Implementation of functional imaging using 11C-methionine PET-CT co-registered with MRI for advanced surgical planning and decision making in prolactinoma surgery

Clinical use of [18F]fluoro-ethyl-L-tyrosine PET co-registered with MRI for localizing prolactinoma remnants

PURPOSE

To assess the utility of [18F]fluoroethyl-L-tyrosine PET co-registered with magnetic resonance imaging ([18F]FET-PET/MRICR) in patients with difficult-to-localize prolactinoma to inform clinical decision-making and (surgical) treatment planning.

METHODS

Retrospective cohort study of 17 consecutive patients with prolactinoma undergoing [18F]FET-PET/MRICR between October 2020 and September 2022 for either (1) additional information in case of difficult-to-visualize remnants after prior transsphenoidal surgery (TSS), or pharmacological treatment, or (2) radiological diagnosis in absence of a (clear) adenoma on diagnostic/post-treatment conventional MRI.

RESULTS

[18F]FET-PET/MRICR identified a lesion in 14/17 patients, yet failed to identify active lesions in 2 patients with negative conventional MRI despite prolactin > 7.5 times upper limit of normal. [18F]FET-PET/MRICR results were inconclusive in 1 patient due to diffuse tracer uptake 10 weeks post-surgery. [18F]FET-PET/MRICR was completely concordant with a suspected lesion on conventional MRI in 10/17 patients, and partially concordant in 3/17 patients. New foci were identified in 4/17 patients. The [18F]FET-PET/MRICR conclusions influenced clinical shared decision-making in 15/17 patients, of whom 7 patients underwent TSS and 8 refrained from TSS. One patient underwent TSS despite negative [18F]FET-PET/MRICR, and one patient underwent additional imaging. Intraoperative findings corresponded with [18F]FET-PET/MRICR in 5/8 patients, and immunohistochemistry was positive in 5/8 patients. The treatment goal was achieved in 7/8 patients, and remission was achieved in 5/7 patients in whom total resection was considered feasible.

CONCLUSION

[18F]FET-PET/MRICR can be of added value in the preoperative decision-making process for selected patients with difficult-to-localize prolactinoma (remnants), or patients lacking a substrate on conventional MRI.

18F-fluoro-ethyl-tyrosine PET co-registered with MRI in patients with persisting acromegaly

OBJECTIVE

To report our experience with 18F-fluoro-ethyl-tyrosine (FET) positron emission tomography-computed tomography (PET-CT) co-registered with magnetic resonance imaging (MRI) (FET-PET/MRICR) in the care trajectory for persistent acromegaly.

DESIGN

Prospective case series.

PATIENTS

Ten patients with insufficiently controlled acromegaly referred to our team to evaluate surgical options.

MEASUREMENTS

FET-PET/MRICR was used to support decision-making if MRI alone and multidisciplinary team evaluation did not provide sufficient clarity to proceed to surgery.

RESULTS

FET-PET/MRICR showed suspicious (para)sellar tracer uptake in all patients. In five patients FET-PET/MRICR was fully concordant with conventional MRI, and in one patient partially concordant. FET-PET/MRICR identified suggestive new foci in four other patients. Surgical re-exploration was performed in nine patients (aimed at total resection (6), debulking (2), diagnosis (1)), and one patient underwent radiation therapy. In 7 of 9 (78%) operated patients FET-PET/MRICR findings were confirmed intraoperatively, and in six (67%) also histologically. IGF-1 decreased significantly in eight patients (89%). All patients showed clinical improvement. Complete biochemical remission was achieved in three patients (50% of procedures in which total resection was anticipated feasible). Biochemistry improved in five and was unchanged in one patient. No permanent complications occurred. At six months, optimal outcome (preoperative intended goal achieved without permanent complications) was achieved in six (67%) patients and an intermediate outcome (goal not achieved, but no complications) in the other three patients.

CONCLUSIONS

In patients with persisting acromegaly without a clear surgical target on MRI, FET-PET/MRICR is a new tracer to provide additional information to aid decision-making by the multidisciplinary pituitary team.

[18F]FET PET/MRI: An Accurate Technique for Detection of Small Functional Pituitary Tumors

Small functional pituitary tumors can cause severely disabling symptoms and early death. The gold standard diagnostic approach includes laboratory tests and MRI, with or without inferior petrosal sinus sampling (IPSS). In up to 40% of patients, however, the source of excess hormone production remains unidentified or uncertain. This excludes patients from surgical, Gamma Knife, and CyberKnife therapy and adversely affects overall cure rates. We here assess the diagnostic yield of O-(2-[18F]fluoroethyl)-l-tyrosine ([18F]FET) PET/MRI for detection of small functional pituitary tumors in these patients. Methods: This retrospective analysis included patients with Cushing disease (CD) but prior negative or inconclusive MRI results who underwent [18F]FET PET/MRI between February 1, 2021, and December 1, 2022. PET/MR images and MR images alone were evaluated by experienced nuclear radiologists, neuroradiologists, or radiologists. Postoperative tissue analysis (when performed) was used as a reference standard to assess diagnostic metrics (i.e., sensitivity and positive predictive value). Results were also compared with previously obtained MR images, preceding IPSS, and clinical or biochemical follow-up. Results: Twenty-two patients (68% female; mean age ± SD, 48 ± 15 y; range, 24-68 y) were scanned. All patients showed a clear metabolic focus on [18F]FET PET, whereas reading of the MRI alone yielded a suspected lesion in only 50%. Fifteen patients underwent surgery directed at the [18F]FET-positive focus. Tissue analysis confirmed a pituitary adenoma/pituitary neuroendocrine tumor of the corticotroph cell type (TPIT lineage) in 10 of 15 and a pituicytoma in 1 of 15, rendering a sensitivity of 100% and a positive predictive value of 73%. Lateralization was more accurate with [18F]FET PET/MRI than with IPSS in 33%. Twelve of 16 (75%) patients who received surgical, Gamma Knife, or CyberKnife therapy after [18F]FET PET/MRI reached short-term remission. Conclusion: [18F]FET PET/MRI shows a high diagnostic yield for localizing small functional pituitary tumors. This multimodal imaging technique provides a welcome improvement for diagnosis, planning of surgery, and clinical outcome in patients with Cushing disease, particularly those with repeated negative or inconclusive MRI results with or without IPSS.

Real-world experience with 11C-methionine positron emission tomography in the management of acromegaly

BACKGROUND

L-[methyl-11C]-methionine-positron emission tomography (Met-PET) is a potentially important imaging adjunct in the diagnostic workup of pituitary adenomas, including somatotroph tumors. Met-PET can identify residual or occult disease and make definitive therapies accessible to a subgroup of patients who would otherwise require lifelong medical therapy. However, existing data on its use are still limited to small case series. Here, we report the largest single-center experience (n = 61) in acromegaly.

METHODS

A total of 189 cases of acromegaly were referred to our national Met-PET service in the last 12 years. For this analysis, we have reviewed outcomes in those 61 patients managed exclusively by our multidisciplinary team (single center, single surgeon). Referral indications were as follows: indeterminate magnetic resonance imaging (MRI; n = 38, 62.3%), occult residual (n = 14, 23.0%), (radio-)surgical planning (n = 6, 9.8%), and occult de novo tumor (n = 3, 4.9%).

RESULTS

A total of 33/61 patients (54.1%) underwent PET-guided surgery. Twenty-four of 33 patients (72.7%) achieved complete biochemical remission following (re-)surgery. Insulin-like growth factor 1 levels were reduced to <2 × upper limit of normal (ULN) in 6 of the remaining 9 cases, 3 of whom achieved levels of <1.1 × ULN compared with mean preoperative levels of 2.4 × ULN (SD 0.8) for n = 9. Only 3 patients developed single new hormonal deficits (gonadotropic/thyrotropic insufficiency). There were no neurovascular complications after surgery.

CONCLUSION

In patients with persistent/recurrent acromegaly or occult tumors, Met-PET can facilitate further targeted intervention (surgery/radiosurgery). This led to complete remission in most cases (24/33) or significant improvement with comparatively low risk of complications. L-[methyl-11C]-methionine-positron emission tomography should therefore be considered in all patients who are potential candidates for further surgical intervention but present no clear target on MRI.

Multidisciplinary Team Care in Pituitary Tumours

The optimal care for patients with pituitary tumours is best provided in a multidisciplinary and collaborative environment, which requires the contribution of multiple medical specialties working together. The benefits and advantages of the pituitary multidisciplinary team (MDT) are broad, and all relevant international consensus and guidelines in the field recommend that patients with pituitary tumours should always be managed in a MDT. Endocrinologists and neurosurgeons are normally the leading specialties within the pituitary MDT, supported by many other specialties with significant contributions to the diagnosis and management of pituitary tumours, including neuropathology, neuroradiology, neuro-ophthalmology, and otorhinolaryngology, among others. Here, we review the literature concerning the concepts of Pituitary MDT/Pituitary Tumour Centre of Excellence (PTCOE) in terms of their mission, goals, benefits, structure, proposed models of function, and barriers, and we also provide the views of different specialists involved in our Pituitary MDT.

Prospective Integrated Individualized Clinical Decision-making and Outcome Evaluation for Surgery in Patients with Acromegaly: A New Paradigm?

BACKGROUND

Growth-hormone-producing pituitary adenomas have variable likelihood for biochemical remission (BR). During preoperative counseling, individual estimated surgical likelihoods/risks should be balanced against alternative (medical) treatments, which is necessary for accurate outcome presentation. Preoperative estimation of BR or total resection (TR) likelihoods have not been reported, resulting in extrapolation of individual outcomes.

AIMS

To share an innovative outcome reporting paradigm by integrating surgical decision-making, and expected/realized results, resulting from the Value-Based Health Care (VBHC) care path with periodical performance evaluation and care innovation cycle.

METHODS

Prospective cohort study of consecutive patients with acromegaly undergoing surgery (January 2016-December 2020; postoperative follow-up ≥6 months) reporting on both classic, and novel innovative outcome evaluations.

RESULTS

Fifty eight patients (66 procedures) were included. Intended TR was achieved in 34/50 procedures, whereas intended debulking was achieved in 15/16 procedures. 38/66 procedures resulted in BR, and 4 procedures resulted in permanent complications. Achieving intended surgical goal was estimated preoperatively as likely in 33 (goal achieved (GA) in 28/33), potentially in 27 (GA in 19/27), and unlikely in 6 procedures (GA in 2/6). Integrated Outcome Square 1 (IOQ1) -intended effect achieved without complications- was achieved in 46/66 patients.

CONCLUSION

Implementation of the developed quality process positively affects preoperative individual shared decision-making, resulting in improved (individual) outcomes, particularly in complex patients for whom preoperative chances are not fully reflected by tumor size and KNOSP grade, e.g., reoperations, or other challenging circumstances identified during preoperative counseling. Through repeated evaluations, our own team's knowledge increased, allowing for improved individualized treatment strategies.

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.

Consecutive resections of double pituitary adenoma for resolution of Cushing disease: illustrative case

BACKGROUND

Double pituitary adenomas are rare presentations of two distinct adenohypophyseal lesions seen in <1% of surgical cases. Increased rates of recurrence or persistence are reported in the resection of Cushing microadenomas and are attributed to the small tumor size and localization difficulties. The authors report a case of surgical treatment failure of Cushing disease because of the presence of a secondary pituitary adenoma.

OBSERVATIONS

A 32-year-old woman with a history of prolactin excess and pituitary lesion presented with oligomenorrhea, weight gain, facial fullness, and hirsutism. Urinary and nighttime salivary cortisol elevation were elevated. Magnetic resonance imaging confirmed a 4-mm3 pituitary lesion. Inferior petrosal sinus sampling was diagnostic for Cushing disease. Primary endoscopic endonasal transsphenoidal resection was performed to remove what was determined to be a lactotroph-secreting tumor on immunohistochemistry with persistent hypercortisolism. Repeat resection yielded a corticotroph-secreting tumor and postoperative hypoadrenalism followed by long-term normalization of the hypothalamic-pituitary-adrenal axis.

LESSONS

This case demonstrates the importance of multidisciplinary management and postoperative hormonal follow-up in patients with Cushing disease. Improved strategies for localization of the active tumor in double pituitary adenomas are essential for primary surgical success and resolution of endocrinopathies.

Care trajectories of surgically treated patients with a prolactinoma: why did they opt for surgery?

PURPOSE

To describe care trajectories in patients with prolactinoma, aiming to clarify the rationale for surgery.

METHODS

Retrospective observational cohort study of consecutive patients with prolactinoma undergoing surgery from 2017 to 2019 at the referral center (RC), prior to surgery being considered a viable treatment option (i.e. PRolaCT study). Demographics and clinical data (type and duration of pretreatment and surgical indications, goals, and outcomes) were collected from patient records. Care trajectories were divided into three phases: (1) diagnosis and initial treatment, (2) endocrine treatment at the RC, and (3) surgical treatment.

RESULTS

40 patients were included (31 females (77.5%), median age 26.5 (14-63) years. Indications for surgery were dopamine agonist (DA) intolerance (n = 31, 77.5%), resistance (n = 6, 15.0%), and patient/physician preference (n = 3, 7.5%). Patients were pretreated with DA (n = 39 (97.5%)), and surgery (n = 3 (7.5%)). Median disease duration at surgery was 4 (0-27) years. Primary surgical goal was total resection in 38 patients (95.0%), of which biochemical remission was achieved 6 months postoperatively in 23 patients (62.2%), and clinical remission in 6 patients (16.2%), missing data n = 1.

CONCLUSION

Care trajectories were highly individualized based on patient and tumor characteristics, as well as the multidisciplinary team's assessment (need for alternative treatment, surgical chances and risks). Most patients were pretreated pharmacologically and had broad variation in timing of referral, undergoing surgery as last-resort treatment predominantly due to DA intolerance. High quality imaging and multidisciplinary consultations with experienced neurosurgeons and endocrinologists enabling treatment tailored to patients' needs were prerequisites for adequate counseling in treatment of patients with prolactinoma.

The utility of PET for detecting corticotropinomas in Cushing disease: a scoping review

While magnetic resonance imaging (MRI) is the current standard imaging method for diagnosing and localizing corticotropinomas in Cushing disease, it can fail to detect adenomas in up to 40% of cases. Recently, positron emission tomography (PET) has shown promise as a diagnostic tool to detect pituitary adenomas in Cushing disease. We perform a scoping review to characterize the uses of PET in diagnosing Cushing disease, with a focus on describing the types of PET investigated and defining PET-positive disease. A scoping review was conducted following the PRISMA-ScR guidelines. Thirty-one studies fulfilled our inclusion criteria, consisting of 10 prospective studies, 8 retrospective studies, 11 case reports, and 2 illustrative cases with a total of 262 patients identified. The most commonly utilized PET modalities in prospective/retrospective studies were FDG PET (n = 5), MET PET (n = 5), 68 Ga-DOTATATE PET (n = 2), 13N-ammonia PET (n = 2), and 68 Ga-DOTA-CRH PET (n = 2). MRI positivity ranged from 13 to 100%, while PET positivity ranged from 36 to 100%. In MRI-negative disease, PET positivity ranged from 0 to 100%. Five studies reported the sensitivity and specificity of PET, which ranged from 36 to 100% and 50 to 100%, respectively. PET shows promise in detecting corticotropinomas in Cushing disease, including MRI-negative disease. MET PET has been highly investigated and has demonstrated excellent sensitivity and specificity. However, preliminary studies with FET PET and 68 Ga-DOTA-CRH PET show promise for achieving high sensitivity and specificity and warrant further investigation.

Pituitary adenoma & nuclear medicine: Recent outcomes and ongoing developments

In order to explore pituitary adenoma (PA), magnetic resonance imaging (MRI) remains the cornerstone. However, there are some limitations and MRI can be non-conclusive. The development of additional imaging modalities like nuclear medicine explorations may help to confirm PA diagnosis, guide management and follow up. Nuclear medicine uses radiopharmaceuticals for imaging with single photon emission computed tomography (SPECT), or positron emission tomography (PET), coupled to CT scan. Radiopharmaceuticals products target specific cellular elements which allow to explore several biological pathways. Nuclear medicine may also be used for therapeutic purposes and recent developments of approach based on Peptide Receptor Radionuclide Therapy (PRRT) for treatment of aggressive PA and pituitary carcinoma will be reviewed. Several radiotracers have been studied in the context of PA, and the aim of this paper is to discuss their respective performances and clinical interest.