High-resolution computed tomography in pituitary microadenoma: is seeing believing?

Analysis of indirect signs of microprolactinoma at MR imaging

OBJECTIVE

To evaluate the diagnostic reliability/value of microprolactinoma indirect signs at MRI.

METHODS AND MATERIAL

A prospective study was carried out over 3 years on 26 women with microprolactinoma (MiP group) and 106 healthy female volunteers as a control group. Size, glandular morphology, pituitary stalk inclination and sellar bony floor erosion were measured and a comparative statistical analysis between both groups was performed.

RESULTS

Patients from the MiP group showed a significantly bigger glandular size than women in the control group, although the glandular morphology did not present significant differences between both groups. Only 5% of normal glands measured over 7.5 mm in height and none of them reached 9 mm, while up to 42.3% of the MiP group scored over 7.5 mm and 19.2% over 9 mm. Mean stalk inclination for the MiP group was 4.6 +/- 3.1 degrees and 3.5 +/- 2.7 degrees for the control group with no significant differences. Five microprolactinomas were located on the glandular midline, 11 on the left side and ten on the right side. No relationship between the microadenoma location inside the gland and stalk inclination was found. From 21 microprolactinomas with eccentric location, 17 coincided with the sellar floor excavation; eccentric excavation presented significant differences between both groups, but not the central excavation.

CONCLUSION

From all indirect sings of microprolactinoma analyzed in this study, only a gland height over 9 mm, and an eccentric sellar excavation of at least 3 mm are reliable signs to support its diagnosis.

Factors predicting pituitary adenoma invasiveness in acromegalic patients

Forty-four adult acromegalic patients carrying growth hormone-producing pituitary macroadenomas were investigated with neuroradiological and endocrinological techniques. Plasma growth hormone and somatomedin-C levels were repeatedly measured before surgical removal of tumors and during the follow-up period. Twenty-five patients presented preoperatively with an invasive adenoma that involved the cavernous sinus (CS). Diagnosis of tumor invasivity was made according to distinct neuroradiological criteria and was confirmed or rejected during surgery Significantly higher basal growth hormone levels were found in patients with CS invasion than in cases without tumor growth in the CS. Evidence is presented that plasma growth hormone level in acromegalics is a more sensitive indicator for predicting tumor invasiveness than somatomedin-C. Growth hormone basal values before surgery and the extent of their decrease after removal of tumor correlate with adenoma growth in the parasellar compartments and should be used as a prognostic factor to aid in planing adjuvant tumor treatment.

Imaging of pituitary tumours

In the neuroradiological study of pituitary tumours, second generation CT, dynamic CT and MRI provide information about the extent of the tumour and its anatomical relations with the surrounding tissues. Sometimes these techniques can distinguish primary anterior pituitary lesions from primary parasellar lesions with presentations in the sellar region. In general, contrast-enhanced MRI and dynamic CT are more sensitive than conventional CT for the diagnosis of pituitary microadenomas, as well as for the precise delineation of the parasellar invasion of macroadenomas. Radiological techniques usually cannot distinguish clinically non-functioning from functioning pituitary adenomas. BSIPSS is used for confirmation of the diagnosis of Cushing's disease as well as for the lateralization of pituitary microadenomas in Cushing's disease and some other anterior pituitary hyperfunctional states. Neurotransmitter-receptor ligand imaging by SPECT with 123I-IBZM and/or 111In-DTPA-octreotide characterizes the dopamine D2 and somatostatin receptor status of pituitary adenomas, respectively. In selected cases, these techniques may be used for the differential diagnosis of pituitary tumours as well as for the differential diagnosis of primary anterior pituitary lesions and primary parasellar lesions with presentations in the sellar region. If medical therapy of these tumours with receptor agonists is being considered, these techniques can help in selecting the first-line treatment. Furthermore, the effects of medical therapy on the tumour can be evaluated. The introduction of newer and more receptor-specific radioligands may expand the clinical use of these techniques in the future. The availability of PET for the clinical diagnosis of pituitary tumours is still limited, but promising results have been described.

Corticotroph cell hyperplasia in a patient with Addison disease: case report

A woman with Addison disease developed hyperpigmentation, headache, and nausea despite conventional replacement therapy with cortisone. Excessively elevated plasma adrenocorticotropic hormone (ACTH) with absence of response to administration of corticotropin-releasing factor (CRF), and roentgenological evidence of enlargement of the sella turcica, as well as detection of enlarged pituitary gland on magnetic resonance images, led to a diagnosis of ACTH-producing microadenoma, which was removed by transsphenoidal microsurgery. The specimen obtained at surgery evidenced corticotroph hyperplasia, as demonstrated by immunohistochemical staining for ACTH. Fine structure exhibited densely granulated cells with a few bundles of microfilaments and an abundance of large lysosomal bodies. Surgical removal of the hyperplasia alleviated the patient's symptoms, and hyperpigmentation faded remarkably. Her plasma ACTH level returned to normal, has remained normal for more than 3 years, and responds adequately to CRF administration.

The evaluation of patients with a suspected pituitary microadenoma: computer tomography compared to magnetic resonance imaging

OBJECTIVES

To perform a prospective study to compare the ability of magnetic resonance imaging (MRI) and computer assisted tomography (CT) to predict the position of a tumour within the pituitary fossa and to assess the clarity of the image generated by the two modalities in patients with suspected pituitary microadenomas.

DESIGN

Nineteen patients were investigated with CT and MRI scans and underwent trans-sphenoidal exploration of the pituitary fossa. Both scans were assessed blind and independently by three neuroradiologists, A, B, and C; A and B examined the CT scans and B and C the MRI scans. The predicted site was then compared to the size and position of the tumour at surgery.

PATIENTS

Twenty-five patients were recruited and had both CT and MRI scans, 19 subsequently underwent trans-sphenoidal exploration of the pituitary fossa and formed the study population.

RESULTS

The joint opinions of A and B of the CT scans were correct in 10/19, and those of B and C of the MRI scans were correct in 17/19 cases, P = 0.008. Observer agreement was used to assess the clarity of the image. A and B agreed about the site of the tumour on the CT scan in 14 of 19 cases (Kappa statistic 0.556); B and C agreed on the MRI scans in 19/19 cases (Kappa statistic 1), P = 0.025. After the exclusion of five cases found to be macroadenomas at surgery, the joint opinions of A and B of the CT scans were correct in 8/14, and those of B and C of the MRI scans were correct in 12/14 cases, P = 0.133. A and B agreed about the site of the tumour on the CT scan in 12/14 cases (Kappa statistic 0.653), B and C agreed on the MRI scans in 14/14 cases (Kappa statistic 1, no significant difference).

CONCLUSIONS

In the assessment of suspected pituitary microadenomas MRI is the imaging technique of choice in view both of its greater diagnostic accuracy and the avoidance of radiation exposure.

A comparison of CT and MRI in the assessment of the pituitary and parasellar region

We have carried out a prospective study to compare high resolution thin slice, contrast-enhanced, axial computed tomography (CT) with unenhanced magnetic resonance imaging (MRI) at 1.5T in the assessment of the pituitary and parasellar region. Forty patients with suspected pituitary disease presenting to an endocrine unit were studied. MRI was superior to CT for the identification of the posterior pituitary and pituitary stalk and was better at showing the cystic nature of tumours. Visualization of the optic chiasm and assessment of displacement of the optic chiasm and the carotid arteries were also better with MRI. CT was equally good at showing cavernous sinus displacement or invasion, sphenoid sinus invasion and erosion of the floor of the sella turcica and was the only technique able to show calcification of the gland. More focal abnormalities were seen in the pituitary gland with CT than with unenhanced MRI, but there was a higher false positive rate for microadenoma detection with CT. All the scans were interpreted separately by three observers, two radiologists and one clinician. The percentage agreement between the observers for the identification of pituitary and parasellar structures was better for MRI than for CT and the clinician in particular found interpretation of the MR images easier. MRI thus not only gives more information overall than CT but it is a more reliable technique between different observers for the assessment of the pituitary and parasellar region.

Pituitary computed tomography: is contrast enhancement necessary?

Direct coronal computed tomography of the pituitary fossa, before and after enhancement with intravenous contrast medium, was performed on 25 consecutive patients with hyperprolactinaemia. The images were viewed separately by two independent observers and the pituitary height, width and contour, and the visibility of the infundibulum, optic chiasm and hypothalamus were assessed. The presence and size of any possible pituitary tumour was recorded. The administration of intravenous contrast medium made no significant difference to the pituitary measurements, the visibility of the infundibulum of hypothalamus, or the detection of possible pituitary tumours. There was an inconsistent improvement in the visibility of the optic chiasm following enhancement. The arguments against an unenhanced examination are discussed and refuted. It is proposed that routine administration of intravenous contrast medium is unnecessary when investigating moderate hyperprolactinaemia.

Pituitary microadenomas. Does Gadolinium enhance their demonstration?

Ten patients with biochemical evidence of a hormonally active pituitary adenoma were examined by dynamic contrast enhanced computed tomography (CT) and then by pre and post Gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging (MRI). Excluding one false positive case, CT and unenhanced MRI were comparable in the detection of microadenoma. Post Gd-DTPA examination gave more clear evidence of the actual adenoma in two patients and aided in the demonstration of a third. However, in two others all imaging techniques failed to demonstrate the microadenoma subsequently found at surgery. On the post enhancement MRI it was easier to assess the relationship of a tumour to the cavernous sinus and to visualise the relationships of the parasellar carotid arteries.

Surgery of adrenal disorders

The surgical management of patients with adrenal disease depends on the functional nature of the endocrinopathy. It requires a thorough knowledge of adrenal anatomy and command of the various surgical approaches to the gland. Included for discussion are Cushing's syndrome, adrenal adenoma and adenocarcinoma, adrenocortical carcinoma, primary aldosteronism, and pheochromocytoma.