Characterization of the Normal and Hyperplastic Thymus on Chemical-Shift MR Imaging

Takahashi, Koji; Inaoka, Tsukasa; Murakami, Noboru; Hirota, Hatsune; Iwata, Kunihiro; Nagasawa, Keiichi; Yamada, Terumasa; Mineta, Masayuki; Aburano, Tamio

doi:10.2214/ajr.180.5.1801265

Cited by 68 publications

(48 citation statements)

References 10 publications

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“…In patients with enlarged thymus older than 15 years of age, chemical shift MRI can diagnose thymic hyperplasia by detecting fatty infiltration within the thymus and is useful in its differentiation from neoplastic processes (15,16). In a series of 41 patients consisting of 23 thymic hyperplasia and 18 thymic neoplasm, chemical shift MRI could differentiate thymic hyperplasia from thymic neoplasms in all patients.…”

Section: Thymic Hyperplasia and Thymic Reboundmentioning

confidence: 99%

“…A recent report suggested chemical shift MRI to be beneficial in differentiation of thymomas from thymic hyperplasia in non-MG patients (15,16). MRI may provide similar results also in MG patients.…”

Section: Thymomamentioning

confidence: 99%

“…Dynamic multiphase gadolinium-enhanced study is useful in the assessment of vascularity and extracellular space volume of the lesions. Chemical shift imaging with 2D GRE is useful to detect tiny amounts of fat tissue in the mixture with water within the lesions (15,16) (Figs. 1, 2).…”

Section: Imaging Technique Mrmentioning

confidence: 99%

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Computed tomography and magnetic resonance imaging of mediastinal tumors

Takahashi¹,

Al-Janabi²

2010

Magnetic Resonance Imaging

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We describe the clinical, pathological, and imaging findings of mediastinal tumors with focus on thymic hyperplasia, thymic epithelial tumors, and germ cell tumors, malignant lymphoma, and various cystic masses. Chemical shift magnetic resonance imaging (MRI) is useful in characterization of the normal thymus and differentiation of hyperplastic thymus and thymic tumors. In contrast to noninvasive thymomas, invasive thymomas and thymic carcinomas show a more aggressive growth pattern. Local invasion and pleural spread are characteristic of invasive thymoma and mediastinal lymphadenopathy and distant metastasis suggest thymic carcinomas. Mature teratoma typically shows various computed tomography (CT) attenuation, and MR signal intensity depending on its contents and fat tissue and bone within the lesions are its characteristic findings. Seminomas typically have homogenous internal CT attenuation and MR signal intensity with minimal contrast enhancement. Nonseminomatous malignant germ cell tumors characteristically show prominent internal degenerative changes and invasion to the adjacent structures. In mediastinal lymphomas, a residual mass is common after treatment and MRI provides important information in distinguishing viable tumors from residual benign masses. Some mediastinal cysts may reveal high attenuation similar to solid lesions on CT depending on their contents and MRI can be useful in the differentiation of cystic masses from solid lesions.

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Section: Thymic Hyperplasia and Thymic Reboundmentioning

confidence: 99%

Section: Thymomamentioning

confidence: 99%

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Computed tomography and magnetic resonance imaging of mediastinal tumors

Takahashi¹,

Al-Janabi²

2010

Magnetic Resonance Imaging

Self Cite

176

131

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“…A unique method for characterizing the normal and hyperplastic thymus with chemical-shift MRI was reported recently (13). In that method, chemical-shift MRI is used to demonstrate the presence of intravoxel fat and water within the tissue and to distinguish normal from abnormal thymus by qualitative comparison and by calculating the chemical-shift ratio between inphase and opposed-phase gradient-echo images (13).…”

Section: Discussionmentioning

confidence: 99%

“…It was recently reported that chemical-shift MRI is useful for characterizing the normal thymus in early adulthood, and for diagnosing thymic hyperplasia by detecting the intravoxel fat and water within the thymus (13). According to the anatomical literature, a microscopic amount of fatty tissue exists within the thymus at birth, and normal fatty replacement of the thymus primarily starts at about 10 years of age, before the thymus undergoes obvious morphologic involution (14,15).…”

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confidence: 99%

Evaluation of normal fatty replacement of the thymus with chemical‐shift MR imaging for identification of the normal thymus

Inaoka

Takahashi

Iwata

et al. 2005

Magnetic Resonance Imaging

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Purpose: To clarify the influences of age and gender on normal fatty replacement of the thymus in childhood, adolescence, and early adulthood using chemical-shift MRI. Materials and Methods:A total of 95 normal subjects (52 males and 43 females, mean age ϭ 15.6 years, range ϭ 7-25 years) who underwent chemical-shift MRI of the thymus were assessed prospectively. Signal intensity loss (SIL) of the thymus was determined by dividing the thymus/ muscle ratio on the opposed-phase image by that on the in-phase image. We evaluated SIL for its correlation with age and gender, and assessed SIL of the thymus with uncommon morphological features.Results: A significant correlation was found between SIL and age (r ϭ 0.750, P Ͻ 0.001). There was no significant difference in SIL between the genders. No significant SIL was identified in any of the subjects aged 10 years or less. However, significant SIL was found in 70.8% of those aged 11-20 years, 100% of those aged 21 years or more, and 46.2% of subjects with uncommon morphological features of the thymus. Conclusion:Chemical-shift MRI can depict physiologic fatty infiltration within the normal thymus in subjects over 11 years of age. It is crucial to correlate these normal agerelated findings with clinical cases in order to avoid misinterpretation.

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