CT Criteria for Management of Blunt Liver Trauma: Correlation with Angiographic and Surgical Findings From the Departments of Diagnostic Radiology and Interventional Radiology University of Maryland Medical Center and Shock Trauma Cente Pierre A. Poletti, MD, Stuart E. Mirvis, MD, Kathirkamanathan Shanmuganathan, MD Karen L. Killeen, MD,Douglas Coldwell, MD Radiology 2000; 216:418 – 427

Preface In previously published studies (1–7), 50% – 96% hemodynamically stable patients with blunt hepatic trauma  can be successfully treated without surgery The quantity of hemoperitoneum by initial CT initially considered --indicator of hepatic trauma severity (8,9). several subsequent studies (6,10–12) : the quantity of hemoperitoneum does not correlate with failed nonsurgical management.

A CT-based grading system has been adapted from the American Association for the Surgery of Trauma classification of blunt hepatic injury.

the direct application of such a CT classification, although reflective of the extent of parenchymal liver damage, cannot reliably predict the need for angiographic assessment of the liver or the probable clinical outcome of attempted nonsurgical management (6,12). Even major hepatic injuries with a severity of up to CT grade 4 typically can be managed without surgery in those patients who maintain hemodynamic stability (6,12–18). Some authors have described wide discrepancies between the CT injury grade and the injury severity determined at surgery (19), with CT generally yielding an underestimation of the extent of injury. the advent of spiral CT and improvements in image quality have led to an increasing role of and reliance on CT for evaluating acute traumatic hepatic lesions (6,7,20 –25).

The value of the periportal blood track as a CT sign to help guide the management of liver trauma remains uncertain and controversial (26,27). The pooling of contrast material locally in the liver parenchyma or freely in the peritoneal space has been recognized as a specific sign of active bleeding that warrants embolization or celiotomy (28). Early detection of arterial contrast material extravasation is clearly important for improving the success of nonsurgical management, because it allows arterial embolization to be performed before the patient becomes hemodynamically unstable and thus potentially prevents the need for urgent surgery.

Intrahepatic vascular injuries have been reported more frequently in association with liver injuries of a higher CT grade than in association with those of a lower CT grade (4). Some authors (4,29) advocate performing mandatory hepatic angiography in all patients with hepatic injuries of CT grade 3 or higher to avoid the risk of missing arterial bleeding at CT. In the present study, our aim was to further determine the value of CT for assisting in decisions regarding the treatment of hemodynamically stable patients with blunt hepatic trauma. The accuracy of CT in depicting hepatic arterial hemorrhage was determined by comparing the CT findings with the results of angiography and surgery.

MATERIALS AND METHODS From to , 20,537 patients to the University of Maryland Shock Trauma Center. Of these patients, 7,188 (35%) were with blunt abdominal trauma. During this period, admission CT of the abdomen and pelvis depicted hepatic injury in 420 (6%) of the patients admitted with blunt-force abdominal trauma. All patients who underwent both hepatic CT and angiography during their acute imaging assessment were included in the study. Seventy-two patients (37 female, 35 male; mean age, 37.5 years; age range, 14 – 93 years; with 29.5% of all CT-depicted hepatic injuries) met these criteria and formed the study population. mechanisms of injury : motor vehicle collision (n = 64), pedestrian struck by vehicle (n = 4), fall (n =2), impact with a falling beam (n = 1), and jet ski accident (n = 1). In 47 (65%) of the 72 patients, more than one CT scan was obtained at admission.

All initial abdominal CT scans were obtained within 24 hours after admission — typically in less than 2 hours. CT was performed from the lung bases to the pelvis with 8-mm contiguous sections. The indications for hepatic angiography included confirmation of and potential embolization for CT signs of contrast material extravasation (ie, CT blush) in hemodynamically stable patients. Hepatic angiography was performed also to exclude hepatic arterial injury in patients with CT evidence of liver injury without direct CT findings of vascular injury who had unexplained transient hypotension (ie, peak systolic pressure equal to or below 100 mm Hg). Hepatic angiography was performed within 12 hours after CT in 59 patients and within 24 hours after CT in 11 patients; it was delayed in two patients for 4 and 7 days after CT.

Figure 1. Active bleeding in the liver of a 77-year-old man struck by a bus. Transverse CT scan shows a grade 3 liver injury (arrows) with areas of high attenuation (arrowheads) within the laceration.

Active bleeding in a 17- year-old male patient admitted following blunt abdominal trauma. (a) Transverse CT scan shows a grade 4 liver laceration (arrows) in the right lobe of the liver with two high-attenuating areas (arrowheads), which represent active bleeding.

(b) Selective right hepatic arterial angiogram obtained after embolization of one bleeding site (solid arrow) confirms the second area of active bleeding (open arrow), as seen in a.

Angiographies were assessed for the presence or absence of hepatic vascular injuries, including localized retention of contrast material (ie, parenchymal extravasation), pseudoaneurysm, occlusion or luminal irregularity of hepatic arteries, devascularized hepatic segments, arteriovenous or arteriobiliary fistulas, and major portal venous perfusion abnormalities. Embolizations were performed for evidence of arterial bleeding, fistula, or major hepatic arterial vascular abnormality (ie, occlusion or marked focal luminal irregularity)

The medical and surgical records of all the patients, as well as the radiologic reports of the 47 patients who underwent follow-up CT, were examined to determine the outcome of surgical or nonsurgical management and the prevalence and types of liver-related complications that occurred. The surgical report for each patient who underwent surgery was reviewed to determine the indication or indications for surgery, the presence and location of any bleeding site or “ oozing, ” and whether surgical treatment (ie, packing, suturing, and/or resection) was required. Our study data were analyzed to determine the value of admission CT in predicting the need for hepatic angiography and the potential for early and late complications among all grades of blunt liver injury.

the following factors were assessed: (a) (a) the association between CT injury grade and injury to specific anatomic sites; (b) (b) the relationship between specific anatomic sites of hepatic injury at CT and angiographic findings, need for surgery, or failed nonsurgical management; (c) (c) the sensitivity, specificity, negative and positive predictive values, and accuracy of CT findings of vascular injury with angiography and surgery as the reference-standard methods; (d) (d) the clinical outcome versus initial treatment (ie, early surgery, angiographic intervention, or observation); (e) (e) the relationship between delayed hepatic trauma complications that occurred more than 10 days after admission and initial CT findings.

Statisitcal Analyses Each CT criterion was compared with the angiographic and surgical results in two by two tables by using statistical software (Stata, College Station, Tex). The x2 or Fisher exact test was used, when appropriate, to evaluate the univariate association between the tested parameters. P value <0.05 was considered to be indicative of a statistically significant difference between two different sample populations.

Results CT Hepatic Injury Grade and Involvement of Specific Anatomic Landmarks

The liver was the major abdominal visceral injury in 51 (71%) of the 72 patients. Splenic injury (n = 16 [22%]) was the most common major associated intraabdominal injury, followed by diaphragmatic tear (n =2 [3%]), renal contusion (n = 1 [1%]), colon tear (n =1 [1%]), and mesenteric contusion (n =1 [1%]).

Liver lacerations extending into major hepatic veins in a 25-year-old man admittedfollowing a motor vehicle collision. Transverse CT scan shows right lobe liver lacerations (arrows) extending to the right and middle hepatic veins at their confluence with the inferior vena cava.

Correlation of Specific CT Injury Findings with Hepatic Angiographic Findings and Clinical Management

Major hepatic venous involvement was also seen in all six CT studies that were false-negative for arterial bleeding when compared with the hepatic angiographic studies (P =.01) Among the 13 patients with both these CT findings, 11 (85%) had arterial bleeding that was confirmed at angiography or surgery and two were considered to have false-positive CT studies for arterial bleeding None of the 25 patients who had no CT finding of arterial vascular injury or major hepatic venous involvement had active bleeding at angiography or surgery. the absence of both these findings was considered to be the most reliable CT evidence to exclude hepatic arterial bleeding, with a sensitivity of 100% (25 of 25 patients), specificity of 92% (25 of 27 patients), and accuracy of 95% (36 of 38 patients) (P <.001).

Hepatic Arterial Contrast Material Extravasation at CT

In two patients, the CT finding probably did represent active bleeding, which retrospectively was found to be extrahepatic in origin and thus did not originate from a branch of the hepatic artery. In another patient, the common hepatic artery was not selectively catheterized for anatomic reasons, and, therefore, the angiographic study was suboptimal because the contrast material injection was limited to the celiac trunk. However, because the angiographic examination was considered to be a reference standard for the present study and because the patient was treated successfully without surgery, that CT study also was considered to be false- positive.

Transverse CT scans false- positive for active bleeding in the liver of a 17-year-old female patient admitted following a motor vehicle collision show a grade 4 liver injury (solid arrows) involving the bare area of the liver and the porta hepatis (open arrow in b). Two focal areas of hemorrhage (arrowheads in a) are seen within the hematoma. The selective hepatic angiogram (not shown) did not show evidence of hepatic hemorrhage.

Normal enhancing hepatic parenchyma within a hepatic laceration mimicking active bleeding in a 20-year-old woman admitted following a motor vehicle accident. Transverse CT scan shows a focal area of normally enhancing hepatic parenchyma (straight arrow) within a grade 4 right liver lobe laceration (curved arrows) mimicking a site of active hemorrhage. The selective hepatic angiogram (not shown) did not show evidence of hepatic bleeding.

Branch of the portal vein mimicking a hepatic pseudoaneurysm in a 31-year- old man admitted following a blunt abdominal trauma. At initial interpretation of the transverse CT scan, a well-circumscribed focal area of high attenuation (arrow) seen within a grade 4 hepatic laceration (arrowheads) was falsely considered to be a hepatic pseudoaneurysm. The selective hepatic angiogram (not shown) did not demonstrate a hepatic arterial pseudoaneurysm. At retrospective review of this scan, these findings were found to be a branch of the normal right portal vein traversing through the hepatic laceration.

Hepatic venous injury in a 14-year- old girl admitted following a blunt abdominal trauma. (a, b) Transverse CT scans show a wedge-shaped, low-attenuating area (open arrows) in the right hepatic lobe drained by the middle hepatic vein. A hepatic laceration (solid arrow in a) extends into the region of the middle hepatic vein (curved arrow in b), which is thrombosed and not enhancing at CT. Free intraperitoneal blood (arrowheads) is seen around the inferior vena cava and the liver. At surgery, the middle hepatic vein was avulsed from the inferior vena cava and actively bleeding.

Evaluation of Initial Treatment: Surgical versus Nonsurgical Management

Angiographic Results versus Outcomes

Conclusion our data indicate that CT-based criteria can be used to guide the diagnostic management of blunt hepatic trauma in hemodynamically stable patients. Such criteria, including CT gradeof hepatic injury, CT evidence of arterial vascular injury, and presence or absence of hepatic venous involvement within the hepatic injury, can help in the selection of patients who should undergo hepatic angiography and possibly embolization. These criteria appear to be useful in identifying high-risk patients — that is, those prone to persistent or delayed hepatic bleeding or who may develop delayed complications and thus need closer observation and CT follow-up. If supported by further studies, our observations should help in adapting the current CT-based injury classifications to improve their usefulness in selecting patients for initial nonsurgical management of blunt hepatic injury.

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