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

Temporal trends in incidence of kidney stones among children: a 25-year population based study

PURPOSE

We conducted a population based pediatric study to determine the incidence of symptomatic kidney stones during a 25-year period and to identify factors related to variation in stone incidence during this period.

MATERIALS AND METHODS

The Rochester Epidemiology Project was used to identify all patients younger than 18 years who were diagnosed with kidney stones in Olmsted County, Minnesota from 1984 to 2008. Medical records were reviewed to validate first time symptomatic stone formers with identification of age appropriate symptoms plus stone confirmation by imaging or passage. The incidence of symptomatic stones by age, gender and study period was compared. Clinical characteristics of incident stone formers were described.

RESULTS

A total of 207 children received a diagnostic code for kidney stones, of whom 84 (41%) were validated as incident stone formers. The incidence rate increased 4% per calendar year (p = 0.01) throughout the 25-year period. This finding was due to a 6% yearly increased incidence in children 12 to 17 years old (p = 0.02 for age × calendar year interaction) with an increase from 13 per 100,000 person-years between 1984 and 1990 to 36 per 100,000 person-years between 2003 and 2008. Computerized tomography identified the stone in 6% of adolescent stone formers (1 of 18) from 1984 to 1996 vs 76% (34 of 45) from 1997 to 2008. The incidence of spontaneous stone passage in adolescents did not increase significantly between these 2 periods (16 vs 18 per 100,000 person-years, p = 0.30).

CONCLUSIONS

The incidence of kidney stones increased dramatically among adolescents in the general population during a 25-year period. The exact cause of this finding remains to be determined.

Digital tomosynthesis in the detection of urolithiasis: Diagnostic performance and dosimetry compared with digital radiography with MDCT as the reference standard

OBJECTIVE

The purpose of this study was to evaluate the diagnostic performance of digital tomosynthesis in comparison with digital radiography in the detection of urinary stones with MDCT as the reference standard.

SUBJECTS AND METHODS

Fifty consecutively enrolled patients (32 men, 18 women; mean age, 51.5 years; range, 19-83 years) referred for unenhanced MDCT of the abdomen with suspicion of urinary stones also underwent digital tomosynthesis and digital radiography (anteroposterior and bladder inlet views). Images from all examinations were randomly read by three blinded radiologists. The mean effective doses for digital tomosynthesis, digital radiography, and low- and high-dose MDCT were measured on a male phantom. Free-response receiver operating characteristics and receiver operating characteristics analyses were used to compare the diagnostic performance of digital radiography with that of digital tomosynthesis.

RESULTS

Both types of analysis showed significantly better performance of tomosynthesis over digital radiography for all urinary stones (p < 0.05). No such improvement was found for ureteral stones. The gain in sensitivity with tomosynthesis was largest for stones between 2 and 5 mm in diameter. The mean effective dose was 0.5 mSv for digital radiography, 0.85 mSv for tomosynthesis, 2.5 mSv for low-dose MDCT, and 12.6 mSv for high-dose MDCT.

CONCLUSION

Use of digital tomosynthesis of the abdomen results in improved detection of urinary stones in general over digital radiography with only a slight increase in effective dose. Use of tomosynthesis, however, was not associated with major improvement in the diagnosis of ureteral stones. The technique has potential as an alternative imaging technique in the detection and follow-up of urinary stones.

Pediatric urolithiasis: clinical predictors in the emergency department

OBJECTIVE

The objective of this study was to identify factors that predict the presence of urolithiasis detected with unenhanced computed tomography (UCT) in children.

METHODS

A retrospective study of all subjects <21 years of age who presented to the emergency department at Akron Children's Hospital and underwent UCT of the abdomen between January 2002 and December 2005 was performed. Demographic, clinical, diagnostic, treatment, and disposition data were abstracted by using a standardized form. Univariate and logistic regression analyses of factors associated with urolithiasis were performed.

RESULTS

A total of 339 eligible patients were identified, with 110 cases of urolithiasis detected with UCT for 95 individual patients. The mean age of the study patients was 14.4 years; 72 patients (66%) were female. In 17 cases (15%) of urolithiasis, initial urinalysis results were negative for blood. Fifty-seven stones (51.8%) were ureteral, 26 (23.6%) were renal, and 4 (3.6%) were in the bladder. Among children who did not have a stone identified through UCT, 23 cases (10%) of potentially significant, alternative diagnoses were identified. A history of urolithiasis, a history of nausea and vomiting, the presence of flank pain on examination, and >2 red blood cells per high-power field in urine microscopy were positively associated with urolithiasis. A history of fever or dysuria and costovertebral angle tenderness on physical examination were inversely associated with urolithiasis on UCT scans.

CONCLUSIONS

UCT plays an important role in the diagnostic evaluation of children with flank pain. Approximately 15% of children with urolithiasis do not have hematuria.

Acute Ureterolithiasis: Incidence of Secondary Signs on Unenhanced Helical CT and Influence on Patient Management

AIM

The purpose of this study was to determine the incidence of secondary signs associated with ureteral stones on unenhanced helical computed tomography (CT) of patients with acute renal colic, and to correlate these with patient management and outcome.

MATERIALS AND METHODS

One hundred and ten patients with ureterolithiasis were evaluated prospectively for the secondary signs of obstruction on unenhanced helical CT. Our attention was focused primarily on the presence or absence of seven secondary signs on unenhanced helical CT, including hydronephrosis, unilateral renal enlargement, perinephric oedema, unilateral absence of the white pyramid, hydroureter, periureteral oedema and lateroconal fascial thickening.

RESULTS

Of the 110 patients, 91 (82.7%) had hydroureter, 88 (80%) had hydronephrosis, 65 (59%) had periureteric oedema and 63 (57.2%) had unilateral renal enlargement. Ninety stones passed spontaneously and 21 required intervention.

CONCLUSION

Secondary signs of urinary tract obstruction are useful and supportive findings in interpretation of the CT examination. In our experience, the most reliable signs indicating ureteral obstruction are hydroureter, hydronephrosis, periureteral oedema and unilateral renal enlargement, respectively. In addition, stones larger than 6 mm, located within the proximal two thirds of the ureter, and seen associated with five or more the secondary signs of obstruction, are more likely to require endoscopic removal and/or lithotripsy.

Evaluation of the patient with flank pain and possible ureteral calculus

Flank pain due to urolithiasis is a common problem in patients presenting to emergency departments. Radiology plays a vital role in the work-up of these patients. Many modalities can be used, including ultrasonography, nuclear medicine, and the traditionally used techniques of intravenous urography and conventional radiography. The development of nonenhanced computed tomography (CT) (single- or multi-detector row helical) has provided a means to enable detection and characterization of urolithiasis with unprecedented sensitivity, specificity, and accuracy while yielding important information for treatment planning, including the size and location of calculi. This technique can also help detect causes for flank pain outside the genitourinary tract. However, close attention must be paid to all aspects of the CT study to prevent misdiagnoses.

Renal colic: new concepts related to pathophysiology, diagnosis and treatment

PURPOSE OF REVIEW

To give new insights into the pathophysiology, diagnosis and treatment of acute renal colic caused by a stone disease.

RECENT FINDINGS

Traditional intravenous pyelography is no longer the primary method of investigation in patients with renal colic. If the patient has a history of previous attacks of renal colic and stone disease the recommended diagnostic approach is to start with plain abdominal radiography and ultrasonography together with Doppler ultrasonography. Noncontrast computerized tomography is reserved for unsolved problems. If the patient has no history of stone disease or has atypical clinical presentation it is better to start with noncontrast computerized tomography. Intravenous pyelography is indispensable if an endoscopic or open intervention is required. Magnetic resonance imaging is a promising method of investigation, particularly in pregnant women. Effective pain relief is achieved by the use of opioids, nonsteroidal antiinflammatory drugs or desmopressin.

SUMMARY

The diagnostic approach to renal colic has recently been changed due to the introduction of new, noninvasive radiologic procedures such as Doppler ultrasonography, noncontrast computerized tomography and magnetic resonance imaging.