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

An audit of the use of CT pituitary scans to exclude a pituitary macroadenoma

BACKGROUND

Pituitary imaging is often required to exclude an adenoma suspected clinically or biochemically. Although magnetic resonance (MR) is the gold standard, computerised tomography (CT) is faster, cheaper and induces less claustrophobia. Our audit at Auckland City Hospital, New Zealand, investigated whether the use of CT of the pituitary as the first line imaging to assess for a pituitary macroadenoma reduces the need for MR.

METHODS

We investigated the usefulness of CT pituitary imaging in the exclusion of pituitary macroadenoma between 2012 and 2020. A re-audit was then undertaken for a period of one year between March 2021 and March 2022 to assess outcomes once a departmental policy change was implemented. At Auckland City Hospital, 32 patients across eight years were eligible for this analysis, of which 31 had data available. In our re-audit, 29 patients were eligible for this analysis. We collected data on patient demographics, relevant hormone levels, indication for imaging and imaging results and subsequent management.

RESULTS

After CT pituitary imaging, 28/31 (90%) of patients did not require further imaging because the clinical question had been addressed. One year after routine initial CT pituitary imaging was implemented by the Auckland City Hospital Endocrinology Department, 29 CT pituitary scans were performed to exclude a pituitary macroadenoma. Of these patients one required further imaging due to the finding of an expanded pituitary sella but not a pituitary macroadenoma.

CONCLUSION

CT pituitary imaging to exclude a pituitary macroadenoma is a useful test that may reduce the need for MR pituitary scans.

TRIAL REGISTRATION

Not applicable. This was an audit as defined by the New Zealand National Ethics Advisory Committee guidelines. Please see 'Declarations' section.

Pituitary apoplexy as a mimicker of infectious meningitis in an adolescent female patient

Pituitary apoplexy can cause a chemical meningitis and its mimicry in presentation with infectious meningitis poses a diagnostic challenge. Here we report an 18-year-old woman who presented with acute headache, altered mental status, and cerebral spinal fluid (CSF) pleocytosis, and clinically improved with antibiotics and steroids. Despite an unremarkable head computed tomography scan, brain magnetic resonance imaging showed a pituitary macroadenoma with apoplexy. This is one of the first reports of an adolescent with pituitary apoplexy masquerading as infectious meningitis and underscores the importance of keeping this rare condition, often missed on CT scans, on the differential for CSF pleocytosis.

Guidelines in the management of CNS tumors

INTRODUCTION

Evidence-based, clinical practice guidelines in the management of central nervous system tumors (CNS) continue to be developed and updated through the work of the Joint Section on Tumors of the Congress of Neurological Surgeons (CNS) and the American Association of Neurological Surgeons (AANS).

METHODS

The guidelines are created using the most current and clinically relevant evidence using systematic methodologies, which classify available data and provide recommendations for clinical practice.

CONCLUSION

This update summarizes the Tumor Section Guidelines developed over the last five years for non-functioning pituitary adenomas, low grade gliomas, vestibular schwannomas, and metastatic brain tumors.

Using magnetic resonance imaging to measure the depth of acupotomy points in the lumbar spine: A retrospective study

Background

The acupotomy is an acupuncture device recently used to stimulate lumbar vertebrae such as transverse processes (TPs) and facet joints (FJs). However, there are many organs, nerves, and blood vessels, which can lead to side effects if the needle misses the treatment target. Therefore, information regarding appropriate insertion depths, which is currently lacking, could facilitate its safe use. We retrospectively investigated the depth from the skin to the TP and FJ of the lumbar vertebrae, using magnetic resonance imaging (MRI).

Methods

This retrospective chart review was conducted at a single medical centre in Korea. From 55,129 patient records, 158 subjects were selected. Perpendicular depth from the skin to the left and right TPs and FJs was measured using T1-weighted sagittal plane MRI. Depth differences between the left and right sides were evaluated using the paired t-test and analysis of covariance (body mass index [BMI] as a covariate). The influence of BMI on depth at each location was evaluated by simple linear regression analysis.

Results

The mean age was 43.2 years and mean BMI was 23.6 kg/m². The depth from skin to the TPs or FJs was unaffected by age, sex, or side. Mean depths (cm) were as follows: (TPs) L1 = 4.5, L2 = 4.9, L3 = 5.3, L4 = 5.7, L5 = 5.9; (FJs) L12 = 3.8, L23 = 4.0, L34 = 4.4, L45 = 4.6, L5S1 = 4.6. Depth was highly correlated with BMI at each location.

Conclusion

The depth of TPs and FJs adjusted for BMI can safely and effectively be used for treatment via various invasive interventions, including acupotomy treatment, in the lumbar region.

The combined use of EphA2/MMP-2 expression and MRI findings contributes to the determination of cerebral glioma grade

Glioma is the most aggressive brain tumor and is associated with a high mortality rate. The aim of the present study was to explore the association between matrix metalloproteinase 2 (MMP-2) and ephrin type-A receptor 2 (EphA2) expression in glioma cells, and to investigate the contribution of magnetic resonance imaging (MRI) in glioma classification. A total of 43 patients with pathologically confirmed glioma were divided into two groups as follows: Low-grade (grades I and II; n=21) and high-grade (grades IV and IV; n=22). Subsequently, immunohistochemistry staining was performed to detect the expression levels of MMP-2 and EphA2 in the low- and high-grade groups. MRI routine and enhanced scans were used to measure the peritumoral edema index (EI), tumor enhancement percentage (EP) and maximum tumor diameter. The results demonstrated that the proportion of MMP-2-positive patients in the high-grade group was 86.36% (19/22), which was significantly higher than that of the low-grade group (57.14%; 12/21) (P<0.05). Furthermore, the proportion of EphA2-positive patients in the high-grade group was 90.91% (20/22), significantly higher than that in the low-grade group (4.76%; 1/21) (P<0.01). In addition, the MRI results indicated that the EI, EP and maximum tumor diameter were significantly higher in the high-grade group compared with the low-grade group (P<0.01, P<0.01 and P<0.05, respectively). Finally, the expression levels of MMP-2 and EphA2 were significantly associated with the EI, EP and maximum tumor diameter (all P<0.05). In conclusion, the expression levels of MMP-2 and EphA2 were positively correlated with glioma invasion. The correlation between these expression levels and MRI assessment of the EI, EP and maximum tumor diameter indicated that the combination of these two methods may be used for the evaluation of the tumor grade and for further clinical treatment applications.

Clinical 7 T MRI: Are we there yet? A review about magnetic resonance imaging at ultra-high field

In recent years, ultra-high field MRI (7 T and above) has received more interest for clinical imaging. Indeed, a number of studies have shown the benefits from the application of this powerful tool not only for research purposes, but also in realms of improved diagnostics and patient management. The increased signal-to-noise ratio and higher spatial resolution compared with conventional and high-field clinical scanners allow imaging of small anatomical detail and subtle pathological findings. Furthermore, greater spectral resolution achieved at ultra-high field allows the resolution of metabolites for MR spectroscopic imaging. All these advantages have a significant impact on many neurological diseases, including multiple sclerosis, cerebrovascular disease, brain tumors, epilepsy and neurodegenerative diseases, in part because the pathology can be subtle and lesions small in these diseases, therefore having higher signal and resolution will help lesion detection. In this review, we discuss the main clinical neurological applications and some technical challenges which remain with ultra-high field MRI.

Measurement of the normal feline pituitary gland in brachycephalic and mesocephalic cats

Objectives The purpose of this study was to determine differences in normal feline pituitary dimensions in brachycephalic and mesocephalic cats as a basis for establishing cryohypophysectomy in cats. Methods Measurements were performed on sagittal T2-weighted and transverse post-gadolinium T1-weighted or T1 3D fast field echo-weighted MRI images. A total of 32 brachycephalic and 27 mesocephalic cats were examined. Inter-observer reproducibility was assessed by t-test and Bland-Altman analysis. Results The cats were 0.6-15.9 years of age with a body weight range of 1.84-6.60 kg. For brachycephalic cats, the mean pituitary gland sagittal height was 2.15 ± 0.15 mm, pituitary gland transverse height was 2.42 ± 0.21 mm, pituitary gland transverse width was 4.44 ± 0.27 mm and pituitary gland sagittal length was 3.14 ± 0.30 mm. In mesocephalic cats, the pituitary gland dimensions were 2.94 ± 0.16 mm, 3.09 ± 0.26 mm, 4.73 ± 0.31 mm and 4.88 ± 0.30 mm for pituitary gland sagittal height, transverse height, transverse width and sagittal length, respectively. There was a highly significant correlation between brachycephalic and mesocephalic cats and pituitary gland height and length ( P <0.0001), respectively. Sex also had an effect on pituitary gland measurements. Neutering status had no significant effect on hypophyseal measurements. Age had a significant influence on pituitary gland height, width and length in the brachycephalic population. Inter-observer reproducibility was good to excellent. Conclusions and relevance The different pituitary measurements in brachycephalic and mesocephalic cats has to be considered if surgery comes into question. There are ranges in pituitary gland sizes, even among the mesocephalic cat population. Thus, exact measuring of the pituitary gland is crucial before any surgical intervention.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Preoperative Imaging Assessment of Patients With Suspected Nonfunctioning Pituitary Adenomas

BACKGROUND

The authors reviewed published articles pertaining to the preoperative imaging evaluation of nonfunctioning pituitary adenomas (NFPAs) and formulated recommendations.

OBJECTIVE

To provide an exhaustive review of published articles pertaining to the preoperative imaging evaluation of nonfunctioning pituitary adenomas.

METHODS

The MEDLINE database was queried for studies investigating imaging for the preoperative evaluation of pituitary adenomas.

RESULTS

From an initial search of 5598 articles, 122 articles were evaluated in detail and included in this article. Based on analysis of these articles, the recommendations are as follows: (1) High-resolution magnetic resonance imaging (level II) is recommended as the standard for preoperative assessment of nonfunctioning pituitary adenomas, but may be supplemented with CT (level III) and fluoroscopy (level III). (2) Although there are promising results suggesting the utility of magnetic resonance spectroscopy, magnetic resonance perfusion, positron emission tomography, and single-photon emission computed tomography, there is insufficient evidence to make formal recommendations pertaining to their clinical applications.

CONCLUSION

The authors identified 122 articles that form the basis of recommendations for preoperative imaging evaluation of nonfunctioning pituitary adenomas. The full guidelines document for this chapter can be located at https://www.cns.org/guidelines/guidelines-management-patients-non-functioning-pituitary-adenomas/Chapter_2.

ABBREVIATIONS

CT, computed tomographyDWI, diffusion-weighted imagingMRI, magnetic resonance imagingNFPA, nonfunctioning pituitary adenoma.

Pituitary Microadenoma

Twenty surgically proven pituitary microadenomas were examined with MR imaging and CT. MR demonstrated 20 of 20 microadenomas: 90% of the tumors were hypointense on T1-weighted images before Gd-DTPA administration and in 45% the tumors were more clearly delineated postcontrast. CT demonstrated 19 of 20 diagnosed microadenomas: showing low attenuation in 85% of the tumors precontrast. Iohexol facilitated delineation of the tumors in 45%. Focal enlargement of the gland and diaphragma sellae convexity were more useful than infundibular tilting and sellar—floor erosion as ancillary findings supporting the diagnosis. In general, CT and MR agreed regarding the microadenomas' size and location, measurement of enlarged intrasellar contents, detection of the diaphragma sellae bulge, and demonstration of infundibulum abnormality. CT was more sensitive than MR in identifying sellar—floor erosion. We suggest that CT be the first method for demonstration of microadenomas.

High resolution pituitary gland MRI at 7.0 tesla: a clinical evaluation in Cushing's disease

Objective

To evaluate the detection of pituitary lesions at 7.0 T compared to 1.5 T MRI in 16 patients with clinically and biochemically proven Cushing’s disease.

Methods

In seven patients, no lesion was detected on the initial 1.5 T MRI, and in nine patients it was uncertain whether there was a lesion. Firstly, two readers assessed both 1.5 T and 7.0 T MRI examinations unpaired in a random order for the presence of lesions. Consensus reading with a third neuroradiologist was used to define final lesions in all MRIs. Secondly, surgical outcome was evaluated. A comparison was made between the lesions visualized with MRI and the lesions found during surgery in 9/16 patients.

Results

The interobserver agreement for lesion detection was good at 1.5 T MRI (κ = 0.69) and 7.0 T MRI (κ = 0.62). In five patients, both the 1.5 T and 7.0 T MRI enabled visualization of a lesion on the correct side of the pituitary gland. In three patients, 7.0 T MRI detected a lesion on the correct side of the pituitary gland, while no lesion was visible at 1.5 T MRI.

Conclusion

The interobserver agreement of image assessment for 7.0 T MRI in patients with Cushing’s disease was good, and lesions were detected more accurately with 7.0 T MRI.

Key Points

• Interobserver agreement for lesion detection on 1.5 T MRI was good;

• Interobserver agreement for lesion detection on 7.0 T MRI was good;

• 7.0 T enabled confirmation of unclear lesions at 1.5 T;

• 7.0 T enabled visualization of lesions not visible at 1.5 T.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-015-3809-x) contains supplementary material, which is available to authorized users.

Predictors of endoscopic transsphenoidal surgery outcome in acromegaly: patient and tumor characteristics evaluated by magnetic resonance imaging

The availability of various first-line treatment modalities for acromegaly and evolving surgical techniques emphasize the need for accurately defined predictors of surgical outcome. We retrospectively analysed the outcome of 30 patients with acromegaly after initial endoscopic transsphenoidal surgery in two university hospitals from 2001 until 2009, and reviewed comparable literature investigating predictive tumor characteristics. Medical records were monitored for patient characteristics. Each pituitary magnetic resonance imaging (MRI) scan was revised independently by two neuroradiologists using a standardised analysis form to record distinctive predefined tumor characteristics. All characteristics were independently analysed as predictors for persistent disease, and a multivariable predictive model was created. Literature from 2000 onwards was searched for studies describing tumor characteristics predictive for surgical outcome. The cohort consisted of 27 macroadenomas with 90 % demonstrating signs of parasellar extension. The surgical cure rate overall was 30 %. Independently, next to male sex and increasing tumor size, infrasellar and parasellar extension based on MRI staging tended to increase the risk of persistent disease. In a multivariable analysis, sex and parasellar extension of the tumor were demonstrated to be the variables allowing for the best fitted predictive model for persistent disease. Earlier studies on preoperative tumor characteristics showed comparable results, although these were based on several different tumor classification systems. This retrospective study demonstrates that accurately defined tumor characteristics based on imaging, especially for cavernous sinus invasion, can be helpful in predicting surgical outcome. Comparative studies on different treatment modalities are essential for clinical practice within the scope of re-evaluation of the role of surgery in GH-secreting adenomas.

The new proposed magnetic resonance areas of the cavernous sinus and their relation to the neurosurgical triangles

MRI appears to be the best contemporary method with which to evaluate cavernous sinus anatomy. Based on anatomic landmarks that are easily detectable in the standard MRI examination, the cavernous sinus is divided into six areas. Each of the newly defined areas corresponds to the previously described neuroanatomic triangles. Evaluation of the newly defined areas in a plane perpendicular to these triangles on a MRI scan permits expansion of these two-dimensional areas into three-dimensional spaces; thus, the neurosurgical approach can be observed and their anatomic and pathologic content examined. Radiologic and surgical evaluation of the cavernous sinus is presented.

Computed tomography and low-field magnetic resonance imaging of the pituitary gland in dogs with pituitary-dependent hyperadrenocorticism: 11 cases (2001-2003)

OBJECTIVE

To compare the results of computed tomography (CT) and magnetic resonance imaging (MRI) of the pituitary gland in dogs with pituitary-dependent hyperadrenocorticism (PDH) caused by histologically confirmed pituitary adenoma.

DESIGN

Retrospective case series.

ANIMALS

11 dogs with PDH that underwent transsphenoidal hypophysectomy.

PROCEDURES

Medical records of dogs examined between January 2001 and March 2003 were reviewed. Dogs were included in this study if they had clinical signs of hypercortisolism at the time of admission (for which PDH was diagnosed) and underwent transsphenoidal hypophysectomy. Pre- and postcontrast CT and low-field MRI (0.2-Tesla magnet) were performed on the same day as surgery for each dog.

RESULTS

An abnormal pituitary gland was found in 7 dogs by use of MRI and in the same 7 dogs by use of CT. Significant differences were found between postcontrast CT and MR images for height, width, and length of the pituitary gland; brain area; and thickness of the sphenoid bone. However, the pituitary gland height-to-brain area ratio determined from postcontrast CT and MR images was not significantly different. The signal-to-noise ratio and contrast-to-noise ratio of pre- and postcontrast MR images were significantly higher than those of the CT images.

CONCLUSIONS AND CLINICAL RELEVANCE

Low-field MRI and dynamic CT imaging of the pituitary gland provided comparable information on the presence of pituitary adenomas in dogs with PDH.

In vivo 3D analysis of the adipose tissue in the orbital apex and the compartments of the parasellar region

As tissue dissections carried out on formaldehyde-fixed anatomical specimens demonstrate, the parasellar region (PSR), traditionally referred to as the cavernous sinus, is composed of three distinct compartments: orbital, pterygopalatine, and lateral sellar. The aim of our study was to identify and measure these compartments in the living and to describe the topography of their adipose body tissues. For this purpose data sets of 35 patients, who had undergone thin-section multislice computed tomography (CT), were examined using 3D-reconstruction software. The pterygopalatine and orbital compartments of the PSR could be identified in the images by their adipose bodies. We provide more exacting measurements of their size than have been presented in earlier studies. Furthermore, we include data about the uni- and bilateral presence of the single compartments and analyze the topography of the adipose tissue bodies in the orbital apex region. Our quantitative data and topographical descriptions confirm the compartmentalization concept of the PSR, allow for correct interpretation of CT scans of the orbital apex and anterior PSR, and provide baseline information for individual planning of surgical and radiological interventions.

MRI evaluation of the diaphragmal opening: using MRI parallel to the transsphenoidal surgical approach

Twenty-six adult diaphragma sellae and infundibulae were examined by MRI parallel to the transsphenonidal surgical plane with attention given to the diaphragmal opening. The diaphragmal opening was observed in 11 cases (42.3%). The anteroposterior diame ter of the opening ranged from 4.0 to 14.0 mm (mean 8.8 mm), and the lateral diameter ranged from 6.0 to 14.0 mm (mean 9.5 mm). In the cases of open diaphragma sellae, the infundibulum tended to be located in the posterior part of the diaphragma sellae but this was not statisticallysignificant. On MRI parallel to the transsphenoidal surgical approach, the anatomy of the dia phragma sellae was well evaluated.

Dynamic magnetic resonance imaging of the normal canine pituitary gland

The pituitary glands of six normal dogs were evaluated using dynamic magnetic resonance imaging. T1 weighted images were obtained every 13 seconds for three minutes of three contiguous slices through the pituitary gland following a bolus intravenous injection of gadolinium-DTPA. Contrast enhancement was seen initially in the region of the pituitary stalk at 52-65 seconds followed by uniform enhancement at 104-143 seconds post injection. This pattern of enhancement was seen in all subjects and is similar to that reported in humans.

Posterior pituitary ectopia and hypopituitarism--magnetic resonance appearances of four cases and a review of the literature

In four patients presenting in childhood with varying degrees of hypopituitarism, magnetic resonance imaging (MRI) showed a reduction in size of the normal pituitary fossa contents and an absent or very narrow stalk. A high signal intensity, enhancing area at the base of the stalk, having the appearances and signal characteristics of the posterior pituitary, was seen in each case. We discuss the case histories and MR findings in our patients and review the relevant literature.

Intracranial arterial calcification and ectasia in visual failure

Calcification of the major intracranial arteries is frequently observed on computed tomography (CT), particularly in the carotid siphon, and has been implicated as a causative factor in low tension glaucoma. Ectasia of the carotid siphon has also been postulated as a possible cause of compressive optic neuropathy. 153 patients, in whom high resolution CT of the orbits and parasellar region had been performed for suspected anterior visual pathway pathology, were retrospectively reviewed. The presence and severity of calcification and ectasia of the major intracranial arteries was recorded. There was a high occurrence of carotid siphon calcification, increasing with age, and independent of sex or race. Calcification was very rare in anterior cerebral, middle cerebral and basilar arteries in all age groups. The amount and degree of ectasia also increased with advancing age, and was more frequently observed in carotid and basilar than anterior and middle cerebral arteries. There was no correlation between the degree of calcification or ectasia and ophthalmological or neurological deficit.

Visual loss following treatment of sphenoid sinus carcinoma

A 71-year-old woman developed complete third nerve palsy and total blindness of the right eye one month after completing a course of radiotherapy for sphenoid sinus carcinoma over a 13-month period. Differential diagnosis included recurrence of the tumor, radiation-induced second neoplasm, empty sella with chiasmal prolapse and secondary chiasmal arachnoid adhesions, and radionecrosis. Magnetic resonance imaging demonstrated gadolinium contrast enhancement of the right intracranial optic nerve and chiasm, suggesting a radionecrosis process.

Imaging in endocrinology: use of a potential methodology for audit consensus development

OBJECTIVE

To explore areas of consensus in the use of imaging techniques in the investigation of endocrine disorders.

DESIGN

A postal questionnaire sent to members of the Endocrine Section of the Royal Society of Medicine following a meeting of the Section in January 1993 on Imaging in Endocrinology.

SUBJECTS

Fifty-two specialists completed the questionnaire which was sent in the first mailing after the meeting.

MEASUREMENTS

Consensus statements were defined as those in which greater than 75% of respondents either agreed or opposed the statement. Majority support or rejection was defined as greater than 50% in favour with less than 25% opposed or vice versa.

RESULTS

Many areas of consensus were defined particularly in the field of the use of imaging in the investigation of pituitary disease. The questionnaire highlighted difficulties in obtaining a consensus view on the imaging techniques which should be employed in the investigation of thyroid, parathyroid and pancreatic disorders.

CONCLUSION

The results are a useful guide to areas in which further discussion and/or research is required. This methodology could, and we believe should, be applied to other areas of endocrine practice. Such results provide an initial data base to develop national audit guide-lines on the use of imaging techniques in endocrine disorders.

Multiple pituitary hormone deficiencies in a patient with spinocerebellar ataxia: magnetic resonance imaging and hormonal studies

Degenerative spinocerebellar ataxia has a rare association with hypogonadotropic hypogonadism. In this report we present the results of the detailed endocrine evaluation and magnetic resonance imaging in one such patient. A 20-year-old male with progressive cerebellar ataxia, hypogonadism, and short stature was investigated. Basal testing revealed hypogonadotropic hypogonadism (LH < 5 mU/L, FSH < 5 mU/L, testosterone 2.5 nM/L). There was no rise in LH after stimulation with LHRH, peak LH level being < 5 mU/L. Insulin hypoglycemia testing was consistent with GH deficiency, with peak GH being 3.2 mU/L. On TRH stimulation, there was no significant rise in prolactin, though the TSH response was normal. Magnetic resonance imaging revealed cerebellar atrophy. The anterior pituitary was atrophic, with a height of 1.4 mm. The posterior pituitary and the pituitary stalk were normal in size and position. This patient with degenerative spinocerebellar ataxia had multiple pituitary hormone deficiencies. The results of our endocrine evaluation and MR imaging lead us to believe that these deficits may result from a lesion at the level of the pituitary gland.

Suprasellar masses: diagnosis and differential diagnosis

Suprasellar masses are neoplastic, vascular, congenital, or infectious/inflammatory in origin. Magnetic resonance imaging (MRI) is the study of choice for evaluating suprasellar masses, although computed tomography (CT) may provide complementary information. Suprasellar masses present with a variety of neurologic or endocrine dysfunctions depending on their site of origin and mass effect on adjacent structures. Imaging characteristics of the most common suprasellar lesions are described with particular emphasis on MR findings.

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.