Detailed MRI Analysis Provides Correlations with Clinical Features and Response to Treatment in Cushing’s Disease

Detailed imaging analysis of patients with Cushing’s disease (CD) and other disorders caused by pituitary adenomas (tumors that arise from the pituitary, a small gland in the brain) provides correlation with clinical characteristics and treatment response, a new Turkish study reports.

The research, “Clinicopathological significance of baseline T2-weighted signal intensity in functional pituitary adenomas,” appeared in the journal Pituitary.

Diagnosis of pituitary adenomas is often done with magnetic resonance imaging (MRI), which provides data on the tumor’s localization, its invasiveness, as well as cell death and other changes. However, MRI does not enable precise evaluation of the tumor’s hormone production and behavior.

Studies on T2-weighted signal intensity (T2-WSI) — one of the basic parameters in MRI scans that highlights fat and water in the body — shows that it correlates with collagen content, degree of fibrosis (scarring), amyloid protein accumulation, and granulation pattern of somatotroph adenomas, which produce excessive levels of growth hormone, causing acromegaly (a hormonal disorder that results from too much growth hormone in the body).

Evaluation of granulation patterns is key in predicting response to somatostatin analogues (SSAs) treatment, the researchers observed. SSAs are intended to stop excess hormone production.

In contrast, analysis of T2-WSI in corticotroph adenomas — benign tumors typical in Cushing’s disease patients that release elevated levels of adrenocorticotropin (ACTH) – is still lacking.

The research team assessed the correlation of T2-WSI with clinical features, granulation patterns, and response to treatment in patients with functional pituitary adenomas (FPAs), which are collectively characterized by excessive production of one or more hormones.

Specifically, scientists focused on 29 patients with Cushing’s disease, 87 with acromegaly, and 78 with prolactinoma, a type of benign pituitary tumor that produces elevated amounts of prolactin.

Results showed that while most somatotroph adenomas (53%) were hypointense, which means a darker image on MRI, the majority of prolactinomas (55%) and corticotroph adenomas (45%) were at least generally hyperintense, meaning lighter on image.

Data also revealed that hyperintense somatotroph adenomas were larger, sparsely granulated, and exhibited reduced shrinkage after treatment with SSAs.

In contrast, hypointense tumors were associated with higher levels of baseline insulin-like growth factor (IGF)-1% ULN, a predictor of insulin sensitivity, and a better response to SSAs.

In women with prolactinomas, hyperintensity correlated with smaller tumor diameter. In turn, hypointense prolactinomas were linked with younger age at diagnosis, higher baseline prolactin levels, and resistance to treatment with a dopamine agonist.

Scientists also found that hyperintense corticotroph adenomas correlated with larger tumor size and a sparsely granulated pattern. No difference was found between hyper and hypointense adenomas on cortisol and ACTH levels.

Investigators also reported that T2-WSI was not correlated with better surgical outcomes or with recurrent Cushing’s disease. Analysis of tumor shrinkage in these patients was not possible, the researchers noted.

“Although in present there is no immediate clinical application, we believe that if medical shrinkage of corticotrophs ever became a part of clinical practice, similar analyses could be performed in the future,” the researchers wrote.

“Further studies with larger series are required in order to make stronger suggestions,” they added.

From https://cushingsdiseasenews.com/2018/03/23/detailed-mri-analysis-correlates-with-cushings-disease-clinical-features/

Adrenocortical carcinoma masquerading as Cushing’s disease

BMJ Case Reports 2017; doi:10.1136/bcr-2016-217519

Summary

Cushing’s syndrome (CS) can be classified as adrenocorticotropic hormone (ACTH)-dependent or ACTH-independent depending on the ACTH levels.

However, 30% of the patients with CS have ACTH levels in the ‘grey zone’ (5–20 pg/mL), thereby posing a challenge in establishing the aetiological diagnosis. In a patient with full-blown features of Cushing’s syndrome with equivocal ACTH levels, and a pituitary microadenoma on contrast-enhanced MRI sella, can falsely lead to a diagnosis of Cushing’s disease. Pituitary microadenoma, if <6 mm in size, may be an incidental finding (incidentaloma) in this scenario and can be present in ∼3–27% of the healthy population. Therefore, in a patient with CS with equivocal ACTH levels and a pituitary microadenoma, multiple samplings for ACTH and adrenal imaging should be performed to exclude ACTH-independent CS and if required, bilateral inferior petrosal sinus sampling to determine the source of ACTH excess.

Find the entire article here: http://casereports.bmj.com/content/2017/bcr-2016-217519.full

Comparison of MRI techniques for detecting microadenomas in Cushing’s disease

1Department of Neurological Surgery and 2Department of Radiology, University of Virginia Health Science Center, University of Virginia, Charlottesville, Virginia
ABBREVIATIONS ACTH = adrenocorticotropic hormone; CMRI = conventional MRI; DMRI = dynamic contrast-enhanced MRI; FSH = follicle-stimulating hormone; IPSS = inferior petrosal sinus sampling; SE = spin echo; SGE = spoiled-gradient echo 3D T1 sequence; SPGR = spoiled gradient–recalled acquisition; VIBE = volumetric interpolated breath-hold examination.

INCLUDE WHEN CITING Published online April 28, 2017; DOI: 10.3171/2017.3.JNS163122.

Correspondence Edward H. Oldfield, Department of Neurological Surgery, University of Virginia, Box 800212, Charlottesville, VA 22908. email: .
OBJECTIVE

Many centers use conventional and dynamic contrast-enhanced MRI (DMRI) sequences in patients with Cushing’s disease. The authors assessed the utility of the 3D volumetric interpolated breath-hold examination, a spoiled-gradient echo 3D T1 sequence (SGE) characterized by superior soft tissue contrast and improved resolution, compared with DMRI and conventional MRI (CMRI) for detecting microadenomas in patients with Cushing’s disease.

METHODS

This study was a blinded assessment of pituitary MRI in patients with proven Cushing’s disease. Fifty-seven patients who had undergone surgery for Cushing’s disease (10 male, 47 female; age range 13–69 years), whose surgical findings were considered to represent a microadenoma, and who had been examined with all 3 imaging techniques were included. Thus, selection emphasized patients with prior negative or equivocal MRI on referral. The MRI annotations were anonymized and 4 separate imaging sets were independently read by 3 blinded, experienced clinicians: a neuroradiologist and 2 pituitary surgeons.

RESULTS

Forty-eight surgical specimens contained an adenoma (46 ACTH-staining adenomas, 1 prolactinoma, and 1 nonfunctioning microadenoma). DMRI detected 5 adenomas that were not evident on CMRI, SGE detected 8 adenomas not evident on CMRI, including 3 that were not evident on DMRI. One adenoma was detected on DMRI that was not detected on SGE. McNemar’s test for efficacy between the different MRI sets for tumor detection showed that the addition of SGE to CMRI increased the number of tumors detected from 18 to 26 (p = 0.02) based on agreement of at least 2 of 3 readers.

CONCLUSIONS

SGE shows higher sensitivity than DMRI for detecting and localizing pituitary microadenomas, although rarely an adenoma is detected exclusively by DMRI. SGE should be part of the standard MRI protocol for patients with Cushing’s disease.

Full text at http://thejns.org/doi/full/10.3171/2017.3.JNS163122

Blood Lipid Levels Linked to High Blood Pressure in Cushing’s Disease Patients

High lipid levels in the blood may lead to elevated blood pressure in patients with Cushing’s disease, a Chinese study shows.

The study, “Evaluation of Lipid Profile and Its Relationship with Blood Pressure in Patients with Cushing’s Disease,” appeared in the journal Endocrine Connections.

Patients with Cushing’s disease often have chronic hypertension, or high blood pressure, a condition that puts them at risk for cardiovascular disease. While the mechanisms of Cushing’s-related high blood pressure are not fully understood, researchers believe that high levels of cortisol lead to chronic hypertension through increased cardiac output, vascular resistance, and reactivity to blood vessel constrictors.

In children and adults with Cushing’s syndrome, the relationship between increased cortisol levels and higher blood pressure has also been reported. Patients with Cushing’s syndrome may remain hypertensive even after surgery to lower their cortisol levels, suggesting their hypertension is caused by changes in blood vessels.

Studies have shown that Cushing’s patients have certain changes, such as increased wall thickness, in small arteries. The renin-angiotensin system, which can be activated by glucocorticoids like cortisol, is a possible factor contributing to vascular changes by increasing the uptake of LDL-cholesterol (LDL-C) — the “bad” cholesterol — in vascular cells.

Prior research showed that lowering cholesterol levels could benefit patients with hypertension and normal lipid levels by decreasing the stiffness of large arteries. However, the link between blood lipids and hypertension in Cushing’s disease patients is largely unexplored.

The study included 84 patients (70 women) referred to a hospital in China for evaluation and diagnosis of Cushing’s disease. For each patient, researchers measured body mass index, blood pressure, lipid profile, and several other biomarkers of disease.

Patients with high LDL-cholesterol had higher body mass index, blood pressure, cholesterol, triglycerides, and apolipoproteinB (apoB), a potential indicator of atherosclerosis and cardiovascular disease.

Data further revealed an association between blood pressure and lipid profile, including cholesterol, triglycerides, apoB and LDL-c. “The results strongly suggested that CHO (cholesterol), LDL-c and apoB might predict hypertension more precisely in [Cushing’s disease],” the scientists wrote.

They further add that high cholesterol, LDL-cholesterol, and apoB might be contributing to high blood pressure by increasing vessel stiffness.

Additional analysis showed that patients with higher levels of “bad” cholesterol — 3.37 mmol/L or higher — had higher blood pressure. This finding remained true, even when patients were receiving statins to lower their cholesterol levels.

No association was found between blood pressure and plasma cortisol, UFC, adrenocorticotropic hormone, or glucose levels in Cushing’s disease patients.

These findings raise some questions on whether lipid-lowering treatment for high blood pressure and cardiovascular disease would be beneficial for Cushing’s disease patients. Further studies addressing this question are warranted.

Adapted from https://cushingsdiseasenews.com/2018/04/24/blood-pressure-linked-lipid-levels-cushings-disease-study/

Fluorescent Metabolite Might Help Surgeons Remove Pituitary Tumors

The resection of microadenomas — small, benign tumors in the pituitary gland underlying Cushing’s disease — could be aided by a fluorescent marker that is naturally produced by the tumor, a new study shows.

The findings were presented recently at the 2018 George Washington Research Days in a poster titled, “Enhanced 5-ALA Induced Fluorescence in Hormone Secreting Pituitary Adenomas.

Cushing’s disease is characterized by high cortisol levels that cause debilitating physical, mental, and hormonal symptoms. The excess cortisol is caused by tiny benign tumors in the pituitary gland, called microadenomas, with a size of less than 10 millimeters.

On account of their small size, these microadenomas pose imaging challenges to physicians. Up to 40 percent of microadenomas remain undetected in the gold-standard magnetic resonance imaging (MRI).

Pituitary adenomas, however, have a characteristic that distinguishes them from the surrounding healthy tissue. They process (metabolize) a natural haemoglobin metabolite, called 5-aminolevulinic acid (5-ALA), into protoporphyrin IX (PpIX) at much higher rates — up to 20 to 50 times higher — than normal tissues.

Importantly, PpIX emits red fluorescence when excited with blue light.

This means that exogenous 5-ALA is taken up by the adenoma cells and rapidly metabolized into the fluorescent metabolite, PpIX, which may establish its use for fluorescence-guided resection of pituitary adenomas.

To test this, researchers incubated human-derived corticotropinoma, as well as the adjacent normal gland cells with 5-ALA. They did the same with mouse model normal pituitary cells and a mouse model pituitary tumor cell line, called AtT20.

They then analyzed the cells’ fluorescence profile by microscopy and with a technique called flow cytometry.

The analysis showed that compared to normal pituitary tissue, human-derived adenomatous cells had a significant increase of tenfold in 5-ALA-induced PpIX fluorescence intensity.

Similarly, mouse pituitary tumor cells (AtT20 cell line) fluoresced seven times more intensely than normal murine pituitary tissue.

The microscopy analysis revealed that the 5-ALA localized in subcellular organelles called mitochondria.

On June 6, 2017, the U.S. Food and Drug Administration approved the use of 5-ALA (under the brand name Gleolan) as an optical imaging agent for patients with gliomas (brain tumors), as an add-on compound to assist surgeons in identifying the malignant tissue during surgery.

Now, these findings suggest that 5-ALA also may be used for fluorescence-guided surgery of microadenomas in Cushing’s disease.

“The supraphysiological levels of glucocorticoids, as seen in CD [Cushing’s disease], may enhance the 5-ALA fluorescence in corticotropinomas,” researchers wrote.

From https://cushingsdiseasenews.com/2018/04/13/fluorescent-metabolite-might-help-surgeons-removepituitary-tumors/