Biomedical subjects
Publications and source records attributed to K Shanmuganathan.
OBJECTIVE: The objective of this study was to determine the CT findings of traumatic lumbar hernia in 15 patients and to discuss the mechanism and treatment of injury. CONCLUSION: CT can reveal traumatic lumbar hernia and show both the anatomy of disrupted muscular layers and the presence of herniated intraabdominal viscera or retroperitoneal fat.
Although MR imaging and MR angiography should not be considered a primary study for patients sustaining blunt or penetrating thoracic trauma, it has achieved importance as an ancillary problem-solving modality. In general, the authors have found MR imaging to be a useful ancillary study to confirm or exclude diaphragm injury, if spiral CT scan with reformations are equivocal; to help assess the aorta and mediastinum in cases of potential injury that are not clarified by CT scan or thoracic angiography; and to identify the true origin of trauma-related masses that may simulate thoracic neoplasms.
Chest radiographs remain the initial imaging modality to rapidly screen patients with blunt chest trauma. Spiral CT is more sensitive and specific in diagnosing most thoracic pathology seen in blunt trauma patients. This article reviews the major clinical and radiologic findings that occur with blunt injuries to the chest, excluding mediastinal vascular injuries.
PURPOSE: To determine, at screening ultrasonography, the prevalence, severity, and clinical outcome of clinically important abdominal visceral injuries, without associated hemoperitoneum, that result from blunt abdominal trauma. MATERIALS AND METHODS: Computed tomography (CT) was performed at admission in 466 patients with visceral injury. A retrospective review was performed of findings from surgery and contrast material-enhanced spiral and conventional CT performed to verify abdominal visceral injuries in 467 (4%) of 11,188 patients with blunt trauma. These patients were admitted to a level 1 trauma center over 33 months to determine the presence of hemoperitoneum and to identify the grade of injury. Medical records of patients with abdominal visceral injury without hemoperitoneum were reviewed for the management required and for results of focused abdominal sonography for trauma (FAST). RESULTS: A total of 575 abdominal visceral injuries were identified at CT and/or surgery. Findings of CT at admission (n = 156) and of surgery (n = 1) revealed no evidence of hemoperitoneum in 157 (34%) patients with abdominal visceral injury; 26 (17%) of whom also had negative FAST studies. Abdominal visceral injuries diagnosed in patients without hemoperitoneum included 57 (27%) of 210 splenic injuries, 71 (34%) of 206 hepatic injuries, 30 (48%) of 63 renal injuries, four (11%) of 35 mesenteric injuries, and two (29%) of seven pancreatic injuries. Surgical and/or angiographic intervention was required in 26 (17%) patients without hemoperitoneum. CONCLUSION: Reliance on the presence of hemoperitoneum as the sole indicator of abdominal visceral injury limits the value of FAST as a screening diagnostic modality for patients who sustain blunt abdominal trauma.
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OBJECTIVE: The purpose of this study was to determine the diagnostic sensitivity and specificity of helical CT with sagittal and coronal reformatted images in detecting diaphragmatic rupture after blunt trauma. MATERIALS AND METHODS: Chest and abdominal helical CT scans obtained in 41 patients with suspected diaphragmatic injury after major blunt trauma were reviewed by three observers who were unaware of surgical findings. Coronal and sagittal reformatted images were reviewed for each patient as well. Findings consistent with diaphragmatic injury, such as waistlike constriction of abdominal viscera (i.e., the "collar sign"), intrathoracic herniation of abdominal contents, and diaphragmatic discontinuity were recorded. Sensitivity and specificity of helical CT were calculated on the basis of surgical findings and clinical follow-up. RESULTS: Helical CT was performed preoperatively in 23 patients with diaphragmatic rupture (left, n = 17; right, n = 5; bilateral, n = 1). An additional 18 patients underwent helical CT to further evaluate suspicious findings seen on chest radiography at admission and were found to have an intact diaphragm. Sensitivity for detecting left-sided diaphragmatic rupture was 78% and specificity was 100%. Sensitivity for the detection of right-sided diaphragmatic rupture was 50% and specificity was 100%. The most common CT finding of diaphragmatic rupture was the collar sign, identified in 15 patients (sensitivity, 63%; specificity, 100%). Diaphragmatic discontinuity was seen in four patients. CONCLUSION: Helical CT, especially with the aid of reformatted images, is useful in the diagnosis of acute diaphragmatic rupture after blunt trauma. Helical CT can be used to detect 78% of left-sided and 50% of right-sided injuries.
Information provided by CT scan allows for determination of the extent of liver injury and identification of other nonhepatic abdominal injuries. This information, coupled with clinical assessment, can be used to optimize management. Contrast-enhanced CT scan can monitor progression or resolution of hepatic injuries, detect complications, and guide percutaneous treatment of some complications. This article discusses CT scanning technique; classification, sites, and mechanisms of liver injury; CT scan appearance of liver injury; and complications of hepatic trauma.
PURPOSE: The purpose of this study was to prospectively examine the accuracy of contrast-enhanced spiral thoracic computed tomography (CEST-CT) for direct detection of traumatic aortic injury resulting from blunt thoracic trauma. METHODS: During a 25-month period, all blunt trauma patients who had abnormal mediastinal contours on admission chest radiographs underwent CEST-CT. The presence and location of mediastinal blood and any direct signs of aortic injury, such as pseudoaneurysm, were recorded. Computed tomographic results were compared with results of aortography, when performed, surgery, or clinical status at discharge. RESULTS: There were 7,826 patients classified as having blunt trauma admitted during the study. Of these, 1,104 (14.3%) had CEST-CT performed. Mediastinal hemorrhage was detected on 118 (10.7%) of all thoracic computed tomographic scans. Direct evidence of aortic injury was detected in 24 patients (20.3%) with mediastinal hemorrhage and 2.2% of all patients undergoing CEST-CT. In this prospective series, CEST-CT was 100% sensitive based on clinical follow-up; it was 99.7% specific, with 89% positive and 100% negative predictive values and an overall diagnostic accuracy of 99.7%. CONCLUSION: CEST-CT is a valuable ancillary study for the detection of traumatic aortic injury. Spiral computed tomography is accurate for the detection and localization of both hemomediastinum and direct signs of aortic injury.
Much recent work on the use of computed tomography (CT) and transesophageal echocardiography in screening for and facilitating the diagnosis of acute thoracic aortic injury in the patient with blunt chest trauma has shown favorable results. This has led some physicians to question whether conventional thoracic aortography is still the reference standard. The purpose of this review article is to summarize the epidemiology and pathophysiology of acute thoracic aortic injury, the current status of the individual imaging modalities in use, and the surgeon's perspective. Despite a burgeoning literature and a confounding array of clinical and imaging advances, timely diagnosis of acute thoracic aortic injury remains a challenge. To overcome this problem, some trauma centers have used CT, transesophageal echocardiography, or both, in their diagnostic algorithm for acute thoracic aortic injury. These diagnostic algorithms are individually tailored by each institution and are still under investigation; therefore, no definite conclusions can be reached.
Hepatic venous outflow obstruction (Budd-Chiari syndrome)is a rare sequel of abdominal trauma. Three cases of Budd-Chiari syndrome resulting from obstruction to the intrahepatic IVC by liver injury are reported. The CT findings include extrinsic compression of the intrahepatic inferior vena cava (IVC) by intraparenchymal and/or subcapsular hepatic haematoma, non-visualization or narrowing of one or more main hepatic veins with intravenous contrast-enhanced CT, and accumulation of low attenuation ascites. This entity should be distinguished from intraperitoneal bile leak or hemoperitoneum associated with major liver injury with which it could be confused. Decompression of the IVC and hepatic veins by surgical or percutaneous drainage of intrahepatic or subcapsular hematoma was curative in two of the three patients.
Chest drain placement is essential to the management of patients with abnormal thoracic collections of air or fluid. Frequently, in these critically ill patients, drain position can only be assessed by portable frontal radiographs. However, evaluation by axial chest CT in some cases reveals unexpected malplacement that may prompt repositioning to reduce morbidity and improve drain function.
PURPOSE: This prospective study was designed to assess the association of clear paranasal sinuses (no free fluid) as shown by facial computed tomography (CT) with the absence of fractures involving the paranasal sinus walls. PATIENTS AND METHODS: All facial CT scans performed during a 12-month period to rule out maxillofacial injury in blunt trauma patients were reviewed. The scans were made using 5-mm slice thickness and 4-mm table incrementation. They were assessed for the presence or absence of free paranasal sinus fluid (hemorrhage) and the presence and location of facial fractures. RESULTS: A total of 366 CT scans of the face were performed during the study. Among them, 180 scans (49%) were identified that showed no evidence of free paranasal fluid. Twenty-two (12%) of these 180 CT studies showed isolated nasal fractures (n = 13) or zygomatic arch fractures (n = 9). No patient without free paranasal sinus fluid had any midfacial fracture involving a paranasal sinus wall (P < .001 by Fischer exact test). CONCLUSION: The absence of free paranasal sinus fluid after facial trauma is a highly reliable criterion to exclude fractures involving the paranasal sinus walls. Other fractures involving osseous structures not contiguous with the paranasal sinus walls, such as nasal or zygomatic arch fractures, are not excluded. The CT "clear sinus" sign is a simple, rapid method to exclude paranasal sinus fractures.
BACKGROUND: Focused abdominal sonography for trauma (FAST) relies on hemoperitoneum to identify patients with injury. Blunt trauma victims (BTVs) with abdominal injury, but without hemoperitoneum, on admission are at risk for missed injury. METHODS: Clinical, radiologic, and FAST data were collected prospectively on BTVs over a 12-month period. All patients with FAST-negative for hemoperitoneum were further analyzed. Examination findings and associated injuries were evaluated for association with abdominal lesions. RESULTS: Of 772 BTVs undergoing FAST, 52 (7%) had abdominal injury. Fifteen of 52 (29%) had no hemoperitoneum by admission computed tomographic scan, and all had FAST interpreted as negative. Four patients with splenic injury underwent laparotomy. Six other patients with splenic injury and five patients with hepatic injury were managed nonoperatively. Clinical risk factors significantly associated with abdominal injury in BTVs without hemoperitoneum include: abrasion, contusion, pain, or tenderness in the lower chest or upper abdomen; pulmonary contusion; lower rib fractures; hemo- or pneumothorax; hematuria; pelvic fracture; and thoracolumbar spine fracture. CONCLUSIONS: Up to 29% of abdominal injuries may be missed if BTVs are evaluated with admission FAST as the sole diagnostic tool. Consideration of examination findings and associated injuries should reduce the risk of missed abdominal injury in BTVs with negative FAST results.
OBJECTIVE: The purposes of this study were to determine the spectrum of CT findings of mesenteric injury, to compare CT findings of mesenteric injury with surgical observations, and to assess the potential of CT to predict which patients with mesenteric injury require laparotomy. MATERIALS AND METHODS: Blunt trauma patients admitted to our facility during a 5-year 4-month period with a CT or surgical diagnosis of mesenteric injury were identified from a radiology database and trauma registry. Patients with CT findings of full-thickness bowel injury associated with mesenteric injury or diagnostic peritoneal lavage performed before CT were excluded. CT scans of all patients were retrospectively reviewed both with and without knowledge of surgical results. Medical records of all study patients were reviewed to ascertain admission physical findings and surgical results. RESULTS: Twenty-seven of 29 patients meeting the study criteria underwent laparotomy, and two others were managed conservatively. Among the 27 patients who had surgery. 24 (89%) had CT findings of mesenteric injury confirmed. Surgical findings showed CT scans to be falsely negative in two other patients and falsely positive in one other patient. No major discrepancies were found between retrospective CT review done with and without knowledge of the surgical findings. Two CT findings unique to patients whose injuries, in the judgment of the surgical team, required surgical repair were active extravasation of IV contrast material and bowel wall thickening associated with mesenteric findings. Physical findings did not correlate well with the type and clinical significance of the mesenteric injury. CONCLUSION: The CT finding of mesenteric bleeding or bowel wall thickening associated with mesenteric hematoma or infiltration in the blunt trauma patient indicates a high likelihood of a mesenteric or bowel injury requiring surgery. The finding of focal mesenteric hematoma or infiltration without adjacent bowel wall thickening is nonspecific and can occur both in mesenteric or bowel lesions that require surgery and those that do not.
In an effort to improve the pharmacokinetic properties and tissue distribution of 2'-F-ara-ddI, two lipophilic prodrugs, 6-azido-2'-3'-dideoxy-2'-fluoro-beta-D- arabinofuranosylpurine (FAAddP, 4) and N6-methyl-2'-3'-dideoxy-2'-fluoro-beta-D-arabinofuranosyladenine (FMAddA, 5), were synthesized and their biotransformation was investigated in vitro and in vivo, in mice. Compounds 4 and 5 were synthesized via the intermediate 2. For the in vitro studies, FAAddP and FMAddA were incubated in mouse serum, liver homogenate, and brain homogenate. FAAddP was metabolized in liver homogenate by the reduction of the azido to the amino moiety followed by deamination, yielding 2'-F-ara-ddI. The conversion of FAAddP to 2'-F-ara-ddA was mediated by microsomal P-450 NADPH reductase system, as shown by the liver microsomal assay. FAAddP was also converted to 2'-F-ara-ddI at a slower rate in the brain than in the liver. FMAddA, however, was stable in brain homogenate and was slowly metabolized in the liver homogenate. Metabolic conversion of FMAddA in vitro was stimulated by the addition of adenosine deaminase. In the in vivo metabolism study, FAAddP underwent reduction to 2'-F-ara-ddA followed by deamination to 2'-F-ara-ddI. FMAddA did not result in increased brain delivery of 2'-F-ara-ddI in vivo, probably due to the slow conversion as observed in the in vitro studies. However, there was an increase in the half-life of 2'-F-ara-ddI produced from FMAddA. This report is the first example in the design of prodrugs using the azido group for adenine- and hypoxanthine-containing nucleosides. This interesting and novel approach can be extended to other antiviral and anticancer nucleosides.
Since 2'-fluoro-5-methyl-beta-L-arabinofuranosyluracil (L-FMAU) has been shown to be a potent anti-HBV agent in vitro, it was of interest to study the structure-activity relationships of related nucleosides. Thus, a series of 1-(2-deoxy-2-fluoro-beta-L-arabinofuranosyl)pyrimidine nucleosides have been synthesized and evaluated for antiviral activity against HBV in 2.2.15 cells. For this study, L-ribose was initially used as the starting material. Due to the commercial cost of L-ribose, we have developed an efficient procedure for the preparation of L-ribose derivative 6. Starting from L-xylose, 6 was obtained in an excellent total yield (70%) through the pyridinium dichromate oxidation of the 3-OH group followed by stereoselective reduction with NaBH4. It was further converted to the 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-alpha-L-arabinofuranose (10), which was then condensed with various 5-substituted pyrimidine bases to give the nucleosides. Among the compounds synthesized, the lead compound, L-FMAU (13), exhibited the most potent anti-HBV activity (EC50 0.1 microM). None of the other uracil derivatives showed significant anti-HBV activity up to 10 microM. Among the cytosine analogues, the cytosine (27) and 5-iodocytosine (35) derivatives showed moderately potent anti-HBV activity (EC50 1.4 and 5 microM, respectively). The cytotoxicity of these nucleoside analogues has also been assessed in 2.2.15 cells as well as CEM cells. None of these compounds displayed any toxicity up to 200 microM in 2.2.15 cells. Thus, compound 13 (L-FMAU), 27, and 35 showed a selectivity of over 2000, 140, and 40, respectively.
We present the first reported case of vision loss due to tension orbital emphysema associated with tension pneumocephalus resulting from blunt trauma. In the setting of trauma, intraorbital air indicates paranasal sinus-orbital communication. Tension orbital emphysema may cause vision loss through optic nerve compression, ischemia, or contusion; or central retinal artery occlusion. Vision impairment after craniofacial injury should prompt urgent computed tomography. Tension orbital emphysema with associated vision impairment requires treatment including direct decompression and, in some cases, high-dose steroids to preserve vision. Increases in sinus pressure from coughing, nose-blowing, or vomiting should be avoided until definitive treatment can be instituted.
PURPOSE: To review the literature and the authors' experience with admission contrast material-enhanced computed tomography (CT) in patients admitted after blunt trauma. MATERIALS AND METHODS: From January 1990 to December 1994, thoracic CT was performed to evaluate traumatic aortic injury in 677 patients with positive or equivocal findings at chest radiography. CT scans positive for mediastinal hemorrhage or aortic injury were retrospectively reviewed and interpreted by consensus, with angiographic and surgical confirmation. RESULTS: CT findings were negative for TAI in 570 (84%) of the 677 patients. Mediastinal hemorrhage was reported in 100 patients and was the only abnormality in 79 of them. Findings at angiography were negative for traumatic aortic injury in 77 (97%). CT signs of traumatic aortic injury in 21 patients included contour abnormality or pseudoaneurysm (n = 19), intimal flap(s) (n = 8), and pseudocoarctation (n = 3). Findings at angiography were positive for traumatic aortic injury in 19 (90%). For aortic injury and mediastinal hemorrhage, respectively, specificity for traumatic aortic injury was 99% and 87% and sensitivity was 90% and 100%; at meta-analysis of data from the authors and the literature, sensitivity was 97.0% and 99.3% and specificity was 99.8% and 87.1%. Reliance on findings at admission CT rather than radiography to indicate suspicion for traumatic aortic injury before angiography resulted in savings of more than $365,000. CONCLUSION: The CT finding of mediastinal hemorrhage alone is sensitive for traumatic aortic injury, but the finding of aortic injury is more specific.