Elsevier

Academic Radiology

Volume 27, Issue 4, April 2020, Pages e64-e71
Academic Radiology

Original Investigation
Sequence and Observer Variability in Gadoxectic Acid-Enhanced MRI Lesion Measurements in Hepatocellular Carcinoma

https://doi.org/10.1016/j.acra.2019.05.021Get rights and content

Rationale and Objectives

The purpose of the study was to investigate interobserver and intersequence variability in measuring hepatocellular carcinoma on magnetic resonance imaging (MRI).

Methods and Materials

Twenty treatment-naïve lesions on Gadoxetic Acid enhanced MRI scans from 20 patients were retrospectively measured by six reviewers with different levels of experience, twice, six weeks apart, on eight different MRI sequences, in randomized order. The sequences include arterial, hepatobiliary, transitional, portal venous, T2, and diffusion weighted images. The single longest diameter (SLD) and longest diameter perpendicular to the longest overall diameter were measured on axial images and products of diameters calculated in accordance to response evaluation criteria in solid tumors v1.1 and World Health Organization response criteria respectively. Lesion-wise intraclass correlation coefficients were used to estimate measurement agreement.

Results

All intraclass correlation coefficients were greater than 0.95. No substantive differences between SLD and products of diameters metrics. Means (∼2.8 mm, SLD) and standard deviations (∼2 mm, SLD) were similar across sequences and observers. Similarly, pairwise comparison between observers grouped by experience showed statistically significant differences, but the effect size was minor (∼2 mm). Arterial and HPB-weighted images had similar mean dimensions (2.76 cm) while the smallest mean was in the transitional phase (2.62 cm). A lesion was not measured on 140 occasions (7%), mostly in ADC.

Conclusion

There is high interobserver and intersequence reliability despite small differences between observers based on experience level. Our results suggest that accurate measurements can be made on arterial phase despite the possibility of indistinct margins. Lesions, however, are more likely to be missed on diffusion-related sequences.

Section snippets

INTRODUCTION

Hepatocellular carcinoma (HCC) has an annual global death rate of around 700,000, ranking third among types of cancer for lethality (1, 2). Cross-sectional imaging such as magnetic resonance imaging (MRI) plays a major role in clinical practice for characterizing and diagnosing focal liver lesions, where international guidelines including the American Association for the Study of Liver Disease, European Association for the Study of the Liver, the Asian Pacific Association for the Study of the

Patient Selection

Patients who had undergone GA-enhanced MRI between 2015 and 2016 with suspected HCC were identified from our departmental database. A board-certified radiologist with 10 years of experience in abdominal imaging (KC) reviewed all the MRI images and a subset of 20 chronologically consecutive patients with a solitary HCC diagnosis (lesions with arterial enhancement and hypointensity on portal venous or transitional phases) was chosen for analysis. Of the 20 lesions chosen, eight had irregular or

RESULTS

In total 1920 (20 × 8 × 6 × 2) measurements of both SLD and PD were recorded. A lesion was not visible to the reviewer on 140 occasions (7% of all lesion measurements), most often in ADC (33% of all missed), and least often in the arterial (on one occasion) (Fig 1). In total 71% of the unobserved lesions were on one of the three DWI related sequences (B0, B500, ADC) (Table 2). When paired by observer experience, intrapair differences in missed lesions are smaller than interpair differences,

DISCUSSION

To our knowledge, this is the first study to examine intersequence and interobserver variability in GA-enhanced MRI imaging, examining the magnitude of effects one can expect based on observer and sequence type. Currently arterial, portal venous, and transitional phases are essential for the diagnosis of HCC in most guidelines; the other sequences are for increasing diagnostic confidence. However, unlike conventional extracellular gadolinium contrast agents, GA is a hepatobiliary-specific

Acknowledgments

We would like to acknowledge the help of Claudia Cheung and Brian Lee with the data acquisition.

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    Funding: Nothing to declare.

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