Reduced Perfusion in Pulmonary Infiltrates of High-risk Hematologic Patients Is a Possible Discriminator of Pulmonary Angioinvasive Mycosis: A Pilot Volume Perfusion Computed Tomography (VPCT) Study

Rationale and Objectives: The aim of this study was to assess perfusion parameters in atypical pneumonia of heavily immunocompromised hematologic patients suspected of having invasive mycosis using volume perfusion computed tomography and establish their diagnostic role. Materials and Methods: Volume perfusion computed tomographic data from 21 consecutive immunocompromised patients presenting with atypical parenchymal opacity of consolidation were analyzed with respect to the degree of perfusion of their pneumonias. All patients presented with clinical and laboratory signs of infection. Seventeen patients (10 men, seven women; mean age, 57 years; age range, 19-76 years) were found with proven (n = 9), probable (n = 2), or possible (n = 6) angioinvasive mycosis. One patient was diagnosed with bronchoinvasive aspergillosis. Four patients (all men; mean age, 71 years; age range, 67-79 years) were diagnosed with bacterial pneumonia. Volume perfusion computed tomography of the involved pulmonary areas was performed at 80 kV and 60 mAs, with 26 measurement points distributed over 65.9 seconds. Fifty milliliters of contrast material was injected at a rate of 5 mL/s, followed by a 50-mL saline chaser. Entire coverage of the pneumonic parenchymal consolidation was obtained in all patients, with the generation of parametric maps of blood flow (BF) using the maximal slope model and blood volume (BV) using Patlak analysis. The results of perfusion measurements were then analyzed and evaluated for all patients. Results: Patients with proven, probable, or possible angioinvasive pulmonary fungal infection revealed very low levels of perfusion of their parenchymal consolidations, with BFs ranging from 0.01 to 23.86 mL/100 mL tissue/min and BVs ranging from 0.88 to 10.67 mL/100 mL tissue, lower than those of the adjacent thoracic musculature and of bacterial pneumonias. Bacterial pneumonias showed all increased perfusion parameters, with BFs ranging from 30.49 to 41.65 mL/100 mL tissue/min and BVs ranging from 10.07 to 49.90 mL/100 mL tissue. The cutoff BF value for differentiation was 23.89 mL/100 mL tissue/min, and the cutoff BV value was 9.6 mL/100 mL tissue. Conclusions: Patients with angioinvasive pulmonary mycosis showed lower perfusion parameters on volume perfusion computed tomography compared to those experiencing bacterial pneumonia.