Gui Fen Yang

Detection of Pulmonary Embolism Using Dual-Energy Computed Tomography and Correlation with Cardiovascular Measurements: A Preliminary Study

Background: Detection of a suspected pulmonary embolism (PE) has been the focus of considerable research over the past few decades. Recently developed dual-source computed tomography (DSCT) scanners with dual-energy mode have been used to detect PE, but the studies on this topic are few. Purpose: To assess the clinical value of dual-source, dual-energy CT (DECT) for the diagnosis of suspected PE and to correlate with cardiovascular measurements. Material and Methods: 31 patients with suspected PE underwent contrast-enhanced DSCT scanning with dual-energy mode. Dedicated software for lung perfusion blood volume (PBV) was used in postprocessing. The numbers and locations of PE in PBV images and CT pulmonary angiography (CTPA) were recorded. Sensitivity and specificity were measured, comparing to CTPA as a standard of reference. The relationship between range of iodine mapping abnormality in PBV images and cardiovascular measurements was analyzed. Results: 33 DECT scans were performed in 31 patients. Seventeen patients had PE, while 14 patients had negative results. Filling defects were detected in pulmonary arteries in 44 pulmonary lobar and 99 segmental arteries. Compared to CTPA as a standard of reference, sensitivity and specificity of PBV images were 93.8% and 93.3% on a per-patient basis, 93.2% and 94.7% on a per-lobe basis, and 76.1% and 97.6% on a per-segment basis, respectively. Spearman correlation test showed good positive correlation between the right ventricle (RV)/left ventricle (LV) diameter ratio and pulmonary lobes with emboli for PBV images (R=0.663; P=0.004). Conclusion: DECT can provide morphological and functional information of the whole lung in a single contrast-enhanced acquisition; the perfusion defects visualized in PBV images appear to have a positive relationship with the patients’ right heart dysfunction.

A Multifunctional PB@mSiO2–PEG/DOX Nanoplatform for Combined Photothermal–Chemotherapy of Tumor

In this work, we design mesoporous silica-coated Prussian blue nanocubes with PEGyltation to construct multifunctional PB@mSiO2-PEG nanocubes. The PB@mSiO2-PEG nanocubes have good biocompatibility, excellent photothermal transformation capacity, in vivo magnetic resonance and photoacoustic imaging ability. After loading antitumor drug doxorubicin (DOX) in the PB@mSiO2-PEG nanocubes, the constructured PB@mSiO2-PEG/DOX nanoplatforms show an excellent pH-responsive drug release character within 48 h, namely, an ultralow cumulative drug release amount of 3.1% at pH 7.4 and a high release amount of 46.6% at pH 5.0. Upon near-infrared laser irradiation, the PB@mSiO2-PEG/DOX nanoplatforms show an enhanced synergistic photothermal and chemical therapeutic efficacy for breast cancer than solo photothermal therapy or chemotherapy.

Dual-energy CT imaging of thoracic malignancies

Abstract Computed tomography (CT) plays a pivotal role in the detection, characterization, and staging of lung cancer and other thoracic malignancies. Since the introduction of clinically viable dual-energy CT techniques, substantial evidence has accumulated on the use of this modality for imaging chest malignancies. This article describes the principles of dual-energy CT along with suitable image acquisition, reconstruction, and postprocessing strategies for oncologic applications in the chest. The potential of dual-energy CT techniques for the detection, characterization, staging, and surveillance of chest malignancy, as well as the limitations of this modality are discussed.

Acute myocardial infarct detection with dual energy CT: correlation with single photon emission computed tomography myocardial scintigraphy in a canine model

Background Dual-energy CT (DECT) has been used to detect myocardial infarct. However, few comparable studies with histopathological findings as gold standard have been published. Purpose To investigate the accuracy of DECT iodine maps for detecting acute myocardial infarction compared with single photon emission computed tomography (SPECT) in a canine model using histopathological findings as the reference standard. Material and Methods A model of myocardial ischemia was created by ligating the left anterior descending (LAD) coronary artery after thoracotomy in six dogs, while another three dogs undergoing thoracotomy without LAD ligature served as a control group. Contrast-enhanced DECT scans of the heart were performed, followed by resting 99mTc-MIBI SPECT myocardial perfusion imaging in all nine dogs before and 3 h after the procedure. Triphenyltetrazolium chloride (TTC) staining was performed and analyzed. In the short axis of the left ventricle, the wall surface was divided into 17 segments, which were assessed for infarcted myocardium on conventional CT from average-weighted data, DECT myocardial iodine maps, conventional CT plus DECT, SPECT, and histopathology. Inter-observer and inter-modality agreement for conventional CT, DECT myocardial iodine maps, and SPECT were calculated. CT value of infracted and non-infracted areas was measured. Results With the histopathological results as the reference standard, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 75.0% (30/40), 92.0% (104/113), 76.9% (30/39), 91.2% (104/114), 87.6% (134/153) for conventional CT, 85.0% (34/40), 84.1% (95/113), 65.4% (34/52), 94.1% (95/101), 84.3% (129/153) for DECT myocardial iodine maps; 87.5% (35/40), 92.9% (105/113), 81.4% (35/43), 95.5% (105/110), 91.5% (140/153) for conventional CT plus DECT; 82.5% (33/40), 90.3% (102/113), 75.0% (33/44), and 93.6% (102/109), 88.2% (135/153) for SPECT, respectively. Excellent inter-observer agreement (Kappa value .0.8) and good inter-modality agreement (Kappa value >0.6) for each modality were found. CT values of infarcted myocardium (26±22 HU, 36±33 HU, 34±16 HU) were lower than those of non-infarcted myocardium (115±16 HU, 121±28 HU, 123±11 HU) on images of 140 kVp, 80 kVp, and average-weighted 120 kVp images (all P < 0.05). Conclusion With histopathology as the reference standard, DECT myocardial iodine maps can detect acute myocardial infarction with diagnostic accuracy comparable to resting SPECT myocardial perfusion imaging in a canine model. DECT plus conventional CT had a potential to improve the detection of acute myocardial infarction.

Thromboembolic complications in nephrotic syndrome: imaging spectrum

Thromboembolism is a well-known complication of nephrotic syndrome. Pulmonary embolism, renal vein thrombosis, and deep vein thrombosis are the most common venous thromboembolic diseases in patients with nephrotic syndrome, while arterial thromboembolic complications are observed less frequently. Imaging plays an important role in the detection and follow-up of thromboembolism in these patients. The purpose of this essay is to describe the epidemiology, pathophysiological mechanisms, the imaging diagnosis, and treatment of thromboembolism in patients with nephrotic syndrome.

Noninvasive Diagnosis of Bronchial Artery Aneurysm Using Dual-Source Computed Tomography Angiography

Bronchial artery aneurysm is a rare entity, detected in less than 1% of all patients undergoing selective bronchial arteriograms. Approximately 50 cases have been reported so far. Computed tomography (CT) reports of mediastinal bronchial artery aneurysms are rare. We report a case of a bronchial artery aneurysm in an 84-year-old male patient, which had been misdiagnosed as lung cancer for 6 years.

Three-dimensional contrast-enhanced magnetic resonance venography for detection of renal vein thrombosis: comparison with multidetector CT venography

Background Renal vein thrombosis is not uncommon, however, there have been few reports on the diagnostic accuracy of three-dimensional contrast-enhanced magnetic resonance venography (3D-CE-MRV) in the detection of renal vein thrombosis (RVT). Purpose To evaluate the value of 3D-CE-MRV for detecting RVT with multidetector computed tomography (CT) venography as reference standard. Material and Methods Thirty-two patients with nephrotic syndrome underwent renal CT venography and gradient echo pulse sequence (FLASH 3D) 3D-CE-MRV in a clinical 3-T whole-body MR scanner for suspected RVT with time interval of 0–5 days. RVT was recorded on a per-patient and per-vessel (left renal vein, right renal vein, and inferior vena cava) basis. The diagnostic accuracy of 3D-CE-MRV for detection of RVT was calculated with CT venography as reference standard. Inter-reader agreement for RVT detection was evaluated using Kappa statistics. Results Of 32 patients, CT venography detected 22 vessels with thrombosis in 17 patients, including five in right renal veins, 14 in left renal veins, and three in inferior vena cava, while 15 patients had no RVT. 3D-CE-MRV detected 21 vessels (21/96, 21.9%) with thrombosis in 16 patients (6/32, 50%), including five in right renal veins, 13 in left renal veins, and three in inferior vena cava, while 16 patients (16/32, 50%) had no RVT. With CT venography as reference standard, the sensitivities and specificities of 3D-CE-MRV for RVT detection were 94.1%, 100%; 95.5%, 100% on a per-patient and a per-vessel basis, respectively. Excellent inter-reader agreement (Kappa value = 0.969, P < 0.001) was observed for RVT detection. Conclusion 3D-CE-MRV has a high diagnostic accuracy in the detection of RVT, which is optimal alternative imaging modality in the detection of RVT.

Altered amygdala and hippocampus effective connectivity in mild cognitive impairment patients with depression: a resting-state functional MR imaging study with granger causality analysis

Neuroimaging studies have demonstrated that the major depression disorder would increase the risk of dementia in the older with amnestic cognitive impairment. We used granger causality analysis algorithm to explore the amygdala- and hippocampus-based directional connectivity patterns in 12 patients with major depression disorder and amnestic cognitive impairment (mean age: 69.5 ± 10.3 years), 13 amnestic cognitive impairment patients (mean age: 72.7 ± 8.5 years) and 14 healthy controls (mean age: 64.7 ± 7.0 years). Compared with amnestic cognitive impairment patients and control groups respectively, the patients with both major depression disorder and amnestic cognitive impairment displayed increased effective connectivity from the right amygdala to the right lingual and calcarine gyrus, as well as to the bilateral supplementary motor areas. Meanwhile, the patients with both major depression disorder and amnestic cognitive impairment had enhanced effective connectivity from the left superior parietal gyrus, superior and middle occipital gyrus to the left hippocampus, the z values of which was also correlated with the scores of mini-mental state examination and auditory verbal learning test-immediate recall. Our findings indicated that the directional effective connectivity of right amygdala - occipital-parietal lobe – left hippocampus might be the pathway by which major depression disorder inhibited the brain activity in patients with amnestic cognitive impairment.

18F-DPA-714 PET Imaging for Detecting Neuroinflammation in Rats with Chronic Hepatic Encephalopathy

Neuroinflammation is considered to be the pathogenesis of hepatic encephalopathy (HE), and imaging neuroinflammation is implicated in HE management. 11C-PK11195, a typical translocator protein (TSPO) radiotracer, is used for imaging neuroinflammation. However, it has inherent limitations, such as short half-life and limited availability. The purpose of this study was to demonstrate the efficiency of new generation TSPO radiotracer, 18F-DPA-714, in detecting and monitoring neuroinflammation of chronic HE. This study was divided into two parts. The first part compared 18F-DPA-714 and 11C-PK11195 radiotracers in ten HE induced rats [bile duct ligation (BDL) and fed hyperammonemic diet (HD)] and 6 control rats. The animal subjects underwent dynamic positron emission tomography (PET) during 2-day intervals. The 11C-PK11195 PET study showed no differences in whole brain average percent injected dose per gram (%ID/g) values at all time points (all P>0.05), while the 18F-DPA-714 PET study showed higher whole brain average %ID/g values in HE rats compared to control group rats at 900 s to 3300 s after injecting radiotracer (all P<0.05). The second part of the study evaluated the effectiveness of ibuprofen (IBU) treatment to chronic HE. Forty rats were classified into six groups, including Sham+normal saline (NS), Sham+IBU, BDL+NS, BDL+HD+NS, BDL+IBU, and BDL+HD+IBU groups. 18F-DPA-714 PET was used to image neuroinflammation. Whole and regional brain average %ID/g values, neurological features, inflammatory factors and activated microglia showed better in the IBU groups than in the NS groups (all P<0.05) and no difference was seen in the Sham groups compared to IBU groups (all P>0.05). In conclusion, this study demonstrated that 18F-DPA-714 is an ideal TPSO radiotracer for imaging neuroinflammation and monitoring anti-neuroinflammation treatment efficacy of chronic HE.

PET and MR imaging of neuroinflammation in hepatic encephalopathy

Neurological or psychiatric abnormalities associated with hepatic encephalopathy (HE) range from subclinical findings to coma. HE is commonly accompanied with the accumulation of toxic substances in bloodstream. The toxicity effect of hyperammonemia on astrocyte, such as the alteration in neurotransmission, oxidative stress, astrocyte swelling, is considered as an important factor in the pathogenesis of HE. Besides, neuroinflammation has captured more attention in the process of HE, but the mechanism of neuroinflammation leading to HE remains unclear. Molecular imaging techniques such as positron emission tomography (PET) and magnetic resonance imaging (MRI) targeting activated microglia and/ or other mediators appear to be promising noninvasive approaches to assess HE. This review focuses on novel imaging and therapy strategies of neuroinflammation in HE.