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

Predictors of favorable long-term outcomes in first-line surgery for microprolactinomas

PURPOSE

Opting for first-line surgery in carefully selected patients with microprolactinomas provides the advantage of avoiding long-term dopamine agonist (DA) medication and potential associated side effects. However, the lack of comprehensive long-term data poses a challenge in identifying those patients who would benefit the most from upfront surgery. To improve guidance in the selection process for microprolactinoma patients in clinical practice, we aimed to establish simple clinical and biochemical parameters predicting non-dependence on DAs.

METHODOLOGY

Retrospective analysis of a prospectively maintained database, focusing on patients with microprolactinomas who underwent upfront surgery. We assessed clinical and biochemical risk factors for the patients' reliance on DAs at their latest follow-up using regression analysis. We next proceeded to conduct Receiver Operating Characteristic (ROC) analysis to determine the optimal threshold cutoff prolactin (PRL) level for practical application in clinical settings that best differentiates between surgical long-term remission status and long-term dependence on DAs.

RESULTS

A microadenoma was observed in 46 patients, of whom 12 (26%) exhibited long-term dependence on DAs at a median follow-up of 78 months. Baseline PRL values were significantly higher in patients with long-term DA dependence compared to those without (p = 0.05). High baseline PRL values (HR 23.9, 95% CI 1.0-593.7, p = 0.05), but not the presence of headache or male gender, were identified as independent predictors of long-term dependence on DAs. PRL thresholds for discriminating long-term DA dependence were estimated to be 290 µg/L (AUROC = 0.73, 95% CI 0.55-0.92, p = 0.03; sensitivity = 90%, specificity = 80%).

CONCLUSIONS

In patients with microprolactinomas, first-line surgery presents a favorable prospect for reducing reliance on DAs. However, for those with high PRL levels ≥ 290 µg/L at diagnosis, first-line surgery is not recommended, as the majority of them require adjuvant DA therapy in the long term.

Neuro-ophthalmic evaluation and management of pituitary disease

Neuro-ophthalmic evaluation is a crucial component of the diagnostic and prognostic assessment of pituitary disease and compressive chiasmopathy, and can inform the timing of vision-restoring tumour resection surgery. The most common disease affecting the pituitary with neuro-ophthalmic implications are pituitary adenomas. Neuro-ophthalmic manifestations include decreased vision, abnormal colour vision and impaired visual field or diplopia. The recognition of these syndromes is critical to achieve early diagnosis and treatment and to improve prognosis. The pattern of vision loss in chiasmal compression is determined by the anatomical relationship between the pituitary lesion and optic chiasm, and potential visual field defects include bitemporal deficits, junctional scotomas, monocular cecocentral defects, and incongruous homonymous hemianopias. Rarer neuro-ophthalmic manifestations of pituitary disease include ophthalmoplegia, nystagmus, and obstructive hydrocephalus. There is growing evidence that demonstrates the strong diagnostic utility of optical coherence tomography (OCT) parameters in detecting the presence of compressive chiasmopathy, as well as the prognostic ability to predict the rate and degree of visual recovery following decompression surgery. Long-term neuro-ophthalmic monitoring is critical for detecting delayed vision loss following resection surgery, which may represent tumour recurrence or secondary complications.

How often should we perform magnetic resonance imaging (MRI) for the follow-up of pituitary adenoma?

Magnetic resonance imaging (MRI) is the examination of choice for diagnosing and monitoring pituitary adenoma (also known as pituitary neuroendocrine tumor or PitNET), whether treated or not. However, repeating the examination too often (and sometimes unnecessarily) is costly, and worrying data on tissue accumulation (brain, bone, etc.) of gadolinium atoms dissociated from their carrier molecule (chelator) have led European authorities to ban contrast agents based on linear chelators of gadolinium, which are particularly susceptible to rapid dissociation, in favor of chemically more stable macrocyclic chelators. It is therefore important to determine the optimal frequency for pituitary MRI monitoring in order to safely assess the natural history or therapeutic response of pituitary adenomas. The aim of this article is to summarize the most recent data on optimal follow-up intervals depending on the type, size and location of the pituitary tumor and the clinical situation in general, in order to generate monitoring algorithms to guide clinicians.

Surveillance Imaging Strategies for Pituitary Adenomas: When, How Frequent, and When to Stop

OBJECTIVE

To describe a practical approach of when and how often to perform imaging, and when to stop imaging pituitary adenomas (PAs).

METHODS

A literature review was carried out and recommendations provided are derived largely from personal experience.

RESULTS

Magnetic resonance imaging is the mainstay imaging modality of choice in the assessment, treatment planning, and follow-up of PAs. These adenomas are discovered incidentally during imaging for a variety of unrelated conditions, because of clinical symptoms related to mass effects on the adjacent structures, or during workup for functional alterations of the adenoma. Imaging is also used in the preoperative and postoperative phases of assessment of PAs, for surgical and radiotherapy planning, for postoperative surveillance to assess for adenoma stability and detection of adenoma recurrence, and for surveillance to monitor for adenoma growth in unoperated PAs. Currently, because there are no evidence-based consensus recommendations, the optimal strategy for surveillance imaging of PAs is not clearly established. Younger age, initial adenoma size, extrasellar extension, mass effect, cavernous sinus invasion, functional status, histopathologic characteristics, cost considerations, imaging accessibility, patient preference, and patient contraindications (eg, implanted metallic devices and patient claustrophobia) are all important factors that influence the strategy for surveillance imaging.

CONCLUSIONS

This review provides a practical approach of performing surveillance imaging strategies for PAs that should be individualized based on clinical presentation, history, adenoma morphology on imaging, and histopathologic characteristics.

Prolactin-secreting pituitary adenomas: male-specific differences in pathogenesis, clinical presentation and treatment

Prolactinomas (PRLomas) constitute approximately half of all pituitary adenomas and approximately one-fifth of them are diagnosed in males. The clinical presentation of PRLomas results from direct prolactin (PRL) action, duration and severity of hyperprolactinemia, and tumor mass effect. Male PRLomas, compared to females, tend to be larger and more invasive, are associated with higher PRL concentration at diagnosis, present higher proliferative potential, are more frequently resistant to standard pharmacotherapy, and thus may require multimodal approach, including surgical resection, radiotherapy, and alternative medical agents. Therefore, the management of PRLomas in men is challenging in many cases. Additionally, hyperprolactinemia is associated with a significant negative impact on men's health, including sexual function and fertility potential, bone health, cardiovascular and metabolic complications, leading to decreased quality of life. In this review, we highlight the differences in pathogenesis, clinical presentation and treatment of PRLomas concerning the male sex.

Diagnosis and management of prolactin-secreting pituitary adenomas: a Pituitary Society international Consensus Statement

This Consensus Statement from an international, multidisciplinary workshop sponsored by the Pituitary Society offers evidence-based graded consensus recommendations and key summary points for clinical practice on the diagnosis and management of prolactinomas. Epidemiology and pathogenesis, clinical presentation of disordered pituitary hormone secretion, assessment of hyperprolactinaemia and biochemical evaluation, optimal use of imaging strategies and disease-related complications are addressed. In-depth discussions present the latest evidence on treatment of prolactinoma, including efficacy, adverse effects and options for withdrawal of dopamine agonist therapy, as well as indications for surgery, preoperative medical therapy and radiation therapy. Management of prolactinoma in special situations is discussed, including cystic lesions, mixed growth hormone-secreting and prolactin-secreting adenomas and giant and aggressive prolactinomas. Furthermore, considerations for pregnancy and fertility are outlined, as well as management of prolactinomas in children and adolescents, patients with an underlying psychiatric disorder, postmenopausal women, transgender individuals and patients with chronic kidney disease. The workshop concluded that, although treatment resistance is rare, there is a need for additional therapeutic options to address clinical challenges in treating these patients and a need to facilitate international registries to enable risk stratification and optimization of therapeutic strategies.

Gender Disparities in Prolactinomas: Unravelling Clinical Patterns, Metabolic Variations, and Treatment Responses

Background and objective Individuals with prolactinoma exhibit elevated rates of obesity, metabolic syndrome (MS), and dyslipidemia compared to their healthy counterparts. However, there is a lack of data regarding metabolic variance between male and female prolactinoma patients. Consequently, this study aimed to investigate and compare sex-specific discrepancies in metabolic abnormalities among individuals diagnosed with prolactinoma. Methods In this prospective study, 80 treatment-naïve patients with prolactinoma (12 males and 68 females) underwent clinical assessments and laboratory investigations. The measured parameters included blood glucose, total cholesterol (TC), triglycerides (TG), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), urea, creatinine, uric acid, and blood glucose levels. The patients were treated with cabergoline, a dopamine agonist, and reevaluated after 12 weeks. Results Forty-eight patients had microprolactinomas (all females), and 32 had macroprolactinomas (20 females, 12 males). The mean age was 28.30±7.49 years for females and 28.91±7.12 years for males (p=0.71). The median symptom duration was 12 months (range 1-72 months, IQR 4-16 months), with no significant difference between males (median 12 months, IQR 5-54 months) and females (median 12 months, IQR 10-24 months, p=0.620). The median serum prolactin (PRL) was 988 ng/mL (IQR 471-1,439) in males and 165 ng/mL (IQR 90-425) in females (p<0.05). Males showed higher HbA1c, BGF, TC, TG, LDL-C, and higher rates of obesity, MS, and diabetes mellitus. Treatment with cabergoline resulted in significant improvements in the HbA1c, BGF, TC, TG, and LDL-C levels. Conclusion Males with prolactinomas had larger tumor sizes and higher serum PRL levels than females. Additionally, males exhibited worse metabolic parameters than females. However, there was no significant difference in the duration of symptoms or age at diagnosis between the two groups.

[Management of prolactinoma prior to, during, and after pregnancy]

Hyperprolactinemia should actively be investigated as a potential reason of infertility. Underlying prolactinomas may successfully be treated with dopamine agonists. However, patients with micro- or well-circumscribed macroprolactinomas (Knosp 0 or 1) should also be informed about transsphenoidal surgery offering cure in contrast to long-lasting medical therapy. Management prior to and during pregnancy is usually unremarkable but may pose some specific challenges.

Is systematic Gadolinium injection relevant during MRI follow-up for non-functioning pituitary macroadenomas?

OBJECTIVE

To compare the performance of coronal contrast-enhanced T1-weighted (ceT1-w) and T2-weighted (T2-w) sequences for diagnosing progression during the MRI follow-up of Non-Functioning Pituitary MacroAdenomas (NFPMAs).

PATIENTS AND METHODS

106 patients, who had at least two MRIs for the follow-up of NFPMA, were enrolled retrospectively. The largest adenoma diameter was measured on coronal ceT1-w sequences and separately on T2-w sequences for all follow-up MRIs. Interobserver variability was also assessed by 2 independent neuroradiologists in a sample series of 100 examinations. Progression was defined by an increase ≥ 2 mm in diameter between 2 MRIs. Progression thresholds of 3 and 4 mm were also tested. The results of ceT1-w and T2-w sequences were analysed for concordance.

RESULTS

93.1% concordance was achieved between ceT1-w and T2-w coronal sequences in 580 follow-up MRIs. In the case of progression detected on at least one sequence, 64.4% concordance was documented for a 2-mm threshold, 87.7% for 3-mm and 97.1% for 4-mm. Discordance was mainly observed on the first postoperative MRI and in case of NFPMAs with multiple recurrences. Kappa was better for diagnosing progression on T2-w than on ceT1-w sequences (0.67 vs. 0.54). It should be noted that 100% agreement was observed between the 2 sequences in the 82 follow-up MRIs of patients with complete surgical resection.

CONCLUSION

93.1% concordance was achieved for coronal ceT1-w and T2-w sequences during the MRI follow-up of NFPMAs, thus challenging systematic injection of gadolinium. If MRI without gadolinium injection is a first-line option, our results suggest that ceT1-w sequences should be reserved for the first postoperative MRI and for the follow-up of aggressive and recurrent NFPMAs.

Clinical Biology of the Pituitary Adenoma

All endocrine glands are susceptible to neoplastic growth, yet the health consequences of these neoplasms differ between endocrine tissues. Pituitary neoplasms are highly prevalent and overwhelmingly benign, exhibiting a spectrum of diverse behaviors and impact on health. To understand the clinical biology of these common yet often innocuous neoplasms, we review pituitary physiology and adenoma epidemiology, pathophysiology, behavior, and clinical consequences. The anterior pituitary develops in response to a range of complex brain signals integrating with intrinsic ectodermal cell transcriptional events that together determine gland growth, cell type differentiation, and hormonal production, in turn maintaining optimal endocrine health. Pituitary adenomas occur in 10% of the population; however, the overwhelming majority remain harmless during life. Triggered by somatic or germline mutations, disease-causing adenomas manifest pathogenic mechanisms that disrupt intrapituitary signaling to promote benign cell proliferation associated with chromosomal instability. Cellular senescence acts as a mechanistic buffer protecting against malignant transformation, an extremely rare event. It is estimated that fewer than one-thousandth of all pituitary adenomas cause clinically significant disease. Adenomas variably and adversely affect morbidity and mortality depending on cell type, hormone secretory activity, and growth behavior. For most clinically apparent adenomas, multimodal therapy controlling hormone secretion and adenoma growth lead to improved quality of life and normalized mortality. The clinical biology of pituitary adenomas, and particularly their benign nature, stands in marked contrast to other tumors of the endocrine system, such as thyroid and neuroendocrine tumors.

Recommendations for the diagnosis and radiological follow-up of pituitary neuroendocrine tumours

Pituitary neuroendocrine tumours (PitNETs) constitute a heterogeneous group of tumours with a gradually increasing incidence, partly accounted for by more sensitive imaging techniques and more extensive experience in neuroradiology in this regard. Although most PitNETs are indolent, some exhibit aggressive behaviour, and recurrence may be seen after surgical removal. The changes introduced in the WHO classification in 2017 and terminological debates in relation to neuroendocrine tumours warrant an update of the guidelines for the diagnosis, preoperative and postoperative management, and follow-up of response to treatment of PitNETs. This multidisciplinary document, an initiative of the Neuroendocrinology area of the Sociedad Española de Endocrinología y Nutrición [Spanish Society of Endocrinology and Nutrition] (SEEN), focuses on neuroimaging studies for the diagnosis, prognosis and follow-up of PitNETs. The basic requirements and elements that should be covered by magnetic resonance imaging are described, and a minimum radiology report to aid clinicians in treatment decision-making is proposed. This work supplements the consensus between the Neuroendocrinology area of the SEEN and the Sociedad Española de Anatomía Patológica [Spanish Society of Pathology] (SEAP) for the pathological study of PitNETs.

A current perspective of pituitary adenoma MRI characteristics: a review

INTRODUCTION

MR imaging is an essential and fundamental tool in the diagnosis, management, and follow-up of patients with pituitary adenomas (PAs). Recent advances have continued to enhance the usefulness of this imaging modality.

AREAS COVERED

This article focuses on signal intensity patterns of PAs and associated clinical characteristics, vertical extension patterns, and cavernous sinus invasion with a special focus on the clinical implications that arise. A search using Medline and Google Scholar was conducted using different combinations of relevant keywords, giving preference to recent publications.

EXPERT OPINION

A higher proportion of GH-secreting PAs are hypointense on T2 weighted images compared to other tumor subtypes. Hypointense tumors are generally smaller compared to hyperintense ones, and among the GH-secreting subgroup, a better response to somatostatin analogue treatment was noted together with an association for a densely granulated pattern. Nonfunctional PAs show a predilection to extend upwards while GH-secreting PAs and prolactinomas show a predominantly inferior extension growth pattern. Further studies to better understand the mechanisms responsible for this behavior are anticipated. Further development, refining and validation of predictive scoring systems for tumor behavior might be useful adjuncts in the management of patients with PAs.

11C-methionine PET aids localization of microprolactinomas in patients with intolerance or resistance to dopamine agonist therapy

PURPOSE

To assess the potential for ¹¹C-methionine PET (Met-PET) coregistered with volumetric magnetic resonance imaging (Met-PET/MR^CR) to inform clinical decision making in patients with poorly visualized or occult microprolactinomas and dopamine agonist intolerance or resistance.

PATIENTS AND METHODS

Thirteen patients with pituitary microprolactinomas, and who were intolerant (n = 11) or resistant (n = 2) to dopamine agonist therapy, were referred to our specialist pituitary centre for Met-PET/MR^CR between 2016 and 2020. All patients had persistent hyperprolactinemia and were being considered for surgical intervention, but standard clinical MRI had shown either no visible adenoma or equivocal appearances.

RESULTS

In all 13 patients Met-PET/MR^CR demonstrated a single focus of avid tracer uptake. This was localized either to the right or left side of the sella in 12 subjects. In one patient, who had previously undergone surgery for a left-sided adenoma, recurrent tumor was unexpectedly identified in the left cavernous sinus. Five patients underwent endoscopic transsphenoidal selective adenomectomy, with subsequent complete remission of hyperprolactinaemia and normalization of other pituitary function; three patients are awaiting surgery. In the patient with inoperable cavernous sinus disease PET-guided stereotactic radiosurgery (SRS) was performed with subsequent near-normalization of serum prolactin. Two patients elected for a further trial of medical therapy, while two declined surgery or radiotherapy and chose to remain off medical treatment.

CONCLUSIONS

In patients with dopamine agonist intolerance or resistance, and indeterminate pituitary MRI, molecular (functional) imaging with Met-PET/MR^CR can allow precise localization of a microprolactinoma to facilitate selective surgical adenomectomy or SRS.

Italian Association of Clinical Endocrinologists (AME) and International Chapter of Clinical Endocrinology (ICCE). Position statement for clinical practice: prolactin-secreting tumors

Prolactinomas are the most frequent pituitary adenomas. Prolactinoma may occur in different clinical settings and always require an individually tailored approach. This is the reason why a panel of Italian neuroendocrine experts was charged with the task to provide indications for the diagnostic and therapeutic approaches that can be easily applied in different contexts. The document provides 15 recommendations for diagnosis and 54 recommendations for treatment, issued according to the GRADE system. The level of agreement among panel members was formally evaluated by RAND-UCLA methodology. In the last century, prolactinomas represented the paradigm of pituitary tumors for which the development of highly effective drugs obtained the best results, allowing to avoid neurosurgery in most cases. The impressive improvement of neurosurgical endoscopic techniques allows a far better definition of the tumoral tissue during surgery and the remission of endocrine symptoms in many patients with pituitary tumors. Consequently, this refinement of neurosurgery is changing the therapeutic strategy in prolactinomas, allowing the definitive cure of some patients with permanent discontinuation of medical therapy.

First-line surgery in prolactinomas: lessons from a long-term follow-up study in a tertiary referral center

CONTEXT

Although consensus guidelines recommend dopamine agonists (DAs) as the first-line approach in prolactinomas, some patients may opt instead for upfront surgery, with the goal of minimizing the need for continuation of DAs over the long term. While this approach can be recommended in selected patients with a microprolactinoma, the indication for upfront surgery in macroprolactinomas remains controversial, with limited long-term data in large cohorts. We aimed at elucidating whether first-line surgery is equally safe and effective for patients with micro- or macroprolactinomas not extending beyond the median carotid line (i.e., Knosp grade ≤ 1).

METHODOLOGY

Retrospective study of patients with prolactinomas Knosp grade ≤ 1 treated with upfront surgery. The primary endpoint was patients' dependence on DAs at last follow-up. The secondary endpoint was postoperative complications. Independent risk factors for long-term dependence on DAs were analyzed.

RESULTS

A microadenoma was noted in 45 patients (52%) and a macroadenoma in 41 (48%), with 17 (20%) harboring a Knosp grade 1 prolactinoma. Median follow-up was 80 months. First-line surgery resulted in long-term remission in 31 patients (72%) with a microprolactinoma and in 18 patients (45%) with a macroprolactinoma (p = 0.02). DA therapy was ultimately required in 11 patients (24%) with microadenomas vs. 20 (49%) with macroadenomas (p = 0.03). As for the latter, DA was required in 13 patients (76%) with Knosp grade 1 macroadenomas vs. 7 patients (29%) with Knosp grade 0 macroadenomas (p = 0.004). There was no mortality, and morbidity was minimal. Knosp grade 1 prolactinomas (OR 7.3, 95% CI 1.4-37.7, p = 0.02) but not adenoma size (i.e., macroprolactinomas) were an independent predictor of long-term dependence on DAs.

CONCLUSIONS

First-line surgery in patients with microprolactinomas or macroprolactinomas Knosp grade 0 resulted in a good chance of non-dependency on DA therapy. However, in patients with prolactinomas Knosp grade 1, first-line surgery cannot be recommended, as adjuvant DA therapy after surgery is required in the majority of them over the long term.

Surgery is a safe, effective first-line treatment modality for noninvasive prolactinomas

PURPOSE

Dopamine agonists (DAs) have long been the recommended first-line treatment for prolactinoma. Given the remarkable developments in surgical techniques, however, surgery is on the rise. We compared the treatment outcomes of patients with noninvasive prolactinomas receiving two different initial treatments (DAs and transsphenoidal surgery).

METHODS

We reviewed 745 patients with hyperprolactinemia or pituitary tumors treated from 2004 to 2020 at Chonnam National University Hwasun Hospital and identified 310 with prolactinomas. After selecting patients who had pituitary tumors with Knosp grade 0 to 1 with follow-up period over 1 year, 70 patients (29 who underwent surgery and 41 who received DAs as the initial treatment) were finally included for a comparative study.

RESULTS

The surgery group exhibited better outcomes in terms of DA-free remission and the structural response, although the tumor size was significantly larger than in the DA group. The groups exhibited comparable results in terms of symptom control and the biochemical response. Univariate and multivariate analyses indicated that surgery as the initial treatment modality provided significantly better clinical outcomes in terms of DA-free remission. In the surgery group, a postoperative prolactin level < 10 ng/mL was the only significant predictor of DA-free remission.

CONCLUSIONS

Transsphenoidal surgery showed comparable clinical outcomes in patients with prolactinomas, and low complication rates. The decision regarding the first-line treatment modality for non-invasive prolactinomas should be made on an individual basis.

What to Do with Incidentally Discovered Pituitary Abnormalities?

Pituitary incidentalomas are discovered in approximately 10% to 40% of brain images. A complete patient history, physical examination, and dedicated pituitary function testing are needed, and subsequent results should lead to appropriate patient management. However, most lesions are asymptomatic pituitary adenomas or Rathke cleft cysts with a benign course. Many lesions can be clinically significant, including prolactinomas or other pituitary adenomas that warrant specific pituitary disease treatment. In other cases, mass effect causing visual compromise or refractory headache indicates a need for surgery. Here, various facets of a complex evaluation and treatment algorithm for pituitary incidentalomas are reviewed.

Prolactinomas

Hyperprolactinemia, defined by a level of serum prolactin above the standard upper limit of normal range, is a common finding in clinical practice and prolactinomas are the main pathological cause. Prolactinomas lead to signs and symptoms of hormone oversecretion, such as galactorrhea and hypogonadism, as well as symptoms of mass effect, including visual impairment, headaches and intracranial hypertension. Diagnosis involves prolactin measurement and sellar imaging, but several pitfalls are involved in this evaluation, which may difficult the proper management. Treatment is medical in the majority of cases, consisting of dopamine agonists, which present high response rates, with a very favorable safety profile. Major adverse effects that should be monitored consist of cardiac valvulopathy and impulse control disorders. Other treatment options include surgery and radiotherapy. Temozolomide may be used for aggressive or malignant carcinomas. Finally, pregnancy outcomes are similar to general population even when dopamine agonist treatment is maintained.

Tumor volume improves preoperative differentiation of prolactinomas and nonfunctioning pituitary adenomas

PURPOSE

Both prolactinomas and nonfunctioning adenomas (NFAs) can present with hyperprolactinemia. Distinguishing them is critical because prolactinomas are effectively managed with dopamine agonists, whereas compressive NFAs are treated surgically. Current guidelines rely only on serum prolactin (PRL) levels, which are neither sensitive nor specific enough. Recent studies suggest that accounting for tumor volume may improve diagnosis. The objective of this study is to investigate the diagnostic utility of PRL, tumor volume, and imaging features in differentiating prolactinoma and NFA.

METHODS

Adult patients with pathologically confirmed prolactinoma (n = 21) or NFA with hyperprolactinemia (n = 58) between 2013 and 2020 were retrospectively identified. Diagnostic performance of clinical and imaging variables was analyzed using receiver-operating characteristic curves to calculate area under the curve (AUC).

RESULTS

Tumor volume and PRL positively correlated for prolactinoma (r = 0.4839, p = 0.0263) but not for NFA (r = 0.0421, p = 0.7536). PRL distinguished prolactinomas from NFAs with an AUC of 0.8892 (p < 0.0001) and optimal cut-off value of 62.45 ng/ml, yielding a sensitivity of 85.71% and specificity of 94.83%. The ratio of PRL to tumor volume had an AUC of 0.9647 (p < 0.0001) and optimal cut-off value of 21.62 (ng/ml)/cm³ with sensitivity of 100% and specificity of 82.76%. Binary logistic regression found that PRL was a significant positive predictor of prolactinoma diagnosis, whereas tumor volume, presence of cavernous sinus invasion, and T2 hyperintensity were significant negative predictors. The regression model had an AUC of 0.9915 (p < 0.0001).

CONCLUSIONS

Consideration of tumor volume improves differentiation between prolactinomas and NFAs, which in turn leads to effective management.

Radiomics With Ensemble Machine Learning Predicts Dopamine Agonist Response in Patients With Prolactinoma

CONTEXT

Early identification of the response of prolactinoma patients to dopamine agonists (DA) is crucial in treatment planning.

OBJECTIVE

To develop a radiomics model using an ensemble machine learning classifier with conventional magnetic resonance images (MRIs) to predict the DA response in prolactinoma patients.

DESIGN

Retrospective study.

SETTING

Severance Hospital, Seoul, Korea.

PATIENTS

A total of 177 prolactinoma patients who underwent baseline MRI (109 DA responders and 68 DA nonresponders) were allocated to the training (n = 141) and test (n = 36) sets. Radiomic features (n = 107) were extracted from coronal T2-weighed MRIs. After feature selection, single models (random forest, light gradient boosting machine, extra-trees, quadratic discrimination analysis, and linear discrimination analysis) with oversampling methods were trained to predict the DA response. A soft voting ensemble classifier was used to achieve the final performance. The performance of the classifier was validated in the test set.

RESULTS

The ensemble classifier showed an area under the curve (AUC) of 0.81 [95% confidence interval (CI), 0.74-0.87] in the training set. In the test set, the ensemble classifier showed an AUC, accuracy, sensitivity, and specificity of 0.81 (95% CI, 0.67-0.96), 77.8%, 78.6%, and 77.3%, respectively. The ensemble classifier achieved the highest performance among all the individual models in the test set.

CONCLUSIONS

Radiomic features may be useful biomarkers to predict the DA response in prolactinoma patients.

Long-term IGF-1 monitoring in prolactinoma patients treated with cabergoline might not be indicated

PURPOSE

Cabergoline (CAB) therapy for prolactinomas has been associated with serum IGF-1 levels modifications, with recent reports indicating a paradoxical increase of IGF-1 levels during ongoing therapy. As a result, IGF-1 measurement has been proposed not only at diagnosis of a prolactinoma, but also during follow-up. In this follow-up study on prolactinoma patients with chronic CAB therapy, we investigated whether there are long-term changes in IGF-1 levels that necessitate continuous monitoring.

METHODS

We reviewed our institutional database on prolactinoma patients with long-term CAB therapy, in whom IGF-1 levels were measured at baseline, at 3-months follow-up and in the long term.

RESULTS

Chronic CAB therapy was noted in 20 patients (13 men, 7 women). Median (±SD) age was 43.5 ± 12.6 years. 17 (85%) patients presented with a macroprolactinoma. Median CAB treatment time was 75 ± 43 months (range 24-187). Median IGF-1 levels increased at last follow-up, though not significantly; from 122 ± 37 ng/ml (IQR 104-160 ng/ml) to 133 ± 54 (IQR 121-162 ng/ml), p = 0.10. Thereby, 18 (90%) patients showed normal serum IGF-1 levels adjusted for age, one (5%) patient above (1.05 × ULN) and 1 (5%) patient below the normal range (0.34 × ULN). No patient was or became symptomatic of acromegaly.

CONCLUSION

Our long-term results indicate that chronic treatment with CAB in prolactinoma patients does not significantly modify serum IGF-1 levels. Bearing in mind the sample size of this study, continuing IGF-1 monitoring is not indicated in prolactinoma patients with long-term CAB therapy.

Advances in the Imaging of Pituitary Tumors

In most patients with pituitary adenomas magnetic resonance imaging (MRI) is essential to guide effective decision-making. T1- and T2-weighted sequences allow the majority of adenomas to be readily identified. Supplementary MR sequences (e.g. FLAIR; MR angiography) may also help inform surgery. However, in some patients MRI findings are 'negative' or equivocal (e.g. with failure to reliably identify a microadenoma or to distinguish postoperative change from residual/recurrent disease). Molecular imaging [e.g. ¹¹C-methionine PET/CT coregistered with volumetric MRI (Met-PET/MR^CR)] may allow accurate localisation of the site of de novo or persistent disease to guide definitive treatment (e.g. surgery or radiosurgery).

Neuroimaging and radiation exposure in pregnancy

Physiologic changes occurring in pregnancy and postpartum can have secondary effects on the maternal nervous system. While most alterations to neurologic function during pregnancy are transient, there is an elevated risk for more serious complication in the peripartum period, such as cerebrovascular events or exacerbation of preexisting neurologic conditions. Due to the morbidity and mortality associated with these neurologic manifestations in some cases, timely diagnostic evaluation is essential. In the pregnant population, the use of diagnostic techniques such as computed tomography (CT) and magnetic resonance imaging (MRI), commonly employed to evaluate emergent neurologic abnormalities, requires special consideration of the potential risks associated with prenatal exposure. This review discusses several neurologic conditions affecting women during pregnancy for which diagnostic imaging may be warranted. Concerns relating to CT and MRI procedures, radiation exposure in utero, and exposure to intravenous contrast by placental transfer and breastfeeding are also reviewed.