Exercise-induced acute renal failure and patchy renal vasoconstriction: CT and MR findings

Contrast-enhanced CT and MR imaging of the kidney were performed in two patients with acute renal failure and severe loin pain following a track race. Prior to the exercise both patients had had flu-like symptoms and took oral medications. There was no evidence of myoglobinuria. Immediate postcontrast CT of the kidney showed multiple patchy areas of poor contrast enhancement; after 24 h, there were multiple patchy enhancing cortical areas on CT without further use of intravenous contrast media. Magnetic resonance imaging of the kidney showed patchy areas of high signal intensity with obliteration of the corticomedullary contrast on T1-weighted images. On T2-weighted images the signal intensity of the lesion was high in one patient and low in the other.     

Delayed CT to evaluate renal masses incidentally discovered at contrast-enhanced CT: demonstration of vascularity with deenhancement

PURPOSE: To determine whether delayed computed tomography (CT) can help confirm vascularity in a neoplasm and differentiate it from a high-density cyst when a well-demarcated homogeneous high-attenuating (> 30-HU) renal mass is incidentally discovered during contrast material-enhanced CT. MATERIALS AND METHODS: In 25 patients, 26 well-demarcated, homogeneous high-attenuating renal masses (mean diameter, 2.5 cm; range, 1-4 cm) detected at initial postcontrast CT were further evaluated with delayed CT (mean, 38 minutes; range, 15-240 minutes) performed with identical parameters. On both the initial postcontrast and delayed CT scans, region-of-interest measurements were obtained in renal masses and in the gallbladder or low-density renal cysts as controls. Correlation with surgical or additional imaging findings was used to determine proof of diagnosis. RESULTS: Nine of the masses demonstrated no change in attenuation between initial postcontrast and delayed CT, indicating that they represented avascular lesions consistent with high-density cysts. These cases were confirmed with prior or follow-up imaging studies that demonstrated stability. Seventeen masses (nine surgically proved neoplasms and eight neoplasms that demonstrated interval growth at follow-up or previous CT) demonstrated decreased attenuation at delayed CT compared with initial postcontrast CT, which indicates vascularity. CONCLUSION: Delayed CT of incidentally discovered well-demarcated homogeneous high-attenuating (> 30-HU) renal masses detected at postcontrast CT enables differentiation of high-density cysts from renal neoplasms by demonstrating deenhancement as a proof of vascularity and, hence, neoplasm.     

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。     

肾螺旋CT平扫与增强延时扫描对肾损伤的诊断

目的探讨螺旋CT平扫与增强延时扫描对肾损伤的诊断价值。方法57例肾损伤患者外伤后30min～3d均经螺旋CT平扫,其中,23例又经增强延时扫描,回顾分析其CT表现特点。结果Ⅰ型肾挫伤（肾内血肿）25例,Ⅱ型肾包膜下血肿11例．Ⅲ型严重肾损伤（肾撕裂或肾断裂）15例,Ⅳ型肾例血肿6例。23例肾损伤CT增强扫描和延时扫描不仅显示了平扫所见,而且,还硅示了肾集合系统损伤导致尿外液渗9例。结论肾螺旋CT平扫与增强延时扫描能显示肾损伤的的部位、范围、类型以及合并其他的损伤,并能指导怖床治疗。     

Computed tomography of high density renal cysts in adult polycystic kidney disease

In a review of abdominal CT in patients with adult polycystic kidney disease 24 patients were found to have single or multiple high density renal cysts on nonenhanced studies. All cases showed well defined, homogeneous high density cysts (56-98 HU), with smooth contours, sharp interfaces with renal parenchyma, and lack of contrast enhancement. The benign nature of these lesions was established by tissue examination in five patients and follow-up CT in four others. In the remaining 15 patients the benign nature of these lesions was assumed based on the constellation of CT and clinical findings.     

Persistent renal enhancement after intra-arterial versus intravenous iodixanol administration

Purpose

To examine the clinical significance of persistent renal enhancement after iodixanol administration.

Methods

We retrospectively studied 166 consecutive patients who underwent non-enhanced abdominopelvic CT within 7 days after receiving intra-arterial (n = 99) or intravenous (n = 67) iodixanol. Renal attenuation was measured for each non-enhanced CT scan. Persistent renal enhancement was defined as CT attenuation >55 Hounsfield units (HU). Contrast-induced nephropathy (CIN) was defined as a rise in serum creatinine >0.5 mg/dL within 5 days after contrast administration.

Results

While the intensity and frequency of persistent renal enhancement was higher after intra-arterial (mean CT attenuation of 73.7 HU, seen in 54 of 99 patients, or 55%) than intravenous contrast material administration (51.8 HU, seen in 21 of 67, or 31%, p < 0.005), a multivariate regression model showed that the independent predictors of persistent renal enhancement were a shorter time interval until the subsequent non-enhanced CT (p < 0.001); higher contrast dose (p < 0.001); higher baseline serum creatinine (p < 0.01); and older age (p < 0.05). The route of contrast administration was not a predictor of persistent renal enhancement in this model. Contrast-induced nephropathy was noted in 9 patients who received intra-arterial (9%) versus 3 who received intravenous iodixanol (4%), and was more common in patients with persistent renal enhancement (p < 0.01).

Conclusion

Persistent renal enhancement at follow-up non-contrast CT suggests a greater risk for contrast-induced nephropathy, but the increased frequency of striking renal enhancement in patients who received intra-arterial rather than intravenous contrast material also reflects the larger doses of contrast and shorter time to subsequent follow-up CT scanning for such patients.     

Sequelae of acute renal infections: CT evaluation

Seventeen patients with upper urinary tract infection who underwent 51 computed tomographic studies (two to five per patient; mean, three) were retrospectively evaluated. Five to 10 days after the initial examination, there was little change in parenchymal abnormalities, but perirenal inflammation worsened and then subsided over 2-8 weeks. Enlargement of the affected kidney, present initially in 12 patients, persisted up to 6 weeks and resolved by 10-16 weeks. Abnormalities of parenchymal contrast material enhancement persisted for 1-2 months. New cortical scars appeared in six of 12 patients with an initially normal renal contour and in one of five patients who had scars initially. Three patients with a renal abscess developed a new calyceal diverticulum, presumably by rupture of the abscess into the collecting system. The present study shows that abnormalities of renal size and enhancement persist for weeks to months after clinical signs of infection resolve and that scarring in adults with urinary tract infection occurs more frequently than was previously realized.     

Measurement of renal extraction fraction with contrast-enhanced CT

Study was approved by the institutional review board, and informed patient consent was waived. A method for minimization of sources of variability in measuring single-kidney extraction fraction (EF) was determined retrospectively with contrast material-enhanced computed tomography (CT). Ten adults underwent CT of the kidneys; precontrast scans were obtained, followed by postcontrast scanning 2 minutes after contrast material injection. Single-kidney EF was then calculated for each patient with the formula EF = (CT(A) - CT(V))/(CT(A) - CT(PRE)), where CT(A) and CT(V) are the postcontrast CT values (in Hounsfield units) of the systemic blood and renal venous blood, respectively, and CT(PRE) is the precontrast CT value of the blood. Both conventional two-dimensional and volumetric three-dimensional regions of interest were used for determining mean CT values of the blood. By using the volumetric regions of interest, left and right renal EF values averaged 17.3% and 18.0%, respectively, for two observers, compared with the accepted value of 15%-20%. This latter technique also minimized right-left kidney and interobserver variability in the measurement of EF.     

动态多期螺旋CT扫描在肝内胆管细胞癌诊断中的价值

目的探讨螺旋CT动态增强扫描在肝内胆管细胞癌诊断中的应用价值。方法对经手术病理证实的30例肝内胆管细胞癌的CT资料进行回顾性分析。结果 30例患者中,肿瘤型18例,平扫表现为肝内单发的低密度不规则肿块,增强动脉期病灶无强化6例,外周部分呈轻度、不完全的环状强化12例,门脉期病灶进一步强化14例,延迟扫描病灶内部呈斑片状持续强化6例、网状或线状持续强化8例,病灶中央始终不强化4例;浸润型4例,平扫表现为肝内胆管壁局限性增厚、管腔狭窄,于增强后各期胆管壁缓慢持续强化;腔内生长型8例,平扫示近肝门部局限性软组织肿块并见肝管扩张增粗及狭窄,增强后近肝门肿块缓慢持续强化。结论螺旋CT动态增强扫描对提高肝内胆管细胞癌的正确诊断率具有一定价值。     

黏液样小管状及梭形细胞肾癌的CT诊断

目的：探讨黏液样小管状及梭形细胞肾癌（MTSRCC）的 CT 表现,提高对该病的认识。方法：回顾性分析8例经手术病理证实的 MTSRCC 的 CT 表现,8例均行 MSCT 平扫及三期增强扫描。分析病灶大小、位置、形态、平扫密度、强化方式和程度、有无周边侵犯、淋巴结和远处转移等征象。结果：8例 MTSRCC 均为单发病灶,CT 上表现为边界清晰的类圆形或椭圆形肿块,最大直径平均为4．53 cm（1．8～7．6 cm）,平扫7例呈等或稍高密度,1例呈低密度,1例伴同侧肾结石,均未见出血和钙化。增强扫描肿瘤呈渐进性轻度强化,6例呈均匀强化,2例呈不均匀强化,其强化程度明显低于正常肾脏皮质,8例皮髓质期和延迟期平均 CT 值分别增加26．2 HU 和33．6 HU,肿瘤与肾皮质的强化比值皮髓质期和延迟期分别为21．54％和33．28％。结论：MTSRCC 为好发于成年女性的较罕见低度恶性肿瘤,在 CT 上表现为边界清晰、出血坏死及钙化少见的规则肿块,可伴有同侧肾结石,具有平扫以等密度为主,渐进性轻度强化的特点。     

Shrinking and disappearing renal cysts

This paper presents 4 patients with what were thought to be hemorrhagic renal cysts that disappeared on follow-up, and an additional patient with a large superficial simple cyst that became smaller on follow-up examination. In 1 patient only was this appearance associated with renal scarring. One patient had uremic-acquired cystic disease of the kidney. The reasons for the disappearance or shrinkage are unclear, but might include bleeding into the cyst or rupture of the cyst into the perirenal space or the collecting system.     

Shrinking and disappearing renal cysts

This paper presents 4 patients with what were thought to be hemorrhagic renal cysts that disappeared on follow-up, and an additional patient with a large superficial simple cyst that became smaller on follow-up examination. In 1 patient only was this appearance associated with renal scarring. One patient had uremic-acquired cystic disease of the kidney. The reasons for the disappearance or shrinkage are unclear, but might include bleeding into the cyst or rupture of the cyst into the perirenal space or the collecting system.     

实体性肾肿瘤的CT诊断（附30例分析）

目的：探讨不同类型实体性肾肿瘤的CT表现特征。方法：回顾性分析30例经手术病理证实的实体性肾肿瘤的CT表现,其中肾透明细胞癌24例,肉瘤样癌1例,肾盂癌2例,嗜酸细胞瘤2例,血管瘤1例。所有病例均行CT平扫和多期增强扫描。结果：2例肾盂癌和1例肾血管瘤主体位于肾髓质,其余肾肿瘤主体均位于肾皮质。增强扫描24例透明细胞癌中21例在动脉期呈不均质显著强化,类似DSA中见到的“肿瘤染色”,而在静脉期和排泄期则呈低密度。3例Ⅰ级透明细胞癌和2例嗜酸细胞瘤类似肾脏的强化形式,即动脉期周边部与肾皮质同等强化,而中央部强化较晚,强化程度也较低。2例肾盂癌1例在动脉期呈不均质明显强化,另1例则始终无明显强化。1例血管瘤在3期均强化不明显。1例肉瘤样癌呈延迟强化,以周边部及类似房隔处强化明显。结论：不同类型的实体性肾肿瘤在CT上有其特殊的表现形式,但分化程度好的透明细胞癌与良性肾肿瘤鉴别较困难,有待于进行更深入细致的研究。     

High-dose i.v. contrast in CT scanning of the postoperative lumbar spine

Evaluation of the postoperative lumbar spine is sometimes difficult because of obliteration of epidural fat by hypertrophic scarring. We examined 70 patients using a high-dose intravenous contrast technique in an attempt to distinguish hypertrophic scarring from herniated disk. The CT interpretation was confirmed in all 17 patients who had follow-up operations. Thirteen had herniated disk material associated with scar and four had hypertrophic scarring only. The latter four patients underwent reoperation because of concomitant foraminal or spinal canal stenosis seen on CT. Twelve of the herniated disks had the expected appearance of a nonenhancing mass surrounded by a rim of enhancing scar tissue. In the 13th patient, homogeneous enhancement of the herniated disk was seen. It is thought that chronically herniated disks, such as this one, may incite enough surrounding scar to give the CT appearance of an enhancing disk. Finally, marginal enhancement in the anulus fibrosus region was seen in over 90% of disk spaces examined. Although an anatomical explanation cannot be given at present, this phenomenon is thought to represent a normal finding.     

Evaluation of exercise-induced acute renal failure in renal hypouricemia using Tc-99m DTPA renography

We present a case of a thirty-eight-year-old man who had exercise-induced acute renal failure (exercise-induced ARF). He experienced oliguria, general fatigue, and vague discomfort in the lower abdomen after he exercised. As he had suffered from hypouricemia before, he was diagnosed as having exercise-induced ARF associated with hypouricemia. Enhanced computed tomography (CT) images showed patchy wedge-shaped contrast enhancement on his bilateral kidneys, consistent with characteristic observations for exercise-induced ARF. Tc-99m diethylene triamine pentaacetic acid (DPTA) renography revealed decreases in both the renal blood flow (RBF) and glomerular filtration rate (GFR), and revealed parenchymal dysfunction of the bilateral kidneys. Renogram revealed a hypofunctional pattern on the bilateral kidneys. CT images and Tc-99m DTPA renography also had improved when the symptoms of exercised-induced ARF indicated improvement. It has been hypothesized that one cause of exercise-induced ARF may be renal vasocontraction. Although CT images are useful in evaluating exercise-induced ARF, Tc-99m DTPA renography can more easily and safely evaluate renal function. We also show that Tc-99m DTPA renography is useful in precisely evaluating the degree of improvement of exercise-induced ARF.     

肾结核的CT诊断（附32例报告）

目的探讨肾结核CT表现及其鉴别诊断。方法经手术病理证实的32例肾结核患者均经CT平扫与对比增强扫描,对其CT表现进行了回顾性分析。结果肾髓质单发或多发囊腔23例（71.9%）,常呈囊状低密度影并围绕肾盂似＂花瓣＂样排列;肾盏、肾盂、输尿管壁不规则增厚23例（71.9%）,伴管腔狭窄或扩张;各种钙化16例（50%）,以及肾脏体积增大17例（53.1%）或缩小5例（15.6%）,肾外形分叶伴积水20例（62.5%）及肾功减退17例（53.1%）,以及自截肾1例（3.13%）。结论肾结核在CT平扫和增强扫描像上具有较特征性的CT表现,对肾结核的诊断具有很重要的价值。     

Patterns and implications of MR contrast enhancement in perinatal asphyxia: a preliminary report.

PURPOSETo determine the presence and location of MR contrast enhancement in infants with perinatal asphyxia and to evaluate the utility of enhancement in assessing extent of brain damage.METHODSPrecontrast and postcontrast MR examinations within the first 10 days of life were evaluated in 10 infants with suspected hypoxic-ischemic birth injury. Findings were correlated with clinical birth history and short-term neurologic follow-up.RESULTSAll four infants with MR signal abnormalities and contrast enhancement in the basal ganglia and brain stem had early seizures and profound neurologic deficits at early follow-up. Two infants had abnormal scans but no contrast enhancement; one with MR signal abnormality within the basal ganglia is neurologically healthy at 10-month follow-up, whereas the other, in status epilepticus at the time of imaging at age 2 days, died. Two infants with minimal parasagittal subcortical white matter enhancement had no early seizure activity and only mild developmental delay at early follow-up. Two infants with normal precontrast and postcontrast MR had no early seizures and remain healthy at early follow-up, despite initial clinical parameters similar to more severely injured infants.CONCLUSIONAlthough the number of patients is small, our results indicate that the presence of contrast enhancement in asphyxiated neonates may indicate more severe brain damage and, hence, a poorer prognosis.     

Segmental renal infarction after blunt abdominal trauma: Clinical significance and appropriate management

Segmental infarction after blunt trauma is an uncommon type of injury occurring as a result of occlusion of a segmental renal artery. We retrospectively reviewed 32 cases of segmental renal infarction after nonpenetrating injury in order to assess the clinical significance and the most appropriate management. Thirty-five segmental infarcts were demonstrated by contrast medium-enhanced computed tomography (CT), 19 in the left and 16 in the right kidney. Twenty-five of the 35 infarcts (71%) occurred as an isolated renal injury. A distinct upper pole predilection for segmental infarct was observed. Angiography showed an occluded branch vessel without contrast medium extravasation in four cases. None of the 30 surviving patients experienced delayed renal hemorrhage or deterioration of renal function. Only 2 of 24 evaluable patients developed mild diastolic hypertension during follow-up. Our data indicate that segmental renal infarction in the blunt trauma patient, as demonstrated by contrast medium-enhanced CT, should be managed nonoperatively and requires no further evaluation with angiography.     

脉络膜血管瘤的MRI表现及动态增强研究

目的 探讨眼脉络膜血管瘤的常规及动态增强MRI表现.方法 回顾性分析30例(31只眼共32个病灶)经临床、眼底相及荧光血管造影确诊的脉络膜血管瘤的MRI资料,其中行平扫和常规增强扫描30例,行动态增强扫描26例,观察各个序列MRI表现,计算动态增强曲线参数.结果 32个脉络膜血管瘤病灶中,位于视乳头颞侧26个病灶,呈梭形28个病灶;与玻璃体信号相比,T1WI呈等信号23个病灶,T2研呈等信号31个病灶;增强后明显强化32个病灶,强化均匀31个病灶,不均匀1个病灶,伴视网膜脱离18只眼;动态增强扫描出现填充征12个病灶,时间-信号曲线呈速升缓降型28个病灶,峰值时问为(91.00±25.27)s,上升斜率为3.03±1.13,流出率中位数为17.06%,强化率为2.87±0.79.结论 脉络膜血管瘤MRI现病灶形态、信号及动态增强具有一定特点,能为临床诊断和治疗方案制定提供重要信息.     

乏脂肪性肾血管平滑肌脂肪瘤的CT表现

目的探讨乏脂肪肾血管平滑肌脂肪瘤（RAML）的CT表现,以提高其诊断准确性。方法 14例RAML患者均经腹部CT平扫和动态增强扫描,对所有患者RAML病灶的数目、形态、密度、是否合并钙化以及强化型式进行回顾性分析,全部病例经手术和病理学确诊。结果多数病灶为边界清楚的圆形肿物,单发或多发,CT平扫多呈等或高密度影,本组病例未见瘤内钙化灶。所有患者的RAML病灶在动态增强的皮质期与实质期均表现为均匀的持续性强化。结论乏脂肪RAML病灶多表现为边界清楚的实性肿块,少有钙化。CT观察病灶的形态,密度及强化形式等特征性表现,有助于提高其定性诊断的准确性。