Functional imaging of adrenal cortex. / Estudios de imagen funcional de la corteza adrenal.

The rising number of high-resolution imaging scans has increased the adrenal lesions detection, which require a differential diagnosis. Currently, the most commonly used scans are CT and MRI, but these are sometimes not very specific. In these cases, nuclear medicine scans with 131I-norcolesterol, 11C-metomidate and 18F-fludeoxyglucose help to differentiate benign vs. malignant lesions, to lateralize the involvement in hypersecretion disease, as well as to guide the therapeutic strategy in both unilateral and bilateral lesions.

Contralateral adrenal suppression on adrenocortical scintigraphy provides good evidence showing subclinical cortisol overproduction from unilateral adenomas.

Unilateral and/or predominant uptake on adrenocortical scintigraphy (ACS) may be related to autonomous cortisol overproduction in patients with subclinical Cushing's syndrome (SCS). However, there is no information regarding whether increased tracer uptake on the tumor side or decreased uptake on the contralateral side on ACS is more greatly associated with inappropriate cortisol production. Therefore, we evaluated the relationship between quantitative 131I-6ß-iodomethyl-norcholesterol (131I-NP-59) uptake in both adrenal glands and parameters of autonomic cortisol secretion and attempted to set a cut off for SCS detection. The study included 90 patients with unilateral adrenal adenoma who fulfilled strict criteria. The diagnosis of SCS was based on serum cortisol ≥3.0 µg/dL after 1-mg dexamethasone suppression test (DST) with at least 1 other hypothalamus-pituitary-adrenal axis function abnormality. Twenty-two (27.7%) subjects were diagnosed with SCS. The uptake rate on the affected side in the SCS group was comparable to that in the non-functioning adenoma group. In contrast, the uptake rate on the contralateral side was lower and the laterality ratio significantly higher in the SCS group. The two ACS indices were correlated with serum cortisol levels after a 1-mg DST, but uptake on the tumor side was not. Tumor size was also important for the functional statuses of adrenal tumors and NP-59 imaging patterns. The best cut-off point for the laterality ratio to detect SCS was 3.07. These results clearly indicate that contralateral adrenal suppression in ACS is good evidence showing subclinical cortisol overproduction.

A case of ganglioneuroma in which 131I-6beta-iodomethyl-19-norcholest-5(10)-en-3beta-ol scintigraphy showed high uptake in the adrenal gland leading to a misdiagnosis.

We experienced a case in which 131I-6beta-iodomethyl-19-norcholest-5(10)-en-3beta-ol (131I-adosterol) scintigraphy showed high uptake in the right adrenal gland. We diagnosed functional cortical adenoma because of the finding of 131I-adosterol scintigraphy. However, no positive findings for the existence of cortical adenoma were obtained in other examinations and we performed right adrenalectomy. Unexpectedly, pathological finding showed the right adrenal gland was occupied with a large ganglioneuroma. This is an instructive case in which 131I-adosterol scintigraphy showed abnormal high uptake in the adrenal gland, in spite of the fact that the adrenal gland was occupied by a tumor derived from adrenal medulla.

Tomographic evaluation of [131I] 6beta-iodomethyl-norcholesterol standardised uptake trend in clinically silent monolateral and bilateral adrenocortical incidentalomas.

AIM: The aim of this study was three-fold: 1) to quantify [131I]-6beta-iodomethyl-norcholesterol ([131I]-NP-59) adrenal uptake trend in patients with incidentalomas, 2) to identify a specific uptake trend (TREND) capable of characterising pre-clinical Cushing syndrome (PC-CS) patients, 3) to assess the clinical availability of TREND as a prognostic factor of late clinical outcome in a cohort of patients with bilateral adrenal adenomas. METHODS: Fifty-seven consecutive patients were examined using three-head SPECT at 24, 48, 72 hours following intravenous injection of [131I ]-NP-59. On the basis of the absence or presence of hormonal abnormalities, the selected population was classified as GR1 or GR2, respectively. Adrenal glands were classified into 4 groups taking into account both the patient group (GR1, GR2) and the presence (+) or absence (-) of the adenoma (AD) on CT scan. Using ROI technique, adrenal-liver uptake ratio (A/L) was estimated bilaterally at 24, 48 and 72 hours. For each adrenal group, mean [131I]-NP-59 uptake trends were derived. RESULTS: TREND was significantly different between GR1/AD+ and GR2/AD+. Among GR2/AD+ patients, TREND correctly identified PC-CS with a global accuracy of 74%. Two patients with bilateral incidentaloma developed an overt CS. In both patients, TREND correctly identified the hyperfunctioning adrenal, thus permitting an effective sparing adrenalectomy. CONCLUSIONS: TREND seems to be a parameter which closely reflects adrenal physiological behaviour, especially in the case of bilateral adrenal involving. The possibility to quantify even contralateral adrenal uptake as standardised index provides additional useful information about normal adrenal parenchyma and, indirectly, about adenoma functional autonomy.

SPECT semiquantitative analysis of adrenocortical (131)I-6 beta iodomethyl-norcholesterol uptake to discriminate subclinical and preclinical functioning adrenal incidentaloma.

UNLABELLED: The goal of this study was to evaluate the clinical reliability of the (131)I-6 beta-iodomethyl-norcholesterol ((131)I-NP-59) uptake semiquantitative evaluation method we propose for the characterization of adrenocortical masses in a selected population of patients with disease clinically classified as subclinical (SC) and preclinical (PC) Cushing's syndrome (CS) according to Reincke's definition. METHODS: Forty-seven consecutive patients with incidentally discovered unilateral adrenal masses were examined by a triple-head SPECT system after intravenous injection of (131)I-NP-59. Abdominal SPECT was performed at 24, 48, 72, and, in selected cases, 96 h after tracer injection. Connected with adrenals and liver, a standard elliptic region of interest (ROI) was manually drawn, taking care to avoid the gallbladder region. The adrenal ROI integral count, obtained by summing the 24-, 48-, and 72-h counting values, was normalized by the hepatic integral count. Subsequently, the adrenal percentage of relative uptake (UPT%) was computed. RESULTS: Discriminant analysis was performed on the variables UPT%, adrenocorticotropic hormone (ACTH) serum concentration, and CT mass dimension (CTMD) to determine the variable, or combination thereof, best discriminating between the SC-CS and PC-CS groups. Compared with both ACTH and CTMD variables, univariate analysis confirmed the UPT% variable as the most significant to discriminate between these 2 clinical groups. In fact, UPT% alone correctly classified 8 of 9 patients in the SC-CS group and 20 of 22 patients in the PC-CS group with 95% positive and 80% negative predictive values and with overall accuracy, sensitivity, and specificity equal to 90%, 91%, and 89%, respectively. When all 3 variables were submitted to stepwise discriminant analysis, the derived classification matrix, after cross-validation, correctly classified 9 of 9 patients in the SC-CS group and 18 of 22 patients in the PC-CS group with 100% positive and 69% negative predictive values and with overall accuracy, sensitivity, and specificity equal to 87%, 82%, and 100%, respectively. CONCLUSION: According to these initial results, use of the proposed semiquantitative approach associated with both laboratory screening for cortisol production and CTMD measure seems to be able to increase the clinical diagnostic accuracy of PC-CS. This approach could be used in the follow-up of adrenal mass function every time hormonal or clinical features are suggestive of adrenocortical hyperfunction.

Adrenocortical scintigraphy with 131I-6-beta-iodomethyl-norcholesterol (NP 59) in bilateral adrenocortical carcinoma.

A case of a 49-year-old man suffering from bilateral adrenocortical carcinoma with local and secondary rapid progression is reported. The results of adrenocortical scintigraphy (NP 59) and histological findings allowed the diagnosis. This case report and a literature review showed the importance of using adrenocortical scintigraphy as a complementary imaging procedure of CT or MR images.