Summary Objective To describe clinical practice experience of 11C‐Metomidate PET/CT as an adjunct to adrenal vein sampling (AVS) in the lateralization of aldosterone‐producing adenomas (APA) in primary aldosteronism (PA). Context Accurate lateralization of APA in the setting of PA offers the potential for surgical cure and improved long‐term cardiovascular outcomes. Challenges associated with AVS, the current gold standard lateralization modality, mean that only a small proportion of potentially eligible patients currently make it through to surgery. This has prompted consideration of alternative strategies for lateralization, including the application of novel molecular PET tracers such as 11C‐Metomidate. Design Clinical Service Evaluation/Retrospective audit. Patients Fifteen individuals with a confirmed diagnosis of PA, undergoing lateralization with 11C‐Metomidate PET/CT prior to final clinical decision on surgical vs medical management. Measurements All patients underwent screening aldosterone renin ratio (ARR), followed by confirmatory testing with the seated saline infusion test, according to Endocrine Society Clinical Practice Guidelines. Adrenal glands were imaged using dedicated adrenal CT. 11C‐Metomidate PET/CT was undertaken due to equivocal or failed AVS. Management outcomes were assessed by longitudinal measurement of blood pressure, ARR, number of hypertensive medications following adrenalectomy or institution of medical therapy. Results We describe the individual lateralization and clinical outcomes for 15 patients with PA. Conclusion 11C‐Metomidate PET/CT in conjunction with adrenal CT and AVS provided useful information which aided clinical decision‐making for PA within a multidisciplinary hypertension clinic.

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Primary aldosteronism (PA) due to a unilateral aldosterone-producing adenoma is a common cause of hypertension. This can be cured, or greatly improved, by adrenal surgery. However, the invasive nature of the standard pre-surgical investigation contributes to fewer than 1% of patients with PA being offered the chance of a cure. The primary objective of our prospective study of 143 patients with PA (NCT02945904) was to compare the accuracy of a non-invasive test, [11C]metomidate positron emission tomography computed tomography (MTO) scanning, with adrenal vein sampling (AVS) in predicting the biochemical remission of PA and the resolution of hypertension after surgery. A total of 128 patients reached 6- to 9-month follow-up, with 78 (61%) treated surgically and 50 (39%) managed medically. Of the 78 patients receiving surgery, 77 achieved one or more PA surgical outcome criterion for success. The accuracies of MTO at predicting biochemical and clinical success following adrenalectomy were, respectively, 72.7 and 65.4%. For AVS, the accuracies were 63.6 and 61.5%. MTO was not significantly superior, but the differences of 9.1% (95% confidence interval = −6.5 to 24.1%) and 3.8% (95% confidence interval = −11.9 to 9.4) lay within the pre-specified −17% margin for non-inferiority (P = 0.00055 and P = 0.0077, respectively). Of 24 serious adverse events, none was considered related to either investigation and 22 were fully resolved. MTO enables non-invasive diagnosis of unilateral PA.

Decision-making in pituitary disease is critically dependent on high quality imaging of the sella and parasellar region. Magnetic resonance imaging (MRI) is the investigation of choice and, for the majority of patients, combined T1 and T2 weighted sequences provide the information required to allow surgery, radiotherapy (RT) and/or medical therapy to be planned and long-term outcomes to be monitored. However, in some cases standard clinical MR sequences are indeterminate and additional information is needed to help inform the choice of therapy for a pituitary adenoma (PA). This article reviews current recommendations for imaging of PA, examines the potential added value that alternative MR sequences and/or CT can offer, and considers how the use of functional/molecular imaging might allow definitive treatment to be recommended for a subset of patients who would otherwise be deemed unsuitable for (further) surgery and/or RT.

Background Pituitary adenomas can give rise to a variety of clinical disorders and surgery is often the primary treatment option. However, preoperative magnetic resonance imaging (MRI) does not always reliably identify the site of an adenoma. In this setting molecular (functional) imaging (e.g. 11C-methionine PET/CT) may help with tumor localisation, although interpretation of these 2D images can be challenging. 3D printing of anatomicalal models for other indications has been shown to aid surgical planning and improve patient understanding of the planned procedure. Here, we explore the potential utility of four types of 3D printing using PET/CT and co-registered MRI for visualising pituitary adenomas. Methods A 3D patient-specific model based on a challenging clinical case was created by segmenting the pituitary gland, pituitary adenoma, carotid arteries and bone using contemporary PET/CT and MR images. The 3D anatomical models were printed using VP, MEX, MJ and PBF 3D printing methods. Different anatomicalal structures were printed in color with the exception of the PBF anatomical model where a single color was used. The anatomical models were compared against the computer model to assess printing accuracy. Three groups of clinicians (endocrinologists, neurosurgeons and ENT surgeons) assessed the anatomical models for their potential clinical utility. Results All of the printing techniques produced anatomical models which were spatially accurate, with the commercial printing techniques (MJ and PBF) and the consumer printing techniques (VP and MEX) demonstrating comparable findings (all techniques had mean spatial differences from the computer model of < 0.6 mm). The MJ, VP and MEX printing techniques yielded multicolored anatomical models, which the clinicians unanimously agreed would be preferable to use when talking to a patient; in contrast, 50%, 40% and 0% of endocrinologists, neurosurgeons and ENT surgeons respectively would consider using the PBF model. Conclusion 3D anatomical models of pituitary tumors were successfully created from PET/CT and MRI using four different 3D printing techniques. However, the expert reviewers unanimously preferred the multicolor prints. Importantly, the consumer printers performed comparably to the commercial MJ printing technique, opening the possibility that these methods can be adopted into routine clinical practice with only a modest investment.

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OBJECTIVEThe object of this study was to determine if revision transsphenoidal surgery (TSS), guided by 11C-methionine PET/CT coregistered with volumetric MRI (Met-PET/MRCR), can lead to remission in patients with persistent acromegaly due to a postoperative lateral disease remnant.METHODSThe authors identified 9 patients with persistent acromegaly following primary intervention (TSS ± medical therapy ± radiotherapy) in whom further surgery had initially been discounted because of equivocal MRI findings with suspected lateral sellar and/or parasellar disease (cases with clear Knosp grade 4 disease were excluded). All patients underwent Met-PET/MRCR. Scan findings were used by the pituitary multidisciplinary team to inform decision-making regarding repeat surgery. Revision TSS was performed with wide lateral exploration as guided by the PET findings. Endocrine reassessment was performed at 6–10 weeks after surgery, with longitudinal follow-up thereafter.RESULTSMet-PET/MRCR revealed focal tracer uptake in the lateral sellar and/or parasellar region(s) in all 9 patients, which correlated with sites of suspected residual tumor on volumetric MRI. At surgery, tumor was identified and resected in 5 patients, although histological analysis confirmed somatotroph tumor in only 4 cases. In the other 4 patients, no definite tumor was seen, but equivocal tissue was removed. Despite the uncertainty at surgery, all patients showed immediate significant improvements in clinical and biochemical parameters. In the 8 patients for whom long-term follow-up data were available, insulin-like growth factor 1 (IGF-1) was ≤ 1.2 times the upper limit of normal (ULN) in all subjects and ≤ 1 times the ULN in 6 subjects, and these findings have been maintained for up to 28 months (median 8 months, mean 13 months) with no requirement for adjunctive medical therapy or radiotherapy. No patient suffered any additional pituitary deficit or other complication of surgery.CONCLUSIONSThis study provides proof of concept that Met-PET/MRCR can be helpful in the evaluation of residual lateral sellar/parasellar disease in persistent acromegaly and facilitate targeted revision TSS in a subgroup of patients.