose is not well established. The aim of this study was to compare the accuracy of three modalities for the determination of the thyroid volume in patients with Graves' disease: planar scintigraphy (PS), single-photon emission tomography (SPET) and ultrasonography (US). These three modalities were compared with magnetic resonance imaging (MRI) as the gold standard. Thyroid volume estimations were performed in 25 patients with Graves' disease. The PS images were subjected to filtering and thresholding, and a standard surface formula was used to calculate the thyroid volume. With SPET the iteratively reconstructed thyroid images were filtered, and after applying a threshold method an automatic segmentation algorithm was used for the volume determinations. Thyroid volumes were estimated from the US images using the ellipsoid volume model for multiple two-dimensional measurements. For MRI, thyroid segmentation was performed manually in gadolinium-enhanced T1-weighted images and a summation-of-areas technique was used for the volume measurements. The thyroid volumes calculated with MRI were 25.0+/-13.8 ml (mean+/-SD, range 7.0-56.3 ml). PS correlated poorly with MRI ( R(2)=0.61) and suffered from a considerable bias (-4.0+/-17.6 ml). The differences between PS and MRI volume estimations had a very large spread (33+/-58%). For SPET both the correlation with MRI ( R(2)=0.84) and the bias (1.8+/-11.9 ml) were better than for PS. US had by far the best correlation with MRI ( R(2)=0.97) and the best precision, but the bias (6.8+/-7.5 ml) was not negligible. In conclusion, SPET is preferred over PS for accurate measurements of thyroid volume. US is the most accurate of the three modalities, if a correction is made for bias.

Management of simple nodular goiter: current status and future perspectives

The simple nodular goiter, the etiology of which is multifactorial, encompasses the spectrum from the incidental asymptomatic small solitary nodule to the large intrathoracic goiter, causing pressure symptoms as well as cosmetic complaints. Its management is still the cause of considerable controversy. The mainstay in the diagnostic evaluation is related to functional and morphological characterization with serum TSH and (some kind of) imaging. Because malignancy is just as common in patients with a multinodular goiter as patients with a solitary nodule, we support the increasing use of fine-needle aspiration biopsy (cytology). Most patients need no treatment after malignancy is ruled out. In case of cosmetic or pressure symptoms, the choice in multinodular goiter stands between surgery, which is still the first choice, and radioiodine if uptake is adequate. In addition to surgery, the solitary nodule, whether hot or cold, can be treated with percutaneous ethanol injection therapy. If hot, radioiodine is the therapy of choice. Randomized studies are scarce, and the side effects of nonsurgical therapy are coming into focus. Therefore, the use of the optimum option in the individual patient cannot at present be based on evidence. However, we are of the view that levothyroxine, although widely used, should no longer be recommended routinely for this condition. Within a few years, the introduction of recombinant human TSH and laser therapy may profoundly alter the nonsurgical treatment of simple nodular goiter.

Thyroid volume measurement in patients prior to radioiodine therapy: comparison between three-dimensional magnetic resonance imaging and ultrasonography

Because of its cost effectiveness, wide availability, and technical ease of application, ultrasonography is the reference method for determining the thyroid volume prior to radioiodine therapy. The goal of the study is a prospective assessment of the deviation between volumetric ultrasonography measurements in comparison to those performed with three-dimensional magnetic resonance imaging (MRI). To that end, 60 consecutive patients with multinodular toxic goiter (n = 28, 46.7%) or Graves' disease (n = 32, 53.3%) were included in the study. Ultrasonographic volumetry according to the well-known ellipsoid formula was performed by three different technicians. In addition, three-dimensional MRI scans of the neck area were acquired and evaluated by the ellipsoid formula as well as by a dedicated region-of-interest technique (MRI-ROI), which was used as standard of reference. While there was no significant difference between the ultrasonographic examinations of the three technicians, a highly significant mean deviation of 22.7% (10.4 mL) was found between the sonographic measurements and the MRI-ROI results (p < 0.01) that were underestimated in 80% of the cases. Correlation coefficients between the various volumetric approaches were highly significant, with values of at least 0.886 (p < 0.01). An additional analysis of volume-dependent subgroups revealed that thyroid volume had no significant influence on the results of ultrasonographic volumetry (p > 0.15). In conclusion, the study showed ultrasonography to be a reliable method of satisfactory accuracy that is appropriate for volumetric thyroid measurements. The findings indicate that the use of a correction factor higher than 0.52 in the ellipsoid formula is recommended to improve accuracy. However, further studies are necessary to confirm these findings.