MRI enhances diagnostic certainty of ovarian cancer following indeterminate ultrasound [Classics Series]

This study summary is an excerpt from the book 2 Minute Medicine’s The Classics in Medicine: Summaries of the Landmark Trials

1. In women with an indeterminate ovarian mass on ultrasonography, magnetic resonance imaging (MRI) provided a significantly higher change in post-test probability compared to computed tomography (CT) or Doppler ultrasound.

Original Date of Publication: July 2005

Study Rundown: Ovarian cancer is the second most common gynecological malignancy with a world-wide incidence of 11.9 cases per 100 000 women. Accurate diagnosis of patients presenting with adnexal masses is crucial to allow timely surgical diagnosis and intervention. Although ultrasound is the first-line imaging modality in women for assessment of a suspicious adnexal mass, at the time of this study there was no evidence-based consensus on the management options for patients following an indeterminate adnexal mass on ultrasonography. The purpose of this landmark meta-analysis was to determine the optimal second-line imaging modality to assess an indeterminate ovarian mass on ultrasound for both pre- and post-menopausal women. The trial performed a literature review to determine the prevalence of ovarian cancer in patients presenting with an adnexal mass as well as the sensitivity and specificity of Doppler ultrasound, CT, and MRI in the characterization of adnexal masses following ultrasonography. The change in pre- and post-test probabilities was calculated for each imaging modality. At the conclusion of the trial, the use of any additional imaging modalities was associated with a significant increase in post-test probability for both pre- and post-menopausal women. However, MRI demonstrated significantly higher diagnostic certainty in post-test probability for ovarian cancer compared to Doppler US or CT in both pre- and post-menopausal women. The positive likelihood ratio for contrast-enhanced MRI was 10-fold higher than Doppler US and approximately 7-fold higher than CT. The results of this trial demonstrate that in both pre- and post-menopausal women with an indeterminate ovarian mass on ultrasonography, second-line imaging is warranted to improve diagnostic certainty for ovarian cancer. Additionally, MRI is the ideal second line imaging modality and provides a significantly higher level of diagnostic certainty in comparison to Doppler US or CT. The study was limited by the absence of integration of serum CA-125 into the diagnostic algorithm of adnexal masses, which may have improved diagnostic certainty. Nevertheless, this study served to inform the use of MRI as the second line imaging modality to determine the need for surgical evaluation of suspected ovarian cancer in both pre- and post-menopausal women.

Click to read the study in Radiology

In-Depth [meta-analysis]: The authors performed a literature review of English-language studies using MEDLINE database to determine the pre-test probability of ovarian cancer in pre- and post-menopausal women. The authors performed a literature review of 83 articles which met the following inclusion criteria: 1) presence of adnexal mass not detected during screening; 2) availability of histopathological information. Two experienced readers abstracted data from each article and disagreements were resolved with consensus. A similar methodology was utilized for a literature review of 12 articles to determine the sensitivity and specificity of ovarian mass characterization by Doppler US, CT, and MRI. Positive and negative likelihood ratios were calculated from the average weighted means of sensitivity and specificity. At the conclusion of the trial, the post-test probability following an indeterminate US result was 25% and 63% for pre- and post-menopausal women, respectively. Robust negative LR following initial indeterminate US result were seen for Doppler US (0.19), CT (0.22), and contrast-enhanced MRI (0.2). With respect to positive LR, contrast-enhanced MRI (44.2) was significantly more robust compared to Doppler US (4.69) and CT (6.81). This effect was seen in both pre- and post-menopausal women.

Kinkel K, Lu Y, Mehdizade A, Pelte M-F, Hricak H. Indeterminate Ovarian Mass at US: Incremental Value of Second Imaging Test for Characterization—Meta-Analysis and Bayesian Analysis. Radiology. 2005 Jul 1;236(1):85–94.

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