Utility of various functional and anatomic imaging modalities for detection of ectopic adrenocorticotropin-secreting tumors.

CONTEXT: Because ectopic ACTH-secreting (EAS) tumors are often occult, improved imaging is needed. OBJECTIVE: Our objective was to evaluate the utility of [(111)In-DTPA-d-Phe]pentetreotide scintigraphy [octreotide (OCT)] imaging at 6 mCi [low OCT (LOCT)] and 18 mCi [high OCT (HOCT)], [(18)F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) and [(18)F]l-3,4-dihydroxyphenylalanine (F-DOPA)-PET scans, computed tomography (CT), and magnetic resonance imaging (MRI). DESIGN AND SETTING: The study was a prospective evaluation at a clinical research center. PATIENTS: Forty-one subjects participated, 30 (17 female) with resected EAS tumors and 11 (three female) with occult EAS, based on inferior petrosal sinus sampling results and imaging studies. INTERVENTION: INTERVENTION included CT and MRI of neck, chest, abdomen, LOCT (with or without HOCT) and FDG- or F-DOPA-PET without CT every 6-12 months. MAIN OUTCOME MEASURE: Tumor identification was the main outcome measure. RESULTS: Most recent results were analyzed. Eighteen patients had tumor resected on the first visit; otherwise, surgery occurred 33 +/- 25 (9-99) months later. Tumor size was 1.9 +/- 1.7 (0.8-8.0) cm; 83% were intrathoracic. CT, MRI, LOCT, HOCT, FDG-PET, and F-DOPA-PET had sensitivities per patient of 93% [95% confidence interval (CI) = 79-98%], 90% (95% CI = 74-96%), 57% (95% CI = 39-73%), 50% (95% CI = 25-75%), 64% (95% CI = 35-85%), and 55% (95% CI = 28-79%) and positive predictive values (PPV) per lesion of 66, 74, 79, 89, 53, and 100%, respectively. LOCT and PET detected only lesions seen by CT/MRI; abnormal LOCT or F-DOPA-PET improved PPV of CT/MRI. By modality, the fraction of patients with one or more false-positive findings was 50% by CT, 31% by MRI, 18% by L/HOCT, and 18% by FDG-PET. Eight occult EAS patients had 64 +/- 58 (9-198) months follow-up; others had none. CONCLUSIONS: High sensitivity and PPV suggest thoracic CT/MRI plus LOCT scans for initial imaging, with lesion confirmation by two modalities.

A change in pituitary magnetic resonance imaging protocol detects ACTH-secreting tumours in patients with previously negative results.

OBJECTIVE: While detection of pituitary tumours with magnetic resonance imaging (MRI) may reduce diagnostic costs and improve surgical outcomes for patients with Cushing's disease, the optimal T1-weighted spin-echo (SE) MRI protocol remains unknown. We hypothesized that specific MR scanning parameters influence detection of corticotropinomas. DESIGN AND PATIENTS: Between December 1997 and November 2004, 21 of 84 consecutive patients with Cushing's disease had a falsely negative initial pituitary MRI study and a lesion identified subsequently at the National Institutes of Health Clinical Center. This study retrospectively reviewed and compared technical parameters used for the two pituitary T1-weighted SE MRIs in 18 patients with available scans. MEASUREMENTS: Repetition time (TR)/echo times (TE), field of view (FOV), matrix size, magnetic field strength, slice thickness, use of gadolinium contrast and the time interval between studies were recorded. RESULTS: The MRI interscan interval was 5.4 +/- 1.1 months. All scans used gadolinium, matrix sizes were similar and nearly all had 3-mm thick slices. Parameters that differed between the NIH- and externally performed scans were: TR (400 ms vs. 492 +/- 19 ms, P = 0.0002); TE (10.3 +/- 0.5 vs. 17.2 +/- 1.2 ms, P = 0.0003); FOV (12 x 12 cm vs.17 +/- 0.6 x 18 +/- 0.7 cm, P < 0.0001). Immunohistochemistry of tumours resected at transsphenoidal surgery confirmed all to be corticotropinomas. CONCLUSIONS: Not all 'T1-weighted SE' scans are equally accurate. MRI technique, particularly FOV and TR/TE value, influences results. We recommend that endocrinologists consider pituitary MRI parameters when interpreting the results.