Mahsa Ghajarzadeh; Mehdi Mohammadifar; Seyed Hassan Emami-Razavi

Research Article

Austin J Radiol. 2016; 3(2): 1047.

Role of Sonoelastography in Differentiating Benign and Malignant Salivary Gland Tumors: A Systematic Review and Meta Analysis

Mahsa Ghajarzadeh^1*, Mehdi Mohammadifar² and Seyed Hassan Emami-Razavi¹

¹Brain and Spinal Injury Research Center, Tehran University of Medical Sciences, Iran

²Department of Radiology, Zanjan University of Medical Sciences, Iran

*Corresponding author: Mahsa Ghajarzadeh, Brain and Spinal Injury Research Center, Tehran University of Medical Sciences, Tehran, Iran

Received: October 21, 2015; Accepted: January 31, 2016; Published: March 01, 2016

Abstract

Objective: The goal of this systematic review is to determine the diagnostic accuracy of sonoelastography in evaluating salivary gland tumors.

Data sources: A highly sensitive search for sonoelastography and salivary gland tumors was performed through MEDLINE, Cochrane Library, ACP Journal Club, EMBASE, Health Technology assessment, and ISI web of knowledge for studies published prior to January 2013.

A manual search was performed to include additional studies from references of the retrieved articles.

Review methods: Two independent reviewers evaluated articles for eligibility. They extracted data from included studies.

The quality of included studies was evaluated by use of Quality Assessment of Diagnostic Accuracy Studies (QUADAS) questionnaire which consists of 14, four option questions (yes, no, unclear, Not Applicable (N/A)).

Forest plots for pooled estimates and summery of ROC plots for different cut-offs were produced.

Results: The literature review and manual search yielded 15 articles, 6 of which eligible to be included. A total of 348 individuals with total number of 366 salivary gland masses were evaluated. Eighty seven were malignant while, 269 were benign. Three hundred and twenty two were located in parotid gland and forty four were in sub-mandibular gland.

The summary sensitivity and specificity for the differentiation of benign and malignant salivary gland masses were 0.63 and 0.59.The summary Diagnostic OR (D OR), positive and negative LRs were 3.18, 1.63 and 0.61. The Area Under the Curve (AUC) was 0.68 (SE=0.03).

Conclusion: Sono-elastography had moderate accuracy in differentiating benign from malignant salivary gland tumors.

Keywords: Sonoelastography; Salivary gland tumors

Introduction

Salivary gland tumors count near 3% of all head and neck tumors [1] which could locate in major or minor salivary glands. The incidence rate of these tumors has been reported between 1 to 5 cases per 100000 person [1,2].

The initial imaging modality applied for salivary gland masses is sonography as it is cost-effective, non invasive and easy to apply [3].

By means of B-mode and color Doppler evaluation, echogenicity, structure, size, contour, calcification and vascularity could be examined, although previous studies demonstrated that the accuracy of these parameters for differentiating benign and malignant lesions are not satisfactory [4-6].

Elastography is a new sonographic modality which provides data regarding tissue stiffness. It provides tissue elasticity estimation by means of local compression.

Under external forces, soft tissues move more than harder ones and reflecting that malignant tissues are firmer than surrounding benign counterparts [7].

Series of previous studies had evaluated accuracy of sonoelastography in differentiating benign and malignant salivary gland tumors. Its sensitivity and specificity had been reported ranging from 41% to 75% and 47% to 91%, respectively [3,7-11].

The goal of this study was to perform a meta-analysis of published information to evaluate the overall accuracy of sonoelastography for differentiation of benign and malignant salivary gland tumors.

Materials and Methods

We searched MEDLINE, Cochrane Library, EMBASE,ACP Journal Club, Health Technology Assessment, and ISI web of knowledge for studies published prior to December 10^th, 2012 by using these search terms: “elastography“, “sonoelastography“, “real-time tissue elastography“, “elasticity“, “elastogram“, “elasticity imaging techniques“, “salivary gland“, “neoplasm”, “ tumor”, “carcinoma”.

A manual search was performed to include additional studies from references of the retrieved articles. Two independent reviewers evaluated articles for eligibility. The criteria for eligibility were:

Studies evaluated diagnostic accuracy of sonoelastography in differentiating malignant and benign salivary gland tumors. Systematic review articles, narrative review articles, letter to editors and editorial articles were excluded.
Using appropriate reference standard test such as Fine-Needle Aspiration (FNA), histological assessment of specimens obtained by surgery or dissection.
Diagnostic measures on sonoelstographic evaluation results such as sensitivity, specificity, positive and negative predictive values.

Data extraction and quality assessment

Two independent reviewers extracted data from included studies. Extracted data included: first author name, study publication year, country, number of patients, number of malignant and benign salivary masses, mean patient age in each study, number of male and female patients, classification method, number of parotid or submandibular masses.

The quality of included studies was evaluated by means of Quality Assessment of Diagnostic Accuracy Studies (QUADAS) questionnaire which consists of 14, four option questions (yes, no, unclear, Not Applicable (N/A)). The same two independent reviewers evaluated the quality of studies and in discord cases, disagreement solved by consensus of reviewers.

Statistical analysis and data synthesis

Accuracy of sonoelastography method was assessed by pooled estimates of sensitivity, specificity, positive and negative predictive values, and diagnostic odds ratio. In case of homogenity, fixed-effect model applied for pooled estimate calculation and if significant heterogeneity was present, the random-effect model was used .The Cochran Q test was estimated to detect the heterogeneity among studies. Inconsistency (I2) was calculated to describe the percentage of the variability attributable to heterogeneity.

Summary Receiver Operating Characteristic (SROC) curves were constructed, by means of Moses-Shapiro-Littenberg method and the Area Under the Curve (AUC) was calculated. P Value of <0.05 was considered significant.

Results

The chart describes the fellow of study selection in this systematic review. The literature and manual search yielded 15 articles, of which, 6 were eligible to include in this study which were published between 2010 and 2012. The studies were conducted in Poland (N=1), Romania (N=2), Turkey (N=2) and China Union (N=1).

A total of 348 individuals with total number of 366 salivary gland masses were evaluated. Eighty seven were malignant while, 269 were benign. Three hundred and twenty two were located in parotid gland and forty four were in sub-mandibular gland.

In five studies, only qualitative scoring system (in four articles scoring 1-4) was used. In one study only strain ratios applied for classification and in remaining one study, both strain ratio and elasticity scoring system (1-5) were applied.

Four studies used 1-4 scoring system while one used 1-5 and one strain ratio.

The characteristics of included articles are listed in (Table 1).

Table 1: Characteristics of the included studies.




  
    Author 
    Publication    year 
    Mean 
      age
    Total number    of patients 
    Male/female 
    Total number    of 
      masses
    malignant    /benign 
    Parotid/    submandibular 
    Method of    classification 
  
  
    Bhatia
    2010
    60
    61
    48/13
    65
    6/59
    57/8
    Scoring system (1-4)
  
  
    Dumitriu
    2011
    50
    66
    37/29
    74
    18/56
    63/11
    Scoring    system (1-4)
  
  
    Yerli
    2012
    49
    46
    N/A
    36
    8/28
    30/6
    Scoring system (1-4)
  
  
    Wierzbicka
    2012
    54
    43
    16/27
    43
    10/33
    43/0
    Scoring    system (1-5) and strain ratio
  
  
    Celebi
    2012
    47
    75
    36/39
    81
    32/49
    81/0
    Scoring system (1-4)
  
  
    Dumitriu
    2010
    50
    57
    N/A
    57
    13/44
    48/9
    Strain ratio



Table 1:  Characteristics of the included studies.

Quality assessment of included studies

Quality of included studies was evaluated by means of QUADAS questionnaire and information is present in (Table 2).

Table 2: Quality assessment of included studies.




  
    Author 
    Q1 
      Spectm 
      composion
    Q2 
      Selecton 
      criteria 
    Q3 
      Appropriate 
      reference 
      standard 
       
    Q4 
      Disease 
      Progression bias
    Q5 
      Partial 
      verification 
      bias 
    Q6 
      Differential 
      verification 
      bias 
       
    Q7 
      Incorporation 
      bias
    Q8 
      Test 
      execution 
      details
    Q9 
      Reference 
      execution 
      details 
    Q10 
      Test review 
      bias
    Q11 
      Diagnostic 
      review 
      bias
    Q12 
      Clinical 
      review 
      bias 
    Q13 
      Intermediate 
      results 
    Q14 
      Withdrawals
  
  
    Bhatia
    Yes s
    yes
    Yes
    Yes
    Yes
    Yes
    Yes
    Yes
    Yes
    Yes
    Yes
    Yes
    Un clear
    Un clear
  
  
    Dumitru
    Yes
    Yes
    Yes
    No
    Yes
    Yes
    Yes
    Yes
    Yes
    Yes
    Un clear
    Un clear
    Un clear
    Un clear
  
  
    Yerli
    Yes
    Yes
    Yes
    No
    Yes
    Yes
    Yes
    Yes
    Yes
    Un clear
    Un clear
    Yes
    Un clear
    Un clear
  
  
    Wierzbicka
    Yes
    Yes
    Yes
    No
    Yes
    Yes
    Yes
    Yes
    Yes
    Un clear
    Un clear
    Yes
    Un clear
    Un clear
  
  
    Celebi
    Yes
    Yes
    Yes
    Un clear
    Un clear
    Yes
    Yes
    Yes
    Yes
    Un clear
    Un clear
    Yes
    Un clear
    Un clear
  
  
    Dumitru
    Yes
    Yes
    Yes
    Un clear
    Un clear
    Yes
    Yes
    Yes
    Yes
    Un clear
    Un clear
    Yes
    Un clear
    Un clear



Table 2:  Quality assessment of included studies.

The summary sensitivity and specificity for the differentiation of benign and malignant salivary gland masses were 0.63 and 0.59. The summary Diagnostic OR (D OR), positive and negative LRs were 3.18, 1.63 and 0.61 (Table 3).

Table 3: Summary estimates of sonoelastography.




  
     
    (95%CI)
  
  
    Sensitivity
    0.63 (0.52-0.73)
  
  
    Specificity
    0.59(0.53-0.65)
  
  
    Diagnostic    OR (DOR)
    3.18(1.86-5.44)
  
  
    Positive LR
    1.63(1.33-2.01)
  
  
    Negative LR
    0.61(0.47-0.79)
  
  
    The Area Under the Curve (AUC) was    0.68 (SE=0.03).



Table 3:  Summary estimates of sonoelastography.

Test of heterogeneity

All measurements showed homogeneity (I²<50%) in differentiating benign and malignant salivary gland masses except specificity (I2> 50%).

Discussion

This is the first systematic review evaluating diagnostic accuracy of sonoelastography in differentiating benign and malignant salivary gland tumors.

The results of current study demonstrated that sonoelastography has modest accuracy in differentiating benign and malignant salivary gland tumors. The pooled sensitivity was 63% and pooled specificity was 59%. The summary diagnostic OR was 3.18 which could be indicative that the odds of obtaining a test positive result in malignant rather than benign tumors is three.

Salivary gland tumors form a wide group of masses which could locate in major or minor salivary glands. It is crucial to determine if the pathology of the salivary gland mass is benign or malignant as lateral parotidectomy or extra capsular dissection could be applied for benign masses and total or radical parotidectomy along with neck dissection could be planned for malignant masses [12,13].

	(95%CI)
Sensitivity	0.63 (0.52-0.73)
Specificity	0.59(0.53-0.65)
Diagnostic OR (DOR)	3.18(1.86-5.44)
Positive LR	1.63(1.33-2.01)
Negative LR	0.61(0.47-0.79)
The Area Under the Curve (AUC) was 0.68 (SE=0.03).