Aerosolised radionuclides for functional imaging in COPD/asthma

Abstract

Radiolabelled aerosols provide a versatile means of studying the pathophysiology of lung disease. If aerosols consisting of small particles are used, a qualitative image of the distribution of ventilation is obtained. Larger particles are deposited by inertial impaction, mainly in larger airways. This mechanism is related to changes in the direction and velocity of airflow rather than to ventilation and is therefore very sensitive to airway narrowing. Measurements of aerosol deposition can therefore identify very early changes in the airways in chronic obstructive pulmonary disease (COPD) and asthma. Aerosols of solid particles can, when deposited on the ciliated mucosa, be used for assessment of mucociliary clearance and are useful for evaluation of therapeutic measures in COPD and asthma. Soluble tracers delivered as aerosols may be absorbed from the lungs into the bloodstream and provide a measure of the permeability of the alveolar-capillary barrier. Finally, radioactive aerosols are extensively used in the development of devices and formulations for inhaled pharmaceuticals.

Improvement in image quality of Tc-99m-based ventilation/perfusion single-photon emission computed tomography in patients with chronic obstructive pulmonary disease through pretest continuous positive airway pressure treatment

“…These patients exhibit increased mucus production that results in accumulation of the radioactive tracer in "hot spots" when ventilation imaging is performed through inhalation of a carbon-coated technetium aerosol. [3,4] Continuous positive airway pressure (CPAP) physiotherapy is frequently used for COPD patients to assist with mucus mobilization. [5] We present two cases [Figures 1 and 2] in which pretest CPAP reduced deposition of the tracer in central airways, thereby improving imaging quality.…”