Occult lung infarction may induce false interpretation of 18F-FDG PET in primary staging of pulmonary malignancies

Abstract

Abstract. Purpose: The aim of the present report is to describe abnormal 18 F-fluorodeoxyglucose (FDG) accumulation patterns in the pleura and lung parenchyma in a group of lung cancer patients in whom lung infarction was present at the time of positron emission tomography (PET). Methods: Between November 2002 and December 2003, a total of 145 patients (102 males, 43 females; age range 38-85 years) were subjected to whole-body FDG PET for initial staging (n=117) or restaging (n=11) of lung cancer or for evaluation of solitary pulmonary nodules (n=17). Of these patients, 24 displayed abnormal FDG accumulation in the lung parenchyma that was not consistent with the primary lesion under investigation (ipsilateral n=12, contralateral n=9 or bilateral n=3). Without correlative imaging, this additional FDG uptake would have been considered indeterminate in differential diagnosis. Results: Of the 24 patients who were identified as having such lesions, six harboured secondary tumour nodules diagnosed as metastases, while in three the diagnosis of a synchronous second primary lung tumour was established. Additionally, nine patients were identified as having poststenotic pneumonia and/or atelectasis (n=6) or granulomatous lung disease (n=3). In the remaining six (4% of all patients), a diagnosis of recent pulmonary embolism that topographically matched the additional FDG accumulation (SUV max range 1.4-8.6, mean 3.9) was made. Four of these six patients were known to have pulmonary embolism, and hence false positive interpretation was avoided by correlating the PET findings with those of the pre-existing diagnostic work-up. The remaining two patients were harbouring small occult infarctions that mimicked satellite nodules in the lung periphery. Based on histopathological results, the abnormal FDG accumulation in these two patients was attributed to the inflammatory reaction and tissue repair associated with the pathological cascade of pulmonary embolism. Conclusion: In patients with pulmonary malignancies, synchronous lung infarction may induce pathological FDG accumulation that can mimic active tumour manifestations. Identifying this potential pitfall may allow avoidance of false positive FDG PET interpretation.

The Incidence of Pulmonary Embolism and Associated FDG-PET Findings in IV Contrast-Enhanced PET/CT

“…4). All these cases demonstrated some focal hypermetabolism associated with the infarction, as has been previously described (13,30). One demonstrated a complete rim of FDG avidity (Fig.…”

Diagnostic usefulness of 18F-FDG PET/CT in the differentiation of pulmonary artery sarcoma and pulmonary embolism

“…Kamel et al [12] suggested that infarctions from pulmonary embolism on PET alone might be mistaken for malignancy because of the high FDG uptake in such lesions. However, their study included the inflammatory area in the peripheral zone of lung parenchyma using PET alone, which could not detect the embolus itself.…”

“…These reports have suggested that a high FDG uptake can distinguish PAS from PE. On the other hand, some reports have suggested that pulmonary emboli can have various uptakes and occasionally misdiagnose PE as malignancy [12]. However, a direct comparison of the maximum standardized uptake value (SUV max ) of FDG uptake in PAS and PE has not been reported.…”

False-Positive FDG PET Uptake−the Role of PET/CT

“…Recent lung infarction or anthracosilicosis [29] may induce false-positive findings [30]. Pneumonia typically causes diffuse FDG accumulation, which is easily recognized, but with cavitations, and necrosis pneumonia can be indistinguishable from neoplasms with central necrosis.…”