INTERESTING IMAGE
Asymmetric Pulmonary Hypermetabolism on 18F-FDG PET/CT Caused by Pulmonary Embolism Evert Caekebeke, MD,* Christophe M. Deroose, MD, PhD,* Peter Verhamme, MD, PhD,† Johan Coolen, MD,‡ and Olivier Gheysens, MD, PhD* Abstract: We present a case of diffuse and moderately increased 18F-FDG uptake in the entire left lung on 18F-FDG PET without any morphological parenchymal abnormalities in a patient with recent history of esophageal adenocarcinoma treated by minimal invasive surgery and adjuvant chemotherapy. Contrast-enhanced CT revealed a large embolism in the left pulmonary artery with near total occlusion. In the absence of parenchymal lesions, the increased 18 F-FDG uptake is most likely an inflammatory response to a recent ischemic insult. This case illustrates that asymmetric lung hypermetabolism in the absence of parenchymal disease can be caused by a central pulmonary embolism. Key Words: 18F-FDG PET, paraneoplastic, pulmonary embolism, lung uptake (Clin Nucl Med 2015;40: 338–339)
Received for publication June 13, 2014; revision accepted November 12, 2014. From the Depatments of *Nuclear Medicine, †Cardiovascular Medicine, and ‡Radiology, University Hospitals Leuven, Leuven, Belgium. Conflicts of interest and sources of funding: none declared. Reprints: Olivier Gheysens, MD, PhD, Department of Nuclear Medicine, University Hospitals Leuven, Herestraat 49, Leuven, B-3000 Belgium. E-mail: [email protected]. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0363-9762/15/4004–0338
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REFERENCES 1. Donadini MP, Dentali F, Squizzato A, et al. Unsuspected pulmonary embolism in cancer patients: a narrative review with pooled data. Intern Emerg Med. 2014;9: 375–384. 2. Wagner T, Brechemier D, Dugert E, et al. Diffuse pulmonary uptake on FDG-PET with normal CT diagnosed as intravascular large B-cell lymphoma: a case report and a discussion of the causes of diffuse FDG uptake in the lungs. Cancer Imaging. 2012;12:7–12. 3. Acikgoz G, Kim SM, Houseni M, et al. Pulmonary lymphangitic carcinomatosis (PLC): spectrum of FDG-PET findings. Clin Nucl Med. 2006;31:673–678. 4. Chen DL, Bedient TJ, Kozlowski J, et al. [18F]fluorodeoxyglucose positron emission tomography for lung antiinflammatory response evaluation. Am J Respir Crit Care Med. 2009;180:533–539. 5. Nakos G, Kitsiouli E, Lekka ME. Bronchoalveolar lavage alterations in pulmonary embolism. Am J Respir Crit Care Med. 1998;158:1504–1510. 6. Halici B, Sarinc Ulasli S, Günay E, et al. Assessment of inflammatory biomarkers and oxidative stress in pulmonary thromboembolism: follow-up results. Inflammation. 2014;37:1186–1190. 7. Bergqvist D. Venous thromboembolism in cancer patients: expanding horizons. Semin Thromb Hemost. 2002; 28(Suppl 3):19–23. 8. van der Hulle T, Kooiman J, den Exter PL, et al. Effectiveness and safety of novel oral anticoagulants as compared with vitamin K antagonists in the treatment of acute symptomatic venous thromboembolism: a systematic review and meta-analysis. J Thromb Haemost. 2014;12:320–328.
Clinical Nuclear Medicine • Volume 40, Number 4, April 2015 Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
Clinical Nuclear Medicine • Volume 40, Number 4, April 2015
Asymmetric Pulmonary Hypermetabolism on 18F-FDG
FIGURE 1. A 54-year-old man with a recent history of esophageal adenocarcinoma treated with minimal invasive surgery and adjuvant chemotherapy underwent a routine follow-up 18F-FDG PET/CT examination. There was no clinical or biochemical suspicion for recurrence. 18F-FDG PET/CT scan revealed a homogenously diffused and moderately increased FDG uptake within the entire left lung (A and B, non–attenuation-corrected transaxial and coronal image; D and E attenuation-corrected transaxial and coronal image) without any morphological parenchymal abnormalities (F, CT lung window). However, contrast-enhanced CT revealed a large embolism in the left pulmonary artery, which was nearly totally occluded (C, CT soft tissue window). Incidental finding of pulmonary thromboembolism (PTE) on contrast-enhanced CT in an oncological setting is not uncommon1; however, PTE will most often remain undiagnosed on 18F-FDG PET or 18F-FDG PET/CT without contrast CT. Unilateral diffuse lung uptake is rare, and only limited data are published in the literature. Wagner et al2 described several causes of diffuse unilateral and bilateral FDG uptake in the lungs with negative CT findings such as chemotherapy/immunotherapy-induced pneumonitis and acute respiratory distress syndrome. Pulmonary lymphangitic carcinomatosis also can present as diffuse unilateral 18F-FDG uptake.3 However, in our case, the increased unilateral 18F-FDG uptake in absence of parenchymal lesions is most likely the result of an inflammatory reaction secondary to a recent ischemic insult4 caused by a central pulmonary embolism. Several authors have reported an up-regulation of inflammatory mediators in (acute) hypoxic lung tissue. Nakos et al5 assessed bronchoalveolar lavage fluid from patients with PTE and mechanically ventilated patients without PTE and found increased levels of total protein, albumin, phospholipids, platelet-activating factor, and platelet-activating factor acetylhydrolase in the group with PTE. Halici et al6 reported increased proinflammatory cytokines (interleukin-6, tumor necrosis factor-α) in 38 patients diagnosed with PTE in comparison with 38 healthy volunteers. These studies revealed an up-regulation of proinflammatory cytokines in response to an acute ischemic/hypoxic event, and the diffuse FDG uptake is most likely the result of an inflammatory reaction. The diagnosis of paraneoplastic pulmonary embolism was made, and the patient was referred to the department of cardiovascular medicine.7Treatment with an oral anticoagulant (rivaroxaban) was started for 3 to 6 months.8
© 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.nuclearmed.com
339
Asymmetric Pulmonary Hypermetabolism on 18F-FDG PET/CT Caused by Pulmonary Embolism Evert Caekebeke, MD,* Christophe M. Deroose, MD, PhD,* Peter Verhamme, MD, PhD,† Johan Coolen, MD,‡ and Olivier Gheysens, MD, PhD* Abstract: We present a case of diffuse and moderately increased 18F-FDG uptake in the entire left lung on 18F-FDG PET without any morphological parenchymal abnormalities in a patient with recent history of esophageal adenocarcinoma treated by minimal invasive surgery and adjuvant chemotherapy. Contrast-enhanced CT revealed a large embolism in the left pulmonary artery with near total occlusion. In the absence of parenchymal lesions, the increased 18 F-FDG uptake is most likely an inflammatory response to a recent ischemic insult. This case illustrates that asymmetric lung hypermetabolism in the absence of parenchymal disease can be caused by a central pulmonary embolism. Key Words: 18F-FDG PET, paraneoplastic, pulmonary embolism, lung uptake (Clin Nucl Med 2015;40: 338–339)
Received for publication June 13, 2014; revision accepted November 12, 2014. From the Depatments of *Nuclear Medicine, †Cardiovascular Medicine, and ‡Radiology, University Hospitals Leuven, Leuven, Belgium. Conflicts of interest and sources of funding: none declared. Reprints: Olivier Gheysens, MD, PhD, Department of Nuclear Medicine, University Hospitals Leuven, Herestraat 49, Leuven, B-3000 Belgium. E-mail: [email protected]. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0363-9762/15/4004–0338
338
www.nuclearmed.com
REFERENCES 1. Donadini MP, Dentali F, Squizzato A, et al. Unsuspected pulmonary embolism in cancer patients: a narrative review with pooled data. Intern Emerg Med. 2014;9: 375–384. 2. Wagner T, Brechemier D, Dugert E, et al. Diffuse pulmonary uptake on FDG-PET with normal CT diagnosed as intravascular large B-cell lymphoma: a case report and a discussion of the causes of diffuse FDG uptake in the lungs. Cancer Imaging. 2012;12:7–12. 3. Acikgoz G, Kim SM, Houseni M, et al. Pulmonary lymphangitic carcinomatosis (PLC): spectrum of FDG-PET findings. Clin Nucl Med. 2006;31:673–678. 4. Chen DL, Bedient TJ, Kozlowski J, et al. [18F]fluorodeoxyglucose positron emission tomography for lung antiinflammatory response evaluation. Am J Respir Crit Care Med. 2009;180:533–539. 5. Nakos G, Kitsiouli E, Lekka ME. Bronchoalveolar lavage alterations in pulmonary embolism. Am J Respir Crit Care Med. 1998;158:1504–1510. 6. Halici B, Sarinc Ulasli S, Günay E, et al. Assessment of inflammatory biomarkers and oxidative stress in pulmonary thromboembolism: follow-up results. Inflammation. 2014;37:1186–1190. 7. Bergqvist D. Venous thromboembolism in cancer patients: expanding horizons. Semin Thromb Hemost. 2002; 28(Suppl 3):19–23. 8. van der Hulle T, Kooiman J, den Exter PL, et al. Effectiveness and safety of novel oral anticoagulants as compared with vitamin K antagonists in the treatment of acute symptomatic venous thromboembolism: a systematic review and meta-analysis. J Thromb Haemost. 2014;12:320–328.
Clinical Nuclear Medicine • Volume 40, Number 4, April 2015 Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
Clinical Nuclear Medicine • Volume 40, Number 4, April 2015
Asymmetric Pulmonary Hypermetabolism on 18F-FDG
FIGURE 1. A 54-year-old man with a recent history of esophageal adenocarcinoma treated with minimal invasive surgery and adjuvant chemotherapy underwent a routine follow-up 18F-FDG PET/CT examination. There was no clinical or biochemical suspicion for recurrence. 18F-FDG PET/CT scan revealed a homogenously diffused and moderately increased FDG uptake within the entire left lung (A and B, non–attenuation-corrected transaxial and coronal image; D and E attenuation-corrected transaxial and coronal image) without any morphological parenchymal abnormalities (F, CT lung window). However, contrast-enhanced CT revealed a large embolism in the left pulmonary artery, which was nearly totally occluded (C, CT soft tissue window). Incidental finding of pulmonary thromboembolism (PTE) on contrast-enhanced CT in an oncological setting is not uncommon1; however, PTE will most often remain undiagnosed on 18F-FDG PET or 18F-FDG PET/CT without contrast CT. Unilateral diffuse lung uptake is rare, and only limited data are published in the literature. Wagner et al2 described several causes of diffuse unilateral and bilateral FDG uptake in the lungs with negative CT findings such as chemotherapy/immunotherapy-induced pneumonitis and acute respiratory distress syndrome. Pulmonary lymphangitic carcinomatosis also can present as diffuse unilateral 18F-FDG uptake.3 However, in our case, the increased unilateral 18F-FDG uptake in absence of parenchymal lesions is most likely the result of an inflammatory reaction secondary to a recent ischemic insult4 caused by a central pulmonary embolism. Several authors have reported an up-regulation of inflammatory mediators in (acute) hypoxic lung tissue. Nakos et al5 assessed bronchoalveolar lavage fluid from patients with PTE and mechanically ventilated patients without PTE and found increased levels of total protein, albumin, phospholipids, platelet-activating factor, and platelet-activating factor acetylhydrolase in the group with PTE. Halici et al6 reported increased proinflammatory cytokines (interleukin-6, tumor necrosis factor-α) in 38 patients diagnosed with PTE in comparison with 38 healthy volunteers. These studies revealed an up-regulation of proinflammatory cytokines in response to an acute ischemic/hypoxic event, and the diffuse FDG uptake is most likely the result of an inflammatory reaction. The diagnosis of paraneoplastic pulmonary embolism was made, and the patient was referred to the department of cardiovascular medicine.7Treatment with an oral anticoagulant (rivaroxaban) was started for 3 to 6 months.8
© 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
www.nuclearmed.com
339
