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Normal Anatomy of the Fetus at MR Imaging¹

¹ From the Department of Radiology, University of Texas Medical School, Houston. Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received February 8, 1999; revision requested May 20 and received June 14; accepted June 14. Address reprint requests to A.K., Department of Radiology, Lyndon B. Johnson General Hospital, 5656 Kelley St, Houston, TX 77026.

View larger version (179K): [in a new window]   Figure 1a.   Fetus at 28 weeks gestation. (a, b) Coronal 0.5-signal-acquired single-shot fast SE images of the brain (repetition time msec/echo time msec = 16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show the cerebral hemisphere (a), thalamus (b), medulla oblongata (c), temporal lobe (d), cerebral peduncle (curved arrow), third ventricle (straight white arrow), and gray-white matter junction (black arrows). (c, d) Coronal 0.5-signal-acquired single-shot fast SE images of the face (16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show that the orbits have moved to a more medial position, which is reflective of normal embryologic development. Both frontal lobes of the cerebral hemispheres are present. Other structures seen on these images include the tongue (a) within the oral cavity, fluid within the maxillary sinus (white arrow), the nasal conchae and nasal meatus (straight black arrow), and the flow void associated with the superior sagittal sinus (curved arrow).

View larger version (183K): [in a new window]   Figure 1b.   Fetus at 28 weeks gestation. (a, b) Coronal 0.5-signal-acquired single-shot fast SE images of the brain (repetition time msec/echo time msec = 16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show the cerebral hemisphere (a), thalamus (b), medulla oblongata (c), temporal lobe (d), cerebral peduncle (curved arrow), third ventricle (straight white arrow), and gray-white matter junction (black arrows). (c, d) Coronal 0.5-signal-acquired single-shot fast SE images of the face (16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show that the orbits have moved to a more medial position, which is reflective of normal embryologic development. Both frontal lobes of the cerebral hemispheres are present. Other structures seen on these images include the tongue (a) within the oral cavity, fluid within the maxillary sinus (white arrow), the nasal conchae and nasal meatus (straight black arrow), and the flow void associated with the superior sagittal sinus (curved arrow).

View larger version (171K): [in a new window]   Figure 1c.   Fetus at 28 weeks gestation. (a, b) Coronal 0.5-signal-acquired single-shot fast SE images of the brain (repetition time msec/echo time msec = 16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show the cerebral hemisphere (a), thalamus (b), medulla oblongata (c), temporal lobe (d), cerebral peduncle (curved arrow), third ventricle (straight white arrow), and gray-white matter junction (black arrows). (c, d) Coronal 0.5-signal-acquired single-shot fast SE images of the face (16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show that the orbits have moved to a more medial position, which is reflective of normal embryologic development. Both frontal lobes of the cerebral hemispheres are present. Other structures seen on these images include the tongue (a) within the oral cavity, fluid within the maxillary sinus (white arrow), the nasal conchae and nasal meatus (straight black arrow), and the flow void associated with the superior sagittal sinus (curved arrow).

View larger version (178K): [in a new window]   Figure 1d.   Fetus at 28 weeks gestation. (a, b) Coronal 0.5-signal-acquired single-shot fast SE images of the brain (repetition time msec/echo time msec = 16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show the cerebral hemisphere (a), thalamus (b), medulla oblongata (c), temporal lobe (d), cerebral peduncle (curved arrow), third ventricle (straight white arrow), and gray-white matter junction (black arrows). (c, d) Coronal 0.5-signal-acquired single-shot fast SE images of the face (16,692/99.7, 24 x 24-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 150 matrix, 12 sections, total acquisition time of 17 seconds) show that the orbits have moved to a more medial position, which is reflective of normal embryologic development. Both frontal lobes of the cerebral hemispheres are present. Other structures seen on these images include the tongue (a) within the oral cavity, fluid within the maxillary sinus (white arrow), the nasal conchae and nasal meatus (straight black arrow), and the flow void associated with the superior sagittal sinus (curved arrow).

View larger version (138K): [in a new window]   Figure 2.   Fetus at 30 weeks gestation. Axial half-Fourier single-shot fast SE image through the brain (4,300/60, 30 x 35-cm field of view, 7.5-mm section thickness with 5.0-mm spacing, 192 x 256 matrix, 13 sections, total acquisition time of 19 seconds) shows the lateral ventricles (a), cerebral peduncles (arrowhead), interpeduncular cistern, and cerebral aqueduct (arrow). (Courtesy of Deborah Levine, MD, and Robert R. Edelman, MD, Beth Israel Deaconess Medical Center, Boston, Mass.)

View larger version (149K): [in a new window]   Figures 3, 4.   Third-trimester fetal anatomy. (3) Sagittal half-Fourier single-shot fast SE image of a fetus (4,300/60, 30 x 35-cm field of view, 192 x 256 matrix, total acquisition time of 19 seconds) shows the hyperintense lung (a) and the low-signal-intensity heart (b). A kidney is seen posteriorly (c) just below the level of the diaphragm. Additional structures seen on this image include the pons (d), oropharynx (straight white arrow), esophagus (arrowhead), fourth ventricle (black arrow), and umbilical vein (curved arrow). (4) Sagittal half-Fourier single-shot fast SE image of a fetus (4,300/60, 30 x 35-cm field of view, 7.5-mm section thickness with 5.0-mm spacing, 192 x 256 matrix, 13 sections, total acquisition time of 19 seconds) shows the lateral ventricle (a), diencephalon (b), cerebellum (c), umbilical cord (straight arrows), umbilical cord insertion (curved arrow), and teeth (arrowheads). (Figs 3 and 4 courtesy of Deborah Levine, MD, and Robert R. Edelman, MD, Beth Israel Deaconess Medical Center, Boston, Mass.)

View larger version (153K): [in a new window]   Figures 3, 4.   Third-trimester fetal anatomy. (3) Sagittal half-Fourier single-shot fast SE image of a fetus (4,300/60, 30 x 35-cm field of view, 192 x 256 matrix, total acquisition time of 19 seconds) shows the hyperintense lung (a) and the low-signal-intensity heart (b). A kidney is seen posteriorly (c) just below the level of the diaphragm. Additional structures seen on this image include the pons (d), oropharynx (straight white arrow), esophagus (arrowhead), fourth ventricle (black arrow), and umbilical vein (curved arrow). (4) Sagittal half-Fourier single-shot fast SE image of a fetus (4,300/60, 30 x 35-cm field of view, 7.5-mm section thickness with 5.0-mm spacing, 192 x 256 matrix, 13 sections, total acquisition time of 19 seconds) shows the lateral ventricle (a), diencephalon (b), cerebellum (c), umbilical cord (straight arrows), umbilical cord insertion (curved arrow), and teeth (arrowheads). (Figs 3 and 4 courtesy of Deborah Levine, MD, and Robert R. Edelman, MD, Beth Israel Deaconess Medical Center, Boston, Mass.)

View larger version (153K): [in a new window]   Figure 5a.   Fetus at 26 weeks gestation. Coronal 0.5-signal-acquired single-shot fast SE image of a fetus (sagittal section through the maternal pelvis) (12,595/97.6, 36 x 36-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 160 matrix, nine sections, total acquisition time of 13 seconds) (a) and sagittal 0.5-signal-acquired single-shot fast SE image of the fetus (coronal section through the maternal pelvis) (13,117/100, 28 x 28-cm field of view, 4.0-mm section thickness with 1.5-mm spacing, 256 x 192 matrix, eight sections, total acquisition time of 13 seconds) (b) show the facial anatomy. Structures seen include the palate (straight arrow), tongue (arrowhead in a), oropharynx (curved arrow), and nasopharynx (arrowhead in b).

View larger version (141K): [in a new window]   Figure 5b.   Fetus at 26 weeks gestation. Coronal 0.5-signal-acquired single-shot fast SE image of a fetus (sagittal section through the maternal pelvis) (12,595/97.6, 36 x 36-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 160 matrix, nine sections, total acquisition time of 13 seconds) (a) and sagittal 0.5-signal-acquired single-shot fast SE image of the fetus (coronal section through the maternal pelvis) (13,117/100, 28 x 28-cm field of view, 4.0-mm section thickness with 1.5-mm spacing, 256 x 192 matrix, eight sections, total acquisition time of 13 seconds) (b) show the facial anatomy. Structures seen include the palate (straight arrow), tongue (arrowhead in a), oropharynx (curved arrow), and nasopharynx (arrowhead in b).

View larger version (153K): [in a new window]   Figure 6.   Fetus at 26 weeks gestation. Sagittal image of a fetus shows the entire spinal column. The sacral portion of the spine demonstrates a mild degree of blurring; however, no abnormalities were seen on other images from the same series (not shown). Hyperintense fluid-filled bowel loops (b) and the intermediate-signal-intensity heart (h) are shown. The low-signal-intensity soft-tissue structure in the retroperitoneum is the collecting system of the kidney (c).

View larger version (187K): [in a new window]   Figure 7.   Fetus at 38 weeks gestation. Coronal heavily T2-weighted fast SE image of the thorax and upper abdomen (11,000/198, 32 x 24-cm field of view, 4.0-mm section thickness with 1.0-mm spacing, 512 x 256 matrix, 14 sections, total acquisition time of 45 seconds) shows the lung (L) and tracheobronchial tree (white arrows), which appear hyperintense because they are filled with amniotic fluid. The pulmonary vasculature (black arrow) and heart (h) are hypointense. Just inferior to the left side of the diaphragm is the stomach (s), which is hyperintense.

View larger version (155K): [in a new window]   Figure 8a.   Fetus at 22 weeks gestation. (a) Oblique fast SE image of a fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the trachea (arrow), the carina (white arrowhead), and the low-signal-intensity aortic arch and descending aorta (black arrowhead). (b) Oblique fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the right and left brachiocephalic veins (straight arrows) joining the superior vena cava (arrowhead). Two chambers of the heart are shown as low-signal-intensity structures. The inferior vena cava (curved arrow) is shown joining the right atrium. (c) Sagittal fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the aortic root (arrowhead) with a portion of the descending aorta. Also seen is the posterior hemidiaphragm (arrow). (d) Coronal fast SE image of the fetus (5,714/84, 40 x 30-cm field of view, 3.0-mm section thickness with 2.0-mm spacing, 10 sections, total acquisition time of 80 seconds) shows the main pulmonary trunk (arrowhead) with the left pulmonary artery. Also seen are the liver (a) and stomach (b) just below the diaphragm.

View larger version (152K): [in a new window]   Figure 8b.   Fetus at 22 weeks gestation. (a) Oblique fast SE image of a fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the trachea (arrow), the carina (white arrowhead), and the low-signal-intensity aortic arch and descending aorta (black arrowhead). (b) Oblique fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the right and left brachiocephalic veins (straight arrows) joining the superior vena cava (arrowhead). Two chambers of the heart are shown as low-signal-intensity structures. The inferior vena cava (curved arrow) is shown joining the right atrium. (c) Sagittal fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the aortic root (arrowhead) with a portion of the descending aorta. Also seen is the posterior hemidiaphragm (arrow). (d) Coronal fast SE image of the fetus (5,714/84, 40 x 30-cm field of view, 3.0-mm section thickness with 2.0-mm spacing, 10 sections, total acquisition time of 80 seconds) shows the main pulmonary trunk (arrowhead) with the left pulmonary artery. Also seen are the liver (a) and stomach (b) just below the diaphragm.

View larger version (147K): [in a new window]   Figure 8c.   Fetus at 22 weeks gestation. (a) Oblique fast SE image of a fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the trachea (arrow), the carina (white arrowhead), and the low-signal-intensity aortic arch and descending aorta (black arrowhead). (b) Oblique fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the right and left brachiocephalic veins (straight arrows) joining the superior vena cava (arrowhead). Two chambers of the heart are shown as low-signal-intensity structures. The inferior vena cava (curved arrow) is shown joining the right atrium. (c) Sagittal fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the aortic root (arrowhead) with a portion of the descending aorta. Also seen is the posterior hemidiaphragm (arrow). (d) Coronal fast SE image of the fetus (5,714/84, 40 x 30-cm field of view, 3.0-mm section thickness with 2.0-mm spacing, 10 sections, total acquisition time of 80 seconds) shows the main pulmonary trunk (arrowhead) with the left pulmonary artery. Also seen are the liver (a) and stomach (b) just below the diaphragm.

View larger version (160K): [in a new window]   Figure 8d.   Fetus at 22 weeks gestation. (a) Oblique fast SE image of a fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the trachea (arrow), the carina (white arrowhead), and the low-signal-intensity aortic arch and descending aorta (black arrowhead). (b) Oblique fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the right and left brachiocephalic veins (straight arrows) joining the superior vena cava (arrowhead). Two chambers of the heart are shown as low-signal-intensity structures. The inferior vena cava (curved arrow) is shown joining the right atrium. (c) Sagittal fast SE image of the fetus (5,714/91, 40 x 30-cm field of view, 4.0-mm section thickness with 2.0-mm spacing, 256 x 128 matrix, 10 sections, total acquisition time of 80 seconds) shows the aortic root (arrowhead) with a portion of the descending aorta. Also seen is the posterior hemidiaphragm (arrow). (d) Coronal fast SE image of the fetus (5,714/84, 40 x 30-cm field of view, 3.0-mm section thickness with 2.0-mm spacing, 10 sections, total acquisition time of 80 seconds) shows the main pulmonary trunk (arrowhead) with the left pulmonary artery. Also seen are the liver (a) and stomach (b) just below the diaphragm.

View larger version (143K): [in a new window]   Figure 9.   Fetus at 28 weeks gestation. Sagittal 0.5-signal-acquired single-shot fast SE image of a fetus (22,458/64.1, 46 x 32-cm field of view, 7.0-mm section thickness with 3.0-mm spacing, 256 x 192 matrix, 12 sections, total acquisition time of 22 seconds) shows the thoracic descending aorta (long arrow), thymus (arrowhead), heart (short arrow), and liver (a).

View larger version (154K): [in a new window]   Figure 10.   Fetus at 38 weeks gestation. Axial echo-planar image through the lung bases (1,699/70, 36 x 27-cm field of view, 6.0-mm section thickness with 1.5-mm spacing, 256 x 128 matrix, 15 sections, total acquisition time of 29 seconds) shows low-signal-intensity structures such as the pulmonary vasculature (arrowhead), the descending aorta (black arrow), and two chambers of the heart (a) separated by the interventricular septum (white arrow).

View larger version (143K): [in a new window]   Figure 11.   Third-trimester fetal anatomy. Axial 0.5-signal-acquired single-shot fast SE image through the lungs (57,738/99.3, 38 x 38-cm field of view, 5.0-mm section thickness with 1.0-mm spacing, 512 x 512 matrix) shows low-signal-intensity structures including the heart (h) and descending aorta (arrowhead).

View larger version (163K): [in a new window]   Figure 12a.   Fetus at 38 weeks gestation. (a) Axial flow-sensitive GRE image through the abdomen (167/4.7, 60° flip angle, 34 x 34-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 256 x 128 matrix, 26 sections, total acquisition time of 25 seconds) shows the fluid-filled proximal renal collecting systems (arrows) and bladder (bl) as hypointense structures. (b) Axial fast SE image through the abdomen (11,000/198, 40 x 30-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 512 x 256 matrix, 20 sections, total acquisition time of 45 seconds) shows the fluid-filled dilated bladder (bl), dilated renal collecting systems (c), and bowel loops (bo) as hyperintense structures. Both postnatal US and cystography showed the collecting systems and bladder to be normal. (c) Coronal fast SE image of the fetus (11,000/198, 32 x 24-cm field of view, 4.0-mm section thickness with 1.0-mm spacing, 512 x 256 matrix, 14 sections, total acquisition time of 45 seconds) shows bowel loops (bo) and the bladder (bl).

View larger version (182K): [in a new window]   Figure 12b.   Fetus at 38 weeks gestation. (a) Axial flow-sensitive GRE image through the abdomen (167/4.7, 60° flip angle, 34 x 34-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 256 x 128 matrix, 26 sections, total acquisition time of 25 seconds) shows the fluid-filled proximal renal collecting systems (arrows) and bladder (bl) as hypointense structures. (b) Axial fast SE image through the abdomen (11,000/198, 40 x 30-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 512 x 256 matrix, 20 sections, total acquisition time of 45 seconds) shows the fluid-filled dilated bladder (bl), dilated renal collecting systems (c), and bowel loops (bo) as hyperintense structures. Both postnatal US and cystography showed the collecting systems and bladder to be normal. (c) Coronal fast SE image of the fetus (11,000/198, 32 x 24-cm field of view, 4.0-mm section thickness with 1.0-mm spacing, 512 x 256 matrix, 14 sections, total acquisition time of 45 seconds) shows bowel loops (bo) and the bladder (bl).

View larger version (157K): [in a new window]   Figure 12c.   Fetus at 38 weeks gestation. (a) Axial flow-sensitive GRE image through the abdomen (167/4.7, 60° flip angle, 34 x 34-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 256 x 128 matrix, 26 sections, total acquisition time of 25 seconds) shows the fluid-filled proximal renal collecting systems (arrows) and bladder (bl) as hypointense structures. (b) Axial fast SE image through the abdomen (11,000/198, 40 x 30-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 512 x 256 matrix, 20 sections, total acquisition time of 45 seconds) shows the fluid-filled dilated bladder (bl), dilated renal collecting systems (c), and bowel loops (bo) as hyperintense structures. Both postnatal US and cystography showed the collecting systems and bladder to be normal. (c) Coronal fast SE image of the fetus (11,000/198, 32 x 24-cm field of view, 4.0-mm section thickness with 1.0-mm spacing, 512 x 256 matrix, 14 sections, total acquisition time of 45 seconds) shows bowel loops (bo) and the bladder (bl).

View larger version (151K): [in a new window]   Figure 13.   Fetus at 28 weeks gestation. Axial 0.5-signal-acquired single-shot fast SE image through the abdomen (57,738/99.3, 38 x 38-cm field of view, 5.0-mm section thickness with 1.0-mm spacing, 512 x 512 matrix) shows the kidneys. The normal renal collecting systems appear as high-signal-intensity structures (arrows).

View larger version (136K): [in a new window]   Figure 14a.   Fetus at 38 weeks gestation. (a) Axial T1-weighted flow-sensitive GRE image through the abdomen (167/4.7, 60° flip angle, 34 x 34-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 256 x 128 matrix, 26 sections, total acquisition time of 25 seconds) shows the liver parenchyma (L) with the hyperintense hepatic vasculature (arrowhead). The hyperintense inferior vena cava (black arrow) and descending aorta (white arrow) are also evident. The relatively low-signal-intensity structure posterior to the left hepatic lobe is the stomach (S). (b) Axial T1-weighted flow-sensitive GRE image through the abdomen (167/4.7, 60° flip angle, 34 x 34-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 256 x 128 matrix, 26 sections, total acquisition time of 25 seconds) shows the hepatic veins (black arrow) approaching the inferior vena cava. The subtle hyperintense vascular structure just lateral to the aorta is the azygos vein (white arrow).

View larger version (141K): [in a new window]   Figure 14b.   Fetus at 38 weeks gestation. (a) Axial T1-weighted flow-sensitive GRE image through the abdomen (167/4.7, 60° flip angle, 34 x 34-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 256 x 128 matrix, 26 sections, total acquisition time of 25 seconds) shows the liver parenchyma (L) with the hyperintense hepatic vasculature (arrowhead). The hyperintense inferior vena cava (black arrow) and descending aorta (white arrow) are also evident. The relatively low-signal-intensity structure posterior to the left hepatic lobe is the stomach (S). (b) Axial T1-weighted flow-sensitive GRE image through the abdomen (167/4.7, 60° flip angle, 34 x 34-cm field of view, 6.0-mm section thickness with 3.0-mm spacing, 256 x 128 matrix, 26 sections, total acquisition time of 25 seconds) shows the hepatic veins (black arrow) approaching the inferior vena cava. The subtle hyperintense vascular structure just lateral to the aorta is the azygos vein (white arrow).

View larger version (167K): [in a new window]   Figure 15.   Fetus at 28 weeks gestation. Sagittal 0.5-signal-acquired single-shot fast SE image through the maternal pelvis (29,336/64.1, 48 x 48-cm field of view, 7.0-mm section thickness with 3.0-mm spacing, 256 x 192 matrix, 18 sections, total acquisition time of 29 seconds) shows an intrauterine gestation with a high, posterior placenta (arrow). The fetus is in a longitudinal vertex position. The three-vessel umbilical cord is wrapped around the fetus' neck (arrowhead).

View larger version (134K): [in a new window]   Figure 16a.   Fetus at 26 weeks gestation. Sagittal 0.5-signal-acquired single-shot fast SE image of a fetus (coronal section through the maternal pelvis) (36,070/63.8, 46 x 46-cm field of view, 7.0-mm section thickness with 3.0-mm spacing, 256 x 192 matrix, 22 sections, total acquisition time of 36 seconds) (a) and coronal 0.5-signal-acquired single-shot fast SE image of the fetus (sagittal section through the maternal pelvis) (12,595/97.6, 36 x 36-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 160 matrix, nine sections, total acquisition time of 13 seconds) (b) show the fetus to be in a longitudinal breech position with a right anterolateral placenta (arrow).

View larger version (144K): [in a new window]   Figure 16b.   Fetus at 26 weeks gestation. Sagittal 0.5-signal-acquired single-shot fast SE image of a fetus (coronal section through the maternal pelvis) (36,070/63.8, 46 x 46-cm field of view, 7.0-mm section thickness with 3.0-mm spacing, 256 x 192 matrix, 22 sections, total acquisition time of 36 seconds) (a) and coronal 0.5-signal-acquired single-shot fast SE image of the fetus (sagittal section through the maternal pelvis) (12,595/97.6, 36 x 36-cm field of view, 5.0-mm section thickness with 2.5-mm spacing, 256 x 160 matrix, nine sections, total acquisition time of 13 seconds) (b) show the fetus to be in a longitudinal breech position with a right anterolateral placenta (arrow).