Subjective assessment of right ventricle enlargement from computed tomography pulmonary angiography images

Abstract

Driven by the evolution of technology Computed Tomography (CT) has become the methodology of choice to confirm or exclude the clinical suspicion of pulmonary artery embolism (PE) [1–6]. With its high temporal and spatial resolution, multi-detector CT has shown unique abilities in characterizing pulmonary embolisms with high sensitivity and specificity and is now serving as the sole reference standard for pulmonary embolism imaging in many institutions [7–9]. Most recent technological advancements, such as dual-energy imaging, further refine CT’s capabilities by allowing the visualization of iodine distribution throughout the lung parenchyma [10–12]. Solidified by significant scientific data and research efforts in the diagnosis of pulmonary embolism, the important question no longer concerns demonstrating CT’s clinical value in diagnosing pulmonary embolism, but optimizing the use in various clinical settings and patient categories. Based on results of investigative trials, such as Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) II, diagnostic algorithms and clinical pathways have been proposed to formulate the appropriate indication of CT in the rule-out of PE [5, 13–15]. In a quest to evolve CT’s competence beyond a pure as-is state interpretation into a tool for prognosis, applying the concept of evaluating the size and function of the right ventricle (RV) for risk assessment has been studied [16–18]. Initiated by the study of Reid et al., various studies compared right-ventricular measurements and ratios of right-ventricular diameters to left-ventricular (LV) diameters in a variety of image reconstructions, from true 4-chamber views to axial images [19–23]. Besides one-dimensional measurements, volumetric assessment of the right ventricle, although more timeconsuming, has been shown to be superior in the identification of high-risk patients [24]. In the current issue of the International Journal of Cardiovascular Imaging, Kumamaru et al. investigate a straightforward approach for the quantification of the size of the right ventricle. They hypothesized that a clear-cut, subjective visual assessment of rightventricular sizes on axial CT pulmonary angiography images is highly correlated with quantitative measurements. To validate their hypothesis, Kumamaru et al. evaluated the accuracy of their straightforward methodology using axial images and compared their findings to the prognostic accuracy of more traditional, quantitative RV/LV diameter ratios. Without using measurement tools, Kumamaru et al. had two readers retrospectively analyze axial CT images of 200 patients diagnosed with acute PE by CT pulmonary angiography to subjectively determine Editorial comment on the article of Kumamaru et al. (doi: 10.1007/s10554-011-9903-5).