Assessing Pulmonary Perfusion in Emphysema

Abstract

Objectives: The objective of this study was to determine whether automated quantification of lung perfused blood volume (PBV) in dual-energy computed tomographic pulmonary angiography (DE-CTPA) can be used to assess the severity and regional distribution of pulmonary hypoperfusion in emphysema. Materials and Methods: We retrospectively analyzed 40 consecutive patients (mean age, 67 [13] years) with pulmonary emphysema, who have no cardiopulmonary comorbidities, and a DE-CTPA negative for pulmonary embolism. Automated quantification of global and regional pulmonary PBV was performed using the syngo Dual Energy application (Siemens Healthcare). Similarly, the global and regional degrees of parenchymal hypodensity were assessed automatically as the percentage of voxels with a computed tomographic density less than j900 Hounsfield unit. Emphysema severity was rated visually, and pulmonary function tests were obtained by chart review, if available. Results: Global PBV generated by automated quantification of pulmonary PBV in the DE-CTPA data sets showed a moderately strong but highly significant negative correlation with residual volume in percentage of the predicted residual volume (r = j0.62; P = 0.002; n = 23) and a positive correlation with forced expiratory volume in 1 second in percentage of the predicted forced expiratory volume in 1 second (r = 0.67; P G 0.001; n = 23). Global PBV values strongly correlated with diffusing lung capacity for carbon monoxide (r = 0.80; P G 0.001; n = 15). Pulmonary PBV values decreased with visual emphysema severity (r = j0.46, P = 0.003, n = 40). Moderate negative correlations were found between global PBV values and parenchymal hypodensity both in a per-patient (r = j0.63; P G 0.001; n = 40) and per-region analyses (r = j0.62; P G 0.001; n = 40). Conclusions: Dual-energy computed tomographic pulmonary angiography allows simultaneous assessment of lung morphology, parenchymal density, and pulmonary PBV. In patients with pulmonary emphysema, automated quantification of pulmonary PBV in DE-CTPA can be used for a quick, reader-independent estimation of global and regional pulmonary perfusion, which correlates with several lung function parameters.Key Words: pulmonary emphysema, severity, distribution, pulmonary perfusion, dual-energy CT (Invest Radiol 2013;48: 79Y85) C hronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide.1,2 It is characterized by airflow limitation and lung inflammation resulting in a progressive deterioration in lung function. Emphysema is a common component of COPD, in which airway obstruction, inflammation, and aberrant activity of proteolytic enzymes cause irreversible destruction of the alveolar walls and enlargement of distal airspaces. Currently, screening for and early diagnosis of COPD and emphysema largely rely on spirometric lung function tests. 4 Spirometry, however, strongly depends on patients' cooperation and is unable to localize emphysematous changes within the lung. Because pulmonary e...

Assessment of regional pulmonary blood flow using 68Ga-DOTA PET

“…Such relevancy has allowed that the advances in imaging techniques for lung perfusion and perfusion distribution become an attractive tool for diagnosis and outcomes prediction and evaluation. For example, differences in perfusion patterns measured by dual CT [29, 30] are being proposed for diagnosis of PH and even to differentiate pulmonary arterial hypertension (PAH) from chronic thromboembolic pulmonary hypertension (CTEPH) [31]. Recently, Lau et al [32] showed using SPECT/CT that pulmonary pre-capillary hypertension showed a redistribution of flow changing the gravidity influence, which appears as a potential tool for disease severity evaluation.…”

Accuracy of dual-energy computed tomography for the measurement of iodine concentration using cardiac CT protocols: validation in a phantom model

“…In oncological imaging, the quantification of iodine has been used for the characterization of masses and for the assessment of therapy response [22]. The quantification of pulmonary iodine content has been shown to indicate the severity of pulmonary disorders including emphysema [23] and pulmonary embolism [24]. …”

Avaliação da perfusão sanguínea pulmonar lobar e global através da tomografia computadorizada de dupla energia em pacientes com suspeita de embolia pulmonar aguda: comparação de diferentes métodos quantitativos

“…No estudo de Sakamoto et al (19) , 72 pacientes com EP foram retrospectivamente divididos em 3 grupos de risco (baixo, intermediário e alto) e foi demonstrada diferença significativa no PBV global entre os grupos, enquanto o grupo de baixo risco não apresentou diferença significativa em relação aos pacientes com resultado negativo para EP. No estudo de Meinel et al (21) ,…”

“…A densidade média de iodo nos pulmões, em mg/ml, corresponde a quantidade total de iodo presente nos pulmões dividido pelo volume pulmonar. Para se obter uma estimativa relativa do volume sanguíneo perfundido por unidade de volume pulmonar, baseando-se no método aplicado em estudos anteriores (20,21) , a densidade média de iodo no parênquima pulmonar (mg/ml) foi normalizada pela densidade média de iodo no tronco da artéria pulmonar (mg/ml), sendo expressa em porcentagem (%) e definida pela equação: Os parâmetros PBVv e PBVm foram utilizados na análise regional dos lobos pulmonares e na análise global da perfusão sanguínea pulmonar.…”

“…Dentre os principais fatores, destaca-se a influência do grau de insuflação pulmonar. Nos estudos prévios de quantificação global do volume sanguíneo perfundido pulmonar (perfused blood volume, PBV) pela TCDE, foi utilizado um método disponível em um software dedicado (DE lung PBV -Siemens Healthcare), que fornece de forma automática o valor do realce do parênquima pulmonar em Unidades Hounsfield (UH) (19)(20)(21) . O realce do parênquima é obtido a partir do algoritmo de decomposição tri-material (ar, tecido e iodo), extraindo-se a atenuação do parênquima pulmonar que é atribuída ao iodo, sendo equivalente à densidade de iodo dentro de um determinado volume pulmonar (22) .…”