Background fluctuation of kidney function versus contrast-induced nephrotoxicity.

OBJECTIVE: The reported incidence of contrast-induced acute kidney injury varies widely. Almost no studies have been conducted to quantify the background fluctuation of kidney function of patients receiving iodinated contrast medium. The purpose of this study was a retrospective comparison of the incidence of acute kidney injury among patients undergoing CT with low-osmolar (iohexol) or isoosmolar (iodixanol) contrast medium with the incidence among patients undergoing CT without contrast administration. MATERIALS AND METHODS: Creatinine concentration and estimated glomerular filtration rate were evaluated for 11,588 patients. Rates of acute kidney injury (defined as a 0.5 mg/dL increase in serum creatinine concentration or a 25% or greater decrease in estimated glomerular filtration rate within 3 days after CT) were compared among groups and stratified according to creatinine concentration and estimated glomerular filtration rate before the imaging examination. RESULTS: In all groups, the incidence of acute kidney injury increased with increasing baseline creatinine concentration. No significant difference in incidence of presumed contrast-induced kidney injury was identified between the isoosmolar contrast medium and the control groups. The incidence of acute kidney injury in the low-osmolar contrast medium cohort paralleled that of the control cohort up to a creatinine level of 1.8 mg/dL, but increases above this level were associated with a higher incidence of acute kidney injury. CONCLUSION: We identified a high incidence of acute kidney injury among control subjects undergoing unenhanced CT. The incidence of creatinine elevation in this group was statistically similar to that in the isoosmolar contrast medium group for all baseline creatinine values and all stages of chronic kidney disease. These findings suggest that the additional risk of acute kidney injury accompanying administration of contrast medium (contrast-induced nephrotoxicity) may be overstated and that much of the creatinine elevation in these patients is attributable to background fluctuation, underlying disease, or treatment.

Primary 2D versus primary 3D polyp detection at screening CT colonography.

OBJECTIVE: Disparate results from the existing large CT colonography (CTC) trials suggest that 2D polyp detection is less sensitive than 3D detection, but no direct evidence exists to support this claim. Our goal was to assess the sensitivity of primary 2D polyp detection with cases from the Department of Defense CTC screening trial and compare results with the primary 3D evaluation and previous 2D CTC trials. MATERIALS AND METHODS: Ten radiologists, blinded to polyp findings, retrospectively interpreted 730 consecutive colonoscopy-proven CTC cases in asymptomatic adults using a primary 2D approach, with 3D reserved for problem solving. Primary 2D CTC performance was compared with the primary 3D CTC results from the original trial of 1,233 asymptomatic adults. The 10 2D reviewers were significantly more experienced in CTC interpretation (> 100 cases interpreted) than the six reviewers from the original 3D trial. RESULTS: Primary 2D CTC sensitivity for adenomas > or = 6 mm was 44.1% (56/127), compared with 85.7% (180/210) at 3D (p < 0.001). Sensitivity of 2D CTC for adenomas > or = 10 mm was 75.0% (27/36) compared with 92.2% (47/51) at 3D (p = 0.027). Similar sensitivity trends were seen for the by-patient analysis and for all polyps at the 6-mm and 10-mm thresholds. By-patient specificity for 2D evaluation at the 10-mm threshold was 98.1% (676/689), compared with 97.4% (1,131/1,161) at 3D evaluation (p = 0.336). CONCLUSION: Primary 2D CTC is less sensitive than primary 3D CTC for polyp detection in low-prevalence screening cohorts. The disappointing 2D sensitivity in this study was very similar to results obtained with primary 2D evaluation in previous CTC trials.

Effect of colonic distention on superiority of supine versus prone views in screening computed tomographic colonography.

PURPOSE: The purpose of this study was to evaluate the effect of colonic distention in computed tomographic colonography (CTC). METHODS: There were 3941 adults who underwent CTC with distention by either carbon dioxide (CO(2); n=2099) or room air (RA; n= 1733). Supine distention and prone distention were prospectively assessed and compared. RESULTS: With CO(2), distention on the supine view was superior in 72.1% (1514/2099) of the patients; with RA, the prone view was better in 56.8% (984/1733) (P<.0001). CONCLUSIONS: With CO(2), the supine data set is more often the superior view, whereas with RA, the prone data set is more often preferred.

Abdominal manifestations of cystic fibrosis in older children and adults.

OBJECTIVE: Cystic fibrosis (CF) is a disorder of exocrine gland function of which the gene mutation has been existing for thousands of years. With recent medical advances, neonates presently affected have a life expectancy of 40 years. The common gastrointestinal presentations of CF patients, including pancreatic, hepatobiliary, and bowel manifestations, are thus important to recognize. CONCLUSION: Gastrointestinal manifestations of CF are varied yet common and thus increasingly important to recognize. The sonographic, CT, and MRI abdominal findings in older children and adults with CF are presented.

Percutaneous sacroplasty for the treatment of sacral insufficiency fractures.

OBJECTIVE: The purpose of this article is to illustrate the effectiveness and utility of percutaneous sacroplasty in the treatment of sacral insufficiency fractures. We also outline the technical considerations in performing the procedure. CONCLUSION: Percutaneous sacroplasty is an effective treatment for sacral insufficiency fractures. Most patients experience significant relief within the first 48 hr.

Comparison of iodixanol with iohexol for delayed pelvic venous opacification: a preliminary study of potential use for CT venography.

OBJECTIVE: The goal of this prospective randomized study was to determine whether isosmolar contrast material offers an advantage over low-osmolar contrast material for delayed venous opacification in CT venography. SUBJECTS AND METHODS. We prospectively enrolled 200 adult outpatients. Patients were randomized to receive either the low-osmolar (hyperosmolar to blood) nonionic contrast medium, iohexol, or the nonionic isosmolar contrast medium, iodixanol. Images were obtained before contrast administration and 180 sec after contrast administration through the pelvis at the level of the external iliac vessels. Opacification of the external iliac vessels was assessed both objectively and subjectively. RESULTS: The arterial and venous densities before contrast administration were approximately 45 H for both groups. On delayed images obtained after contrast administration, the mean venous density was 95.2 H for iohexol and 101.4 H for iodixanol. Changes in venous density due to administration of iohexol and iodixanol were 49.8 and 56.1 H, respectively. This 12.5% difference was highly significant (p = 0.002). Sixty-six percent of the images in the iodixanol group were rated either 4 (good) or 5 (excellent), whereas only 36% of the iohexol group achieved a similar rating on our subjective rating scale. This difference was statistically significant (chi(2) = 16.4, p < 0.001, df = 1). CONCLUSION: Our study shows that isosmolar contrast material provides significant improvement in delayed opacification of the external iliac vessels in comparison with conventional low-osmolar contrast medium (hyperosmolar to blood).

Imaging of the brain, including diffusion-weighted imaging in methylmalonic acidemia.

Methylmalonic acidemia (MMA) is a multifactorial autosomal recessive inborn error of organic acid metabolism, often presenting with neurologic findings. We report the imaging findings in a case of a child with classic neurological and laboratory findings for MMA. Imaging studies demonstrated abnormalities within the basal ganglia, particularly the globi pallidi (GP). Diffusion-weighted abnormalities seen in patients with MMA during an acute episode of metabolic acidosis and at follow-up are discussed. The authors are aware of only one prior report of serial examinations demonstrating resolution of restricted diffusion in the GP. The biochemical and pathophysiologic basis of the imaging findings of MMA are explained.