FDG-PET/CT in the detection of pituitary stalk ACTH-secreting adenoma

BackgroundEctopic adrenocorticotropic hormone (ACTH)-secreting lung tumors represent the most common cause of ectopic Cushing syndrome (ECS). Pulmonary opportunistic infections are associated with ECS. The present study aimed to evaluate the usefulness of 18F-FDG PET/CT for differentiating ectopic ACTH-secreting lung tumors from tumor-like pulmonary infections in patients with ECS.MethodsWe retrospectively reviewed the imaging data of 24 patients with ECS who were suspected to have ACTH-secreting lung tumors and underwent 18F-FDG PET/CT between 2008 and 2019. Eleven patients with lung tumors and 4 with pulmonary infections also had additional somatostatin receptor imaging (99mTc-HYNIC-TOC SPECT/CT or 68Ga-DOTATATE PET/CT).ResultsIn total, 18 patients had lung tumors and six had pulmonary infections. The primary source of ECS remained occult in the six patients with pulmonary infections. The maximum standardized uptake value (SUVmax) for pulmonary infections was significantly higher than that for tumors (P = 0.008). Receiver operating characteristic analysis revealed that a cut-off SUVmax of 4.95 helped in differentiating ACTH-secreting lung tumors from infections with 75% sensitivity and 94.4% specificity. For the 11 patients with ACTH-lung tumors, somatostatin receptor imaging (SRI) was positive in 6; while for the 4 with pulmonary infections, SRI was positive in 2. The sensitivity and specificity of somatostatin receptor imaging (SRI) for detecting ACTH-secreting lung tumor was 54.5% and 50%.ConclusionsOur findings suggest that pulmonary infections exhibit significantly higher FDG uptake than ACTH-secreting lung tumors in 18F-FDG PET/CT. An SUVmax cut-off value of 4.95 may be useful for differentiating the two conditions. Our results also suggested that SRI may not be an effective tool for differentiating the two conditions given the relatively low specificity.

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Use of 18F-FDG PET/CT to differentiate ectopic adrenocorticotropic hormone-secreting lung tumours from tumour-like pulmonary infections in patients with ectopic Cushing syndrome

10.21203/rs.3.rs-16145/v1 ◽

2020 ◽

Author(s):

Guozhu Hou ◽

Yuanyuan Jiang ◽

Fang Li ◽

Xin Cheng

Keyword(s):

Fdg Pet ◽

Adrenocorticotropic Hormone ◽

Cushing Syndrome ◽

Pulmonary Infections ◽

Lung Tumours ◽

Pet Ct ◽

18F Fdg ◽

Ectopic Adrenocorticotropic Hormone ◽

Fdg Pet Ct ◽

Acth Secreting

Abstract Purpose: Ectopic adrenocorticotropic hormone (ACTH)-secreting lung tumours represent the most common cause of ectopic Cushing syndrome (ECS). Pulmonary opportunistic infections are associated with ECS and occasionally difficult to differentiate from tumours by using computed tomography (CT) alone. The aim of the present study was to evaluate the usefulness of 18F-fluorodeoxyglucose (FDG) positron emission tomography/CT (18F-FDG PET/CT) for differentiating ectopic ACTH-secreting lung tumours from tumour-like pulmonary infections in patients with ECS.Methods: We retrospectively reviewed the imaging data for 24 patients with ECS who were suspected to have ACTH-secreting lung tumours and underwent 18F-FDG PET/CT between 2008 and 2019.Results: In total, 18 patients had lung tumours (17 carcinoids and 1 small cell lung cancer) and six had pulmonary infections (cryptococcosis, n = 3; aspergillosis, n = 4; pulmonary abscess, n = 1). The primary source of ECS remained occult in the six patients with pulmonary infections. The maximum standardized uptake value (SUVmax) for pulmonary infections was significantly higher than that for tumours (P = 0.008). Receiver operating characteristic analysis was performed, and it was found that a cut-off SUVmax of 4.95 helped in differentiating lung tumours from infections with 75% sensitivity and 94.4% specificity. In subgroup analysis of 12 typical and five atypical carcinoids, there was no significant between-group difference with respect to SUVmax, the lesion size, the ACTH level, and the prevalence of regional lymph node metastasis.Conclusions: Our findings suggest that pulmonary infections exhibit significantly higher FDG uptake than do ACTH-secreting lung tumours in 18F-FDG PET/CT. Therefore, SUVmax (cut-off 4.95) may be useful for differentiating the two conditions. Typical and atypical ACTH-secreting lung carcinoids may show a similar clinical behaviour and appearance on 18F-FDG PET/CT.

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Use of 18F-FDG PET/CT to differentiate ectopic adrenocorticotropic hormone-secreting lung tumors from tumor-like pulmonary infections in patients with ectopic Cushing syndrome

10.21203/rs.3.rs-403749/v1 ◽

2021 ◽

Author(s):

Guozhu Hou ◽

Yuanyuan Jiang ◽

Fang Li ◽

Xin Cheng

Keyword(s):

Fdg Pet ◽

Adrenocorticotropic Hormone ◽

Cushing Syndrome ◽

Lung Tumors ◽

Pulmonary Infections ◽

Pet Ct ◽

Ectopic Adrenocorticotropic Hormone ◽

Well Differentiated ◽

Fdg Pet Ct ◽

Acth Secreting

Abstract Background: Ectopic adrenocorticotropic hormone (ACTH)-secreting lung tumors represent the most common cause of ectopic Cushing syndrome (ECS). Pulmonary opportunistic infections are associated with ECS and occasionally difficult to differentiate from tumors by using computed tomography (CT) alone. The present study aimed to evaluate the usefulness of 18F-fluorodeoxyglucose (FDG) positron emission tomography/CT (18F-FDG PET/CT) for differentiating ectopic ACTH-secreting lung tumors from tumor-like pulmonary infections in patients with ECS.Methods: We retrospectively reviewed the imaging data for 24 patients with ECS who were suspected to have ACTH-secreting lung tumors and underwent 18F-FDG PET/CT between 2008 and 2019. Part of the 24 patients underwent 99mTc-HYNIC-TOC scintigraphy and 68Ga-DOTA-TATE PET/CT.Results: In total, 18 patients had lung tumors and six had pulmonary infections. The primary source of ECS remained occult in the six patients with pulmonary infections. The maximum standardized uptake value (SUVmax) for pulmonary infections was significantly higher than that for tumors (P = 0.008). Receiver operating characteristic analysis was performed, and it was found that a cut-off SUVmax of 4.95 helped in differentiating lung tumors from infections with 75% sensitivity and 94.4% specificity. In a subgroup analysis of 12 typical and five atypical carcinoids, there was no significant between-group difference with respect to SUVmax, the lesion size, the ACTH level, and the prevalence of regional lymph node metastasis. Four out of 6 patients with 5 infectious lesions and 16 out of 18 patients with 16 ACTH-secreting tumors underwent 99mTc-HYNIC-TOC scintigraphy, and 1/6 patients with 1 infectious lesion, and 6 out of 18 patients with 6 ACTH-secreting tumors underwent 68Ga-DOTA-TATE PET/CT. There is no significant difference in sensitivity between tumor lesions and infections using 99mTc-HYNIC-TOC scintigraphy. Conclusions: Our findings suggest that pulmonary infections exhibit significantly higher FDG uptake than do well-differentiated ACTH-secreting lung tumors in 18F-FDG PET/CT. Therefore, SUVmax (cut-off 4.95) may be useful for differentiating the two conditions. However, 99mTc-HYNIC-TOC scintigraphy is of no value in distinguishing the focus of well-differentiated ACTH-secreting lung tumors from that of infection. Typical and atypical ACTH-secreting lung carcinoids may show similar clinical behavior and appearance on 18F-FDG PET/CT.

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