Non-contrast spiral CT for patients with suspected renal colic

CT of appendicoliths in adult appendicitis: clinical significance and characteristics of overlooked cases

OBJECTIVES

Accurate computed tomography (CT) identification of appendicoliths in adults with acute appendicitis is crucial as it may preclude nonoperative management due to high risk of failure and complications. This investigation aimed to identify the significance of appendicoliths in acute appendicitis and to evaluate the performance of portovenous-phase (PVP) CT and the consequences of overlooked appendicoliths.

METHODS

CT examinations of 324 consecutive patients (mean age 51.9 years, 112 men) with pathologically confirmed acute appendicitis were retrospectively included. Two radiologists independently reviewed the images, and disagreement was resolved by a consensus.

RESULTS

Appendicoliths were identified in 134/324 patients, of which 75 had complicated appendicitis. Among 190 patients without appendicoliths, 52 had complicated appendicitis. An appendicolith was independently associated with complicated appendicitis (adjusted odds ratio 2.289; 95% CI: 1.343-3.902; p = 0.002). The larger minimum diameter was significantly associated with complication. The 4.5-/6.0-mm cutoffs for minimum and maximum diameters of appendicoliths demonstrated 82.7%/85.3% sensitivity and 35.6%/33.9% specificity in predicting complications. The PVP alone had 82.1-88.1% sensitivity, respectively per patient and per appendicolith, and a 100% specificity in the detection of appendicoliths, as compared with combined noncontrast and PVP. PVP overlooked 28/237 appendicoliths (11.8%) corresponding to 24/134 patients (17.9%). Of the 24 patients with overlooked appendicoliths, 16 had complicated appendicitis but 14 were correctly categorized by findings other than appendicoliths. In total, 2/127 patients (1.6%) with complicated appendicitis were misdiagnosed as having uncomplicated appendicitis.

CONCLUSIONS

Appendicoliths in acute appendicitis were strongly associated with complications. While PVP overlooked some appendicoliths, only 1.6% of complicated appendicitis were misclassified when considering other CT findings.

CLINICAL RELEVANCE STATEMENT

This study found a strong association between appendicoliths and complications. Its presence may preclude conservative management. Although portovenous-phase CT overlooked some appendicoliths, the combination with other CT findings allowed correct classification in a vast majority of cases.

KEY POINTS

• Accurate identification of appendicoliths is crucial for nonoperative management decisions in adult acute appendicitis. • Appendicoliths are strongly associated with complications in adult acute appendicitis. • Portovenous-phase CT overlooked some appendicoliths, but only a small percentage of patients with complicated appendicitis were misclassified when considering other CT findings.

Role of computed tomography morphodensitometry in predicting the outcome of shock wave lithotripsy

Objectives:

The objective of this study was to predict the outcome of shock wave lithotripsy (SWL) on the basis of computed tomography (CT) morphodensitometry for ureteral and renal stones. We also assessed the possibility that Hounsfield unit (HU) values and the location of the stones could be used to predict the outcome of SWL.

Material and methods:

A prospective study was performed to measure stone size, location, composition, surface area, surface volume, stone burden, the skin-to-stone distance and the HU for solitary renal and ureteral stones by non-contrast CT studies (NCCT) from August 2013 to September 2015. Success of SWL was defined as: (1) being stone-free or (2) residual stone fragments < 4 mm by radiography/NCCT.

Results:

Of the 100 assessed patients, 68 patients (68%) were stone-free, 12 (12%) had residual stone fragments < 4 mm (clinically insignificant residual fragments) and 20 (20%) had residual stone fragments ≥ 4 mm/ancillary procedures. Multivariate analysis revealed that stone location and mean HU were significant predictors of SWL success. Receiver operating characteristic curves defined cut-off values for predicting treatment outcome. Treatment success rates were significantly higher for stones < 800 HU than with stones > 800 HU ( p = 0.160).

Conclusion:

Evaluation of stone HU values and stone location prior to SWL can predict treatment outcome and aid in the development of treatment strategies.

Level of evidence

2 & 4

Investigating the clinical significance of twinkling artifacts in patients with urolithiasis smaller than 5 mm

PURPOSE

Our aim was to evaluate the effectiveness of twinkling artifacts (TA) in detecting calculi <5 mm in diameter in patients with renal colic pain who had undergone urinary grayscale ultrasonography (US) and computed tomography (CT) imaging assays.

MATERIALS AND METHODS

In this retrospective study, a total of 76 calculi <5 mm detected in 60 patients were evaluated. Whole data were established using an ultrasound (US) probe at frequencies 1.5-4.5 MHz and noncontrast CT. In US, echogenicity and posterior-shadow (PS) parameters were evaluated and compared with color-Doppler ultrasonography (CDUS) and CT signs.

RESULTS

The mean size of measured calculi was 3.9 ± 0.8 mm (range 2-5 mm). The calculus localization rates detected by CT imaging were as follows: kidneys (n = 61, 80.3 %), proximal ureter (n = 4, 5.3 %), middle ureter (n = 3, 3.9 %) and distal ureter (n = 8, 10.5 %). CT detected the calculus in all 76 cases. There was a statistically significant difference in US-CT and CDUS-CT comparisons (p < 0.001 and p = 0.023, respectively); however, no difference was found when comparing both US methods with CT (p = 0.083).

CONCLUSIONS

TA can be regarded as a significant marker of urolithiasis, and co-operative usage of Doppler and grayscale methods can yield satisfactory results comparable with CT.

Emergency department imaging protocol for suspected acute renal colic: re-evaluating our service

OBJECTIVES

The objective of our study is to determine the positive rate for urolithiasis in male and female patients, and evaluate whether there has been any change at our institution in the use and outcome of unenhanced multidetector CT (CT KUB) performed in the emergency department (ER) for patients presenting with suspected acute renal colic.

METHODS

A retrospective review of all 1357 consecutive cases between August 2007 and August 2009 admitted to the ER and investigated with CT KUB.

RESULTS

The positive rate for urolithiasis was 47.5% and the rate of other significant findings was 10%. Female patients had a significantly lower positive rate than male patients (26.8% vs 61.6%, p<0.001). Urological intervention was required in 37% and these patients had a larger average stone size. In young female patients with a significantly sized ureteric calculus (>4 mm), the presence of hydronephrosis vs no hydronephrosis was 83% vs 17%, respectively. Among them, only three patients required ureteroscopy for stone removal.

CONCLUSION

Contrary to other studies there has been no "indication creep" in the use of CT KUB at our institution. However, the young female patient presenting with suspected urolithiasis presents a particular diagnostic problem, and the significant percentage of negative examinations in females implies that an improvement in current practice is needed. The indiscriminate use of CT KUB in all female patients with flank pain should be avoided, and it is suggested that they should be initially evaluated with ultrasound to detect the presence of hydronephrosis.

Analyzing the effect of distance from skin to stone by computed tomography scan on the extracorporeal shock wave lithotripsy stone-free rate of renal stones

Purpose

To determine whether the distance from skin to stone, as measured by computed tomography (CT) scans, could affect the stone-free rate achieved via extracorporeal shock wave lithotripsy (ESWL) in renal stone patients.

Materials and Methods

We retrospectively reviewed the records 573 patients who had undergone ESWL at our institution between January 2006 and January 2010 for urinary stones sized from about 5 mm to 20 mm and who had no evidence of stone movement. We excluded patients with ureteral catheters and percutaneous nephrostomy patients; ultimately, only 43 patients fulfilled our inclusion criteria. We classified the success group as those patients whose stones had disappeared on a CT scan or simple X-ray within 6 weeks after ESWL and the failure group as those patients in whom residual stone fragments remained on a CT scan or simple X-ray after 6 weeks. We analyzed the differences between the two groups in age, sex, size of stone, skin-to-stone distance (SSD), stone location, density (Hounsfield unit: HU), voltage (kV), and the number of shocks delivered.

Results

The success group included 33 patients and the failure group included 10. In the univariate and multivariate analysis, age, sex, size of stone, stone location, HU, kV and the number of shocks delivered did not differ significantly between the two groups. Only SSD was a factor influencing success: the success group clearly had a shorter SSD (78.25±12.15 mm) than did the failure group (92.03±14.51 mm). The results of the multivariate logistic regression analysis showed SSD to be the only significant independent predictor of the ESWL stone-free rate.

Conclusions

SSD can be readily measured by CT scan; the ESWL stone-free rate was inversely proportional to SSD in renal stone patients. SSD may therefore be a useful clinical predictive factor of the success of ESWL on renal stones.

Evaluation of possible predictive variables for the outcome of shock wave lithotripsy of renal stones

Purpose

The aim of this study was to evaluate possible predictive variables for the outcome of shock wave lithotripsy (SWL) of renal stones in a single center.

Materials and Methods

Between March 2008 and March 2010, a retrospective review was performed of 115 patients who underwent SWL for solitary renal stones. The patients' characteristics and stone size, location, skin-to-stone distance (SSD), and Hounsfield units (HU) of stone were reviewed. The impact of the possible predictors on the disintegration of the stones was evaluated by logistic regression analysis. Receiver operator characteristic (ROC) curves were generated to compare the predictive powers of the variables.

Results

Seventy-nine patients (68.7%) had successful outcomes, whereas 36 patients (31.3%) had residual stones. Significant differences were found in the mean size and mean HU of the stones (size: 8.34±3.58 mm vs. 13.57±5.41 mm, p<0.001; HU: 675.29±254.34 vs. 1,075.00±290.41, p<0.001). In the unadjusted model, age, stone size, and stone density were significant predictors. In the reduced model, stone density and size were significant predictors for the outcome of SWL. The area under the ROC curve (AUC) was significantly higher for stone density and size than for the other parameters, but the AUC between stone density and size did not differ significantly (stone density: 0.874, stone size: 0.827, p=0.388).

Conclusions

Stone density and size were significant predictors of the outcome of SWL for renal stones less than 2.0 cm in diameter. We should consider HU and stone size when making decisions on the treatment of renal stones.

Evaluation of patients with suspected ureteral calculi using sonography as an initial diagnostic tool: how can we improve diagnostic accuracy?

OBJECTIVE

The purpose of this study was to evaluate the usefulness of sonography as an initial diagnostic tool in patients with suspected ureterolithiasis.

METHODS

We performed a prospective study of 318 patients with suspected ureteral stones over a 14-month period. All patients underwent sonography after fasting for 8 hours and bladder filling. If no cause of the flank pain was found by sonography, computed tomography or intravenous urography was performed immediately to confirm the absence of ureteral stones.

RESULTS

We found urolithiasis with sonography in 291 of 296 patients with confirmed urolithiasis. The 5 remaining cases were identified after non-contrast-enhanced computed tomography (n = 3), intravenous urography (n = 1), or the passage of a stone (n = 1, pregnant patient). We detected 313 calculi in the 291 patients with sonography as follows: 307 ureteral calculi in 285 patients, 5 urinary bladder calculi that were probably passed from the ureter in 5 patients, and 1 urethral calculus. The locations of the 313 calculi in the 291 patients with a sonographic diagnosis were as follows: 21 were in the ureteropelvic junction, 96 in the proximal half of the ureter, 69 in the distal half of the ureter, 121 in the ureterovesical junction, 5 in the urinary bladder, and 1 in the urethra. Hydronephrosis was seen in 200 of the 291 patients with calculi identified by sonography (68.7%). Twinkling artifacts helped confirm the presence of tiny calculi in 184 of the 214 calculi (86%).

CONCLUSIONS

Sonography can be used as an initial diagnostic tool in patients with suspected ureterolithiasis.

Characterization of human renal stones with MDCT: advantage of dual energy and limitations due to respiratory motion

OBJECTIVE

Our aim was to determine, using CT attenuation values, the chemical composition of 241 human renal stones placed in a jelly phantom and to analyze the influence of respiratory motion on the classification.

MATERIALS AND METHODS

The stones were placed in a jelly simulating the X-ray attenuation of the kidneys. A dynamic platform was used to apply to the phantom free-breathing motion (sinusoidal motion in z-axis) and motion due to lack of maintenance of a breath-hold (5 mm x s(-1) in z-axis). Determination of the chemical composition was performed with mean CT attenuation values obtained at 80 and 120 kV and with dual-energy CT attenuation values.

RESULTS

Two hundred forty-one human urinary stones were classified into six groups: uric acid, cystine, struvite, weddellite (calcium oxalate dihydrate), whewellite (calcium oxalate monohydrate), and brushite. With no motion, the use of dual energy enabled differentiation of all of the types of stones with statistically significant differences. Uric acid (-20 +/- 22 H), cystine (106 +/- 19 H), struvite (271 +/- 16 H), weddellite (323 +/- 5 H), brushite (415 +/- 30 H), and whewellite (510 +/- 17 H) were identified as distinct groups. Motion-induced mean CT attenuation values were significantly different from those obtained with no motion. With motion, dual-energy CT attenuation values did not allow differentiation of all stone types.

CONCLUSION

Dual-energy CT attenuation values can be used to predict the chemical composition of stones in vitro. However, when slight motion is applied to renal stones during image acquisition, the values become significantly different from those obtained with no motion. Consequently, confusion arises in differentiating stone types. A perfect breath-hold has to be performed for in vivo use of attenuation value to discern stone type.

Radiation Dose Associated with Unenhanced CT for Suspected Renal Colic: Impact of Repetitive Studies

OBJECTIVE

The purpose of our study was to assess the dose of ionizing radiation delivered through the use of unenhanced CT for suspected renal colic by determining the incidence of repeated unenhanced CT examinations and the cumulative radiation dose delivered.

MATERIALS AND METHODS

All unenhanced CT examinations for suspected renal colic performed at our institution over a 6-year period were included, and patient age, sex, and multiplicity of examinations were determined. For the adult patient, this protocol prescribes a fixed tube current of 200 mA, 140 kVp, and a nominal slice width of 5 mm. The dose-length product (DLP) was estimated for 15 randomly chosen single-detector CT (SDCT) and MDCT adult flank pain examinations using manufacturer's software. The mean DLPs for SDCT and MDCT were computed and converted to effective doses. Total effective doses were calculated for patients who underwent more than three examinations, and values were compared with established standards.

RESULTS

A total of 5,564 examinations were performed on 4,562 patients. Of these patients, 2,795 (61%) were women (mean age, 45.5 +/- 16.2 [SD] years) and 1,731 (38%) were men (mean age, 44.7 +/- 16.4 years), with 144 patients (3%) of pediatric age. The mean effective doses for a single study were 6.5 mSv for SDCT and 8.5 mSv for MDCT. A subset of 176 patients (4%) had three or more examinations, with estimated effective doses ranging from 19.5 to 153.7 mSv. All patients with multiple examinations had a known history of nephrolithiasis.

CONCLUSION

Patients with a history of nephrolithiasis and flank pain are at increased risk for serial CT with potentially high cumulative effective doses.

Imagerie de la lithiase urinaire : « Trois en un »

Urinary lithiasis is very common among the general population, with a high prevalence level. In rich countries it is mainly located inside the upper urinary tract. Helical CToperated with newer devices is the most accurate modality to provide all needed information: diagnosis of stone without contrast medium injection, morphology (size, number) and localization, diagnosis of urinary obstruction, urinary tract aspect and all kind of differential diagnosis in emergency. It must be used during follow up to diagnose residual fragments. Multiplanar reconstructions are essential for the clinicians; but diagnosis is interpreted by scrolling axial views with dynamic analysis on computer screen. Low-dose helical CT is today available. Helical CT provides an "all-in-one" examination. It should soon replace combined plain film-ultrasonography performed in an emergency context of renal colic and intravenous urography for pre- and post-treatment assessments.

Unexplained renal colic: What is the utility of IV contrast?

PURPOSE

The aim of this study was to evaluate the benefit of intravenous (IV) contrast in patients with suspected renal colic and unremarkable unenhanced MDCT.

MATERIALS AND METHODS

One thousand two hundred and four patients with suspected ureterolithiasis were evaluated with unenhanced MDCT. Seven hundred and eight patients that had additional imaging following IV contrast were our study group.

RESULTS

Of the patients, 9.4% (67/708) had abnormalities seen only on contrast-enhanced exams. In 53.1% (376/708) of the patients, no additional finding was identified after IV contrast.

CONCLUSION

IV contrast in patients with renal colic is rarely helpful.

Predictions of outcomes of renal stones after extracorporeal shock wave lithotripsy from stone characteristics determined by unenhanced helical computed tomography: a multivariate analysis

The aim of our study is to analyze the relationships between the characteristics of renal stones determined by unenhanced helical computed tomography (UHCT) and their outcomes after extracorporeal shock wave lithotripsy (ESWL) as well as to predict ESWL outcomes of renal stones by their UHCT characteristics with the use of multivariate analysis. During a 7-month period, 80 adult patients with renal stones underwent ESWL as well as UHCT both before and 3 months after ESWL. Of the 80 patients, 42 patients were classified as ESWL successes and 38 as ESWL failures based on their post-ESWL UHCT findings. For pre-ESWL UHCT, a stone number of more than 2 (P=0.0236), a maximal stone size of greater than 12 mm (P<0.0001), a stone burden of more than 700 mm3 (P<0.0001), a maximal stone density of more than 900 HU (P=0.0008) and nonround/oval stones (P=0.0007) were associated with ESWL failure outcomes. Multivariate analysis demonstrated that a stone burden of more than 700 mm3 (P=0.0003), the presence of nonround/oval stones (P=0.0072) and a maximal stone density of more than 900 HU (P=0.0430) were statistically significant predictors of a failure outcome for ESWL. Thus, the analysis of stone characteristics of renal stones by UHCT is helpful in selecting appropriate patients undergoing ESWL for favorable outcomes and reduces the overall costs of the treatment of renal stones.

Unenhanced helical computed tomography vs intravenous urography in patients with acute flank pain: accuracy and economic impact in a randomized prospective trial

Unenhanced helical computed tomography (UHCT) has evolved into a well-accepted alternative to intravenous urography (IVU) in patients with acute flank pain and suspected ureterolithiasis. The purpose of our randomized prospective study was to analyse the diagnostic accuracy of UHCT vs IVU in the normal clinical setting with special interest on economic impact, applied radiation dose and time savings in patient management. A total of 122 consecutive patients with acute flank pain suggestive of urolithiasis were randomized for UHCT ( n=59) or IVU ( n=63). Patient management (time, contrast media), costs and radiation dose were analysed. The films were independently interpreted by four radiologists, unaware of previous findings, clinical history and clinical outcome. Alternative diagnoses if present were assessed. Direct costs of UHCT and IVU are nearly identical (310/309 Euro). Indirect costs are much lower for UHCT because it saves examination time and when performed immediately initial abdominal plain film (KUB) and sonography are not necessary. Time delay between access to the emergency room and start of the imaging procedure was 32 h 7 min for UHCT and 36 h 55 min for IVU. The UHCT took an average in-room time of 23 min vs 1 h 21 min for IVU. Mild to moderate adverse reactions for contrast material were seen in 3 (5%) patients. The UHCT was safe, as no contrast material was needed. The mean applied radiation dose was 3.3 mSv for IVU and 6.5 mSv for UHCT. Alternative diagnoses were identified in 4 (7%) UHCT patients and 3 (5%) IVU patients. Sensitivity and specificity of UHCT and IVU was 94.1 and 94.2%, and 85.2 and 90.4%, respectively. In patients with suspected renal colic KUB and US may be the least expensive and most easily accessable modalities; however, if needed and available, UHCT can be considered a better alternative than IVU because it has a higher diagnostic accuracy and a better economic impact since it is more effective, faster, less expensive and less risky than IVU. In addition, it also has the capability of detecting various additional renal and extrarenal pathologies.

Suspected ureteral colic: primary helical CT versus selective helical CT after unenhanced radiography and sonography

OBJECTIVE

The purpose of this study was to compare the accuracy of unenhanced helical CT with combined sonography and unenhanced radiography in patients with acute flank pain suggestive of ureteral colic.

SUBJECTS AND METHODS

From January 1997 to December 1999, 181 consecutive patients with acute flank pain underwent unenhanced radiography, sonography, and unenhanced helical CT (protocol A). From January 2000 to December 2000, 96 consecutive patients arriving at the emergency department with acute flank pain were alternately submitted either to primary unenhanced helical CT (protocol B, 48 patients) or to unenhanced radiography and sonography with the addition of helical CT in unclear cases (protocol C, 48 patients).

RESULTS

When compared with the diagnostic accuracy for ureterolithiasis of the combined sonography and radiography in the same group of subjects (protocol A), CT had a greater sensitivity (92% vs 77%), negative predictive value (87% vs 68%), and overall accuracy (94% vs 83%). Among patients who underwent primary CT (protocol B), we found three false-negatives (all with spontaneous stone passage) and no false-positives. Among patients initially examined with unenhanced radiography and sonography (protocol C), we found one false-positive (leading to patient admission and needless repeated radiographic and sonographic studies) and six false-negatives (all followed by an uncomplicated course and spontaneous passage); CT depicted four of these stones but did not result in change in treatment. Fourteen percent of the patients in protocol C required invasive treatment, but combined sonography and radiography showed stones and hydronephrosis in all these patients.

CONCLUSION

Unenhanced CT was the most accurate modality for determining the presence of ureterolithiasis. The combination of abdominal radiography and sonography, however, yielded comparable results with no clinically important misdiagnoses and thus can be used as an alternative when CT resources are limited.

Unenhanced spiral CT for the assessment of renal colic. How does limiting the referral base affect the discovery of additional findings not related to urinary tract calculi?

The value of unenhanced spiral CT (UESCT) for investigating acute flank pain suggestive of urinary tract calculi is increasingly appreciated in the last few years. Recent studies have identified the advantages of UESCT in recognizing alternative findings within or outside the urinary tract. We sought to determine how narrowing the referral base for the UESCT would affect the discovery of potentially significant alternative findings in patients with acute flank pain suggestive of renal colic. Between January 1999 and December 1999, 425 patients, 271 (63.8%) men and 154 (36.2%) women who were 1-90 years old (mean 45.7 years old) with acute flank pain were studied with UESCT. CT studies were solely ordered by urologists, and only patients with intractable renal colic or patients that returned more than once to the emergency room with the complaint of acute flank pain were studied. A calculus within the ureter was diagnostic of an obstructive stone. Any other abnormality within the abdomen and pelvis was reported. A ureteral calculus was detected on 251 (59%) CT scans. Nineteen (4.5%) CT scans were consistent with recent excretion of a stone. In 112 (26.3%) CT scans, the cause for the patient's acute flank pain could not be explained. Forty-three (10.1%) alternative significant diagnoses that explain the patient's complaints were found. Nineteen (44%) were findings related to the urinary tract, and 24 (56%) were not related to the urinary tract. Ninety-seven (22.3%) additional findings not significant to the patient's current complaint were also reported. Even when narrowing the indications for the UESCT, about 10% of significant alternative findings to urinary stones were encountered. The variety of diagnoses found unexpectedly on the UESCT that alter a patient's management demonstrates the pivotal role of UESCT in triaging these patients rapidly towards optimal therapy. The UESCT can be used as a useful screening tool, sometimes revealing the exact pathology and sometimes directing the radiologist to the modality by which to continue.

Emergency department time for evaluation of patients discharged with a diagnosis of renal colic: unenhanced helical computed tomography versus intravenous urography

The objective of this study was to determine whether patients discharged from the Emergency Department (ED) with a proven diagnosis of renal colic require less total evaluation and treatment time if unenhanced helical computed tomography (CT) rather than intravenous urography (IVU) was the diagnostic imaging study used. A retrospective review was undertaken of the medical records of 98 consecutive patients with a final diagnosis of urolithiasis or renal colic evaluated with an unenhanced helical CT scan or an IVU between January 1, 1999, and December 31, 1999. All patients were managed by Emergency Physicians and discharged from the ED. The time the patient was brought to the treatment area, the time the imaging study was ordered, and the time the patient was discharged were recorded. There were 75 patients evaluated with CT scan and 23 patients with an IVU. Patients who underwent unenhanced helical CT scan were in the ED for a mean time of 291 min [95% confidence interval (CI) 266-316] and those who had an IVU were in the ED for an average of 410 min (95% CI 340-481). Use of unenhanced helical CT scan was associated with less total time in the ED compared to IVU for patients with renal colic by a significant mean of 119 min. It is concluded that ED evaluation and treatment time of patients ultimately discharged with a proven diagnosis of renal colic is significantly less when evaluated with unenhanced helical CT scan compared to IVU.

Unenhanced helical computed tomography for the evaluation of suspected renal colic in the adolescent population: a pilot study

OBJECTIVES

Unenhanced helical computed tomography (UHCT) is rapidly becoming the preferred imaging modality for the evaluation of suspected renal colic in the adult population; however, a series addressing its use in the adolescent population has not been previously published. We assessed the utility of UHCT in the evaluation of suspected renal colic in this age group.

METHODS

Seventeen patients between the ages of 8 and 18 years (mean 14.7) presented to the emergency departments of four hospitals for evaluation of suspected renal colic. All patients were studied with UHCT immediately after initial evaluation. A single helical acquisition was performed from the midpoint of T-12 vertebra to a point below the bladder base, using a slice thickness of 5 mm. Films were reviewed by the institutional radiologist, and results were quantified.

RESULTS

Of the 17 patients who underwent evaluation, no abnormality was detected in 8 patients. A stone was localized in 7 patients who were then appropriately treated. One patient had no stone visualized, but secondary signs suggested a recently passed stone. The final patient had no stone; however, marked bilateral hydroureteronephrosis was noted that led to further evaluation. A single phlebolith was seen in only 1 patient, and no study was nondiagnostic.

CONCLUSIONS

UHCT is a safe, rapidly performed test for the evaluation of suspected renal colic in adolescents. It is highly sensitive and specific for renal and ureteral calculi and, more importantly, allows visualization of alternate pathology. In addition, secondary signs are seen that aid in determining obstruction and are helpful if no stone is visualized. Phleboliths, which can simulate a stone, are rarely seen in adolescence. We believe UHCT allows for rapid triage and localization of stones and should be recommended as the primary diagnostic modality for the evaluation of adolescents with suspected renal colic.

CT for the evaluation of flank pain

Unenhanced helical CT allows rapid and accurate determination of whether a stone is present anywhere in the urinary tract. There is a learning curve for both radiologist and urologist, but a number of signs are highly predictive of stone. Helical CT scans should always be accompanied by a "scoutogram" to convey an idea of what the stone might look like. The scan requires no contrast medium and takes only 5 to 10 minutes of imaging time, making it cost effective. It behooves both urologists and radiologists to familiarize themselves with the techniques for reading these scans.

Alternative or additional diagnoses on unenhanced helical computed tomography for suspected renal colic: experience with 1000 consecutive examinations

OBJECTIVES

To determine the incidence and spectrum of significant alternative or additional diagnoses established or suggested on unenhanced helical computed tomography (CT) in a large series of patients with suspected renal colic.

METHODS

One thousand consecutive unenhanced helical CT examinations were performed for suspected renal colic. All official CT reports were retrospectively reviewed, which was followed by review of all available relevant follow-up radiology reports. A selected image and chart review was also performed.

RESULTS

Ureteral calculi were identified on 557 examinations, findings consistent with a recently passed stone were discovered on 67 examinations, and 275 CT examinations were unremarkable. An alternative or additional diagnosis was established or suggested on 101 examinations, including in 26 patients with concurrent ureteral calculi. There were 62 genitourinary and 39 nongenitourinary tract diagnoses. Eighty-seven of the diagnoses could be confirmed on retrospective image review combined with patient follow-up. There were two false-positive diagnoses for significant, alternative pathologic findings.

CONCLUSIONS

A wide spectrum of significant, alternative, and additional genitourinary and nongenitourinary diagnoses can be reliably established or suggested on unenhanced helical CT performed for suspected renal colic. These abnormalities were identified in 10% of cases in this series of 1000 consecutive CT examinations.

Use of magnetic resonance urography

OBJECTIVES

Magnetic resonance urography (MRU) is a new technique that uses heavily weighted T2 coronal images with fat suppression pulse. Urine appears white on MRU, resembling an intravenous urogram (IVU). Contrast agents are not necessary. This study describes the use of MRU in the diagnosis and treatment of patients with hematuria.

METHODS

One hundred six patients with microscopic or gross hematuria and 6 normal volunteers underwent MRU between 1992 and 1995. A modified, heavily weighted T2 technique with intravenous administration of furosemide and ureteral compression was used. Thirty-two patients had other imaging techniques as well for comparison.

RESULTS

MRU provided high-resolution images in almost all cases; 73 (69%) had a normal MRU. Significant findings in the 33 patients with abnormalities included renal cysts in 17 (51%), renal cell carcinoma in 6 (18%), transitional cell carcinoma in 5 (15%), ureteropelvic junction obstruction in 3 (9%), and stones causing obstruction in 6 (18%). Five patients with renal failure also had good visualization of the entire urinary tract. MRU was comparable to other imaging modalities except in identifying nonobstructing calculi.

CONCLUSIONS

MRU provides an alternative to conventional imaging of the urinary tract, especially in those patients who have contraindications to ionizing radiation and contrast agents. Improvements in resolution, technique, and cost have to be addressed before it can be used regularly in urologic practice.