Electronic ISSN 2287-0237

VOLUME

HEPATIC CYST VERSUS HEMANGIOMA: USEFUL T2-FLAIR IMAGE FOR DIFFERENTIATION

FEBRUARY 2017 - VOL.13 | ORIGINAL ARTICLE

     The first two common benign hepatic nodules are hepatic cyst and hepatic hemangioma.1,2 By nature, hepatic cyst contains fluid with protein but hepatic hemangioma contains vascular structures with tortuous and variation in sizes. Most of these conditions are free of symptom, except for some occasions; hemangioma may occur rupture causing internal hemorrhage. Hence, the correct diagnosis at the initial non-invasive study is leading to properly follow up and for treatment planning before complication occurrence. 

     Nowadays, standard protocol of magnetic resonance imaging (MRI) liver composes of T2-weighted (T2W) and T2W images with long TE (echo time)3,4 routinely, which can differentiate the hepatic cyst and hemangioma. Hepatic cyst demonstrates bright signal as cerebrospinal fluid (CSF) on both T2W and T2W long TE images. There is rather signal drop of the hepatic hemangioma on the long TE images, but still be brighter signal than splenic signal (Figure 1A-1B).

     Sometimes, the small hepatic nodules of these two entities will be difficulty to differentiate based on the non-contrast study as mentioned. Therefore, multiphase contrasted MRI play an important role to make imaging diagnosis. The hepatic cyst shows no enhancement, on the other hand, hepatic hemangioma will be peripheral enhancement, progressive homogeneous enhancement and persistent enhancement on subsequent images (Figure 2A-2B). However, contrasted study of gadolinium may increase risk for contrast allergy and nephrogenic systemic fibrosis (NSF) in the patient of renal function impairment.

     We modified the T2-FLAIR image by using fast fluid attenuated inversion recovery (FLAIR) pulse sequences5,6 to null signal from the fluid, then the lesion as hepatic cyst will become dark signal (Figure 3A) but in contrast, the lesion of hepatic hemangioma becomes mildly to moderately bright signal (Figure 3B).

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The study was a retrospective study as follows:

1. All MRI liver studies at Bangkok Hospital Headquarters, Bangkok, Thailand, from 2014 to 2015, composed of multiphase contrasted images and T2-FLAIR images, were recruited. The hepatic nodules from the recruited studies were totally 106 nodules; if were multiple cysts in the same liver, we counted only one cyst, if were both hepatic cysts and hemangioma on the same liver, we counted only hemangioma, if were mixed entities as hepatic cyst, hemangioma with other liver tumor as hepatocellular carcinoma as on our population, we counted only cyst or hemangioma. These counted nodules showed on Table 1.

2. Two experienced radiologists independently read out the nodules as a hepatic cyst or hemagioma based on only T2-FLAIR images, regardless of multiphase contrasted MRI liver or the result of the previous report.

3. All cases were divided into 4 groups and analysis as shown on Table 2 analysis.

- Group a: The result of interpretation of the contrasted MRI study and T2-FLAIR image were agreed to be hemangioma.

- Group b: The result of interpretation of the contrasted MRI study read out as hepatic cyst but the T2-FLAIR image read out as hepatic hemangioma.

- Group c: The result of interpretation of the contrasted MRI study read out as hepatic hemangioma but T2-FLAIR read out as hepatic cyst

- Group d: The result of interpretation of the contrasted MRI study and T2-FLAIR were agreed to be hepatic cyst.

4. Calculated to evaluate the concordance from this formula.7

             pp

The included nodules from the study were 106 ones totally as followings; multiphase contrasted MRI reading out as hemangioma about 73 nodules, and reading out as cyst about 33 ones, T2-FLAIR images reading out as hemangioma about 74 nodules, and reading out as cyst about 32 ones. 

Table 1: The 106 counted hepatic nodules from the recruited study

Table106

     There was the one nodule being cyst appearance on multiphase contrasted MRI, but showing as hemangioma on T2-FLAIR images (Table 2).

     Therefore, the concordance of using multiphase contrasted MRI and T2-FLAIR images for differentiating both two types of nodules was 99.05 percent (Table 3). 

     From a total of 106 nodules, the reading out by both pulse sequences as agreed as 73 nodules for hepatic hemangioma and corresponded to hepatic cyst for 32 nodules. Only one nodule is an abnormal finding, reading out by multiphase contrasted MRI revealed dark signal nodule (Figure 4A) which is likely to be a hepatic cyst but on the T2-FLAIR images demonstrated a rather bright signal nodule, which should be hemangioma (Figure 4B). When this case had been examined by ultrasonic scan, there was a cyst with echoic content, probably due to hemorrhagic cyst.

     Motoomi et al.,8 have also found the one nodule showing as a cyst on post contrast images, but being a hyperintense FLAIR signal. The nodule represented a hemorrhagic cyst similarly to our study. Katsumi et al.,9 and Motoomi et al.,8found the usefulness of FLAIR imaging in hepatic cyst and hepatic hemangioma, furthermore in this present study, the result agreed to the mentioned concept.

     The use of T2-FLAIR images to differentiate both entities, between hepatic cyst and hepatic hemangioma, instead of contrasted MRI study alone, is very useful, as the accuracy rate is 99.05%. We recommend this pulse sequence to differentiate hepatic cyst and hemangioma without contrast, or even adding the T2-FLAIR images to routine MRI liver protocol. 

Table2: Number of reading out nodules on multiphase contrasted MRI and T2-FLAIR image

r

 

Table3: Analysis of the results : n = (a+b+c+d)

3

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Figure 4A-4B: 4A show axial post contrast images (THRIVE sequence, 3T, TR 3.2 ms, TE 1.5 ms) showed a non-enhancing lesion in segment VII, being mild hyperintense FLAIR (3T,TR 11000,TE 107 ms) signal on 4B, could be a hemorrhagic cyst, and this was confirmed by sonography in Figure 5. 

 

f5

Figure 5: The sonography of the liver showed a subcapsular cyst with echoic content in right hepatic lobe, and represented hemorrhagic cyst.

     The advantages are less cost, time of examination, noother modalities for further examination, no risk to contrast allergy and to patients with renal function impairment. However, the disadvantage of the T2-FLAIR images is seen in the case of an hepatic cyst containing blood or turbid protein, or intrahepatic biloma. In case of a doubtful differentiation, doing further sonography will be helpful, or a 6-month follow up is recommended to observe internal content change.

     A T2-FLAIR image on an MRI study is very useful to differentiate between hepatic cysts and hemangioma; the accuracy is 99.05%, instead of multiphase contrasted MRI study. It will save costs and total scan time of the study, it will avoid the risk of contrast allergy and risks to patients with renal function impairment.