The diagnostic yield for computed tomography pulmonary angiography in patients with anticoagulation

BACKGROUND:Patients who present to the emergency department(ED)for suspected pulmonary embolism(PE)are often on active oral anticoagulation(AC).However,the diagnostic yield of computed tomography pulmonary angiography(CTPA)in screening for PE in patients who present on AC has not been well characterized.We aim to investigate the diagnostic yield of CTPA in diagnosing PE depending on AC status.METHODS:We reviewed and analyzed the electronic medical records of patients who underwent CTPA for PE at a university hospital ED from June 1,2019,to March 25,2022.Primary outcome was the incidence of PE on CTPA depending on baseline AC status and indication for AC.RESULTS:Of 2,846 patients,242 were on AC for a history of venous thromboembolism(VTE),210 were on AC for other indications,and 2,394 were not on AC.The incidence of PE on CTPA was significantly lower in patients on AC for other indications(5.7%)when compared to patients on AC for prior VTE(24.3%)and patients not on AC at presentation(9.8%)(P<0.001).In multivariable analysis among the whole cohort,AC was associated with a positive CTPA(odds ratio[OR]0.26,95%confidence interval[CI]:0.15-0.45,P<0.001).CONCLUSION:The incidence of PE among patients undergoing CTPA in the ED is lower in patients previously on AC for indications other than VTE when compared to those not on AC or those on AC for history of VTE.AC status and indication for AC may affect pre-test probability of a positive CTPA,and AC status therefore warrants consideration as part of future diagnostic algorithms among patients with suspected PE.

Computed tomography pulmonary angiography using a 20% reduction in contrast medium dose delivered in a multiphasic injection

AIM To evaluate the feasibility of reducing the dose of iodinated contrast agent in computed tomography pulmonary angiography(CTPA). METHODS One hundred and twenty-seven patients clinically suspected of having pulmonary embolism underwent spiral CTPA, out of whom fifty-seven received 75 mL and the remaining seventy a lower dose of 60 mL of contrast agent. Both doses were administered in a multiphasic injection. A minimum opacification threshold of 250 Hounsfield units(HU) in the main pulmonary artery is used for assessing the technical adequacy of the scans. RESULTS Mean opacification was found to be positively correlated to patient age(Pearson's correlation 0.4255, P < 0.0001) and independent of gender(male:female, 425.6 vs 450.4,P = 0.34). When age is accounted for, the study and control groups did not differ significantly in their mean opacification in the main(436.8 vs 437.9, P = 0.48),left(416.6 vs 419.8, P = 0.45) or the right pulmonary arteries(417.3 vs 423.5, P = 0.40). The number of sub-optimally opacified scans(the mean opacification in the main pulmonary artery < 250 HU) did not differ significantly between the study and control groups(7 vs 10).CONCLUSION A lower dose of iodine contrast at 60 mL can be feasibly used in CTPA without resulting in a higher number of sub-optimally opacified scans.

Gadolinium Enhances Dual-energy Computed Tomography Scan of Pulmonary Artery

Objective To evaluate the feasibility of using gadopentetate dimeglumine(Gd-DTPA)for dual-energy computed tomography pulmonary angiography(CTPA).Methods Sixty-six patients were randomly divided into three groups and underwent CTPA.Group A had a turbo flash scan using an iohexol injection,Group B had a turbo flash scan using Gd-DTPA,and Group C had a dual-energy scan using Gd-DTPA.The original images of Group C were linearly blended with a blending factor of 0.5 or reconstructed at 40,50,60,70,80,90,100,and 110 keV,respectively.The groups were compared in terms of pulmonary artery CT value,image quality,and radiation dose.Results The pulmonary artery CT values were significantly higher in Group C40keV than in Groups B and C,but lower than in Group A.There was no significant difference in the image noise of Groups C40keV,B,and C.Moreover,Group A had the largest beam hardening artifacts of the superior vena cava(SVC),followed by Groups B and C.Group C40keV showed better vascular branching than the other three groups,among which Group B was superior to Group A.The subjective score of the image quality of Groups A,B,and C showed no significant difference,but the score was significantly higher in Group C40keV than in Groups A and B.The radiation dose was significantly lower in Group B than in Groups A and C.Conclusion Gd-CTPA is recommended to patients who are unsuitable for receiving an iodine-based CTPA.Furthermore,a turbo flash scan could surpass a dual-energy scan without consideration for virtual monoenergetic imaging.

Role of pulmonary perfusion magnetic resonance imaging for the diagnosis of pulmonary hypertension:A review

Among five types of pulmonary hypertension,chronic thromboembolic pulmonary hypertension(CTEPH)is the only curable form,but prompt and accurate diagnosis can be challenging.Computed tomography and nuclear medicine-based techniques are standard imaging modalities to non-invasively diagnose CTEPH,however these are limited by radiation exposure,subjective qualitative bias,and lack of cardiac functional assessment.This review aims to assess the methodology,diagnostic accuracy of pulmonary perfusion imaging in the current literature and discuss its advantages,limitations and future research scope.

Contrast-enhanced CT of Pulmonary Embolism: Report of 20 cases

Objectives To study the characteristic of pulmonary embolism （PE） in contrast-enhanced CT. Methods The radiological features were described in 20 patients with lobar and proximal PE diagnosed with a Toshiba Xpress/SX CT scanner after contrast material was administrated. Results There were 7 cases of pulmonary embolism （ PE ） secondary to lower limb deep vein thrombosis （DVT）, of which 2 cases were related to sauna bath. We grouped the cases according to their extensiveness of embolism： mild, moderate, severe, or complete embolism. Mild embolism： the emboli occupied less than 30%, of the inner diameter of pulmonary artery （PA）. Median embolism： the emboli occupied 30 -50% of the PA diameter. Severe embolism： the emboli occupied over half of the PA （50%）, but there were contrast flow. Completed embolism： there was no contrast found around the emboli. The direct sign of PE was a filling defect or no opacification in the affected branch of pulmonary artery （PA）. There were 9 other secondary signs： （1）widen PA, （2）enlarged right ventricle and the right atrium, （3）increased translucency of the lung and decreased bronchovascular shadows, （4）shrunken pulmonary veins liked dried rattan, （5）decreased left atrium and the left ventricle size, （6）shifting of interventricular septum to the left and posterior direction, （7）The lateral lung parenchyma demonstrated in a triangular shape, （8）pleural effusion and （9）pericardiacle effusion. Conclusions The diagnosis of PE was revealed by 10 radiological signs by contrast-enhanced CT.With full understanding of the pathophysiological basis of these 10 signs ： correct diagnosis of pulmonary embolism can be made. PE is commonly caused by lower limb. And sauna bath is one of the main predisposing causes.

Correlation of D-dimer level with the radiological severity indexes of pulmonary embolism on computed tomography pulmonary angiography

Background It is known that the main role of D-dimer has been as an exclusionary test in patients with suspected venous thromboembolism.However,the D-dimer is increasingly beginning to find clinical utility as a marker in the evaluation of the extent of the embolic disease.The aim of the study was to determine whether D-dimer levels predict the radiological markers of pulmonary embolism （PE） severity using Mastora score.Methods This prospective study involved 69 patients with acute PE proved by computed tomography pulmonary angiography （CTPA）.The D-dimer level was noted.A pulmonary artery obstruction index （PAOI; Mastora score） ≥21.3% indicated severe obstruction of PE.A right ventricle/left ventricle （RV/LV） ratio 〉0.9 indicated RV dysfunction.Results The median D-dimer level and PAOI were 765 μg/L （95% C/：750-1 205 μg/L） and 16.77% （95% CI：16.32%-23.06%）,respectively.The D-dimer level was positively correlated with PAOI （r=0.417,P 〈0.000 1）.PAOI ≥21.3% was associated with high D-dimer levels （median,993 μg/L （95% C/：856-1 841 μg/L）,Z=-2.991,P=0.003）.The D-dimer level was correlated with the RV/LV ratio （r=0.272,P=0.024）.RV/LV ratios 〉0.9 were associated with high D-dimer levels （median,880 μg/L （95% CI：764-1 360 μg/L）,Z=-2.070,P=0.038）.PAOI was positively correlated with the RV/LV ratio （r =0.390,P=0.001）.After three months,both the PAOI and D-dimer levels decreased （Z=-7.009,P 〈0.000 1; Z=-6.976,P〈0.000 1,respectively）.Conclusion D-dimer levels are positively correlated with PE burden and right ventricle dysfunction on CTPA,and can help monitor the therapeutic response.

Multimodality imaging in COVID-19 patients:A key role from diagnosis to prognosis

The integrated clinical,laboratory and ultrasound approach is essential for the diagnosis,evaluation and monitoring of the patient's therapy in coronavirus disease 2019 pneumonia.The ideal imaging approach in this context is not yet well defined.Chest X-ray is characterized by low sensitivity in identifying earlier lung changes.The"bedside"pulmonary ultrasound has an undeniable series of advantages in the patient at high infectious risk and can provide incremental data in the respiratory intensive care for the serial control of the individual patient as well as for the home delivery of the stabilized subjects.Pulmonary computed tomography shows high sensitivity but should not be routinely performed in all patients,because in the first 48 h it can be absolutely negative and in the late phase the imaging findings may not change the therapeutic approach.Echocardiography should be limited to patients with hemodynamic instability to assess ventricular function and pulmonary pressures.

Incidence of Pleural Effusion in Patients with Pulmonary Embolism

Background： No data on the incidence ofpleural effusion （PE） in Chinese patients with pulmonary embolism are available to date. The aim of the current study was to investigate the frequency of PE in a Chinese population of patients with pulmonary embolism. Methods： This was a retrospective observational single-center study. All data of computed tomography pulmonary angiography （CTPA） performed over 6-year period on adult patients with clinically suspected pulmonary embolism were analyzed. Results： From January 2008 until December 2013, PE was identified in 423 of 3141 patients （13.5%） with clinically suspected pulmonary embolism who underwent CTPA, The incidence of PE in patients with pulmonary embolism （19.9%） was significantly higher than in those without embolism （9.4%） （P 〈 0.001 ）. Majority of PEs in pulmonary embolism patients were small to moderate and were unilateral. The locations of emboli and the numbers of arteries involved, CT pulmonary obstruction index, and parenchymal abnormalities at CT were not associated with the development of PE, Conclusions： PEs are present in about one fifth of a Chinese population of patients with pulmonary embolism, which are usually small, unilateral, and unsuitable for diagnostic thoracentesis.

Primary pulmonary artery chondrosarcoma： the use of different imaging modalities

Fewer than 300 patients with primary pulmonary artery sarcoma have been reported since 1923,when it was first described by Mandelstamm.1 The diagnosis of pulmonary artery sarcoma is difficult,and misdiagnosis as chronic pulmonary embolism often occurs.Herein,we reported a case of primary pulmonary artery chondrosarcoma.So far as we know,this patient served as the first case ever reported to receive computed tomography pulmonary angiography （CTPA）,gadolinium enhanced magnetic resonance imaging （MRI）,and positron emission tomography/computed tomography （PET/CT） before surgery.By these means,the utility of different imaging modalities for pulmonary artery sarcoma was well demonstrated.Keywords：primary pulmonary artery chondrosarcoma; computed tomography pulmonary angiography;magnetic resonance imaging; positron emission tomography