Chest CT Usage in Covid-19 Pneumonia: Multicenter Study on Radiation Doses and Diagnostic Quality in Brazil

We assessed variations in chest CT usage, radiation dose and image quality in COVID-19 pneumonia. Our study included all chest CT exams performed in 533 patients from 6 healthcare sites from Brazil. We recorded patients’ age, gender and body weight and the information number of CT exams per patient, scan parameters and radiation doses (volume CT dose index—CTDIvol and dose length product—DLP). Six radiologists assessed all chest CT exams for the type of pulmonary findings and classified CT appearance of COVID-19 pneumonia as typical, indeterminate, atypical or negative. In addition, each CT was assessed for diagnostic quality (optimal or suboptimal) and presence of artefacts. Artefacts were frequent (367/841), often related to respiratory motion (344/367 chest CT exams with artefacts) and resulted in suboptimal evaluation in mid-to-lower lungs (176/344) or the entire lung (31/344). There were substantial differences in CT usage, patient weight, CTDIvol and DLP across the participating sites.

Whole-Brain Volume CT Angiography can Effectively Detect Early Ischemic Cerebrovascular Diseases

Objective: To investigate the role of whole-brain volume computed tomography (CT) perfusion in assessing early ischemic cerebrovascular diseases. Materials and Methods: Seventy-two patients with early ischemic cerebrovascular diseases who had undergone routine CT scan and 320-row volume CT whole-brain perfusion imaging within 8 h after admission were retrospectively enrolled in this one-center case-sectional study. The perfusion parameters of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and dynamic CT angiogram (4D-CTA) were obtained and analyzed. Results: Among 72 patients, 29 cases with 37 cerebral ischemic lesions were found in plain CT scan, whereas 51 cases with 76 lesions were found in whole-brain CT perfusion, with 30.6% more patients being detected. The CBF value was significantly lower in the abnormal than normal corresponding perfusion area in the healthy hemisphere (P<0.05), while the MTT and TTP values were significantly higher in the abnormal than the normal corresponding area (P<0.05). 4D-CTA image suggested that 59 cases had different degrees of stenosis or occlusion, including 11 mild, 18 moderate, 21 severe, and 9 occlusive cases. Four-D-CTA imaging could detect significantly (P<0.05) more patients with abnormal perfusion in severe cerebral vascular stenosis or occlusion than those with no, mild or moderate stenosis (93.33% vs. 16.67%) (P<0.05). The stenosis of intracranial and carotid arteries was positively correlated with MTT and TTP values (P<0.05). Conclusion: Whole-brain volume CT angiography can comprehensively display early cerebral ischemic lesions, cerebral blood perfusion status, and cerebral vascular stenosis, providing valuable information for early detection of ischemic cerebral diseases and appropriate treatment planning.

Application and Value of Dynamic Volume CT Multiparameter Imaging in the Diagnosis of Traumatic High-Flow Penile Abnormal Erection

Objective. To explore the clinical application of dynamic volume CT multiparameter imaging in the observation of penile hemodynamics in patients with abnormal vascular erections. Methods. 90 patients with suspected vascular abnormal erections treated in our hospital from January 2016 to January 2020 were included in the study, and 40 patients with psychologically abnormal erections were selected for the control. The corpus cavernosum injection vasoactive drug test (ICI) and dynamic volume CT and Doppler ultrasound were used to test the hemodynamics of the corpus cavernosum of all selected patients and to analyze the changes of penile length, circumference, systolic peak flow rate, diastolic peak flow rate, and blood flow resistance index in different types of penile erection disorder patients before and after ICI test. Results. Among the 90 patients with suspected vascular abnormal erection, 34 patients had arterial abnormal erection, 25 patients had venous abnormal erection, and 31 patients had mixed vascular abnormal erection. In patients with arterial abnormal erection and mixed vascular abnormal erection, penile cavernous body diameter, PSV, and abnormal erection V are smaller than those in patients with venous abnormal erection and psychological abnormal erection, while arterial abnormal erection and psychological abnormal erection are obviously higher in RI than venous abnormal erection and mixed vascular abnormal erection, and the difference is statistically significant ( P < 0.05 ). Before the ICI test, there was no significant difference in the penis circumference and length between the four groups of patients with arterial abnormal erection, venous abnormal erection, mixed vascular abnormal erection, and psychological abnormal erection ( P > 0.05 ); after the ICI test, patients with arterial abnormal erections had significantly shorter penis perimeter and penis length than those with venous abnormal erections, mixed vascular abnormal erections, and psychological abnormal erections ( P < 0.05 ). Conclusion. Dynamic volume CT can clearly reflect the penile hemodynamic state of patients with vascular abnormal erections, provide a powerful diagnostic basis for accurately and effectively determining the classification of vascular abnormal erections, and be worthy of popularization and clinical use.

Quantitative evaluation of upper urinary tract pump function in pigs with acute unilateral lower ureteral obstruction by 640-slice dynamic volume CT

Background It is a challenging problem to differentiate obstructive hydronephrosis from noninvasive evaluation of renal pelvis and ureteral motility in patients. The purpose of this study was to explore the value of 640-slice dynamic volume CT (DVCT) in the quantitative measurement of upper urinary tract (UUT) pump function after acute unilateral lower ureteral obstruction in pigs. Methods In this study, a perfusion pig model was constructed by constant pressure perfusion testing of the renal pelvis and left nephrostomy. The perfusion and pressure measuring devices were connected to create a state of no obstruction and acute obstruction of the lower part of the left ureter. After successful modelling, continuous dynamic volume scanning of the bilateral renal excretion phase was performed with 640-slice DVCT, and pump functions of the renal pelvis and part of the upper ureter were calculated and analysed. No obstruction or acute obstruction of the lower part of the left ureter was observed. Pump functions of the renal pelvis and part of the upper ureter were determined. Results The results showed that after LUUT fistulostomy, the time difference between the average UUT volume and positive volume value increased gradually, and the calculated flow velocity decreased, which was significantly different from that of the RUUT. The volume difference of the LUUT increased significantly in mild obstruction. In the bilateral control, the volume change rate of the LUUT increased with mild obstruction and decreased with severe obstruction, and there was a significant difference between the left and right sides. Conclusion The continuous dynamic volume scan and measurement of 640-slice DVCT can obtain five pump function datasets of UUT in pigs with acute lower ureteral obstruction.

Noninvasive Assessment of Foot Perfusion in a Rabbit Model of Atherosclerosis Using Dynamic Volume Perfusion CT with an Upslope Method

Objectives: To evaluate the feasibility of foot dynamic volume CT with the upslope method and to demonstrate macrovascular reactivity and microvascular perfusion during cuff-induced reactive hyperemia state in a rabbit model of atherosclerosis.Materials and Methods: 30 New Zealand male rabbits were divided into 2 groups: dietary hypercholesterolemia induced atherosclerosis (n=10) and normal diet control (n=20). To measure for macrovascular reactivity, perfusion parameters of the left posterior tibial artery was measured at baseline and at reactive hyperemia state. For the evaluation of microvascular perfusion, color-coded perfusion map of the plantar dermis was generated for perfusion CT scan by an in-house dedicated analysis software based on upslope method. Dermal perfusion values were measured and analyzed before and after cuff-induced reactive hyperemia.Results: Foot dynamic volume CT with the upslope method demonstrated significant impairment of both macrovascular reactivity and microvascular perfusion in atherosclerotic rabbits during cuff-induced reactive hyperemia (CRH) state. Arterial time-to-peak of cholesterol-fed rabbits failed to show acceleration while healthy rabbits showed significant decrease in time. Microvascular perfusion calculated by perfusion value (P<0.01) and perfusion ratio (P=.014) showed decreased microvascular perfusion in cholesterol fed rabbits compared to healthy rabbits during CRH state. Post-CT pathologic examination revealed decreased endothelial cell density in cholesterol-fed rabbits (P<0.001).Conclusions: Foot perfusion CT using upslope method provides perfusion parameters for large arteries and a perfusion map of the foot during cuff-induced reactive hyperemia in rabbit models of atherosclerosis. It may be a useful tool for the quantitative and functional evaluation of atherosclerotic peripheral arterial disease.

CT-derived 3D-diaphragm motion in emphysema and IPF compared to normal subjects

Image registration-based local displacement analysis enables evaluation of respiratory motion between two computed tomography-captured lung volumes. The objective of this study was to compare diaphragm movement among emphysema, idiopathic pulmonary fibrosis (IPF) and normal subjects. 29 normal, 50 emphysema, and 51 IPF subjects were included. A mass preserving image registration technique was used to compute displacement vectors of local lung regions at an acinar scale. Movement of the diaphragm was assumed to be equivalent to movement of the basal lung within 5 mm from the diaphragm. Magnitudes and directions of displacement vectors were compared between the groups. Three-dimensional (3D) and apico-basal displacements were smaller in emphysema than normal subjects (P = 0.003, P = 0.002). Low lung attenuation area on expiration scan showed significant correlations with decreased 3D and apico-basal displacements (r = − 0.546, P < 0.0001; r = − 0.521, P < 0.0001) in emphysema patients. Dorsal–ventral displacement was smaller in IPF than normal subjects (P < 0.0001). The standard deviation of the displacement angle was greater in both emphysema and IPF patients than normal subjects (P < 0.0001). In conclusion, apico-basal movement of the diaphragm is reduced in emphysema while dorsal–ventral movement is reduced in IPF. Image registration technique to multi-volume CT scans provides insight into the pathophysiology of limited diaphragmatic motion in emphysema and IPF.

Quantitative Evaluation of Upper Urinary Tract Pump Function in Pigs With Acute Unilateral Lower Ureteral Obstruction by 640-slice Dynamic Volume CT

Background: It is a challenging problem to differentiate obstructive hydronephrosis from non-invasive evaluation of renal pelvis and ureteral motility in patients. The purpose of this study was to explore the value of 640-slice dynamic volume CT (DVCT) in quantitative measurement of upper urinary tract (UUT) pump function after acute unilateral lower ureteral obstruction in pigs. Methods: In this study, perfusion pig model was made by constant pressure perfusion test of renal pelvis and left nephrostomy. The perfusion and pressure measuring devices were connected to create the state of no obstruction, acute obstruction of the lower part of the left ureter. After successful modeling, continuous dynamic volume scanning of bilateral renal excretion phase was performed with 640-slice DVCT, and pump functions of the renal pelvis and part of the upper ureter were calculated and analyzed. No obstruction, acute obstruction of the lower part of the left ureter. Pump functions of the renal pelvis and part of the upper ureter. Results: Results showed after LUUT fistulostomy, the time difference between the average UUTs volume and positive volume value increased gradually, and the calculated flow velocity decreased, which was significantly different from that of the RUUT. The volume difference of the LUUT increased significantly in mild obstruction. In the bilateral control, the volume change rate of the LUUT increased in mild obstruction and decreased in severe obstruction, and there was significant difference between the left and the right side. Conclusion: The continuous dynamic volume scan and measurement of 640-slice DVCT can obtain five pump function data of UUT in pigs with acute lower ureteral obstruction.