Korean J Radiol.  2005 Mar;6(1):17-21. 10.3348/kjr.2005.6.1.17.

Detectability of Various Sizes of Honeycombing Cysts in an Inflated and Fixed Lung Specimen: the Effect of CT Section Thickness

• Nishimoto
• Takahashi
• Murata K
• Kichikawa

• KMID: 1783168
• DOI: http://doi.org/10.3348/kjr.2005.6.1.17

Abstract

OBJECTIVE
We wanted to clarify the relationship between the visibility of air cysts on CT images, the CT slice thickness and the size of the air cysts, with contact radiographs as the gold standard, for the accurate evaluation of honeycomb cysts. MATERIALS AND METHODS: An inflated and fixed autopsied lung having idiopathic interstitial pneumonia was evaluated. The corresponding air cysts were identified on the contact radiographs of a 0.5 mm-thick-section specimen and also on the CT images of three different kinds of section thickness: 0.5, 1.0 and 2.5 mm. The maximal diameters of the air cysts were measured under a stereomicroscope. RESULTS: A total of 341 air cysts were identified on the contact radiograph, and they were then evaluated. Sixty-six percent of air cysts 1 to 2 mm in diameter were detected by 0.5 mm slice thickness CT, while only 34% and 8% were detected by 1.0 and 2.5 mm slice thickness CT, respectively. Only 28% and 22% of air cysts less than 1 mm in diameter were detected by 0.5 and 1.0 mm slice thickness CT, respectively. CT with a 2.5 mm slice thickness could not demonstrate air cysts less than 1 mm in diameter. CONCLUSION: The CT detection rate of honeycombing is significantly influenced both by the slice thickness and the size of the air cysts.

Keyword

Lung, CT; Lung, diseases; Lung, fibrosis; Lung, interstitial disease

MeSH Terms

Aged
Aged, 80 and over
Cadaver
Cysts/*radiography
Female
Humans
Lung Diseases/pathology/*radiography
Tissue Fixation/methods
*Tomography, X-Ray Computed

Figure

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  Fig. 1 A. Idiopathic pulmonary fibrosis in an 85-year-old woman. Contact radiograph of the specimen (0.5 mm thick slice). Air cysts from 1.0 to 4.0 mm in diameter were concentrated in the area of the right upper quadrant. Air cysts from 6.2 to 12.6 mm in diameter existed in the area of right lower quadrant. B. On 0.5-mm-slice-thickness CT image cysts are clearly visudized. C. On 1-mm-slice-thickness CT image, every air cyst was clearly described. The walls of the air cysts were more definite on the 0.5 mm slice thickness CT images than with 1 mm slice thickness CT images. D. On 2.5-mm-slice-thickness CT image, the margins of the small air cysts became unclear and some were recognized as reticular shadow superimposed ground grass opacity. The large air cysts were the same as on the contact radiograph.

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  Fig. 2 The bar graph demonstrates the frequency distribution of the maximal diameter of air cysts detected on the contact radiographs.

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  Fig. 3 The bar graph demonstrates the relationship among the ratio of detected air cysts on CT images, the size of the cysts and slice thickness.

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