局灶结节性肝脏脂肪浸润

Nodularfocalfattyinfiltration局灶结节性肝脏脂肪浸润

来自：双语学影像；病例选自《MayoClinicBodyMRICaseReview》

History

69-year-oldwomanwithirritablebowelsyndromeandnewlowbackpain;CTshowedmultiplehepaticlesionssuspiciousformetastases

69岁女性，肠易激综合征病史，近期出现下腰痛。CT示肝脏多发占位，可疑转移瘤。

Fig2.5.1T1WIIP/OP2D-SPGR

Fig2.5.2FS-T2WI

Fig2.5.2CE-axialarterialandportalvenousphase

ImagingFindings

AxialT1-weightedIPandOP2DSPGRimages(Figure2.5.1)demonstratemultipleroundedmasses,withperipheralhalosofsignaldropoutseenononlytheOPimages.Axialfat-suppressed,T2-weightedimages(Figure2.5.2)demonstratenocorrespondingabnormalities,andarterialandportalvenousphasepostgadolinium3DSPGRimages(Figure2.5.3)arealsounremarkable.

T1WI横断位同反相位图像示：肝内多发类圆形肿块，仅OP相位图可见，病灶周边见晕状信号衰减。

横断位脂肪抑制T2WI序列，对应位置未见明显异常信号。

3DSPGR增强扫描动脉期、门静脉期未见明显异常。

Diagnosis

Nodularfocalfattyinfiltration

局灶结节性肝脏脂肪浸润

Comment

Thiscaseisanotherexampleofanunusualformoffattyinfiltrationthatisalsonodular,butwithfattysparingatthecenterofthelesionandaperipheralhalooffat.

这是一例少见类型的肝脏脂肪浸润，同样表现为结节状，但病灶中心无明显脂肪浸润，周边可见晕状脂肪。

Figure2.5.4CTscan：

Figure2.5.5US-guidedbiopsy

Oneofthemorechallengingaspectsoftheradiologist’sjobismakinganunexpecteddiagnosis(particularlyonethatcontradictsacolleague).TheCTscanwasreadasconsistentwithhepaticmetastases(Figure2.5.4)andaUS-guidedbiopsy(Figure2.5.5)wasnegativeformalignancy.Atthetime,thisradiologic-pathologicdiscordancewasattributedtosamplingerror;however,insteadofrepeatingthebiopsy,anMRIwasperformedtobettercharacterizethelesions.

放射科医生工作中具有挑战性的情况之一就是做出一个令人意想不到的诊断结果（尤其是当你和同事的诊断不一致时）。CT扫描几乎所有人都诊断为转移瘤，但超声引导下穿刺结果未见恶性病变。此时，放射科和病理科的意见不一致被认为抽样误差所致，但磁共振代替了二次穿刺活检，对这种诊断不一致给出了解释。

Fattyinfiltrationisoccasionallyperivascularinnature,andmayappearashalosortracks(dependingontheimagingplane)offatsurroundingthehepaticveinsorportalveins,orboth.AsnotedinCase2.4,aconfidentdiagnosisofnodularfocalfattyinfiltrationrestsontheabsenceofcorrespondingabnormalitiesonT2-anddiffusion-weightedimagesinconjunctionwithunremarkabledynamicpostgadoliniumimages.Thereare,ofcourse,fat-containingtumors,suchashepaticadenomasandHCCs,thatdemonstrateimagingfeaturessuggestiveofamass.Perilesionalfattyinfiltration(ie,ahalooffat)hasbeendescribedinafewcasereportsasoccurringinpatientswithmetastaticinsulinoma.Thispatternispresumablyrelatedtolocaleffectsofinsulin,butneuroendocrinemetastasestypicallyshowhighsignalintensityonT2-anddiffusion-weightedimages.

肝脏脂肪浸润偶尔可沿血管周围发生，根据扫描方向不同，表现为肝静脉或门静脉周围“晕状”或“轨道状”脂肪信号。上期病例中，局灶结节性肝脏脂肪浸润的诊断信心依赖于T2WI、DWI及增强扫描未见明显对应的病灶显示。当然，含脂质的肿瘤，如腺瘤、HCC，其影像学特点更加倾向肿块。少数文献中报道，病灶周围脂肪浸润可发生于转移性胰岛细胞瘤，可能与胰岛素的局部效应有关，但神经内分泌肿瘤的转移瘤一般表现为T2WI和DWI高信号。

Inthiscase,theMRIreportlistednodularfocalfattyinfiltrationasthetopdifferentialdiagnosisbutsaidthatneoplasmcouldnotbeexcluded.Thisledtoasecondbiopsy,whichagaindemonstratedbenignhepaticparenchymawithfattychange.Twoyearsafterthisexamination,afollow-upCTdemonstratedradiographicresolutionofthemultiplelivermassesaftermildweightloss.

本例患者，MR诊断提示首先考虑局灶结节性脂肪浸润，但肿瘤不能完全排除。所以，患者再次进行了穿刺活检，结果依然显示为良性的肝实质脂肪变。两年后，患者体重略减低，复查CT显示原肝脏内多发病灶消失。

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