Utilization of a clinical prediction rule for abdominal–pelvic CT scans in patients with blunt abdominal trauma

This study aims to determine if a clinical prediction (CP) rule to identify patients at low risk for intra-abdominal injury (IAI) is being utilized in patients undergoing abdominal computed tomography (CT) following blunt abdominal trauma. A retrospective review of adult patients with blunt abdominal trauma undergoing abdominal CT scans was performed. The CP rule was positive if any of the following were present: systolic blood pressure <90 mmHg; urinalysis >25 red blood cells/high power field; Glasgow Coma Scale score <14; abdominal tenderness; costal margin tenderness; femur fracture; hematocrit <30 %; or pneumothorax or rib fracture on chest X-ray. The CP rule was negative if all variables were negative. Acute intervention was defined as therapeutic laparotomy or angiographic embolization. All variables in the CP rule were obtained in 218/262 (83 %; 95 % confidence interval (CI), 78, 88 %) patients. Of the 44 patients without complete CP rule assessment, 1 (2.3 %; 95 % CI, 0.1 %, 12.0 %) had an IAI but did not undergo therapeutic intervention. IAI was present in 11 (6.7 %; 95 % CI, 3.4, 11.6 %) of the 165 patients with at least one CP rule positive and 4 (36 %; 95 % CI, 11, 69 %) underwent therapeutic intervention. In the CP rule-negative patients, IAI was identified in 1/53 (1.9 %; 95 % CI, 0, 10.1 %) and no therapeutic intervention was required. An important percentage of patients undergoing abdominal CT are not assessed for or have a negative CP rule. Improved implementation of this CP rule may reduce unnecessary abdominal CT scans in patients presenting with blunt abdominal trauma.     

Respiratory gated multidetector computed tomography: Applicable for diagnostic abdominal imaging?

Purpose

To evaluate the ability and accuracy of a respiratory gated technique used with contrast enhanced MDCT of the upper abdomen with focus on diagnostic image quality and depiction of organs and major vessels.

Materials and methods

Forty-five adult patients who were referred to our institution for follow-up dynamic contrast enhanced abdominal CT imaging were included in this study. Respiratory gated CT scans were performed with the use of a dedicated hardware. A multiphasic CT scan was performed for each patient. Respiratory gated images were obtained between early arterial and portal venous phases during free breathing. Images of respiratory gated (RG) and breathhold (BH) phases were compared qualitatively and quantitatively by two radiologists. Definitive statistical methods were used for evaluating the scoring data, while Mann Whitney U test was used for comparison. Statistical significance was accepted for p values <0.05.

Results

Statistical significant difference was found for comparison of scores regarding luminal opacification and contoural integrity of intrahepatic vascular structures with scores of RG scans rated poor to moderate (e.g. 2.86 ± 1.07 for luminal opacification of intrahepatic portal veins as well as border detectability) in comparison to scores of BH scans rated good to excellent (e.g. 1.37 ± 1.31 for luminal opacification, 1.35 ± 1.28 for border detectability of intrahepatic portal veins, p < 0.001). Furthermore, statistical significant differences were found for general image noise levels (p < 0.001).

Conclusions

Further technical advances of RG technique could enable routine use of this technique for selected patient groups.     

Vomiting—is this a good indication for CT head scans in patients with minor head injury?

The National Institute for Health and Clinical Excellence head injury guidelines advise CT imaging within 1 h if there is more than one episode of vomiting post-head injury in adults and three or more episodes in children. Since the guideline publication, studies have found that, following head injury, vomiting alone is associated with an abnormal CT head scan in 13-45% of cases. CT head scan requests referred from the emergency department between 1 May 2009 and 30 April 2010 were retrospectively reviewed. Patients with vomiting as the sole indication for an "immediate" CT head scan performed within 1 h were included in the study. Reports produced by experienced neuroradiologists were reviewed and the detection of significant head injury was noted. There were 1264 CT head scans performed during our study period. 151 (124 adults, 27 children) were indicated owing to vomiting following head injury. 5 of the 124 adult scans and 1 of the 27 paediatric scans showed an abnormal finding, giving positive predictive values (PPV) of 4% and 3.7%, respectively. None of these patients required either acute or delayed neurosurgical intervention. In our experience, vomiting alone has a PPV of 4% for significant head injury in adults. However, none of these injuries were serious enough to warrant acute or delayed intervention. Given these findings, vomiting following head injury is a reasonable indication for a CT head scan; however, as none of the patients required acute intervention, we suggest that these scans do not usually need to be performed within 1 h of request.     

Size-specific dose estimates: Localizer or transverse abdominal computed tomography images?

AIM: To investigate effect of body dimensions obtained from localizer radiograph and transverse abdominal computed tomography (CT) images on Size Specific Dose Estimate.METHODS: This study was approved by Institutional Review Board and was compliant with Health Insurance Portability and Accountability Act. Fifty patients with abdominal CT examinations (58 ± 13 years, Male:Female 28:22) were included in this study. Anterior-posterior (AP) and lateral (Lat) diameters were measured at 5 cm intervals from the CT exam localizer radiograph (simple X-ray image acquired for planning the CT exam before starting the scan) and transverse CT images. Average of measured AP and Lat diameters, as well as maximum, minimum and mid location AP and Lat were measured on both image sets. In addition, off centering of patients from the gantry iso-center was calculated from the localizers. Conversion factors from American Association of Physicists in Medicine (AAPM) report 204 were obtained for AP, Lat, AP + Lat, and effective diameter (√ AP * Lat) to determine size specific dose estimate (SSDE) from the CT dose index volume (CTDI_vol) recorded from the dose reports. Data were analyzed using SPSS v19.RESULTS: Total number of 5376 measurements was done. In some patients entire body circumference was not covered on either projection radiograph or transverse CT images; hence accurate measurement of AP and Lat diameters was not possible in 11% (278/2488) of locations. Forty one patients were off-centered with mean of 1.9 ± 1.8 cm (range: 0.4-7 cm). Conversion factors for attained diameters were not listed on AAPM look-up tables in 3% (80/2488) of measurements. SSDE values were significantly different compared to CTDI_vol, ranging from 32% lower to 74% greater than CTDI_vol.CONCLUSION: There is underestimation and overestimation of dose comparing SSDE values to CTDI_vol. Localizer radiographs are associated with overestimation of patient size and therefore underestimation of SSDE.     

CT scanning of children with blunt abdominal trauma – is oral contrast useful?

Purpose: To determine the usefulness of oral contrast in CT scanning of children with blunt abdominal trauma by comparing scans performed with and without oral contrast. Methods: CT scans of 273 children with abdominal trauma and 40 without trauma were reviewed. Results: Of the trauma patients, 116 (43 %) were scanned with oral contrast, 157 (57 %) without. Among the children who underwent laparotomy, CT scanning identified 6 of 6 organ injuries in those scanned with oral contrast and 11 of 12 in those scanned without. CT scanning identified all bowel injuries. The pancreatic body and tail were significantly better visualized in scans with oral contrast. Detection of pancreatic or liver injury was not, however, significantly different in the two groups. Opacification of the bowel by contrast was significantly better in elective than in trauma patients. Conclusion: There was no difference in detection of injuries between children scanned with and without oral contrast.     

Can chest and abdominal trauma CT eliminate the need for plain films of the spine? – Experience with 329 multiple trauma patients

Purpose: To compare the accuracy of spine plain films with chest and abdominal trauma CT in detection of spine fractures. Methods: The study prospectively enrolled 329 multiple trauma patients. Of these, 38 patients had both chest CT for trauma and thoracic spine plain films, and 87 patients had both abdominal CT for trauma and lumbar spine plain films. Results: Of the fractures visible at either chest trauma CT or thoracic spine plain film examination, all were diagnosed on CT and 62 % on plain films. Of fractures visible at either abdominal trauma CT or lumbar spine plain films, 94 % were diagnosed on CT and 67 % on plain films. The one false negative CT involved an articular process fracture, which was visible but not mentioned, in a patient with a sacral fracture. Conclusion: Evaluation of the digital scout images and bone windows when a patient has chest and abdominal trauma CT appears to be as accurate as thoracic and lumbar spine plain films in the evaluation of spinal trauma.     

Gallium-67 scintigraphy in lymphoma: is there a benefit of image fusion with computed tomography?

The usefulness and complementarity of gallium (67Ga) scintigraphy and computed tomography (CT) in the management of patients with lymphoma have been extensively demonstrated. Owing to a lack of anatomical landmarks and physiological distribution of the tracer, precise localisation of abnormalities on 67Ga scintigraphy can be difficult. As fusion imaging techniques between single-photon emission tomography (SPET) and CT have been developed recently, we investigated whether use of CT/67Ga SPET fusion imaging could help in the interpretation of 67Ga scintigraphy. From November 1999 to May 2001, 52 consecutive fusion studies were performed in 38 patients [22 patients with Hodgkin's disease (HD) and 16 patients with non-Hodgkin's lymphoma (NHL)] as part of pre-treatment staging (n=13), treatment evaluation (n=20) or evaluation of suspected recurrence (n=19). 67Ga scintigraphy was carried out 2 and 6 days following the injection of 185-220 MBq 67Ga citrate. On day 2, 67Ga SPET and CT were performed, focussing on the chest and/or the abdomen/pelvis. Data from each imaging method were co-registered using external markers. 67Ga scintigraphy and CT were initially interpreted independently by nuclear medicine physicians and radiologists. CT/67Ga SPET fusion studies were then jointly interpreted and both practitioners indicated when fusion provided additional information in comparison with CT and 67Ga SPET alone. Image fusion was considered to be of benefit in 12/52 (23%) studies which were performed for initial staging (n=4), treatment evaluation (n=4) or evaluation of suspected recurrence (n=4). In these cases, image fusion allowed either confirmation and/or localisation of pathological gallium uptake (n=10) or detection of lesions not visible on CT scan (n=2). Fusion was relevant for discrimination between osseous lesions and lymph node involvement adjacent to bone, especially in the thoracic and lumbar spine and pelvis. In the abdomen and pelvis, fusion helped to differentiate physiological bowel elimination from abnormal uptake, and assisted in precisely locating uptake in neighbouring viscera of the left hypochondrium, including the spleen, left liver lobe, coeliac area, stomach wall and even the splenic flexure. At the thoracic level, fusion also proved useful for demonstrating clearly the relationships of abnormal foci to the pleura, hepatic dome, mediastinum, ribs or thoracic spine. Clinical management was altered by fusion imaging in one patient (chemotherapy was given instead of radiotherapy) and was potentially affected in three other patients (in that, in conjunction with other factors, the results of fusion imaging had an influence on the decision regarding use of irradiation and especially the treatment volume). In conclusion, CT/67Ga SPET fusion imaging allowed precise localisation of gallium uptake and correct attribution to the involved viscera, thereby altering the diagnosis in 20%-25% of studies in comparison with CT and 67Ga SPET analyses alone. CT/67Ga SPET fusion therefore appears valuable in facilitating the interpretation of 67Ga scintigraphy and we recommend its use in patients with lymphoma when CT and 67Ga scintigraphy are planned.     

Small mesenteric hematoma following blunt abdominal trauma as early sign in computed tomography of occult small bowel perforation—report of 2 cases

Blunt abdominal trauma can lead to mesenteric injuries, which are not an uncommon but often underestimated finding on the initial computed tomography (CT) scan. Only small mesenteric hematomas, which are shrinking in short-term follow-up CT examinations, do not require surgery. We present two cases where subtle mesenteric hematoma was one hint on the admission scan for subsequent small bowel perforation. So it can be a relevant finding and should prompt early CT follow-up imaging, even in asymptomatic patients. This will enable early diagnosis and reduction in morbidity and mortality.     

Relevant incidental findings at abdominal multi-detector contrast-enhanced computed tomography: A collateral screening?

AIM: To investigate the prevalence of relevant incidental findings (RIFs) detected during routine abdominal contrast-enhanced computed tomography (CeCT).METHODS: We retrospectively evaluated the reports of a consecutive series of abdominal CeCT studies performed between January and May 2013. For each report, patients’ age and sex, admission as inpatient or outpatient, clinical suspicion as indicated by the requesting physician, availability of a previous abdominal examination, and name of the reporting radiologist were recorded. Based on the clinical suspicion, the presence and features of any RIFs (if needing additional workup) was noted.RESULTS: One thousand forty abdominal CeCT were performed in 949 patients (528 males, mean age 66 ± 14 years). No significant difference was found between inpatients and outpatients age and sex distribution (P > 0.472). RIFs were found in 195/1040 (18.8%) CeCT [inpatients = 108/470 (23.0%); outpatients = 87/570 (15.2%); P = 0.002]. RIFs were found in 30/440 (6.8%) CeCT with a previous exam and in 165/600 (27.5%) without a previous exam (P < 0.001). Radiologists’ distribution between inpatients or outpatients was significantly different (P < 0.001). RIFs prevalence increased with aging, except for a peak in 40-49 year group. Most involved organs were kidneys, gallbladder, and lungs.CONCLUSION: A RIF is detected in 1/5 patients undergoing abdominal CeCT. Risk of overdiagnosis should be taken into account.     

Benign or malignant?: differentiating breast lesions with computed tomography attenuation values on dynamic computed tomography mammography

OBJECTIVE: To evaluate enhancement effects of breast lesions with dynamic computed tomography (CT) and to determine characteristics to aid in differential diagnosis of benign and malignant lesions. METHODS: One hundred seventy-six women underwent preoperative dynamic CT, in which they were scanned with rapid injection of contrast media (3 mL/s) after 30 seconds and 2 minutes (early and delayed phases, respectively). The CT values and enhancement patterns of malignant lesions (n = 154) were compared with those of benign lesions (n = 22), and the cut point of CT values with the best validity was analyzed. RESULTS: The CT values of malignant lesions were higher than those of benign lesions in both phases (P < 0.0001). The cut point was determined to be 60 Hounsfield units (HU) in the early phase (44% validity, 90% sensitivity). Washout and plateau patterns were more commonly seen in the malignant group (73% specificity). CONCLUSIONS: The analysis of enhancement effects on CT may lead to more appropriate differentiation of benign and malignant lesions.     

Multislice computed tomography of the sternum: which image reconstruction do we need?

OBJECTIVE: To assess the diagnostic value and to optimize image reconstruction for multislice spiral computed tomography (MSCT) of the sternum. MATERIALS AND METHODS: Forty patients underwent MSCT of the sternum using a standardized examination protocol (4x1 mm or 4x2.5 mm collimation; 120 kV, 120 mAseff). Axial images with an effective slice thickness of 1.25 mm or 3 mm and an increment of 0.8 mm or 1 mm were reconstructed. Coronal and sagittal reformations with a slice thickness between 2 mm or 3 mm and 5 mm and a slice distance ranging from 1 mm to 4 mm (overlap 1 mm) were calculated. In all patients, additional plain film radiographs (n=9) or clinical follow-up data were available. Image quality was assessed visually using a five-point grading scale. RESULTS: In all patients, the correct diagnosis was established using multiplanar reformats (MPR) exclusively. Best image quality for MPR was achieved using a slice thickness of 3 mm and a slice distance of 2 mm. Images acquired with a 4x1 mm collimation proved superior to images reconstructed from data obtained with a 4x2.5 mm collimation. CONCLUSION: MPR from MSCT data are a valuable tool for the diagnosis of sternal pathologies. For best image quality the thinnest possible collimation should be chosen.     

Does distracting pain justify performing brain computed tomography in multiple traumas with mild head injury?

Traumatic brain injury (TBI) is a significant health concern classified as mild, moderate, and severe. Although the indications to perform brain computed tomography (CT) are clear in moderate and severe cases, there still exists controversy in mild TBI (mTBI). We designed the study to evaluate the significance of distracting pain in patients with mTBI. The study population included patients with mild traumatic brain injury (GCS ≥13). Moderate and high risk factors including age <18 months or ≥60 years, moderate to severe or progressive headache, ≥2 episodes of vomiting, loss of consciousness (LOC), post-traumatic amnesia, seizure or prior antiepileptic use, alcohol intoxication, previous neurosurgical procedures, uncontrolled hypertension, anticoagulant use, presence of focal neurologic deficits, deformities in craniofacial region, and penetrating injuries were excluded. The patients were then grouped based on presence (DP+) or absence (DP?) of another organ fracture with severe pain (based on VAS). The primary outcome was any abnormal findings on brain CT scans; 330 patients were enrolled (184 DP+ and 146 DP?). Overall, two DP+ and one DP? patients had mild cerebral edema in brain CT (p?>?0.99). No patients had any neurologic symptoms or signs in follow-up. Our results show that in the absence of any other risk factors, distracting pain from other organs (limbs, pelvis, and non-cervical spine) cannot be regarded as a brain CT indication in patients with mild TBI, as it is never associated with significant intracranial lesions.