Value of 99mTc-Technegas SPECT/CT for Localization of Alveolar-pleural Fistulas

Fig. 1. A 77-year-old male with a history of recent resection of pulmonary metastasis from rectal cancer underwent ventilation single-photon emission computed tomography/computed tomography (SPECT/CT) for further evaluation of a persistent alveolar-pleural fistula resulting in pneumothorax and extensive soft tissue emphysema. 99mTc-Technegas SPECT (a), fused coronal (b) and axial SPECT/CT (c, d, e) demonstrated marked tracer deposition in the apical right upper lobe (arrow) due to focal trapping of 99mTc-Technegas particles and visualized 99mTc-Technegas transport via the chest tube (arrowhead). Axial CT images (f, g) demonstrated soft tissue emphysema. Wedge resection was performed and confirmed an alveolar-pleural fistula, and the pneumothorax resolved completely after surgical therapy. Prolonged parenchymal air leak, defined as air leak persisting over 5 days, is the most frequent complication after lung resection and is reported to occur in 16–18 % of cases [1, 2]. It has been reported to be associated with incomplete interlobar fissures, emphysematous lungs, upper lobe resections and pleural adhesions [1]. It frequently leads to a more complicated and protracted hospital course [3–5]. In persistent air leaks, surgical re-exploration must be considered after failure of conservative treatment [6]. 99mTc-Technegas ventilation scintigraphy is an established and well-studied tool for imaging of lung ventilation [7], and combined SPECT/CT has been shown to improve overall diagnostic accuracy in many areas of pulmonary nuclear medicine [7, 8]. Precise localization of air leaks is desirable for newer interventional treatment options including endobronchial valves [6] to guide valve placement and may facilitate the surgical approach. Ventilation SPECT has been suggested to be useful for localization of air leaks before [9, 10], but focal 99mTc-Technegas deposition in the lungs has not been evidenced to represent an actual fistula by either transport via the chest tube or surgical resection, for the previous reports relied on conservative treatment. This is a case of persistent alveolar-pleural fistula following thoracic surgery correctly detected on 99mTc-Technegas SPECT/CT