Value of fetal cerebral MRI in sonographically proven cardiac rhabdomyoma.

BACKGROUND: Tuberous sclerosis complex (TSC) is an autosomal dominant phakomatosis associated with intracardiac rhabdomyomas. OBJECTIVE: The aim of our study was to examine the value of cerebral MRI in diagnosing TSC in fetuses with intracardiac rhabdomyomas, applying the TSC Consensus Conference (TSCCC) criteria. MATERIALS AND METHODS: In a prospective manner six consecutive fetuses with cardiac rhabdomyomas (21-34 weeks' gestation) underwent cerebral MRI. The MRI results were correlated with clinical follow-up at 10-34 months after birth, histology, and genetic data. RESULTS: In five of the six fetuses the diagnosis of TSC was established. In two of five fetuses MRI demonstrated cerebral manifestations of TSC that correlated well with severe epilepsy manifesting during the follow-up period. In another two of five fetuses MRI as well as clinical follow-up were normal. One of five pregnancies was terminated and histology demonstrated microscopically small subependymal nodules not demonstrated by MRI. CONCLUSION: The results of our study agree with the available literature that fetal MRI is sufficient for the detection of cerebral lesions in TSC and should be better promoted. The TSCCC criteria can also be applied to fetal MRI.

MRI of cardiac rhabdomyoma in the fetus.

Primary cardiac tumors are rarely diagnosed in utero and are usually seen on prenatal echocardiography. Cardiac rhabdomyomata can be associated with tuberous sclerosis. Prenatal MRI can be performed to assess associated malformations. This case report illustrates the ability of fetal MRI to image cardiac rhabdomyata and compares it with prenatal and postnatal echocardiography.

Pelvimetry and patient acceptability compared between open 0.5-T and closed 1.5-T MR systems.

Our objective was to compare maternal pelvimetry and patient acceptability between open low-field (0.5-T) and closed 1.5-T MR systems. Thirty women referred for pelvimetry (pregnant: n=15) were scanned twice in the supine position, once in the vertical open system and once in the closed system. Each patient completed a comfort and acceptability questionnaire. Pelvimetric and questionnaire data were compared between systems. Total scan time was double in the open system (7:52+/-1:47 vs 3:12+/-1:20 min). Poor image quality in the open system prevented assessment of interspinous and intertuberous diameters in one woman and all measurements in another, both pregnant, with abdominal circumferences >120 cm. The open system was much more acceptable in terms of claustrophobia and confinement (both p<0.01). Claustrophobia interrupted one closed examination. Thirty-three percent of pregnant women in both systems reported fear of fetal harm. Sixty percent of all women preferred the open system, 7% the closed system, and 33% had no preference. Limits of agreement of 3-5% from the mean for all diameters confirmed good pelvimetric reproducibility. Women's preference for open-system MR pelvimetry is feasible with abdominal circumferences

MR obstetric pelvimetry: effect of birthing position on pelvic bony dimensions.

OBJECTIVE: The aim of our study was to measure the impact of supine and upright birthing positions on MR pelvimetric dimensions. MATERIALS AND METHODS: MR pelvimetry was performed in 35 nonpregnant female volunteers in an open 0.5-T MR imaging system with patients in the supine, hand-to-knee, and squatting positions. The obstetric conjugate; sagittal outlet; and interspinous, intertuberous, and transverse diameters were compared among positions. RESULTS: With patients in the hand-to-knee and squatting positions, the sagittal outlet (11.8 +/- 1.3 cm and 11.7 +/- 1.3 cm) exceeded that in the supine position (11.5 +/- 1.3 cm; p = 0.002 and p = 0.01, respectively), as did the interspinous diameter (11.6 +/- 1.1 cm and 11.7 +/- 1.0 cm vs 11.0 +/- 0.7 cm; p < 0.0001, in both cases). Intertuberous diameter was wider with patients in the squatting position than in the supine position (12.7 +/- 0.8 cm vs 12.4 +/- 1.1 cm; p = 0.01). Only the obstetric conjugate was smaller with patients in the upright squatting position than in the supine position (12.3 +/- 0.8 cm vs 12.4 +/- 0.9 cm; p = 0.01). Transverse diameter did not change significantly in any position. CONCLUSION: An upright birthing position significantly expands female pelvic bony dimensions, suggesting facilitation of labor and delivery.

Original report. Fetal cardiographic monitoring during 1.5-T MR imaging.

OBJECTIVE: The aim of this report was to determine the feasibility of fetal cardiotocography during MR imaging and the safety of 1.5-T MR imaging on the basis of fetal heart activity and fetal movements. CONCLUSION: Fetal cardiotocography is feasible during MR imaging using modified standard equipment. The use of 1.5-T MR imaging appears to be safe and to have no negative short-term effects on the heart rate or movement incidence of healthy third-trimester fetuses under our experimental conditions.

Obstetric MR pelvimetry: reference values and evaluation of inter- and intraobserver error and intraindividual variability.

PURPOSE: To establish obstetric magnetic resonance (MR) pelvimetric reference values in a large study population and stratify them according to delivery modality and to determine the intra- and interobserver error and intraindividual variability of MR pelvimetric assessment in volunteers. MATERIALS AND METHODS: MR pelvimetric data were retrospectively reviewed in 781 women (mean age, 28.9 years +/- 5.2 [SD]) clinically referred, and the data were correlated to obstetric history to derive normative values. Five observers assessed results of multiple MR pelvimetric examinations in 10 female volunteers (mean age, 34.7 years +/- 6.0; eight nullipara, two primipara) to provide data for measurement error analysis. RESULTS: All values were higher in the spontaneous vaginal delivery subgroup (n = 100) and lower in the cesarean section or vacuum extraction subgroup (n = 130; intersubgroup difference, P <.001, Mann-Whitney U test). Pelvimetric parameters in the group undergoing spontaneous vaginal delivery were as follows: obstetric conjugate, 121.7 mm +/- 8.6; interspinous distance, 112.3 mm +/- 7.9; intertuberous distance, 120.6 mm +/- 11.3; transverse diameter, 129.5 mm +/- 8.7; and sagittal outlet, 115.8 mm +/- 9.9. In the volunteer study, intraobserver, interobserver, and intraindividual reliabilities were high for the obstetric conjugate (0.94-0.96), interspinous distance (0.92-0.95), and transverse diameter (0.95-0.98) but low for intertuberous distance (0.64-0.87) and sagittal outlet (0.66-0.85). CONCLUSION: Pelvimetric dimensions are smaller in women undergoing cesarean section or vacuum extraction than they are in those delivering vaginally. The pelvimetric parameters associated with the largest measurement errors are intertuberous distance and sagittal outlet.

MR assessment of fetal lung development using lung volumes and signal intensities.

The purpose of this study was to evaluate the monitoring and diagnostic potential of MRI in fetal lung development and disease using lung volume and signal intensity changes through gestation. Thirty-five healthy fetuses (22-42 weeks) were examined on a 1.5- T MR system using sagittal T2w single-shot fast spin-echo imaging (TR indefinite, TE 90 ms, slice thickness/gap 3-5/0 mm, FOV 26-40 cm, NEX 0.5). Fetal body and lung were segmented manually and volumes calculated. Signal intensities (SI) of fetal lung and three reference values were measured on the section best displaying the lung. Regions of interests were defined by including the maximal organ area possible. The following SI ratios were generated: lung/liver, lung/amniotic fluid, lung/muscle, liver/fluid and liver/muscle. Volumes and ratios were correlated with gestational age. Data from seven fetuses with pulmonary pathology were compared with these normative values. Absolute lung volume varied from 12.3 to 143.5 cm(3) in correlation with gestational age ( P<0.001); lung volume relative to total body volume ranged from 1.6 to 5.0%, decreasing with gestational age ( P=0.001). All SI ratios measured were unrelated to gestational age. Diagnoses in the seven abnormal fetuses were hydrothorax ( n=2), congenital cystic adenomatoid malformation ( n=2), diaphragmatic hernia ( n=2) and pulmonary sequestration ( n=1); their absolute and relative lung volumes were below normal ( P<0.001). The SI ratios did not differ significantly from those in the normal population. Normative MR fetal lung volumes may have important clinical applications in confirming and quantifying intrauterine pulmonary hypoplasia and in complementing ultrasound in the planning of fetal and post-natal surgery. No clinical relevance was found for fetal lung SI values.