Cost utility analysis of radiographic screening for an orbital foreign body before MR imaging.

BACKGROUND AND PURPOSE: Our purpose was to evaluate the cost-effectiveness of clinical versus radiographic screening for an orbital foreign body before MR imaging. METHODS: Costs of screening were determined on the basis of published reports, disability rating guides, and a practice survey. Base case estimates were derived from published guidelines. A single-state change model was constructed using social cost as the unit of analysis. Sensitivity analysis was performed for each variable. The benefit of screening was avoidance of immediate, permanent, nonameliorable, unilateral blindness. RESULTS: Using base case estimates and a discount rate of zero, we calculated the cost of the current guideline as $328,580 per quality-adjusted life-year saved. Sensitivity analysis identified screening cost as a critical variable. Discount rates and effectiveness of foreign body removal also were found to be important factors. Probability of injury and prevalence of foreign body may impact the analysis. CONCLUSION: Clinical screening before radiography increases the cost-effectiveness of foreign body screening by an order of magnitude, assuming base case ocular foreign body removal rates. Asking the patient "Did a doctor get it all out?" serves this purpose. Occupational history by itself is not sufficient to mandate radiographic orbital screening. Current practice guidelines for foreign body screening should be altered.

Inflamed pericholecystic fat: color Doppler flow imaging and clinical features.

PURPOSE: To analyze the color Doppler flow imaging features and clinical importance of inflamed pericholecystic fat. MATERIALS AND METHODS: Forty patients with surgically proved right upper quadrant inflammatory lesions in the gallbladder or the pericholecystic space underwent color Doppler sonography (CDS). Findings in the pericholecystic space were correlated with those at computed tomography (CT) in four patients and with surgical findings in 40 patients. RESULTS: CDS performed in 12 (30%) of the 40 patients demonstrated echogenic pericholecystic masses greater than 1 cm in diameter that contained internal vascularity. CT in four patients and surgical findings in all 12 patients demonstrated inflamed fat adherent to the gallbladder. CONCLUSION: Identification with CDS of inflamed pericholecystic fat may provide preoperative information that could be pertinent in the decision to perform open or laparoscopic cholecystectomy in patients with acute cholecystitis.

Magnetic resonance imaging and measurement of blood flow.

Blood flow can be shown as a negative image with magnetic resonance spin-echo techniques or as a positive image with gradient-echo techniques. Phase contrast refers to techniques where structures can be seen because of flow-induced phase shifts. These techniques can show the presence (slow flow) and also the direction of flow. Gradient-echo techniques--including phase-contrast versions--can be used with cardiac synchronization to obtain multiple images during the cardiac cycle. These images can be viewed in a movie or cine format to provide dynamic information about blood flow. Blood flow can be measured by using contrast media in boluses or even more elegantly with phase-contrast methods. Clinical applications of flow measurements are growing rapidly. Phase-contrast or gradient-echo techniques can be used to create magnetic resonance angiography, which was first used to study the carotid bifurcation and intracranial circulation and is now being used throughout the body.

Chronic mesenteric ischemia: evaluation with phase-contrast cine MR imaging.

PURPOSE: To compare superior mesenteric artery (SMA) blood flow in healthy volunteers and patients with stenoses in the fasting state and after food intake by using phase-contrast (PC) cine magnetic resonance (MR) imaging. MATERIALS AND METHODS: Ten healthy subjects, four asymptomatic patients (three with 50% stenosis, one with 70% stenosis), and one symptomatic patient (with 80% stenosis) were studied. All subjects were studied after fasting at least 8 hours and 15, 30, and 45 minutes after ingesting a standard meal. RESULTS: In healthy volunteers, SMA blood flow at all postprandial intervals increased significantly compared with that obtained after fasting (P < or = .0005). The percentage change in SMA blood flow 30 minutes after food intake provided the best distinction between the healthy subjects, the asymptomatic patients, and the symptomatic patient. CONCLUSION: Cine PC MR imaging is an effective, noninvasive technique for measuring SMA blood flow.

Spiral CT of renal artery stenosis: comparison of three-dimensional rendering techniques.

PURPOSE: To evaluate the accuracy of computed tomographic (CT) angiography in the detection of renal artery stenosis (RAS). MATERIALS AND METHODS: CT angiography was performed in 31 patients undergoing conventional renal arteriography. CT angiographic data were reconstructed with shaded surface display (SSD) and maximum-intensity projection (MIP). Stenosis was graded with a four-point scale (grades 0-3). The presence of mural calcification, poststenotic dilatation, and nephrographic abnormalities was also noted. RESULTS: CT angiography depicted all main (n = 62) and accessory (n = 11) renal arteries that were seen at conventional arteriography. MIP CT angiography was 92% sensitive and 83% specific for the detection of grade 2-3 stenoses (> or = 70% stenosis). SSD CT angiography was 59% sensitive and 82% specific for the detection of grade 2-3 stenoses. The accuracy of stenosis grading was 80% with MIP and 55% with SSD CT angiography. Poststenotic dilatation and the presence of an abnormal nephrogram were 85% and 98% specific, respectively. CONCLUSION: CT angiography shows promise in the diagnosis of RAS. The accuracy of CT angiography varies with the three-dimensional rendering technique employed.

Dynamic breath-hold multiplanar spoiled gradient-recalled MR imaging with gadolinium enhancement for differentiating hepatic hemangiomas from malignancies at 1.5 T.

PURPOSE: To compare the enhancement patterns of focal liver lesions at dynamic breath-hold gadolinium-enhanced multiplanar spoiled gradient-recalled (SPGR) magnetic resonance (MR) imaging with T2 relaxation times in the differentiation of liver hemangiomas from malignancies. MATERIALS AND METHODS: Forty-seven patients with focal liver lesions underwent MR imaging with spin-echo and gadolinium-enhanced multiplanar SPGR techniques. T2 relaxation times and enhancement patterns were compared for accuracy in liver lesion characterization. RESULTS: Enhancement patterns allowed better characterization of liver lesions than did T2 relaxation times. Only specific patterns of contrast enhancement indicated a hemangioma. Although 18 of the 33 malignancies and 10 of the 12 hemangiomas showed progressive centripetal hyperintense enhancement, only hemangiomas filled in with hyperintense peripheral nodules. Malignancies often filled in with hyperintense thick rinds. CONCLUSION: Gadolinium-enhanced multiplanar SPGR imaging allows more accurate characterization of liver lesions than does T2 relaxation time.

Three-dimensional spiral computed tomographic angiography: an alternative imaging modality for the abdominal aorta and its branches.

PURPOSE: We sought to apply a new technique of computed tomographic angiography (CTA) to the preoperative and postoperative assessment of the abdominal aorta and its branches. METHODS: After a peripheral intravenous contrast injection, the patient is continuously advanced through a spiral CT scanner, while maintaining a 30-second breath-hold. Thirty-five patients with abdominal aortic, renal, and visceral arterial disease have undergone CTA. RESULTS: Diagnostic three-dimensional images were obtained in patients with aortic aneurysms (n = 9), aortic dissections (n = 4), and mesenteric artery stenoses (n = 4). The technique has also been used to assess vessels after operative reconstruction or endovascular intervention in 18 patients. These preliminary studies have correlated well with conventional arteriographic findings. In aneurysmal disease both the lumen and mural thrombus and associated renal artery stenoses are visualized. The true and false channels of aortic dissections and the perfusion source of the visceral vessels are clearly shown; patency of visceral and renal reconstruction or stent placement are confirmed. CTA is relatively noninvasive and can be completed in less time than conventional angiography with less radiation exposure. CONCLUSIONS: This initial experience suggests that CTA may be a valuable alternative to conventional arteriography in the evaluation of the aorta and its branches.

Three-dimensional spiral CT angiography of the abdomen: initial clinical experience.

Spiral computed tomography (CT) is a new technology that couples continuous tube rotation with continuous table feed. This allows compilation of a data set that has continuous anatomic information without the establishment of arbitrary boundaries at section interfaces as in conventional CT. The unique method of data collection of the spiral scanner has been combined with a dynamic intravenous contrast material bolus to image abdominal vasculature, specifically, the aorta, renal arteries, and splanchnic circulation. Through various techniques of image processing, including surface renderings and maximum-intensity projections, it is possible to obtain excellent anatomic detail of the aorta and its major branches. The authors applied this technique in 15 patients and reliably saw third-order aortic branches as well as third-order splenic-portal venous anatomic detail with remarkable clarity. Pathologic conditions detected include stenotic renal arteries, abdominal aortic dissection, abdominal aortic aneurysm, and celiac bypass graft occlusion.

CT angiography with spiral CT and maximum intensity projection.

The authors describe a technique for obtaining angiographic images by means of spiral computed tomography (CT), preprocessing of reconstructed three-dimensional sections to suppress bone, and maximum intensity projection. The technique has some limitations, but preliminary results in 48 patients have shown excellent anatomic correlation with conventional angiography in studies of the abdomen, the circle of Willis in the brain, and the extracranial carotid arteries. With continued development and evaluation, CT angiography may prove useful as a screening tool or replacement for conventional angiography in some patients.

CT of fundoplication.

To determine the CT findings postfundoplication, we retrospectively compared CT in 22 postfundoplication patients with CT in 22 patients with unrepaired hiatal hernias and gastroesophageal (GE) junction abnormalities and 24 patients with gastric or esophageal carcinoma involving the GE junction. Seventeen of the 22 postfundoplication patients had undergone a Nissen procedure. Of the 22 patients, 11 had esophageal dilatation, 14 had GE junction masses, 4 had esophageal wall thickening, 7 had surgical clips, and none had hepatic metastases or upper abdominal lymphadenopathy. Statistically, on CT, postfundoplication patients are more likely to have a GE junction mass (p = 0.023) and least likely to have wall thickening (p = 0.021). Nonetheless, because the findings occur frequently in each group, they are not diagnostic in the individual patient. However, 11 of 12 post-Nissen masses had the unique finding of an oval or linear central fat density within the mass. This finding was absent in the other postfundoplication masses and in those patients with repaired hiatal hernia or tumor. We conclude that pseudomasses occur on CT postfundoplication and can be indistinguishable from hiatal hernias and GE junction neoplasms unless a central fat density is present.

Primary peritoneal neuroblastoma: computed tomography findings.

Primary peritoneal tumors are rare neoplasms. The computed tomography findings in an adult patient with a primary peritoneal neuroblastoma are described. Discussion of these uncommon neoplasms and this unusual presentation of neuroblastoma forms the basis of this report.

CT demonstration of calcified liver metastases in medullary thyroid carcinoma.

The presence of calcification can be found in greater than 50% of thyroid cancers. With medullary thyroid carcinoma, calcifications may be found in the primary lesion as well as in metastatic lymph nodes and in the liver. We report two cases of medullary thyroid carcinoma with associated calcified liver metastases.