Adrenal masses: characterization with in vivo proton MR spectroscopy--initial experience

Correlation between the size of pheochromocytoma and the level of metanephrines

Objective. Pheochromocytomas (PHEO) and paraganglioma (PGLs) are rare neuroendocrine catecholamine-producing tumors that arise from the chromaffin cells of either the adrenal medulla or extra-adrenal paraganglionic tissues. Despite the recent advances in imaging technologies, biochemical evidence of excessive catecholamine production by the tumor is considered the most important test for the diagnosis of these tumors. The aim of the present study is to investigate the role of the catecholamine metabolites (normetanephrine and metanephrine) levels in the diagnosis of PHEO/PGLs and to evaluate if their levels correlate with the size of these tumors. Patients and Methods. Twenty-five patients were included in the study during the time period of 10 years. Their data were compared with another set of 25 patients to obtain the sensitivity and specificity of metanephrine and normetanephrine in the diagnosis of PHEO/PGLs. The tumor size was reviewed in every patient to obtain the correlation coefficient between the tumor sizes and the plasma/24-hour urinary metanephrine levels. Results. The sensitivity and specificity rates for plasma metanephrine were 80-92% and 92-96%, respectively; while for 24-hour urinary metanephrine were 80-90% and 95-100%, respectively. We found a strong positive relationship between the tumor size and the plasma levels of normetanephrine (r=0.518, p<0.01), and metanephrine (r=0.577, p<0.01). While the relation with the 24-hour urinary concentrations of normetanephrine (r=0.384, p=0.01) and 24-h urinary meta-nephrine (r=0.138, p<0.01) was low. Conclusion. The determination of plasma and 24-hour urinary levels of metanephrines is a reliable test for the diagnosis of PHEO, as they are continuously produced by the tumor cells in contrast to catecholamines.

Adrenal Mass Characterization in the Era of Quantitative Imaging: State of the Art

Simple Summary

Non-invasive characterization of adrenal lesions requires a rigorous approach. Although CT is the cornerstone of adrenal lesion characterization, a multimodality multiparametric imaging approach helps improve confidence in adrenal lesion characterization.

Abstract

Detection and characterization of adrenal lesions have evolved during the past two decades. Although the role of imaging in adrenal lesions associated with hormonal secretion is usually straightforward, characterization of non-functioning adrenal lesions may be challenging to confidently identify those that need to be resected. Although many adrenal lesions can be readily diagnosed when they display typical imaging features, the diagnosis may be challenging for atypical lesions. Computed tomography (CT) remains the cornerstone of adrenal imaging, but other morphological or functional modalities can be used in combination to reach a diagnosis and avoid useless biopsy or surgery. Early- and delayed-phase contrast-enhanced CT images are essential for diagnosing lipid-poor adenoma. Ongoing studies are evaluating the capabilities of dual-energy CT to provide valid virtual non-contrast attenuation and iodine density measurements from contrast-enhanced examinations. Adrenal lesions with attenuation values between 10 and 30 Hounsfield units (HU) on unenhanced CT can be characterized by MRI when iodinated contrast material injection cannot be performed. ¹⁸F-FDG PET/CT helps differentiate between atypical benign and malignant adrenal lesions, with the adrenal-to-liver maximum standardized uptake value ratio being the most discriminative variable. Recent studies evaluating the capabilities of radiomics and artificial intelligence have shown encouraging results.

Adrenal cavernous hemangioma misdiagnosed as pheochromocytoma: a case report

BACKGROUND

Adrenal hemangioma is a rare benign adrenal tumor that is usually misdiagnosed preoperatively. We here present a case of adrenal cavernous hemangioma that was successfully treated with retroperitoneal laparoscopic adrenalectomy.

CASE PRESENTATION

A 67-year-old man with dull right back pain attended our clinic for examination of a mass on the right adrenal gland for 1 week. Pheochromocytoma was considered according to the preoperative computed tomography angiography + computed tomography urography findings and was subsequently corrected to adrenal gland hemangioma according to postoperative pathological findings. The patient showed no recurrence of adrenal hemangioma during the 1-year follow-up period after surgery.

CONCLUSION

Adrenal gland hemangioma is rare with a high rate of misdiagnosis, and it should be considered in imaging findings of adrenal tumors with typical hemangioma. Surgery is an effective treatment method.

The value of signal intensity on T1-weighted chemical shift magnetic resonance imaging combined with proton magnetic resonance spectroscopy for the diagnosis of adrenal adenomas

Objective

To investigate the advantages of using modified signal intensity measurements on chemical shift imaging alone or in conjunction with proton magnetic resonance spectroscopy in the differential diagnosis of adrenal adenomas.

Materials and Methods

This was a prospective study involving 97 patients with adrenal nodules or masses. The signal intensity index (SII) was calculated as [(signal intensity on the in-phase image − signal intensity on the out-of-phase image) ∕ (signal intensity on the in-phase image)] × 100%. We determined the averages of the minimum, mean, and maximum signal intensity values measured on three consecutive images. When that was not possible (for smaller lesions), we used one or two images. We employed a region of interest that covered one half to two thirds of the mass. All indices were compared with metabolite ratios derived from spectroscopy: lactate/creatine; glutamine-glutamate/creatine; choline/creatine; choline/lipid; 4.0-4.3 ppm/Cr; and lipid/creatine.

Results

Of the 97 patients evaluated, 69 were diagnosed with adenomas and 28 were diagnosed with nonadenomas. All SII measurements and spectroscopy-derived metabolite ratios were significant to the differentiation between adenomas and nonadenomas, except for the lipid/creatine and choline/lipid ratios. In 37.8% of the cases, it was not possible to perform spectroscopy. When it was possible, the lactate/creatine ratio was found to have higher accuracy than did the SII.

Conclusion

Determining the SII and metabolite ratios increased the accuracy of the differential diagnosis of adrenal adenomas.

A pictorial review of non-traumatic adrenergic crisis

Non-traumatic adrenal crisis is a rare but critical diagnosis to make in emergency settings due to grave consequences. Various pathologies can present as acute crisis, such as spectrum of endocrine imbalance, ranging from catecholamine excess in pheochromocytomas to acute adrenal insufficiency related to glandular dysfunction. Critical manifestations may be due to structural causes related to adrenal hemorrhage, especially when they are bilateral. Oncological complications such as vascular invasion, tumoral bleed, rupture, and hormonal dysfunction can occur. Due to non-specific clinical presentation, these conditions may come as a surprise on imaging performed for other reasons. Recognition of these imaging findings is critical for appropriate patient management. Although there are few articles discussing non-traumatic emergencies in literature, this review is inclusive of all possible etiologies, thus provides a holistic approach and insight into each situation. Specific imaging approach is needed to tailor the diagnosis. This article will also discuss about the advanced imaging techniques that will complement diagnosis.

Adrenal cortical adenoma: current update, imaging features, atypical findings, and mimics

Adrenal adenoma is the most common adrenal lesion. Due to its wide prevalence, adrenal adenomas may demonstrate various imaging features. Thus, it is important to identify typical and atypical imaging features of adrenal adenomas and to be able to differentiate atypical adrenal adenomas from potentially malignant lesions. In this article, we will discuss the diagnostic approach, typical and atypical imaging features of adrenal adenomas, as well as other lesions that mimic adrenal adenomas.

Adrenal cortical carcinoma: pathology, genomics, prognosis, imaging features, and mimics with impact on management

Adrenocortical carcinoma (ACC) is a rare tumor with a poor prognosis. Most tumors are either metastatic or locally invasive at the time of diagnosis. Differentiation between ACC and other adrenal masses depends on clinical, biochemical, and imaging factors. This review will discuss the genetics, pathological, and imaging feature of ACC.

Correlation Between Size and Function of Unilateral and Bilateral Adrenocortical Nodules: An Observational Study

OBJECTIVE. Adrenal incidentalomas occur in 5% of adults and can produce autonomous cortisol secretion that increases the risk of metabolic syndrome and cardiovascular disease. The objective of our study was to evaluate the relationship between adrenal nodule size measured on CT and autonomous cortisol secretion. SUBJECTS AND METHODS. In a prospective study of 73 patients 22-87 years old with incidentalomas, unilateral in 52 patients and bilateral in 21 patients, we measured maximum nodule diameter on CT and serum cortisol levels at 8:00 am, 60 minutes after the adrenocorticotropic hormone stimulation test, and after the dexamethasone suppression test. We also studied 34 age-, sex-, and body mass index-matched control subjects. Statistics used were Spearman correlation coefficients, t tests, ANOVA test, and multivariate analysis. RESULTS. The mean maximum diameter of unilateral nodules measured on CT was larger on the right (2.47 ± 0.98 [SD] cm) than on the left (2.04 ± 0.86 cm) (p = 0.01). In the bilateral cases, the mean diameter of the right nodules was 2.69 ± 0.93 cm compared with 2.13 ± 0.89 cm on the left (p = 0.06). Mean baseline serum cortisol level was significantly higher in the patients with incidentalomas (bilateral, 13.1 ± 4.5 mcg/dL [p < 0.001]; unilateral, 9.7 ± 3.2 mcg/dL [p = 0.019]) than in the control subjects (7.5 ± 3.6 mcg/dL). After dexamethasone suppression test, serum cortisol levels were suppressed to less than 1.8 mcg/dL in 100% of control subjects, 33% of patients with bilateral incidentalomas, and 62% of patients with unilateral incidentalomas (p < 0.001). There were significant correlations between maximum nodule diameter on CT and serum cortisol levels after the dexamethasone suppression test (ρ = 0.500; p < 0.001) and at baseline (ρ = 0.373; p = 0.003). CONCLUSION. Increasing size of adrenal nodules is associated with more severe hyper-cortisolism and less dexamethasone suppression; these cases need further evaluation and possibly surgery because of increased risks of metabolic syndrome and cardiovascular mortality.

Radiological differentiation of phaeochromocytoma from other malignant adrenal masses: importance of wash-in characteristics on multiphase CECT

RATIONALE AND INTRODUCTION

To evaluate the computerised tomography (CT) characteristics of phaeochromocytoma (PCC) that differentiate them from other non-benign adrenal masses such as adrenocortical carcinoma (ACC), primary adrenal lymphoma (PAL) and adrenal metastases (AM).

METHODS

This retrospective study was conducted at a tertiary health care institute from Western India. Patients presented between January 2013 and August 2016 with histological diagnosis of PCC or other non-benign adrenal mass having adequate reviewable imaging data comprising all four CECT phases were included.

RESULTS

The study cohort consisted of 72 adrenal masses from 66 patients (33 PCC, 22 ACC, 4 PAL, 13 AM). Unlike other masses, majority of PCC (25/33) showed peak enhancement in early arterial phase (EAP). PCC had significantly higher attenuation in EAP and early venous phase (EVP), and higher calculated percentage arterial enhancement (PAE) and percentage venous enhancement (PVE) than other adrenal masses (P < 0.001). For diagnosis of PCC with 100% specificity, PAE value ≥100% and EAP attenuation ≥100 HU had 78.8 and 63.6% sensitivity respectively. ACC were significantly larger in size as compared to PCC and metastasis. The adreniform shape was exclusively found in PAL (two out of four) and AM (4 out of 13). None of the enhancement, wash-in or washout characteristics were discriminatory among ACC, PAL and AM.

CONCLUSION

Peak enhancement in EAP, PAE value ≥100% and EAP attenuation ≥100 HU differentiate PCC from other malignant adrenal masses with high specificity.

Practical Approach to Adrenal Imaging

Various pathologies can affect the adrenal gland. Noninvasive cross-sectional imaging is used for evaluating adrenal masses. Accurate diagnosis of adrenal lesions is critical, especially in cancer patients; the presence of adrenal metastasis changes prognosis and treatment. Characterization of adrenal lesions predominantly relies on morphologic and physiologic features to enable correct diagnosis and management. Key diagnostic features to differentiate benign and malignant adrenal lesions include presence/absence of intracytoplasmic lipid, fat cells, hemorrhage, calcification, or necrosis and locoregional and distant disease; enhancement pattern and washout values; and lesion size and stability. This article reviews a spectrum of adrenal pathologies.

氢质子磁共振波谱对胰腺癌分析及其分化程度相关性研究

目的

探讨氢质子磁共振波谱(¹H magnetic resonance spectroscopy, ¹H MRS)分析胰腺癌瘤体与瘤旁导管上皮内瘤变(pancreatic duct intraepithelial neoplasia, Pan IN)病变及肿瘤不同分化程度的代谢物差异.

方法

病理确诊为胰腺导管腺癌的患者47例(低分化17例、中分化30例), 术前均行¹H MRS检查, 使用呼吸门控的抑水点分辨波谱序列对肿瘤的瘤体、瘤旁组织进行¹H MRS检测. 分析出每个¹H MRS数据的胆碱峰(choline-containing metabolites, CCM)/脂肪峰(lipid, Lip)、胆固醇及不饱和脂肪酸峰(cholesterol and unsaturated fatty acids, Chol+Unsat)/Lip、Chol+Unsat/CCM的峰下面积比, 采用配对样本t检验比较瘤体和瘤旁组织的代谢物差异, 用独立样本t检验比较胰腺导管腺癌低分化组和中分化组的代谢物差异.

结果

同时获得瘤体和瘤旁数据共24例, 瘤体组织的CCM/Lip高于瘤旁组织(0.266±0.084 vs 0.200±0.081), 瘤体组织的Chol+Unsat/Lip高于瘤旁组织(0.324±0.109 vs 0.258±0.092), 差异均有统计学意义(P<0.05), 瘤体和瘤旁组织的Chol+Unsat/CCM无统计学差异; 胰腺低分化和中分化导管腺癌的CCM/Lip、Chol+Unsat/Lip、Chol+Unsat/CCM无统计学差异.

结论

¹H MRS对鉴别胰腺癌与瘤旁Pan IN病变具有一定意义, 但不可预测其肿瘤分化程度.

Adrenocortical neoplasms in adulthood and childhood: distinct presentation. Review of the clinical, pathological and imaging characteristics

Adrenocortical tumors (ACT) in adulthood and childhood vary in clinical, histopathological, molecular, prognostic, and imaging aspects. ACT are relatively common in adults, as adenomas are often found incidentally on imaging. ACT are rare in children, though they have a significantly higher prevalence in the south and southeast regions of Brazil. In clinical manifestation, adults with ACT present more frequently with glucocorticoid overproduction (Cushing syndrome), mineralocorticoid syndromes (Conn syndrome), or the excess of androgens in women. Subclinical tumors are frequently diagnosed late, associated with compression symptoms of abdominal mass. In children, the usual presentation is the virilizing syndrome or virilizing association and hypercortisolism. Histopathological grading and ACT classification in malignant and benign lesions are different for adults and children. In adults, the described criteria are the Hough, Weiss, modified Weiss, and Van Slooten. These scores are not valid for children; there are other criteria, such as proposed by Wieneke and colleagues. In molecular terms, there is also a difference related to genetic alterations found in these two populations. This review discusses the imaging findings of ACT, aiming to characterize the present differences between ACT found in adults and children. We listed several differences between magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography-computed (PET-CT) and also performed a literature review, which focuses on studied age groups of published articles in the last 10 years regarding cortical neoplasm and imaging techniques. Published studies on ACT imaging in children are rare. It is important to stress that the majority of publications related to the differentiation of malignant and benign tumors are based almost exclusively on studies in adults. A minority of articles, however, studied adults and children together, which may not be appropriate.

Apparent diffusion coefficient of normal adrenal glands

Objective

To assess the feasibility and reliability of apparent diffusion coefficient (ADC) measurements of normal adrenal glands.

Materials and methods

This was a retrospective study involving 32 healthy subjects, divided into two groups: prepubertal (PreP, n = 12), aged from 2 months to 12.5 years (4 males; 8 females); and postpubertal (PostP, n = 20), aged from 11.9 to 61 years (5 males; 15 females). Diffusion-weighted magnetic resonance imaging (DW-MRI) sequences were acquired at a 1.5 T scanner using b values of 0, 20, 500, and 1000 s/mm². Two radiologists evaluated the images. ADC values were measured pixel-by-pixel on DW-MRI scans, and automatic co-registration with the ADC map was obtained.

Results

Mean ADC values for the right adrenal glands were 1.44 × 10^-3 mm²/s for the PreP group and 1.23 × 10^-3 mm²/s for the PostP group, whereas they were 1.58 × 10^-3 mm²/s and 1.32 × 10^-3 mm²/s, respectively, for the left glands. ADC values were higher in the PreP group than in the PostP group (p < 0.05). Agreement between readers was almost perfect (intraclass correlation coefficient, 0.84-0.94; p < 0.05).

Conclusion

Our results demonstrate the feasibility and reliability of performing DW-MRI measurements of normal adrenal glands. They could also support the feasibility of ADC measurements of small structures.

Practical Approach to Adrenal Imaging

Various pathologies can affect the adrenal gland. Noninvasive cross-sectional imaging is used for evaluating adrenal masses. Accurate diagnosis of adrenal lesions is critical, especially in cancer patients; the presence of adrenal metastasis changes prognosis and treatment. Characterization of adrenal lesions predominantly relies on morphologic and physiologic features to enable correct diagnosis and management. Key diagnostic features to differentiate benign and malignant adrenal lesions include presence/absence of intracytoplasmic lipid, fat cells, hemorrhage, calcification, or necrosis and locoregional and distant disease; enhancement pattern and washout values; and lesion size and stability. This article reviews a spectrum of adrenal pathologies.

Adrenocortical carcinoma: modern management and evolving treatment strategies

Adrenocortical carcinoma (ACC) is a rare cancer with a poor prognosis. Unlike many other cancers, there has been little improvement in patient outcome over the past several decades. However, as scientific advancements are made and our understanding of the molecular genetics involved in ACC improve then progress may be achieved in this devastating disease. This review focuses on recent literature published in the field of ACC from 2010 to 2015 with an emphasis on improving diagnosis, staging and treatment for ACC.

Adrenal imaging for adenoma characterization: imaging features, diagnostic accuracies and differential diagnoses

Adrenocortical adenoma is the most common adrenal tumour. This lesion is frequently encountered on cross-sectional imaging that has been performed for unrelated reasons. Adrenal adenoma manifests various imaging features on CT, MRI and positron emission tomography/CT. The learning objectives of this review are to describe the imaging findings of adrenocortical adenoma, to compare the sensitivities of different imaging modalities for adenoma characterization and to introduce differential diagnoses.

Clinical application of magnetic resonance spectroscopy in diagnosis of pancreatic cancer

Pancreatic cancer (PC) is one of the most frequent malignant tumors of the digestive system, which is difficultly detected and highly aggressive. More than 80% of patients with PC present with advanced disease that is incurable by surgery. Thus, early diagnosis and surgery before frank invasion occurs are critical for improving PC patients' outcomes. Magnetic resonance spectroscopy (MRS) is conducive to screening, early diagnosis and differential diagnosis of PC. Nowadays, MRS is preeminently a tool for nondestructive chemical analysis and metabolic profiling. MRS is expected to be a sensitive and accurate method for PC diagnosis and differential diagnosis, for tracking tumor change and for assessing treatment response.

Magnetic resonance spectroscopy of paragangliomas: new insights into in vivo metabolomics

Paragangliomas (PGLs) can be associated with mutations in genes of the tricarboxylic acid (TCA) cycle. Succinate dehydrogenase (SDHx) mutations are the prime examples of genetically determined TCA cycle defects with accumulation of succinate. Succinate, which acts as an oncometabolite, can be detected by ex vivo metabolomics approaches. The aim of this study was to evaluate the potential role of proton magnetic resonance (MR) spectroscopy ((1)H-MRS) for identifying SDHx-related PGLs in vivo and noninvasively. Eight patients were prospectively evaluated with single voxel (1)H-MRS. MR spectra from eight tumors (four SDHx-related PGLs, two sporadic PGLs, one cervical schwannoma, and one cervical neurofibroma) were acquired and interpreted qualitatively. Compared to other tumors, a succinate resonance peak was detected only in SDHx-related tumor patients. Spectra quality was considered good in three cases, medium in two cases, poor in two cases, and uninterpretable in the latter case. Smaller lesions had lower spectra quality compared to larger lesions. Jugular PGLs also exhibited a poorer spectra quality compared to other locations. (1)H-MRS has always been challenging in terms of its technical requisites. This is even more true for the evaluation of head and neck tumors. However, (1)H-MRS might be added to the classical MR sequences for metabolomic characterization of PGLs. In vivo detection of succinate might guide genetic testing, characterize SDHx variants of unknown significance (in the absence of available tumor sample), and even optimize a selection of appropriate therapies.

Application of a protocol for magnetic resonance spectroscopy of adrenal glands: an experiment with over 100 cases

Objective

To evaluate a protocol for two-dimensional (2D) hydrogen proton (1H) magnetic resonance spectroscopy (MRS) (Siemens Medical Systems; Erlangen, Germany) in the detection of adrenal nodules and differentiation between benign and malignant masses (adenomas, pheochromocytomas, carcinomas and metastases).

Materials and Methods

A total of 118 patients (36 men; 82 women) (mean age: 57.3 ± 13.3 years) presenting with 138 adrenal nodules/masses were prospectively assessed. A multivoxel system was utilized with a 2D point-resolved spectroscopy/chemical shift imaging sequence. The following ratios were calculated: choline (Cho)/creatine (Cr), 4.0–4.3/Cr, lipid (Lip)/Cr, Cho/Lip and lactate (Lac)/Cr.

Results

2D-1H-MRS was successful in 123 (89.13%) lesions. Sensitivity and specificity values observed for the ratios and cutoff points were the following: Cho/Cr ≥ 1.2, 100% sensitivity, 98.2% specificity (differences between adenomas/pheochromocytomas and carcinomas/ metastases); 4.0–4.3 ppm/Cr ≥ 1.5, 92.3% sensitivity, 96.9% specificity (differences between carcinomas/pheochromocytomas and adenomas/metastases); Lac/Cr ≤ –7.449, 90.9% sensitivity and 77.8% specificity (differences between pheochromocytomas and carcinomas/adenomas).

Conclusion

Information provided by 2D-1H-MRS were effective and allowed for the differentiation between adrenal masses and nodules in most cases of lesions with > 1.0 cm in diameter.

Imaging of the adrenal gland lesions

With the steep increase in the use of cross-sectional imaging in recent years, the incidentally detected adrenal lesion, or "incidentaloma", has become an increasingly common diagnostic problem for the radiologist, and a need for an approach to classifying these lesions as benign, malignant or indeterminate with imaging has spurred an explosion of research. While most incidentalomas represent benign disease, typically an adenoma, the possibility of malignant involvement of the adrenal gland necessitates a reliance on imaging to inform management decisions. In this article, we review the literature on adrenal gland imaging, with particular emphasis on computed tomography, magnetic resonance imaging, and photon-emission tomography, and discuss how these findings relate to clinical practice. Emerging technologies, such as contrast-enhanced ultrasonography, dual-energy computed tomography, and magnetic resonance spectroscopic imaging will also be briefly addressed.

Value of 18-F-FDG PET/CT and CT in the Diagnosis of Indeterminate Adrenal Masses

The purpose of this paper was to study the value of 18-FDG PET/CT and reassess the value of CT for the characterization of indeterminate adrenal masses. 66 patients with 67 indeterminate adrenal masses were included in our study. CT/MRI images and 18F-FDG PET/CT data were evaluated blindly for tumor morphology, enhancement features, apparent diffusion coefficient values, maximum standardized uptake values, and adrenal-to-liver maxSUV ratio. The study population comprised pathologically confirmed 16 adenomas, 19 metastases, and 32 adrenocortical carcinomas. Macroscopic fat was observed in 62.5% of the atypical adenomas at CT but not in malignant masses. On 18F-FDG PET/CT, SUVmax and adrenal-to-liver maxSUV ratio were significantly lower in adenomas than in malignant tumors. An SUVmax value of less than 3.7 or an adrenal-to-liver maxSUV ratio of less than 1.29 is highly predictive of benignity.

Adrenal lesions: spectrum of imaging findings with emphasis on multi-detector computed tomography and magnetic resonance imaging

The adrenal gland is a common site of a large spectrum of abnormalities like primary tumors, hemorrhage, metastases, and enlargement of the gland from external hormonal stimulation. Most of these lesions represent nonfunctioning adrenal adenomas and thus warrant a conservative management. Multi-detector computed tomography (CT) and magnetic resonance (MR) imaging are still considered highly specific and complementary techniques for the detection and characterization of adrenal abnormalities. Radiologist can establish a definitive diagnosis for most adrenal masses (i.e., carcinoma, hemorrhage) based on imaging alone. Imaging therefore can differentiate malignant lesions from those benign and avoid unnecessary aggressive management of benign lesions. The article gives an overview of the adrenal lesions and their imaging characteristics seen on CT and MR imaging.

Glutamine/glutamate metabolism studied with magnetic resonance spectroscopic imaging for the characterization of adrenal nodules and masses

PURPOSE

To assess glutamine/glutamate (Glx) and lactate (Lac) metabolism using proton magnetic resonance spectroscopic imaging (1H-MRS) in order to differentiate between adrenal gland nodules and masses (adenomas, pheochromocytomas, carcinomas, and metastases).

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. A total of 130 patients (47 men) with 132 adrenal nodules/masses were prospectively assessed (54 ± 14.8 years). A multivoxel system was used with a two-dimensional point-resolved spectroscopy/chemical-shift imaging sequence. Spectroscopic data were interpreted by visual inspection and peak amplitudes of lipids (Lip), choline (Cho), creatine (Cr), Lac, and Glx. Lac/Cr and Glx/Cr were calculated. Glx/Cr was assessed in relation to lesion size.

RESULTS

Statistically significant differences were observed in Glx/Cr results between adenomas and pheochromocytomas (P < 0.05), however, with a low positive predictive value (PPV). Glx levels were directly proportional to lesion size in carcinomas. A cutoff point of 1.44 was established for the differentiation between carcinomas larger versus smaller than 4 cm, with 75% sensitivity, 100% specificity, 100% PPV, and 80% accuracy. Lac/Cr results showed no differences across lesions. A cutoff point of -6.5 for Lac/Cr was established for carcinoma diagnosis.

CONCLUSION

Glx levels are directly proportional to lesion size in carcinomas. A cutoff point of -6.5 Lac/Cr differentiates carcinomas from noncarcinomas.

Cross-sectional imaging work-up of adrenal masses

Advances in medical imaging with current cross-section modalities enable non-invasive characterization of adrenal lesions. Computed tomography (CT) provides characterization with its non-contrast and wash-out features. Magnetic resonance imaging (MRI) is helpful in further characterization using chemical shift imaging (CSI) and MR spectroscopy. For differentiating between benign and malignant masses, positron emission tomography (PET) imaging is useful with its qualitative analysis, as well as its ability to detect the presence of extra-adrenal metastases in cancer patients. The work-up for an indeterminate adrenal mass includes evaluation with a non-contrast CT. If a lesion is less than 10 Hounsfield Units on a non-contrast CT, it is a benign lipid-rich adenoma and no further work-up is required. For the indeterminate adrenal masses, a lipid-poor adenoma can be differentiated from a metastasis utilizing CT wash-out features. Also, MRI is beneficial with CSI and MR spectroscopy. If a mass remains indeterminate, PET imaging may be of use, in which benign lesions demonstrate low or no fluorodeoxyglucose activity. In the few cases in which adrenal lesions remain indeterminate, surgical sampling such as percutaneous biopsy can be performed.

Radiological evaluation of adrenal incidentalomas: current methods and future prospects

Incidental adrenal lesions are very common. Computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) all have a role to play in characterizing adrenal lesions. The purpose of this review is to discuss the rationale behind both established and emerging imaging techniques. We also discuss how to follow up incidentally found lesions.

In vivo 1H MRS for musculoskeletal lesion characterization: which factors affect diagnostic accuracy?

In vivo (1)H MRS is a noninvasive imaging technique for the identification of malignancy. Musculoskeletal lesions vary in their composition, causing field inhomogeneity and magnetic susceptibility effects which may be technical and diagnostic challenges for MRS. This study investigated the factors that affect diagnostic accuracy in the use of MRS for the characterization of musculoskeletal neoplasms. During a 7-year period, 210 consecutive patients with musculoskeletal lesions larger than 1.5 cm in diameter were examined. MRS of a single-voxel point-resolved spectroscopy sequence with TE = 135 ms was undertaken using a 1.5-T scanner. Lesions with a choline signal-to-noise ratio larger than 3.0 were considered to be malignant tumors. The diagnostic accuracy was calculated for all lesions and for subgroups on the basis of lesion type (bone and soft tissue), lesion composition (mixed and solid nonsclerotic), lesion size (≤4, >4-10 and >10 cm), MR scanner (MR scanner 1 and 2) and selected voxel size (≤3, >3-8 and >8 cm(3)). Multivariate logistic regressions were performed to estimate the associations between each factor and diagnostic accuracy. The diagnostic accuracy was 73.3% for all lesions. The accuracy was 54.4% for mixed lesions and 80.4% for solid nonsclerotic lesions (p < 0.001). The diagnostic accuracy was lower for larger lesions [86.8% for lesions of ≤4 cm, 71.6% for lesions of >4-10 cm (p = 0.04) and 63.6% for lesions of >10 cm (p = 0.007)]. There was no difference in diagnostic accuracy for bone versus soft-tissue lesions or as a function of MR scanner or voxel size. By the use of multivariate logistic regression, a solid nonsclerotic lesion was 3.15 times (95% confidence interval, 1.59-6.27) more likely than a mixed lesion to have a diagnosis (p = 0.001). MRS can be used to characterize musculoskeletal lesions, particularly solid nonsclerotic lesions.

The metabolic features of normal pancreas and pancreatic adenocarcinoma: preliminary result of in vivo proton magnetic resonance spectroscopy at 3.0 T

OBJECTIVE

The objective of the study was to analyze the metabolic features and distribution of normal pancreas and pancreatic adenocarcinoma while determining the biomarker of pancreatic cancerous process.

METHODS

Twenty-seven control and 29 pancreatic adenocarcinoma patients underwent breath-hold 3-T proton magnetic resonance spectroscopy. The ratios of lipid (lipid/InW), choline-containing compounds (CCCs/InW), and fatty acids (FAs/InW) to nonsaturated internal water (InW) of the normal pancreas head and body-tail region, with cancerous and noncancerous regions in pancreatic adenocarcinoma, were calculated.

RESULTS

In normal pancreas, there were no statistical difference in the ratios of FAs to InW and lipid to InW of different regions, but CCCs/InW of body-tail area was greater than that of head (7.28 × 10⁻⁴ vs 3.23 × 10⁻⁴). In pancreatic cancer, FAs/InW and lipid/InW between cancerous and noncancerous region were different (3.44 × 10⁻⁴ vs 16.3 × 10⁻⁴ and 7.78 × 10⁻⁴ vs 36.3 × 10⁻⁴, respectively). Choline-containing compounds/InW in cancerous region was smaller than that in noncancerous region of pancreatic head cancer (1.62 × 10⁻⁴ vs 5.69 × 10⁻⁴) but similar to such region in body-tail cancer. Lipid/InW dropped in noncancerous regions (from 0.67 to 0.36), whereas there were no differences in FAs/InW and CCCs/InW between normal pancreas regions and noncancerous regions in pancreatic cancer.

CONCLUSIONS

In normal pancreas, CCCs of body-tail region was greater than that of head. Whereas in pancreatic adenocarcinoma, CCCs, FAs, and lipid were all decreased in cancerous region, lipid in the noncancerous region was also decreased compared with normal pancreas. Lipid may be the potential sensitive biomarker for pancreatic cancer.

Medical management of pheochromocytoma: Role of the endocrinologist

Pheochromocytoma is a rare tumor arising from chromaffin cells in adrenal medulla or other paraganglia in the body, which may be associated with many genetic syndromes and mutation. The role of endocrinologist is in biochemical diagnosis of suspected cases; its anatomic and functional localization with the help of imaging like CT, MRI, and nuclear scanning; preoperative control of hypertension; and postoperative follow-up of cases that have undergone surgical resection. Familial and genetic screening of cases and their family is important to detect occult cases. Endocrinologist will also play a role in cases with malignant pheochromocytoma in assessment of metastasis, control, chemoradiotherapy, and follow-up.

[Diagnosis and management of adrenal incidentaloma]

The growing demand for imaging tests and the progressive aging of the population have led to a progressive increase in the detection of indeterminate adrenal lesions. Once an adrenal incidentaloma is detected, clinical and hormone tests together with a battery of imaging techniques (CT, MRI, PET/CT…) make it possible to determine the cause in most cases. In this article, we discuss the advantages and limitations of each technique. We show the imaging characteristics of the most common adrenal lesions and propose a diagnostic algorithm to enable their diagnosis.

Adrenocortical carcinoma: the range of appearances on CT and MRI

OBJECTIVE

Adrenocortical carcinoma (ACC) is a rare, aggressive tumor arising from the adrenal cortex that typically presents late with a large mass. The increased use of cross-sectional imaging for unrelated reasons has led to a greater number of ACCs being detected incidentally at an earlier stage. Recognition of the typical clinical, biochemical, and imaging findings is imperative for rapid diagnosis, prompt intervention, and early use of the appropriate therapy.

CONCLUSION

Cross-sectional imaging with CT and MRI is essential for determining the extent of local and distant tumor spread. Complete surgical resection is currently the only potentially curative treatment of ACC, and the information attained from CT and MRI is important to guide surgery and further patient management.

Update on imaging of the adrenal cortex

PURPOSE OF REVIEW

To explain the rationale behind and findings on both established and newer techniques in adrenal cortical imaging. We also discuss management of incidentally found adrenal lesions.

RECENT FINDINGS

Computed tomography, MRI and PET all have a role to play in imaging of adrenal lesions.

SUMMARY

The role of adrenal imaging is to differentiate benign 'leave-alone' lesions from those that warrant further management.

Comparison of 3D two-point Dixon and standard 2D dual-echo breath-hold sequences for detection and quantification of fat content in renal angiomyolipoma

PURPOSE

To assess the utility of a 3D two-point Dixon sequence with water-fat decomposition for quantification of fat content of renal angiomyolipoma (AML).

METHODS

84 patients underwent renal MRI including 2D in-and-opposed-phase (IP and OP) sequence and 3D two-point Dixon sequence that generates four image sets [IP, OP, water-only (WO), and fat-only (FO)] within one breath-hold. Two radiologists reviewed 2D and 3D images during separate sessions to identify fat-containing renal masses measuring at least 1cm. For identified lesions subsequently confirmed to represent AML, ROIs were placed at matching locations on 2D and 3D images and used to calculate 2D and 3D SI(index) [(SI(IP)-SI(OP))/SI(IP)] and 3D fat fraction (FF) [SI(FO)/(SI(FO)+SI(WO))]. 2D and 3D SI(index) were compared with 3D FF using Pearson correlation coefficients.

RESULTS

41 AMLs were identified in 6 patients. While all were identified using the 3D sequence, 39 were identified using the 2D sequence, with the remaining 2 AMLs retrospectively visible on 2D images but measuring under 1cm. Among 32 AMLs with a 3D FF of over 50%, both 2D and 3D SI(index) showed a statistically significant inverse correlation with 3D FF (2D SI(index): r=-0.63, p=0.0010; 3D SI(index): r=-0.97, p<0.0001).

CONCLUSION

3D two-point Dixon sequence may provide a reasonable alternative to 2D dual-echo sequence for detection of renal AML and may have additional value for quantification of fat content of these lesions given the observation that 3D FF, unlike 2D and 3D SI(index), is not limited by ambiguity of water or fat dominance. This may assist clinical management of AML given evidence that fat content predicts embolization response.

Cancer imaging: novel concepts in clinical magnetic resonance imaging

Cancer is a major public health problem in the Western world. Imaging is of crucial importance in oncology, because it may reduce cancer-related morbidity and mortality. To improve tumour evaluation, there is a need for functional imaging modalities that go beyond gross assessment of anatomical abnormalities and allow visualization and quantification of biochemical processes in vivo. Magnetic resonance imaging (MRI) not only provides anatomical information, but also offers a wide range of functional sequences that may aid the evaluation of cancerous lesions. Furthermore, MRI provides the opportunity to guide and monitor anticancer therapies noninvasively. The aim of this review is to highlight some of the most promising developments of MRI in the functional assessment of cancer and the guidance and monitoring of (novel) anticancer therapies.

Adrenal imaging

OBJECTIVE

Adrenal nodules are frequently encountered on current high-resolution imaging, and accurate characterization of such lesions is critical for appropriate patient care. Our article highlights how imaging techniques such as CT densitometry, CT washout characteristics, chemical shift MRI, PET, and PET/CT help characterize most adrenal lesions. We focus on these techniques as well as specifically, because of space constraints, the varied imaging appearances of adrenocortical carcinoma, pheochromocytoma, and lymphoma on these techniques.

CONCLUSION

The imaging characterization of adrenal lesions has continued to advance over the past decade as new technologies have evolved. CT, MRI, PET, and PET/CT are now established clinical techniques capable of differentiating benign from malignant adrenal lesions.

Clinical management of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare and heterogeneous malignancy, and most of the diagnostic and therapeutic strategies are not fully established according to criteria of evidence-based medicine. However, recently collaborative efforts (e.g. International Consensus Conference 2003 and networks like the European Network for the Study of Adrenal Tumours (ENSAT)) have significantly advanced the field. This article summarizes current standards in the management of ACC. In patients with suspected ACC a thorough endocrine and imaging work-up is followed by complete (Ro) resection of the tumour by an expert surgeon and initiation of adjuvant mitotane. In advanced disease not amenable to radical resection, cytotoxic drugs will be added to mitotane. The most promising regimens (etoposide, doxorubicin, cisplatin plus mitotane and streptozotocin plus mitotane) are currently compared in an international phase-III trial. Several targeted therapies are under investigation (e.g. IGF-1 inhibitors, sunitinib, sorafenib) and may lead to new treatment options.

Characterization of adrenal pheochromocytoma using respiratory-triggered proton MR spectroscopy: initial experience

OBJECTIVE

The aim of our study was to evaluate the feasibility of respiratory-triggered proton single-voxel MR spectroscopy for the diagnosis of adrenal pheochromocytoma and to determine whether certain spectral resonances detected on single-voxel MR spectroscopy are specific for adrenal pheochromocytomas compared with adrenal adenomas.

CONCLUSION

Adrenal pheochromocytomas have a unique MR spectral signature, showing 6.8 ppm resonance that is not seen in adenomas. This unique spectral signature may be attributed to the presence of catecholamines and catecholamine metabolites that are abundant in pheochromocytomas.