| Background and PurposeHemangiomas and vascular malformations are common benign vascular lesions of soft-tissue. The latter is divided into fast-flow (arterial malformation, arteriovenous fistula, arteriovenous malformation) and slow-flow (capillary malformation, venous malformation, lymphatic malformation).Their biological characteristics, treatment and prognosis are markedly different.MRI is one of the commonly used methods to diagnosis hemangiomas and vascular malformations. But there are many similarities among different types lesions, differential diagnosis still has certain difficulty. Arterial spin labeling(ASL) is a noninvasive magnetic resonance technique to evaluate tissue blood perfusion information, diffusion-weighted imaging (DWI) is the only noninvasive technology to detect water molecules dispersion information in vivo.The paper is to explore the findings of blood perfusion on ASL and diffusion on DWI of both hemangiomas and vascular malformations, thereby offer valuable information on diagnosis and differential diagnosis。Materials and Methods1.Between June 2009 and November 2010,39 patients with hemangiomas or vascular malformations were proven by surgical in Henan Provincial People's Hospital. Among them,11 cases were male and 28 cases were female. Aging from 1 to 46 years old, mean age was 18 years.12 cases were upper extremities,25 cases were lower extremities and 2 cases involved upper and lower extremities.2.All the cases were perfomed conventional MR imaging, ASL and DWI by American GE HDxt 1.5T MR scanner with 8 channel body coil.T1WI(TR/TE 380.0ms/14.9ms),T2WI(TR/TE 3020ms/85.0m)used FSE sequence, NEX 2,Matrx 320×224.Number of slices 6,Section thickness 5mm,Intersection 1.5mm.T2WI with fat saturation.EPI-FAIR(echo planar imaging flow sensitive alternating inversion recovery) sequence, TR 800ms,TE 81.8ms,TI 1200ms,Flip angle 90°,NEX 1,Matrx 128×128, Number of slices 6,Section thickness 5mm,Intersection 1.5mm.The FOV was adjusted with the size of lesion.EPI-DWI(echo planar diffusion-weighted imaging)sequence, TR 4200ms,TE 70.9ms,NEX 1,Matrx 128x128.Number of slices 6,Section thickness 5mm, Intersection 1.5mm.The FOV was adjusted with the size of lesion. The b value of diffusion coefficient was 500s-mm-2.3.Image processing and data acquisition were on GE AW4.4 workstation.ASL The blood flow (BF) was calculated in area of lesions and mirror area in three groups, respectively. Then the rBFs(rBF=BFiesion/BFnormal) were compared.DWI On apparent diffusion coefficient (ADC) imaging, the region of interest(ROI) was drawn in the maximum level of lesions.The ADC mean was taken.4.All specimens were fixed in 10% neutral formalin and embedded in paraffin. Conventional pathologic examination was performed.5.Statistics SPSS 13.0 software package was applied for statistical analysis. Group comparison of data was treated by one-factor analysis of variance, interclass comparison each other by LSD method. When variance was unequal, non-parameter rank close inspection was used. P<0.05 means the difference significant.Results 1.The conventional MRI findings of hemangiomas and vascular malformations8 cases of hemangiomas showed nodule or mass in the soft tissue of extremities. Among them the boundaries of 6 cases were unclear and 2 were clear. On T1WI,6 cases were heterogeneous isointensity,1 case was homogenous isointensity and 1 case was hyper-isointensity. On T2WI,7 cases were heterogeneous hyperintensity and 1 case was homogenous hyperintensity.23 cases of slow-flow vascular malformations showed mass with irregular shape and unclear boundary in the soft tissue of extremities. On T1WI,12 cases were hyper-isointensity,9 cases were heterogeneous isointensity and 2 cases were homogenous isointensity. On T2WI,21 cases were heterogeneous hyperintensity and 2 cases were homogenous hyperintensity.8 cases of fast-flow vascular malformations showed mass with irregular shape and unclear boundary in the soft tissue of extremities, too. On T1WI,5 cases were hyper-isointensity and 3 cases were heterogeneous isointensity. On T2WI,all the 8 cases were heterogeneous hyperintensity2.The ASL findings of hemangiomas and vascular malformationsBoth hemangiomas and vascular malformations showed hyper-iso-hypoperfusion mixed on ASL-BF imagings.7 cases of hemangiomas showed obviously higher perfusion than the normal and 1 case showed slightly higher perfusion than the normal.20 cases of slow-flow vascular malformations showed lower perfusion than the normal and 3 case showed identical perfusion with the normal. All the 8 cases of fast-flow vascular malformations showed obviously higher perfusion than the normal.The mean rBF of hemangiomas, slow-flow vascular malformations and fast-flow vascular malformations was 1.2237±0.1232,0.9616±0.1112 and 2.7481±1.1966, respectively. There were significant differences among the three groups(χ2=29.569.P <0.05).The rBF of hemangiomas was slightly higher than that of slow-flow vascular malformations(Z=-4.153,P=0.000), and lower than that of fast-flow vascular malformations(Z=-3.361,P=0.001). The rBF of slow-flow vascular malformations was apparently lower than that of fast-flow vascular malformations(Z=-4.153,P=0.000). The differences were significant between any two in the three groups(P<0.05).3.The DWI findings of hemangiomas and vascular malformationsHemangiomas, slow-flow vascular malformations and fast-flow vascular malformations were hyperintensity on DWI. They showed limited diffusion on ADC maps. Among the 8 cases of hemangiomas,6 cases were obviously heterogeneous hyperintensity,1 case was obviously homogenous hyperintensity and 1 case was slightly heterogeneous hyperintensity.23 cases of slow-flow vascular malformations were heterogeneous hyperintensity, among them 19 cases were obviously hyperintensity and 4 cases were slightly hyperintensity.8 cases of fast-flow vascular malformations were heterogeneous hyperintensity, among them 3 cases were obviously hyperintensity and 5 cases were slightly hyperintensity.The order of ADC mean values from lower to higher was hemangiomas, slow-flow vascular malformations, fast-flow vascular malformations. The data were (1.1734±0.3208)×10-3mm2·s-1, (1.7766±0.4033)×10-3mm2·s-1 and (2.3251±0.5145)×10-3mm2·s-1.There were significant differences among the three groups(F=15.547, P<0.05). The ADC value of hemangiomas was lower than that of slow-flow vascular malformation(P=0.001), and also lower than that of fast-flow vascular malformation(P=0.000). The ADC value of slow-flow vascular malformation was lower than that of fast-flow vascular malformation(P=0.003). The differences were significant between any two in the three groups(P<0.05).4.The pathology findings of hemangiomas and vascular malformationsAccording to the classification standard issued by the international association for the study of vascular anomalies in 1996,there were 8 patients with hemangiomas,23 with slow-flow vascular malformations, and 8 with fast-flow vascular malformations. Conclusions1.MRI can show the range of hemangiomas and vascular malformations clearly and reflect their component of organization to some extent. It is useful for diagnosis and treatment.2.ASL can provide information about the blood flow of soft-tissue hemangiomas and vascular malformations and is valuable for their diagnosis and differential diagnosis.3.DWI can reflect diffusion difference between soft-tissue hemangiomas and vascular malformations, therefore it is helpful in the differential diagnosis.4.Combined with MRI,ASL and DWI could enhance the diagnosis accuracy of soft-tissue hemangiomas and vascular malformations, and also offer information for choice of treatments. |
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