肾上腺转移瘤的动态CT、MRI检查

目的 探讨动态增强CT及MRI检查对肾上腺转移瘤的鉴别诊断价值.方法 搜集资料完整的17例(共27个)肾上腺转移瘤,观察其大小、形态及强化特征,分析肿瘤廓清率对肾上腺转移瘤的鉴别诊断价值,并对2种检查(CT和MRI)方法进行相关性分析.结果 17例共27个肾上腺转移瘤中,63%肿块边缘不光滑且形态不规则,67%肿块增强后呈不均匀强化,所有肿块随时间延迟均呈轻、中度逐渐强化,达峰值后肿块内对比剂排空缓慢.在动态增强CT及MRI检查中,于延迟5 min肾上腺转移瘤的廓清率分别仅为12.7%和11.4%.2种检查方法在延迟5 min时相关性最大,相关系数0.819(P=0.024).结论动态增强CT及MRI检查对绝大多数肾上腺转移瘤可做出正确定位、定性诊断,有利于治疗方案的正确制订.     

动态增强CT检查对肾上腺腺瘤与非腺瘤的鉴别诊断价值

目的探讨动态增强CT检查技术对肾上腺腺瘤与非腺瘤的鉴别诊断价值并优选出有意义的参数，以进一步明确两者的鉴别诊断标准。资料与方法对44例共49个肾上腺肿瘤先平扫再行动态增强CT检查，观察以肿瘤的CT绝对值、绝对开始廓清率及相对开始廓清率作为标准鉴别肾上腺腺瘤与非腺瘤的诊断价值。结果延时3min，以36％的绝对开始廓清率或35％的相对开始廓清率分别与CT绝对值58HU相结合作为标准，对腺瘤有较高的诊断价值，对于腺瘤中的乏脂质性腺瘤与非腺瘤的鉴别诊断也具有同样的价值。结论以肿瘤的廓清率与延时增强后的CT绝对值作为联合标准，能明显提高腺瘤的诊断价值。     

良、恶性乏脂质性肾上腺肿瘤的动态MRI检查

目的：探讨MRI动态增强检查技术对乏脂质性肾上腺肿瘤良、恶性的鉴别诊断价值。方法：经手术和临床证实的29例共33个乏脂质性肾上腺肿瘤行MRI平扫并于注药后1min、2min、3min、5min、7min和9min时间点行动态增强检查,分别观察病变的增强程度并获取乏脂质性肾上腺肿瘤的廓清率（Wash）和时间-信号强度曲线（T-S curve）,以评估良、恶性肿瘤间是否存在统计学差异。结果：T-S曲线分Ⅰ~Ⅴ五种类型。良性乏脂质性肿瘤的特征曲线为Ⅰ、Ⅱ型和Ⅳ型;恶性乏脂质性肿瘤的特征曲线为Ⅲ型和Ⅴ型（P=0.000）,肾上腺良性乏脂质性肿瘤的廓清率高于恶性肿瘤,两者之间差异有统计学意义（P=0.006）,在5min延迟点诊断价值较大,Wash≥23%提示为良性肿瘤。结论：MRI动态增强检查技术对乏脂质性肾上腺肿瘤良、恶性的鉴别诊断具有较高价值。     

肿瘤廓清率在动态增强MRI检查中对肾上腺肿瘤的鉴别诊断价值

目的　探讨应用动态增强MRI检查技术 ,以肿瘤的廓清率为标准 ,再结合该时间点的信号增加比 ,对肾上腺腺瘤与非腺瘤进行鉴别诊断的临床价值。方法　 3 6例共 41个肾上腺肿瘤均先行常规SE序列T1 WI及T2 WI成像 ,再利用屏气快速多层面破坏性梯度回波序列 (fastmultiplanarspoiledgradient-echo ,FMPSPGR)行轴位扫描 ,先平扫 ,再以同样条件行MRI动态增强检查 ,观察病变的增强程度并分别测量肿瘤实质部分的信号值。分别比较腺瘤与非腺瘤的廓清率及信号增加比 ,明确其鉴别诊断价值。结果　延时 5min并以廓清率 2 2 %为阈值时 ,诊断腺瘤的敏感性 74% ,特异性 73 % ,准确性 73 % ;若将延时 5min时肿瘤的廓清率 (2 2 % )与信号增加比(<0 .48)相结合 ,则诊断腺瘤的敏感性、特异性、准确性明显提高 ,分别为 95 %、91%、93 %。结论　利用动态增强检查技术 ,以肿瘤的廓清率为标准 ,再结合该时间点的信号增加比 ,可在最短的时间内提高肾上腺腺瘤与非腺瘤的鉴别诊断水平     

肾上腺腺瘤与非腺瘤的CT鉴别诊断

目的 探讨肾上腺腺瘤与非腺瘤的CT鉴别诊断价值.方法 回顾性分析经手术和随访证实的56例(58个病灶)肾上腺肿瘤的CT表现及病理组织学特征,患者均行CT平扫及1 min、5 min增强扫描,对诊断参数进行分析并对照病理组织学表现,对肾上腺肿瘤做出正确的诊断.结果 腺瘤与非腺瘤在CT平扫及增强后1 min、5 min的CT值、相对廓清率和绝对廓清率的差异均有统计学意义(P＜0.05),以平扫时CT≤19 HU,延时5 min时CT≤46 HU,绝对廓清率≥63%,相对廓清率≥31%为阈值相结合作为诊断标准时,诊断腺瘤或乏脂性腺瘤的敏感性分别为96%或86%.结论 以肿瘤平扫及增强后的CT值与肿瘤的廓清率作为联合标准,对腺瘤(包括乏脂性腺瘤)与非腺瘤的鉴别诊断有较高的价值.     

增强MRI时间-信号增强率曲线对肾上腺肿瘤的鉴别价值

目的 :以肿瘤的时间 信号增强率曲线作为诊断标准 ,进一步证实Gd DTPA动态增强MRI检查技术对肾上腺肿瘤的鉴别诊断价值。方法 :3 6例共 41个肾上腺肿瘤 ,腺瘤 19例共 19个 ,非腺瘤 17例共 2 2个。所有肿瘤均先行常规SE序列T1 W和T2 W成像 ,选定肿瘤中心层面定位后 ,再利用屏气快速多层面破坏性梯度回波序列 (FMPSPGR)行轴位扫描 ,先平扫 ,再以同样条件行MRI动态增强检查 ,即静注Gd DTPA ,自注药后 0 .5min开始扫描 ,之后分别在 60min内共 17个时间点 ,以同等条件延时扫描 ,观察病变的增强程度 ,并分别测量其实质部分的信号值。计算肿瘤的信号比、最大信号增加比、增强率 ,再根据随时间延时肿瘤增强率的变化绘制曲线 ,比较肾上腺肿瘤间的时间 信号增强率曲线有无差异 ,并明确其对肾上腺肿瘤的鉴别诊断价值。结果 :Ⅰ型时间 信号增强率曲线具有高度特异性 ,只有大多数神经源性肿瘤符合此增强特点 ,对区分腺瘤与其它类型的非腺瘤无诊断价值 ;以Ⅲ型或Ⅳ型曲线为标准诊断恶性肿瘤的准确率均不高 ,有 5 0 %的恶性肿瘤无法确诊 ;而以Ⅱ型时间 信号增强率曲线为标准较前 3种曲线更有助于肾上腺肿瘤的鉴别诊断 ,即以早期增强 ,延时 9min内肿瘤增强率下降程度超过肿瘤最大增强率的 5 0 %为诊断腺瘤的标准 ,敏     

CT动态增强鉴别肾上腺乏脂肪腺瘤与肾上腺结节样增生的价值

目的探讨CT动态增强对鉴别肾上腺乏脂肪腺瘤与肾上腺结节样增生的价值。方法回顾性分析经手术病理证实的12例肾上腺乏脂肪腺瘤和27例肾上腺结节样增生患者的病例资料,统计两组病例各期增强CT值,利用公式灌注值P=CT静脉期-CT平扫期、廓清值C=CT静脉期-CT延迟期、绝对廓清灌注指数APC=(C/P)×100%及相对廓清灌注指数RAPC=(C/CT静脉期)×100%得到相关参数,并通过绘制受试者工作特征曲线,鉴别两者的最佳价值。结果肾上腺乏脂肪腺瘤直径较结节样增生更大;肾上腺乏脂肪腺瘤病灶各期CT值均明显高于结节样增生,且两者灌注值P、廓清值C、APC及RAPC有明显的统计学差异。年龄、性别、高血压、病灶位置、对侧肾上腺萎缩及动脉期CT值对鉴别两者无显著意义。结论CT动态增强扫描有助于鉴别肾上腺乏脂肪腺瘤和肾上腺结节样增生。     

肾上腺腺瘤和非腺瘤的动态增强CT检查

目的采用规范化的动态增强CT检查技术,对大样本病例进行深人地多角度评价．使肾上腺肿瘤动态增强CT检查能够在临床上广泛应用。资料与月法经手术和临床证实的70例共79个肾上腺肿块（腺瘤44个．非腺瘤35个）分别以相同的扫描条件行CT平扫和动态增强检查（静脉注人对比剂后30s开始扫描）,然后延时1、2、3、5．7min扫描。剂量1．2ml／kg体重,注射流率2．5ml／s。分析评价肾上腺肿块的T—D曲线和廓清率Wash（相对廓清率Washr和绝对廓清率Washa）。结果T—D曲线分为5种类型,即A、B、C、D和E各型。腺瘤的特征曲线为A、C型,非腺瘤为B、D、E型（P=0．000）。Washr和Washa于腺瘤和非腺瘤间存在显著性差异（P=0．000）,腺瘸的Washr和Washa均高于非腺瘤,并且Washr诊断效果优于Washa。7min延时点诊断价值较大．Washr≥34HU提示为腺瘤．反之提示为非腺瘤。结论肾上腺CT动态增强检查能够对腺瘤和非腺瘤尤其对乏脂性腺瘤与非腺瘤的鉴别诊断具有较大价值。     

肾上腺双能CT增强扫描方案的优化

目的:探讨肾上腺病变双能CT增强扫描检查方案的优化及其临床应用价值。方法:2011年3月-2011年6月来我院就诊并接受双能成像(GSI)三期增强扫描的患者12例(共12个肾上腺结节,腺瘤9个、恶性病变3个),测量病变在平扫、门脉期(对比剂注射后70s)及长延迟期(对比剂注射后5min)的密度值,计算出病变在各单能量下的完全灌注廓清率(APW)和相对灌注廓清率(RPW),并与病理及临床诊断结果进行对照分析,使用受试者工作特征(ROC)曲线计算各能级下的最大诊断效能。结果:在各KeV(40～140KeV)下使用文献经典对比剂廓清率的诊断敏感度和特异度偏低。使用ROC曲线计算各KeV下鉴别腺瘤和恶性肿瘤的APW和RPW能达到较高的诊断敏感度和特异度,其中APW界值范围为-19.5%～36.0%,RPW界值范围为11%～19%;并且,APW及RPW的敏感度和特异度在低能级(40～70KeV)下均较高:敏感度为100%、特异度为66.7%。结论:双能CT虽不能明显提高延迟5min时经典对比剂廓清率对肾上腺病变的诊断敏感度和特异度,但有估算出在各个能级下的APW和RPW诊断界值范围的潜在价值;综合各能级下的廓清率界值范围有利于提高对肾上腺良恶性结节的鉴别诊断敏感度和特异度。     

乏脂性肾血管平滑肌脂肪瘤与非透明细胞肾癌的多层CT鉴别诊断

目的 探讨多层CT(MDCT)对乏脂性肾血管平滑肌脂肪瘤(AMLmf)与非透明细胞肾癌的鉴别诊断价值.方法 回顾性分析108例患者的临床及影像资料,其中AMLmf 19例,乳头状肾细胞癌(PRcc) 43例,嫌色细胞肾癌(ChRcc) 46例,均在术前行MDCT平扫及增强扫描.由两名放射科医师盲法分析肿瘤形态学特征和平扫强化特点,采用独立样本t检验、x2检验及秩和检验进行分析.利用多因素Logistic回归分析法评价CT征象的预测价值,受试者工作特征(ROC)曲线用于鉴别AMLmf与非透明细胞肾癌.结果 AMLmf较PRcc及ChRcc有更高的女性患病率.AMLmf在肿瘤大小、钙化、假包膜、肿瘤内血管、囊变坏死方面与PRcc及ChRcc相比,差异有统计学意义(P＜0.05).PRcc较AMLmf及ChRcc晚期强化发生率更高.多因素Logistic回归分析结果表明肿瘤内血管和囊变坏死是区分AMLmf与非透明细胞肾癌最有价值的预测变量.AMLmf平扫CT值、皮髓期△H值及廓清率均高于PRcc及ChRcc(P＜0.05).ROC曲线分析肿瘤平扫CT值、皮髓期△H值和廓清率鉴别AMLmf与非透明细胞肾癌的曲线下面积分别为0.808、0.739和0.772.当肿瘤平扫CT值为41.15 HU时,鉴别AMLmf与非透明细胞肾癌的敏感性为78.9％,特异性为77.5％;当皮髓期△H值为39.35 HU时,鉴别AMLmf与非透明细胞肾癌敏感性为78.9％,特异性为68.5％;当廓清率为-7.26％时,鉴别AMLmf与非透明细胞肾癌的敏感性为63.2％,特异性为84.3％.结论 肿瘤内部血管和囊变坏死是鉴别AMLmf与非透明细胞肾癌最有价值的预测变量.肿瘤平扫CT值、皮髓期△H值和廓清率有助于鉴别AMLmf与非透明细胞肾癌.     

Delayed enhanced CT of lipid-poor adrenal adenomas

OBJECTIVE. Although representing a minority of adrenal adenomas, the lipid-poor variety cannot be accurately identified on unenhanced CT or chemical shift MR imaging. We compared the delayed contrast-enhanced CT features of lipid-poor adenomas with those of lipid-rich adenomas and of adrenal nonadenomas to determine whether there were differences in the washout features between these groups of lesions. SUBJECTS AND METHODS. Eighteen proven lipid-poor adenomas, 56 lipid-rich adenomas, and 40 adrenal nonadenomas underwent CT before, immediately after, and 15 min delay after IV contrast injection. Region-of-interest measurements were made of all adrenal lesions at the three time points. The degree of enhancement, enhancement washout, percentage enhancement washout, and relative percentage enhancement washout were calculated for each adrenal mass. Pooled data were analyzed statistically. Optimal threshold values for diagnosing adrenal adenomas were also determined. RESULTS. The mean CT attenuation of lipid-poor adenomas was significantly higher than that of lipid-rich adenomas at all three phases but not significantly different from that of nonadenomas. The mean percentage enhancement washout on images obtained 15 min after administration of contrast material was similar for lipid-rich and lipid-poor adenomas but was significantly higher than that of nonadenomas. The mean relative percentage enhancement washout was significantly different among all three groups. CONCLUSION. Lipid-poor adenomas cannot be differentiated from adrenal nonadenomas on the basis of a single mean attenuation value. However, lipid-poor adrenal adenomas show enhancement and enhancement washout features nearly identical to lipid-rich adenomas and can be distinguished from nonadenomas on the basis of a percentage washout threshold value of 60% and a relative percentage washout of 40%.     

Magnetic resonance tomography of adrenal gland tumors. Detection and differentiation using fast gradient echo sequences and dynamic contrast media studies

The use of fast gradient echo sequences enable reduction of the acquisition times in MR imaging, allowing examinations during suspended respiration. Furthermore, repeated single slices in the same position after administration of a paramagnetic contrast agent provide dynamic evaluation of tissue perfusion. These new diagnostic modalities were applied for imaging normal adrenal glands in 128 cases and for differentiation of 83 adrenal tumors in 74 patients. CT remains the imaging method of choice for the detection of adrenal masses, due to the higher spatial resolution. Fast gradient echo MRI offers the possibility of differentiation between benign and malignant adrenal lesions. The 70% accuracy reached with precontrast scans can be augmented to 90% using dynamic contrast-enhanced studies.     

Evaluation of adrenal masses in oncologic patients: dynamic contrast-enhanced MR vs CT

The CT examinations, precontrast gradient echo MR images, and fast contrast enhanced dynamic MR studies were evaluated in 44 patients with 52 adrenal masses and known malignant disease of different origin. Morphologic features (size, shape, attenuation, contour, and enhancement) on CT scans, signal intensity on T2-weighted MR images, and patterns of enhancement on Gd-DTPA enhanced dynamic MR studies were analyzed in all patients. With dynamic contrast enhanced studies with prolonged imaging up to 15 min after Gd-DTPA, masses with moderate enhancement and complete washout after 10 min were considered as adenomas. Computed tomography and plain MR had a sensitivity of 0.71 and 0.96, a specificity of 0.75 and 0.88, and overall accuracy of 0.56 and 0.71, respectively. Simultaneous use of precontrast MR and dynamic contrast enhanced studies led to an accurate diagnosis in 88% (sensitivity = 1.0, specificity = 0.91) and thus should be considered in oncologic patients with undetermined adrenal masses.     

原发性肾脏罕少见良性肿瘤的CT、MRI 表现与临床病理分析

目的：分析和探讨肾脏罕少见良性肿瘤的 CT、MRI 影像学表现及临床病理分析,提高肾脏罕少见良性肿瘤的诊断准确性。方法回顾性分析本院9例经手术及病理证实的肾脏罕少见良性肿瘤的 CT 及 MRI 影像学资料,分析其影像学特点和病理特征。结果入组病例分别为混合型上皮间质肿瘤(MESTK),囊性肾瘤(CN),平滑肌瘤(RL),嗜酸细胞腺瘤(RO)。病变分布情况：6例位于左肾,3例位于右肾。瘤体大小：长径2.5~8.9 cm,平均5.7 cm;短径2.5~8.4 cm,平均4.9 cm。形态：类圆形或椭圆形(n=7),不规则形(n=2)。9例病灶突出于肾轮廓外。MESTK 呈多囊性病变,增强扫描囊性成分未见明确强化,囊壁及粗间隔可见强化。CN 呈囊性病灶,平扫可见斑片状钙化,增强扫描囊性成分未见明确强化,病灶可见强化分隔影。RL 的 CT 和 MRI 平扫密度/信号不均匀,可见斑片状坏死;病灶增强扫描皮质期及髓质期明显强化,延迟期强化程度减退。RO 1例 MRI 平扫 T1 WI 呈不均匀低信号;T2 WI 呈不均匀高信号;CT 病灶密度欠均匀,平扫以等密度为主;增强扫描皮质期、髓质期病变呈明显不均匀强化,排泄期强化程度下降,中心瘢痕可见轻度延迟强化。结论肾脏罕少见良性肿瘤具有一定的 CT、MRI 影像学特点,结合其临床病理特点,可以提高肾脏罕少见恶性肿瘤的诊断和鉴别诊断。     

动态增强MRI时间信号强度曲线在卵巢良恶性肿瘤鉴别中的价值

目的探讨动态增强MRI时间信号强度曲线(TIC)鉴别卵巢肿瘤良恶性的价值。方法收集2016年1月—2017年8月间于我院超声检查发现盆腔附件肿块的71例女性病人,年龄14～78岁,中位年龄52岁。所有病人行MRI常规及动态增强检查后经手术获得病理结果。利用工作站在肿块实性区和正常子宫外肌层设置兴趣区获取TIC,以子宫外肌层强化曲线为基准,对卵巢肿块实性区的TIC类型进行校正,分析曲线类型与良恶性卵巢肿瘤的关系。采用χ~2检验比较良恶性肿瘤间3种TIC类型差异。结果 71例病人中包括卵巢恶性肿瘤40例,良性肿瘤26例,交界性肿瘤5例。上述3种肿瘤的TIC类型的差异有统计学意义(P0.05)。良性肿瘤以Ⅰ型TIC为主(73.1%),恶性肿瘤以Ⅲ型TIC为主(77.5%)。MRI+TIC鉴别肿瘤良恶性的敏感度、特异度、阳性预测值和阴性预测值较单独常规MRI检查各指标均有不同程度提高。结论动态增强MRI及其TIC对卵巢良恶性肿瘤具有重要的鉴别诊断价值。     

Retroperitoneal Bronchogenic Cyst Presenting Paraadrenal Tumor Incidentally Detected by 18F-FDG PET/CT

A follow-up ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET/CT scan of a 57-year-old asymptomatic male who had undergone total thyroidectomy for thyroid cancer revealed a 5.0 × 4.0-cm, well-defined, ovoid-shaped mass around the left adrenal gland without definite FDG uptake. On the adrenal CT scan, the left paraadrenal tumor showed high attenuation on the precontrast scan without enhancement. The average Hounsfield unit (HU) was 58.1 on the precontrast scan and 58.4 on the postcontrast scan. The patient underwent laparoscopic adrenalectomy for resection of the left paraadrenal tumor. The final histopathologic examination revealed a bronchogenic cyst. Although retroperitoneal bronchogenic cysts are rare, they should be considered in the differential diagnosis of retroperitoneal cystic tumors. The preoperative diagnosis is difficult, but a contrast-enhanced CT scan or ¹⁸F-FDG PET/CT scan may be useful for differentiating hyperattenuated cysts from other soft tissue masses.     

Characterization of indeterminate (lipid-poor) adrenal masses: use of washout characteristics at contrast-enhanced CT

PURPOSE: To determine whether computed tomographic (CT) scans and attenuation measurements on contrast material-enhanced and nonenhanced CT scans could be used to characterize adrenal masses, in particular, to characterize these lesions by using adrenal washout characteristics at contrast-enhanced CT. MATERIALS AND METHODS: Eighty-six patients (49 men, 37 women; age range, 29-86 years; mean age, 72 years) with 101 adrenal lesions depicted at contrast-enhanced CT underwent delayed (mean, 9 minutes) enhanced scanning. Seventy-eight patients also underwent nonenhanced CT. Mean diameter of the benign lesions was 2.1 cm (range, 1.0-4.2 cm); mean diameter of the malignant lesions was 2.3 cm (range, 1.0-4.1 cm). Region-of-interest measurements were obtained at nonenhanced, dynamic enhanced, and delayed enhanced CT and were used to calculate a relative percentage washout as follows: 1 - (Hounsfield unit measurement on delayed image / Hounsfield unit measurement on dynamic image) x 100%. RESULTS: Ninety-nine of 101 lesions were correctly characterized as benign or malignant with a relative percentage washout threshold of 50% on delayed scans; benign lesions demonstrated more than 50% washout; and malignant lesions, less than 50% washout. Two benign lesions demonstrating less than 50% washout were characterized as benign by using conventional CT. CONCLUSION: Calculation of relative percentage washout on dynamic and delayed enhanced CT scans may lead to a highly specific test for adrenal lesion characterization, reduce the need for, and possibly obviate, follow-up imaging or biopsy.     

Distinguishing benign from malignant adrenal masses: multi-detector row CT protocol with 10-minute delay

PURPOSE: To retrospectively evaluate the accuracy of precontrast attenuation, relative percentage washout (RPW), and absolute percentage washout (APW) in distinguishing benign from malignant adrenal masses at multi-detector row computed tomography (CT). MATERIALS AND METHODS: This HIPAA-compliant retrospective study had institutional review board approval; the need for informed consent was waived. One hundred twenty-two adrenal masses were evaluated in 99 patients (51 men, 48 women; age range, 37-86 years) who had undergone CT performed according to the study protocol and who either were given a pathologic diagnosis or underwent follow-up imaging. Unenhanced images were obtained before administration of 120 mL of an intravenous contrast agent with a 75-second scan delay. Delayed images were obtained after 10 minutes. RPW and APW were computed. Receiver operating characteristic (ROC) analysis was performed to compare mean attenuation and both RPW and APW. Analysis was first performed with the exclusion of pheochromocytomas, myelolipomas, and cysts. Precontrast attenuation criteria specific for benignity or malignancy were determined, and ROC analysis of results for the entire nonpheochromocytoma group was then performed. RESULTS: By using an RPW of 37.5% and excluding cysts and myelolipomas, all malignant lesions were detected with a sensitivity of 100% (17 of 17 lesions) and a specificity of 95% (90 of 95 lesions). Area under the binomial ROC curve (A(z)) values were 0.912, 0.985, and 0.892 for precontrast attenuation, RPW, and APW, respectively. Precontrast attenuation of less than 0 or more than 43 HU indicated benign and malignant entities, respectively. Incorporation of these criteria into the APW analysis yielded a sensitivity of 100% (17 of 17 lesions) and a specificity of 98% (93 of 95 lesions) for a threshold washout value of 52.0%. This attenuation-corrected APW generated the greatest A(z) value (ie, 0.988). Combining all the information available from the protocol yielded a sensitivity of 100% (17 of 17 lesions) and a specificity of 98% (98 of 100 lesions) for differentiating benign from malignant masses. CONCLUSION: Precontrast attenuation of less than 0 HU supercedes the washout profile in the evaluation of an individual adrenal mass. Noncalcified, nonhemorrhagic adrenal lesions with precontrast attenuation of more than 43 HU should be considered suspicious for malignancy.