Helical CT of urinary calculi

Effect of stone composition, stone size, and scan collimation

K. Chee Saw, James A. McAteer, Ashish G. Monga, Gonzalo T. Chua, James E. Lingeman, James Williams

Research output: Contribution to journalArticle

128 Citations (Scopus)

Abstract

OBJECTIVE. Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan collimation width on the measurement of attenuation in vitro. MATERIALS AND METHODS. One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different collimations. A model, based on the physics of helical CT, was used to predict the effect of scan collimation width and stone size on measured attenuation. RESULTS. At a 1-mm collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which overlapped and showed the highest values. At a wider collimation, attenuation was lower and the ability to differentiate stone composition was lost. Attenuation also decreased with smaller stones. At a 10-mm collimation, some uric acid stones (<~6 mm) and other stones (<~4 mm) had very low attenuation, so low that they could remain undetected on helical CT. The model predicted well the degree that attenuation was affected by stone size and collimation width. CONCLUSION. Stone composition and stone size, relative to CT collimation, independently influenced CT attenuation. The effect of stone size and collimation generally conformed to the model's predictions. We determined that small stones with low attenuation can be overlooked on helical CT.

Original languageEnglish
Pages (from-to)329-332
Number of pages4
JournalAmerican Journal of Roentgenology
Volume175
Issue number2
StatePublished - Aug 2000

Fingerprint

Urinary Calculi
Spiral Computed Tomography
Uric Acid
Calcium Oxalate
Cystine
Physics
Durapatite
Therapeutics

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

Chee Saw, K., McAteer, J. A., Monga, A. G., Chua, G. T., Lingeman, J. E., & Williams, J. (2000). Helical CT of urinary calculi: Effect of stone composition, stone size, and scan collimation. American Journal of Roentgenology, 175(2), 329-332.

Helical CT of urinary calculi : Effect of stone composition, stone size, and scan collimation. / Chee Saw, K.; McAteer, James A.; Monga, Ashish G.; Chua, Gonzalo T.; Lingeman, James E.; Williams, James.

In: American Journal of Roentgenology, Vol. 175, No. 2, 08.2000, p. 329-332.

Research output: Contribution to journalArticle

Chee Saw, K, McAteer, JA, Monga, AG, Chua, GT, Lingeman, JE & Williams, J 2000, 'Helical CT of urinary calculi: Effect of stone composition, stone size, and scan collimation', American Journal of Roentgenology, vol. 175, no. 2, pp. 329-332.
Chee Saw, K. ; McAteer, James A. ; Monga, Ashish G. ; Chua, Gonzalo T. ; Lingeman, James E. ; Williams, James. / Helical CT of urinary calculi : Effect of stone composition, stone size, and scan collimation. In: American Journal of Roentgenology. 2000 ; Vol. 175, No. 2. pp. 329-332.
@article{34504d6b7fe3431b91acf2c29970b1f0,
title = "Helical CT of urinary calculi: Effect of stone composition, stone size, and scan collimation",
abstract = "OBJECTIVE. Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan collimation width on the measurement of attenuation in vitro. MATERIALS AND METHODS. One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different collimations. A model, based on the physics of helical CT, was used to predict the effect of scan collimation width and stone size on measured attenuation. RESULTS. At a 1-mm collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which overlapped and showed the highest values. At a wider collimation, attenuation was lower and the ability to differentiate stone composition was lost. Attenuation also decreased with smaller stones. At a 10-mm collimation, some uric acid stones (<~6 mm) and other stones (<~4 mm) had very low attenuation, so low that they could remain undetected on helical CT. The model predicted well the degree that attenuation was affected by stone size and collimation width. CONCLUSION. Stone composition and stone size, relative to CT collimation, independently influenced CT attenuation. The effect of stone size and collimation generally conformed to the model's predictions. We determined that small stones with low attenuation can be overlooked on helical CT.",
author = "{Chee Saw}, K. and McAteer, {James A.} and Monga, {Ashish G.} and Chua, {Gonzalo T.} and Lingeman, {James E.} and James Williams",
year = "2000",
month = "8",
language = "English",
volume = "175",
pages = "329--332",
journal = "American Journal of Roentgenology",
issn = "0361-803X",
publisher = "American Roentgen Ray Society",
number = "2",

}

TY - JOUR

T1 - Helical CT of urinary calculi

T2 - Effect of stone composition, stone size, and scan collimation

AU - Chee Saw, K.

AU - McAteer, James A.

AU - Monga, Ashish G.

AU - Chua, Gonzalo T.

AU - Lingeman, James E.

AU - Williams, James

PY - 2000/8

Y1 - 2000/8

N2 - OBJECTIVE. Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan collimation width on the measurement of attenuation in vitro. MATERIALS AND METHODS. One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different collimations. A model, based on the physics of helical CT, was used to predict the effect of scan collimation width and stone size on measured attenuation. RESULTS. At a 1-mm collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which overlapped and showed the highest values. At a wider collimation, attenuation was lower and the ability to differentiate stone composition was lost. Attenuation also decreased with smaller stones. At a 10-mm collimation, some uric acid stones (<~6 mm) and other stones (<~4 mm) had very low attenuation, so low that they could remain undetected on helical CT. The model predicted well the degree that attenuation was affected by stone size and collimation width. CONCLUSION. Stone composition and stone size, relative to CT collimation, independently influenced CT attenuation. The effect of stone size and collimation generally conformed to the model's predictions. We determined that small stones with low attenuation can be overlooked on helical CT.

AB - OBJECTIVE. Helical CT has become the preferred methodology for identifying urinary calculi. However, the ability to predict stone composition, which influences patient treatment, depends on the accurate measurement of the radiographic attenuation of stones. We studied the effects of stone composition, stone size, and scan collimation width on the measurement of attenuation in vitro. MATERIALS AND METHODS. One hundred twenty-seven human urinary calculi of known composition and size were scanned at 120 kVp, 240 mA, and a 1:1 pitch at different collimations. A model, based on the physics of helical CT, was used to predict the effect of scan collimation width and stone size on measured attenuation. RESULTS. At a 1-mm collimation, stone groups could be differentiated by attenuation: the attenuation of uric acid was less than that of cystine or struvite, which overlapped; these were less than the attenuation of calcium oxalate monohydrate, which was in turn lower than that of brushite and hydroxyapatite, which overlapped and showed the highest values. At a wider collimation, attenuation was lower and the ability to differentiate stone composition was lost. Attenuation also decreased with smaller stones. At a 10-mm collimation, some uric acid stones (<~6 mm) and other stones (<~4 mm) had very low attenuation, so low that they could remain undetected on helical CT. The model predicted well the degree that attenuation was affected by stone size and collimation width. CONCLUSION. Stone composition and stone size, relative to CT collimation, independently influenced CT attenuation. The effect of stone size and collimation generally conformed to the model's predictions. We determined that small stones with low attenuation can be overlooked on helical CT.

UR - http://www.scopus.com/inward/record.url?scp=0342656568&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0342656568&partnerID=8YFLogxK

M3 - Article

VL - 175

SP - 329

EP - 332

JO - American Journal of Roentgenology

JF - American Journal of Roentgenology

SN - 0361-803X

IS - 2

ER -