Ovarian cystic teratomas: MR imaging

Cystic Ovarian Lesions in SSFP Diffusion Imaging

PURPOSE

MR assessments of ovarian cystic lesions are usually based on morphological features, signal intensities and enhancement with contrast media. This study was performed to evaluate the usefulness of the steady-state free precession (SSFP) diffusion imaging of cystic ovarian lesions for analyzing cystic contents.

MATERIALS AND METHODS

Sixty-one ovarian cystic lesions in 37 patients were examined. The diffusion-related coefficient (DRC) and the ratio of the relative apparent diffusion coefficient of the lesion to that of subcutaneous fat tissue (rADC(L)/rADC(F)) were calculated from SSFP diffusion images.

RESULTS

The DRCs and the rADC(L)/rADC(F) ratios in endometrial cysts and in the fatty parts of dermoid cysts were significantly lower than in other cystic tumors.

CONCLUSION

SSFP diffusion imaging can be included in clinical practice to analyze ovarian cystic lesions within a short scan time; the DRC and the rADC(L)/rADC(F) ratio are useful for evaluating cystic contents.

Ovarian teratomas: tumor types and imaging characteristics

Ovarian teratomas include mature cystic teratomas (dermoid cysts), immature teratomas, and monodermal teratomas (eg, struma ovarii, carcinoid tumors, neural tumors). Most mature cystic teratomas can be diagnosed at ultrasonography (US) but may have a variety of appearances, characterized by echogenic sebaceous material and calcification. At computed tomography (CT), fat attenuation within a cyst is diagnostic. At magnetic resonance (MR) imaging, the sebaceous component is specifically identified with fat-saturation techniques. The US appearances of immature teratoma are nonspecific, although the tumors are typically heterogeneous, partially solid lesions, usually with scattered calcifications. At CT and MR imaging, immature teratomas characteristically have a large, irregular solid component containing coarse calcifications. Small foci of fat help identify these tumors. The US features of struma ovarii are also nonspecific, but a heterogeneous, predominantly solid mass may be seen. On T1- and T2-weighted images, the cystic spaces demonstrate both high and low signal intensity. Familiarity with the US, CT, and MR imaging features of ovarian teratomas can aid in differentiation and diagnosis.

Unusual "floating balls" appearance of an ovarian cystic teratoma: sonographic and CT findings

Ovarian cystic teratomas are cystic fatty tumors that can be easily diagnosed by sonography and CT. We present a case of ovarian cystic teratoma with an unusual sonographic appearance of mobile, hyperechoic, intracystic fat balls; this finding correlated well with the appearance on CT.

Imaging evaluation of ovarian masses

Adnexal masses present a special diagnostic challenge, in part because benign adnexal masses greatly outnumber malignant ones. Determination of a degree of suspicion for malignancy is critical and is based largely on imaging appearance. Endovaginal ultrasonography (US) is the most practical modality for assessment of ovarian tumors because it is readily available and has a high negative predictive value. Morphologic analysis of adnexal masses is accurate for identifying masses as either low risk or high risk. The most important morphologic features are non-fatty solid (vascularized) tissue, thick septations, and papillary projections. Color Doppler US helps identify solid, vascularized components in a mass. Spectral Doppler waveform characteristics (eg, resistive index, pulsatility index) correlate well with malignancy but generally add little information to morphologic considerations. Computed tomography can help assess the extent of disease in patients before and after primary cytoreductive surgery. Magnetic resonance (MR) imaging is better reserved for problem solving when US findings are nondiagnostic or equivocal because, although it is more accurate for diagnosis, it is also more expensive. The signal intensity characteristics of ovarian masses make possible a systematic approach to diagnosis. Mature cystic teratomas, cysts, endometriomas, leiomyomas, fibromas, and other lesions can be accurately diagnosed on the basis of T1-weighted, T2-weighted, and fat-saturated T1-weighted MR imaging findings.

Value of fat-suppression gradient-echo MR imaging in the diagnosis of ovarian cystic teratomas

Gradient-echo MR imaging (MRI) was evaluated for the diagnosis of ovarian mature cystic teratomas (MCTs). The FLASH technique was applied to T1-weighted images with and without fat suppression in 18 surgical operated patients with 19 MCTs, and findings were compared to those of conventional spin-echo (SE) T1-weighted-SE. Seventeen out of 19 MCTs were correctly diagnosed using FLASH and SE T1-weighted MR images with and without fat saturation. This study suggests that gradient-echo MRI can replace conventional SE T1-weighted MRI for the diagnosis of ovarian MCTs.

Complex adnexal masses: detection and characterization with MR imaging--multivariate analysis

PURPOSE

To evaluate the accuracy of magnetic resonance (MR) imaging in the detection and characterization of complex adnexal masses, with particular reference to the findings predictive of malignancy, role of gadolinium-enhanced contrast material, and observer variability.

MATERIALS AND METHODS

Preoperative MR imaging of the pelvis was performed in 128 consecutive patients with clinically or ultrasonographically detected complex adnexal masses. Histopathologic examination demonstrated 187 masses, 96 of which were malignant. MR imaging studies were prospectively and independently reviewed by two radiologists, one of whom reevaluated the studies after a 6-month interval. The predictive value of MR imaging findings was determined with multivariate logistic regression analysis. The value of gadolinium enhancement was assessed by using receiver operating characteristic analysis. Inter- and intraobserver variabilities were assessed by using weighted K statistics.

RESULTS

Gadolinium-enhanced MR imaging depicted 176 (94%) of 187 adnexal masses, with an overall accuracy for the diagnosis of malignancy of 93%. The MR imaging findings that were most predictive of malignancy were necrosis in a solid lesion (odds ratio, 107) and vegetations in a cystic lesion (odds ratio, 40). Use of gadolinium-based contrast material contributed significantly to lesion characterization. Interobserver (K, 0.79-0.85) and intraobserver (K, 0.84-0.86) agreement were excellent.

CONCLUSION

Gadolinium-enhanced MR imaging is highly accurate in the detection and characterization of complex adnexal masses, with excellent inter- and intraobserver agreement.

Squamous cell carcinoma arising in a mature teratoma with metastasis to the urinary bladder

We describe a patient with squamous cell carcinoma arising in a mature teratoma. Magnetic resonance (MR) images revealed a solid lobulated mass attached to the ovarian cyst containing a fat-fluid level. The solid component with extension into pelvic fat showed as hypointensity on T2-weighted MR images with good enhancement. A metastatic tumor to the urinary bladder was also demonstrated.

Magnetic resonance imaging of the female pelvis

Evaluation of pelvic pathology is an important part of most radiology practices. Magnetic resonance imaging (MRI) has proven itself to be a useful and cost-effective method in evaluating many of these diseases. This article reviews appropriate MR imaging techniques and findings of common gynecologic disorders. Uterine pathology is categorized into congenital anomalies, benign lesions (leiomyomas, adenomyosis, endometrial polyps, and nabothian cysts), and malignancies (endometrial and cervical carcinoma). Adnexal pathology reviewed includes endometriosis, polycystic ovaries, teratomas, and benign and malignant ovarian epithelial tumors.

Steroid cell tumors of the ovary: clinical, ultrasonic, and MRI diagnosis--a case report

Steroid cell tumors of the ovary are rare sex-cord neoplasms which account for less than 0.1% of all ovarian tumors. They have been divided into two subtypes according to their cell of origin as follows: stromal luteoma, and Leydig cell tumors, and a third subtype with lineage unknown is a steroid cell tumor, not otherwise specified (NOS). The clinical presentation may take many forms, including pain, abdominal distention and bloating, but perhaps the most interesting and noticeable presentations are those related to the hormonal activity and virilizing properties of the tumor. No radiological features of the steroid cell tumor, NOS have been presented in the literature. This report presents the MRI and ultrasonographic findings of a patient having steroid cell tumor, NOS, of the right ovary with metastasis to the uterus.

Ovarian fibromas and cystadenofibromas: MRI features of the fibrous component

Ovarian fibromas and cystadenofibromas are neoplasms that share a similar distinctive tissue component of dense fibrous tissue. We sought to describe the MRI features of these neoplasms and to determine if the fibrous component shows distinctive characteristics. Fourteen patients in whom MR images performed with multicoil and fast-spin-echo images and who subsequently underwent surgery for resection of ovarian fibromas or cystadenofibromas were identified from two institutions. Five patients had ovarian fibromas, and nine patients had fourteen cystadenofibromas. 1.5-T MR studies used T1-weighted spin echo and multiplanar T2-weighted fast-spin-echo images, with fat saturation gadolinium-enhanced fast multiplanar gradient-echo images in seven patients. Studies were reviewed for findings of low (approximately equal to skeletal muscle) signal intensity solid components on T2-weighted images, characteristics of gadolinium enhancement, and associated endometrial findings. Images were obtained ex vivo from three adnexal surgical specimens with an 8-cm field of view and correlated with histology. All five of the fibromas showed predominantly very low signal intensity, similar to skeletal muscle, on T2-weighted images. Two of five fibromas were in patients with endometrial polyps and increased amounts of fluid in the pelvis. Thirteen cystadenofibromas were multicystic masses with bands of very low signal intensity ranging from 2 to 20 mm in the wall of the mass, and one was predominantly solid fibrous tissue. Pathologic correlation with specimen images showed that the low signal intensity material was the subepithelial fibrous component of the cystadenofibromas. Fibrous components of ovarian fibromas and cystadenofibromas are demonstrable by MR as solid components representing fibrous tissue of very low signal intensity on T2-weighted images.

Adhesion formation from release of dermoid contents in the peritoneal cavity and effect of copious lavage: a prospective, randomized, blinded, controlled study in a rabbit model

OBJECTIVES

To determine, in a rabbit model, whether peritoneal exposure to dermoid cyst material produces inflammation and adhesions above control levels and whether saline lavage reduces the degree of peritoneal reaction.

DESIGN

A prospective, randomized, blinded, controlled study of adhesion formation. Thirty New Zealand white female rabbits were assigned randomly to five experimental groups: [1] laparoscopy with intraperitoneal injection of human dermoid material, [2] laparoscopy with intraperitoneal injection of human dermoid material and subsequent lavage to clear all visible dermoid material, [3] laparoscopy with saline lavage, [4] laparoscopy with intraperitoneal injection of human follicular fluid (antigenic control), and [5] laparoscopy alone.

MAIN OUTCOME MEASURES

Six weeks after initial laparoscopy, inflammation and adhesions were scored in several categories via visual assessment (range 0 to 15) and histologic microscopic evaluation (range 0 to 24). Data were evaluated using Kruskal-Wallis and Mann-Whitney U nonparametric tests.

RESULTS

For groups 1, 2, 3, 4, and 5, respectively, mean +/- SEM total inflammation-adhesion scores were 13.85 +/- 0.55, 2.90 +/- 1.15, 0 +/- 0, 1.50 +/- 1.00, and 0 +/- 0 for clinical evaluation and 16.83 +/- 1.22, 7.33 +/- 1.76, 0 +/- 0,0 +/- 0, and 0 +/- 0 for histologic evaluation. Using nonparametric tests, significant differences were found between groups in clinical and histologic scores.

CONCLUSIONS

Dermoid material produces a significant peritonitis. Results of the clinical evaluation demonstrate that saline lavage brings inflammation and adhesion formation close to control levels. However, results of the histologic evaluation suggest that the decrement in inflammation as a result of lavage may be less dramatic than that found by clinical evaluation.

Distinguishing between cystic teratomas and endometriomas of the ovary using chemical shift gradient echo magnetic resonance imaging

The purpose of this study was to evaluate the efficacy of chemical shift gradient echo magnetic resonance imaging (MRI) in distinguishing between cystic teratomas and endometriomas of the ovary, using a 1.5T magnet. The study included 22 patients with 31 ovarian lesions (15 cystic teratomas and 16 endometriomas), which showed high signal intensity on T1-weighted spin echo images. Chemical shift gradient echo images with three different echo times (TE = 2.5, 4.5 and 6.5 ms) were obtained in all cases. Indices were calculated on the basis of the signal intensities of lesions on the chemical shift gradient echo images. All endometriomas had signal intensity indices of less than 2.1, while all cystic teratomas had signal intensity indices of 18.1 or greater. Chemical shift gradient echo imaging is an alternative method that is useful and simple for distinguishing between cystic teratomas and endometriomas of the ovary.

Mature cystic teratomas of the ovary: CT and MR findings

OBJECTIVE

To correlate CT and MR patterns of ovarian mature cystic teratomas (MCT).

SUBJECTS AND METHODS

CT and MR findings in 25 histologically proven ovarian MCT were retrospectively reviewed. MCT characterization at CT and MR was based on detection of fat and/or a Rokitansky protuberance. MR signal intensity and CT density numbers of fat were correlated.

RESULTS

At pathology, 24/25 tumors contained fat, 1/25 a water content, and 23/25 a Rokitansky protuberance. Twenty one MCT contained fat with a density number less than-20 HU (mean density: -95 HU) and a signal intensity superior or equal to sub-cutaneous fat on T1 images, however, only six of these had a signal intensity equal to sub-cutaneous fat on T1 and T2 images and 12 had a reversed chemical shift artifact. Three contained fat with a density number ranging from -13 to +8 HU and a signal intensity inferior to subcutaneous fat on T1 images. CT showed a Rokitansky protuberance in 21/23, containing adipose tissue in 16 and calcified structures in 21. Standard MR showed a Rokitansky protuberance in 14/23 and characterized adipose tissue in eight cases, and calcified material in six cases. Finally, CT characterized 24/25 (96%) MCT. Standard MR characterized 22/25 (88%) MCT, and standard MR with fat-suppression sequences characterized 23/25 (92%) MCT.

CONCLUSION

Standard MR is less effective than CT in characterizing fat and has the same difficulty as CT in characterizing fat mixed with hair when its density is high. When fat cannot be identified by either technique, diagnosis of a Rokitansky protuberance is more easily made at CT than at MR.

Solid mature teratoma of the ovary: appearances at MR imaging

Magnetic resonance imaging (MRI) appearances of a case with rare solid mature teratoma of the ovary is presented. The lesion was almost entirely solid with small cystic component. The solid tissue, consisting of bronchial cartilage, smooth muscle, glands, and epithelium, exhibited hypointense signal on T1-weighted image, relatively hyperintense signal on T2-weighted image, and reticular pattern of enhancement on the postcontrast scan. The presence of fatty tissue mixed with hair bundle, which did not exhibit a signal intensity of fatty tissue, was clearly indicated by chemical shift artifact within the cystic component.

Magnetic resonance imaging evaluation of adnexal masses

Anatomically, the adnexa encompasses the region within the pelvis that includes the ovary, fallopian tube, round ligament, and structures arising from associated embryologic rests. The scope and spectrum of gynecologic pathology seen in this area is enormously diverse, and specific diagnoses are often elusive to conventionally-used imaging techniques such as ultrasound and CT. MRI has become an important tool in the evaluation of the adnexal mass because of its multiplanar capability and undersurpassed soft tissue contrast. It is particularly effective in defining the origin of a pelvic mass. The recent development of fast spin-echo sequences along with new phased array coils have enabled higher resolution imaging in shortened imaging times. The result is improved characterization of adnexal masses, which often leads to specific diagnoses.

The role of magnetic resonance imaging in problematic gynecologic diagnoses

MRI is a modality that provides excellent anatomic detail, especially of soft tissue and bone. Comparison of T1-weighted and T2-weighted images offers significant diagnostic information of pelvic pathology. In five problematic gynecologic cases, magnetic resonance imaging (MRI) provided key information for optimal treatment planning or a definitive diagnosis for the gynecologist.

Ovarian cystic teratomas: value of chemical fat saturation magnetic resonance imaging

Chemical fat saturation (FS) magnetic resonance imaging (MRI) for the characterization of ovarian cystic teratoma was evaluated in 19 patients with 22 lesions. The tumour was evaluated for signal intensity, location and size; the presence of chemical shift artefact, debris and fat-fluid level. Ovarian cystic teratoma was diagnosed prospectively if the mass contained fat and/or more than one type of internal pattern on (1) SE T1-, T2-, (2) SE T1-, T2-, FS T1-weighted images. A correct diagnosis was reached in 17 of 22 tumours on conventional T1- and T2-weighted images, and in 21 of 22 tumours when fat-saturation images were added. When fat-saturation images were added, four of five tumours misdiagnosed on conventional images were then correctly diagnosed. These tumours contained only small amounts of fat. Fat-saturation images could detect smaller amounts of fat than conventional images. However, one tumour did not show decreased intensity on fat saturation images, and was not diagnosed even when fat-saturation images were added. Fat saturation images have been shown to be of value in diagnosing cystic teratomas.

Fat suppression techniques in MR imaging of mature ovarian teratomas: comparison with CT

OBJECTIVE

The aim of this study is to analyze the ability of MR fat suppression techniques to characterize fat components of ovarian mature cystic teratomas (MCT) shown by CT.

SUBJECTS AND METHODS

MR images of eight MCTs of the ovary were obtained using standard sequences followed by a SPIR (spectral presaturation with inversion recovery) sequence in six cases and by Dixon sequences in two cases. In all cases correlation with CT and pathologic findings was achieved.

RESULTS

MR fat suppression sequences showed to be as accurate as CT in detecting fat inside the cystic part of the teratomas (8/8).

CONCLUSION

MR fat suppression sequences should be performed when presence of fat is suspected on images of ovarian tumors produced by standard MR sequences.

Magnetic resonance imaging of female pelvic masses and local recurrent tumors at an ultra low (0.02 T) magnetic field: correlation with computed tomography

Pelvic MR (41 patients) and CT (36 patients) examinations were performed on 14 females with a primary pelvic complaint, and on 28 females with a suspicion of local recurrent disease of gynecologic malignant tumor. Benign cystic tumors were found in eight patients, five patients had endometriomas, one had a lymphoma, and one had a small androblastoma. Ten local recurrent tumors were confirmed histopathologically or cytologically. All cysts, one endometrioma, the lymphoma, and six recurrent tumors were detected on images obtained by our ultra low field magnetic unit. The smallest cyst detected was 16 mm in diameter. Small scattered implants of endometriosis were not discerned. The appearance of the tumors did not differ essentially from those described at high magnetic fields. Physical examination detected all 10 recurrent tumors, CT detected 8 of them, and MRI 6 out of 9 cases. The sensitivities of physical examination, CT and MRI to find recurrent diseases were 100%, 80%, and 67%, respectively. Corresponding specificities were 93%, 67%, and 80%. The results indicate that physical examination is most important in recurrent diseases. CT is the basic method for imaging malignant pelvic tumors. MR imaging at 0.02 T magnetic field provides a convenient and inexpensive method for more specific information, if CT findings are equivocal. MRI at 0.02 T is also accurate in detecting benign pelvic masses, but the findings are not very specific.

Gynecologic magnetic resonance imaging

Magnetic resonance imaging (MRI) is an excellent modality with which to delineate normal anatomic structures and a variety of pathologic conditions in the female pelvis. It excels at demonstrating the extent of local tumor involvement in cases of endometrial and cervical cancer. It can help to elucidate the origin and nature of a variety of benign pelvic masses in cases where ultrasound findings are equivocal, and it is an accurate tool in demonstrating congenital abnormalities of the female reproductive tract. As technology continues to evolve, MRI will likely assume an even greater role in evaluating the female pelvis.

MRI of female uterine and juxta-uterine masses: clinical application in 25 patients

The clinical utility of magnetic resonance imaging (MRI) in the diagnosis of gynecologic masses was evaluated in 25 patients. In each patient the final pathologic diagnosis was semiquantitatively correlated with the diagnostic impressions from pelvic examination, ultrasound and MRI. There were 9 uterine, 11 ovarian and 5 nonovarian pelvic masses. Pelvic examination correlation with final diagnosis was 26%, consistent with the literature. Ultrasound fared surprisingly poorly, with only 44% correlation. MRI showed an 87% correlation with the final diagnosis. MRI was able to accurately identify masses, discriminate adnexal masses from fluid-filled bowel, identify dermoids, and in one case obviated surgery in a pregnant patient. MRI provided significant clinical management information with greater accuracy than did ultrasound or pelvic examination.

Magnetic resonance imaging as an adjunct to sonography in the evaluation of the female pelvis

Magnetic resonance imaging (MRI) of the pelvis is generally considered to be most beneficial in those cases where the pelvic sonogram is limited or equivocal. All cases that underwent both sonographic and MRI examinations at our institution for the evaluation of the female pelvis in the past two years were retrospectively reviewed. We reviewed the sonographic and MRI reports and the subsequent clinical management in the 41 cases that had both studies to assess whether MRI contributed to the clinical management decision. Both studies were interpreted independently based upon the known clinical and laboratory data available at the time. MRI was obtained in 21 cases because the sonogram was suboptimal or inconclusive. In the other 20 cases it was obtained for additional information, even though the sonogram was diagnostic. Of the 21 inconclusive sonographic studies, MRI established or clarified the diagnosis in all cases. Of the 20 studies where MRI was obtained for additional information, MRI added useful data that helped contribute to the clinical management of 11 patients. MRI is an important adjunct to pelvic sonography. It established, clarified, or added significant data in 78% of cases.