In vitro CT comparisons of dissected phleboliths and retrieved ureteral calculi

Purpose: This project was designed to assess the accuracy of radiologists in distinguishing between pelvic phleboliths and ureteral calculi by CT scanning in vitro. Materials and methods: Twenty-five phleboliths were dissected from autopsy specimens, and 23 ureteral calculi were retrieved intact and all calcifications made available for this study. Calcifications were suspended in ordinary butter and subjected to CT scanning using both bone and soft tissue windows. A panel of three radiologists blinded to the correct diagnoses independently assessed the images. The questions asked were: was the calcification a phlebolith or a stone? was it round or irregular? did it have a central “hole” or not? Confidence levels for each observer and each question were rated on a semicontinuous scale from 0 to 100 and receiver-operating characteristic (ROC) curves computed. Results: ROC curves for distinguishing between ureteral stones and calculi ranged from .78 to .99. As a subset, ROC curves for roundness alone, assuming phleboliths tended to be round and calculi not, ranged from .85 to .98. These ROC curves for roundness alone correlated closely with overall performance in distinguishing ureteral stones from phleboliths. ROC curves for determining central radiolucencies, however, although the latter were assumed to be hypothetically present in phleboliths, were degenerate for two observers, and only .57 for the third. Conclusions: Under optimal in vitro conditions, pelvic phleboliths and ureteral calculi do possess characteristics, especially shape, that many permit discrimination by CT scanning.     

Nonenhanced helical CT and US in the emergency evaluation of patients with renal colic: prospective comparison

PURPOSE: To compare nonenhanced helical computed tomography (CT) with ultrasonography (US) for the depiction of urolithiasis. MATERIALS AND METHODS: During 9 months, 45 patients (mean age, 44 years; mean weight, 92.5 kg) prospectively underwent both nonenhanced helical CT (5-mm collimation; pitch of 1.5) and US of the kidneys, ureters, and bladder. US evaluation included a careful search for ureteral calculi. Presence of calculi and obstruction and incidental diagnoses were recorded. Clinical, surgical, and/or imaging follow-up data were obtained in all patients. The McNemar test was used to compare groups. RESULTS: Diagnoses included 23 ureteral calculi and one each of renal cell carcinoma, appendicitis, ureteropelvic junction obstruction, renal subcapsular hematoma, cholelithiasis, medullary calcinosis, and myelolipoma. CT depicted 22 of 23 ureteral calculi (sensitivity, 96%). US depicted 14 of 23 ureteral calculi (sensitivity, 61%). Differences in sensitivity were statistically significant (P: =.02). Specificity for each technique was 100%. When modalities were compared for the detection of any clinically relevant abnormality (eg, unilateral hydronephrosis and/or urolithiasis in patients with an obstructing calculus), sensitivities of US and CT increased to 92% and 100%, respectively. One case of appendicitis was missed at US, whereas medullary calcinosis and myelolipoma were missed at CT. CONCLUSION: Nonenhanced CT has a higher sensitivity for the detection of ureteral calculi compared with US.     

Assessment of the clinical utility of the rim and comet-tail signs in differentiating ureteral stones from phleboliths.

OBJECTIVE: This study was designed to assess interobserver variability in identifying the rim and comet-tail signs and to determine the clinical utility of these signs in determining whether or not the calcifications with which they are associated represent ureteral calculi. MATERIALS AND METHODS: Two radiologists and a radiology resident, unaware of the final diagnosis, reviewed preselected helical CT images from renal stone examinations in patients with 65 indeterminate pelvic calcifications. Assessment of calcifications for rim or comet-tail signs was performed independently of an assessment for the following five secondary signs of urinary tract obstruction: caliectasis, pelviectasis, ureterectasis, perinephric stranding, and renal enlargement. Agreement in identifying rim and comet-tail signs was assessed by obtaining kappa statistics. The utility the of rim or comet-tail signs in determining whether ureterolithiasis was present in patients in whom perinephric stranding and ureterectasis were present or absent was determined. The frequency with which one or more of each of the five assessed secondary signs was identified ipsilateral to a calcification having rim or comet-tail signs was also tabulated. RESULTS: Kappa values for interobserver agreement ranged from 0.49 to 0.73. In only one patient was a rim sign detected in the absence of ureterectasis and perinephric stranding. Reviewers identified at least three of the five assessed secondary signs ipsilateral to calcifications showing a rim sign in all but one patient (by each radiologist) and four patients (by the resident). When three or more secondary signs of obstruction were seen ipsilateral to a calcification having a comet-tail sign, in all but one instance, this was because the calcification was a ureteral calculus or because there was a separate ipsilateral ureteral calculus. CONCLUSION: In many instances, observers did not agree about whether the rim and comet-tail signs were present. The rim sign was observed in the absence of any secondary signs of urinary tract obstruction in only one (1.5%) of the 65 patients in our series (95% confidence interval, 0-5.3%). The comet-tail sign, when accompanied by secondary signs of obstruction, should indicate that an ipsilateral ureteral stone is present and not the reverse.     

Distinguishing pelvic phleboliths from distal ureteral calculi: thin-slice CT findings

The objective is to evaluate the appearance of phleboliths and distal ureteral stones by determining their roundness and presence of central lucency on thin-slice CT. Seventy-seven patients with pelvic radioopacities at unenhanced CT were selected. Those patients consequently underwent thin-slice CT with 1-mm collimation, a FOV of 10 cm, a pitch of 1:1 and a bone reconstruction algorithm. Three radiologists reviewed all images for roundness and the presence of central radiolucency. No calculi showed central lucency on either imaging technique used. Thin-slice CT revealed central lucency in 60% of phleboliths with 100% specificity. Three of 40 ureteral stones showed round contour. Thin-slice CT revealed a round contour in 97% of phleboliths with 93% specificity. Central lucency is a characteristic finding of pelvic phleboliths on thin-slice CT. This finding can therefore be used in combination with roundness as a problem-solving tool in differentiating phleboliths from distal ureteral stones.     

Sensitivity of CT scout radiography and abdominal radiography for revealing ureteral calculi on helical CT: implications for radiologic follow-up

OBJECTIVE: We compared the sensitivity of CT scout radiography with that of abdominal radiography in revealing ureteral calculi on unenhanced helical CT. MATERIALS AND METHODS: Over a 6-month period, patients presenting to the emergency department with acute flank pain were examined with standard abdominal radiography and unenhanced helical CT, which included CT scout radiography. In 60 patients in whom a diagnosis of ureteral calculus was made, CT scout radiographs and abdominal radiographs were examined by two interpreters who assessed whether stones could be visualized. All CT scout radiographs were viewed on a workstation using optimized window settings. RESULTS: CT scout radiography and abdominal radiography revealed 28 (47%) and 36 (60%) of 60 ureteral calculi, respectively. All ureteral calculi that appeared on CT scout radiography also appeared on abdominal radiography. However, eight calculi that were visible on abdominal radiography were not visible on CT scout radiography. CT scout radiography and abdominal radiography revealed 28% and 46% of 39 calculi less than or equal to 3 mm in diameter, respectively. For 21 calculi larger than 3 mm, the sensitivity of CT scout radiography and abdominal radiography was 81% and 86%, respectively. CONCLUSION: Abdominal radiography is more sensitive than CT scout radiography in revealing ureteral calculi; however, some calculi revealed on unenhanced helical CT cannot be seen on either abdominal radiography or CT scout radiography. Ureteral calculi not visible on either study can only be followed, when necessary, with unenhanced helical CT.     

Central lucency of pelvic phleboliths: comparison of radiographs and noncontrast helical CT

To compare how often the central lucency of pelvic phleboliths is seen on plain radiographs and noncontrast helical computed tomography (CT), both images in 70 patients with renal colic were analyzed. Both images revealed the same number of phleboliths in all cases except one in which one of two phleboliths demonstrated by CT was not seen on radiographs. Radiography revealed central lucency in 95 of 149 pelvic phleboliths (63%), but CT failed to depict a hypodense center in any of 150 phleboliths. The presence or absence of central lucency on CT images cannot, therefore, be used to differentiate phleboliths from distal ureteral calculi.     

Suprapelvic phleboliths: prevalence, distribution and clinical associations

The preliminary radiographs of 783 patients undergoing excretory urography were prospectively surveyed for the presence of abdominally located phleboliths. Two per cent demonstrated typical densities in a periureteral distribution flanking the lumbar spine where they could be confused with ureteral calculi. All these patients were multiparous females and three-quarters of them had pelvic masses (11% of all patients with pelvic masses), suggesting a possible association with gonadal vein thrombi. Altered venous flow with dilatation of ovarian veins, consequent valvular incompetence and stasis may account for the gonadal vein distribution in the pelvic mass cases. Other observed clinical conditions included hepatic disease, portal hypertension and varices. Obstruction and stasis of venous flow in hepatic disease states may lead to phlebolith formation in gastric and mesenteric varices. Unlike pelvic phleboliths, suprapelvic phleboliths are infrequent but may be detected by careful inspection of low kilovoltage films, particularly in the regions closely flanking the lumbar spine. Their presence may be associated with pelvic masses or significant chronic hepatic disease and they may be confused on plain film with ureteral calculi.     

Acute ureterolithiasis: nonenhanced helical CT findings of perinephric edema for prediction of degree of ureteral obstruction

PURPOSE: To determine whether the extent of perinephric edema on helical computed tomographic (CT) images without contrast material enhancement can be used to predict the degree of ureteral obstruction in patients with acute ureterolithiasis. MATERIALS AND METHODS: Nonenhanced helical CT and excretory urographic images in 82 patients with flank pain were retrospectively reviewed. For each patient, a radiologic diagnosis was established, and the degree of ureteral obstruction determined on urograms was compared with the extent of perinephric edema assessed on CT images. RESULTS: None of 29 patients with no abnormalities seen at urography had evidence of perinephric edema at CT. Of six patients with noncalculous disease, two with acute pyelonephritis had perinephric edema at CT. Of 47 patients with acute ureterolithiasis, eight had no perinephric edema at CT and a nonobstructing calculus at urography, 21 had limited edema at CT and low-grade obstruction at urography, and 15 had extensive edema at CT and high-grade obstruction at urography. Three patients had extensive perinephric edema at CT but low-grade obstruction at urography. The extent of edema allowed accurate prediction of the degree of ureteral obstruction in 44 (94%) of 47 patients with acute ureterolithiasis. CONCLUSION: The extent of perinephric edema on nonenhanced helical CT images can be used to predict the degree of ureteral obstruction in acute ureterolithiasis.     

Radiographically occult ureteral calculi in an HIV-positive child undergoing indinavir therapy

Helical CT has been shown to be a sensitive and specific tool for the rapid diagnosis of obstructing urinary tract calculi. AIDS patients taking the protease inhibitor indinavir, however, can develop urinary tract calculi that are invisible on CT. We present a case of a 9-year-old HIV-positive girl who developed acute ureteral obstruction while taking indinavir. Helical CT after the administration of intravenous contrast demonstrated signs of ureteral obstruction although no obstructing calculus was visualized. This case demonstrates that obstructing ureteral calculi secondary to indinavir therapy may not be visualized with helical CT, unlike nearly all other obstructing calculi. When secondary signs of obstruction are seen in these patients, the radiologist must have a high index of suspicion for urinary tract calculi even without direct visualization of a stone.     

Trends in the use of unenhanced helical CT for acute urinary colic

OBJECTIVE: Unenhanced helical CT for urolithiasis detection is a limited CT examination that was designed specifically for the detection of urolithiasis. The purpose of this study was to repeat a prior study to assess whether clinicians had broadened the indications and changed the yield and findings of unenhanced helical CT. MATERIALS AND METHODS: One hundred consecutive patients with suspected renal colic or flank pain referred for unenhanced helical CT were selected for this study. We reviewed the original radiographic reports for each patient and recorded the presence of ureteral calculi. Other urinary abnormalities and extraurinary lesions were also recorded and compared with the results of the previous study. RESULTS: In this study, 56% of the patients who underwent unenhanced helical CT had symptoms of urinary colic, and 44% of patients had unspecified flank pain, compared with 100% of patients with symptoms of urinary colic 1 year earlier. The sensitivity and specificity of unenhanced helical CT in detecting ureteral calculi were 96% and 99%, respectively. Ureteral calculi were identified in only 28% of the patients versus 49% of patients (p < .01) 1 year earlier. Extraurinary lesions were identified in 45% of the patients versus 16% (p < .01) 1 year before. CONCLUSION: As clinicians developed familiarity with this technique, the indications for performance of unenhanced helical CT were expanded with a consequent reduction in the rate of detection of stone disease and identification of an increased number of extraurinary lesions, which suggests a demand for emergency abdominal CT studies.     

螺旋CT多平面重建诊断输尿管结石的临床价值

目的 :探讨螺旋CT扫描结合多平面重建 (MPR)在输尿管结石诊断中的应用价值。材料和方法 :对 42例输尿管结石的患者行螺旋CT扫描并行多平面重建 (MPR) ,其中 4例行增强延时扫描。结果 :CT确诊输尿管结石 95 .3 % ( 4 0 /4 2 ) ;MPR图像质量分为好、较好、差 ,分别为 66.7% ( 2 8/4 2 )、2 3 .8% ( 10 /4 2 )、9.5 % ( 4 /4 2 )。结论 :螺旋CT结合MPR可全面、立体、直观地显示输尿管结石及梗阻扩张的程度 ,在诊断和鉴别诊断方面具有重要的临床价值。     

Abdominal radiography after CT reveals urinary calculi: a method to predict usefulness of abdominal radiography on the basis of size and CT attenuation of calculi

OBJECTIVE: The purpose of this study was to determine if the radiographic visibility of urinary tract calculi could be predicted on the basis of CT features. MATERIALS AND METHODS: The images of 26 patients whose urinary tract calculi were revealed on unenhanced helical CT and who also underwent digital abdominal radiography were retrospectively reviewed. CT features studied included size and CT attenuation of the calculi. These CT findings were correlated with the ability to detect the same calculi with radiography. RESULTS: Forty-nine urinary tract calculi were detected with unenhanced helical CT in 26 patients. Twenty-six (53%) calculi were visible on radiography. Most (79%) calculi larger than 5 mm were detectable with radiography (p < 0.01). One (8%) of 13 calculi with CT attenuation below 200 H was detectable on radiographs. Ninety-five percent (21/22) of calculi with CT attenuation exceeding 300 H were visible on radiographs (p < 0.0001). The one remaining calculus was obscured by overlying anatomy. CONCLUSION: Radiographic surveillance of urinary tract calculi detected with CT may not be useful if the calculi have a CT attenuation below 200 H. Most calculi larger than 5 mm and nearly all calculi with a CT attenuation exceeding 300 H can be seen on abdominal radiographs.     

螺旋CT诊断输尿管结石的应用价值（附32例报告）

目的评价螺旋CT对输尿管结石的诊断价值。方法对32例临床表现急性腰腹痛、镜下血尿，可疑输尿管结石的患者，行螺旋CT检查，将获得的容积图像行三维立体重建成像处理。结果31例螺旋CT图像显示出输尿管结石，确诊率97％。8例CT三维立体成像显示结石引起肾盂、输尿管扩张及结石周围组织水肿等继发性变化。结论螺旋CT诊断输尿管结石安全、快捷、准确，有较高的临床应用价值。     

螺旋CT对输尿管远段结石可疑病例的诊断价值

目的：探讨螺旋CT对输尿管远段可疑结石病例的诊断价值。方法：临床通过X平片，静脉尿路造影（胛）及B超检查高度怀疑输尿管远段结石60例病例，对照手术病理结果及临床排石证实结果，并结合Cr检查资料进行分析。结果：60例病例中有51例Cr诊断输尿管远段结石，阳性率为85％。其中2例为血管壁钙化，6例盆腔静脉石，1例为邻近髂骨骨岛。结论：螺旋Cr对输尿管远段结石的诊断价值很高，通过平扫及多平面图像重建技术（MPVR）能较容易与相邻结构区分并进行鉴别诊断，特别是对临床症状相符，又通过X线平片，静脉尿路造影及B超检查高度怀疑结石的病例进行CT检查，具有很高的准确性。     

螺旋CT及其泌尿系成像对输尿管病变的诊断价值

目的 探讨螺旋CT及其泌尿系成像（spiral CT urography,SCTU)技术对输尿管病变的诊断价值。方法 27例输尿管病变患者中,结石9例、肿瘤5例、狭窄9例、畸形1例、炎症1例及输尿管瘘2例。均行螺旋CT泌尿系检查。注射对比剂后10－15min行螺旋CT容积扫描,在工作站利用软件进行图像后处理,获得泌尿系立体图像。其中15例同时行螺旋CT平扫,10例行静脉泌尿系造影。结果 （1）螺旋CT平扫8例阴性结石清晰可见。（2）SCTU图像上,8例阴性和1例阳性结石可见其、形态、大小及扩张的肾孟和输尿管;5例输尿管肿可见局部管腔内对比剂柱变细或突然中断,管壁不光整;7例单纯狭窄可见狭窄部位管腔逐渐变细,管壁无明显增厚。2例迷走血管压迫致狭窄者均位于肾孟输尿管交界处;1例重复肾并输尿管畸形者显示双肾孟、双输尿管;输尿管瘘者显示瘘口位置、走行。结论 与普通CT及静脉泌尿系造影（IVU）相比,螺旋CT及其SCTU技术有明显优越性,可使静脉管病变诊断准确率明显提高。     

The role of renal scintigraphy and unenhanced helical computerized tomography in patients with ureterolithiasis

Unenhanced helical computerized tomography (UHCT) has recently evolved as an accurate imaging modality for determination of the presence or absence of ureterolithiasis in patients with acute flank pain. Functional renal scintigraphy is considered the gold standard for urinary tract obstruction. The objective of this study was to correlate the secondary signs of urinary obstruction on UHCT with findings of functional renal scintigraphy. UHCT was performed in 30 patients admitted to the emergency room with acute flank pain. All patients had a calcified urinary stone identified on UHCT. The location of each urinary stone was classified as ureteral or in the ureterovesical junction. The presence of secondary CT signs of ureteral obstruction was determined for each patient. After oral or intravenous hydration, a technetium-99m diethylene triamine penta-acetic acid renal scan was performed in all patients within 12 h of the CT scan. Follow-up delayed scintigraphic images were obtained at 2 h and 24 h in patients with evidence of ureteral obstruction. The sensitivity, specificity and predictive values of each possible combination of CT findings were determined by comparison with the scintigraphic results. The distal ureter was the most common location for a calculus on UHCT, followed in frequency by the ureterovesical junction, proximal ureter and mid-ureter. The renograms showed high-grade, unilateral obstruction in 12 patients, indeterminate scans in five patients and normal renograms in 13 patients. The sensitivities and specificities of individual CT findings ranged from 50% to 75% and from 8% to 69%, respectively. Perinephric stranding gave the highest positive predictive value (PPV) for obstruction (69% including indeterminate renograms). None of the individual CT findings showed a statistically significant correlation with scintigraphic findings. A combination of one or two positive CT findings had a PPV of only 25% for obstruction. A combination of three or four positive CT findings gave a PPV of 70% for obstruction. Our preliminary study shows that secondary CT signs of ureterolithiasis correlate poorly with the scintigraphic findings and that they do not permit evaluation of the functional status of obstructed kidneys. Even a combination of the most frequent CT findings has a low predictive value, i.e. does not allow a decision to be made as to the most suitable treatment. Therefore, renal scintigraphy should be performed in conjunction with UHCT in all patients with ureteral calculi.     

The role of renal scintigraphy and unenhanced helical computerized tomography in patients with ureterolithiasis

Unenhanced helical computerized tomography (UHCT) has recently evolved as an accurate imaging modality for determination of the presence or absence of ureterolithiasis in patients with acute flank pain. Functional renal scintigraphy is considered the gold standard for urinary tract obstruction. The objective of this study was to correlate the secondary signs of urinary obstruction on UHCT with findings of functional renal scintigraphy. UHCT was performed in 30 patients admitted to the emergency room with acute flank pain. All patients had a calcified urinary stone identified on UHCT. The location of each urinary stone was classified as ureteral or in the ureterovesical junction. The presence of secondary CT signs of ureteral obstruction was determined for each patient. After oral or intravenous hydration, a technetium-99m diethylene triamine penta-acetic acid renal scan was performed in all patients within 12 h of the CT scan. Follow-up delayed scintigraphic images were obtained at 2 h and 24 h in patients with evidence of ureteral obstruction. The sensitivity, specificity and predictive values of each possible combination of CT findings were determined by comparison with the scintigraphic results. The distal ureter was the most common location for a calculus on UHCT, followed in frequency by the ureterovesical junction, proximal ureter and mid-ureter. The renograms showed high-grade, unilateral obstruction in 12 patients, indeterminate scans in five patients and normal renograms in 13 patients. The sensitivities and specificities of individual CT findings ranged from 50% to 75% and from 8% to 69%, respectively. Perinephric stranding gave the highest positive predictive value (PPV) for obstruction (69% including indeterminate renograms). None of the individual CT findings showed a statistically significant correlation with scintigraphic findings. A combination of one or two positive CT findings had a PPV of only 25% for obstruction. A combination of three or four positive CT findings gave a PPV of 70% for obstruction. Our preliminary study shows that secondary CT signs of ureterolithiasis correlate poorly with the scintigraphic findings and that they do not permit evaluation of the functional status of obstructed kidneys. Even a combination of the most frequent CT findings has a low predictive value, i.e. does not allow a decision to be made as to the most suitable treatment. Therefore, renal scintigraphy should be performed in conjunction with UHCT in all patients with ureteral calculi. Received 21 October and in revised form 14 December 1999     

非增强螺旋CT与B超在泌尿系结石诊断中的价值比较

目的:探讨非增强螺旋CT(NCHCT)对泌尿系结石的诊断价值.方法:对50例急性腰腹部绞痛而怀疑泌尿系结石患者行NCHCT检查,并同时行泌尿系B超检查作对照,对检查结果进行临床随访,随访3天～3个月(平均0.5个月).结果:38例患者被证实为泌尿系结石(3例保守治疗后自行排出结石,28例经体外冲击波碎石后排出结石证实,7例手术取出结石),NCHCT诊断泌尿系结石38例;B超诊断泌尿系结石28例,1例假阳性.NCHCT与B超诊断泌尿系结石的敏感度分别为100%、73.7%,特异度分别为100%、91.7%,阳性预测值分别为100%、96.6%,阴性预测值分别为100%、52.4%,约登指数(正确指数)分别为1.0、0.65,NCHCT与B超相比较(u=3.23,P＜0.01),差异具有显著性意义.结论:NCHCT诊断泌尿系结石比B超具有更高的敏感度和特异度,可作为临床怀疑泌尿系结石、尤其是急性肾绞痛患者的常规检查方法.     

16层螺旋CT检查输尿管结石的应用价值

 目的 探讨16层螺旋CT在输尿管结石病例中的诊断价值.方法 应用东芝Aquilion 16层螺旋CT对142例临床拟诊输尿管病变病例进行检查分析,采用标准和低剂量扫描两组对比分析,对确诊输尿管结石病例减少造影剂用量行增强扫描.结果 两组扫描方法对输尿管结石诊断准确性无差异,低剂量组辐射剂量仅为标准组的37.12%.增强扫描适当减少造影剂用量,也能满足临床制定治疗方案前评估肾功能的要求.结论 16层螺旋CT对诊断输尿管结石有很高的准确性,适当降低扫描条件不影响结石检出率,适当减少造影剂用量不影响临床评价肾功能,但却减少了辐射剂量和患者费用,在临床中应该得到大力推广.     

Combined magnetic resonance urography and targeted helical CT in patients with renal colic: a new approach to reduce delivered dose

PURPOSE: To determine whether magnetic resonance urography (MRU), obtained before helical computed tomography (CT) in patients with acute renal colic, can help delimit the obstructed area to be subsequently examined by a targeted CT scan, thus reducing the dose of radiation. MATERIALS AND METHODS: Patients (51) with symptoms of acute renal colic underwent MRU and a total urinary tract helical CT. CT images from the 5 cm below the level of ureteral obstruction as demonstrated by MRU were selected out. Combined interpretation of MRU and selected CT images constituted protocol A. Protocol B consisted of the entire unenhanced helical CT of the urinary tract. The two protocols were compared regarding the following points: 1) sensitivity in diagnosing the presence of obstructing urinary stones, and 2) the delivered radiation dose. RESULTS: Protocol A and protocol B had, respectively, 98% and 100% sensitivity in demonstrating ureteral stone as a cause of renal colic. Estimated average dose calculated from phantom study was 0.52 mSv for protocol A and 2.83 mSv for protocol B. Therefore, the effective radiation dose was 5.4 times lower in protocol A compared to protocol B. CONCLUSION: Combined MRU and short helical CT has a high sensitivity in detecting ureteral calculi with a reduced radiation dose.