Value of chemical shift subtraction MRI in characterization of adrenal masses

Laparoscopic resection for a case preoperatively diagnosed as adrenal rest tumor in the liver: A case report

INTRODUCTION AND IMPORTANCE

Adrenal rest tumors (ARTs) are frequently found in the abdominal axis and testis and are often detected incidentally during surgery or autopsy. The standard treatment is complete resection due to their malignant potential; however, precise preoperative diagnosis is difficult due to the similarity of the radiological findings of this disease with those of hepatocellular carcinoma (HCC) and angiomyolipoma.

CASE PRESENTATION

A 58-year-old woman was diagnosed with a tumor through a physical examination and came to our clinic for a close examination. Dynamic computed tomography showed a tumor with a diameter of 27 mm that occupied segment 7 (S7) of the liver. The tumor was slightly enhanced in the arterial phase and washed out in the portal phase. Magnetic resonance imaging (MRI) demonstrated that this round tumor protruded from the liver surface and had high signal intensity on T2-weighted imaging. The tumor showed a high signal intensity on diffusion-weighted imaging. Chemical shift imaging revealed the markedly low intensity of the tumor. The preoperative diagnosis was suspected hepatic ART. Laparoscopic S7 partial resection was performed. The operative duration was 147 min, and the blood loss was 10 mL. The patient was discharged from the hospital on postoperative day 5. The pathological diagnosis was ART.

CLINICAL DISCUSSION

Hepatic ART (HART) is diagnosed preoperatively as HCC in most cases, and resection is rarely reported. The most standard treatment for HART is surgery for possible malignancy. Recent advances in radiological imaging have made it possible to distinguish HART from HCC using MRI chemical shift images. In the case of a highly vascular and fatty tumor such as the present case, HART diagnosis can be made preoperatively using MRI chemical shift imaging. This case is the first reported preoperative diagnosis of HART using chemical shift imaging.

CONCLUSIONS

We report a case of laparoscopic radical resection in a patient preoperatively diagnosed with hepatic ART. Chemical shift imaging in MRI is essential for distinguishing ART from HCC.

Differentiation between adrenocortical carcinoma and lipid-poor adrenal adenoma using a multiparametric MRI-based diagnostic algorithm

PURPOSE

The purpose of this study was to evaluate the capabilities of multiparametric magnetic resonance imaging (MRI) in differentiating between lipid-poor adrenal adenoma (LPAA) and adrenocortical carcinoma (ACC).

MATERIALS AND METHODS

Patients of two centers who underwent surgical resection of LPAA or ACC after multiparametric MRI were retrospectively included. A training cohort was used to build a diagnostic algorithm obtained through recursive partitioning based on multiparametric MRI variables, including apparent diffusion coefficient and chemical shift signal ratio (i.e., tumor signal intensity index). The diagnostic performances of the multiparametric MRI-based algorithm were evaluated using a validation cohort, alone first and then in association with adrenal tumor size using a cut-off of 4 cm. Performances of the diagnostic algorithm for the diagnosis of ACC vs. LPAA were calculated using pathology as the reference standard.

RESULTS

Fifty-four patients (27 with LPAA and 27 with ACC; 37 women; mean age, 48.5 ± 13.3 [standard deviation (SD)] years) were used as the training cohort and 61 patients (24 with LPAA and 37 with ACC; 47 women; mean age, 49 ± 11.7 [SD] years) were used as the validation cohort. In the validation cohort, the diagnostic algorithm yielded best accuracy for the diagnosis of ACC vs. LPAA (75%; 46/61; 95% CI: 55-88) when used without lesion size. Best sensitivity was obtained with the association of the diagnostic algorithm with tumor size (96%; 23/24; 95% CI: 80-99). Best specificity was obtained with the diagnostic algorithm used alone (76%; 28/37; 95% CI: 60-87).

CONCLUSION

A multiparametric MRI-based diagnostic algorithm that includes apparent diffusion coefficient and tumor signal intensity index helps discriminate between ACC and LPAA with high degrees of specificity and accuracy. The association of the multiparametric MRI-based diagnostic algorithm with adrenal lesion size helps maximize the sensitivity of multiparametric MRI for the diagnosis of ACC.

Low-Field Magnetic Resonance Imaging: Its History and Renaissance

ABSTRACT

Low-field magnetic resonance imaging (MRI) systems have seen a renaissance recently due to improvements in technology (both hardware and software). Originally, the performance of low-field MRI systems was rated lower than their actual clinical usefulness, and they were viewed as low-cost but poorly performing systems. However, various applications similar to high-field MRI systems (1.5 T and 3 T) have gradually become possible, culminating with high-performance low-field MRI systems and their adaptations now being proposed that have unique advantages over high-field MRI systems in various aspects. This review article describes the physical characteristics of low-field MRI systems and presents both their advantages and disadvantages for clinical use (past to present), along with their cutting-edge clinical applications.

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.

The efficacy of the 3-dimensional vibe-caipirinha-dixon technique in the evaluation of pancreatic steatosis

Background/aim

CAIPIRINHA is a new technique in abdominal imaging. Pancreatic steatosis (PS) is a subject of increasing scientific interest. The aim of this study was to investigate the efficacy of the isotropic 3D-VIBE- CAIPIRINHA -DIXON technique on a new generation 3-tesla MR unit in the evaluation of PS.

Materials and methods

In this retrospective study, the imaging findings of 49 patients with PS and 41 control subjects were examined. The pancreas-to-spleen ratio (PSR), pancreas-to-muscle ratio (PMR), and pancreatic signal intensity index (PSII) were defined as 3 new parameters and these indexes were calculated from the in-phase/out of phase 3D-VIBE- CAIPIRINHA-DIXON images.

Results

The PSR, PMR, and PSII values were significantly different between the patient and control groups (P = 0.001, P = 0.009, P < 0.001, respectively). Statistically significant differences were observed between patient and control groups for ROI measurements of fatty areas on these sequences/images: subtraction (in-out) (P < 0.001), T2W HASTE (P < 0.001), DIXON-fat (P < 0.001), fat-suppressed T1W (P = 0.002), and subtraction (out-in) (P = 0.010).

Conclusion

Evaluation of PS with the 3D-VIBE-CAIPIRINHA-DIXON technique can be made rapidly and effectively.

Characterization of adrenal lesions on chemical shift MRI: comparison of 1.5 T and 3 T MRI

PURPOSE

To compare three chemical shift MRI techniques [two-dimensional (2D) dual gradient echo (dGRE), 3D VIBE, and 3D VIBE-Dixon] at 3 T and 2D dGRE technique at 1.5 T to assess their ability of detecting microscopic fat in adrenal adenomas and differentiating between adenomas and non-adenomas.

METHODS

Seventy-eight patients with 97 lesions (78 adenomas, 19 non-adenomas) underwent both 1.5 T and 3 T chemical shift MRI. The Wilcoxon signed-ranked test was used to determine if there was significant difference between the signal intensity index (SII) values of each technique to assess their ability to detect microscopic fat in adrenal adenomas. ROC analysis was performed for the SII values of each technique, the adrenal-to-spleen SI ratio of 2D dGRE technique at 3 T, and the fat fraction values of the 3D VIBE-Dixon technique to identify the optimal threshold for differentiation of adrenal adenomas from non-adenomas.

RESULTS

For detection of microscopic fat, the mean SII value of 2D dGRE technique at 1.5 T was significantly higher than that of the chemical shift imaging techniques at 3 T (p = 0.001). For discrimination of adenomas from non-adenomas, the area under the curve (AUC) and 95% confidence interval values of 2D dGRE technique at 1.5 T and 2D dGRE, 3D VIBE, 3D VIBE-Dixon techniques at 3 T were calculated as 1.00 (1.00-1.00), 0.991 (0.978-1.00), 0.999 (0.995-1.00), 0.993 (0.979-1.00), respectively, for the SII.

CONCLUSION

Chemical shift MRI at 1.5 T using the 2D dGRE technique provided the most accurate differentiation between adenomas and non-adenomas. However, there was no statistically significant difference between chemical shift imaging techniques at 1.5 T and 3 T.

Laparoscopic Trans-Abdominal Right Adrenalectomy for a Large Primitive Adrenal Oncocytic Carcinoma: A Case Report and Review of Literature

Patient: Male, 48

Final Diagnosis: Adrenal oncocytic carcinoma

Symptoms: Asymptomatic

Medication: —

Clinical Procedure: Transabdominal laparoscopic right adrenalectomy

Specialty: Surgery

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.

Update on CT and MRI of Adrenal Nodules

OBJECTIVE

The objective of this article is to review the current role of CT and MRI for the characterization of adrenal nodules.

CONCLUSION

Unenhanced CT and chemical-shift MRI have high specificity for lipid-rich adenomas. Dual-energy CT provides comparable to slightly lower sensitivity for the diagnosis of lipid-rich adenomas but may improve characterization of lipid-poor adenomas. Nonadenomas containing intracellular lipid pose an imaging challenge; however, nonadenomas that contain lipid may be potentially diagnosed using other imaging features. Multiphase adrenal washout CT can be used to differentiate lipid-poor adenomas from metastases but is limited for the diagnosis of hypervascular malignancies and pheochromocytoma.

Chemical shift MR imaging in the lumbar vertebra: the effect of field strength, scanner vendors and flip angles in repeatability of signal intensity index measurement

BACKGROUND

To evaluate the reproducibility of signal intensity index (SII) measurements with MRI systems from different vendors and with different field strengths, and to test the effectiveness of flip angle.

METHODS

Thirty-two healthy volunteers (mean age 35.3 ± 9.3 years) were enrolled in this ethics committee-approved study. Chemical shift MR imaging was performed on 1.5- and 3.0-T MR systems from three vendors. Two independent observers measured SII values in five lumbar segments. Inter- and intraobserver agreement was assessed using the interclass correlation coefficients (ICCs). Differences of mean SII values between different field strengths and MR vendors as well as flip angles were compared by using repeated-measures analysis of variance. Differences of mean SII values between different flip angles were also compared by using paired-sample t test.

RESULTS

Inter- and intra-observer correlation coefficients showed good agreement (all ICC > 0.75) when measuring SII values at different MR systems (ICCs ranging from 0.896 to 0.983) and flip angles (ICCs ranging from 0.824 to 0.983). There were no significant differences in mean SII values measured by different MR vendors with different field strengths (all p > 0.05 ranging from 0.337 to 0.824). The differences in the mean SII between the four different flip angles were statistically significant (all p < 0.05 ranging from < 0.001 to 0.004) except the group of flip angle 50° versus 70° (p = 0.116).

CONCLUSION

The SII measurement using chemical shift MR imaging may be comparable between different MR systems. Also high flip angles showed better stability to quantitate lumbar fat content.

Whole-Body MRI Screening in Asymptomatic Subjects; Preliminary Experience and Long-Term Follow-Up Findings

BACKGROUND

The aim of this study is to describe the technique and to evaluate the results of whole-body magnetic resonance imaging in an asymptomatic population.

MATERIAL/METHODS

Between March 2009 and December 2011, 118 consecutive subjects undergoing thorough medical check-up were prospectively included in the study. MRI was performed with a 205-cm moving table, parallel imaging and automatic image composing software.

RESULTS

In 83 subjects (70%), 103 benign lesions were detected. Two malignant (adrenal and renal carcinoma) lesions and one precancerous (pancreatic mucinous carcinoma) lesion were detected. The most common lesions were renal cysts, liver hemangiomas, liver cysts, thyroid nodules, and uterine leiomyomas.

CONCLUSIONS

WB-MRI is able to cover area from head to toes in one diagnostic work-up, and besides the anatomic regions evaluated by conventional radiological modalities, i.e. brain parenchyma, bones and extremities, can be evaluated in one examination.

Classic Cushing's syndrome in a patient with adrenocortical carcinoma

Adrenocortical carcinoma is an aggressive but rare neoplasm of the adrenal cortex, with an estimated incidence of approximately 2.5 per one million patients. The prognosis for patients with adrenocortical carcinoma is often very poor. Patients often present with symptoms of hormone hypersecretion but may also present with pain or a palpable mass. Imaging plays an important role in preoperative planning when clinical and biochemical findings are compatible with adrenal cortical carcinoma. We report a case of adrenocortical carcinoma in a young woman who presented with classical Cushing syndrome, but who had an atypical hormonal profile.

Chemical shift MRI can aid in the diagnosis of indeterminate skeletal lesions of the spine

OBJECTIVES

To evaluate the role of chemical shift MRI in the characterisation of indeterminate skeletal lesions of the spine as benign or malignant.

METHODS

Fifty-five patients (mean age 54.7 years) with 57 indeterminate skeletal lesions of the spine were included in this retrospective study. In addition to conventional MRI at 3 T which included at least sagittal T1WI and T2WI/STIR sequences, patients underwent chemical shift MRI. A cut-off value with a signal drop-out of 20 % was used to differentiate benign lesions from malignant lesions (signal drop-out <20 % being malignant).

RESULTS

There were 45 benign lesions and 12 malignant lesions. Chemical shift imaging correctly diagnosed 33 of 45 lesions as benign and 11 of 12 lesions as malignant. In contrast, there were 12 false positive cases and 1 false negative case based on chemical shift MRI. This yielded a sensitivity of 91.7 %, a specificity of 73.3 %, a negative predictive value of 97.1 %, a positive predictive value of 47.8 % and a diagnostic accuracy of 82.5 %.

CONCLUSIONS

Chemical shift MRI can aid in the characterisation of indeterminate skeletal lesions of the spine in view of its high sensitivity in diagnosing malignant lesions. Chemical shift MRI can potentially avoid biopsy in a considerable percentage of patients with benign skeletal lesions of the spine.

KEY POINTS

• Differentiating benign from malignant skeletal lesions of the spine can be challenging. • Utility of chemical shift MRI in characterising indeterminate spinal lesion is unreported. • This study demonstrates sensitivity 91.7 %, specificity 73.3 %, diagnostic accuracy 82.5 % for CSI. • CSI is useful in differentiating benign from malignant skeletal spine lesions. • Biopsy can potentially be avoided in some patients with benign skeletal lesions.

Adrenal adenoma and metastasis from clear cell renal cell carcinoma: can they be differentiated using standard MR techniques?

BACKGROUND

Chemical-shift magnetic resonance imaging (MRI) has been known to successfully differentiate adenomas from metastases. However, there has been concern that metastasis from extra-adrenal primary malignancies which contain high lipid content such as clear cell renal cell carcinoma (RCC) could mimic adrenal adenomas.

PURPOSE

To evaluate the ability of MR to differentiate adrenal adenoma from metastasis using chemical-shift imaging and MR feature analysis in patients with clear cell RCC.

MATERIAL AND METHODS

This study was institutional review board-approved; informed consent was waived. Eleven patients with 13 metastases and 13 patients with 15 adrenal adenomas in patients with clear cell RCC for evaluation of an adrenal mass underwent MR. Signal intensity on in- and opposed-phases, signal intensity index (SII), size, T2 SI, cystic change, necrosis, and hemorrhage were evaluated. Statistical analyses included Student t-test and Fisher exact test. If available, precontrast CT attenuation of the adrenal adenomas was measured. SII was correlated with attenuation using Pearson correlation coefficient.

RESULTS

Mean size of adenomas was smaller than that of metastases (P < 0.002). Mean SII of adenomas (45.0% ± 24.6) was significantly greater than that of metastases (6.6% ± 4.7; P < 0.001). With a threshold of 16.5% for SII, the sensitivity, specificity, and accuracy for adenomas were 80%, 100%, and 89.2%, respectively. All six lipid-rich adenomas were diagnosed as adrenal adenoma. Three of eight (37.5%) lipid-poor adenomas were misdiagnosed as metastases. While up to 53.8% (7/13) of the metastases demonstrated cystic change, necrosis, or hemorrhage, only one (6.7%) adenoma exhibited cystic change or necrosis (P < 0.05 for all). Precontrast attenuation and SII were significantly correlated: r = -0.810 (P < 0.001).

CONCLUSION

In patients with clear cell RCC who underwent MR for adrenal masses, SII and MR features such as cystic change, necrosis, and hemorrhage were helpful in differentiating adenomas from metastases.

Quantification of cervical spine muscle fat: a comparison between T1-weighted and multi-echo gradient echo imaging using a variable projection algorithm (VARPRO)

Background

Previous data using T1-weighted MRI demonstrated neck muscle fat infiltration (MFI) in patients with poor functional recovery following whiplash. Such findings do not occur in those with milder symptoms of whiplash, chronic non-traumatic neck pain or healthy controls, suggesting traumatic factors play a role. Muscle degeneration could potentially represent a quantifiable marker of poor recovery, but the temporal constraints of running a T1-weighted sequence and performing the subsequent analysis for muscle fat may be a barrier for clinical translation. The purpose of this preliminary study was to evaluate, quantify and compare MFI for the cervical multifidus muscles with T1-weighted imaging and a more rapid quantitative 3D multi-echo gradient echo (GRE) Dixon based method in healthy subjects.

Methods

5 asymptomatic participants with no history of neck pain underwent cervical spine MRI with a Siemens 3 Tesla system. The muscle and fat signal intensities on axial spin-echo T1-weighted images were quantitatively classified for the cervical multifidii from C3-C7, bilaterally. Additional axial GRE Dixon based data for fat and water quantification were used for comparison via paired t-tests. Inter-tester reliability for fat and water measures with GRE images were examined using 1) Pearson’s Intra-class correlation coefficient 2) Bland-Altman Plots and 3) Lin’s-Concordance Coefficient. P < 0.05 was used to indicate significance.

Results

Total mean (SD) MFI (C3-C7) for the multifidii obtained with T1-weighted imaging and GRE were 18.4% (3.3) (range 14-22%) and 18.8% (2.9) (range 15-22%), respectively. The Pearson correlation coefficients for inter-tester reliability on the GRE sequences for the C3-C7 multifidii ranged from .83 - .99, indicating high levels of agreement with segmental MFI measures. Bland-Altman Plots revealed all data points were within 2 SDs and concordance was established between 2-blinded raters, suggesting good agreement between two raters measuring fat and water with GRE imaging.

Conclusions

Results of this preliminary study demonstrate reliability between 2 raters of varying experience for MRI analysis of MFI with 3D GRE MRI. The quantification of MFI for healthy cervical musculature is comparable to T1-weighted images. Inclusion of larger samples of symptomatic data and histological comparison with the reference standard biopsy is warranted.

Fatty degeneration of multifidus muscle in patients with chronic low back pain and in asymptomatic volunteers: quantification with chemical shift magnetic resonance imaging

OBJECTIVE

To evaluate and compare the fatty degeneration of multifidus muscles by chemical shift magnetic resonance imaging (MRI) in patients with chronic low back pain and in asymptomatic volunteers.

MATERIALS AND METHODS

Sixty-five patients with lumbar disc pathology were selected prospectively for this study. The control group consisted of 25 asymptomatic volunteers. The patients were grouped according to the fatty degeneration of multifidus muscles by a semiquantitative method (grade 0-4) on axial T2 weighted imaging. Chemical shift MRI was performed in the axial plane using a double-echo fast low-angle shot (FLASH) sequence. Fatty degeneration was calculated through signal intensity suppression rate (SISR) and signal intensity index (SII).

RESULTS

The semiquantitative grading of fatty degeneration of the multifidus muscle was 0 in 25 of 65 patients (patient group 0), 1 in 20 patients (patient group 1), 2 in 20 patients (patient group 2). Neither grade 3 nor grade 4 were detected in patient groups. For the control group, patient group 0, patient group 1, and patient group 2, median SISR values were 5.00, -9.00, -17.50, and -22.50 %, respectively. SII median values were -4.20 % for the control group, 7.00 % for patient group 0, 12.50 % for patient group 1, and 19.50 % for patient group 2. SISR values in the multifidus muscle calculated for the patient groups were significantly lower than those calculated for the control group. SII values in patients groups were significantly higher than in the control group.

CONCLUSIONS

Chemical shift MRI may be a useful method to quantitatively evaluate the fatty degeneration in multifidus muscle in patients with low back pain.

Adrenal cortical adenoma arising from an adrenohepatic union

Although the observation of an adrenohepatic union is not a rare occurrence during autopsies, cases associated with this clinical entity are rarely described. We report a case with an adrenal cortical adenoma arising from adrenohepatic union tissue in a patient with a past history of a liver mass.

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.

Adrenal oncocytic neoplasm: a systematic review

INTRODUCTION

Oncocytic neoplasms as tumors arising in the adrenal glands are rare, usually considered as nonfunctional and benign. In the current literature, there are extremely limited reports of adrenal oncocytic neoplasms; as to date, only 147 cases have been described. The rarity of the event prompted this study which reviews and presents the incidence, histology, diagnosis and therapy of adrenal oncocytic neoplasms.

MATERIALS AND METHODS

A review by systematic literature search was done using the MEDLINE®/Cochrane libraries from 1950 to date using the medical subject headings 'oncocytoma', 'adrenal gland', 'adrenal oncocytoma', 'adrenal oncocytic neoplasm' and 'adrenal oncocytic carcinoma'.

RESULTS

Adrenal oncocytic neoplasm is a rare disease, usually incidentally detected because only 17% are functional adrenal masses. The typical oncocyte displays abundant granular eosinophilic cytoplasm, due to the accumulation of mitochondria. Computed tomography and magnetic resonance imaging are not able to identify or differentiate benign and malignant oncocytic neoplasms. The mainstay of therapy is adrenalectomy, recently performed by laparoscopy. The prognosis is good for benign tumors, while adrenocortical oncocytic carcinoma has a poor survival rate of only 5 years.

CONCLUSIONS

Adrenal oncocytic neoplasm, a rare and mostly benign tumor, usually presents as an incidental, large adrenal mass; surgery is the mainstay of therapy, by means of laparoscopy which is now the most diffuse approach to adrenalectomy.

Adrenal imaging: a comprehensive review

The discovery of an incidental adrenal mass (adrenal incidentaloma) continues to rise with the increasing use of cross-sectional imaging. Although most adrenal lesions are benign and asymptomatic, radiologists should guide evaluation of these lesions, whether benign or malignant. This article reviews the various imaging techniques used to evaluate adrenal masses and their relative strengths and weaknesses. It focuses on the most prevalent adrenal pathologies and their typical imaging characteristics, and concludes with a brief discussion of developing techniques, including diffusion-weighted imaging and dual-energy CT.

Assessment of association between low back pain and paraspinal muscle atrophy using opposed-phase magnetic resonance imaging: a population-based study among young adults

STUDY DESIGN

A cross-sectional imaging study of young adults.

OBJECTIVE

To evaluate whether severity of low back symptoms predicts atrophy in the paraspinal muscles of young adults.

SUMMARY OF BACKGROUND DATA

Although an increased fat content of the lumbar muscles has been observed among adults with chronic LBP, there is limited knowledge of this association in younger populations.

METHODS

The population-based study sample consisted of 554 subjects (321 females and 233 males) from the 1986 Northern Finland Birth Cohort. Latent Class Analysis (LCA) was used to cluster the subjects according to the low back symptoms and functional limitations at 18, 19, and 21 years. The mean age of the subjects at the time of the MRI (magnetic resonance imaging) was 21 years (range, 20-23). Muscle atrophy was evaluated by assessing the fat content of the paraspinal muscles using Opposed-Phase MRI. The cross-sectional areas (CSAs) of the erector spinae and multifidus muscles were also measured.

RESULTS

LCA analysis produced five clusters differing in symptoms, ranging from a cluster (n = 65) in which subjects had high likelihood of symptoms and functional limitations at all time points, to a cluster (n = 165) with no pain ever. The fat content of the multifidus muscles was significantly higher among women than men (14.0% vs. 5.3%, P < 0.001), but it was not significantly associated with symptom severity. The CSA of both erector spinae and multifidus muscles were significantly larger among men than women (P < 0.001 in all of the muscles), but were not associated with pain severity.

CONCLUSION

Low back symptoms and functional limitations over a 3-year period were not associated with increased fat content or a reduction in the cross-sectional area of lumbar paraspinal muscles among young adults.

[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.

Evaluation of vertebral bone marrow fat content by chemical-shift MRI in osteoporosis

OBJECTIVE

To quantitatively evaluate vertebral bone marrow fat content and investigate its association with osteoporosis with chemical-shift magnetic resonance imaging (CS-MRI).

MATERIALS AND METHODS

Fifty-six female patients (age range 50-65 years) with varying bone mineral densities as documented with dual x-ray absorptiometry (DXA) were prospectively included in the study. According to the DXA results, the patients were grouped as normal bone density, osteopenic, or osteoporotic. In order to calculate fat content, the lumbar region was visualized in the sagittal plane by CS-MRI sequence. "Region of interest" (ROI)s were placed within L3 vertebral bodies and air (our reference point) at different time points by different radiologists. Fat content was calculated through "signal intensity (SI) suppression rate" and "SI Index". The quantitative values were compared statistically with those obtained from DXA examinations. Kruskal-Wallis, and Mann-Whitney U tests were used for comparisons between groups. The reliability of the measurements performed by two radiologists was evaluated with the "intraclass correlation coefficient". This study was approved by an institutional review board and all participants provided informed consent to participate in the study.

RESULTS

Eighteen subjects with normal bone density (mean T score, 0.39 ± 1.3 [standard deviation]), 20 subjects with osteopenia (mean T score, -1.79 ± 0.38), and 18 subjects with osteoporosis (mean T score, -3 ± 0.5) were determined according to DXA results. The median age was 55.9 (age range 50-64 years) in the normal group, 55.5 (age range 50-64 years) in the osteopenic group, and 55.1 (age range 50-65 years) in the osteoporotic group (p = 0.872). In the CS-MRI examination, the values of "SI suppression ratio" and "SI Index" (median [min:max]) were calculated by the first and second reader, independently. There was no statistically significant difference between the groups with regard to vertebral bone marrow fat content (p > 0.05). According to the "intraclass correlation coefficient", the measurements were reliable (0.55 and 0.60).

CONCLUSIONS

Vertebral bone marrow fat content calculated with CS-MRI is not a reliable parameter for predicting bone mineral density in female patients aged between 50 and 65 years.

PET/CT imaging in different types of lung cancer: an overview

Lung cancer (LC) still represents one of the most common tumours in both women and men. PET/CT is a whole-body non-invasive imaging procedure that has been increasingly used for the assessment of LC patients. In particular, PET/CT added value to CT is mainly related to a more accurate staging of nodal and metastatic sites and to the evaluation of the response to therapy. Although the most common PET tracer for LC evaluation is 18F-FDG, new tracers have been proposed for the evaluation of lung neuroendocrine tumours (68Ga-DOTA-peptides, 18F-DOPA) and for the assessment of central nervous system metastasis (11C-methionine). This review focuses on the main clinical applications and accuracy of PET/CT for the detection of non-small cells lung cancer (NSCLC), broncho-alveolar carcinoma (BAC), small cells lung cancer (SCLC), lung neuroendocrine tumours (NET) and solitary pulmonary nodules (SPN).

EUS-FNA for the detection of left adrenal metastasis in patients with lung cancer

In patients with lung cancer, enlarged or (18)Fluoro-deoxyglucose positron emission tomography ((18)FDG-PET) positive left adrenal glands are suspected for distant metastases and require tissue confirmation for a definitive assessment. The aim of this study was to assess the sensitivity of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for left adrenal metastases in lung cancer patients with a suspect adrenal gland based on imaging. EUS-FNA findings of patients with (suspected) lung cancer and CT enlarged or (18)FDG-PET positive left adrenal glands were retrospectively evaluated. In the absence of metastases at EUS, clinical and radiological follow-up was obtained. In 85 patients, EUS-FNA demonstrated left adrenal metastases of lung cancer in 53 (62%), benign adrenal tissue in 25 (29%), a metastasis from colon carcinoma in 1 (1%) and a primary adrenocortical carcinoma in 1 (1%) patient. In five patients (5.9%), the aspirates contained non-representative material. EUS outcomes were false negative in two patients. Sensitivity and negative predictive value (NPV) for EUS-FNA of the left adrenal gland were at least 86% (95% CI 74-93%) and 70% (95% CI 50-85%). No complications occurred. EUS-FNA is a sensitive, safe and minimally invasive technique to provide tissue proof of left adrenal metastases in patients with (suspected) lung cancer and enlarged or (18)FDG-PET positive adrenal glands. Therefore, EUS-FNA qualifies as the staging test of choice for patients with lung cancer with suspected left adrenal metastases.

A multi-center study on the surgical management of metastatic disease to adrenal glands

BACKGROUND

In the management of adrenal lesions in oncological patients, many issues are still controversial: morphological signs of suspected malignancy, accuracy of imaging examinations, use of fine needle aspiration (FNA), and the role of laparoscopy. The present study attempts to address these questions through the evaluation of the management of adrenal metastases (AM) in a wide cohort of patients included in the Italian Register of Endoscopic Adrenal Surgery.

METHODS

In January 2009, all patients recorded on the Register were evaluated, on the basis of CT scan, MRI, and FNA. The diagnostic, surgical, and follow-up data of 95 patients with pre-operative AM diagnosis have been reviewed. On the basis of the fulfilled criteria three patterns were identified: "diagnostic", "suspect," and "non-diagnostic."

RESULTS

CT scan sensitivity was 41.5%/77.9% and specificity was 54.5%/90.9% for "diagnostic"/"diagnostic" + "suspect" examinations, respectively. MRI sensitivity was 15.7%/78.9% and specificity was non-determinate/83.3% for "diagnostic"/"diagnostic" + "suspect" exams, respectively. Sensitivity of FNA was 33.3%. About surgery, conversions rate was 16.6%; no mortality or re-operations were reported; complications rate was 10.7%; and no relation was noted between tumor size and surgical outcome. Mean survival was 32 months; 5-year survival was 23%, independent of AM size; survival for lung AM was similar to that of breast and kidney AM.

CONCLUSIONS

Laparoscopy for AM, in expert hand, seems to be a feasible and oncologically safe approach. Due to the unsatisfactory diagnostic accuracy for AM, every oncological patient with suspect adrenal lesions should be encouraged to undergo this surgical procedure.

Using chemical-shift MR imaging to quantify fatty degeneration within supraspinatus muscle due to supraspinatus tendon injuries

The objective of this study was to prospectively quantify the fatty degeneration of supraspinatus (SSP) muscle due to SSP tendon injuries by using chemical-shift magnetic resonance imaging (CS-MRI). Forty-one patients with suspected rotator cuff tear or impingement examined with MR arthrography were included in the study. The following images were obtained after injection of diluted gadolinium chelate into glenohumeral joint: fat-saturated T1-weighted spin echo in the coronal, axial, and sagittal-oblique plane; fat-saturated T2-weighted and intermediate-weighted fast spin-echo in the coronal-oblique plane; and T1-weighted spin echo in the sagittal-oblique plane. CS-MRI was performed in the coronal plane using a double-echo fast low-angle shot (FLASH) sequence. SSP tendon changes were classified as normal, tendinosis, and partial and complete tear according to MR arthrography findings. Fatty degeneration was quantified after measurement of signal intensity values within the region of interest (ROI) placed over SSP muscle. Signal intensity (SI) suppression ratio and SI index were calculated with the values obtained. Degrees of fatty degeneration depicted in normal subjects and subjects with rotator cuff injuries were compared. Median (min:max) was used as descriptive values. SI suppression ratio was -3.5% (-15.5:3.03) in normal subjects, whereas it was -13.5% (-28.55:-6.60), -30.7% (-41.5:-20.35), and -43.75% (-62:-24.90) in tendinosis, partial and complete tears, respectively. SI index was 0.75% (-6:11.5) in normal subjects. It was 10% (4.50:27), 26.5% (19.15:35.5), and 41% (23.9:57) in tendinosis, partial and complete tears, respectively. The increase in degree of fatty degeneration parallels the seriousness of tendon pathology. CS-MRI is a useful method for grading fat accumulation within SSP muscle.

Magnetic resonance characterization of pheochromocytomas in the abdomen and pelvis: imaging findings in 18 surgically proven cases

PURPOSE

To study the magnetic resonance imaging characteristics of adrenal and extra-adrenal pheochromocytomas in the abdomen and pelvis.

METHODS

We retrospectively reviewed 18 cases of pathologically proven cases of pheochromocytomas in the abdomen and pelvis. These patients have undergone magnetic resonance imaging evaluation before surgery. The study population included 10 men and 7 women (age range, 19-68 years; mean, 38 years). A consensus review of the magnetic resonance images was performed by 2 blinded expert observers. A qualitative evaluation was completed, and the tumors were classified by anatomical location, shape, T2 signal, contrast enhancement, and signal dropout on chemical shift pulse sequences.

RESULTS

On T2-weighted images, most lesions demonstrated mild to moderate increased signal intensity (SI) (n = 12), 5 lesions demonstrated a markedly increased SI, and only 1 lesion demonstrated an isointense SI on T2-weighted images.Five lesions demonstrated marked postcontrast enhancement. Three lesions demonstrated moderate enhancement, and 5 lesions demonstrated mild postcontrast enhancement.The pattern of enhancement was variable: 4 salt and pepper, 4 homogeneous, 3 heterogeneous, and 2 target with central necrosis and hemorrhage. None of the lesions contained significant amount of intracellular lipid, as no lesions demonstrated greater than 16.5% signal dropout on out-of-phase compared with in-phase pulse sequences.

The indeterminate adrenal lesion

With the increasing use of abdominal cross-sectional imaging, incidental adrenal masses are being detected more often. The important clinical question is whether these lesions are benign adenomas or malignant primary or secondary masses. Benign adrenal masses such as lipid-rich adenomas, myelolipomas, adrenal cysts and adrenal haemorrhage have pathognomonic cross-sectional imaging appearances. However, there remains a significant overlap between imaging features of some lipid-poor adenomas and malignant lesions. The nature of incidentally detected adrenal masses can be determined with a high degree of accuracy using computed tomography (CT) and magnetic resonance imaging (MRI) alone. Positron emission tomography (PET) is also increasingly used in clinical practice in characterizing incidentally detected lesions. We review the performance of the established and new techniques in CT, MRI and PET that can be used to distinguish benign adenomas and malignant lesions of the adrenal gland.

Intra-renal adrenal adenoma: a compelling addition to the differential diagnosis of renal mass

We report a case of an adrenal rest arising in the kidney of a 37-year-old male. An incidental 4.5 cm right upper pole mass with a minimal amount of fat was discovered on computed tomography scan. Laparoscopic renal exploration and biopsy revealed angiomyolipoma on frozen section. However, final pathological analysis of the partial nephrectomy specimen revealed intra-renal adrenal adenoma. The diagnosis was confirmed by immunohistochemistries and transmission electron microscopy. We review the reported literature on intra-renal adrenal adenoma and highlight the aspects that raise the index of suspicion for this entity on the differential diagnosis of renal masses.

Chemical shift MRI: is there any contribution to morphologic evaluation of solid breast masses?

RATIONALE AND OBJECTIVES

To investigate the contribution of chemical shift magnetic resonance imaging for assessment of the margins of solid breast masses by benefiting from India ink artifact.

METHODS AND MATERIALS

Eighty-eight masses in 64 patients were evaluated in T1- and T2-weighted images, dynamic contrast and chemical shift studies according to Breast Imaging Reporting and Data System magnetic resonance lexicon. Subtraction images were automatically obtained by chemical shift imaging and dynamic studies. Each sequence was scored using a scale of 1 to 5 according to its ability to demonstrate margins separate from surrounding parenchyma. Breast parenchyma was evaluated as fatty and dense. The results were compared with the histopathologic results.

RESULTS

Twenty-eight (31.8%) of the lesions were localized in fatty breast, and the remaining 60 (68.2%) lesions were localized in dense breast. There were 34 (38.6%) benign and 54 (61.4%) malignant masses. In fatty breast, chemical shift subtraction and T1-weighted images were valuable both for the demonstration and differentiation of benign lesions (P < .05). None of the sequence was valuable for both the demonstration and differentiation of malignant lesions in fatty breasts (P > .05). In dense breasts, chemical shift subtraction and dynamic contrast subtraction images were valuable for both the demonstration and differentiation of benign and malignant lesions. Additional to these sequences, T2-weighted images was also valuable for benign lesions (P < .05).

CONCLUSION

Chemical shift subtraction can contribute to routine dynamic contrast subtraction in morphologic analysis particularly for the evaluation of margins of benign lesions in fatty breasts. It can also help in morphologic analysis of masses in dense breast.

PET, CT, and MR Imaging for Assessment of Thoracic Malignancy: Structure Meets Function

Imaging of patients with thoracic malignancy usually requires a multimodality approach. Each of these modalities has its own strengths and weaknesses. CT remains central to the staging and restaging of thoracic malignancies, but has recently been complemented with [18F]-2-fluoro-2-deoxy-D-glucose(FDG)-positron emission tomography (PET) imaging to maximize its potential. Furthermore, because FDG-PET/CT is useful at all stages of the workup and treatment of these patients, this modality has taken hold in the clinical realm for evaluation of patients with thoracic malignancy and is rapidly replacing PET-only imaging. MR imaging is also occasionally used in some patients with thoracic malignancies to improve disease staging or lesion characterization. PET/MR imaging may come to be used to evaluate patients with thoracic malignancies as well.

Quantitative evaluation of norcholesterol scintigraphy, CT attenuation value, and chemical-shift MR imaging for characterizing adrenal adenomas

OBJECTIVE

The objective of our study was to evaluate diagnostic ability and features of quantitative indices of three modalities: uptake rate on norcholesterol scintigraphy, computed tomography (CT) attenuation value, and fat suppression on chemical-shift magnetic resonance imaging (MRI) for characterizing adrenal adenomas.

METHODS

Image findings of norcholesterol scintigraphy, CT, and MRI were reviewed for 78 patients with functioning (n = 48) or nonfunctioning (n = 30) adrenal masses. The norcholesterol uptake rate, attenuation value on unenhanced CT, and suppression on in-phase to opposed-phase MRI were measured for adrenal masses.

RESULTS

The norcholesterol uptake rate, CT attenuation value, and MR suppression index showed the sensitivity of 60%, 82%, and 100%, respectively, for functioning adenomas of <2.0 cm, and 96%, 79%, and 67%, respectively, for those of >or=2.0 cm. A statistically significant correlation was observed between size and norcholesterol uptake, and between CT attenuation value and MR suppression index. Regarding norcholesterol uptake, the adenoma-to-contralateral gland ratio was significantly higher in cortisol releasing than in aldosterone-releasing adenomas.

CONCLUSIONS

The norcholesterol uptake rate was reliable for characterization of adenomas among adrenal masses of >or=2.0 cm. CT attenuation value and MR suppression index were well correlated with each other, and were useful regardless of mass size.

Preoperative imaging for metastasectomy

For most solid neoplasms, medical imaging is a vital component of tumor staging and surveillance. Imaging strategies vary according to the type and grade of primary neoplasm, tumor stage at diagnosis, tumor markers, previous therapies, and patient symptoms. In this article, we address imaging of individual organs (lung, liver, adrenals) and outline imaging strategies for specific types of neoplasms.

Sectional anatomy of the adrenal gland in the coronal plane

To provide practical anatomic data for the imaging diagnosis and surgical treatment of adrenal disease, we investigated the anatomy of the adrenal gland and its relationships to regional structures using 31 sets of serial coronal sections of upper abdomen of Chinese adult cadavers and correlated coronal magnetic resonance (MR) images of ten upper abdomens of adult healthy volunteers and coronal reconstructed multislice spiral computed tomography (MSCT) images of five patients without lesions in the adrenal gland. The adrenal glands were visualized mainly on the successive coronal sections between 18 mm anterior to the posterior margin of inferior vena cava and 24 mm posterior to the posterior margin of inferior vena cava. In general, the left adrenal gland was visualized two sections earlier than the right adrenal gland. On the plane through the anterior parts of bilateral renal hili (A18), the appearance rate of bilateral adrenal glands was 100%, and the maximal measurements of bilateral adrenal glands were visualized. The length, width, thickness of right adrenal body, thickness of medial limb and lateral limb were, respectively, 34.02 +/- 2.12 mm, 10.91 +/- 0.89 mm, 5.82 +/- 0.26 mm, 2.78 +/- 0.08 mm, 2.62 +/- 0.06 mm, whereas the measurements of left adrenal gland were 28.31 +/- 2.46 mm, 18.40 +/- 1.06 mm, 6.84 +/- 0.24 mm, 3.02 +/- 0.08 mm, 2.86 +/- 0.07 mm, respectively. The coronal plane has superior advantage in showing the bilateral adrenal glands. The shapes of adrenal glands are various, whereas the range of adrenal thickness is quite narrow. The thickness of adrenal medial and lateral limbs, especially the thickness of lateral limb are useful for the diagnosis of the bilateral adrenocortical disease.

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

PURPOSE

To prospectively determine the accuracy of in vivo proton ((1)H) magnetic resonance (MR) spectroscopy in distinguishing adrenal adenomas, pheochromocytomas, adrenocortical carcinomas, and metastases, with histologic or computed tomographic findings and follow-up data as the reference standards.

MATERIALS AND METHODS

This study was approved by the institutional ethics committee, and informed consent was obtained. Sixty consecutive patients (24 male and 36 female patients; mean age, 53 years) harboring adrenal tumors larger than 2 cm in diameter (mean diameter, 4.6 cm +/- 3.4 [standard deviation]) entered the study and were examined with a 1.5-T MR imaging system and point-resolved multivoxel (1)H MR spectroscopy. Thirty-eight patients had adenomas; 10, pheochromocytomas; five, carcinomas; and seven, metastases. Amplitude values for choline, creatine, lipid, and a metabolite peak at precession frequency of 4.0-4.3 ppm were measured. Metabolite ratios (choline-creatine, choline-lipid, lipid-creatine, and 4.0-4.3 ppm/creatine) and cutoff values (obtained by using receiver operating characteristic analyses) were obtained and compared for each type of adrenal mass, which was identified previously on the basis of clinical, hormonal, and pathologic evidence. Results were evaluated with chi(2) and Student t tests. Significance was inferred at P < .05.

RESULTS

Cutoff values of 1.20 for the choline-creatine ratio (92% sensitivity, 96% specificity; P < .01), 0.38 for the choline-lipid ratio (92% sensitivity, 90% specificity; P < .01), and 2.10 for the lipid-creatine ratio (45% sensitivity, 100% specificity) enabled adenomas and pheochromocytomas to be distinguished from carcinomas and metastases. A 4.0-4.3 ppm/creatine ratio greater than 1.50 enabled distinction of pheochromocytomas and carcinomas from adenomas and metastases (87% sensitivity, 98% specificity; P < .01). The best distinction was obtained by comparing choline-creatine and 4.0-4.3 ppm/creatine ratios.

CONCLUSION

(1)H MR spectroscopy can be used to characterize adrenal masses on the basis of spectral findings for benign adenomas, carcinomas, pheochromocytomas, and metastases.

Staging non-small cell lung cancer

Patients with newly diagnosed non-small cell lung cancer (NSCLC) need accurate tumor staging in order to direct appropriate therapy and establish prognosis; the tumor is usually staged using the TNM system. The major imaging modalities currently used for staging this disease are thoracic computed tomography (CT) (including the adrenal glands) and whole body fluorodeoxyglucose (FDG)-positron emission tomography (PET) scanning. CT is generally most useful in evaluating the T stage, i.e. local spread of the neoplasm, whereas PET is most helpful in assessing the N and M stages, i.e. regional and distant tumor spread, respectively. Integrated CT-PET imaging adds information compared to the use of either modality alone. PET findings frequently lead to upstaging the disease and thus prevent unindicated surgeries. Magnetic resonance imaging (MRI) is helpful in evaluating local extent of disease in patients with superior sulcus tumors and possible brachial plexus involvement. Staging accuracy using any of these imaging techniques is imperfect; therefore, pathologic confirmation of positive findings is recommended, whenever possible, before denying a patient potentially curative therapy.

The indeterminate adrenal mass in patients with cancer

With the increasing use of abdominal cross-sectional imaging, incidental adrenal masses are frequently detected. The commonest clinical question is whether these are benign adenomas or malignant primary or secondary masses. The nature of incidentally detected adrenal masses can be determined with a high degree of accuracy using computed tomography (CT) and magnetic resonance imaging (MRI) as benign adrenal masses such as myelolipomas, lipid-rich adenomas, adrenal cysts and adrenal haemorrhage which have pathognomonic imaging findings. However, there remains a significant overlap between the imaging features of some lipid-poor adenomas and malignant lesions. We review the recent advances in CT, MRI and positron emission tomography (PET) which can be used to distinguish between benign adenomas and malignant lesions of the adrenal gland.