This review found that diffusion-weighted magnetic resonance imaging was potentially technically feasible to differentiate malignant from benign focal liver lesions. These conclusions were supported by the data, but should be interpreted with caution due to the possibility of missed studies and a lack of details on study quality.

To evaluate the ability of diffusion weighted magnetic resonance imaging (DW-MRI) to differentiate malignant hepatic tumours from benign lesions.

MEDLINE, EMBASE, Web of Science and Cochrane Central Register of Controlled Trials (CENTRAL) were searched from inception to October 2009. Search terms were reported and included a diagnostic filter. Abstract books, conference proceedings and review articles were screened. No language restrictions were applied. Studies available only as abstracts were excluded.

Studies that evaluated the accuracy of DW-MRI for diagnosis of malignant hepatic lesions and that reported sufficient data to construct a 2x2 table of test performance were eligible for inclusion. Inclusion criteria were not defined in terms of reference standard, but studies were required to report details of the reference standard used in the methods section.

Included studies were conducted in Japan, France, Netherlands, Germany, Turkey, Greece, Belgium, UK and USA. All studies used 1.5 Tesla scanner systems. Where reported, thresholds on DW-MRI ranged from 1.47 to 5.5 x10³mm/s². Reference standards consisted of combinations of surgical specimens/resection, biopsy, follow-up imaging, pathology and clinical follow-up.

Two reviewers independently selected studies for inclusion; disagreements were resolved through consensus.

Two reviewers independently assessed study quality using QUADAS criteria with studies assigned a summary score based on the number of items fulfilled. Disagreements were resolved through consensus.

Two reviewers independently extracted data to construct 2x2 tables of test performance. These data were used to calculate sensitivity, specificity, positive and negative likelihood ratios and diagnostic odds ratios (DOR) together with 95% confidence intervals (CIs). Disagreements were resolved through consensus.

Summary estimates of sensitivity and specificity together with 95% CIs were calculated using the bivariate random-effects model. Summary receiver operating characteristic (SROC) plots were calculated; details on the method used were not reported. Heterogeneity was assessed graphically using funnel plots and statistically using the Cochrane Q test and I² statistic. Heterogeneity in sensitivity and specificity was assessed using meta-regression analysis. Spectrum characteristics, QUADAS score and methodological features (such as sample size) variables were added to the model. Publication bias was assessed using funnel plots and the Egger test.

Fourteen studies (804 patients, 1,665 hepatic lesions) were included. QUADAS scores ranged from 8 to 12.

Sensitivity ranged from 74% to 100%. Summary sensitivity was 91% (95% CI 86% to 94%). Specificity ranged from 77% to 100%. Summary specificity was 93% (95% CI 86% to 97%). There was substantial heterogeneity for both sensitivity (I²=82%) and specificity (I²=82%).

The only variable to be significantly associated with sensitivity in the meta-regression analysis was sensitivity encoding (p=0.03), which indicated that the SENSE technique may have affected accuracy.

Diffusion-weighted MRI was potentially technically feasible to differentiate malignant from benign focal liver lesions.

The review addressed a clear question. Inclusion criteria were defined. The literature search included relevant databases and no language restrictions were applied. However, use of a diagnostic filter and a lack of specific attempts to locate unpublished studies meant that relevant studies may have been missed. Publication bias was assessed in the review, but the methods used were not appropriate for diagnostic data. Appropriate steps were taken to minimise bias and errors at all stages of the review. Study quality was formally assessed using accepted criteria. But, results were presented as summary quality scores (not appropriate for QUADAS), which made the validity of the included studies unclear. Only limited study details were presented, especially in terms of patients. Appropriate methods were used to pool sensitivity and specificity, although no details on methods used to construct SROC curves were reported. Heterogeneity was formally assessed and investigated and the results were clearly presented with the aid of graphical summaries.

The authors' conclusions were supported by the data, but should be interpreted with caution due to the possibility of missed studies and a lack of details on study quality.

Practice: The authors stated that the evidence presented supported use of DW-MRI in clinical practice, but that DW-MRI may not be a sufficient test for solid lesions due to its low specificity.

Research: The authors stated that further studies were required in order to analyse apparent diffusion coefficient cutoff (ADC) of the corresponding type of malignant hepatic lesions.

Not stated.

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.