The uterus: in vitro MR-anatomic correlation of normal and abnormal specimens

Characteristics of bladder leiomyoma as noted on magnetic resonance imaging

Leiomyoma of the bladder is a rare benign mesenchymal tumor that can be evaluated preoperatively with magnetic resonance imaging. Small tumors that appear to be leiomyomas on magnetic resonance imaging can be treated conservatively with transurethral resection.

T2-weighted MR imaging of the uterus: comparison of optimized fast spin-echo and HASTE sequences with conventional fast spin-echo sequences

OBJECTIVE

Our objective was to compare the value of a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence with optimized fast spin-echo and conventional fast spin-echo techniques in evaluation of the uterus.

SUBJECTS AND METHODS

Optimized fast spin-echo imaging was compared with fast spin-echo and HASTE imaging, for both image quality and ability to assess the zonal anatomy of the uterus, in 40 volunteers. In optimized fast spin-echo imaging, the imaging time was reduced using partial-Fourier reconstruction, reducing the echo spacing, and increasing the echo train length.

RESULTS

HASTE imaging offered the least motion artifact of all techniques. On optimized fast spin-echo imaging, motion artifacts were moderate to severe in 10% of patients. On fast spin-echo imaging, motion artifacts were moderate to severe in 40% of patients. Optimized fast spin-echo imaging was superior to the other two techniques in terms of anatomic sharpness and overall image quality.

CONCLUSION

Although HASTE imaging offers the unique feature of providing images free of motion artifacts, optimized fast spin-echo imaging appears to be the preferred technique for T2-weighted imaging of the uterus.

Compression of large uterine myoma by sacral promontory: MR findings

We present the MR findings of three cases of large uterine myomas that had geographically nonenhancing areas that were compressed by the sacral promontory. These nonenhancing areas on contrast-enhanced T1-weighted images showed no abnormal signal intensity on T2-weighted images. On delayed images following contrast medium administration, the nonenhancing area eventually enhanced homogeneously. There was no evidence of degeneration at pathologic examination. We think that the sacral promontory may compress large myomas with vascular insufficiency, resulting in delayed contrast enhancement of that area.

Biochemical heterogeneity in hysterectomized uterus measured by 31P NMR using SLIM localization

Ultrasound and magnetic resonance imaging show contrast between the inner and outer myometrium, which is useful in the diagnosis of gynecological disorders. To determine whether the image contrast is associated with biochemical differences between these myometrial regions, phosphorus metabolite concentrations in the inner one third of the myometrium (the junctional zone; JZ) were compared with the outermost one third of the myometrium (OM) in hysterectomized uteri using 31P spectral localization by imaging (SLIM). The technique was validated by comparing the results of SLIM with the results of standard Fourier-encoded spectroscopic imaging (FSI) analysis using phantoms, and by nonlocalized spectroscopy on biopsies taken from the same hysterectomy specimens. As expected theoretically, SLIM yielded better localization than FSI, as judged by spectral intensity and leakage measurements on phantom compartments of known composition. SLIM localization revealed that the JZ has a higher intracellular phosphomonoester (PME) concentration than does the OM, which was confirmed by nonlocalized spectroscopy, and that there is very little NMR-visible phosphorus in the cervix.

Conspicuity of normal and pathologic female pelvic anatomy: comparison of gadolinium-enhanced T1-weighted images and fast spin echo T2-weighted images

PURPOSE

Our goal was to compare the conspicuity of normal and pathologic female pelvic anatomy between gadolinium-enhanced T1-weighted images and fast SE (FSE) T2-weighted images.

METHOD

In 48 consecutive female patients, pre- and postenhanced T1-weighted images were compared with FSE T2-weighted images acquired with a phased array coil. Normal zonal anatomy (ZA) and pathologic abnormalities in gadolinium-enhanced T1-weighted images were rated as increased, decreased, or without change in conspicuity as compared with FSE T2-weighted images.

RESULTS

The normal ZA of the uterine corpus on T1-weighted images showed a decrease in conspicuity in 93% of patients and an increase in 7% compared with FSE T2-weighted images. Conspicuity of cervical ZA on T1-weighted images was decreased in 86%, increased in 6%, and without change in 8% as compared with FSE T2-weighted images. ZA of the vagina on T1-weighted images was decreased in 94% and increased in 6% as compared with FSE T2-weighted images. On T1-weighted images, ovarian anatomy delineation was decreased in 95% and increased in 5% as compared with FSE T2-weighted images. Conspicuity of malignant pathologic abnormalities on T1-weighted images was decreased in 81%, increased in 11%, and without change in 8% as compared with FSE T2-weighted images. In patients with benign disease, conspicuity on T1-weighted images was decreased in 92%, increased in none, and without change in 8% as compared with FSE T2-weighted images. The p value for all categories was < 0.0001.

CONCLUSION

Conspicuity of both normal and pathologic anatomy was significantly decreased on enhanced T1-weighted images. The use of gadolinium cannot replace T2-weighted scans for delineation of anatomy and disease and should be reserved to cases in which standard imaging sequences are not sufficiently diagnostic.

Quantitative MRI of uterine leiomyomas during triptorelin treatment: reproducibility of volume assessment and predictability of treatment response

Magnetic resonance (MR) imaging is increasingly applied for the quantitative evaluation of uterine leiomyomas. MR is thought to be more accurate in comparison to ultrasound (US) techniques. MR signal intensity (SI) may prove to be predictive of myoma response to GnRH agonist treatment. This study aimed to evaluate the precision of uterine volume assessment by a parallel planimetric MR method and the accuracy of the ellipsoid formula based calculations from MR and US images. It was also attempted to analyze the precision of MR leiomyoma volume measurements and examine the relation between pretreatment myoma SI patterns and the response to agonist therapy. Twenty-seven women with a myomatous uterus were scanned three times during GnRH agonist treatment for 6 months. T1- and T2-weighted, as well as T1 contrast-enhanced sequences of the uterus were obtained in the transverse and sagittal plane. Abdominal US of the uterus was performed with a conventional sector scanner. By the use of a software system for analysis of three-dimensional images obtained by MR, uterine volume was measured by a parallel planimetric method (MR-ROI) as well as the use of the ellipsoid formula (MR-ELL). Myoma volume was assessed by the MR-ROI method. SI of the myomas was estimated from selected tissue samples as well as from the integral myoma region of interest. By abdominal US, volume was assessed by the ellipsoid equation (US-ELL). Within- and between-observer and method reliability (Rw/Rb) was calculated from mean squares obtained by analysis of variance. For uterine volume assessment, reliability between observers and between methods when the MR-ROI and MR-ELL methods were analyzed was excellent. For the US-ELL measurements, the between-observer reliability was limited. Moreover, the reliability of the US-ELL was low when the MR-ROI method was used as the standard. Myoma volume assessment with the MR-ROI method showed high between-observer and between-method agreement. The myoma/fat SI ratio and the mean SI coefficient of variation failed to show a correlation with the degree of response to triptorelin treatment of individual myomas. In MR uterine volume assessment the MR-ELL method is very accurate compared with the more complicated MR-ROI method. The agreement between MR and US is limited. Therefore, the ellipsoid method on MR images is to be regarded as the method of choice for quantitative assessment of uterine volume response to hormonal treatment. Myoma SI patterns were shown to be of no value in the response prediction of myomas to treatment with GnRH agonists.

Prediction of histopathologic features and proliferative activity of uterine leiomyoma by magnetic resonance imaging prior to GnRH analogue therapy: correlation between T2-weighted images and effect of GnRH analogue

To predict the histological features and proliferative activity of leiomyomas and to evaluate the effect of GnRH analogues (GnRHa) by MR images, the correlation between MR images and histopathologic findings was studied on 137 leiomyomatous nodules from 79 patients. The correlation among cellularity, proliferative activity and MR images was studied on sections of 42 leiomyomatous, nodules stained with hematoxylin-eosin and immunohistochemistry for proliferating cell nuclear antigen. The utility of MR imaging in assessing response to therapy with a GnRHa (buserelin 900 micrograms/day, intranasal for 16 weeks) was studied on 62 leiomyomatous nodules from 29 patients. On T2-weighted MR images, we encountered five major images. According to the increase of signal intensity relative to that of the myometrium and/or the endometrium, the images were classified as Type 1, Type 2, Type 3, Type 4, and Type 5. Histopathologically, the majority of Type 1, Type 2 and Type 3 images had features of typical leiomyoma. Almost all cellular leiomyomas and bizarre leiomyomas had Type 4 images. Variable degenerative features were observed in the nodules with Type 5 images. According to the increase of signal intensity, leiomyomas had a tendency to show a high degree of both cellularity and proliferative activity. Moreover, the reduction rate of leiomyomatous nodules after GnRHa therapy correlated with the tumor signal intensity on T2-weighted images before therapy. The reduction rate was the lowest in Type 1 images (20.9%) and the highest in Type 4 images (50.7%). These results suggest that increased the signal intensity on T2-weighted MR images correlates with the cellularity and proliferative activity of leiomyomas, and with tumor response to GnRHa treatment. MR imaging enables quantitative monitoring of GnRHa therapy in patients with leiomyomatous nodules, and allows us to predict the histopathology, cellularity, proliferative activity, and shrinkage rate of nodules before GnRHa treatment.

The value of MRI in the assessment of traumatic intra-uterine adhesions (Asherman's syndrome)

Since the publication titled Amenorrhea Traumatica (atretica) by Asherman in 1948, this syndrome has been considered a well defined clinical entity. It is typically manifested by the formation of fibrous adhesions involving the uterine cavity, sometimes involving the internal cervical os. The major causes are surgical intervention of the post-partum uterus and elective termination of early pregnancy. The diagnosis is usually suggested by hysterography and confirmed by hysteroscopy. The MRI appearances are reported in four cases of Asherman's Syndrome in which the diagnosis was confirmed by hysteroscopy. The full range of MRI appearances in Asherman's Syndrome has not been established and to our knowledge there has been only one case reported in the literature.

MR evaluation of cervical cancer in hysterectomy specimens: correlation of quantitative T2 measurement and histology

Specimens from modified radical hysterectomies performed for invasive carcinoma of the cervix were analyzed with quantitative T2 magnetic resonance (MR) imaging and histologic study to determine to what degree there was a correlation between the findings of the two modalities. The mean T2 of cervical stroma was 48 msec, while the outer zone of the cervix had a mean T2 of 62 msec and the central canal region typically had T2 values of 115 msec +/- 20 (standard deviation). A total of nine cervical cancers were analyzed, and their mean T2 value was 79 msec. Separation between cervical stroma and tumor was good, with stromal T2 values ranging from 30 to 66 msec, while tumor T2s ranged from 60 to 97 msec. Statistical analysis indicated that these data were associated with a sensitivity of 89% and a specificity of 95%, with 95% confidence intervals of [50%, 99.4%] and [74%, 99.7%], respectively, for separating tumor from stroma on the basis of T2 value. Quantitative T2 imaging was found to provide an effective, nonsubjective means of classifying cervical anatomy and neoplastic disease.

Magnetic resonance imaging of the uterus in vivo and in vitro at an ultra low magnetic field (0.02 T): assessment of its normal structure and of leiomyomas

The purpose of this investigation was to analyze the normal anatomy and leiomyomas of the uterus with an ultra low field (0.02 T) magnetic resonance imaging (MRI) device. MR imaging was performed on 18 uteri, 11 of which were imaged both preoperatively (in vivo) and as an operative specimen (in vitro), 6 only as an operative specimen, and 1 only preoperatively. All uteri were examined histologically after imaging. The junctional zone was much better delineated in vivo than in vitro, indicating that its appearance on MR is partly due to blood flow. No structures contributing to its visibility in vitro could be demonstrated histologically. Twenty leiomyomas (size range 7-79 mm) in 12 uteri were found with MRI. They were slightly better discerned in vivo than in vitro. The leiomyomas, having no degenerative changes, had a signal intensity which was the same or lower than that of the myometrium. On images obtained in vitro the signal intensity of these leiomyomas relative to that of myometrium correlated directly with their muscular content (R = 0.74, p = .002). The authors conclude that the junctional zone is a sum of physiological and structural factors, the latter being responsible for its in vitro delineation. MR imaging of the uterus in vitro did not give more information than MR imaging in vivo. All leiomyomas larger than 10 mm could be detected, indicating that MR imaging at 0.02 T is an accurate method for the imaging of the uterine leiomyomas.

Uterine contractions: possible diagnostic pitfall at MR imaging

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent-enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.

Imaging of uterovaginal anomalies in the pediatric patient

Uterovaginal anomalies are relatively common congenital disorders whose diagnosis at a young age is important but often difficult. The various modalities currently employed for this evaluation are discussed, including MRI, the most recent available tool. The embryology of female reproductive tract anomalies is included.

The normal uterus on magnetic resonance imaging and variations associated with the hormonal state

Magnetic Resonance Imaging of the pelvis has lead to a new radioanatomical description of the uterus. Variations in the anatomical zones of the uterus were noted with different sequences used in MRI. There was also structural and signal variation depending on hormonal impregnation. Twenty seven MRIs of pelvices were carried out on 16 female volunteers. Eight of them were on oestroprogesterone as the method of contraception (Group I) and had a single MRI. Six were not taking contraceptives (Group II) and had different MRI's during the same cycle. Two women already had already gone through the menopause (Group III). Results showed differences in the size of the uterus (uterine height, length of the uterine body and cervix, diameter of the cervix) between groups I and II but no cyclic changes were observed within group II. The myometrium was found to be thicker in group I and in the luteal phase of group II females in comparison to the follicular phase in the same group. The endometrial cavity was seen in 40% of cases on T1 weighted sequences; on T2 weighted sequences it was seen in all the cases. It was thicker during the second phase in group II than in group I and III. The myometrial signal compared to that of the bladder content (urine) showed a significant increase between early and late echoes on T2 weighted sequences in group I and during the second phase of the menstrual cycle in group II. No variations, or at times a decrease in signal, were observed during the first phase of the cycle in group II.(ABSTRACT TRUNCATED AT 250 WORDS)

Oblique NMR imaging of the uterus in macaques: uterine response to estrogen stimulation

We report methods for quantitative NMR imaging of the primate uterus and the application of these methods of measuring the response of the monkey (Macaca nemestrina) uterus (endometrial volume, myometrial volume, T2 values, myometrial junction zone) to estrogen stimulation. High-field (2.35 T), fat-suppressed, T2-weighted (TE50) oblique methods were used. Slice thickness, location, and angle were varied on each examination to obtain six contiguous slices between the cervix and fundus, regardless of size or orientation of the uterus. Basal endometrial and myometrial volumes were 0.05 +/- 0.01 cm3 and 1.31 +/- 0.23 cm3 in chronically ovariectomized animals. These increased by 15.7 +/- 3.6-fold and 3.1 +/- 0.4-fold, respectively, during 7 days of estrogen stimulation (estradiol benzoate, 5 micrograms/kg sc daily) while myometrial T2 increased from 52 +/- 1 to 67 +/- 4 ms. These changes reversed following menstrual bleeding.

Primary lymphoma of the cervix: MRI findings with gadolinium

MRI evaluation of primary cervical lymphoma has not been reported. We report such a case of primary cervical lymphoma, a lesion well seen and well delineated from normal tissue by MRI. Although primary lymphoma of the cervix is a rare entity, the disease does exist and can be well demonstrated by MRI. We evaluated the MR appearance of this lesion with both nonenhanced and gadolinium-enhanced imaging.

Contractions of the inner third of the myometrium

Forty-six consecutive endovaginal ultrasound examinations were screened for the presence of myometrial contractions. The study group contained pregnant women up to 10 weeks' menstrual age, nonpregnant, and postmenopausal women. Rhythmic myometrial contractions of the inner myometrial third not previously reported were seen in 35 studies in pregnant, nonpregnant, and postmenopausal women. The contractions involved the inner third of the myometrium in all but two cases. In these two cases, all three muscular layers were involved. The majority of women showed retrograde contractions, with the contraction wave moving from the cervix to the fundus. In menstruating women and one case of abortion, the contractions were antegrade. It is our speculation that these retrograde contractions of the inner myometrial third may be important in sperm transport and for the conservation of early pregnancies within the uterine cavity.

Correlation of ultrasound findings and endometrial histopathology in postmenopausal women

Comparison of ultrasound scan and histology of the endometrium was made in 90 postmenopausal women. Of these, 63 women had postmenopausal bleeding (group A) and 27 had had no bleeding (group B). Sensitivity of ultrasound to diagnose endometrial pathology was 91%, and all endometrial carcinomas, hyperplasias and pyometra were diagnosed by ultrasound. In 10 premenopausal women (group C), who had a hysterectomy for cervical intraepithelial neoplasia, the ultrasound measurements of the endometrial wall thickness were within 1 mm of the actual thickness, as measured in the fresh unfixed specimen with a ruler. This preliminary study has shown that a normal ultrasound appearance of the endometrium in postmenopausal women reliably excludes significant endometrial pathology. Also, changes in the thickness and texture of the endometrium detected by ultrasound correlated with subsequent pathological findings.

Modifications of relaxation times induced by radiation therapy in cervical carcinoma: preliminary results

Pelvic Magnetic Resonance Imaging (MRI) was performed in eight healthy women and in eight patients with carcinoma of the cervix, using a 0.5 T superconductive magnet, to evaluate relaxation times of the normal uterine cervix and carcinomas. Spin-lattice (T1) and spin-spin (T2) relaxation times for skeletal muscle, adipose tissue and bone marrow of the epiphysis of the femur were also measured in all cases. In the group of patients with carcinoma of the cervix MRI was performed before, during and after radiation therapy. The mean T1 and T2 values for the normal uterine cervix and cervical carcinoma were evaluated. Mean spin-lattice time for carcinomas were confirmed to be higher than the mean calculated value for the normal cervix, while no significant variation was observed with respect to spin-spin time. A high individual T1 and T2 variability was noted not only in the group of patients affected by cervical carcinoma, but among the healthy subjects too. After radiation therapy a mean T1 time reduction of approximately 20% was found in cervical carcinomas compared with pretreatment measurements, whereas no difference was evident for T2 time. These preliminary results confirm that reduction in spin-lattice time is demonstrated in tumours submitted to radiation therapy. More detailed biological information, such as percentages of vital and necrotic cells, tissue water content and cellular kinetics are probably necessary for a clearer understanding of this phenomenon even in an apparently homogeneous group of patients.

Magnetic resonance imaging of gynecologic masses

The pelvis of 21 women with various gynecological masses were imaged with magnetic resonance (MR) imagers at 2.0 and 0.5 T. Fifteen normal individuals were used for studying the normal appearance of the female genitalia using spin echo pulse sequences with various pulse repetition (TR) and spin echo (TE) time values. Images were compared with those of the ultrasonic images, intraoperative findings, and the histopathologic examinations. The masses included simple ovarian cyst, cystadenoma, serous cystadenocarcinoma, ovarian teratoma, dysgerminoma, and uterine myoma. MR imaging was useful in demonstrating the anatomy and pathology of the cases examined in this study. It detected the internal structure of some tumors which were sonographically homogeneous. The potential of MR in staging of malignancies was demonstrated.

Magnetic resonance imaging and histopathology in femoral head necrosis

We correlated preoperative magnetic resonance (MR) images and histopathology of eight femoral heads from patients with osteonecrosis. The signal intensity of the MR image was low in the area where fibrovascular tissue, disintegrated fibrovascular tissue, or amorphous necrotic material occupied the medullary space. On the other hand, the necrotic marrow without revascularization showed high signal intensity. Osteonecrosis can be detected by MR imaging as soon as a certain amount of bone marrow is replaced by fibrovascular tissue.

MRI in staging of endometrial and cervical carcinoma

MRI of 54 patients with endometrial and cervical carcinoma was performed on a 0.6-T superconducting magnet. In 18 of 24 cases of surgically proved endometrial carcinoma, MRI accurately showed the depth of myometrial invasion. MRI was superior to CT scan for defining the primary site and extent of the tumor in 14 of 24 cases. Of 25 patients with cervical carcinoma studied, MRI was superior to CT scan in 15 of 19 cases with CT correlation for localizing the primary site. MRI showed parametrial extension and invasion of surrounding structures but is probably less reliable than CT scan for detection of adenopathy because of false positive findings from volume averaging with bowel.

The value of MRI in evaluating perirectal and pelvic disease

MRI of the perirectal region is facilitated by the superb soft tissue contrast, multiplanar imaging capability, lack of respiratory motion artifact and absence of clip artifact which can hamper visualization by CT scan. MRI provides distinct advantages over CT scanning without the need for ionizing radiation or the injection of intravenous contrast material. This study reviews the findings in 18 consecutive patients with a variety of perirectal pathologies including rectal carcinoma (3), gynecologic neoplasm (8), sacral lesions (2), pelvic arteriovenous malformations (2), inflammatory bowel disease (2), and a pelvic kidney (1). In the perirectal region, MR was useful to show normal tissue planes, benign processes which can mimic neoplasm, intrapelvic extension of malignancy and adenopathy.

Magnetic resonance imaging of the female pelvis

Magnetic resonance (MR) imaging is particularly well suited for the evaluation of the female pelvis because of the lack of respiratory motion and the multiplanar imaging ability of MR. The MR appearance of normal anatomy is dependent on the pulse sequence used. This is also true for pelvic pathology. Primary cervical carcinoma is best seen on T2-weighted images; parametrial extension and lymph node metastases are best evaluated on T1-weighted images. Endometrial carcinoma is also best seen on T2-weighted images. Absence of the junctional low intensity band of the uterus may indicate myometrial invasion by endometrial tumor, although more data are needed to make a final diagnosis. Uterine leiomyomata have a variable MR appearance which may be related to the degree of cellularity of the tumor. Our experience in the MR appearance of adnexal masses is limited. MR imaging should assume a more important role in imaging the female pelvis in the future.

Gynecologic anatomy with magnetic resonance imaging

Magnetic resonance imaging demonstrates gynecologic anatomy not visible with other techniques. Tissue layers within and outside the uterine corpus, cervix, and vagina are defined in any plane. Such soft tissue contrast resolution is promising for the noninvasive diagnosis of disease.