Testicular adrenal rest tumours in postpubertal males with congenital adrenal hyperplasia: sonographic and MR features

The purpose of this study was to investigate the prevalence of testicular adrenal rest tumours in patients with congenital adrenal hyperplasia (CAH), and to describe sonographic and MR features of these lesions. Seventeen postpubertal male CAH patients underwent scrotal sonography, with colour Doppler, and in 16 of them pre- and postcontrast enhanced T1- and T2-weighted MR images of the testes were obtained. Ultrasound revealed lesions in 16 of 17 patients (94%), bilateral in 10 patients and unilateral in 6 patients. The lesions were typically located adjacent to the mediastinum testis. The maximal diameter of the lesions varied from 2 to 40 mm. Margins were blurred in 11 of 31 lesions. Seventeen of the 20 lesions smaller than 2 cm in diameter were hypoechoic, whereas all 11 lesions larger than 2 cm showed hyperechoic reflections. On MR all lesions were isointense on T1- and hypointense on T2-weighted images and lesion margins were clearly defined. Enhancement of the lesions after intravenous contrast was seen in 13 of 15 patients. In our series the prevalence of testicular adrenal rest tumours in postpubertal CAH patients is much higher than in other reported studies. The lesions may develop from some small, hypoechoic, and multifocal nodules and coalesce to large hypoechoic lesions with hyperechoic reflections on ultrasound. As our results suggest that ultrasonography and MR show the lesions equally well, ultrasonography should be the method of first choice for detection and follow-up of these lesions, because it is the cheapest and quickest imaging technique. In case of a partial orchiectomy, MR is recommended because it shows lesion margins optimally.     

Testicular adrenal rest tissue in congenital adrenal hyperplasia: serial sonographic and clinical findings

OBJECTIVE: The purpose of this study was to describe the serial sonographic findings and clinical and laboratory data obtained during follow-up of patients with congenital adrenal hyperplasia in whom testicular adrenal rest tissue develops. MATERIALS AND METHODS: We retrospectively reviewed testicular sonography and laboratory data for 12 patients with congenital adrenal hyperplasia who also had intratesticular masses consistent with adrenal rest tissue. The studies were done during follow-up that ranged from 7 months to 10 years. RESULTS: During follow-up of 11 of the 12 patients after the initial sonographic diagnosis, the testicular adrenal rest tissue either remained stable in size (n = 1), grew larger or smaller (n = 9), disappeared (n = 4), or reappeared after disappearing (n = 3). In one patient, the testicular adrenal rest tissue grew very rapidly in a 1-month interval. Discordant changes in the testicular adrenal rest tissue were noted in 10 patients with bilateral masses. We found no relationship between the change in size of the masses and clinical control (based on 17-hydroxyprogesterone level) at the time of sonography. CONCLUSION: In patients with congenital adrenal hyperplasia who have testicular masses detected sonographically, testicular adrenal rest tissue is the most likely diagnosis. Testicular adrenal rest tissue may remain stable in size, grow larger or smaller, or disappear during sonographic follow-up. The change in size may be marked, may occur very rapidly, and, in our study cohort, was not related to short-term clinical control based on 17-hydroxyprogesterone level at the time of sonography.     

Testicular adrenal rests in a patient with congenital adrenal hyperplasia: US and MRI features

We present ultrasonographic and magnetic resonance imaging findings of intratesticular adrenal rests in a 16-year-old patient with congenital adrenal hyperplasia. Scrotal ultrasonography showed bilateral well-delineated homogenous hypoechoic lesions located around the mediastinum testis, which were highly vascularized on power Doppler ultrasonography. Relative to normal testicular parenchyma the lesions were iso- or hyperintense on T1-weighted and hypointense on T2-weighted images. T2-weighted images also showed a target-like appearance caused by a more hypointense peripheral halo around the lesions. The lesions enhanced remarkably on post-contrast images. This case suggests that radiological evaluation of testes, even in the presence of normal physical examination findings, should be included in periodical follow-up of patients with congenital adrenal hyperplasia. Magnetic resonance (MR) imaging is useful in demonstrating the lesions, because the contrast resolution better than with ultrasonography.     

Magnetic resonance imaging of the adrenal gland]

Adrenal imaging was performed using magnetic resonance (MR) was in 100 patients who had no clinical or biochemical evidence of adrenal abnormality and in 19 patients with 24 adrenal lesions (adenoma in 5, hyperplasia in 2, metastasis in 5, (lung cancer in 1, hepatoma in 4) adrenal cancer in 1, pheochromocytoma in 3, neuroblastoma in 3). Normal adrenal glands showed intermediate intensity between muscle and liver, and were detected in over 90% of cases on T1-weighted images (T1-weighted SE, inversion recovery). Adenomas and hyperplasias had the same intensity as normal glands. Medullary masses showed extreme hyperintensity on T2-weighted images and could be differentiated from cortical masses. Neuroblastomas were detected as hyperintense tumors with intratumoral hemorrhage and necrosis on T2-weighted MR images. Metastatic adrenal tumors from lung cancer were hyperintense on T2-weighted images, while metastasis from hepatoma showed low intensity on the same pulse sequence. In diagnosing adrenal metastasis, we must compare and contrast the tumor intensity and structure with those of the primary lesions. MR is considered a useful modality in characterizing adrenal tissue.     

Prevalence of ovarian adrenal rest tumours and polycystic ovaries in females with congenital adrenal hyperplasia: results of ultrasonography and MR imaging

The aim of the investigation was to assess the prevalence of ovarian adrenal rest tumours and polycystic ovaries in female patients with congenital adrenal hyperplasia (CAH). Thirteen female CAH patients (median age 19.8 years, range 14.8–23.5 years) underwent transvaginal (n=6) or transabdominal (n=7) ultrasonography by a gynaecologist and MR imaging (n=13) of the ovaries (pre and post contrast-enhanced T1- and T2-weighted images). Ovarian adrenal rest tumours were defined as small hypoechoic and multifocal nodules on ultrasound and isointense lesions on T1- and hypointense on T2-weighted MR images (derived from characteristics of testicular adrenal rest tumours). Polycystic ovaries were defined as the presence of 10 follicles arranged peripherally around or scattered throughout increased stroma. No ovarian adrenal rest tumours were found either on ultrasound, or by MR imaging. Polycystic ovaries were found in 2 of the 13 patients (15.4%), both with ultrasound and MR. No ovarian adrenal rest tumours were detected in these female CAH patients, which suggests that ovarian adrenal rest tumours in CAH females are rare. The prevalence of polycystic ovaries corresponded to that in the general population. From these results, we would suggest that routine ovarian imaging in CAH females is not indicated. However, when ovarian dysfunction is present, ovarian imaging is advised, first by ultrasonography, to detect ovarian adrenal rest tumours or polycystic ovaries.     

How accurate is MR imaging in characterisation of adrenal masses: update of a long-term study.

OBJECTIVE: The purpose of this study was to update a long-term study that evaluates the accuracy of MR imaging in the characterisation of adrenal tumours. In all patients, MR imaging findings were correlated with histopathologic results. PATIENTS: In 204/560 patients who underwent MR imaging for characterisation of an adrenal mass, histopathologic results were available. The final study group consisted of 229 adrenal masses in 204 patients. MR imaging was performed using T2-weighted fast spin-echo imaging and unenhanced and gadolinium-enhanced T1-weighted spin-echo imaging in all patients. In addition, chemical shift imaging was performed in 182 patients and dynamic gadolinium-enhanced studies in 198 patients. Chemical shift images and dynamic studies were qualitatively assessed. All images were reviewed by an experienced investigator (Gertraud Heinz-Peer) who was blinded to the clinical history and the results of prior imaging studies. RESULTS: The sensitivity of MR imaging for the differentiation of benign and malignant adrenal masses was 89%, the specificity 99%, and the accuracy was 93.9%. This results in a positive predictive value (PPV) of 90.9% and a negative predictive value (NPV) of 94.2%. These results are comparable to the data published previously by our study group with a lower number of cases. CONCLUSION: Large study numbers show that MR imaging is a reliable method in characterisation of benign and malignant adrenal masses. Since laparoscopic adrenalectomy has become the new gold standard in the surgical treatment of benign adrenal lesions, the high accuracy of MR imaging in characterisation of those lesions offers even patients with large adrenal masses (>5 cm) the advantages of the minimally invasive technique.     

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.     

Primary hyperaldosteronism (Conn syndrome): MR imaging findings

PURPOSE: To describe the magnetic resonance (MR) imaging features of the adrenal glands in primary hyperaldosteronism and assess MR imaging in the detection and characterization of aldosterone-producing adenoma (APA). MATERIALS AND METHODS: The authors retrospectively reviewed the cases of 20 patients (13 female and seven male patients; age range, 14-67 years; median age, 46 years) with primary hyperaldosteronism who underwent 1.5-T MR imaging between 1995 and 1998. All patients underwent transverse T1- and T2-weighted imaging, and chemical shift imaging was performed in 17 patients. Imaging results were correlated with findings at biochemical testing, venous sampling, or surgery. RESULTS: Among the 20 patients, 10 (50%) had APA and 10 (50%) bilateral adrenal hyperplasia (BAH). In the detection of APA, MR imaging had a sensitivity of 70%, specificity of 100%, and accuracy of 85%. APAs (mean size, 20 x 16 mm) were iso- or hypointense relative to the liver on T1-weighted images and slightly hyperintense on T2-weighted images. With chemical shift imaging, the signal intensity decreased on the out-of-phase images in six of seven (86%) patients with APA and in eight of nine (89%) patients with BAH. CONCLUSION: MR imaging has a high specificity in the detection of APA. As with nonhyperfunctioning adenoma, APA and BAH show evidence of intracellular lipid at chemical shift imaging.     

Adrenocorticotropin-independent macronodular adrenal hyperplasia: an uncommon cause of primary adrenal hypercortisolism

PURPOSE: To describe the imaging findings in the adrenal glands of 12 patients with adrenocorticotropin (ACTH)-independent macronodular adrenocortical hyperplasia (AIMAH). MATERIALS AND METHODS: Computed tomographic (CT) and magnetic resonance (MR) imaging findings in the adrenal glands were reviewed retrospectively in 12 patients (three men, nine women) with ACTH-independent Cushing syndrome and with bilateral nonpigmented multinodular adrenal hyperplasia. The results of pituitary MR imaging, adrenal scintigraphy, and petrosal sampling were available in nine, five, and six patients, respectively. Eleven patients underwent bilateral and one patient underwent unilateral adrenalectomy. RESULTS: Eleven patients had enlarged multinodular adrenal glands: Nodules were 0.1-5.5 cm. The combined weight of both adrenal specimens for the 11 bilateral adrenalectomy specimens was 28-297 g, with a mean weight of 122 g. Glands were hypointense compared with the liver on T1-weighted images and were hyperintense on T2-weighted images. Pituitary MR imaging findings were negative in nine of nine patients. Iodomethylnorcholesterol scintigraphy showed bilateral uptake in four of five patients. Petrosal sinus sampling revealed no petrosal-to-peripheral ACTH gradients before corticotropin-releasing hormone (CRH) stimulation in six of six patients, but three patients had gradients after CRH stimulation. After undergoing bilateral or unilateral adrenalectomy, all patients were cured. CONCLUSION: AIMAH is a rare cause of ACTH-independent Cushing syndrome, with characteristic CT findings of massively enlarged multinodular adrenal glands. Bilateral adrenalectomy is indicated on the basis of clinical and CT findings.     

MR evaluation of adrenal masses at 1.5 T

We retrospectively studied the value of MR imaging at 1.5 T to distinguish between nonadenomatous (n = 17) and adenomatous (n = 15) adrenal masses on the basis of (1) signal-intensity ratios on T1- and T2-weighted spin-echo images, (2) T2 relaxation times, and (3) T2 relaxation-time ratios. Univariate and then multivariate logistic regression were applied to these quantitative parameters to determine which of these best discriminated nonadenomas from adenomas, and whether or not more than one of these parameters improved the prediction. The adrenal mass/liver signal-intensity ratio on T2-weighted spin-echo images could not be used to differentiate nonadenomas from adenomas. Adrenal mass/fat signal-intensity ratios on T2-weighted spin-echo images, adrenal/liver T2 relaxation-time ratios, and adrenal mass T2 relaxation times were best for distinguishing nonadenomas from adenomas. By using a T2 value of greater than 61 msec, the true-positive ratio/false-positive ratio of differentiating nonadenomas from adenomas was 100%/20%; at greater than 82 msec, it was 64%/0.06%. The adrenal mass/fat signal-intensity ratios on T2-weighted spin-echo images and the adrenal/liver T2 relaxation-time ratios showed similar inherent discriminatory capacity. Overlap remains despite the use of these parameters. On the basis of this preliminary information, we conclude that MR has merit for the characterization of adrenal masses at 1.5 T. T2 relaxation time of the adrenal mass shows the greatest promise for discriminating nonadenomas from adenomas.     

Magnetic resonance imaging of adrenal cortical carcinoma

Five cases of adrenal cortical carcinoma examined with magnetic resonance (MR) are presented. Clinical histories, computed tomographic (CT) scans, and final pathologic findings were reviewed in each case. All masses were hypointense compared to the liver on T1-weighted images and became hyperintense compared to the liver on T2-weighted images. Signal intensity of adrenal masses, fat, and liver were measured. Adrenal/liver and adrenal/fat signal intensity ratios were then calculated. All the masses were readily identified with MR. The MR also demonstrated displacement or invasion of adjacent organs, as well as liver metastases. The inferior vena cava was also identified in each case. Even though there were no consistent MR findings to diagnose adrenal cortical carcinomas accurately, superior blood vessel identification and multiplanar capabilities may make MR the imaging modality of choice in evaluating the extent of disease and in planning surgical excision.     

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.     

Value of MRI in symptomatic patients treated with tamoxifen

PURPOSE: To assess the MR imaging (MRI) findings in symptomatic tamoxifen treated-women with abnormal transvaginal sonography. PATIENTS AND METHODS: From january 1997 to june 2000, 32 consecutive symptomatic tamoxifen treated-women with abnormal transvaginal sonography were prospectively studied by MRI. T1-weighted, T2-weighted, post-contrast T1-weighted and dynamic gradient-echo T1-weighted sequences were used. All patients underwent uterine sampling within one month of MRI. RESULTS: Endometrial thickness at sonography ranged from 5 to 48 mm (mean thickness 19 mm), and on T2-weighted imaging ranged from 3 to 50 mm (mean=25 mm). Three MRI patterns were found. Pattern 1 (13 patients) was defined as homogeneous high signal intensity of the endometrium on T2W images, and signal void in the lumen on gadolinium-enhanced images. Pattern 2 (8 patients) was defined as heterogeneous endometrial signal on T2W images, and latticelike enhancement traversing the endometrial canal on gadolinium-enhanced images. Pattern 3 (11 patients) was defined as heterogeneous signal on T2W images with masses or nodules which were better seen on dynamic gadolinium-enhanced images. In pattern 1 we found 13 atrophic endometrium, in addition there were 4 polypoid glandulo-cystic proliferation (PGCP), and 1 adenomyosis. In pattern 2 we found 3 PGCP, 4 atrophy and 1 polyp without hyperplasia. The 2 carcinomas and the polyps with hyperplasia were found in pattern 3 (11 patients). CONCLUSION: In our experience MRI allows differentiation of lesions which may require surgery from other lesions in which noninvasive follow-up is possible.     

Detection of hepatic masses in patients with carcinoma: comparative sensitivities of sonography, CT, and MR imaging

To evaluate the sensitivity of sonography, CT, and MR imaging in the detection of hepatic masses in carcinoma patients, we conducted a prospective study of 75 consecutive patients with gastrointestinal tumors who were admitted for surgical resection of the primary tumor. Sonography was performed with convex transducers of 3.5 and 5.0 MHz. Three noninvasive CT techniques were used: unenhanced CT scans, the incremental bolus dynamic scanning technique, and delayed scanning 4-6 hr after bolus injection of 60 g of iodine. MR images (1.5 T) were acquired as presaturated T1- and T2-weighted spin-echo sequences and as breath-holding fast low-angle shot (FLASH) 60 degrees and FLASH 15 degrees sequences. As it is difficult to distinguish benign from malignant masses solely on the basis of morphologic criteria, the techniques for each imaging method were designed to detect and not to characterize hepatic lesions. Each examination was interpreted blindly, and the results were compared with surgical findings, intraoperative sonography, and biopsy of the liver as the gold standard. All focal hepatic masses verified at surgery, malignant or benign, were included in the analysis. Sixty-five (68%) of 95 focal hepatic masses were detected by CT, 60 lesions (63%) by MR, and 50 lesions (53%) by sonography. Although lesions 1-2 cm were shown almost equally well by CT and MR (74% and 77%, respectively), the detection rate of smaller lesions (less than 1.0 cm) decreased more drastically with MR (31%) than with CT (49%). Sonography had a sensitivity of only 20% with the smaller lesions. All imaging techniques had a sensitivity of 100% for focal hepatic masses larger than 2.0 cm. Our results show that CT has a higher overall sensitivity (68%) than MR and sonography for the detection of focal hepatic masses. When the results of the three procedures are combined, the overall sensitivity is 77%. This is unsatisfactorily low, as CT and MR have a size threshold of about 1.0 cm and are relatively unreliable for the detection of smaller lesions.     

Diagnostic accuracy of chemical-shift MR imaging to differentiate between adrenal adenomas and non adenoma adrenal lesions

PURPOSE: The objective of this study was to evaluate the diagnostic accuracy of chemical-shift (CS) magnetic resonance (MR) imaging in the differential diagnosis of adenoma and nonadenoma adrenal masses. MATERIALS AND METHODS: We enrolled 36 patients (9 men, 27 women, mean age 51.3+14.4 years) with unilateral (n=31) or bilateral (n=5) adrenal masses incidentally discovered during imaging examinations [ultrasound (US), computed tomography (CT)] performed for other indications. A total of 41 adrenal lesions were evaluated (mean diameter 3.0+2.2 cm). Histology (n=19), biopsy (n=3) or clinical-imaging follow-up (n=19) demonstrated 29 adenomas, five pheochromocytomas, three cysts and four carcinomas. MR imaging was performed using the following breath-hold sequences: T1-fast field echo (FFE) [repetition time (TR)/echo time (TE)=236/4.6 ms], T2-turbo spin echo-single shot (TSE-SSh) (TR/TE=831/80 ms), T1-DUAL-FFE (TR=236, double TE=4.6/2.3 ms in phase and out of phase) and T1-FFE after gadolinium-DTPA (Gd). Axial and coronal imaging planes were used, with a slice thickness of 3-5 mm. MR images were qualitatively assessed for signal intensity of the adrenal mass relative to the liver on T1, T2, CS and T1-Gd scans; diagnostic criteria for adenomas were isointensity or hypointensity on both T1 and T2 scans, out-of-phase CS signal loss and mild transient enhancement after Gd. RESULTS: Analysis of T1-T2 signal intensity showed diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 80%, 72%, 100%, 100% and 60%, respectively. In contrast, analysis of CS and T1-Gd signal intensity showed diagnostic accuracy, sensitivity, specificity, PPV and NPV for both sequences of 93%, 90% (p<0.05 vs. T1-T2 analysis), 100%, 100% and 80% (p<0.05 vs. T1-T2 analysis), respectively. CONCLUSIONS: CS MR imaging significantly improves characterization of adrenal masses compared with conventional T1-T2-weighted images, providing accuracy similar to that of the T1 sequence after Gd. Therefore, the CS sequence is strongly recommended for MR study of adrenal masses, and its use might obviate the need for Gd administration.     

MR imaging of testicular torsion: features of testicular hemorrhagic necrosis and clinical outcomes

PURPOSE: To determine whether emergency subtraction dynamic contrast-enhanced MR imaging (DCE-MRI) in combination with T2- and T2*-weighted imaging of the testis is useful in the evaluation of patients with testicular torsion. MATERIALS AND METHODS: Fourteen patients with surgically proven testicular torsion were examined using preoperative emergency MRI, including T2-weighted, T2*-weighted, and DCE-MRI. The affected testis was examined histologically in eight patients who underwent orchiectomy, and by postoperative follow-up MRI in six patients who underwent orchiopexy. The diagnostic criteria for testicular torsion and detection of hemorrhagic necrosis in the affected testis in emergency MRI were decreased or no perfusion in DCE-MRI and a spotty and/or streaky pattern of low or very low signal intensity in T2- and T2*-weighted images. The intraoperative findings and clinical outcomes were also compared. RESULTS: The histological findings and follow-up MR images revealed total or partial necrosis of the affected testis in 10 of the 14 patients. In the diagnosis of complete torsion, the sensitivities were 100% for DCE-MRI and 75% for T2- and T2*-weighted imaging. In the detection of testicular necrosis, T2- and T2*-weighted imaging showed the highest accuracy (100%), followed by 12-hour time from onset (93%), intraoperative findings (79%), and DCE-MRI (71%). CONCLUSION: Emergency MRI can help diagnose testicular torsion and detect testicular necrosis when DCE-MRI is used in combination with T2- and T2*-weighted images.     

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.     

Evaluation of adrenal masses in oncologic patients: dynamic contrast-enhanced MR vs CT

The CT examinations, precontrast gradient echo MR images, and fast contrast enhanced dynamic MR studies were evaluated in 44 patients with 52 adrenal masses and known malignant disease of different origin. Morphologic features (size, shape, attenuation, contour, and enhancement) on CT scans, signal intensity on T2-weighted MR images, and patterns of enhancement on Gd-DTPA enhanced dynamic MR studies were analyzed in all patients. With dynamic contrast enhanced studies with prolonged imaging up to 15 min after Gd-DTPA, masses with moderate enhancement and complete washout after 10 min were considered as adenomas. Computed tomography and plain MR had a sensitivity of 0.71 and 0.96, a specificity of 0.75 and 0.88, and overall accuracy of 0.56 and 0.71, respectively. Simultaneous use of precontrast MR and dynamic contrast enhanced studies led to an accurate diagnosis in 88% (sensitivity = 1.0, specificity = 0.91) and thus should be considered in oncologic patients with undetermined adrenal masses.     

MR imaging of adrenal myelolipomas

The magnetic resonance (MR) images in six patients with seven adrenal myelolipomas are presented. Four lesions involved the right gland, and three the left; they ranged from 3 to 12.5 cm in diameter. Magnetic resonance was able to image all lesions. Using T1-weighted sequences, three structural patterns were observed; (a) homogeneous masses with intensity equal to adjacent fat (three cases); (b) heterogeneous masses with fat intensity areas and areas similar to renal cortex (two cases); and (c) nodules quite different from fat, hypointense to the liver (two cases). On T2-weighted images, myelolipomas were slightly hypointense to fat and either hypo- or isointense to the liver. A comparison with the results of CT studies was possible in all cases, and good correlation with determination of the presence and quantity of fat density tissues within the lesions was observed. However, MR imaging did not seem to help in diagnosing adrenal myelolipoma in patients with equivocal CT findings, and needle biopsy is still needed in difficult cases.     

Depiction of the normal adrenal gland evaluation with 0.5 tesla MRI

MR studies of the abdomen in 128 patients were reviewed in order to evaluate the normal adrenal glands. The studies were performed on a 0.5-Tesla superconducting unit. T1-weighted spin-echo (T1WI), T2-weighted spin-echo (T2WI) and T2*-weighted gradient-echo (T2*-WI) images were obtained. T1WI demonstrated the normal adrenal glands in 90% of the patients. T2*WI identified the glands in 86%, a higher rate than the 73% for T2WI. On both T1WI and T2WI, the right adrenal gland was demonstrated of a lower rate than the left adrenal gland, because the right retroperitoneal fat layer was narrow in patients with hepatic tumors. T2*WI depicted both adrenal glands equally, because the intensity of the left adrenal gland was the same as that of collateral veins from portal hypertension. It is suggested that both T1WI and T2WI with a gradient echo pulse sequence are more useful in depicting the adrenal glands than both T1WI and T2WI.