Pancreatic Iodine Density and Fat Fraction on Dual-Energy Computed Tomography in Acute Pancreatitis.

The aim of our study was to investigate iodine density (ID) and fat fraction (FF) on dual-energy computed tomography (DECT) in patients with acute pancreatitis (AP). This retrospective study included 72 patients with clinically confirmed AP and 62 control subjects with DECT of the abdomen. Two radiologists assessed necrosis and measured attenuation values, ID, and FF in three pancreatic segments. We used receiver operating characteristic (ROC) analysis to determine the optimal threshold for ID for the differentiation between AP groups. The ID was significantly higher in interstitial edematous AP compared to necrotizing AP and the control group (both p < 0.05). The ROC curve analysis revealed the thresholds of ID for detecting pancreatic necrosis ≤ 2.2, ≤2.3, and ≤2.4 mg/mL (AUC between 0.880 and 0.893, p > 0.05) for the head, body, and tail, respectively. The FF was significantly higher for pancreatitis groups when compared with the control group in the head and body segments (both p < 0.001). In the tail, the difference was significant in necrotizing AP (p = 0.028). The ID values were independent of attenuation values correlated with the FF values in pancreatic tissue. Iodine density values allow for differentiation between morphologic types of AP.

Virtual monoenergetic dual-energy CT reconstructions at 80 keV are optimal non-contrast CT technique for early stroke detection.

BACKGROUND: Virtual monoenergetic (VM) dual-energy computed tomography (DE-CT) enables grey-to-white matter contrast-to-noise ratio optimization, potentially increasing ischaemic brain oedema visibility. The aim of this study was to compare the diagnostic accuracy of VM and standard DE-CT reconstructions for early stroke detection. METHODS: Consecutive patients with non-contrast DE-CT of the brain scanned within 12 h of stroke symptom onset were prospectively included in the study. Patients with other significant brain pathology were excluded. Two radiologists jointly evaluated standard and VM reconstructions (from 40 to 190 keV at increments of 10 keV) for early stroke signs on a four-point Likert scale: (a) stroke definitely present, (b) stroke probably present, (c) probably no stroke, and (d) definitely no stroke. Follow-up imaging and clinical data served as the standard of reference. Diagnostic accuracy was evaluated by receiver operating characteristic analysis. RESULTS: Stroke incidence among 184 patients was 76%. In 64 patients follow-up imaging served as the standard of reference: ischemic brain oedema detection was significantly more accurate on VM reconstructions at 80 keV compared with standard DE-CT reconstructions (area under the curve (AUC) = 0.821 vs. AUC = 0.672, p = 0.002). The difference was most prominent within the first 3 h after symptom onset (at 11%, AUC = 0.819 vs. AUC = 0.709, p = 0.17) and in patients with National Institutes of Health Stroke Scale above 16 (at 37.5%, AUC = 1 vs. AUC = 0.625, p = 0.14). CONCLUSION: VM DE-CT reconstructions at 80 keV appear to be the optimal non-contrast CT technique for diagnosing early ischaemic stroke, particularly within the first 3 h after symptom onset and in severely ill patients.

Comparing image quality of single- and dual-energy computed tomography of the brain.

PURPOSE: Weighted average dual-energy computed tomography (DE-CT) reconstructions are considered a proxy of standard CT images of the brain, recommended for routine clinical use and used as a reference standard in DE-CT research. However, their image quality has not been assessed, which was the aim of our study. METHODS: Images from 81 consecutive patients who underwent both non-contrast single-energy (SE)-CT and DE-CT of the brain on the same scanner were retrospectively evaluated. Attenuation values (HU) and SD of grey matter/white matter (GM/WM) pairs, along with SD in the posterior fossa and subcalvarial region were measured. Four readers evaluated image noise, GM/WM contrast, posterior fossa and subcalvarial artefacts, as well as overall image quality. RESULTS: Weighted average DE-CT GM and WM HU were significantly lower and noise higher compared to SE-CT (GM HU 36.46 v. 41.82; WM HU 28.18 v. 29.94; GM SD 2.93 v. 2.49; and WM SD 3.16 v. 2.44, all p < 0.0001). After correcting the measured SE-CT noise for 37% higher acquisition dose, DE-CT GM noise became significantly lower (2.93 v. 3.11, p = 0.0121). Measured and dose corrected SE-CT GM/WM contrast-to-noise ratio was superior to weighted average DE-CT (3.42 and 2.74 v. 1.95, both p < 0.0001). Weighted average DE-CT had significantly less artifacts on qualitative analysis. CONCLUSION: Weighted average DE-CT images of the brain yield less artefacts at 37% dose reduction and lower noise at SE-CT equivalent dose. Dose-adjusted GM/WM contrast-to-noise ratio of weighted average DE-CT with 0.4 weighting factor remains inferior to SE-CT images.

A simple prognostic model for assessing in-hospital mortality risk in patients with acutely decompensated heart failure.

Background An assessing of the in-hospital mortality risk for an emergency hospitalized patient with acutely decompensated heart failure (ADHF) is challenging task. Simple formula can help. Methods On the base of six indicators identified in derivation group, simple formula for assessing the risk for in-hospital mortality of ADHF patients was derived and later tested in validation group. Results The retrospective analysis of a derivation group (533 survivors, 121 deceased) identified six risk indicators: age, heart rate (HR), systolic blood pressure (SBP) and serum concentrations of urea, sodium (Na) and uric acid (UA). The final formula was created ([age/10]2 × HR/SBP)+(Urea-Na/10)+UA/100 and formula result of 53 was established as cut-off result. In the derivation group, at the cut-off point of 53, area under the ROC curve (AUC) was 0.741 (95% CI 0.701-0.776); with sensitivity 54% and specificity 83%. The discriminative capacity of the formula was significantly higher than each of its components. In the validation group of 591 patients (527 survived, 64 died) AUC was also 0.741 (95% CI 0.706-0.774), sensitivity was 66% and specificity 76%. Positive predictive value (PPV) of the developed formula was modest (34%), but negative predictive value (NPV) was 95%. N-terminal pro-B type natriuretic peptide and troponin I were determined, but not included into formula. Conclusions The developed formula enables simple, rapid and inexpensive risk assessment, but its disadvantage is a low PPV. However, a high NPV permits the identification of patients with a low risk of in-hospital mortality, which could lead to a more rational patient treatment.

Can the difference in serum concentration of urea and cystatin C be used in diagnosis and prognosis of heart failure?

Changes in renal function are an important diagnostic and prognostic indicator in patients with heart failure (HF). They are caused by decreased renal perfusion and consequently decreased glomerular filtration rate (GFR), or by the effect of increased neurohormonal activity (sympathetic nervous system [SNS], rennin-angiotensin-aldosterone system [RAAS] and arginine vasopressin [AVP]). However, the increase of serum concentration of urea, creatinine and other metabolites is not specific for HF. Therefore, it is not possible to distinguish HF from renal diseases solely based on the increase of their concentration, since the increase of their concentration caused by the decrease of GFR cannot be differentiated from the increase due to neurohormonal activity. Urea and cystatin C (Cys C) have different mechanisms of renal elimination, so it can be assumed that in HF their concentrations will not be increased proportionally, what can be used for diagnostic and prognostic purposes. After glomerular filtration Cy C undergoes proximal tubular reabsorption and breakdown, without returning to the blood flow. Since it is not secreted, its serum concentration depends only on GFR. In contrast to Cys C, urea is filtered in glomerulus and subsequently reabsorbed in proximal tubules and collecting duct. Reabsorption of urea is modified by effects of SNS, RAAS and AVP. Therefore its serum concentration depends upon GFR and neurohormonal effect on the tubular function. Since the increase of serum concentration of Cys C is caused only by the effect of the decreased renal perfusion on GFR, while the increase of urea is a result from both decreased GFR and tubular effects of increased neurohormonal activity, the paper hypothesis is that in HF the increase of urea will be significantly higher than the increase of serum Cys C, while in the patients with renal diseases their increase would be mostly proportional. It can be assumed that the disproportion between the increase of Cys C and urea would indicate an increased neurohormonal activity in patients with HF and correlate with its activity. If this hypothesis is proved correct, this parameter could be used in HF diagnosis and risk stratification of such patients.