Ventilation-perfusion SPECT/CT in Diagnosing Swyer-James (MacLeod) Syndrome

摘要

We present the characteristics of a ventilation-perfusion scan correlating to both planar and single photon emission computed tomography and computed tomography (SPECT/CT) images of the lungs in a patient with Swyer-James (MacLeod) syndrome. A Tc-99m MAA lung perfusion scan was recorded with multiple projections and SPECT/CT. In the ventilation scan, initially dynamic acquisition of aerosol Tc-99m DTPA was obtained with an interval of 0.4 seconds per frame, followed by multiple static projections and SPECT/CT. Anatomically co-registered SPECT/CT of perfusion images demonstrated diffusely decreased perfusion without CT chest lesions over the affected radiolucent left lung. The SPECT/CT of ventilation scan showed heterogeneous radiotracer distribution and multiple defects resembling airflow obstruction over the left lung. A dynamic ventilation scan revealed diminished inhaled radioisotope in the left lung compared with the normal right lung. In contrast to over aeration of the left lung observed in the same area on CT, the dynamic hypoventilation implies the presence of air trapping. The SPECT/CT of ventilation-perfusion study showed matched defects in the left lung excluding a residual area of normal density, and permitted a specific reconstructive display to exhibit the pathophysiology of Swyer-James (MacLeod) syndrome with anatomic and functional co-registration.