Cystic meningiomas: MR characteristics and surgical correlations.

PURPOSETo describe the MR appearance of cystic meningiomas, and to correlate the MR appearance with the surgical and neuropathologic findings.METHODSEight patients with cysts associated with meningiomas were studied on a 1.5-T MR system. Unenhanced sagittal T1- and axial T2-weighted images were obtained in all patients. Axial and coronal gadopentetate dimeglumine-enhanced T1-weighted spin-echo images were obtained in seven patients. Additional sagittal T1-weighted spin-echo contrast-enhanced images were obtained in four patients.RESULTSThe cystic components were intratumoral and eccentric in two cases, intraparenchymal in one case, and extraparenchymal (trapped cerebrospinal fluid) in five cases. Cyst wall enhancement was present in two of seven cases performed with intravenous gadopentetate dimeglumine. There was no correlation between cyst signal intensity and cyst content. A preoperative diagnosis of cystic meningioma was possible in all eight cases.CONCLUSIONSMR demonstrates the extradural location of the tumor and its cystic component, correlates well with the surgical presentation and the neuropathologic results, and allows the preoperative diagnosis of cystic meningioma based on the MR findings. Division into three types of cysts aids the neurosurgeon, who must decide whether total resection is feasible. To obtain total resection and reduce the risk of recurrence with an intratumoral cyst, the surgeon must ensure that the plane of resection is in fact between the thin enhancing membrane of the tumor cyst and the adjacent arachnoid. In cases in which the cyst is trapped cerebrospinal fluid or intraparenchymal in location, the cyst wall adjacent to or within the brain parenchyma is not included in the resection.     

Pituitary cysts in childhood evaluated by MR imaging

BACKGROUND AND PURPOSE: Pituitary cysts are common findings on pathologic examination and imaging studies. They are generally considered to be rarer in children than in adults; however, no good data exist to substantiate this opinion. We reviewed MR imaging studies to evaluate the frequency and imaging features of pituitary cysts in children. METHODS: We retrospectively reviewed T1-weighted sagittal images in 341 patients <15 years of age to evaluate for pituitary cysts. Paramagnetic contrast was administered in 86 of the 341 patients. Sagittal or coronal fast spin-echo T2-weighted images were performed in 166 patients. For patients having pituitary cysts, pituitary function was examined by assessing blood levels of pituitary hormones. RESULTS: A cystic pituitary lesion was recognized in 4 patients (1.2%) aged 1-4 years. None of the 4 manifested endocrinologic signs or symptoms or were the results of their laboratory studies abnormal. All the lesions were sharply demarcated and situated just posterior to the anterior pituitary lobe. All were iso- or hypointense compared with the pons on T1-weighted images without contrast enhancement, suggesting a Rathke cleft cyst. MR imaging of a patient with probable low-grade gliomas in the left hypothalamic region and optic chiasma showed complete resolution of a pituitary cyst at a 1-year follow-up study. CONCLUSION: The frequency of pituitary cysts on MR imaging in childhood is almost equal to that of Rathke cleft cysts, as assessed in autopsy studies of subjects aged 10 to 29 years. These cysts are common in children and should be considered, in the absence of signs or symptoms of pituitary dysfunction, as incidental findings.     

Rathke囊肿囊内结节的MRI表现及诊断价值

目的：研究Rathke囊肿的囊内结节MRI表现特点及意义。方法：回顾性分析27例经手术病理证实的Rathke囊肿的MRI表现,观察囊内结节的发生率、大小、信号特点及有无强化。其中男11例,女16例,平均年龄33.4岁。所有患者均行MRI平扫及增强扫描。结果：10例Rathke囊肿内出现结节,T1WI表现为高、等或稍低信号,T2WI表现为低信号。结节大小为0.3-1.1 cm,平均0.6 cm。增强扫描囊内结节无强化。结论：鞍区囊性占位内出现囊内结节,显示特征性信号并且无强化,有助于Rathke囊肿的诊断。     

Rathke cleft cyst: MR and biomedical analysis of cyst content

PURPOSE: At least one type of Rathke cleft cyst has unique MR findings, specifically, high intensity on T1-weighted images and iso- to low intensity on T2-weighted images relative to white matter. To clarify the influence of cyst content on MR images, we analyzed the cyst content by biomedical methods after surgical removal. METHOD: We studied five patients diagnosed with Rathke cleft cyst, whose MR images showed high intensity on T1-weighted images and iso- to low intensity on T2-weighted images. After surgery, total protein and cholesterol levels were quantified, and correlations of protein and cholesterol content with T1 and T2 signal intensities were performed in vitro. RESULTS: All five cysts had very high concentrations of protein (11,700-26,600 mg/dl, mean 17,940 mg/dl) with nearly no cholesterol (at most 2.0 mg/dl). Along with increases in protein concentration in vitro, the signal intensity of T1-weighted images increased, while that of T2-weighted images decreased. In contrast, the cholesterol concentration sequence influenced the signal intensity of neither T1- nor T2-weighted images. CONCLUSION: The unique MR finding of Rathke cleft cysts--high signal intensity on T1-weighted images and low signal intensity on T2-weighted images--might depend mainly on protein concentration, not on cholesterol.     

Rathke cleft cysts: CT, MR imaging, and pathologic features

The authors retrospectively reviewed the clinical, computed tomography (CT), and magnetic resonance (MR) imaging findings in seven patients with pathologically proved Rathke cleft cysts. All the cysts were located in the anterior sella turcica or the anterior suprasellar cistern. Five cysts had both intra- and suprasellar components, one was entirely intrasellar, and the other was predominantly suprasellar in location. The size of the cysts ranged from 8 to 20 mm. CT scans demonstrated low-density homogeneous lesions in four cases. On MR images of three of these four cases, the cysts had the same intensity as cerebrospinal fluid on T1- and T2-weighted images, while in the fourth case, the cyst was hyperintense on the T1-weighted images. In the remaining three cases, CT showed slight hyperdensity relative to brain parenchyma, suggestive of contrast enhancement. MR showed signal heterogeneity of these lesions with focal components of diminished signal intensity of T2-weighted images. These same foci appeared iso- to slightly hyperintense on T1-weighted images.     

Thickened pituitary stalk on MR images in patients with diabetes insipidus and Langerhans cell histiocytosis

The MR images of four female patients with acute onset of central diabetes insipidus and pathologically confirmed Langerhans cell histiocytosis were evaluated retrospectively for evidence of lesions in the hypothalamic-pituitary axis. The examinations were conducted on a 1.5-T MR system with thin-section sagittal and coronal T1-weighted (short TR/short TE) and T2-weighted (long TR/long TE) images. Three patients underwent T1-weighted MR after IV administration of gadopentetate dimeglumine. Compared with 20 normal subjects who were evaluated with the same MR protocol, three of the four patients had a symmetrically thickened pituitary stalk that demonstrated homogeneous signal enhancement following contrast administration. The high signal intensity of the posterior lobe, which was seen in normal subjects on T1-weighted sagittal images, was absent in all four patients. Two patients had associated abnormalities on either chest films or imaging studies of the temporal bone and two patients had isolated CNS Langerhans cell histiocytosis. The combination of a thickened pituitary stalk and absent posterior pituitary hyperintensity, while nonspecific for Langerhans cell histiocytosis, should nevertheless prompt further studies, such as chest films, bone scanning, or temporal bone CT, to attempt to narrow the differential diagnosis. Gadopentetate dimeglumine, in particular, may be a useful adjunct in the MR examination of the patient with diabetes insipidus.     

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 adenoma, craniopharyngioma, and Rathke cleft cyst involving both intrasellar and suprasellar regions: differentiation using MRI

AIMS: To determine the differential magnetic resonance imaging (MRI) features of pituitary adenoma, craniopharyngioma, and Rathke cleft cyst involving both intrasellar and suprasellar regions. MATERIALS AND METHODS: The MRI images of 64 patients with pituitary adenoma (n=38), craniopharyngioma (n=13), or Rathke cleft cyst (n=13) were retrospectively reviewed by three neuroradiologists. The following characteristics were evaluated: shape, volume, extent, component characteristics, signal intensities of solid portions on T2-weighted images, signal intensities of cystic portions on T1-weighted images, and enhancement patterns of solid portions and cyst walls of tumours. Fisher's exact test applied with Bonferroni correction was used for multiple comparison. A flowchart for differential diagnosis was constructed based on statistical analysis of the results. RESULTS: A snowman shape, solid characteristics, and homogeneous enhancement of the solid portion were more common in pituitary adenomas (p<0.017). A superiorly lobulated shape, third ventricle compression by superior tumour extension, mixed solid and cystic characteristics, and reticular enhancement of the solid portion were more common in craniopharyngiomas (p<0.017). Finally, an ovoid shape, a small tumour volume, cystic characteristics, and no or thin cyst wall enhancement were more common in Rathke cleft cysts (p<0.017). The flowchart yielded diagnostic accuracies as follows: 92.1% in pituitary adenoma; 92.3% in craniopharyngioma; 92.3% in Rathke cleft cyst; and 92.2% overall. CONCLUSION: A combination of MRI findings is helpful in the differential diagnosis of the three tumours involving both intrasellar and suprasellar regions.     

MR imaging findings of Rathke's cleft cysts: significance of intracystic nodules

BACKGROUND AND PURPOSE: Rathke's cleft cysts often may be difficult to differentiate from other intrasellar or suprasellar masses on radiologic studies. The purpose of this study was to describe the significance of intracystic nodules, a diagnostic characteristic found in Rathke's cleft cysts, on MR images. METHODS: A retrospective review of MR studies was conducted for 13 patients who, after pathologic analysis, were diagnosed as having Rathke's cleft cyst. These patients underwent unenhanced and contrast-enhanced T1- and T2-weighted axial and coronal spin-echo sequential imaging. The signal intensity and incidence of the intracystic nodules on T1- and T2-weighted images were analyzed. The signal intensity of the nodule was compared with that of white matter and surrounding cyst fluid. The signal intensity of cyst fluid was compared with the intraoperative appearance of the cyst fluid. Biochemical and pathologic analyses of the intracystic nodules were conducted in two cases. RESULTS: An intracystic nodule having high signal intensity on T1-weighted images and low signal intensity on T2-weighted images was observed in 10 (77%) of the cases. At surgery, intracystic nodules were yellow, waxy, solid masses. Pathologic analysis showed this nodule to be a mucin clump. Biochemical analysis of the intracystic nodules showed cholesterol and proteins as the main constituents. In the Rathke's cleft cyst with intracystic nodules, cyst fluid revealed low signal intensity to isointensity relative to the intensity of the nodules on T1-weighted images, and isointensity to high signal intensity on T2-weighted images. Intracystic nodules were clearly visible on T2-weighted images. CONCLUSION: Because cyst fluid of Rathke's cleft cysts shows variable intensities on MR images, the specific diagnosis is often difficult when based on MR signal intensity values alone. The presence of an intracystic nodule with characteristic signal intensities on MR images may be indicative of the diagnosis of Rathke's cleft cyst.     

Gadopentetate dimeglumine-enhanced MR of the brain: clinical utility and safety in patients younger than two years of age.

PURPOSETo evaluate the clinical utility and safety of gadopentetate dimeglumine as a contrast agent for MR of the brain in patients younger than 2 years of age.METHODSIn 125 consecutive patients younger than 2 years of age, MR images obtained before and after gadopentetate dimeglumine administration (0.1 mmol/kg) were independently and prospectively evaluated. After interpreting the unenhanced T1- and T2-weighted images, we rated the utility of contrast administration in each patient as not helpful, helpful, or essential for formulation of the radiologic diagnosis. Ratings were categorized both on the basis of the referring clinical diagnoses and on the basis of a radiologic diagnosis that was established from the clinical history and from the findings on the precontrast and postcontrast T1- and T2-weighted images. Patients'' vital signs were recorded, and general medical status was observed for 120 minutes after gadopentetate dimeglumine administration.RESULTSIn no case did gadopentetate dimeglumine permit detection of lesions when precontrast T1- and T2-weighted images were normal. In only 4 of 125 patients were postcontrast images considered essential for establishing the radiologic diagnosis. Abnormal contrast enhancement was radiologically helpful in 20 of 125 patients. Lack of enhancement was considered helpful in 22 of 125 patients. No adverse clinical events or clinically important trends in vital signs were observed after contrast administration.CONCLUSIONThe indiscriminate use of contrast agents in the MR imaging of patients younger than 2 years of age is not warranted. Appropriate decisions regarding the use of gadopentetate dimeglumine can be based on the findings in unenhanced T1- and T2-weighted images and on the referring clinical diagnosis.     

MR appearance of Rathke's cleft cysts

Summary Two of three patients who proved to have symptomatic Rathke's cleft cysts presented with visual field deficit and all with diabetes insipidus. CT showed intra- and suprasellar cystic low density lesions with ring enhancement. MR showed intra-and suprasellar masses. On the T1-weighted images two of the three had hyperintense portions similar to fat and the other a hyperintense portion similar to white matter within the cysts. These portions were isointense to brain on the T2-weighted images in all cases. This characteristic intensity on MR images provides differentiation from cystic pituitary adenomas and cystic craniopharyngiomas, and leads to correct diagnosis of Rathke's cleft cyst.     

Persistent and recurrent hyperparathyroidism: assessment with gadopentetate dimeglumine-enhanced MR imaging

The effect of gadopentetate dimeglumine on signal intensity of abnormal parathyroid glands was assessed in 14 patients with persistent and recurrent hyperparathyroidism. Non-contrast material-enhanced T1- and T2-weighted spin-echo images were compared with T1-weighted images obtained 1 minute and 10 minutes after administration of gadopentetate dimeglumine. Percentage of contrast between the abnormal gland and surrounding tissue was determined with the use of skeletal muscle, subcutaneous fat, and thyroid gland as reference tissues. All 11 abnormal parathyroid glands showed low to intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Gadopentetate dimeglumine significantly increased the signal intensity enhancement ratio of all abnormal parathyroid glands, causing increased percentage of contrast relative to the thyroid gland and skeletal muscle on T1-weighted images. However, the percentage of contrast relative to these tissues was even greater on nonenhanced T2-weighted images. Thus, gadopentetate dimeglumine can substantially enhance the signal intensity of abnormal parathyroid glands and improve differential contrast with some neighboring tissues on T1-weighted images, but it does not improve contrast with surrounding tissue beyond that achieved on T2-weighted images.     

Rheumatoid knee: role of gadopentetate-enhanced MR imaging

Physical examination is often insufficient in distinguishing between joint effusion and inflamed synovium in the knee joints of patients with rheumatoid arthritis. The authors prospectively evaluated the role of intravenously administered gadopentetate dimeglumine in distinguishing between these two conditions. Fourteen patients with classic rheumatoid arthritis were examined first by a rheumatologist and then by means of magnetic resonance (MR) imaging with T1- and T2-weighted sequences. T1-weighted images were also obtained following the intravenous administration of gadopentetate dimeglumine. T1-weighted images obtained prior to contrast material administration demonstrated an identical low-intensity signal from both effusion and inflamed synovium, and T2-weighted images demonstrated increased signal intensity in both cases. Intravenous administration of gadopentetate dimeglumine allowed distinction between effusion and abnormal synovium, with the effusion remaining of low signal intensity and the synovium demonstrating enhancement and increased signal intensity. The authors conclude that the use of gadopentetate allows distinction between synovial thickening and joint effusion in the knee, which may affect treatment decisions.     

Preliminary experience with gadolinium-enhanced dynamic MR imaging for uterine neoplasms.

Usefulness of gadopentetate dimeglumine in magnetic resonance (MR) imaging of uterine neoplasms was evaluated in 53 patients with endometrial carcinoma and 15 patients with cervical carcinoma. T1- and T2-weighted MR images were obtained before the contrast material was administered. After a bolus injection of gadopentetate dimeglumine, dynamic MR images were acquired, followed by static T1-weighted images. Gadolinium-enhanced MR images revealed relatively small endometrial carcinomas in the uterine cavity as high signal intensity in four cases and invasion of the myometrium as low signal intensity in 20 cases. In eight cases, endometrial tumors showed irregular, early enhancement compared with that of the myometrium on dynamic images; these cases were associated with poor prognosis. Tumor extension into the lower part of the uterus, parametrium, and paracervical fat was well seen on enhanced images in cases of cervical carcinoma. The authors believe that gadolinium-enhanced MR imaging will prove helpful in the staging of uterine neoplasms.     

Normal and abnormal pituitary glands: gadopentetate dimeglumine-enhanced MR imaging

Dynamic magnetic resonance (MR) imaging with a 1.5-T superconductive unit was used in the evaluation of nine normal pituitary glands and 10 pituitary adenomas, including four microadenomas and six macroadenomas. Seven to 10 images were obtained every 20-30 seconds with use of the spin-echo technique after rapid injection of gadopentetate dimeglumine. The earliest contrast material enhancement of normal structures was seen in the infundibulum and posterior lobe of the pituitary gland at 20 seconds, followed by gradual contrast material enhancement of the anterior lobe of the pituitary gland from the junction of the infundibulum to the peripheral portion of the anterior lobe of the pituitary gland within 80 seconds after gadopentetate dimeglumine injection. The peak enhancement of pituitary adenomas occurred at 60-200 seconds, usually after the most marked enhancement of the normal pituitary gland. Microadenomas are best visualized at earlier phases of gadopentetate dimeglumine-enhanced dynamic imaging, with signal intensity lower than that seen on images of normal pituitary glands.     

Parotid gland: plain and gadolinium-enhanced MR imaging

The purpose of this study was to show the typical appearance of lesions of the parotid gland with plain MR imaging and MR imaging enhanced with gadopentetate dimeglumine. Seventeen patients with inflammatory changes and 43 with benign and malignant tumors were studied. The examinations were carried out with plain T1-weighted sequences with a repetition time (TR) of 500 msec and an echo time (TE) of 25 msec (TR/TE = 500/25), T2-weighted sequences (1,600/90), and gadolinium-enhanced T1-weighted sequences in axial, coronal, and sagittal orientations. For identifying normal anatomic structures such as the facial nerve and the main duct, the administration of gadopentetate dimeglumine was helpful. In inflammatory changes, gadolinium-enhanced images showed no diagnostic advantages. Gadopentetate dimeglumine proved helpful in delineating tumorous lesions and in differentiating benign and malignant lesions. However, an exact differentiation of the different histologic types was not possible. Post-operative fibrosis could be differentiated from recurrent tumors after administration of gadolinium. If a question regarding infiltration or definition of the boundaries of a lesion cannot be answered with non-enhanced MR imaging, gadopentetate dimeglumine administration is advised. However, for routine imaging of the parotid gland, its use is not recommended.     

Choroidal hemangioma: MR findings and differentiation from uveal melanoma.

BACKGROUND AND PURPOSEThe aim of this study was to establish the MR imaging characteristics of choroidal hemangioma and to compare them with those of uveal melanoma.METHODSAmong 41 patients examined at 1.5 T (4-cm surface coil, T1-weighted and fast spin-echo T2-weighted sequences), 25 had uveal melanoma and 16 had circumscribed choroidal hemangioma. After i.v. bolus injection of gadopentetate dimeglumine, dynamic and T1-weighted sequences were acquired.RESULTSIn patients with choroidal hemangioma, uniform signal characteristics were detected on fast T2-weighted images. In 15 of 16 patients with choroidal hemangioma, lesions were isointense with vitreous on fast spin-echo T2-weighted images, whereas lesions in 24 of 25 patients with uveal melanoma were hypointense. Signal characteristics of uveal melanoma and hemangioma did not differ significantly on plain T1-weighted images. Enhancement was earlier and much stronger for circumscribed choroidal hemangioma than for uveal melanoma. After i.v. bolus application of gadopentetate dimeglumine, the increase of signal intensity was higher for circumscribed choroidal hemangioma (signal intensity ratio, 5.8) than for uveal melanoma (signal intensity ratio, 2.2).CONCLUSIONCircumscribed choroidal hemangioma may be difficult to differentiate from melanoma by ophthalmologic examination. Differentiation may not be possible if direct viewing of uveal space-occupying lesions is hampered by opaque vitreous media. The characteristic findings on fast spin-echo T2-weighted MR images and early enhanced images aid in differentiating choroidal hemangioma from uveal melanoma.     

Optimizing brain MR imaging protocols with gadopentetate dimeglumine: enhancement of intracranial lesions on spin-density- and T2-weighted images

To determine whether long TR MR imaging is best performed before or after IV administration of gadopentetate dimeglumine, we obtained spin-density- and T2-weighted images before and after contrast administration in 21 patients with known intracranial enhancing lesions. Of 25 lesions demonstrating enhancement on T1-weighted sequences, 21 showed mild or moderate enhancement on spin-density-weighted sequences and 20 showed mild enhancement on T2-weighted sequences. Importantly, no spin-density or T2 information was obscured by the administration of gadopentetate dimeglumine, and no T2 shortening effects were visible. Two new foci of enhancement were visible on postcontrast spin-density- and T2-weighted images that were missed on postcontrast T1-weighted images and on precontrast spin-density- and T2-weighted studies. Visualization of new areas of enhancement is the main advantage provided by the long TR images obtained after IV injection of gadopentetate dimeglumine. The most likely reason for the appearance of these newly visualized lesions is thought to be delayed enhancement. This imaging protocol also allows the display of adjacent edema or gliosis and enhancing lesions on a single image. Additionally, in three cases, posterior fossa phase-shift artifacts raised the suspicion of an enhancing lesion on postcontrast T1-weighted images, but the cerebellum was shown to be normal on the postcontrast spin-density- and T2-weighted studies. On the basis of our results, we recommend obtaining long TR images after rather than before the administration of gadopentetate dimeglumine in patients with intracranial enhancing lesions.     

Preoperative evaluation of osteosarcoma: value of gadopentetate dimeglumine-enhanced MR imaging.

Decisions regarding the surgical approach in osteosarcoma require accurate assessment of tumor extent. In order to determine whether enhancement with gadopentetate dimeglumine could add clinically significant information to that available with unenhanced MR imaging, 21 patients with osteosarcoma underwent preoperative MR imaging. T1- and T2-weighted spin-echo MR images obtained before and after administration of IV gadopentetate dimeglumine were evaluated to determine the conspicuity of marrow and soft-tissue extent of tumor, including tumor involvement of major neurovascular bundles and adjacent joints. MR results were correlated with tumor margins found at surgery. In some instances, use of gadopentetate dimeglumine obscured differentiation of tumor from normal marrow or tumor infiltration into perineurovascular fat, and tumor extension through pseudocapsule could not be differentiated from peritumoral edema after contrast administration. Contrast enhancement did assist in differentiation of intraarticular tumor from effusion; however, synovial invasion could be identified on unenhanced T1-weighted images by loss of synovial fat and cortical disruption. These results indicate that gadopentetate dimeglumine does not assist in defining tumor margins of osteosarcoma.     

Normal abdominal enhancement patterns with dynamic gadolinium-enhanced MR imaging

The objective of this study was to quantitatively and qualitatively determine contrast enhancement patterns of normal abdominal organs with dynamic gadolinium-enhanced magnetic resonance (MR) imaging. Dynamic gadolinium-enhanced, T1-weighted, spin-echo imaging was performed during a 23-second breath hold in 38 patients, with images acquired before, during, and at 1,2, and 5 minutes after bolus injection of gadopentetate dimeglumine. Enhancement patterns of normal liver, spleen, pancreas, adrenal gland, kidney, aorta, inferior vena cava, and fat were determined by visual evaluation and by performance of signal intensity measurements with an electronic cursor. Time-intensity curves demonstrated peak enhancement of all abdominal organs during or immediately after bolus injection of gadopentetate dimeglumine. MR enhancement patterns included visualization of renal cortical nephrogram and heterogeneous enhancement of the spleen during the bolus phase of contrast material administration. Peak enhancement of normal liver was 72%; spleen, 172%; pancreas, 82%; adrenal gland, 85%; and kidney, 291%. This study established reference data regarding abdominal organ enhancement that will be useful as dynamic gadolinium-enhanced MR imaging becomes clinically implemented.