Evaluation of crossing vessels in patients with ureteropelvic junction obstruction by means of helical CT.

Helical computed tomography (CT) was used to demonstrate the distribution of crossing vessels in patients with ureteropelvic junction (UPJ) obstruction for planning surgical management. Twenty patients with symptomatic UPJ obstruction were evaluated with dual-phase contrast material-enhanced helical CT. In addition to axial images, coronal, sagittal, and curved paracoronal images along the crossing vessels or the UPJ were obtained by means of multiplanar reconstruction. Crossing vessels were evaluated according to type, position, and association with UPJ obstruction. Fifteen vessels in 12 of the 20 patients were found to cross the UPJ at helical CT. Nine vessels were arteries and six were veins; seven vessels crossed anteriorly and eight crossed posteriorly. In 11 patients, crossing vessels were thought to be associated with UPJ obstruction at helical CT; retroperitoneoscopic repair was performed, and the diagnosis was found to have been accurate in all except one. In the eight patients in whom no significant vessels were seen and the one patient in whom the crossing vessel was not associated with UPJ obstruction at helical CT, endopyelotomy was performed and UPJ obstruction was relieved, with no complications. Helical CT is useful for evaluation of vessels crossing the UPJ and for planning surgical management.     

肾盂输尿管连接部梗阻X线诊断分析

目的：回顾性分析16例肾盂输尿管连接部梗阻病因、X线、CT表现，以进一步提高对病因诊断认识，提高术前诊断准确率。方法：采用排泄性尿路造影，逆行尿路造影，CT检查诊断肾盂输尿管连接部阻梗16例。结果：所有病例均清晰显示梗阻的连接部形态特征及尿路积水情况。结论：尿路造影结合CT检查是诊断肾盂输尿管连接部梗阻病因的重要手段，对病因定性、鉴别具有重要意义，对手术治疗可提供重要信息。     

Diuretic radionuclide renography in assessing Anderson-Hynes pyeloplasty in unilateral pelviureteric junction obstruction

The topic of whether improvement can be expected after pyeloplasty in patients with pelvi-ureteric junction obstruction (PUJO) continues to generate debate. The aim of this study was to analyse the functional outcome of unilateral Anderson-Hynes (A-H) pyeloplasty using differential renal function (DRF) and drainage patterns determined by diuretic radionuclide renography (DRR). A retrospective study was carried out by evaluation of the records of patients who underwent A-H pyeloplasty for unilateral PUJO and reported for a follow up renal dynamic scan between the years 2000 and 2003. A total of 126 patients (93 males and 33 females) aged three months to 40 years had undergone pre-operative and post-operative DRR and were followed for at least six months after operation. For comparison, the renal function prior to and after pyeloplasty was classified into three Groups based on the DRF: Group A: > or = 40% DRF 52 patients, Group B: 20%-39% DRF 65 patients and Group C: < 20% DRF 9 patients. The difference between pre-operative and post-operative DRF in the last follow up study, which ranged from six months to 144 months after operation, was calculated for each patient. To account for an accepted error of measurement, an absolute difference in DRF of more than 5% was considered significant. Improvement in drainage was assessed by the time Tmax 1/2 of the renographic curve. Unpaired t test was applied between Group A and Group B patients. Chi square analysis was applied to estimate the proportion of improvement between Groups A and B. Post-pyeloplasty scans revealed stable renal function in 102 (81%) subjects, while improvement was noticed in 14 (11%) subjects. The remaining 10 (8%) subjects had deterioration in renal function. No improvement in renal function was seen in Group C patients. Our results have shown that in the majority of cases studied, after A-H pyeloplasty renal function remains stable. A-H pyeloplasty applied in patients with preserved DRF and obstruction will result in long term preservation of renal function.     

Ureteropelvic junction obstruction: use of helical CT for preoperative assessment--comparison with intraarterial angiography

PURPOSE: To evaluate helical computed tomography (CT) in the preoperative assessment of crossing arteries in kidneys with ureteropelvic junction (UPJ) obstruction and to compare the results with those obtained by means of angiography. MATERIALS AND METHODS: Forty-one consecutive patients with symptomatic UPJ obstruction in 42 obstructed kidneys underwent renal helical CT and renal intraarterial digital subtraction angiography (DSA; flush aortography and bilateral selective renal injections). The helical CT and DSA images were interpreted in a blinded manner by two readers, and the results were compared. RESULTS: DSA showed 126 renal arteries in the 41 patients; 56% of patients had supernumerary renal arteries. Helical CT depicted 121 (96%) of these 126 renal arteries prospectively. Retrospectively, 124 (98%) renal arteries were visible on CT images. Twelve (29%) of the 42 kidneys with UPJ obstruction had identifiable arteries crossing the UPJ on DSA images. If DSA is used as the standard of reference, CT angiography was 100% sensitive and 96.6% specific for depicting these crossing arteries. CONCLUSION: Renal helical CT seems suitable to replace intraarterial DSA in the preoperative assessment of crossing arteries in kidneys with UPJ obstruction.     

Detection of crossing vessels as the cause of ureteropelvic junction obstruction: the role of antegrade pyelography prior to endopyelotomy

PURPOSE: To review the utility of antegrade pyelography in detecting crossing vessels as the cause of uretero-pelvic junction (UPJ) obstruction prior to planned endopyelotomy. MATERIALS AND METHODS: A retrospective review of the medical records, surgical reports, and medical images was performed in 109 consecutive adult patients in our practice who underwent antegrade pyelography just prior to planned endopyelotomy for symptomatic UPJ obstruction between January 1996 and December 2002. RESULTS: Fourteen patients were identified in whom a specific antegrade pyelographic appearance was detected in the diagnosis UPJ obstruction caused by crossing vessels. Surgical plans were changed in all 14 patients from antegrade endopyelotomy to open surgical pyeloplasty, during which the anterior (ventral) crossing vessels causing obstruction were confirmed. An additional three patients in the reviewed endopyelotomy group clinically failed their initial endopyelotomy procedure and were shown at the time of subsequent open or laparoscopic reconstructive surgery to have UPJ obstruction caused by anterior crossing vessels, but that diagnosis was missed at the time of the initial antegrade pyelogram. CONCLUSION: A specific antegrade pyelographic appearance was identified to diagnose UPJ obstruction caused by anterior crossing vessels with a sensitivity of 82.4% and a specificity of 100%. The direct obstructing effect of the vessels on the ureter is defined with pyelography as an acute posteriorly angulated ureteral deformity just below a patent UPJ. Recognition of this specific antegrade pyelographic appearance permits use of an appropriate surgical technique for UPJ obstruction repair.     

Renal trauma in occult ureteropelvic junction obstruction: CT findings

The aim of this study was to present CT findings of occult ureteropelvic junction obstruction in patients with renal trauma and to describe the clinical signs and singular CT features that are characteristically observed with trauma and are relevant to management of these patients. We retrospectively reviewed 82 helical CT studies in patients with renal trauma referred to our institution. We found 13 cases of occult preexisting renal pathology, six of which were occult ureteropelvic junction obstructions. The clinical presentation, radiologic findings of trauma according to the Federle classification, and CT findings of obstructed ureteropelvic junction are presented. We found three category-I lesions (one in a horseshoe kidney), two of them treated with nephrostomy because of increased ureteropelvic junction obstruction due to pelvic clots; two category-II lesions (parenchymal and renal pelvis lacerations) that had presented only with microhematuria; and one category-IV lesion (pelvic laceration alone). Pelvic extension was demonstrated in all the cases with perirenal collections. The CT studies in all the cases with suspected ureteropelvic junction obstruction showed decreased parenchymal thickness and enhancement, and dilatation of the renal pelvis and calyx, with a normal ureter. Computed tomography can provide information to confidently diagnose underlying ureteropelvic junction obstruction in renal trauma, categorize the traumatic injury (at times clinically silent) and facilitate proper management according to the singularities observed, such us rupture of the renal pelvis alone (Federle category IV) and increasing ureteropelvic obstruction due to clots which can be decompressed by nephrostomy. Received: 3 October 1997; Revision received: 6 April 1998; Accepted: 1 July 1998     

Antenatal detection of pelviureteric junction stenosis: main controversies

Although renography has been used for half a century to evaluate the function of the infant kidney, there are still important disagreements among the specialists involved in this particular pathology. Each department of nuclear medicine has his own way to acquire and process a renogram; to interpret the obtained images, curves, and quantitative parameters; and to make recommendations for the referring physician. The urologist has his or her part of responsibilities because the decision for operating or not operating varies from one center to another and is generally determined by a series of unproven assumptions. The aim of the present work is to focus on the main controversies involving both the nuclear medicine physician and the urologist. Concerning the technique of renography. The bladder catheter, systematically recommended in different centers, can best be replaced in most of the cases by a much less-invasive procedure, namely the acquisition and processing of late postmicturition (PM) posterect images. The change of patient's position contributes strongly to the renal washout. Intravenous hydration is used to standardize the level of hydration. However, the patients, in most of the cases, are in good health, and adequate oral hydration is sufficient. Even if hydration was not ideal when the procedure began, the administration of furosemide and the late PM images will result in a very good drainage of a normal kidney. Any renal tracer with high extraction rate is adequate, but diethylene triamine pentaacetic acid ((99m)Tc-DTPA) does not allow a precise estimation of differential function in children younger than 6 months. The moment of furosemide injection (F0, F+20, F-15) does not influence the quality of the final renal washout, and the F0 procedure is recommended in cases of known hydronephrosis because it shortens the time of acquisition on the gamma camera and allows the simultaneous injection of both the tracer and the diuretic. Background correction remains controversial among nuclear medicine physicians. Including in the background area some liver and spleen activity, which are responsible for an important part of the extrarenal activity within the renal area, will improve the quality of the renogram curve, suppressing almost completely the initial vascular phase. The supporters of the Rutland-Patlak (R-P) fit for calculating differential function state that the vascular component is eliminated better than with use of the classical integral method. However, this method is based on a slope, with counting statistics being rather poor in infants with immature function. In most of the cases, the integral method will provide robust results. Determination of the same differential function by the use of both methods increases the level of confidence of the final results. It is generally admitted that the first renogram in children with antenatally detected hydronephrosis should be performed at approximately 1 month of age. However, there is a tendency to start earlier, and even in the first days of life, in case of huge hydronephrosis. The renogram should be repeated in case of significant hydronephrosis, significant increase of dilation, poor response to furosemide, or low initial differential function. Moderate dilation associated with normal differential function can probably be monitored by ultrasound alone. T(?) of the diuretic curve is an empiric parameter that does not take into account the bladder emptying and the change of patient's position. Output efficiency (OE) and normalized residual activity (NORA), measured on the late PM and posterect images, represent physiological parameters not dependent on the input function of the considered kidney and can be used whatever the moment of furosemide injection. There is presently no way to quantitatively measure cortical transit in antenatally detected pelviureteric junction syndrome; all methods are limited by the slight kidney motion related to respiratory movements and by the almost-complete superimposition between cortical area and collecting system. The best approach probably is a visual estimation. Concerning the position of the urologist. The main controversy is related to the definition of obstruction and the indication for surgery. Neither the degree of hydronephrosis nor the impairment of differential function and/or the quality of the response to furosemide can define which kidney is in danger of further deterioration. Alternatively, these parameters are unable to predict for which kidneys an improvement of differential function can be expected because of a pyeloplasty. It has not been excluded, according to recent published work, that cortical transit could be a better predictive factor of the risk of a conservative attitude or the benefits of a surgical procedure, but this procedure has still to be confirmed.     

Nasal airway obstruction: CT assessment

Twenty-one cases of nasal airway obstruction were analyzed using computed tomography (CT) at the Children's Hospital in Boston between 1980 and 1984. Seven of these patients had stenosis of the entire nasal passage, two had stenosis of the anterior nasal cavity, and 12 had atresia of the posterior choanae. The spectrum of these abnormalities and the optimum technique for CT scanning are discussed.     

The efficacy of helical CT in the diagnosis of small bowel obstruction

OBJECTIVE: To evaluate the usefulness and reliability of helical computed tomography (CT) for patients with small bowel obstruction. METHODS AND MATERIAL: Helical CT findings of 41 patients were evaluated prospectively on the basis of the presence and the cause of obstruction, and the presence of strangulation. RESULTS: In the determination of the cause of the obstruction sensitivity and specificity of CT were 84 and 90%, respectively. Of the 19 patients undergoing surgery, 6 had strangulation and were correctly identified by CT. CONCLUSION: Helical CT is an accurate method in the detection of small bowel obstruction, especially for evaluating the cause and vascular complications of obstruction.     

Single-detector helical CT in PET-CT: assessment of image quality

OBJECTIVE: CT in positron emission tomography (PET)-CT imaging is often performed as a single scan from the base of the skull to the groin, potentially resulting in degradation of the quality of CT scans depending on the position of the patient's arms and mode of breathing and the use and timing of IV contrast injection. The aim of our study was to assess the impact of artifacts on the diagnostic quality of CT scans using a single-detector helical CT scanner in PET-CT imaging. MATERIALS AND METHODS: Two radiologists retrospectively evaluated the diagnostic image quality of CT scans obtained with PET-CT in 81 patients with lymphoma. The severity of the artifacts related to the position of the patient's arms beside the body, the influence of breathing motion, and the presence of contrast material in the upper thoracic veins were ranked using a 4-point scale. RESULTS: Performing CT with the patient's arms positioned beside the body resulted in streak artifacts, predominantly in the upper abdomen, that were graded as mild in 22%, moderate in 40%, and severe in 38% of the scans. A patient's weight significantly correlated with the degree of severity of the artifacts (p < 0.05). Shallow breathing by the patient during scanning caused blurring and double-imaging, again predominantly in the upper abdomen, that were graded as mild in 23%, moderate in 49%, or severe in 28% of the scans. In 84% of the CT scans obtained with IV contrast material, the image quality of the upper thoracic region was moderately (27%) or severely (57%) degraded by streak artifacts from highly concentrated contrast material in the upper thoracic veins. CONCLUSION: The use of a single-detector CT scanner in whole-body PET-CT decreases the image quality of CT scans because of streak artifacts that occur predominantly in scans of the upper abdomen. Scanning with the patient's arms raised eliminates the streak artifacts in scans of the abdominal region. With the new generation of PET-CT devices equipped with MDCT scanners, breathing motion artifacts can be expected to be eliminated if protocols for breath-hold CT are applied. Reversing the direction of CT scanning allows one to avoid imaging the thoracic region at a time when undiluted IV contrast material is still present in the upper thoracic veins.     

Paddle-wheel multislice helical CT display of pulmonary vessels and other lung structures

The authors have now instituted the paddle-wheel method of CT reconstruction imaging of the lungs as a routine supplement to the standard axial multislice helical CT pulmonary angiography images for pulmonary embolism, and are exploring its role in other diseases. This unique way of viewing lung structures adds a new dimension to pulmonary imaging. Large-scale comparison studies of the traditional and the proposed paddle-wheel CT display method are necessary to quantitate their relative clinical effectiveness in the evaluation of the pulmonary vasculature, airways, and lungs.     

MSCTA和MSCTU对肾盂输尿管连接部梗阻的诊断价值

目的：探讨MSCT血管成像（MSCTA）及尿路成像（MSCTU）在肾盂输尿管连接部梗阻（UPJO）诊断中的价值。方法：回顾性分析经手术病理证实的16例UPJO患者的MSCTA及MSCTU影像资料,利用多种后处理重组技术（MPR、CPR、MIP、VR）进行重组。结果：16例肾盂输尿管连接部梗阻中,梗阻位置全部诊断正确。梗阻原因诊断为输尿管息肉1例,血管压迫3例,炎性狭窄12例。术前诊断与手术探查及病理结果基本一致。结论：MSCTU和MSCTA可作为UPJO术前评估的常规方法,在诊断引起UPJO的疾病方面具有重要价值。     

Intermittent hydronephrosis: a unique feature of ureteropelvic junction obstruction caused by a crossing renal vessel

Obstruction at the ureteropelvic junction (UPJ) is usually intrinsic. Recently, however, 13 (11%) of approximately 120 children with UPJ obstruction were found to have extrinsic obstruction caused by a lower-pole renal vessel. In each case, the obstruction was confirmed at the time of surgery. Most of these patients had intermittent pain. Excretory urograms did not show obstruction between episodes of pain, but when a urogram was obtained during an episode, marked obstruction was noted. Contrast agent trapped in a segment of proximal ureter suggests the presence of an extrinsic obstruction. Properly timed renal imaging, therefore, can identify the urinary tract as the source of the symptoms.     

多层螺旋CT周围血管成像的初步应用

目的 :探讨多层螺旋CT(MSCT)在周围血管疾病中的应用价值。方法 :对 18例临床怀疑周围血管疾病的患者 ,均行上肢或下肢动脉或静脉CT血管造影。动脉系统疾病经肘前静脉以 3ml/s流率注入 10 0ml对比剂 ,延迟 2 5～40s后扫描 ;静脉性疾病经足背静脉或手背静脉以 1ml/s流率注入 5 0ml对比剂 ,延迟时间为 60～ 70s。扫描条件为层厚3 .2mm ,重建间隔 1.6mm ,螺距 1.2 5。结果 :动脉系统疾病 10例 ,狭窄或闭塞性疾病 9例 ,其中 1例合并动脉瘤 ,1例传统血管造影均不能插管操作 ,1例动脉瘤MRA以及传统血管造影均没有做出正确诊断 ;1例为正常下肢动脉。静脉系统疾病 3例 ,其中下肢深静脉血栓 2例 ,上肢多发性静脉瘤 1例 ,经传统血管造影证实。结论 :应用MSCT诊断周围血管疾病有一定的临床价值。     

Silicosis: expiratory thin-section CT assessment of airway obstruction

PURPOSE: To prospectively evaluate if findings on paired inspiratory and expiratory thin-section computed tomographic (CT) scans in patients with silicosis correlate with pulmonary function test results. MATERIALS AND METHODS: Institutional review board approval and patient consent were obtained. Thirty-seven men (mean age, 71 years; range, 53-88 years) with silicosis were included. All patients had undergone inspiratory and expiratory thin-section CT and spirometry. Silicotic nodules, large opacity, emphysema, reticular opacities, bronchiectasis, and air trapping were graded subjectively on CT images. Emphysema was quantified on these images with built-in software. CT numbers were correlated with spirometric findings by using Spearman rank correlation analyses. Ten healthy volunteers (three men and seven women; mean age, 58 years) served as control subjects. RESULTS: After exclusion of three patients with inadequate image quality, 34 patients (mean age, 70 years; range, 53-88 years) were enrolled in the study group. Spirometric values did not differ significantly between patients with simple (n = 20) and patients with complicated (n = 14) silicosis but were significantly lower in patients than in control subjects. CT findings included air trapping (n = 33), emphysema (n = 26), nodules (n = 32), bronchiectasis (n = 22), large opacity (n = 19), and reticulation (n = 5). The extent of both air trapping and emphysema correlated negatively with spirometric values; the air trapping score showed the strongest correlation (ratio of forced expiratory volume in 1 second to forced vital capacity [FVC]: rho = -0.632, P < .001; forced expiratory flow at 50% of the FVC: rho = -0.576, P = .001). Silicotic nodule, large opacity, and bronchiectasis scores did not correlate with obstructive functional impairments. CONCLUSION: In comparison with the spirometric value, the extent of air trapping proved the best CT index in the assessment of obstructive derangement in workers with exposure to silica dust.