Korean J Radiol.  2011 Jun;12(3):341-350. 10.3348/kjr.2011.12.3.341.

Diagnosing Small Hepatic Cysts on Multidetector CT: an Additional Merit of Thinner Coronal Reformations

• Hwang SH
• Yu JS
• Chung JJ
• Kim JH
• Kim KW

• KMID: 1122331
• DOI: http://doi.org/10.3348/kjr.2011.12.3.341

Abstract

OBJECTIVE
We wanted to validate the additional merit of the thinner coronal reformation images from multidetector CT (MDCT) for making the diagnosis of hepatic cysts.
MATERIALS AND METHODS
For the 90 benign hepatic cysts confirmed on MRI, the transverse (5-mm thickness) and additional coronal (2-mm thickness) reformation images from MDCT were compared with each other in terms of the Hounsfield units (HUs) and the size of each hepatic cyst.
RESULTS
The attenuations (mean: 17.2 HUs, standard deviation: +/- 14.4) on the thinner coronal images were significantly lower than those (mean: 40.7 HUs; standard deviation: +/- 20.6) on the thicker transverse images for the small hepatic cysts (< or = 10 mm on the transverse image, p < 0.01). Twenty-three (79%) of the 29 cysts between 5 mm and 10 mm and 21 (51%) of 41 lesions up to 5 mm showed a mean HU value of 20 or less on the coronal reformation images.
CONCLUSION
By reducing the partial volume effect, routine coronal reformation of MDCT with a thinner section thickness can provide another merit for making a confidential diagnosis of many small sub-centimeter hepatic cysts, and these small cysts are not easily characterized on the conventional transverse images.

Keyword

Multidetector CT (MDCT); Hepatic cyst; Hounsfield units (HUs); Sectional thickness; Partial volume effect

MeSH Terms

Adult
Analysis of Variance
Contrast Media/diagnostic use
Cysts/*radiography
Female
Gadolinium DTPA/diagnostic use
Humans
Iohexol/analogs & derivatives/diagnostic use
Liver Diseases/*radiography
Magnetic Resonance Imaging/methods
Male
Middle Aged
Radiographic Image Interpretation, Computer-Assisted/*methods
Tomography, X-Ray Computed/*methods

Figure

• 

  Fig. 1 Interactive dot diagram that plots attenuation values on y axis according to sizes of hepatic cysts on x axis shows significant attenuation difference between transverse and coronal images for small hepatic cysts less than 10 mm in size (p < 0.01).

• 

  Fig. 2 50-year-old man with group I (≤ 5 mm) hepatic cyst in cirrhotic liver. A. Transverse image with 5-mm section thickness from portal venous phase contrast-enhanced CT section of abdomen reveals 4-mm hypoattenuating lesion (66 HUs), as compared with liver parenchyma, in right lobe of liver (arrow). B. Coronal image with 2-mm section thickness demonstrates that right hepatic lesion corresponding to that shown in A has 4-mm height and 30 HUs (arrow). C, D. Hepatic lesion (arrow) corresponding to that shown in A and B reveals typical appearance of hepatic cyst with markedly hyperintensity on transverse T2-weighted image (C) and no internal enhancement on transverse contrast-enhanced T1-weighted MR image (D).

• 

  Fig. 3 41-year-old man with group II (> 5 mm and ≤ 10 mm) hepatic cyst in right lobe. A. Transverse image with 5-mm section thickness from portal venous phase contrast-enhanced CT section of abdomen reveals 7-mm hypoattenuating lesion (43 HUs), as compared with liver parenchyma, in right lobe of liver (arrow). B. Coronal image with 2-mm section thickness demonstrates that right hepatic lesion corresponding to that shown in A has 4-mm height and 9 HUs (arrow). C, D. Hepatic lesion (arrows) corresponding that shown in A and B reveals typical appearance of hepatic cyst with markedly hyperintensity on transverse T2-weighted image (C) and no internal enhancement on transverse contrast-enhanced T1-weighted MR image (D).

• 

  Fig. 4 60-year-old man with group III (> 10 mm) large hepatic cyst in cirrhotic liver. A. Transverse image with 5-mm section thickness from portal venous phase contrast-enhanced CT section of abdomen reveals 21-mm hypoattenuating lesion (10 HUs), as compared with liver parenchyma, in right lobe of liver (arrow). B. Coronal image with 2-mm section thickness demonstrates that right hepatic lesion corresponding to that shown in A has 16-mm height and 10 HUs (arrow).

• 

  Fig. 5 Interactive dot diagram that plots attenuation differences between transverse and coronal images on y axis according to heights of hepatic cysts on x axis reveals that attenuation differences were greater for shorter lesions in group I (p = 0.02) and group II (p = 0.03).

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