“ Determination of the maximum axial area may improve the accuracy in predicting spontaneous passage of ureteral stones, particularly those between 5 and 10 mm.”
CT-Based Determination of Maximum Ureteral Stone Area: A Predictor of Spontaneous Passage
Demehri S et al.
AJR 2012: 198:603-608
Nephrolithiasis: Imaging Studies
- Ultrasound
- CT scanning
- Excretory Urography
- MR Nephrourography
Nephrolithiasis: What does the referring clinician need to know?
- Presence or absence of calculus
- Location of calculus (kidney, ureter, bladder)
- Number of stones
- Stone diameter
- Presence of additional findings (i.e. acute pyelonephritis)
Nephrolithiasis: What Surgeons Need to Know
Eisner BH et al.=
AJR 2011; 196:1274-1278
Can renal calculi be missed on CT?
- 99 percent of stones can be detected ranging from calcium based stones to radiolucent stones like uric acid, xanthine, or cystine.
- The one percent of stones that can be missed are pure matrix stones or stones composed of protease inhibitor, indinavir
“ Not only does this study enable the detection of stones of all sizes, but in its area of examination from above the kidneys to below the bladder base, it enables the evaluation of other urinary and extraurinary abnormalities that may be contributing to symptoms of acute flank pain.”
Nephrolithiasis: What Surgeons Need to Know
Eisner BH et al.
AJR 2011; 196:1274-1278
"In patients with known calculi greater than 3 mm being evaluated for recurrent pain or when calculi 3 mm or smaller are viewed as not clinically important due to their spontaneous passage, a protocol with up to 75% reduction in dose should be considered."
Urinary Calculi: Radiation Dose Reduction of 50% and 75% at CT-Effect on Sensitivity
Ciaschini MW et al.
Radiology 2009; 251:105-111
"There was no statistically significant difference in sensitivity with a 50% or 75% dose reduction for the detection of calculi greater than 3 mm in diameter."
Urinary Calculi: Radiation Dose Reduction of 50% and 75% at CT-Effect on Sensitivity
Ciaschini MW et al.
Radiology 2009; 251:105-111
"There was no significant differences between the 100% examinations and the 50% and 25% examinations for the detection of calculi greater than 3 mm."
Urinary Calculi: Radiation Dose Reduction of 50% and 75% at CT-Effect on Sensitivity
Ciaschini MW et al.
Radiology 2009; 251:105-111
"For all stones, stone size estimation is improved in the coronal plane, and the difference is significantly more pronounced for vertically oriented stones, which may be underestimated in the axial plane by more than 20%."
Assesment of Urinary Tract Calculi With 64-MDCT: The Axial Versus Coronal Plane
Metser U et al.
AJR 2009; 192:1509-1513
"The detection of stones and estimation of maximal stone diameter were improved using coronal reformations. The conspicuity of stones and diagnostic confidence in identifying stones smaller than 5 mm in diameter were also improved on the coronal plane."
Assesment of Urinary Tract Calculi With 64-MDCT: The Axial Versus Coronal Plane
Metser U et al.
AJR 2009; 192:1509-1513
"On arterial phase scans, 75% of the renal calculi and all renal calculi larger than 5 mm were detected; the attenuation of the calculi had a significant correlation to detectability."
Detection of Renal Calculi on Late Arterial Phase Computed Tomography Images: Are Noncontrast Scans Always Needed to Detect Renal Calculi?
Kawamoto S, Horton KM, Fishman EK
J Comput Assist Tomogr 2008;32:859-864
"The reduced radiation CT protocol (30 mAs) resulted in similar detection of renal stones 3.0 mm or larger compared with the standard radiation protocol (100 mAs) while reducing patient exposure by as much as 70%."
Effect of Reduced Radiation CT Protocols on the Detection of Renal Calculi
Jin DH et al
Radiology 2010; 255;100-107
"Detection of 2.0 mm stones is difficult, even with standard CT protocols by using 5 mm section reconstruction; this may lead to a significant overestimation of sensitivity in clinical studies where a conventional CT scan is used as a reference standard."
Effect of Reduced Radiation CT Protocols on the Detection of Renal Calculi
Jin DH et al
Radiology 2010; 255;100-107
"In patients with known calculi greater than 3 mm being evaluated for recurrent pain or when calculi 3 mm or smaller are viewed as not clinically important due to their spontaneous passage, a protocol with up to 75% reduction in dose should be considered.”
Urinary Calculi: Radiation Dose Reduction of 50% and 75% at CT-Effect on Sensitivity
Ciaschini MW et al.
Radiology 2009; 251:105-111
"There was no statistically significant difference in sensitivity with a 50% or 75% dose reduction for the detection of calculi greater than 3 mm in diameter."
Urinary Calculi: Radiation Dose Reduction of 50% and 75% at CT-Effect on Sensitivity
Ciaschini MW et al.
Radiology 2009; 251:105-111
"There was no significant differences between the 100% examinations and the 50% and 25% examinations for the detection of calculi greater than 3 mm."
Urinary Calculi: Radiation Dose Reduction of 50% and 75% at CT-Effect on Sensitivity
Ciaschini MW et al.
Radiology 2009; 251:105-111
"Coronal reformations from MDCT do not improve urinary stone detection but may reduce evaluation time; however, there is a danger of missing additional findings. Coronal reformations from thick (i.e. 3-5mm) axial sections may result in reduced detection of small stones and should therefore be avoided."
Unenhanced MDCT in Patients with Suspected Urinary Tract Stone Disease: Do Coronal Reformations Improve Diagnostic Performance Memarsadeghi M et al.
AJR:189, August 2007,329
Urolithiasis
Very common:
- 12% of the population - Of those, 50% will have recurrence within 5 years
- Accounts for up to 1/100 hospital admissions
- Incidence increasing
Who is affected?:
- Males more than females
- More common in caucasians
- Usually present between 20-40 years of age
"Multidetector computed tomography has become the imaging study of choice for the diagnosis of urinary tract calculi, investigation of hematuria, and the characterization of renal masses."
Imaging for Renal Colic and Hematuria
Miller JC et al.
JACR 2006:814-817.
