Adrenal masses: evaluation with fast gradient-echo MR imaging and Gd- DTPA-enhanced dynamic studies

Fast gradient-echo magnetic resonance (MR) imaging of 38 adrenal masses with proved diagnosis was performed during suspended respiration with various repetition times (TRs), echo times (TEs), and flip angles. Dynamic perfusion studies after gadolinium diethylenetriamine-pentaacetic acid (DTPA) administration were performed by repeated imaging at short time intervals. With more T2 weighting (TR = 60 msec, TE = 30 msec, and flip angle = 15 degrees), malignant tumors and pheochromocytomas had a significantly higher relative signal intensity than adenomas; overlap of signal intensity led to equivocal findings in nine cases. After administration of Gd-DTPA, adenomas showed only mild enhancement and quick washout; malignant tumors and pheochromocytomas showed strong enhancement and slower washout. Five of the nine cases that were equivocal in precontrast images could thus be correctly classified. In addition to this improved classification of adrenal masses, fast, dynamic contrast material-enhanced MR imaging resulted in a reduction in total examination time.     

Cardiac tumors: assessment with Gd-DTPA enhanced MR imaging

Previous studies have shown the value of MR imaging for the identification of cardiac masses. The distinction of intramural tumors from normal myocardium may be equivocal because of the similarity of signal intensity between tumor and normal myocardium on ECG-gated SE images. The purpose of this study was to assess the role of Gd-DTPA for improving the contrast between cardiac tumors and myocardium. Four patients with established or suspected cardiac tumors were imaged with a 1.5 T imager. The T1-weighted images (TR = RR interval, TE = 20-30 ms) were obtained before and immediately after the intravenous injection of Gd-DTPA, at a dosage of 0.1 mmol/kg. Tumors were identified in three patients. All tumors were isointense to the myocardium in precontrast images but demonstrated differential enhancement relative to myocardium after the administration of Gd-DTPA. Two tumors were hyperintense relative to myocardium, and the third was mostly hypointense, surrounded by a hyperintense rim. In the remaining case, no tumor was found and the myocardium was homogeneously enhanced on postgadolinium images. Gadolinium DTPA can produce differential enhancement of tumor from normal myocardium and therefore demonstrate intramural masses.     

Dynamic sequential MR imaging of focal liver lesions: initial experience in 22 patients at 1.5 T

The feasibility of dynamic sequential magnetic resonance (MR) imaging of focal hepatic lesions using Gd-diethylenetriamine pentaacetic acid (DTPA) was evaluated in this study. Three patients with hepatocellular carcinoma, 12 patients with metastases, and 7 patients with hemangiomas were studied with pre- and postcontrast multislice spin echo (SE) images using a repetition time of 500 ms and an echo time of 15 ms. The dynamic distribution phase of Gd-DTPA (0.1 mmol/kg) was investigated by using a sequential, transverse partial flip imaging sequence [fast low angle shot (FLASH)] before and after intravenous administration of Gd-DTPA. The lesion-liver contrast-to-noise ratio showed a great variability in patients with metastases and was significantly improved following administration of Gd-DTPA in patients with hemangiomas, two patients with hepatocellular carcinoma, and eight patients with metastases both on FLASH and SE images. Hemangiomas appeared darker than liver parenchyma on precontrast SE and FLASH images, increasingly enhanced over 5 min postinjection (pi) on FLASH images, and were still greatly enhanced at 10 min pi on SE images. During the dynamic sequential image acquisition the contrast enhancement of hemangiomas was significantly different from the enhancement observed in malignant lesions. The results of this study indicate the clinical potential of dynamic sequential imaging for the MR assessment of focal hepatic lesions.     

Lumbar spine: postoperative MR imaging with Gd-DTPA

Thirty patients with failed back surgery syndrome were studied to evaluate the effectiveness of magnetic resonance (MR) imaging with gadolinium-diethylenetriaminepentaacetic acid/dimeglumine (Gd-DTPA) in differentiating postoperative epidural fibrosis (scar) from recurrent disk herniation. Pre- and postcontrast MR images were interpreted without access to other diagnostic, surgical, or pathologic findings. Seventeen patients had surgical and pathologic correlation of the MR findings at 19 disk levels. The precontrast studies had a sensitivity, specificity, and accuracy of 100%, 71%, and 89%, respectively. The enhanced MR studies correctly depicted the character of abnormal epidural soft tissue in 17 patients at all 19 levels. Scar showed heterogeneous enhancement on the early T1-weighted spin-echo images obtained within 10 minutes after contrast material administration. Herniated disk did not show significant enhancement on the early studies but showed variable degrees of enhancement on delayed images in nine of 12 cases. Other criteria were found to be less useful than the pattern of enhancement. Results indicate that precontrast and early postcontrast T1-weighted spin-echo studies are highly accurate in separating epidural fibrosis from herniated disk.     

Is Gd-DTPA required for routine cranial MR imaging?

Gadopentetate dimeglumine (gadolinium diethylenetriaminepentaacetic acid [DTPA]) was administered prospectively to 500 consecutive children and adults referred for routine cranial magnetic resonance (MR) imaging over a 4-month period. Pre- and postcontrast images were blindly and independently interpreted by two experienced neuroradiologists. Specific criteria were provided to the readers to define objectively when contrast material enhancement (or lack thereof) would be considered "radiologically helpful." Contrast-enhancing lesions were observed in 99 cases (20%). In only 15 cases (3%) did Gd-DTPA permit detection of lesions not also apparent on the precontrast studies. Contrast enhancement was considered radiologically helpful in 74 of the 99 cases. Lack of enhancement was considered helpful in 112 of the 500 cases (22%). Factors that may indicate increased usefulness of Gd-DTPA include increased patient age, definite lesion seen at computed tomography or precontrast MR imaging, prior craniotomy for tumor, and clinically documented systemic or central nervous system disease. Gd-DTPA should probably be used routinely for cranial MR imaging in most patients, except, perhaps, children and young adults with normal precontrast images.     

The dynamic magnetic resonance study of focal liver lesions by FLASH sequences with bolus intravenous gadolinium-DTPA]

Thirty-five patients with hepatic hemangioma (n = 12), metastasis (n = 10), hepatocellular carcinoma (HCC) (n = 10) and focal nodular hyperplasia (n = 3) were examined with the fast low-angle shot (FLASH) technique and an intravenous bolus injection of Gd-DTPA. In order to differentiate the lesions, the following criteria were used: a) pre Gd-DTPA intensity of lesions; b) post Gd-DTPA patterns of contrast enhancement. On the basis of these criteria, an unquestionable differential diagnosis could be made. Hemangiomas were characterized by an hypointense mass before Gd-DTPA, by peripheral contrast enhancement and by subsequent continuous hyperintense fill-in; thus, hemangiomas were visualized as hyperintense lesion during the late phase. Before contrast administration hypovascular metastases appeared as hypointense; they were characterized by delayed uptake of contrast agent. HCCs were hyperintense lesions before contrast administrations; then, quick contrast enhancement and rapid decrease in signal intensity were observed with visualization of a hyperintense ring due to the capsule. Finally, focal nodular hyperplasia appeared isointense or hypointense relative to normal liver on precontrast scans; the lesions were enhanced transiently with subsequent quick dismission of contrast agent. This initial experience suggests dynamic contrast-enhanced MR imaging as an effective method to improve the differential diagnosis among hepatic tumors when precontrast T2-weighted images are equivocal.     

Incidentally discovered adrenal masses: evaluation with Gadolinium enhancement and fat-suppressed MR imaging at 0.5 T

The purpose of the study is to evaluate the ability of Gd-enhancement and fat-suppressed MR imaging operating at midfield strength to characterize incidentally discovered adrenal masses. Sixty patients with 72 adrenal masses incidentally discovered during US or CT exams were studied with a 0.51 MR unit following clinical and laboratory evaluation. After Gd-DTPA intravenous administration a modified three-point Dixon technique was performed in all patients. This technique provided three images sets: conventional T1-weighted SE images, fat-suppressed T1-weighted images and water-suppressed T1-weighted images. Diagnosis was established by means of surgery (11 lesions), fineneedle biopsy (21 lesions) and stability on ultrasonographic follow-up for at least 1 year (range, 12–87 months) from adrenal lesion discovery (40 masses). In most of adenomas (n = 55) an homogeneous enhancement was observed on postcontrast T1WI; however, 15 out of these lesions showed a small focal spot of high intensity in Gd-enhanced fat-suppressed images. On the contrary, malignant conditions (n = 6) and pheochromocytoma (n = 1), all had inhomogeneous signal intensities which were relatively higher after Gadolinium injection as compared with the liver. The fat suppression technique demonstrated areas of bright signal intensity related to high vascularity. The performance of three observers in order to differentiate malignant from benign conditions showed sensitivity, specificity, diagnostic accuracy, positive and negative predictive values of 100, 88.5, 90, 50 and 100% on the basis of gadolinium enhancement only, by utilizing the Dixon technique. In conclusion, although Gd-enhancement and fat-suppressed sequence helped correctly differentiate among the groups of incidentally discovered adrenal masses, the degree of overlap suggests that it is still difficult to characterize individual patients. However, the modified three-point Dixon technique after contrast material administration appears to be a further capability of midfield MRI in the characterization of adrenal tissue.     

Intradural spinal metastases in pediatric patients with primary intracranial neoplasms: Gd-DTPA enhanced MR vs CT myelography

Recently, the application of intravenous gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) has been shown to improve the detection of intradural extramedullary spinal disease in adults. The ability of Gd-DTPA enhanced magnetic resonance (MR) to detect intradural extramedullary spinal metastases was studied in pediatric brain tumor patients. Spinal MR images before and after intravenous injection of Gd-DTPA were analyzed retrospectively in eight pediatric patients with known intracranial neoplasms and clinically suspected subarachnoid tumor seedings. Contrast enhanced spinal MR was compared with CT myelography in four of these patients. In our pediatric population Gd-DTPA enhanced images revealed tumor seeding not appreciable on noncontrast images. Although CT myelography has been the accepted standard investigation in the evaluation of suspected spinal metastases in children, we found that contrast enhanced MR is equal or superior in sensitivity to CT myelography. Spinal MR also provided information not obtainable via CT myelography. In the future, Gd-DTPA enhanced spinal MR should be considered in the initial evaluation of suspected subarachnoid spinal metastases in pediatric patients with known primary brain tumors.     

Comparison of delayed enhanced CT and chemical shift MR for evaluating hyperattenuating incidental adrenal masses

PURPOSE: To retrospectively compare the accuracy of delayed enhanced computed tomography (CT) and chemical shift magnetic resonance (MR) imaging for characterizing hyperattenuating adrenal masses at CT, with either follow-up imaging or pathologic review as the reference standard. MATERIALS AND METHODS: The institutional review board approved this retrospective study with a waiver of patient informed consent. Forty-three hyperattenuating adrenal masses (>10 HU) on unenhanced CT images were found in 34 patients (23 men and 11 women; mean age, 52.7 years) by reviewing radiologic reports. These lesions were retrospectively analyzed with delayed enhanced CT and chemical shift MR. The diagnostic accuracy of CT by using absolute percentage loss of enhancement (PLE) and relative PLE and of chemical shift MR by using adrenal-to-spleen ratio (ASR) or signal intensity index (SII) were obtained to determine which modality was more accurate for lipid-poor adenoma. For CT, an adenoma was diagnosed if a mass had an absolute PLE greater than 60% and a relative PLE greater than 40%. For MR, an adenoma was diagnosed if a mass had an ASR of 0.71 or an SII greater than 16.5%. McNemar test was used to compare diagnostic performance of CT and MR. RESULTS: Hyperattenuating adrenal masses included 37 adenomas and six nonadenomas. The sensitivity, specificity, and accuracy for adenoma at CT were 97% (36 of 37), 100% (six of six), and 98% (42 of 43), respectively, and at MR were 86% (32 of 37), 50% (three of six), and 49% (21 of 43), respectively. CT helped confirm five more adenomas and three more metastatic tumors than did MR. However, there was no significant difference for diagnostic accuracy between these two imaging modalities (P>.05) CONCLUSION: Delayed enhanced CT can characterize additional hyperattenuating adrenal masses that cannot be characterized with chemical shift MR.     

Characterization of musculoskeletal masses using dynamic Gd-DTPA enhanced spin-echo MRI.

Early studies evaluating the utility of Gd-diethylenetriamine pentaacetic acid (DTPA) enhanced MR imaging for characterization of musculoskeletal masses have demonstrated inconsistent and often conflicting results. In this study a new method, dynamic Gd-DTPA enhanced rapid acquisition spin echo MR imaging, was implemented in the evaluation of 18 musculoskeletal lesions and the enhancement features of these lesions were analyzed. Lesions were evaluated before, during, and sequentially following bolus Gd-DTPA injection. Analysis of intensity, volume, timing of onset, progression, uniformity, and pattern of enhancement did not demonstrate significant differences between benign (n = 8) and malignant (n = 10) masses. Significant variations in enhancement were noted in different regions within these masses, which limits the utility of previous dynamic contrast enhanced methods that provide only a single imaging slice for analysis, and are therefore subject to sampling error. This pilot study indicates no advantage for using dynamic Gd-DTPA enhanced imaging for qualitative lesion characterization.     

Characterization of adrenal masses using MR imaging with histopathologic correlation.

OBJECTIVE: The purpose of this study was to evaluate the sensitivity, specificity, and accuracy of MR imaging in the characterization of adrenal masses by correlating imaging findings with histopathologic results. In addition, adrenal tumors that were of an indeterminate nature on MR imaging were analyzed. SUBJECTS AND METHODS: For 114 patients with 134 adrenal masses, MR findings were compared with histologic results. In all patients, MR imaging was performed using T2-weighted fast spin-echo imaging and unenhanced and gadolinium-enhanced T1-weighted spin-echo imaging. Chemical-shift imaging was performed in 92 patients and dynamic gadolinium-enhanced studies in 108 patients. Chemical-shift images were analyzed quantitatively and qualitatively, and dynamic gadolinium-enhanced studies were qualitatively assessed. RESULTS: The sensitivity of MR imaging in differentiating between benign and malignant adrenal masses was 91%, the specificity was 94%, and the accuracy was 93%. The diagnosis at MR imaging differed from that at histology in 12 (9%) of 134 patients. Results of quantitative analyses of chemical-shift imaging techniques showed significant differences between adenomas and nonadenomas (-36.0% versus -3.7%; p < .001). Qualitative analysis provided a similar diagnostic confidence compared with quantitative analysis. Both chemical-shift and dynamic gadolinium-enhanced studies proved to be unreliable in characterizing borderline tumors (epithelial tumors with high malignant potential). Moreover, such imaging failed to allow correct diagnosis of adenomas in two patients. CONCLUSION: The characterization of an adrenal mass can be made with high sensitivity and specificity using MR imaging. The increased reliance on MR imaging seems to be based mainly on findings from chemical-shift and dynamic gadolinium-enhanced studies. The need to perform histologic sampling of incidentally discovered adrenal masses may be reduced to some problematic lesions, which will remain during the era of MR imaging.     

Gd-DTPA administered MR imaging of intracranial mass lesions: a comparison with CT and precontrast MR

Magnetic resonance (MR) images of 13 intracranial mass lesions taken with the intravenous administration of gadolinium-DTPA were evaluated in comparison with precontrast computed tomography (CT), postcontrast CT, and precontrast MR. In the MR images taken with Gd-DTPA, tumor delineation improved in eight of 13 cases (62%) in comparison with precontrast MR images, and in seven of 13 cases (54%) in comparison with the overall evaluation of precontrast CT, postcontrast CT, and precontrast MR images. Tumor demarcation was unchanged in the remaining cases; no deterioration was observed with Gd-DTPA administration. MR imaging with Gd-DTPA should be performed to better evaluate the extent of intracranial mass lesions and to provide additional information.     

Comparative evaluation of computerized tomography/magnetic resonance (1.5 T) in the detection of brain metastasis]

Forty-four patients with small cell carcinoma of the bronchus underwent CT and MR studies of the brain to detect cerebral metastases. All patients were studied with contrast-enhanced CT scans, short (T1-weighted) and long (T2-weighted), spin-echo (SE) and FLASH 90 degrees MR sequences. Gd-DTPA enhanced SE-T1 and FLASH 90 degrees sequences were also obtained. A quantitative comparison of the results was carried out to assess the sensitivity of the different techniques in the detection of brain metastases according to lesion diameter. Metastases were identified in 19/44 patients (43%). All techniques detected the lesions greater than 2 cm; of the metastases less than 2 cm, 63/124 (51%) were detected only by Gd-DTPA SE-T1 and FLASH sequences and 11 more (9%) only by Gd-DTPA SE-T1 scans. All the lesions identified on enhanced CT scans or on T2-weighted images were easily detected by Gd-DTPA scans. CT sensitivity was higher than that of pre-contrast SE-T1 and FLASH studies and only slightly lower than that of T2-weighted images. As for lesions less than 2 cm, Gd-DTPA T1-weighted sequences had the highest detection rate (124 lesions) versus Gd-DTPA FLASH 90 degrees scans (113 lesions) and precontrast T1-weighted scans (45 lesions). When comparing Gd-DTPA SE-T1 and FLASH 90 degrees sequences in the detection of lesions less than 1 cm, we observed that the latter missed 9% of metastases, mainly due to a high rate of magnetic susceptibility artifacts and to lower contrast resolution. Therefore, Gd-DTPA SE-T1 images still remain the most accurate technique in the assessment of cerebral metastases.     

Evaluation of adrenal masses with gadolinium enhancement and fat-suppressed MR imaging

A study was undertaken to determine the ability to characterize benign and malignant masses with unenhanced and contrast material-enhanced fast lowangle shot and fat-suppressed spin-echo magnetic resonance (MR) imaging. Thirty patients with adrenal masses detected at computed tomography (CT) underwent MR imaging within 14 days after CT. CT and MR images were interpreted in a prospective, blinded fashion. Sixteen patients had 20 benign adrenal masses, and 14 patients had 18 malignant masses. Quantitative measurements included percentage of contrast enhancement on immediate postcontrast dynamic images and periphery - center signal-to-noise ratio (S/N) on gadolinium-enhanced fat-suppressed images. Qualitative evaluation included determination of the regularity of lesion margins, homogeneity of signal intensity, and local extension. MR imaging depicted all adrenal masses discovered at CT examinations. Lesions ranged in diameter from 1 to 15 (mean, 4.4) cm. No significant difference was observed in percentage of contrast enhancement between benign (90.5% ± 59.0 [standard deviation]) and malignant (110.5% ± 116.4) masses. A difference was observed between periphery - center S/N for benign (?.05 ± 1.5) and malignant (7.7 ± 9.8) masses; overlap between the two, however, occurred. Qualitative evaluation allowed correct characterization of 32 of 38 masses, comparing favorably with CT, which allowed characterization of 30 lesions.     

Clinical experience with routine Gd-DTPA administration for MR imaging of the brain

A retrospective analysis of intracranial magnetic resonance (MR scans of 514 patients who underwent nonselective Gd-DTPA enhanced MR imaging was performed to determine the efficacy of this protocol for Gd-DTPA administration. This report reviews the frequency and clinical significance of abnormally enhancing areas that were entirely undetectable on precontrast images or would have been missed without the retrospective knowledge of enhancement. Fifty-seven patients (11% of the 514 patients studied) showed enhancing lesions, with 16 (3.1% of the total) of these patients demonstrating one or more lesions identifiable only on postcontrast images. Of those 16 patients, 8 had other focal abnormalities on precontrast studies, whereas the remaining 8 (1.6% of the total) had negative precontrast studies. The new diagnoses affected clinical management directly in five patients and in another nine contributed potentially significant information. Considerations regarding a selective versus nonselective protocol for Gd-DTPA administration for intracranial MR imaging and the use of clinical information to augment these protocols are discussed.     

Staging of urinary bladder neoplasms with MR imaging: is Gd-DTPA helpful?

This study was performed to investigate whether intravenous administration of Gd-DTPA can improve the accuracy of MR imaging in the detection and staging of bladder neoplasms. In 68 patients with suspected urinary bladder neoplasms, MR examinations were performed with T1-weighted SE sequences before and after intravenous administration of Gd-DTPA. The findings were compared with surgical staging using the TNM classification. Overall staging accuracy of contrast enhanced MR was 46%; if stages Ta-T3a were combined into one group, the accuracy was 69%. Accuracy was low (19%) in tumors without muscular bladder wall invasion (Ta). In cases with extravesical spread (greater than or equal to T3b), the accuracy of staging was 87%. Contrast enhanced MR detected extravesical extension of tumor with a sensitivity of 93% and a specificity of 95%. Contrast enhancement increased the sensitivity for detection of urinary bladder neoplasms from 70% on precontrast T1-weighted scans to 79% on postcontrast scans. In comparison with T2-weighted scans, the Gd-DTPA enhanced T1-weighted scans had better image quality and lower acquisition times.     

MR imaging of intraocular lesions--a comparison with CT]

Thirty-two intraocular lesions were studied with magnetic resonance (MR) imaging and computed tomography (CT). These lesions included retinoblastoma (n = 11), uveal melanoma (n = 6), metastatic choroidal tumor (n = 3), choroidal hemangioma (n = 2), retinochoroiditis (n = 6) and Coats' disease (n = 4). MR imaging was superior to CT in the depiction of intraocular masses and retinal detachment. Gd-DTPA enhanced MR imaging was more useful than contrast enhanced CT in evaluating the contrast enhancement of intraocular tumors. Differential diagnosis of intraocular tumors was difficult with both MR imaging and CT. Intratumoral calcification was noticed on CT in nine cases of retinoblastoma. It was concluded that MR imaging, including contrast enhancement study, is more useful than CT in the evaluation of intraocular lesions, except for calcification, and contrast enhanced CT may be unnecessary in the diagnosis of intraocular lesions.     

Dynamic contrast enhanced MRI in the differential diagnosis of adrenal adenomas and malignant adrenal masses

OBJECTIVE: To evaluate the value of dynamic MR imaging in the differential diagnosis of adrenal adenomas and malignant tumors, especially in cases with atypical adenomas. MATERIALS AND METHODS: Sixty-four masses (48 adenomas, 16 malignant tumors) were included in this prospective study. Signal loss of masses was evaluated using chemical shift MR imaging. Five dynamic series of T1-weighted spoiled gradient echo (FFE) images were obtained, with the acquisition starting simultaneously with i.v. contrast administration (0-100 s) followed by a T1-weighted FFE sequence in the late phase (5th minute). Contrast enhancement patterns in the early (25th second) and late (5th minute) phase images were evaluated. For the quantitative evaluation, signal intensity (SI)-time curves were obtained according to the SIs on the 0th, 25th, 50th 75th and 100th second. Also, the wash-in rate, maximum relative enhancement, time-to-peak, and wash-out of contrast at 100 s of masses in both groups were calculated. The statistical significance was determined by Mann-Whitney U test. To evaluate the diagnostic performance of the quantitative tests, receiver operating characteristic (ROC) analysis was performed. RESULTS: Chemical shift MR imaging was able to differentiate 44 out of 48 adenomas (91.7%) from non-adenomas. The 4 adenomas (8.3%) which could not be differentiated from non-adenomas by this technique did not exhibit signal loss on out-of-phase images. With a cut-off value of 30, SI indices of adenomas had a sensitivity of 93.8%, specificity of 100% and a positive predictive value of 100%. On visual evaluation of dynamic MR imaging, early phase contrast enhancement patterns were homogeneous in 75% and punctate in 20,83% of the adenomas; while patchy in 56.25% and peripheral in 25% of the malignant tumors. On the late phase images 58.33% of the adenomas showed peripheral ring-shaped enhancement and 10.41% showed heterogeneous enhancement. All of the malignant masses showed heterogeneous enhancement. At the 25th second, the SIs and wash-in rates of the adenomas were significantly higher than those of the malignant masses (p=0.010). Time-to-peak enhancement of the malignant masses was significantly longer than that of the adenomas. With a cut-off value of 52.85 s, the time-to-peak enhancement had 87.5% sensitivity and 80% specificity. CONCLUSION: Chemical shift MR has a high sensitivity and specificity in the differential diagnosis of adenomas and malignant adrenal masses. However, taking into consideration only the atypical adenomas, chemical shift MRI is of no diagnostic value. Although the diagnostic value of dynamic MRI is lower than chemical shift MRI, in the atypical cases contrast enhancement patterns and time-to-peak and wash-in rates derived from SI-time curve of dynamic MRI give are contributory to the results of chemical shift MRI.     

Adrenal adenomas: characteristic postgadolinium capillary blush on dynamic MR imaging

We sought to evaluate dynamic post-gadolinium contrast enhanced magnetic resonance (MR) imaging characteristics of adrenal adenomas with comparison to those of malignant adrenal tumors. MR images, including in- and out-of-phase spoiled gradient echo (SGE) and dynamic gadolinium enhancement, of 35 adrenal adenomas in 34 patients, and 12 malignant adrenal tumors in 12 patients, were reviewed retrospectively. MR images were assessed for the presence of a capillary blush on immediate postgadolinium SGE images, and for rapid washout of contrast on 45-second postgadolinium SGE images. Thirty-five adrenal adenomas (mean size, 3.1 cm) and 12 malignant adrenal tumors (mean size, 7.4 cm) were assessed. Of 35 adrenal adenomas, 25 (71%) showed a homogeneous capillary blush on immediate postgadolinium images. Thirty-three (94%) adrenal adenomas demonstrated rapid washout on 45-second postgadolinium images (P < 0.001). Of 35 adrenal adenomas, 30 (86%) showed diminished signal intensity (SI) on out-of-phase images. Of 12 malignant adrenal tumors, none showed a homogeneous capillary blush on immediate postgadolinium images. Six (50%) malignant tumors showed negligible enhancement, four (33%) showed irregular patchy enhancement, and two (17%) showed peripheral enhancement (P < 0.001). On 45-second postgadolinium images, 11 (92%) of 12 malignant adrenal tumors showed irregular enhancement. In the majority of adrenal adenomas, an initial homogeneous capillary blush and rapid washout are demonstrated on gadolinium-enhanced dynamic MR imaging. Our preliminary results suggest that this may provide useful complementary information to the appearance of adrenal masses on in- and out-of-phase images.     

Magnetic resonance tomography of adrenal gland tumors. Detection and differentiation using fast gradient echo sequences and dynamic contrast media studies

The use of fast gradient echo sequences enable reduction of the acquisition times in MR imaging, allowing examinations during suspended respiration. Furthermore, repeated single slices in the same position after administration of a paramagnetic contrast agent provide dynamic evaluation of tissue perfusion. These new diagnostic modalities were applied for imaging normal adrenal glands in 128 cases and for differentiation of 83 adrenal tumors in 74 patients. CT remains the imaging method of choice for the detection of adrenal masses, due to the higher spatial resolution. Fast gradient echo MRI offers the possibility of differentiation between benign and malignant adrenal lesions. The 70% accuracy reached with precontrast scans can be augmented to 90% using dynamic contrast-enhanced studies.