Need For Additional Imaging Research Articles

Imaging Peripheral Arterial Disease: A Randomized Controlled Trial Comparing Contrast-enhanced MR Angiography and Multi–Detector Row CT Angiography

To prospectively evaluate clinical utility, patient outcomes, and costs of contrast material-enhanced magnetic resonance (MR) angiography compared with multi-detector row computed tomographic (CT) angiography for initial imaging in the diagnostic work-up of patients with peripheral arterial disease. Institutional review board approval and informed consent were obtained. Patients referred for diagnostic imaging work-up to evaluate the feasibility of a revascularization procedure were randomly assigned to undergo either MR angiography or CT angiography. Clinical utility was assessed with therapeutic confidence (scale of 0-10) at initial imaging and with the need for additional imaging. Patient outcomes included ankle-brachial index, maximum walking distance, change in clinical status, and health-related quality of life. Actual diagnostic and therapeutic costs were calculated from the hospital perspective. Differences between group means were calculated with unpaired t tests and 95% confidence intervals. A total of 157 consecutive patients with peripheral arterial disease were prospectively randomized to undergo MR angiography (51 men, 27 women; mean age, 63 years) or CT angiography (50 men, 29 women; mean age, 64 years). For one of the 78 patients in the MR group, no data were available. Mean confidence for MR angiography (7.7) was slightly lower than that for CT angiography (8.0, P = .8). During 6 months of follow-up, 13 patients in the MR group compared with 10 patients in the CT group underwent additional vascular imaging (P = .5). Although not statistically significant, there was a consistent trend of less improvement in the MR group across all patient outcomes. The average cost for diagnostic imaging was 359 ($438) higher in the MR group than in the CT group (95% confidence interval: 209, 511 [$255, $623]; P < .001). Therapeutic costs were higher in the MR group, but the difference was not significant. The results suggest that CT angiography has some advantages over MR angiography in the initial evaluation of peripheral arterial disease.

Computed Tomography-Generated Templates: A New Approach to Frontal Sinus Osteoplastic Flap Surgery

The aim of this study was to present a new technique for frontal sinus template creation used in osteoplastic flap surgery, obviating the need for the traditional 6-ft Caldwell radiograph. Seventeen human cadaver skulls were studied prospectively. Using digital addition algorithms of sequential coronal computed tomography (CT) images of the frontal sinus to create a composite image, an image is printed to 1 cm = 1 cm scale. A frontal sinus template was created using this processed image and compared with a control 6-ft Caldwell radiograph. The mean variance between corresponding vertical points on the templates was 0.71 mm (95% confidence interval, 0.56-0.87 mm). The mean variance between horizontal points was 1.11 mm (95% confidence interval, 0.97-1.28 mm). The mean difference in width was 2.46 mm. The plain film templates were always wider than the CT-generated templates. The CT-generated frontal sinus templates are virtually identical to the Caldwell radiograph-derived templates. They may obviate the need for additional imaging and minimize the potential errors commonly associated with 6-ft Caldwell templates.

A Clinical Probability Assessment and D-dimer Measurement Should Be the Initial Step in the Investigation of Suspected Venous Thromboembolism

I access to noninvasive investigation and a declining tolerance for diagnostic uncertainty has resulted in increasing numbers of patients who are referred with suspected venous thromboembolism (VTE), all of whom require objective testing to confirm or exclude the diagnosis. Hence, the proportion of patients with suspected VTE in whom the diagnosis is confirmed has fallen progressively from 30 to 35% in the 1970s and 1980s,1–3 to around 15 to 25% in the last decade.4–6 Indeed, prevalences of 10% have been reported.7 This trend is not inappropriate for a potentially fatal disorder that can be effectively treated, but it has important resource implications. The potential value of plasma d-dimers (d-ds) as an exclusionary test for VTE in an era of increasing numbers of negative imaging test results has been appreciated for more than a decade. However, although outcome studies performed in the last 5 years have shown that a negative d-d test result can be used to minimize the need for serial ultrasound testing in patients with suspected deep vein thrombosis (DVT),8,9 and to reduce the need for additional imaging in patients with suspected pulmonary embolism (PE) and nondiagnostic ventilation/perfusion (V/Q) scan results,10,11 their role as an exclusionary first-line test has been uncertain. The clinically useful d-d tests can be divided into two main groups that have important differences in performance characteristics. Rapid enzyme-linked immunosorbent assays (ELISAs) have very high sensitivity but low specificity, while modern latex agglutination tests tend to be somewhat less sensitive but more specific. More recently, highly sensitive latex agglutination tests have been developed, but they tend to have lower specificities so that their performance characteristics tend to resemble those of the ELISA assays. In the absence of an assay that is both highly sensitive and specific, two possible strategies for the initial use of d-d as an exclusionary tool are apparent. First, an assay chosen for high specificity could be used in combination with an additional factor such as low pretest probability (PTP), which identifies a subgroup with a low disease prevalence. This strategy is based on the concept that a test that had a sensitivity of, say, 90%, could not be used by itself to exclude VTE safely, but might be perfectly adequate when targeted to a subgroup of patients with a prior probability of, for example, only 5%. Second, an assay chosen for high sensitivity could be employed either as a stand-alone exclusionary test or in combination with an additional factor that identifies the major subgroup of patients in whom prevalence of VTE is not particularly high (ie, those with low or intermediate PTP). The proper evaluation of these approaches requires clinical outcome studies that will investigate the safety of withholding imaging and treatment in patients with suspected VTE on the basis of these strategies, together with an assessment of their exclusionary efficiency. Ideally, patients categorized as being “VTE-negative” should have a 3-month event rate similar to that observed in patients with suspected DVT who have normal venogram or serial *From the Department of Haematology, Guy’s & St. Thomas’ Trust, London, UK. Received February 25, 2002; revision accepted May 29, 2003. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (e-mail: permissions@chestnet.org). Correspondence to: James Kelly, Department of Haematology, Fourth Floor, North Wing, St. Thomas’ Hospital, London, UK SE1 7EH; e-mail: jameskelly@northbrookfm.fsnet.co.uk opinions/hypotheses

The utility of panoramic imaging of the temporomandibular joint in patients with temporomandibular disorders

Objective: The objective of this study was to evaluate the utility of panoramic imaging in assessment of patients with temporomandibular disorders (TMDs). Study Design: Fifty-five consecutive patients referred for diagnosis and management of facial pain and jaw dysfunction were included. A single examiner completed the history and clinical examination on all patients. All patients received panoramic imaging. On the basis of clinical and radiographic findings, a subset of patients received advanced imaging modalities. The panoramic radiographs were interpreted by 2 examiners; if any disagreement was noted, a third examiner interpreted the radiographs. Results: Seventy-five percent of the patients had complaints of facial pain, and 75% exhibited tenderness in masticatory muscles. Tenderness was present in TM joint regions in 62%. Altered bony anatomy was seen in 43.6% of panoramic radiographs. Panoramic imaging did not lead to changes in clinical diagnosis in any of the patients seen, although the findings on the radiographs did lead to requests for additional imaging studies in 3 cases, one of which was later referred for surgical intervention because of radiographic findings. Conclusion: Clinical findings may be of greater relevance leading to the diagnoses associated with TMD and to determination of the need for additional imaging rather than the use of panoramic imaging in all patients with facial pain and TMD.(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:236-9)

Safety and Speed of a CT Imaging Protocol for the Entire Cerebrovascular Axis During Acute Stroke

P33 Background: Newer generation CT scanners allow for rapid contrast enhanced imaging of the neurovascular axis during acute stroke. Methods: Using a multidetector CT scanner (GE Lightspeed®) we utilized the following imaging protocol in 38 consecutive patients: noncontrast axial CT of the brain (3.5 mm thickness), dynamic CT perfusion, and CT angiography from vertex to aortic arch (110 cc contrast using 18–20 ga IV at 3–4 cc/sec, scan delay 20 sec, 3:1 pitch, slice thickness 1.25 mm, 120 KV, 170 MA.) Results: Serum creatinine was unchanged in all subjects from baseline to hospital discharge; renal failure was not observed (table). One case of contrast extravasation occurred. Total imaging time was 27 ± 16 mins (mean ± SD; range 9–100 mins). Image quality was degraded by motion in 3 studies (7.9%). CTA was 91% sensitive (10 of 11 vessels) and 89% specific (32 of 36 vessels) for carotid disease compared with duplex, MRA and/or conventional angiography. Three of 3 cervical carotid occlusions were correctly identified by CTA. In the 35 patients imaged because of suspected stroke, 4 large vessel occlusions and 11 intracranial stenoses were revealed by review of acute CTA partition images. Conclusions: High-speed, multislice spiral CT scanners allow rapid and safe imaging of the entire cerebrovascular axis in patients with acute stroke and may reduce the need for additional imaging.

Differentiating normal from abnormal inferior thoracic paravertebral soft tissues on chest radiography in children.

The purposes of this investigation were to define the normal appearances, define factors that have the potential to influence appearance, and establish defined criteria to differentiate normal from abnormal appearances of posteroinferior paravertebral soft tissues on chest radiography in children. Paravertebral soft tissues were evaluated on frontal chest radiographs in 23 children with documented abnormalities and 275 children without abnormalities in the region. The frequency of visualization, course, width, and factors (patient positioning, age, and sex) potentially influencing the appearance of paravertebral soft tissues were determined. Inferolateral course and width greater than that of the adjacent pedicle were evaluated as criteria for abnormality. Only 28% of the children without abnormalities had paravertebral soft tissues visualized, and the frequency of visualization directly increased with age (p = 0.001). For identification of abnormal cases on the left side, width greater than the adjacent pedicle had a sensitivity of 100% and a specificity of 98%, and inferolateral course had a sensitivity of 86% and a specificity of 95%. Visualization on the right side (n = 5) was always abnormal. Six normal cases had a width greater than that of the adjacent pedicle on the left side on initial radiographs obtained with supine positioning and met normal criteria on repeated radiographs with upright positioning. Width greater than the adjacent pedicle is the best radiographic criterion for differentiation of abnormal from normal left-sided paravertebral soft tissues, particularly on radiographs obtained with upright positioning. Identifiable right-sided paravertebral soft tissue is always abnormal. These criteria are useful aids in determining the need for additional imaging, such as CT.

Safety and Speed of a CT Imaging Protocol for the Entire Cerebrovascular Axis During Acute Stroke

P33 Background: Newer generation CT scanners allow for rapid contrast enhanced imaging of the neurovascular axis during acute stroke. Methods: Using a multidetector CT scanner (GE Lightspeed®) we utilized the following imaging protocol in 38 consecutive patients: noncontrast axial CT of the brain (3.5 mm thickness), dynamic CT perfusion, and CT angiography from vertex to aortic arch (110 cc contrast using 18–20 ga IV at 3–4 cc/sec, scan delay 20 sec, 3:1 pitch, slice thickness 1.25 mm, 120 KV, 170 MA.) Results: Serum creatinine was unchanged in all subjects from baseline to hospital discharge; renal failure was not observed (table). One case of contrast extravasation occurred. Total imaging time was 27 ± 16 mins (mean ± SD; range 9–100 mins). Image quality was degraded by motion in 3 studies (7.9%). CTA was 91% sensitive (10 of 11 vessels) and 89% specific (32 of 36 vessels) for carotid disease compared with duplex, MRA and/or conventional angiography. Three of 3 cervical carotid occlusions were correctly identified by CTA. In the 35 patients imaged because of suspected stroke, 4 large vessel occlusions and 11 intracranial stenoses were revealed by review of acute CTA partition images. Conclusions: High-speed, multislice spiral CT scanners allow rapid and safe imaging of the entire cerebrovascular axis in patients with acute stroke and may reduce the need for additional imaging.