Recent advances in neuroendocrine imaging

[staticnrg]

Abstract

 

Purpose of review: Imaging is a critical component of both neuroendocrine lesion identification and anatomic delineation for treatment planning. Cross-sectional and isotopic-based physiologic imaging techniques have, to date, been the radiological modalities of choice. This review focuses on recent advances in imaging that are related to the evaluation of neuroendocrine abnormalities, in particular advances in MRI.

 

Recent findings: Magnetic-resonance perfusion examination of tissue characteristics in the pituitary, adrenal and thyroid glands indicates that, in many cases, adenomas of these glands have distinguishable hemodynamic characteristics relative to the parenchyma of the gland as a whole and to other lesions. Moreover, perfusion metrics might provide a basis for evaluating response to therapy (in the pituitary) and delineation of lesions in the adrenal and thyroid glands. Anisotropy-based imaging techniques show promise in providing direct, relevant information about pituitary tumor involvement of the adjacent cavernous sinuses.

 

Summary: The most recent methodological advances in the imaging of neuroendocrine disorder involves the continued development and application of MRI, in particular using pulse sequences, which provide a greater insight into the internal structure and physiology of the tissues interrogated, relative to standard sequences.

 

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Introduction

 

Neuroendocrine lesions are a heterogeneous group of entities that originate from endocrine cells and their related tissues ? the hallmark of which is the production of biogenic amines and polypeptide hormones. Identification of these lesions has been approached through a variety of modalities and methodologies including isotopic imaging [e.g. PET, 131I-metaiodobenzylguanidine (MIBG)] and anatomic imaging [e.g. computed tomography (CT), MRI, ultrasound]. Contrast between normal and abnormal tissues is discerned based on differences in tracer uptake (nuclear medicine), magnetic environment and characteristics of protons (MRI), differences in electron density between volumes of tissue (radiograph CT) and impedance/reflectivity of sound (ultrasound).

 

Pituitary

The clinical presentation of pituitary-related disorders can be ascribed predominantly to mass effect related to adjacent structures (e.g. the optic nerves), elevated hormone production [e.g. adrenocorticotropic hormone (ACTH)], decreased hormone production or inflammation/hemorrhage. Although the majority of pituitary tumors are adenomas, multiple other lesions (including Rathke's cleft cysts, craniopharyngiomas, lymphomas, metastasis, and dermoid tumors) might also affect pituitary function. Elevated levels of pituitary hormones are often associated with pituitary adenomas (which make up approximately 10% of all intracranial neoplasms) either directly (ACTH over production) or by the 'stalk effect' (elevated prolactin). Rarely, hyperthyroidism is reported as a consequence of a thyroid-stimulating hormone (TSH)-secreting pituitary adenoma [1,2].

 

Hypercortisolemia (Cushing's syndrome) may be divided (reviewed in [3]) into ACTH dependent/pituitary origin (70?80% of cases), ACTH dependent/ectopic secretion (EAS) and ACTH independent (adrenal or other source) ? these latter two (20?30% of cases) are discussed further. Laboratory testing, including high-dose dexamethasone suppression (HDSS) and corticotropin-releasing hormone (CRH) tests, is utilized to distinguish between Cushing's disease (pituitary adenoma overproduction of ACTH) and primary adrenal or ectopic ACTH production. The combination of CRH and HDSS tests has a very high sensitivity and specificity for identifying Cushing's disease. Recent results in 105 pediatric patients [4], using an overnight HDSS test, showed the discrimination of nearly all patients with pituitary tumors from nonpituitary sources (sensitivity: 97.5%; specificity: 100%).

 

In all patients with Cushing's disease, anatomic characterization and localization within the pituitary gland of microadenomas, as well as the tumor size and its relationships to adjacent structures (macroadenomas), are important for surgical planning. A critical issue in imaging pituitary macroadenomas is the question of cavernous sinus invasion, which can significantly affect surgical approach and management. Preoperative evaluation of the pituitary gland to determine the presence or absence of cavernous sinus invasion has rested largely on the relationship of tumor to the internal carotid arteries, and cavernous sinus venous compartments [5]. Yoneoka et al. [6??] have demonstrated the use of 3 T-based MRI using three-dimensional anisotropy contrast to identify cavernous sinus invasion. Cavernous sinus wall invasion by macroadenomas interferes with the uniformity of nerve fiber tracts that lie within the sinus wall, producing direct imaging evidence of involvement. Using this approach, the authors were able to identify the oculomotor and ophthalmic/maxillary nerves in 116 imaged cavernous sinuses (100%). Of this group, there were 33 patients with pituitary macroadenomas, of whom 10 (12 sides) were found to have cavernous sinus invasion at surgery. The concordance between imaging and surgical findings was very good, with a sensitivity and specificity of 100% for oculomotor nerve involvement. This approach may provide a significant advance in answering this relevant clinical question.

 

An important, and diagnostically difficult, subset of patients with Cushing's disease has episodic and/or mild hypercortisolemia. F. et al. [7] have redemonstrated the value of dynamic pituitary imaging for the detection of small adenomas in Cushing's disease; these authors (with a blinded reader) found pituitary lesions in 23 of 24 patients with Cushing's syndrome. The sensitivity and specificity of dynamic MRI was higher than that of any other test utilized with a false-positive rate of 16% ? similar to other tests. Moreover, these authors found that dynamic pituitary MRI had a greater negative predictive value for Cushing's disease than laboratory testing (in patients with mild/episodic hypercortisolism). In a group of five patients, Kim et al. [8] found the signal-to-noise ratio and spatial resolution of a 3 T system allowed better localization of the small pituitary adenomas that casue Cushing's disease. These results confirm earlier findings [9] of the advantages of a 3 T system in the assessment and identification of pituitary macroadenomas and microadenomas. In a subset of patients in who imaging at 1.5 T did not definitively identify the tumor, preoperative bilateral cavernous sinus sampling (CSS) correctly lateralized 22 of 26 subjects [10]. Inferior petrosal sinus sampling (IPSS) has also been widely used, with similar results, and with relatively low complication rates [11?]. Treatment of hypercortisolemia related to a pituitary adenoma might be invasive, with surgical cure rates as high as 84%, [11?] or noninvasive (radiotherapy) with effective control in up to approximately 50% of patients [12?].

 

Although perfusion-weighted imaging by MRI is gaining widespread use in the evaluation of acute stroke [13], there has been a limited application to the understanding and clinical evaluation of neuroendocrine lesions. The significant potential use of this imaging approach in the evaluation of pituitary lesions is highlighted in recent work by Manuchehri et al. [14??]. These authors have demonstrated by perfusion MRI, in 23 subjects, that the vascularity (approximated by enhancement index) of functional microprolactinomas is greater than in the normal pituitary, whereas that of macroprolactinomas is indistinguishable ? at baseline. In serial imaging, after treatment with a dopamine antagonist, 3?4 days after drug therapy, there were significant decreases in vascular parameters in both macroprolactinomas and microprolactinomas (but not in normal pituitaries or nonlesional hyperprolactinemic pituitaries treated with the same drug) compared with baseline. In the five patients with macroprolactinomas, in whom there was a decrease in tumor size, the reduction in vascular parameters preceded shrinkage. Interestingly, in one patient (out of five), no reduction in either vascular parameters or tumor size was seen. This finding raises the possibility that absence or decrease in this indicator, if not seen within days of treatment, may identify lesions that are unresponsive to dopamine antagonist therapy ? thus requiring surgery.

 

Sathyapalan et al. [15], in five patients with newly diagnosed acromegaly, have demonstrated a similar decrease in tumor vascularity (using exchange rate as the measure of tumor vascularity) in octreotide-treated growth hormone (GH)-secreting tumors. These results suggest both a mechanism for action of pharmacologic therapy (antiangiognesis) and a parameter that could be used clinically in the evaluation of these patients.

 

The incidence of hypopituitarism is estimated at approximately 4.2 per 100 000 per year, whereas the prevalence is estimated at 45.5 per 100 000 [16], making it a relatively common disease with multiple causes, both genetic and acquired (including posttraumatic). Distinguishable anatomic phenotypes defined by MRI are associated with specific gene deficits. For example, mutations in the LHX4 gene are associated with an ectopic posterior pituitary [17], Prop-1 with enlargement of the adenohypophysis [18] and in Fanconi's anemia with decreased pituitary size [19]. Thus, particularly in pediatric patients, evaluation of the pituitary by MRI is essential in the work-up of hypopituitarism, providing both diagnostic and prognostic information (reviewed in [20]). Acquired hypopituitarism that occurs after severe head trauma has also been associated with a distinct imaging appearance ? increased pituitary volume in the acute phase of injury [21].

 

Adrenal glands

 

EAS is a complex problem that requires a multifaceted diagnostic and therapeutic approach. Initial laboratory evaluation, with a high-dose dexamethasone suppression or CRH test, will often distinguish between a pituitary (70?80% of cases) and nonpituitary source (20?30%; [22]). Importantly, despite the sensitivity and specificity of HDSS and CRH tests, a subset of patients with ectopic ACTH production will also be suppressed [23]. As with Cushing's disease, imaging plays a central role in the evaluation of these patients ? often allowing identification of the cause. In one relatively large series, Isidori et al. [23] found that conventional chest radiograph showed a tumor in 25% (10/40) of patients. In this same series, subsequent CT scan of the chest, abdomen and pelvis identified the source in 20 of 30 remaining patients. In those patients in whom cross-sectional imaging fails to provide a diagnosis, subsequent imaging by MIBG, Octreotide or PET [24] can be considered. The most common ectopic sources of ACTH are small-cell lung carcinoma and carcinoid tumors [3,23]. In patients in whom there is failure of localization/therapy, adrenalectomy provides chemical cure and improved quality-of-life, although with incomplete resolution of clinical symptomatology [25].

 

An important and increasingly common diagnosis is primary hyperaldosteronism as a cause for hypertension [causal in approximately 10% of cases (reviewed in [26])], either from a solitary adenoma (approximately one-third) or from a bilateral hyperplasia (two-third of cases). In all patients, evaluation involved cross-sectional imaging, in particular MRI. Accurate characterization of adrenal masses depends on chemical shift imaging ? based upon the slightly differing resonant frequencies of protons in water and fat in an external magnet field (approximately 220 Hz at 1.5T). Notably, implementation of chemical shift imaging at 3 T requires the modification of multiple imaging parameters [27].

 

Inan et al. [28] have demonstrated the value of MRI, with correct differentiation of 44 out of 48 adenomas from nonadenomas. These authors have extended the usual chemical shift evaluation to include perfusion-imaging analysis of the four lesions that could not be distinguished based upon standard methods. The use of time-to-peak (a perfusion metric commonly used in stroke evaluation) reliably distinguished between atypical adenomas (in which chemical shift imaging is nondiagnostic) and metastasis ? albeit in a small number of cases. These findings indicate a role for MRI (including perfusion sequences) in the evaluation of primary hyperaldosteronism, allowing the accurate localization and identification of adenomas, and presumably source of excess steroid production.

 

Thyroid and parathyroid

Thyroid and parathyroid tumors may present clinically, as with all neuroendocrine tumors, as a result of direct mass effect/invasion of adjacent structures, metastasis or as a consequence of hormone overproduction. Malignant thyroid neoplasms account for approximately 1?2% of all cancers in the United States [29]. Imaging of the thyroid includes all modalities, but particularly ultrasound, MRI and CT. For benign disease, novel, image-guided treatment options include percutaneous ethanol injection [30] and laser ablation [31].

 

PET-CT has demonstrated an evolving role in the treatment of differentiated thyroid carcinomas in patients with disease not detectable using conventional whole body (I123) scanning. Leboulleux et al. [32] have suggested that PET can alter patient management in approximately 30% of patients with differentiated thyroid cancers, and has been recommended for use in the evaluation of recurrence [33]. However, in medullary thyroid cancers, 18-fluoro-deoxy-glucose (FDG)-PET appears to have limited value [34]. Fanti et al. [35] have explored the use of a novel tracer, tetraazycyclododecanetetraacetic acid-[1-Nal3]-octreotide [(68)Ga-DOTA-NOC] for the evaluation of neuroendocrine lesions, finding value for clinical decision making in 12 of 14 patients, with inflammatory processes compromising results in two patients.

 

The application of advanced MRI techniques to thyroid gland disorder has, to date, been limited. M?ssig et al. [36] have characterized quantitative magnetic-resonance perfusion, using arterial spin labeling (an alternative to first-pass gadolinium-based methods) in a patient with Grave's disease. These authors found elevated gland perfusion (1500 ml/min?100 g tissue), three times that of normal controls ? consistent with qualitative findings on Doppler ultrasound and the inflammatory nature of the process. The proximity of the thyroid gland to the trachea produces technical limitations with perfusion imaging based upon standard echoplanar techniques, secondary to susceptibility artifact. Schraml et al. [37??] have demonstrated perfusion imaging of the thyroid gland using an arterial spine labeling/flow-sensitive alternating inversion recovery (FAIR)-true fast imaging with steady precession (FISP) sequence (relatively less sensitive to susceptibility artifacts) in eight healthy volunteers and one individual with a known functioning adenoma. These authors found normal gland perfusion values of approximately 400?500 ml/g per minute, consistent with published values in similar tissues. Interestingly, in the one adenoma examined, there was a reduction in hemodynamic values ? raising the possibility that perfusion MRI might provide an alternative method for the evaluation of solitary thyroid nodules.

 

More broadly, MRI has been used to evaluate the cognitive effects of disorders in thyroid function. Functional MRI (fMRI), a technique based upon small changes in brain parenchymal blood flow, has shown a decrease in frontoparietal activation in patients with subclinical hypothyroidism, which resolved with adequate treatment [38]. This decrease provides an interesting starting point in understanding the basis for cognitive impairment in these patients. In rare instances, Wernicke's encephalopathy has been reported as presumed sequelae of the hypermetabolic state associated with hyperthyroidism [39].

 

The radiological approach to hyperparathyroidism involves all available modalities (reviewed in [40]), with no single approach providing definitive imaging. The greatest success has been reported with a combination of techniques: preoperative sestamibi scanning with intraoperative ultrasound [41?43]. The combination of methodologies, when results are concordant, has resulted in both positive predictive values and specificities as high as 100%.

 

Summary

 

The identification of anatomic abnormalities associated with specific neuroendocrine symptoms can be approached using a number of both primarily anatomic and physiological methods. Recent advances suggest an approach to hypercortisolemia beginning with chemical testing followed by brain MRI that includes dynamic contrast-enhanced pituitary sequence for all patients with an apparent pituitary source ? preferably at 3 T. In those patients in whom a pituitary source is not identified, or whose laboratory studies suggest a nonpituitary source, a CT scan of the chest, abdomen and pelvis would be a next reasonable imaging study. Isotopic imaging, in particular PET-CT, may provide additional information in some patients. In the subset of patients in whom a cause is not identified by imaging, invasive testing with IPSS or CSS may provide accurate anatomic localization.

 

The application of advanced MRI techniques to neuroendocrine disorder is still in its early stages. However, magnetic-resonance-based physiological imaging is likely to continue to improve the identification and evaluation of neuroendocrine disorder and lesions. In particular, perfusion imaging might provide an alternative method for the assessment of thyroid nodules and in measuring response to pharmacological therapy of both pituitary and thyroid lesions.

 

Acknowledgement

 

The author acknowledges the editorial contribution of Ms. Siolotuma E. Thompson, B.A.

 

References and recommended readingPapers of particular interest, published within the annual period of review, have been highlighted as:? of special interest?? of outstanding interestAdditional references related to this topic can also be found in the Current World Literature section in this issue (p. 394).1 George JT, Thow JC, Matthews B, et al. Atrial fibrillation associated with a thyroid stimulating hormone-secreting adenoma of the pituitary gland leading to a presentation of acute cardiac decompensation: a case report. J Med Case Reports 2008; 28:67. [Context Link]

 

2 Foppiani L, Del Monte P, Ruelle A, et al. TSH-secreting adenomas: rare pituitary tumors with multifaceted clinical and biological features. J Endocrinol Invest 2007; 30:603?609. [Context Link]

 

3 Sahdev A, Reznek RH, Evanson J, Grossman AB. Imaging in Cushing's syndrome. Arq Bras Endocrinol Metabol 2007; 51:1319?1328. [Context Link]

 

4 Batista DL, Riar J, Keil M, Stratakis CA. Diagnostic tests for children who are referred for the investigation of Cushing syndrome. Pediatrics 2007; 120:e575?e586. [Context Link]

 

5 Vieira JO Jr, Cukiert A, Liberman B. Evaluation of magnetic resonance imaging criteria for cavernous sinus invasion in patients with pituitary adenomas: logistic regression analysis and correlation with surgical findings. Surg Neurol 2006; 65:130?135. [Context Link]

 

6?? Yoneoka Y, Watanabe N, Matsuzawa H, et al. Preoperative depiction of cavernous sinus invasion by pituitary macroadenoma using three-dimensional anisotropy contrast periodically rotated overlapping parallel lines with enhanced reconstruction imaging on a 3-tesla system. J Neurosurg 2008; 108:37?41. The use of anisotropy-based imaging in the evaluation of fiber tracks will probably continue to grow, using this kind of imaging approach. [Context Link]

 

7 F. TC, Zuckerbraun E, Lee ML, et al. Dynamic pituitary MRI has high sensitivity and specificity for the diagnosis of mild Cushing's syndrome and should be part of the initial workup. Horm Metab Res 2007; 39:451?456. [Context Link]

 

8 Kim LJ, Lekovic GP, White WL, Karis J. Preliminary experience with 3-Tesla MRI and Cushing's disease. Skull Base 2007; 17:273?277. [Context Link]

 

9 Pinker K, Ba-Ssalamah A, Wolfsberger S, et al. The value of high-field MRI (3T) in the assessment of sellar lesions. Eur J Radiol 2005; 54:327?334. [Context Link]

 

10 Gazioglu N, Ulu MO, Ozlen F, et al. Management of Cushing's disease using cavernous sinus sampling: effectiveness in tumor lateralization. Clin Neurol Neurosurg 2008; 110:333?338. [Context Link]

 

11? Gandhi CD, Meyer SA, Patel AB, et al. Neurologic complications of inferior petrosal sinus sampling. AJNR Am J Neuroradiol 2008; 29:760?765. IPSS continues to be important in a subset of patients in which imaging fails to provide adequate localization information. [Context Link]

 

12? Jagannathan J, Sheehan JP, Pouratian N, et al. Gamma knife surgery for Cushing's disease. J Neurosurg 2007; 106:980?987. Noninvasive approaches to pituitary disease are currently limited, but likely to expand with improvements in radiotherapy. [Context Link]

 

13 Davis SM, Donnan GA, Parsons MW, et al, for the EPITHET investigators. Effects of alteplase beyond 3 h after stroke in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET): a placebo-controlled randomised trial. Lancet Neurol 2008; 7:299?309. [Context Link]

 

14?? Manuchehri AM, Sathyapalan T, Lowry M, et al. Effect of dopamine agonists on prolactinomas and normal pituitary assessed by dynamic contrast enhanced magnetic resonance imaging. Pituitary 2007; 10:261?266. These authors use perfusion-imaging techniques to address a fundamental biological question in the method of action of pharmacotherapeutics in pituitary tumors. This study and similar imaging approaches will probably form part of the basis for more individualized therapy. [Context Link]

 

15 Sathyapalan T, Lowry M, Turnbull LW, et al. Mechanism of action of octreotide in acromegalic tumours in vivo using dynamic contrast-enhanced magnetic resonance imaging. Pituitary 2007; 10:233?236. [Context Link]

 

16 Schneider HJ, Aimaretti G, Kreitschmann-Andermahr I, et al. Hypopituitarism. Lancet 2007; 369:1461?1470. [Context Link]

 

17 Vieira TC, Boldarine VT, Abucham J. Molecular analysis of PROP1, PIT1, HESX1, LHX3, and LHX4 shows high frequency of PROP1 mutations in patients with familial forms of combined pituitary hormone deficiency. Arq Bras Endocrinol Metabol 2007; 51:1097?1103. [Context Link]

 

18 do Amaral LL, Ferreira RM, Ferreira NP, et al. Combined pituitary hormone deficiency and PROP-1 mutation in two siblings: a distinct MR imaging pattern of pituitary enlargement. AJNR Am J Neuroradiol 2007; 28:1369?1370. [Context Link]

 

19 Sherafat-Kazemzadeh R, Mehta SN, Care MM, et al. Fanconi Anemia Comprehensive Care Center. Small pituitary size in children with Fanconi anemia. Pediatr Blood Cancer 2007; 49:166?170. [Context Link]

 

20 Garel C, L?ger J. Contribution of magnetic resonance imaging in nontumoral hypopituitarism in children. Horm Res 2007; 67:194?202. [Context Link]

 

21 Maiya B, Newcombe V, Nortje J, et al. Magnetic resonance imaging changes in the pituitary gland following acute traumatic brain injury. Intensive Care Med 2008; 34:468?475. [Context Link]

 

22 Isidori AM, Lenzi A. Ectopic ACTH syndrome. Arq Bras Endocrinol Metabol 2007; 51:1217?1225. [Context Link]

 

23 Isidori AM, Kaltsas GA, Pozza C, et al. The ectopic adrenocorticotropin syndrome: clinical features, diagnosis, management, and long-term follow-up. J Clin Endocrinol Metab 2006; 91:371?377. Bibliographic Links [Context Link]

 

24 Kumar J, Spring M, Carroll PV, et al. 18Flurodeoxyglucose positron emission tomography in the localization of ectopic ACTH-secreting neuroendocrine tumours. Clin Endocrinol (Oxf) 2006; 64:371?374. [Context Link]

 

25 Mishra AK, Agarwal A, Gupta S, et al. Outcome of adrenalectomy for Cushing's syndrome: experience from a tertiary care center. World J Surg 2007; 31:1425?1432. [Context Link]

 

26 Schirpenbach C, Reincke M. Primary aldosteronism: current knowledge and controversies in Conn's syndrome. Nat Clin Pract Endocrinol Metab 2007; 3:220?227. [Context Link]

 

27 Merkle EM, Schindera ST. MR imaging of the adrenal glands: 1.5T versus 3T. Magn Reson Imaging Clin N Am 2007; 15:365?372. [Context Link]

 

28 Inan N, Arslan A, Akansel G, et al. Dynamic contrast enhanced MRI in the differential diagnosis of adrenal adenomas and malignant adrenal masses. Eur J Radiol 2008; 65:154?162. [Context Link]

 

29 National Cancer Institute. SEER cancer statistics review. Bethesda, MD: National Cancer Institute; 1975?2004. [Context Link]

 

30 Tarantino L, Francica G, Sordelli I, et al. Percutaneous ethanol injection of hyperfunctioning thyroid nodules: long-term follow-up in 125 patients. AJR Am J Roentgenol 2008; 190:800?808. [Context Link]

 

31 D?ssing H, Bennedbaek FN, Bonnema SJ, et al. Randomized prospective study comparing a single radioiodine dose and a single laser therapy session in autonomously functioning thyroid nodules. Eur J Endocrinol 2007; 157:95?100. [Context Link]

 

32 Leboulleux S, Schroeder PR, Schlumberger M, Ladenson PW. The role of PET in follow-up of patients treated for differentiated epithelial thyroid cancers. Nat Clin Pract Endocrinol Metab 2007; 3:112?121. Review. [Context Link]

 

33 Fletcher JW, Djulbegovic B, Soares HP, et al. Recommendations on the use of 18F-FDG PET in oncology. J Nucl Med 2008; 49:480?508. [Context Link]

 

34 Giraudet AL, Vanel D, Leboulleux S, et al. Imaging medullary thyroid carcinoma with persistent elevated calcitonin levels. J Clin Endocrinol Metab 2007; 92:4185?4190. [Context Link]

 

35 Fanti S, Ambrosini V, Tomassetti P, et al. Evaluation of unusual neuroendocrine tumours by means of (68)Ga-DOTA-NOC PET. Biomed Pharmacother 2008 [Epub ahead of print]. [Context Link]

 

36 M?ssig K, Schraml C, Gallwitz B, et al. A novel MR-imaging technique using arterial spin labeling for thyroid gland perfusion in thyrotoxicosis. Thyroid 2007; 17:1155?1156. [Context Link]

 

37?? Schraml C, Boss A, Martirosian P, et al. FAIR true-FISP perfusion imaging of the thyroid gland. J Magn Reson Imaging 2007; 26:66?71. MRI-based physiological imaging using perfusion-based sequences might have significant impact on understanding thyroid gland disorder. This study is the first description of fundamental magnetic-resonance perfusion parameters in the normal thyroid gland. [Context Link]

 

38 Zhu DF, Wang ZX, Zhang DR, et al. fMRI revealed neural substrate for reversible working memory dysfunction in subclinical hypothyroidism. Brain 2006; 129:2923?2930. Buy Now Bibliographic Links [Context Link]

 

39 Bonucchi J, Hassan I, Policeni B, Kaboli P. Thyrotoxicosis associated Wernicke's encephalopathy. J Gen Intern Med 2008; 23:106?109. [Context Link]

 

40 Rubello D, Gross MD, Mariani G, Al-Nahhas A. Scintigraphic techniques in primary hyperparathyroidism: from preoperative localization to intra-operative imaging. Eur J Nucl Med Mol Imaging 2007; 34:926?933. [Context Link]

 

41 Whitson BA, Broadie TA. Preoperative ultrasound and nuclear medicine studies improve the accuracy in localization of adenoma in hyperparathyroidism. Surg Today 2008; 38:222?226. [Context Link]

 

42 Sukan A, Reyhan M, Aydin M, et al. Preoperative evaluation of hyperparathyroidism: the role of dual-phase parathyroid scintigraphy and ultrasound imaging. Ann Nucl Med 2008; 22:123?131. [Context Link]

 

<A name=RF42>43 Hessman O, St?lberg P, Sundin A, et al. High success rate of parathyroid reoperation may be achieved with improved localization diagnosis. World J Surg 2008; 32:774?781. [Context Link]

 

Keywords: MRI; neuroendocrine; perfusion; pituitary

[justashell]

the signal-to-noise ratio and spatial resolution of a 3 T system allowed better localization of the small pituitary adenomas that casue Cushing's disease. These results confirm earlier findings [9] of the advantages of a 3 T system in the assessment and identification of pituitary macroadenomas and microadenomas. In a subset of patients in who imaging at 1.5 T did not definitively identify the tumor, preoperative bilateral cavernous sinus sampling (CSS) correctly lateralized 22 of 26 subjects [

 

I think I can hear Gracie singing the praises of a 3T machine! I can't wait 'til they come up with one that goes to "11"---(Spinal Tap).

 

Thanks for sharing this Robin---I still get looks of "yeah right", when I tell people I am treated by a special doctor in L.A....and his trusty fellow researcher, Z!!!

Thank goodness for smart folks who love to understand all this stuff! It's more complicated than the last 40 years of General Hospital!

[twinkie]

Thank you Robin! I am definently a fan of the 3T MRI.

love,

melly in nv

[justashell]

Robin when are you going to "hatch" or "come out of your chrisyalis"???

Ignore me if I'm sticking my nose where it doesn't belong...

[fatnsassy]

You are right Shelley! I'm a big fan of those 3T's. There is not much chance of a 1.5T picking up a tumor that is less than 1mm, like mine!

 

OSU has an 8T machine. They don't use it on people, yet. They plan to, but who knows what year that will be approved! They are awesome! Talk about crystal clear imaging! They have a 4T they use on animals, but won't use on humans, also. Right now, the 3T is our best friend! LOL!

 

Gracie

[justashell]

I imagine that 8T causes brown-outs on the electrical grid when they start it up.

I can just imagine them revving it up---and all those hydrogen atoms in your body wondering what the heck is going on.

(What the heck just happened Mildred?)

[staticnrg]

Robin when are you going to "hatch" or "come out of your chrisyalis"???

Ignore me if I'm sticking my nose where it doesn't belong...

 

 

Dearheart, I have no clue what you mean!! You'll have to spell it out for me!

 

Hugs!!

Robin

[da89165]

OSU has an 8T machine. They don't use it on people, yet. They plan to, but who knows what year that will be approved! They are awesome! Talk about crystal clear imaging!

 

They must be able to see into the future with that thing!!!!

[fatnsassy]

Check out this article (click here). They now have a 9.4T. It's used for metabolic processes in the brain, but wouldn't we like to get a look at our tumors with that baby?!

 

Oh, Robin, Shelley was asking where you've been hiding, since you have not been on the boards for a while.

 

Hugs,

 

Gracie

[justashell]

Your avatar picture----it looks like you're "hatching" or coming out of your chrysalis...your head is hinged---and the new you is coming out?

[da89165]

Check out [url="http://www.sciencedaily.com/releases/2007/12/071204163237.htm"]this article (click here)[/url]. They now have a 9.4T. It's used for metabolic processes in the brain, but wouldn't we like to get a look at our tumors with that baby?!

 

Since that baby is in Chicago, I bet they could scan us right here in our homes in Indy and Ohio?!?!?!

 

Seriously though, I just have to believe that with imaging being able to identify more pituitary tumors, there has to be faster care for people.

[staticnrg]

Check out this article (click here). They now have a 9.4T. It's used for metabolic processes in the brain, but wouldn't we like to get a look at our tumors with that baby?!

 

Oh, Robin, Shelley was asking where you've been hiding, since you have not been on the boards for a while.

 

Hugs,

 

Gracie

 

Oh...been working in San Francisco and just got back midnight Sunday. Heading to see my girls tomorrow. Sorry folks, but I'm so glad I feel like doing all this!

 

Your avatar picture----it looks like you're "hatching" or coming out of your chrysalis...your head is hinged---and the new you is coming out?

 

 

Oh, DUH...Shelley I should have understood that! Well, I call it metamorphosis, so it's still a work in progress.

 

Hugs!

Robin