Pituitary adenomas: value of MR imaging

MR imaging has become the imaging modality of choice for diagnosis of pituitary adenomas. In order to optimize MR evaluation, dedicated pulse sequences must be utilized and knowledge of diagnostic pitfalls and normal variants is mandatory. The MRI features of pituitary adenomas may vary based on their volume, but also on their cell-type. Postoperative MR imaging based on a pre-established schedule is useful to detect residual and/or early recurrent tumor.     

Pituitary adenomas and pregnancy: morphological MRI features

The authors present the clinical aspects and changes of the pituitary gland and adenomas in pregnant women by MRI. A number of physiological morphologic changes are seen during pregnancy. Moreover, the hormonal milieu affects patients with adenomas which could evolve leading to severe complications as hypertrophy, necrosis, and hemorrhage. An increase in the volume and T1 hyperintensity of the anterior pituitary, is normally seen. These changes are explained by an increase in lactotrops and prolactin production. Tumoral complications are more frequent with macroadenomas, and are suggestive of a sellar mass or apoplexy. Nevertheless, other differential diagnoses must be suggested in pregnancy and post-partum including hypophysitis and Sheehan syndrome.     

Pituitary adenomas: findings of postoperative MR imaging.

Preoperative and postoperative magnetic resonance (MR) images obtained in 25 patients with pituitary macroadenomas (1.1-5.2 cm in diameter) were evaluated to determine normal (physiologic) and abnormal findings after transsphenoidal or subfrontal surgery. With a 1.5-T unit, T1-weighted sagittal and coronal images were obtained before and after administration of gadopentetate dimeglumine. The physiologic changes after surgery included resorption of packing material and sphenoid sinus opacifications, reexpansion of the pituitary gland, and lowering of the optic chiasm. Implanted gelatin foam appeared as an endosellar, circularly enhancing mass that was seen on follow-up studies to have decreased in size. Muscle-and-fat implants appeared as areas of high signal intensity. In 14 patients, residual tumors were found in the suprasellar (n = 4), retrosellar (n = 3), parasellar (n = 8), and/or endosellar (n = 3) space. Residual tumors were differentiated from implant materials by means of location, characteristic signal intensity, and enhancing pattern, which were identical to those of the corresponding preoperative adenoma in 13 cases (93%). Preoperative studies and clinical information are helpful in the evaluation of postoperative MR imaging examinations.     

Pituitary adenomas: high-resolution MR imaging at 1.5 T

The magnetic resonance (MR) images of 28 patients with surgically confirmed pituitary adenomas were retrospectively evaluated. The examinations were performed on a 1.5-T superconducting MR system using a multisection spin-echo technique with 3-mm-thick sections and a 256 X 256 matrix. T1- and T2-weighted images were obtained in sagittal and coronal planes. The MR findings were correlated with detailed operative reports and diagrams. There were 11 microadenomas and 17 macroadenomas. Ten of the microadenomas and all of the macroadenomas were accurately localized and their extent delineated, particularly on T1-weighted coronal sections. Adenomas typically appeared hypointense on T1-weighted coronal sections. The appearance on T2-weighted images was variable, and generally the lesions were less well seen. Involvement of parasellar structures, particularly the optic chiasm and cavernous sinuses, was accurately depicted. Cyst formation and hemorrhage could be characterized in some instances. In general, there was excellent correlation between MR imaging and operative findings.     

Pituitary adenomas: early postoperative MR imaging after transsphenoidal resection.

BACKGROUND AND PURPOSE: Although there have been several reports on postoperative MR imaging of the sella, immediate postoperative changes (usually within 3 days) have not been extensively analyzed. The purpose of this study was to establish the value of early postoperative MR imaging in differentiating residual tumor from postoperative surgical changes in the sella after transsphenoidal resection of pituitary adenomas. METHODS: Eighty-three patients with surgically proven pituitary adenomas (32 nonfunctioning, 24 prolactin-secreting, 22 growth hormone-secreting, and five prolactin- and growth hormone-secreting tumors) were studied prospectively. All patients underwent dynamic MR imaging within 7 days after surgery. We analyzed the postoperative MR images by focusing on changes in the pituitary gland, signal intensity, resorption of implanted material, and visibility of residual tumor. The patients were divided into four groups according to enhancement pattern of the postoperative pituitary mass: no enhancement, nodular enhancement, peripheral rim enhancement, and a combination of nodular and peripheral rim enhancement. RESULTS: Postoperative changes included resorption of implanted material and reexpansion of the pituitary gland. In 22 patients, residual tumors were found, and all patients showed nodular or combined enhancement. The residual tumors were confirmed by immediate reoperation in three patients, by hormonal assay and follow-up MR images in 11 patients with functioning adenomas, and by growth of the tumor on follow-up MR images in eight patients with nonfunctioning adenomas. Forty-eight patients showed no enhancement and 13 patients showed peripheral rim enhancement. CONCLUSION: Early postoperative dynamic MR imaging after transsphenoidal resection in pituitary adenoma is very effective in differentiating residual tumor from postoperative surgical changes.     

儿童间变性脑膜瘤伴出血一例

患儿女,13岁,无诱因自觉右颞部胀痛3个月,无恶心、呕叶等,症状逐渐加重,神经系统专科检查阴性.头颅CT检查提示右颞叶占位性病变.头颅MRI:病灶位于右侧颞部,T1WI以高信号为主,其内夹杂斑片状等信号影(图1);T2WI呈高低混杂信号,周围可见环形低信号影环绕,其外围环以大片状水肿带(图2);增强后其周围不规则花环状强化,其内可见不规则低信号无强化区,病灶分叶,边界尚清(图3,4).术前诊断为原始神经外胚层肿瘤(PNET).     

垂体瘤诊治进展

垂体瘤是最常见的中枢神经系统肿瘤之一.随着检查手段的进步,垂体瘤发病率逐年攀升.垂体瘤症状与一些常见疾病类似,漏诊现象较为常见,漏诊人群会出现严重并发症,影响其寿命和生活质量.尽早诊断与治疗垂体瘤对患者至关重要.垂体瘤的治疗手段主要包括手术治疗、药物治疗以及放射治疗等.本文对近年来的垂体瘤诊断及治疗进展进行概述,以期提高对垂体瘤的认识.     

Pituitary adenomas in patients with Cushing disease: initial experience with Gd-DTPA-enhanced MR imaging

To assess the role of magnetic resonance imaging in the evaluation of adrenocorticotropic-hormone (ACTH)-producing pituitary adenomas, and the effect of intravenously administered gadolinium-diethylenetriaminepentaacetic acid (DTPA) on lesion/pituitary contrast, imaging was performed in 13 patients with clinical and chemical evidence of Cushing disease. Images were obtained at 0.5 T before and after the injection of Gd-DTPA (0.1 mmol/kg). Lesions were identified in eight of 12 precontrast and ten of 12 postcontrast studies. In these 12 patients adenomas were found at transsphenoidal surgery. The other patient, with normal images, was found to have an ectopic source of ACTH. Coronal images corresponded remarkably well with the neurosurgeon's intraoperative findings. Serial T1-weighted images disclosed early enhancement of the pituitary gland and delayed enhancement of the cystic adenomas. The discrepancy in times to peak enhancement accounted for improved lesion/pituitary contrast in some early images and for reversal or diminution of lesion/pituitary contrast in later images.     

Rapid decrease in amino acid metabolism in prolactin-secreting pituitary adenomas after bromocriptine treatment: a PET study

Four patients with prolactin-secreting pituitary adenomas were examined with positron emission tomography using L-[11C]methionine to monitor the effect of dopamine agonist treatment on the amino acid metabolism in the tumors. Within the first few hours after intramuscular injection of bromocriptine retard (50 mg) the amino acid metabolism decreased by 40%. Two of the patients were reexamined 7 and 9 days later and showed a 70% reduction in the metabolism of the adenomas. This metabolic effect was later accompanied by significant tumor shrinkage in all adenomas. It is suggested that bromocriptine has a general and rapid effect on the protein synthesis of the prolactin-secreting pituitary adenoma cells.     

Multicystic acoustic schwannoma with intratumoral hemorrhage: a report of two cases.

We encountered two multicystic acoustic schwannomas with intratumoral hemorrhage. The radiological appearance in each case was similar to that obtained with CT and MRI. From a histological perspective, in each case we observed hypervascularity with thin-walled, dilated vessels in clusters and hemosiderin depositions around the dilated vessels.     

Pituitary adenomas and normal pituitary tissue: enhancement patterns on gadopentetate-enhanced MR imaging

A dynamic study of magnetic resonance (MR) imaging was used to obtain successive heavily T1-weighted coronal images (spin-echo [SE] 100/15 [repetition time msec/echo time msec]) of normal pituitary glands and pituitary adenoma immediately after patients were given an intravenous bolus injection of gadopentetate dimeglumine. The images were obtained every minute for 5-8 minutes at 1.5 T. Usual T1-weighted images (SE 600/15) were also obtained before and after the dynamic study was performed. The study group consisted of 18 patients, 10 with normal pituitary glands, and eight with pituitary adenoma. Normal pituitary glands showed maximum enhancement on the first or second image following the administration of gadopentetate dimeglumine, followed by gradual signal reduction through the later images, whereas pituitary adenomas reached a peak of enhancement later and showed slower signal reduction than normal pituitaries. The difference of enhancement patterns between the normal pituitary gland and the pituitary adenoma produced prominent image contrast on the first or second image after administration of gadopentetate dimeglumine, which improved the visualization of one microadenoma and four normal pituitary glands that had been displaced by large adenomas. Dynamic MR imaging is a useful diagnostic procedure not only for detection of microadenomas, but also for visualization of pituitary glands that have been displaced by large pituitary adenomas.     

Pituitary hemorrhage as a complication of hantaviral disease.

We report the case of a 27-year-old man with hemorrhagic fever with renal syndrome who demonstrated pituitary hemorrhage followed by atrophic change seen on follow-up MR.     

Visualization of nonfunctioning adrenal adenomas with iodocholesterol: possible relationship to subcellular distribution of tracer

[131I] 19-iodocholesterol (I-131 C) correctly located adrenocortical adenomas in four patients who had no clinical or biochemical evidence of excessive steroid production. Three of the four "nonfunctioning" adenomas showed significant quantities of lipid histologically. To clarify the discordance between uptake and adrenal-steroid excretion, the subcellular location of I-131 C was studied. Normal rats and rats treated with ACTH or aminogluthimide (AG) were injected intravenously with I-131 C or [3H] cholesterol (H-3 C) and killed after three days. The homogenized adrenals were subjected to subcellular fractionation. Treatment with AG increased both the amount and the percentage of both I-131 C and H-3 C contained in the lipid fraction. ACTH treatment decreased H-3 C content but did not change I-131 C content in the lipid layer, suggesting an impairment of I-131 C mobilization from lipid droplets. The data demonstrate that excess steroid production is not necessary for I-131 C uptake and provide an explanation why certain biochemically nonfunctioning adrenocortical adenomas are visualized with I-131 C.     

Recurrent pituitary adenomas after surgical resection: the role of radiation therapy

Postoperative radiation therapy for pituitary adenomas is usually reserved for extensive lesions or those that are incompletely resected. Nineteen patients who received external beam radiation as a salvage procedure after recurrence following surgery alone for pituitary adenomas were studied. At recurrence, nine patients underwent reexcision. All 19 patients underwent external beam irradiation for salvage. Within a median follow-up time of 11.8 years from the time of surgical failure, two patients have died of progressive adenoma, two are alive with disease progression, eight are alive without disease progression, and seven have died of intercurrent disease. The 5-, 10-, 15-, and 20-year overall actuarial (and progression-free) survival rates were 79% (90%), 62% (90%), 44% (80%), and 44% (53%), respectively. Dose of radiation, suprasellar extension at the time of surgical failure, and histologic findings had no bearing on prognosis. One patient developed a radiation-induced brain necrosis that was successfully resected. Radiation therapy can be an effective salvage modality for recurrent pituitary adenomas after surgical failure.     

甲状腺腺瘤囊内出血合并上呼吸道梗阻的紧急外科处理

目的:探讨甲状腺腺瘤囊内自发性出血并上呼吸道梗阻的紧急外科处理方法及疗效。方法:本组13例,均为甲状腺腺瘤合并囊内出血及上呼吸道梗阻。5例瘤体穿刺减压后行甲状腺部分切除术。其余8例采用清醒状态下局部麻醉,颈前部横切口快速切开减压,呼吸道梗阻解除后全麻气管插管,行甲状腺部分切除术。结果:5例瘤体穿刺减压后,呼吸道梗阻迅速缓解。8例颈前部切开减压后,甲状腺肿瘤迅速突出切口外,上呼吸道梗阻解除,全麻气管插管顺利。13例均行甲状腺部分切除术。结论:甲状腺腺瘤囊内自发性大出血合并上呼吸道梗阻可危及患者生命,紧急采用局部穿刺减压或局麻下颈前部切开可迅速缓解上呼吸道梗阻,为进一步外科处理赢得了时间。     

肾上腺腺瘤与转移瘤的CT鉴别诊断

目的探讨ＣＴ对肾上腺腺瘤与转移瘤的鉴别诊断价值。方法１０９例共１３０个肾上腺腺瘤和转移瘤，分别观察肿瘤的大小、边界、内部结构及其与同侧肾上腺的关系，测量肿瘤的平扫和增强后ＣＴ值及增强程度，２０例做了像素矩阵图分析，应用接受器工作特性（ＲＯＣ）曲线对结果进行分析。结果肿瘤平扫ＣＴ值的ＲＯＣ曲线下面积是０．９０±０．０５，明显大于增强后ＣＴ值（０．８１±０．０４）、增强程度（０．７１±０．０８）和肿瘤大小（０．８０±０．０４）的ＲＯＣ曲线下面积；以肿瘤直径≤３．０ｃｍ，密度均匀，平扫ＣＴ值≤２０ＨＵ，增强后ＣＴ值≤３５ＨＵ，增强程度≤２０ＨＵ为标准，诊断腺瘤的敏感性分别是８６％、８５％、８８％、７６％、和７４％，特异性分别是６８％、６９％、９０％、７４％和５９％；肿瘤与肾上腺相连（６８％）、平扫ＣＴ值＜０ＨＵ、ＣＴ像素矩阵图上有轻度负ＣＴ值区域只见于腺瘤，边界模糊或（和）侵犯周围结构、呈不规则厚环状强化是转移瘤的特征。全组总体符合率为９３％。结论综合分析肿瘤的各种ＣＴ征象，ＣＴ能鉴别绝大多数肾上腺腺瘤和转移瘤。