Histogram analysis for characterization of indeterminate adrenal nodules on noncontrast CT

Michael F. Lin, Lauren Q. Chang-Sen, Jay Heiken, Thomas K. Pilgram, Kyongtae T. Bae

Research output: Contribution to journalReview article

6 Citations (Scopus)

Abstract

Objective: To determine the effectiveness of the CT histogram method to characterize indeterminate adrenal nodules above 10 Hounsfield units (HU) on noncontrast CT. Materials and methods: Retrospective review of clinical CT data from January 2005 through 2008 identified 194 indeterminate adrenal nodules (>10 HU on noncontrast CT) in 175 patients. 20 nodules in 18 patients were excluded due to large standard deviation (SD > 30) of HU values. Of the remaining 174 nodules, 131 were classified as benign lipid-poor nodules based on size stability for ≥1 year (104), in- and opposed-phase MRI (17), adrenal washout CT (3), or biopsy (7). 43 were classified as malignant by size increase over a short time (30), avid FDG uptake on PET/CT (15), or biopsy (5). Histogram analysis was performed by drawing a circular region of interest on all adrenal nodules. Mean attenuation, total number of pixels, number of negative pixels, and percentage of negative pixels were recorded for each nodule. Results: At the threshold value of >10% negative pixels, 59/131 benign nodules were correctly characterized, but 1/43 malignant nodules was falsely characterized as benign (sensitivity 45%, specificity 98%, positive predictive value 98%). With a slightly higher threshold value of >15% negative pixels, there were no false benign judgments. 36 nodules had more than 15% negative pixels, all of which were benign (sensitivity 27%, specificity 100%, positive predictive value 100%). In the subgroup of benign nodules measuring 11–20 HU, 80% and 54% were identified with threshold values of >10% and >15% negative pixels, respectively. Conclusion: The CT histogram method with a threshold value of >10% negative pixels can identify many benign adrenal nodules with attenuation values >10 HU on unenhanced CT with extremely high specificity. A threshold of >15% negative pixels can achieve 100% specificity. This method is highly robust provided very “noisy” CT examinations (SD > 30) are eliminated.

Original languageEnglish (US)
Pages (from-to)1666-1674
Number of pages9
JournalAbdominal Imaging
Volume40
Issue number6
DOIs
StatePublished - Aug 12 2015
Externally publishedYes

Fingerprint

Biopsy
Sensitivity and Specificity
Lipids

Keywords

  • Adrenal nodules
  • CT
  • CT noise
  • Histogram analysis
  • Negative pixels

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Medicine(all)
  • Radiology Nuclear Medicine and imaging
  • Urology
  • Gastroenterology

Cite this

Histogram analysis for characterization of indeterminate adrenal nodules on noncontrast CT. / Lin, Michael F.; Chang-Sen, Lauren Q.; Heiken, Jay; Pilgram, Thomas K.; Bae, Kyongtae T.

In: Abdominal Imaging, Vol. 40, No. 6, 12.08.2015, p. 1666-1674.

Research output: Contribution to journalReview article

Lin, Michael F. ; Chang-Sen, Lauren Q. ; Heiken, Jay ; Pilgram, Thomas K. ; Bae, Kyongtae T. / Histogram analysis for characterization of indeterminate adrenal nodules on noncontrast CT. In: Abdominal Imaging. 2015 ; Vol. 40, No. 6. pp. 1666-1674.
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abstract = "Objective: To determine the effectiveness of the CT histogram method to characterize indeterminate adrenal nodules above 10 Hounsfield units (HU) on noncontrast CT. Materials and methods: Retrospective review of clinical CT data from January 2005 through 2008 identified 194 indeterminate adrenal nodules (>10 HU on noncontrast CT) in 175 patients. 20 nodules in 18 patients were excluded due to large standard deviation (SD > 30) of HU values. Of the remaining 174 nodules, 131 were classified as benign lipid-poor nodules based on size stability for ≥1 year (104), in- and opposed-phase MRI (17), adrenal washout CT (3), or biopsy (7). 43 were classified as malignant by size increase over a short time (30), avid FDG uptake on PET/CT (15), or biopsy (5). Histogram analysis was performed by drawing a circular region of interest on all adrenal nodules. Mean attenuation, total number of pixels, number of negative pixels, and percentage of negative pixels were recorded for each nodule. Results: At the threshold value of >10{\%} negative pixels, 59/131 benign nodules were correctly characterized, but 1/43 malignant nodules was falsely characterized as benign (sensitivity 45{\%}, specificity 98{\%}, positive predictive value 98{\%}). With a slightly higher threshold value of >15{\%} negative pixels, there were no false benign judgments. 36 nodules had more than 15{\%} negative pixels, all of which were benign (sensitivity 27{\%}, specificity 100{\%}, positive predictive value 100{\%}). In the subgroup of benign nodules measuring 11–20 HU, 80{\%} and 54{\%} were identified with threshold values of >10{\%} and >15{\%} negative pixels, respectively. Conclusion: The CT histogram method with a threshold value of >10{\%} negative pixels can identify many benign adrenal nodules with attenuation values >10 HU on unenhanced CT with extremely high specificity. A threshold of >15{\%} negative pixels can achieve 100{\%} specificity. This method is highly robust provided very “noisy” CT examinations (SD > 30) are eliminated.",
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AU - Lin, Michael F.

AU - Chang-Sen, Lauren Q.

AU - Heiken, Jay

AU - Pilgram, Thomas K.

AU - Bae, Kyongtae T.

PY - 2015/8/12

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N2 - Objective: To determine the effectiveness of the CT histogram method to characterize indeterminate adrenal nodules above 10 Hounsfield units (HU) on noncontrast CT. Materials and methods: Retrospective review of clinical CT data from January 2005 through 2008 identified 194 indeterminate adrenal nodules (>10 HU on noncontrast CT) in 175 patients. 20 nodules in 18 patients were excluded due to large standard deviation (SD > 30) of HU values. Of the remaining 174 nodules, 131 were classified as benign lipid-poor nodules based on size stability for ≥1 year (104), in- and opposed-phase MRI (17), adrenal washout CT (3), or biopsy (7). 43 were classified as malignant by size increase over a short time (30), avid FDG uptake on PET/CT (15), or biopsy (5). Histogram analysis was performed by drawing a circular region of interest on all adrenal nodules. Mean attenuation, total number of pixels, number of negative pixels, and percentage of negative pixels were recorded for each nodule. Results: At the threshold value of >10% negative pixels, 59/131 benign nodules were correctly characterized, but 1/43 malignant nodules was falsely characterized as benign (sensitivity 45%, specificity 98%, positive predictive value 98%). With a slightly higher threshold value of >15% negative pixels, there were no false benign judgments. 36 nodules had more than 15% negative pixels, all of which were benign (sensitivity 27%, specificity 100%, positive predictive value 100%). In the subgroup of benign nodules measuring 11–20 HU, 80% and 54% were identified with threshold values of >10% and >15% negative pixels, respectively. Conclusion: The CT histogram method with a threshold value of >10% negative pixels can identify many benign adrenal nodules with attenuation values >10 HU on unenhanced CT with extremely high specificity. A threshold of >15% negative pixels can achieve 100% specificity. This method is highly robust provided very “noisy” CT examinations (SD > 30) are eliminated.

AB - Objective: To determine the effectiveness of the CT histogram method to characterize indeterminate adrenal nodules above 10 Hounsfield units (HU) on noncontrast CT. Materials and methods: Retrospective review of clinical CT data from January 2005 through 2008 identified 194 indeterminate adrenal nodules (>10 HU on noncontrast CT) in 175 patients. 20 nodules in 18 patients were excluded due to large standard deviation (SD > 30) of HU values. Of the remaining 174 nodules, 131 were classified as benign lipid-poor nodules based on size stability for ≥1 year (104), in- and opposed-phase MRI (17), adrenal washout CT (3), or biopsy (7). 43 were classified as malignant by size increase over a short time (30), avid FDG uptake on PET/CT (15), or biopsy (5). Histogram analysis was performed by drawing a circular region of interest on all adrenal nodules. Mean attenuation, total number of pixels, number of negative pixels, and percentage of negative pixels were recorded for each nodule. Results: At the threshold value of >10% negative pixels, 59/131 benign nodules were correctly characterized, but 1/43 malignant nodules was falsely characterized as benign (sensitivity 45%, specificity 98%, positive predictive value 98%). With a slightly higher threshold value of >15% negative pixels, there were no false benign judgments. 36 nodules had more than 15% negative pixels, all of which were benign (sensitivity 27%, specificity 100%, positive predictive value 100%). In the subgroup of benign nodules measuring 11–20 HU, 80% and 54% were identified with threshold values of >10% and >15% negative pixels, respectively. Conclusion: The CT histogram method with a threshold value of >10% negative pixels can identify many benign adrenal nodules with attenuation values >10 HU on unenhanced CT with extremely high specificity. A threshold of >15% negative pixels can achieve 100% specificity. This method is highly robust provided very “noisy” CT examinations (SD > 30) are eliminated.

KW - Adrenal nodules

KW - CT

KW - CT noise

KW - Histogram analysis

KW - Negative pixels

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