Evaluation of the Pulmonary Arteries on CTPA With Dual Energy CT: Objective Analysis and Subjective Preferences in a Multireader Study.

PURPOSE: To perform qualitative and quantitative evaluation of low-monoenergetic images (50 KeV) compared with conventional images (120 kVp) in pulmonary embolism (PE) studies and to determine the extent and clinical relevance of these differences as well as radiologists' preferences. MATERIALS AND METHODS: One hundred fifty CT examinations for PE detection conducted on a single-source dual-energy CT were retrospectively evaluated. Attenuation, contrast-to-noise-ratio, and signal-to-noise-ratio were obtained in a total of 8 individual pulmonary arteries on each exam-including both central (450/1200=37.5%) and peripheral (750/1200=62.5%) locations. Results were compared between the conventional and low-monoenergetic images. For quality assessment, 41 images containing PE were presented side-by-side as pairs of slices in both conventional and monoenergetic modes and evaluated for ease in embolus detection by 9 radiologists: cardiothoracic specialists (3), noncardiothoracic specialists (3), and residents (3). Paired samples t tests, a-parametric Wilcoxon test, McNemar test, and kappa statistics were performed. RESULTS: Monoenergetic images had an overall statistically significant increased average ratio of 2.09 to 2.26 ( P <0.05) for each measured vessel attenuation, with an increase in signal-to-noise ratio (23.82±9.29 vs. 11.39±3.2) and contrast-to-noise ratio (17.17±6.7 vs 7.27±2.52) ( P <0.05). Moreover, 10/150 (6%) of central pulmonary artery measurements considered suboptimal on conventional mode were considered diagnostic on the monoenergetic images (181±14.6 vs. 387.7±72.4 HU respectively, P <0.05). In the subjective evaluation, noncardiothoracic radiologists showed a preference towards low-monoenergetic images, whereas cardiothoracic radiologists did not (74.4% vs. 57.7%, respectively, P <0.05). CONCLUSIONS: The SNR and CNR increase on monoenergetic images may have clinical significance particularly in the setting of sub-optimal PE studies. Noncardiothoracic radiologists and residents prefer low monoenergetic images.

The syndrome of inappropriate antidiuresis: pathophysiology, clinical management and new therapeutic options.

Hyponatremia is a marker of different underlying diseases and it can be a cause of morbidity itself; this implies the importance of a correct approach to the problem. The syndrome of inappropriate antidiuresis (SIAD) is one of the most common causes of hyponatremia: it is a disorder of sodium and water balance characterized by urinary dilution impairment and hypotonic hyponatremia, in the absence of renal disease or any identifiable non-osmotic stimulus able to induce antidiuretic hormone (ADH) release; according to its definition, it is diagnosed through an exclusion algorithm. SIAD is usually observed in hospitalized patients and its prevalence may be as high as 35%. The understanding of the syndrome has notably evolved over the last years, as reflected by the significant change in the name, once the syndrome of inappropriate secretion of ADH (SIADH), today SIAD. This review is up to date and it analyses the newest notions about pathophysiological mechanisms, classification, management and therapy of SIAD, including vaptans.