Comparison of growth hormone-producing and non-growth hormone-producing pituitary adenomas: imaging characteristics and pathologic correlation

Magnetic resonance imaging in the management of prolactinomas; a review of the evidence

PURPOSE

This review aimed to evaluate data on the use of magnetic resonance imaging in the management of prolactinomas.

METHODS

Recent literature about prolactinoma behavior and magnetic resonance imaging in the management of prolactinomas is reviewed.

RESULTS

A review of evidence regarding prolactinoma pituitary MRI follow-up; techniques and sequences, recent data on possible gadolinium retention, the role and a review of T2-weighted images in the identification of prolactinomas and frequently encountered clinical scenarios, as well as MRI correlation with prolactin secretion, tumor growth and prediction of response to medical therapy are presented.

CONCLUSION

The underlying decision to perform serial imaging in prolactinoma patients should be individualized on a case-by-case basis. Future studies should focus on alternative imaging methods and/or contract agents.

The Clinicopathological Spectrum of Acromegaly

BACKGROUND

Acromegaly results from a persistent excess in growth hormone with clinical features that may be subtle or severe. The most common cause of acromegaly is a pituitary tumor that causes excessive production of growth hormone (GH), and rare cases are due to an excess of the GH-releasing hormone (GHRH) or the ectopic production of GH.

OBJECTIVE

Discuss the different diseases that present with manifestations of GH excess and clinical acromegaly, emphasizing the distinct clinical and radiological characteristics of the different pathological entities.

METHODS

We performed a narrative review of the published clinicopathological information about acromegaly. An English-language search for relevant studies was conducted on PubMed from inception to 1 August 2019. The reference lists of relevant studies were also reviewed.

RESULTS

Pituitary tumors that cause GH excess have several variants, including pure somatotroph tumors that can be densely or sparsely granulated, or plurihormonal tumors that include mammosomatotroph, mixed somatotroph-lactotroph tumors and mature plurihomonal Pit1-lineage tumors, acidophil stem cell tumors and poorly-differentiated Pit1-lineage tumors. Each tumor type has a distinct pathophysiology, resulting in variations in clinical manifestations, imaging and responses to therapies.

CONCLUSION

Detailed clinicopathological information will be useful in the era of precision medicine, in which physicians tailor the correct treatment modality to each patient.

Pituitary magnetic resonance imaging predictive role in the therapeutic response of growth hormone-secreting pituitary adenomas

Background

Growth hormone (GH)-secreting pituitary adenomas, responsible for the development of acromegaly, are the second most frequent type of secreting pituitary adenomas and are characterized by very variable T2-weighted signal intensity on pituitary magnetic resonance imaging (MRI). Previous data have demonstrated a correlation between T2-weighted tumor signal intensity and response to therapy with conventional somatostatin analogs (SSA) in patients with acromegaly. The aim of the current retrospective study was to investigate the correlation between the T2-weighted tumor signal on pituitary MRI and both biochemical and radiological response to first-line SSA therapy.

Methods

Twenty-two naive patients with acromegaly were eligible for the study (14 females and 8 males, mean age ± SD: 58.8±15.74). A biochemical evaluation (GH and IGF-I levels) and an MRI assessment (volume and signal intensity analysis of adenoma) were conducted in each patient at diagnosis and after 12 months of SSA therapy.

Results

On diagnostic pituitary MRI, 16 (72.7%) adenomas were T2- hypointense and 6 (27.2%) T2-hyperintense. After 12 months of SSA therapy, IGF-I levels decreased by more than 50% from baseline in 62.5% of patients with T2-hypointense and 33.3% of patients with T2- hyperintense tumor signal, respectively (P=0.03). Moreover, GH levels decreased by more than 80% from baseline in 81.3% and 33.3% of patients with T2-hypointense and T2-hyperintense tumor signal (P=0.02). A significant tumor volume reduction (≥20%) was observed in 75% of the T2-hypointense and 33.3% of the T2-hyperintense adenomas (P=0.001).

Conclusions

In naive patients with acromegaly, first-line SSA therapy is associated with a better biochemical response and greater tumor shrinkage in T2-hypointense compared to T2-hyperintense adenomas. Therefore, T2-weighted sequences of pituitary MRI can help to classify GH-secreting pituitary adenomas into a T2-hypointense and T2-hyperintense type and, therefore, to identify patients who can better respond to first-line SSA therapy.

The Utility of Using Preoperative MRI as a Predictor for Intraoperative Pituitary Adenoma Consistency and Surgical Resection Technique

Objective  Most pituitary adenomas are of soft consistency and can be resected during surgery with routine suction instruments. However, fibrous adenomas may require more aggressive techniques. The ability to predict consistency on magnetic resonance imaging (MRI) would improve preoperative preparation and may have implications on the extent of resection. Design  A retrospective review of MRI and tumor histology of 50 consecutive patients who underwent endoscopic endonasal resection for nonfunctional adenomas was performed. Methods  An intensity ratio was calculated based on quantitative MRI signal intensity of the adenoma and pons. Intraoperatively, a sequentially graded technique required for resection ranged from suction (R1) for softer tumors, curettes (R2) for tumors with intermediate consistency, and aspirators and/or other microinstruments (R3) for firmer tumors. Fibrotic content was determined from histologic collagen percentage, and rates of gross total resection (GTR) were calculated from postoperative imaging. Statistical analyses were performed to determine if resection classification could be predicted by intensity ratio or collagen percentage, calculate ratio of cut-off points for clinical use, and assess for correlation between intensity ratios and collagen percentage. Results  Tumors with ratios < 1.6 on the T2-weighted coronal image and collagen content > 5.3% were likely to have required a more aggressive resection technique. Statistically significant lower rates of GTR and higher rates of perioperative complications were seen with such tumors. Conclusion  Preoperative MRI analyses can be helpful but not definitive in predicting adenoma consistency. Fibrous adenomas, associated with higher collagen content, are more difficult to resect and have higher rates of subtotal resection.

Clinical Characteristics of Acromegalic Patients With Paradoxical GH Response to Oral Glucose Load

CONTEXT

A paradoxical GH response to oral glucose (OG) is often found in acromegaly. However, the clinical characteristics of patients with acromegaly and a paradoxical GH response to OG (OG responders) remain unclear.

OBJECTIVE

The aim of the present study was to define the clinical characteristics of OG responders with acromegaly.

DESIGN

Retrospective study.

SETTING

Hospitalized care at Osaka University Hospital.

PATIENTS AND METHODS

Of 63 patients with acromegaly admitted to our hospital from January 2006 to January 2017, 19 were classified as OG responders and 44 as nonresponders. The clinical characteristics of these groups were compared.

RESULTS

Before surgery, OG responders had substantially greater IGF-1 SD scores than nonresponders (P < 0.05), although no difference was found in basal GH levels between the two groups (P = 0.46). Regarding glucose metabolism, 120-minute plasma glucose and immunoreactive insulin after OG administration and hemoglobin A1c were significantly greater in OG responders than in nonresponders (P < 0.01, P < 0.05, P < 0.05, respectively). GH levels during octreotide or bromocriptine testing were decreased more significantly in OG responders than in nonresponders (P < 0.05, P < 0.05, respectively). The proportion of pituitary tumors with hypointensity on T2-weighted MRI was significantly greater in OG responders than in nonresponders (P < 0.05). The difference in IGF-1 and parameters of glucose metabolism described disappeared between the two groups after surgery.

CONCLUSIONS

The paradoxical GH response reflected the clinical characteristics, especially IGF-I level, glucose metabolism, and drug efficacy in acromegaly. A paradoxical GH response, in addition to the nadir GH levels, to OG load is potentially useful for evaluation of the clinical characteristics of acromegaly.

Preoperative evaluation of tumour consistency in pituitary macroadenomas: a machine learning-based histogram analysis on conventional T2-weighted MRI

PURPOSE

To evaluate the potential value of machine learning (ML)-based histogram analysis (or first-order texture analysis) on T2-weighted magnetic resonance imaging (MRI) for predicting consistency of pituitary macroadenomas (PMA) and to compare it with that of signal intensity ratio (SIR) evaluation.

METHODS

Fifty-five patients with 13 hard and 42 soft PMAs were included in this retrospective study. Histogram features were extracted from coronal T2-weighted original, filtered and transformed MRI images by manual segmentation. To achieve balanced classes (38 hard vs 42 soft), multiple samples were obtained from different slices of the PMAs with hard consistency. Dimension reduction was done with reproducibility analysis, collinearity analysis and feature selection. ML classifier was artificial neural network (ANN). Reference standard for the classifications was based on surgical and histopathological findings. Predictive performance of histogram analysis was compared with that of SIR evaluation. The main metric for comparisons was the area under the receiver operating characteristic curve (AUC).

RESULTS

Only 137 of 162 features had excellent reproducibility. Collinearity analysis yielded 20 features. Feature selection algorithm provided six texture features. For histogram analysis, the ANN correctly classified 72.5% of the PMAs regarding consistency with an AUC value of 0.710. For SIR evaluation, accuracy and AUC values were 74.5% and 0.551, respectively. Considering AUC values, ML-based histogram analysis performed better than SIR evaluation (z = 2.312, p = 0.021).

CONCLUSION

ML-based T2-weighted MRI histogram analysis might be a useful technique in predicting the consistency of PMAs, with a better predictive performance than that of SIR evaluation.

T2-weighted magnetic resonance imaging characterization of prolactinomas and association with their response to dopamine agonists

PURPOSE

Recent work supports the use of T2-weighted MRI intensity as a tool for treatment stratification in acromegaly. Our study aimed to establish if the pattern of T2 intensity could be a predictor of hormonal and/or tumoral response to dopamine agonists (DAs) in prolactinomas.

METHODS

This was a retrospective study performed in two academic centers. We characterized the magnetic resonance T2-weighted aspect of prolactinomas (signal intensity and homogeneity in the whole tumors) before DA therapy and correlated this pattern to the prolactin (PRL) concentration at diagnosis and to hormonal and tumoral responses after 1 year of medical treatment. We separately analyzed a subgroup of prolactinomas visually very bright in more than 50% of the surface ("cystic" tumors).

RESULTS

Out of 70 prolactinomas, 80% were T2 hyperintense and 40% were heterogeneous. At diagnosis, heterogeneous prolactinomas were more frequent in men (68% vs. 28.9%, p ≤ 0.011), larger (median area 304.5 mm² vs. 56.5 mm², p ≤ 0.021), taller (mean height 18.6 mm vs. 9.9 mm, p < 0.001), more secreting (median PRL ULN_area 23 µg/L/cm² vs. 12.6 µg/L/cm², p ≤ 0.032) and had poorer hormonal response to DA as compared with homogeneous prolactinomas. "Cystic" tumors were diagnosed almost exclusively in women and secreted less prolactin, but showed similar hormonal and tumoral response as "non-cystic" tumors. In homogeneous prolactinomas, the T2-weighted intensity ratio was correlated to prolactin secretion, although not significantly, and did not predict hormonal and tumoral response to DA.

CONCLUSIONS

Our study confirms that hypo/isointense prolactinoma is a rare finding and suggests for the first time that the heterogeneity of prolactinoma T2 signal at diagnosis might be correlated with a different clinical behavior and could be used as a negative predictor factor of hormonal response to DA.

International Union of Basic and Clinical Pharmacology. CV. Somatostatin Receptors: Structure, Function, Ligands, and New Nomenclature

Somatostatin, also known as somatotropin-release inhibitory factor, is a cyclopeptide that exerts potent inhibitory actions on hormone secretion and neuronal excitability. Its physiologic functions are mediated by five G protein-coupled receptors (GPCRs) called somatostatin receptor (SST)1-5. These five receptors share common structural features and signaling mechanisms but differ in their cellular and subcellular localization and mode of regulation. SST₂ and SST₅ receptors have evolved as primary targets for pharmacological treatment of pituitary adenomas and neuroendocrine tumors. In addition, SST₂ is a prototypical GPCR for the development of peptide-based radiopharmaceuticals for diagnostic and therapeutic interventions. This review article summarizes findings published in the last 25 years on the physiology, pharmacology, and clinical applications related to SSTs. We also discuss potential future developments and propose a new nomenclature.

MRI criteria of subtypes of adenomas and epithelial cysts of the pituitary gland

This study aimed to assess the clinical applicability of MRI criteria for differentiation of pituitary adenomas and cystic pituitary lesions. One hundred ninety-eight consecutive patients with surgical resection of a pituitary adenoma/cystic pituitary lesion were retrospectively analyzed, blinded to clinical data and histopathological diagnosis. Different morphologic criteria were assessed: signal intensity in T2/T1w images, pattern of contrast enhancement, size, super-/infrasellar extension, and invasion of the cavernous sinus. For validation of the criteria, a second independent patient cohort (n = 102) was analyzed for diagnostic accuracy of the criteria. We identified differences between subtypes of pituitary adenomas regarding morphological MRI criteria. Especially, ACTH-producing adenomas and GH-producing adenomas showed partially specific imaging features. Application of our criteria on the second patient cohort (n = 102) did however not significantly improve diagnostic accuracy. Only differentiation between cystic pituitary lesions and adenomas was facilitated using these criteria, but did not reach statistical significance in this cohort (P = 0.352). MRI criteria might facilitate differentiation between pituitary adenomas and cystic pituitary lesions, but not between subtypes of pituitary adenomas. These subtypes show partially specific MR imaging features, however, due to a high variability knowledge of clinical symptoms and laboratory findings remain essential for the correct diagnosis.

Tumor to Cerebellar Peduncle T2-Weighted Imaging Intensity Ratio Fails to Predict Pituitary Adenoma Consistency

Object  The consistency of pituitary macroadenomas affects the complexity of surgical resection. On T2-weighted (T2W) imaging, the intensity ratio of the tumor to the cerebellar peduncle (tumor to cerebellar peduncle T2-weighted imaging intensity [TCTI] ratio) correlates with meningioma consistency. We aimed to determine the correlation of this radiographic finding with pituitary macroadenoma consistency and to determine whether it can be used for preoperative planning. Methods  We performed a retrospective evaluation of 196 patients with macroadenomas who underwent endoscopic transsphenoidal resection from January 2012 to June 2017. Macroadenoma consistency was determined by one senior neurosurgeon at the time of surgery. Axial and coronal T2W magnetic resonance imaging images were evaluated retrospectively, and adenoma size, Knosp grade, suprasellar extension and TCTI were calculated. Results  The mean TCTI ratio was 1.70 (95% confidence interval [CI]: 1.65-1.75). Intraoperatively, 140 (71.4%) adenomas were classified as soft and 48 (24.5%) as fibrous. Gross total resection was achieved in 66.7% of fibrous adenomas and in 86.4% of soft adenomas ( p  = 0.007). The mean ratio was 1.68 (95% CI: 1.62-1.74) for soft tumors and 1.76 (95%CI: 1.67-1.84) for fibrous tumors. There was no difference in the mean TCTI ratio between groups. Lactotroph and somatotroph adenomas had a lower mean TCTI ratio compared with other functioning and nonfunctioning adenomas with a mean TCTI of 1.52 compared with 1.77. Conclusions  In this retrospective cohort study, we found that the TCTI ratio does not correlate with tumor consistency. We also noted that the TCTI ratio is increased in prolactin and growth hormone-secreting adenomas.

Clinicopathological significance of baseline T2-weighted signal intensity in functional pituitary adenomas

PURPOSE

To assess baseline T2-weighted signal intensity (T2-WSI) of functional pituitary adenomas (FPA), and to investigate the relationship of baseline T2-WSI with clinical features, histopathological granulation patterns, and response to treatment in patients with acromegaly, prolactinoma and Cushing's disease (CD).

METHODS

Somatotroph adenomas (n = 87), prolactinomas (n = 78) and corticotroph adenomas (n = 29) were included in the study. Baseline T2-WSI findings (grouped as hypo-, iso- and hyperintense) were compared with hormone levels, tumor diameter, granulation patterns and response to treatment.

RESULTS

Somatotroph adenomas were mostly hypointense (53%), prolactinomas were dominantly hyperintense (55%), and corticotroph adenomas were generally hyperintense (45%). Hyperintense somatotroph adenomas were larger in size with sparsely granulated pattern and tumor shrinkage rate was lower after somatostatin analogues (SSA) (p = 0.007, p = 0.035, p = 0.029, respectively). T2 hypointensity was related with higher baseline IGF-1% ULN (upper limit of normal) levels and a better response to SSA treatment (p = 0.02, p = 0.045, respectively). In female prolactinomas, hyperintensity was correlated with a smaller adenoma diameter (p = 0.001). Hypointense female prolactinomas were related to younger age at diagnosis, higher baseline PRL levels and dopamine agonist (DA) resistance (p = 0.009, p = 0.022, p < 0.001, respectively). Hyperintense corticotroph adenomas were related to larger adenoma size and sparsely granulated pattern (p = 0.04, p = 0.017, respectively). There was no significant difference in the recurrence with T2WSI in CD.

CONCLUSION

Baseline hypointense somatotroph adenomas show a better response to SSA, whereas hypointensity was related to DA resistance in female prolactinomas.

Epidemiology and biomarker profile of pituitary adenohypophysial tumors

Recent studies have reported the prevalence of pituitary tumors to be ~1/1000 population. Many are prolactin-producing tumors that are managed medically, however, the epidemiology of surgically resected pituitary adenohypophysial neuroendocrine tumors has not been reported in a large series with detailed characterization. We reviewed 1055 adenohypophysial tumors from 1169 transsphenoidal resections from the pathology files of University Health Network, Toronto, 2001-2016. Tumors were characterized by immunohistochemical localization of transcription factors (Pit-1, ERα, SF-1, Tpit), hormones (adrenocorticotropin, growth hormone, prolactin, β-thyrotropin, β-folliculotropin, β-luteotropin, α-subunit), and other biomarkers (keratins, Ki67, p27, FGFR4). Electron microscopy was used only for unusual lesions. In this cohort, 51.3% of patients were female; the average age was 51 years. Gonadotroph tumors represented 42.5%. Pit-1-lineage-tumors represented 29.9%; these were subclassified as growth-hormone-predominant (somatotroph/mammosomatotroph/mixed; 53%), prolactin-predominant (lactotroph/acidophil-stem-cell; 28%), thyrotrophs (2%), plurihormonal (14%), and not-otherwise-specified (3%). Corticotroph tumors represented 17.1%. Only 4.5% were null cell tumors and 0.5% were unusual plurihormonal tumors. In 5.5% the tumor was not characterized for technical reasons (sample size, fixation, necrosis or other artifact). All corticotroph and plurihormonal tumors were positive for keratins; others tumors showed variable negativity with highest rates in gonadotroph (37.1%) and null cell tumors (28.2%). Tumors with a Ki67 ≥ 3% comprised 60% of this cohort. Global loss of p27 was most frequent in corticotroph neoplasms, specifically those associated with elevated glucocorticoid levels. Corticotroph and lactotroph tumors were more common among females; gonadotroph tumors were more common among males. Younger patients had mainly corticotroph and Pit-1-lineage neoplasms, whereas older patients harbored mainly gonadotroph tumors. This represents one of the largest surgical series of morphologically characterized pituitary tumors reported to date and the first to include the routine use of transcription factors for tumor classification. The data provide the basis for clinicopathologic correlations that are helpful for prognostic and predictive patient management.

Predictors of surgical outcome and early criteria of remission in acromegaly

BACKGROUND

Transsphenoidal surgery (TSS) is the cornerstone of acromegaly treatment, however there are no robust predictors of surgical outcome and remission can only be defined three months after surgery.

PURPOSE

To analyze if biochemical, demographical, radiological, and immunohistochemical characteristics are predictors of surgical remission and investigate if immediate postoperative GH and IGF-I levels can help defining remission earlier.

METHODS

Consecutive acromegaly patients submitted to TSS between 2013-2016 were evaluated. Remission criteria was defined as normal IGF-I and GH <1 mcg/L three months after surgery. Data of age, sex, GH and IGF-I levels, tumor volume, cavernous sinus invasion, T2-weighted signal, Ki-67, and granulation pattern were correlated with remission status. GH and IGF-I levels at 24, 48 h, and one week postoperative were evaluated as early criteria of remission.

RESULTS

Sixty-nine patients were included (84% macroadenomas) and surgical remission was achieved in 45%. No difference between cured and not cured patients concerning age, gender, preoperative GH or IGF-I levels, tumor volume, T2-weighted signal, Ki-67 and tumor granularity was observed. Remission was obtained in 20 of 36 (56%) of the non-invasive tumors, and in 3 of 16 (19%) of the invasive tumors (p = 0.017). A GH <1.57 mcg/L 48 h after surgery was able to predict remission with 93% sensitivity and 86% specificity and an IGF-I < 231% ULNR one week after surgery predicted remission with 86% sensitivity and 93% specificity.

CONCLUSION

Cavernous sinus invasion is the only preoperative predictor of surgical remission. GH at 48 h and IGF-I one week after surgery can define earlier not cured patients.

Association between radiological parameters and clinical and molecular characteristics in human somatotropinomas

Acromegaly is a rare but severe disease, originated in 95% of cases by a growth hormone-secreting adenoma (somatotropinoma) in the pituitary. Magnetic resonance imaging (MRI) is a non-invasive technique used for the diagnosis and prognosis of pituitary tumours. The aim of this study was to determine whether the use of T2-weighted signal intensity at MRI could help to improve the characterisation of somatotropinomas, by analysing its relationship with clinical/molecular features. An observational study was implemented in a cohort of 22 patients (mean age = 42.1 ± 17.2 years; 59% women; 95% size>10 mm). Suprasellar-extended somatotropinomas presented larger diameters vs. non-extended tumours. T2-imaging revealed that 59% of tumours were hyperintense and 41% isointense adenomas, wherein hyperintense were more invasive (according to Knosp-score) than isointense adenomas. A higher proportion of hyperintense somatotropinomas presented extrasellar-growth, suprasellar-growth and invasion of the cavernous sinus compared to isointense adenomas. Interestingly, somatostatin receptor-3 and dopamine receptor-5 (DRD5) expression levels were associated with extrasellar and/or suprasellar extension. Additionally, DRD5 was also higher in hyperintense adenomas and its expression was directly correlated with Knosp-score and with tumour diameter. Hence, T2-weighted MRI on somatotropinomas represents a potential tool to refine their diagnosis and prognosis, and could support the election of preoperative treatment, when required.

AIP and the somatostatin system in pituitary tumours

Classic somatostatin analogues aimed at somatostatin receptor type 2, such as octreotide and lanreotide, represent the mainstay of medical treatment for acromegaly. These agents have the potential to decrease hormone secretion and reduce tumour size. Patients with a germline mutation in the aryl hydrocarbon receptor-interacting protein gene, AIP, develop young-onset acromegaly, poorly responsive to pharmacological therapy. In this review, we summarise the most recent studies on AIP-related pituitary adenomas, paying special attention to the causes of somatostatin resistance; the somatostatin receptor profile including type 2, type 5 and truncated variants; the role of G proteins in this pathology; the use of first and second generation somatostatin analogues; and the role of ZAC1, a zinc-finger protein with expression linked to AIP in somatotrophinoma models and acting as a key mediator of octreotide response.

Is it really possible to predict the consistency of a pituitary adenoma preoperatively?

OBJECTIVES

To determine if the consistency of pituitary adenomas can be predicted based on a preoperative MRI study and to assess the surgical outcome of firm pituitary adenomas.

MATERIALS AND METHODS

One hundred consecutive patients with pituitary adenomas and suprasellar extension were operated by a transsphenoidal approach from July 2003 to December 2006. In addition to the neurological examination, the patients were evaluated by ophthalmological, endocrinological and radiological workups. The signal intensity of the lesion on T2WI and other dimensions of the tumors were included in the MRI study.

RESULTS

There were 52 male and 48 female patients with a mean age of 42.47 years. The mean diameter of the tumor was 32.97mm and the mean SSE was 14.95mm. Six out of 100 patients had firm adenomas peroperatively. Only one of the six patients had isointense SI on T2 WI. Of these 6 patients, total excision was performed in 1 patient, subtotal in 3 patients and partial excision in 2 patients. Among the six patients with firm adenomas, 4 had preoperative hypopituitarism (P<0.001). There was a statistically significant correlation between consistency and the postoperative permanent hypopituitarism (P<0.001). The average follow up was 43.5 months. The literature is reviewed and various aspects of pituitary adenoma consistency are discussed.

CONCLUSIONS

With the present study, the consistency of pituitary adenomas cannot be reliably predicted based on a preoperative MRI study. Patients with firm adenomas likely to have more incidence of preoperative hypopituitarism and postoperative permanent hypopituitarism.

Cross-sectional prevalence of pancreatic cystic lesions in patients with acromegaly, a single-center experience

PURPOSE

Acromegaly is a disease associated with an increased risk for several kinds of neoplasms including colon and thyroid cancer. Although the association between acromegaly and pancreatic neoplasms has not been elucidated, it has recently been reported that GNAS gene mutations were found in 58% of intraductal papillary mucinous neoplasms (IPMNs), which are representative pancreatic cystic lesions, suggesting a link between IPMNs and acromegaly. To assess the prevalence of pancreatic cystic lesions in patients with acromegaly, we performed a retrospective cross-sectional single institute study.

METHODS

Thirty consecutive acromegalic patients (20 females and 10 males; mean age, 60.9 ± 11.9 years) who underwent abdominal contrast-enhanced computed tomography or magnetic resonance imaging between 2007 and 2015 at Kobe University Hospital were recruited. We also analyzed the relationship between presence of pancreatic cystic lesions and somatic GNAS mutations in pituitary tumors.

RESULTS

Seventeen of 30 (56.7%) patients studied had pancreatic cystic lesions. Nine of 17 patients (52.9%) were diagnosed with IPMNs based on imaging findings. These results suggest that the prevalence of IPMNs may be higher in acromegalic patients in acromegalic patients than historically observed in control patients (up to 13.5%). In patients with pancreatic cystic lesions, the mean patient age was higher and the duration of disease was longer than in those without pancreatic cystic lesions (67.0 ± 2.3 vs. 53.0 ± 2.7 years, p < 0.001, 15.5 ± 2.4 vs. 7.3 ± 2.8 years, p = 0.04). There were no differences in serum growth hormone levels or insulin-like growth factor standard deviation scores between these two groups (21.3 ± 6.4 vs. 23.0 ± 7.4 ng/ml, p = 0.86, 6.6 ± 0.5 vs. 8.0 ± 0.6, p = 0.70). Neither the presence of somatic GNAS mutation in a pituitary tumor nor low signal intensity of the tumor in T2 weighted magnetic resonance imaging was associated with the presence of pancreatic cystic lesions.

CONCLUSIONS

These data demonstrate that old or long-suffering patients with acromegaly have a higher prevalence of pancreatic cystic lesions. Moreover, the prevalence of pancreatic cystic lesions may be increased in acromegalic patients.

Expression of cell cycle regulators and biomarkers of proliferation and regrowth in human pituitary adenomas

PURPOSE

The pathogenesis of pituitary adenomas (PA) is complex. Ki-67, pituitary tumour transforming gene (PTTG), vascular endothelial growth factor (VEGF), cyclin D1, c-MYC and pituitary adenylate cyclase-activating peptide (PACAP) protein expression were analysed and correlated with tumour and patient characteristics.

METHODS

74 pituitary tumour samples (48 non-functional PA, 26 functional PAs); Immunohistochemical analysis of protein expression, retrospective analysis of MR images and in vitro analysis of octreotide treatment was carried out on GH3 cells.

RESULTS

PTTG expression was negatively associated with age and positively with PA size, regrowth and Ki-67 index. Cyclin D1 correlated with Ki-67 and tumour size. c-MYC negatively correlated with size of tumour and age; and correlated with PTTG expression. Somatostatin analogue treatment was associated with lower Ki-67, PTTG and Cyclin D1 expression while T2 hypointense PAs were associated with lower PTTG, cyclin D1, c-MYC and Ki-67. In vitro analyses confirmed the effect of somatostatin analogue treatment on Pttg and Cyclin D1 expression.

CONCLUSIONS

Interesting and novel observations on the differences in expression of tumour markers studied are reported. Correlation between Ki-67 expression, PTTG nuclear expression and recurrence/regrowth of PAs, emphasizes the role that Ki-67 and PTTG expression have as markers of increased proliferation. c-MYC and PTTG nuclear expression levels were correlated providing evidence that PTTG induces c-MYC expression in PAs and we propose that c-MYC might principally have a role in early pituitary tumorigenesis. Evidence is shown that the anti-proliferative effect of somatostatin analogue treatment in vivo occurs through regulation of the cell cycle.

Preoperative Evaluation of Sellar and Parasellar Macrolesions by [18F]Fluorodeoxyglucose Positron Emission Tomography

OBJECTIVE

Various diseases can occur in the sellar and suprasellar regions. The potential of [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET) for the preoperative evaluation of sellar and parasellar lesions was investigated.

METHODS

A total of 49 patients aged 8-82 years with sellar and parasellar macroscopic lesions (≥10 mm) underwent FDG PET. Twenty-two patients had pituitary adenomas, including 14 nonfunctioning and 8 growth hormone-secreting adenomas. Eleven patients had craniopharyngiomas, including 5 adamantinomatous and 6 squamous-papillary types. Eight patients had chordoma, 4 had meningioma, and 4 had a Rathke cleft cyst. The maximum standardized uptake value (SUV_max), and the ratio of the SUV_max in the tumor to the mean standardized uptake value in the normal cortex (T/N ratio) or in the normal white matter (T/W ratio) were calculated. The relationships between SUV_max, T/N ratio, and T/W ratio, and lesion disease were evaluated.

RESULTS

Uptakes of FDG, including SUV_max, T/N ratio, and T/W ratio, were lower in chordoma and Rathke cleft cyst compared with pituitary adenoma. SUV_max, T/N ratio, and T/W ratio of nonfunctioning adenoma were significantly higher than those of growth hormone-secreting adenoma. SUV_max, T/N ratio, and T/W ratio of squamous-papillary type were significantly higher than those of the adamantinomatous type of craniopharyngioma.

CONCLUSIONS

FDG PET is useful for the preoperative diagnosis of sellar and parasellar macrolesions. High uptake in nonfunctioning pituitary adenoma, and low uptake in chordoma are significant. The difference in FDG uptake dependent on the histologic subtype may be related to the specific genetics of the craniopharyngioma subtype.

Predictive role of dynamic contrast enhanced T1-weighted MR sequences in pre-surgical evaluation of macroadenomas consistency

PURPOSE

Our hypothesis was that pituitary macroadenomas show different areas of consistency detectable by enhanced magnetic resonance imaging (MRI) with Dynamic study during gadolinium administration.

MATERIALS AND METHODS

We analysed 21 patients with pituitary macroadenomas between June 2013 and June 2015. All patients underwent trans-sphenoidal surgery and neurosurgeon described macroadenomas consistency. Similarly, two neuroradiologists manually drew regions of interest (ROIs) inside the solid-appearing portions of macroadenoma and in the normal white matter both on dynamic and post-contrast acquisitions. The ratio between these ROIs, defined as Signal Intensity Ratio (SIR), allowed obtaining signal intensity curves over time on dynamic acquisition and a single value on post-contrast MRI. SIR values best differentiating solid from soft macroadenoma components were calculated and correlated with pathologic patterns. A two-sample T test and empiric receiver operating characteristic (ROC) curve of SIR was performed.

RESULTS

According to ROC analysis, the SIR value of 1.92, obtained by dynamic acquisition, best distinguished soft and hard components. All the specimens from soft components were characterized by high cellularity, high representation of vascularization and micro-haemorrhage and low percentage of collagen content. The reverse was evident in hard components.

CONCLUSIONS

We demonstrated that dynamic MRI acquisition could distinguish with good accuracy macroadenomas consistency.

Pituitary acromegaly: not one disease

Acromegaly has traditionally been regarded as a monomorphous disorder resulting from a benign pituitary adenoma. Increasing evidence, however, is highlighting that this disorder is associated with a spectrum of morphologically distinct pituitary tumors with variable clinical, biochemical and radiologic features and differing therapeutic outcomes that are attributed to different genetic and epigenetic changes. These data underscore the need for developing a more refined clinicopathological risk stratification system and implementing personalized targeted therapeutic approaches.

T2-weighted MRI signal intensity as a predictor of hormonal and tumoral responses to somatostatin receptor ligands in acromegaly: a perspective

T2-weighted MRI signal intensity of GH-secreting pituitary adenomas is gaining recognition as a marker of disease characteristics and may be a predictor of response to treatment of acromegaly. Adenomas that are T2-hypointense are more common, are smaller and are less likely to invade the cavernous sinus compared to the T2-iso and hyperintense tumors. T2-hypointense tumors are also accompanied by higher IGF1 values at baseline. When presurgical somatostatin receptor ligand (SRL) therapy is administered, T2-hypointense adenomas have better hormonal responses and have greater tumor shrinkage. Adjuvant SRL therapy of patients with T2-hypointense tumors that are uncured by surgery is also associated with a better hormonal response. We review the studies that have dealt with the T2-weighted signal intensity of GH-secreting pituitary tumors and elaborate on the details and nuances of this promising avenue of research.

Management of aggressive growth hormone secreting pituitary adenomas

Aggressive GH-secreting pituitary adenomas (GHPAs) represent an important clinical problem in patients with acromegaly. Surgical therapy, although often the mainstay of treatment for GHPAs, is less effective in aggressive GHPAs due to their invasive and destructive growth patterns, and their proclivity for infrasellar invasion. Medical therapies for GHPAs, including somatostatin analogues and GH receptor antagonists, are becoming increasingly important adjuncts to surgical intervention. Stereotactic radiosurgery serves as an important fallback therapy for tumors that cannot be cured with surgery and medications. Data suggests that patients with aggressive and refractory GHPAs are best treated at dedicated tertiary pituitary centers with multidisciplinary teams of neuroendocrinologists, neurosurgeons, radiation oncologists and other specialists who routinely provide advanced care to GHPA patients. Future research will help clarify the defining features of "aggressive" and "atypical" PAs, likely based on tumor behavior, preoperative imaging characteristics, histopathological characteristics, and molecular markers.

Sellar and Parasellar Imaging

The skull base is a complex anatomical region that harbors many important neurovascular structures in a relatively confined space. The pathology that can develop at this site is varied, and many disease processes may present with similar clinical and neuroimaging findings. While computed tomography maintains a role in the evaluation of many entities and can, for instance, delineate osseous erosion with great detail and characterize calcified tumor matrices, magnetic resonance imaging (MRI) is the mainstay in the neuroimaging assessment of most pathology occurring at the skull base. Various MRI sequences have proven to be robust tools for tissue characterization and can provide information on the presence of lipids, paramagnetic and diamagnetic elements, and tumor cellularity, among others. In addition, currently available MRI techniques are able to generate high spatial resolution images that allow visualization of cranial nerves and their involvement by adjacent pathology. The information obtained from such examinations may aid in the distinction of these disease processes and in the accurate delineation of their extent prior to biopsy or treatment planning.

T2-weighted MRI signal predicts hormone and tumor responses to somatostatin analogs in acromegaly

GH-secreting pituitary adenomas can be hypo-, iso- or hyper-intense on T2-weighted MRI sequences. We conducted the current multicenter study in a large population of patients with acromegaly to analyze the relationship between T2-weighted signal intensity on diagnostic MRI and hormonal and tumoral responses to somatostatin analogs (SSA) as primary monotherapy. Acromegaly patients receiving primary SSA for at least 3 months were included in the study. Hormonal, clinical and general MRI assessments were performed and assessed centrally. We included 120 patients with acromegaly. At diagnosis, 84, 17 and 19 tumors were T2-hypo-, iso- and hyper-intense, respectively. SSA treatment duration, cumulative and mean monthly doses were similar in the three groups. Patients with T2-hypo-intense adenomas had median SSA-induced decreases in GH and IGF-1 of 88% and 59% respectively, which were significantly greater than the decreases observed in the T2-iso- and hyper-intense groups (P < 0.001). Tumor shrinkage on SSA was also significantly greater in the T2-hypo-intense group (38%) compared with the T2-iso- and hyper-intense groups (8% and 3%, respectively; P < 0.0001). The response to SSA correlated with the calculated T2 intensity: the lower the T2-weighted intensity, the greater the decrease in random GH (P < 0.0001, r = 0.22), IGF-1 (P < 0.0001, r = 0.14) and adenoma volume (P < 0.0001, r = 0.33). The T2-weighted signal intensity of GH-secreting adenomas at diagnosis correlates with hormone reduction and tumor shrinkage in response to primary SSA treatment in acromegaly. This study supports its use as a generally available predictive tool at diagnosis that could help to guide subsequent treatment choices in acromegaly.

Epidemiology and radiological geometric assessment of pituitary macroadenomas: population-based study

CONTEXT

Pituitary adenomas are relatively common tumours with diverse clinical features. Epidemiological data are important to help quantify health burden.

OBJECTIVE

To provide in-depth epidemiological data on macroadenomas and radiologically characterize macroadenomas.

DESIGN

Population-based retrospective analysis, Prevalence as at 2014; Incidence based on data from 2000 to 2014, Retrospective analysis of baseline MRI.

SETTING

The Maltese islands.

PATIENTS

173/136 patients with macroadenomas for prevalence/incidence estimates respectively, 122 baseline MRI for radiological characterization.

MAIN OUTCOME MEASURES

Prevalence rates, Standardized Incidence rates (SIR), MRI findings.

RESULTS

The prevalence for macroadenomas was 40·67/100 000 people and the SIR was 1·90/100 000/year. Giant pituitary adenomas (>40 mm) constituted 4·8% of the whole cohort of PAs and the SIR was 0·18/100 000/year. Giant prolactinomas constituted 4·7% of all the prolactinomas and the SIR was 0·07/100 000/year, while giant NFPA constituted 6·0% of all NFPA and the SIR was 0·12/100 000/year. There was a statistically significant difference in the degree of suprasellar extension (P < 0·001) and infrasellar extension (P = 0·028) between the different macroadenoma subtypes and in the vertical extension indices (median vertical extension index NFPA 3·0 mm; PRLoma -7·7 mm; GH-secreting PA -1·7 mm; P < 0·001). Pituitary macroadenomas with cavernous sinus invasion were statistically significantly larger than those without cavernous sinus invasion (P < 0·001). NFPA had predominantly a superior extension into the cavernous sinus (63·6%) compared to the functional PAs which had predominantly an inferior extension into the cavernous sinus (59·1%) (P = 0·032).

CONCLUSIONS

The various macroadenoma subtypes' epidemiological data are presented and differences between growth patterns among the various subtypes are highlighted.

Epidemiological variations of aggressive growth hormone-secreting adenomas

Acromegaly is a chronic disorder characterized by increased morbidity and mortality in uncontrolled patients. Growth hormone-secreting pituitary adenoma is the hallmark in the majority of cases, generally considered as benign due to lack of distant metastases. However, clinical behavior in a certain proportion of these adenomas could be quite aggressive, causing difficulties in their management. Aggressive pituitary adenomas have some clinical, radiological, ultrastructural and molecular features in common and they are usually resistant to the standard treatment. In the recent years, efforts have been made to define the most appropriate markers of such adenomas that would allow an early detection and efficient individualized therapeutic strategy. The aim of this review is to give an update on epidemiology and certain markers predicting aggressive behavior of somatotropinomas.

Evaluation of diffusivity in pituitary adenoma: 3D turbo field echo with diffusion-sensitized driven-equilibrium preparation

OBJECTIVE

Diffusivity of pituitary adenoma has not been investigated fully. The purpose of this study was to evaluate the feasibility of turbo field echo with diffusion-sensitized driven-equilibrium (DSDE-TFE) preparation for pituitary adenoma in the sella turcica and unaffected anterior lobe of the pituitary gland.

METHODS

This retrospective study included 23 adult patients with pituitary adenomas. Among them, 6 each were prolactin-producing adenomas and growth hormone-producing adenomas (GH) and the remaining 11 were non-functioning adenomas (NON). The apparent diffusion coefficients (ADCs) were measured in the pituitary adenoma and in the unaffected pituitary gland using coronal reformatted plane.

RESULTS

All pituitary adenomas were clearly visualized on DSDE-TFE and ADC maps without obvious geometrical distortion. There were no statistically significant differences in ADC of the all pituitary adenoma (1.50 ± 0.61 × 10(-3) mm(2) s(-1)) and the unaffected anterior lobe of the pituitary gland (1.49 ± 0.37 × 10(-3) mm(2) s(-1), p = 0.99). The ADC in prolactin-producing adenomas (2.04 ± 0.76 × 10(-3) mm(2) s(-1)) was significantly higher than that in GH (1.26 ± 0.47 × 10(-3) mm(2) s(-1); p < 0.05) and NON (1.33 ± 0.42 × 10(-3) mm(2) s(-1); p = 0.04). There was no statistically significant difference between GH and NON (p = 0.97). The intraclass correlation coefficient for ADC was 0.985 in adenomas and 0.635 in unaffected glands.

CONCLUSION

With its insensitivity to field inhomogeneity and high spatial resolution, DSDE-TFE proved a feasible method for evaluating the diffusivity in the pituitary gland and adenoma.

ADVANCES IN KNOWLEDGE

DSDE-TFE could enable us to assess ADC of pituitary adenoma in the sella turcica with high resolution and few susceptibility artefacts.

Quantitative analyses of T2-weighted MRI as a potential marker for response to somatostatin analogs in newly diagnosed acromegaly

In growth hormone (GH)-producing adenomas, T2-weighted MRI signal intensity is a marker for granulation pattern and response to somatostatin analogs (SSA). Prediction of treatment response is necessary for individualized treatment, and T2 intensity assessment might improve preoperative classification of somatotropinomas. The objectives of this study are (I) to explore the feasibility of quantitative T2-weighted MRI histogram analyses in newly diagnosed somatotroph adenomas and their relation to clinical and histological parameters and (II) to compare the quantitative method to conventional, visual assessment of T2 intensity. The study was a retrospective cohort study of 58 newly diagnosed patients. In 34 of these, response to primary SSA treatment after median 6 months was evaluated. Parameters from the T2 histogram analyses (T2 intensity ratio and T2 homogeneity ratio) were correlated to visually assessed T2 intensity (hypo-, iso-, hyperintense), baseline characteristics, response to SSA treatment, and histological granulation pattern (anti-Cam5.2). T2 intensity ratio was lowest in the hypointense tumors and highest in the hyperintense tumors (0.66 ± 0.10 vs. 1.07 ± 0.11; p < 0.001). T2 intensity at baseline correlated with reduction in GH (r = -0.67; p < 0.001) and IGF-1 (r = -0.36; p = 0.037) after primary SSA treatment (n = 34). The T2 homogeneity ratio correlated with adenoma size reduction (r = -0.45; p = 0.008). Sparsely granulated adenomas had a higher T2 intensity than densely or intermediately granulated adenomas. T2 histogram analyses are an applicable tool to assess T2 intensity in somatotroph adenomas. Quantitatively assessed T2 intensity ratio in GH-producing adenomas correlates with conventional assessment of T2 intensity, baseline characteristics, response to SSA treatment, and histological granulation pattern.

60 YEARS OF NEUROENDOCRINOLOGY: Acromegaly

Acromegaly (ACM) is a chronic, progressive disorder caused by the persistent hypersecretion of GH, in the vast majority of cases secreted by a pituitary adenoma. The consequent increase in IGF1 (a GH-induced liver protein) is responsible for most clinical features and for the systemic complications associated with increased mortality. The clinical diagnosis, based on symptoms related to GH excess or the presence of a pituitary mass, is often delayed many years because of the slow progression of the disease. Initial testing relies on measuring the serum IGF1 concentration. The oral glucose tolerance test with concomitant GH measurement is the gold-standard diagnostic test. The therapeutic options for ACM are surgery, medical treatment, and radiotherapy (RT). The outcome of surgery is very good for microadenomas (80-90% cure rate), but at least half of the macroadenomas (most frequently encountered in ACM patients) are not cured surgically. Somatostatin analogs are mainly indicated after surgical failure. Currently their routine use as primary therapy is not recommended. Dopamine agonists are useful in a minority of cases. Pegvisomant is indicated for patients refractory to surgery and other medical treatments. RT is employed sparingly, in cases of persistent disease activity despite other treatments, due to its long-term side effects. With complex, combined treatment, at least three-quarters of the cases are controlled according to current criteria. With proper control of the disease, the specific complications are partially improved and the mortality rate is close to that of the background population.

Treatment of acromegaly in the era of personalized and predictive medicine

Acromegaly is a chronic disorder usually diagnosed late in the disease evolution. Such delayed diagnosis, together with the inability to achieve the treatment goals of normalizing biochemical disease markers and controlling tumour mass may result in substantial morbidity and mortality. Somatostatin analogues (SSA) are accepted as first-line medical therapy or as second-line therapy in patients undergoing unsuccessful surgery and are considered a cornerstone in the treatment of acromegaly. However, because a high percentage of patients experience SSA medical treatment failure, the identification of biomarkers associated with a successful or unsuccessful response to all classes of medical therapy would help in the choice of treatment and potentially allow for a quicker normalization of biochemical parameters. The current treatment algorithms for acromegaly are based upon a "trial-and-error" approach with additional treatment options provided when disease is not controlled. In many other diseases, therapeutic algorithms have been evolving towards personalized treatment with the medication that best matches individual disease characteristics, using biomarkers that identify therapeutic response. Additionally, a personalized approach to complementary treatment of comorbidities present in the acromegalic patient is also required. This review will discuss the development of a potential treatment algorithm for acromegaly addressing the biochemical control of the disease as well of its associated comorbidities, under a personalized approach based upon markers of prognostic and predictive significance, such as tumour size, MRI adenoma signal, GH value after acute octreotide test, granular adenoma pattern, Ki-67, somatostatin receptor phenotype, aryl hydrocarbon-interacting protein expression, gsp mutations, RAF kinase activity, E-cadherin and beta-arrestin-1.

Characteristic location and growth patterns of functioning pituitary adenomas: correlation with histological distribution of hormone-secreting cells in the pituitary gland

OBJECTIVE

To evaluate the correlation between the magnetic resonance imaging findings of functional pituitary adenomas and histological distribution of hormone-secreting cells in pituitary gland.

METHODS

Forty-nine patients with pathologically confirmed functional micro and macro pituitary adenomas were retrospectively reviewed for its location and growth direction.

RESULTS

Micro-prolactin, micro-adrenocorticotropic hormone (ACTH), and micro-growth hormone (GH) producing adenomas showed specific location (P-value <.01). Macro-GH and macro-thyroid-stimulating hormone producing adenomas showed specific growth direction (P-value <.05), whereas macro-prolactin and macro-ACTH producing adenomas did not.

CONCLUSION

The functional pituitary microadenomas' location and macroadenomas' growth pattern correlate well with histological distribution of hormone-secreting cells in pituitary gland.

Update on prognostic factors in acromegaly: Is a risk score possible?

Certain clinical conditions and markers have recently been demonstrated to modify the natural history of acromegaly in affected patients. Thus, some clinical, histological, radiological and molecular factors are associated with more aggressive pituitary tumors that have higher biochemical activity, higher tumor volumes and decreased tumoral and biochemical responses to current therapies. However, these factors do not seem to have an equal influence on the prognosis of patients with acromegaly. We present a review of the factors that influence the clinical course of patients with acromegaly and propose a risk value for each factor that will allow prognostic scoring for affected patients by considering a combination of these factors.

Clinicopathological correlates of extrasellar growth patterns in pituitary adenomas

We reviewed clinical, imaging and histopathology details of 297 patients who underwent surgery for pituitary adenomas, with an equal distribution of functional and non-functioning tumors, to examine clinicopathological correlates of extrasellar growth. Knosp grades of 3 and 4 on MRI defined cavernous sinus invasion, Hardy grades of C and D defined significant suprasellar/subfrontal extension, and intraoperative evidence of tumor eroding through the clivus or sellar floor defined infrasellar invasion. Disease status at follow-up was known in 246 patients overall, including 35 patients who were evaluated for progression of residual disease on serial imaging. On univariate analysis, we found several statistically significant associations (p < 0.05) including adenoma size with age, sex and tumor protein p53 reactivity; cavernous sinus invasion with size, non-functional status, increased mitotic activity, an elevated MIB-1 proliferation index and p53 reactivity; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with age and tumor size. When adjusting for confounders with logistic regression, several significant associations were evident including adenoma size with male sex and p53 reactivity; cavernous sinus invasion with size and elevated MIB-1 proliferation index; suprasellar/subfrontal extension with p53 reactivity; and infrasellar invasion with adenoma size alone. Patients with early progression of postoperative residual tumor were younger with a non-significant trend towards higher MIB-1 proliferation indices. Individual patterns of extrasellar growth in pituitary adenomas are associated with unique clinical and immunohistochemical profiles. Younger patients with elevated MIB-1 values are probably at high risk for early recurrence of non-functioning tumors. Definitions of atypia must be standardized before more robust assumptions about tumor biology can be established.

Prediction of Consistency of Pituitary Adenomas by Magnetic Resonance Imaging

Objective Pituitary adenomas are typically soft. The prevalence of fibrous adenomas is ∼ 5 to 13%. Firm tumors are difficult to remove by curettage or suction. Predicting fibrous adenomas by magnetic resonance (MR) imaging is typically difficult and unreliable. We propose a new prediction method based on MR T2-sequence intensity. Methods The MRIs of 36 consecutive patients with nonsecreting macroadenomas were evaluated preoperatively by a blinded radiologist. Using an MR T2-weighted sequence, regions of interest were sampled from the adenoma and cerebellar peduncle, and the ratio was calculated. Intraoperatively, tumors were graded prospectively for their consistency by the operating surgeon. Results There were 28 soft and 6 fibrous tumors. Unpaired t test for these ratios was found to be statistically significant (p < 0.0240; 95% confidence interval, -0.8229 to -0.06207). Mean values for soft tumors were found to be 1.918 (standard error of the mean [SEM] = 0.08212); firm tumors, 1.475 (SEM = 0.1179). Soft tumors were associated with ratios > 1.5 (sensitivity 100%; specificity 66.7%); firm tumors were associated with ratios < 1.8 (sensitivity 100%; specificity 42.9%). Conclusion Fibrous adenomas are typically diagnosed intraoperatively. However, their resection can be technically challenging. Using T2 intensity ratios on routine preoperative MRI allows identification of these challenging cases. The surgeon can then be better prepared for the surgical resection.

Pituitary MRI characteristics in 297 acromegaly patients based on T2-weighted sequences

Responses of GH-secreting adenomas to multimodal management of acromegaly vary widely between patients. Understanding the behavioral patterns of GH-secreting adenomas by identifying factors predictive of their evolution is a research priority. The aim of this study was to clarify the relationship between the T2-weighted adenoma signal on diagnostic magnetic resonance imaging (MRI) in acromegaly and clinical and biological features at diagnosis. An international, multicenter, retrospective analysis was performed using a large population of 297 acromegalic patients recently diagnosed with available diagnostic MRI evaluations. The study was conducted at ten endocrine tertiary referral centers. Clinical and biochemical characteristics, and MRI signal findings were evaluated. T2-hypointense adenomas represented 52.9% of the series, were smaller than their T2-hyperintense and isointense counterparts (P<0.0001), were associated with higher IGF1 levels (P=0.0001), invaded the cavernous sinus less frequently (P=0.0002), and rarely caused optic chiasm compression (P<0.0001). Acromegalic men tended to be younger at diagnosis than women (P=0.067) and presented higher IGF1 values (P=0.01). Although in total, adenomas had a predominantly inferior extension in 45.8% of cases, in men this was more frequent (P<0.0001), whereas in women optic chiasm compression of macroadenomas occurred more often (P=0.0067). Most adenomas (45.1%) measured between 11 and 20 mm in maximal diameter and bigger adenomas were diagnosed at younger ages (P=0.0001). The T2-weighted signal differentiates GH-secreting adenomas into subgroups with particular behaviors. This raises the question of whether the T2-weighted signal could represent a factor in the classification of acromegalic patients in future studies.

Invasion of the cavernous sinus space in pituitary adenomas: endoscopic verification and its correlation with an MRI-based classification

OBJECT An important prognostic factor for the surgical outcome and recurrence of a pituitary adenoma is its invasiveness into parasellar tissue, particularly into the space of the cavernous sinus (CS). The aims of this study were to reevaluate the existing parasellar classifications using an endoscopic technique and to evaluate the clinical and radiological outcomes associated with each grade. METHODS The authors investigated 137 pituitary macroadenomas classified radiologically at least on one side as Grade 1 or higher (parasellar extension) and correlated the surgical findings using an endoscopic technique, with special reference to the invasiveness of the tumor into the CS. In each case, postoperative MRI was performed to evaluate the gross-total resection (GTR) rate and the rate of endocrinological remission (ER) in functioning adenomas. RESULTS The authors found a 16% rate of CS invasion during surgery for these macroadenomas. Adenomas radiologically classified as Grade 1 were found to be invasive in 1.5%, and the GTR/ER rate was 83%/88%. For Grade 2 adenomas, the rate of invasion was 9.9%, and the GTR/ER rate was 71%/60%. For Grade 3 adenomas, the rate of invasion was 37.9%, and the GTR/ER rate was 75%/33%. When the superior compartment of the CS (Grade 3A) was involved, the authors found a rate of invasion that was lower (p < 0.001) than that when the inferior compartment was involved (Grade 3B). The rate of invasion in Grade 3A adenomas was 26.5% with a GTR/ER rate of 85%/67%, whereas for Grade 3B adenomas, the rate of surgically observed invasion was 70.6% with a GTR/ER rate of 64%/0%. All of the Grade 4 adenomas were invasive, and the GTR/ER rate was 0%. A comparison of microscopic and endoscopic techniques revealed no difference in adenomas with Grade 1 or 4 parasellar extension. In Grade 2 adenomas, however, the CS was found by the endoscopic technique to be invaded in 9.9% and by microscopic evaluation to be invaded in 88% (p < 0.001); in Grade 3 adenomas, the difference was 37.9% versus 86%, respectively (p = 0.002). Grade 4 adenomas had a statistically significant lower rate of GTR than those of all the other grades. In case of ER only, Grade 1 adenomas had a statistically significant higher rate of remission than did Grade 3B and Grade 4 adenomas. CONCLUSIONS The proposed classification proved that with increasing grades, the likelihood of surgically observed invasion rises and the chance of GTR and ER decreases. The direct endoscopic view confirmed the low rate of invasion of Grade 1 adenomas but showed significantly lower rates of invasion in Grade 2 and 3 adenomas than those previously found using the microscopic technique. In cases in which the intracavernous internal carotid artery was encased (Grade 4), all the adenomas were invasive and the GTR/ER rate was 0%/0%. The authors suggest the addition of Grades 3A and 3B to distinguish the strikingly different outcomes of adenomas invading the superior CS compartments and those invading the inferior CS compartments.

Predictive value of diffusion-weighted MRI for tumor consistency and resection rate of nonfunctional pituitary macroadenomas

BACKGROUNDS

Firm tumor consistency is one of the most important factors that impede sufficient removal of pituitary macroademoas via a transsphenoidal approach. The utility of diffusion-weighted (DW) magnetic resonance imaging (MRI) in predicting the tumor consistency and successfulness of transsphenoidal resection was evaluated in this study.

METHODS

Thirty consecutive primary cases of nonfunctional pituitary macroadenomas were prospectively enrolled. Conventional and DW MRI were done for all the patients and the apparent diffusion coefficient (ADC) values and the signal intensity of the solid tumor were determined. Intraoperative report of tumor consistency, the degree of fibrosis and percentage of collagen content were documented. The 8 weeks postoperative MRI was used for calculation of the tumor resection rate.

RESULTS

The tumor consistency was soft in 10 patients (33.3 %), intermediate in 14 patients (46.7 %) and hard in 6 patients (20 %). The mean collagen content percentage was 10, 23.5 and 66 % (p = 0.009) and the average resection rate was 75, 43 39 % in the three groups respectively (p = 0.001). The mean ADC value was not significantly correlated with the tumor consistency and resection rate. Tumors with isointense to hyperintense signal on DW MRI were more commonly removable by suction and had higher resection rates than those with hypointense signals (p = 0.019). For ADC values within the range of 600-740 × 10(-3) mm(2)/s, a residual volume larger than 20 % of the tumor was more likely.

CONCLUSIONS

DW MRI was useful to predict the tumor consistency, collagen content and the chance of removal of pituitary macroadenomas through endoscopic transsphenoidal surgery, and is recommended in the preoperative patient evaluation.

Serial 3 T magnetic resonance imaging during cabergoline treatment of macroprolactinomas

OBJECTIVE

Cabergoline is the treatment of choice for prolactin (PRL)-producing pituitary adenomas, because of its efficacy in normalizing PRL levels, and inducing tumor shrinkage. The clinical use of 3 T magnetic resonance imaging (MRI) for neuroimaging has rapidly expanded in recent years. In particular, T2-weighted imaging (T2WI) provides high anatomical and contrast resolution.

PATIENTS AND METHODS

In this study, serial 3 T MRI with T2WI was utilized during cabergoline treatment of 10 patients with macroprolactinomas. Cabergoline was started at a standard weekly dosage and incrementally adjusted on individual posttreatment PRL values.

RESULTS

MRI confirmed tumor shrinkage in all patients during cabergoline treatment. Cabergoline normalized hyperprolactinemia in all but one patient. In six of 10 patients, distinct low-signal-intensity areas were evident throughout the adenomas on T2WI. In four of those six patients, massive low-signal-intensity areas appeared at 1-4 months, after which tumors decreased in size by over 80%. These findings in the early phase of prolactinoma treatment predicted pronounced regression or near-complete disappearance of the tumor. Reduction of T2 intensity possibly reflected dehydration due to diffuse hemorrhage in the adenomas.

CONCLUSION

T2-weighted 3 T MR images are valuable for assessing and monitoring cabergoline treatment of macroprolactinomas.

Growth hormone secreting pituitary microadenomas and empty sella - An under-recognized association?

OBJECTIVE

To describe an association of growth hormone (GH) secreting pituitary microadenomas and empty sella (ES), which has been described in case reports - the underlying mechanisms are unclear.

METHODS

We retrospectively analyzed patients operated for GH-producing pituitary adenomas between February 2004 and February 2009. Magnetic resonance imaging (MRI), computed tomography (CT) imaging, and pituitary function testing were performed. All cases underwent transsphenoidal surgery (TSS). Mean follow up was 38 months (range 12-80 months).

RESULTS

Out of 152 patients with acromegaly due to GH-producing pituitary adenomas (female:male=73:79; age range 17-63 years), 69 patients had microadenomas (45.4%; 38 females, 31 males). We found 14 cases (14/69, 20.3%), all microadenomas, with presurgical evidence of ES - 10 females (71%) and 4 males (29%) (female:male=2.5:1). When compared with 103 patients with GH-negative microadenomas treated in the same time period (ES in 4 of 103; 3.9%), ES was highly significantly associated with GH production by the microadenoma (p=0.001). In acromegalics with empty sella, no cases of ectopic adenoma were found. Postoperatively, GH and IGF-1 levels fell in all patients, and 7 cases had random GH and IGF-1 levels consistent with cure.

CONCLUSION

The combination of GH-producing microadenomas and empty, enlarged sella is not rare. In this setting, preoperative CT scans are very useful and the transsphenoidal approach is efficient and safe. The mechanism underlying the association of GH-producing microadenomas and empty sella remains unclear and requires further studies.

Aggressive pituitary adenomas--diagnosis and emerging treatments

The WHO categorizes pituitary tumours as typical adenomas, atypical adenomas and pituitary carcinomas, with typical adenomas constituting the major class. However, the WHO classification does not provide an accurate correlation between histopathological findings and clinical behaviour. Tumours lacking typical histological features are classified as atypical, but not all are clinically atypical or exhibit aggressive behaviour. Pituitary carcinomas, by definition, have craniospinal or systemic metastases, although not all display classical cytological features of malignancy. Aggressive pituitary adenomas, defined from a clinical perspective, have earlier and more frequent recurrences and can be resistant to conventional treatments. Specific biomarkers have not yet been identified that can distinguish between clinically aggressive and nonaggressive pituitary adenomas, although the antigen Ki-67 proliferation index might be of value. This Review highlights the need to develop new biomarkers to facilitate the early detection of clinically aggressive pituitary adenomas and discusses emerging markers that hold promise for their identification. Defining aggressiveness is of crucial importance for improving the management of patients by enhancing prognostic predictions and effectiveness of treatment. New drugs, such as temozolomide, have potential use in the management of these patients; anti-VEGF therapy, mTOR and tyrosine kinase inhibitors are also potentially useful in managing selected patients.

Geometric survey on magnetic resonance imaging of growth hormone producing pituitary adenoma

Apart from the radiologic features regarding size and invasiveness, we had noticed some differences in morphology among types of pituitary adenomas. We conducted this study to verify the differences in radiologic morphology between growth hormone producing pituitary adenomas (GHoma) and nonfunctioning pituitary adenomas (NFoma). Pre-surgical magnetic resonance images (MRIs) were assessed in 50 cases of GHoma and 50 cases of NFoma. Geometric parameters on MRI were set in accordance with sellar anatomy. Intensity of T1-weighted image was not different between the two groups, but hypo-intensity of T2-weighted image was more frequently seen in GHoma. Predominant inferior extension of tumor was seen mostly in GHoma (88 vs. 38%). Extension of the tumor to the superior compartment of cavernous sinus was more frequent in NFoma. Pituitary gland was generally located superior to GHoma and postero-superior to NFoma. Growth characteristics of pituitary adenoma were confirmed to differ between GHoma and NFoma.

Severe growth hormone deficiency is rare in surgically-cured acromegalics

Growth hormone deficiency (GHD) in surgically-cured acromegalics has been reported to negatively affect their metabolic condition and quality of life (QOL). The incidence of GHD, its causes, and its effects on their physio-psychological condition remain to be examined in detail. We performed a retrospective study to investigate GH secretory function in surgically-cured acromegalics, prognostic factors of GHD, and its impact on QOL. The study population consisted of 72 acromegalics who were determined to be surgically cured according to the Cortina consensus criteria. We recorded the incidence of impaired GH secretory function based on the peak GH level during postoperative insulin tolerance test (ITT) which lowered their nadir blood sugar to under 50 mg/dL. Their QOL was evaluated by SF-36. In surgically-cured acromegalics, the incidence of severe GHD (peak GH during ITT ≦ 3.0 μg/L) was 12.5 % (9/72). The preoperative tumor size was significantly larger in patients with severe GHD than without severe GHD (21.9 ± 9.0 vs. 15.5 ± 7.1 mm, p = 0.017). The peak GH levels during postoperative ITT were statistically correlated with the physical but not the mental component summary of the SF-36 score. The incidence of GHD was 12.5 % in our surgically-cured acromegalics. As some QOL aspects are positively related with peak GH levels during postoperative ITT, efforts should be made to preserve pituitary function in acromegalic patients undergoing adenomectomy.

Pituitary macroadenoma presenting with pituitary apoplexy, acromegaly and secondary diabetes mellitus - a case report

Pituitary adenomas are associated with significant morbidity. The usual symptoms on presentation are of endocrine dysfunction and mass effects. A 31-year-old African female presented with headache, irregular menses, blurring of vision in the right eye and complete loss of vision in the left eye for 1 year. She had coarse facial features, enlarged hands and feet. Her right eye had temporal hemianopia with decreased visual acuity and her left eye had no perception of light. Investigations revealed an elevated fasting blood sugar and an elevated prolactin and growth hormone level. A CT scan and MRI done showed a hemorrhagic pituitary macroadenoma. She was put on bromocriptine, ocreotide, analgesics and insulin. Thereafter, she underwent transphenoidal surgery, where near total resection of the tumor was achieved. Patient is doing well post-operatively. This case highlights the importance of the use of a high clinical index of suspicion and radiological findings in diagnosis.

Imaging the pituitary and parasellar region

Magnetic resonance imaging is the fundamental imaging tool for the evaluation of tumors and other lesions of the pituitary gland and infundibulum. Abnormalities may arise within the pituitary itself, from vestigial embryologic remnants, or from surrounding tissues. Correct diagnosis rests on accurate assessment of lesion location, imaging appearance, and clinical presentation. This article reviews the radiologic evaluation of lesions within the sella and suprasellar cistern, focusing on common masses and pseudomasses of the pituitary and sellar region that neurosurgeons are most likely to encounter in clinical practice.

Clinical implications of growth hormone-secreting tumor subtypes

Growth hormone (GH) pituitary tumors are almost always benign adenomas, yet are associated with significant morbidity and mortality. Surgical and medical responses of GH tumors are often incomplete, and therefore predictors of residual or recurrent disease are needed. Clinical features, including patient gender, age or size of adenoma, have proven to be unreliable predictors of recurrence. Differing clinical behavior between the two GH tumor subtypes, sparsely granulated (SG) versus densely granulated (DG), has been reported, but has not been used routinely in clinical management. SG tumors are more common in younger patients (<50 years), and are usually larger tumors. SG tumors have been reported to be less responsive to somatostatin analogs (SSA) than DG tumors. The mechanisms underlying these potential differences in tumor behavior, however, are poorly defined. Subsets (up to 50 %) of DG adenomas harbor a gsp mutation that can activate cAMP that provides a theoretical intracellular target for somatostatin therapy. In contrast, some SG tumors have reduced somatostatin receptor expression and mutations in the extracellular domain of the GH receptor that may contribute to SSA resistance. While DG versus SG growth hormone adenomas are readily distinguished by immunohistochemistry, other less common GH adenoma variants still require electron microscopy (EM) for confident subclassification. Whether these less common variants possess unique clinical features is unknown. Research is needed to identify clinically relevant biomarkers of GH pituitary tumors that predict risk of recurrence and response to medical therapy.

Intensity of pituitary adenoma on T2-weighted magnetic resonance imaging predicts the response to octreotide treatment in newly diagnosed acromegaly

BACKGROUND

Primary, preoperative medical treatment is an option in selected patients with acromegaly, but a subset of patients respond poorly. Valid prediction of response to somatostatin analogues (SA) might thus alter treatment stratification. The aims of this study were to assess whether T2 signal intensity could determine long-term response to first-line SA treatment and to assess clinical and biochemical baseline characteristics, as well as histological subtype in relation to the magnetic resonance imaging (MRI) appearances.

METHODS

In 45 newly diagnosed patients, T2-weighted signal intensity of the tumour was classified into hypo-, iso- or hyperintense. Biochemical and clinical baseline variables for the three groups were compared. In 25 patients primarily treated with long-acting SA for a median of 6 months [interquartile range (IQR):155-180 days], GH and IGF-1 reduction was assessed, and in 34 cases, immunohistochemical granulation pattern was evaluated.

RESULTS

The results showed that 12 (27%) adenomas were hypointense, 15 (33%) isointense and 18 (40%) hyperintense. Median IGF-1 [ratio IGF-1/ULN; (upper limit of normal)] was 3·5 (2·3-4·9), 2·9 (2·6-3·8) and 1·9 (1·3-2·6), respectively (P = 0·006 for difference between groups). Median GH values (μg/l) of a 3- to 5-point profile were 17·5 (6·1-35), 9·3 (6·0-32·5) and 4·1 (1·5-8·3), (P = 0·025). Median IGF-1 reduction (% of baseline) after first-line SA treatment was 51 (49-70), 36 (19-74) and 13 (5-42) (P = 0·03); median reduction in GH (% of baseline) was 86 (72-94), 78 (62-85) and 46 (1-70) (P = 0·02). T2 hyperintensity was associated with sparse granulation pattern on immunohistochemistry.

CONCLUSION

In patients with acromegaly, T2 signal intensity at diagnosis correlates with histological features and predicts biochemical outcome of first-line SA treatment.

Advances in pituitary imaging technology and future prospects

There have been substantial advances in pituitary imaging in the last half-century. In particular, magnetic resonance imaging is now established as the imaging modality of choice, providing high quality images of the hypothalamic-pituitary axis and adjacent structures. More recent technological advances, such as the emergence of 3 Tesla MRI, are already being widely incorporated into imaging practice. However, other advanced techniques, including a variety of potential imaging biomarkers, still require further research to evaluate their potential and define their precise role. The recent development of intraoperative MRI appears promising and may have the potential to improve the outcome of pituitary surgery. Modern high quality imaging inevitably leads to the discovery of incidental lesions, including those within the pituitary gland, although it also plays a central role in their subsequent evaluation and management.