Angiomyolipoma with minimal fat on MDCT

Can counts of negative-attenuation pixels aid diagnosis?

C. Simpfendorfer, B. R. Herts, G. A. Motta-Ramirez, D. S. Lockwood, M. Zhou, M. Leiber, E. M. Remer

Research output: Contribution to journalComment/debate

Abstract

Objective: The purpose of this study was to determine whether counts of pixels with subzero attenuation on CT scans can aid in the diagnosis of renal angiomyolipoma with minimal fat. Materials and Methods: Of 33 angiomyolipomas identified among 719 renal masses resected from 702 patients over 4 years, 15 masses in 15 patients were prospectively diagnosed on the basis of the presence of fat at MDCT. The 18 patients with minimal-fat angiomyolipoma and a matched (age, sex, tumor size) cohort of patients with renal cell carcinoma were included in this study. Three radiologists independently counted the number of pixels with attenuation less than -10, -20, and -30 HU. Receiver operating characteristic analysis of the number of pixels at each cutoff was used to calculate sensitivity, specificity, and positive predictive value with the following criteria: 1, more than 10 pixels less than -20 HU; 2, more than 20 pixels less than -20 HU; 3, more than 5 pixels less than -30 HU. Results: Using criterion 1, reader A identified six angiomyolipomas; reader B, five; and reader C, two. The combined sensitivity was 24%; specificity, 98%; and positive predictive value, 69%. Using criterion 2, reader A identified three angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 17%; specificity, 100%; and positive predictive value, 100%. Using criterion 3, reader A identified four angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 18%; specificity, 100%; and positive predictive value, 100%. Conclusion: CT findings of more than 20 pixels with attenuation less than -20 HU and more than 5 pixels with attenuation less than -30 HU have a positive predictive value of 100% in detection of angiomyolipoma, but most angiomyolipomas with minimal fat cannot be reliably identified on the basis of an absolute pixel count.

Original languageEnglish (US)
Pages (from-to)101
Number of pages1
JournalInternational Braz J Urol
Volume35
Issue number1
DOIs
StatePublished - Jan 1 2009

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Angiomyolipoma
Fats
Kidney
Renal Cell Carcinoma
ROC Curve
Sensitivity and Specificity

ASJC Scopus subject areas

  • Urology

Cite this

Simpfendorfer, C., Herts, B. R., Motta-Ramirez, G. A., Lockwood, D. S., Zhou, M., Leiber, M., & Remer, E. M. (2009). Angiomyolipoma with minimal fat on MDCT: Can counts of negative-attenuation pixels aid diagnosis? International Braz J Urol, 35(1), 101. https://doi.org/10.1590/S1677-55382009000100019

Angiomyolipoma with minimal fat on MDCT : Can counts of negative-attenuation pixels aid diagnosis? / Simpfendorfer, C.; Herts, B. R.; Motta-Ramirez, G. A.; Lockwood, D. S.; Zhou, M.; Leiber, M.; Remer, E. M.

In: International Braz J Urol, Vol. 35, No. 1, 01.01.2009, p. 101.

Research output: Contribution to journalComment/debate

Simpfendorfer, C, Herts, BR, Motta-Ramirez, GA, Lockwood, DS, Zhou, M, Leiber, M & Remer, EM 2009, 'Angiomyolipoma with minimal fat on MDCT: Can counts of negative-attenuation pixels aid diagnosis?', International Braz J Urol, vol. 35, no. 1, pp. 101. https://doi.org/10.1590/S1677-55382009000100019
Simpfendorfer, C. ; Herts, B. R. ; Motta-Ramirez, G. A. ; Lockwood, D. S. ; Zhou, M. ; Leiber, M. ; Remer, E. M. / Angiomyolipoma with minimal fat on MDCT : Can counts of negative-attenuation pixels aid diagnosis?. In: International Braz J Urol. 2009 ; Vol. 35, No. 1. pp. 101.
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abstract = "Objective: The purpose of this study was to determine whether counts of pixels with subzero attenuation on CT scans can aid in the diagnosis of renal angiomyolipoma with minimal fat. Materials and Methods: Of 33 angiomyolipomas identified among 719 renal masses resected from 702 patients over 4 years, 15 masses in 15 patients were prospectively diagnosed on the basis of the presence of fat at MDCT. The 18 patients with minimal-fat angiomyolipoma and a matched (age, sex, tumor size) cohort of patients with renal cell carcinoma were included in this study. Three radiologists independently counted the number of pixels with attenuation less than -10, -20, and -30 HU. Receiver operating characteristic analysis of the number of pixels at each cutoff was used to calculate sensitivity, specificity, and positive predictive value with the following criteria: 1, more than 10 pixels less than -20 HU; 2, more than 20 pixels less than -20 HU; 3, more than 5 pixels less than -30 HU. Results: Using criterion 1, reader A identified six angiomyolipomas; reader B, five; and reader C, two. The combined sensitivity was 24{\%}; specificity, 98{\%}; and positive predictive value, 69{\%}. Using criterion 2, reader A identified three angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 17{\%}; specificity, 100{\%}; and positive predictive value, 100{\%}. Using criterion 3, reader A identified four angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 18{\%}; specificity, 100{\%}; and positive predictive value, 100{\%}. Conclusion: CT findings of more than 20 pixels with attenuation less than -20 HU and more than 5 pixels with attenuation less than -30 HU have a positive predictive value of 100{\%} in detection of angiomyolipoma, but most angiomyolipomas with minimal fat cannot be reliably identified on the basis of an absolute pixel count.",
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T2 - Can counts of negative-attenuation pixels aid diagnosis?

AU - Simpfendorfer, C.

AU - Herts, B. R.

AU - Motta-Ramirez, G. A.

AU - Lockwood, D. S.

AU - Zhou, M.

AU - Leiber, M.

AU - Remer, E. M.

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N2 - Objective: The purpose of this study was to determine whether counts of pixels with subzero attenuation on CT scans can aid in the diagnosis of renal angiomyolipoma with minimal fat. Materials and Methods: Of 33 angiomyolipomas identified among 719 renal masses resected from 702 patients over 4 years, 15 masses in 15 patients were prospectively diagnosed on the basis of the presence of fat at MDCT. The 18 patients with minimal-fat angiomyolipoma and a matched (age, sex, tumor size) cohort of patients with renal cell carcinoma were included in this study. Three radiologists independently counted the number of pixels with attenuation less than -10, -20, and -30 HU. Receiver operating characteristic analysis of the number of pixels at each cutoff was used to calculate sensitivity, specificity, and positive predictive value with the following criteria: 1, more than 10 pixels less than -20 HU; 2, more than 20 pixels less than -20 HU; 3, more than 5 pixels less than -30 HU. Results: Using criterion 1, reader A identified six angiomyolipomas; reader B, five; and reader C, two. The combined sensitivity was 24%; specificity, 98%; and positive predictive value, 69%. Using criterion 2, reader A identified three angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 17%; specificity, 100%; and positive predictive value, 100%. Using criterion 3, reader A identified four angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 18%; specificity, 100%; and positive predictive value, 100%. Conclusion: CT findings of more than 20 pixels with attenuation less than -20 HU and more than 5 pixels with attenuation less than -30 HU have a positive predictive value of 100% in detection of angiomyolipoma, but most angiomyolipomas with minimal fat cannot be reliably identified on the basis of an absolute pixel count.

AB - Objective: The purpose of this study was to determine whether counts of pixels with subzero attenuation on CT scans can aid in the diagnosis of renal angiomyolipoma with minimal fat. Materials and Methods: Of 33 angiomyolipomas identified among 719 renal masses resected from 702 patients over 4 years, 15 masses in 15 patients were prospectively diagnosed on the basis of the presence of fat at MDCT. The 18 patients with minimal-fat angiomyolipoma and a matched (age, sex, tumor size) cohort of patients with renal cell carcinoma were included in this study. Three radiologists independently counted the number of pixels with attenuation less than -10, -20, and -30 HU. Receiver operating characteristic analysis of the number of pixels at each cutoff was used to calculate sensitivity, specificity, and positive predictive value with the following criteria: 1, more than 10 pixels less than -20 HU; 2, more than 20 pixels less than -20 HU; 3, more than 5 pixels less than -30 HU. Results: Using criterion 1, reader A identified six angiomyolipomas; reader B, five; and reader C, two. The combined sensitivity was 24%; specificity, 98%; and positive predictive value, 69%. Using criterion 2, reader A identified three angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 17%; specificity, 100%; and positive predictive value, 100%. Using criterion 3, reader A identified four angiomyolipomas; reader B, four; and reader C, two. The combined sensitivity was 18%; specificity, 100%; and positive predictive value, 100%. Conclusion: CT findings of more than 20 pixels with attenuation less than -20 HU and more than 5 pixels with attenuation less than -30 HU have a positive predictive value of 100% in detection of angiomyolipoma, but most angiomyolipomas with minimal fat cannot be reliably identified on the basis of an absolute pixel count.

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