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Helical CT in Emergency Radiology¹

¹ From the Department of Radiology, Massachusetts General Hospital, Blossom St, PO Box 9657, FND 210, Boston, MA 02114. Received July 20, 1998; revision requested August 28; revision received January 26, 1999; accepted June 18. Address reprint requests to R.A.N.

View larger version (119K): [in a new window]   Figure 1a. Helical CT of thoracic aortic injury. (a) Transverse section at the aortic arch shows an intimal disruption with a false aneurysm (arrow), as well as blood (H) in the mediastinum. Bilateral hemothoraces are present. (b) Slightly lower transverse section also shows the false aneurysm (large arrow). A ring of hematoma (small arrow) surrounds the descending aorta. (c) Oblique reformation shows the relationship of the injury and false aneurysm (A) with the left common carotid artery (C) and left subclavian artery (S). Arrow indicates torn intimal flap. (d) Three-dimensional reformation (CT angiogram) shows the relationship of the injury and false aneurysm (A) to the brachiocephalic trunk (B), left common carotid artery (C), and left subclavian artery (S).

View larger version (126K): [in a new window]   Figure 1b. Helical CT of thoracic aortic injury. (a) Transverse section at the aortic arch shows an intimal disruption with a false aneurysm (arrow), as well as blood (H) in the mediastinum. Bilateral hemothoraces are present. (b) Slightly lower transverse section also shows the false aneurysm (large arrow). A ring of hematoma (small arrow) surrounds the descending aorta. (c) Oblique reformation shows the relationship of the injury and false aneurysm (A) with the left common carotid artery (C) and left subclavian artery (S). Arrow indicates torn intimal flap. (d) Three-dimensional reformation (CT angiogram) shows the relationship of the injury and false aneurysm (A) to the brachiocephalic trunk (B), left common carotid artery (C), and left subclavian artery (S).

View larger version (121K): [in a new window]   Figure 1c. Helical CT of thoracic aortic injury. (a) Transverse section at the aortic arch shows an intimal disruption with a false aneurysm (arrow), as well as blood (H) in the mediastinum. Bilateral hemothoraces are present. (b) Slightly lower transverse section also shows the false aneurysm (large arrow). A ring of hematoma (small arrow) surrounds the descending aorta. (c) Oblique reformation shows the relationship of the injury and false aneurysm (A) with the left common carotid artery (C) and left subclavian artery (S). Arrow indicates torn intimal flap. (d) Three-dimensional reformation (CT angiogram) shows the relationship of the injury and false aneurysm (A) to the brachiocephalic trunk (B), left common carotid artery (C), and left subclavian artery (S).

View larger version (114K): [in a new window]   Figure 1d. Helical CT of thoracic aortic injury. (a) Transverse section at the aortic arch shows an intimal disruption with a false aneurysm (arrow), as well as blood (H) in the mediastinum. Bilateral hemothoraces are present. (b) Slightly lower transverse section also shows the false aneurysm (large arrow). A ring of hematoma (small arrow) surrounds the descending aorta. (c) Oblique reformation shows the relationship of the injury and false aneurysm (A) with the left common carotid artery (C) and left subclavian artery (S). Arrow indicates torn intimal flap. (d) Three-dimensional reformation (CT angiogram) shows the relationship of the injury and false aneurysm (A) to the brachiocephalic trunk (B), left common carotid artery (C), and left subclavian artery (S).

View larger version (86K): [in a new window]   Figure 2a. Helical CT of aortic dissection. (a) Transverse section at the pulmonary artery level shows a normal ascending aorta (AA) but type III dissection in the descending aorta. The true lumen (T) is well opacified at the time this section was acquired, but there is delayed opacification of the patent false lumen (F). (b) Oblique reformation across the diaphragm shows the patent true lumen (T) and patent, larger caliber false lumen (F). (c) Coronal reformation through the renal arteries shows the thin intimal flap (arrows) between the true and false lumens. (d) Three-dimensional reformation of the abdominal aorta shows patency of the true and false lumens, as well as patency of the celiac artery (C), superior mesenteric artery (S), and renal arteries (arrows). The upper poles of the kidneys were imaged at CT prior to full parenchymal opacification; by comparison the lower pole parenchyma is well opacified.

View larger version (152K): [in a new window]   Figure 2b. Helical CT of aortic dissection. (a) Transverse section at the pulmonary artery level shows a normal ascending aorta (AA) but type III dissection in the descending aorta. The true lumen (T) is well opacified at the time this section was acquired, but there is delayed opacification of the patent false lumen (F). (b) Oblique reformation across the diaphragm shows the patent true lumen (T) and patent, larger caliber false lumen (F). (c) Coronal reformation through the renal arteries shows the thin intimal flap (arrows) between the true and false lumens. (d) Three-dimensional reformation of the abdominal aorta shows patency of the true and false lumens, as well as patency of the celiac artery (C), superior mesenteric artery (S), and renal arteries (arrows). The upper poles of the kidneys were imaged at CT prior to full parenchymal opacification; by comparison the lower pole parenchyma is well opacified.

View larger version (169K): [in a new window]   Figure 2c. Helical CT of aortic dissection. (a) Transverse section at the pulmonary artery level shows a normal ascending aorta (AA) but type III dissection in the descending aorta. The true lumen (T) is well opacified at the time this section was acquired, but there is delayed opacification of the patent false lumen (F). (b) Oblique reformation across the diaphragm shows the patent true lumen (T) and patent, larger caliber false lumen (F). (c) Coronal reformation through the renal arteries shows the thin intimal flap (arrows) between the true and false lumens. (d) Three-dimensional reformation of the abdominal aorta shows patency of the true and false lumens, as well as patency of the celiac artery (C), superior mesenteric artery (S), and renal arteries (arrows). The upper poles of the kidneys were imaged at CT prior to full parenchymal opacification; by comparison the lower pole parenchyma is well opacified.

View larger version (152K): [in a new window]   Figure 2d. Helical CT of aortic dissection. (a) Transverse section at the pulmonary artery level shows a normal ascending aorta (AA) but type III dissection in the descending aorta. The true lumen (T) is well opacified at the time this section was acquired, but there is delayed opacification of the patent false lumen (F). (b) Oblique reformation across the diaphragm shows the patent true lumen (T) and patent, larger caliber false lumen (F). (c) Coronal reformation through the renal arteries shows the thin intimal flap (arrows) between the true and false lumens. (d) Three-dimensional reformation of the abdominal aorta shows patency of the true and false lumens, as well as patency of the celiac artery (C), superior mesenteric artery (S), and renal arteries (arrows). The upper poles of the kidneys were imaged at CT prior to full parenchymal opacification; by comparison the lower pole parenchyma is well opacified.

View larger version (91K): [in a new window]   Figure 3a. Helical CT of pulmonary embolus. (a) Transverse section obtained just below the aortic arch shows an embolus (arrow) in the left pulmonary artery. (b) Transverse section at a lower level shows an embolus (arrow) in the left lower lobe pulmonary artery.

View larger version (106K): [in a new window]   Figure 3b. Helical CT of pulmonary embolus. (a) Transverse section obtained just below the aortic arch shows an embolus (arrow) in the left pulmonary artery. (b) Transverse section at a lower level shows an embolus (arrow) in the left lower lobe pulmonary artery.

View larger version (131K): [in a new window]   Figure 4a. Helical CT of neck abscess. (a) Transverse scan shows a low-attenuating abscess (straight arrows) in the lateral retropharyngeal soft tissues, anterior to the right carotid artery and jugular vein (small curved arrows), which are compressed; compare with the normal left common carotid artery (C) and left jugular vein (J). The abscess displaces the airway (A) to the left. Extensive edema is seen in the soft tissues of the right side of the neck, lateral to the abscess; compare with the left soft tissues. (b) Coronal reformation shows the abscess (long arrows) medial to the lateral pharyngeal fat plane (short arrows). Compare with normal left lateral pharyngeal fat plane (L). Extensive edema is again seen in the soft tissues of the right side of the neck.

View larger version (64K): [in a new window]   Figure 4b. Helical CT of neck abscess. (a) Transverse scan shows a low-attenuating abscess (straight arrows) in the lateral retropharyngeal soft tissues, anterior to the right carotid artery and jugular vein (small curved arrows), which are compressed; compare with the normal left common carotid artery (C) and left jugular vein (J). The abscess displaces the airway (A) to the left. Extensive edema is seen in the soft tissues of the right side of the neck, lateral to the abscess; compare with the left soft tissues. (b) Coronal reformation shows the abscess (long arrows) medial to the lateral pharyngeal fat plane (short arrows). Compare with normal left lateral pharyngeal fat plane (L). Extensive edema is again seen in the soft tissues of the right side of the neck.

View larger version (134K): [in a new window]   Figure 5a. Helical CT of liver and right kidney injury. (a) Transverse scan shows a low-attenuating laceration (black arrow) of the right lobe of the liver in a patient who suffered right-sided blunt abdominal trauma. A small amount of hemoperitoneum (white arrows) can be seen around the right lobe of liver and behind the spleen. (b) Slightly lower transverse scan in the same patient shows an additional laceration of the right kidney (black arrow) with hemorrhage (H) in the right perirenal space. Hemoperitoneum (white arrow) can be seen adjacent to the liver.

View larger version (131K): [in a new window]   Figure 5b. Helical CT of liver and right kidney injury. (a) Transverse scan shows a low-attenuating laceration (black arrow) of the right lobe of the liver in a patient who suffered right-sided blunt abdominal trauma. A small amount of hemoperitoneum (white arrows) can be seen around the right lobe of liver and behind the spleen. (b) Slightly lower transverse scan in the same patient shows an additional laceration of the right kidney (black arrow) with hemorrhage (H) in the right perirenal space. Hemoperitoneum (white arrow) can be seen adjacent to the liver.

View larger version (155K): [in a new window]   Figure 6a. Helical CT of splenic fracture and left renal trauma. (a) Transverse section obtained in a patient who experienced blunt left abdominal trauma with a fracture (straight arrow) of the spleen and lack of perfusion of the posterior splenic fragment. Hemorrhage is seen in the perisplenic space (curved arrow) and in the left perirenal space (H); there is no perfusion of the upper pole of the left kidney. (b) Slightly lower transverse scan shows hemorrhage (H) in the left perirenal space and further signs of the left renal artery injury; only a small segment (arrow) of the posterior left kidney is perfused.

View larger version (152K): [in a new window]   Figure 6b. Helical CT of splenic fracture and left renal trauma. (a) Transverse section obtained in a patient who experienced blunt left abdominal trauma with a fracture (straight arrow) of the spleen and lack of perfusion of the posterior splenic fragment. Hemorrhage is seen in the perisplenic space (curved arrow) and in the left perirenal space (H); there is no perfusion of the upper pole of the left kidney. (b) Slightly lower transverse scan shows hemorrhage (H) in the left perirenal space and further signs of the left renal artery injury; only a small segment (arrow) of the posterior left kidney is perfused.

View larger version (174K): [in a new window]   Figure 7a. Helical CT of traumatic avulsion of the gallbladder. (a) Transverse scan shows hemorrhage in the gallbladder bed with a point of active bleeding; arrow indicates extravasation of IV contrast material. Hemoperitoneum (and probably also bile) can be identified lateral to the right lobe of liver and in the Morison pouch (H). (b) Slightly lower transverse scan shows the gallbladder (arrow) located inferior to its fossa, surrounded by hemoperitoneum. The enhancement of the gallbladder wall indicates that the cystic artery remains intact. (c) Coronal reformation confirms traumatic avulsion of the gallbladder (white arrows) from the gallbladder fossa (black arrows).

View larger version (169K): [in a new window]   Figure 7b. Helical CT of traumatic avulsion of the gallbladder. (a) Transverse scan shows hemorrhage in the gallbladder bed with a point of active bleeding; arrow indicates extravasation of IV contrast material. Hemoperitoneum (and probably also bile) can be identified lateral to the right lobe of liver and in the Morison pouch (H). (b) Slightly lower transverse scan shows the gallbladder (arrow) located inferior to its fossa, surrounded by hemoperitoneum. The enhancement of the gallbladder wall indicates that the cystic artery remains intact. (c) Coronal reformation confirms traumatic avulsion of the gallbladder (white arrows) from the gallbladder fossa (black arrows).

View larger version (139K): [in a new window]   Figure 7c. Helical CT of traumatic avulsion of the gallbladder. (a) Transverse scan shows hemorrhage in the gallbladder bed with a point of active bleeding; arrow indicates extravasation of IV contrast material. Hemoperitoneum (and probably also bile) can be identified lateral to the right lobe of liver and in the Morison pouch (H). (b) Slightly lower transverse scan shows the gallbladder (arrow) located inferior to its fossa, surrounded by hemoperitoneum. The enhancement of the gallbladder wall indicates that the cystic artery remains intact. (c) Coronal reformation confirms traumatic avulsion of the gallbladder (white arrows) from the gallbladder fossa (black arrows).

View larger version (126K): [in a new window]   Figure 8a. Helical CT of mesenteric injury and Chance fracture. (a) Transverse scan obtained in an automobile accident victim who was wearing a lap-type seat belt. Hemoperitoneum (H) was identified adjacent to the liver and spleen. No parenchymal organ injury was seen, and there were no signs of bowel rupture. (b) Slightly lower scan showed a fracture (black arrow) of a lumbar vertebra. Fluid is shown around the aorta and inferior vena cava (white arrows). Laparotomy identified a mesenteric injury with venous bleeding. (c) Targeted lumbar spine CT scan shows fractures of the posterior vertebral body (straight black arrows) and left lamina (curved arrow). (d) Sagittal reformation confirms a Chance fracture (arrow) extending horizontally through the pars interarticularis and pedicles and then extending anteroinferiorly through the posterior vertebral body.

View larger version (127K): [in a new window]   Figure 8b. Helical CT of mesenteric injury and Chance fracture. (a) Transverse scan obtained in an automobile accident victim who was wearing a lap-type seat belt. Hemoperitoneum (H) was identified adjacent to the liver and spleen. No parenchymal organ injury was seen, and there were no signs of bowel rupture. (b) Slightly lower scan showed a fracture (black arrow) of a lumbar vertebra. Fluid is shown around the aorta and inferior vena cava (white arrows). Laparotomy identified a mesenteric injury with venous bleeding. (c) Targeted lumbar spine CT scan shows fractures of the posterior vertebral body (straight black arrows) and left lamina (curved arrow). (d) Sagittal reformation confirms a Chance fracture (arrow) extending horizontally through the pars interarticularis and pedicles and then extending anteroinferiorly through the posterior vertebral body.

View larger version (182K): [in a new window]   Figure 8c. Helical CT of mesenteric injury and Chance fracture. (a) Transverse scan obtained in an automobile accident victim who was wearing a lap-type seat belt. Hemoperitoneum (H) was identified adjacent to the liver and spleen. No parenchymal organ injury was seen, and there were no signs of bowel rupture. (b) Slightly lower scan showed a fracture (black arrow) of a lumbar vertebra. Fluid is shown around the aorta and inferior vena cava (white arrows). Laparotomy identified a mesenteric injury with venous bleeding. (c) Targeted lumbar spine CT scan shows fractures of the posterior vertebral body (straight black arrows) and left lamina (curved arrow). (d) Sagittal reformation confirms a Chance fracture (arrow) extending horizontally through the pars interarticularis and pedicles and then extending anteroinferiorly through the posterior vertebral body.

View larger version (196K): [in a new window]   Figure 8d. Helical CT of mesenteric injury and Chance fracture. (a) Transverse scan obtained in an automobile accident victim who was wearing a lap-type seat belt. Hemoperitoneum (H) was identified adjacent to the liver and spleen. No parenchymal organ injury was seen, and there were no signs of bowel rupture. (b) Slightly lower scan showed a fracture (black arrow) of a lumbar vertebra. Fluid is shown around the aorta and inferior vena cava (white arrows). Laparotomy identified a mesenteric injury with venous bleeding. (c) Targeted lumbar spine CT scan shows fractures of the posterior vertebral body (straight black arrows) and left lamina (curved arrow). (d) Sagittal reformation confirms a Chance fracture (arrow) extending horizontally through the pars interarticularis and pedicles and then extending anteroinferiorly through the posterior vertebral body.

View larger version (141K): [in a new window]   Figure 9a. Helical CT of ureteral stone. (a) Transverse section from a nonenhanced helical CT scan shows slight enlargement of the right kidney and dilatation of the right intrarenal collecting system (arrow). (b) Slightly lower transverse section shows perinephric and periureteral fat stranding (black arrow) on the right; the normal left ureter is indicated by the white arrow. (c) Transverse section, just below the kidneys, shows a stone (arrow) in the proximal right ureter with edema of the ureteral wall and periureteral stranding. (d) Coronal reformation shows the stone (arrow) within an obstructed proximal right ureter.

View larger version (137K): [in a new window]   Figure 9b. Helical CT of ureteral stone. (a) Transverse section from a nonenhanced helical CT scan shows slight enlargement of the right kidney and dilatation of the right intrarenal collecting system (arrow). (b) Slightly lower transverse section shows perinephric and periureteral fat stranding (black arrow) on the right; the normal left ureter is indicated by the white arrow. (c) Transverse section, just below the kidneys, shows a stone (arrow) in the proximal right ureter with edema of the ureteral wall and periureteral stranding. (d) Coronal reformation shows the stone (arrow) within an obstructed proximal right ureter.

View larger version (148K): [in a new window]   Figure 9c. Helical CT of ureteral stone. (a) Transverse section from a nonenhanced helical CT scan shows slight enlargement of the right kidney and dilatation of the right intrarenal collecting system (arrow). (b) Slightly lower transverse section shows perinephric and periureteral fat stranding (black arrow) on the right; the normal left ureter is indicated by the white arrow. (c) Transverse section, just below the kidneys, shows a stone (arrow) in the proximal right ureter with edema of the ureteral wall and periureteral stranding. (d) Coronal reformation shows the stone (arrow) within an obstructed proximal right ureter.

View larger version (167K): [in a new window]   Figure 9d. Helical CT of ureteral stone. (a) Transverse section from a nonenhanced helical CT scan shows slight enlargement of the right kidney and dilatation of the right intrarenal collecting system (arrow). (b) Slightly lower transverse section shows perinephric and periureteral fat stranding (black arrow) on the right; the normal left ureter is indicated by the white arrow. (c) Transverse section, just below the kidneys, shows a stone (arrow) in the proximal right ureter with edema of the ureteral wall and periureteral stranding. (d) Coronal reformation shows the stone (arrow) within an obstructed proximal right ureter.

View larger version (147K): [in a new window]   Figure 10. Helical CT of a normal appendix. Helical CT scan obtained with rectally administered contrast material shows a normal appendix (arrow) filling with contrast material and adjacent to a well-opacified cecum (C).

View larger version (147K): [in a new window]   Figure 11a. Helical CT scans obtained in two patients with appendicitis. (a) The abnormal appendix (arrows) does not fill with rectally administered contrast material. It is dilated, measures 10 mm in diameter, and is surrounded by periappendiceal fat stranding and inflammation. (b) Abnormal appendix in another patient. The appendix is kinked and imaged in cross section at two different sites (arrows). There is no contrast material opacification of the appendix. Rather, the appendix is pus-filled and dilated, with adjacent fat stranding.

View larger version (145K): [in a new window]   Figure 11b. Helical CT scans obtained in two patients with appendicitis. (a) The abnormal appendix (arrows) does not fill with rectally administered contrast material. It is dilated, measures 10 mm in diameter, and is surrounded by periappendiceal fat stranding and inflammation. (b) Abnormal appendix in another patient. The appendix is kinked and imaged in cross section at two different sites (arrows). There is no contrast material opacification of the appendix. Rather, the appendix is pus-filled and dilated, with adjacent fat stranding.

View larger version (181K): [in a new window]   Figure 12a. Helical CT of sigmoid diverticulitis. (a) Helical scan obtained with rectally administered contrast material shows thickening of the sigmoid colon wall (straight arrow) with inflammatory stranding (curved arrow) in the adjacent mesenteric fat. (b) Helical CT scan obtained in another patient with sigmoid diverticulitis. Also seen is marked thickening of the sigmoid colon wall (arrow) with extensive surrounding inflammation in the mesenteric fat. Free fluid (F) is seen adjacent to the diseased segment of colon.

View larger version (195K): [in a new window]   Figure 12b. Helical CT of sigmoid diverticulitis. (a) Helical scan obtained with rectally administered contrast material shows thickening of the sigmoid colon wall (straight arrow) with inflammatory stranding (curved arrow) in the adjacent mesenteric fat. (b) Helical CT scan obtained in another patient with sigmoid diverticulitis. Also seen is marked thickening of the sigmoid colon wall (arrow) with extensive surrounding inflammation in the mesenteric fat. Free fluid (F) is seen adjacent to the diseased segment of colon.

View larger version (150K): [in a new window]   Figure 13. Helical CT of leaking abdominal aortic aneurysm. Transverse section obtained just below the kidneys shows a large aortic aneurysm (A) with retroperitoneal hemorrhage (H).

View larger version (123K): [in a new window]   Figure 14. CT angiogram of abdominal aortic aneurysm. Three-dimensional model shows that the aneurysm (arrows) begins below patent celiac (C), superior mesenteric (S), and renal (R) arteries and does not extend beyond the aortic bifurcation into the common iliac (I) arteries. The inferior mesenteric artery is not opacified.

View larger version (144K): [in a new window]   Figure 15a. Helical CT of facial fractures. Left frontal fracture, a left zygoma complex fracture, and a left nasal fracture resulting from a motor vehicle accident. (a) Transverse section, midorbital level, shows a medially displaced left nasal fracture (open arrow) and a fracture at the zygomaticosphenoid suture (straight arrow), a component of the zygoma complex fracture. Orbital emphysema (curved arrow) is present on the left side. (b) Transverse section, maxillary sinus level, shows three components (arrows) of the left zygoma complex fracture: fractures of the anterior (1) and posterolateral (2) walls of the maxillary sinus at the zygomaticomaxillary sutures and at the zygomaticotemporal suture (3) of the zygomatic arch. Blood is seen in both maxillary sinuses. (c) Coronal section, through the orbits, shows the frontal bone fractures (black arrows) and zygoma complex fractures (white arrow). (d) Three-dimensional reformation obtained in the Waters projection shows the frontal fractures (curved arrows), the medially displaced left nasal fracture (small straight arrow), and the zygoma complex fracture (large straight arrows). (e) Three-dimensional reformation obtained from the left lateral surface shows that the zygomatic bone (Z) is posteriorly displaced at its fracture line (large straight arrows) through the anterior wall of the left maxillary sinus. The frontal fractures (curved arrows) and left nasal fracture (small straight arrow) are again visible.

View larger version (176K): [in a new window]   Figure 15b. Helical CT of facial fractures. Left frontal fracture, a left zygoma complex fracture, and a left nasal fracture resulting from a motor vehicle accident. (a) Transverse section, midorbital level, shows a medially displaced left nasal fracture (open arrow) and a fracture at the zygomaticosphenoid suture (straight arrow), a component of the zygoma complex fracture. Orbital emphysema (curved arrow) is present on the left side. (b) Transverse section, maxillary sinus level, shows three components (arrows) of the left zygoma complex fracture: fractures of the anterior (1) and posterolateral (2) walls of the maxillary sinus at the zygomaticomaxillary sutures and at the zygomaticotemporal suture (3) of the zygomatic arch. Blood is seen in both maxillary sinuses. (c) Coronal section, through the orbits, shows the frontal bone fractures (black arrows) and zygoma complex fractures (white arrow). (d) Three-dimensional reformation obtained in the Waters projection shows the frontal fractures (curved arrows), the medially displaced left nasal fracture (small straight arrow), and the zygoma complex fracture (large straight arrows). (e) Three-dimensional reformation obtained from the left lateral surface shows that the zygomatic bone (Z) is posteriorly displaced at its fracture line (large straight arrows) through the anterior wall of the left maxillary sinus. The frontal fractures (curved arrows) and left nasal fracture (small straight arrow) are again visible.

View larger version (175K): [in a new window]   Figure 15c. Helical CT of facial fractures. Left frontal fracture, a left zygoma complex fracture, and a left nasal fracture resulting from a motor vehicle accident. (a) Transverse section, midorbital level, shows a medially displaced left nasal fracture (open arrow) and a fracture at the zygomaticosphenoid suture (straight arrow), a component of the zygoma complex fracture. Orbital emphysema (curved arrow) is present on the left side. (b) Transverse section, maxillary sinus level, shows three components (arrows) of the left zygoma complex fracture: fractures of the anterior (1) and posterolateral (2) walls of the maxillary sinus at the zygomaticomaxillary sutures and at the zygomaticotemporal suture (3) of the zygomatic arch. Blood is seen in both maxillary sinuses. (c) Coronal section, through the orbits, shows the frontal bone fractures (black arrows) and zygoma complex fractures (white arrow). (d) Three-dimensional reformation obtained in the Waters projection shows the frontal fractures (curved arrows), the medially displaced left nasal fracture (small straight arrow), and the zygoma complex fracture (large straight arrows). (e) Three-dimensional reformation obtained from the left lateral surface shows that the zygomatic bone (Z) is posteriorly displaced at its fracture line (large straight arrows) through the anterior wall of the left maxillary sinus. The frontal fractures (curved arrows) and left nasal fracture (small straight arrow) are again visible.

View larger version (183K): [in a new window]   Figure 15d. Helical CT of facial fractures. Left frontal fracture, a left zygoma complex fracture, and a left nasal fracture resulting from a motor vehicle accident. (a) Transverse section, midorbital level, shows a medially displaced left nasal fracture (open arrow) and a fracture at the zygomaticosphenoid suture (straight arrow), a component of the zygoma complex fracture. Orbital emphysema (curved arrow) is present on the left side. (b) Transverse section, maxillary sinus level, shows three components (arrows) of the left zygoma complex fracture: fractures of the anterior (1) and posterolateral (2) walls of the maxillary sinus at the zygomaticomaxillary sutures and at the zygomaticotemporal suture (3) of the zygomatic arch. Blood is seen in both maxillary sinuses. (c) Coronal section, through the orbits, shows the frontal bone fractures (black arrows) and zygoma complex fractures (white arrow). (d) Three-dimensional reformation obtained in the Waters projection shows the frontal fractures (curved arrows), the medially displaced left nasal fracture (small straight arrow), and the zygoma complex fracture (large straight arrows). (e) Three-dimensional reformation obtained from the left lateral surface shows that the zygomatic bone (Z) is posteriorly displaced at its fracture line (large straight arrows) through the anterior wall of the left maxillary sinus. The frontal fractures (curved arrows) and left nasal fracture (small straight arrow) are again visible.

View larger version (160K): [in a new window]   Figure 15e. Helical CT of facial fractures. Left frontal fracture, a left zygoma complex fracture, and a left nasal fracture resulting from a motor vehicle accident. (a) Transverse section, midorbital level, shows a medially displaced left nasal fracture (open arrow) and a fracture at the zygomaticosphenoid suture (straight arrow), a component of the zygoma complex fracture. Orbital emphysema (curved arrow) is present on the left side. (b) Transverse section, maxillary sinus level, shows three components (arrows) of the left zygoma complex fracture: fractures of the anterior (1) and posterolateral (2) walls of the maxillary sinus at the zygomaticomaxillary sutures and at the zygomaticotemporal suture (3) of the zygomatic arch. Blood is seen in both maxillary sinuses. (c) Coronal section, through the orbits, shows the frontal bone fractures (black arrows) and zygoma complex fractures (white arrow). (d) Three-dimensional reformation obtained in the Waters projection shows the frontal fractures (curved arrows), the medially displaced left nasal fracture (small straight arrow), and the zygoma complex fracture (large straight arrows). (e) Three-dimensional reformation obtained from the left lateral surface shows that the zygomatic bone (Z) is posteriorly displaced at its fracture line (large straight arrows) through the anterior wall of the left maxillary sinus. The frontal fractures (curved arrows) and left nasal fracture (small straight arrow) are again visible.

View larger version (151K): [in a new window]   Figure 16a. Normal screening helical CT of the cervical spine. The transverse sections demonstrate the presence or absence of fractures. (a) Representative transverse section (3-mm collimation) at C1. (b) Representative transverse section at C7. (c) Representative sagittal reformation shows normal alignment at the midline. Sagittal reformations demonstrate best the presence or absence of alignment abnormalities. (d) Representative sagittal reformation at the right facet joints. Arrow indicates the facet joint between the inferior articulating facet of C2 (2) and the superior articulating facet of C3 (3).

View larger version (151K): [in a new window]   Figure 16b. Normal screening helical CT of the cervical spine. The transverse sections demonstrate the presence or absence of fractures. (a) Representative transverse section (3-mm collimation) at C1. (b) Representative transverse section at C7. (c) Representative sagittal reformation shows normal alignment at the midline. Sagittal reformations demonstrate best the presence or absence of alignment abnormalities. (d) Representative sagittal reformation at the right facet joints. Arrow indicates the facet joint between the inferior articulating facet of C2 (2) and the superior articulating facet of C3 (3).

View larger version (124K): [in a new window]   Figure 16c. Normal screening helical CT of the cervical spine. The transverse sections demonstrate the presence or absence of fractures. (a) Representative transverse section (3-mm collimation) at C1. (b) Representative transverse section at C7. (c) Representative sagittal reformation shows normal alignment at the midline. Sagittal reformations demonstrate best the presence or absence of alignment abnormalities. (d) Representative sagittal reformation at the right facet joints. Arrow indicates the facet joint between the inferior articulating facet of C2 (2) and the superior articulating facet of C3 (3).

View larger version (114K): [in a new window]   Figure 16d. Normal screening helical CT of the cervical spine. The transverse sections demonstrate the presence or absence of fractures. (a) Representative transverse section (3-mm collimation) at C1. (b) Representative transverse section at C7. (c) Representative sagittal reformation shows normal alignment at the midline. Sagittal reformations demonstrate best the presence or absence of alignment abnormalities. (d) Representative sagittal reformation at the right facet joints. Arrow indicates the facet joint between the inferior articulating facet of C2 (2) and the superior articulating facet of C3 (3).

View larger version (161K): [in a new window]   Figure 17a. Helical CT of an odontoid fracture. (a) Transverse section with 3-mm collimation and 3-mm image spacing shows a fracture (arrows) at the base of the odontoid process (type III odontoid fracture). (b) Sagittal reformation prepared from the 3-mm-collimation helical sections that were reconstructed at 1-mm image spacing. Note the odontoid fracture line (arrows). (c) Coronal reformation prepared from the 3-mm-collimation helical sections that were reconstructed at 1-mm image spacing. Note the odontoid fracture line (arrows).

View larger version (174K): [in a new window]   Figure 17b. Helical CT of an odontoid fracture. (a) Transverse section with 3-mm collimation and 3-mm image spacing shows a fracture (arrows) at the base of the odontoid process (type III odontoid fracture). (b) Sagittal reformation prepared from the 3-mm-collimation helical sections that were reconstructed at 1-mm image spacing. Note the odontoid fracture line (arrows). (c) Coronal reformation prepared from the 3-mm-collimation helical sections that were reconstructed at 1-mm image spacing. Note the odontoid fracture line (arrows).

View larger version (194K): [in a new window]   Figure 17c. Helical CT of an odontoid fracture. (a) Transverse section with 3-mm collimation and 3-mm image spacing shows a fracture (arrows) at the base of the odontoid process (type III odontoid fracture). (b) Sagittal reformation prepared from the 3-mm-collimation helical sections that were reconstructed at 1-mm image spacing. Note the odontoid fracture line (arrows). (c) Coronal reformation prepared from the 3-mm-collimation helical sections that were reconstructed at 1-mm image spacing. Note the odontoid fracture line (arrows).

View larger version (93K): [in a new window]   Figure 18a. Helical CT of unilateral facet dislocation. (a) Lateral conventional radiograph shows anterior spondylolisthesis (arrow) of C4 (4) on C5 (5). (b) Sagittal reformation through the right facet joints shows a unilateral C4-C5 facet dislocation without fracture. Note that the right inferior facet of C4 (4) is dislocated anterior to the right superior facet of C5 (5). (c) Three-dimensional reformation viewed from the right lateral surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). (d) Three-dimensional reformation viewed from the posterior surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). The superior facet (F) of C5 is now fully visible compared to the facet on the opposite side.

View larger version (69K): [in a new window]   Figure 18b. Helical CT of unilateral facet dislocation. (a) Lateral conventional radiograph shows anterior spondylolisthesis (arrow) of C4 (4) on C5 (5). (b) Sagittal reformation through the right facet joints shows a unilateral C4-C5 facet dislocation without fracture. Note that the right inferior facet of C4 (4) is dislocated anterior to the right superior facet of C5 (5). (c) Three-dimensional reformation viewed from the right lateral surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). (d) Three-dimensional reformation viewed from the posterior surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). The superior facet (F) of C5 is now fully visible compared to the facet on the opposite side.

View larger version (156K): [in a new window]   Figure 18c. Helical CT of unilateral facet dislocation. (a) Lateral conventional radiograph shows anterior spondylolisthesis (arrow) of C4 (4) on C5 (5). (b) Sagittal reformation through the right facet joints shows a unilateral C4-C5 facet dislocation without fracture. Note that the right inferior facet of C4 (4) is dislocated anterior to the right superior facet of C5 (5). (c) Three-dimensional reformation viewed from the right lateral surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). (d) Three-dimensional reformation viewed from the posterior surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). The superior facet (F) of C5 is now fully visible compared to the facet on the opposite side.

View larger version (157K): [in a new window]   Figure 18d. Helical CT of unilateral facet dislocation. (a) Lateral conventional radiograph shows anterior spondylolisthesis (arrow) of C4 (4) on C5 (5). (b) Sagittal reformation through the right facet joints shows a unilateral C4-C5 facet dislocation without fracture. Note that the right inferior facet of C4 (4) is dislocated anterior to the right superior facet of C5 (5). (c) Three-dimensional reformation viewed from the right lateral surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). (d) Three-dimensional reformation viewed from the posterior surface. The arrow indicates the site of dislocation. The cylinder-shaped C4 pillar (4) is shown dislocated anterior to the C5 pillar (5). The superior facet (F) of C5 is now fully visible compared to the facet on the opposite side.

View larger version (151K): [in a new window]   Figure 19a. Helical CT of lumbar spine burst fracture. (a) Anterior surface of the 3D CT model of an L1 (1) vertebral body fracture. (b) Right lateral surface of the 3D CT model of an L1 (1) vertebral body fracture. (c) Sagittal section of the 3D model clearly shows a large retropulsed fragment (arrows) extending into the vertebral canal. Compare the normal canal within the L2 vertebra below.

View larger version (163K): [in a new window]   Figure 19b. Helical CT of lumbar spine burst fracture. (a) Anterior surface of the 3D CT model of an L1 (1) vertebral body fracture. (b) Right lateral surface of the 3D CT model of an L1 (1) vertebral body fracture. (c) Sagittal section of the 3D model clearly shows a large retropulsed fragment (arrows) extending into the vertebral canal. Compare the normal canal within the L2 vertebra below.

View larger version (164K): [in a new window]   Figure 19c. Helical CT of lumbar spine burst fracture. (a) Anterior surface of the 3D CT model of an L1 (1) vertebral body fracture. (b) Right lateral surface of the 3D CT model of an L1 (1) vertebral body fracture. (c) Sagittal section of the 3D model clearly shows a large retropulsed fragment (arrows) extending into the vertebral canal. Compare the normal canal within the L2 vertebra below.

View larger version (189K): [in a new window]   Figure 20a. Helical CT of a comminuted intraarticular distal radial fracture. (a) Anteroposterior radiograph shows a subtle, nondisplaced fracture (arrow) of the distal radius. (b) Transverse CT scan through the distal radius shows several fracture lines (arrows) and fracture fragments. The ulna is intact and a plaster splint is shown in place. (c) Coronal reformation confirms several fracture lines (arrows), including intraarticular fractures.

View larger version (165K): [in a new window]   Figure 20b. Helical CT of a comminuted intraarticular distal radial fracture. (a) Anteroposterior radiograph shows a subtle, nondisplaced fracture (arrow) of the distal radius. (b) Transverse CT scan through the distal radius shows several fracture lines (arrows) and fracture fragments. The ulna is intact and a plaster splint is shown in place. (c) Coronal reformation confirms several fracture lines (arrows), including intraarticular fractures.

View larger version (121K): [in a new window]   Figure 20c. Helical CT of a comminuted intraarticular distal radial fracture. (a) Anteroposterior radiograph shows a subtle, nondisplaced fracture (arrow) of the distal radius. (b) Transverse CT scan through the distal radius shows several fracture lines (arrows) and fracture fragments. The ulna is intact and a plaster splint is shown in place. (c) Coronal reformation confirms several fracture lines (arrows), including intraarticular fractures.

View larger version (177K): [in a new window]   Figure 21a. Helical CT of tibial plateau fracture. (a) Transverse section of a tibial plateau fracture that has fractured the plateau into medial (M), lateral (L), and posterior (P) segments. (b) Coronal reformation shows marked inferior displacement of the medial (M) plateau segment. The lateral portion of the lateral plateau (L) is intact and remains connected to and continuous with the tibial shaft. (c) Sagittal reformation shows marked inferior displacement of the posterior (P) segment of the plateau. (d) Three-dimensional reformation viewed from the anterior surface. The lateral plateau (L) is in normal position; the medial (M) plateau is depressed. (e) Three-dimensional reformation viewed from the posterior surface. The lateral plateau (L) is in normal position; the medial plateau (M) and posterior fracture segment (P) are depressed.

View larger version (172K): [in a new window]   Figure 21b. Helical CT of tibial plateau fracture. (a) Transverse section of a tibial plateau fracture that has fractured the plateau into medial (M), lateral (L), and posterior (P) segments. (b) Coronal reformation shows marked inferior displacement of the medial (M) plateau segment. The lateral portion of the lateral plateau (L) is intact and remains connected to and continuous with the tibial shaft. (c) Sagittal reformation shows marked inferior displacement of the posterior (P) segment of the plateau. (d) Three-dimensional reformation viewed from the anterior surface. The lateral plateau (L) is in normal position; the medial (M) plateau is depressed. (e) Three-dimensional reformation viewed from the posterior surface. The lateral plateau (L) is in normal position; the medial plateau (M) and posterior fracture segment (P) are depressed.

View larger version (161K): [in a new window]   Figure 21c. Helical CT of tibial plateau fracture. (a) Transverse section of a tibial plateau fracture that has fractured the plateau into medial (M), lateral (L), and posterior (P) segments. (b) Coronal reformation shows marked inferior displacement of the medial (M) plateau segment. The lateral portion of the lateral plateau (L) is intact and remains connected to and continuous with the tibial shaft. (c) Sagittal reformation shows marked inferior displacement of the posterior (P) segment of the plateau. (d) Three-dimensional reformation viewed from the anterior surface. The lateral plateau (L) is in normal position; the medial (M) plateau is depressed. (e) Three-dimensional reformation viewed from the posterior surface. The lateral plateau (L) is in normal position; the medial plateau (M) and posterior fracture segment (P) are depressed.

View larger version (126K): [in a new window]   Figure 21d. Helical CT of tibial plateau fracture. (a) Transverse section of a tibial plateau fracture that has fractured the plateau into medial (M), lateral (L), and posterior (P) segments. (b) Coronal reformation shows marked inferior displacement of the medial (M) plateau segment. The lateral portion of the lateral plateau (L) is intact and remains connected to and continuous with the tibial shaft. (c) Sagittal reformation shows marked inferior displacement of the posterior (P) segment of the plateau. (d) Three-dimensional reformation viewed from the anterior surface. The lateral plateau (L) is in normal position; the medial (M) plateau is depressed. (e) Three-dimensional reformation viewed from the posterior surface. The lateral plateau (L) is in normal position; the medial plateau (M) and posterior fracture segment (P) are depressed.

View larger version (126K): [in a new window]   Figure 21e. Helical CT of tibial plateau fracture. (a) Transverse section of a tibial plateau fracture that has fractured the plateau into medial (M), lateral (L), and posterior (P) segments. (b) Coronal reformation shows marked inferior displacement of the medial (M) plateau segment. The lateral portion of the lateral plateau (L) is intact and remains connected to and continuous with the tibial shaft. (c) Sagittal reformation shows marked inferior displacement of the posterior (P) segment of the plateau. (d) Three-dimensional reformation viewed from the anterior surface. The lateral plateau (L) is in normal position; the medial (M) plateau is depressed. (e) Three-dimensional reformation viewed from the posterior surface. The lateral plateau (L) is in normal position; the medial plateau (M) and posterior fracture segment (P) are depressed.

View larger version (151K): [in a new window]   Figure 22a. Helical CT of acute stroke. (a) Nonenhanced CT scan obtained in a patient with suspected stroke does not show any signs of bleeding or other acute abnormality. (b) Helical CT scan obtained with IV contrast material shows decreased blood flow to the left middle cerebral artery distribution (between arrows). (c) CT arteriogram at the circle of Willis shows an occlusion (arrow) of the left middle cerebral artery.

View larger version (154K): [in a new window]   Figure 22b. Helical CT of acute stroke. (a) Nonenhanced CT scan obtained in a patient with suspected stroke does not show any signs of bleeding or other acute abnormality. (b) Helical CT scan obtained with IV contrast material shows decreased blood flow to the left middle cerebral artery distribution (between arrows). (c) CT arteriogram at the circle of Willis shows an occlusion (arrow) of the left middle cerebral artery.

View larger version (136K): [in a new window]   Figure 22c. Helical CT of acute stroke. (a) Nonenhanced CT scan obtained in a patient with suspected stroke does not show any signs of bleeding or other acute abnormality. (b) Helical CT scan obtained with IV contrast material shows decreased blood flow to the left middle cerebral artery distribution (between arrows). (c) CT arteriogram at the circle of Willis shows an occlusion (arrow) of the left middle cerebral artery.