膝关节色素沉着绒毛结节性滑膜炎的影像学表现

目的 探讨膝关节色素沉着绒毛结节性滑膜炎(PVNS)的影像学表现特征.方法 结合文献复习回顾性分析5例经手术(或关节镜)及病理证实的膝关节色素沉着绒毛结节性滑膜炎的X线平片、CT及MRI等影像学表现.结果 X线平片仅能显示关节囊的肿胀,关节面下的骨侵蚀或骨缺损及其周围硬化;CT可以显示关节囊突向关节腔的软组织结节.MRI对显示关节滑膜增厚和关节积液尤其敏感,滑膜增厚及软组织结节在T1W1呈等低信号,T2W1等信号1例,低信号或稍高信号4例,4例在增厚的滑膜内见多发散在含铁血黄素沉着的长T1、短T2低信号影,增强后结节明显强化.结论 MRI明显优于X线平片及CT,有助于本病的诊断和鉴别诊断.     

色素沉着绒毛结节性滑膜炎的影像学表现

目的:探讨色素沉着绒毛结节性滑膜炎(PVNS)的影像学表现,以提高对该病的影像学诊断水平及鉴别诊断的能力。方法:回顾性分析11例经病理证实的PVNS影像学资料并进行总结。11例均行X线检查,其中2例同时行关节空气造影检查;CT平扫7例;10例行MRI检查,其中1例加增强扫描。结果:11例均为单关节发病,其中膝关节8例、踝关节2例、髋关节1例。主要影像学表现为:①关节囊肿胀及结节状软组织肿块:11例均显示关节囊肿胀,4例X线平片(36.3%)、5例CT(71.4%)及10例MRI(100%)显示结节状软组织肿块;②软骨下边缘清楚的骨侵蚀伴硬化缘6例:其中X线显示2例、CT显示6例、MRI显示5例;③滑膜增厚10例:4例CT(57.1%)、10例MRI(100%)显示滑膜增厚;其中弥漫性增厚8例,单纯局限性增厚2例;④关节腔积液及关节间隙的改变:关节腔积液9例(81.8%),关节间隙狭窄4例(36.3%);⑤多发结节的MRI信号改变:结节均呈长T1短T2信号者5例;信号混杂者3例;另2例既有长T1长T2信号,也有长T1短T2信号。结论:PVNS的影像学表现具有一定的特征,影像学检查(特别是MRI检查)大多能够做出正确诊断。     

良性色素性外周神经源性肿瘤的影像学表现

目的探讨良性色素性外周神经源性肿瘤(BMPNT)的影像学特征。方法选取经手术病理证实7例色素性外周神经源性肿瘤患者行CT和MRI扫描,分析其特征。结果7例BMPNT均为单发,其中神经鞘瘤6例、神经纤维瘤1例;位于颈部3例,椎管内2例、鼻腔和后纵隔各1例。5例CT平扫表现为边界清楚不均匀软组织密度影,其内3例合并钙化,增强扫描呈轻中度强化。7例肿块在MRI平扫均表现为混杂信号影,其内含有不同范围短T1短T2信号区,其在瘤内呈结节状、斑片状或弥漫性分布,3例瘤内合并囊变坏死呈长T1长T2信号;增强扫描肿块呈轻度至明显不均匀强化。结论外周神经源性肿瘤含有黑色素是一种少见现象,其MRI表现具有一定特征。     

微囊型脑膜瘤的MRI表现及病理对照

目的 探讨微囊型脑膜瘤的MRI表现及病理对照,分析其影像特征.方法 回顾性分析病理证实的微囊型脑膜瘤10例的临床及MRI资料,10例均行MRI平扫,其中增强扫描7例.结果 10例肿瘤发生于大脑半球凸面者4例,大脑镰旁4例,上矢状窦旁2例.9例肿瘤周围水肿显著,1例水肿轻微.9例肿瘤MRI平扫表现为较均匀长T1、长T2信号,其中2例肿瘤与相邻硬脑膜宽基底部可见单个或多个结节状等、稍长T1及等、稍长T2信号.1例肿瘤MRI表现为不均匀长T1、长T2信号,内见环形影,环壁呈长T1、长T2信号,环内呈短T1、短T2信号.增强扫描6例肿瘤呈均匀显著强化,1例肿瘤不均匀强化.结论 微囊型脑膜瘤的MRI表现与病理显著相关.     

结节性硬化症脑部CT和MRI表现(附12例报告)

目的:分析结节性硬化症脑部CT和MRI表现,以提高对本病的认识。方法:回顾性分析12例经临床证买为结节性硬化症患者的CT和MRI脑部影像学表现。结果:TSC脑部主要影像学改变包括:①室管膜下结节(12例),CT 上表现为多发高密度钙化结节,MRI上表现为T1WI高信号、T2WI低信号7例,T1WI和T2WI上均为低信号1例,T1WI 上呈等信号、T2WI上呈低信号4例;②皮层及皮层下结节(9例),其CT表现为高密度钙化灶3例、低密度灶6例,MRI上呈T1WI低信号、T2WI高信号9例;③脑白质异常(6例),CT上表现为多发低密度灶4例,MRI上表现为T1WI低信号、 T2WI高信号6例。5例行MRI增强扫描,示室管膜下结节呈中等强化,皮层及皮层下结节和脑白质异常信号均未见强化。结论:CT和MRI能较好显示结节性硬化脑部改变,CT对显示钙化结节较敏感,MRI对显示皮层及皮层下结节和脑白质改变较敏感。     

原发性肾脏淋巴瘤的MRI特征

目的:探讨原发性肾脏淋巴瘤(PRL)的MRI特征.方法:回顾性分析9例经手术病理证实的PRL的MRI检查资料,均行MRI平扫及增强.结果:9例共16个病灶,位于左肾6例8个,右肾2例2个,1例双肾受累6个病灶.病灶呈结节状或类圆形4例,不规则或地图状4例,新月形1例.瘤体直径0.6～7.8cm.MRI表现:肾内结节/肿块型4例,肾周型2例,肾盂型2例,弥漫浸润型1例,其中7例肾脏保持正常形态,所有病灶均无包膜.均呈等或稍长T1、等或稍长T2信号,T1WI反相位信号均无减低,DWI高信号,6例信号均匀,3例信号不均匀,其内见小片坏死呈长T1长T2信号.增强皮质期病变均呈轻度强化,髓质期8例轻度持续强化,1例明显强化,分泌期均呈低信号.结论:PRL的MRI表现具有较典型的特征,MRI检查是诊断PRL的有效方法.     

侵蚀性葡萄胎的MRI诊断

目的 探讨侵蚀性葡萄胎的MRI表现及其诊断价值.资料与方法 回顾性分析8例经临床手术和病理证实的侵蚀性葡萄胎患者的MRI表现.结果 所有8例患者MRI表现为宫腔增大,肌层不均匀增厚,宫腔和肌层内可见长T1、长T2信号的囊性影和等信号结节影,外肌层和盆腔内可见大量的血管流空信号.5例宫腔和肌层内见斑点状、条片状高信号出血灶.6例双侧附件出现实性或囊性肿块.增强扫描表现为宫腔、肌层及附件病灶呈环形和结节状强化.结论 侵蚀性葡萄胎MRI表现具有特征性,有助于诊断.     

眼眶血管内皮瘤及血管外皮瘤的MRI表现

目的探讨眼眶血管内皮瘤(hemangioendothelioma,HE)及血管外皮瘤(hemangiopericytoma,HPC)的MRI表现,旨在提高其影像学诊断水平。方法回顾性分析10例眼眶HE及HPC的MRI表现,均行MRI平扫及动态增强扫描。结果 10例中8例发生于眶隔后肌锥外间隙,2例发生于眶隔前;9例表现为形态规整的圆形或类圆形,边界清楚,1例可见分叶;平扫8例表现为等T1、长T2信号,7例可见点、条状血管流空信号;动态增强扫描显示肿瘤早期即出现明显强化,9例表现为明显均匀强化,1例强化不均匀,内部可见囊变区。结论眼眶HE及HPC为富血供脉管性肿瘤,具有一定的影像学特征,MRI平扫及动态增强扫描有助于其影像学诊断。     

酷似海绵状血管瘤的眼眶海绵状淋巴管瘤的影像学表现

目的 探讨酷似海绵状血管瘤的眼眶海绵状淋巴管瘤的影像学表现.资料与方法 回顾性分析7例经手术病理证实的眼眶海绵状淋巴管瘤的CT和MRI表现以及MR动态增强扫描的特点.结果 7例均表现为眼眶椭圆形肿块,其中4例累及眼眶后部和眶尖,视神经明显受压移位.7例CT表现均呈等密度,密度均匀.MRI显示7例均呈略长T1长T2信号,信号不均匀,T2WI显示肿块内有散在的条状和小片状低信号.7例MR动态增强扫描都表现为"渐进性强化"征象,其中5例肿块强化范围扩大较快.结论 表现为眼眶内椭圆形肿块的海绵状淋巴管瘤与海绵状血管瘤非常相似,但肿块累及眼眶后部和眶尖及动态增强扫描显示肿瘤强化范围扩大较快高度提示肿瘤为海绵状淋巴管瘤.     

脑瘤样炎性脱髓鞘病的MRI特征

目的:总结脑瘤样炎性脱髓鞘病(tumor-like inflammatory demyelinating diseases,TIDD)的MRI特征。方法:回顾性分析11例经病理或治疗证实的脑TIDD的MRI征象。结果:11例中,9例为单发团块状,2例为多发团块或结节状。病灶位于额叶4个,颞叶2个,顶叶1个,基底节1个,桥臂1个,跨额颞叶4个。MRI平扫均呈长T1、长T2信号。MRI增强扫描:7个呈斑片状或结节样明显强化,4个明显强化、呈"开环征",2个呈片状或线状轻度强化。4个内缘显示扩张血管影,垂直于侧脑室壁。DWI表现:8个呈明显高信号,4个呈稍高或高低混杂信号,1个呈等及稍低信号。结论:脑TIDD具有特征性的MRI表现,MRI对该病的诊断、鉴别诊断有重要价值。     

原发性眼眶静脉曲张的CT和MRI表现

目的探讨原发性眼眶静脉曲张(POV)的CT及MRI表现。方法临床诊断的30例原发性眼眶静脉曲张患者,9例行CT横断位和冠状位扫描,21例行MR扫描,4例行CT和MR检查。结果30例中30只患眼,左眼18例,右眼12例,均为单侧发病。病变部位眼睑3例,眼眶前部1例,眼眶后部(球后)17例,眼睑和眼眶前部5例,眼睑、眼眶前部和眼眶后部2例,眼眶前部和眼眶后部2例。形态17例为不规则块状,4例为卵圆形,9例为不规则条状。CT冠状位,病变均显示为软组织密度,有明显强化;静脉石2例;眶骨受压变薄、眶腔扩大3例。MR扫描,颈部加压后25例均显示病变,11例呈等T1长T2信号,7例呈长T1长T2信号,1例呈等T1等T2信号,6例呈长T1长T2为主的混杂信号,增强的22例中,14例呈明显均匀强化,8例呈不均匀强化。结论CT横断位和冠状位及颈部加压或俯卧位MRI在原发性眼眶静脉曲张的诊断和鉴别诊断方面有重要价值。     

眶壁转移瘤的CT和MRI诊断

目的分析研究眶壁转移瘤的CT和MRI特点,提高诊断准确率.方法回顾性分析23例经手术病理证实的眶壁转移瘤的CT和MRI表现,成人组16例,儿童组7例.所有病例均行CT平扫与MR平扫和增强扫描.结果16例成年患者CT表现均为溶骨性骨质破坏和眼眶不规则肿块,9例骨质破坏区邻近的颅内可见扁平不规则肿块;16例MRI表现为骨质破坏区邻近的眼眶和颅内均可见略长T1、略长T2信号的不规则软组织影,增强后呈明显强化.7例儿童患者CT表现均为溶骨性骨质破坏和眼眶不规则肿块,其中2例可见垂直针状高密度影,3例骨质破坏区邻近的颅内可见扁平不规则软组织肿块;MRI显示7例骨质破坏区邻近的眼眶内和6例颅内可见略长T1、略长T2信号不规则的软组织影,其中1例为双侧,增强后呈明显强化;7例双侧眶骨、4例斜坡和双侧岩尖及1例双侧颞骨鳞部骨髓腔呈略长T1、略长T2信号影,增强后呈明显强化.结论眶壁转移瘤的CT和MRI表现有一些特点,有助于诊断和鉴别诊断.     

肝脏局灶结节性增生MRI表现与病理对照研究

目的:探讨肝脏局灶结节性增生(FNH)的MRI表现,并与病理进行对照研究。方法:回顾性分析16例经手术病理证实的肝脏FNH的MRI表现。结果:16例病变均为单发。平扫13个病灶在T_1WI呈低或稍低信号,T_2WI呈等或稍高信号,3个呈等信号,其中5个病灶中央瘢痕区呈更长T_1更长T_2信号影。动态增强扫描,动脉期13个病变均呈明显强化,门脉期5个病灶呈稍高信号,11个病变呈等或稍低信号,其中2个病变中央更低信号区稍强化;延迟期7个病灶近等信号,9个病灶呈略低信号,而病灶中央更低信号区仅3例呈高信号明显强化。结论:FNH是一种良性病变,有时术前不易确诊,典型的MRI表现结合临床表现能够对肝脏FNH进行定性诊断。     

Nodular fasciitis in the head and neck: CT and MR imaging findings

BACKGROUND AND PURPOSE: The purpose of this study was to describe the CT and MR imaging findings of nodular fasciitis occurring in the head and neck region. METHODS: CT (n = 6) and MR (n = 4) images obtained from 7 patients (3 men and 4 women; mean age, 19.4 years; age range, 1-48 years) with surgically confirmed nodular fasciitis in the head and neck were retrospectively reviewed. All patients presented with a palpable mass in the head and neck that was noticed 1-3 months earlier: 5 in the face, one in the occipital scalp, and the remaining one in the supraclavicular fossa. We investigated the CT and MR imaging characteristics with emphasis on the location, size, internal content, margin, enhancement pattern, and signal intensity of the lesion. RESULTS: All lesions appeared as a discrete mass on imaging, ranging from 1.0 cm to 4.6 cm in diameter (mean, 2.2 cm). Six lesions, all of which appeared benign, were located in the subcutaneous tissue superficial to the deep cervical fascia. The remaining lesion was located deep to the temporalis muscle and showed an aggressive imaging appearance, markedly eroding the bony orbit and skull. Five lesions were solid, and 2 lesions were partly or completely cystic in appearance. Five lesions were well defined, whereas 2 lesions were ill defined. Four of 5 solid lesions showed moderate to marked diffuse enhancement, whereas the remaining lesion demonstrated mild enhancement. Two cystic lesions showed peripheral, nodular, or rim-like enhancement. Compared with muscle, both solid lesions had isointense signal intensity on T1-weighted images and hyperintense signal intensity on T2-weighted images, whereas the signal intensity of the solid portions of the deep-seated, partly cystic lesion was isointense on both T1-weighted and T2-weighted images. CONCLUSION: Although rare, nodular fasciitis occurs as a discrete solid or cystic mass in the head and neck, depending on the predominant stromal components. When one sees a head and neck mass with a superficial location and moderate to marked enhancement on CT and MR imaging, nodular fasciitis should be included in the differential diagnosis, especially in patients with a recently developed, rapidly growing mass and a history of recent trauma.     

Orbit: initial experience with surface coil spin-echo MR imaging at 1.5 T

Fifty-nine cases in which surface coil MR imaging of the orbit was performed were reviewed. MR imaging was performed with spin-echo techniques at 1.5 T with both short repetition time/echo time (TR/TE) and long TR/TE sequences in all cases. In all patients short TR/TE images were obtained with small-diameter surface coils; long TR/TE images were usually obtained with a standard head coil. Surface coil MR appears to be an important adjunct in state-of-the-art orbital imaging. Orbital MR imaging may be most useful, providing information not available on computed tomography (CT), in identifying lesions in the orbital apex, superior orbital fissure, and optic canal; differentiating inflammatory pseudotumor from malignancy in clinically similar patients; characterizing lesions containing hemorrhage or other paramagnetic material; defining the posterior extent of optic pathway gliomas; and detecting abnormal flow in intraorbital vascular structures. CT seems to be superior to MR imaging in the evaluation of small perioptic meningiomas, especially those that are calcified.     

Solitary fibrous tumor of the orbit: CT and MR imaging findings

BACKGROUND AND PURPOSE:Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm originating from mesenchymal fibroblast-like cells. The purpose of this study was to describe the CT and MR imaging features of SFTs in the orbit.MATERIALS AND METHODS:We retrospectively reviewed CT and MR images in 6 patients (2 men and 4 women), aged 18 to 51 years, with SFT proved on histologic examination located in and around the orbit. All patients underwent CT (including dual-phase CT in 3), and MR imaging was obtained in 3. We evaluated the imaging findings with emphasis on the location, size, margin, internal architecture, and pattern of enhancement of the lesion.RESULTS:All 6 lesions were found as a solitary, well-defined mass, ranging in size from 18 to 30 mm (mean, 24 mm). Three were located in the postseptal orbit, 2 in the lacrimal sac, and 1 on the lower eyelid. Compared with the cerebral cortex, all 3 lesions examined by MR imaging showed homogeneous isointense signal intensity on T1-weighted images and heterogeneous mixed isointense and hyperintense signal intensity on T2-weighted images. On visual inspection, all 6 lesions showed marked homogeneous (n = 4) or heterogeneous (n = 2) enhancement on postcontrast CT and MR images. In 3 patients examined with dual-phase CT, all lesions demonstrated rapid enhancement with early washout of contrast material.CONCLUSION:SFT might be included in the differential diagnosis of soft tissue masses in the orbit, if one sees a markedly enhancing mass showing the similar characteristics to those of the internal carotid artery on postcontrast CT or MR images.

Since the first report by Klemperer and Rabin¹ in 1931 as a primary spindle-cell tumor of the pleura, solitary fibrous tumor (SFT) has been recognized as a distinctive, though rare, pathologic entity that most commonly arises from the pleura and peritoneum. Although once thought to be mesothelial in origin, SFT is now considered a tumor of mesenchymal fibroblast-like cell origin, and there has been an increasing incidence of the tumor to be found in the extrapleural, extraserosal sites such as the lung, liver, breast, and meninges. It can also arise in the extracranial head and neck region such as the orbit, sinonasal cavity, salivary gland, thyroid gland, upper respiratory tract, and deep cervical spaces.^2–7Since the first report of 2 cases of orbital SFT in 1994,⁸ the orbit has become one of the common sites of the head and neck involved by the tumor, and more than 50 cases of orbital SFT have been reported mostly in the ophthalmologic and pathologic literature.^9–21 To our knowledge, however, systematic analysis of the imaging features of orbital SFT has seldom been reported in the radiologic literature. The purpose of this study was to describe the characteristic CT and MR imaging findings of 6 cases of patients with SFT of the orbit proved on pathologic examination.     

MR鼻泪管成像的临床应用

目的 探讨MR鼻泪管成像技术和诊断价值.方法 对8名健康志愿者(16侧正常泪道)和17例泪溢患者(32侧泪溢泪道)进行MR检查,检查前向双侧结膜囊滴入无菌盐水,扫描序列为MR三维快速反转自旋回波泪道成像(3D-FRFSE MRD)序列,泪溢患者还加做了横断面及冠状面快速回复快速自旋回波T2WI序列.在MRI后3 d内对泪溢患者进行泪道内镜检查,并将MRD结果与内镜所见对照分析.结果 16侧正常泪道中有8侧泪囊及鼻泪管全程显影.32侧有泪溢症状的泪道经内镜证实为鼻泪管慢性炎症改变,黏膜增厚呈灰红色,阻塞处为灰白色无弹性的膜状物附着.泪溢组3D-FRFSE MRD序列判断的阻塞部位与内镜的符合率为78%(25/32),表现为阻塞部位以上的泪道呈含水的高信号,其以下的泪道不显影.泪溢侧的鼻泪管在FRFSE T2wI序列上均有阳性改变,阻塞部位以上的泪囊和(或)鼻泪管腔内可见长T2液体信号充填,其以下的管腔内可见等或稍长T2的软组织信号影充填,管壁黏膜增厚.结论 鼻泪管滴注无菌盐水后MRI可以显示正常鼻泪管,而且具有对鼻泪管阻塞定位、定性的诊断价值.     

Atypical focal nodular hyperplasia of the liver: imaging features of nonspecific and liver-specific MR contrast agents

OBJECTIVE: The objective of our study was to describe the functional and differential uptake features of atypical focal nodular hyperplasia using different MR contrast agents and to evaluate their potential role in the diagnosis and characterization of focal nodular hyperplasia. MATERIALS AND METHODS: Contrast-enhanced MR images of 45 patients with 85 focal nodular hyperplasia lesions were retrospectively reviewed. In these patients, sonographic findings were nonspecific (n = 37), or CT features were inconclusive (n = 8). Non-liver specific gadolinium chelates were used in 18 patients (48 lesions) suspected of having either focal nodular hyperplasia or hemangioma. The following liver-specific agents were used in patients with suspected focal nodular hyperplasia or metastases: mangafodipir trisodium, 30 patients (55 lesions); ferumoxides, six patients (16 lesions); and SHU 555 A, six patients (six lesions). Individual lesions were quantified by signal intensity and assessed qualitatively by homogeneity, contrast enhancement, and presence of a central scar. RESULTS: At unenhanced MR imaging, the triad of homogeneity, isointensity, and central scar was found in 22% of the focal nodular hyperplasia lesions. On mangafodipir trisodium-enhanced T1-weighted images, all focal nodular hyperplasia lesions showed contrast uptake: in 64% of the lesions, uptake was equal to parenchyma; 25%, greater than the parenchyma; and 11%, less than the parenchyma. On iron oxide-enhanced T2-weighted images, all focal nodular hyperplasia lesions showed uptake of the contrast agent, but contrast uptake in the lesions was less than in the surrounding parenchyma. Dynamic gadolinium chelate-enhanced MR imaging showed early and vigorous enhancement of focal nodular hyperplasia lesions with rapid washout in 88%. Atypical imaging features of the lesions included hyperintensity on T1-weighted images, necrosis and hemorrhage, and inhomogeneous or only minimal contrast uptake. CONCLUSION: For patients in whom the diagnosis of focal nodular hyperplasia cannot be established on unenhanced or gadolinium-enhanced MR imaging, homogeneous uptake of liver-specific contrast agent with better delineation of central scar may help to make a confident diagnosis of focal nodular hyperplasia.     

Surface-coil MR imaging of orbital neoplasms

Fifteen patients with orbital neoplasms demonstrated by CT were studied with magnetic resonance (MR) using a 13 cm surface coil and a 0.6 T superconducting magnet. The use of a surface coil allowed for a reduction in slice thickness and a significant improvement in spatial resolution resulting in better demonstration and improved characterization of orbital lesions. All neoplasms (15/15) were demonstrated by MR. The lesions were grouped into four main categories on the basis of signal intensities on T1- and T2-weighted images. CT was superior to MR in displaying densely calcified or bony lesions (two of 15 cases). MR was at least equal or superior to CT in demonstrating the other lesions (13 of 15 cases) and had the added advantage of improved tissue characterization in some cases. With the use of surface coils, MR could become the primary imaging technique for evaluation of orbital neoplasms.     

MR Imaging of Orbital Inflammatory Pseudotumors with Extraorbital Extension

Objective

To demonstrate a variety of MR imaging findings of orbital inflammatory pseudotumors with extraorbital extension.

Materials and Methods

We retrospectively reviewed the MR features of five patients, who were diagnosed clinically and radiologically as having an orbital inflammatory pseudotumor with extraorbital extension.

Results

The types of orbital pseudotumors were a mass in the orbital apex (n = 3), diffuse form (n = 2), and myositis (n = 1). The extraorbital extension of the orbital pseudotumor passed through the superior orbital fissure in all cases, through the inferior orbital fissure in two cases, and through the optic canal in one case. The orbital lesions extended into the following areas: the cavernous sinus (n = 4), the middle cranial fossa (n = 4), Meckel''s cave (n = 2), the petrous apex (n = 2), the clivus (n = 2), the pterygopalatine fossa and infratemporal fossa (n = 2), the foramen rotundum (n = 1), the paranasal sinus (n = 1), and the infraorbital foramen (n = 1). On MR imaging, the lesions appeared as an isosignal intensity with gray matter on the T1-weighted images, as a low signal intensity on the T2-weighted images and showed a marked enhancement on the post-gadolinium-diethylene triamine pentaacetic acid (post-Gd-DTPA) T1-sequences. The symptoms of all of the patients improved when they were given high doses of steroids. Three of the five patients experienced a recurrence.

Conclusion

MR imaging is useful for demonstrating the presence of a variety of extraorbital extensions of orbital inflammatory pseudotumors.