Accuracy of repeated kidney size estimation by ultrasonography and urography in children

The accuracy of repeated sonographic and urographic kidney length measurements in kidney size evaluation was investigated in 80 children 0 to 14 years of age, mean age 4.5 years. At sonography 250 kidney lengths were compared. A difference of 0 to 1.0 cm in repeated length measurement was considered to be good accuracy and 94 per cent of right and 96 per cent of left kidney lengths were found within this interval--a better result than for urography with 76 per cent of repeated right kidney and 79 per cent of kidney lengths within the same interval (94 lengths). Both methods display a variation of kidney length which may lead to under- and overestimation of kidney size and growth. The investigation thus indicates good accuracy for repeated sonographic kidney size assessment which should be repeated often enough to establish a growth chart displaying the trend rather than rely too much on single measurements. Sonography can be highly recommended as a convenient and harmless alternative to urography.     

CT urography and MR urography

CT urography and MR urography are an evolving concept and developing technique. As the technology matures, CT urography will combine the ultimate diagnostic capabilities of intravenous urography and CT. In the near future, many intravenous urograms will be replaced by CT urography to evaluate patients with hematuria and other genitourinary conditions. MR urography currently serves as an alternative imaging technique to intravenous urography and CT urography for children and pregnant women and for patients with contraindications to iodinated contrast media.     

Urography in the child who wets.

Most children who wet have no underlying structural abnormality and will not benefit from urography. However, several conditions may mimic simple enuresis, and in children with clinical clues that suggest these diagnoses, urography can be confirmatory. The urogram should be conducted so as to exclude an anatomic cause for wetting. This is likely in females in the presence of a duplex collecting system, a nonfunctioning kidney, marked vaginal reflux, or a widened interpublic distance. In the urogram of a child of either sex, a spinal anomaly should be sought.     

Metrizamide in high-dose urography.

The non-ionic water-soluble contrast medium metrizamide (Amipaque) was used for high-dose urography in 11 patients with apparently normal renal function. Films of good quality were obtained. Adverse reactions and the effect on pulse and blood pressure as well as a large number of blood and urine laboratory parameters were recorded. Only clinically insignificant effects occurred, and the medium is recommended for further use in urography.     

Functional, dynamic, and anatomic MR urography: feasibility and preliminary findings.

RATIONALE AND OBJECTIVES: The authors assessed the feasibility of using magnetic resonance (MR) urography to acquire functional, dynamic, and anatomic information in human subjects with normal and hydronephrotic kidneys. MATERIALS AND METHODS: In subjects known to have or suspected of having hydronephrosis, split renal filtration fractions were measured with a customized magnetization-prepared, inversion-prepared gradient-recalled echo sequence to determine the T1 of flowing blood in the inferior vena cava and aorta before and after contrast medium administration and in the renal veins and arteries after contrast medium administration. Multiple timed sets of coronal fast spoiled gradient-echo 70 degrees flip-angle images were acquired before and after contrast medium administration to derive MR renograms from changes in the signal intensity of the cortex and medulla. Precontrast T2-weighted images were obtained with a three-dimensional fast spoiled gradient-echo maximum intensity projection pulse sequence, and postcontrast T1 maximum intensity projection images were also obtained to depict the renal anatomy. RESULTS: Split filtration fraction differentiated normal from hydronephrotic kidneys. MR renograms depicted vascular, tubular, and ductal phases and differentiated between normal and hydronephrotic kidneys (P < .05, n = 20). Contrast medium dose correlated with the peak of the cortical signal intensity curves on the renogram (r = 0.7, P < .0005; n = 20). The sensitivities for the visual determination of hydronephrosis and unilateral delayed excretion of contrast material were both 100%, and the specificities were 64% and 85%, respectively. CONCLUSION: The preliminary findings show promise for the use of MR urography in the comprehensive assessment of renal function, dynamics, and anatomy.     

Sonography, urography and angiography in kidney carcinoma. A comparative study

In a comparative study the validity of angiographic, sonographic and urographic findings for evaluation of 204 renal tumors was investigated. Angiography showed 97% correct results, sonography 96% and urography 93%. Mean tumor size was 8.4 cm. 25% of all tumors caused renal vein occlusion. On the one side there is a striking correlation between tumor growth and vein occlusion, and on the other side between vein occlusion and urographic silent right kidney. 20% of all tumors had metastasized at the time of diagnosis. In 4.5% of all cases we found a left sided symptomatic varicocele of the left side with invasion of the left renal vein by tumor masses.     

Fluid restriction before excretory urography.

Despite a lack of hard evidence, many radiologists continue to support the use of fluid restriction before urography. Based on increasing the urinary contrast medium concentration, this has been shown to be a poor index for renal opacification. The usual overnight restriction produces no significant change in urine osmolality or opacification. Effective fluid restriction may produce a just detectable increase in pyelographic density but the nephrogram in unaffected, even by active hydration. Fluid restriction may occasionally result in inadvertent dehydration with serious or fatal reactions. Since it is ineffectual in improving the urogram and potentially hazardous, it should be abandoned.     

Patient radiation dose at CT urography and conventional urography

PURPOSE: To measure and compare patient radiation dose from computed tomographic (CT) urography and conventional urography and to compare these doses with dose estimates determined from phantom measurements. MATERIALS AND METHODS: Patient skin doses were determined by placing a thermoluminescent dosimeter (TLD) strip (six TLD chips) on the abdomen of eight patients examined with CT urography and 11 patients examined with conventional urography. CT urography group consisted of two women and six men (mean age, 55.5 years), and conventional urography group consisted of six women and five men (mean age, 58.9 years). CT urography protocol included three volumetric acquisitions of the abdomen and pelvis. Conventional urography protocol consisted of acquisition of several images involving full nephrotomography and oblique projections. Mean and SD of measured patient doses were compared with corresponding calculated doses and with dose measured on a Lucite pelvic-torso phantom. Correlation coefficient (R(2)) was calculated to compare measured and calculated skin doses for conventional urography examination, and two-tailed P value significance test was used to evaluate variation in effective dose with patient size. Radiation risk was calculated from effective dose estimates. RESULTS: Mean patient skin doses for CT urography measured with TLD strips and calculated from phantom data (CT dose index) were 56.3 mGy +/- 11.5 and 54.6 mGy +/- 4.1, respectively. Mean patient skin doses for conventional urography measured with TLD strips and calculated as entrance skin dose were 151 mGy +/- 90 and 145 mGy +/- 76, respectively. Correlation coefficient between measured and calculated skin doses for conventional urography examinations was 0.95. Mean effective dose estimates for CT urography and conventional urography were 14.8 mSv +/- 90.0 and 9.7 mSv +/- 3.0, respectively. Mean effective doses estimated for the pelvic-torso phantom were 15.9 mSv (CT urography) and 7.8 mSv (conventional urography). CONCLUSION: Standard protocol for CT urography led to higher mean effective dose, approximately 1.5 times the radiation risk for conventional urography. Patient dose estimates should be taken into consideration when imaging protocols are established for CT urography.     

MSCT曲面重组尿路成像与MRU对泌尿系病变的诊断比较

目的:比较MSCT曲面重组尿路成像(CTU)与磁共振尿路成像(MRU)在泌尿系病变检查中显示和诊断疾病的能力,探讨CTU、MRU对泌尿系病变的定位、定性诊断价值。方法:24例临床提示有泌尿系病变的患者,行MRI检查,采用单次激发快速自旋回波(SSFSE)序列,行MRU检查,同期采用10mm层厚层距,完成从肾上极至耻骨联合下缘CT平扫及增强扫描,获得原始横断面图像,将22例肾实质期和6例肾排泄期图像进行后处理,获得冠状面、矢状面及任意斜面尿路图像,在此基础上,再沿尿路走行方向管腔中心划曲线,进行曲面重组(CPR),获得CTU图像。采用盲法,比较CTU、MRU对泌尿系病变的定位、定性诊断价值。结果:CTU、MRU均对泌尿系梗阻病变部位作出明确诊断,定位诊断符合率为100%;CTU、MRU定性诊断符合率分别为100%和58.8%。对输尿管下段的显示CTU优于MRU,CTU能清楚地显示尿路全貌及其周围组织结构。结论:CTU、MRU对泌尿系梗阻病变均能明确定位;CTU定性诊断符合率明显高于MRU,能更直观显示泌尿系病变与扩张肾盂、输尿管的关系,在泌尿系病变诊断方面具有独特的优势。     

Medullary rays. Visualization during excretory urography.

The medullary rays are well-defined anatomic structures consisting of bundles of renal tubules which form in the renal cortex and continue through the renal medulla as the medullary striations. These structures are occasionally visualized during excretory urography in abnormal physiologic states characterized by tubular stasis and hyperconcentration of contrast material. Under these conditions, fine striations are visualized which correspond in position and orientation to these structures. The work of others has shown that in tubular stasis, contrast material is hyperconcentrated in the tubules. On microradiography in normal and obstructed kidneys, the highest concentrations of contrast material are seen in the lumen of collecting ducts. Lastly, retrograde injection of contrast material into the medullary rays produces a roentgen image similar to our illustrated cases.