Differentiation of malignant from benign pheochromocytomas with diffusion-weighted and dynamic contrast-enhanced magnetic resonance at 3.0 T.
ABSTRACT To retrospectively evaluate the usefulness of the apparent diffusion coefficients (ADCs) and dynamic contrast-enhanced magnetic resonance (MR) imaging for differentiation of malignant from benign pheochromocytomas at 3.0-T MR.
The Institutional Review Board approved this retrospective study, and informed consent was waived. Forty patients with pheochromocytomas underwent diffusion-weighted (DW) MR imaging in addition to T1- and T2-weighted sequences, chemical shift imaging techniques, and dynamic contrast-enhanced MR imaging at 3.0-T MR imaging system. In each patient, precontrast single-shot spin-echo echo-planar DW imaging was performed with b values of 0 and 800 seconds/mm². In each patient, 3-dimensional fat-saturated T1-weighted dynamic contrast-enhanced MR imaging was performed at baseline (precontrast), during the arterial phase, and 1, 2, 3, and 5 minutes after contrast injection. Diagnosis was based on pathologic findings in surgical specimens. Independent samples t test was used to compare ADCs of benign and malignant pheochromocytomas. Receiver operating characteristic curve analysis was used to test the ability of ADCs in differentiating malignant from benign pheochromocytomas. Differences in dynamic contrast-enhanced patterns between malignant and benign pheochromocytomas were analyzed.
Pathologic diagnoses revealed that 29 pheochromocytomas (three from both adrenal glands of the same patient) were benign and 13 were malignant. With b values of 0 and 800 seconds/mm², mean ± SD ADC of malignant pheochromocytomas ([1.175 ± 0.132] × 10⁻³ mm²/s) was larger than that of benign ones ([0.918 ± 0.124] × 10⁻³ mm²/s), and the difference was significant (P < 0.001). Apparent diffusion coefficients obtained with b values of 0 and 800 seconds/mm² were effective for distinguishing malignant from benign pheochromocytomas (area under the receiver operating characteristic curve, 0.906): A threshold value of 1.016 × 10⁻³ mm²/s permitted distinction with high sensitivity (93.3%) and specificity (77.8%). In dynamic contrast-enhanced MR imaging, malignant pheochromocytomas got peak signal intensity earlier (at arterial phase) than benign ones (at 1 minute after contrast injection).
In our limited study, ADCs in DW imaging with b values of 0 and 800 seconds/mm and dynamic contrast-enhanced pattern of malignant pheochromocytomas were significantly different from that of benign ones, suggesting that DW imaging and dynamic contrast-enhanced MR imaging may be useful in preoperative characterization and prognosis of pheochromocytomas, especially for those without obvious metastasis and vascular invasion.
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ABSTRACT: Head and neck paragangliomas (HNPGLs) account for approximately 3% of all paragangliomas (PGLs). Most often, HNPGLs are benign, nonsecreting, and slowly progressing. The initial physical examination and biochemical diagnosis usually adds very little to the proper diagnosis of these tumors, and, therefore, radiologists and nuclear medicine physicians play a pivotal role in providing the initial diagnosis, the locoregional staging, and the plan for detecting potential multicentric or metastatic lesions. Based on several current studies, the most accurate use of HNPGL-specific initial and subsequent imaging modalities must be guided by the knowledge of genetics and the specifically measured biochemical profile of these tumors for the proper management of these patients. Thus, this short review article presents the application of the most up-to-date anatomical and functional imaging approaches to HNPGLs tightly linked to the clinical management of these patients. Based on the most recent studies, 18F-FDOPA PET/CT has been shown to be a useful addition to anatomical imaging in the preoperative localization and molecular assessment of HNPGLs. It is estimated that the frequency of metabolically active PGLs on 18F-FDOPA PET/CT in this region is higher than 90%. For patients with hereditary PGL syndromes, (18)F-FDG-PET/CT should be reserved. Imaging of somatostatin receptors using Octreoscan or 68Ga-labeled somatostatin analogues plays an important role for selecting patients for targeted radiation therapy. This review also concludes that it is expected that in the near future, these patients will indeed benefit from new diagnostic approaches based on the identification of new targets by molecular profiling studies that will result in the development of novel PGL-specific radiopharamceuticals.Seminars in nuclear medicine 11/2013; 43(6):462-473. DOI:10.1053/j.semnuclmed.2013.06.005 · 3.13 Impact Factor
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ABSTRACT: The aim of this study was to evaluate the utility of apparent diffusion coefficient (ADC) values in differentiation between solid adrenal masses. The ADC values of 73 adrenal lesions (54 benign, 19 malignant) in 69 patients were measured at b 100, 600 and 1000 gradients on diffusion-weighted magnetic resonance imaging (DW-MRI). No statistically significant difference was found between ADC values of benign and malignant adrenal masses, nonadenomatous benign adrenal masses and malignant adrenal masses, adrenal adenomas and nonadenomatous lesions, adenomas and metastases, adenomas and pheochromocytomas, metastases and pheochromocytomas. ADC values are not helpful in the differentiation between solid adrenal masses.Clinical imaging 01/2013; DOI:10.1016/j.clinimag.2013.11.003 · 0.60 Impact Factor
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ABSTRACT: Head and neck paragangliomas (HNPGLs) are rare neuroendocrine tumors belonging to the family of pheochromocytoma/paraganglioma neoplasms. Despite advances in understanding the pathogenesis of these tumors, the growth potential and clinical outcome of individual cases remains largely unpredictable. Over several decades, surgical resection has long been the treatment of choice for HNPGLs. However, increasing experience in various forms of radiosurgery has been reported to result in curative-like outcomes, even for tumors localized in the most inaccessible anatomical areas. The emergence of such new therapies challenges the traditional paradigm for the management of HNPGLs. This review will assist and guide physicians who encounter patients with such tumors, either from a diagnostic or therapeutic standpoint. This review will also particularly emphasize current and emerging knowledge in genetics, imaging, and therapeutic options, as well as the health-related quality of life for patients with HNPGLs.Endocrine Reviews 07/2014; 35(5):er20141026. DOI:10.1210/er.2014-1026 · 19.36 Impact Factor