乳腺叶状肿瘤MRI表现特征分析

目的分析乳腺叶状肿瘤(phyllodes tumors,PTs)MRI平扫、动态增强、扩散加权成像(DWI)和磁共振波谱(MRS)表现特征,提高对本病MRI诊断水平。资料与方法搜集2005年1月至2008年12月期间于我院行乳腺MRI检查并经手术病理证实的5例乳腺PTs,按照美国放射学会提出的乳腺影像报告和数据系统磁共振成像(BI-RADS-MRI)标准,回顾性分析病变的MRI表现,包括形态学、平扫T1WI及T2WI信号、动态增强表现及强化曲线类型、DWI信号及表观扩散系数(ADC)值和MRS表现特征。结果5例乳腺PTs病理诊断良性1例,交界性2例,恶性2例。MRI上4例表现为分叶状,1例为卵圆形;5例PTsMRI平扫T1WI均呈较低信号,T2WI呈高信号,其中1例内有低信号分隔;4例行动态增强检查的PTs于动态增强早中期(增强后第一至第三时相)呈快速渐进性强化,动态增强中后期时间-信号强度曲线3例呈平台型,1例呈轻度流出型;5例PTs于DWI上均呈高信号,ADC值低于正常乳腺组织,且低于鉴别乳腺良恶性病变的ADC界值;3例行MRS检查,均可见胆碱(Cho)峰。结论MRI检查有助于乳腺PTs的诊断,但确诊仍需...     

乳腺少见恶性肿瘤的MRI诊断

目的:探讨乳腺少见恶性肿瘤的MRI表现及特征。方法:回顾性分析11例经手术病理证实为乳腺少见恶性肿瘤的MRI特征。观察病灶信号、形态、最大径线、边缘、ADC值、增强扫描实性成分TIC类型,以及腋下有无肿大淋巴结。结果:4例乳腺恶性叶状肿瘤,呈分叶状,伴不同程度出血、坏死及囊变,2例可见裂隙征,DWI为高信号,ADC值(0.6~1.1)×10-3mm2/s,TIC为Ⅱ、Ⅲ型。4例乳腺黏液腺癌,其中单纯型2例,以囊性为主,实性成分较少,T1WI呈稍高信号,压脂T2WI呈高信号,DWI为高信号,中心ADC值分别为2.2×10-3mm2/s、2.4×10-3mm2/s,边缘结节样实性成分ADC值为1.2×10-3 mm2/s,边缘实性部分TIC为Ⅱ型;2例混合型,以实性为主,部分区域呈囊样改变,T1WI呈等、稍高信号,T2WI呈等高信号,ADC值囊性区较高为2.0×10-3 mm2/s,实性区较低为0.8×10-3mm2/s,TIC为Ⅱ型或Ⅲ型。2例乳腺髓样癌,信号较均匀,边界清晰,DWI为高信号,ADC值0.8×10-3 mm2/s,动态增强扫描早期外围强化更明显,呈环形强化,逐渐向中心强化,TIC为Ⅱ型。1例淋巴瘤,形态不规则,无分叶,与周围组织分界不清,少量坏死,DWI为高信号,ADC值为0.9×10-3mm2/s,强化明显且均匀,TIC为Ⅲ型。结论:乳腺少见恶性肿瘤的MRI表现具有一定特征性,通过对病灶形态、信号、DWI、ADC值及TIC综合分析,能提高其诊断准确率。     

MRI鉴别诊断结节肿块型乳腺导管内乳头状瘤与浸润性导管癌的价值

目的探讨结节肿块型乳腺导管内乳头状瘤(IDP)与浸润性导管癌(IDC)的MRI表现和特征,提高MRI对IDP的诊断准确率。方法选取并分析我院经手术病理证实为IDC的患者31例和术前MRI误诊为乳腺癌经手术病理证实为IDP的患者18例,采用χ^(2)及秩和检验比较两组患者MRI形态学参数,包括病灶边缘、强化方式、T2WI信号、TIC类型,采用t检验比较两组患者MRI功能学参数,包括ADC值、峰值信号强度、EER(%)、ERmax(%)、TIC斜率、峰值时间。结果两组患者MRI形态学参数中,病灶边缘、TIC类型差异有统计学意义(P<0.05),形状、强化方式、T_(2)WI信号差异无统计学意义(P>0.05)。两组患者MRI功能学参数中,ADC值、峰值信号强度、EER(%)、ERmax(%)、TIC斜率、峰值时间差异均有统计学意义(P<0.05)。结论不规则肿块型IDP与IDC的MRI表现有重叠,病灶的边缘、TIC类型、ADC值、峰值信号强度以及TIC曲线达峰时间、斜率、早期强化率、峰值强化率对二者的鉴别具有重要意义。     

MRI在乳腺叶状肿瘤与纤维腺瘤鉴别诊断中的价值

目的 分析乳腺叶状肿瘤(PTs)的MRI特征,提高PTs与纤维腺瘤(FAs)的鉴别诊断水平.方法 搜集经手术病理证实、行MRI检查的PTs患者10例及FAs患者33例,分析其MRI表现,并进行统计学分析,比较两者的差异.结果 10例PTs中,术后病理诊断良性2例,交界性8例.叶状肿瘤具有短期内明显增大病史,在最大横径、深分叶、T1WI上存在高信号区域、T2囊性成分、低信号的分隔、不均匀强化、增多的血管、时间-信号强度曲线上,与FAs有统计学差异(P =0.026).在T2WI信号、胆碱(Cho)峰值上,两者没有统计学差异.结论 PTs和FAs在MRI表现上有一定差异,有助于PTs的正确诊断.     

乳腺腺病瘤MRI表现特征分析

目的分析乳腺腺病瘤MRI平扫、动态增强(DCE)和扩散加权成像(DWI)表现特征,提高对腺病瘤的认识和术前诊断准确率。方法搜集2008年10月至2013年11月期间行乳腺MRI检查并经手术病理证实的8例患者9个乳腺腺病瘤,依据美国放射学会提出的乳腺影像报告和数据系统磁共振成像(BI-RADS-MRI)标准,回顾性分析病变MRI表现,包括形态学、平扫T1WI及T2WI信号、DCE表现及时间-信号强度曲线(TIC)类型、DWI信号及ADC值。结果 9个腺病瘤中8个表现为肿块,1个表现为非肿块。8个肿块型腺病瘤中,6个呈圆形或卵圆形,所有病变均边界清楚,6个边缘不规则;于平扫T1WI均呈等信号,脂肪抑制T2WI呈等或稍高信号;DCE-MRI扫描均于早期时相明显强化,早期强化率平均值为(173.2±52.8)%,4个腺病瘤内部呈不均匀强化;7个TIC呈流出型;于DWI上呈高或稍高信号,b值为500 s/mm2时,平均ADC值为(1.4±0.3)×10-3mm2/s,b值为1000 s/mm2时,平均ADC值为(1.2±0.3)×10-3mm2/s。1例非肿块型腺病瘤呈区域性分布,呈不均匀强化,TIC呈Ⅰ型。结论腺病瘤DEC-MRI扫描TIC类型和DWI上ADC值表现与乳腺癌相似,但其形态上多呈良性病变特点,MRI检查有助于乳腺腺病瘤的诊断,但确诊仍需依靠组织病理学。     

乳腺髓样癌与纤维腺瘤MRI影像特征及病理对比研究

目的 研究乳腺髓样癌的磁共振表现和临床病理特征,并与纤维腺瘤进行比较.资料与方法 以行乳腺MRI检查并经病理证实的24例女性乳腺髓样癌患者为研究组,32例女性乳腺纤维腺瘤患者为对照组,术前15d内行MRI检查,分析两组患者的MRI表现及病理特征.结果 研究组有10例发生淋巴结转移,而对照组无淋巴结转移.实验组在所有序列上均清晰可见,直径一般为1.0～4.3cm; T1WI均呈低信号,T2WI 4例呈低信号,20例呈明显高信号,时间-信号强度曲线(TIC)为Ⅲ型和Ⅱ型;对照组形态多呈类圆形或分叶状,边界光整;T1WI 18例呈低信号,14例呈等信号,T2WI 2例呈低信号,TIC为Ⅰ型;两组形态、内部强化及病理分级、TIC方面比较,差异有统计学意义(P＜0.05),而患者年龄、病灶大小比较,差异无统计学意义(P＞0.05).结论 MRI影像表现及病理特征有助于诊断乳腺髓样癌.     

乳腺叶状肿瘤的3.0T MRI表现

【摘要】目的：分析乳腺叶状肿瘤的MRI特征,提高对本病的MRI诊断水平。方法：回顾性分析51例经手术病理证实的乳腺叶状肿瘤的MRI资料,其中良性31例、交界性15例、恶性5例。结果：51例叶状肿瘤的主要MRI表现：分叶状或类圆形肿块,边界清晰,T2WI信号多不均匀、可见低信号分隔,动态增强扫描可见低信号分隔不强化,时间-信号强度曲线以渐进型和平台型为主。良性、交界性及恶性叶状肿瘤的ADC值分别为(1.66±0.18)×10-3、(1.54±0.17)×10-3和(1.33±0.23)×10-3mm2/s;恶性和交界性合并后（非良性）ADC值为(1.46±0.21)×10-3mm2/s,与良性肿瘤比较,差异有统计学意义（t=3.08,P<0.05）。结论：MRI能够准确显示乳腺叶状肿瘤的形态学及血流动力学特征,为术前明确诊断提供诊断依据。     

乳腺非肿块性浸润性导管癌的MRI诊断

目的探讨乳腺非肿块性浸润性导管癌的MRI影像学特点。资料与方法回顾性分析27例经手术病理证实的乳腺非肿块性浸润性导管癌,分析病灶的形态、信号特点、ADC值及增强时间-信号曲线(TIC)的类型。结果 27例乳腺癌中,T1WI呈低信号3例,等信号22例,高信号2例;T2WI呈高信号18例,等或稍低信号9例。DWI呈等信号4例,高信号23例。ADC值范围(0.78～1.35)×10-3mm2/s,平均(1.15±0.21)×10-3mm2/s。病灶分布呈节段性17例,局灶性1例,多区域性5例,弥漫性4例。14例见患侧乳腺有明显粗大的动脉血管显影。TIC曲线呈平台型(Ⅱ型)8例,廓清型(Ⅲ型)19例。结论乳腺非肿块性浸润性导管癌的MRI影像表现有一定的特点,以节段性分布、较低的ADC值及Ⅲ型TIC曲线诊断价值最大。     

乳腺叶状肿瘤 MRI表现特征分析

目的：分析乳腺叶状肿瘤（PTB）的MRI表现,提高对该病的认识和诊断水平。方法回顾性分析经手术病理证实的13例PTB的M RI表现,包括肿瘤的形态特征、平扫信号强度、动态增强表现及时间信号强度曲线,类型、DWI信号特征,并与病理结果对照。结果13例PTB均单发。病灶大小为6．2cm ×4．2cm～1．2cm×1．1cm。4例分叶状呈多发结节融合样改变,9例边缘轻度分叶,8例在分叶间见条状分隔延伸至肿瘤内部。M RI平扫T1 WI呈等或稍低信号, T2 WI 9例呈混杂高信号,4例呈均匀高信号。DWI（b值＝800s／mm2）8例呈较高信号,5例呈稍高信号;6例同时检测了ADC图,呈高信号。动态增强扫描11例较均匀明显强化,2例不均匀明显强化,见囊变未强化区。T IC 10例呈Ⅱ型,Ⅰ型2例,Ⅲ型1例。术后病理诊断：良性9例,交界性4例,未见恶性 PTB。结论 PTB的 M RI表现具有一定特征性, M RI检查有助于该病的诊断。     

乳腺叶状瘤的X线及MRI表现

目的探讨乳腺叶状瘤(PT)X线和MRI的影像学特征,以提高其影像诊断和鉴别诊断水平。方法回顾性分析经手术、病理证实的30例PT患者的临床及影像资料,其中22例行X线检查,19例行MRI。结果 30例均为单发,表现为乳腺内直径1.5～21 cm(平均6.2 cm)的肿块;22例行乳腺X线检查者,病灶表现为圆形(5例)或分叶状(17例)、密度高于邻近腺体的肿块,边界清楚(16例)或部分不清(6例),所有病例均未发现钙化及邻近皮肤增厚、乳头回缩、周围乳腺结构扭曲等恶性征象。行MRI的19例患者,病灶表现为圆形(7例)或分叶状(12例),T1WI上呈等信号(8例)或低信号(11例),信号均匀(12例)或不均匀(7例),出现囊变或分隔(5例)、出血(2例);19例肿瘤T2WI上均为高信号,动态增强后时间-信号强度曲线(TIC)呈平台型16例,轻度流出型3例。30例PT病理诊断:Ⅰ级14例,Ⅱ级10例,Ⅲ级6例。结论 PT的影像学表现有一定的特点,尤其MRI动态增强扫描对诊断有重要价值,但其良恶性的判定仍有赖于组织病理学检查。     

11例子宫腺肉瘤的MRI表现及文献复习

目的 总结分析子宫腺肉瘤的MRI表现,以加深对该疾病的认识,提高诊断准确性。 方法 回顾性分析11例经病理确诊为子宫腺肉瘤病人的临床、病理及影像资料,并复习相关文献。分析病灶的部位、大小、边界及MRI信号变化特点,以及表观扩散系数（ADC）值及动态增强时间-信号强度曲线（TIC）。 结果 11例子宫腺肉瘤病人均为单发病灶,MRI显示肿瘤位于子宫腔或宫颈管内,最大径为1.5~12 cm。T₂WI及脂肪抑制（FS）T₂WI上病灶内大部分呈高信号或稍高信号,其中4个呈散在小囊样结构。扩散加权成像（DWI）上8个呈高信号或稍高信号,3个呈中等信号;平均ADC值为（0.94±0.33）×10^-3 mm²/s。增强扫描11个均呈渐进性强化,其中2个呈网格样强化,TIC表现为Ⅰ型6个,Ⅱ型5个。 结论 子宫腺肉瘤的MRI表现具有特征性,对本病的准确诊断有一定帮助。     

廓清型乳腺纤维腺瘤的 MRI 诊断

目的：探讨廓清型乳腺纤维腺瘤的 MRI 表现,提高对此类型肿瘤的影像诊断水平。方法回顾性分析经病理证实的各20例MR 时间-信号曲线(TIC)呈廓清型表现的乳腺纤维腺瘤及乳腺癌的 MRI 图像,归纳、比较2组病变的形态学表现、内部信号、表观扩散系数(ADC)值以及动态增强表现,并进行统计学分析。结果动态增强扫描 TIC 为廓清型乳腺纤维腺瘤形态多为卵圆形或圆形(18/20),边界清楚(16/20),T2 WI 多呈高信号,内部可见无强化的低信号分隔(9/20);平均最小 ADC 值为(1.412±0.332)×10-3 mm2/s,高于乳腺癌(0.888±0.160)×10-3 mm2/s,差异有统计学意义(P <0.05);强化较均匀(16/20),平均早期强化率为(1.694±0.628)×100%,稍低于乳腺癌组(1.849±0.430)×100%,差异无统计学意义(P >0.05)。结论廓清型乳腺纤维腺瘤与乳腺癌在 MRI 动态增强TIC 及早期强化率方面有着相似的表现,但清楚的边缘、更高的 T2 WI 信号、内部无强化的低信号分隔以及更高的 ADC 值有助于廓清型乳腺纤维腺瘤的诊断。     

Phyllodes tumor of the breast: correlation between MR findings and histologic grade

PURPOSE: To retrospectively evaluate the magnetic resonance (MR) imaging findings of phyllodes tumor of the breast and to compare these findings with the histologic grade. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. The authors reviewed the MR findings in 30 female patients aged 16-73 years (mean, 40.2 years) with surgically confirmed phyllodes tumors. Analyzed MR findings included tumor shape, margin, internal enhancement, and size; signal intensity (SI) of tumor higher than that of normal breast tissue on T1-weighted images; SI of tumor lower than or equal to that of normal tissue on T2-weighted images; cyst wall appearance; kinetic curve assessment; and apparent diffusion coefficient (ADC). The MR findings and histologic grade were statistically analyzed to determine whether any correlations existed. Significant MR findings were compared with histopathologic findings. RESULTS: Nineteen benign, six intermediate (characterized by five to nine cell reproductions at 10 high-power fields, pushing or infiltrative margins, moderate stromal cellularity, and atypia and overgrowth), and five malignant phyllodes tumors were assessed. Irregular cyst wall (P = .003), tumor SI lower than or equal to normal tissue SI on T2-weighted images (P = .005), and low ADC (P = .001) correlated significantly with histologic grade. Tumor SI higher than normal tissue SI on T1-weighted images was more frequent in the malignant (in three of five tumors) and intermediate (in three of six tumors) groups than in the benign group (in two of 19 tumors); however, it was not a significant finding (P = .024). Tumor SI higher than normal tissue SI on T1-weighted images and irregular cyst wall corresponded histopathologically to hemorrhagic infarction and necrosis, respectively. Tumor SI lower than or equal to normal tissue SI on T2-weighted images and low ADC corresponded histopathologically to stromal hypercellularity. Other findings were not significant. CONCLUSION: Several MR findings can be used to help determine the histologic grade of phyllodes breast tumors.     

Differentiation of phyllodes breast tumors from fibroadenomas on MRI

OBJECTIVE: The purpose of our study was to evaluate the MRI appearance of phyllodes breast tumors and to differentiate them from fibroadenomas. MATERIALS AND METHODS: MR images were obtained on a 1.5-T imager. T1- and T2-weighted sequences and dynamic 2D fast-field echo T1-weighted sequences were performed. MR images of 23 patients with 24 phyllodes breast tumors (one malignant, 23 benign) were analyzed with respect to morphology and contrast enhancement. The tumors were compared with the MRI appearance of 81 fibroadenomas of 75 patients. RESULTS: Well-defined margins were seen in 87.5% of the phyllodes tumors and 70.4% of the fibroadenomas, and a round or lobulated shape in 100% and 90.1%, respectively. A heterogeneous internal structure was observed in 70.8% of phyllodes tumors and in 49.4% of fibroadenomas. Nonenhancing internal septations were found in 45.8% of phyllodes tumors and 27.2% of fibroadenomas. A significantly greater increase in signal was seen on T2-weighted images in the tissue surrounding phyllodes tumors (21%) compared with fibroadenomas (1.2%). Most of both lesions appeared with low signal intensity on T1- and T2-weighted images. After the administration of contrast material, 33.3% of phyllodes tumors and 22.2% of fibroadenomas showed a suspicious signal intensity-time course. CONCLUSION: Phyllodes breast tumors and other fibroadenomas cannot be precisely differentiated on breast MRI. Phyllodes tumors have benign morphologic features and contrast enhancement characteristics suggestive of malignancy in 33% of cases.     

弥散MRI诊断颅内表皮样囊肿的价值

目的:探讨磁共振弥散加权成像(DWI)及表观弥散系数(ADC)图诊断颅内表皮样囊肿的价值.材料和方法:分析19例表皮样囊肿常规MRI和DWI的信号特征,定量测定表皮样囊肿、正常脑实质和脑脊液的ADC值.结果:17例表皮样囊肿T1WI、T2WI呈等或稍高于脑脊液信号,2例T1WI呈高低混杂信号.肿瘤边缘弧线形增强或不增强.19例肿瘤DWI呈明显高于脑实质和脑脊液信号,肿瘤较脑脊液的平均ADC值显著减低,较脑实质的平均ADC值显著增高.结论:DWI优于常规MRI发现颅内表皮样囊肿,DWI上表皮样囊肿的高信号可能是肿瘤组织的T2余辉效应所致.     

乳腺导管乳头状瘤的MR特征

目的 探讨乳腺导管乳头状瘤(IP)的MRI表现,提高对IP的认识和术前诊断准确性.方法 回顾性分析经手术病理证实的24例IP的MRI表现,包括形态学、平扫信号强度、增强扫描病变内部强化方式及其动态变化特征和时间-信号强度曲线(TIC)类型、DWI上ADC值.采用配对设计资料t检验比较IP和正常乳腺组织ADC值的差异.结果 24例IP最大径0.3～2.0 cm.17例呈圆形或卵圆形,7例不规则形;边界18例清晰,6例欠清.平扫T1WI呈等或稍低信号,T2WI呈稍高信号.动态增强扫捕早期时相肿瘤均明显强化,15例呈较均匀强化,9例强化欠均匀,早期强化率平均值为(156.50±19.67)%,延迟时相18例表现为肿瘤边缘部分信号强度高于中心部分,而呈"环形"表现.TIC 19例旱Ⅲ型,5例呈Ⅱ型.b值为1000 s/ram2时,平均ADC值为(1.14±0.29)×10-3mm2/s,低于正常乳腺组织的ADC值[(1.83±0.32)×10-3mm2/s],差异有统计学意义(t=5.53,P=0.000).结论 IP的动态增强扫描TIC类型和DWI上ADC值表现与乳腺癌相似,动态增强扫描早期强化率和内部强化方式的动态变化特征上具有特征性.

Abstract：

Objective To characterize the MR features of intraductal papilloma of the breast.Methods The MRI data of 24 patients with intraductal papillomas of the breast verified by histopathology were analyzed.The MRI features analyzed included morphology,signal intensity on pre-enhanced T1 WI and FE T2 WI,the patterns of dynamic enhancement,and the mean ADC on DWI.The ADC values for intraductal papilloma and normal breast tissue were compared using paired t test.Results The maximum diameter of the tumors ranged from 0.3 cm to 2.0 cm.Of the 24 tumors,17 were round or oval and 7 were irregular in shape:the margins were well-defined in 18 cases,and ill-defined in 6 cases.AII tumors were isointensity or hypointensity on T1 WI,and slight hyperintensity on T2 WI.On dynamic enhanced images,all the 24 tumors showed rapid initial enhancement.and the mean early phase enhancement rate was(156.50±19.67)%.In the early phase.homogenous enhancement was shown in 15 cases and heterogeneous enhancement in 9 cases.In the delayed phases,the most tumors(18/24)had ring-like enhancement pattern in which signal intensity in peripheral is higher than that in center.The patterns of time-signal intensitycurves were type Ⅲ(washout)in 19 cases and type Ⅱ(plateau)in 5 cases.With b=1000 s/mm2,the mean ADC value for intraductal papilloma[(1.14±0.29)×10-3mm2/s]was significantly lower than that of the normal breast tissue [(1.83±0.32)x 10-3mm2/s (t=5.53,P=0.000).Conclusions MRI features of intraductal papilloma are similar to breast cancer in washout pattern on DCE-MRI and lower ADC value on DWL However,relative lower early enhancement rate and dynamic signal intensity course on DCE-MRI are characteristic clues to differentiating intraductal papilloma from breast eancer.     

Predicting the pathological grade of breast phyllodes tumors: a nomogram based on clinical and magnetic resonance imaging features

Objective:To explore the potential factors related to the pathological grade of breast phyllodes tumors (PTs) and to establish a nomogram to improve their differentiation ability.Methods:Patients with PTs diagnosed by post-operative pathology who underwent pretreatment magnetic resonance imaging (MRI) from January 2015 to June 2020 were retrospectively reviewed. Traditional clinical features and MRI features evaluated according to the fifth BI-RADS were analyzed by statistical methods and introduced to a stepwise multivariate logistic regression analysis to develop a prediction model. Then, a nomogram was developed to graphically predict the probability of non-benign (borderline/malignant) PTs.Results:Finally, 61 benign, 73 borderline and 48 malignant PTs were identified in 182 patients. Family history of tumor, diameter, lobulation, cystic component, signal on fat saturated T₂ weighted imaging (FS T₂WI), BI-RADS category and time–signal intensity curve (TIC) patterns were found to be significantly different between benign and non-benign PTs. The nomogram was finally developed based on five risk factors: family history of tumor, lobulation, cystic component, signal on FS T₂WI and internal enhancement. The AUC of the nomogram was 0.795 (95% CI: 0.639, 0.835).Conclusion:Family history of tumor, lobulation, cystic components, signals on FS T₂WI and internal enhancement are independent predictors of non-benign PTs. The prediction nomogram developed based on these features can be used as a supplemental tool to pre-operatively differentiate PTs grades.Advances in knowledge:More sample size and characteristics were used to explore the factors related to the pathological grade of PTs and establish a predictive nomogram for the first time.     

Magnetic resonance imaging of pyomyositis in 43 cases

PURPOSE: To describe the magnetic resonance imaging (MRI) findings in pyomyositis. METHODS AND MATERIALS: Forty-three patients with proven muscle infection (30 males, 13 females) ranging in age from 14 to 86 years (mean 42 years) were studied with MRI. The initial clinical diagnose were soft tissue infection (n=27), neoplasm (n=12), thrombophlebitis (n=3), and lymphedema (n=1). Spin-echo T1- and T2-weighted images were obtained in all cases and STIR sequence in 6. Spin-echo T1-weighted images after Gd-DTPA injection were obtained in 16 cases. The signal intensity findings, the extent of the abnormalities in the soft tissue (muscle, fascial and subcutaneous involvement), the presence of fluid collections, and the involvement of neighbouring bone and joint were reviewed retrospectively. RESULTS: A hyperintense signal on T2-weighted and STIR images were detected in all patients. Fluid collections were seen in 21 cases as localized areas of hypointensity on the T1-weighted images, and highly hyperintense areas on the T2-weighted images. In four patients a rim of high signal intensity was seen around the fluid collection on the T1-weighted images. On contrast-enhanced T1-weighted images there was diffuse enhancement in the patients without fluid collections that was heterogeneous in seven and homogeneous in two. After Gd-DTPA all fluid collections showed a central area without enhancement and a well-defined enhancing peripheral rim. Involvement of adjacent structures included subcutaneous tissue (n=25), bone marrow (n=14), fascial planes (n=15) and joints (n=11). CONCLUSION: MRI is useful in the assessment of pyomyositis and in determining the location and extension. A hyperintense rim on unenhanced T1-weighted images and peripheral enhancement after Gd-DTPA are useful for identifying the number, size, and location of soft-tissue abscesses.     

鼻道、鼻咽恶性黑色素瘤的MRI诊断

目的 分析鼻道、鼻咽恶性黑色素瘤的MRI表现,探讨其诊断要点.方法 回顾性分析经病理证实的8例鼻道、鼻咽恶性黑色素瘤的MRI特征及临床资料,所有患者均行MR平扫、增强及动态增强检查.结果 肿瘤位于中鼻道1例,鼻咽部2例,鼻腔、上颌窦及同侧筛窦5例.5例可见明显骨质破坏并侵犯邻近结构,累及翼腭窝3例、颞下窝2例、眼眶4例、前颅底2例、咽旁间隙1例.MRI表现:3例直径＜2 cm,呈类圆形肿块,T1WI为高信号,T2 WI为低信号,呈明显均匀强化.5例直径＞3 cm,不规则肿块,MRI表现为混杂信号,T1WI以等、低信号为主,其内有斑片状高信号;在T2WI,1例以等低、信号为主,4例以稍高信号为主,增强扫描呈轻度不均匀强化.动态增强扫描时间-信号强度曲线平台型、流出型各4例.结论 鼻道、鼻咽恶性黑色素瘤MRI信号特征与肿瘤大小相关.肿瘤较小时T1WI呈高信号,T2WI呈低信号;肿瘤较大时MRI信号混杂,轻度不均匀强化为其特征.