Adrenal phaeochromocytoma: correlation of MRI appearances with histology and function

The purpose of this study was to describe the range of appearances of adrenal phaeochromocytomas on T2-weighted MRI, correlate appearances with histopathology, and quantify the incidence of the previously described hyperintense appearance. The appearance and MR characteristics of 44 phaeochromocytomas were reviewed retrospectively. T2-weighted appearances were grouped: (1) ‘classical’, homogeneous, high signal intensity, isointense to CSF; (2) homogeneous, isointense or minimally hyperintense to spleen, hypointense to CSF; (3) heterogeneous, marbled appearance; (4) heterogeneous, multiple high signal intensity pockets. All 44 adrenal phaeochromocytomas were well circumscribed, 1.2–15 cm in maximum diameter, with no visual or quantitative signal loss on chemical shift imaging. On T2-weighted MRI 5/44 (11%) had group 1 appearance; 15/44 (34%) group 2, 7/44 (16%) group 3; and 17/44 (39%) group 4. Homogeneous group 1 and 2 lesions were smaller (mean 4.5 cm) than heterogeneous group 3 and 4 lesions (mean 6.3 cm). Increasing MRI heterogeneity correlated pathologically with increasing amounts of haemorrhage, necrosis and fibrosis. No MRI features were predictive of malignancy. Non-functioning phaeochromocytomas were larger than functioning lesions. No size difference was seen between syndrome and sporadic lesions. In this large series we report a wide range of appearances of adrenal phaeochromocytomas on T2-weighted MRI. The previously described classical hyperintense phaeochromocytoma is relatively uncommon.     

Role of magnetic resonance in the radiologic diagnosis of parotid pathology

MRI findings in 13 patients with monolateral parotid tumor were compared with US, sialographic and CT findings. MRI did not allow an accurate diagnosis in 2 patients with diffuse chronic parotitis. MRI was superior to CT in 1 case in defining the intraglandular site of the lesion, and in 2 patients in showing the extraglandular involvement. MRI proved to be superior to CT thanks to its contrast resolution and to multiplanar imaging. MRI high contrast resolution made it possible to demonstrate neoplastic lesions of 4 mm in diameter. The lesion has low signal intensity on T1-weighted images and high signal intensity on T2-weighted. Parotid tumors cannot be characterized by signal intensity alone: only morphology allows to discriminate between benign and malignant lesions. To conclude, US is a screening method, while MRI is helpful in detecting multifocal lesions and in evaluating the tumor extent.     

Value of various imaging modalities for diagnostic work-up of tumors of the adrenal gland

OBJECTIVE: This paper describes the value of various imaging modalities for diagnostic work-up of tumors of the adrenal gland. METHODS: Results of the literature are reviewed. An optimized examination protocol for computed tomography (CT) and magnetic resonance imaging (MRI) is shown for assessment and differentiation of unclear lesions of the adrenal gland. RESULTS: Measurements of attenuation in the native examination as well as delayed enhancement are the cornerstones in the CT diagnostics of tumors of the adrenal gland. In MRI, chemical-shift imaging and evaluation of signal characteristics in T1- and T2-weighted images are most important for characterization even in unclear cases. CONCLUSION: CT and MRI play the major role in imaging of adrenal gland tumors.Whereas CT is less expensive and widely available,MRI provides advantages in unclear cases because of the excellent tissue contrast and the superior characterization.     

Desmoplastic fibroma of bone: a report of two cases

Desmoplastic fibroma is a rare bone tumor with benign, locally aggressive, lytic behavior. Histologically, it is very similar to the more common and better known desmoid tumor. It can occur at any site in the skeleton but is most common in the mandible or in the long bones. We present two cases; the tumor was located in the proximal tip of the fibula in one case and in the proximal tip of the femur in the other. We describe the appearance of these lesions on CT and MRI. In both cases, the lesions were lytic, expansive, with a trabeculated appearance and internal septa, and without mineralized osseous matrix. At MRI, one of the tumors was very heterogeneous, with two differentiated areas on T2-weighted sequences: the upper zone was hypointense and the lower zone showed intermediate signal intensity. We also describe the behavior of the tumor after the administration of intravenous Gadolinium: the upper zone showed no significant enhancement and the lower showed significant enhancement in the early phase.     

Diagnostic value of MR imaging in comparison to CT in the detection and differential diagnosis of renal masses: ROC analysis

The aim of this work was to compare MR imaging and CT in the detection of renal masses and in the differential diagnosis between benign and malignant lesions. In 33 patients with 54 renal lesions CT and MR images were evaluated by four readers with regard to tumor detection and characterization using a receiver-operating-characteristics (ROC) analysis. The MRI protocol consisted of a T1-weighted spin-echo (SE) sequence (TR/TE: 300/10 ms) before and after contrast administration and a heavily T2-weighted turbo-SE (TSE) sequence (TR/TE: 5500/150 ms). A_z values for the area under the ROC curves for lesion detection were 0.92 ± 0.04 for CT and 0.91 ± 0.05 for MRI, respectively, which was not statistically different. The MRI technique was slightly, but not significantly, better than CT in the overall characterization (accuracy in differentiation between benign and malignant) of renal lesions with an A_z value of 0.90 ± 0.05 compared with 0.88 ± 0.06 for CT. The MRI technique proved to be statistically superior to CT (p < 0.01) in the correct characterization of benign renal lesions. MRI equals CT in the overall detection and differential diagnosis of renal masses. MRI is very helpful for further differential diagnosis of lesions which are equivocal on CT especially in the differentiation between complicated cysts and cystic or hypovascular renal cell carcinoma. Received 29 April 1996; Revision received 14 August 1996; Accepted 2 September 1996     

胚胎发育不良性神经上皮瘤的影像学与临床病理特征

目的探讨胚胎发育不良性神经上皮瘤（DNT）的MRI、CT表现及临床病理特征。方法回顾性分析经组织病理学证实的12例DNT的MRI、CT表现与临床病理特点。结果男6例，女6例，年龄12～68岁（平均36．7岁）。大多数病例以癫痫小发作为主，神经系统检查无阳性体征。MR检查病变均位于幕上结构，累及皮层，额叶（4例）及颞叶（3例）为主；最大径2-5cm不等，形态呈类圆形、分叶状或不规则状；2例累及白质，7例伴囊性变。病变在MRI均呈T1WI低信号，T2WI高信号，无病变周围水肿及占位效应；囊性病变在T1WI信号均匀，等于或略高于脑脊液。6例CT扫描病变均呈低密度改变，其中2例呈囊性分叶状，1例呈局灶性钙化；4例增强后病变无强化，1例病变内呈轻度不均匀强化。病理组织学DNT分为3型：单纯型（4例）、复杂型（6例）及非特异型（2例）。结论DNT是一种良性病变，MRI较CT更具特征性表现。     

CT、MRI在附睾肿块诊断中的应用价值

 目的 探讨附睾肿块的临床特点和CT、MRI表现.方法 回顾性分析42例经手术病理证实的附睾肿块的临床表现和CT、MRI特点.结果 附睾囊肿13例,附睾非特异性炎性肿块11例,结核8例,精子性肉芽肿4例,平滑肌瘤2例,纤维假瘤1例,腺瘤样瘤3例;附睾囊肿及结核的影像表现有一定特征性;MRI对于附睾炎性肿块、平滑肌瘤、纤维假瘤的诊断有较大帮助.结论 附睾肿块大多为良性病变;正确认识附睾肿块的CT、MRI表现,对附睾肿块的早期诊断及治疗有较高的临床价值,少数附睾肿块缺乏影像特征性,依赖病理确诊.     

Deep soft tissue leiomyoma of the thigh

A case of ossified leiomyoma of the deep soft tissues of the left thigh is presented. The radiographic appearance suggested a low-grade chondrosarcoma. MRI of the lesion showed signal characteristics similar to muscle on both T1- and T2-weighted spin echo sequences with linear areas of high signal intensity on T1-weighted images consistent with medullary fat in metaplastic bone. Histopathological examination of the resected specimen revealed a benign ossified soft tissue leiomyoma. Received: 23 December 1998 Revision requested: 31 January 1999 Revision received: 11 March 1999 Accepted: 16 March 1999     

Discriminatory power of MRI for differentiation of adrenal non-adenomas vs adenomas evaluated by means of ROC analysis: Can biopsy be obviated?

The purpose of our study was to evaluate the discriminatory power of MRI in high-field magnet (1.5 T) for differentiation of adrenal non-adenomas vs adenomas assessing the following parameters separately and in combination: mean diameter of adrenal mass; previously described and new ratios as well as index calculated from signal intensity (SI) on SE T2-weighted images, chemical shift imaging (CSI), and Gd-DTPA-enhanced dynamic studies. One hundred eight adrenal masses (36 non-hyperfunctioning adenomas, 27 pheochromocytomas, 23 aldosterone-secreting adenomas, 20 malignant masses and 2 cortisol-secreting adenomas) in 95 patients were evaluated with SE sequences, CSI and Gd-DTPA dynamic studies. Indices and ratios of SI for all examined MRI methods were calculated and examined retrospectively for significance of differences between the groups with calculation of sensitivity and specificity. Receiver operating characteristics (ROC) analysis of calculated parameters in combination was performed. The multifactorial analysis of all four parameters, including size of the tumor, T2_liver index, CSI ratio reflecting lipid content in the tumor and Wo_max/last ratio reflecting maximal washout of contrast agent from the tumor had 100 % sensitivity and 100 % specificity in characterization of adrenal non-adenoma. The best performance of combination of mean tumor diameter with single MRI SI parameter was achieved in combination with T2_liver index for all adrenal masses (area under ROC 0.987) and CSI ratio for non-hyperfunctioning adrenal masses (area under ROC 0.991). Magnetic resonance imaging enables sensitive and specific diagnosis of adrenal non-adenoma. Received: 18 June 1998; Revised: 11 January 1999; Accepted: 5 May 1999     

MRI characteristics of two cases of adrenal ganglioneuromas.

Two cases of the magnetic resonance imaging (MRI) of adrenal ganglioneuromas are presented. The appearance on spin-echo sequences is that of a heterogeneous mass, increasing in signal intensity in T2-weighted images, with associated areas of decreased signal, consistent with findings in the one previously reported case. The diagnosis of adrenal ganglioneuroma should be considered in the differential diagnosis of heterogeneous adrenal masses.     

Magnetic resonance imaging of the prostate

The prostate was examined by magnetic resonance imaging (MRI) in 33 subjects, including five normal volunteers, 18 with prostatic carcinomas, seven with benign nodular hyperplasias, two cases of acute prostatitis, and one case of chronic prostatitis. Of 18 prostatic carcinomas, 16 produced an inhomogeneous signal intensity, with areas of diminished signal on T1-weighted scans and usually increased signal on T2-weighted images relative to the rest of the prostate. However, a similar appearance was also seen in five cases of benign nodular hyperplasia. It is doubtful at present whether MRI is able to reliably differentiate benign from malignant prostatic disease. Extraprostatic tumor extension and pelvic adenopathy was well shown, and MRI is very promising as a method for the preoperative staging of known prostatic carcinomas.     

Slow-growing labyrinthine masses: contribution of MRI to diagnosis, follow-up and treatment

We report the use of MRI in the diagnosis, follow-up and therapeutic management of three cases of intralabyrinthine Schwannoma. The diagnosis was based on the history and initial and follow-up MRI findings. The main feature suggesting the diagnosis was a nodular intralabyrinthine mass of low signal intensity on T2-weighted images, and high or isointense signal on T1-weighted images (relative to cerebrospinal fluid), which showed contrast enhancement. Follow-up imaging showed growth of the tumour in one patient. One patient underwent surgery for severe tinnitus. To detect these lesions, MRI should be focussed on the inner ear, using thin-section T2-weighted and T1-weighted images before and after contrast medium. MRI allowed informed surgical planning. Received: 26 March 1997 Accepted: 27 January 1998     

Normal adrenal gland: in vivo observations, and high-resolution in vitro chemical shift MR imaging-histologic correlation

RATIONALE AND OBJECTIVES: The purpose of this study was to determine whether adrenal cortical lipid affects signal intensity on magnetic resonance (MR) images and to evaluate contrast between cortex and medulla. MATERIALS AND METHODS: From their clinical database, the authors selected 37 MR imaging studies of patients with adrenal adenomas. Two independent readers compared in-phase and fat-suppressed T1-weighted images, looking for visible lipid-induced signal intensity loss in the adrenal gland. Six adrenal gland specimens obtained after radical nephrectomy were also studied with high-resolution MR imaging, including in-phase, opposed-phase, and fat-suppressed T1-weighted images, and T2-weighted images. Adjacent histologic sections were stained with oil red O for neutral fats and with hematoxylin-eosin, and they were also viewed with polarization light microscopy. The relative amount of lipid was graded as mild, moderate, or intense, and the appearance of the cortex and medulla was compared with that on the MR images. RESULTS: On the 37 clinical MR studies, there was no visible signal intensity loss within the limbs of the ipsilateral adrenal glands. T2-weighted images of the adrenal specimens showed a thin high-intensity band, corresponding to the appearance of medulla on histologic slices. This could not be seen on any of the T1-weighted images. Region-of-interest measurements were nearly identical for in-phase and opposed-phase images. Histologic analysis showed abundant cortical lipid. CONCLUSION: Adrenal corticomedullary contrast can be depicted on high-resolution T2-weighted images but not on any T1-weighted images. There is abundant cortical lipid in adrenal specimens, but comparison of in-phase with opposed-phase MR images does not depict it.     

Eosinophilic granuloma: MRI manifestations

The appearance on magnetic resonance imaging (MRI) of 16 cases of pathologically proven eosinophilic granuloma were reviewed retrospectively and correlated with the radiographic appearance of the lesion. The most common MR appearance (ten cases) was a focal lesion, surrounded by an extensive, ill-defined bone marrow and soft tissue reaction with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, considered to represent bone marrow and soft tissue edema (the flare phenomenon). The MRI manifestations of eosinophilic granuloma, especially during the early stages, are nonspecific, and may simulate an aggressive lesion such as osteomyelitis or Ewings sarcoma, or other benign bone tumors such as osteoid osteoma or chrondroblastoma.     

Hepatic MRI with SPIO: detection and characterization of focal liver lesions

A variety of parenterally administered iron oxides have been developed for contrast-enhanced MRI of the liver. Two different classes of iron oxides are currently clinically approved or in phase 3 trials: superparamagnetic iron oxides (SPIO) with a high R2/R1 relaxivity ratio and short blood half-life (AMI-25 and SH U 555 A), and ultrasmall paramagnetic iron oxides (USPIO) with a lower R2/R1 relaxivity ratio and longer blood half-life (AMI-227). All iron oxides significantly increase tumor-to-liver contrast and allow detection of more lesions than unenhanced MRI on T2-weighted images at a field strength of 0.2–1.5 T. Malignant lesions without phagocytic cells exhibit constant signal on T2-weighted accumulation phase images with all three iron oxides. All iron oxides cause a signal decrease of benign lesions with either phagocytic cells or a significant blood pool on T2-weighted accumulation phase images. The signal decrease of benign lesions is proportional to the Kupffer cell activity or tumor vascularity and is useful for lesion characterization. Another enhancement feature for the differentiation of benign from malignant lesions is ring enhancement of malignant lesions (metastases) on T1-weighted enhanced images either during the perfusion phase with SH U 555 A or during the accumulation phase with AMI-227, which is attributed to the blood pool effects of the compounds. Differentiation of lesions and vessels is easier on enhanced images with angiographic effects than on unenhanced images. Iron oxides improve the quality of two-dimensional MR angiography techniques of the portal venous system by decreasing background signal (liver tissue with all iron oxides) and increasing intravascular signal (AMI-227). The use of iron oxides for hepatic MRI provides an alternative to the existing multistep diagnosis with CT, CT portography, MRI and biopsy. Received: 24 September 1997; Revision received: 12 November 1997; Accepted: 14 November 1997     

肾上腺囊性病变的影像学诊断和鉴别

目的 分析肾上腺囊性病变的影像学表现,以提高其诊断准确性. 资料与方法 经手术病理证实的肾上腺囊性病变16例,术前14例经螺旋CT和多排螺旋CT平扫增强扫描.2例经MR检查.然后与手术病理对照,回顾性分析CT和MR表现. 结果 16例病理证实的肾上腺囊性病变中,肾上腺上皮性囊肿8例,陈旧出血形成假囊肿3例,嗜铬细胞瘤囊变3例,原发性肾上腺癌囊变2例.肾上腺上皮性囊肿和肿瘤坏死囊变CT多表现为低密度,出血为等密度或高密度; T1WI为低信号或高信号,T2WI为显著高信号或低信号.囊内壁光整11例,毛糙5例.囊外壁光整13例,不规则3例.囊壁钙化2例.增强扫描显示壁强化11例,不强化5例. 结论 肾上腺囊性病变特征不同,有助于明确诊断.     

MRI of influenza encephalopathy in children: value of diffusion-weighted imaging

PURPOSE: Our purpose was to describe the MR findings of influenza encephalopathy and assess the value of diffusion-weighted imaging for its diagnosis. METHOD: We examined a total of five patients diagnosed as having influenza encephalopathy or encephalitis by MRI, including diffusion-weighted imaging. We analyzed the conventional images and compared them with diffusion-weighted images. RESULTS: Abnormally hyperintense lesions of varying extent and location were noted on T2-weighted and fluid-attenuated inversion recovery images in the cortex and adjacent white matter in every case. They showed no contrast enhancement. Diffusion-weighted imaging demonstrated the lesions as areas of restricted proton diffusion more clearly than conventional imaging. CONCLUSION: Influenza encephalopathy is depicted as areas of T2 elongation having a rather nonspecific distribution. Diffusion-weighted imaging can demonstrate the lesions sensitively and serve as a valuable adjunct to conventional MRI.     

Diagnosis of adrenal adenoma: value of central spot of high-intensity hyperintense rim sign and homogeneous isointensity to liver on gadolinium-enhanced fat-suppressed spin-echo MR images

Eighty-nine patients with 108 adrenal masses, either adenomas (n = 88) or malignant lesions (n = 20), underwent magnetic resonance imaging (MRI) of the abdomen at 0.5 T for the purpose of determining whether adrenal adenomas could be differentiated from malignant lesions on gadolinium-enhanced fat-suppressed T1-weighted spin-echo (SE) images (Gd-E FS T1WI) and on T2-weighted SE images. The imaging protocol included conventional unenhanced SE T1- and T2-weighted sequences and Gd-E FS T1WI. Three observers independently evaluated signal intensity on unenhanced and enhanced images and also the presence of structures of high signal intensity in the outer margin [hyperintense rim sign (HRS)] or in the center [hyperintense central spot (HCS)] of the adrenal masses. Forty-one (46.5%) of 88 adenomas were homogeneously isointense to liver in unenhanced and enhanced T1-weighted sequences and in T2WI. HCS and HRS were observed in 33/88 (37.5%) and 15/88 (17%) adenomas, respectively, on Gd-E FS T1WI; in contrast, these signs were never revealed in any case of malignant lesions. Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy in classifying lesions as suggestive of adenoma were 93%, 90%, 98%, 75%, and 93%, respectively. Visual evaluation of details of tumor structures on Gd-E FS T1WI allows good characterization of adrenal masses. HCS, HRS, and homogeneous isointensity to liver are characteristic signs of adrenal adenomas.     

MRI of intramedullary cavernous haemangiomas

We reviewed 11 cases of intramedullary cavernous haemangiomas (IMCH) studied by MRI, to assess its diagnostic value in these lesions. Follow-up MRI was obtained in five patients 7 days-2 years following the initial study. In one case a postoperative examination was obtained. The diagnosis was pathologically proven in ten cases, and supported in the last by a family and personal history of cavernous haemangiomas. A reticulate appearance with areas of mixed signal intensity in both T1-and T2-weighted images was the most common finding. Homogeneous high, low or intermediate signal intensity was each found in one case, Two small lesions gave low signal. A rim of low signal was less common than in cerebral cavernous haemangiomas. In one case, the brain showed more than 20 lesions with the MRI appearances of cavernous haemangiomas. In two of five patients, serial preoperative MRI showed progressive disappearance of high-signal areas on both T1-and T2-weighted images. To find a haemorrhagic intramedullary lesion on MRI is not rare. Although the appearances are not pathognomonic, an IMCH can be suggested. We suggest that the following characteristics may help: (1) a personal and/or family history of cavernous haemangiomas; (2) typical MRI appearances of mixed acute, subacute and chronic haemorrhage; (3) a tendency for signal intensity to decrease on follow-up; (4) normal spinal angiography; and (5) associated brain lesions.     

肾上腺常见肿瘤的MRI与CT对照研究

目的：将肾上腺常见肿瘤的MRI影像学特征与CT进行比较,结合病理诊断和生化结果评价MRI在肾上腺肿瘤诊断中的价值。方法：对我院于2000年5月-2008年6月收治并经病理证实的36例肾上腺肿瘤进行回顾性分析,所有病例均有详尽的MRI／及CT影像资料。结合病理,分析MR／和CT的影像特点。结果：36例中,CT和MRI发现阳性率分别为94％和100％;肾上腺癌及转移瘤10例,CT及MRI诊断准确率分别为4／10、10／10,其中,肾上腺癌伴腔静脉癌栓6例,CT和MRI诊断准确率分别为33％和100％。结论：CT和MRI在肾上腺肿瘤的诊断和鉴别诊断上有很好的互补性,MRI对良、恶性肿瘤的鉴别诊断价值及对静脉腔瘤栓的显示上优于CT。