Comparative anatomy on 3-D MRI of the urogenital sinus and the periurethral area before and during the second stage of labor during childbirth.

PURPOSE OF THE STUDY: To describe the observable MRI changes in the urogenital sinus during the second stage of labor and delivery by comparing the changes in the positions of the anatomical structures of the maternal perineum using MRI-based vector 3-D models. MATERIALS AND METHODS: Seven pregnant women underwent 3-D MRI sequences using a Philips 1 T Panorama open MRI during the pre-labor period and during the second stage of labor. A 3-D vector reconstruction platform (BABYPROGRESS, France) enabled the transformation of volumes of 2-D images into finite element meshes. The polygonal meshes labeled with the principal components of the urogenital sinus were used as part of a biomechanical study of the pressure exerted on the perineum during fetal descent. RESULTS: The expansion of the urogenital sinus was observed in all patients. Qualitative stretching was observed toward the rear and bottom of the iliococcygeus, pubococcygeus, puborectalis and obturator internus muscles. Significant length differences were measured along the iliococcygeus and pubococcygeus muscles but not along the tendinous arch of the levator ani or the puborectalis muscle. The inversion of the levator ani muscle curvature was accompanied by the transmission of pressure generated during fetal descent to the pubic muscle insertions and the descent of the tendinous arch of the levator ani. CONCLUSION: Mechanical pressures responsible for the tensioning of the constituent muscles of the urogenital sinus were qualitatively identified during the second stage of labor. MRI-based vector 3-D models allow the quantitative assessment of levator ani muscle stretching during labor, but 2-D MRI is not sufficient for describing perineal expansion. Vector 3-D models from larger scale studies have the potential to aid in the calibration of a realistic simulation based on the consideration of the reaction of each muscular element. These models offer perspectives to enhance our knowledge regarding perineal expansion during childbirth as a risk factor for postpartum perineal defects.

Using Magnetic Resonance Imaging During Childbirth to Demonstrate Fetal Head Moldability and Brain Compression: Prospective Cohort Study.

BACKGROUND: Childbirth is a physiological process with significant medical risk, given that neurological impairment due to the birthing process can occur at any time. Improvements in risk assessment and anticipatory interventions are constantly needed; however, the birthing process is difficult to assess using simple imaging technology because the maternal bony pelvis and fetal skeleton interfere with visualizing the soft tissues. Magnetic resonance imaging (MRI) is a noninvasive technique with no ionizing radiation that can monitor the biomechanics of the birthing process. However, the effective use of this modality requires teamwork and the implementation of the appropriate safeguards to achieve appropriate safety levels. OBJECTIVE: This study describes a clinically effective and safe method to perform real-time MRI during the birthing process. We reported the experience of our team as part of the IMAGINAITRE study protocol (France), which aimed to better understand the biomechanics of childbirth. METHODS: A total of 27 pregnant women were examined with 3D MRI sequences before going into labor using a 1-Tesla open-field MRI. Of these 27 patients, 7 (26%) subsequently had another set of 3D MRI sequences during the second stage of labor. Volumes of 2D images were transformed into finite element 3D reconstructions. Polygonal meshes for each part of the fetal body were used to study fetal head moldability and brain compression. RESULTS: All 7 observed babies showed a sugarloaf skull deformity and brain compression at the middle strait. The fetus showing the greatest degree of molding and brain shape deformation weighed 4525 g and was born spontaneously but also presented with a low Apgar score. In this case, observable brain shape deformation demonstrated that brain compression had occurred, and it was not necessarily well tolerated by the fetus. Depending on fetal head moldability, these observations suggest that cephalopelvic disproportion can result in either obstructed labor or major fetal head molding with brain compression. CONCLUSIONS: This study suggests the presence of skull moldability as a confounding factor explaining why MRI, even with the best precision to measure radiological landmarks, fails to accurately predict the modality of childbirth. This introduces the fetal head compliance criterion as a way to better understand cephalopelvic disproportion mechanisms in obstetrics. MRI might be the best imaging technology by which to explore all combined aspects of cephalopelvic disproportion and achieve a better understanding of the underlying mechanisms of fetal head molding and moldability.

Three-dimensional magnetic resonance imaging of fetal head molding and brain shape changes during the second stage of labor.

To demonstrate and describe fetal head molding and brain shape changes during delivery, we used three-dimensional (3D) magnetic resonance imaging (MRI) and 3D finite element mesh reconstructions to compare the fetal head between prelabor and the second stage of labor. A total of 27 pregnant women were examined with 3D MRI sequences before going into labor using a 1 Tesla open field MRI. Seven of these patients subsequently had another set of 3D MRI sequences during the second stage of labor. Volumes of 2D images were transformed into finite element 3D reconstructions. Polygonal meshes for each part of the fetal body were used to study fetal head molding and brain shape changes. Varying degrees of fetal head molding were present in the infants of all seven patients studied during the second phase of labor compared with the images acquired before birth. The cranial deformation, however, was no longer observed after birth in five out of the seven newborns, whose post-natal cranial parameters were identical to those measured before delivery. The changing shape of the fetal brain following the molding process and constraints on the brain tissue were observed in all the fetuses. Of the three fetuses presenting the greatest molding of the skull bones and brain shape deformation, two were delivered by cesarean-section (one after a forceps failure and one for engagement default), while the fetus presenting with the greatest skull molding and brain shape deformation was born physiologically. This study demonstrates the value of 3D MRI study with 3D finite element mesh reconstruction during the second stage of labor to reveal how the fetal brain is impacted by the molding of the cranial bones. Fetal head molding was systematically observed when the fetal head was engaged between the superior pelvic strait and the middle brim.

Pulmonary veno-occlusive disease: clinical, functional, radiologic, and hemodynamic characteristics and outcome of 24 cases confirmed by histology.

Pulmonary veno-occlusive disease (PVOD) is defined by specific pathologic changes of the pulmonary veins. A definite diagnosis of PVOD thus requires a lung biopsy or pathologic examination of pulmonary explants or postmortem lung samples. However, lung biopsy is hazardous in patients with severe pulmonary hypertension, and there is a need for noninvasive diagnostic tools in this patient population. Patients with PVOD may be refractory to pulmonary arterial hypertension (PAH)-specific therapy and may even deteriorate with it. It is important to identify such patients as soon as possible, because they should be treated cautiously and considered for lung transplantation if eligible. High-resolution computed tomography of the chest can suggest PVOD in the setting of pulmonary hypertension when it shows nodular ground-glass opacities, septal lines, lymph node enlargement, and pleural effusion. Similarly, occult alveolar hemorrhage found on bronchoalveolar lavage in patients with pulmonary hypertension is associated with PVOD. We conducted the current study to identify additional clinical, functional, and hemodynamic characteristics of PVOD. We retrospectively reviewed 48 cases of severe pulmonary hypertension: 24 patients with histologic evidence of PVOD and 24 randomly selected patients with idiopathic, familial, or anorexigen-associated PAH and no evidence of PVOD after meticulous lung pathologic evaluation. We compared clinical and radiologic findings, pulmonary function, and hemodynamics at presentation, as well as outcomes after the initiation of PAH therapy in both groups. Compared to PAH, PVOD was characterized by a higher male:female ratio and higher tobacco exposure (p < 0.01). Clinical presentation was similar except for a lower body mass index (p < 0.02) in patients with PVOD. At baseline, PVOD patients had significantly lower partial pressure of arterial oxygen (PaO2), diffusing lung capacity of carbon monoxide/alveolar volume (DLCO/VA), and oxygen saturation nadir during the 6-minute walk test (all p < 0.01). Hemodynamic parameters showed a lower mean systemic arterial pressure (p < 0.01) and right atrial pressure (p < 0.05), but no difference in pulmonary capillary wedge pressure. Four bone morphogenetic protein receptor II (BMPR2) mutations have been previously described in PVOD patients; in the current study we describe 2 additional cases of BMPR2 mutation in PVOD. Computed tomography of the chest revealed nodular and ground-glass opacities, septal lines, and lymph node enlargement more frequently in patients with PVOD compared with patients with PAH (all p < 0.05). Among the 16 PVOD patients who received PAH-specific therapy, 7 (43.8%) developed pulmonary edema (mostly with continuous intravenous epoprostenol, but also with oral bosentan and oral calcium channel blockers) at a median of 9 days after treatment initiation. Acute vasodilator testing with nitric oxide and clinical, functional, or hemodynamic characteristics were not predictive of the subsequent occurrence of pulmonary edema on treatment. Clinical outcomes of PVOD patients were worse than those of PAH patients.

Effect of age on the performance of a diagnostic strategy based on clinical probability, spiral computed tomography and venous compression ultrasonography: the ESSEP study.

As the prevalence of PE increases with age, the effect of age on the diagnostic work-up in front of a clinical suspicion of PE deserves exploration. In this retrospective analysis, we used the data from 1041 consecutive suspected PE patients. The patients were divided into three groups according to tertiles of age: under 54 years, 54 to 73 years and above 73 years. The prevalence of PE in patients with respectively low, intermediate and high pretest clinical probability was expressed within each age group. We studied the effect of age on the results observed in three main groups of patients, after performing CT scan and ultrasonography (CUS): (1) patients with inconclusive results; (2) patients with negative findings on both exams and non high pretest clinical probability; (3) patients with positive findings.The prevalence of PE increased significantly with age, in overall, as well as in patients with low or intermediate pretest clinical probability. An analysis according to the three main diagnostic groups showed that: (1) the distribution of inconclusive spiral CT or CUS examinations was not different between age groups; (2) no thromboembolic event occurred in untreated patients with low or intermediate clinical probability aged under 54 years of age, whereas 7 events were diagnosed in patients aged over 73 years (p<0.001); (3) a higher proportion of older patients had a positive result at both spiral CT and CUS examinations. The percentage of positive CT scans in the case of negative or inconclusive CUS results was not different between age groups; conversely, in the case of a negative or inconclusive CT scan, the percentage of positive CUS was higher in older patients. In conclusion, management of elderly suspected PE patients appears to be different from both the work-up and the outcome perspectives.

Deep venous thrombosis in patients with acute pulmonary embolism: prevalence, risk factors, and clinical significance.

STUDY OBJECTIVES: To determine the prevalence of lower-limb deep venous thrombosis (DVT) that can be detected by compression ultrasonography (CUS) in patients with symptomatic pulmonary embolism (PE) diagnosed with spiral CT pulmonary angiography (CTPA); and to explore the risk factors for positive CUS results and the prognostic significance of such findings. DESIGN: Post hoc analysis of data from a prospective multicenter outcome study of 1,041 patients with clinically suspected non-severe PE. All patients underwent CTPA and CUS within 24 h of enrollment and were followed up for 3 months. PATIENTS: Among the 290 patients with positive CT findings, CUS was diagnostic in 281 patients who constitute the study population. RESULTS: Mean age +/- SD was 64.3 +/- 17.7 years; 128 patients (44.8%) were men. DVT signs or symptoms were present in 90 patients (32%). CUS detected DVT in 169 patients (60.1%; 95% confidence interval [CI], 54.1 to 65.9%), including 127 patients (45.2%; 95% CI, 39.3 to 51.2%) with proximal DVT. Sensitivity and specificity of DVT symptoms for CUS-detectable DVT were 43% and 85%, respectively. Multivariate analysis showed that an age > or = 70 years (odds ratio [OR], 1.90; 95% CI, 1.14 to 3.17) and the presence of DVT signs or symptoms (OR, 4.12; 95% CI, 2.24 to 7.55) were independent risk factors for positive CUS results. DVT symptoms (OR, 4.78; 95% CI, 2.75 to 8.33) and a history of venous thromboembolism (OR, 2.59; 95% CI, 1.46 to 4.62) were independent risk factors for proximal DVT. The 3-month risk of recurrent thromboembolic event or death was not significantly different among patients with and without DVT (6.5% vs 2.7%, p = 0.15). CONCLUSION: These results do not support screening for DVT in patients with CTPA-proven symptomatic PE; however, they suggest that CUS might prove especially efficient and safe as a frontline test in elderly patients with suspected PE. Further studies are needed before these conclusions can be translated into clinical recommendations.

Quantification of elasticity changes in the myometrium during labor using Supersonic Shear Imaging: a feasibility study.

Very little is known about the myometrium's physiology in terms of its elasticity but shear wave elastography could be an efficient tool to better understand it. This could considerably help the prevention of difficult births, the consequences of which are tremendous for neonate morbidity and pathologies. The purpose of this paper is to show the feasibility of the in vivo monitoring of myometrial stiffness changes in contraction and relaxation during pregnancy. In this study, Supersonic Shear Wave Imaging, a real-time and quantitative imaging technique that has been proven efficient for the investigation of tissue elasticity, was used to quantify the uterus shear-wave speed and stiffness in 6 patients, through the abdomen, using an 8-MHz linear ultrasound probe. Changes in shear wave speed were tracked in real time during the uterine contraction and were well correlated with the uterine pressure, which is currently considered to be a gold standard. These results open a new way to better understand the myometrium contraction during labour.

Multidetector CT scan findings of a right aberrant retroesophageal vertebral artery with an anomalous origin from a cervical aortic arch.

Various malformations of the aortic arch and great vessels have been reported in the literature, which reflects the complexity of their embryologic development. Most of them are of incidental finding and remain asymptomatic but can be responsible for respiratory or digestive symptoms and be associated with congenital cardiac diseases. We report the case of a patient presenting a right retroesophageal vertebral artery. This malformation was associated with multiple anomalies of the aortic arch. We report a classification of the most common aortic arch abnormalities by recalling Edwards double aortic arch model and embryologic variants. Here, we report on the rare case of a right retroesophageal vertebral artery. We assimilate this malformation to a vertebral arteria lusoria and attribute it to the lack of caudal migration of the fourth branchial arch, responsible for a left cervical aortic arch with an interruption between the right subclavian and vertebral arteries.

CT imaging of peripheral pulmonary vessel disease.

The diseases concerning the small pulmonary vessels are difficult to diagnose. Pathologic findings are rarely limited to the small vessels, and a continuum between the involvement of small and large vessels is frequent. Moreover, small vessels can be affected by various disease entities with overlapping radiologic features and a wide spectrum of clinical manifestations. Nevertheless, these various entities can be easily separated into two different groups by imaging techniques, particularly by computed tomography: obstructive and inflammatory diseases. Radiologic findings of obstructive diseases are relatively constant, dominated by the manifestation of pulmonary hypertension. In contrast, radiologic manifestations of inflammatory diseases are often florid and nonspecific. After a recall of the classification of small vessel diseases and the imaging techniques, we show the computed tomography features of the principal diseases involving the small pulmonary vessels by classifying them in these two principal groups.

Usefulness of abdominal CT scan in severe peritoneal sepsis linked to primary peritonitis.

We report 2 cases of primary group A streptococcal peritonitis in which emergency abdominal CT scan ruled out a hollow viscus perforation, or necrosis, avoiding unnecessary laparotomy. These cases highlight the usefulness of abdominal CT scan and suggest that blind surgical exploration has no advantages.

Comparison of doses for pulmonary embolism detection with helical CT and pulmonary angiography.

The objective of this study was to compare the radiation exposure delivered by helical CT and pulmonary angiography (PA) for the detection of pulmonary embolism (PE), with an anthropomorphic phantom. A preliminary survey defined a representative standard procedure for helical CT and PA ( n=148) by choosing the exposure settings most frequently used. Then, radiation doses were measured with thermoluminescent dosimeters TLD 100 (Lif) introduced into the depth of an anthropomorphic phantom. Average doses were approximately five times smaller with helical CT than with PA (6.4+/-1.5 and 28+/-7.6 mGy, respectively). The most important doses were abreast the pulmonary apex for CT, and abreast the pulmonary arteries for PA. Compared with PA, helical CT dose distribution was relatively uniform (10-13 mGy). Finally, concerning abdomen and pelvis, doses were more important for PA than for CT scan (0.06-2.86 and 0.2-11.5 mGy, respectively). For the diagnostics of PE, radiation exposure is five times smaller with helical CT than with pulmonary angiography.

Pulmonary arterial hypertension: thin-section CT predictors of epoprostenol therapy failure.

PURPOSE: To correlate pretherapeutic thin-section computed tomographic (CT) findings in patients with pulmonary hypertension with the risk of fatality with treatment with epoprostenol. MATERIALS AND METHODS: Seventy-three consecutive patients with severe pulmonary hypertension treated with epoprostenol were retrospectively separated into two groups. The first group included 12 patients who had a fatal outcome with epoprostenol therapy. The second group (n = 61) was a reference group of patients with epoprostenol-induced clinical improvement. Pretherapeutic thin-section CT scans of each patient were reviewed. RESULTS: Poorly defined nodular opacities (P =.003), septal lines (P =.04), pleural effusion (P =.01), and adenopathy (P =.009) strongly correlated with a risk of clinical worsening with treatment. In six patients in group 1, postmortem examination of the lung revealed either pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis. CONCLUSION: On pretherapeutic thin-section CT scans, poorly defined nodular opacities, septal lines, pleural effusion, and adenopathy should raise suspicion for pulmonary veno-occlusive disease or pulmonary capillary hemangiomatosis and provoke possible further evaluation before epoprostenol therapy.

Pulmonary hypertension: CT of the chest in pulmonary venoocclusive disease.

OBJECTIVE: Pulmonary venoocclusive disease is a rare cause of pulmonary hypertension that is often difficult to distinguish from severe primary pulmonary hypertension. Unfortunately, medical treatment of primary pulmonary hypertension with prostacyclin can be fatal in patients with venoocclusive disease, and an early pretreatment diagnosis of this uncommon condition is critical. The aim of our study was to evaluate this disease noninvasively using CT of the chest. MATERIALS AND METHODS: We reviewed cross-referenced records from 1996 to 2001 in our departments of radiology and pathology and identified 15 patients with initial pretreatment CT scans who had pathologically confirmed pulmonary venoocclusive disease. Their CT scans were compared with the CT scans of 15 consecutive patients with pathologically confirmed primary pulmonary hypertension. All patients had undergone a postmortem or posttransplantation examination. RESULTS: Ground-glass opacities were significantly more frequent in pulmonary venoocclusive disease (p = 0.003); the opacities were abundant with random zonal predominance and preferentially centrilobular distribution (p = 0.03). Subpleural septal lines and adenopathy were also significantly more frequent (p < 0.0001). CONCLUSION: On the initial pretreatment chest CT scan, the presence of ground-glass opacities (particularly with a centrilobular distribution), septal lines, and adenopathy are indicative of pulmonary venoocclusive disease in patients displaying pulmonary hypertension. Caution should be exercised before vasodilator therapy is initiated in the patients whose scans show such radiologic abnormalities.

Diagnostic strategy for patients with suspected pulmonary embolism: a prospective multicentre outcome study.

BACKGROUND: We designed a prospective multicentre outcome study to evaluate a diagnostic strategy based on clinical probability, spiral CT, and venous compression ultrasonography of the legs in patients with suspected pulmonary embolism (PE). The main aim was to assess the safety of withholding anticoagulant treatment in patients with low or intermediate clinical probability of PE and negative findings on spiral CT and ultrasonography. METHODS: 1041 consecutive inpatients and outpatients with suspected PE were included. Patients with negative spiral CT and ultrasonography and clinically assessed as having a low or intermediate clinical probability were left untreated. Those with high clinical probability underwent lung scanning, pulmonary angiography, or both. All patients were followed up for 3 months. FINDINGS: PE was diagnosed in 360 (34.6%) patients; 55 had positive ultrasonography despite negative spiral CT. Of 601 patients with negative spiral CT and ultrasonography, 76 were clinically assessed as having a high probability of PE; lung scanning or angiography showed PE in four (5.3% [95% CI 1.5-13.1]). The remaining 525 patients were assessed as having low or intermediate clinical probability, and 507 of them were not treated. Of these patients, nine experienced venous thromboembolism during follow-up (1.8% [0.8-3.3]). The diagnostic strategy proved inconclusive in 95 (9.1%) patients, and pulmonary angiography was done in 74 (7.1%). INTERPRETATION: Withholding of anticoagulant therapy is safe when the clinical probability of PE is assessed as low or intermediate and spiral CT and ultrasonography are negative.