The diagnostic value of fused positron emission tomography/computed tomography in the localization of adrenocorticotropin-secreting pituitary adenoma in Cushing’s disease

Abstract

Despite the high resolution of magnetic resonance imaging (MRI) of the pituitary gland, up to 40% of cases of Cushing's disease (CD) have normal MRI. Fused images of positron emission tomography and computed tomography (PET-CT) may have a potential diagnostic role in CD in general and in such cases in particular. Objective of this study is to explore the diagnostic potential of PET-CT for localization of adrenocorticotropin-secreting pituitary adenomas in CD. PET-CT was performed in 12 cases with de novo (7 cases) or persistent CD (5 cases) that were proven to have CD on biochemical, radiological and/or histopathological findings. These cases had a definite CD confirmed on histopathological and immunostaining examination of the subsequent transphenoidal surgical specimens (10 cases) and/or bilateral inferior petrosal sinus sampling (IPSS, 4 cases). PET-CT was positive in 7 of the 12 cases of CD (58%) showing a focal area of uptake in the pituitary gland. In these seven cases, MRI was positive in six (85.7%) but negative in one case (14.3%). In the other five cases with negative PET-CT, MRI was positive in two and negative in three cases. Of four cases with negative MRI, PET-CT was positive in one case (25%). We conclude that PET-CT is positive in around 60% of the cases of CD. Although the majority of cases with positive PET-CT had positive MRI, PET-CT may detect some cases with negative MRI and thus provides important diagnostic information. If these findings are confirmed in larger studies, PET-CT might become an important diagnostic technique, especially when the more invasive and technically demanding procedure of IPSS is not available or inconclusive.

Utility of 11C-Methionine and 18F-FDG PET/CT in Patients With Functioning Pituitary Adenomas

“…Hence, new methods should be explored. Although 18 F-FDG PET is helpful for detecting the sites of ACTH secretion, [19][20][21] Alzahrani et al 22 concluded that the positive rate of 18 F-FDG PET/CT is approximately 60% in patients with Cushing disease. As in our study, the sensitivity of 18 F-FDG PET/CT is unsatisfactory.…”

Pituitary Metastasis and the Role of CSF Pulsations in Secondary Displacement after Surgery

“…For nonfunctioning adenomas, 18F-FDG PET scans are usually negative, because of the low metabolic activity that is often similar to normal cells. However, the cells of functioning tumors may be more active and some studies report that functioning pituitary macro-and micro adenomas can show increased FDG uptake on PET [7][8][9][10]. In our patient the 18F-FDG PET-CT showed a precocious SUVmax at 6.2 becoming 8.9 in the late sequences.…”

Metabolic In Vivo Visualization of Pituitary Adenomas: a Systematic Review of Imaging Modalities

“…1 Functional adenomas, comprising roughly 70% of PAs, 1–3 produce excess hormone secretion that can lead to a variety of clinical symptoms and associated syndromes. 4 The most common functional PAs, in descending order, are prolactin-secreting (prolactinomas), growth hormone (GH)-secreting, corticotropin (ACTH)-secreting, gonadotropin (LH or FSH)-secreting, and thyrotropin (TSH)-secreting adenomas. 5 The remaining 30% of PAs are classified as nonfunctional, which mainly produce symptoms due to their mass effect.…”

“…Routine laboratory studies, such as dexamethasone suppression tests, are able to definitively diagnose hormonal disorders at low cost, but suffer from low sensitivity and rates of false positives and negatives in up to 50% of cases. 4,7,8 Laboratory studies are also unable to localize the site of aberrant hormone secretion. Moreover, there may be a significant time lapse until hormone levels accrue to the point of eliciting detectable alterations in lab values, which can delay appropriate treatment.…”