To reduce routine computed tomographic angiography for thoracic aortic injury assessment in level II blunt trauma patients using three mediastinal signs on the initial chest radiograph: a preliminary report.

PURPOSE: CTA is routinely ordered on level II blunt thoraco-abdominally injured patients for assessment of injury to the thoracic aorta. The vast majority of such assessments are negative. The question being asked is, Does the accurate interpretation of the three mediastinal signs permit reliable determination of which patients need CTA for aortic assessment? The purpose of this investigation was to evaluate the role of three specifically selected mediastinal anatomic signs on the initial supine chest radiograph (CXR) of adult level II blunt thoraco-abdominally injured patients for the presence or absence of a mediastinal hematoma. The presence of a mediastinal hematoma is typically used as an indicator for computed tomographic angiography (CTA). The three mediastinal signs are the right para-tracheal stripe (RPTS), left para-spinal line (LPSL), and the left apical extra-pleural area (LAPA). MATERIALS AND METHODS: The patient triage designation (level II trauma) was made by the attending physician at the time of admission. The initial CXR image and the CTA report of the 197 adult blunt level II thoraco-abdominally injured patients obtained on the day of admission were compared. The CXR of each of the 197 patients was independently assessed by each of four observers specifically for the status of the three mediastinal signs. Each observer was blinded to the CTA report until after the status of the three mediastinal sign evaluation had been determined. Two or three of the mediastinal signs being positive were required to determine that the CXR was positive for a mediastinal hematoma. RESULTS: Two or three of the selected mediastinal signs were normal in 192 (97.5%) patients. None of these patients had either a mediastinal hematoma or a major aortic injury on CTA. In each of the remaining five (2.5%) patients, two or three of the mediastinal signs were abnormal. Each of these patients had a mediastinal hematoma and a major thoracic aortic injury on CTA. CONCLUSIONS: This preliminary study suggests that the accurate interpretation of the three specifically selected mediastinal signs on the initial supine CXR of adult level II blunt thoraco-abdominally injured patients could reduce the need for routine CTA for thoracic aortic injury assessment, and requires verification by an additional study.

Toward Reduction of Post-Hospital Admission Death Rate Caused by Acute Traumatic Aortic Tear.

BACKGROUND: Terminology and classifications are the vehicles by which pathologic conditions are identified and understood. It is critically important for the patient admitted with suspected blunt thoracic aortic injury that admitting physicians have a thorough knowledge of acute traumatic aortic tear and its natural history. OBJECTIVES: The objectives of this review were as follows: (1) to introduce a pathology-based terminology and classification of acute traumatic aortic injuries that unambiguously defines each, and (2) to emphasize the clinical relevance of acute traumatic tear to post-hospital admission deaths in blunt thoracoabdominally injured patients. METHODS: This is a literature review of 32 refereed articles pertaining to acute traumatic thoracic aortic injury published from 1957 to the present. RESULTS: The terminology used to describe aortic injury is inconsistent. Several terms are often loosely interchanged: tear, laceration, transection, and rupture. Furthermore, classifications of aortic injuries have been proposed based on microscopic or gross pathologic or computed tomography scan results. While microscopically-based classifications have little or no clinical application, a classification based on gross pathology provides information useful for aortic injury prognosis and management. CONCLUSION: Reduction of post-hospital death caused by acute aortic tear requires knowledge and understanding of the pathology of acute traumatic aortic tear and its natural history. Such understanding of pathology of acute traumatic aortic tear and its natural history is enhanced by terminology that defines the aortic injury. Therefore, we present our proposed terminology and classification of acute traumatic injuries.

Superior mesenteric artery pseudoaneurysm after blunt abdominal trauma.

True aneurysms and pseudoaneurysms of the visceral arteries are uncommon. Visceral artery aneurysms (VAAs) represent 0.1-0.2% of all vascular aneurysms and were also found in 0.1% of autopsies. VAAs most commonly affect the splenic (60%), hepatic (20%), and superior mesenteric (9%) arteries. Mesenteric injury caused by blunt abdominal trauma is relatively rare. A 30-year-old man arrived at our trauma hospital and was found to have a traumatic pseudoaneurysm of the superior mesenteric artery (SMA) after a motor vehicle collision. To date, only 10 visceral arterial pseudoaneurysms have been reported in the literature. We present an 11th case of a pseudoaneurysm involving the SMA after blunt abdominal trauma.

Acetabular fractures revisited: a new CT-based classification.

The objective of this investigation is to provide a new CT-based classification of acetabular fractures. The axial CT scans of 112 randomly selected acetabular fracture patients admitted to a Level 1 trauma center between January 1998 and December 2000 were analyzed by an experienced orthopedic trauma surgeon and two experienced emergency radiologists. When available, 3D reformatted images were analyzed as well. The fracture pattern for each acetabular fracture with respect to column(s) wall(s) and extension superiorly and/or inferiorly from the acetabulum, when present, was recorded. Fracture comminution was not a defining characteristic. Analysis of the acetabular fracture patterns showed that each fracture fell into one of four broad categories: Category 0--wall only; Category 1--single column; Category 2--both columns, with extension subcategories of (A) no extension, (B) superior extension only, (C) inferior extension only, and (D) both superior and inferior extension; and Category 3--the "floating" acetabulum. The axial CT display of acetabular fracture patterns provides a basis for a classification of acetabular fractures that is simple, unambiguous, readily understood by both radiologists and orthopedic surgeons, and provides clear direction for both diagnosis and surgical treatment planning. Category and subcategory fracture specificity creates a mechanism for intra- and interdepartmental postoperative assessment of any of the individual acetabular fracture types.

Acetabular fractures revisited: part 1, redefinition of the Letournel anterior column.

OBJECTIVE: The objective of part 1 of this study is to redefine the Letournel anterior column on the basis of developmental and adult pelvic skeletal anatomy. MATERIALS AND METHODS: The axial CT scans of 112 randomly selected patients with acetabular fracture or fracture-dislocations admitted to a level I trauma center between January 1998 and December 2000 were analyzed by an experienced orthopedic trauma surgeon and two experienced emergency radiologists. When available, 3D reformatted images were analyzed as well. The discrepancy between the Letournel definition of the anterior and posterior columns became readily apparent. Standard text books of anatomy and surgical anatomy were referenced relative to the embryologic and adult components of the acetabulum. RESULTS: The anterior column is redefined with its superior border being the anatomic arcuate and iliopectineal lines, thereby coinciding with the superior border (arcuate line) of the Letournel posterior column. CONCLUSION: Redefinition of the anterior column eliminates diagnostic ambiguity of the Letournel elementary anterior column fracture as well as the Letournel associated anterior column or wall with hemitransverse fracture. The redefined anterior column is integral to the CT-based classification described in part 2 of our study.

Acetabular fractures revisited: part 2, a new CT-based classification.

OBJECTIVE: The objective of this investigation was to provide a new CT-based classification of acetabular fractures. MATERIALS AND METHODS: The axial CT scans of 112 randomly selected acetabular fractures in patients admitted to a level 1 trauma center between January 1998 and December 2000 were analyzed by an experienced orthopedic trauma surgeon and two experienced emergency radiologists. When available, 3D reformatted images were analyzed as well. The fracture pattern for each acetabular fracture, with respect to column walls and extension beyond the acetabulum, when present, was recorded. Fracture comminution was not a defining characteristic. RESULTS: Analysis of the 112 acetabular fracture patterns showed that each fracture fell into one of four broad categories. Category 0 included wall fractures only. Category I included acetabular fractures limited to a single (anterior or posterior) column. Category II fractures included those involving both the anterior and posterior columns; category II fractures were further subdivided into those with no fracture extension beyond the acetabulum, those with superior or inferior extension, and those with both superior and inferior extensions beyond the acetabulum. Category III fractures included only the "floating" acetabulum, which is defined as an acetabular fracture in which the acetabulum is separated from the axial skeleton both anteriorly and posteriorly. CONCLUSION: The axial CT display of acetabular fracture patterns provides a basis for a classification of acetabular fractures that is simple, unambiguous, readily understood by both radiologists and orthopedic surgeons and provides clear direction for both diagnosis and surgical treatment planning. Category and subcategory fracture specificity creates a mechanism for intra- and interdepartmental postoperative assessment of any of the individual acetabular fracture types.

Malalignment: signs and significance.

Malalignment of the vertebrae, in patients suspected of blunt spinal trauma, is the quintessential sign of spinal injury. Malalignment is obvious in displaced fractures and dislocations but is rarely considered in the diagnosis because of the obvious injury. In patients with more subtle injuries such as those limited to ligamentous structures, vertebral malalignment is the only radiographic sign that leads one to the recognition of the injury. Equally important is the fact that vertebral malalignment may be congenital and may be due to physiologic movement as well as radiographic patient positioning. Recognition of the pattern of traumatic malalignment as distinguished from the appearance of non-traumatic malalignment is essential to accurate radiologic diagnosis. Because malalignment is critical to the radiographic assessment of blunt cervical spine injury, this presentation is limited to the cervical spine. The format of the article includes signs of physiologic and traumatic malaignment as seen on antero-posterior and lateral radiographs of the cervico-cranium and the lower cervical spine.

Microhabitat segregation in two desert rodent species: the relation of prey availability to diet.

I studied diet in relation to microhabitat use in two desert rodents:Microdipodops megacephalus, the dark kangaroo mouse, andPeromyscus maniculatus, the deer mouse. Contrary to expectation, both species ate primarily arthropods, which were most abundant near shrubs.Peromyscus used the area near shrubs, in contrast toMicrodipodops, which used open microhabitat. As a consequence, the diet ofPeromyscus was narrower and more concentrated on abundant prey types than that ofMicrodipodops. Thus microhabitat segregation, which is frequently reported for desert rodents, is related to a diet-breadth difference between these rodents. The use of open microhabitat and low density resources byMicrodipodops, when compared with the large bipedalDipodomys and small quadrupedalPerognatus, suggests that bipedal locomotion in desert rodents is related to use of open microhabitat, and that body size is related to density of food resources.