| Conspicuity of renal calculi at unenhanced CT: effects of calculus composition and size and CT technique. | |
| | |
MedLine Citation:
|
PMID: 12354990 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
PURPOSE: To determine the effects of calculus size, composition, and technique (kilovolt and milliampere settings) on the conspicuity of renal calculi at unenhanced helical computed tomography (CT). MATERIALS AND METHODS: The authors performed unenhanced CT of a phantom containing 188 renal calculi of varying size and chemical composition (brushite, cystine, struvite, weddellite, whewellite, and uric acid) at 24 combinations of four kilovolt (80-140 kV) and six milliampere (200-300 mA) levels. Two radiologists, who were unaware of the location and number of calculi, reviewed the CT images and recorded where stones were detected. These observations were compared with the known positions of calculi to generate true-positive and false-positive rates. Logistic regression analysis was performed to investigate the effects of stone size, composition, and technique and to generate probability estimates of detection. Interobserver agreement was estimated with kappa statistics. RESULTS: Interobserver agreement was high: the mean kappa value for the two observers was 0.86. The conspicuity of stone fragments increased with increasing kilovolt and milliampere levels for all stone types. At the highest settings (140 kV and 300 mA), the detection threshold size (ie, the size of calculus that had a 50% probability of being detected) ranged from 0.81 mm + 0.03 (weddellite) to 1.3 mm + 0.1 (uric acid). Detection threshold size for each type of calculus increased up to 1.17-fold at lower kilovolt settings and up to 1.08-fold at lower milliampere settings. CONCLUSION: The conspicuity of small renal calculi at CT increases with higher kilovolt and milliampere settings, with higher kilovolts being particularly important. Small uric acid calculi may be imperceptible, even with maximal CT technique. |
| | |
Authors:
|
Mitchell E Tublin; Michael E Murphy; David M Delong; Franklin N Tessler; Mark A Kliewer |
Publication Detail:
|
Type: Journal Article |
Journal Detail:
|
Title: Radiology Volume: 225 ISSN: 0033-8419 ISO Abbreviation: Radiology Publication Date: 2002 Oct |
Date Detail:
|
Created Date: 2002-09-30 Completed Date: 2002-10-17 Revised Date: 2004-11-17 |
Medline Journal Info:
|
Nlm Unique ID: 0401260 Medline TA: Radiology Country: United States |
Other Details:
|
Languages: eng Pagination: 91-6 Citation Subset: AIM; IM |
Affiliation:
|
Department of Radiology, Albany Medical College, NY, USA. tublinme@msx.upmc.edu |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Humans Kidney Calculi / chemistry, pathology, radiography* Logistic Models Models, Statistical Observer Variation Phantoms, Imaging Tomography, X-Ray Computed* / methods |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Renal cyst pseudoenhancement: evaluation with an anthropomorphic body CT phantom.
Next Document: Acute cardiac transplant rejection: detection and grading with MR imaging with a blood pool contrast...