CT Lung Perfusion Research Articles

Enhancing diagnostic precision for acute chest syndrome in sickle cell disease: insights from dual-energy CT lung perfusion mapping.

Acute chest syndrome (ACS) is secondary to occlusion of the pulmonary vasculature and a potentially life-threatening complication of sickle cell disease (SCD). Dual-energy CT (DECT) iodine perfusion map reconstructions can provide a method to visualize and quantify the extent of pulmonary microthrombi. A total of 102 patients with sickle cell disease who underwent DECT CTPA with perfusion were retrospectively identified. The presence or absence of airspace opacities, segmental perfusion defects, and acute or chronic pulmonary emboli was noted. The number of segmental perfusion defects between patients with and without acute chest syndrome was compared. Sub-analyses were performed to investigate robustness. Of the 102 patients, 68 were clinically determined to not have ACS and 34 were determined to have ACS by clinical criteria. Of the patients with ACS, 82.4% were found to have perfusion defects with a median of 2 perfusion defects per patient. The presence of any or new perfusion defects was significantly associated with the diagnosis of ACS (P = 0.005 and < 0.001, respectively). Excluding patients with pulmonary embolism, 79% of patients with ACS had old or new perfusion defects, and the specificity for new perfusion defects was 87%, higher than consolidation/ground glass opacities (80%). DECT iodine map has the capability to depict microthrombi as perfusion defects. The presence of segmental perfusion defects on dual-energy CT maps was found to be associated with ACS with potential for improved specificity and reclassification.

Pulmonary circulation abnormalities in post-acute COVID-19 syndrome: dual-energy CT angiographic findings in 79 patients.

To evaluate the frequency and pattern of pulmonary vascular abnormalities in the year following COVID-19. The study population included 79 patients remaining symptomatic more than 6months after hospitalization for SARS-CoV-2 pneumonia who had been evaluated with dual-energy CT angiography. Morphologic images showed CT features of (a) acute (2/79; 2.5%) and focal chronic (4/79; 5%) PE; and (b) residual post COVID-19 lung infiltration (67/79; 85%). Lung perfusion was abnormal in 69 patients (87.4%). Perfusion abnormalities included (a) perfusion defects of 3 types: patchy defects (n = 60; 76%); areas of non-systematized hypoperfusion (n = 27; 34.2%); and/or PE-type defects (n = 14; 17.7%) seen with (2/14) and without (12/14) endoluminal filling defects; and (b) areas of increased perfusion in 59 patients (74.9%), superimposed on ground-glass opacities (58/59) and vascular tree-in-bud (5/59). PFTs were available in 10 patients with normal perfusion and in 55 patients with abnormal perfusion. The mean values of functional variables did not differ between the two subgroups with a trend toward lower DLCO in patients with abnormal perfusion (74.8 ± 16.7% vs 85.0 ± 8.1). Delayed follow-up showed CT features of acute and chronic PE but also two types of perfusion abnormalities suggestive of persistent hypercoagulability as well as unresolved/sequelae of microangiopathy. Despite dramatic resolution of lung abnormalities seen during the acute phase of the disease, acute pulmonary embolism and alterations at the level of lung microcirculation can be identified in patients remaining symptomatic in the year following COVID-19. • This study demonstrates newly developed proximal acute PE/thrombosis in the year following SARS-CoV-2 pneumonia. • Dual-energy CT lung perfusion identified perfusion defects and areas of increased iodine uptake abnormalities, suggestive of unresolved damage to lung microcirculation. • This study suggests a complementarity between HRCT and spectral imaging for proper understanding of post COVID-19 lung sequelae.

Dual-energy CT lung perfusion in systemic sclerosis: preliminary experience in 101 patients.

To investigate lung perfusion in systemic sclerosis (SSc). The study population included 101 patients who underwent dual-energy CT (DECT) in the follow-up of SSc with pulmonary function tests obtained within 2 months. Fifteen patients had right heart catheterization-proven PH. Thirty-seven patients had no SSc-related lung involvement (Group A), 56 patients had SSc-related interstitial lung disease (Group B) of variable extent (Group B mild: ≤ 10% of lung parenchyma involved: n = 17; Group B moderate: between 11 and 50%: n = 31; Group B severe: > 50%: n = 8), and 8 patients had PVOD/PCH (Group C). Lung perfusion was abnormal in 8 patients in Group A (21.6%), 14 patients in Group B (25%), and 7 patients in Group C (87.5%). In Group A and Group B mild (n = 54), (a) patients with abnormal lung perfusion (n = 14; 26%) had a higher proportion of NYHA III/IV scores of dyspnea (7 [50%] vs 7 [17.5%]; p = 0.031) and a shorter mean walking distance at the 6MWT (397.0 [291.0; 466.0] vs 495.0 [381.0; 549.0]; p = 0.042) but no evidence of difference in the DLCO% predicted (61.0 [53.0; 67.0] vs 68.0 [61.0; 78.0]; p = 0.055) when compared to patients with normal lung perfusion (n = 40; 74%); (b) a negative correlation was found between the iodine concentration in both lungs and the DLCO% predicted but it did not reach statistical significance (r = -0.27; p = 0.059) and no correlation was found with the PAPs (r = 0.16; p = 0.29) and walking distance during the 6MWT (r = -0.029; p = 0.84). DECT lung perfusion provides complementary information to standard HRCT scans, depicting perfusion changes in SSc patients with normal or minimally infiltrated lung parenchyma. • In a retrospective observational study of 101 consecutive patients with SSc, dual-energy CT pulmonary angiography was obtained to evaluate lung perfusion. • Lung perfusion was abnormal in 14 out of 54 patients (26%) with no or mild SSc-related lung infiltration. • Patients with abnormal perfusion and no or mild SSc-related lung infiltration had more severe scores of dyspnea and shorter walking distance than patients with similar lung findings and normal perfusion, suggesting the presence of small vessel vasculopathy.

Dual-energy CT lung perfusion characteristics in pulmonary arterial hypertension (PAH) and pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis (PVOD/PCH): preliminary experience in 63 patients.

In the stratification of potential causes of PH, current guidelines recommend performing V/Q lung scintigraphy to screen for CTEPH. The recognition of CTEPH is based on the identification of lung segments or sub-segments without perfusion but preserved ventilation. The presence of mismatched perfusion defects has also been described in a small proportion of idiopathic pulmonary arterial hypertension (PAH) and pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis (PVOD/PCH). Dual-energy CT lung perfusion changes have not been specifically investigated in these two entities. To compare dual-energy CT (DECT) perfusion characteristics in PAH and PVOD/PCH, with specific interest in PE-type perfusion defects. Sixty-three patients with idiopathic or heritable PAH (group A; n = 51) and PVOD/PCH (group B; n = 12) were investigated with DECT angiography with reconstruction of morphologic and perfusion images. The number of patients with abnormal perfusion did not differ between group A (35/51; 68.6%) and group B (6/12; 50%) (p = 0.31) nor did the mean number of segments with abnormal perfusion per patient (group A: 17.9 ± 4.9; group B: 18.3 ± 4.1; p = 0.91). The most frequent finding was the presence of patchy defects in group A (15/35; 42.9%) and a variable association of perfusion abnormalities in group B (4/6; 66.7%). The median percentage of segments with PE-type defects per patient was significantly higher in group B than in group A (p = 0.041). Two types of PE-type defects were depicted in 8 patients (group A: 5/51; 9.8%; group B: 3/12; 25%), superimposed on PH-related lung abnormalities (7/8) or normal lung (1/8). The iodine concentration was significantly lower in patients with abnormal perfusion (p < 0.001) but did not differ between groups. Perfusion abnormalities did not differ between the two groups at the exception of a higher median percentage of segments with PE-type defects in patients with PVOD/PCH. • Patchy perfusion defect was the most frequent pattern in PAH. • A variable association of perfusion abnormalities was seen in PVOD/PCH. • Lobular and PE-type perfusion defects larger than a sub-segment were depicted in both PAH and PVOD/PCH patients.

Comparison of test bolus and bolus tracking techniques for dual-energy CT lung perfusion scan

Objective To compare the test bolus technique with the bolus tracking technique for dual-energy CT pulmonary angiography in patients suspected of pulmonary embolism (PE). Methods A total of 60 patients were randomized into 2 groups:bolus tracking technique group (group B,n=30) and test bolus technique group (group T,n=30).A standard dual-energy CT pulmonary angiography (CTPA) was performed after injection of 60 ml contrast medium followed by 35ml saline chaser at a speed of 4 ml/s.Attenuation profiles of different vascular segments (the subclavian vein,superior vena cava,left atrium,pulmonary trunk,S1 and S10 pulmonary artery) and enhancement value of lung parenchyma were measured to evaluate the timing techniques.The overall image quality Key words: Pulmonary embolism; Tomography,X-ray computed; Angiography; Contrast media

Dual Energy CT lung perfusion imaging—Correlation with SPECT/CT

Aims were (1) to determine the diagnostic accuracy of Dual Energy CT (DECT) in the detection of perfusion defects and (2) to evaluate the potential of DECT to improve the sensitivity for PE. 15 patients underwent Dual Energy pulmonary CT angiography (DE CTPA) and a combination of lung perfusion SPECT/CT and ventilation scintigraphy. CTPA and DE iodine distribution maps as well as perfusion SPECT/CT and inhalation scintigrams were reviewed for pulmonary embolism (PE) diagnosis. DECT and SPECT perfusion images were assessed regarding localization and extent of perfusion defects. Diagnostic accuracy of DE iodine (perfusion) maps was determined with reference to SPECT/CT. Diagnostic accuracies for PE detection of DECT and of SPECT/CT with ventilation scintigraphy were calculated with reference to the consensus reading of all modalities. DE CTPA had a sensitivity/specificity of 100%/100% for acute PE, while the combination of SPECT/CT and ventilation scintigraphy had a sensitivity/specificity of 85.7%/87.5%. For perfusion defects, DECT iodine maps had a sensitivity/specificity of 76.7% and 98.2%. DECT is able to identify pulmonary perfusion defects with good accuracy. This technique may potentially enhance the diagnostic accuracy in the assessment of PE.

Comparative study of dual-energy CT pulmonary angiography and lung perfusion with pulmonary perfusion scintigraphy in the diagnosis of pulmonary embolism

Objective To investigate the diagnostic value of dual-energy CT pulmonary angiography (DE-CTPA) and dual-energy CT lung perfusion (DE-CTLP) in the assessment of pulmonary embolism comparing with pulmonary ventilation-perfusion scintigraphy. Methods Fifty patients suspected of PE (26 males, 24 females) underwent both DE-CTPA, DE-CTLP and pulmonary ventilation-perfusion scintigraphy. The results were compared and the correlation between the intravascular clots in DE-CTPA and the perfusion defects in DE-CTLP was analyzed. The sensitivity, specificity and accuracy of DE-CTLP for PE were assessed according to scintigraphic results which was considered as a gold standard. Result ( 1 ) Of 50 cases,920 segments in 46 cases were diagnostable, 4 cases were not included because of the poor image quality. lntravascular clots were found in 262 segments on DE-CTPA and perfusion defects in 266 segments were identified on DE-CTLP, while 268 segments were positive on scintigraphy. (2) The perfusion defects on DE-CTLP were correlated well with the clots on CTPA ( r = 0. 883, P < 0. 01 ). The Dual energy CT Lung perfusion imaging had a good consistence with scintigraphy (Kappa = 0. 940, P <0. 01 ). The sensitivity, specificity, positive and negative predictive value were 96. 2% (279/290), 98.0%(641/654), 95. 5% (279/292) and 98. 3% (641/652), respectively. (3)The radiation dose of DE-CTPA and CE-CTLP scan was(4. 37 ± 0. 47) mSv by using CareDose 4D technique. Conclusion DE-CTPA and CE-CTLP can provide pulmonary vascular morphology and parenchyma perfusion information which are useful and valuable for the diagnosis of PE. Key words: Pulmonary embolism; Tomography,X-ray computed; Perfusion; Radionuclide imaging

Regional differences in lung radiosensitivity after radiotherapy for non–small-cell lung cancer

Purpose To study regional differences in lung radiosensitivity by evaluating the incidence of radiation pneumonitis (RP) in relation to regional dose distributions. Methods and materials Registered chest CT and single photon emission CT lung perfusion scans were obtained in 106 patients before curative or radical radiotherapy for non–small-cell lung cancer. The mean lung dose (MLD) was calculated. The single photon-emission CT perfusion data were used to weigh the MLD with perfusion, resulting in the mean perfusion-weighted lung dose. In addition, the lungs were geometrically divided into different subvolumes. The mean regional dose (MRD) for each region was calculated and weighted with the perfusion of each region to obtain the mean perfusion-weighted regional dose. RP was defined as respiratory symptoms requiring steroids. The incidence of RP for patients with tumors in a specific subvolume was calculated. The normal tissue complication probability (NTCP) parameter values for the TD 50, and an offset NTCP parameter for tumor location were fitted for both lungs and for each lung subvolume to the observed data using maximum likelihood analysis. Results The incidence of RP correlated significantly with the MLD and MRD of the posterior, caudal, ipsilateral, central, and peripheral lung subvolumes ( p between 0.05 and 0.002); no correlation was seen for the anterior, cranial, and contralateral regions Similarly, a statistically significant correlation was observed between the incidence of RP and the perfusion-weighted MLD and perfusion-weighted MRD for all regions, except the anterior lung region. For this region, the dose–effect relation improved remarkably after weighting the local dose with the local perfusion. A statistically significant difference ( p = 0.01) in the incidence of RP was found between patients with cranial and caudal tumors (11% and 40%, respectively). Therefore, a dose-independent offset NTCP parameter for caudal tumors was included in the NTCP model, improving most correlations significantly, confirming that patients with caudal tumors have a greater probability of developing RP. Conclusion The incidence of RP correlated significantly with the MLD and MRD of most lung regions, except for the anterior, cranial, and contralateral regions. Weighting the local dose with the local perfusion improved the dose–effect relation for the anterior lung region. Irradiation of caudally located lung tumors resulted in a greater risk of RP than irradiation of tumors located in other parts of the lungs.