Evaluation of Blunt Abdominal Trauma Using PACS-Based 2D and 3D MDCT Reformations of the Lumbar Spine and Pelvis

Brian C. Lucey; Joshua W. Stuhlfaut; Aaron R. Hochberg; Jose C. Varghese; Jorge A. Soto

Disclosures

Am J Roentgenol. 2005;185(6):1435-1440. 

In This Article

Materials and Methods

Approval from our institutional review board was obtained. We reviewed our database of trauma cases and retrieved the records of 156 consecutive patients who underwent both abdominal or pelvic CT and radiography of the pelvis or the lumbar spine after sustaining blunt abdominal trauma (107 males and 49 females; mean age, 39 years; age range, 5-93 years) over a 9-month period (January 2002 to September 2002). All patients had radiographs of the pelvis, according to standard departmental trauma protocol. Seventy-four patients (47%) had radiographs of the lumbar spine also. In all cases, both the CT scans and radiographs were requested by the trauma team. The radiographs of the lumbar spine were ordered for patients when the trauma team believed that there was high clinical index of suspicion for lumbar spine fracture.

All CT examinations were performed using a 4-MDCT scanner (MX 8000, Philips Medical Systems). Imaging parameters included a slice collimation of 3.2 mm reconstructed at 1.6-mm intervals, 140 kVp, and 200-220 mAs. IV contrast material (300 mg I/mL iohexol, 100 mL) was given in all patients at a rate of 2.5-3.0 mL/sec through a 20-gauge line, ideally placed in the antecubital fossa. No oral contrast material was given according to our standard departmental trauma protocol.[15]

Ten (13%) of the 74 patients had a repeat CT examination using 2-mm collimation dedicated to a segment of the lumbar spine that was considered abnormal on the initial radiographs or on the initial abdominal CT scan. Twelve (8%) of the 156 patients underwent repeat dedicated CT scanning of the pelvis using 2-mm collimation at the request of the orthopedic team. The repeat lumbar spine CT scans were ordered for evaluation of the spinal canal at the site of injury and to specifically identify bone fragments retropulsed toward the spinal canal. The repeat pelvis CT scans were ordered to evaluate for bone fragments within the hip joints.

A single portable anteroposterior view of the pelvis was obtained in the trauma room on admission in all patients. Radiography of the lumbar spine ideally included an anteroposterior view and a lateral view. Both views were obtained in 70 (95%) of 74 patients. A single view was obtained in the remaining four patients. Three of these views were lateral and one was anteroposterior. This discrepancy resulted from patient instability while obtaining the images and the second view could not be obtained. Sixty-one (82%) of the 74 patients had radiographs obtained as the initial evaluation of the lumbar spine. Thirteen (18%) of the 74 patients had radiography of the lumbar spine performed after the initial abdominal and pelvic CT examination was performed. Nine patients (12%) had repeat radiography after CT because the initial radiographs were considered inadequate for excluding a lumbar spine fracture (Figs.1-3)

62-year-old man with large fracture through L5 vertebral body.A, Lateral radiograph of lumbar spine. No fracture was identified during image analysis session.B, Sagittal reformatted image of abdominopelvic CT scan shows large fracture through L5 vertebral body that was not visible on radiograph (A).C, Axial CT image shows fracture through transverse process of L4 on right that was not visible on radiograph (A).

62-year-old man with large fracture through L5 vertebral body.A, Lateral radiograph of lumbar spine. No fracture was identified during image analysis session.B, Sagittal reformatted image of abdominopelvic CT scan shows large fracture through L5 vertebral body that was not visible on radiograph (A).C, Axial CT image shows fracture through transverse process of L4 on right that was not visible on radiograph (A).

62-year-old man with large fracture through L5 vertebral body.A, Lateral radiograph of lumbar spine. No fracture was identified during image analysis session.B, Sagittal reformatted image of abdominopelvic CT scan shows large fracture through L5 vertebral body that was not visible on radiograph (A).C, Axial CT image shows fracture through transverse process of L4 on right that was not visible on radiograph (A).

28-year-old man with shattered lumbar vertebra.A, Radiograph obtained after abdominal CT scan shows deformity of spine, which suggests compression fractures that are difficult to define. Lateral radiograph could not be obtained because patient became unstable and was transferred to operating room.B, Sagittal reformatted image of abdominopelvic CT scan clearly shows shattered lumbar vertebra with retropulsion of bone fragments into spinal canal.

28-year-old man with shattered lumbar vertebra.A, Radiograph obtained after abdominal CT scan shows deformity of spine, which suggests compression fractures that are difficult to define. Lateral radiograph could not be obtained because patient became unstable and was transferred to operating room.B, Sagittal reformatted image of abdominopelvic CT scan clearly shows shattered lumbar vertebra with retropulsion of bone fragments into spinal canal.

34-year-old man with anterior wedge-compression fracture of L4.A, Lateral radiograph of lumbar spine shows mild anterior wedge-compression fracture of L4.B, Sagittal reformatted image of abdominopelvic CT scan shows fracture through anterior part of vertebral body.C, Sagittal reformatted image of abdominopelvic CT scan shows unsuspected extent of fracture involving posterior wall of vertebral body.D, Coronal reformatted image of abdominopelvic CT scan shows comminuted nature of fracture.

34-year-old man with anterior wedge-compression fracture of L4.A, Lateral radiograph of lumbar spine shows mild anterior wedge-compression fracture of L4.B, Sagittal reformatted image of abdominopelvic CT scan shows fracture through anterior part of vertebral body.C, Sagittal reformatted image of abdominopelvic CT scan shows unsuspected extent of fracture involving posterior wall of vertebral body.D, Coronal reformatted image of abdominopelvic CT scan shows comminuted nature of fracture.

34-year-old man with anterior wedge-compression fracture of L4.A, Lateral radiograph of lumbar spine shows mild anterior wedge-compression fracture of L4.B, Sagittal reformatted image of abdominopelvic CT scan shows fracture through anterior part of vertebral body.C, Sagittal reformatted image of abdominopelvic CT scan shows unsuspected extent of fracture involving posterior wall of vertebral body.D, Coronal reformatted image of abdominopelvic CT scan shows comminuted nature of fracture.

34-year-old man with anterior wedge-compression fracture of L4.A, Lateral radiograph of lumbar spine shows mild anterior wedge-compression fracture of L4.B, Sagittal reformatted image of abdominopelvic CT scan shows fracture through anterior part of vertebral body.C, Sagittal reformatted image of abdominopelvic CT scan shows unsuspected extent of fracture involving posterior wall of vertebral body.D, Coronal reformatted image of abdominopelvic CT scan shows comminuted nature of fracture.

Twenty-eight patients (18%) had repeat anteroposterior radiographs of the pelvis after abdominopelvic CT was performed. An additional 67 patients (43%) had repeat three-view pelvic series including anteroposterior and both 45º oblique views (Judet views) performed after the initial CT scan. These films were obtained for a more complete evaluation of the acetabula.

CT images were reviewed at a PACS workstation by two radiologists, by consensus. Multiplanar and 3D reconstructions were obtained in all cases. These were obtained using a software package (Voxar 3D, Voxar Inc.) that is directly incorporated into the PACS workstations. This allows immediate online postprocessing of the raw data at the primary interpreting workstation without requiring the imaging data to be transferred to a separate stand-alone workstation. For interpretation of the CT data sets, the radiologists were allowed to use the axial images displayed with bone window settings (width, 3,200 H; level, 800 H), and were asked to use the postprocessing options available (multiplanar and volume-rendering reformations) as needed. However, we did not record the number of reformations that were generated by the radiologists. Radiographs were reviewed during a separate session approximately 4 weeks after the CT interpretation on a PACS workstation by the same two radiologists who were blinded to the CT results.

The presence or absence of lumbar spine and pelvic fractures was recorded for both interpretation sessions (CT scans and radiographs). Spinal fractures were divided into three groups: vertebral body fractures, transverse process fractures, and spinous process fractures. Pelvic fractures were classified and documented as involving the pubic rami, iliac bones, acetabula, and sacrum or symphysis pubis diastasis. For statistical purposes, we evaluated the kappa value between the two observers for each segment of the lumbar spine and pelvis in addition to comparing the kappa values for the total number of fractures identified.

For this study, no pathologic gold standard was used because this would be impractical. For the purposes of this study, the CT scans were obtained to represent the gold standard because we believed that, given the reported reliability of MDCT, no significant fractures would be missed. If available, the repeat dedicated CT scans were also used in conjunction with the initial CT scans as a gold standard. We acknowledge the implicit limitations that this places on the study.

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