Clinical Significance of Gray to White Matter Ratio after Cardiopulmonary Resuscitation in Children

Cardiopulmonary resuscitation (CPR) successfully restores systemic circulation approximately 50% of the time; however, many successfully restored patients have severe neurologic damage. In adults, the gray matter to white matter attenuation ratio (GWR) in brain computed tomography (CT) correlates with the neurologic outcome. However, in children, the clinical significance of GWR still remains unclear. The aim of this study was to evaluate the clinical characteristics of children who underwent CPR for cardiac arrest according to the survival and to demonstrate the differentiation of grey/white matter by Hounsfield units of brain CT and to characterize the attenuations of grey and white matters. Methods: This is a retrospective single-center study. We enrolled those who underwent brain CT within 24 h after return of spontaneous circulation (ROSC) from January 2005 to June 2018. Brain CTs were taken within 24 h of ROSC. We measured the attenuation of grey and white matter in Hounsfield units and calculated GWR. They were compared with healthy controls. Patients were analyzed as follows: survivors vs. non-survivors and better neurologic outcome vs. worse neurologic outcome. Results: Among 100 pediatric patients who had CPR, 56 met inclusion criteria. There were 24 patients who survived and 32 non-survivors. Our study revealed that the incidence of seizure, duration of CPR, and instances of hypothermia were significantly different between survivors and non-survivors. In both survivors and non-survivors, the attenuation of the caudate nucleus, putamen, GWR-basal ganglia, and average GWR were significantly different from controls. In regression analyses, the medial cortex and average GWR were the significant variables to predict survival, and the receiver operating curves revealed areas under curve of 0.733 and 0.666, respectively. Also, the medial cortex 1 was the only variable that predicted the neurologic outcome. Conclusions: There was some predictive survival value of GWR and medial cortex at the centrum semiovale level in early brain CT within 24 h after cardiac arrest. Although we could not find the predictive value of GWR in the neurologic outcome of pediatric patients, we found that the absolute attenuation of the medial cortex was low in patients with worse neurologic outcomes. Further prospective, multicenter studies are needed to determine the predictive value of GWR and the medial cortex.

Clinical Use of Tailored Computed Tomography to Prevent Poststernotomy Dehiscence

Background Morphological and tissue density analysis of the sternum can be performed in the preoperative computed tomography (CT). The purpose of this study was to analyze morphology and tissue density of sternum in CT and effect for comparison sternal instability. Methods Patients with sternal instability (n = 61) and sternal stability (n = 66) were enrolled in this study. All of the patients were studied using same thorax CT procedure. All the measurements were performed by one specific cardiovascular radiologist. The Hounsfield units (HUs) were measured in axial sections of the sternum trabecular bone. Results Sternal instability group mean HU was 75.36 ± 13.19 and sternal stability group HU was 90.24 ± 12.16 (p < 0.000). HU is the statically significant predictor of sternal instability. Conclusion Our study showed a significant correlation between the mean HU value of sternum and sternal instability. We think that it is important to evaluate the existing thorax CT while performing preoperative risk analysis for sternal dehiscence.

Intracranial Lesion Detection and Artifact Characterization: Comparative Study of Susceptibility and T2*-Weighted Imaging in Dogs and Cats

Susceptibility-weighted imaging (SWI), an MRI sequence for the detection of hemorrhage, allows differentiation of paramagnetic and diamagnetic substances based on tissue magnetic susceptibility differences. The three aims of this retrospective study included a comparison of the number of areas of signal void (ASV) between SWI and T2*-weighted imaging (T2*WI), differentiation of hemorrhage and calcification, and investigation of image deterioration by artifacts. Two hundred twelve brain MRIs, 160 dogs and 52 cats, were included. The sequences were randomized and evaluated for presence/absence and numbers of ASV and extent of artifacts causing image deterioration by a single, blinded observer. In cases with a CT scan differentiation of paramagnetic (hemorrhagic) and diamagnetic (calcification) lesions was made, SWI was performed to test correct assignment using the Hounsfield Units. Non-parametric tests were performed to compare both sequences regarding detection of ASV and the effect of artifacts on image quality. The presence of ASV was found in 37 SWI sequences and 34 T2*WI sequences with a significant increase in ASV only in dogs &gt;5 and ≤ 15 kg in SWI. The remaining weight categories showed no significance. CT examination was available in 11 cases in which 81 ASV were found. With the use of phase images, 77 were classified as paramagnetic and none as diamagnetic. A classification was not possible in four cases. At the level of the frontal sinus, significantly more severe artifacts occurred in cats and dogs (dogs, p &lt; 0.001; cats, p = 0.001) in SWI. The frontal sinus artifact was significantly less severe in brachycephalic than non-brachycephalic dogs in both sequences (SWI, p &lt; 0.001; T2*WI, p &lt; 0.001). In conclusion, with the advantages of better detection of ASV in SWI compared with T2*WI and the opportunity to differentiate between paramagnetic and diamagnetic origin in most cases, SWI is generally recommended for dogs. Frontal sinus conformation appears to be a limiting factor in image interpretation.

Non-lipid-rich low attenuation plaque with intraplaque haemorrhage assessed by multimodality imaging: a case report

Background The lipid-rich necrotic core is a major pathological hallmark of acute coronary syndrome. Low attenuation plaque (LAP) on coronary computed tomography angiography (CCTA), defined as plaque CT attenuation of &lt;30 Hounsfield units, is commonly believed to correspond to the lipid component. This report presents a non-lipid-rich LAP with intraplaque haemorrhage of the left main coronary artery (LM), as assessed by CCTA, near-infrared spectroscopy (NIRS), and non-contrast magnetic resonance imaging (MRI) using coronary atherosclerosis T1-weighted characterisation with integrated anatomical reference technique, recently developed by our group. Case Summary A 75-year-old woman presented with chest discomfort on exertion. CCTA revealed severe stenosis of the mid-left circumflex coronary artery and minimal stenosis with a large eccentric LM plaque. The LM lesion had an LAP, with a minimum plaque attenuation of 25 Hounsfield units. On non-contrast T1-weighted MRI, a high-intensity plaque with a plaque-to-myocardium signal intensity ratio of 3.02 was observed within the vessel wall, indicating intraplaque haemorrhage. NIRS categorised the lesion as non-lipid-rich, with a maximum lipid core burden index in 4 mm of 169. Discussion Intraplaque haemorrhage is a key feature of plaque instability, which is different from the lipid-rich necrotic core. Non-contrast T1-weighted MRI is ideal for detecting intraplaque haemorrhage with short T1 values. The imaging findings suggest that LAP on CCTA may represent not only lipid-rich plaques but also intraplaque haemorrhage. MRI provides a unique insight into plaque vulnerability from a different perspective than lipid assessment. Multimodality imaging, including MRI, facilitates the understanding complicated plaque morphologies.

A study on relationship of Hounsfield Units value on non-contrast computer tomography and recanalization of intravenous thrombolysis

Objective: To determine whether the administration of intravenous alteplase would be beneficial or futile to patients with acute ischemic stroke caused by large vessel occlusion (LVO) before endovascular treatment (EVT), we conducted this study to determine the relationship between Hounsfield units (HU) in non-contrast computed tomography (NCCT) and recanalization by alteplase. Methods: We performed a retrospective analysis of patients with acute ischemic stroke caused by LVO received intravenous thrombolysis (IVT) or followed by EVT at our center during November 2016 and October 2020. The clinical characteristics and imaging features of patients who achieved recanalization after IVT, and those who did not, were compared. Results: Forty-three eligible patients were enrolled; 12 achieved recanalization by IVT. Baseline clinical characteristics did not differ between patients of the recanalization and non-recanalization groups. HU in the NCCT were estimated and statistically significant maximum and mean values of the ipsilateral middle cerebral artery (MCA) were found between the groups (P< 0.05). The results hint that patients in the non-recanalization group have a higher rHU and δHU value of the ipsilateral MCA compared with recanalization group (P< 0.05). With regards the receiver operator characteristic (ROC) curve, we demonstrated that a high HU value of the ipsilateral MCA could be a predictor for non-recanalization by IVT. Conclusion: Patients suffering LVO stroke are less likely to obtain recanalization by IVT with a high HU value of the ipsilateral MCA. It is feasible to screen patients with LVO using HU for direct EVT.

Potential role of epicardial adipose tissue as a biomarker of anthracycline cardiotoxicity

Background We investigated the radiodensity of epicardial (EAT), subcutaneous (SAT), and visceral adipose tissue (VAT) before and after treatment with anthracyclines in a population of breast cancer (BC) patients, and in controls not treated with anthracyclines, to detect a potential role of EAT density as a biomarker of changes related to chemotherapy cardiotoxicity. Methods We reviewed BC patients treated with anthracyclines who underwent CT before (CT-t0) and after (CT-t1) chemotherapy, and age- and sex-matched controls who underwent two CT examinations at comparable intervals. On non-contrast scans, EAT was segmented contouring the pericardium and thresholding between -190 and -30 Hounsfield units (HU), and SAT and VAT were segmented with two 15-mm diameter regions of interest thresholded between -195 and -45 HU. Results Thirty-two female patients and 32 controls were included. There were no differences in age (p = 0.439) and follow-up duration (p = 0.162) between patients and controls. Between CT-t0 and CT-t1, EAT density decreased in BC patients (-66 HU, interquartile range [IQR] -71 to -63 HU, to -71 HU, IQR -75 to -66 HU, p = 0.003), while it did not vary in controls (p = 0.955). SAT density increased from CT-t0 to CT-t1 in BC patients (-107 HU, IQR -111 to -105 HU, to -105 HU, IQR -110 to -100 HU, p = 0.014), whereas it did not change in controls (p = 0.477). VAT density did not vary in either BC patients (p = 0.911) or controls (p = 0.627). Conclusions EAT density appears to be influenced by anthracycline treatment for BC, well known for its cardiotoxicity, shifting towards lower values indicative of a less active metabolism.

Assessment of the Homogeneity of Polymeric Materials Using Hounsfield Units

The X-ray transparency of various polymers and plastics is one of the most important factors in the choice of material in the design of new medical robotic and mechatronic systems and complexes. Along with the radiolucency, such a parameter as material inhomogeneity is also one of the main ones. The inhomogeneity of the material can not only affect the radiolucency of individual areas of the product but also impose restrictions on the use of polymeric materials by changing the physical and mechanical properties of the products. In this work, a technique was proposed for determining the location of regions of interest with reliable values on a CT image. Data were obtained for the values of the parameter HU and standard deviation for various polymer materials. A technique was proposed for determining the degree of heterogeneity of polymeric materials. The values of the degree of heterogeneity were obtained for all investigated materials.