CRD summary

This review concluded that real-time ultrasonography was a good technique for preoperative lymph node staging of papillary thyroid carcinoma. Relevant studies may have been missed and there were limitations in the meta-analysis. The conclusions appear optimistic; summary estimates seemed to indicate that ultrasonography may be useful to confirm cervical lymph node metastases but not adequate for rule-out.

Authors' objectives

To assess the diagnostic performance of ultrasound for the detection of cervical lymph node metastasis in patients with papillary thyroid carcinoma.

Searching

MEDLINE and EMBASE were searched from January 1995 to November 2010. Search terms were reported. CancerLit, The Cochrane Library, bibliographies of included studies and relevant reviews were screened for additional articles. Only studies published in English or Chinese were included.

Study selection

Studies that assessed real-time ultrasonography for evaluation of cervical lymph node metastasis in 10 or more patients with papillary thyroid carcinoma were eligible for inclusion. Studies were required to report sufficient data to determine the numbers of true positive, false positive, false negative and true negative test results on a per patient or per lesion basis.

Where reported, mean ages of study participants ranged from 39 to 55 years. Most participants were female. Reported ultrasound frequencies ranged from 5MHz to 12MHz.

Two reviewers independently assessed studies for inclusion.

Assessment of study quality

Methodological quality of included studies was assessed using the 14-item QUADAS tool. Only studies that met at least nine QUADAS criteria were included in the review.

Two reviewers independently assessed study quality. Any disagreements were resolved by consultation with a third reviewer.

Data extraction

Data were extracted on the numbers of true positive, false positive, false negative and true negative test results. These data were used to calculate per patient or per lesion sensitivity and specificity values, with 95% confidence intervals (CI), for real-time ultrasonography. A value of 0.5 was added to all cells that contained a count of zero. Where reported, these data were also extracted for other imaging modalities – computed tomography (CT) and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) – for comparison with real-time ultrasonography.

Study authors were contacted for additional data where necessary.

Two reviewers independently extracted data. Any disagreements were resolved by consultation with a third reviewer.

Methods of synthesis

Pooled estimates of per patient and per lesion sensitivity and specificity, with 95% CI, were calculated; a random effects model was used where there was evidence of between-study heterogeneity (p<0.05). Summary receiver operating characteristic (SROC) curves were constructed using the Moses and Littenberg model.

Between-study heterogeneity was assessed using the Χ² test. Subgroup analyses and linear regression were used to explore sources of between-study heterogeneity and assess threshold effect.

Publication bias was assessed using Deeks funnel plots.

Results of the review

Thirteen studies (1,020 participants, range 12 to 299) were included in the review. Two studies included some patients with a primary tumour other than papillary thyroid carcinoma (other head and neck cancers). Most studies did not report the time interval between the index test and reference standard and only around half of the studies reported interpretation of the reference standard blinded to the results of the index test.

Pooled estimates of per patient sensitivity and specificity of real-time ultrasonography were 72% (95% CI 46% to 88%) and 98% (95% CI 84% to 100%) based on six studies with significant between-study heterogeneity. The median prevalence of cervical lymph node metastasis in patients with papillary thyroid carcinoma was 45% and linear regression suggested that sensitivity was not correlated with prevalence.

Pooled estimates of per lesion sensitivity and specificity of real-time ultrasonography were 63% (95% CI 47% to 76%) and 93% (95% CI 73% to 99%) based on seven studies with significant between-study heterogeneity. The median prevalence of cervical lymph node metastasis in patients with papillary thyroid carcinoma was 58%. Linear regression suggested that sensitivity was not correlated with prevalence.

There was no evidence of threshold effect. Meta-regression analysis, using individual QUADAS criteria as indicator variables, suggested that representativeness of the participant sample, time delay between index test and reference standard and blinded interpretation of the reference standard significantly affected estimates of test performance. The results of subgroup analyses were reported in the article. No data that compared real-time ultrasonography to other imaging modalities were reported.

There was no evidence of publication bias.

Authors' conclusions

Real-time ultrasonography was a good technique for preoperative lymph node staging of papillary thyroid carcinoma and was helpful for detecting metastatic cervical lymph nodes.

CRD commentary

The review reported a clear research objective. Some inclusion criteria were defined but the reference standard used to confirm diagnoses was not specified. Several sources were searched to identify relevant studies and an assessment of publication bias was reported. The restriction studies in English or Chinese may have resulted in the omission of relevant studies. Measures to minimise error and bias were applied throughout the review process and the methodological quality of included studies was assessed. An overall quality score (not recommended for QUADAS) was used to select studies for inclusion and the effect of individual QUADAS criteria on estimates of test performance was investigated. It may have been more appropriate to use a bivariate or hierarchical model to generate summary estimates of test performance, particularly given the presence of significant between-study heterogeneity.

Overall, the authors' conclusions appear optimistic for the data presented; summary estimates seem to indicate that real-time ultrasound may be useful to confirm the presence of cervical lymph node metastases but would not be adequate for rule-out.

Implications of the review for practice and research

Practice: The authors did not specify any recommendations for clinical practice.

Research: The authors stated that high-quality prospective studies of ultrasonography for evaluation of cervical lymph node status in patients with papillary thyroid carcinoma were required.

Funding

Shanghai Leading Academic Discipline Project and Shanghai Jiaotong University School of Medicine Leading Academic Discipline Project, China.

Bibliographic details

Wu LM, Gu HY, Qu XH, Zheng J, Zhang W, Yin Y, Xu JR. The accuracy of ultrasonography in the preoperative diagnosis of cervical lymph node metastasis in patients with papillary thyroid carcinoma: a meta-analysis. European Journal of Radiology 2012; 81(8): 1798-1805. [PubMed: 21536396]

Original Paper URL

http://www.ejradiology.com/article/S0720-048X(11)00407-4/abstract

Indexing Status

Subject indexing assigned by NLM

MeSH

Humans; Lymph Nodes /ultrastructure; Lymphatic Metastasis; Neck; Preoperative Care /statistics & numerical data; Prevalence; Prognosis; Reproducibility of Results; Sensitivity and Specificity; Thyroid Neoplasms /epidemiology /secondary /ultrasonography

AccessionNumber

12012038223

Database entry date

14/02/2013

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.